Patent Publication Number: US-2019195348-A1

Title: Electric oil pump

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2017-245617 filed on Dec. 21, 2017. The entire content of which is incorporated herein by reference. 
     BACKGROUND 
     Technical Field 
     The disclosure relates to an electric oil pump. 
     Description of Related Art 
     An electric oil pump having a structure including a pump part, a motor part configured to drive the pump part, and a control part configured to control an operation of the motor part is known. In this electric oil pump, the pump part is disposed on one side of the motor part in the axial direction and a shaft that extends from the motor part penetrates a pump body of the pump part. On one side end surface of the pump body in the axial direction, a housing part in which one side is open in the axial direction of the pump body and the other side in the axial direction is recessed is provided. A pump rotor is accommodated in the housing part. In addition, the control part has a board on which electronic components that drive the motor part are mounted. 
     The electric oil pump of the related art has a structure having a fin in order to improve heat dissipation in many cases. 
     An electric oil pump is used in an environment in which oil flows around. Since the electric oil pump of the related art has a structure having a small fin, there is no need to consider oil around the electric oil pump. However, when a heat dissipating fin is made large in order to improve heat dissipation, oil around the electric oil pump is thought to remain in a groove formed by the heat dissipating fin. When this occurs, there is a risk of oil that remains for a long time causing deterioration and their adverse effects. 
     SUMMARY 
     According to an exemplary embodiment of the disclosure, there is provided an electric oil pump including a motor part having a shaft disposed along a central axis that extends in an axial direction; a pump part that is positioned on one side of the motor part in the axial direction and is driven by the motor part via the shaft and discharges oil; and a control part configured to control an operation of the motor part. The motor part includes a rotor fixed to the other side of the shaft in the axial direction, a stator disposed to face the rotor, and a motor housing in which the rotor and the stator are accommodated. The pump part includes a pump rotor attached to the shaft that protrudes from the motor part to one side in the axial direction and a pump housing having a housing part in which the pump rotor is accommodated. The control part includes a plurality of electronic components and a board on which the plurality of electronic components are mounted. The motor housing has a cylindrical part in which the rotor and the stator are accommodated, a plurality of heat dissipating fins that extend from the cylindrical part and radially outward from the motor part and extend from the cylindrical part in a circumferential direction of the cylindrical part, and a fin support that supports the plurality of heat dissipating fins. The plurality of heat dissipating fins are disposed at intervals in the axial direction, and the fin support has an inter-fin through-hole between the pair of heat dissipating fins adjacent in the axial direction. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an electric oil pump according to a first embodiment. 
         FIG. 2  is a cross-sectional view of the electric oil pump taken along the arrow A-A in  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the electric oil pump taken along the arrow B-B in  FIG. 1 . 
         FIG. 4  is a schematic side view showing a state in which the electric oil pump in  FIG. 1  is attached to a transmission. 
         FIG. 5  is a bottom view of the electric oil pump in  FIG. 1 . 
         FIG. 6  is an enlarged view of an electronic component  82   d  shown in  FIG. 3  and is a cross-sectional view at the position of the electronic component  82   d.    
         FIG. 7  is a cross-sectional view of the electric oil pump taken along the arrow C-C in  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     According to the exemplary embodiment of the disclosure, it is possible to provide an electric oil pump having a structure in which oil is unlikely to remain. 
     An electric oil pump according to an embodiment of the disclosure will be described below with reference to the drawings. In the present embodiment, an electric oil pump configured to supply oil to a transmission mounted on a vehicle such as an automobile will be described. In addition, in the following drawings, in order to allow respective configurations to be easily understood, actual structures and scales and numbers in the structures may be different therefrom. 
     In addition, in the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z axis direction is a direction parallel to an axial direction of a central axis J shown in  FIG. 2  (a vertical direction in  FIG. 1 ). The X axis direction is a direction parallel to a lateral direction of an electric oil pump shown in  FIG. 1 , that is, a left to right direction in  FIG. 1 . The Y axis direction is a direction orthogonal to both the X axis direction and the Z axis direction. 
     In addition, in the following description, the positive side (+Z side) in the Z axis direction will be referred to as “rear side” and the negative side (−Z side) in the Z axis direction will be referred to as “front side.” Here, the rear side and the front side are terms that are simply used for explanation, and do not limit actual positional relationships and directions. In addition, unless otherwise noted, a direction (Z axis direction) parallel to the central axis J is simply defined as an “axial direction,” a radial direction around the central axis J is simply defined as a “radial direction,” and a circumferential direction around the central axis J, that is, a circumference ( 0  direction) around the central axis J is simply defined as a “circumferential direction.” 
     Here, in this specification, the term “extending in the axial direction” includes not only extending strictly in the axial direction (the Z axial direction) but also extending in a direction inclined in a range of less than 45° with respect to the axial direction. In addition, in this specification, the term “extending in the radial direction” includes not only extending strictly in the radial direction, that is, extending in a direction perpendicular to the axial direction (the Z axial direction), but also extending in a direction inclined in a range of less than 45° with respect to the radial direction. 
       FIG. 1  is a plan view of an electric oil pump according to a first embodiment.  FIG. 2  is a cross-sectional view of an electric oil pump  1  taken along the arrow A-A in  FIG. 1 .  FIG. 3  is a cross-sectional view of the electric oil pump  1  taken along the arrow B-B in  FIG. 1 . As shown in,  FIG. 1 , the electric oil pump  1  according to the present embodiment includes a motor part  10 , a pump part  40 , and a control part  82 . The motor part  10  has a shaft  11  that is disposed along the central axis J that extends in the axial direction. The pump part  40  is positioned on one side (front side) of the motor part  10  in the axial direction and is driven by the motor part  10  via the shaft  11 , and discharges oil. The control part  82  is disposed between the motor part  10  and a board cover  61  in the Y axis direction and controls an operation of the motor part  10 . Constituent members will be described below in detail. 
