Patent Publication Number: US-11646624-B2

Title: Electric compressor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2019-063153 filed on Mar. 28, 2019 and Japanese Patent Application No. 2019-227824 filed on Dec. 18, 2019, the entire disclosure of which is incorporated herein by reference. 
     The present disclosure relates to an electric compressor. 
     BACKGROUND ART 
     Korean Unexamined Patent Publication No. 10-2018-0120129 mentions a known electric compressor. This electric compressor includes a compression part, a motor, an inverter, a motor housing, an inverter case, and a rotary shaft. 
     The compression part is configured to compress refrigerant that serves as fluid. The motor is configured to drive the compression part. The inverter is configured to control the motor. The motor housing has a bottomed-cylindrical shape and accommodates the motor. The inverter case accommodates the inverter, and is joined to an end portion of the motor housing. 
     The motor housing includes a first housing fastened to the compression part and a second housing fastened to the first housing and the inverter case. The second housing includes a motor peripheral wall and a motor bottom wall. The motor peripheral wall has a cylindrical shape, extends in an axial direction of the rotary shaft, and cooperates with the first housing to accommodate the motor. The motor bottom wall is disposed at an end of the motor peripheral wall in the axial direction. The motor bottom wall has a circular disk shape, extends inwardly from the motor peripheral wall in a radial direction, and faces the inverter case in the axial direction. The motor bottom wall has an opening through which a plurality of lead terminals serving as a conductive member is inserted to connect the motor and the inverter. 
     The inverter case includes an inverter box that contacts an end of the second housing and an inverter cover that is fastened to the inverter box. The inverter box includes a box peripheral wall and an inverter bottom wall. The box peripheral wall has a cylindrical shape, extends in the axial direction, and surrounds the inverter. The inverter bottom wall extends inwardly from the box peripheral wall in a radial direction of the box peripheral wall on the motor housing side. The inverter bottom wall faces the motor bottom wall and contacts the motor bottom wall and the motor peripheral wall. The inverter cover includes a cover peripheral wall and an inverter cover wall. The cover peripheral wall has a cylindrical shape and contacts the box peripheral wall. The inverter cover wall has a circular disk shape and extends in the radial direction, and the inverter cover wall is connected to the cover peripheral wall and faces the inverter. 
     In this electric compressor, power is supplied from outside the compressor to the inverter in the inverter case, and then supplied to the motor via the lead terminals to activate the motor. This activates the compression part, so that an air conditioning device for a vehicle and the like operates. 
     However, the above-described known electric compressor does not include a sealing member for sealing a gap between the motor housing and the inverter case. Accordingly, in this electric compressor, moisture may enter from outside the compressor and contact the lead terminals, and therefore may cause deterioration of lead terminals and/or phase short circuit. 
     In order to prevent this possible problem, a sealing member may be disposed between a circular-ring-shaped first end face, which is formed in the motor peripheral wall or the motor bottom wall and extends in a direction perpendicular to the axial direction, and a circular-ring-shaped second end face, which is formed in the box peripheral wall or the inverter bottom wall of the inverter case and extends in the direction perpendicular to the axial direction. 
     This electric compressor, however, still has such a concern in a state where the electric compressor is in use in a moisture and salty environment. Particularly, when the motor housing and the inverter case are fastened to each other with a plurality of fasteners in the axial direction with too much fastening power of the fasteners in order to seek a sealing effect, the sealing member may be pressed excessively in the axial direction. This may decrease the durability of the sealing member. 
     As a solution to this concern, for example, the sealing member may be held between the motor housing and the inverter case in a radial direction of the motor housing. However, this configuration may cause the sealing member to move in the axial direction of the motor housing, i.e., a direction in which the inverter case is fastened to the motor housing, during the assembly of the inverter case and the motor housing, and may cause the sealing member to be deformed by the movement. This may therefore cause a decrease in the durability or the sealing effect. 
     The present disclosure, which has been made in light of such circumstances, is directed to providing an electric compressor that, even under severe conditions, has high durability and surely reduces a phase short circuit and deterioration of a conductive member through which an inverter and a motor are electrically connected. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, there is provided an electric compressor that includes a compression part, a motor, an inverter, a motor housing, an inverter case, a fastener, and a conductive member. The compression part is configured to compress fluid. The motor is configured to drive the compression part. The inverter is configured to control the motor. 
     The motor housing has a bottomed-cylindrical shape and accommodates the motor. The inverter case is joined to an end portion of the motor housing and accommodates the inverter. The fastener fastens the inverter case to the motor housing in an axial direction of the motor housing. The inverter is electrically connected to the motor through the conductive member. The inverter case includes a case peripheral wall that has a cylindrical shape and surrounds the inverter and the end portion of the motor housing. The end portion of the motor housing has an end face that extends in a radial direction of the motor housing and a peripheral surface that extends in the axial direction of the motor housing and is connected to the end face, and the conductive member is disposed on the end face. A sealing member has a ring shape and is disposed between the peripheral surface and the case peripheral wall. An accommodation groove for accommodating the sealing member is recessed in the peripheral surface. The sealing member is held by the peripheral surface and the case peripheral wall in a radial direction of the sealing member to seal a space in which the conductive member is disposed. 
