Abstract:
A cyclone type dirt separator disposed at an intermediate point of an suction tube which connects the suction fitting and the cleaner main body of an electric vacuum cleaner, the dirt separator including: a dirt separating section which causes the suction air to undergo a spiral flow and conducts air from the vicinity of the center of this spiral flow to the cleaner main body, a dirt collection chamber which is attached to the dirt separating section from below and causes the dirt separated from the spiral flow to drop so that the dirt is collected inside the dirt collection chamber, and a recessed portion which is formed in the vicinity of the inside bottom center of the dirt collection chamber so as to be recessed downward.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field  
         [0002]     The present invention relates to a cyclone type dirt separator which is provided at an intermediate point of the suction tube of an electric vacuum cleaner and further relates to an electric vacuum cleaner that uses such a separator.  
         [0003]     2. Description of the Related Art  
         [0004]     In typical electric vacuum cleaners, suction air that involves dirt that is sucked in via a suction fitting (suction nozzle) is led to the cleaner main body via a suction tube. Here, the suction air that contains dirt passes through a filter installed in the cleaner main body, and dirt is collected by this filter.  
         [0005]     In collection of the dirt, if relatively large pieces of dirt such as paper debris, sludge and the like are contained in large quantities in the dirt that is sucked in, the filter quickly becomes clogged, so that the suction capacity soon drops. Accordingly, the filter must be cleaned frequently, and this frequent filter cleaning is in fact a problem of poor efficiency. In order to solve this problem, a system has been proposed in which a cyclone type dirt separator is interposed at an intermediate point of the suction tube that connects the suction fitting and the cleaner main body, so that the cyclone type dirt separator captures and removes relatively large pieces of dirt.  
         [0006]     In the cyclone type dirt separator disclosed in Japanese Patent No. 3102864, the lower end of an exhaust tube that sucks air from the vicinity of a spiral flow into the cleaner main body is closed, numerous fine through-holes are formed in the outer circumferential surface of this tube, and air is sucked from these fine through-holes and discharged into the cleaner main body. In this structure, the dirt that is separated from the spiral flow is collected in a contaminant collection trough (a dirt collection part) that extends downward and surrounds the exhaust tube.  
         [0007]     On the other hand, in the cyclone type dirt separators of Japanese Patent Application Laid-Open (Kokai) Nos. 2003-135336 and H10-85159, the open lower end of an exhaust tube is caused to face the vicinity of the center of the dust separating section that generates a spiral flow, and the lower part of the dust separating section is communicated with a dust collecting part that is provided below the dust separating section via a dust collecting opening that is in the form of a funnel. In this structure, the dirt that is separated by the spiral flow in the dust separating section drops into the dust collecting part via the dust collecting opening.  
         [0008]     However, in the system of Japanese Patent No. 3102864, dirt separated by centrifugal force in the spiral flow is conducted downward along the inside circumferential wall of the contaminant collecting trough; accordingly, the separation of dirt and air can be accomplished with good efficiency. However, since the fluid motion of the spiral flow enters the interior of the contaminant collecting trough along the inside circumferential wall of the contaminant collecting trough, the air inside the contaminant collecting trough undergoes a spiral flow. As a result, the dirt that collects in the bottom of the contaminant collecting trough is entrained by the fluid motion (spiral flow) of this air and may be discharged from the exhaust tube. This dirt causes clogging of the filter of the cleaner main body.  
         [0009]     In the systems of Japanese Patent Application Laid-Open (Kokai) Nos. 2003-135336 and H10-85159, a spiral flow is generated in the dust separating section, and dirt is collected in the dust collecting part separated by the dust collecting opening installed in the funnel-form bottom. Consequently, the spiral flow inside the dust separating section tends not to enter the dust collecting part. Accordingly, it would appear that the amount of dirt that is entrained by the spiral flow in dust collecting part is small compared to that seen in the system of Japanese Patent No. 3102864.  