     As shown in  FIG. 2 , the motor part  10  includes the shaft  11 , a rotor  20 , a stator  22 , and a cylindrical part  13   d  of a motor housing  13 . 
     The motor part  10  is, for example, an inner rotor type motor, the rotor  20  is fixed to the outer circumferential surface of the shaft  11 , and the stator  22  is positioned outside the rotor  20  in the radial direction. The rotor  20  is fixed to the other side of the shaft  11  in the axial direction (the rear side with respect to the pump part  40 ). The stator  22  is disposed to face the rotor  20 . 
     The motor housing  13  includes the cylindrical part  13   d  having a cylindrical shape that covers the stator  22  and a case  50  that extends in a direction orthogonal to the axial direction from the outer surface of the cylindrical part  13   d . The rotor  20  and the stator  22  are accommodated in the cylindrical part  13   d . The motor housing  13  includes a stator holding part  13   a , a board support  13   b , and a holding part  13   c . The motor housing  13  is made of a metal. The cylindrical part  13   d  and the case  50  are integrally molded. Therefore, the cylindrical part  13   d  and the case  50  are a single member. A motor cover  72   c  is disposed at an end of the other side (rear side) of the cylindrical part  13   d  in the axial direction and an opening on the other side (rear side) of the cylindrical part  13   d  in the axial direction is covered with the motor cover  72   c.    
     The stator holding part  13   a  has a cylindrical shape that extends in the axial direction. The shaft  11  of the motor part  10 , the rotor  20 , and the stator  22  are disposed in the stator holding part  13   a . The outer surface of the stator  22 , that is, the outer surface of a core back part  22   a  (to be described below), is fitted to an inner circumferential surface  13   a   1  of the stator holding part  13   a . Thereby, the stator  22  is accommodated in the stator holding part  13   a.    
     As shown in  FIG. 3 , the board support  13   b  extends radially outward from the cylindrical part  13   d  of the motor housing  13  and supports a board  82   a  of the control part  82 . The board support  13   b  is integrally molded with the case  50 . Therefore, the board support  13   b  and the case  50  are a single member. 
     As shown in  FIG. 2 , the holding part  13   c  is provided at the rear side end of the cylindrical part  13   d  of the motor housing  13 . The holding part  13   c  is integrally molded with the case  50 . Therefore, the holding part  13   c  and the case  50  are a single member. A bearing housing part  13   f   1  is disposed at and fixed to the rear side end of the cylindrical part  13   d  of the motor housing  13  which is on the inner side of the holding part  13   c  in the radial direction. The bearing housing part  13   f   1  has a shape in which the front side is open and the rear side is recessed. The bearing housing part  13   f   1  has a circular shape when viewed from the front side. The bearing housing part  13   f   1  is disposed coaxially with the central axis J of the shaft  11 . A bearing  16  provided in the bearing housing part  13   f   1  supports the rear side end of the shaft  11 . 
     As shown in  FIG. 2 , the rotor  20  is fixed to the rear side of the shaft  11  with respect to the pump part  40 . The rotor  20  includes a rotor core  20   a  and a rotor magnet  20   b . The rotor core  20   a  surrounds a circumference ( 0  direction) around the shaft  11  and is fixed to the shaft  11 . The rotor magnet  20   b  is fixed to the outer surface along a circumference ( 0  direction) around the rotor core  20   a . The rotor core  20   a  and the rotor magnet  20   b  rotate together with the shaft  11 . Here, the rotor  20  may be an embedded magnet type in which a permanent magnet is embedded inside the rotor  20 . Compared to a surface magnet type in which a permanent magnet is provided on the surface of the rotor  20 , in the embedded magnet type rotor  20 , it is possible to reduce a risk of the magnet being peeled off due to a centrifugal force, and it is possible to actively use a reluctance torque. 
     The stator  22  is disposed to face the rotor  20  outside the rotor  20  in the radial direction and surrounds a circumference (θ direction) around the rotor  20  and rotates the rotor  20  around the central axis J. The stator  22  includes the core back part  22   a , a tooth part  22   c , a coil  22   b , and an insulator (bobbin)  22   d.    
     The shape of the core back part  22   a  is a cylindrical shape concentric with the shaft  11 . The tooth part  22   c  extends from the inner surface of the core back part  22   a  toward the shaft  11 . A plurality of tooth parts  22   c  are provided and are disposed at uniform intervals in the circumferential direction on the inner surface of the core back part  22   a . The coil  22   b  is wound around the insulator  22   d . The insulator  22   d  is attached to each of the tooth parts  22   c.    
     As shown in  FIG. 2 , the shaft  11  extends around the central axis J that extends in the axial direction and penetrates the motor part  10 . The front side (−Z side) of the shaft  11  protrudes from the motor part  10  and extends into the pump part  40 . The front side of the shaft  11  is fixed to an inner rotor  47   a  of the pump part  40 . The front side of the shaft  11  is supported by a bearing  55  (to be described below). Therefore, the shaft  11  is supported at both ends. 
     As shown in  FIG. 3 , the control part  82  includes the board  82   a  and a plurality of electronic components  82   b ,  82   d , and  82   e  mounted on the board  82   a . The control part  82  generates a signal for driving the motor part  10  and outputs the signal to the motor part  10 . The board  82   a  is supported by and fixed to the board support  13   b  that extends radially outward from the cylindrical part  13   d  of the motor housing  13 . 
