Patent Publication Number: US-11389278-B2

Title: Oral cavity washing device

Description:
RELATED APPLICATIONS 
     This application claims the benefit of Japanese Application No. 2016-225537, filed on Nov. 18, 2016, the entire disclosure of which Application is incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an oral cavity washing device for washing the inside of an oral cavity with a washing liquid. 
     2. Description of the Related Art 
     Conventionally, an oral cavity washing device which includes a body unit, a tube, a washing unit and the like is disclosed in Unexamined Japanese Patent Publication No. 2015-217174, for example (referred to as “PTL 1” hereinafter). The body unit includes a tank for storing a washing liquid, and a pump for discharging the washing liquid. The tube is connected to the body unit, and a washing liquid discharged from the pump flows through the tube. The washing unit includes a washing unit which discharges a washing liquid supplied from the tube. 
     PTL 1 discloses one example of a conventional oral cavity washing device. The conventional oral cavity washing device further includes a structure for detachably mounting the washing unit on the body unit. With such a configuration, when a user uses the washing unit, the user removes the washing unit from the body unit. On the other hand, when the user does not use the washing unit, the user can mount the washing unit on the body unit. 
     In the conventional oral cavity washing device, at the time of mounting the washing unit on the body unit in a state where the washing unit is brought into contact with the body unit, there may be a case where a position of the washing unit is slightly displaced from a position suitable for mounting the washing unit. That is, there is a possibility that the washing unit cannot be mounted at an appropriate position on the body unit. 
     SUMMARY 
     According to an aspect of the present disclosure, an oral cavity washing device includes: a body unit including a pump from which a washing liquid is discharged; a tube connected to the body unit for making the washing liquid discharged from the pump flow through the tube; a washing unit connected to the tube for discharging the washing liquid; and a joining portion which joins the body unit and the washing unit to each other by a magnetic force. 
     According to the oral cavity washing device of the present disclosure, the washing unit can be easily mounted at an appropriate position on the body unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an oral cavity washing device of an exemplary embodiment; 
         FIG. 2  is a front view of the oral cavity washing device in  FIG. 1 ; 
         FIG. 3  is a plan view of a body unit in  FIG. 1 ; 
         FIG. 4  is a perspective view showing a state where a washing unit is removed from the body unit; 
         FIG. 5  is a cross-sectional view taken along line  5 - 5  in  FIG. 2 ; 
         FIG. 6  is an enlarged view of portion A in  FIG. 5 ; 
         FIG. 7  is a cross-sectional view taken along line  7 - 7  in  FIG. 2 ; 
         FIG. 8  is an enlarged view of portion B in  FIG. 7 ; 
         FIG. 9  is an exploded perspective view of the body unit in  FIG. 1 ; 
         FIG. 10  is a cross-sectional view taken along line  10 - 10  in  FIG. 3 ; 
         FIG. 11  is a cross-sectional view taken along line  11 - 11  in  FIG. 2 ; 
         FIG. 12  is a cross-sectional view taken along line  12 - 12  in  FIG. 2 ; 
         FIG. 13  is a bottom view of the body unit in  FIG. 1 ; 
         FIG. 14  is a cross-sectional view taken along line  14 - 14  in  FIG. 13 ; 
         FIG. 15  is a cross-sectional view showing a sixth seal portion according to a modification; and 
         FIG. 16  is a perspective view showing one example of an oral cavity washing device according to the modification. 
     
    
    
     DETAILED DESCRIPTION 
     (One Example of a Mode which an Oral Cavity Washing Device can Adopt) 
     [1] According to an aspect of the present disclosure, an oral cavity washing device includes: a body unit including a pump from which a washing liquid is discharged; a tube connected to the body unit for making the washing liquid discharged from the pump flow through the tube; a washing unit connected to the tube for discharging the washing liquid; and a joining portion which joins the body unit and the washing unit to each other by a magnetic force. 
     With such a configuration, when the washing unit is disposed close to the body unit, the washing unit is joined to the body unit by a magnetic force of the joining portion. Accordingly, even when the position of the washing unit with respect to the body unit is not accurately aligned unlike a conventional oral cavity washing device, the washing unit can be mounted on the body unit. 
     [2] According to one example of the oral cavity washing device, the joining portion includes a first joining portion formed on the body unit and a second joining portion formed on the washing unit, one of either the first joining portion or the second joining portion includes a magnet, and the other of either the first joining portion or the second joining portion includes a magnet or a ferromagnetic. With such a configuration, the configuration of the joining portion can be simply formed. 
     [3] According to one example of the oral cavity washing device, the first joining portion includes a magnet, and the second joining portion includes a ferromagnetic. With such a configuration, in a state where the washing unit is removed from the body unit, the second joining portion does not attract a ferromagnetic which exists around the oral cavity washing device. 
     [4] According to one example of the oral cavity washing device, the first joining portion includes a first accommodating portion in which a magnet or a ferromagnetic is accommodated. With such a configuration, the magnet or the ferromagnetic is minimally smeared. 
     [5] According to one example of the oral cavity washing device, the body unit further includes a first case which accommodates a pump. The first case includes a first outer wall which forms an outer shell of the body unit, and the first accommodating portion includes a second outer wall which forms the outer shell of the body unit together with the first outer wall of the body unit. With such a configuration, downsizing of the oral cavity washing device can be realized. 
     [6] According to one example of the oral cavity washing device, a thickness of the second outer wall of the body unit is smaller than a thickness of a portion of the first outer wall of the body unit around the second outer wall of the body unit. With such a configuration, a magnetic force which acts between the first joining portion and the second joining portion can be increased. 
     [7] According to one example of the oral cavity washing device, the second joining portion includes a second accommodating portion in which a magnet or a ferromagnetic is accommodated, and the washing unit includes a second case having a grip portion. The second case includes a first outer wall which forms an outer shell of the washing unit, and the second accommodating portion includes a second outer wall which forms the outer shell of the washing unit together with the first outer wall of the washing unit. Further, a thickness of the second outer wall of the washing unit is smaller than a thickness of a portion of the first outer wall of the washing unit around the second outer wall of the washing unit. With such a configuration, a magnetic force which acts between the first joining portion and the second joining portion can be increased. 
     [8] According to one example of the oral cavity washing device, the second outer wall of the body unit includes a recessed portion which corresponds to a shape of the outer shell of the washing unit, and the magnet or the ferromagnetic is disposed on an inner surface side of the recessed portion of the second outer wall of the body unit. With such a configuration, in a state where the washing unit is joined to the body unit at the joining portion, the washing unit is arranged on the recessed portion of the body unit. Accordingly, a posture of the washing unit which is joined to the body unit is determined by the joining portion. 
     [9] According to one example of the oral cavity washing device, the recessed portion is formed so as to extend in a height direction of the body unit, and the magnet or the ferromagnetic is disposed at a center in the height direction of the body unit on the inner surface side of the recessed portion. With such a configuration, a force of the joining portion where the washing unit is joined to the body unit acts on the whole washing unit in a well-balanced manner. Accordingly, a posture of the washing unit which is joined to the body unit can be made further stable. 
     [10] According to one example of the oral cavity washing device, the first outer wall of the body unit includes a restricting portion which restricts a downward movement of the washing unit mounted on the body unit relative to the body unit. With such a configuration, when the washing unit which is joined to the body unit moves downward relative to the body unit due to its own weight, the washing unit is brought into contact with the restricting portion. Accordingly, a position of the washing unit in a height direction relative to the body unit is determined. 