     Other aspects and advantages of the disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
         FIG.  1    is a longitudinal-sectional view of an electric compressor according to a first embodiment; 
         FIG.  2    is an enlarged-sectional view of a main part of the electric compressor according to the first embodiment; 
         FIG.  3    is an enlarged-sectional view of a main part of an electric compressor according to a second embodiment; and 
         FIG.  4    is an enlarged-sectional view of a main part of an electric compressor according to a reference embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The following will describe an electric compressor according to a first and a second embodiment of the present disclosure with reference to the drawings. 
     First Embodiment 
     As illustrated in  FIG.  1   , an electric compressor according to the first embodiment includes a scroll-type compression part  10 , a motor  12 , an inverter  14 , and a housing  16 . The housing  16  includes a front housing  1 , a motor housing  3 , an inverter case  4 , and a rotary shaft  19 . 
     In the following description, the left side of  FIG.  1    on which the front housing  1  is located corresponds to a front side of the electric compressor, and the right side of  FIG.  1    on which the inverter case  4  is located corresponds to a rear side of the electric compressor. The upper side and the lower side of  FIG.  1    correspond to an upper side and a lower side of the electric compressor, respectively. The front-to-rear direction of the compressor indicated in  FIG.  1    corresponds to an axial direction of the rotary shaft  19  of the embodiment of the present disclosure, and the up-to-down direction of the compressor corresponds to a radial direction of the rotary shaft  19  of the embodiment of the present disclosure. Directions indicated in  FIG.  2    and thereafter correspond to the directions indicated in  FIG.  1   . The front-to-rear direction of the embodiments is merely exemplary. The electric compressor of the present disclosure may be mounted in various postures depending on the vehicle on which the compressor is mounted, so that the front-to-rear direction of the electric compressor may be changed according to the posture. Further, the axial direction and the radial direction of the rotary shaft  19  correspond to those of the motor housing  3 , the inverter case  4 , and a sealing member  55  that will be described later. 
     As illustrated in  FIG.  1   , the front housing  1  and the motor housing  3  are in abutment with each other and fastened to each other with a plurality of bolts  9 . The motor housing  3  includes a motor peripheral wall  3   d  that has a cylindrical shape and extends in the front-to-rear direction, and a motor bottom wall  3   a  that has a disk shape and is disposed at a rear end of the motor peripheral wall  3   d , so that the motor housing  3  has a bottomed-cylindrical shape and has an opening on the front housing  1  side. A shaft supporting member  11  and a fixed scroll  13  are disposed within the motor housing  3 , and the fixed scroll  13  is located in front of the shaft supporting member  11 . The front housing  1  and the motor housing  3  cooperate to accommodate the fixed scroll  13  and the shaft supporting member  11  that are in contact with each other. 
     The motor bottom wall  3   a  has a front surface  30   a  facing frontward and a rear surface  30   b  facing rearward. The rear surface  30   b  serves as an end face of the present disclosure. The rear surface  30   b , i.e., the motor bottom wall  3   a , is located at a rear end of the motor housing  3 . A shaft supporting portion  3   b  having a cylindrical shape projects forward from a center of the front surface  30   a . The shaft supporting member  11  includes a main body  11   a  that has a cylindrical shape and a flange  11   b  that extends outward from an opening edge of a front end of the main body  11   a . The main body  11   a  has a shaft hole  11   c  that is formed through a center of the main body  11   a . The flange  11   b  is fixed to an inner peripheral surface of the motor housing  3 . An anti-rotation pin  17   a  projects forward from a front surface of the flange  11   b  to restrain rotation of a movable scroll  15 , which will be described later, while allowing orbiting of the movable scroll  15 . 
     The rotary shaft  19  extends in the front-to-rear direction, and is inserted through the shaft hole  11   c . The rotary shaft  19  is supported at its opposite ends by the shaft supporting member  11  and the shaft supporting portion  3   b  respectively via a radial bearing  23  and a radial bearing  21 . A sealing member  25  is disposed behind the radial bearing  23 , and seals a gap between the shaft supporting member  11  and the rotary shaft  19 . 
     An eccentric pin  19   a  that has a columnar shape is disposed at a front end of the rotary shaft  19  at a position eccentrically displaced from an axis O of the rotary shaft  19 , and the eccentric pin  19   a  extends in an axial direction of the rotary shaft  19 . The eccentric pin  19   a  is fitted into and supported by a bushing  27 . The bushing  27  is formed integrally with a balancing weight  27   a  that is formed over an approximately half circumference of an outer peripheral surface of the bushing  27  and spreads out in a fan-like shape outwardly from the outer peripheral surface of the bushing  27 . 