     As shown in  FIG. 2 , a detection part  72  is disposed to face the rear side end of the shaft  11  and includes a plate-like circuit board  72   a  and a rotation angle sensor  72   b  mounted on the circuit board  72   a . The circuit board  72   a  is supported by and fixed to a board support (not shown) fixed to the rear side end of the cylindrical part  13   d  of the motor housing  13 . A magnet for a rotation angle sensor  72   d  is disposed at and fixed to the rear side end of the shaft  11 . The rotation angle sensor  72   b  faces the magnet for a rotation angle sensor  72   d  and is disposed on the rear side of the magnet for a rotation angle sensor  72   d . When the shaft  11  rotates, the magnet for a rotation angle sensor  72   d  also rotates and thereby a magnetic flux changes. The rotation angle sensor  72   b  detects a change in the magnetic flux due to rotation of the magnet for a rotation angle sensor  72   d  and thereby detects a rotation angle of the shaft  11 . 
     As shown in  FIG. 1  and  FIG. 2 , the pump part  40  is positioned on one side (front side) of the motor part  10  in the axial direction. The pump part  40  is driven by the motor part  10  via the shaft  11 . The pump part  40  includes a pump rotor  47  and a pump housing  51 . In the present embodiment, the pump housing  51  includes a pump body  52  and a pump cover  57 . The pump housing  51  has a housing part  60  for accommodating the pump rotor  47  between the pump body  52  and the pump cover  57 . These components will be described below in detail. 
     As shown in  FIG. 2 , the pump body  52  is disposed at the front side end of the cylindrical part  13   d  of the motor housing  13 . The pump body  52  is integrally molded with the case  50 . Therefore, the pump body  52  and the case  50  are a single member. The pump body  52  has a concave part  54  that is recessed from an end surface  52   c  on the rear side (+Z side) to the front side (−Z side). The bearing  55  and a sealing member  59  are sequentially accommodated in the concave part  54  from the rear side to the front side. The bearing  55  supports the shaft  11  that protrudes from the motor part  10  to one side (front side) in the axial direction. The sealing member  59  seals oil leaking from the pump rotor  47 . 
     The pump body  52  is a single member with respect to the motor housing  13 . Thereby, the bearing  55  in the concave part  54  is positioned in the axial direction. 
     The pump body  52  has a through-hole  56  that penetrates along the central axis J. Both ends of the through-hole  56  in the axial direction are open and the shaft  11  passes therethrough, and an opening on the rear side (+Z side) opens to the concave part  54  and an opening on the front side (−Z side) opens to an end surface  52   d  on the front side of the pump body  52 . 
     As shown in  FIG. 2 , the pump rotor  47  is attached to the front side of the pump body  52 . The pump rotor  47  includes the inner rotor  47   a , an outer rotor  47   b , and a rotor body  47   c . The pump rotor  47  is attached to the shaft  11 . More specifically, the pump rotor  47  is attached to the front side (−Z side) of the shaft  11 . The inner rotor  47   a  is fixed to the shaft  11 . The outer rotor  47   b  surrounds the outside of the inner rotor  47   a  in the radial direction. The rotor body  47   c  surrounds the outside of the outer rotor  47   b  in the radial direction. The rotor body  47   c  is fixed to the pump body  52 . 
     The inner rotor  47   a  has an annular shape. The inner rotor  47   a  is a gear having teeth on the outer surface in the radial direction. The inner rotor  47   a  rotates around a circumference (θ direction) together with the shaft  11 . The outer rotor  47   b  has an annular shape surrounding the outside of the inner rotor  47   a  in the radial direction. The outer rotor  47   b  is a gear having teeth on the inner surface in the radial direction. The outer surface of the outer rotor  47   b  in the radial direction has a circular shape. The inner surface of the rotor body  47   c  in the radial direction has a circular shape. 
     The gear on the outer surface of the inner rotor  47   a  in the radial direction is engaged with the gear on the inner surface of the outer rotor  47   b  in the radial direction, and the outer rotor  47   b  is rotated according to rotation of the inner rotor  47   a  by the shaft  11 . That is, the pump rotor  47  rotates according to rotation of the shaft  11 . In other words, the motor part  10  and the pump part  40  have the same rotation axis. Thereby, it is possible to prevent the size of the electric oil pump  1  from becoming larger in the axial direction. 
     In addition, when the inner rotor  47   a  and the outer rotor  47   b  rotate, a volume between engaging parts of the inner rotor  47   a  and the outer rotor  47   b  changes. An area in which the volume decreases is a pressurized area and an area in which the volume increases is a negative pressure area. An intake port (not shown) of the pump cover  57  is disposed on the front side of the negative pressure area of the pump rotor  47 . In addition, a discharge port of the pump cover  57  (not shown) is disposed on the front side of a pressurized area of the pump rotor  47 . 
     As shown in  FIG. 2 , the pump cover  57  is attached to the front side of the pump rotor  47 . The pump cover  57  is fixed to the rotor body  47   c  of the pump rotor  47 . The pump cover  57  is attached and fixed to the pump body  52  together with the rotor body  47   c  of the pump rotor  47 . The pump cover  57  has an intake opening  41  connected to the intake port. The pump cover  57  has a discharge opening  42  connected to the discharge port. 
     Oil sucked into the pump rotor  47  from the intake opening  41  provided at the pump cover  57  through the intake port of the pump cover  57  is stored in a volume part between the inner rotor  47   a  and the outer rotor  47   b  and is sent to the pressurized area. Then, the oil is discharged from the discharge opening  42  provided at the pump cover  57  through the discharge port of the pump cover  57 . A direction in which the intake opening  41  is sucked is orthogonal to a direction in which oil is discharged from the discharge opening  42 . Thereby, it is possible to reduce a pressure loss from the intake opening to the discharge opening and it is possible to make a flow of oil smooth. 
