Patent Publication Number: US-2022235765-A1

Title: Electric pump

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2021-009801 filed on Jan. 25, 2021, the entire content of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an electric pump. 
     BACKGROUND 
     An electric pump attached to a predetermined object is known. For example, an electric oil pump mounted on an automatic transmission of an automobile is conventionally known. 
     The electric pump as described above may include a circuit board in which an electrolytic capacitor is attached. In this case, when the predetermined object to which the electric pump is attached is an object in which vibration occurs, such as an automatic transmission of an automobile, there is a possibility that a malfunction such as damage occurs in the electrolytic capacitor in the electric pump due to vibration transmitted from the predetermined object. 
     SUMMARY 
     An aspect of an electric pump of the present invention is an electric pump attached to a predetermined object. The electric pump includes a motor having a rotor rotatable about a center axis extending in an axial direction, a pump mechanism coupled to the rotor, a circuit board located radially outside the motor and having a plate face directed in a radial direction, an electrolytic capacitor attached to the plate face of the circuit board, and a housing that houses the motor, the pump mechanism, the circuit board, and the electrolytic capacitor therein. The housing has a mounting face attached to the predetermined object. The mounting face is a face directed radially outward. The plate face of the circuit board is disposed along a direction intersecting the mounting face. The electrolytic capacitor is disposed at a position closer to the mounting face than the center axis in the direction orthogonal to the mounting face. 
     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 preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view illustrating part of the electric pump of an embodiment; 
         FIG. 2  is a partially sectional perspective view illustrating part of the electric pump of an embodiment; 
         FIG. 3  is a perspective view illustrating a circuit board of an embodiment; and 
         FIG. 4  is a view of the circuit board of an embodiment when viewed from upper side. 
     
    
    
     DETAILED DESCRIPTION 
     An electric pump  100  of the present embodiment illustrated in  FIGS. 1 and 2  is an electric pump attached to a device M mounted on a vehicle. That is, the device M corresponds to a predetermined object to which the electric pump  100  is attached. The device M is not particularly limited, and may be an automatic transmission or a drive device that drives an axle of a vehicle. The electric pump  100  is, for example, an electric oil pump that supplies oil to the device M. 
     In the present embodiment, the electric pump  100  is attached to the device M in a direction orthogonal to the vertical direction. A direction in which the electric pump  100  is attached to the device M is orthogonal to a direction in which a center axis J of a motor  20  described later of the electric pump  100  extends. The center axis J illustrated in  FIGS. 1, 2, and 4  is an imaginary line extending in a direction orthogonal to the vertical direction. 
     In each diagram, the vertical direction is a direction parallel to the Z-axis. In the vertical direction, a side (+Z side) in which the arrow of the Z-axis is directed is an upper side. In the vertical direction, a side (−Z side) opposite to a side where the arrow of the Z-axis is directed is a lower side. In each drawing, the direction in which the electric pump  100  is attached to the device M is a direction parallel to the Y-axis orthogonal to the Z-axis. In the following description, a direction parallel to the Y-axis is referred to as a “mounting direction”. In the mounting direction, a side (+Y side) in which the arrow of the Y-axis is directed is referred to as “the one side in the mounting direction”. In the mounting direction, a side (−Y side) opposite to the side in which the arrow of the Y-axis is directed is referred to as “the other side in the mounting direction”. 
     In each drawing, the direction in which the center axis J extends is a direction parallel to the X-axis orthogonal to both the Z-axis and the Y-axis. In the following description, a direction in which the center axis J extends, that is, a direction parallel to the X-axis is referred to as an “axial direction”. A radial direction centered on the center axis J is simply referred to as a “radial direction”. A circumferential direction centered on the center axis J is simply referred to as a “circumferential direction”. In the axial direction, a side (+X side) in which the arrow of the X-axis is directed is referred to as a “front side”. In the axial direction, a side (−X side) opposite to a side in which the arrow of the X-axis is directed is referred to as a “rear side”. 
     As illustrated in  FIG. 1 , the electric pump  100  includes a housing  10 , a motor  20 , a pump mechanism  30 , a circuit board  40 , and a bus bar assembly  50 . The housing  10  accommodates the motor  20 , the pump mechanism  30 , the circuit board  40 , and the bus bar assembly  50  therein. 
     The housing  10  includes a housing body  11 , a motor cover  12 , pump cover  13 , and a board cover  14 . The housing body  11 , the motor cover  12 , the pump cover  13 , and the board cover  14  are separate members. The motor cover  12  is attached to the rear side (−X side) of the housing body  11 . The pump cover  13  is attached to the front side (+X side) of the housing body  11 . The board cover  14  is attached to the lower side of the housing body  11 . 
     As illustrated in  FIG. 2 , the housing body  11  includes a motor housing  15 , a pump housing  16 , a board housing  17 , and a mounting portion  18 . In the present embodiment, the motor housing  15 , the pump housing  16 , the board housing  17 , and the mounting portion  18  are portions of the same single member. 