     The fixed scroll  13  includes a fixed base plate  13   a , a shell  13   b , and a fixed scroll wall  13   c . The fixed base plate  13   a  has a disk shape and extends in the radial direction. The shell  13   b  has a cylindrical shape and extends rearward from an outer peripheral region of the fixed base plate  13   a . The fixed scroll wall  13   c  is disposed inward of the shell  13   b  and extends rearward in a scroll form from the fixed base plate  13   a.    
     The movable scroll  15  is disposed between the bushing  27  and the fixed scroll  13  via a radial bearing  29 . The movable scroll  15  includes a movable base plate  15   a  that has a disk shape and extends in the radial direction, and a movable scroll wall  15   b  that extends forward from the movable base plate  15   a  in a scroll form. The movable scroll wall  15   b  is engaged with the fixed scroll wall  13   c.    
     The movable base plate  15  has an anti-rotation hole  17   b  that is formed in a rear surface of the movable base plate  15   a  and in which a top end of the anti-rotation pin  17   a  is loosely fitted. A ring  17   c  that has a cylindrical shape is loosely fitted in the anti-rotation hole  17   b . The anti-rotation pin  17   a  slides and rotates on an inner peripheral surface of the ring  17   c , thereby preventing the movable scroll  15  from rotating while allowing the movable scroll  15  to orbit around the axis O. The fixed base plate  13   a , the fixed scroll wall  13   c , the movable base plate  15   a , and the movable scroll wall  15   b  cooperate to define a compression chamber  31 . 
     Within the motor housing  3 , a motor chamber  3   c  is formed behind the shaft supporting member  11 . The motor chamber  3   c  doubles as a suction chamber. A stator  33  is disposed in the motor chamber  3   c  and fixed to an inner peripheral surface of the motor peripheral wall  3   d . A rotor  35  is disposed in the stator  33  and fixed to the rotary shaft  19 . The rotor  35  and the rotary shaft  19  are rotated together by energization of the stator  33  to generate the driving force that is transmitted to the movable scroll  15  via the eccentric pin  19   a  and the bushing  27  to cause the movable scroll  15  to orbit. 
     The motor chamber  3   c  communicates with the outside of the compressor through an inlet  3   e  formed through the motor peripheral wall  3   d . The inlet  3   e  is connected to an evaporator (not illustrated) via piping. The evaporator is connected to an expansion valve and a condenser via piping. Refrigerant at low-pressure and low-temperature is introduced from the evaporator into the motor chamber  3   c  through the inlet  3   e , and supplied to the compression chamber  31  through a suction passage (not illustrated) formed in the shaft supporting member  11 . 
     A discharge chamber  37  is formed between the fixed base plate  13   a  and the front housing  1 . The discharge chamber  37  communicates with the compression chamber  31  through a discharge port  13   d  that is formed through a center of the fixed base plate  13   a . The discharge port  13   d  is opened and closed, in the discharge chamber  37 , by a discharge valve  39  that is disposed on the fixed base plate  13   a . The opening degree of the discharge valve  39  is regulated by a retainer  41  that is disposed on the fixed base plate  13   a.    
     The discharge chamber  37  communicates with the outside of the compressor through an outlet  1   a  that is formed through the front housing  1 . The outlet  1   a  is connected to the condenser (not illustrated) via piping. Refrigerant introduced into the discharge chamber  37  is discharged to the condenser through the outlet  1   a.    
     The compression part  10  configured to compress refrigerant includes the motor chamber  3   c , the rotary shaft  19 , the bushing  27 , the radial bearing  29 , the movable scroll  15 , the fixed scroll  13 , the discharge chamber  37 , the discharge valve  39 , and the retainer  41 . The compression part  10  may include an oil separator (not illustrated) that may be disposed in the discharge chamber  37 . The motor  12  configured to drive the compression part  10  includes the rotor  35 , the stator  33 , and the rotary shaft  19 . The front housing  1 , the motor housing  3 , the compression part  10 , the motor  12 , and the bolt  9  cooperate to form a compressor body  20 . 
     The inverter case  4  includes an inverter box  5  and an inverter cover  7 . The inverter box  5  of the inverter case  4  includes a first peripheral wall  5   a , an inverter bottom wall  5   b , and a second peripheral wall  5   c . The first peripheral wall  5   a  has a cylindrical shape, and extends rearward in a direction of the axis O. The inverter bottom wall  5   b  has a disk shape, extends inwardly from the first peripheral wall  5   a  in the radial direction of the motor housing  3 , and is connected to the first peripheral wall  5   a  on the motor peripheral wall  3   d  side. The inverter bottom wall  5   b  faces the rear surface  30   b  of the motor bottom wall  3   a  in an axial direction of the motor housing  3  and is in contact with the rear surface  30   b . The second peripheral wall  5   c  has a cylindrical shape, and extends forward from the inverter bottom wall  5   b  in the axial direction, in other words, the second peripheral wall  5   c  is located opposite to the first peripheral wall  5   a  in the axial direction of the motor housing  3  with the inverter bottom wall  5   b  disposed between the first peripheral wall  5   a  and the second peripheral wall  5   c . The first peripheral wall  5   a  is integrated with the inverter bottom wall  5   b  and the second peripheral wall  5   c.    
