Patent Publication Number: US-2019195347-A1

Title: Electric oil pump and method for making electric oil pump

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2017-245619 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 and a method of producing 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. 
     In the structure of the related art, a board and a control circuit part that control an operation of the motor part are disposed on the other side with respect to the motor part in the axial direction in many cases. The control circuit part includes electronic components such as an inverter circuit, a microcomputer, a coil, and a capacitor, and the electronic components may be mounted on both surfaces of the board. 
     In the electric oil pump, since the motor part and the pump part are linearly disposed in the axial direction, the length in the axial direction increases. In the electric oil pump device of the related art, the board is disposed to extend in a direction orthogonal to the axial direction, but the electronic components are mounted on the board and protrude to the other side in the axial direction. In addition, the board and the electronic components are covered with a cover. The cover is attached to the other side end of the motor part in the axial direction and disposed to protrude to the other side in the axial direction with respect to the board and the electronic component. Therefore, the electric oil pump device of the related art increases in length in the axial direction and increases in size. 
     On the other hand, for example, in electric oil pumps applied to vehicles, there is strong demand for downsizing for securing minimum ground clearance for the vehicles. Therefore, it is desirable to provide an electric oil pump which has a board on which electronic components are mounted and is reduced in size in the axial direction. 
     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; and 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. 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, a coil provided in the stator, and a motor housing having a cylindrical part 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 motor housing includes a bearing that supports the shaft that protrudes from the motor part to the other side in the axial direction, a tubular bearing housing that holds the bearing, and a bus bar assembly connected to a coil end of the coil that extends from the stator. The stator, the bus bar assembly, and the bearing housing are sequentially disposed from the pump part to the motor part. 
     In a production method in the above embodiment, there is provided a method of producing an electric oil pump including a motor part having a shaft disposed along a central axis that extends in an axial direction; and 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. 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, a coil provided in the stator, and a motor housing in which the rotor and the stator are accommodated. The motor housing includes a bearing that supports the shaft that protrudes from the motor part to the other side in the axial direction, a tubular bearing housing that holds the bearing, and a bus bar assembly connected to a coil end of the coil that extends from the stator. The method includes a stator press-fitting process in which the stator is press-fitted into the motor housing from the other side of the motor housing in the axial direction; a bus bar assembly insertion process in which the bus bar assembly is inserted into the motor housing from the other side of the motor housing in the axial direction and the bus bar assembly is disposed near the stator; a coil connection process in which a coil end of the coil is electrically connected to a connecting bus bar of the bus bar assembly; a bearing housing press-fitting process in which the bearing housing is press-fitted into the motor housing from the other side of the motor housing in the axial direction; and a bus bar assembly fixing process in which the bearing housing is fixed to the bus bar assembly through a fixing member. 
     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 cross-sectional view of an electric oil pump according to a first embodiment. 
         FIG. 2  is a plan view of the electric oil pump in which illustration of a board cover is omitted. 
         FIG. 3  is a cross-sectional view of the electric oil pump taken along the arrow II-II in 
         FIG. 2 . 
         FIG. 4  is a perspective view of a bearing housing. 
         FIG. 5  is a perspective view of an internal structure of the electric oil pump when viewed from the motor part side. 
         FIG. 6  is an internal structure view of a bus bar assembly in which an assembly main body is omitted. 
         FIG. 7  is a perspective view of the assembly main body of the bus bar assembly. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The disclosure is to provide an electric oil pump which has a board and is reduced in size in an axial direction and a method of producing an electric oil pump. 
     An electric oil pump and a method of producing an electric oil pump according to embodiments 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. 1  (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 direction orthogonal to the plane of the paper 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 cross-sectional view of an electric oil pump according to a first embodiment.  FIG. 2  is a plan view of the electric oil pump in which illustration of a board cover is omitted. As shown in  FIG. 1  and  FIG. 2 , an electric oil pump  1  of the present embodiment includes a motor part  10  and a pump part  40 . In addition, the electric oil pump  1  includes 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 on the +X side with respect to the motor part  10  and controls an operation of the motor part  10 . Constituent members will be described below in detail. 
     As shown in  FIG. 1 , the motor part  10  includes the shaft  11 , a rotor  20 , a stator  22 , a cylindrical part  13   d  of a motor housing  13 , and a coil  22   b.    
     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 disposed outside the rotor  20  in the radial direction. The rotor  20  is fixed to the other side (rear side) of the shaft  11  in the axial direction. 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  (refer to  FIG. 3 ), 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 surface  13   a   1  of the stator holding part  13   a . Thereby, the stator  22  is accommodated in the stator holding part  13   a.    