     As shown in  FIG. 1 , the intake opening  41  is disposed on the side in which the board  82   a  is disposed with respect to the motor part  10 . Thereby, an additionally required disposition space is minimized by arranging a disposition space of the intake opening  41  and a disposition space of the board  82   a  in an overlapping manner and it is possible to reduce the size of the electric oil pump  1  in the radial direction. 
     The pump part  40 , the detection part  72 , and the control part  82  are accommodated in the case  50 . As shown in  FIG. 1  and  FIG. 3 , the case  50  extends from the cylindrical part  13   d  of the motor housing  13  in a direction (X direction) orthogonal to the axial direction. As shown in  FIG. 1  and  FIG. 3 , the case  50  has a board housing part  84  in the +X direction of the cylindrical part  13   d . Thereby, it is possible to reduce the size of the electric oil pump  1  in a direction (Y direction) orthogonal to the axial direction. The board housing part  84  is integrally molded with the case  50 . Therefore, the board housing part  84  and the case  50  are a single member. As shown in  FIG. 1  and  FIG. 3 , the case  50  has a fin part  80  in the −X direction of the cylindrical part  13   d . The fin part  80  is integrally molded with the case  50 . Therefore, the fin part  80  and the case  50  are a single member. The fin part  80  dissipates heat generated from the electric oil pump  1 . While the fin part  80  is disposed on the right side with respect to the cylindrical part  13   d  and the board housing part  84  is disposed on the left side in  FIG. 3 , the fin part  80  may be disposed on the left side with respect to the cylindrical part  13   d  and the board housing part  84  may be disposed on the right side. 
       FIG. 4  is a schematic side view showing a state in which the electric oil pump  1  in  FIG. 1  is attached to a transmission. As shown in  FIG. 4 , the electric oil pump  1  is attached to an attachment surface  102  provided on the bottom surface of a transmission  100 . The electric oil pump  1  is accommodated in an oil pan  101  provided below the transmission  100 . The electric oil pump  1  sucks oil in the oil pan  101  from the intake opening  41  and discharges it from the discharge opening  42 . The case  50  of the electric oil pump  1  has a plurality of attachment parts  63  attached to the attachment surface  102  of the transmission  100 . The attachment part  63  has an attachment through-hole  64  at the center. A bolt (not shown) passes through the attachment through-hole  64  and the electric oil pump  1  is attached to the attachment surface  102  of the transmission  100  using the bolt. The attachment part  63  has a contact surface that comes in contact with the attachment surface  102  when the electric oil pump  1  is attached to the attachment surface  102 . 
     As shown in  FIG. 1 , the plurality of attachment parts  63  are provided at four corners on a surface parallel to the attachment surface  102  (a surface that extends in the X direction). A first attachment part among the plurality of attachment parts  63  is disposed on one side with respect to the stator  22  in the axial direction and on one side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A second attachment part among the plurality of attachment parts  63  is disposed on one side with respect to the stator  22  in the axial direction and on the other side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A third attachment part among the plurality of attachment parts  63  is disposed on the other side with respect to the stator  22  in the axial direction and on one side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A fourth attachment part among the plurality of attachment parts  63  is disposed on the other side with respect to the stator  22  in the axial direction and on the other side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . The plurality of attachment parts  63  may be three or more attachment parts. Thereby, attachment can be performed with the plurality of attachment parts  63  with high accuracy. 
     As shown in  FIG. 3 , the board housing part  84  has a shape in which the side (−Y side) that faces the attachment surface  102  is open and the opposite side (+Y side) is recessed. The board housing part  84  accommodates the board  82   a  in the recess. The surface of the board  82   a  is parallel to the axial direction. The board cover  61  covers the board  82   a . The board housing part  84  has a support  84   a  at the bottom of the recess. The support  84   a  supports a heat dissipating fin  86 . 
     The board cover  61  is disposed at an opening of the board housing part  84  and blocks the opening of the board housing part  84 . The board cover  61  is disposed parallel to the board  82   a . Thereby, it is possible to reduce the size of the electric oil pump  1  in the direction (Y direction) orthogonal to the axial direction. As shown in  FIG. 1 , the board cover  61  has a plurality of fixing parts  85  fixed to the case  50 . When the electric oil pump  1  is attached to the attachment surface  102  of the transmission  100  by the attachment part  63 , the board cover  61  is disposed parallel to the attachment surface  102  of the transmission  100 . Thereby, it is possible to reduce the size of the electric oil pump  1  in the direction (Y direction) orthogonal to the axial direction. 
     As shown in  FIG. 1  and  FIG. 3 , the plurality of fixing parts  85  includes a first fixing part  85   a , a second fixing part  85   b , and a second fixing part  85   c . The first fixing part  85   a  among the plurality of fixing parts  85  is disposed on one side (−X side) with respect to the shaft  11  in a direction parallel to the board  82   a . The second fixing parts  85   b  and  85   c  among the plurality of fixing parts  85  are disposed on the other side (+X side) with respect to the shaft  11  in a direction parallel to the board  82   a . The plurality of fixing parts  85  are, for example, a bolt. Thereby, the plurality of fixing parts  85  can avoid the position of the shaft  11  in the X direction. The position of the shaft  11  in the X direction is a position at which the motor part  10  is the largest in the Y direction. Accordingly, compared to when the plurality of fixing parts  85  are positioned at the position of the shaft  11  in the X direction, according to the present embodiment, it is possible to reduce the size of the electric oil pump  1  in the direction (Y direction) orthogonal to the axial direction while a sufficient length of the bolt is secured. Thereby, the plurality of fixing parts  85  can fix the board cover  61  more firmly. In addition, Thereby, the board cover  61  can cover the entire board  82   a.    
