Patent Publication Number: US-2023148831-A1

Title: Dishwasher

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of Korean Patent Application Nos. 10-2021-0159662, filed on Nov. 18, 2021, and 10-2021-0159664, filed on Nov. 18, 2021, and 10-2022-0028084, filed on Mar. 4, 2022, and 10-2022-0028086, filed on Mar. 4, 2022, the disclosures of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present application relates to a dishwasher, and in particular, a dishwasher that can prevent an airflow guide from clattering effectively without an additional member and support the airflow guide reliably, allow a lower end surface of a fastening nut to be exposed to a wash space, prevent wash water from remaining between the fastening nut and a tub, and prevent the tub and a dry air supply hole from corroding. 
     BACKGROUND 
     Dishwashers spray wash water such as water to a wash target such as cooking vessels, cooking tools and the like accommodated in them to wash the wash target. At this time, wash water used for washing a wash target can include detergent. 
     In some cases, dishwashers are comprised of a tub forming a wash space, a storage part accommodating wash targets in the tub, a spray arm spraying wash water to the storage part, and a sump storing water and supplying wash water to the spray arm. 
     Dishwashers help to reduce time and efforts taken to clean wash targets such as cooking vessels and the like after meals, thereby ensuring improvement in user convenience. 
     In some cases, dishwashers perform a washing process of washing wash targets, a rinsing process of rinsing the wash targets, and a drying process of drying the wash targets after the washing and rinsing processes. 
     In recent years, the drying stage of dishwashers involves supplying high-temperature dry air into the tub to reduce a drying period and promote the effect of sterilizing wash targets. 
     As a related art, a dishwasher provided with a hot air supply device that generates and supplies high-temperature dry air after the washing and rinsing stages is disclosed in DE Patent Publication No. 102015212869 (document 001). 
     In the dishwasher according to document 001, a dry air spray part for spraying dry air generated through the hot air supply device, which is disposed under of a tub, into the tub is disposed in the tub. 
     The dry air spray part is coupled to a hot air supply tube that extends in a way that penetrates the tub. 
     At this time, the dry air spray part can be coupled to the hot air supply tube simply by being press-fitted to the hot air supply tube, thereby ensuring a simple assembly or fastening. 
     However, according to document 001, without a very tight manufacturing tolerance for the dry air spray part and the hot air supply tube, clattering can occur due to a relative displacement or a relative movement that is caused by an up-down gap. 
     Additionally, according to document 001, without rigidity of a predetermined level or above in a connecting portion between the dry air spray part and the hot air supply tube, the dry air spray part can easily escape upward and downward from its right position as quite a strong impact is applied. 
     Further, according to document 001, without rigidity of a predetermined level or above in the connecting portion between the dry air spray part and the hot air supply tube, the connecting portion between the dry air spray part and the hot air supply tube can be readily broken as quite a strong impact is applied. 
     Further, the dry air spray part according to document 001 extends vertically through an open hole that is formed in a way that penetrates the lower surface of the tub. 
     Accordingly, a connecting portion between the open hole and the dry air spray part is exposed to high-temperature wash water, and when wash water remains in the connecting portion after the washing stage and the rinsing stage, the open hole and the lower surface side of the tub are highly likely to corrode. 
     Further, it is highly likely that wash water and food included in the wash water remaining in the connection portion between the open hole and the dry air spray part can cause the reproduction of germs and generate a bad smell. 
     Further, since the dry air spray part according to document 001 is not fixed to the hot air supply tube in a rotation direction, the dry air spray part is likely to collide with the edge of the tub depending on the operation state of the dishwasher. 
     Accordingly, the dry air spray part can be broken or generate noise due to its collision with the edge of the tub. 
     Further, the dry air spray part according to document 001 has an outer shape corresponding to the shape of the edge of the tub. Accordingly, the outer shape of the dry air spray part can be big. 
     As the dry air spray part having a big outer shape is disposed in the wash space, an available wash space of the tub can be reduced substantially, and interference with other components including a lower spray arm and a lower rack, disposed in the tub, can occur. Further, since the dry air spray part needs to be disposed closet to the tub, food and the like is highly likely to be fixed between the dry air spray part and the inner surface of the tub. 
     PRIOR ART DOCUMENT 
     [Patent Document] 
     (Document 001) DE Patent Publication No. 102015212869. 
     SUMMARY 
     Technical Problems 
     The first objective of the present disclosure is to provide a dishwasher in which a means of limiting a relative displacement or a relative movement is provided integrally between an airflow guide and a connection duct part to which the airflow guide connects, such that the airflow guide is reliably supported and effectively prevented from clattering without an additional member. 
     The second objective of the present disclosure is to provide a dishwasher in which a screw part integrally provided at a connection duct part is supported at at least three different spots at a time of a relative downward displacement or a relative downward movement of the airflow guide, such that even if quite a strong external force is applied, the airflow guide is effectively prevented from escaping from its right position. 
     The third objective of the present disclosure is to provide a dishwasher in which a screw part integrally provided at a connection duct part is supported at at least three different spots at a time of a relative downward displacement or a relative downward movement of the airflow guide, such that the airflow guide and the connection duct part are effectively prevented from being broken since external force is divided and transferred to the connection duct part through the three different spots. 
     The fourth objective of the present disclosure is to provide a dishwasher in which a connection duct part, extending in a way that penetrates a dry air supply hole, is fixed in the state of being spaced from the lower surface of a fastening nut fixed to a tub, such that the lower end surface of the fastening nut is exposed to a wash space, wash water is prevented from remaining between the fastening nut and the tub, and the tub and the dry air supply hole are prevented from corroding. 
     The fifth objective of the present disclosure is to provide a dishwasher in which wash water is prevented from remaining between a fastening nut and a tub, to effectively prevent the reproduction of germs and the generation of a bad smell between the fastening nut and the tub. 
     The sixth objective of the present disclosure is to provide a dishwasher in which a release prevention part is integrally provided to prevent an airflow guide from rotating and escaping in the state of being coupled and fixed, thereby providing dry air reliably in a predetermine direction regardless of the operation state of the airflow guide. 
     The seventh objective of the present disclosure is to provide a dishwasher in which an airflow guide is sufficiently spaced from the edge of a tub, such that the damage and noise of the airflow guide, caused by its collision with the edge of the tub, are minimized. 
     The eighth objective of the present disclosure is to provide a dishwasher in which an airflow guide is coupled to a dry air supply part, based on a two-stage coupling manipulation, to readily implement the setting of the right position of the airflow guide with respect to the dry air supply part and effectively prevent the misassembly of the airflow guide with respect to the dry air supply part. 
     Aspects according to the present disclosure are not limited to the above ones, and other aspects and advantages that are not mentioned above can be clearly understood from the following description and can be more clearly understood from the embodiments set forth herein. Additionally, the aspects and advantages in the present disclosure can be realized via means and combinations thereof that are described in the appended claims. 
     Technical Solutions 
     A dishwasher according to the present disclosure comprises a tub accommodating a wash target and having a wash space a front surface of which is open; a dry air supply part being disposed at a lower portion side of the tub and generating dry air for drying the wash target; an airflow guide diverting a flow direction of the dry air supplied by the dry air supply part and supplying the dry air to the wash space, wherein the dry air supply part comprises a connection duct part having an upper end that extends by penetrating a lower surface of the tub upward and supplying the dry air into the airflow guide; and a relative movement limiter limiting a rotational movement and a downward movement of the airflow guide relative to the connection duct part in a state in which the airflow guide is coupled to the connection duct part completely. 
     The airflow guide may comprise a cylindrical duct coupling part into which the upper end of the connection duct part is inserted and coupled, and the relative downward movement of the duct coupling part may be limited by a male screw thread. 
     The relative movement limiter may comprise at least one of protruding ribs that are formed in a way that protrudes downward toward the male screw thread at the lower end of the duct coupling part, and at a time of the relative downward movement, the lower end surface of at least one of the protruding ribs may contact the male screw thread. 
     As the duct coupling part and the connection duct part are coupled completely, a gap having a predetermined width may be formed between the lower end surface of at least one of the protruding ribs and the male screw thread, and the relative downward movement may be limited to the predetermined width or less. 
     At least one of the protruding ribs may comprise a first protruding rib, a second protruding rib and a third protruding rib that are arranged at regular intervals around a circular opening through which the upper end of the connection duct part passes. 
     The heights at which the first protruding rib, the second protruding rib and the third protruding rib protrude downward from the lower end of the duct coupling part may differ respectively. 
     Additionally, a maximum height of the first protruding rib protruding from the lower end of the duct coupling part may be a first height, a maximum height of the second protruding rib protruding from the lower end of the duct coupling part may be a second height greater than the first height, and a maximum height of the third protruding rib protruding from the lower end of the duct coupling part may be a third height greater than the second height. 
     Further, a circumferential width of the first protruding rib, a circumferential width of the second protruding rib and a circumferential width of the third protruding rib may be the same. 
     Further, when viewed from the upper portion side of the airflow guide, the first protruding rib, the second protruding rib and the third protruding rib may be consecutively disposed clockwise at the lower end of the connection duct part. 
     Further, a lower end surface of the first protruding rib, a lower end surface of the second protruding rib and a lower end surface of the third protruding rib, protruding from the lower end of the duct coupling part, may be inclined surfaces the height of which respectively increases clockwise. 
     The dry air supply part may further comprise a fastening nut that is screw-coupled to the male screw thread of the connection duct part to fix the connection duct part to the lower surface of the tub, and as the duct coupling part and the connection duct part are coupled completely, at least one of the protruding ribs may be in no contact with the fastening nut. 
     Further, a radial maximum width of at least one of the protruding ribs may be less than a gap between the outer circumferential surface of the connection duct part and the inner circumferential surface of the fastening nut. 
     At least one of the protruding ribs may be inserted into the fastening nut. 
     The duct coupling part may be coupled to the connection duct part, based on a two-stage coupling manipulation. 
     Further, the two-stage coupling manipulation may comprise a perpendicular movement manipulation of relatively moving the airflow guide downward; and a rotational movement manipulation of relatively moving the airflow guide circumferentially after the perpendicular movement manipulation is completed. 
     As the rotational movement manipulation starts, the gap between the lower end surface of at least one of the protruding ribs and the male screw thread may decrease gradually. 
     Further, as the rotational movement manipulation starts, the airflow guide may rotate in a direction opposite to the direction in which the airflow guide rotates to screw-couple the fastening nut to the male screw thread of the connection duct part. 
     Further, the relative movement limiter may further comprise a first guide groove that is formed on the inner circumferential surface of the duct coupling part and extends linearly along an up-down direction, and a second guide groove that has one end portion integrally connecting to an upper end of the first guide groove and extends along a circumferential direction in a circular arc shape, and a guide projection may be provided on the outer circumferential surface of the connection duct part, protrudes toward the inner circumferential surface of the connection duct part, and moves along the first guide groove and the second guide groove at a time of the two-stage coupling manipulation. 
     Further, in the state in which the guide projection is inserted into the first guide groove, the perpendicular movement manipulation may be guided, and in the state in which the guide projection is inserted into the second guide groove, the rotational movement manipulation may be guided. 
     Further, as the rotational movement manipulation is completed, a relative upward movement of the guide projection of the duct coupling part may be limited by the second guide groove. 
     Further, in the state in which the fastening nut is screw-coupled to the connection duct part completely, the lower end surface of the fastening nut may be exposed to the wash space at least partially. 
     The fastening nut may comprise a plurality of contact projections having an upper end that respectively connects to the lower end surface of the fastening nut integrally, and having a lower end that extends toward the lower surface of the tub. 
     Each of the plurality of contact projections may be space from each other on the lower end surface of the fastening nut along the circumferential direction at predetermined circumferential intervals. 
     The predetermined circumferential interval of the plurality of contact projections may be maintained regularly. 
     The predetermined circumferential interval may be greater than a maximum circumferential thickness of the plurality of contact projections. 
     Each of the plurality of contact projections may have the same outer shape. 
     Each of the plurality of contact projections may have an outer shape the horizontal cross section of which decreases gradually from the upper end to the lower end. 
     The lower end of each of the contact projections, contacting the lower surface of the tub, may be formed into a curved surface that is convex toward the lower surface of the tub. 
     Further, a dry air supply hole may be provided on the lower surface of the tub, and the upper end of the connection duct part may pass and extend through the dry air supply hole, and a ring-type coupling surface may be formed around the dry air supply hole and pressurized by the lower end of the contact projection. 
     The coupling surface may extend in a direction perpendicular to the direction in which the fastening nut moves while being screw-coupled to the connection duct part. 
     The direction in which the fastening nut moves while being screw-coupled to the connection duct part may be a perpendicular direction, and the direction in which the coupling surface extends may be a horizontal direction. 
     Further, a convergence surface having a predetermined downward inclination angle with respect to the horizontal direction may be provided around the coupling surface. 
     Further, a cylindrical part may be provided on the lower surface of the tub, and extend circumferentially along the dry air supply hole and protrude upward toward the lower end surface of the fastening nut. 
     The height of the cylindrical part protruding from the lower surface of the tub may remain constant along the circumferential direction. 
     The height of the cylindrical part protruding from the lower surface of the tub may be less than the height of the contact projection protruding from the lower end surface of the fastening nut. 
     The airflow guide may be detachably coupled to the dry air supply part without an additional coupling member. 
     The dry air supply part may comprise a connection duct part that extends in a way that penetrates the lower surface of the tub upward, and supplies the dry air to the airflow guide, and the airflow guide may be detachably coupled to the connection duct part. 
     The airflow guide may be coupled to the connection duct part, based on a two-stage coupling manipulation. 
     The two-stage coupling manipulation may comprise a perpendicular movement manipulation of relatively moving the airflow guide downward. 
     The two-stage coupling manipulation may comprise a rotational movement manipulation of relatively moving the airflow guide circumferentially after the perpendicular movement manipulation is completed. 
     The airflow guide may comprise a duct coupling part having an upper end that is exposed to an inner flow space, and a lower end that connects to the connection duct part, and having a cylindrical shape. The upper end of the cylindrical connection duct part may be coupled to the lower end of the duct coupling part, based on the two-stage coupling manipulation. 
     The upper end of the connection duct part may be inserted into the lower end of the duct coupling part. 
     Further, a first guide groove and a second guide groove may be formed on the inner circumferential surface of the duct coupling part, and the first guide groove may extend linearly along the up-down direction, and the second guide groove may have one end portion integrally connecting to the upper end of the first guide groove and extending along the circumferential direction in a circular arc shape. 
     Further, a guide projection may be provided on the outer circumferential surface of the connection duct part, and may protrude toward the inner circumferential surface of the connection duct part and join the first guide groove and the second guide groove. 
     In the state where the guide projection joins the first guide groove, the perpendicular movement manipulation may be guided. 
     Further, in the state where the guide projection joins the second guide groove, the rotational movement manipulation may be guided. 
     Further, a stopper projection may be integrally provided at the second guide groove, and the stopper projection may be disposed near the other end portion of the second guide groove, and after the rotational movement manipulation is completed, block the generation of a relative rotation in a direction opposite to the direction of the rotational movement manipulation. 
     The relative movement limiter may further comprise a release prevention part that keeps the airflow guide fixed after the rotational movement manipulation is completed, and the release prevention part may prevent the airflow guide from rotating in a direction opposite to the direction of the rotational movement manipulation. 
     One end portion of the release prevention part may be a fixed end portion that integrally connects to the airflow guide, and the other end portion of the release prevention part may be a free end portion that separates from the airflow guide and is elastically deformed. 
     The dry air supply part may further comprise a fastening nut that is screw-coupled to the connection duct part and fixes the connection duct part to the tub, and at least one stopper may be integrally provided at the upper end of the fastening nut and join the free end portion of the release prevention part to prevent the airflow guide from rotating in a direction opposite to the direction of the rotational movement manipulation. 
     The airflow guide may further comprise a release prevention part that keeps the airflow guide fixed after the rotational movement manipulation is completed. 
     The release prevention part may prevent the airflow guide from rotating in a direction opposite to the direction of the rotational movement manipulation. 
     The dry air supply part may comprise a connection duct part that extends in a way that penetrates the lower surface of the tub in the upward direction and supplies the dry air to the airflow guide, and the airflow guide may be detachably coupled to the connection duct part and prevented from rotating relative to the connection duct part in the opposite direction by the release prevention part. 
     The airflow guide may comprise a lower guide which is coupled to the connection duct part and into which dry air generated in the dry air supply part is drawn; and an upper guide which is coupled to the upper side of the lower guide and has a flow space in which the dry air flows, the lower guide, comprising: a duct coupling part having an upper end that is exposed to the flow space and a lower end that is coupled to the connection duct part and having a cylindrical shape; and an edge wall that is formed in a way that surrounds the outer surface of the duct coupling part at least partially, and spaced from the duct coupling part, and the release prevention part may be integrally formed on the edge wall. 
     The release prevention part may be formed m a way that the lower end of the edge wall is partially cut. 
     Further, one end portion of the release prevention part may be a fixed end portion that integrally connects to the airflow guide, and the other end portion of the release prevention part may be a free end portion that separates from the airflow guide and is elastically deformed. 
     Further, a radial thickness of the free end portion may be greater than a radial thickness of the fixed end portion. 
     The dry air supply part may further comprise a fastening nut that is screw-coupled to the connection duct part and fixes the connection duct part to the tub, and at least one of stoppers may be integrally provided at the upper end of the fastening nut, and join the free end portion of the release prevention part and prevent the airflow guide from rotating in a direction opposite to the direction of the rotational movement manipulation. 
     At least one of the stoppers may comprise a first stopper and a second stopper that are arranged one after another along the circumferential direction, and in the state in which the release prevention part is not elastically deformed, the free end portion may protrude at least partially further inward than the radial outer side end portion of the first stopper and the radial outer side end portion of the second stopper with respect to a radial direction. 
     If the airflow guide relatively rotates in a direction opposite to the direction of the rotational movement manipulation, the free end portion may contact any one of one side surface of the first stopper or one side surface of the second stopper. 
     The inner circumferential surface of the release prevention part, facing the connecting duct part, may extend toward the free end portion from the fixed end portion in the circumferential direction, and comprise a non-contact surface that is in no contact with the radial outer side end portion of the first stopper or the radial outer side end portion of the second stopper; and a contact surface that is formed after the non-contact surface in succession, and at a time of the rotational movement manipulation, contacts the radial outer side end portion of the first stopper or the radial outer side end portion of the second stopper. 
     The free end portion of the release prevention part may be elastically deformed based on contact with the radial outer side end portion of the first stopper or the radial outer side end portion of the second stopper. 
     Further, a distance between the contact surface and the central axis of the duct coupling part may decrease gradually toward the free end portion. 
     The free end portion of the release prevention part may be provided with an end portion surface that is formed in a parallel direction with the radial direction, and a tool groove may be provided on the end portion surface and concave toward the fixed end portion. 
     Furthermore, at least one of reinforcement ribs may be integrally provided on the outer circumferential surface of the release prevention part, and protrude outward in the radial direction and extend along the circumferential direction. 
     Advantageous Effects 
     A dishwasher according to the present disclosure may have the effects of evenly distributing dry air and ensuring a sufficient period for which dry air stays in a tub, thereby improving drying efficiency and reducing a drying period. 
     The dishwasher according to the present disclosure has the effect of preventing wash water from being reversely drawn through a discharge opening that is directly exposed to a wash space. 