       FIG. 3  is a cross-sectional view of the electric oil pump  1  taken along the arrow II-II in  FIG. 2 . As shown in  FIG. 3 , the board support  13   b  extends radially outward from the stator holding part  13   a  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. 
       FIG. 4  is a perspective view of a bearing housing  25 . As shown in  FIG. 1 , the holding part  13   c  is provided at the rear side end of the cylindrical part  13   d  of the motor housing  13 . The bearing housing  25  is disposed at 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  25  has a tubular shape, and holds a bearing  16 . The bearing  16  supports the shaft  11  that protrudes from the motor part  10  to the other side (rear side) in the axial direction. In the present embodiment, as shown in  FIG. 4 , the bearing housing  25  includes a disk-shaped main body part  25   a , and a tubular bearing housing part  25   b  that protrudes from a front side surface (a front side end surface  25   a   1 ) of the main body part  25   a  to the front side. An annular raised part  25   a   2  that rises to the rear side is provided at the rear side end of the peripheral part of the main body part  25   a . An outer surface  25   a   3  outside the raised part  25   a   2  in the radial direction is fitted to a surface  13   c   1  of the bearing holding part  13   c . In the present embodiment, the outer surface  25   a   3  outside the raised part  25   a   2  in the radial direction is press-fitted to the inner surface  13   c   1  of the bearing holding part  13   c.    
     A flange part  25   c  that protrudes radially outward is provided in an annular shape at the rear side end of the raised part  25   a   2 . A front side surface of the flange part  25   c  comes in contact with a step  13   c   2  provided in the bearing holding part  13   c . As shown in  FIG. 1 , in the step  13   c   2 , the inner surface  13   c   1  on the rear side of the motor housing  13  bends and extends radially outward. Therefore, in the bearing housing  25 , while the front side surface of the flange part  25   c  is in contact with the step  13   c   2 , the outer surface  25   a   3  of the raised part  25   a   2  is press-fitted to the inner surface  13   c   1  of the bearing holding part  13   c  and fitted into the motor housing  13 . Therefore, the bearing housing  25  that is positioned to the front side is fixed to the motor housing  13 . 
     As shown in  FIG. 1  and  FIG. 4 , the bearing housing part  25   b  has a concave part  25   b   1  in which the front side is open and the rear side is recessed. The concave part  25   b   1  has a circular shape when viewed from the front side. The bearing  16  is accommodated in the concave part  25   b   1 . The concave part  25   b   1  is disposed coaxially with the central axis J of the shaft  11 . The bearing  16  provided in the concave part  25   b   1  supports the rear side end of the shaft  11 . A through-hole  25   d  that penetrates in the axial direction is provided at the central part of the bearing housing  25 . The through-hole  25   d  is smaller than the inner diameter of the concave part  25   b   1 . In the through-hole  25   d , the front side opens to the concave part  25   b   1  and the rear side opens to the rear side surface of the main body part  25   a . The inner diameter of the through-hole  25   d  is larger than the outer diameter of the shaft  11 . 
       FIG. 5  is a perspective view of an internal structure of the electric oil pump  1  when viewed from the side of the motor part  10 . As shown in  FIG. 4 , in the main body part  25   a  of the bearing housing  25 , a plurality of fixing through-holes  25   f  through which a fixing member  26  passes is provided outside the bearing housing part  25   b  in the radial direction. In the present embodiment, two fixing through-holes  25   f  are provided at symmetrical positions on both sides of the bearing housing part  25   b  in the radial direction (X axis direction) and penetrate in the axial direction. In addition, in the main body part  25   a , two positioning holes  25   e  through which a positioning pin  31  provided in a bus bar assembly  30  passes are provided to penetrate in the axial direction. In the present embodiment, the two positioning holes  25   e  are provided at positions close to the bearing housing part  25   b  on the −Y side of the bearing housing part  25   b.    
       FIG. 6  is an internal structure view of the bus bar assembly  30  in which an assembly main body  33  is omitted.  FIG. 7  is a perspective view of the assembly main body  33  of the bus bar assembly  30 . As shown in  FIG. 5  and  FIG. 6 , the bus bar assembly  30  is connected to a coil end  22   e  of the coil  22   b  that extends from the stator  22 . In addition, the bus bar assembly  30  is connected to a bus bar  73  connected to the board  82   a . Therefore, the coil end  22   e  is electrically connected to the board  82   a  through the bus bar assembly  30 . 