     [11] According to one example of the oral cavity washing device, the washing unit includes the second case including the grip portion, and a nozzle which is provided to the second case so as to discharge a washing liquid, and the second joining portion is formed on the grip portion. With such a configuration, downsizing of the nozzle can be realized. 
     [12] According to one example of the oral cavity washing device, the second case includes a first end portion on which the nozzle is mounted, and a first end surface which is formed on the first end portion. Further, the oral cavity washing device is configured such that, in a state where the washing unit is mounted on the body unit, the first end surface is disposed on substantially the same plane as an upper surface of the body unit. With such a configuration, a positional relationship between the first end surface and the upper surface of the body unit can be utilized as a mark when the washing unit is mounted on the body unit. 
     [13] According to one example of the oral cavity washing device, the body unit further includes an arranging portion which is formed on the body unit so as to arrange a tube on the arranging portion in a state where the washing unit is mounted on the body unit. The arranging portion includes a recessed portion formed on the body unit. With such a configuration, in a state where the washing unit is mounted on the body unit, the tube can be accommodated in the arranging portion. 
     [14] According to one example of the oral cavity washing device, the second case is configured such that a second end portion on a side opposite to the first end portion opposedly faces the arranging portion in a state where the washing unit is mounted on the body unit. With such a configuration, a user can easily grasp the second end portion when the user removes the washing unit from the body unit. As a result, the washing unit can be easily removed from the body unit. 
     Exemplary Embodiment 
     Hereinafter, a schematic configuration of oral cavity washing device  1  according to an exemplary embodiment is described with reference to  FIG. 1 . 
       FIG. 1  is a perspective view showing an external appearance of oral cavity washing device  1  according to the exemplary embodiment. Oral cavity washing device  1  is used for washing the inside of an oral cavity, mainly for washing teeth and gums in the oral cavity. Oral cavity washing device  1  is used in a state where oral cavity washing device  1  is mounted on a flat mounting surface such as a washstand (not shown in the drawing), for example. Oral cavity washing device  1  is driven by electric power supplied from an external power source (not shown in the drawing) such as a commercial power source, and is configured to discharge a washing liquid to the inside of the oral cavity. As one example, the washing liquid is clean water into which detergent is mixed or clean water. 
     Oral cavity washing device  1  includes body unit  10 , tube  80 , washing unit  100 , and power source cord PC. Body unit  10  includes device body  20  and tank  70 . Tank  70  stores a washing liquid. Tank  70  is detachably mounted on device body  20 , for example. 
     Device body  20  accommodates various kinds of elements for driving oral cavity washing device  1 . To be more specific, device body  20  includes first case  21  (case), pump  31 , motor  32 , and power source circuit  33  (see  FIG. 7 ). Pump  31 , motor  32 , and power source circuit  33  are accommodated in first case  21 . Pump  31  discharges a washing liquid stored in tank  70 . Motor  32  drives pump  31 . Power source circuit  33  supplies power to motor  32 . Power source cord PC is electrically connected with power source circuit  33 . A plug PG of power source cord PC is connected to an external power source. With such a configuration, power of the external power source is supplied to power source circuit  33  via power source cord PC. 
     Tube  80  is connected with body unit  10  thus making a washing liquid discharged from pump  31  flow through body unit  10 . Washing unit  100  is connected with tube  80 , and discharges a washing liquid. Washing unit  100  is detachably mounted on body unit  10 .  FIG. 1  shows a state where washing unit  100  is mounted on body unit  10 . When a user uses washing unit  100  for washing the inside of his or her oral cavity, washing unit  100  is removed from body unit  10 . 
     First case  21  (case) of device body  20  is formed by joining a plurality of parts  22 . First case  21  is made of a material such as an acrylonitrile butadiene styrene (ABS) resin. The plurality of parts  22  include an upper lid  23 , case body  30 , bottom lid  24 , and arranging portion  40 . Respective parts  22  are respectively formed of individually molded products using a resin material. Upper lid  23 , bottom lid  24 , and arranging portion  40  are respectively joined to case body  30 . Upper lid  23  forms flat upper surface  23 A of device body  20 . 
     Tube  80  is formed of a curl tube which is curled in an extensible and shrinkable manner, for example. It is preferable that a kind of a material for forming tube  80 , a diameter of tube  80 , a wall thickness of tube  80  be determined from a viewpoint of movability of washing unit  100  when washing unit  100  is moved around body unit  10  and also from a viewpoint of durability of tube  80 , for example. Tube  80  is made of a material such as an ethylene vinyl acetate copolymer (EVA) having a high flexibility, for example. As one example a diameter of tube  80 , it is preferable that the diameter fall within a range of from 3.0 mm to 5.0 mm, for example. To be more specific, the diameter of tube  80  is 4.0 mm as one example. As one example of a wall thickness of tube  80 , it is preferable that the wall thickness fall within a range of from 0.5 mm to 1.5 mm, for example. To be more specific, the wall thickness of tube  80  is 1.0 mm as one example. 
     Washing unit  100  includes second case  101  and nozzle  105 . Nozzle  105  is mounted on first end surface  103 A of second case  101  so as to discharge a washing liquid. Second case  101  is made of a material such as an ABS resin, for example. Second case  101  includes grip portion  102 . Grip portion  102  is configured such that the user can grip washing unit  100  with one hand. Second case  101  includes first end portion  103 , and second end portion  104  which forms an end portion on a side opposite to first end portion  103 . First end portion  103  includes first end surface  103 A. As described above, first end surface  103 A is configured such that nozzle  105  can be mounted on first end surface  103 A. Second end portion  104  includes second end surface  104 A. Tube  80  is inserted into second case  101  from second end surface  104 A, for example, and is connected to an inlet of a passage for a washing liquid, which is formed in second case  101 . Nozzle  105  is connected to an outlet of the passage for a washing liquid. 
     Washing unit  100  further includes an operation part  106 . Operation part  106  is mounted on grip portion  102 . Operation part  106  opens and closes a check valve (not shown in the drawing) mounted in second case  101 . To be more specific, when the check valve is opened by operating operation part  106 , a washing liquid which flows through tube  80  is discharged from discharge port  105 A of nozzle  105 . On the other hand, when the check valve is closed by operating operation part  106 , discharging of the washing liquid from discharge port  105 A of nozzle  105  is stopped. 
     Body unit  10  further includes an operation part  50  and display part  60 . Operation part  50  has a function of selecting operations of body unit  10  mainly relating to a discharge of a washing liquid. Operation part  50  is mounted on an upper surface  23 A of device body  20 , for example. 
     Operation part  50  includes a plurality of buttons. The plurality of buttons include first button  51 , second button  52 , and third button  53 , and function as follows in response to operations by a user. First button  51  is a button for turning on or off the power source of body unit  10 . Second button  52  is a button for increasing a water pressure of a washing liquid discharged from pump  31 . Third button  53  is a button for decreasing a water pressure of a washing liquid discharged from pump  31 . A water pressure of a washing liquid discharged from pump  31  is regulated by an operation of second button  52  and third button  53  within a range of a discharge pressure of pump  31 . To be more specific, it is preferable that a discharge pressure of pump  31  be set to a value which falls within a range of from 3.0 kgf/cm 2  to 8.0 kgf/cm 2 , for example. A water pressure of a washing liquid discharged from discharge port  105 A of nozzle  105  changes corresponding to a water pressure of a washing liquid discharged from pump  31 . 