     The inverter cover  7  includes a cover peripheral wall  7   a  and an inverter cover wall  7   b . The cover peripheral wall  7   a  has a cylindrical shape, and has a diameter that is equal to a diameter of the first peripheral wall  5   a  and is coaxial with the first peripheral wall  5   a . The cover peripheral wall  7   a  is disposed in contact with the first peripheral wall  5   a  via a gasket (not illustrated). The first peripheral wall  5   a , the second peripheral wall  5   c , and the cover peripheral wall  7   a  cooperate to serve as a case peripheral wall of the present disclosure. The inverter cover wall  7   b  has a disk shape, is connected to the cover peripheral wall  7   a , and extends inwardly from the cover peripheral wall  7   a  in the radial direction. The cover peripheral wall  7   a  faces the inverter  14 , specifically, a board  14   a  of the inverter  14  in the front-to-rear direction. 
     The inverter  14  is formed integrally with the inverter holder  45  that is made of a resin material. The inverter  14  includes the board  14   a , a switching element  14   b , a coil  14   c , and a connector  14   d . The board  14   a  is disposed on a surface of the inverter holder  45  on the inverter cover  7  side. The switching element  14   b , the coil  14   c , and the connector  14   d  are disposed on the other surface of the inverter holder  45  on the motor housing  3  side. The inverter  14  is connected to an external power source through an opening (not illustrated) formed in the inverter box  5  and the inverter cover  7 . The inverter holder  45  is held in the first peripheral wall  5   a  within the inverter box  5 . 
     The rear surface  30   b  of the motor bottom wall  3   a  extends in the radial direction of the motor housing  3  and has an opening  3   f  that communicates with the motor chamber  3   c , and the inverter bottom wall  5   b  has an opening  5   d  that communicates with the opening  3   f . Three lead terminals  49  each serving as a conductive member of the present disclosure is inserted through the opening  3   f  and the opening  5   d  via an insulator  47 . In other words, the lead terminals  49  are disposed on the rear surface  30   b . Coils of the stator  33  of the motor  12  are electrically connected to the connector  14   d  of the inverter  14  through the lead terminals  49 . 
     As illustrated in  FIG.  2   , the motor housing  3  has, at a rear end thereof, an end portion  50  that has a diameter smaller than a diameter of each of other parts of the motor housing  3 . The end portion  50  has an outer peripheral surface that serves as a first peripheral surface  51 , and the first peripheral surface  51  forms a cylindrical shape and extends in the axial direction of the motor housing  3 . The first peripheral surface  51  serves as a peripheral surface of the present disclosure. That is, the end portion  50  includes the motor bottom wall  3   a  that has the rear surface  30   b , and the first peripheral surface  51 . The first peripheral surface  51  doubles as an outer peripheral surface of the motor bottom wall  3   a . The first peripheral surface  51  is connected to the rear end of the motor peripheral wall  3   d , i.e., the rear surface  30   b.    
     The first peripheral surface  51  has an accommodation groove  71 . The accommodation groove  71  is formed in the first peripheral surface  51  and is recessed in a direction radially away from the second peripheral wall  5   c . The accommodation groove  71  has a circular ring shape and extends over a whole circumference of the first peripheral surface  51  in the circumferential direction. The accommodation groove  71  has a bottom surface  71   a  and a side surface  71   b . The bottom surface  71   a  is flat, and faces the second peripheral wall  5   c  in the radial direction. The side surface  71   b  extends in the radial direction, and is connected to the bottom surface  71   a  and the first peripheral surface  51 . The second peripheral wall  5   c  has a second peripheral surface  53  that forms a cylindrical shape, and the second peripheral surface  53  extends forward in the axial direction and faces the first peripheral surface  51  and the accommodation groove  71 . The first peripheral wall  5   a  and the second peripheral wall  5   c  each have a cylindrical shape, and the cylindrical first peripheral wall  5   a  has a diameter equal to a diameter of the cylindrical second peripheral wall  5   c , and is formed coaxially with the second peripheral wall  5   c . An outer peripheral surface of the first peripheral wall  5   a  is continuously connected to the second peripheral wall  5   c . The first peripheral wall  5   a , the second peripheral wall  5   c , the cover peripheral wall  7   a , and the motor peripheral wall  3   d  have the same diameter and are formed coaxially with each other. 