         [0010]     However, a spiral flow would be generated inside the dust collecting part according to the amount of suction air, so that dirt may be entrained; and secure prevention of the entrainment of dirt in the dust collecting part is difficult. Furthermore, since the dust collecting part is installed separately from the dust separating section, the total length of the structure increases, causing a problem of increased size of the apparatus.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     Accordingly, the first object of the present invention is to provide a cyclone type dirt separator which assuredly prevents the entrainment of dirt accumulated in the contaminant collecting trough or dust collecting part by spiral flow of air, thus preventing the exhaust of entrained dirt and intake of such dirt into the cleaner main body.  
         [0012]     The second object of the present invention is to provide an electric vacuum cleaner that is equipped with such a cyclone type dirt separator.  
         [0013]     The above object is accomplished by a unique structure of the present invention for a cyclone type dirt separator, which is interposed at an intermediate point of the suction tube connecting the suction fitting and a cleaner main body of an electric vacuum cleaner, and which separates dirt from the suction air containing dirt that is sucked in from the suction fitting; and in the present invention, the separator is comprised of: 
        a dirt separating section which causes the suction air to make a spiral flow and conducts air from the vicinity of the center of this spiral flow to the cleaner main body,     a dirt collection chamber which is mounted on this dirt separating section from below and causes the dirt separated from the spiral flow to drop so that the dirt is collected in said dirt collection chamber, and     a recessed portion formed in the vicinity of the inside bottom center of the dirt collection chamber so as to be recessed downward.        
 
         [0017]     In this structure of the present invention, since the recessed portion is formed in the vicinity of the center of the inside bottom of the dirt collection chamber, the dirt that enters the dirt collection chamber is conducted into the inside bottom surface and is collected in the recessed portion. In addition, even if a spiral flow is generated in the dirt collection chamber, since this spiral flow tends not to enter the sunken recessed portion, no entrainment of the dirt accumulated in the recessed portion occurs, and dirt in the vicinity of the inside bottom likewise tends not to become entangled and entrained with the dirt accumulated in this recessed portion. Accordingly, dirt that has once entered the dirt collection chamber is prevented from being discharged from the exhaust tube, so that the need for frequent cleaning of the filter inside the cleaner main body is eliminated.  
         [0018]     The above object is further accomplished by a unique structure of the present invention for an electric vacuum cleaner that comprises:  
         [0019]     a cleaner main body provided with an electrically driven air blower;  
         [0020]     a suction tube with one end thereof connected to the vacuum suction port of this cleaner main body;  
         [0021]     a suction fitting which is attached to the tip end of this suction tube; and  
         [0022]     a cyclone type dirt separator which is interposed at an intermediate point of the suction tube, the cyclone type dirt separator causing suction air containing dirt that is sucked in from the suction fitting to undergo a spiral flow, separating dirt from this air in spiral flow, and causing the separated dirt that is thus separated to drop into a substantially tubular dirt collection chamber so that this dirt is collected in the dirt collection chamber; and in addition,  
         [0023]     the dirt collection chamber of the cyclone type dirt separator has a recessed portion that is formed in the vicinity of the inside bottom center of the dirt collection chamber so that it is recessed downward.  
         [0024]     Accordingly, in the electric vacuum cleaner of the present invention, dirt that has once entered the dirt collection chamber of the cyclone type dirt separator is prevented from being discharged from the exhaust tube, and the need for frequent cleaning of the filter inside the cleaner main body is eliminated.  
         [0025]     In the cyclone type dirt separator of the present invention, the separating section may comprise an exhaust tube, which is disposed substantially in coaxial with the central axis of the spiral of the spiral flow, whose lower end is closed off, and which exhausts air via the exhaust openings in the circumferential surface; and the dirt collection chamber may have a substantially tubular shape that extends downward while surrounding this exhaust tube. In this case, the dirt that is separated by the centrifugal force arising from the spiral flow can be conducted into the inside bottom of the dirt collection chamber with good efficiency, so that the dirt separation is done efficiently. Furthermore, one part (the upper part) of the dirt collection chamber surrounds the exhaust tube and forms an integral unit with the separating section, thus generating a spiral current of air; accordingly, this structure contributes the overall size reduction.  