     It is preferable that a maximum discharge pressure of pump  31  be larger than a predetermined maximum discharge pressure. The predetermined maximum discharge pressure is determined based on a relationship with a discharge pressure of pump  31  and a force in which a washing liquid discharged from discharge port  105 A of nozzle  105  cleans intraoral soil, for example. It is preferable that one example of a predetermined maximum discharge pressure be set to a value which falls within a range of 4 kgf/cm 2  and above. It is more preferable that the predetermined maximum discharge pressure be set to a value which falls within a range of 6 kgf/cm 2  and above. It is further more preferable that the predetermined maximum discharge pressure be set to a value which falls within a range of 8 kgf/cm 2  or more. 
     Display part  60  displays various information associated with operations by operation part  50 . Display part  60  includes a plurality of light emitting diode (LED) lamps which are mounted on upper surface  23 A of device body  20 , for example. A lighting state of the respective LED lamps (for example, the number of lighting) is regulated by second button  52  and third button  53  of operation part  50 , and a change in level of a water pressure of a washing liquid is indicated by such a lighting state of the respective LED lamps. 
     Arranging portion  40  is joined to case body  30 , and in a state where washing unit  100  is mounted on body unit  10 , tube  80  is arranged on arranging portion  40 . Arranging portion  40  includes recessed portion  41 . Recessed portion  41  is configured to accommodate tube  80 . Recessed portion  41  includes an opening  41 A which opens toward front surface  30 D of case body  30 . 
     Oral cavity washing device  1  according to the exemplary embodiment has the above-mentioned schematic configuration. 
     Hereinafter, the configuration of oral cavity washing device  1  as viewed from a front surface side is described with reference to  FIG. 2 . 
       FIG. 2  is a front view of oral cavity washing device  1  showing a state where washing unit  100  where nozzle  105  is removed from second case  101  is mounted on body unit  10 . 
     Second case  101  of washing unit  100  is configured such that second end portion  104  opposedly faces arranging portion  40  in a state where washing unit  100  is mounted on body unit  10 . Accordingly, when a user intends to remove washing unit  100  from body unit  10 , the user can easily grasp second end portion  104 . With such a configuration, the user can easily remove washing unit  100  from body unit  10 . 
     Second case  101  is configured such that first end surface  103 A is disposed on substantially the same plane as upper surface  23 A of device body  20  in a state where washing unit  100  is mounted on body unit  10 . Accordingly, a user can use a positional relationship between first end surface  103 A and upper surface  23 A of device body  20  as one of marks when the user mounts washing unit  100  on body unit  10 . A state where first end surface  103 A is disposed on substantially the same plane as upper surface  23 A includes a state where a step is not formed between first end surface  103 A and upper surface  23 A of device body  20 , and a state where a small step is formed between first end surface  103 A and upper surface  23 A of device body  20 . The small step means a step of a level that a hand moving around body unit  10  is minimally caught by device body  20  and washing unit  100 . That is, the small step means a step of a level which is regarded as not being formed between upper surface  23 A of device body  20  and first end surface  103 A of washing unit  100  or means a step of a level where upper surface  23 A of device body  20  and first end surface  103 A of washing unit  100  are regarded as substantially co-planar with each other. 
     Next, the configuration of oral cavity washing device  1  as viewed in a plan view is described with reference to  FIG. 3 . 
       FIG. 3  is a plan view of oral cavity washing device  1  in a state where washing unit  100  is omitted. 
     It is preferable that a two-dimensional shape of body unit  10  be an elliptical shape or an approximately elliptical shape as viewed in a plan view as shown in  FIG. 3 . A two-dimensional shape of body unit  10  is a two-dimensional shape of body unit  10  in a state where tank  70  is mounted on device body  20 . That is, the two-dimensional shape of body unit  10  is equal to a two-dimensional shape of body unit  10  which is projected on a plane perpendicular to a center axis of body unit  10 . One example of an elliptical shape of a two-dimensional shape of body unit  10  is a circular shape, for example. When the two-dimensional shape of body unit  10  is an elliptical shape or an approximately elliptical shape, a contact area between body unit  10  and tube  80  in a state where tube  80  (see  FIG. 1 ) is brought into contact with body unit  10  is narrowed. 
     One example of a two-dimensional shape of tank  70  or device body  20  is a semi-elliptical shape or an approximately semi-elliptical shape as viewed in a plan view. In such a configuration, a two-dimensional shape of device body  20  is a two-dimensional shape of device body  20  in a state where tank  70  is mounted on device body  20 . 
     It is preferable that a three-dimensional shape of body unit  10  be a columnar shape, an approximately columnar shape, a truncated conical shape, an approximately truncated conical shape, a conical shape, an approximately conical shape, a dual conical shape, an approximately dual conical shape, an elliptical shape, or an approximately elliptical shape. In this case, a three-dimensional shape of body unit  10  is a three-dimensional shape of body unit  10  in a state where tank  70  is mounted on device body  20 . To be more specific, as shown in  FIG. 1 , the three-dimensional shape of body unit  10  is an elliptical columnar shape which is one example of a columnar shape. In a case where a three-dimensional shape of body unit  10  is a shape exemplified above, in a state where tube  80  is accommodated in body unit  10 , a contact area between body unit  10  and tube  80  is narrowed. In a case where a shape of body unit  10  is a dual conical shape, an approximately dual conical shape, an elliptical shape, or an approximately elliptical shape, it is preferable that a support portion (not shown in the drawing) be formed on a bottom portion of body unit  10 . With such a configuration, body unit  10  is mounted on the mounting surface in a stable manner by way of the support portion. 
     Terms indicating a two-dimensional shape and a three-dimensional shape of body unit  10  are classified into terms not including “approximately” which is a prefix and terms including “approximately” which is a prefix. Terms including “approximately” are an approximately elliptical shape, an approximately columnar shape, an approximately truncated conical shape, an approximately conical shape, an approximately dual conical shape, an approximately elliptical shape, and an approximately semi-elliptical shape, for example. A shape described by a term not including “approximately” is referred to as a basic shape. A shape described by a term including “approximately” is referred to as a similar shape. A similar shape is a shape by which an advantageous effect substantially equal to an advantageous effect acquired in a case where a two-dimensional shape or a three-dimensional shape of body unit  10  is a basic shape can be acquired with respect to narrowing of a contact area between body unit  10  and tube  80 . Further, a similar shape includes a shape by which a significant advantageous effect can be acquired compared to a conventional oral cavity washing device where a side surface of a body unit  10  is formed of a flat surface. 
     As described above, in oral cavity washing device  1  according to the exemplary embodiment, a two-dimensional shape and a three-dimensional shape of body unit  10  as viewed in a plan view are respectively formed into a basic shape or a similar shape. Accordingly, a design property of oral cavity washing device  1  can be enhanced. 
     A similar shape of a two-dimensional shape includes following various examples such as a first example, a second example, and a third example. To be more specific, a similar shape of a two-dimensional shape in the first example partially includes a straight line. A similar shape of a two-dimensional shape in the second example partially includes a curved line having a center outside the similar shape. A similar shape of a two-dimensional shape in the third example includes characteristics of both the first example and the second example. 
     The similar shape of the three-dimensional shape includes following various examples such as a first example, a second example, a third example, and a fourth example. A similar shape of a three-dimensional shape in the first example partially includes a flat surface. A similar shape of a three-dimensional shape in the second example partially includes a projecting portion. A similar shape of a three-dimensional shape in the third example partially includes a recessed portion. A similar shape of a three-dimensional shape in the fourth example includes at least two characteristics out of characteristics of the first to third examples. 