     The dishwasher according to the present disclosure has the effect of preventing an airflow guide from escaping from a set position or clattering through a simple structure after the airflow guide is assembled and fixed to a dry air supply part. 
     The dishwasher according to the present disclosure has the effect of preventing the airflow guide from escaping from its right position or being broken due to an external impact after the airflow guide is assembled and fixed to the dry air supply part. 
     The dishwasher according to the present disclosure has the effect of preventing the corrosion of the tub and a dry air supply hole and preventing the reproduction of germs and the generation of a bad smell between the tub and a fastening nut since the lower end surface of the fastening nut is exposed to a wash space to prevent wash water from remaining between the fastening nut and the tub. 
     The dishwasher according to the present disclosure has the effect of simplifying the processes of assembling and fixing the airflow guide to the dry air supply part since the assembly structure and fixation structure of the airflow guide spraying dry air are simplified. 
     The dishwasher according to the present disclosure has the effect of preventing a change in a predetermined position of a discharge opening through a means of preventing the misassemble between an upper guide and a lower guide that constitute the airflow guide. 
     The dishwasher according to the present disclosure has the effect of preventing the airflow guide from releasing or escaping from its set position through a simple structure after the airflow guide is assembled and fixed to the dry air supply part. 
     Specific effects are described along with the above-described effects in the section of detailed description. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings constitute a part of the specification, illustrate one or more embodiments in the disclosure, and together with the specification, explain the disclosure. 
         FIG.  1    is front perspective view showing a dishwasher of one embodiment. 
         FIG.  2    is a schematic cross-sectional view showing the dishwasher in  FIG.  1   . 
         FIG.  3    is a front perspective view showing a dry air supply part of the dishwasher of one embodiment, which is accommodated in a base. 
         FIG.  4    is an exploded perspective view showing the dry air supply part in  FIG.  3   . 
         FIGS.  5  and  6    are front perspective views showing a bottom tub coupled to the dry air supply part in  FIG.  3   . 
         FIG.  7    is a plan view of  FIG.  5   . 
         FIG.  8    is a cross-sectional view along A-A in  FIG.  7   . 
         FIG.  9    is a plan view for describing a relative position relationship between a lower rack and a bottom tub with respect to an airflow guide of the dishwasher of one embodiment. 
         FIG.  10    is a partial enlarged view of  FIG.  9    cut in a direction parallel with the front-rear direction. 
         FIGS.  11  and  12    are partial enlarged views of  FIG.  9   . 
         FIG.  13    is a plan view showing a relative position of a lower spray arm and an airflow guide. 
         FIGS.  14 A to  14 C  show experimental data on the distribution of measured temperatures in a drying process of the related art, and  FIGS.  15 A to  15 C  show experimental data on the distribution of measured temperatures in a drying process of one embodiment. 
         FIG.  16    is an exploded perspective view showing an airflow guide and a connection duct part of the dishwasher of one embodiment. 
         FIG.  17    is a side view showing an upper guide in  FIG.  16   , and  FIG.  18    is a rear perspective view showing the upper guide. 
         FIG.  19    is a rear perspective view showing a lower guide in  FIG.  16   ,  FIG.  20    is a front perspective view of the lower guide, and  FIG.  21    is a bottom perspective view of the lower guide. 
         FIG.  22    is a cross-sectional view showing a coupling state between the connection duct part and the lower guide. 
         FIG.  23    is a perpendicular cross-sectional view showing a cross section in the state where the airflow guide is coupled to the connection duct part. 
         FIG.  24    is a horizontal cross-sectional view showing a cross section in the state where the airflow guide is coupled to the connection duct part. 
         FIGS.  25 A to  27 B  are plan views and front views showing the process of assembling the airflow guide of the dishwasher of one embodiment to the connection duct part. 
         FIGS.  28  and  29    are cross-sectional views for describing the structure and function of a release prevention part provided at the airflow guide. 
         FIG.  30    is a partial enlarged view showing the state where the airflow guide is assembled to the connection duct part completely. 
         FIG.  31    is a partial enlarged view showing a connection duct part to which an airflow guide is assembled. 
         FIGS.  32  to  34    are cross-sectional views showing the cross sections of the airflow guide, the connection duct part and the bottom tub in  FIG.  30   , which are cut in different positions. 
         FIG.  35    is a cross-sectional view showing a perpendicular cross section of a fastening nut of the dishwasher of one embodiment. 
         FIG.  36    is a perpendicular cross-sectional view showing a relationship between the fastening nut and the bottom tub in  FIG.  35   . 
     
    
    
     DETAILED DESCRIPTION 
     The above-described aspects, features and advantages are specifically described hereafter with reference to the accompanying drawings such that one having ordinary skill in the art to which the present disclosure pertains can embody the technical spirit of the disclosure easily. In the disclosure, detailed description of known technologies in relation to the disclosure is omitted if it is deemed to make the gist of the disclosure unnecessarily vague. Below, preferred embodiments according to the disclosure are specifically described with reference to accompanying drawings. In the drawings, identical reference numerals can denote identical or similar components. 
     The terms “first”, “second” and the like are used herein only to distinguish one component from another component. Thus, the components should not be limited by the terms. Certainly, a first component can be a second component, unless stated to the contrary. 
     Throughout the disclosure, each component can be provided as a single one or a plurality of ones, unless explicitly stated to the contrary. 
     When one component is described as being “in the upper portion (or lower potion)” or “on (or under)” another component, one component can be directly on (or under) another component, and an additional component can be interposed between the two components. 
     When any one component is described as being “connected”. “coupled”, or “connected” to another component, any one component can be directly connected or coupled to another component, but an additional component can be “interposed” between the two components or the two components can be “connected”. “coupled”, or “connected” by an additional component. 
     The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless explicitly indicated otherwise. It should be further understood that the terms “comprise” or “include” and the like, set forth herein, are not interpreted as necessarily including all the stated components or steps but can be interpreted as excluding some of the stated components or steps or can be interpreted as including additional components or steps. 
     The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless explicitly indicated otherwise. It should be further understood that the terms “comprise” or “include” and the like, set forth herein, are not interpreted as necessarily including all the stated components or steps but can be interpreted as excluding some of the stated components or steps or can be interpreted as including additional components or steps. 
     Throughout the disclosure, the terms “A and/or B” as used herein can denote A, B or A and B, and the terms “C to D” can denote C or greater and D or less, unless stated to the contrary. 
     Hereafter, the subject matter of the present disclosure is described with reference to the drawings showing the configuration of the dishwasher  1  of the embodiment. 
     [Entire Structure of Dishwasher] 
     Hereafter, the entire structure of the dishwasher of one embodiment is describer with reference to the accompanying drawings. 
       FIG.  1    is a front perspective view showing a dishwasher according to the present disclosure, and  FIG.  2    is a schematic cross-sectional view schematically showing the inner structure of the dishwasher according to the present disclosure. 
     As illustrated in  FIG.  1  to  2   , the dishwasher  1  according to the present disclosure comprises a case  10  forming the exterior of the dishwasher  1 , a tub  20  being installed in the case  10 , forming a wash space  21  in which a wash target is washed and having a front surface that is open, a door  30  opening and closing the open front surface of the tub  20 , a driving part  40  being disposed under the tub  20  and supplying, collecting, circulating and draining wash water for washing a wash target, a storage part  50  being provided detachably in the wash space  21  in the tub  20  and allowing a wash target to be mounted on, and a spray part  60  being installed near the storage part  50  and spraying wash water for washing a wash target. 
     At this time, wash targets mounted in the storage part  50  may be cooking vessels such as bowls, dishes, spoons, chopsticks, and the like, and other cooking tools, for example. Hereafter, the wash targets are referred to as cooking vessels, unless mentioned otherwise. 
     The tub  20  may be formed into a box the front surface of which is open entirely, and may be a so-called tub. 
     The tub  20  may have a wash space  21  therein, and its open front surface may be opened and closed by the door  30 . 
     The tub  20  may be formed in a way that a metallic sheet having strong resistance against high-temperature and moisture, e.g., a stainless steel-based sheet, is pressed. 
     Additionally, a plurality of brackets may be disposed on the inner surfaces of the tub  20  and allow functional components such as a storage part  50 , a spray part  60  and the like, which are described below, to be supported and installed in the tub  20 . 
     The driving part  40  may comprise a sump  41  storing wash water, a sump cover  42  distinguishing the sump  41  from the tub  20 , a water supply part  43  supplying wash water to the sump  41  from the outside, a drain part  44  discharging wash water of the sump  41  to the outside, and a water supply pump  45  and a supply channel  46  for supplying wash water of the sump  41  to the spray part  60 . 
     The sump cover  42  may be disposed at the upper side of the sump  41 , and distinguish the sump  41  from the tub  20 . Additionally, the sump cover  42  may be provided with a plurality of return holes for returning wash water, having sprayed to the wash space  21  through the spray part  60 , to the sump  41 . 
     That is, wash water having sprayed toward cooking vessels from the spray part  60  may fall to the lower portion of the wash space  21  and return to the sump  41  through the sump cover  42 . 
     The water supply pump  45  is provided in a lateral portion or the lower portion of the sump  41 , and pressurizes wash water and supplies the same to the spray part  60 . 
     One end of the water supply pump  45  may connect to the sump  41 , and the other end may connect to the supply channel  46 . The water supply pump  45  may have an impeller  451 , a motor  453  and the like, therein. As power is supplied to the motor  453 , the impeller  451  may rotate, and wash water of the sump  41  may be pressurized and then supplied to the spray part  60  through the supply channel  46 . 
     The supply channel  46  may selectively supply the wash water supplied by the water supply pump  45  to the spray part  60 . 
     For example, the supply channel  46  may comprise a first supply channel  461  connecting to a lower spray arm  61 , and a second supply channel  463  connecting to an upper spray arm  62  and a top nozzle  63 . The supply channel  46  may be provided with a supply channel diverting valve  465  selectively opening and closing the supply channels  461 ,  463 . 
     At this time, the supply channel diverting valve  465  may be controlled to allow each of the supply channels  461 ,  463  to be opened consecutively or opened simultaneously. 
     The spray part  60  is provided to spray wash water to cooking vessels and the like stored in the storage part  50 . 
     Specifically, the spray part  60  may comprise a lower spray arm  61  being disposed under the tub  20  and spraying wash water to a lower rack  51 , an upper spray arm  62  being disposed between the lower rack  51  and an upper rack  52  and spraying wash water to the lower rack  51  and the upper rack  52 , and a top nozzle  63  being disposed in the upper portion of the tub  20  and spraying wash water to a top rack  53  or the upper rack  52 . 
     In particular, the lower spray arm  61  and the upper spray arm  62  may be provided in the wash space  21  of the tub  20 , and spray wash water toward cooking vessels in the storage part  50  while rotating. 
     The lower spray arm  61  may be rotatably supported at the upper side of the sump cover  42  such that the lower spray arm  61  may spray wash water to the lower rack  51  while rotating under the lower rack  51 . 
     Additionally, the upper spray arm  62  may be rotatably supported by a spray arm holder  467  such that the upper spray arm  62  may spray wash water while rotating between the lower rack  51  and the upper rack  52 . 
     The tub  20  may be further provided with a reflection plate on a lower surface  25  thereof, to enhance washing efficiency, and the reflection plate diverts the direction of wash water having sprayed from the lower spray arm  61  to an upward direction (U-direction). 
     Since a well-known configuration can be applied to the configuration of the spray part  60 , detailed description of the configuration of the spray part  60  is omitted hereafter. 
     The storage part  50  for storing cooking vessels may be provided in the wash space  21 . 
     The storage part  50  may be withdrawn through the open front surface of the tub  20  from the inside of the tub  20 . 
     For example.  FIG.  2    shows an embodiment provided with a storage part comprising a lower rack  51  that is disposed in the lower portion of the tub  20  and stores relatively large-sized cooking vessels, an upper rack  52  that is disposed at the upper side of the lower rack  51  and stores medium-sized cooking vessels, and a top rack  53  that is disposed in the upper portion of the tub  20  and stores small-sized cooking vessels and the like. However, the subject matter of the present disclosure is not limited to the embodiment. Hereafter, a dishwasher that is provided with three storage parts  50 , as illustrated, is described. 
     Each of the lower rack  51 , the upper rack  52  and the top rack  53  may be withdrawn outward through the open front surface of the tub  20 . 
     To this end, the tub  20  may have a guide rail  54 , on both lateral walls thereof that form the inner circumferential surface of the tub  20 , and for example, the guide rail  54  may comprise an upper rail  541 , a lower rail  542 , a top rail  543  and the like. 
     Each of the lower rack  51 , the upper rack  52  and the top rack  53  may be provided thereunder with wheels. A user may withdraw the lower rack  51 , the upper rack  52  and the top rack  53  outward through the front surface of the tub  20  to easily store cooking vessels on the racks or take out cooking vessels from the racks after a washing process. 
     The guide rail  54  may be provided as a fixed guide rail that guides the withdrawal and insertion of the spray part  60  in the form of a simple rail or as a stretchable guide rail which guides the withdrawal and storage of the spray part  60  and the withdrawal distance of which increases as the spray part  60  is withdrawn. 
     The door  30  is used for opening and closing the open front surface of the tub  20  that is described above. 
     In some examples, a hinge part for opening and closing the door  30  is provided in the lower portion of the open front surface, and the door  30  is open with respect to the hinge part as a rotation axis. 
     The door  30  may be provided with a handle  31  and a control panel  32  on the outer surface thereof. The handle  31  is used for opening the door  30 , and the control panel  32  is used for controlling the dishwasher  1 . 
     As illustrated, the control panel  32  may be provided with a display  33  that visually displays information on a current operation state and the like of the dishwasher, and a button part  34  comprising a selection button to which the user&#39;s selection manipulation is input, a power button to which the user&#39;s manipulation for turning on-off the power source of the dishwasher is input, and the like. 
     The inner surface of the door  30  may form a mounting surface that supports the lower rack  51  of the storage part  50  as the door  30  is opened as well as forming one surface of the tub  20  as the door  30  is closed. 
     To this end, as the door  30  is fully opened, the inner surface of the door  30  forms a horizontal surface in the same direction where the guide rail  54 , by which the lower rack  51  is guided, extends, for example. 
     The door  30  may be provided rotatably between a closed position and a fully-open position, and an intermediate still position may be formed between the closed position and the fully open position. 
     The door  30  may stand still in the intermediate still position, and at this time, the wash space  21  of the tub  20  may be open outward partially. When the door  30  is disposed at the intermediate still position, a dry air supply part  80  described hereafter may operate to supply high-temperature dry air or low-temperature dry air to the wash space  21 . 
     Though not illustrated, the dry air supply part  80  may be provided in the lower portion of the tub  20  and generate high-temperature dry air and supply the high-temperature dry air into the tub  20 . 
     Hereafter, a detailed configuration of the dry air supply part  80  is described with reference to  FIG.  3     
     [Detailed Configuration of Dry Air Supply Part] 
     Hereafter, the detained configuration of the above-described dry air supply part  80  is described with reference to  FIGS.  3  to  7   . 
     As illustrated in  FIG.  3   , the dry air supply part  80  may be accommodated in a base  90  and may be disposed to be supported by a lower surface  91  of the base  90 . 
     For example, the dry air supply part  80  may be disposed in a position adjacent to a rear surface  93  of the base  90 , and disposed in a position between a leakage detecting part and the rear surface  93  of the base  90 , approximately in parallel with the rear surface  93  of the base  90 . 
     The position in which the dry air supply part is disposed may be selected considering the characteristics of the dry air supply part  80  that generates heat of about 100° C. or greater in a high-temperature dry air supply mode. That is, the dry air supply part may be disposed to avoid electronic components that are greatly affected by high-temperature heat. 
     Additionally, the arrangement position of the dry air supply part may be selected based on the position of a dry air supply hole  254  formed on the lower surface  25  of the tub  20 . That is, considering the user&#39;s safety, the dry air supply hole  254  into which dry air flows may be formed at the corner of the lower surface  25  of the tub  20 , which is adjacent to the rear surface and the left side surface of the tub  20 . 
     For the dry air supply part  80  to effectively generate dry air and supply the same to the dry air supply hole  254  formed in the above-described position, the dry air supply part  80  may be disposed at the lower side of the dry air supply hole  254 . 
     The arrangement position of the dry air supply part  80  is described exemplarily. The dry air supply part  80  may be disposed near a left side surface  94 , a right side surface  95  or a front surface  92  of the base  90  rather than the rear surface  93  of the base  90 . Hereafter, the dry air supply part  80  disposed near the rear surface  93  of the base  90  approximately in parallel with the rear surface  93  is described, but the position of the dry air supply part  80  is not limited. 
     Additionally, a support rib for supporting the dry air supply part  80  and preventing the escape of the dry air supply part  80 , a plurality of guide ribs setting the position of a leakage detecting part that detects whether wash water leaks from the tub  20  and preventing the escape of the leakage detecting part, and a wash water rib for guiding wash water being discharged from the dry air supply part  80  to the leakage detecting part may be provided on the lower surface  91  of the base  90 . 
     The support rib, the guide ribs and the wash water rib may be formed integrally on the lower surface  91  of the base  90 , for example. 
     A first leg, a second leg  892  and a third leg  893  of the dry air supply part  80  described hereafter may be coupled to the support rib, based on a non-fastening method. That is, the first leg, the second leg  892  and the third leg  893  may be simply held at the support rib without an additional fastening means such that the dry air supply part  80  may be supported in up-down, front-rear and left-right directions. 
       FIG.  4    shows a detailed configuration of the dry air supply part  80 . 
     As illustrated, the dry air supply part  80  generating dry air and supplying the same into the tub  20  may comprise an air blowing fan that generates dry airflow F to be supplied into the tub  20 , a heater that heats dry air, a heater housing  81  that has an air passage in which the heater is accommodated, and a filtering part  88  that filters air to be suctioned into the air blowing fan. 
     The air blowing fan is disposed at the upstream side in the direction of dry airflow F with respect to the heater and the heater housing  81 , and accelerates air to the air passage formed in the heater housing  81  to generate dry airflow F. 
     The air blowing fan, and an air blowing motor generating rotational driving force of the air blowing fan may be mutually modularized, and form an assembly in a way that the air blowing fan and the air blowing motor are accommodated in a fan housing  82 . 
     The air blowing fan and the fan housing  82  may be fixed to a housing connector  87  that connects a filer housing  881  of the below-described filtering part  88  and the heater housing  81 . 
     Specifically, the air blowing fan and the fan housing  82  may be accommodated entirely in the filter housing  881  in the state of being fixed to a connection tab  872  the housing connector  87 . 
     The type of the air blowing fan to be applied to the dry air supply part  80  is not limited, but a sirocco fan, for example, is preferred considering the position and space limitations in the installation of the air blowing fan. 
     When a sirocco fan is applied as illustrated, filtered air may be suctioned from a lower surface of the fan housing  82 , in a direction parallel a direction from the center of the sirocco fan to the rotational axis of the same, and be accelerated and discharged outward in the radial direction. 
     The accelerated and discharged air may form dry airflow F and be drawn into the air passage in the heater housing  81  through the fan housing  82  and an inlet  8712  of the housing connector  97 . 
     At this time, the air blowing fan, e.g., a sirocco fan, and a rotation shaft  8251  of the motor may be disposed to have directionality approximately parallel with the up-down direction (U-D direction), and filtered air may be suctioned through the lower surface of the fan housing  82 , for example. 