     The accommodation groove  71 , i.e., the end portion  50  (the first peripheral surface  51 ), cooperates with the second peripheral wall  5   c  to hold the sealing member  55 , which is made of rubber, between the motor housing  3  and the inverter case  4  in a radial direction of the sealing member  55 . The radial direction and an axial direction of the sealing member  55  correspond to those of the motor housing  3  (including the peripheral surface of the present disclosure, i.e., the first peripheral surface  51 ), the inverter case  4  (including the case peripheral wall of the present disclosure, i.e., the first peripheral surface  5   a , the second peripheral wall  5   c , and the cover peripheral wall  7   a ), and the rotary shaft  19 . The sealing member  55  seals a space in which the lead terminals  49  are disposed. More specifically, the sealing member  55  has a circular ring shape. The sealing member  55  has a plurality of raised portions  55   a  in a form of a plurality of lines on an inner peripheral surface of the sealing member  55  that faces the accommodation groove  71  and on an outer peripheral surface of the sealing member  55  that faces the second peripheral surface  53 . Each of the raised portions  55   a  has a circular ring shape along the inner peripheral surface and the outer peripheral surface of the sealing member  55 . The sealing member  55  is disposed between the accommodation groove  71  and the second peripheral surface  53 , i.e., between the first peripheral surface  51  and the second peripheral surface  53 , with the sealing member  55  accommodated in the accommodation groove  71 . The whole of the sealing member  55  is accommodated in the accommodation groove  71  in the axial direction; however, a part of an outer periphery of the sealing member  55 , which includes the outer peripheral surface of the sealing member  55 , protrudes from the accommodation groove  71 . In other words, the accommodation groove  71  has a depth capable of accommodating an approximately radial half of the sealing member  55 . The sealing member  55  in the accommodation groove  71  is held between the bottom surface  71   a  and the second peripheral wall  5   c  in the radial direction of the sealing member  55 , and a whole outer periphery of the sealing member  55  is covered by the second peripheral wall  5   c . Accordingly, the whole of the sealing member  55  is hidden from the outside of the electric compressor by the second peripheral wall  5   c . The first peripheral wall  5   a  surrounds the inverter  14  and the second peripheral wall  5   c  surrounds the end portion  50 . 
     The inverter cover wall  7   b  of the inverter cover  7 , the inverter holder  45 , the inverter bottom wall  5   b  of the inverter box  5 , and the motor peripheral wall  3   d  have a plurality of bolt holes  7   c , a plurality of bolt holes  45   a , a plurality of bolt holes  5   e , and a plurality of bolt holes  3   g , respectively. A plurality of fasteners, which in this embodiment, is a plurality of bolts  43  is inserted through the bolt holes  7   c ,  45   a ,  5   e  and screwed into the bolt holes  3   g . That is, the bolts  43  penetrate through the inverter case  4  and are fastened to one end of the motor housing  3 . 
     The electric compressor configured as described above cooperates with the evaporator, the expansion valve, and the condenser to form the refrigeration circuit of an air conditioning device for a vehicle. This electric compressor operates as described below. When a driver of the vehicle activates the air conditioning device, the inverter  14  controls the motor  12  to rotate the rotor  35  and the rotary shaft  19 . Accordingly, the eccentric pin  19   a  orbits around the axis O. The anti-rotation pin  17   a  slides and rotates along the inner peripheral surface of the ring  17   c , thereby restraining the rotation of the movable scroll  15  while allowing the orbiting of the movable scroll  15  around the axis O. The orbiting of the movable scroll  15  moves the compression chamber  31  from the outer periphery side of the fixed scroll  13  and the movable scroll  15  toward the center of the fixed scroll  13  and the movable scroll  15  while decreasing a volume of the compression chamber  31 . Accordingly, the refrigerant supplied to the motor chamber  3   c  from the evaporator through the inlet  3   e  is introduced into and compressed in the compression chamber  31 . The refrigerant compressed to a discharge pressure is discharged into the discharge chamber  37  through the discharge port  13   d , and ejected into the condenser through the outlet  1   a . Therefore, the air conditioning is performed by the air conditioning device for a vehicle as described above. 
     In this electric compressor, the ring-shaped sealing member  55  seals a gap between the bottom surface  71   a  of the accommodation groove  71  and the second peripheral surface  53  of the second peripheral wall  5   c  of the inverter box  5 , i.e., a gap between the end portion  50  and the second peripheral wall  5   c.    
     In this electric compressor, the plurality of bolts  43  fastens the motor housing  3  to the inverter case  4  in an axial direction of the motor housing  3 , and the sealing member  55  is disposed between the accommodation groove  71  and the second peripheral wall  5   c , i.e., between the first peripheral surface  51  of the end portion  50  and the second peripheral surface  53  of the second peripheral wall  5   c . The first peripheral surface  51  in which the accommodation groove  71  is formed forms a cylindrical shape and extends in the axial direction, and the second peripheral surface  53  forms a cylindrical shape and extends in the axial direction. This configuration prevents the sealing member  55  from being axially pressed by a fastening power of the bolts  43 . In this electric compressor, the sealing member  55  is accommodated in the accommodation groove  71  that is formed in the end portion  50  of the motor housing  3 , more specifically, in the first peripheral surface  51  of the end portion  50 . The sealing member  55  contacts the accommodation groove  71 , more specifically, the side surface  71   b  of the accommodation groove  71  if the sealing member  55  moves in the axial direction during the assembly of the motor housing  3  and the inverter box  5  in the axial direction or during the fastening of the inverter case  4  to the motor housing  3  with the bolts  43  in the axial direction of the motor housing  3 . This configuration restricts the sealing member  55  from moving out of the accommodation groove  71  in the axial direction. Accordingly, the sealing member  55  is unlikely to displace relative to the first peripheral surface  51  and the second peripheral surface  53  in the axial direction, and seals the gap between the end portion  50  and the second peripheral wall  5   c  at an appropriate position. 