     As shown in  FIG. 2 , upper surface  23 A of device body  20  is positioned on substantially the same plane as flat upper surface  75 A (see  FIG. 1 ) of tank  70 , for example, in a state where tank  70  (see  FIG. 1 ) is mounted on device body  20 . Accordingly, a hand of a user moving around body unit  10 , washing unit  100 , tube  80  and the like are minimally caught by body unit  10 . A state where upper surface  23 A is positioned on substantially the same plane as upper surface  75 A includes a state where a step is not formed between upper surface  23 A of device body  20  and upper surface  75 A of tank  70 , and a state where a small step is formed between the upper surface  23 A of device body  20  and upper surface  75 A of tank  70 . The small step means a step of a level that a hand of a user moving around body unit  10 , washing unit  100 , tube  80  and the like are minimally caught by body unit  10 . That is, the small step means a step of a level which is regarded as not being formed between upper surface  23 A of device body  20  and upper surface  75 A of tank  70  or means a step of a level where upper surface  23 A of device body  20  and upper surface  75 A of tank  70  are regarded as substantially co-planar with each other. 
     Next, a mounting configuration of washing unit  100  and device body  20  of oral cavity washing device  1  is described with reference to  FIG. 4  to  FIG. 8 . 
       FIG. 4  is a perspective view showing a state where washing unit  100  is removed from body unit  10 .  FIG. 5  is a cross-sectional view taken along line  5 - 5  in  FIG. 2 .  FIG. 6  is an enlarged view of portion A in  FIG. 5 .  FIG. 7  is a cross-sectional view taken along line  7 - 7  in  FIG. 2 .  FIG. 8  is an enlarged view of portion B in  FIG. 7 . 
     As shown in  FIG. 4 , washing unit  100  further includes removing switch  107 . Removing switch  107  is pushed when nozzle  105  is removed from second case  101 . Removing switch  107  is mounted on a back surface of second case  101  on a side of first end portion  103  (a surface of second case  101  which opposedly faces body unit  10  in a state where washing unit  100  is mounted on body unit  10 ), for example. 
     Oral cavity washing device  1  further includes elastic member  42  indicated by dots in  FIG. 4 . Elastic member  42  is exemplified as a member made of an elastic material such as elastomer, for example and hence, even when elastic member  42  is brought into contact with tube  80 , tube  80  is minimally abraded. Elastic member  42  is mounted on arranging portion  40  with which tube  80  is likely to be brought into contact. With such a configuration, when tube  80  is vibrated due to driving of pump  31  (see  FIG. 7 ), elastic member  42  absorbs the vibrations of tube  80 . Accordingly, abrasion brought about by a contact vibration between tube  80  and elastic member  42  minimally occurs. Further, noises generated by the vibration can be made small compared to a case where vibrating tube  80  is brought into contact with a portion which is not covered by elastic member  42 . 
     Elastic member  42  includes first elastic member  42 A and second elastic member  42 B. First elastic member  42 A is mounted on an edge  41 B of opening  41 A of recessed portion  41 , for example (see  FIG. 5 ). To be more specific, first elastic member  42 A is mounted on whole edge  41 B of opening  41 A, for example. That is, first elastic member  42 A is mounted on edge  41 B of opening  41 A which may strongly come into friction contact with tube  80 . Accordingly, the generation of abrasion of tube  80  can be further decreased. Further, noises generated by the vibration can be made small compared to a case where vibrating tube  80  is brought into contact with a portion which is not covered with first elastic member  42 A. 
     Second elastic member  42 B is mounted on an inner peripheral surface  41 C and bottom surface  41 D of recessed portion  41 , for example. To be more specific, second elastic member  42 B is mounted on whole inner peripheral surface  41 C and whole bottom surface  41 D of recessed portion  41 , for example. That is, second elastic member  42 B is mounted on inner peripheral surface  41 C and bottom surface  41 D of recessed portion  41 , which are easily brought into contact with tube  80 . Accordingly, the generation of abrasion of tube  80  can be further suppressed. Further, noises generated by the vibration can be made small compared to a case where vibrating tube  80  is brought into contact with a portion which is not covered by second elastic member  42 B. 
     Oral cavity washing device  1  further includes joining portion  110 . In joining portion  110 , washing unit  100  is mounted on body unit  10  in a detachable manner. To be more specific, joining portion  110  makes body unit  10  and washing unit  100  joined to each other by a magnetic force. That is, when washing unit  100  is disposed close to body unit  10 , washing unit  100  and body unit  10  are joined to each other by a magnetic force of joining portion  110 . 
     Case body  30  further includes recessed portion  34 . Recessed portion  34  is disposed so as to open on front surface  30 D of case body  30 , for example. Recessed portion  34  has a shape corresponding to a shape of the outer shell of washing unit  100 . To be more specific, surface  34 A of recessed portion  34  forms a space of recessed portion  34 , and has a curved surface corresponding to the outer shell of washing unit  100 , for example. With such a configuration, in a state where washing unit  100  is joined to body unit  10  by joining portion  110 , washing unit  100  is disposed on recessed portion  34  of body unit  10 . Accordingly, a posture of washing unit  100  which is joined to body unit  10  is determined by joining portion  110 . 
     Case body  30  includes first outer wall  30 A and second outer wall  30 B. First outer wall  30 A and second outer wall  30 B form an outer shell of case body  30 . Second outer wall  30 B is mounted on a portion of recessed portion  34  of case body  30 , for example. Second outer wall  30 B is disposed so as to be surrounded by first outer wall  30 A. In such a configuration, removing switch  107  which is mounted on the back surface of second case  101  of washing unit  100  forms a gap between back surface of second case  101  and surface  34 A of recessed portion  34  in a state where washing unit  100  is mounted on body unit  10 . As shown in  FIG. 6 , second outer wall  30 B is formed so as to project to the outside of case body  30  with respect to first outer wall  30 A such that the formed gap is gradually decreased. 
     Joining portion  110  includes first joining portion  111  and second joining portion  112 . First joining portion  111  is mounted on front surface  30 D of case body  30 . To be more specific, first joining portion  111  is mounted on surface  34 A of recessed portion  34  of case body  30 , for example. First joining portion  111  includes magnet  111 A, yoke  111 B (see  FIG. 6 ), and first accommodating portion  111 C (see  FIG. 6 ). Magnet  111 A is made of as a neodymium magnet, for example. Yoke  111 B is mounted on magnet  111 A on a side opposite to second outer wall  30 B of case body  30  (see  FIG. 6 ). With such a configuration, yoke  111 B can make a magnetic flux of magnet  111 A strongly act on second joining portion  112 . Yoke  111 B is made of a material such as low carbon steel, for example. First accommodating portion  111 C is mounted on case body  30 , and accommodates magnet  111 A and yoke  111 B. First accommodating portion  111 C includes second outer wall  30 B and an inner wall  30 C which is disposed in case body  30  (see  FIG. 6 ). 
     Recessed portion  34  of case body  30  is formed so as to extend in a height direction of body unit  10 , for example. A lower end portion  34 B of recessed portion  34  is connected to recessed portion  41  of arranging portion  40 . Magnet  111 A is mounted on an inner surface (tank  70 ) side of recessed portion  34  on second outer wall  30 B of case body  30 . To be more specific, magnet  111 A is mounted on the inner surface side of recessed portion  34  in a vicinity of a center in the height direction of recessed portion  34 , for example. Accordingly, a force of joining portion  110  for joining washing unit  100  to body unit  10  acts on whole washing unit  100  in a well-balanced manner. With such a configuration, a posture of washing unit  100  which is joined to body unit  10  can be made further stable. 
     Second case  101  of washing unit  100  includes first outer wall  101 A and second outer wall  101 B. First outer wall  101 A and second outer wall  101 B form an outer shell of second case  101 . Second outer wall  101 B is mounted on a portion of a back surface of second case  101 , for example. Second outer wall  101 B is surrounded by first outer wall  101 A, and is formed on first outer wall  30 A in a recessed manner toward inside of second case  101 . Second outer wall  101 B of second case  101  is formed into a shape fitted to second outer wall  30 B of case body  30 . With such a configuration, a magnetic force which acts between first joining portion  111  and second joining portion  112  can be increased. 