     Further, a PCB substrate for controlling the moor may be built into an upper surface  821  of the fan housing  82 , which corresponds to the opposite side of the lower surface into which filtered air is suctioned. 
     The fan housing  82 , as illustrated, may be fixed to a ring-type connection tab  872  provided at the housing connector  87  through a fastening means such as a screw bolt that is not illustrated, and the like, for example. 
     The connection tab  872  may be provided with a pair of fastening bosses that extend from the upper surface of the connection tab  872  in the upward direction (U-direction). 
     To support the fan housing  82  and the heater housing  81 , the first leg protruding toward the base may be integrally formed under the housing connector  87 . 
     The heater may be indirectly supported in the state of separating from the heater housing  81  and a connector main body  871 . 
     The front end side of the heater may be supported by a terminal fixation part, in the state of separating from the housing connector  87 . A c may be fixed to the front surface of the terminal fixation part, in the state of protruding outward. 
     An entirely-open rear end portion  871   b  of the housing connector  87  may be fixed while being fitted and coupled to the heater housing  81 . 
     The heater is disposed in the air passage formed in the heater housing  81 , and preferably, is directly exposed to dry airflow F in the air passage and heats the dry airflow F. 
     When the dry air supply part  80  supplies high-temperature dry air, power may be supplied to the heater, and the heater may heat dry air, and when the dry air supply part  80  supplies low-temperature dry air, the supply of power to the heater may be cut off, and the heater may stop operating. 
     At this time, when low-temperature dry air is supplied, the air blowing motor may keep operating to generate dry airflow F. 
     The type of the heater provided in the dry air supply part  80  of one embodiment is not limited, but a tube-type sheath heater may be selected since the sheath heater has a relatively simple structure, ensures excellent heat generation efficiency and helps to prevent electric leakage caused by the reverse inflow of wash water that comes in from the tub  20  reversely, for example. 
     To enhance heat exchange efficiency, the heater that is a sheath heater may have a stereoscopic shape with a plurality of bends, to be directly exposed to dry airflow F at the air passage in the heater housing  81  and ensure a maximum heat transfer surface. 
     Additionally, a pair of terminals for receiving power may be formed in one end portion and the other end portion of the heater. 
     The rear end side of the heater may be fixed and supported by a single heater bracket  845  disposed in the heater housing  81 . That is, the rear end side of the heater may be supported on the air passage through the heater bracket  845  in the state of being separated from the heater housing  81 . 
     Further, a temperature sensor as a temperature sensing part  86  sensing the temperature of high-temperature dry air generated through the heater or detecting the overheating of the heater may be provided on the upper side surface of the heater housing  81 . 
     For example, the temperature sensor may comprise a thermistor that senses the temperature of dry air, and a thermostat that detects the overheating of the heater. 
     An output signal of the temperature sensor may be delivered to a non-illustrated controller, and the controller may receive the output signal of the temperature sensor to determine the temperature of high-temperature dry air and the overheating of the heater. As the heater overheats, the controller may cut off the supply of power to the heater and change the operation mode of the dry air supply part  80  from the high-temperature dry air supply mode to the low-temperature dry air supply mode. 
     The heater housing  81  may be formed into a hollow hole that has a vacant inner space such that the air passage, in which the above-described heater and heater bracket  845  are disposed, is formed. 
     At this time, for dry airflow F to move, the front end portion of the heater housing  81 , corresponding to the upper stream side with respect to the direction of the movement of the dry airflow F. and the rear end portion of the heater housing  81 , corresponding to the lower stream side with respect to the direction of the movement of the dry airflow F, may be open at least partially. 
     The dry air supply part  80  may further comprise a connection duct part  85  that is coupled to an outlet, formed at the left end side of the heater housing  81  and being open in the upward direction (U-direction), and has an air passage therein. 
     As described above, the heater housing  81  and the air blowing fan are disposed under the lower surface  25  of the tub  20 , e.g., a bottom tub  20   c . The connection duct part  85  guides dry air being discharged from the heater housing  81  to a predetermined position, i.e., the dry air supply hole  254  formed at the tub  20 . 
     For example, the predetermined position may be the lower surface  25  of the tub  20 , and the dry air supply hole  254  into which dry airflow F guided to the connection duct part  85  is drawn may be formed at a corner of the lower surface  25  of the tub  20 , which is adjacent to a rear surface  23  and a left side surface  26 . 
     As shown in the illustrative embodiment, a duct main body  851  of the connection duct part  85  may have a shape that is capable of changing the direction of dry airflow and connecting the dry air supply hole  254  of the tub  20  and the outlet of the heater housing  81 . 
     For example, the duct main body  851  of the connection duct part  85  may have a cylinder shape that allows of the fluid communication of a lower end portion  8512  with the outlet of the heater housing  81  and allows an upper end  8511  to extend in the upward direction (U-direction) and connect to the dry air supply hole  254 . 
     The lower end portion  8512  of the duct main body  851  may be coupled the heater housing  81  in a sliding manner. 
     Further, considering the cross section of the rectangle-shaped outlet of the heater housing  81 , the lower end portion of the duct main body  851  may have a rectangle pillar shape, and for the prevention of leakage, the upper end  8511  of the duct main body  851  may have a cylinder shape. 
     That is, the duct main body  851  may have a cylinder shape to improve the efficiency of a coupling between the upper end  8511  of the duct main body  851  and the dry air supply hole  254  of the tub  20  and to prevent leakage. 
     An airflow guide  83  may be coupled to the upper end  8511  of the duct main body  851  and divert the direction of dry airflow being supplied through the duct main body  851  to supply the dry airflow to the wash space. 
     The filtering part  88  may be disposed in the upper stream of the heater with respect to the direction of the flow of dry airflow, to filter air to be suctioned into the air blowing fan and supply the filtered air to the heater. 
     Specifically, the filtering part  88  may comprise a filter member  883  that filters air to be suctioned into the air blowing fan, and a hollow hole-type filter housing  881  that has a filter accommodation space S 1  in which the filter member  883  is disposed in a replaceable manner and a fan housing accommodation space S 2  in which the fan housing  82  is disposed. 
     As illustrated in  FIG.  4   , the filter housing  881  may comprise a first housing  8811  and a second housing  8812  that are disposed in the form of a segment body that is segmented with respect to the up-down direction (U-D direction), for example. At this time, the first housing  8811  may be the upper housing, and the second housing  8812  may be the lower housing. 
     The filter housing  881  accommodates and supports the filter member  883  and the fan housing  82  of the air blowing fan. 
     Accordingly, the first housing  8811  may be divided into a filter accommodation part  8811   a  and a fan housing accommodation part  8811   b  such that the first housing  8811  accommodates and supports the filter member  883  and the fan housing  82  at least partially, preferably, accommodates and supports the upper portion of the filter member  883  and the upper portion of the fan housing  82 . 
     As illustrated, the lower surfaces of the filter accommodation part  8811   a  and the fan housing accommodation part  8811   b  of the first housing  8811  are open entirely to allow the second housing  8812  to be coupled to the lower sides of the filter accommodation part  8811   a  and the fan housing accommodation part  8811   b  of the first housing  8811 . 
     The filter accommodation part  8811   a  may be formed further upstream than the fan housing accommodation part  8811   b  with respect to the direction of the flow of dry airflow, and in the illustrative embodiment, formed on the right of the fan housing accommodation part  8811   b.    
     The filter accommodation part  8811   a , for example, may have an outer shape of a partial cylinder to accommodate the filter member  883  having a cylinder shape in a way that the filter member  883  may be inserted and withdrawn when the filter member  883  is replaced. 
     Additionally, a filter guide rib may be integrally provided in the filter accommodation part  8811   a  and have a shape similar to that of a filter guide rib  8812   f  of the second housing  8812  described hereafter. 
     The filter accommodation part  8811   a  may have a coupling opening  8811   c  at the upper end thereof, and the coupling opening  8811   c  is open in the form of a circle in response to the outer shape of the filter member  883 . The filter member  883  may move downward through the coupling opening  8811   c , and move to a filter accommodation part  8812   a  of the second housing  8812 . 
     The fan housing accommodation part  8811   b  may be formed further downstream than the filter accommodation part  8811   a  with respect to the direction of the flow of dry airflow, and in the illustrative embodiment, formed integrally at the filter accommodation part  8811   a , on the right of the filter accommodation part  8811   a , near the heater housing  81 . 
     The fan housing accommodation part  8811   b  may have an inner shape corresponding to the outer shape of the upper portion of the fan housing  82 , to cover the upper portion of the air blowing fan entirely. For example, the fan housing accommodation part  8811   b  may have an upper surface formed into a flat plate. 
     As illustrated, the upper surface of the first housing  8811  may have an inclined surface  8811   b   1  that connects the upper end of the filter accommodation part  8811   a  and the fan housing accommodation part  8811   b.    
     The second housing  8812  of the filter housing  881  is coupled to the lower portion of the first housing  8811  and forms a sealed accommodation space, and accommodates and supports the lower portions of the filter member  883  and the fan housing  82 . 
     Like the first housing  8811 , the second housing  8812  may be divided into a filter accommodation part  8812   a  and a fan housing accommodation part  8812   b , to accommodate and support the lower portion of the filter member  883  and the lower portion of the fan housing  82 . 
     As illustrated, the upper end of the second housing  8812  may be open entirely to be coupled to the lower end of the first housing  8811 . 
     In response to the filter accommodation part  8811   a  of the first housing  8811 , the filter accommodation part  8812   a  of the second housing  8812 , provided under the filter accommodation part  8811   a  of the first housing  8811 , may be provided with a plurality of filter guide ribs that guides the filter member  883 &#39;s movement and prevents the filter member  883 &#39;s escape from the right position at a time of inserting the filter member  883 . 
     Additionally, in response to the filter member  883 &#39;s outer shape formed into a cylinder, the plurality of filter guide ribs may be arranged and disposed radially around the filter member  883 . 
     As the center of the plurality of filter guide ribs  8812   f , a lower suction opening  8812   c  may be formed on the bottom surface of the filter accommodation part  8812   a  in a penetrating manner, and is open toward the lower surface of the base  90  and allows external air to be suctioned. 
     The lower suction opening  8812   c  may have a circle shape to correspond to the shape of a lower opening of the filter member  883  having a cylinder shape, and a relative position and size of the lower suction opening  8812   c  may be determined to allow external air to pass through the lower opening and to be smoothly suctioned into the filter member  883 . 
     Additionally, as one airtight means, a pair of ring-type ribs may be formed around the lower suction opening of the bottom surface of the second housing  8812 , and prevent non-filtered external air to be leaked and suctioned into the inner space of the filter housing  881  directly. 
     The fan housing accommodation part  8812   b  may be formed further downstream than the filter accommodation part  8812   a  with respect to the direction of the flow of dry airflow, and in the illustrative embodiment, formed integrally at the filter accommodation part  8812   a , on the right of the filter accommodation part  8812   a , near the heater housing  81 . 
     The fan housing accommodation part  8811   b  may have an inner shape corresponding to the outer shape of the lower portion of the fan housing  82 , to cover the lower portion of the air blowing fan entirely. 
     The bottom surface of the fan housing accommodation part  8811   b  may be spaced a predetermined distance apart from the lower surface of the fan housing  82 , to allow filtered air to be suctioned effectively, and for example, be formed into a flat surface in a direction parallel with the horizontal direction. 
     As a means of spacing the fan housing  82  apart from the bottom surface of the fan housing accommodation part  8811   b  and supporting the fan housing  82 , a plurality of uplifted surface parts and a screw boss that protrude from the bottom surface may be provided in the fan housing accommodation part  8812   b.    
     In the first housing  8811  and the second housing  8812  that are disposed in the form of a segment body as described above, the lower end of the first housing  8811  and the upper end of the second housing  8812  may be detachably coupled to each other. 
     To achieve the above-described detachable coupling relationship, a fastening tab  8811   d  extending toward the second housing  8812  is provided at the lower end of the first housing  8811 , and a hook projection  8812   d  may be provided at the upper end of the second housing  8812  and fastened to the fastening tab  8811   d  based on a hook coupling. 
     A tub connection duct  882  may be detachably coupled and fastened to the coupling opening  8811   c  of the filter accommodation part  8811   a  of the first housing  8811 . 
     The filter member  883  may be replaced through a lower surface  25  of the tub  20 . 
     To this end, the filter accommodation part  8811   a  of the first housing  8811  needs to connect to the lower surface  25  of the tub  20 , and the tub connection duct  882  connects the lower surface  25  of the tub  20  and the filter accommodation part  8811   a  of the first housing  8811 . 
     The tub connection duct  882  may be integrally provided at the filter accommodation part  8811   a  of the first housing  8811 . The tub connection duct  882  may be provided additionally in the first housing  8811 , as illustrated. 
     Like the duct main body  851  of the above-described connection duct part  85 , an upper end portion  8821  of the tub connection duct  882  may pass through the lower surface  25  of the tub  20  and extend upward. 
     A filter replacement hole  253  ( FIG.  11   ) may be provided on the lower surface  25  of the tub  20  to allow the upper end portion  8821  of the tub connection duct  882  to be inserted. 
     A sump hole  252  on which a sump  41  is mounted may be provided in the central portion of the lower surface  25  of the tub  20 . The lower surface  25  of the tub  20  may have a convergence surface having an inclination angle at which the convergence surface gradually inclines downward toward the sump hole  252 , to allow wash water to be effectively converged on the sump hole  252 . 
     As illustrated, the filter replacement hole  253  may be formed on the convergence surface, at the rear of the sump hole  252 . 
     To distinguish the filter replacement hole  253  from the dry air supply hole  254 , the filter replacement hole  253  may be formed at the corner adjacent to the rear surface and the right side surface, on the lower surface  25  of the tub  20 . Additionally, to easily insert and withdraw the filter member  883  for replacement, the filter replacement hole  253  may be disposed closer to the front surface of the tub  20  than the dry air supply hole  254  and disposed further rearward than a water softener communication hole  255 . 
     The water softener communication hole  255  formed in front of the filter replacement hole  253 , for example, may be used to insert a water softening agent into a water softener provided under the water softener communication hole  255 , and the like, or used for the replacement and maintenance and repairs of another component such as a purification filter of a water supply part, and the like. 
     The filter replacement hole  253  may be disposed between the water softener communication hole  255  and the dry air supply hole  254  with respect to the front-rear direction or the left-right direction. 
     That is, the filter replacement hole  253  may be disposed outside a virtual extension line that connects the water softener communication hole  255  and the dry air supply hole  254 . 
     By doing so, even if the lower surface  25  of the tub  20  has a plurality of openings, the strength, torsional rigidity and flexural rigidity of the tub  20  may not decrease. 
     Additionally, to distinguish the filter replacement hole  253  from the water softener communication hole  255  formed in front of the filter replacement hole  253 , a sealing cap  884  having a different shape or color from the water softener communication hole  255  may be applied at the upper end of the tub connection duct  882  that passes through the filter replacement hole  253  and is exposed to the wash space. 
     As described above, the filter replacement hole  253  is provided on the convergence surface provided on the lower surface  25  of the tub  20 . Thus, the tub connection duct  882 &#39;s upper end portion and flange coupled to the filter replacement hole  253  may have a predetermined inclination angle with respect to the perpendicular direction in response to the inclination angle of the convergence surface of the tub  20 , i.e., may be formed to incline with respect to the perpendicular direction. 
     A first gasket  885  may be further provided between the flange  8823  of the tub connection duct  882  and the lower surface  25  of the tub  20 , to prevent a fastening nut  886  from loosening and prevent leakage. 
     As the tub connection duct  882  is fixed to the lower surface  25  of the tub  20  through the fastening nut  886 , the sealing cap  884  may be coupled to the upper end portion  8821  of the tub connection duct  882  exposed to the inside of the tub  20 . At this time, an airtight ring  887  for preventing leakage may be disposed between the sealing cap  884  and the upper end portion  8821  of the tub connection duct  882 . 
     Additionally, an upper suction opening  8826  into which external air is suctioned may be formed under the flange corresponding to the upper side of the filter accommodation space S 1 , between the upper end portion and a lower end portion of the tub connection duct  882 , in a penetrating manner. 
     The upper suction opening  8826  may be formed in a way that penetrates the cylinder-type tub connection duct  882  from the inner circumferential surface thereof to the outer circumferential surface thereof. For example, the upper suction opening  8826  may be provided as a plurality of penetration openings arranged and formed along the circumferential direction of the tub connection duct  882 . 
     The upper suction opening  8826  may be formed higher than an upper opening of the filter member  883 , in the state where the filter member  883  is disposed in the filter accommodation space S 1 . Accordingly, the upper suction opening  8826  may be formed between the tub  20  and the upper surface of the filter member  883  with respect to the up-down direction. 
     After external air having passed through the upper suction opening  8826  in a direction parallel with the horizontal direction enters into the filter member  883 , the direction of the airflow changes, and the external air may be filtered while passing through the outer circumferential surface of the filter member  883 . 
     The suction path of external air and the flow path of dry airflow having passed through the filter member  883  are described hereafter with reference to  FIG.  8   . 
     [Air Flow Path Before and After Filtering] 
     Hereafter, the flow path of external air before the external air passes through the filter member  883  of the dishwasher  1  of one embodiment, and the flow path of dry airflow F after external air passes through the filter member  883  and is filtered are described with reference to  FIG.  8   . 
     The first housing  8811  and the second housing  8812  of the filter housing  881  of the dishwasher  1  of one embodiment are spaced from each other in the up-down direction, and in the filter housing  881 , external air is suctioned through a plurality of suction openings that are open toward a space between the base  90  and the tub  20 . 
     As described above, the plurality of suction openings may comprise the upper suction opening  8826  provided at the tub connection duct  882 , at the upper side of the filter accommodation space S 1 , and the lower suction opening  8812   c  provided on the bottom surface of the second housing  8812 , at the lower side of the filter accommodation space S 1 . 
     As described above, the upper suction opening  8826  and the lower suction opening  8812   c  are spaced from each other and disposed respectively in the uppermost position and the lowermost position of the filter housing  881  with respect to the space between the tub  20  and the base  90 . Accordingly, in the state where the effect of the flow rate of air suctioned respectively into the upper suction opening and the lower suction opening is minimized, external air may flow into the filter housing  881  through the two suction openings, thereby ensuring more flow rate of air required to dry a wash target and spending less time drying a wash target than usual. 
     As illustrated, the upper suction opening  8826  is open in a direction approximately parallel with the horizontal direction. Accordingly, external air suctioned into the upper suction opening  8826  forms airflow of a direction parallel with the horizontal direction. 
     The lower suction opening  8812   c  is formed on the bottom surface that extends horizontally. Accordingly, the lower suction opening  8812   c  is open toward the base  90  in a direction parallel with the perpendicular direction, and external air suctioned into the lower suction opening  8812   c  forms airflow of a direction parallel with the perpendicular direction. 
     External air suctioned through the upper suction opening  8826  may enter into the upper opening of the filter member  883  disposed right under the upper suction opening  8826  in the state where the filter member  883  is disposed in the filter accommodation space S 1 . 
     Additionally, external air suctioned through the lower suction opening  8812   c  may enter into the lower opening of the filter member  883  disposed right on the lower suction opening  8812   c  in the state where the filter member  883  is disposed in the filter accommodation space S 1 . 
     In the state where the filter member  883  is disposed, an airtight means of preventing non-filtered air from being suctioned into the filter housing  881  may be provided at the upper end side and the lower end side of the filter member  883 . 