         [0026]     Furthermore, with a substantially flange-form baffling plate which narrows the air flow path between this baffling plate and the inside wall of the dirt collection chamber, the entry of the spiral flow into the inside bottom of the dirt collection chamber is prevented, so that the entrainment of dirt accumulated in this inside bottom and the outflow of such dirt together with the exhaust can be much more securely prevented.  
         [0027]     In the present invention, the inside surface in the vicinity of the opening of the recessed portion and the inside bottom surface of the dirt collection chamber are not smoothly continuous, or such surfaces meet with a ridge in between. For example, the inside bottom surface of the dirt collection chamber can be formed as a so-called artillery shell-form curved surface in which the diameter is smoothly reduced downward, and this curved surface and the opening circular edge of the recessed portion abuts at an obtuse angle to form a substantially annular edge shape. With this structure, if a spiral flow occurs in the inside bottom, the spiral flow is less likely to enter the recessed portion.  
         [0028]     The recessed portion can be of a substantially cylindrical shape with a closed bottom. However, the present invention is not limited to this structure, and a square tubular shape recessed portion that has a closed bottom or the like can be also used. By way of setting the diameter of the opening of the recessed portion at approximately ½ to ⅓ of the diameter near the center of the dirt collection chamber, the intrusion of the spiral flow can be sufficiently cut off while maintaining the capacity (volume) of the recessed portion at a large value.  
         [0029]     In the present invention, it is preferable that the cyclone type dirt separator be installed in the connecting portion between a flexible tube and an extension tube that constitute the suction tube of an electric vacuum cleaner; however, this cyclone type dirt separator can be disposed, for instance, in the vicinity of the tip end of the extension tube and in the vicinity of the vicinity of the rear end of the flexible tube (immediately before the cleaner main body or the like). 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0030]      FIG. 1  shows the electric vacuum cleaner of the present invention equipped with a cyclone type dirt separator according to one embodiment of the present invention;  
         [0031]      FIG. 2  is a sectional side view of the cyclone type dirt separator;  
         [0032]      FIG. 3  is a sectional view of the essential portion of the cyclone type dirt separator;  
         [0033]      FIG. 4  is a sectional view taken along the line IV-IV in  FIG. 3 ;  
         [0034]      FIG. 5  is a sectional view taken along the line V-V in  FIG. 4 ; and  
         [0035]      FIG. 6  illustrates the exhaust openings of the exhaust tube inside the dirt separator. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]     In  FIG. 1 , the reference numeral  10  is a cleaner main body, and this cleaner main body  10  is equipped with a filter  12  and an electrically driven air blower  14 . A suction tube  16  connected to the cleaner main body  10  is comprised of a flexible tube  18  and an extension tube  20 , and a cyclone type dirt separator  22  is provided at an intermediate point of this suction tube  16 . The electrically driven air blower  14  generates a suction force by rotating a fan (not shown) at high speed with an electric motor (not shown).  
         [0037]     The electric vacuum cleaner  10  is indeed usable without a cyclone type dirt separator  22 ; and in this case, the flexible tube  18  (or the forward end of the flexible tube  18 ) and the extension tube  20  (or the rear end of the extension tube  20 ) are directly connected to each other to form the suction tube  16 . When a cyclone type dirt separator  22  is used, the cyclone type dirt separator  22  is interposed between the flexible tube  18  and the extension tube  20 . In other words, the forward end of the flexible tube  18  is connected to the rear end of the dirt separator  22  (or to the exhaust tube  32 , which will be described later, of the dirt separator  22 ), and the rear end of the flexible tube  18  is connected to the cleaner main body  10 , and a suction fitting (suction brush)  24  is attached to the forward end of the extension tube  20  and the rear end of the extension tube  20  is connected to the dirt separator  22  (or to the suction intake tube  34 , which will be described later, of he dirt separator  22 ) as shown by arrows in  FIG. 1 .  