       FIG. 5  is a bottom view of the electric oil pump  1  in  FIG. 1 . The board housing part  84  has a plurality of heat dissipating fins  86  that dissipate heat at an end on the opposite side (+Y side) that faces the attachment surface  102 . The plurality of heat dissipating fins  86  are disposed at intervals in the axial direction. The heat dissipating fin  86  is integrally molded with the case  50 . Therefore, the heat dissipating fin  86  and the case  50  are a single member. 
     The heat dissipating fins  86  extend radially outward from the motor part  10  and extend in the circumferential direction of the cylindrical part  13   d  of the motor housing  13 . The heat dissipating fins  86  extend in a direction crossing the axial direction. The heat dissipating fins  86  extend in a direction orthogonal to the axial direction. As shown in  FIG. 3 , the length of the heat dissipating fin  86  in the circumferential direction is longer on a radially inner side than on a radially outer side. The board housing part  84  has the support  84   a  at an end on the side (−Y side) that faces the board  82   a  of the heat dissipating fin  86 . The support  84   a  is integrally molded with the case  50 . Therefore, the support  84   a  and the case  50  are a single member. The support  84   a  supports the heat dissipating fin  86 . The support  84   a  is a plate-like member that extends radially outward from the cylindrical part  13   d  of the motor housing  13  and in the axial direction. The support  84   a  extends in the axial direction and thus connects the heat dissipating fins  86  adjacent in the axial direction. Thereby, it is possible to reduce swinging of the respective heat dissipating fins  86  in the axial direction, and it is possible to increase the strength of the heat dissipating fins  86  in the axial direction. The support  84   a  extends to the outside in the radial direction and thus connects the heat dissipating fins  86  adjacent in the axial direction also on the outside in the radial direction. Thereby, it is possible to reduce swinging of the respective heat dissipating fins  86  in the axial direction also on the outside in the radial direction, and it is possible to increase the strength of the heat dissipating fins  86  in the axial direction. Here, according to the strength of the heat dissipating fin  86  in the axial direction, swinging of the heat dissipating fins  86  in the axial direction is reduced. The support  84   a  extends in a radially outward direction and in the axial direction and thus heat generated from the control part  82  can be received in a larger area compared to when the support  84   a  is not provided, heat is efficiently transferred to the heat dissipating fin  86 , and a heat dissipation effect can be improved. As shown in  FIG. 3 , the support  84   a  has a heat transfer part  83  that extends toward the board  82   a . The heat transfer part  83  is integrally molded with the case  50 . Therefore, the heat transfer part  83  and the case  50  are a single member. The heat transfer part  83  is a columnar member that extends from the support  84   a  toward the board  82   a . The heat transfer part  83  may have, for example, a prismatic shape or a columnar shape. A distance between an end on the side of the board  82   a  of the heat transfer part  83  and the board  82   a  is shorter than a distance between the support  84   a  and the board  82   a . Thereby, compared to when the heat transfer part  83  is not provided, according to the present embodiment, heat generated from the control part  82  is easily received by the heat transfer part  83 , heat is efficiently transferred to the support  84   a  and the heat dissipating fin  86 , and a heat dissipation effect can be improved. 
     As shown in  FIG. 5 , the board housing part  84  has a rib  87  connecting the plurality of heat dissipating fins  86 . The rib  87  is a columnar member that extends from the support  84   a  to the side (+Y side) opposite to the board  82   a . The rib  87  may have, for example, a prismatic shape or a columnar shape. The rib  87  extends from the support  84   a . Thereby, the rib  87  serves as a path through which heat received in the support  84   a  is transferred to the heat dissipating fin  86  and it is possible to further increase a heat dissipation efficiency of the heat dissipating fin  86 . The rib  87  connects a surface of a heat dissipating fin  86  in the axial direction and a surface of an adjacent heat dissipating fin  86  in the axial direction. Thereby, it is possible to reduce swinging of the respective heat dissipating fins  86  in the axial direction, and it is possible to increase the strength of the heat dissipating fins  86  in the axial direction. Here, according to the strength of the heat dissipating fins  86  in the axial direction, swinging of the heat dissipating fins  86  in the axial direction is reduced. The rib  87  is integrally molded with the case  50 . Therefore, the rib  87  and the case  50  are a single member. 
     As shown in  FIG. 3 , the board  82   a  has an end  82   a   1 . The end  82   a   1  of the board  82   a  is disposed at a position overlapping the cylindrical part  13   d  of the motor housing  13  in a direction orthogonal to the surface of the board  82   a . Thereby, it is possible to reduce the size of the electric oil pump  1  in the direction (X direction) orthogonal to the axial direction. The electronic component  82   b , the electronic component  82   d , the electronic component  82   e  and a connector  82   c  are mounted on the board  82   a . The electronic component  82   b , the electronic component  82   d , and the electronic component  82   e  are a plurality of electronic components. 
     The electronic component  82   e  which is shorter in height than the electronic component  82   b  (the height from the board  82   a  is lower) is mounted on a surface that faces the motor part  10  within the surface of the board  82   a  at a position overlapping the cylindrical part  13   d  of the motor housing  13  in a direction orthogonal to the surface of the board  82   a . Thereby, a position that faces the motor part  10  of the board  82   a  can be used as a component mounting area, it is possible to reduce the size of the board  82   a , and it is possible to reduce the size of the electric oil pump  1 . 
     On a surface that faces the motor part  10  within the surface of the board  82   a  at a position overlapping the cylindrical part  13   d  of the motor housing  13  in a direction orthogonal to the surface of the board  82   a , the electronic component  82   b  which is taller in height than the electronic component  82   e  (the height from the board  82   a  is higher) cannot be mounted because the height serves as an obstacle. Thereby, it is possible to reduce the size of the electric oil pump  1  in the direction (Y direction) orthogonal to the axial direction. 
