Electric pump

Abstract

An electric pump (100) comprises: a pump unit (10) that discharges a liquid; a motor unit (20) that rotates a drive shaft (1) to drive the pump unit (10); and a housing (40) that accommodates the pump unit (10) and the motor unit (20). A bearing (60) for rotatably supporting the drive shaft (1) is mounted on an outer peripheral surface of the drive shaft (1), and the housing (40) has a bearing accommodating recess (45) for accommodating the bearing (60). The bearing accommodating recess (45) accommodates a snap ring (65), which is mounted in contact with a surface of the bearing (60) on an opening (45a) side of the bearing accommodating recess (45) and held in the bearing accommodating recess (45) to support the bearing (60), and a washer (70) which is provided between the bearing (60) and a bottom surface (45c) of the bearing accommodating recess (45), and biases the bearing (60) toward the snap ring (65).

Description

electric pump

[0001] The present invention relates to an electric pump.

[0002] JP2010-112302A discloses an electric pump unit in which a pump, an electric motor for driving the pump, and a motor controller are assembled in a unit housing. A bearing is provided on the outer circumferential surface of the pump drive motor shaft driven by the motor. The bearing is press-fitted into the housing of the electric pump unit.

[0003] In the electric pump unit described in JP2010-112302A, the bearing is press-fit into the housing, so it is time-consuming to remove the bearing from the housing during maintenance. Therefore, there is room for improvement in maintainability in the electric pump unit described in JP2010-112302A.

[0004] An object of the present invention is to improve the maintainability of an electric pump.

[0005] According to one aspect of the present invention, there is provided an electric pump comprising: a pump section that discharges liquid; a motor section that rotates a drive shaft to drive the pump section; and a housing that accommodates the pump section and the motor section, wherein a bearing that rotatably supports the drive shaft is provided on the outer peripheral surface of the drive shaft, and the housing has a bearing accommodating recess in which the bearing is accommodated, and the bearing accommodating recess accommodates a support ring that is provided in contact with the surface of the bearing on the opening side of the bearing accommodating recess and is held in the bearing accommodating recess to support the bearing, and a biasing ring that is provided between the bearing and the bottom surface of the bearing accommodating recess and biases the bearing toward the support ring.

[0006] Fig. 1 is a perspective view of an electric pump according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of the electric pump according to an embodiment of the present invention. Fig. 3 is a plan view of a pump portion. Fig. 4 is a plan view of a rotor.

[0007] An electric pump 100 according to an embodiment of the present invention will be described below with reference to the drawings. The electric pump 100 is mounted on, for example, a vehicle and discharges a coolant (liquid) for cooling an electric motor mounted on the vehicle, or discharges oil (liquid) for lubricating gears mounted on the vehicle. The electric pump 100 may also be used as a fluid pressure supply source that discharges a working fluid (liquid) for driving equipment. The electric pump 100 may also be mounted on industrial machinery other than a vehicle.

[0008] FIG. 1 is a perspective view of electric pump 100, and FIG. 2 is a cross-sectional view of electric pump 100 taken along line II-II in FIG. 1. As shown in FIG. 2, electric pump 100 includes a pump unit 10 that discharges liquid, a motor unit 20 that rotates a drive shaft 1 to drive pump unit 10, a control unit 30 that controls motor unit 20, and a housing 40 that accommodates pump unit 10, motor unit 20, and control unit 30. In electric pump 100, the control unit 30, motor unit 20, and pump unit 10 are arranged in this order from the top in FIGS. 1 and 2. Hereinafter, the axial direction of drive shaft 1 will also be simply referred to as the "axial direction," and the radial direction of drive shaft 1 will also be simply referred to as the "radial direction."

[0009] 3 is a plan view of the pump unit 10 viewed from below in FIGS. 1 and 2 , with the pump cover 56 of the housing 40 covering the pump unit 10 removed. The pump unit 10 is an internal gear pump having an inner rotor 11 to which the drive shaft 1 is connected and an outer rotor 12 disposed outside the inner rotor 11. The inner rotor 11 and the outer rotor 12 are housed in the housing 40 (specifically, the housing main body 41 described below), are eccentrically disposed relative to each other, and are covered by the pump cover 56 of the housing 40. Specifically, the inner rotor 11 is disposed so that its center overlaps with the drive shaft 1, and the outer rotor 12 is disposed so that its center is offset from the drive shaft 1. The inner rotor 11 has a plurality of external teeth 11a on its outer peripheral surface, and the outer rotor 12 has a plurality of internal teeth 12a on its inner peripheral surface that slide against the external teeth 11a. The external teeth 11a and the internal teeth 12a are formed with different numbers of teeth, and a pump chamber 13 is defined by adjacent external teeth 11a of the inner rotor 11 and internal teeth 12a of the outer rotor 12. A plurality of pump chambers 13 are formed in the pump section 10.