     The bus bar assembly  30  has a tubular shape, and includes a plurality of connecting bus bars  35  connected to the coil end  22   e  and the assembly main body  33  in which the connecting bus bar  35  is disposed. In the present embodiment, the connecting bus bar  35  is made of a metal, and the bus bar assembly  30  is an integrally molded article made of a resin. 
     The coil end  22   e  protrudes from an end on the other side (rear side) of the motor part  10  in the axial direction. When two coil ends  22   e  adjacent in the circumferential direction are set as one coil end group  22   f , three coil end groups  22   f  are disposed at uniform intervals in the circumferential direction. Therefore, the bus bar assembly  30  has three connecting bus bars  35  connected to the respective three coil end groups  22   f.    
     The connecting bus bar  35  includes a bus bar main body part  35   a  that is curved in the circumferential direction radially outward from the shaft  11 , a coil end side connection part  35   b  connected to one end of the bus bar main body part  35   a  and connected to the coil end  22   e , and a board side connection part  35   c  connected to the other end of the bus bar main body part  35   a  and connected to the bus bar  73  connected to the board  82   a.    
     As shown in  FIG. 7 , the assembly main body  33  has a tubular shape and has one side (front side) in the axial direction that is open and a bottom  33   a  on the rear side. The assembly main body  33  has the bottom  33   a  at the rear side end of a tubular part  33   b  that extends in a cylindrical shape. An insertion hole  33   c  into which the bearing housing part  25   b  of the bearing housing  25  is inserted is provided at the central part of the bottom  33   a . The bus bar assembly  30  is disposed on the inner surface  13   a   1  of the motor housing  13  in the axial direction in a freely movable manner. In the present embodiment, the outer diameter of the tubular part  33   b  is smaller than the inner diameter of the inner surface  13   a   1  of the motor housing  13 . 
     As shown in  FIG. 1 , a step  13   c   3  protruding radially inward is provided on the inner surface  13   a   1  of the motor housing  13 . One side end of the bus bar assembly  30  in the axial direction comes in contact with the step  13   c   3  and the bus bar assembly  30  is disposed in the motor housing  13 . In the present embodiment, as shown in  FIG. 1 , the step  13   c   3  is provided at a position at which the inner surface  13   a   1  of the motor housing  13  forming the stator holding part  13   a  is connected to the inner surface  13   c   1  of the motor housing  13  forming the bearing holding part  13   c . The inner diameter of the inner surface  13   a   1  of the stator holding part  13   a  is smaller than the inner diameter of the inner surface  13   c   1  of the bearing holding part  13   c . Therefore, the step  13   c   3  is provided at a position at which the inner surface  13   a   1  of the stator holding part  13   a  is connected to the inner surface  13   c   1  of the bearing holding part  13   c . The step  13   c   3  is positioned at a position slightly shifted to the front side from the rear side end of the stator  22 . 
     At the step  13   c   3 , the front side end of the tubular part  33   b  of the bus bar assembly  30  comes in contact with the step  13   c   3  and is disposed in the motor housing  13 . Therefore, positioning of the bus bar assembly  30  on the front side can be performed. In addition, in the tubular part  33   b , while the front side end is in contact with the step  13   c   3 , the outer surface of the tubular part  33   b  comes in contact with the inner surface of the cylindrical part  13   d  of the motor housing  13 , and is disposed in the motor housing  13  in contact with the outside of the stator  22 . Therefore, it is possible to position a bus bar assembly  13  in the radial direction with respect to the inside of the motor housing  13 . Here, during positioning of the bus bar assembly  13  in the radial direction, the tubular part  33   b  of the bus bar assembly  30  may come in contact with only one of the inner surface of the cylindrical part  13   d  of the motor housing  13  and the outer surface of the stator  22 . In addition, on the other side with respect to the step  13   c   3  in the axial direction, the stator  22 , the tubular part  33   b  of the bus bar assembly  30 , and the cylindrical part  13   d  of the motor housing  13  are sequentially disposed in contact from the inner side to the outer side in the radial direction. Therefore, it is possible to easily position the bus bar assembly  30  in the radial direction with respect to the motor housing  13 . 
     As shown in  FIG. 5  and  FIG. 7 , the bus bar assembly  30  has a plurality of exposure through-holes  33   d  which are provided at intervals in the circumferential direction of the peripheral part in the bus bar assembly  30  and to which the coil end side connection part  35   b  of the connecting bus bar  35  is exposed when viewed in the axial direction. In the present embodiment, the exposure through-holes  33   d  are provided at positions at uniform intervals in the circumferential direction of the peripheral part of the bottom  33   a  of the bus bar assembly  30 . The exposure through-hole  33   d  is an elongated hole that is curved and extends in the circumferential direction when viewed from the rear side. 