     Second joining portion  112  is mounted on washing unit  100 . To be more specific, second joining portion  112  is mounted on a back surface of grip portion  102  in a vicinity of an intermediate portion in a height direction (a surface on a side opposite to operation part  106 ). Second joining portion  112  includes ferromagnetic  112 A and second accommodating portion  112 B (see  FIG. 6 ). Ferromagnetic  112 A is made of a cold rolled steel sheet, for example. Accordingly, in a state where washing unit  100  is removed from body unit  10 , second joining portion  112  does not attract a ferromagnetic which exists around oral cavity washing device  1 . Ferromagnetic  112 A forms second joining portion  112  and hence, a manufacturing cost can be decreased compared to a case where both first joining portion  111  and second joining portion  112  include a magnet. Second accommodating portion  112 B includes second outer wall  101 B and an inner wall  101 D which is disposed in second case  101  (see  FIG. 6 ). 
     First outer wall  30 A of case body  30  includes restricting portion  35 . Restricting portion  35  restricts the downward movement of washing unit  100  mounted on body unit  10  with respect to body unit  10 . Restricting portion  35  is mounted on lower end portion  34 B of recessed portion  34  of case body  30 , for example (see  FIG. 4 ). In such a configuration, restricting portion  35  is covered by elastic member  42 , for example. 
     First outer wall  101 A of second case  101  includes contact portion  108 . Contact portion  108  is mounted on a back surface of second end portion  104  of second case  101 , for example. When washing unit  100  moves downward with respect to body unit  10 , contact portion  108  is brought into contact with restricting portion  35  of first outer wall  30 A of case body  30 . That is, also when washing unit  100  joined to body unit  10  moves downward with respect to body unit  10  due to its own weight, contact portion  108  is brought into contact with restricting portion  35 . With such a configuration, a position of washing unit  100  in a height direction with respect to body unit  10  is determined. 
     That is, as shown in  FIG. 5 , in a state where washing unit  100  is mounted on body unit  10 , a position of washing unit  100  with respect to body unit  10  is maintained by joining portion  110  and restricting portion  35 . In a state where washing unit  100  is maintained by joining portion  110  and restricting portion  35  with respect to body unit  10 , first end surface  103 A of second case  101  is disposed on substantially the same plane as upper surface  23 A of device body  20 . 
     Next, a relationship between first joining portion  111  and second joining portion  112  is described with reference to  FIG. 6 . 
     Magnet  111 A of first joining portion  111  is fixed to second outer wall  30 B of case body  30  in first accommodating portion  111 C. Yoke  111 B is mounted on magnet  111 A. In such a configuration, thickness TA 1  of second outer wall  30 B of case body  30  is set smaller than thickness TA 2  of a portion of first outer wall  30 A of case body  30  around second outer wall  30 B in a height direction of body unit  10 . Accordingly, a magnetic force which acts between first joining portion  111  and second joining portion  112  can be increased. 
     Second outer wall  101 B of second case  101  includes thin wall portion  101 C. Ferromagnetic  112 A of second joining portion  112  is fixed to thin wall portion  101 C of second outer wall  101 B in second accommodating portion  112 B. In such a configuration, thickness TB 1  of thin wall portion  101 C of second outer wall  101 B of second case  101  is set smaller than thickness TB 2  of a portion of first outer wall  101 A of second case  101  around second outer wall  101 B in a height direction of washing unit  100 . Accordingly, a magnetic force which acts between first joining portion  111  and second joining portion  112  can be increased. 
     As shown in  FIG. 7 , washing unit  100  is fitted in recessed portion  34  of case body  30 . With such a configuration, washing unit  100  is mounted on body unit  10  in a state where an approximately half of washing unit  100  is embedded in body unit  10 , for example. Accordingly, a large projecting portion is minimally formed in a two-dimensional shape of oral cavity washing device  1  as viewed in a plan view. As a result, a design property of oral cavity washing device  1  can be further enhanced. 
     As shown in  FIG. 8 , thickness TA 1  of second outer wall  30 B of case body  30  is set smaller than thickness TA 3  of a portion of first outer wall  30 A of case body  30  around second outer wall  30 B in a width direction of body unit  10 . Thickness TB 1  of thin wall portion  101 C of second outer wall  101 B of second case  101  is set smaller than thickness TB 3  of a portion of first outer wall  101 A of second case  101  around second outer wall  101 B in a width direction of washing unit  100 . With such a configuration, a magnetic force which acts between first joining portion  111  and second joining portion  112  can be increased. 
     As described above, washing unit  100  of oral cavity washing device  1  is mounted on device body  20  by a magnetic force generated by way of joining portion  110 . 
     Next, in a configuration of body unit  10  of oral cavity washing device  1 , respective elements are individually described with reference to  FIG. 9 . 
       FIG. 9  is an exploded perspective view showing a state where various kinds of elements which form body unit  10  are disassembled. In  FIG. 9 , the illustration of a portion of body unit  10  is omitted. 
     First, tank  70  includes tank body  71 , bottom portion  72 , drain port  73  (see  FIG. 7 ), an outlet  74  (see  FIG. 12 ), lid  75 , and handle  76 . Tank body  71  is configured to store a washing liquid. A washing liquid is poured into tank body  71  from opening  71 A of tank body  71 . Bottom portion  72  forms a bottom surface of tank body  71 . From drain port  73 , a washing liquid stored in tank body  71  is discharged. An amount of a washing liquid to be discharged is regulated by a float valve (not shown in the drawing). Drain port  73  is formed in an inner surface of bottom portion  72 . Outlet  74  is formed in an outer surface of bottom portion  72  so as to be communicated with drain port  73 . Lid  75  is detachably mounted on tank body  71 , and opens and closes opening  71 A of tank body  71 . Lid  75  forms an upper surface  75 A of tank  70  in a state where lid  75  is mounted on tank body  71 . Handle  76  is mounted on tank body  71  at a position in a vicinity of opening  71 A. 
     Next, case body  30  includes support portion  36 . Support portion  36  supports bottom portion  72  of tank  70 . A shape of support portion  36  is a shape similar to shape of tank  70  as viewed in a plan view. Support portion  36  includes water supply port  36 A. Water supply port  36 A is configured to be connectable with outlet  74  of tank  70 . That is, when tank  70  is mounted on device body  20 , outlet  74  of tank  70  is connected to water supply port  36 A of support portion  36 . Water supply port  36 A is connected to pump  31 . Accordingly, a washing liquid stored in tank  70  is discharged from drain port  73 , and is made to flow into pump  31  through outlet  74  and water supply port  36 A. 
     Next, operation part  50  further includes panel  54 . First button  51  to third button  53 , and display part  60  are mounted on panel  54 . Upper lid  23  of first case  21  includes a plurality of holes  23 B through which first button  51  to third button  53  are exposed to the outside. Panel  54  includes a plurality of holes  54 A into which first button  51  to third button  53  are inserted. After panel  54  is fixed to case body  30  by way of a plurality of screws  55 , upper lid  23  is joined to case body  30 . 
     Oral cavity washing device  1  further includes seal structure  120 . Seal structure  120  suppresses the invasion of water into first case  21 . Seal structure  120  is mounted on first case  21 . A protective class of oral cavity washing device  1  is international protection (IP) X7, for example. 