     In the present embodiment, the motor housing  15  has a cylindrical shape extending in the axial direction. As illustrated in  FIG. 1 , the motor housing  15  has a first housing recess  11   a  including a recess opened to the rear side (−X side). The opening at the rear side of the first housing recess  11   a  is closed by the motor cover  12 . 
     The pump housing  16  is connected to the front side (+X side) of the motor housing  15 . The pump housing  16  has a second housing recess  11   b  including a recess opened to the front side. The opening at the front side of the second housing recess  11   b  is closed by the pump cover  13 . 
     The board housing  17  is located below the motor housing  15  and the pump housing  16 . The board housing  17  extends in the axial direction. An end of the board housing  17  at the front side (+X side) protrudes to the front side relative to the pump housing  16  and the pump cover  13 . The board housing  17  has a third housing recess  11   c  including a recess opening downward. The lower opening of the third housing recess  11   c  is closed by the board cover  14 . For example, at least some of the electronic components attached to an upper plate face  40   a  described later of the circuit board  40  is accommodated in the third housing recess  11   c.    
     As illustrated in  FIG. 2 , the mounting portion  18  is located at the one side in the mounting direction (+Y side) of the motor housing  15  and the pump housing  16 . The mounting portion  18  extends in the axial direction. The mounting portion  18  protrudes to the rear side (−X side) relative to the motor housing  15  and the motor cover  12 . The mounting portion  18  protrudes to the front side (+X side) relative to the pump housing  16  and the pump cover  13 . 
     The mounting portion  18  has through holes  18   a,    18   b,  and  18   c  penetrating the mounting portion  18  in the mounting direction. The through hole  18   a  is provided in a portion, of the mounting portion  18 , protruding to the rear side (−X side) relative to the motor housing  15  and the motor cover  12 . The through hole  18   b  and the through hole  18   c  are each provided at a portion, of the mounting portion  18 , protruding to the front side (+X side) relative to the pump housing  16  and the pump cover  13 . The through hole  18   b  and the through hole  18   c  are disposed side by side at intervals in the vertical direction. A bolt B to be tightened into a screw hole (not illustrated) provided in the device M passes through each of the through holes  18   a,    18   b,  and  18   c  from the other side in the mounting direction (−Y side). In the present embodiment, the mounting portion  18  is attached to the device M by three bolts B. With this configuration, the electric pump  100  is attached to the device M. The electric pump  100  is attached to the device M in a cantilever manner. 
     The face, of the mounting portion  18 , on the one side in the mounting direction (+Y side) is a mounting face  19  attached to the device M. That is, the housing  10  has the mounting face  19  attached to the device M as a predetermined object. The mounting face  19  is a face, of the housing  10 , on the one side in the mounting direction. The mounting face  19  is a face directed radially outward. The mounting face  19  is orthogonal to the mounting direction. In the present embodiment, the mounting face  19  is parallel to both the vertical direction and the axial direction. As shown in  FIGS. 3 and 4 , in the present embodiment, the mounting face  19  extends in the axial direction. As illustrated in  FIG. 4 , the mounting face  19  is in contact with the device M. More specifically, the mounting face  19  is in contact with a mounted face Ma of the device M. The mounted face Ma is a face directed in the other side in the mounting direction (−Y side). The mounted face Ma is provided with a screw hole (not illustrated) into which the bolt B is fastened. 
     As illustrated in  FIG. 1 , the housing body  11  has a first through hole  11   d  axially connecting the inside of the first housing recess  11   a  and the inside of the second housing recess lib. An oil seal  24  that seals between an inner peripheral face of the first through hole  11   d  and an outer peripheral face of a shaft  21  described later is held in the first through hole  11   d.  The housing body  11  has a second through hole  11   e  axially connecting the inside of the first housing recess  11   a  and the inside of the third housing recess  11   c.    
     The board cover  14  is a box-shaped member that opens upward. The board cover  14  extends in the axial direction. The board cover  14  includes a board cover main body portion  14   a  attached to the lower side of the housing body  11  and a connector portion  14   b  protruding from the board cover main body portion  14   a  to the front side (+X side). 
     The motor  20  is housed in the first housing recess  11   a.  The motor  20  includes a rotor  22  having the shaft  21 , a stator  23 , a first bearing  27 , and a second bearing  28 . The rotor  22  is capable of rotating about a center axis J extending in the axial direction. The shaft  21  has a columnar shape centered on the center axis J and extending in the axial direction. The shaft  21  is rotatably supported about the center axis J by the first bearing  27  and the second bearing  28 . In the present embodiment, each of the first bearing  27  and the second bearing  28  is a rolling bearing. The first bearing  27  is held by the motor cover  12 . The second bearing  28  is held in the first through hole  11   d.  An end, of the shaft  21 , on the front side (+X side) protrudes into the second housing recess  11   b  via the first through hole  11   d  and is coupled to the pump mechanism  30 . The stator  23  is located radially outside the rotor  22 . The stator  23  is fixed to the inner peripheral face of the first housing recess  11   a.  The stator  23  includes a coil  23   c.    