     The bus bar assembly  30  has a rear side end surface  33   e  that comes in contact with the front side end surface  25   a   1  on one side of the bearing housing  25  in the axial direction at the other side end in the axial direction. In the present embodiment, the rear side end surface  33   e  is a rear side surface of the bottom  33   a  of the assembly main body  33 . The rear side end surface  33   e  has a female screw  33   f  into which a shaft part of the fixing member  26  (bolt) inserted into the bearing housing  25  is screwed between the pair of exposure through-holes  33   d  adjacent in the circumferential direction of the bus bar assembly  30 . In the present embodiment, as shown in  FIG. 7 , two female screws  33   f  are provided with an interval therebetween in the circumferential direction on the rear side end surface  33   e  on both sides in the X axis direction of the insertion hole  33   c  provided at the central part of the assembly main body  33 . The female screw  33   f  has an insert. 
     Two positioning pins  31  that protrude to the other side in the axial direction in an area of the rear side end surface  33   e  different from an area in which the female screws  33   f  are provided and are disposed with an interval therebetween are provided on the rear side end surface  33   e  of the bus bar assembly  30 . In the present embodiment, the two positioning pins  31  are provided on the side of −Y axis direction with respect to the female screw  33   f.    
     The bus bar assembly  30  is fixed to the bearing housing  25  through the fixing member  26  (bolt). In the present embodiment, in the bus bar assembly  30 , while the front side end surface  25   a   1  of the bearing housing  25  comes in contact with the rear side end surface  33   e  of the bus bar assembly  30  and the positioning pin  31  is inserted into the positioning hole  25   e , the fixing member  26  (bolt) inserted into the fixing through-hole  25   f  of the bearing housing  25  is screwed into the female screw  33   f  of the bus bar assembly  30 , and thus the bus bar assembly  30  is fixed to the bearing housing  25 . In the present embodiment, the fixing member  26  is a bolt. 
     As shown in  FIG. 1 , 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 ( 0  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. 1 , 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  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 motor housing  13 . 
     Here, as shown in  FIG. 1 , a rotation angle sensor  72   b  configured to detect a rotation angle of the shaft  11  is disposed at a position inside the motor cover  72   c  which faces the rear side end of the shaft  11 . The rotation angle sensor  72   b  is mounted on a 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 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 , 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. 1 , the pump body  52  is positioned at the front side end of the motor housing  13 . 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  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. 1 , the pump rotor  47  is attached to the front side of the shaft  11 . 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. 1 , 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  (refer to  FIG. 2 ) connected to the intake port. The pump cover  57  has a discharge opening  42  (refer to  FIG. 2 ) 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. 2 , 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. 
     As shown in  FIG. 2  and  FIG. 3 , the case  50  has a board housing part  84  that extends from the motor housing  13  in a direction (+X direction) orthogonal to the axial direction and is recessed to the positive side in the Y axis direction. In addition, the board housing part  84  extends from one side end of the motor housing  13  in the axial direction to the other side end. 
     The board housing part  84  has a bottomed container shape and has a rectangular shape when viewed toward the positive side in the Y axis direction. The board  82   a  is accommodated in the board housing part  84 . Thereby, it is possible to reduce the size of the electric oil pump  1  in the direction (Y axis direction) orthogonal to the axial direction. 
     As shown in  FIG. 2 , the electric oil pump  1  is attached to an attachment surface provided on a bottom surface of a transmission (not shown). The electric oil pump  1  is accommodated in an oil pan provided below the transmission. The electric oil pump  1  sucks oil in the oil pan 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 of the transmission. In the present embodiment, the attachment part  63  is provided at the tip of an arm  50   a  that extends obliquely outward from corners on both sides in the axial direction of the negative side end of the board housing part  84  in the Y axis direction when viewed toward the positive side in the X axis direction. In addition, the attachment part  63  is provided at the tip of an arm  50   b  that extends obliquely outward from each of both sides in the axial direction of the outer surface of the motor housing  13  opposite to the side on which the board housing part  84  is positioned with respect to the motor housing  13 . 
     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 an attachment surface of the transmission using the bolt. The attachment part  63  has a contact surface that comes in contact with the attachment surface when the electric oil pump  1  is attached to the attachment surface. 