     Seal structure  120  includes first seal portion  121 , and second seal portion  122 . First seal portion  121  seals joint portions  131 A,  131 B,  131 C between plurality of parts  22  in the outer shell of first case  21 . First seal portion  121  includes first seal member  121 A, second seal member  121 B, and third seal member  121 C. 
     First seal member  121 A seals joint portion  131 A between upper lid  23  and case body  30 . First seal member  121 A is made of a material such as rubber, for example. To be more specific, first seal member  121 A is sandwiched between panel  54  of operation part  50  and case body  30 , and panel  54  is fixed to case body  30  by screws  55 . With such a configuration, first seal member  121 A seals joint portion  131 A. 
     Second seal member  121 B seals joint portion  131 B between bottom lid  24  and case body  30 . Second seal member  121 B is made of a material such as rubber, for example. To be more specific, second seal member  121 B is sandwiched between bottom lid  24  and case body  30 , and bottom lid  24  is fixed to case body  30  by screws or the like (not shown in the drawing). With such a configuration, second seal member  121 B seals joint portion  131 B. 
     Third seal member  121 C seals joint portion  131 C between arranging portion  40  and case body  30 . Third seal member  121 C is made of a material such as rubber, for example. To be more specific, third seal member  121 C is sandwiched between arranging portion  40  and case body  30 , and arranging portion  40  is fixed to case body  30  by screw  43  (see  FIG. 4 ). With such a configuration, third seal member  121 C seals joint portion  131 C. 
     Further, second seal portion  122  seals joint portions  132 A,  132 B,  132 C between first case  21  and operation part  50 . Second seal portion  122  includes first seal member  122 A, second seal member  122 B, and third seal member  122 C. 
     First seal member  122 A seals joint portion  132 A between upper lid  23  and first button  51 . First seal member  122 A is made of a material such as rubber, for example. First seal member  122 A is provided so as to seal a gap formed between first button  51  which is inserted into hole  54 A of panel  54  and panel  54  (see  FIG. 10 ), for example. To be more specific, first seal member  122 A is mounted so as to cover a gap formed between first button  51  and panel  54 , and upper lid  23  is joined to case body  30 . With such a configuration, first seal member  122 A seals joint portion  132 A. 
     In the same manner, second seal member  122 B seals joint portion  132 B between upper lid  23  and second button  52 . Third seal member  122 C seals joint portion  132 C between upper lid  23  and third button  53 . Configurations of second seal member  122 B and a configuration of third seal member  122 C are substantially equal to the configuration of first seal member  122 A. 
     As shown in  FIG. 10 , seal structure  120  further includes seal member  61 . Seal member  61  seals joint portion  62  between upper lid  23  and display part  60 . Seal member  61  is made of a material such as rubber, for example. Seal member  61  covers display part  60  so as to seal display part  60 , for example. To be more specific, seal member  61  is mounted so as to cover display part  60 , and upper lid  23  is joined to case body  30 . With such a configuration, seal member  61  seals joint portion  62 . Seal member  61  may be configured to form a portion of second seal portion  122 . 
     As shown in  FIG. 11 , oral cavity washing device  1  further includes connecting portion  81 . Connecting portion  81  is a portion where body unit  10  and tube  80  are connected to each other. To be more specific, connecting portion  81  is disposed in recessed portion  41  of arranging portion  40 , and forms a connecting portion between case body  30  and tube  80 . 
     Seal structure  120  further includes third seal portion  123 . Third seal portion  123  seals joint portion  133  between connecting portion  81  and body unit  10 . Third seal portion  123  is formed of elastic member  123 A such as an O ring, for example. Elastic member  123 A is mounted on arranging portion  40 , and seals connecting portion  81 . To be more specific, third seal portion  123  is sandwiched between connecting portion  81  and arranging portion  40 , and connecting portion  81  is fixed to case body  30  by screw  82  by way of arranging portion  40 . With such a configuration, third seal portion  123  seals joint portion  133 . 
     Oral cavity washing device  1  further includes two elastic members  123 B,  123 C formed of an O ring, for example. Two elastic members  123 B,  123 C suppress leakage of water from flow passage  31 A which connects pump  31  and tube  80  to each other into inside of body unit  10 . 
     Oral cavity washing device  1  further includes pump accommodating portion  37 . Pump accommodating portion  37  accommodates pump  31 . Pump accommodating portion  37  is formed in support portion  36  of case body  30 , for example. Pump accommodating portion  37  is formed by outer wall  36 B of support portion  36 . Pump accommodating portion  37  includes pump support portion  37 A which supports pump  31 . Pump accommodating portion  37  and pump support portion  37 A form a portion of case body  30 . Pump accommodating portion  37  and pump support portion  37 A are made of a resin material such as an ABS, for example, in the same manner as the other portions of case body  30 . Pump support portion  37 A includes ribs (not shown in the drawing) which are formed on an inner surface of outer wall  36 B. Ribs fix pump  31  by a joining unit, for example. The joining unit includes fitting structures which are formed on pump  31  and the ribs respectively. The joining unit is a plurality of screws  38 , for example. 
     As shown in  FIG. 12 , seal structure  120  further includes fourth seal portion  124 . Fourth seal portion  124  seals water supply port  36 A of case body  30 . Fourth seal portion  124  is elastic member  124 A such as an O ring, for example. Fourth seal portion  124  is fitted in water supply port  36 A. With such a configuration, fourth seal portion  124  seals water supply port  36 A. Accordingly, also in a state where when tank  70  is removed from device body  20 , water minimally enters the inside of body unit  10 . 
     Oral cavity washing device  1  further includes elastic member  124 B. Elastic member  124 B is formed of an O ring, for example, and provides sealing between outlet  74  of tank  70  and water supply port  36 A of case body  30 . Elastic member  124 B is fixed to a periphery of outlet  74  of tank  70 . With such a configuration, elastic member  124 B suppresses leakage of a washing liquid discharged from outlet  74  of tank  70  to the outside in a state where tank  70  is mounted on device body  20 . 
     As shown in  FIG. 5 , seal structure  120  further includes fifth seal portion  125 . Fifth seal portion  125  forms waterproof layer  125 A indicated by a double-dashed chain line in  FIG. 5 . Waterproof layer  125 A covers power source circuit  33 . Waterproof layer  125 A is formed of a resin layer made of a urethane resin, for example, which is formed by potting, for example. With such a configuration, a waterproof property of power source circuit  33  can be further enhanced. 
     As shown in  FIG. 13 , device body  20  further includes wiring passage  25 . Wiring passage  25  forms a passage for holding power source cord PC led out from the inside of first case  21 . Wiring passage  25  is disposed on bottom surface  24 A of bottom lid  24 . In this exemplary embodiment, wiring passage  25  is disposed in a bifurcated manner, for example. Wiring passage  25  includes first outlet  25 A and second outlet  25 B. First outlet  25 A and second outlet  25 B are portions where power source cords PC are led out from device body  20 . First outlet  25 A and second outlet  25 B are disposed in line symmetry with respect to a center line of device body  20  in a width direction. First outlet  25 A and second outlet  25 B are disposed on side of bottom lid  24 , for example.  FIG. 13  shows an example where power source cord PC is led out from first outlet  25 A. With such a configuration, installation of oral cavity washing device  1  is minimally restricted by power source cord PC. 
     As shown in  FIG. 14 , device body  20  further includes lead-out portion  26 . Lead-out portion  26  is a portion through which power source cord PC is led out from the inside of first case  21 . Lead-out portion  26  is formed on bottom surface  24 A of bottom lid  24 . 