     Furthermore, in this electric compressor, the first peripheral wall  5   a  and the second peripheral wall  5   c  extend from the inverter bottom wall  5   b  in opposite directions, and this configuration allows the inverter case  4  to have sufficient rigidity to resist a high fastening force. 
     Particularly, in this electric compressor, the first peripheral wall  5   a  and the second peripheral wall  5   c  each have a cylindrical shape and have an equal diameter to form one continuous peripheral wall, so that the inverter case  4  easily exhibits the required strength even if a wall thickness of the inverter case  4  is reduced for weight reduction. Accordingly, the inverter case  4  exhibits excellent durability. 
     The sealing member  55  has the ring-shaped raised portions  55   a  in a form of a plurality of lines on each of the outer peripheral surface and the inner peripheral surface of the sealing member  55 , so that the sealing member  55  contacts the bottom surface  71   a  of the accommodation groove  71  and the second peripheral surface  53  of the second peripheral wall  5   c  at the plurality of lines. This configuration prevents moisture from entering from outside the compressor at the raised portion  55   a  as the second-outermost line on the outer peripheral surface of the sealing member  55  and/or the raised portion  55   a  as the second-outermost line on the inner peripheral surface of the sealing member  55  even if the moisture from the outside has crossed the raised portion  55   a  as the outermost line on the outer peripheral surface on the sealing member  55  and/or the raised portion  55   a  as the outermost line on the inner peripheral surface of the sealing member  55 , so that the sealing member  55  exhibits a higher sealing effect. Accordingly, the sealing member  55  exhibits excellent durability and a preferred sealing effect. 
     Therefore, in this electric compressor, the lead terminals  49  are unlikely to contact moisture outside the compressor even in a state where the electric compressor is in use in a moisture and salty environment, and the deterioration of the lead terminals  49  and a short circuit are therefore surely reduced. The sealing member  55  does not contact the bottom surface  71   a  and the second peripheral surface  53 , except at the raised portions  55   a . That is, the sealing member  55  only makes point contact with the bottom surface  71   a  and the second peripheral surface  53  at the raised portions  55   a . This reduces an area of contact between the sealing member  55  and the bottom surface  71   a  and an area of contact between the sealing member  55  and the second peripheral surface  53 . However, as described above, the accommodation groove  71  of this electric compressor restricts the movement of the sealing member  55  in the axial direction. Accordingly, the sealing member  55  is not easily deformed by the movement of the sealing member  55  in the axial direction although the area of contact between the sealing member  55  and the bottom surface  71   a  and the area of contact between the sealing member  55  and the second peripheral surface  53  are reduced. This electric compressor surely prevents a possibility that one or some of the raised portions  55   a  leave or do not fully contact the bottom surface  71   a  or the second peripheral surface  53  during the assembly of the motor housing  3  and the inverter box  5  in the axial direction or during the fastening of the inverter case  4  to the motor housing  3  with the bolts  43  in the axial direction of the motor housing  3 . 
     Therefore, even under severe conditions, this electric compressor has higher durability and surely reduces a deterioration of the lead terminals  49  and a short circuit. 
     In this electric compressor, the first peripheral surface  51  and the second peripheral surface  53  each form a cylindrical shape, and the sealing member  55  and the accommodation groove  71  each have a circular ring shape. Accordingly, when the axial direction of the electric compressor is set horizontally, the moisture, which may have reached the first peripheral surface  51  or the second peripheral surface  53  from outside the compressor, is easy to drain outside the sealing member  55  under moisture&#39;s own weight without entering inside the sealing member  55 . Therefore, the compressor reduces the deterioration of the sealing member  55 , the motor housing  3 , and the inverter case  4 , thereby exhibiting higher durability. 
     Furthermore, in the electric compressor, the inverter case  4  is fastened to the motor housing  3 , so that the second peripheral wall  5   c  covers the whole of the accommodation groove  71  from the outer side of the compressor. Accordingly, the second peripheral wall  5   c  also covers the whole of the sealing member  55  in the accommodation groove  71  from the outer side of the compressor. Therefore, in this electric compressor, the sealing member  55  is unlikely to be deteriorated by ultraviolet, thereby exhibiting higher durability. The second peripheral wall  5   c  covers the whole of the accommodation groove  71  and the sealing member  55  in such a manner, so that moisture is unlikely to reach the sealing member  55  from outside the electric compressor. Particularly, the sealing member  55  contacts the bottom surface  71   a  and the second peripheral surface  53  at the plurality of lines of the sealing member  55 , so that the second-outermost line prevents moisture from entering the compressor even if the moisture from the outside has crossed the outermost line. Accordingly, the sealing member  55  exhibits a higher sealing effect. 