[0010] The pump cover 56 that covers the pump section 10 is formed with a suction port (not shown) that introduces liquid from the outside into the pump chamber 13, and a discharge port (not shown) that introduces liquid discharged from the pump chamber 13 to the outside. When the drive shaft 1 rotates, the inner rotor 11 and the outer rotor 12 rotate while the external teeth 11a of the inner rotor 11 slide against the internal teeth 12a of the outer rotor 12. As the inner rotor 11 and the outer rotor 12 rotate, the volume of the pump chamber 13 repeatedly expands and contracts. In the expansion region (suction region) where the pump chamber 13 expands, liquid is sucked in through the suction port, and in the contraction region (discharge region) where the pump chamber 13 contracts, coolant is discharged and introduced to the outside through the discharge port.

[0011] 2, the motor unit 20 has an annular stator 21 and a rotor 25 disposed radially inside the stator 21. The stator 21 and the rotor 25 are housed in a housing 40 (specifically, a housing main body 41, which will be described later).

[0012] The stator 21 includes an annular stator core 22 disposed to surround the rotor 25 and a coil wire 23 wound around the stator core 22. The stator core 22 includes an annular yoke portion 22a that contacts the inner peripheral surface of the housing 40 (housing main body 41) and a plurality of teeth 22b that protrude radially inward from the yoke portion 22a and are arranged at predetermined intervals in the circumferential direction. The yoke portion 22a is formed with a plurality of protrusions 22c that protrude in the axial direction toward the control unit 30. The coil wire 23 is wound around the teeth 22b of the stator core 22. As a result, a U-phase coil, a V-phase coil, and a W-phase coil corresponding to the three-phase drive current are formed on each tooth portion 22b. The ends of each coil wire 23 are connected to the control unit 30.

[0013] Figure 4 is a plan view of the rotor 25 as seen from above in Figure 2. As shown in Figures 2 and 4, the rotor 25 includes a rotor core 26 that is provided on the outer peripheral surface of the drive shaft 1 and rotates together with the drive shaft 1, and a plurality of permanent magnets 27 that are provided on the outer peripheral surface of the rotor core 26. The permanent magnets 27 are arranged in an annular shape, with north and south poles arranged alternately. The rotor core 26 includes an annular wall portion 26a (see Figure 2) that is provided on the inner peripheral surface of the permanent magnets 27, and a disk portion 26b that is provided at one axial end of the wall portion 26a. The disk portion 26b is provided at the upper end of the wall portion 26a in Figure 2. The disk portion 26b is formed with a maintenance hole 26c (see FIG. 4) that penetrates the disk portion 26b in the axial direction, an insertion hole 26d that penetrates the center and into which the drive shaft 1 is inserted and press-fitted, and a cylindrical portion 26e (see FIG. 2) that protrudes toward the bearing 60 (described later) and has the insertion hole 26d on its inner circumferential surface. The maintenance holes 26c are formed on an arc centered on the insertion hole 26d, and three cylindrical portions 26e are formed circumferentially spaced apart from each other. The cylindrical portions 26e abut against the bearing 60 (described later). The functions of the maintenance holes 26c and the cylindrical portions 26e will be described later. In the motor portion 20, the rotor 25 rotates around the drive shaft 1 due to the interaction between the magnetization state of the stator core 22 of the stator 21 and the permanent magnet 27. This drives the pump portion 10.

[0014] A bearing 60 for rotatably supporting the drive shaft 1 and an oil seal 75 are provided on the outer peripheral surface of the drive shaft 1 driven by the motor unit 20. The bearing 60 and the oil seal 75 are housed in the housing 40.