     The pump mechanism  30  is housed in the second housing recess  11   b.  The pump mechanism  30  has an inner rotor  31  and an outer rotor  32 . The inner rotor  31  is coupled to a portion, of the shaft  21 , protruding into the second housing recess  11   b.  With this configuration, the pump mechanism  30  is coupled to the rotor  22 . The outer rotor  32  has an annular shape surrounding the inner rotor  31 . The inner rotor  31  and the outer rotor  32  mesh with each other. Rotation of the inner rotor  31  by the shaft  21  also rotates the outer rotor  32 . 
     The bus bar assembly  50  is located at the rear side (−X side) of the stator  23  in the first housing recess  11   a.  The bus bar assembly  50  includes a first bus bar  51   a,  a second bus bar  51   b,  and a bus bar holder  52 . The bus bar holder  52  is located at the rear side of the stator  23 . The first bus bar  51   a  is held by the bus bar holder  52 . The first bus bar  51   a  is electrically connected to the coil  23   c  of the stator  23 . The second bus bar  51   b  is electrically connected to the first bus bar  51   a.  The second bus bar  51   b  extends downward from the first bus bar  51   a.  The second bus bar  51   b  extends to the circuit board  40  through the second through hole  11   e.  The second bus bar  51   b  is electrically connected to the circuit board  40 . Accordingly, the stator  23  is electrically connected to the circuit board  40  via the first bus bar  51   a  and the second bus bar  51   b.    
     The circuit board  40  is located radially outside the motor  20 . In the present embodiment, the circuit board  40  is located below the motor  20 . The circuit board  40  is located between the board housing  17  and the board cover  14  in the vertical direction. The circuit board  40  has a plate shape whose plate face is directed in the radial direction. The plate face of the circuit board  40  includes an upper plate face  40   a  facing upward and a lower plate face  40   b  facing downward. As illustrated in  FIG. 3 , the upper plate face  40   a  and the lower plate face  40   b  are disposed along a direction intersecting the mounting face  19 . In the present embodiment, the upper plate face  40   a  and the lower plate face  40   b  are disposed along a mounting direction orthogonal to the mounting face  19 . More specifically, the upper plate face  40   a  and the lower plate face  40   b  extend in the mounting direction and the axial direction. The upper plate face  40   a  and the lower plate face  40   b  are orthogonal to the vertical direction. Although not illustrated, wiring patterns are provided on the upper plate face  40   a  and the lower plate face  40   b.    
     As illustrated in  FIGS. 3 and 4 , the circuit board  40  has a rectangular plate shape extending in the axial direction. In the present embodiment, the circuit board  40  has a rounded rectangular shape having a long side along the axial direction and a short side along the mounting direction when viewed in the vertical direction. As illustrated in  FIG. 4 , in the present embodiment, the center position of the circuit board  40  in the mounting direction is the same as the position of the center axis J in the mounting direction. In other words, when viewed in the vertical direction, the center axis J overlaps the center of the circuit board  40  in the mounting direction. 
     The circuit board  40  has a plurality of fixing portions  47  fixed to the housing  10 . Each fixing portion  47  is provided at an outer peripheral edge portion of the circuit board  40 . In the present embodiment, six fixing portions  47  are provided. The six fixing portions  47  include fixing portions  47   c  and  47   d  provided at two corner portions of the rectangular plate-like circuit board  40  on the one side in the mounting direction (+Y side), fixing portions  47   e  and  47   f  provided at two corner portions of the circuit board  40  on the other side in the mounting direction (−Y side), a fixing portion  47   g  provided at a central portion between the fixing portion  47   c  and the fixing portion  47   d  in the axial direction, and a fixing portion  47   h  provided at a central portion between the fixing portion  47   e  and the fixing portion  47   f  in the axial direction. The fixing portion  47   c  is located at the front side (+X side) relative to the fixing portion  47   d.  The fixing portion  47   e  is located at the front side relative to the fixing portion  47   f.  In the present embodiment, the fixing portion  47   g  is disposed slightly shifted to the front side relative to the fixing portion  47   h.  The fixing portion  47   g  is disposed slightly shifted to the front side relative to the axial center of the circuit board  40 . The fixing portion  47   h  is disposed at the axial center of the circuit board  40 . 
     Each fixing portion  47  has a through hole  47   a  penetrating the circuit board  40  in the vertical direction, and a peripheral edge portion  47   b  surrounding the through hole  47   a.  In the present embodiment, the through hole  47   a  is a circular hole. As illustrated in  FIG. 3 , a bolt  46  passes through the through hole  47   a  from below. The bolt  46  passes through the through hole  47   a  from below and is tightened into a screw hole  17   b  provided in the housing  10 . Thus, the fixing portion  47  is fixed to the housing  10  by the bolt  46 . In the present embodiment, the screw hole  17   b  is provided at the lower end of a boss portion  17   a  provided in the board housing  17 . The boss portion  17   a  has a cylindrical shape protruding downward. The screw hole  17   b  is recessed upward from the lower face of the boss portion  17   a.  Six boss portions  17   a  are provided. 
     The peripheral edge portion  47   b  has an annular shape. The head of the bolt  46  is in contact with the lower face of the peripheral edge portion  47   b.  The lower face of the boss portion  17   a  is in contact with the upper face of the peripheral edge portion  47   b.  For example, no wiring pattern is provided on the upper face and the lower face of the peripheral edge portion  47   b.    