         [0038]     When a switch (not shown) on the cyclone type dirt separator  22  is turned on, the electric motor of the air blower is started; and an air suction negative pressure is generated in the suction fitting  24 . Air that contains dirt is sucked in via the suction fitting  24 , and relatively large pieces of dirt are separated from this suction air by the cyclone type dirt separator  22 ; and then the air enters the cleaner main body  10 . This air passes through the cleaner main body and is exhausted to the outside.  
         [0039]     As seen from  FIG. 2 , the cyclone type dirt separator  22  is comprised of a dirt separating section  26 , a dirt collection chamber  28 , and a grip section  30 .  
         [0040]     The dirt separating section  26  includes an exhaust tube  32 , a suction intake tube  34 , a spiral flow passage  38  and a spiral flow compartment  40 . The exhaust tube  32  is, at its end, connected to the flexible tube  18 ; and this exhaust tube  32  extends downward and is bent at its intermediate point to take a substantially shallow V shape when viewed from the side as seen from  FIG. 2 . The suction intake tube  34  is disposed parallel to and on a different axis than the lower part of the exhaust tube  32 , and the lower end of the suction intake tube  34  is connected to the extension tube  20 . The spiral flow passage  38  is provided so as to communicate with the upper end of the suction intake tube  34  and is led to the outer circumference of the exhaust tube  32  so that the suction air is put in a spiral flow  36  (see  FIG. 3 ). The spiral flow compartment  40  separates dirt from the suction air by means of the spiral flow  36  of the air. The exhaust tube  32  is disposed in substantially coaxial with the central axis of the rotation of the spiral flow  36 .  
         [0041]     As shown in  FIG. 5 , the spiral flow passage  38  is formed by being surrounded by a partition wall  38   a  that constitutes the lower wall of the spiral flow passage  38  which forms a partition with the spiral flow compartment  40 , a flow passage opening  38   b  that is formed in this partition wall  38   a,  an inclined wall  38   c  that constitutes the upper wall of the spiral flow passage  38 , a circular arc form outer circumferential wall  38   d,  and an inner circumferential wall  38   e.  The flow passage opening  38   b  is formed by cutting away the partition wall  38   a  for the length L in the circumferential direction. The inner circumferential wall  38   e  is formed by the outer circumferential surface of the exhaust tube  32 . The upstream side of the inclined wall  38   c  (the upstream side being the part located on the suction intake tube  34  side) is connected to the upper wall of the suction intake tube  34 , and the downstream side (which is the portion located on the partition wall  38   a  side) is connected to the rear edge  38   f  (which is on the downstream side in the spiral direction) of the opening  38   b.    
         [0042]     The exhaust tube  32  is formed, on its circumferential wall, with numerous exhaust openings  42  (see  FIG. 6 ) so that the exhaust openings  42  face the spiral flow compartment  40 . Each of the exhaust openings  42  is in a slit-form having longer longitudinal sides in the longitudinal direction of the exhaust tube  32  than the width in the circumferential direction. Thus, the exhaust opening  42  is, for instance, approximately 20 mm long and approximately 6 mm wide. These exhaust openings  42  are provided in two (upper and lower) stages in the longitudinal direction of the exhaust tube  32 , and they prevent large pieces of debris such as paper scraps or the like from being sucked into the exhaust tube  32 . The lower end  32   a  of the exhaust tube  32  is closed, and a baffling plate  44  that extends substantially in the form of a cone is disposed on this lower end of the exhaust tube  32 . In the shown embodiment, the baffling plate  44  has a substantially circular (reversed) conical shape so that the diameter gradually increases toward its lower edge.  
         [0043]     With the structure described above, air or dirty air is sucked in through the suction fitting (suction brush)  24  and rapidly flows through the extension tube  20  and into the suction intake tube  34  of the separator  22 . Then, the air enters the spiral flow passage  38 , flows along the curved outer and inner circumferential walls  38   d  and  38   e  and hits the inclined wall  38   c,  so that the air, while being rotating, flows downward into the spiral flow compartment  40  through the flow passage opening  38   b,  thus forming a spiral flow  36  or “cyclone.” The spiral flow  36 , particularly the portion of the air which is in the vicinity of the center of the spiral flow  36 , enters the exhaust tube  32  through the exhaust openings  42  of the exhaust tube  32  so that large pieces of dirt in the air are caught by the striped pattern portions between the exhaust openings  42  and thus separated and removed from the spiral flow  36 , and the air without large pieces of dirt eventually flows into the cleaner main body  10  through the flexible tube  18 .  