     The electronic component  82   b  is mounted on a surface that faces the motor part  10  within the surface of the board  82   a  at a position not overlapping the cylindrical part  13   d  of the motor housing  13  in a direction orthogonal to the surface of the board  82   a . The electronic component  82   b  is mounted radially outward from a mounting position of the electronic component  82   e . The electronic component  82   e  has a higher heat resistance than the electronic component  82   b . The electronic component  82   e  is, for example, a resistor. Thereby, a resistor having a high heat resistance which is short in height can be efficiently mounted near the motor part  10 . The electronic component  82   b  is, for example, an electrolytic capacitor. Thereby, it is possible to efficiently mount an electrolytic capacitor which is tall in height and it is possible to keep an electrolytic capacitor having a low heat resistance away from heat generated from the motor part  10 . 
     The connector  82   c  is mounted on a surface that faces the motor part  10  within the surface of the board  82   a  at a position not overlapping the cylindrical part  13   d  of the motor housing  13  in a direction orthogonal to the surface of the board  82   a . The connector  82   c  is taller in height than the electronic component  82   b  (the height from the board  82   a  is higher). The connector  82   c  is mounted radially outward from a mounting position of the electronic component  82   b . Thereby, it is possible to efficiently mount the connector  82   c  which is tall in height. 
     The electronic component  82   d  is mounted on a surface opposite to a surface that faces the motor part  10  within the surface of the board  82   a . The board  82   a  has a first surface and a second surface. The first surface of the board  82   a  is a surface that faces the plurality of heat dissipating fins  86 . The first surface of the board  82   a  is a surface that faces the support  84   a . The second surface of the board  82   a  is a surface opposite to the first surface of the board  82   a . As shown in  FIG. 3 , the electronic component  82   d  is mounted on the second surface of the board  82   a . The electronic component  82   d  is a power semiconductor element for controlling power that drives the motor part  10 . The electronic component  82   d  is a field effect transistor (FET) or an insulated gate bipolar transistor (IGBT). The electronic component  82   d  is a heat generating component that is more likely to generate heat than other components. 
       FIG. 6  is an enlarged view of the electronic component  82   d  shown in  FIG. 3  and is a cross-sectional view at the position of the electronic component  82   d . The board  82   a  has a board through-hole  82   a   2  that penetrates from the second surface of the board  82   a  to the first surface at a position that faces the electronic component  82   d . Heat generated from the electronic component  82   d  is dissipated from the second surface of the board  82   a  to the first surface through the board through-hole  82   a   2 . A thermally conductive member  82   a   3  having thermal conductivity is provided on the inner circumference of the board through-hole  82   a   2 . The thermally conductive member  82   a   3  is, for example, a copper foil. Thereby, it is possible to efficiently dissipate heat generated from the electronic component  82   d.    
     As shown in  FIG. 6 , a heat dissipation member  82   f  is provided on the first surface of the board  82   a . The heat dissipation member  82   f  is provided at a position at which the board through-hole  82   a   2  is covered. The heat dissipation member  82   f  is a member having thermal conductivity. Thereby, it is possible to efficiently dissipate heat generated from the electronic component  82   d . The heat dissipation member  82   f  is an insulating member. As shown in  FIG. 3 , the heat dissipation member  82   f  is in contact with the board  82   a  on the −Y side and is in contact with the heat transfer part  83  on the +Y side. Thereby, it is possible to efficiently dissipate heat generated from the electronic component  82   d.    
       FIG. 7  is a cross-sectional view of the electric oil pump  1  taken along the arrow C-C in  FIG. 1 . The fin part  80  has a fin support  79 . The fin support  79  extends radially outward from the cylindrical part  13   d  of the motor housing  13 . The fin part  80  includes a heat dissipating fin  80   a , a heat dissipating fin  80   b  adjacent to the heat dissipating fin  80   a , a heat dissipating fin  80   c  adjacent to the heat dissipating fin  80   b , a heat dissipating fin  80   d , a heat dissipating fin  80   e  adjacent to the heat dissipating fin  80   d , a heat dissipating fin  80   f  adjacent to the heat dissipating fin  80   e , a heat dissipating fin  80   g  adjacent to the heat dissipating fin  80   f , a heat dissipating fin  80   h  adjacent to the heat dissipating fin  80   g , a heat dissipating fin  80   i  adjacent to the heat dissipating fin  80   h , a heat dissipating fin  80   j  adjacent to the heat dissipating fin  80   i , a heat dissipating fin  80   k  adjacent to the heat dissipating fin  80   j , and a heat dissipating fin  80   l  adjacent to the heat dissipating fin  80   k . The fin support  79  and the heat dissipating fins  80   a  to  80   l  are integrally molded with the case  50 . Therefore, the fin support  79 , the heat dissipating fins  80   a  to  80   l , and the case  50  are a single member. 
     The case  50  has an end  58   a  adjacent to the heat dissipating fin  80   a  on one side (front side) in the axial direction and an end  58   b  adjacent to the heat dissipating fin  80   c  on the other side (rear side) in the axial direction. The ends  58   a  and  58   b  are integrally molded with the case  50 . Therefore, the ends  58   a  and  58   b , and the case  50  are a single member. 
     The heat dissipating fins  80   a  to  80   l  extend radially outward from the cylindrical part  13   d  of the motor housing  13  and extend in the circumferential direction of the cylindrical part  13   d . The heat dissipating fins  80   a  to  80   c  extend from the fin support  79  in the direction (−Y direction) orthogonal to the axial direction. The heat dissipating fins  80   d  to  80   l  extend from the fin support  79  in the direction (+Y direction) orthogonal to the axial direction. The fin support  79  supports the heat dissipating fins  80   a  to  80   l . The heat dissipating fins  80   a  to  80   l  are disposed at intervals in the axial direction. 