     Seal structure  120  further includes sixth seal portion  126 . Sixth seal portion  126  provides sealing between bottom lid  24  and power source cord PC in lead-out portion  26 . Sixth seal portion  126  includes bushing  126 A and seal member  126 B. Bushing  126 A is provided to power source cord PC such that bushing  126 A can be inserted into lead-out portion  26 . Bushing  126 A is integrally formed with power source cord PC, for example. Seal member  126 B is formed of an O ring, for example. To be more specific, seal member  126 B is sandwiched between bushing  126 A and lead-out portion  26 , and bushing  126 A is fixed to bottom lid  24  by screws  126 C. With such a configuration, seal member  126 B provides sealing between bushing  126 A and lead-out portion  26 . Seal structure  120  satisfies a protective class of IPX7 by including first seal portion  121  to sixth seal portion  126 . Accordingly, also when body unit  10  is immersed in water, water minimally enters the inside of body unit  10 . As a result, a user can efficiently wash body unit  10 . 
     The respective elements constituting body unit  10  of oral cavity washing device  1  are formed as described above. 
     Hereinafter, one example of steps of using oral cavity washing device  1  is described with reference to  FIG. 1 . 
     Oral cavity washing device  1  is used by a user as follows, for example. 
     In a first step, a user pours a predetermined amount of washing liquid in tank  70 , and mounts tank  70  on device body  20 . 
     In a second step, the user turns on the power source of oral cavity washing device  1  by operating first button  51  of body unit  10 . With such an operation, pump  31  (see  FIG. 7 ) starts to drive. 
     In a third step, the user removes washing unit  100  from body unit  10 , and directs discharge port  105 A of nozzle  105  toward the inside of his or her oral cavity. 
     In a fourth step, the user operates operation part  106  of washing unit  100  so that a washing liquid is discharged to the inside of his or her oral cavity from discharge port  105 A. With such an operation, the inside of the oral cavity is washed with a washing liquid discharged from discharge port  105 A. 
     In a fifth step, the user interrupts or finishes washing of his or her oral cavity using oral cavity washing device  1 . Then, the user mounts washing unit  100  on body unit  10 . In the fifth step, when the user interrupts washing of the inside of his or her oral cavity using oral cavity washing device  1 , the user continues washing of the inside of his or her oral cavity by repeating the third step to the fifth step. 
     During such an operation, in a procedure that a washing liquid is discharged from discharge port  105 A, a washing liquid discharged from pump  31  passes through the inside of tube  80 . Accordingly, tube  80  vibrates by receiving water pressure of a washing liquid which flows through tube  80  and the like. Magnitude of vibrations of tube  80  depends on magnitude of water pressure of a washing liquid discharged from pump  31  as described above. Then, vibrating tube  80  is brought into contact with body unit  10 . 
     Therefore, in oral cavity washing device  1  of this exemplary embodiment, elastic member  42  is mounted on arranging portion  40  with which tube  80  is likely to be brought into contact. Elastic member  42  absorbs vibrations of tube  80 . Accordingly, abrasion of tube  80  minimally occurs. Further, noises generated by the contact between tube  80  and arranging portion  40  can be decreased. 
     In oral cavity washing device  1  of this exemplary embodiment, a two-dimensional shape of body unit  10  as viewed in a plan view is a circular shape, and a three-dimensional shape of body unit  10  is a circular columnar shape. Accordingly, also when tube  80  is brought into contact with body unit  10 , a contact area between body unit  10  and tube  80  is narrowed. With such a configuration, even when pump  31  is driven, in a state where tube  80  is brought into contact with body unit  10 , abrasion of tube  80  minimally occurs. 
     In oral cavity washing device  1  of this exemplary embodiment, in mounting washing unit  100  on body unit  10 , when washing unit  100  is disposed close to body unit  10 , washing unit  100  is joined to body unit  10  by a magnetic force of joining portion  110 . Accordingly, even when washing unit  100  is not positionally aligned with body unit  10  accurately, washing unit  100  can be mounted on body unit  10  at a proper position. 
     (Modification) 
     The description relating to the exemplary embodiment is merely an example that the oral cavity washing device of the present disclosure can take, and does not intend to limit such a mode. The present disclosure can take, besides the exemplary embodiment, a following modification of the exemplary embodiment, and a mode obtained by combining at least two modifications which do not conflict with each other, for example. 
     For example, a configuration of sixth seal portion  126  can be arbitrarily changed. In a first example, as shown in  FIG. 15 , bushing  126 A may be connected to lead-out portion  26  by ultrasonic welding, press-fitting or pressure bonding. With such a configuration, sealing is provided between bushing  126 A and lead-out portion  26 . In a second example, power source cord PC may be integrally formed with bottom lid  24 . With such a configuration, sealing is provided between bottom lid  24  and power source cord PC. 
     A configuration of seal structure  120  shown in  FIG. 9  can be arbitrarily changed. In a first example, first seal portion  121  can take a mode where at least one of first seal member  121 A, second seal member  121 B, and third seal member  121 C is omitted. In a second example, second seal portion  122  can take a mode where at least one of first seal member  122 A, second seal member  122 B, and third seal member  122 C is omitted. In a third example, seal structure  120  shown in  FIG. 5 ,  FIG. 9 ,  FIG. 11  and  FIG. 12  can take a mode where at least one of first seal portion  121 , second seal portion  122 , third seal portion  123 , fourth seal portion  124 , fifth seal portion  125 , and sixth seal portion  126  is omitted. 
     A two-dimensional shape of body unit  10  as viewed in a plan view in  FIG. 3  can be arbitrarily changed. For example, a two-dimensional shape of body unit  10  as viewed in a plan view may be a shape including corners. 
     The relationship between upper surface  23 A of device body  20  and upper surface  75 A of tank  70  shown in  FIG. 1  can be arbitrarily changed. In a first example, upper surface  23 A of device body  20  may be set higher than upper surface  75 A of tank  70 . In a second example, upper surface  23 A of device body  20  may be set lower than upper surface  75 A of tank  70 . In a third example, a portion of upper surface  75 A of tank  70  may be configured to cover upper surface  23 A of device body  20  such that upper surface  75 A of tank  70  forms the whole upper surface of body unit  10 . In a fourth example, a portion of upper surface  23 A of device body  20  may be configured to cover upper surface  75 A of tank  70  such that upper surface  23 A of device body  20  forms the whole portion of an upper surface of body unit  10 . In a fifth example, tank  70  may be detachably mounted on upper surface  23 A of device body  20 . As a relationship between upper surface  23 A of device body  20  and upper surface  75 A of tank  70 , the relationship in a state where tank  70  is mounted on device body  20  is shown. 
     The relationship between first end surface  103 A of second case  101  and upper surface  23 A of device body  20  shown in  FIG. 2  can be arbitrarily changed. In a first example, first end surface  103 A may be set higher than upper surface  23 A of device body  20 . In a second example, first end surface  103 A may be set lower than upper surface  23 A of device body  20 . As a relationship between first end surface  103 A of second case  101  and upper surface  23 A of device body  20 , the relationship in a state where washing unit  100  is mounted on body unit  10  is shown. 
     The relationship between recessed portion  34  of case body  30  and recessed portion  41  of arranging portion  40  shown in  FIG. 4  can be arbitrarily changed. For example, recessed portion  34  of case body  30  may be in a positionally displaced manner from recessed portion  41  of arranging portion  40  in a width direction of body unit  10 . In such a case, second end portion  104  of second case  101  does not opposedly face arranging portion  40  in a state where washing unit  100  is mounted on body unit  10 . The configuration where second end portion  104  of second case  101  does not opposedly face arranging portion  40  includes a configuration where a length of second case  101  is made short. 