         [0044]     The dirt collection chamber  28  has a shape of a substantially artillery shell in which the upper end is open and the lower part shows a gradual and smooth decrease in diameter. The dirt collection chamber  28  is, at its upper end, attached to the dirt separating section  26  in a coaxial relation with the exhaust tube  32 , and the dirt collection chamber  28  is detachable with reference to the dirt separating section  26 .  
         [0045]     The spiral flow compartment  40  is provided in coaxial with the exhaust tube  32  between the exhaust tube  32  and the upper part of the dirt collection chamber  28 .  
         [0046]     The diameter of the baffling plate  44  is set so that air is allowed to flow between the baffling plate  44  and the inside surface of the dirt collection chamber  28 , so that the spiral flow  36  is prevented from flowing around beneath the baffling plate  44  and so that a gap that suppresses any back flow of dirt is formed.  
         [0047]     The dirt collection chamber  28  is provided so that the inside bottom surface  46  is takes a curved surface that has a smooth decrease in diameter in the downward direction. A recessed portion  48  that sinks downward is formed in the center of this inside bottom surface  46  of the dirt collection chamber  28 . The recessed portion  48  is in a shape of a cylinder with a closed bottom, and the diameter of this recessed portion is approximately ½ to ⅓ of the diameter of the dirt collection chamber  28 . More specifically, the diameter of this recessed portion  48  is approximately ½ to ⅓ of the diameter of the approximately the vertically central portion of the dirt collection chamber  28  which is substantially at the height of the baffling plate  44 . As best seen from  FIG. 3 , the central axis of the recessed portion  48  is set on the central axis A of the exhaust tube  32 , thus being on the axis of the rotation of the spiral flow  36 .  
         [0048]     The curved surface of the inside bottom surface  46  of the dirt collection chamber  28  and the inside surface in the vicinity of the opening or of the opening edge  48   a  of the recessed portion  48  are formed so that they are not smoothly continuous (or unsmoothly continuous). In other word, as best seen from  FIG. 3 , the portion where the inside bottom surface  46  of the dirt collection chamber  28  and the opening or the opening edge  48   a  of the recessed portion  48  abut each other with an obtuse-angle and thus takes an obtuse-angle edge form surface or a step form surface. Since this abutting surface is thus a surface that is bent in a discontinuous form, edge form or step form from the inside bottom surface  46  to the recessed portion  48 , even if the spiral flow  36  drops down along the inside bottom surface  46 , this spiral flow is blocked by the opening edge  48   a  of the recessed portion  48 , and dirt that has dropped into the recessed portion  48  is not entrained by the spiral flow. Furthermore, dirt that drops into the dirt collection chamber  28  is prevented from being entrained since such dirt dropping into the dirt collection chamber  28  is entangled with dirt that has previously been dropped in the bottom of the dirt collection chamber  28 .  
         [0049]     The dirt collection chamber  28  is detachable. In other words, as shown in  FIGS. 1 and 2 , the hook  50  provided in the vicinity of the lower end of the suction intake tube  34  is provided so that it is engaged with and disengaged from the outside of the recessed portion  48  positioned at the lower end of the dirt collection chamber  28 . When the dirt collection chamber  28  is set on the suction intake tube  34  as shown in  FIGS. 2 and 3 , the dirt collection chamber  28  is fastened in place by this hook  50 . When dirt that has accumulated inside the dirt collection chamber  28  is to be discarded, the hook  50  is disengaged from the recessed portion  48 , the dirt collection chamber  28  is removed from the suction intake tube  34 , and the dirt inside the recessed portion  48  is discharged.