     In this electric compressor, the motor housing  3  has the motor chamber  3   c  that doubles as the suction chamber, and the rear surface  30   b  of the motor bottom wall  3   a  of the motor housing  3  contacts the inverter bottom wall  5   b . This configuration facilitates the cooling of the inverter  14 . The switching element  14   b  and the coil  14   c  may contact the inverter bottom wall  5   b  if the cooling of the switching element  14   b  and the coil  14   c  is desired especially. 
     In this electric compressor, the inverter case  4  serves as an individual container that is formed separately from the motor housing  3 , in contrast to an electric compressor in which a cup-shaped member is joined to an end face of the motor housing  3  to form an inverter accommodation chamber. This configuration makes it easy to increase the size of a space for accommodating the inverter  14  as the inverter  14  including a filter element increases in size. This increases the weight of the inverter case  4  and the inverter  14  and requires a high tightening force of the fasteners, but does not deteriorate the sealing member  55 . 
     Second Embodiment 
     As illustrated in  FIG.  3   , an electric compressor according to a second embodiment includes an inverter case  8  and a sealing member  56  instead of the inverter case  4  and the sealing member  55  of the electric compressor according to the first embodiment. In the electric compressor according to the first embodiment, the inverter case  4  is formed of two members such as the inverter box  5  and the inverter cover  7   m . In contrast, in the electric compressor according to the second embodiment, the inverter case  8  is formed of a single member. 
     The inverter case  8  includes a case peripheral wall  8   a  and a case bottom wall  8   b . The case peripheral wall  8   a  has a cylindrical shape and extends in the axial direction. More specifically, the cylindrical case peripheral wall  8   a  has a diameter that is equal to a diameter of the motor peripheral wall  3   d  of the motor housing  3  and is coaxial with the motor peripheral wall  3   d . That is, the diameter of the case peripheral wall  8   a  is larger than a diameter of the end portion  50  of the motor housing  3 . The case peripheral wall  8   a  has a third peripheral surface  81  that faces the first peripheral surface  51  of the end portion  50  and the accommodation groove  71 . 
     The case bottom wall  8   b  has a disk shape. The case bottom wall  8   b  is connected to the case peripheral wall  8   a  and extends inwardly from the case peripheral wall  8   a  in a radial direction of the case peripheral wall  8   a . The case bottom wall  8   b  has a plurality of bolt holes  8   c . The inverter case  8  does not include the inverter bottom wall  5   b . Accordingly, the inverter case  8  has a bottomed-cylindrical shape, that is, a cup shape by using the case peripheral wall  8   a  and the case bottom wall  8   b.    
     In this electric compressor, the inverter case  8  accommodates the inverter  14  and the inverter holder  45 , and is joined to the end portion  50  of the motor housing  3  with the plurality of bolts  43 . Accordingly, the case peripheral wall  8   a  of the inverter case  8  surrounds the end portion  50  while surrounding the inverter  14  and the inverter holder  45 . The case bottom wall  8   b  faces the board  14   a  of the inverter  14  in the front-to-rear direction. Since the inverter case  8  does not include the inverter bottom wall  5   b , the inverter holder  45  is held by the rear surface  30   b  of the motor bottom wall  3   a  of the motor housing  3 . 
     The sealing member  56  is made of rubber and has a circular ring shape similar to the sealing member  55 . However, the sealing member  56  does not include the raised portions  55   a  in contrast to the sealing member  55 . The sealing member  56  has a rectangular shape in a radial-sectional view of the sealing member  56 . More specifically, in a radial-sectional view of the sealing member  56 , the sealing member  56  has a rectangular shape wherein edges of the sealing member  56  in the axial direction are longer than edges of the sealing member  56  in the radial direction. 
     The sealing member  56  is disposed between the bottom surface  71   a  of the accommodation groove  71  and the third peripheral surface  81 , i.e., between the first peripheral surface  51  and the third peripheral surface  81 , with the sealing member  56  accommodated in the accommodation groove  71 . The whole of the sealing member  56  is accommodated in the accommodation groove  71  in the axial direction; however, a part of an outer periphery of the sealing member  56 , which includes an outer peripheral surface of the sealing member  56 , protrudes from the accommodation groove  71 . The sealing member  56  in the accommodation groove  71  is held by the bottom surface  71   a  and the case peripheral wall  8   a  in a radial direction of the sealing member  56 , thereby sealing a space in which the lead terminals  49  are disposed. The radial direction and an axial direction of the sealing member  56  correspond to those of the motor housing  3  (including the peripheral surface of the present disclosure, i.e., the first peripheral surface  51 ), the inverter case  8  (including the case peripheral wall of the present disclosure, i.e., the case peripheral wall  8   a ), and the rotary shaft  19 . A whole outer periphery of the sealing member  56  is covered by the case peripheral wall  8   a . Accordingly, a whole of the sealing member  56  is hidden from the outside of the electric compressor by the case peripheral wall  8   a . Other configurations of the electric compressor of this embodiment are the same as those of the electric compressor of the first embodiment with the same reference characters denoting the same components, and the detailed description thereof is not repeated. 