     Thus, external air suctioned into the upper suction opening  8826  and the lower suction opening  8812   c  may enter respectively into the upper opening and the lower opening of the filter member  883 , without leaking. 
     Further, in the state where the filter member  883  is disposed in the filter accommodation space S 1 , the upper opening of the filter member  883  is open toward the lower surface  25  of the tub  20 , and the lower opening of the filter member  883  is open toward the lower surface of the base  90 . Accordingly, the direction of airflow of external air changes downward while passing through the upper opening, and external air having passed through the lower opening flows upward. 
     As described above, external air suctioned into the filter member  883  may pass through the filtering material of the filter member  883  and be evenly suctioned entirely in the up-down direction and circumferential direction. 
     Further, external air suctioned into the inner circumferential surface of the filter member  883  is filtered, and while passing through the outer circumferential surface of the filter member  883 , is discharged, and immediately after the discharge, the direction of the flow of the external air changes. 
     As illustrated in  FIG.  8   , the direction of the flow of the filtered air having passed through the outer circumferential surface of the filter member  883  may change toward the lower surface of the fan housing  82  that is open toward the bottom surface of the filter housing  881 . 
     The lower surface of the fan housing  82  is disposed in a position spaced upward from the bottom surface, between the lower end and the upper end of the filter member  883 . Accordingly, air having passed through the filter member  883  in a position higher than the lower surface of the fan housing  82  flows downward to the lower surface of the fan housing  82 , and air having passed through the filter member  883  in a position lower than the lower surface of the fan housing  82  flows upward to the lower surface of the fan housing  82 . 
     Filtered air drawn into the fan housing  82  through the above-described flow path is accelerated by the air blowing fan and then drawn into the housing connector  87  and the inner space of the heater housing  81 , such that dry airflow F is formed. 
     [Detailed Configuration of Airflow Guide] 
     Hereafter, a detailed configuration of the airflow guide  83  of the dishwasher  1  of one embodiment is described with reference to  FIGS.  1  to  9   . 
     As illustrated in  FIG.  9   , the airflow guide  83  may be disposed between the lower surface  25  of the bottom tub  20   c  and the lower rack  51 , near the lower surface  25  of the bottom tub  20   c , and divert the direction of the flow of dry airflow F supplied through the duct main body  851 . 
     Specifically, the airflow guide  83  may be disposed near the corner formed between the left side surface  26  and the rear surface  23  of the bottom tub  20   c  or near the corner formed between the right side surface  27  and the rear surface  23  of the bottom tub  20   c . In response to the position of the airflow guide  83 , the above-described dry air supply hole  254  for transferring dry air may be formed on the lower surface  25  of the bottom tub  20   c.    
       FIGS.  1  to  9    show that the airflow guide  83  and the dry air supply hole  254  are adjacent to the lower surface  25  of the bottom tub  20   c , near the corner formed between the left side surface  26  and the rear surface  23  of the bottom tub  20   c , for example. Hereafter, for convenience, the airflow guide  83  and the dry air supply hole  254 , which are disposed near the corner formed between the left side surface  26  and the rear surface  23  of the bottom tub  20   c  as illustrated, are described as an example, but not limited. 
     The corner formed between the left side surface  26  and the rear surface  23  of the bottom tub  20   c  corresponds to a position farthest from the upper end of the front surface  22  of the tub  20  that is partially open in the drying stage. 
     Thus, the period for which dry air sprayed from the airflow guide  83  remains in the tub  20  may extend effectively. By doing so, dry air may be supplied to the lower rack  51 , the upper rack  52  and the top rack  53  evenly and then discharged through the upper end of the front surface of the tub, enabling thermal energy of the dry air to be transferred to wash targets effectively and significantly promoting the effect of drying the wash targets. 
     Additionally, since the airflow guide  83  is spaced a predetermined distance apart from the rear surface  23 , the lower surface  25  and the left side surface  26  of the bottom tub  20   c , food and the like may be effectively prevented from being fitted and fixed between the airflow guide  83  and the bottom tub  20   c.    
     The period for which dry air remains in the tub  20  may further increase, based on the adjustment of the direction of the spray of dry air from the airflow guide  83 . 
     That is, a discharge opening  833  of the airflow guide  83 , from which dry air sprays, may be formed in a position where dry air does not directly spray toward the lower rack  51  and wash targets stored on the lower rack  51 . 
     Specifically, the airflow guide  83  of the dishwasher  1  of one embodiment may discharge dry air in a direction that is not the upward direction (U-direction) perpendicular to the lower surface  25  of the bottom tub  20   c  or the direction in which dry air does not spray directly toward the lower rack  51 . 
     To this end, the discharge opening  833  from which dry air sprays may be formed on the right side surface of the airflow guide  83  to discharge dry air in a direction approximately parallel with the rear surface  23  of the bottom tub  20   c.    
     As illustrated in  FIGS.  9  and  10   , the front-rear (F-R direction) width of the airflow guide  83  may be greater than the left-right (Le-Ri direction) width in the state where the airflow guide  83  is coupled to the duct main body  851  of the connection duct part  85 , and the discharge opening  833  may be formed continuously throughout the right side surface of the airflow guide  83 , facing the right side surface  27  of the bottom tub  20   c , and the rear surface of the airflow guide  83 . That is, the discharge opening  833  of the airflow guide  83  may have the directionality that does not face the door directly and face the front surface  22  of the tub  22  or the door  30  linearly. 
     At this time, the discharge opening  833  of the airflow guide  83  may be formed into a slit or have an oblong shape the up-down (U-D direction) height of which is less than the front-rear (F-R direction) length. Additionally, for dry air to spray in a lowermost position, the up-down (U-D direction) height of the discharge opening  833  may remain constant in the front-rear direction (F-R direction). 
     Additionally, as illustrated, a front edge  833   b  of the discharge opening  833 , which is a first side edge, may be formed on the right side surface of the airflow guide  83 , having a flat plate shape, and a rear edge  833   a  that is a second side edge may extend to the rear surface of the airflow guide  83 , having a curved surface shape. That is, the front edge  833   b  and the rear edge  833   a  of the discharge opening  833  may be spaced from each other, along the direction where an upper end edge of the discharge opening  833  extends. 
     Accordingly, dry air sprayed through the discharge opening  833  may be discharged in the lowest position with respect to the up-down direction (U-D direction), and based on the slit shape of the discharge opening, spray having directionality, which is approximately parallel with the rear surface  23  of the bottom tub  20   c  with respect to the horizontal direction and does not face the door  30  linearly. 
     Further, to promote the effect of distributing dry air sprayed through the discharge opening  833 , the discharge opening  833  may extend from the lower portion of the lower rack  51 , between a space S formed between the lower rack  51  and the rear surface  23  of the bottom tub  20   c.    
     That is, at least a portion of dry air sprayed through the slit-shaped discharge opening  833  may spray toward between the lower surface  25  of the bottom tub  20   c  and the lower rack  51 , and the remaining portion of the dry air may spray toward the space S. 
     To this end, the front edge  833   a  of the slit-shaped discharge opening  833  may be disposed under the lower rack  51 , and the rear edge  833   b  of the discharge opening  833  may be disposed in the space S. 
     In other words, the discharge opening  833  of the airflow guide  83 , as illustrated in  FIG.  9   , may be divided into a first portion  8331  disposed under the lower rack  51 , and a second portion  8332  disposed in the space S. and a rear end portion  511  of the lower rack  51  may be a reference line dividing the first portion  8331  and the second portion  8332 . 
     By doing so, dry air may spray in a direction that does not face the center of the lower rack  51  directly, or a direction that avoids the lower rack  51 , and dry airflow F having passed through the first portion  8331  may move up toward the lower surface of the lower rack  51 , and dry airflow F having passed through the second portion  8332  may move up by passing through the space S. 
     Thus, the thermal energy of dry air may be distributed evenly in the tub  20  without concentrating on a specific portion of the lower rack  51 . 
     A relative ratio of the first portion  8331  and the second portion  8332  may be set differently depending on a required distribution ratio of dry air. That is, when more dry air needs to be supplied to the lower rack  51 , a surface area ratio of the first portion  8331  may increase, and when more dry air needs to be supplied to the space S, a surface area ratio of the second portion  8332  may increase. 
     However, since the capacity of the lower rack  51  is much greater than the capacity of the upper rack  52  or the top rack  53 , the surface area ratio of the first portion  8331  is greater than the surface area ratio of the second portion  8332 , for example. 
     To this end, the airflow guide  83 , as illustrated in  FIGS.  11  and  12   , may be disposed closer to the rear surface  23  of the bottom tub  20   c  than the lower rack  51 . Specifically, when the rear end portion  511  of the lower rack  51  is spaced a first distance G 1  apart from the rear surface  23  of the bottom tub  20   c  in the state where the lower rack  51  is stored in the wash space, the rear end portion of the airflow guide  83  may be spaced from the rear surface  23  of the bottom tub  20   c  to have a second distance G 2  less than the first distance G 1 . 
     At this time, the front edge  833   a  of the slit-shaped discharge opening  833  may be disposed under the lower rack  51 , and the rear edge  833   b  of the discharge opening  833  may be disposed in the space S. 
     In other words, the discharge opening  833  of the airflow guide  83 , as illustrated in  FIG.  12   , may be divided into a first portion  8331  disposed under the lower rack  51 , and a second portion  8332  disposed in the space S, and the rear end portion  511  of the lower rack  51  may be a reference line dividing the first portion  8331  and the second portion  8332 . 
     By doing so, dry air may spray in a direction that does not face the center of the lower rack  51  directly, or a direction that avoids the lower rack  51 , and dry airflow F 1  having passed through the first portion  8331  may move up toward the lower surface of the lower rack  51 , and dry airflow F 2  having passed through the second portion  8332  may move up by passing through the space S. 
     Thus, the thermal energy of dry air may be distributed evenly in the tub  20  without concentrating on a specific portion of the lower rack  51 . 
     A relative ratio of the first portion  8331  and the second portion  8332  may be set differently depending on a required distribution ratio of dry air. That is, when more dry air needs to be supplied to the lower rack  51 , a surface area ratio of the first portion  8331  may increase, and when more dry air needs to be supplied to the space S, a surface area ratio of the second portion  8332  may increase. 
     However, since the capacity of the lower rack  51  is much greater than the capacity of the upper rack  52  or the top rack  53 , the surface area ratio of the first portion  8331  is greater than the surface area ratio of the second portion  8332 , for example. 
     Considering the fact, the surface area of the second portion  8332 , escaping from the rear end portion  511  of the lower rack  51  and being disposed in the space S, may account for 25% to 50% of the entire surface area of the discharge opening  833  of the airflow guide  83 . 
     Further, since the rear edge  833   b  of the discharge opening  833 , as illustrated in  FIGS.  11  and  12   , extends to the rear surface of the airflow guide  83 , at least a portion of dry airflow sprayed at the rear edge  833   b  side of the discharge opening  833  may have directionality facing the rear surface  23  of the bottom tub  20   c.    
     As illustrated in  FIG.  13   , the airflow guide  83  may be disposed outside the rotation range R 1  of the lower spray arm  61 , and separated and spaced from the rear surface  23 , the lower surface  25  and the left side surface  26  of the bottom tub  20   c.    
     That is, the airflow guide  83  may be disposed between the corner gathered and formed by the rear surface  23 , the lower surface  25  and the left side surface  26  of the bottom tub  20   c , and the rotation rage of the lower spray arm  61 . 
     Since the airflow guide  83  is disposed at the corner of the bottom tub  20   c , outside the rotation range R 1  of the lower spray arm  61 , as described above, interference with the lower spray arm  61  rotating in the washing stage or the rinsing stage may be prevented effectively. 
     Additionally, since the airflow guide  83  is spaced a predetermined distance apart from the rear surface  23 , the lower surface  25  and the left side surface  26  of the bottom tub  20   c , food and the like may be effectively prevented from being fitted and fixed between the airflow guide  83  and the bottom tub  20   c.    
       FIGS.  14 A to  14 C  are views showing temperature distribution measured respectively at a top rack  53 , an upper rack  52  and a lower rack  51  in the state where dry air is supplied through an airflow guide  83  of the related art, and  FIGS.  15 A to  15 C  are views showing temperature distribution measured respectively at the top rack  53 , the upper rack  52  and the lower rack  51  in the state where dry air is supplied through the airflow guide  83  of one embodiment. 
     The experiment on the comparative example of the related art in  FIGS.  14 A to  14 C , and the experiment on the experimental example of one embodiment in  FIGS.  15 A to  15 C  were performed under the same test conditions, except for the direction in which dry air sprayed. 
     As illustrated in  FIGS.  14 A to  14 C , when the airflow guide  83  is disposed near the lower surface  25  of the bottom tub  20   c  or dry air sprays toward the central portion of the bottom tub  20   c , in the related art, there is no big temperature deviation in each position of the lower rack  51  ( FIG.  14 A ). 
     However, the temperature deviation in each position of the upper rack  52  and the top rack  53  reveals that temperature decreases rapidly from the central portion of the upper rack  52  and the top rack  53  to the outer side of the upper rack  52  and the top rack  53 , and there is a big deviation between the central portion and the outer side ( FIG.  14 B  and  FIG.  14 C ). 
     On the contrary, as illustrated in  FIGS.  15 A to  15 C , when the airflow guide  83  is disposed near the lower surface  25  of the bottom tub  20   c , but dry air sprays in a direction parallel with the rear surface  23  of the bottom tub  20   c  and is distributed evenly, in the experimental example of the present disclosure, there is no big temperature deviation in each position of the lower rack  51  ( FIG.  15 A ). 
     Further, the temperature deviation in each position of the upper rack  52  and the top rack  53  reveals that temperature decreases from the central portion of the upper rack  52  and the top rack  53  to the outer side of the upper rack  52  and the top rack  53  gradually and slowly, and there is no big temperature deviation between the central portion and the outer side. 
     In particular, unlike the related art, the present disclosure shows that the temperature of the central portion of the top rack  53  also remains quite high, that the temperature of dry air sprayed along the airflow guide  83  of one embodiment remains constant in the tub  20  entirely/dry air sprayed along the airflow guide  83  of one embodiment may make the temperature inside the entire tub  20  constant and that the effect of drying wash targets is promoted noticeably. 
     Hereafter, the inner structure of the airflow guide  83  of the dishwasher  1  of one embodiment is described with reference to  FIGS.  16  to  24   . 
     As illustrated in  FIG.  16   , the airflow guide  83  of the dishwasher  1  of one embodiment may comprise a lower guide  831  detachably coupled to the duct main body  851  of the connection duct part  85 , an upper guide  832  coupled to the upper side of the lower guide  831 , and a cap cover  834  disposed at the upper side of the upper guide  832  and coupled to the outer surface of the upper guide  832 . 
     The airflow guide  83 , for example, may be divided with respect to the up-down direction (U-D direction). The lower guide  831  constitutes the lower portion of the segment body. The upper guide  832  and the cap cover  834  may constitute the upper portion of the segment body. 
     The upper guide  832  is coupled to the upper side of the lower guide  831  described hereafter, and forms a closed inner flow space formed into a channel in which dry airflow F flows together with the lower guide  831 . 
     To form the inner flow space as illustrated in  FIGS.  17  and  18   , the upper guide  832  may be formed into a container which has a vacant space therein, and the lower surface of which is open entirely. 
     The open lower surface of the upper guide  832  may be coupled with a guide main body  8311  of the lower guide  831  and be closed entirely. By doing so, a closed inner flow space may be formed between the upper guide  832  and the lower guide  831 . 
     At this time, in response to the shape of the lower guide  831 , the outer shape of the upper guide  832  may have a front-rear width greater than a left-right width. 
     The upper guide  832  may be formed into a container that has an upper end surface  8321  formed approximately in parallel with a reference surface  8311   a  of the lower guide  831  described hereafter, and a lower surface being open through an outer wall surface which extends in the downward direction (D-direction) along the circumference of the upper end surface  8321 . 
     At this time, the upper end surface  8321  and the outer wall surface may be integrally formed, and have a uniform thickness as a whole to ensure a maximum inner flow space, and preferably, be manufactured using plastic injection molding. 
     The outer wall surface may comprise a first flat surface part  8322   c  that forms the right side surface of the outer wall surface and is formed into a flat plate, and a second flat surface part  8322   d  that forms the left side surface of the outer wall surface and is formed into a flat plate. The first flat surface part  8322   c  and the second flat surface part  8322   d  may have a symmetrical shape, and be formed into a perpendicular surface or an inclined surface having a slope where a gap between the first flat surface part  8322   c  and the second flat surface part  8322   d  decreases gradually in the upward direction (U-direction). 
     Additionally, a first curved surface part  8322   a  may be continuously formed at the front sides of the first flat surface part  8322   c  and the second flat surface part  8322   d , and a second curved surface part  8322   b  may be continuously formed at the rear sides of the first flat surface part  8322   c  and the second flat surface part  8322   d.    
     The first curved surface part  8322   a  may form the front surface of the upper guide  832 , and for example, have an outer shape of a half cylindrical surface that is convex forward. 
     Like the first curved surface part  8322   a , the second curved surface part  8322   b  may form the rear surface of the upper guide  832 , and for example, have an outer shape of a half cylindrical surface that is convex rearward. 
     The first curved surface part  8322   a  and the second curved surface part  8322   b  may be disposed to have an approximately symmetrical shape. 
     Each of the first curved surface part  8322   a  and the second curved surface part  8322   b  may integrally connect to the upper end surface  8321 , the first flat surface part  8322   c  and the second flat surface part  8322   dc , and form a continuous surface for the upper end surface  8321 , the first flat surface part  8322   c  and the second flat surface part  8322   d.    
     As illustrated, a first camper surface  8322   e  in a camper shape may be formed at an edge formed between the upper end surface  8321  and the outer wall surface. The first camper surface  8322   e  may help to minimize flow loss or noise caused by eddy currents that may be generated at an angular edge side of the inner flow space in which dry airflow F flows. 
     The first camper surface  8322   e  may be a curved surface having a predetermined curvature, or an inclined surface having a predetermined slope. 
     Like the first camper surface  8322   e , a second camper surface  8322   f  in a camper shape may be formed at an edge that is formed by the upper end surface  8321  and the first curved surface part  8322   a  which are met, and at an edge that is formed by the upper end surface  8321  and the second curved surface part  8322   b  which are met. 
     Like the first camper surface  8322   e , the second camper surface  8322   f  may be a curved surface having a predetermined curvature, or an inclined surface having a predetermined slope. 
     A lower end portion  8323  of the upper guide  832  formed around the open lower surface of the upper guide  832  may be formed continuously while its height remains approximately constant from the upper end surface  8321  with respect to the up-down direction (U-D direction) such that the lower end portion  8323  of the upper guide  832  may be inserted and coupled to a misassembly prevention groove  8311   d  of the lower guide  831  described hereafter. 
     A first notch hole  8324  forming the front edge, the rear edge and the upper end edge of the discharge opening  833  may be formed in the lower end portion  8323  of the upper guide  832 . 
     The first notch hole  8324 , as illustrated, may be formed into a notch where the first flat surface part  8322   c  and the second curved surface part  8322   b  of the upper guide  832  are partially cut. 