     As shown in  FIG. 3 , the case  50  has a fin part  80  that extends in the X axis direction on the outer surface on the positive side of the motor housing  13  in the Y axis direction opposite to the side on which the board housing part  84  is positioned with respect to the motor housing  13 . The fin part  80  dissipates heat generated from the electric oil pump  1 . In addition, as shown in the drawing, the board housing part  84  has a plurality of heat dissipating fins  86  that protrude in the Y axis direction on a bottom  84   a  of the board housing part  84  and extend in the X axis direction. The plurality of heat dissipating fins  86  are disposed at intervals in the axial direction. The heat dissipating fin  86  dissipates heat generated from the board  82   a  and the motor part  10 . 
     Next, a method of producing the electric oil pump  1  will be described with reference to  FIG. 1 . The method of producing the electric oil pump  1  includes a stator press-fitting process in which the stator  22  is press-fitted into the motor housing  13  from the other side of the motor housing  13  in the axial direction, a bus bar assembly insertion process in which the bus bar assembly  30  is inserted into the motor housing  13  from the other side of the motor housing  13  in the axial direction and the bus bar assembly  30  is disposed near the stator  22 , a coil connection process in which the coil end  22   e  of the coil  22   b  is electrically connected to the connecting bus bar  35  of the bus bar assembly  30 , a bearing housing press-fitting process in which the bearing housing  25  is press-fitted into the motor housing  13  from the other side of the motor housing  13  in the axial direction, and a bus bar assembly fixing process in which the bus bar assembly  30  is fixed to the bearing housing  25  through the fixing member  26 . 
     In the stator press-fitting process of the present embodiment, the stator  22  is press-fitted and fixed to the inner surface  13   a   1  of the motor housing  13  which is the stator holding part  13   a  of the motor housing  13 . In the bus bar assembly insertion process, the bus bar assembly  30  is inserted along the inner surface  13   a   1  of the motor housing  13  which is the bearing holding part  13   c  of the motor housing  13 , and the assembly main body  33  of the bus bar assembly  30  is brought into contact with the step  13   c   3 . In the coil connection process, the coil end  22   e  is connected to the coil end side connection part  35   b  of the connecting bus bar  35  by welding or fusing. In the bus bar assembly fixing process, the fixing member  26  (bolt) is inserted into the fixing through-hole  25   f  of the bearing housing  25  and screwed into the female screw  33   f  of the bus bar assembly  30 . 
     After the bus bar assembly fixing process, a rotation angle sensor assembly fixing process in which a rotation angle sensor assembly  72  to which the rotation angle sensor  72   b  capable of detecting a rotation angle of the shaft  11  is attached is fixed to the bearing housing  25  through the fixing member  26  is performed. In the present embodiment, the fixing member  26  is a bolt. As shown in  FIG. 1 , the rotation angle sensor assembly  72  includes the rotation angle sensor  72   b  and the circuit board  72   a  attached to the rotation angle sensor  72   b . The rotation angle sensor assembly fixing process includes a rotation angle sensor attaching process in which the rotation angle sensor  72   b  is attached to the circuit board  72   a . When the rotation angle sensor attaching process is performed, it is possible to obtain the rotation angle sensor assembly  72  in which the rotation angle sensor  72   b  is attached to the circuit board  72   a  through the fixing member  26  (bolt). 
     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, as shown in  FIG. 1 , in the electric oil pump  1  according to the present embodiment, from the pump part  40  to the motor part  10 , the stator  22 , the bus bar assembly  30 , and the bearing housing  25  are sequentially disposed. Therefore, a control part configured to control an operation of the motor part  10  is not provided on the other side with respect to the bearing housing  25  in the axial direction. Thus, compared to when a control part is disposed on the other side of the shaft  11  in the axial direction, the length of the electric oil pump  1  in the axial direction can be shortened and it is possible to reduce the size of the electric oil pump. 
     (2) In addition, the bearing housing  25  is disposed in the motor housing  13  and is fixed to the inner surface  13   c   1  of the motor housing  13 . Therefore, in the bearing housing  25 , a component for fixing into the motor housing  13  is not necessary. Thus, it is possible to reduce the cost of the electric oil pump  1 . 
     (3) In addition, the bus bar assembly  30  is disposed on the inner surface  13   a   1  of the motor housing  13  in the axial direction in a freely movable manner. Therefore, the bus bar assembly  30  can be easily inserted and disposed into a motor housing  13   c   1 . 