     The electric pump  100  includes an electrolytic capacitor  41 , a choke coil  42 , an inductor  43 , a diode  44 , and a shunt resistor  45 . The electrolytic capacitor  41 , the choke coil  42 , the inductor  43 , the diode  44 , and the shunt resistor  45  are electronic components attached to the plate face of the circuit board  40 . The electrolytic capacitor  41 , the choke coil  42 , the inductor  43 , and the diode  44  are attached to the upper plate face  40   a  of the plate face of the circuit board  40 . The shunt resistor  45  is attached to the lower plate face  40   b  of the plate face of the circuit board  40 . The electrolytic capacitor  41 , the choke coil  42 , the inductor  43 , the diode  44 , and the shunt resistor  45  together with the circuit board  40  are housed inside the housing  10 . 
     Electrolytic capacitor  41  has a columnar shape protruding upward from upper plate face  40   a.  The type of the electrolytic capacitor  41  is not particularly limited. As shown in  FIG. 4 , the electrolytic capacitor  41  is disposed at a position closer to the mounting face  19  than the center axis J in the mounting direction (Y-axis direction) orthogonal to the mounting face  19 . In the present embodiment, electrolytic capacitor  41  is disposed at a position closer to the mounting face  19  than the center of gravity G of electric pump  100  in the mounting direction orthogonal to the mounting face  19 . In other words, the electrolytic capacitor  41  is disposed at a position closer to the mounting face  19  than the imaginary line IL passing through the center of gravity G and extending in the axial direction when viewed in the vertical direction. In the present embodiment, the center of gravity G and the imaginary line IL are located toward the one side in the mounting direction (+Y side) relative to the center axis J. That is, in the present embodiment, the center of gravity G and the imaginary line IL are disposed at a position closer to the mounting face  19  than the center axis J in the mounting direction. The axial position of the center of gravity G is, for example, the same as the position of the axially central portion of the circuit board  40  in the axial direction. 
     In the present specification, “A certain object is disposed at a position closer to the mounting face than another object in the mounting direction orthogonal to the mounting face” means that the center position of the certain object in the mounting direction may be closer to the position of the mounting face in the mounting direction than the center position of the another object in the mounting direction. That is, “the electrolytic capacitor  41  is disposed closer to the mounting face  19  than the center axis J in the mounting direction” means that the center position of the electrolytic capacitor  41  in the mounting direction may be closer to the position of the mounting face  19  in the mounting direction than the position of the center axis J in the mounting direction. In addition, “the electrolytic capacitor  41  is disposed at a position closer to the mounting face  19  than the center of gravity G in the mounting direction” means that the center position of the electrolytic capacitor  41  in the mounting direction may be closer to the position of the mounting face  19  in the mounting direction than the position of center of the gravity G in the mounting direction. In the present embodiment, the entire electrolytic capacitor  41  is located toward the one side in the mounting direction (+Y side) relative to the center axis J, the center of gravity G, and the imaginary line IL. 
     In the present embodiment, a plurality of electrolytic capacitors  41  is provided. Three electrolytic capacitors  41 , namely, an electrolytic capacitor  41 A, an electrolytic capacitor  41 B, and an electrolytic capacitor  41 C are provided. The electrolytic capacitor  41 A, the electrolytic capacitor  41 B, and the electrolytic capacitor  41 C are located at a central portion of the upper plate face  40   a  of the circuit board  40  in the axial direction in a portion at the one side in the mounting direction (+Y side). The electrolytic capacitor  41 A, the electrolytic capacitor  41 B, and the electrolytic capacitor  41 C are disposed side by side along the axial direction. The electrolytic capacitor  41 B is located at the front side (+X side) relative to the electrolytic capacitor  41 A. Electrolytic capacitor  41 C is located between the electrolytic capacitor  41 A and the electrolytic capacitor  41 B in the axial direction. 
     In the present specification, “a plurality of certain objects is disposed side by side along the axial direction” means that the plurality of certain objects may overlap each other at least partially when the plurality of certain objects is viewed in the axial direction. In the present embodiment, the electrolytic capacitor  41 C is disposed shifted toward the other side in the mounting direction (−Y side) relative to the electrolytic capacitor  41 A and the electrolytic capacitor  41 B. A portion of the electrolytic capacitor  41 C on the one side in the mounting direction (+Y side) overlaps a portion of the electrolytic capacitor  41 A on the other side in the mounting direction and a portion of the electrolytic capacitor  41 B on the other side in the mounting direction when viewed in the axial direction. Electrolytic capacitor  41 A and electrolytic capacitor  41 B are disposed at the same position in the mounting direction. The entire electrolytic capacitor  41 A and the entire electrolytic capacitor  41 B overlap each other, for example, when viewed in the axial direction. 