     The lower end of the first notch hole  8324  is entirely open, and as the upper guide  832  is coupled to the lower guide  831 , the above-described reference surface  8311   a  of the lower guide  831  may be coupled to the open lower end of the first notch hole  8324 , and the reference surface  8311   a  may block the lower end of the first notch hole  8324 . 
     The upper end edge of the first notch hole  8324  may extend approximately in parallel with the reference surface  8311   a  of the lower guide  831  and may extend linearly. 
     The front edge of the first notch hole  8324  may be formed at the first flat surface part  8322   c  and extend linearly along the up-down direction (U-D direction). The rear edge of the first notch hole  8324  may be formed at the second curved surface part  8322   b  and extend linearly along the up-down direction (U-D direction). 
     A rear corner part formed by the upper end edge and the rear edge which are met, and a front corner part formed by the upper end edge and the front edge which are met may respectively have a curved edge having a predetermined curvature. 
     A first holding hole  8325  which is formed into a rectangular penetration hole and to which the upper guide holding projection  8312   g  of the lower guide  831  is held and coupled may be formed at the first curved surface part  8322   a  of the upper guide  832 , near the lower end portion  8323  of the upper guide  832 . 
     As illustrated in  FIG.  17   , the outer shape of the upper guide  832  is approximately symmetrical with respect to the front-rear direction (F-R direction), but the first notch hole  8324  and the first holding hole  8325  are formed in an asymmetrical position with respect to the front-rear direction (F-R direction). The first notch hole  8324  and the first holding hole  8325  may serve as a means of preventing the misassembly of the upper guide  832  to the lower guide  831 . 
     Additionally, at least one cap cover holding projection  8326  for fastening the cap cover  834  described hereafter may be integrally formed at the second flat surface part  8322   d  of the upper guide  832 . 
     As described hereafter, the cap cover  834  may be coupled to the outer surface of the upper guide  832 . At least one cap cover holding projection  8326  may have a lamp surface having a predetermined angle with respect to the second flat surface part  8322   d , and a step surface formed approximately perpendicularly with respect to the second flat surface part, to ensure ease of coupling and prevent ease of separation. 
     As illustrated in  FIG.  16   , the cap cover  834  may be provided with a second holding hole  8345  that is formed near the lower end portion  8343  in a way that penetrates the inside and the outside of the cap cover  834 . 
     The second holding hole  8345  may be formed into a rectangular penetration hole having a width and a height at which the cap cover holding projection  8326  can be inserted into the second holding hole  8345  at a time of coupling the upper guide  832  and the cap cover  834 , and like the cap cover holding projection  8326 , may be disposed higher than the upper guide holding projection  8312   g  with respect to the up-down direction. 
     By doing so, the cap cover holding projection  8326  and the second holding hole  8345  may clearly distinguish from the upper guide holding projection  8312   g  because of the difference in their heights, and the misassembly of the cap cover  834  having a symmetrical shape with respect to the front-rear direction (F-R direction) may be prevented effectively. 
     Additionally, the upper guide  832  of the airflow guide  83  of one embodiment may be provided with a blocking rib  8328  as a first means of minimizing the inflow of wash water into the airflow guide  83  and the connection duct part  85  through the discharge opening  833 . 
     As illustrated in  FIGS.  17  and  18   , the blocking rib  8328  may comprise a first rib  8328   a  that extends in a shade shape along the upper end edge, the front edge and the rear edge of the first notch hole  8324 . 
     The first rib  8328   a  extends continuously along the edges of the first notch hole  8324  and protrude approximately perpendicularly with respect to the first flat surface part  8322   c  of the upper guide  832 . Preferably, the first rib  8328   a  may be formed integrally on the first flat surface part  8322   c  and the second curved surface part  8322   b  of the upper guide  832 . 
     One end portion of the first rib  8328   a  may be formed at the rear edge of the first notch hole  8324 , and the other end portion of the first rib  8328   a  may be formed at the front edge of the first notch hole  8324 . The first rib  8328   a  may extend in a continuous protruding wall shape, between one end portion and the other end portion thereof, to serve as a shade surrounding the first notch hole  8324  approximately entirely. 
     However, to prevent interference with a first edge wall  8311   b  of the lower guide  831 , one end portion and the other end portion of the first rib  8328   a  may be respectively spaced a predetermined height from the lower end portion  8323  of the upper guide  832  in the upward direction (U-direction). 
     The first rib  8328   a  may help to minimize the fall of wash targets from the storage part after a wash or the passage of wash water scattered after a fall through the first notch hole  8324 . 
     To this end, a horizontal rib of the first rib  8328   a , formed at least at the upper end edge of the first notch hole  8324 , may horizontally protrude past the first edge wall  8311   b  of the lower guide  831  and the reference surface  8311   a , as illustrated in  FIG.  17   . 
     That is, the horizontal portion of the first rib  8328   a  may extend to cover the first edge wall  8311   b  and the reference surface  8311   a  with respect to the up-down direction (U-D direction), and in the state where the airflow guide  83  is installed completely, the first edge wall  8311   b  and the reference surface  8311   a  are covered and by the first rib  8328   a  and is not be seen, when view from above. 
     Accordingly, the flow of wash water, which falls perpendicularly after wash targets are washed, collides with the first edge wall  8311   b  and then is scattered, into the first notch hole  8324  may be minimized. 
     However, wash water scattered in the washing stage or the rinsing stage may fall in a direction different from the perpendicular direction. That is, wash water avoiding the first rib  8328   a , colliding with the first edge wall  8311   b  and being scattered is likely to flow into the first notch hole  8324 . 
     To prevent this from happening, the blocking rib  8328  may further comprise at least one second rib  8328   b  that extends across the inside the first notch hole  8324 , along the front-rear direction (F-R direction). 
       FIGS.  17  to  18    exemplarily show an embodiment provided with a pair of second ribs  8328   b  that are spaced in the up-down direction (U-D direction). Hereafter, an embodiment provided with a pair of second ribs  8328   b , as illustrated, is described for convenience, but not limited. 
     Each of the pair of second ribs  8328   b  may extend across the inside the first notch hole  8324  and have the same shape. 
     At this time, to prevent deterioration in the spray efficiency of dry air spraying, the up-down thickness of each of the second ribs  8328   b  may be much less than the front-rear length. 
     Additionally, to minimize the flow of perpendicularly falling wash water into the first notch hole  8324 , caused by the collision with the first edge wall  8311   b  and scattering of the wash water, the pair of second ribs  8328   b , like the first rib  8328   a , may protrude horizontally past the first edge wall  8311   b  and the reference surface  8311   a  of the lower guide  831 . That is, the horizontal position of the left end portion of the horizontal rib of the first rib  8328   a  may be the same as the horizontal position of the left end portion of the pair of second ribs  8328   b.    
     However, to cover the inside of the first notch hole  8324  entirely with respect to the front-rear direction (F-R direction), the rear end portion forming one end portion of each of the second ribs  8328   b  may integrally connect to the rear edge of the first notch hole  8324 , and the front end portion forming the other end portion of each of the second rib  8328   b  may integrally connect to the front edge of the first notch hole  8324 . 
     The shape of the second rib  8328   b  may help to prevent the inflow of wash water, in a way that the wash water is blocked by the second rib  8328   b  again, even if the wash water collides with the first edge wall  8311   b  by avoiding the first rib  8328   a  and is scattered. 
     Additionally, since the thickness of the pair of second ribs  8328   b  is much less than the front-rear length thereof, the second ribs have relatively low strength, and is likely to be damaged by small magnitude of external force. To prevent such damage, a bridge rib  8328   c  is disposed between the front end portion and the rear end portion of the second rib  8328   b  and connects the pair of second ribs  8328   b  mutually to reinforce the second ribs. In the illustrative embodiment, the bridge rib  8328   c  extends only between the pair of second ribs  8328   b , but may further extend to the upper end edge of the first notch hole  8324 . 
     Further, the upper guide  832  of the airflow guide  83  of one embodiment may be provided with at least one blocking wall  8329  that is disposed in the inner flow space of the upper guide  832 , as a second means of minimizing the flow of wash water into the airflow guide  83  and the connection duct part  85  through the discharge opening  833 . 
     At least one blocking wall  8329  may help to prevent and minimize the movement of the droplets of wash water, which has passed through the blocking rib  8328  and flown into the airflow guide  83  after the wash water&#39;s collision and scattering, toward the lower portion of the upper end surface  8321  of the upper guide  832  or toward a duct coupling part  8312  of the lower guide  831 . 
     To this end, as illustrated in  FIGS.  17  and  18   , at least one blocking wall  8329  may be disposed in the form of a barrier that extends downward from the lower portion of the upper end surface  8321  of the upper guide  832 , to at least partially block the upper portion side of the first notch hole  8324  forming the discharge opening  833 . 
     That is, the up-down position of the lower end of at least one blocking wall  8329  may be between the upper end edge of the first notch hole  8324  and the reference surface  8311   a  of the lower guide  831 . Accordingly, when the inside of the first notch hole  8324  is viewed from the outside, the duct coupling part  8312  of the lower guide  831  is entirely covered by at least one blocking wall  8329  and is not be seen visually from the outside. 
     Thus, among droplets of wash water being scattered and flowing into the airflow guide  83 , droplets bouncing upward collide with at least one blocking wall  8329  and flow downward along at least one blocking wall  8329  by using gravity. 
     The droplets prevented from coming in and falling downward along at least one blocking wall  8329  need to be discharged out of the airflow guide  83  again. To this end, the lower end edge of at least one blocking wall  8329  may extend toward a channel guide surface  8313  of the lower guide  831 . Additionally, at least one blocking wall  8329  may be disposed in the channel guide surface area with respect to the horizontal direction, as described hereafter. A relative position relationship between the blocking wall  8329  and the channel guide surface  8313  of the lower guide  831  is described hereafter with reference to  FIGS.  23  and  24   . 
     Further, as shown in the illustrative embodiment, the blocking wall  8329  may comprise a first blocking wall  8329   a  disposed relatively close to the first notch hole  8324 , and a second blocking wall  8329   b  disposed farther from the first notch hole  8324  than the first blocking wall  8329   a , for example. 
     As described above, at least one blocking wall  8329  is disposed in the inner flow space where dry airflow F flows. 
     Accordingly, if a single blocking wall covers the upper portion side of the first notch hole  8324  entirely, the flow resistance of dry airflow F may increase, resulting in deterioration of air blowing efficiency. 
     To prevent deterioration in air blowing efficiency, caused by an increase in flow resistance, the blocking wall  8329  may be divided into the first blocking wall  8329   a  and the second blocking wall  8329   b  to complementarily cover the upper portion side of the first notch hole  8324 . 
     That is, the first blocking wall  8329   a  may be disposed to partially cover the upper portion side of the first notch hole  8324 , and the second blocking wall  8329   b  may be disposed to at least partially cover the remaining portion of the first notch hole  8324  that is not cover by the first blocking wall  8329   a.    
     The upper end edge of the first blocking wall  8329   a  may integrally connect to the lower portion of the upper end surface  8321  of the upper guide  832  and be formed into a curved surface that is convex in a direction farther from the first notch hole  8324  forming the discharge opening  833 , from one end edge  8329   a   1  of the first blocking wall  8329   a  toward the other end edge  8329   a   2  thereof. 
     Likewise, the upper end edge of the second blocking wall  8329   b  may integrally connect to the lower portion of the upper end surface  8321  of the upper guide  832  and be formed into a curved surface that is convex in a direction farther from the first notch hole  8324  forming the discharge opening  833 , from one end edge  8329   b   1  of the second blocking wall  8329   b  toward the other end edge  8329   b   2  thereof. 
     That is, the flow direction of air having passed through the upper end  8511  of the connection duct part  85  and flown into the inner flow space changes toward the first notch hole  8324  forming the discharge opening  833 , as described hereafter. That is, in the process of changing a flow direction, a rotation speed component is produced in dry airflow F. 
     To prevent a rapid change in the flow space and produce a rotation speed component effectively in the process of changing a flow direction, the first blocking wall  8329   a  and the second blocking wall  8329   b  may also serve as a flow guide. 
     To minimize flow resistance and serve as a flow guide effectively, the first blocking wall  8329   a  and the second blocking wall  8329   b  may be formed into a curved surface having predetermined curvature, and have a uniform thickness from one end edge  8329   a   1 ,  8329   b   1  to the other end edge  8329   a   2 ,  8329   b   2  of each of the first blocking wall  8329   a  and the second blocking wall  8329   b.    
     However, detailed shapes of the first blocking wall  8329   a  and the second blocking wall may differ from each other. 
     That is, one end edge  8329   a   1  of the first blocking wall  8329   a  may be a fixation end portion that integrally connects to the front edge of the first notch hole  8324 , and the other end edge  8329   a   2  of the first blocking wall  8329   a  may be a free end portion that does not connect to the outer wall surface of the upper guide  832 . 
     One end edge  8329   a   1  of the first blocking wall  8329   a  integrally connects to the front edge of the first notch hole  8324 , as described above, such that droplets of wash water are prevented from flowing directly into an upper end  8312   a  of the duct coupling part  8312  of the lower guide  831  and the upper end  8511  of the connection duct part  85  through the front edge side of the first notch hole  8324 , in a minimum distance. 
     Additionally, the up-down position of a lower end edge  8329   a   3  of the first blocking wall  8329   a  may change from one end edge  8329   a   1  of the first blocking wall  8329   a  to the other end edge  8329   a   2  thereof. For example, the lower end edge  8329   a   3  of the first blocking wall  8329   a  may have a step. 
     Specifically, the lower end edge  8329   a   3  of the first blocking wall  8329   a  may comprise a first edge  8329   a   31  the up-down position of which is maintained approximately in a first position, and a second edge  8329   a   32  the up-down position of which is maintained approximately in a second position. At this time, the first position is lower than the second position, thereby forming a step. 
     The first edge  8329   a   31 , as illustrated, may be disposed closer to the one end edge of the first blocking wall  8329   a  and the front edge side of the first notch hole  8324  than the second edge  8329   a   32 . 
     That is, the up-down position of the lower end edge of the first blocking wall  8329   a , formed near the front edge side of the first notch hole  8324 , may remain lower. By doing so, droplets of wash water may be further prevented from directly flowing into the upper end  8312   a  of the duct coupling part  8312  of the lower guide  831  and the upper end  8511  of the connection duct part  85 , into which dry airflow F comes through the front edge side of the first notch hole  8324 , in a minimum distance. 
     As described hereafter, the first position of the first edge  8329   a   31  and the second position of the second edge  8329   a   32  may be lower than the up-down position of the upper end of a division wall provided at the lower guide  831 . That is, the lower end edge  8329   a   3  of the first blocking wall  8329   a  may entirely extend to a position lower than the up-down position of the upper end of the division wall  8314 . 
     Additionally, the second blocking wall  8329   b  may be disposed in the state of separating from the first blocking wall  8329   a  and disposed between the first blocking wall  8329   a  and the second flat surface part  8322   d.    
     As illustrated, each of one end edge  8329   b   1  and the other end edge  8329   b   2  of the second blocking wall  8329   b  may be a free end portion that does not connect to the outer wall surface of the upper guide  832 . 
     However, the other end edge  8329   b   2  of the second blocking wall  8329   b  may be disposed closer to the rear edge of the first notch hole  8324  than the other end edge  8329   a   2  of the first blocking wall  8329   a  with respect to the front-rear direction, as described above. 
     Further, the up-down position of a lower end edge  8329   b   3  of the second blocking wall  8329   b  may remain constant approximately from one end edge  8329   b   1  to the other end edge  8329   b   2  and remain higher than the second edge  8329   a   32  of the first blocking wall  8329   a.    
     However, like the up-down position of the lower end edge of the first blocking wall  8329   a , the up-down position of the lower end edge  8329   b   3  of the second blocking wall  8329   b  may be entirely lower than the up-down position of the upper end of the division wall  8314  provided at the lower guide  831 . 
     Further, the cap cover  834  disposed at the upper side of the upper guide  832  may be coupled to the outer surface of the upper guide  832  to protect the upper guide  832 . 
     The upper guide  832  is disposed lower than the storage part that accommodates wash targets, and the upper end surface  8321  and the outer wall surface are disposed in a way that the upper end surface  8321  and the outer wall surface are mostly exposed to the wash space  21  of the tub  20 . However, as described above, the upper guide  832  is made of a plastic material having relatively low strength. 
     Accordingly, the upper guide  832  may be broken directly due to a collision with wash targets that may fall from the storage part between the washing stage and the rinsing stage or may fall while the user withdraws the storage part. 
     The cap cover  834  is coupled to the upper side of the outer surface of the upper guide  832  to prevent the damage to the upper guide  832 , caused by a collision with wash targets. 
     To this end, the cap cover  834  may be made of a material having higher breaking strength and corrosion resistance than the upper guide  832 , and preferably, may be formed with a sheet of metal such as stainless steel and the like. 
     To be coupled to the outer surface of the upper guide  832 , the cap cover  834  may have a shape corresponding to the shape of the outer surface of the upper guide  832 . 
     Accordingly, like the upper guide  832 , the cap cover  834  has a vacant space therein, and is formed into a container that is entirely open. 
     The upper guide  832  may be inserted and coupled through an open lower surface of the cap cover  834 . 
     In response to the shape of the upper guide  832 , the outer shape of the cap cover  834  may have a front-rear width greater than a left-right width. 
     Specifically, the cap cover  834  may comprise an upper end surface  8341  formed in parallel with the upper end surface  8321  of the upper guide  832 , and an outer wall surface extending along the circumference of the upper end surface  8321  in the downward direction (D-direction). 
     Like the upper guide  832 , the outer wall surface of the cap cover  834  may comprise a first flat surface part  8342   c  forming a right side surface and being formed into a flat plate, and a second flat surface part  8342   d  forming a left side surface and being formed into a flat plate. 
     The first flat surface part  8342   c  and the second flat surface part  8342   d  may have a symmetrical shape, and be formed into a perpendicular surface or an inclined surface having a slope where a gap between the first flat surface part  8342   c  and the second flat surface part  8342   d  decreases gradually in the upward direction (U-direction). 
     Additionally, a first curved surface part  8342   a  may be formed at the front sides of the first flat surface part  8342   c  and the second flat surface part  8342   d , and a second curved surface part  8342   b  may be continuously formed at the rear sides of the first flat surface part  8342   c  and the second flat surface part  8342   d.    
     The first curved surface part  8342   a  may form the front surface of the cap cover  834 , and for example, have an outer shape of a half cylindrical surface that is convex forward in response to the shape of the first curved surface part  8322   a  of the upper guide  832 . 
     The second curved surface part  8342   b  may form the rear surface of the cap cover  834 , and for example, have an outer shape of a half cylindrical surface that is convex forward in response to the shape of the second curved surface part  8322   b  of the upper guide  832 . 
     Each of the first curved surface part  8342   a  and the second curved surface part  8342   b  may be integrally formed on the upper end surface  8341 , the first flat surface part  8342   c  and the second flat surface part  8342   d , and form a continuous surface for the upper end surface  8341 , the first flat surface part  8342   c  and the second flat surface part  8342   d.    
     Additionally, in response to the upper guide  832 , a camper surface  8342   e  in a camper shape may be formed at an edge formed between the upper end surface  8341  and the outer wall surface. 
     However, unlike the upper guide  832 , the cap cover  834  is not provided with a component corresponding to the second camper surface  8322   f  of the upper guide  832 . 