     As shown in  FIG. 1  and  FIG. 7 , the fin support  79  has a plurality of inter-fin through-holes  81  that penetrate in the direction (Y direction) orthogonal to the axial direction. The plurality of inter-fin through-holes  81  include a first inter-fin through-hole  81   a , a second inter-fin through-hole  81   b , a third inter-fin through-hole  81   c , a fourth inter-fin through-hole  81   d , and a fifth inter-fin through-hole  81   e . The first inter-fin through-hole  81   a  and the second inter-fin through-hole  81   b  are provided on the surface of the fin support  79  between the end  58   a  and the heat dissipating fin  80   a . The first inter-fin through-hole  81   a  penetrates between the heat dissipating fin  80   d  and the heat dissipating fin  80   e . The second inter-fin through-hole  81   b  penetrates between the heat dissipating fin  80   e  and the heat dissipating fin  80   f . The third inter-fin through-hole  81   c  is provided on the surface of the fin support  79  between the heat dissipating fin  80   a  and the heat dissipating fin  80   b . The third inter-fin through-hole  81   c  penetrates between the heat dissipating fin  80   g  and the heat dissipating fin  80   h . The fourth inter-fin through-hole  81   d  is provided on the surface of the fin support  79  between the heat dissipating fin  80   b  and the heat dissipating fin  80   c . The fourth inter-fin through-hole  81   d  penetrates between the heat dissipating fin  80   i  and the heat dissipating fin  80   j . The fifth inter-fin through-hole  81   e  is provided on the surface of the fin support  79  between the heat dissipating fin  80   c  and the end  58   b . The fifth inter-fin through-hole  81   e  penetrates between the heat dissipating fin  80   l  and the heat dissipating fin  80   l.    
     The plurality of inter-fin through-holes  81  function as an oil loophole. As shown in  FIG. 4 , the electric oil pump  1  is attached to the lower side of the transmission  100 , and oil supplied from the discharge opening  42  to the transmission  100  flows down to the upper part of the electric oil pump  1 . The plurality of inter-fin through-holes  81  serve as a flow path through which oil flowing down to the upper part of the electric oil pump  1  flows to the lower side of the electric oil pump  1  without remaining in the electric oil pump  1 . 
     The third inter-fin through-hole  81   c  and the fifth inter-fin through-hole  81   e  are disposed at a central part between a pair of heat dissipating fins adjacent to the axial direction. Thereby, it is possible to flow oil downward more smoothly. Like the first inter-fin through-hole  81   a  and the second inter-fin through-hole  81   b , a plurality of through-holes may be provided between a pair of heat dissipating fins adjacent in the axial direction. A direction of the first inter-fin through-hole  81   a , the second inter-fin through-hole  81   b , the fourth inter-fin through-hole  81   d , and the fifth inter-fin through-hole  81   e  extends in a direction orthogonal to the attachment surface  102  (in other words, a direction orthogonal to a contact surface of the attachment part  63  that comes in contact with the attachment surface  102  of the transmission  100 ). Thereby, it is possible to flow oil downward more smoothly. Like the third inter-fin through-hole  81   c , a direction thereof may extend in a direction crossing the attachment surface  102  rather than a direction orthogonal to the attachment surface  102 . 
     The plurality of inter-fin through-holes  81  may be disposed on the outside in the radial direction within the surface of the fin support  79 . Thereby, it is possible to increase the strength of the motor part in the axial direction and an operation of forming a through-hole can be easily performed by a tool. 
     The surface of the fin support  79  between adjacent heat dissipating fins may be inclined toward an opening of the inter-fin through-hole  81 . Thereby, it is possible to flow oil downward more smoothly. The inter-fin through-hole  81  has a circular cross-sectional shape in a direction orthogonal to a penetration direction. Thereby, it is possible to flow oil downward more smoothly. 
     The fin support  79  has a first surface and a second surface. The first surface of the fin support  79  is a surface between a pair of heat dissipating fins adjacent in the axial direction. The second surface of the fin support  79  is a surface opposite to the first surface of the fin support  79 . The size of the inner diameter of the inter-fin through-hole  81  decreases from the first surface of the fin support  79  to the second surface of the fin support  79 . Thereby, when a tool is inserted from the first surface of the fin support  79  and the inter-fin through-hole  81  is formed, the tool is easily pulled out and the inter-fin through-hole  81  is easily formed. 
     In the electric oil pump  1 , a part in which there is a risk of oil flowing down to the upper part remaining is not limited to a part between a pair of heat dissipating fins adjacent in the axial direction. In one or some exemplary embodiments, a through-hole is provided as an oil loophole in all parts in which there is a risk of oil flowing down to the upper part remaining. For example, a groove through-hole  66  is provided at an arm  62  of the attachment part  63  shown in  FIG. 1 . 
     The attachment part  63  has the arm  62  that extends toward the stator  22 . The arm  62  has a groove  65  that is open in a direction orthogonal to a contact surface of the attachment part  63  that comes in contact with the attachment surface  102  of the transmission  100 . The groove through-hole  66  is provided at the bottom of the groove  65 . The groove through-hole  66  serves as a flow path through which oil flowing down to the upper part of the electric oil pump  1  flows to the lower side of the electric oil pump  1  without remaining in the electric oil pump  1 . 
     Next, actions and effects of the electric oil pump  1  will be described. As shown in  FIG. 1  and  FIG. 2 , when the motor part  10  of the electric oil pump  1  is driven, the shaft  11  of the motor part  10  rotates, and the outer rotor  47   b  also rotates as the inner rotor  47   a  of the pump rotor  47  rotates. When the pump rotor  47  rotates, oil sucked from the intake opening  41  of the pump part  40  moves into the housing part  60  of the pump part  40 , and is discharged from the discharge opening  42 . 