     In the present embodiment, the plurality of electrolytic capacitors  41 A,  41 B,  41 C is disposed around one fixing portion  47   g  of the plurality of fixing portions  47  when viewed in the vertical direction orthogonal to the plate face of the circuit board  40 . The fixing portion  47   g  is a fixing portion  47  located at the central portion of the circuit board  40  in the axial direction at the edge portion on the one side in the mounting direction (+Y side). When viewed in the vertical direction, the centers of the plurality of electrolytic capacitors  41 A,  41 B,  41 C are disposed at the same distance from the center of the fixing portion  47   g.  That is, in the present embodiment, the three electrolytic capacitors  41 A,  41 B, and  41 C are disposed along an imaginary arc C centered on the fixing portion  47   g  when viewed in the vertical direction orthogonal to the plate face of the circuit board  40 . When viewed in the vertical direction, the center of the imaginary arc C overlaps the center of the through hole  47   a  of the fixing portion  47   g.  When viewed in the vertical direction, the centers of the plurality of electrolytic capacitors  41 A,  41 B,  41 C are located on the imaginary arc C. 
     The electrolytic capacitor  41 A and the electrolytic capacitor  41 B are disposed with the fixing portion  47   g  interposed therebetween in the axial direction when viewed in the vertical direction orthogonal to the plate face of the circuit board  40 . More specifically, a portion of the electrolytic capacitor  41 A on the one side in the mounting direction (+Y side) and a portion of the electrolytic capacitor  41 B on the one side in the mounting direction are disposed with a portion of the fixing portion  47   g  on the other side in the mounting direction (−Y side) interposed therebetween in the axial direction when viewed in the vertical direction. Electrolytic capacitor  41 C is located toward the other side in the mounting direction relative to the fixing portion  47   g.    
     A portion of the electrolytic capacitor  41 A on the one side in the mounting direction (+Y side) is located between a portion of the fixing portion  47   d  on the other side in the mounting direction (−Y side) and a portion of the fixing portion  47   g  on the other side in the mounting direction in the axial direction and between a portion of the fixing portion  47   c  on the other side in the mounting direction and a portion of the fixing portion  47   d  on the other side in the mounting direction in the axial direction when viewed in the vertical direction. That is, in the present embodiment, each of the fixing portions  47   d,    47   g  and the fixing portions  47   c,    47   d  corresponds to a pair of fixing portions  47  disposed with at least part of the electrolytic capacitor  41 A interposed therebetween when viewed in the vertical direction orthogonal to the plate face of circuit board  40 . 
     A portion of the electrolytic capacitor  41 B on the one side in the mounting direction (+Y side) is located between a portion of the fixing portion  47   c  on the other side in the mounting direction (−Y side) and a portion of the fixing portion  47   g  on the other side in the mounting direction in the axial direction and between a portion of the fixing portion  47   c  on the other side in the mounting direction and a portion of the fixing portion  47   d  on the other side in the mounting direction in the axial direction when viewed in the vertical direction. That is, in the present embodiment, each of the fixing portions  47   c,    47   g  and the fixing portions  47   c,    47   d  corresponds to a pair of fixing portions  47  disposed with at least part of the electrolytic capacitor  41 B interposed therebetween when viewed in the vertical direction orthogonal to the plate face of circuit board  40 . 
     The electrolytic capacitor  41 C is located between the fixing portion  47   g  and the fixing portion  47   h  in the mounting direction when viewed in the vertical direction. That is, in the present embodiment, the fixing portions  47   g  and  47   h  correspond to a pair of fixing portions  47  disposed with at least part of the electrolytic capacitor  41 C interposed therebetween when viewed in the vertical direction orthogonal to the plate face of the circuit board  40 . 
     The choke coil  42  is an electronic component having a mass larger than that of the electrolytic capacitor  41 . The choke coil  42  is an inductor. In the present embodiment, the mass of the choke coil  42  is the largest among the masses of the electronic components attached to the circuit board  40 . The choke coil  42  is disposed at a position closer to the mounting face  19  than the center axis J in the mounting direction orthogonal to the mounting face  19 . In the present embodiment, the choke coil  42  is disposed at a position closer to the mounting face  19  than the center of gravity G in the mounting direction. The entire choke coil  42  is located toward the one side in the mounting direction (+Y side) relative to the center axis J and the center of gravity G. In the present embodiment, choke coil  42  is disposed side by side with the plurality of electrolytic capacitors  41 A,  41 B,  41 C along the axial direction. The choke coil  42  is located toward the front side (+X side) relative to the electrolytic capacitor  41 B. 
     The choke coil  42  is disposed shifted to the other side in the mounting direction (−Y side) relative to the electrolytic capacitors  41 A and  41 B. A portion of the choke coil  42  on the one side in the mounting direction (+Y side) and a portion of the electrolytic capacitor  41 C on one side in the mounting direction are disposed with a portion of the electrolytic capacitor  41 B on the other side in the mounting direction interposed therebetween in the axial direction when viewed in the vertical direction. In the present embodiment, the electrolytic capacitor  41 A, the electrolytic capacitor  41 C, the electrolytic capacitor  41 B, and the choke coil  42  are disposed in zigzag in this order from the rear side (−X side) toward the front side (+X side) when viewed in the vertical direction. 