     A configuration of elastic member  42  shown in  FIG. 4  and  FIG. 5  can be arbitrarily changed. In a first example, first elastic member  42 A may be mounted on a portion of edge  41 B of opening  41 A. In a second example, second elastic member  42 B may be mounted on a portion of inner peripheral surface  41 C of recessed portion  41 . In a third example, second elastic member  42 B may be mounted on a portion of bottom surface  41 D of recessed portion  41 . In a fourth example, elastic member  42  can take a mode where at least one of first elastic member  42 A and second elastic member  42 B is omitted. 
     First outer wall  30 A of case body  30  shown in  FIG. 4  can take a mode where restricting portion  35  is omitted. In this case, in a state where washing unit  100  is mounted on body unit  10 , the position of washing unit  100  with respect to body unit  10  is maintained only by a magnetic force of joining portion  110 . Accordingly, first outer wall  101 A of second case  101  can take a mode where contact portion  108  is omitted. 
     In recessed portion  34  shown in  FIG. 4 , whether or not magnet  111 A is disposed in a vicinity of a center in height direction of recessed portion  34  can be arbitrarily changed. In a first example, in recessed portion  34 , magnet  111 A may be disposed on an upper side in a height direction of body unit  10 . In a second example, in recessed portion  34 , magnet  111 A may be disposed on a lower side in a height direction of body unit  10 . 
     Whether or not magnet  111 A shown in  FIG. 4  and  FIG. 6  is disposed in first accommodating portion  111 C can be arbitrarily changed. For example, magnet  111 A may be disposed on an outer surface side of recessed portion  34 . In such a case, first accommodating portion  111 C can be omitted from first joining portion  111 . Case body  30  can take a mode where recessed portion  34  is omitted. 
     Whether or not ferromagnetic  112 A shown in  FIG. 6  is disposed in second accommodating portion  112 B can be arbitrarily changed. For example, ferromagnetic  112 A may be disposed on an outer surface side of second case  101 . In this case, second accommodating portion  112 B can be omitted from second joining portion  112 . 
     A relationship between thickness TA 1  of second outer wall  30 B of case body  30  and thicknesses TA 2 , TA 3  of portions of first outer wall  30 A of case body  30  around second outer wall  30 B shown in  FIG. 6  and  FIG. 8  can be arbitrarily changed. In a first example, thickness TA 1  may be set substantially equal to at least one of thicknesses TA 2 , TA 3 . In a second example, thickness TA 1  may be set larger than at least one of thicknesses TA 2 , TA 3 . 
     A relationship between thickness TB 1  of thin wall portion  101 C of second outer wall  101 B of second case  101  and thicknesses TB 2 , TB 3  of portions of first outer wall  101 A of second case  101  around second outer wall  101 B shown in  FIG. 6  and  FIG. 8  can be arbitrarily changed. In a first example, thickness TB 1  may be set substantially equal to at least one of thicknesses TB 2 , TB 3 . In a second example, thickness TB 1  may be set larger than at least one of thicknesses TB 2 , TB 3 . 
     A configuration of joining portion  110  shown in  FIG. 6  can be arbitrarily changed. In a first example, a configuration may be adopted where first joining portion  111  includes a ferromagnetic, and second joining portion  112  includes a magnet. In this case, a manufacturing cost can be reduced compared to a case where both first joining portion  111  and second joining portion  112  include a magnet. In a second example, a configuration may be adopted where first joining portion  111  includes magnet  111 A, and second joining portion  112  includes a magnet such that the magnet and the magnet  111 A attract to each other. In this case, the magnet included in joining portion  110  may be an electromagnet. In a third example, joining portion  110  may be configured to physically join body unit  10  and washing unit  100  to each other. In such a physical joint, one of first joining portion  111  and second joining portion  112  includes a hook, and the other of first joining portion  111  and second joining portion  112  includes a portion to be hooked which can be joined to the hook, for example. That is, oral cavity washing device  1  can take a mode where joining portion  110  of this exemplary embodiment is omitted. 
     Whether or not operation part  50  shown in  FIG. 4  is to be disposed on upper surface  23 A of device body  20  can be arbitrarily changed. For example, operation part  50  may be disposed on a side surface of device body  20 . 
     Whether or not display part  60  shown in  FIG. 4  is to be disposed on upper surface  23 A of device body  20  can be arbitrarily changed. For example, display part  60  may be disposed on a side surface of device body  20 . Oral cavity washing device  1  can take a mode where display part  60  is omitted. 
     Oral cavity washing device  200  according to the modification may include a following configuration which is described with reference to  FIG. 16 . Oral cavity washing device  200  of the modification differs from oral cavity washing device  1  of the exemplary embodiment with respect to a following point, and has substantially the same configuration as oral cavity washing device  1  of the exemplary embodiment with respect to other points. Here, components common to components of oral cavity washing device  1  according to the exemplary embodiment are given the same reference numerals to describe oral cavity washing device  200 , and the description of the common components will be partially or entirely omitted. 
       FIG. 16  is a perspective view showing one example of oral cavity washing device  200  according to the modification. 
     As shown in  FIG. 16 , oral cavity washing device  200  includes body unit  210 , tube  80 , washing unit  220 , and power source cord PC. Body unit  210  includes device body  211 , support base  212 , tank  213 , and operation part  214 . 
     Configurations of device body  211 , tank  213 , operation part  214  and washing unit  220  are substantially equal to the configurations of device body  20 , tank  70 , operation part  50 , and washing unit  100  according to the above-mentioned exemplary embodiment. 
     Tank  213  is detachably mounted on an upper portion of device body  211 . Support base  212  is a base on which washing unit  220  is placed, and is integrally formed with device body  211 . For example, when washing unit  220  is placed on support base  212 , washing unit  220  and body unit  210  are joined to each other by a magnetic force. 
     Body unit  210  further includes arranging portion  215 . Arranging portion  215  is mounted on body unit  210 . In a state where washing unit  220  is mounted on body unit  210 , tube  80  is arranged on arranging portion  215 . For example, arranging portion  215  is formed of a portion surrounded by washing unit  220  placed on support base  212 , side surface  211 A of device body  211 , upper surface  212 A of support base  212 , and side surface  213 A of tank  213 . 
     Oral cavity washing device  200  further includes elastic member  230 . Elastic member  230  is disposed on a portion indicated by dots in  FIG. 16 . Elastic member  230  is made of an elastic material such as elastomer, for example, and hence, even when elastic member  230  is brought into contact with tube  80 , tube  80  is minimally abraded. Elastic member  230  is mounted on arranging portion  215 . 
     Elastic member  230  includes first elastic member  231 , second elastic member  232 , and third elastic member  233 . First elastic member  231  is mounted on side surface  211 A of device body  211 . Second elastic member  232  is mounted on upper surface  212 A of support base  212 . Third elastic member  233  is mounted on side surface  213 A of tank  213 . That is, elastic member  230  is mounted on arranging portion  215  with which tube  80  is likely to be brought into contact. Accordingly, elastic member  230  absorbs vibrations of tube  80  which are generated at the time of operating oral cavity washing device  200 . With such a configuration, generation of abrasion of tube  80  can be suppressed. Elastic member  230  can take a mode where one or two of the above-mentioned first elastic member  231 , second elastic member  232 , and third elastic member  233  is/are omitted. 
     Oral cavity washing device  200  further includes connecting portion  81 , and elastic member  240 . Connecting portion  81  is mounted on arranging portion  215 . One example of elastic member  240  is an O ring. Elastic member  240  is mounted on arranging portion  215  so as to seal connecting portion  81 . With such a configuration, an invasion of water into the inside of body unit  210  from connecting portion  81  can be prevented.