     (1) Here, in the electric oil pump  1  according to the present embodiment, the fin support  79  that supports the heat dissipating fins  80   a  to  80   l  has the inter-fin through-hole  81  between heat dissipating fins adjacent in the axial direction. Accordingly, since oil between heat dissipating fins can flow out from between the heat dissipating fins through the inter-fin through-hole  81 , it is possible to prevent oil from remaining in one place, and it is possible to prevent deterioration of oil. 
     (2) In addition, the inter-fin through-hole  81  is disposed at the center between a pair of heat dissipating fins adjacent in the axial direction. Accordingly, oil adhered to either of the pair of heat dissipating fins also uniformly reaches the inter-fin through-hole  81 , and the oil can smoothly flow out through the inter-fin through-hole  81 . 
     (3) In addition, the inter-fin through-hole  81  is disposed on the outside in the radial direction. Accordingly, it is possible to increase the strength of the motor part  10  in the axial direction and a process for a tool forming an inter-fin through-hole in the production process becomes easier. 
     (4) In addition, a surface between a pair of heat dissipating fins adjacent in the axial direction within the surface of the fin support  79  is inclined toward the inter-fin through-hole  81 . Accordingly, oil on the surface of the fin support  79  easily reaches the inter-fin through-hole  81  and the oil can smoothly flow out through the inter-fin through-hole  81 . 
     (5) In addition, the inter-fin through-hole  81  has a circular cross-sectional shape in a direction orthogonal to a penetration direction of the inter-fin through-hole  81 . Accordingly, oil on the surface of the fin support  79  easily reaches the inter-fin through-hole  81  and the oil can smoothly flow out through the inter-fin through-hole  81 . 
     (6) In addition, the fin support  79  has a first surface and a second surface. The first surface of the fin support  79  is a surface between a pair of heat dissipating fins adjacent in the axial direction, and the second surface of the fin support  79  is a surface opposite to the first surface of the fin support  79 . The size of the inner diameter of the inter-fin through-hole  81  decreases from the first surface of the fin support  79  to the second surface of the fin support  79 . Accordingly, when a tool is inserted from the first surface of the fin support  79  to the second surface of the fin support  79  and the inter-fin through-hole  81  is formed, the tool is easily pulled out and the inter-fin through-hole  81  is easily formed. 
     (7) In addition, in the inter-fin through-hole  81 , the plurality of attachment parts  63  extend in a direction orthogonal to a contact surface that comes in contact with the attachment surface  102 . Thus, oil can easily flow out from between heat dissipating fins through the inter-fin through-hole  81  due to its own weight. 
     (8) In addition, the plurality of attachment parts  63  are provided at three corners on a surface parallel to the attachment surface  102  (a surface that extends in the X direction). A first attachment part among the plurality of attachment parts  63  is disposed on one side with respect to the stator  22  in the axial direction and on one side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A second attachment part among the plurality of attachment parts  63  is disposed on one side with respect to the stator  22  in the axial direction and on the other side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A third attachment part among the plurality of attachment parts  63  is disposed on the other side with respect to the stator  22  in the axial direction and on one side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . Thus, when the second attachment part and the third attachment part are diagonally disposed, attachment can be performed with the plurality of attachment parts  63  with high accuracy, it is possible to increase a degree of parallelization of the board cover  61  and the attachment surface  102  of the transmission  100 , it is possible to determine a direction in which the inter-fin through-hole  81  extends with high accuracy, and oil can easily flow out from between heat dissipating fins through the inter-fin through-hole  81  due to its own weight. 
     (9) In addition, the plurality of attachment parts  63  are provided at four corners on a surface parallel to the attachment surface  102  (a surface that extends in the X direction). A first attachment part among the plurality of attachment parts  63  is disposed on one side with respect to the stator  22  in the axial direction and on one side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A second attachment part among the plurality of attachment parts  63  is disposed on one side with respect to the stator  22  in the axial direction and on the other side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A third attachment part among the plurality of attachment parts  63  is disposed on the other side with respect to the stator  22  in the axial direction and on one side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . A fourth attachment part among the plurality of attachment parts  63  is disposed on the other side with respect to the stator  22  in the axial direction and on the other side with respect to the stator  22  in a direction parallel to the surface of the board  82   a . Thus, when the second attachment part and the third attachment part are diagonally disposed, and the first attachment part and the fourth attachment part are diagonally disposed, attachment can be performed with the plurality of attachment parts  63  with high accuracy, it is possible to increase a degree of parallelization of the board cover  61  and the attachment surface  102  of the transmission  100 , it is possible to determine a direction in which the inter-fin through-hole  81  extends with high accuracy, and oil can easily flow out from between heat dissipating fins through the inter-fin through-hole  81  due to its own weight. 
     (10) In addition, the plurality of attachment parts  63  have the arm  62  that extends toward the stator  22 . The arm  62  has the groove  65  that is open in a direction orthogonal to a contact surface of the attachment surface  102 . The groove through-hole  66  is provided at the bottom of the groove  65 . Accordingly, since oil of the groove  65  can flow out from the groove  65  through the groove through-hole  66 , it is possible to prevent oil from remaining in one place, and it is possible to prevent deterioration of oil. 
     While the exemplary embodiments of the disclosure have been described above, the disclosure is not limited to such embodiments and various modifications and alternations within the spirit and scope of the disclosure can be made. These embodiments and modifications thereof are included in the scope and spirit of the disclosure and also included in the scope described in the claims and equivalents thereof. 
     Features of the above-described exemplary embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While the exemplary embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined by the following claims.