     In the present embodiment, the inductor  43  is an inductor used for boosting a power supply supplied from the outside to the electric pump  100 . The inductor  43  is located toward the other side in the mounting direction (−Y side) relative to the electrolytic capacitor  41 B. The inductor  43  is disposed at a position closer to the mounting face  19  than the center axis J in the mounting direction orthogonal to the mounting face  19 . The inductor  43  is disposed at a position overlapping the imaginary line IL when viewed in the vertical direction. 
     In the present embodiment, the diode  44  is a bidirectional transient voltage suppressor (TVS) diode used for a protection circuit that protects electronic components and the like on the circuit board  40  from a surge voltage. The diode  44  is located toward the other side in the mounting direction (−Y side) relative to the choke coil  42 . The diode  44  is located toward the front side (+X side) relative to the inductor  43 . The diode  44  is disposed at a position closer to the mounting face  19  than the center axis J in the mounting direction orthogonal to the mounting face  19 . The diode  44  is located between the center axis J and the imaginary line IL when viewed in the vertical direction. 
     In the present embodiment, the shunt resistor  45  is attached to the lower plate face  40   b  so as to overlap the electrolytic capacitor  41 A when viewed in the vertical direction. The circuit board  40  is interposed between the shunt resistor  45  and the electrolytic capacitor  41 A in the vertical direction. The shunt resistor  45  is disposed at a position closer to the mounting face  19  than the center axis J in the mounting direction orthogonal to the mounting face  19 . In the present embodiment, the shunt resistor  45  is disposed at a position closer to the mounting face  19  than the center of gravity G in the mounting direction. The entire shunt resistor  45  is located toward the one side in the mounting direction (+Y side) relative to the center axis J and the center of gravity G. 
     The electric pump  100  may vibrate in a direction orthogonal to the mounting direction with the mounting face  19  as a fulcrum due to vibration transmitted from the device M. In this case, when the plate face of the circuit board  40  is disposed along the direction intersecting the mounting face  19 , the vibration generated in the circuit board  40  by the vibration of the device M tends to be larger in a portion, of the circuit board  40 , farther from the mounting face  19  in the mounting direction, that is, a portion located at the other side in the mounting direction (−Y side). Therefore, when the circuit board  40  vibrates in the plate thickness direction due to the vibration from the device M, the amplitude of the vibration generated in the circuit board  40  tends to be larger at a portion farther from the mounting face  19  in the mounting direction. On the other hand, the amplitude of the vibration generated in the circuit board  40  tends to be small in a portion closer to the mounting direction with respect to the mounting face  19 . 
     According to the present embodiment, the electrolytic capacitor  41  is disposed at a position closer to the mounting face  19  than center axis J in the direction orthogonal to the mounting face  19 . Therefore, the electrolytic capacitor  41  can be disposed at a portion, of the circuit board  40 , relatively close to the mounting face  19 . That is, the electrolytic capacitor  41  can be disposed at a portion where the amplitude of the vibration generated in circuit board  40  is relatively small. Consequently, it is easy to reduce the vibration applied to the electrolytic capacitor  41 . Therefore, it is possible to suppress occurrence of a defect such as damage to the electrolytic capacitor  41 . The electrolytic capacitor  41  is an electronic component that is relatively more likely to be damaged by vibration than other electronic components. Therefore, as described above, it is possible to further suppress the occurrence of a defect in the electrolytic capacitor  41 , so that the reliability of the electric pump  100  can be improved. 
     According to the present embodiment, the electrolytic capacitor  41  is disposed at a position closer to the mounting face  19  than the center of gravity G of the electric pump  100  in the direction orthogonal to the mounting face  19 . The amplitude of the vibration generated in the circuit board  40  tends to be particularly large at a position farther from the mounting face  19  than the center of gravity G. Therefore, by disposing the electrolytic capacitor  41  at a position closer to the mounting face  19  than the center of gravity G, the electrolytic capacitor  41  can be disposed at a portion where the amplitude of the vibration generated in circuit board  40  is smaller. Consequently, the vibration applied to electrolytic capacitor  41  can be easily reduced. Thus, it is possible to further suppress the occurrence of a defect in the electrolytic capacitor  41 . 
     According to the present embodiment, the mounting face  19  extends in the axial direction. Therefore, the axial dimension of the mounting face  19  is larger than the vertical dimension of the mounting face  19 . In this case, the electric pump  100  is less likely to vibrate around an axis extending in the vertical direction orthogonal to both the axial direction and the mounting direction. On the other hand, the electric pump  100  is likely to vibrate around an axis extending in an axial direction orthogonal to both the vertical direction and the mounting direction. Here, in the present embodiment, the plate face of the circuit board  40  is directed in the radial direction. Therefore, the plate face of the circuit board  40  is along the axial direction. The circuit board  40  is disposed along a direction intersecting the mounting face  19 . As a result, the plate thickness direction of the circuit board  40  tends to be the vertical direction orthogonal to both the axial direction and the mounting direction or a direction close to the vertical direction. In this case, as described above, when the electric pump  100  is likely to vibrate around an axis extending in an axial direction orthogonal to both the vertical direction and the mounting direction, the circuit board  40  is likely to vibrate in the plate thickness direction, and the amplitude of the vibration generated in the circuit board  40  is likely to be large. As described above, the electric pump  100  of the present embodiment has a structure in which the amplitude of the vibration generated in the circuit board  40  tends to be large. 