     The lower end portion  8343  of the outer wall surface of the cap cover  834  may extend to the lower end portion  8323  of the outer wall surface of the upper guide  832  to cover the outer wall surface of the upper guide  832  entirely. Accordingly, at a time of coupling the cap cover  834  to the lower guide  831 , the lower end portion  8343  of the cap cover  834  and the lower end portion  8323  of the upper guide  832  may be inserted into the misassembly prevention groove  8311   d  of the lower guide  831 , together. 
     Additionally, a second notch hole  8344  may be formed in the lower end portion  8343  of the cap cover  834  and have a shape corresponding to that of the first notch hole  8324  of the upper guide  832 . 
     Like the first notch hole  8324 , the second notch hole  8344  may be formed into a notch where the first flat surface part  8342   c  and the second curved surface part  8342   b  of the cap cover  834  are partially cut. 
     Since the second notch hole  8344  has the same shape as the first notch hole  8324 , a detailed shape of the second notch hole  8344  is not described. 
     However, a holding jaw  8344   a  may be provided at the lower end of the front edge of the second notch hole  8344  and protrude to the inside of the second notch hole  8344 . 
     The holding jaw  8344   a  is a portion that is held and coupled to the other end portion of the above-described first rib  8328   a , and the right side portion of the cap cover  834  may be coupled to the upper guide  832  through the holding jaw  8344   a.    
     Additionally, the second holding hole  8345  may be formed near the lower end portion  8323  of the upper guide  832 , at the second flat surface part  8342   d  of the cap cover  834 , and formed into a rectangular penetration hole to which the above-described cap cover holding projection  8326  of the upper guide  832  is held and coupled. 
     As the cap cover holding projection  8326  is held and coupled to the second holding hole  8345 , the left side portion of the cap cover  834  may be coupled to the upper guide  832 . 
     That is, the cap cover  834  may be coupled to two spots of the upper guide  832  at least though the holding jaw  8344   a  and the cap cover holding projection  8326 . 
     Further, the lower guide  831 , as illustrated in  FIGS.  19  to  21   , may comprise a guide main body  8311  formed into an approximately flat plate. 
     The guide main body  8311  may have an outer shape in which a front-rear (F-R direction) width is greater than a left-right (Le-Ri direction) width, in the state where the guide main body  8311  is disposed at the connection duct part  85 . 
     At this time, the left and right edges of the outer edge forming the outer shape of the guide main body  8311  may have a linear shape, the front edge may have a circular arc shape that is convex forward, and the rear edge may have a circular arc shape that is convex rearward. 
     The left and right edges of the guide main body  8311  may have shapes that are approximately symmetrical to each other and parallel with each other, and the front and rear edges of the guide main body  8311  may have shapes that are symmetrical to each other. 
     The reference surface  8311   a  serving as a lower end edge of the above-described discharge opening  833  may be formed at the right edge side of the guide main body  8311 . The reference surface  8311   a , as illustrated, may be provided in the form of a flat surface that extends in a direction farther from the discharge opening  833  along the horizontal direction, and extend to the lower end of the channel guide surface  8313  described hereafter from the right edge. 
     Further, the first edge wall  8311   b  may be formed at least partially at the left, right, front and rear edges of the guide main body  8311  and extend from the reference surface  8311   a  in the upward direction (U-direction) by a predetermined height. 
     The first edge wall  8311   b , as illustrated, may be formed continuously along the outer edge of the guide main body  8311 . However, the first edge wall  8311   b  may not be formed at least in the discharge opening area  833  not to prevent the spray of dry air, as illustrated in  FIG.  19   . 
     Further, a misassembly prevention groove  8311   d  may be formed inside the first edge wall  8311   b  and be depressed further downward (in the D-direction) than the reference surface  8311   a , with respect to the up-down direction (U-D direction), and serve as a misassembly prevention part of the upper guide  832 . At this time, the height at which the misassembly prevention groove  8311   d  is depressed from the reference surface  8311   a , may remain constant approximately along the first edge wall  8311   b.    
     The lower end portion  8323  of the upper guide  832 , which is described hereafter, may be inserted and coupled to the misassembly prevention groove  8311   d . Accordingly, the misassembly prevention groove  8311   d  may have a shape and a size corresponding to the shape and the size of the lower end portion  8323  of the upper guide  832 . As described above, the shape of the lower end portion  8323  of the upper guide  832  is formed continuously except for the area where the first notch hole  8324  forming the discharge opening  833  is formed, i.e., the area where the reference surface  8311   a  is formed. In response, the misassembly prevention groove  8311   d  may be formed continuously along the first edge wall  8311   b.    
     At this time, the shape of the lower end portion  8323  of the upper guide  832  may be asymmetrical to the shape of the misassembly prevention groove  8311   d  with respect to the front-rear direction (F-R direction). Accordingly, the lower end portion  8323  of the upper guide  832  may not be coupled and fastened to the misassembly prevention groove  8311   d  in a direction different from a predetermined direction. By doing so, a misassembly between the upper guide  832  and the lower guide  831  may be prevented effectively. 
     Further, a second edge wall  8311   c  may be formed at the front edge of the guide main body  8311  and extend from the reference surface  8311   a  in the downward direction (D-direction) to have a predetermined height. 
     The second edge wall  8311   c , as illustrated, may be formed continuously into a cylinder along the circular arc-shaped front edge of the guide main body  8311 , and the lower end potion of the second edge wall  8311   c  may extend past a lower end  8312   b  of the duct coupling part  8312  that is described below. 
     That is, the second edge wall  8311   c  may be formed in a way that surrounds the outer surface of the below-described duct coupling part  8312  at least partially. At this time, the second edge wall  8311   c  is formed in the state of being separated and spaced from the duct coupling part  8312 , and a predetermined space may be formed between the second edge wall  8311   c  and the duct coupling part  8312 . As described below, an upper end  8522  of a fastening nut  852  may be inserted into the space at least partially. 
     A release prevention part  8311   e  may be provided on the second edge wall  8311   c , and based on an interaction with the fastening nut  852 , keep the lower guide  831  fixed to the fastening nut  852  and prevent the lower guide  831  from escaping from a fixed position. 
     As described hereafter, the lower guide  831  is detachably coupled to the duct main body  851  of the connection duct part  85  based on a two-stage coupling manipulation, without an additional coupling member. The two-stage coupling manipulation may comprise an up-down perpendicular movement manipulation and a circumferential rotational movement manipulation, for example. 
     The release prevention part  8311   e  prevents a relative rotation of the lower guide  831  in a direction opposite to the direction of the rotational movement in the two-stage coupling manipulation, i.e., prevents the lower guide  831  from escaping from the fixed position after the second-stage coupling manipulation including the perpendicular movement manipulation and the rotational movement manipulation is completed. 
     The release prevention part  8311   e , as illustrated exemplarily, may be formed integrally on the second edge wall  8311   c , and prevent the relative rotation of the lower guide  831  in a direction opposite to the direction of the rotational movement of the two-stage coupling manipulation, in the form of an elastic hook. 
     The lower guide  831 , as described above, is directly coupled to the duct main body  851  of the connection duct part  85 , using a pipe coupling method. 
     To this end, the lower guide  831  may comprise a cylindrical duct coupling part  8312  to which the upper end  8511  of the cylinder-shaped duct main body  851  is inserted and detachably coupled. 
     In response to the shape of the duct main body  851 , the duct coupling part  8312  may be formed into a cylinder the central axis C of which extends in parallel with the up-down direction (U-D direction). For the upper end  8511  of the duct main body  851  to be inserted into and pass through the duct coupling part  8312 , the inner diameter of the lower end  8312   b  of the duct coupling part  8312  may be greater than or the same as the outer diameter of the upper end  8511  of the duct main body  851 . 
     The duct coupling part  8312  may be formed integrally at the guide main body  8311 , and disposed near the circular arc-shaped rear edge of the guide main body  8311 . That is, the duct coupling part  8312  may be biased toward the rear side of the guide main body  8311  with respect to the front-rear direction (F-R direction). 
     The upper end  8312   a  of the cylindrical duct coupling part  8312 , from which dry air is discharged, may be formed in a position that protrudes from the guide main body  8311 , in the upward direction (U-direction). Preferably, the upper end  8312   a  of the duct coupling part  8312  protrudes to and is exposed to the inner flow space formed between the guide main body  8311  of the lower guide  831  and the upper guide  832 . 
     At this time, in the state where the coupling of the upper end  8511  of the connection duct part  85  is completed, the position of the upper end  8312   a  of the duct coupling part  8312  may be formed in a position lower than the position of the upper end  8511  of the connection duct part  85  with respect to the up-down direction (U-D direction). 
     That is, the upper end  8511  of the connection duct part  85 , as illustrated in  FIG.  22   , may protrude further upward than the upper end  8312   a  of the duct coupling part  8312 . Since the upper end  8511  of the connection duct part  85  remains higher than the upper end  8312   a  of the duct coupling part  8312  as described above, the upward movement of droplets of wash water coming in through the discharge opening  833  along a gap between the outer circumferential surface of the connection duct part  85  and the inner circumferential surface of the duct coupling part  8312 , caused by a capillary phenomenon, may be fundamentally blocked. 
     Additionally, the central axis of the duct coupling part  8712  may be spaced from the first notch hole  8724  with respect to the front-rear direction (F-R direction) or the horizontal direction. In the embodiment, the central axis of the duct coupling part  8712  may be disposed further forward than the first notch hole  8724 . That is, at least the front edge of the first notch hole  8724  is disposed further rearward than the central axis of the duct coupling part  8712 . Accordingly, a portion of the upper end  8712   a  of the duct coupling part  8712 , exposed outward through the discharge opening  873  or the first notch hole  8724 , may be minimized, and the flow of the reversely incoming wash water, having passed through the discharge opening  873 , into the duct coupling part  8712  through the upper end  8712   a  of the duct coupling part  8712  may be minimized. 
     Further, a first guide groove  8312   d  that extends in a linear shape along the up-down direction (U-D direction), and a second guide groove  8312   e  that extends in a circular arc shape along the circumferential direction may be formed on an inner circumferential surface  8312   c  of the duct coupling part  8312 . 
     As illustrated, the upper end of the first guide groove  8312   d  integrally connects to one end portion of the second guide groove  8312   e.    
     The lower guide  831 , as described above, is coupled to the duct main body  851  of the connection duct part  85 , based on the two-stage coupling manipulation comprising the up-down perpendicular movement manipulation and the circumferential rotational movement manipulation. 
     The first guide groove  8312   d  extending along the up-down direction (U-D direction) in a linear shape guides the up-down perpendicular movement of the lower guide  831 , and the second guide groove  8312   e  extending along the circumferential direction in a circular arc shape guides the circumferential rotational movement of the lower guide  831 . 
     A guide projection  8516  may be integrally provided on the outer circumferential surface of the duct main body  851  inserted into and coupled to the duct coupling part  8312  of the lower guide  831 , and protrude toward the inner circumferential surface of the connection duct part  85  and be inserted into the first guide groove  8312   d  and the second guide groove  8312   e  of the connection duct part  85 . 
     Accordingly, the guide projection  8516 , as described hereafter, may be first inserted into the first guide groove  8312   d  at a time of coupling the lower guide  831  and the duct main body  851 . 
     As a result, in the state where the guide projection  8516  of the duct main body  851  is inserted into the first guide groove  8312   d , the lower guide  831  may move perpendicularly in the downward direction (D-direction). 
     As the up-down perpendicular movement manipulation of the two-stage coupling manipulation starts, the first guide groove  8312   d  moves in the downward direction (D-direction) along the guide projection  8516  that stands still. As the guide projection  8516  reaches the upper end of the first guide groove  8312   d , the lower guide  831  may not move in the downward direction (D-direction) any longer because of the guide projection  8516 &#39;s action. 
     At this time, since the guide projection  8516  has arrived at one end portion of the second guide groove  8312   e , the lower guide  831  may not make a downward (D-direction) movement while making a circumferential rotational movement in the two-stage coupling manipulation. 
     As the lower guide  831  rotates for the circumferential rotational movement manipulation of the two-stage coupling manipulation, the second guide groove  8312   e  moves along the guide projection  8516  that stands still. As the guide projection  8516  reaches the other end portion of the second guide groove  8312   e , the lower guide  831  may not rotate in the circumferential direction any longer because of the guide projection  8516 &#39;s action. 
     When the lower guide  831  does not rotate any longer as described above, the lower guide  831  and the duct main body  851  may be coupled completely, the lower guide  831  may be disposed in a fixed position completely, and without an additional coupling member or an additional fastening member, the lower guide  831  and the duct main body  851  may be coupled. 
     As illustrated in  FIGS.  19  and  20   , a stopper projection  8312   f  may be integrally formed on the inner circumferential surface  8312   c  of the duct coupling part  8312 , at the other end portion side of the second guide groove  8312   e , and may form stick-slip in relation to the movement of the guide projection  8516 , and after the guide projection  8516  reaches the other end portion of the second guide groove  8312   e , stop a relative rotation of the lower guide  831  in the opposite direction. 
     Thus, as long as external force of greater than a specific level is not applied, the stopper projection  8312   f  may prevent the guide projection  8516  from escaping from the other end portion of the second guide groove  8312   e.    
     However, when the coupling of the lower guide  831  and the setting of the right position of the lower guide  831  are completed in the state where the guide projection  8516  is inserted into the second guide groove  8312   e , the airflow guide  83  may not make a self weight-induced movement due to a hold between the second guide groove  8312   e  and the guide projection  8516 . 
     However, as strong external force such as a collision of a wash target falling in the washing stage or the rinsing stage and the like is applied, the second guide groove  8312   e  and the guide projection  8516  may be easily released from the hold therebetween. 
     Even without strong external force, the lower guide  831  and the airflow guide  83  are highly likely to clatter because of a gap between the duct coupling part  8312  of the lower guide  831  and the duct main body  851  of the connection duct part  85 , caused by manufacturing tolerance. 
     The clatter occurs due to a gap-induced relative displacement or relative movement of the lower guide  831  with respect to the connection duct part  85 . 
     According to the present disclosure, at least one protruding rib may be included as a means of minimizing a gap between the lower guide  831  and the connection duct part  85 , in particular, a means of limiting a relative downward movement to the connection duct part  85 . 
     Referring to  FIG.  21   , at least one protruding rib may protrude downward from the lower end  8312   b  of the duct coupling part  8312  toward a male screw thread  8541  provided on the outer circumferential surface of the duct main body  851  of the connection duct part  85 . 
     That is, the airflow guide  83  of the dishwasher of one embodiment may adjust the amount of a generated gap and limit a relative downward movement through the male screw thread  8514  of the duct main body  851  disposed at the lower portion side of the duct coupling part  8312 . 
     Accordingly, as a relative downward movement of the airflow guide  83 , i.e., a relative downward movement of the lower guide  831 , is made, the relative movement of the lower guide  831  may be limited in a way that the lower end surface of at least one protruding rib contacts one side surface of the male screw thread  8514 . 
       FIG.  21    shows at least one protruding rib comprising a first protruding rib  8312   h   1 , a second protruding rib  8312   h   2  and a third protruding rib  8312   h   3  that are disposed around a circular opening formed at the lower end  8312   b  of the duct coupling part  8312  of the lower guide  831  at regular intervals, for example. Hereafter, at least one protruding rib comprising the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  is described but not limited. 
     As illustrated, the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3 , disposed at regular intervals along the circumferential direction, may have the same cross-sectional shape. For example, a cross section in a direction perpendicular to the direction in which the protruding rib protrudes may have an approximately rectangular shape. 
     That is, the protruding ribs  8312   h   1 ,  8312   h   2 ,  8312   h   3  may be formed into a rectangular pillar having the same circumferential width and the same radial width and protrude from the lower end  8312   b  of the duct coupling part  8312 . 
     However, the heights at which the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  protrude downward from the lower end  8312   b  of the duct coupling part  8312  may be set differently. 
     That is, the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  protrude toward the male screw threads  8514  that extend spirally in different positions. A maximum height of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may differ such that a gap between the first, second and third protruding ribs  8312   h   1 ,  8312   h   2 ,  8312   h   3  and the male screw thread  8514  remains constant in the position of each of the protruding ribs. 
     For example, the first protruding rib  8312   h   1  may protrude at a first height that is the smallest value, the second protruding rib  8312   h   2  may protrude at a second height greater than the first height, and the third protruding rib  8312   h   3  may protrude at a third height greater than the second height. 
     The first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3 , as described hereafter, may be disposed clockwise consecutively, when viewed from the upper portion side of the airflow guide  83 . 
     Additionally, the lower end surfaces of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be provided in the form of an inclined surface, in response to the shape of one side surface of the male screw thread  8514  that extends spirally. 
     Detailed configurations of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  are described below with reference to  FIGS.  28  and  29   . 
     Further, at least one upper guide holding projection  8312   g  may be integrally formed on the outer circumferential surface of the duct coupling part  8312  and couple the upper guide  832  described hereafter and the lower guide  831  mutually. 
     At least one upper guide holding projection  8312   g  may have a lamp surface having a predetermined inclination angle with respect to the outer circumferential surface of the duct coupling part  8312 , and a stepped surface formed approximately perpendicularly with respect to the outer circumferential surface of the duct coupling part  8312 , such that a coupling based on the downward movement of the upper guide  832  is readily ensured but a separation based on the upward movement of the upper guide  832  is not readily ensured. 
     Further, the channel guide surface  8313  guiding dry airflow F, having passed through the upper end  8312   a  of the duct coupling part  8312 , to the discharge opening  833  may be formed at the front side of the duct coupling part  8312 . 
     As illustrated in  FIG.  19   , a curved surface of an inclined surface may be formed continuously between the upper end and the lower end of the channel guide surface  8313  to minimize flow loss of dry airflow F and the amount of generated flow noise. The upper end of the channel guide surface  8313  may extend to the approximately same height as the upper end  8312   a  of the duct coupling part  8312 , and the lower end may extend in a curved surface shape or an inclined surface shape to the reference surface  8311   a  of the lower guide  831 . 
     Specifically, the channel guide surface  8313  may be a concave surface that is provided in a way that the channel guide surface  8313  is surrounded by the rear surface of the duct coupling part  8312  and a boundary wall  8313   d.    
     That is, the channel guide surface  8313  may be formed into a concave surface to prevent droplets of wash water, which collide with the first edge wall  8311   b , then are scattered and come in, from moving to the duct coupling part  8312  and the connection duct part  85 , after the droplets collide with the channel guide surface  8313  and are scattered again. 
     That is, the shape of the channel guide surface  8313  may be formed such that a gap between the channel guide surface  8313  and the upper end surface  8321  of the upper guide  832  remains big to prevent the rescattered droplets of the wash water from bouncing. 
     For example, the channel guide surface  8313  may comprise a first inclined surface  8313   a  extending from the reference surface  8311   a  in a direction across the duct coupling part  8312 , a second inclined surface  8313   c  having an extension width much less than the first inclined surface  8313   a , and a curved surface part  8313   b  disposed between the first inclined surface  8313   a  and the second inclined surface  8313   c.    
     The first inclined surface corresponds to a portion occupying most of the surface area of the channel guide surface  8313 . Additionally, the reference surface  8311   a  and the first inclined surface  8313   a  are disposed in succession. To suppress the rescattering of wash water to a maximum degree, the first inclined surface  8313   a  is formed into a flat surface having a minimum climb angle. For example, the climb angle of the first inclined surface  8313   a  may be about 10 degrees or so with respect to the reference surface. 