[0015] The control unit 30 controls the current supplied to the stator 21 to drive the motor unit 20. The control unit 30 includes electronic components 31 and a substrate 32 on which the electronic components 31 are mounted and to which the coil wires 23 of the motor unit 20 are connected. The electronic components 31 include, for example, a magnetic detection sensor such as a Hall element that can detect changes in magnetism that occur in response to the rotation of the drive shaft 1, and a calculation unit that calculates the rotation angle and rotation speed of the drive shaft 1 based on the detection value of the magnetic detection sensor. The control unit 30 controls the direction of the current flowing through the coil wires 23 of the stator 21 in accordance with the rotation angle of the drive shaft 1, and also controls the magnitude of the current supplied to the coil wires 23 so that the rotation speed of the drive shaft 1 matches a target rotation speed input from outside. The electronic components 31 are mounted on both sides of the substrate 32. A heat dissipation unit 33 that dissipates heat from the substrate 32 is provided on the side of the substrate 32 opposite the motor unit 20 (the upper side in FIG. 2 ).

[0016] As shown in FIG. 2 , the housing 40 includes a housing body portion 41 having an opening 42 , a cover portion 51 that covers the opening 42 , and a pump cover portion 56 that covers the pump portion 10 .

[0017] The housing main body 41 has an insertion hole 43 through which the drive shaft 1 is inserted, an annular motor accommodating recess 44 in which the motor section 20 is accommodated, a bearing accommodating recess 45 provided radially inside the motor accommodating recess 44 in which a bearing 60 and the like are accommodated, an oil seal accommodating recess 46 formed axially continuous with the bearing accommodating recess 45 in which an oil seal 75 is accommodated, and a pump accommodating recess 47 in which the pump section 10 is accommodated.

[0018] The insertion hole 43 is formed to extend in the axial direction through the opening 42, the bearing accommodating recess 45, the oil seal accommodating recess 46, and the pump accommodating recess 47. The motor accommodating recess 44 is formed continuously with the opening 42 and has an outer inner circumferential surface 44a, which is an inner circumferential surface located on the radially outer side, and an inner inner circumferential surface 44b, which is an inner circumferential surface located on the radially inner side. The annular yoke portion 22a of the stator core 22 of the motor section 20 is provided in contact with the outer inner circumferential surface 44a, and the wall portion 26a of the rotor core 26 of the rotor 25 faces the inner inner circumferential surface 44b.

[0019] As described above, the rotor core 26 is mounted in the motor accommodating recess 44 provided radially outward, and therefore the bearing accommodating recess 45 is covered by the disk portion 26b of the rotor core 26. That is, the rotor core 26 is mounted such that the disk portion 26b seals the opening 45a of the bearing accommodating recess 45. The maintenance hole 26c of the rotor 25 faces the bearing accommodating recess 45. As shown in FIG. 2 , the bearing accommodating recess 45 accommodates a bearing 60 that is mounted on the outer circumferential surface of the drive shaft 1 and rotatably supports the drive shaft 1, an annular snap ring 65 that serves as a support ring supporting the bearing 60, and an annular washer 70 that serves as a biasing ring that biases the bearing 60 toward the snap ring 65. In the electric pump 100, the bearing accommodating recess 45 is positioned inside the rotor 25 and accommodates the bearing 60 and other components, thereby enabling a reduction in the axial dimension.

[0020] The bearing 60 is not press-fit into the bearing accommodating recess 45, and the fit between the bearing 60 and the bearing accommodating recess 45 is a loose fit. An opening 45a of the bearing accommodating recess 45 is formed on the opening 42 side of the housing main body 41 (the upper side in FIG. 2 ), and an annular groove 45b is formed to hold a snap ring 65. The snap ring 65 is provided in contact with the surface of the bearing 60 facing the opening 45a of the bearing accommodating recess 45. The snap ring 65 is retained in the bearing accommodating recess 45 by being received in the groove 45b, thereby supporting the bearing 60. The snap ring 65 is radially expandable and contractible, and by doing so, can be switched between a state in which it is retained in the bearing accommodating recess 45 and a state in which it is not retained (in other words, a state in which it is received in the groove 45b and a state in which it is not received). As described above, the rotor 25 is formed with a maintenance hole 26c facing the bearing accommodating recess 45, and the snap ring 65 can be visually observed through the maintenance hole 26c of the rotor 25 (see FIG. 4 ). Therefore, the snap ring 65 can be expanded or contracted by inserting a tool (not shown) into the maintenance hole 26c and fitting it into the openings 65a provided at both circumferential ends of the snap ring 65. In this way, even when the rotor 25 is attached, the snap ring 65 can be switched between a state in which it is held in the bearing accommodating recess 45 and a state in which it is not held therein via the maintenance hole 26c. Note that the maintenance hole 26c is formed with two openings 65a of the snap ring 65 facing each other so that the snap ring 65 can be expanded or contracted using a tool. Specifically, the maintenance hole 26c is formed with a size such that one opening 65a faces each of two maintenance holes 26c, or such that two openings 65a face each of one maintenance hole 26c. A washer 70 is provided between the bearing 60 and the bottom surface 45c of the bearing accommodating recess 45 and biases the bearing 60 toward the snap ring 65. Therefore, the bearing 60 is held in the bearing accommodating recess 45 while being pressed against the snap ring 65 by the washer 70. This prevents the bearing 60 from rattling in the axial direction.