     According to the present embodiment, as described above, even when the vibration is transmitted from the device M to the electric pump  100 , the vibration applied to the electrolytic capacitor  41  is easily reduced, and it is possible to suppress the occurrence of a defect in the electrolytic capacitor  41 . That is, in the configuration in which the mounting face  19  extends in the axial direction, the effect that it is possible to suppress the occurrence of a defect in the electrolytic capacitor  41  can be more effectively obtained. With the configuration of the circuit board  40  as described above, it is possible to suppress an increase in size of the electric pump  100  in the axial direction and the mounting direction. That is, according to the present embodiment, it is possible to suppress the occurrence of a defect in the electrolytic capacitor  41  attached to the circuit board  40  while disposing the circuit board  40  in which the electric pump  100  can be prevented from increasing in size in the axial direction and the mounting direction. 
     According to the present embodiment, the electrolytic capacitor  41  includes two or more electrolytic capacitors  41  disposed side by side along the axial direction. Therefore, as compared with a case where two or more electrolytic capacitors  41  are disposed side by side along the mounting direction, two or more electrolytic capacitors  41  can be disposed closer to the mounting face  19 . As a result, it is possible to further suppress the occurrence of a defect in two or more electrolytic capacitors  41 . In the present embodiment, since the three electrolytic capacitors  41 A,  41 B, and  41 C are disposed side by side along the axial direction, it is possible to further suppress the occurrence of failure in any of the three electrolytic capacitors  41 A,  41 B, and  41 C. 
     According to the present embodiment, two or more electrolytic capacitors  41  among the plurality of electrolytic capacitors  41  are disposed along the imaginary arc C centered on one fixing portion  47   g  among the plurality of fixing portions  47  when viewed in the direction orthogonal to the plate face of the circuit board  40 . Therefore, two or more electrolytic capacitors  41  can be disposed around the fixing portion  47   g.  In the present embodiment, all the electrolytic capacitors  41 A,  41 B, and  41 C are disposed along the imaginary arc C when viewed in the vertical direction, and are disposed around the fixing portion  47   g.  Here, the amplitude of the vibration generated in the circuit board  40  tends to be smaller around the fixing portion  47  in the circuit board  40 . Therefore, by disposing two or more electrolytic capacitors  41  around one fixing portion  47 , it is easy to further reduce the vibration applied to the two or more electrolytic capacitors  41 . As a result, it is possible to further suppress the occurrence of a defect in two or more electrolytic capacitors  41 . In the present embodiment, it is possible to further suppress the occurrence of a defect in all the electrolytic capacitors  41 A,  41 B, and  41 C. In addition, by collectively disposing two or more electrolytic capacitors  41  around one fixing portion  47   g,  the two or more electrolytic capacitors  41  can be collectively disposed on the circuit board  40 , and respective electronic components can be efficiently disposed on the circuit board  40 . 
     According to the present embodiment, the plurality of fixing portions  47  includes the pair of fixing portions  47  disposed with at least part of the electrolytic capacitor  41  interposed therebetween when viewed in the direction orthogonal to the plate face of circuit board  40 . As described above, the amplitude of the vibration generated in the circuit board  40  tends to be smaller around the fixing portion  47  in the circuit board  40 . Therefore, the amplitude of the vibration generated in the circuit board  40  tends to be small also between the fixing portion  47  and the fixing portion  47 . Consequently, at least part of the electrolytic capacitor  41  is disposed between the pair of fixing portions  47 , so that the vibration applied to electrolytic capacitor  41  can be easily reduced. Accordingly, it is possible to further suppress the occurrence of a defect in the electrolytic capacitor  41 . 
     Further, according to the present embodiment, the electric pump  100  includes the choke coil  42  attached to the plate face of the circuit board  40  as an electronic component having a mass larger than that of the electrolytic capacitor  41 . The choke coil  42  is disposed at a position closer to the mounting face  19  than the center axis J in the direction orthogonal to the mounting face  19 . As the electronic component having a relatively large mass is disposed farther from the mounting face  19 , the amplitude of the vibration generated in the circuit board  40  tends to be larger due to the mass of the electronic component. Therefore, by disposing the choke coil  42 , which is an electronic component having a relatively large mass, at a position closer to the mounting face  19  than the center axis J, it is possible to suppress an increase in amplitude of the vibration generated in the circuit board  40  due to the mass of the choke coil  42 . Consequently, the amplitude of the vibration generated in circuit board  40  can be easily reduced, and the vibration applied to electrolytic capacitor  41  can be easily reduced. Thus, it is possible to further suppress the occurrence of a defect in the electrolytic capacitor  41 . 