     (4) The tubular part  33   b  of the bus bar assembly  30  is disposed between the stator  22  and the cylindrical part  13   d  of the motor housing  13 , and the tubular part  33   b  comes in contact with at least one of the outer circumferential surface of the stator  22  and the inner circumferential surface of the cylindrical part  13   d . Therefore, it is possible to easily position the bus bar assembly  30  in the radial direction with respect to the motor housing  13 . 
     (5) In addition, one side end of the bus bar assembly  30  in the axial direction comes in contact with the step  13   c   3  and the bus bar assembly  30  is disposed in the motor housing  13 . Therefore, it is possible to easily perform positioning on one side of the bus bar assembly  30  in the axial direction. 
     (6) In addition, the bus bar assembly  30  has a plurality of exposure through-holes  33   d  which are provided at intervals in the circumferential direction of the peripheral part in the bus bar assembly  30  and to which the coil end side connection part  35   b  of the connecting bus bar  35  is exposed when viewed in the axial direction. Therefore, when the coil end  22   e  is connected to the coil end side connection part  35   b , it is possible to easily connect the coil end  22   e  to the coil end side connection part  35   b  through the exposure through-hole  33   d.    
     (7) In addition, the female screw  33   f  into which a shaft part of the fixing member  26  (bolt) inserted into the bearing housing  25  is screwed is provided on the rear side end surface  33   e  between the pair of exposure through-holes  33   d  adjacent in the circumferential direction of the bus bar assembly  30  within the rear side end surface  33   e  of the bus bar assembly  30 . Therefore, since the fixing member  26  (bolt) is fastened to the female screw  33   f  while the rear side end surface  33   e  of the bus bar assembly  30  is in contact with the front side end surface  25   a   1  of the bearing housing  25 , the bus bar assembly  30  can be firmly fixed to the bearing housing  25 . 
     (8) In addition, on the rear side end surface  33   e  of the bus bar assembly  30 , two positioning pins  31  that protrude to the other side in the axial direction on an area of the rear side end surface  33   e  different from an area in which the female screw  33   f  is provided are disposed at an interval therebetween are provided. In addition, the bearing housing  25  has the positioning hole  25   e  into which two positioning pins  31  are inserted on the front side end surface  25   a   1 . Therefore, when the two positioning pins  31  are inserted into the positioning hole  25   e , it is possible to perform positioning in the circumferential direction and the radial direction of the bus bar assembly  30 . 
     (9) In addition, the bus bar assembly  30  is an integrally molded article made of a resin. Therefore, it is possible to increase the position accuracy of a component (for example, the connecting bus bar  35 ) disposed in the bus bar assembly  30 . 
     (10) In addition, the bearing housing  25  is press-fitted and fixed to the inner surface  13   c   1  of the motor housing  13 . Therefore, the bearing housing  25  can be firmly fixed to the motor housing  13 . 
     (11) In addition, the bus bar assembly  30  is fixed to the bearing housing  25  through the fixing member  26 . Therefore, the bus bar assembly  30  can be fixed to the bearing housing  25 . 
     (12) In addition, the fixing member  26  is a bolt. Therefore, the bus bar assembly  30  can be firmly fixed to the bearing housing  25 . 
     (13) In addition, a stator press-fitting process, a bus bar assembly insertion process, a coil connection process, a bearing holding part press-fitting process, and a bus bar assembly fixing process are included. Therefore, it is possible to provide a method of producing the electric oil pump  1  through which the bus bar assembly  30  can be firmly fixed to the bearing housing  25  through the fixing member  26  according to these processes. 
     (14) In addition, after the bus bar assembly fixing process, the rotation angle sensor assembly fixing process is performed. Therefore, it is possible to provide a method of producing the electric oil pump  1  through which it is possible to provide the rotation angle sensor assembly  72  to the electric oil pump  1 . 
     (15) In addition, the rotation angle sensor assembly fixing process includes a rotation angle sensor attaching process in which the rotation angle sensor  72   b  is attached to the circuit board  72   a  through the fixing member  26 . Therefore, when the rotation angle sensor attaching process is performed, it is possible to obtain the rotation angle sensor assembly  72  in which the rotation angle sensor  72   b  is attached to the circuit board  72   a  through the fixing member  26 . 
     (16) In addition, since the fixing member  26  is a bolt, the bus bar assembly  30  can be firmly fixed to the bearing housing  25  in the bus bar assembly fixing process. In addition, in the rotation angle sensor attaching process, the rotation angle sensor  72   b  can be firmly fixed to the circuit board  72   a.    
     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 present 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 present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.