[0021] The oil seal accommodating recess 46 is formed to have a smaller diameter than the bearing accommodating recess 45 and accommodates the oil seal 75. The oil seal accommodating recess 46 is provided between the bearing accommodating recess 45 and the pump accommodating recess 47.

[0022] The pump accommodating recess 47 is formed with its center offset from the insertion hole 43, and accommodates the inner rotor 11 and the outer rotor 12 of the pump section 10. A plurality of fastening holes 47a are formed in the end face of the pump accommodating recess 47 (see FIG. 3 ), into which fastening members (not shown) for attaching the pump cover section 56 are fastened.

[0023] The cover 51 has a protrusion 51a that protrudes from the opposite side to the housing main body 41 (upward in FIG. 2 ). The protrusion 51a is hollow, and the board 32 and heat dissipation unit 33 of the control unit 30 are housed in the hollow part of the protrusion 51a. The board 32 housed in the housing 40 is electrically connected to the outside via a connector (not shown) provided on the housing main body 41. The cover 51 is fixed to the housing main body 41 with fastening members 81.

[0024] The pump cover portion 56 is provided to cover the pump accommodating recess 47. The pump cover portion 56 is formed with insertion holes (not shown) through which fastening members (not shown) are inserted, and the pump cover portion 56 is fixed to the housing main body portion 41 by the fastening members. The pump cover portion 56 is formed with the suction port 56a and the discharge port 56b as described above.

[0025] Next, a method for assembling the electric pump 100 will be described in detail.

[0026] To assemble the electric pump 100, first, the oil seal 75 is placed in the oil seal accommodating recess 46, and the washer 70 is placed in the bearing accommodating recess 45. Then, the bearing 60 is press-fitted onto the drive shaft 1. Next, the drive shaft 1 with the press-fitted bearing 60 is inserted into the insertion hole 43 from the opening 42 side of the housing main body 41. As a result, the oil seal 75 is attached to the outer peripheral surface of the drive shaft 1, and the bearing 60 abuts against the washer 70. Then, the snap ring 65 is placed and held in the groove 45b of the bearing accommodating recess 45. The axial position of the drive shaft 1, with the bearing 60 and oil seal 75 provided, relative to the housing 40 is determined by holding the snap ring 65 in the groove 45b.

[0027] Thereafter, the insertion hole 26d of the rotor 25 is press-fit onto the drive shaft 1, and the rotor 25 is accommodated in the motor accommodating recess 44. In this state, the cylindrical portion 26e of the rotor 25 is inserted into the hollow portion of the snap ring 65 and abuts against the bearing 60. The stator 21 is then accommodated in the motor accommodating recess 44, and the pump section 10 is further accommodated in the pump accommodating recess 47. Finally, the cover portion 51 of the housing 40, to which the control section 30 is attached, and the pump cover portion 56 are attached to the housing main body 41, thereby completing the assembly of the electric pump 100.

[0028] As described above, in the electric pump 100, the bearing 60 is supported by the snap ring 65 under the biasing force of the washer 70, rather than being press-fitted, and is held in the bearing accommodating recess 45. Therefore, the bearing 60 can be easily removed from the housing 40 simply by removing the snap ring 65 from the bearing accommodating recess 45. Specifically, the drive shaft, rotor 25, and bearing 60 can be easily removed from the housing 40 as an integrated assembly simply by removing the snap ring 65 from the groove 45b and then removing it from the bearing accommodating recess 45. This improves the maintainability of the electric pump 100.