     The curved surface part  8313   b  and the second inclined surface  8313   c  are followed by the first inclined surface  8313   a  to prevent a rapid change in the inner flow path in which dry airflow F flows. 
     The second inclined surface  8313   c , as illustrated, may be formed into a flat surface, like the first inclined surface  8313   a , but has a climb angle much greater than that of the first inclined surface  8313   a.    
     For example, the climb angle of the second inclined surface  8313   c  may be about 80 degrees or so with respect to the reference surface  8311   a.    
     Additionally, the lower guide  831  of the airflow guide  83  of one embodiment may comprise a division wall  8314  that protrudes upward from the upper end  8312   a  of the duct coupling part  8312  as a third means of minimizing the flow of wash water into the airflow guide  83  and the connection duct part  85  through the discharge opening  833 . 
     The division wall  8314  finally blocks droplets of wash water, which have passed through the above-described blocking rib  8328  and blocking wall  8329  in the state of being scattered after a collision, from entering into the duct coupling part  8312 . 
     To this end, the division wall  8314 , as illustrated in  FIGS.  19 ,  20  and  22   , may protrude upward from the upper end  8312   a  of the duct coupling part  8312 , divide the area where the duct coupling part  8312  is formed and the area where the channel guide surface  8313  is formed, and extend in the form of a barrier that blocks the upper end of the duct coupling part  8312 . 
     That is, the division wall  8314  may be boundary wall that is disposed between the duct coupling part area and the channel guide surface area and distinguishes the duct coupling part area from the channel guide surface area. 
     As illustrated, the thickness of the division wall  8314  may remain constant from the right end portion thereof to the left end portion thereof. 
     At this time, the right end portion of the division wall  8314  may be a free end portion, and the left end portion may extend to the boundary wall  8313   d  and integrally connect to the boundary wall  8313   d.    
     Additionally, to minimize flow resistance of dry airflow F moving toward the channel guide surface  8313  past the division wall  8314 , the up-down position of the upper end of the division wall  8314  may remain constant approximately from the right end portion thereof to the left end portion thereof. 
     However, the up-down position of the upper end of the division wall  8314  may be lower than the upper end  8511  of the duct main body  851  and higher than the lower end edge of the blocking wall  8329  of the upper guide  832  such that the division wall  8314  blocks scattered droplets effectively while avoiding interference with the flow of dry airflow F and preventing a rapid increase in the flow resistance of dry airflow F. 
     That is, the up-down position of the upper end of the division wall  8314  may be higher than that of the lower end edge  8329   b   3  of the second blocking wall  8329   b  that is in the highest position of the lower end edge of the blocking wall  8329  of the upper guide  832 . 
     Hereafter, a means of preventing the inflow of wash water, provided at the airflow guide  83  of the dishwasher  1  of one embodiment, is described with reference to  FIGS.  23  and  24   . 
     As describe above, the discharge opening  833  of the airflow guide  83  spraying dry air to the wash space  21  of the tub  20  is open in the wash space  21 . 
     Additionally, since the dry air supply part  80  is in a non-operation state in the washing stage or the rinsing stage, it is highly likely that wash water is scattered in a droplet state and flows into the inner flow space of the airflow guide  83  through the discharge opening  833 . The droplets of the incoming wash water may also be recondensed in the airflow guide  83 , pass through the duct coupling part  8312  and then flow into the dry air supply part  80 . 
     To prevent the inflow of wash water, the airflow guide  83  of one embodiment is provided with a means of preventing the inflow of wash water as follows. 
     The first rib  8328   a  may be provided at the upper end edge, the front edge and the rear edge of the first notch hole  8324  and extend in a shade shape, and at least one second rib  8328   b  may be provided in the first notch hole  8324  and extend across the first notch hole  8324  along the front-rear direction (F-R direction). 
     By doing so, the inflow of droplets of wash water directly passing through the discharge opening  833  or the first notch hole  8324  may be blocked primarily. 
     Further, the first blocking wall  8329   a  and the second blocking wall  8329   b  may be provided in the first notch hole  8324 , and extend downward from the lower portion of the upper end surface  8321  of the upper guide  832  to at least partially cover the upper portion side of the discharge opening  833  or the first notch hole  8324 . 
     Among droplets of wash water that flows into the airflow guide  83  in the state of being scattered through the first notch hole  8324 , droplets bouncing upward collide with the first blocking wall  8329   a  and the second blocking wall  8329   b  and move downward along the first blocking wall  8329   a  and the second blocking wall  8329   b.    
     The first blocking wall  8329   a  and the second blocking wall  8329   b , as illustrated, are disposed in the channel guide surface area. Accordingly, droplets of wash water, which are blocked by the first blocking wall  8329   a  and the second blocking wall  8329   b , may flow down to the channel guide surface  8313  by using gravity. 
     Further, droplets of wash water, which are not blocked by the first blocking wall  8329   a  and the second blocking wall  8329   b , may be finally blocked from moving toward the duct coupling part  8312  by the division wall  8314  that protrudes upward from the upper end  8312   a  of the duct coupling part  8312 . 
     As describe above, the up-down position of the upper end of the division wall  8314  is higher than the up-down positions of the lower end edge  8329   a   3  of the first blocking wall  8329   a  and the lower end edge  8329   b   3  of the second blocking wall  8329   b.    
     Thus, droplets of wash water having flown into the airflow guide  83  may be blocked from moving to the duct coupling part  8312  while colliding with the first blocking wall  8329   a  and the second blocking wall  8329   b , but droplets of wash water, which avoid the first blocking wall  8329   a  and the second blocking wall  8329   b  and are scattered toward the duct coupling part  8312  while colliding with the channel guide surface  8313 , may collide with the division wall  8314  without bouncing higher than the upper end of the division wall  8314 . 
     As described about the first blocking wall  8329   a  and the second blocking wall  8329   b , droplets of wash water, which collide with the division wall  8314  and are blocked by the division wall  8314 , may flow down to the channel guide surface  8313  along the division wall  8314  by using gravity without moving toward the duct coupling part past the upper end of the division wall  8314 . 
     As described above, droplets of wash water, blocked by the first blocking wall  8329   a  and the second blocking wall  8329   b , and droplets of wash water, blocked by the division wall  8314 , may move to the channel guide surface  8313  and naturally be discharged to the bottom tub  20   c  through the discharge opening  833 . 
     Additionally, the upper end  8511  of the duct main body  851  protrudes to a position higher than the division wall  8314  of the lower guide  831  while protruding upward from the upper end  8312   a  of the duct coupling part  8312  of the lower guide  831 . 
     Accordingly, even if droplets of washer are produced past the upper end of the division wall  8314 , it is highly likely that the droplets do not reach the upper end  8511  of the duct main body  851  that is disposed in a higher position than the upper end of the division wall  8314  with respect to the up-down direction. 
     Further, wash water may be collected on the lower surface  25  of the tub  20  at a predetermined water level or above, in the washing stage or the rinsing stage. 
     An increasing water level of wash water may lead to the flow of wash water into the airflow guide  83  through the discharge opening  833  of the airflow guide  83  and the infiltration of water into a gap between the inner circumferential surface  8312   c  of the duct coupling part  8312  and the outer circumferential surface of the duct main body  851 . 
     That is, the airflow guide  83  itself is likely to be submerged by wash water. 
     However, even if the airflow guide  83  is submerged as described above, wash water having flown into the airflow guide  83  may be discharged out of the airflow guide  83  along the channel guide surface  8313  through the discharge opening  833  again in the state where the water level of the wash water does not exceed the upper end of the division wall  8314 . 
     Additionally, even if the water level of wash water exceeds the upper end of the division wall  8314 , the height of the division wall  8314  remains lower than the height of the upper end  8511  of the duct main body  851 , as described above. Thus, the wash water may not reach the upper end  8511  of the duct main body  851 , and the wash water having arrived at the upper end  8312   a  of the duct coupling part  8312  may be discharged from the upper end  8312   a  of the duct coupling part  8312  to the lower surface  25  of the tub  20  again, through the gap between the inner circumferential surface  8312   c  of the duct coupling part  8312  and the outer circumferential surface of the duct main body  851 . 
     By setting the height of the division wall  8314 , the height of the upper end  8312   a  of the duct coupling part  8312  and the height of the upper end  8511  of the duct main body  851 , wash water may be prevented from flowing into the heater housing  81  and the heater effectively past the upper end  8511  of the duct main body  851  even if the wash water is scattered ad flows into the airflow guide  83  or submerges the airflow guide  83 . 
     Further, the airflow guide  83  of the dishwasher  1  of one embodiment may help to minimize resistance against the flow of dry airflow F supplied through the upper end  8511  of the duct main body  851  of the connection duct part  85  while blocking and minimizing the movement of droplets of wash water coming in through the first notch hole  8324  and the discharge opening  833  to the duct coupling part  8312  and the duct main body  851 , based on the positions of the blocking rib  8328  of the upper guide  832 , the blocking wall  8329 , the division wall  8314  of the lower guide  831 , and the upper end  8511  of the duct main body  851 . 
     Specifically, since the height of the upper end of the division wall  8314  remains lower than the upper end  8511  of the duct main body  851  into which dry airflow F flows, as illustrated in  FIG.  24   , the division wall  8314 &#39;s resistance against the flow of dry airflow F having passed through the upper end  8511  of the duct main body  851  may be minimized. 
     Further, the flow path of dry airflow F having passed through the upper side of the division wall  8314  is partially blocked by the first blocking wall  8329   a  and the second blocking wall  8329   b , but the lower end edge  8329   a   3  of the first blocking wall  8329   a  and the lower end edge  8329   b   3  of the second blocking wall  8329   b  are spaced upward from the channel guide surface  8313  by a predetermined distance. 
     Accordingly, the dry airflow F may flow effectively through a space between the lower end edge  8329   a   3  of the first blocking wall  8329   a  and the channel guide surface  8313  and a space between the lower end edge  8329   b   3  of the second blocking wall  8329   b  and the channel guide surface  8313 . 
     Further, the other end edge  8329   a   2  of the first blocking wall  8329   a  and the other end edge  8329   b   2  of the second blocking wall  8329   b  may be respectively separated from the outer wall surface of the upper guide  832 . 
     Thus, dry airflow F may flow effectively through a space between the other end edge  8329   a   2  of the first blocking wall  8329   a  and the outer wall surface of the upper guide  832  and a space between the other end edge  8329   b   2  of the second blocking wall  8329   b  and the outer wall surface of the upper guide  832 . 
     The above-described configurations of the first blocking wall  8329   a  and the second blocking wall  8329   b  may help to minimize an increase in the flow resistance against dry airflow F and maximize a flow path of dry airflow F. 
     [Assembly of Airflow Guide and Means of Limiting Relative Movement] 
     Hereafter, the process of assembling and fixing the airflow guide  83  of one embodiment to the connection duct part  85  and a means of limiting movement relative to the connection duct part are described with reference to  FIGS.  25 A to  27 B . 
     As described above, the lower guide  831  may be coupled to the duct main body  851  of the connection duct part  85  based on a two-stage coupling manipulation. Preferably, the two-stage coupling manipulation may comprise an up-down simple perpendicular movement manipulation and a circumferential simple rotational movement manipulation. 
     For the up-down perpendicular movement manipulation, in the state where the cap cover  834  and the upper guide  832  are coupled to the lower guide  831 , the airflow guide  83  may be arranged to be disposed at the upper side of the duct main body  851  of the connection duct part  85 , as illustrated in  FIGS.  25 A and  25 B . 
     At this time, the central axes of the duct main body  851  and the duct coupling part  8312  may be aligned in the up-down direction (U-D direction) to be inserted into the lower end  8312   b  of the duct coupling part  8312  of the lower guide  831  of the upper end  8511  of the duct main body  851 . 
     Additionally, the airflow guide  83  may be rotated clockwise around the duct coupling part  8312  from the fixed position within a predetermined range of angles. The position of the airflow guide  83  rotated clockwise is a position in which the guide projection  8516  formed on the outer circumferential surface of the duct main body  851  can be inserted into the first guide groove  8312   d  of the duct coupling part  8312 . 
     When the arrangement of the airflow guide  83  is completed with respect to the duct main body  851  as illustrated, the airflow guide  83  moves perpendicularly in the downward direction (D-direction) along the direction indicated by the arrow in  FIGS.  25 A and  25 B  such that the upper end  8511  of the duct main body  851  is inserted into the lower end  8312   b  of the duct coupling part  8312 . Accordingly, the guide projection  8516  of the duct main body  851  may be inserted into the lower end portion of the first guide groove  8312   d.    
     In the state where the guide projection  8516  of the duct main body  851  is inserted into the lower end portion of the first guide groove  8312   d  as described above, as the airflow guide  83  perpendicularly moves in the downward direction (D-direction), the up-down perpendicular movement manipulation of the airflow guide  83  starts. 
     Accordingly, the movement of the first guide groove  8312   d  of the duct coupling part  8312  is guided by the guide projection  8516  that stands still, and the first guide groove  8312   d  perpendicularly moves in the downward direction (D-direction). 
     As the guide projection reaches the upper end of the first guide groove  8312   d  as illustrated in  FIGS.  26 A and  26 B , the airflow guide  83  may not perpendicularly move in the downward direction (D-direction) any longer, based on the guide projection  8516 &#39;s action. 
     At this time, since the guide projection  8516  reaches one end portion of the second guide groove  8312   e , the airflow guide  83  may not make a perpendicular movement in the downward direction (D-direction), but may make a rotational movement circumferentially along the direction indicated by the arrow in  FIG.  26 A . 
     For the circumferential rotational movement manipulation of the two-stage coupling manipulation, as the airflow guide  83  rotates counterclockwise along the direction indicated by the arrow, the second guide groove  8312   e  may start to make a rotational movement counterclockwise along the guide projection  8516  that sands still. 
     As the airflow guide  83  starts to make a rotational movement counterclockwise, the guide projection  8516  reaches a stopper projection  8312   f  that is disposed near the other end portion of the second guide groove  8312   e.    
     At this time, stick-slip in relation to the rotation of the airflow guide  83  may be formed by the stopper projection  8312   f , and as a rotational force is additionally applied, the guide projection  8516  may go over the stopper projection  8312   f.    
     Then as the guide projection  8516  reaches the other end portion of the second guide groove  8312   e  past the stopper projection  8312   f , the airflow guide  83  may not rotate counterclockwise any longer because of the guide projection  8516 &#39;s action. 
     When the airflow guide  83  cannot rotate any longer as described above, the coupling between the lower guide  831  and the duct main body  851  may be completed, and as long as another external force is not applied, the guide projection may be fixed to the other end portion side of the second guide groove  8312   e  by the stopper projection  8312   f , as illustrated in  FIGS.  27 A and  27 B . 
     Accordingly, the airflow guide  83  may be disposed in a fixed position of the connection duct part  85 , based on a very simple manipulation or assembly process comprising the simple perpendicular movement manipulation and the simple rotational movement manipulation. 
     However, as the arrangement of the airflow guide  83  is completed, the self weight-induced movement of the airflow guide  83  is impossible, but as strong external force is applied, the second guide groove  8312   e  and the guide projection  8516  are likely to be easily unheld from each other. 
     Further, the lower guide  831  and the airflow guide  83  are highly likely to clatter because of a gap between the duct coupling part  8312  of the lower guide  831  and the duct main body  851  of the connection duct part  85 , caused by manufacturing tolerance. 
     To prevent the second guide groove  8312   e  and the guide projection  8516  from being unheld from each other and keep them fixed in their fixed positions, the release prevention part  8311   e  may be provided. 
     To prevent a relative rotation in an elastic hook way, the release prevention part  8311   e , as described above, may be provided with a hook part that is integrally formed on the second edge wall  8311   c  of the lower guide  831  in a way that a L-shaped notch is formed at the lower end side of the second edge wall  8311   c  of the lower guide  831 , i.e., in a way that the lower end of the second edge wall  8311   c  is partially cut. 
     Preferably, the hook part constituting the release prevention part  8311   e  may be disposed near the left edge side of the guide main body  8311  of the lower guide  831 , on the second edge wall  8311   c.    
     Specifically, the release prevention part  8311   e  may be formed into a circular arc-shaped plate that is disposed in a way that surrounds the circumference of the fastening nut  852  disposed inside the second edge wall  8311   c , in a circular arc shape, and is elastically deformable, as illustrated in  FIGS.  28  and  29   . 
     One end portion of the release prevention part  8311   e  functions as a fixation end portion  8311   e   1  integrally connecting to the second edge wall  8311   c . As described hereafter, the fixation end portion  8311   e   1  may also provide resilient force or elastic force to the other end portion side that is deformed at a time of rotational movement manipulation for installing and fixing the airflow guide  83 . 
     The other end portion of the release prevention part  8311   e  separates from the second edge wall  8311   c  and functions as a free end portion  8311   e   2 , and directly contacts one lateral surface of the stopper  8521  provided in the upper portion of the fastening nut  852  to stop the rotation of the lower guide  831 . 
     To keep the free end portion  8311   e   2  contacting and holding the stopper  8521  directly and effectively, the radial thickness of the free end portion  8311   e   2  may be greater than the radial thickness of the fixation end portion  8311   e   1 . 
     Specifically, as illustrated, a distance between an outer circumferential surface  8311   e   4  of the release prevention part  8311   e  and the central axis C of the duct coupling part  8312  remains constant, and an inner circumference surface  8311   e   3  of the release prevention part  8311   e  may comprise a portion where a distance from the central axis C of the duct coupling part  8312  remains constant, and a portion where a distance from the central axis C of the duct coupling part  8312  changes. 
     As illustrated, the inner circumferential surface  8311   e   3  of the release prevention part  8311   e  may comprise a non-contact surface that stays in no contact with the radial outer end portion of the stopper  8521 , and a contact surface that is in contact with the radial outer end portion of the stopper  8521 , for example. 
     The non-contact surface extends toward the free end portion  8311   e   2  from the fixation end portion  8311   e   1 , has the same curvature as the outer circumferential surface  8311   e   4  and corresponds to a portion where a distance from the central axis C of the duct coupling part  8312  remains constant. 
     The contact surface extends to the free end portion  8311   e   2  from the position where the non-contact surface ends and corresponds to a portion where a distance from the central axis C of the duct coupling part  8312  decreases gradually. 
     The free end portion  8311   e   2  corresponding to the position where the contact surface ends may protrude further inward than the radial outer end portion of the stopper  8521  in the state where the release prevention part  8311   e  is not deformed as illustrated in  FIG.  28   . 
     Additionally, the contact surface corresponds to a portion that is directly pressurized by the radial outer end portion of the stopper  8521  while the lower guide  832  rotates. 
     Accordingly, the contact surface may be formed into a curved surface or an inclined surface such that the relative movement of the radial outer end portion of the stopper  8521  is smoothly made and frictional force decreases, for example. 
     Further, a tool groove  8311   e   5  may be formed on the end portion surface of the free end portion  8311   e   2  of the release prevention part  8311   e  and be concave toward the fixation end portion  8311   e   1  side with respect to the circumferential direction. 
     In the state where the airflow guide  83  is fixed in the fixed position completely, even if external force is applied, the airflow guide  83  is configured not to rotate in a direction where the airflow guide  83  separates from the connection duct part  85  as long as the release prevention part  8311   e  or the stopper  8521  is not broken. 