     According to the present embodiment, the electronic component having a mass larger than that of the electrolytic capacitor  41  is the choke coil  42 , which is an inductor. The choke coil  42  tends to have the largest mass among the electronic components attached to the circuit board  40 . Therefore, by disposing the choke coil  42  at a position closer to the mounting face  19  than the center axis J, it is easy to more suitably reduce the amplitude of the vibration generated in the circuit board  40 . Thus, the vibration applied to the electrolytic capacitor  41  can be more suitably reduced. Therefore, it is possible to further suitably suppress the occurrence of a defect in the electrolytic capacitor  41 . 
     According to the present embodiment, the choke coil  42 , which is an electronic component having a larger mass than electrolytic capacitor  41 , is disposed side by side with electrolytic capacitor  41  along the axial direction. Therefore, compared with the case that the choke coil  42  is disposed side by side with the electrolytic capacitor  41  along the mounting direction, the choke coil  42  can be disposed closer to the mounting face  19 . As a result, it is easy to more suitably reduce the amplitude of the vibration generated in the circuit board  40 . Therefore, it is possible to further suitably suppress the occurrence of a defect in the electrolytic capacitor  41 . 
     According to the present embodiment, the electric pump  100  further includes the shunt resistor  45  attached to the plate face of the circuit board  40 . The shunt resistor  45  is disposed at a position closer to the mounting face  19  than the center axis J in the direction orthogonal to the mounting face  19 . Therefore, similarly to the electrolytic capacitor  41  described above, it is easy to reduce the vibration applied to the shunt resistor  45 . Therefore, it is possible to suppress the occurrence of a defect such as damage to the shunt resistor  45 . Similarly to the electrolytic capacitor  41 , the shunt resistor  45  is an electronic component that is relatively more likely to be damaged by vibration than other electronic components. Therefore, it is possible to further suppress the occurrence of a defect in the shunt resistor  45 , so that it is possible to further improve the reliability of the electric pump  100 . 
     The present invention is not limited to the above-described embodiment, and other structures and other methods may be employed within the scope of the technical idea of the present invention. The circuit board may be disposed in any manner as long as the circuit board is located radially outside the motor, the plate face is directed in the radial direction, and the plate face is disposed along the direction intersecting the mounting face. The plate face of the circuit board may be inclined with respect to a direction orthogonal to the mounting face. The plate face of the circuit board may not be orthogonal to the vertical direction. The number and position of the fixing portions in the circuit board are not particularly limited. When a plurality of fixing portions is provided, the plurality of fixing portions may not include a pair of fixing portions with at least part of the electrolytic capacitor interposed therebetween when viewed in a direction orthogonal to the plate face of the circuit board. 
     The electrolytic capacitor may be disposed at any position as long as it is disposed at a position closer to the mounting face than the center axis in the direction orthogonal to the mounting face. The electrolytic capacitor may be disposed at the same position as the center of gravity of the electric pump in the direction orthogonal to the mounting face, or may be disposed at a position farther from the mounting face than the center of gravity of the electric pump. The electrolytic capacitor may not be disposed around the fixing portion provided on the circuit board. 
     The number of electrolytic capacitors is not particularly limited. Only one electrolytic capacitor may be provided, only two electrolytic capacitors may be provided, or four or more electrolytic capacitors may be provided. When a plurality of electrolytic capacitors is provided, some two or more electrolytic capacitors among the plurality of electrolytic capacitors may be disposed side by side along the axial direction, and the other one or more electrolytic capacitors among the plurality of electrolytic capacitors may not be disposed side by side along the axial direction. Not all of the plurality of electrolytic capacitors may be disposed along the axial direction. The plurality of electrolytic capacitors may include one or a plurality of electrolytic capacitors that are not disposed along an imaginary arc centered on one fixing portion when viewed in a direction orthogonal to the plate face of the circuit board. 
     The electronic component having a mass larger than that of the electrolytic capacitor may be an electronic component other than the inductor. When the electronic component having a mass larger than that of the electrolytic capacitor is an inductor, the electronic component may be an inductor other than the choke coil. The arrangement of the electronic component having a mass larger than that of the electrolytic capacitor is not particularly limited. The electronic component having a mass larger than that of the electrolytic capacitor may be disposed at the same position as the center axis in the direction orthogonal to the mounting face, or may be disposed at a position farther from the mounting face than the center axis. An electronic component having a mass larger than that of the electrolytic capacitor may not be provided. 
     The arrangement of the shunt resistor is not particularly limited. The shunt resistor may be disposed at the same position as the center axis in the direction orthogonal to the mounting face, or may be disposed at a position farther from the mounting face than the center axis. The shunt resistor may not be provided. 
     The application of the electric pump to which the present invention is applied is not particularly limited. The type of the fluid sent by the electric pump is not particularly limited, and may be water or the like. The predetermined object to which the electric pump is attached may be any object. The electric pump may be mounted on a device other than the vehicle. The electric pump may be disposed in any manner with respect to the vertical direction. The center axis of the motor of the electric pump may extend in a direction inclined with respect to the vertical direction without being orthogonal to the vertical direction, or may extend in parallel with the vertical direction. Each configuration and method described in this description can be combined as appropriate within a scope that does not give rise to mutual contraction. 
     Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While preferred 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.