[0029] Furthermore, in the electric pump 100, the drive shaft 1, bearing 60, oil seal 75, rotor 25, and stator 21 are all inserted and assembled from the opening 42 side of the housing main body 41. Therefore, when disassembling the electric pump 100 for maintenance, these components can all be removed from one direction, improving the maintainability of the electric pump 100. In addition, in the electric pump 100, the above components are inserted and assembled from one direction, so the inner circumferential surface of the housing 40 can be machined from one direction. Therefore, compared to when the above components are inserted from two different directions and the inner circumferential surface of the housing 40 needs to be machined from two directions, the coaxiality of the above components is improved.

[0030] Furthermore, in the electric pump 100, the axial position of the drive shaft 1 relative to the housing 40 can be easily determined by accommodating the snap ring 65 in the groove 45b and holding the bearing 60 in the bearing accommodating recess 45.

[0031] In addition, in the electric pump 100, by switching the snap ring 65 to a state where it is not held in the bearing accommodating recess 45 through the maintenance hole 26c of the rotor 25, the bearing 60 can be easily removed from the housing 40 together with the drive shaft 1, rotor 25, etc.

[0032] Furthermore, in the electric pump 100, the cylindrical portion 26e of the rotor 25 is inserted into the hollow portion of the snap ring 65 and abuts against the bearing 60. This increases the contact area (press-fit area) between the drive shaft 1 and the rotor 25, and the hollow portion of the snap ring 65 can be used to more firmly connect the drive shaft 1 and the rotor 25.

[0033] According to the present embodiment described above, the following effects are achieved.

[0034] In the electric pump 100, the bearing 60 is supported by the snap ring 65 under the biasing force of the washer 70 and is held in the bearing accommodating recess 45. Therefore, the bearing 60 can be easily removed from the housing 40 by simply removing the snap ring 65 from the bearing accommodating recess 45, improving the maintainability of the electric pump 100.

[0035] Next, modified examples of this embodiment will be described. The following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above embodiment, or to combine the configurations described in the different modified examples below.

[0036] <Modification 1> In the above embodiment, an annular groove 45b is formed in the bearing accommodating recess 45, and the snap ring 65 is held in the groove 45b to hold the bearing 60 in the bearing accommodating recess 45, thereby determining the axial position of the drive shaft 1 relative to the housing 40. However, this is not limiting, and the groove 45b does not have to be annular as long as it can hold the snap ring 65. Furthermore, the groove 45b is not essential, and the snap ring 65 may be held in the bearing accommodating recess 45 by a structure other than the groove 45b.

[0037] <Modification 2> In the above embodiment, the oil seal 75 is provided on the outer peripheral surface of the drive shaft 1, and the housing main body 41 of the housing 40 has the oil seal accommodating recess 46. However, the oil seal 75 and the oil seal accommodating recess 46 are not essential components of the electric pump 100.

[0038] <Modification 3> In the above embodiment, the motor accommodating recess 44 is provided radially outward of the bearing accommodating recess 45. This positions the bearing accommodating recess 45 inside the rotor 25 and accommodates the bearing 60 and the like, thereby reducing the axial dimension of the electric pump 100. However, although this increases the axial dimension of the electric pump 100, the motor accommodating recess 44 may be provided alongside the bearing accommodating recess 45 in the axial direction rather than radially outward of the bearing accommodating recess 45.

[0039] <Modification 4> In the above embodiment, the rotor 25 (rotor core 26) is formed with the maintenance hole 26c and the cylindrical portion 26e into which the drive shaft 1 is press-fitted. However, the maintenance hole 26c and the cylindrical portion 26e are not essential components of the electric pump 100.

[0040] The configuration, operation, and effects of the embodiment of the present invention will be described below.

[0041] The electric pump 100 comprises a pump section 10 that discharges liquid, a motor section 20 that rotates a drive shaft 1 to drive the pump section 10, and a housing 40 that accommodates the pump section 10 and the motor section 20. A bearing 60 that rotatably supports the drive shaft 1 is provided on the outer peripheral surface of the drive shaft 1, and the housing 40 has a bearing accommodating recess 45 in which the bearing 60 is accommodated. The bearing accommodating recess 45 accommodates a snap ring 65 that is provided in contact with the surface of the bearing 60 on the side of the opening 45a of the bearing accommodating recess 45 and serves as a support ring that is held in the bearing accommodating recess 45 and supports the bearing 60, and a washer 70 that is provided between the bearing 60 and a bottom surface 45c of the bearing accommodating recess 45 and serves as a biasing ring that biases the bearing 60 toward the snap ring 65.