     In this electric compressor, the sealing member  56  has a rectangular shape in the radial-sectional view of the sealing member  56 , so that the outer peripheral surface and the inner peripheral surface of the sealing member  56  respectively make a surface contact with the third peripheral surface  81  and the bottom surface  71   a . This configuration secures a large area of contact between the sealing member  56  and the third peripheral surface  81  and a large area of contact between the sealing member  56  and the bottom surface  71   a . Particularly, in the radial-sectional view of the sealing member  56 , the sealing member  56  has a rectangular shape, and the edges of the sealing member  56  in the axial direction are longer than the edges of the sealing member  56  in the radial direction. Accordingly, this electric compressor has a large area of contact between the sealing member  56  and the third peripheral surface  81  and a large area of contact between the sealing member  56  and the bottom surface  71   a , compared with a case where the sealing member  56  has a square shape in the radial-sectional view of the sealing member  56 . Therefore, in this electric compressor, the sealing member  56  suitably seals a gap between the bottom surface  71   a  and the third peripheral surface  81 , i.e., a gap between the end portion  50  and the case peripheral wall  8   a . The sealing member  56  does not need the raised portions  55   a  unlike the sealing member  55 , so that the sealing member  56  has a simple configuration compared with the sealing member  55 . Therefore, in this electric compressor, the sealing member  56  is easy to form. 
     In this electric compressor, the inverter case  8  is formed of a single member, and the inverter case  8  includes a case peripheral wall  8   a  and a case bottom wall  8   b  to have a bottomed-cylindrical shape. This configuration allows the electric compressor of this embodiment to have a reduced number of parts, thereby reducing the manufacturing cost, in comparison with the electric compressor of the first embodiment. Other advantageous effects of the electric compressor of this embodiment are the same as those of the electric compressor of the first embodiment. 
     Reference Embodiment 
     In an electric compressor according to a reference embodiment, as illustrated in  FIG.  4   , the motor housing  3  includes a cylindrical portion  3   j  having a cylindrical shape at a rear end of the motor bottom wall  3   a , and the cylindrical portion  3   j  has an inner peripheral surface that serves as a first peripheral surface  61 . The first peripheral surface  61  forms a cylindrical shape and extends rearward in the axial direction. The cylindrical portion  3   j  is connected to the motor peripheral wall  3   d . The inverter box  5  includes a first peripheral wall  5   g  and a first peripheral wall  5   h  that is continuously connected to the first peripheral wall  5   g , and does not include the second peripheral wall  5   c  of the first embodiment. A diameter of the first peripheral wall  5   g  is smaller than a diameter of the first peripheral wall  5   h . The first peripheral wall  5   g  has an outer peripheral surface that serves as a second peripheral surface  62 . The second peripheral surface  62  faces the first peripheral surface  61 . The sealing member  55  is disposed between the first peripheral surface  61  and the second peripheral surface  62 . In this electric compressor, the accommodation groove  71  for accommodating the sealing member  55  is not formed in the first peripheral surface  61  or the second peripheral surface  62 . Other configurations of the electric compressor of this embodiment are the same as those of the electric compressor of the first embodiment. 
     This electric compressor may have a concern about strength since the inverter box  5  does not include the second peripheral wall  5   c . Additionally, in this electric compressor, the cylindrical portion  3   j  needs to be formed in the motor housing  3 . This complicates the manufacturing of the motor housing  3 , thereby increasing the manufacturing cost of the electric compressor. Furthermore, since the accommodation groove  71  is not formed in the first peripheral surface  61  or the second peripheral surface  62  in this electric compressor, the sealing member  55  is likely to move in the axial direction during the assembly of the motor housing  3  and the inverter box  5  in the axial direction or during the fastening of the inverter case  4  to the motor housing  3  with the bolts  43  in the axial direction of the motor housing  3 . Accordingly, it is difficult for the sealing member  55  to seal the gap between the first peripheral surface  61  and the second peripheral surface  62  at a suitable position. 
     Although the present disclosure has been described based on the above embodiments, the present disclosure is not limited to the above embodiments, and may be modified within the scope of the present disclosure. 
     For example, the electric compressor of the first embodiment and the second embodiment uses the scroll-type compression part  10 , but the electric compressor of the present disclosure may use other types of compression part, such as a swash scroll type, a vane type, or the like. 
     The configuration of the first embodiment and the configuration of the second embodiment may be combined to form the electric compressor. 
     The present disclosure is applicable to an air conditioning device for a vehicle or the like.