     Additionally, the airflow guide  83  is formed in a position farthest from the front surface of the tub  20 , and the release prevention part  8311   e  is formed in a position facing the left side surface of the bottom tub  20   c . The positions are hardly reached by the user, and the user cannot undo the holding state between the release prevention part  8311   e  and the stopper  8521  easily without an additional tool. 
     For the user to easily deform the release prevention part  8311   e  and undo the holding state between the free end portion  8311   e   2  of the release prevention part  8311   e  and the stopper  8521  with an ordinary tool such as a screwdriver and the like, the tool groove  8311   e   5  may be provided on the end portion surface of the free end portion  8311   e   2  of the release prevention part  8311   e.    
     At this time, the tool groove  8311   e   5  may have a polygonal cross section as illustrated for an ordinary tool to be readily held at a time of undoing the holding state.  FIGS.  28  and  29    show an embodiment comprising a tool groove  8311   e   5  having a cross section of a E shape, among polygons, for example. 
     Additionally, the release prevention part  8311   e  is configured to repeat elastically deformation at a time of assembling and separating the airflow guide  83 . 
     Repetitive deformation may result in fatigue fracture. To prevent fatigue fracture, at least one reinforcement rib  8311   e   6  may be integrally provided on the outer circumferential surface  8311   e   4  of the release prevention part  8311   e  and protrude outward in the radial direction. 
     Hereafter, a relationship between the stopper  8521  of the fastening nut  852  and the operation of the release prevention part  8311   e  in the coupling process of the airflow guide  83  is described. 
     As described above, the lower guide  831  of the airflow guide  83  may be coupled to the duct main body  851  of the connection duct part  85  based on the two-stage coupling manipulation comprising a simple up-down perpendicular movement manipulation and a simple circumferential rotational movement manipulation. 
     As the up-down perpendicular movement manipulation is completed, the free end portion  8311   e   2  of the release prevention part  8311   e  may be disposed in a space between a pair of stoppers  8521  that are adjacent to each other with respect to the circumferential direction, as illustrated in  FIG.  28   . 
     As illustrated, the space between the pair of adjacent stoppers  8521  may be embodied by a circular arc groove that is open toward the outside in the upward direction and the radial direction. 
     As the circumferential rotational movement manipulation starts after the up-down perpendicular movement manipulation is completed, out of the pair of stoppers  8521 , the radial outer end portion of a stopper  8521  disposed forward with respect to the rotation direction of the airflow guide  83 , and the contact surface of the release prevention part  8311   e  may start to contact each other. 
     As the radial outer end portion of the stopper  8521  and the contact surface of the release prevention part  8311   e  start to contact, the rotational force of the airflow guide  83  is converted into a pressurizing force against the release prevention part  8311   e.    
     Accordingly, the release prevention part  8311   e  is pressurized by the stopper  8521  that stands still, and is pushed gradually outward in the radial direction from an initial position that is no load state and starts to be elastically deformed. 
     At this time, the release prevention part  8311   e  may be elastically deformed continuously to the position where the free end portion  8311   e   2 &#39;s contact with the radial outer end portion of the stopper  8521  is undone. 
     Thus, as illustrated in  FIG.  29   , as the contact between the free end portion  8311   e   2  of the release prevention part  8311   e  and the stopper  8521  is undone, the release prevention part  8311   e  may instantly return to the initial position with a click by using elasticity. 
     The free end portion  8311   e   2  of the release prevention part  8311   e  protrudes to the inside of a circular arc groove formed at the front side of the stopper  8521  at the same time as the release prevention part  8311   e  returns to the initial position. 
     Accordingly, once the free end portion  8311   e   2  of the release prevention part  8311   e  enters into the circular arc groove, based on the counterclockwise rotation of the airflow guide  83 , as illustrated, the clockwise rotation opposite to the counterclockwise rotation must be limited by the lateral surface of the stopper  8521 . 
     By doing so, a rotational movement in a direction where the airflow guide  83  separates from the duct main body  851  of the connection duct part may be prevented effectively through the release prevention part  8311   e  and the stopper  8521 . 
     However, in the state where a rotational movement is not completed during the two-stage coupling manipulation, the free end portion  8311   e   2  of the release prevention part  8311   e  may rotate toward another adjacent stopper  8521  past the previous stopper  8521 . At this time, the free end portion  8311   e   2  of the release prevention part  83711   e  may continue to rotate further while going over another stopper  8521 , in the same way described above, and the airflow guide  83 &#39;s rotation in the opposite direction may be limited in the same way. 
     The additional rotational movement may be performed until the guide projection provided at the duct main body  851  reaches the other end portion of the second guide groove  8312   e , as described above. 
     Additionally, a relative movement, in particular, a downward relative movement, of the airflow guide  83 , caused by a gap between the second guide groove  8312   e  and the guide projection  8516 , may be limited and minimized through the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  that protrude downward from the lower end  8312   b  of the duct coupling part  8312 . 
       FIG.  30    shows that the airflow guide  83  is arranged in a fixed position completely. For convenience, the cap cover  834  and the upper guide  832  are omitted in  FIG.  30   . 
     As the fixation and arrangement of the airflow guide  83  are completed as illustrated in  FIG.  30   , a gap having a predetermined width may be formed between the first to third protruding ribs  8312   h   1 ,  8312   h   2 ,  8312   h   3  and the male screw thread  8514  of duct main body  851  respectively. 
     As illustrated in the cross-sectional views of  FIGS.  32  to  34   , the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3 , disposed at regular intervals around the circular opening formed at the lower end  8312   b  of the duct coupling part  8312 , may have a different maximum protrusion height such that the gap between the protruding ribs and the male screw thread  8514  is maintained at a predetermined level or below in the position of each of the protruding ribs. 
     At this time, a gap between the first protruding rib  8312   h   1  and the male screw thread  8514  of the duct main body  851 , a gap between the second protruding rib  8312   h   2  and the male screw thread  8514  of the duct main body  851 , and a gap between the third protruding rib  8312   h   3  and the male screw thread  8514  of the duct main body  851  may differ depending on manufacturing tolerance of each of the protruding ribs. 
     However, the entire amount of a downward relative movement of the airflow guide  83  may be limited based on a gap having a maximum width among the gaps. 
     At this time, the maximum width of a gap may be 0.01 mm or less, for example. 
     Since the maximum gap is limited to 0.01 mm or less, the user may not recognize a clatter caused by the amount of relative movement or displacement corresponding to 0.01 mm or less even though each of the protruding ribs  8312   h   1 ,  8312   h   2 ,  8312   h   3  does not directly contact the male screw thread  8514  of the duct main body  851 . 
     Further, as illustrated in  FIG.  31   , the male screw thread  8514  of the duct main body  851 , when viewed from above, may be provided as a right-handed screw to be tightened clockwise. 
     Thus, the male screw thread  8514  extends in a spiral shape the up-down position of which gradually becomes low clockwise, when viewed from above. 
     When viewed from above, the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be consecutively disposed clockwise such that the gap between each of the protruding ribs  8312   h   1 ,  8312   h   2 ,  8312   h   3  and the male screw thread  8541  of the duct main body  851  remains similar approximately. 
     That is, the protrusion heights of the protruding ribs  8312   h   1 ,  8312   h   2 ,  8312   h   3  may gradually become high clockwise in response to the position of the male screw thread  8514  of the duct main body  851  that gradually becomes low clockwise. 
     Accordingly, the counterclockwise rotational movement manipulation starts in the state where the perpendicular movement manipulation is completed, the gap between each of the protruding ribs  8312   h   1 ,  8312   h   2 ,  8312   h   3  and the male screw thread  8514  of the duct main body  851  may decrease gradually. 
     Additionally, as illustrated in  FIG.  31   , the male screw thread  8514  of the duct main body  851  may have at least three or more windings from an upper end  8514   b  thereof to a lower end  8514   a  thereof, for example. 
     At this time, as illustrated in  FIGS.  32  and  33   , a screw thread  8523   a  of the fastening nut  852  to be screw-coupled to the male screw thread  8514  of the duct main body  851  may have two windings that are less than those of the male screw thread  8514  of the duct main body  851 , for example. 
     Thus, as a screw coupling of the fastening nut  852  to the male screw thread  8514  of the duct main body  851  is completed, the upper side surface of the screw thread of the male screw thread  8514 , corresponding to one winding from the upper end  8514   b  of the male screw thread  8514  of the duct main body  851 , may remain exposed to the lower end  8312   b  of the duct coupling part  8312 . 
     As a result, the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  of the duct coupling part  8312  may be supported by the upper side surface of the male screw thread  8514  of the duct main body  851  at a time of occurrence of a downward relative movement, without being affected by the screw thread  8523   a  provided on an inner circumferential surface  8523  of the fastening nut  852 . 
     Further, the radial maximum widths of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be the same, and be less than a gap between the outer circumferential surface of the connection duct part  85  and the inner circumferential surface  8523  of the fastening nut  852 . 
     Accordingly, the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be in no contact with the inner circumferential surface  8523  and the upper end  8522  of the fastening nut  852 . 
     By doing so, although the third protruding rib  8312   h   3  having a maximum protrusion height is inserted into the fastening nut  852 , a relative position of the third protruding rib  8312   h   3  with respect to the male screw thread  8514  of the duct main body  851 , as illustrated in  FIG.  33   , may be set regardless of the inner circumferential surface  8523  and the upper end  8522  of the fastening nut  852 . 
     At this time, as described above, the lower end surfaces of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be provided in the form of an inclined surface to correspond to the shape of the upper side surface of the male screw thread  8514  of the duct main body  851 , which extends spirally. 
     The inclination angles of the lower end surfaces of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be approximately the same as that of the male screw thread  8514  of the duct main body  851 . 
     Thus, as at least any one of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  contacts the upper side surface of the male screw thread  8514  of the duct main body  851  because of the airflow guide  83 &#39;s downward relative movement caused by external force, at least any one of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be in surface-contact with the upper side surface of the male screw thread  8514  of the duct main body  851 . 
     That is, the lower end surface of at least any one of the first protruding rib  8312   h   1 , the second protruding rib  8312   h   2  and the third protruding rib  8312   h   3  may be entirely supported by the upper side surface of the male screw thread  8514  of the duct main body  851 . 
     Since a maximum relative contact surface between the lower end surface of at least any one of the protruding ribs and the male screw thread  8514  of the duct main body  851  is ensured, the downward relative movement of the airflow guide  83  may be effectively limited, and the airflow guide  83  may be reliably supported, despite strong external force. 
     [Detailed Configuration of Fastening Nut] 
     Hereafter, a detailed configuration of the fastening nut  852  provided in the dishwasher  1  of one embodiment is described with reference to  FIGS.  35  and  36   . 
     The fastening nut, as described above, is screw-coupled to the outer circumferential surface of the connection duct part  85  and fixes the connection duct part  85  to the lower surface  25  of the bottom tub  20   c.    
     To this end, the fastening nut  852  may have a cylindrical shape entirely, and be provided with a screw thread  8523   a  on the cylinder-shaped inner circumferential surface  8523   a  thereof, and the screw thread  8523   a  has a female screw shape and is screw-coupled to the male screw thread  8514  of the duct main body  851  of the connection duct part  85 . 
     The screw thread  8523   a  of the fastening nut, as described above, may have two windings, for example. 
     At a time of fixing and coupling the duct main body  851 , the fastening nut  852  is screw-coupled to the male screw thread  8514  of the duct main body  851  such that the upper end  8511  of the duct main body  851  is fixed to the tub  20 , in the state of being exposed to the inside of the tub  20 . 
     At this time, in the state where the fastening nut  852  is in close contact with the upper portion side of the lower surface  25  of the bottom tub  20   c , and a flange  8513  of the duct main body  851  is in close contact with the lower portion side of the lower surface  25  of the bottom tub  20   c , the flange  8513  receives the force of being pulled toward the lower surface of the bottom tub  20   c , because of the fastening nut  852 &#39;s coupling force. 
     By doing so, adhesive force between the flange  8513  and the lower surface  25  of the bottom tub  20   c  increases. Thus, it is less likely that wash water leaks to the outer circumferential surface of the duct main body  851 . As a means of promoting the effect of preventing the leakage of wash water, an airtight ring made of an elastic material may be further provided between the flange  8513  and the lower surface  25  of the bottom tub  20   c.    
     Additionally, a plurality of stoppers  8521  may be provided at the upper end side of the fastening nut  852  and interact with the release prevention part  8311   e  of the airflow guide  83 . 
     The plurality of stoppers  8521  may be formed in a way that the upper end  8522  and the outer circumferential surface  8524  of the fastening nut  852  are depressed partially, and each of the plurality of stoppers  8521  may be disposed along the circumferential direction at regular intervals. 
     As described above, the other end portion of the release prevention part  8311   e  of the airflow guide  83  separates from the second edge wall  8311   c  and functions as a free end portion  8311   e   2 , and directly contacts one side surface of the stopper  8521  of the fastening nut  852  and limits the rotational movement of the airflow guide  83  to prevent the airflow guide  83 &#39;s escape from the right position thereof. 
     Further, the fastening nut  852  is directly exposed to wash water in the washing stage and the rinsing stage. In particular, the fastening nut  852  is directly exposed to the wash pace, and in some cases, is submerged in wash water filling the lower surface  25  of the bottom tub  20   c , since it is disposed at the upper side of the lower surface  25  of the bottom tub  20   c.    
     To be protected from corrosion caused by wash water, the fastening nut  852  may be manufactured, based on a plastic injection molding process. 
     Further, as the fastening nut  852  is coupled to the duct main body  851  completely, as described above, a lower end surface  8525  of the fastening nut  852  is in close contact with the lower surface  25  of the bottom tub  20   c  directly. 
     At this time, a minute gap may be formed between the lower surface  25  of the bottom tub  20   c  and the lower end surface  8525  of the fastening nut  852 , in close contact, due to their manufacturing tolerance, and through the gap, wash water may flow into a space formed by the inner circumferential surface  8523  of the fastening nut  852 , the outer circumferential surface of the duct main body  851  and the lower surface  25  of the bottom tub  20   c.    
     Since the gap is minute, the wash water can hardly be discharged out of the fastening nut  852  once the wash water flows into the space. 
     The lower surface  25  of the bottom tub  20   c  is highly likely to be corroded by the wash water which is drawn but not discharged. In particular, since the dry air supply hole  254  is formed inside the fastening nut  852  in a way that the bottom tub  20   c  is perforated, the dry air supply hole  254  is highly likely to corrode, and germs included in wash water are reproduced generating a bad smell. 
     As a means of preventing the bottom tub  20   c ′ corrosion and generation of a bad smell, the fastening nut  852  provided at the dishwasher  1  of one embodiment may comprise a plurality of contact projections  8526  that extends toward the bottom tub  20   c  from the lower end surface  8525 . 
     Each of the plurality of contact projections  8526  may have an upper end that integrally connects to the lower end surface  8525  of the fastening nut  852 , and a lower end that extends toward the lower surface  25  of the bottom tub  20   c  in the form of a protruding rib. 
     Each of the plurality of contact projections  8526  may be spaced from one another by a predetermined circumferential distance Dc, on the lower end surface  8525  of the fastening nut  852 , in the circumferential direction. 
     At this time, the predetermined circumferential distance may be greater than a maximum circumferential thickness Wc of each contact projection  8526 . 
     By doing so, a wash water passage through which wash water comes in and out may be provided between the contact projections  8526 , and the lower end surface  8525  of the fastening nut  852  may be separated from the lower surface  25  of the bottom tub  20   c  and exposed to the wash space. 
     Accordingly, wash water may be effectively discharged out of the fastening nut without staying in the space formed by the inner circumferential surface  8523  of the fastening nut  852 , the outer circumferential surface of the duct main body  851  and the lower surface  25  of the bottom tub  20   c.    
     By doing so, the corrosion of the bottom tub  20   c , i.e., the corrosion of the dry air supply hole  254 , may be prevented effectively. 
     Further, each contact projection  8526  may have the same outer shape. 
     At this time, each contact projection  8526  may be formed into a sharp edge having a horizontal cross section of which decreases gradually from an upper end to a lower end, for example. 
     Additionally, a contact end portion  8526   a  at the lower end of the contact projection  8526 , contacting the lower surface  25  of the bottom tub  20   c , may be formed into a curved surface that is convex toward the lower surface  25  of the bottom tub  20   c . Accordingly, the contact projection  8526  and the bottom tub  20   c  may remain at least in a linear contact state. 
     The shape of the contact projection may help to distribute the fastening nut  852 &#39;s coupling force or pressurizing force uniformly through the each of the contact projections  8526  and apply the same to the lower surface  25  of the bottom tub  20   c . Further, the sharp edge shape of the contact projection may help to minimize foreign substances such as food and the like fitted or fixed between the contact projection  8526  and the bottom tub  20   c.    
     Further, as illustrated in  FIG.  36   , the dry air supply hole  254  through which the upper end  8511  of the duct main body  851  passes, is formed on a convergence surface  251  for guiding wash water to the sump hole  252 . 
     The convergence surface  251  has a predetermined convergence inclination angle with respect to the horizontal direction to allow wash water to be moved by gravity. 
     Accordingly, the pressurizing force of the fastening nut  852  that moves perpendicularly at a time of screw-coupling the fastening nut  852  to the male screw thread  8514  of the duct main body  851  may not be applied uniformly through the contact projection  8526 . 
     For the pressurizing force of the contact projection  8526  of the fastening nut  852  to be uniformly distributed and applied to the bottom tub  20   c , a ring-type coupling surface  2541  may be formed around the dry air supply hole  254  and be pressurized by the contact end portion  8526   a  of the lower end of the contact projection  8526 . 
     At this time, the ring-type coupling surface  2541  may have directionality that extends in the horizontal direction perpendicular to the perpendicular direction where the fastening nut  852  is moved while being screw-coupled. 
     For example, the ring-type coupling surface  2541  may be a ring-type bead surface that is formed in a way that the surrounding area of the dry air supply hole  254  is pressed and plastic-deformed. 
     As described above, since the coupling surface  2541  extending horizontally is additionally formed in the portion of the bottom tub  20   c , where the pressuring force of the fastening nut  852  is directly applied, each contact projection  8526  may apply its pressurizing force to the bottom tub  20   c  uniformly or evenly. 
     Further, the bottom tub  20   c , as illustrated, may be further provided with a cylindrical part  2542  that extends circumferentially along the dry air supply hole  254  and protrudes upward toward the lower end surface  8525  of the fastening nut  852 . 
     The cylindrical part  2542  intends to extend upward the height of a flooding water surface of wash water filling the lower surface  25  of the bottom tub  20   c.    
     As illustrated, to prevent interference with the fastening nut  852 , the height at which the cylindrical part  2542  protrudes from the lower surface  25  of the bottom tub  20   c  may be less than the height at which the contact projection  8526  protrudes from the lower end surface  8525  of the fastening nut  852 . 
     Additionally, the height at which the cylindrical part  2542  protrudes from the lower surface  25  of the bottom tub  20   c  may remain constant along the circumferential direction. 
     Thus, it is less likely that wash water flows into the dry air supply hole  254  directly and that the dry air supply hole  254  and the cylindrical part  2542  are corroded by wash water. 
     The embodiments are described above with reference to a number of illustrative embodiments thereof. However, embodiments are not limited to the embodiments and drawings set forth herein, and numerous other modifications and embodiments can be drawn by one skilled in the art within the technical scope of the disclosure. Further, the effects and predictable effects based on the configurations in the disclosure are to be included within the scope of the disclosure though not explicitly described in the description of the embodiments.