[0042] In this configuration, the bearing 60 is supported by the snap ring 65 under the biasing force of the washer 70 and is held in the bearing accommodating recess 45. Therefore, the bearing 60 can be easily removed from the housing 40 by simply removing the snap ring 65 from the bearing accommodating recess 45. This improves the maintainability of the electric pump 100.

[0043] In addition, in the electric pump 100, an oil seal 75 is further provided on the outer peripheral surface of the drive shaft 1, and the housing 40 further has an oil seal accommodating recess 46 that is continuous with the bearing accommodating recess 45 and has a smaller diameter than the bearing accommodating recess 45, and that accommodates the oil seal 75, and a groove 45b that holds a snap ring 65 is formed in the bearing accommodating recess 45, and the axial position of the drive shaft 1 provided with the bearing 60 and oil seal 75 relative to the housing 40 is determined by the snap ring 65 being held in the groove 45b.

[0044] In this configuration, the axial position of the drive shaft 1 relative to the housing 40 can be easily determined by accommodating the snap ring 65 in the groove 45 b and holding the bearing 60 in the bearing accommodating recess 45 .

[0045] In addition, in the electric pump 100, the motor section 20 has an annular stator 21 and a rotor 25 arranged radially inside the stator 21, and the housing 40 further has an annular motor accommodating recess 44 arranged radially outside the bearing accommodating recess 45 and accommodating the stator 21 and rotor 25.

[0046] In this configuration, the bearing accommodating recess 45 is located inside the rotor 25 and accommodates the bearing 60 and the like, so the axial dimension of the electric pump 100 can be reduced.

[0047] Furthermore, in the electric pump 100, a maintenance hole 26c is formed in the rotor 25, which penetrates the rotor 25 in the axial direction and faces the bearing accommodating recess 45, and the snap ring 65 can be switched between a state in which it is held in the bearing accommodating recess 45 and a state in which it is not held therein through the maintenance hole 26c.

[0048] In this configuration, the bearing 60 can be easily removed from the housing 40 by switching the snap ring 65 to a state where it is not held in the bearing accommodating recess 45 through the maintenance hole 26 c of the rotor 25 .

[0049] In addition, in the electric pump 100 , the rotor 25 is formed with a cylindrical portion 26 e into which the drive shaft 1 is press-fitted, and the cylindrical portion is inserted into the hollow portion of the snap ring 65 and abuts against the bearing 60 .

[0050] In this configuration, the hollow portion of the snap ring 65 can be used to more firmly connect the drive shaft 1 and the rotor 25.

[0051] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0052] This application claims priority based on Japanese Patent Application No. 2023-51945, filed with the Japan Patent Office on March 28, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An electric pump, a pump unit that discharges liquid; a motor unit that rotates a drive shaft to drive the pump unit; a housing that accommodates the pump unit and the motor unit, a bearing for rotatably supporting the drive shaft is provided on an outer circumferential surface of the drive shaft; the motor unit has an annular stator and a rotor disposed radially inside the stator, the housing has a bearing accommodating recess in which the bearing is accommodated, and an annular motor accommodating recess that is provided radially outward of the bearing accommodating recess and in which the stator and the rotor are accommodated, The bearing accommodating recess has: a support ring provided in contact with a surface of the bearing on the opening side of the bearing accommodating recess, the support ring being held in the bearing accommodating recess to support the bearing; a biasing ring that is provided between the bearing and a bottom surface of the bearing accommodating recess and biases the bearing toward the support ring, a maintenance hole that penetrates the rotor in the axial direction and faces the bearing accommodating recess; The electric pump, wherein the support ring can be switched between a state in which it is held in the bearing accommodating recess and a state in which it is not held in the bearing accommodating recess through the maintenance hole.

2. 2. The electric pump according to claim 1, An oil seal is further provided on the outer circumferential surface of the drive shaft, the housing further includes an oil seal accommodating recess that is continuous with the bearing accommodating recess, has a smaller diameter than the bearing accommodating recess, and accommodates the oil seal, A groove for holding the support ring is formed in the bearing accommodating recess, The electric pump has an axial position of the drive shaft, on which the bearing and the oil seal are provided, relative to the housing, determined by the support ring being held in the groove.

3. An electric pump as described in claim 1, the rotor is formed with a cylindrical portion into which the drive shaft is press-fitted, The cylindrical portion is inserted into the hollow portion of the support ring and abuts against the bearing.