CN215058125U

CN215058125U - Electric pump

Info

Publication number: CN215058125U
Application number: CN202121351963.8U
Authority: CN
Inventors: 小林喜幸; 樋口孔二; 吴楠; 阮氏清三
Original assignee: Nidec Tosok Corp
Current assignee: Nidec Tosok Corp
Priority date: 2020-06-23
Filing date: 2021-06-17
Publication date: 2021-12-07
Anticipated expiration: 2031-06-17
Also published as: JP2022003236A; JP7452282B2

Abstract

The utility model provides an electric pump, it has: a motor unit having a shaft rotatable about a central axis extending in an axial direction; and a pump section located on one axial side of the motor section and connected to the shaft. The pump section has: an inner rotor coupled to the shaft; and an outer rotor surrounding and engaged with the inner rotor. The inner rotor has a hole portion into which a part of the shaft is inserted. The shaft has: a support portion that supports the inner rotor in a radial direction centered on the central axis; and a torque transmission portion that transmits torque to the inner rotor. The hole portion has: a fitting hole portion in which the support portion is fitted; and a coupling hole portion into which the torque transmission portion is inserted and which couples the torque transmission portion around the central axis.

Description

Electric pump

Technical Field

The utility model relates to an electric pump.

Background

An electric pump having a structure in which an inner rotor is coupled to a shaft of a motor unit is known. For example, as such an electric pump, patent document 1 describes an oil pump disposed in a transmission of a continuously variable transmission for a vehicle.

Patent document 1: japanese laid-open patent publication No. 11-050972

In the electric pump as described above, a portion for positioning the inner rotor in the radial direction may be provided in the housing of the electric pump. However, in this case, when the dimensional accuracy of the housing is poor, or when the assembly accuracy of the housing is poor, or the like, the radial position of the inner rotor is shifted, and there is a possibility that the inner rotor cannot be arranged with high axial accuracy with respect to the shaft of the motor portion.

SUMMERY OF THE UTILITY MODEL

In view of the above, an object of the present invention is to provide an electric pump having a structure capable of improving the shaft accuracy of an inner rotor with respect to a shaft.

A first aspect of the present invention provides an electric pump, characterized in that: a motor unit having a shaft rotatable about a central axis extending in an axial direction; and a pump section located on one axial side of the motor section and coupled to the shaft. The pump section includes: an inner rotor coupled to the shaft; and an outer rotor surrounding and meshing with the inner rotor. The inner rotor has a hole portion into which a part of the shaft is inserted. The shaft has: a support portion that supports the inner rotor in a radial direction centered on the central axis; and a torque transmission unit that transmits torque to the inner rotor. The hole portion has: a fitting hole portion into which the support portion is fitted; and a coupling hole portion into which the torque transmission portion is inserted, and which is coupled to the coupling hole portion around the central axis.

The electric pump according to a second aspect of the present invention is the electric pump according to the first aspect, wherein the torque transmission portion has a plurality of outer teeth portions on an outer peripheral surface, and the coupling hole portion has a plurality of inner teeth portions on an inner peripheral surface thereof, the plurality of inner teeth portions being engaged with each other by the plurality of outer teeth portions.

The utility model discloses an electric pump of third mode's characterized in that, in the electric pump of first mode, the inner rotor has: an inner rotor body portion; and a protruding portion that protrudes in the axial direction from the inner rotor body portion, wherein the hole portion is provided across the inner rotor body portion and the protruding portion.

A fourth aspect of the present invention is the electric pump of the third aspect, wherein the fitting hole is provided in the inner rotor main body, and the coupling hole spans the inner rotor main body and the protrusion.

A fifth aspect of the present invention is the electric pump of the fourth aspect, wherein the inner diameter of the connecting hole is smaller than the inner diameter of the fitting hole, and the outer diameter of the torque transmission portion is smaller than the outer diameter of the support portion.

A sixth aspect of the present invention is the electric pump of the fifth aspect, wherein the outer diameter of the protruding portion is larger than the inner diameter of the fitting hole portion.

A seventh aspect of the present invention is the electric pump of the third aspect, wherein the pump section has a pump chamber that accommodates the inner rotor and the outer rotor therein, and a concave portion is provided on a surface on one side in the axial direction in the inner surface of the pump chamber, and the concave portion accommodates the protruding portion therein.

The electric pump according to an eighth aspect of the present invention is the electric pump according to the seventh aspect, wherein the hole portion axially penetrates the inner rotor, an end portion on one side of an axial direction of the shaft is protruded to one side of the axial direction of the inner rotor, and is accommodated in the inside of the concave portion, and the concave portion has: a large diameter portion into which the protruding portion is inserted; and a small diameter portion into which an end portion of the shaft on one side in the axial direction is inserted, and an inner diameter of the small diameter portion is smaller than an inner diameter of the large diameter portion.

The electric pump according to a ninth aspect of the present invention is the electric pump according to any one of the first to eighth aspects, wherein the hole portion axially penetrates the inner rotor, the torque transmission portion is located at a position closer to one side of the axial direction than the support portion, and the hole portion protrudes toward one side of the axial direction than the inner rotor, and an end portion of one side of the axial direction of the torque transmission portion has a tapered portion whose outer diameter decreases as it goes toward one side of the axial direction.

According to the utility model discloses, in the electric pump, can improve the axle precision of inner rotor for the axle.

Drawings

Fig. 1 is a sectional view showing an electric pump of the present embodiment.

Fig. 2 is a sectional view showing a part of the electric pump of the present embodiment, and is a partially enlarged view in fig. 1.

Fig. 3 is a perspective view showing a part of the shaft and the inner rotor of the present embodiment.

Fig. 4 is a sectional view showing the shaft and the pump portion of the present embodiment, and is a sectional view taken along line IV-IV in fig. 2.

Description of the reference symbols

10: an electric pump; 20: a motor section; 20 a: a rotor; 21: a shaft; 21 d: a support portion; 21 e: a torque transmission section; 21 f: an outer tooth portion; 21 g: a tapered portion; 22: a rotor body; 35: a recess; 35 a: a large diameter portion; 35 b: a small diameter part; 40: a pump section; 41: an inner rotor; 41 a: an inner rotor body portion; 41 b: a protrusion; 42: an outer rotor; 43: a pump chamber; 44: a hole portion; 44 a: a fitting hole portion; 44 b: a connecting hole part; 44 c: an inner tooth portion; j: a central axis.

Detailed Description

In the following description, the direction in which the Z axis shown in each drawing extends is referred to as the vertical direction, and the positive side (+ Z side) in the Z axis direction is referred to as the "upper side", and the negative side (-Z side) in the Z axis direction is referred to as the "lower side". The axial direction of the central axis J shown in each figure is parallel to the Z-axis direction, i.e., the vertical direction. The Z-axis direction, which is a direction parallel to the axial direction of the central axis J, is simply referred to as the "axial direction". The radial direction about the central axis J is simply referred to as the "radial direction", and the circumferential direction about the central axis J is simply referred to as the "circumferential direction". In the present embodiment, the lower side corresponds to the "one axial side".

The vertical direction, the upper side, and the lower side are only names for describing relative positional relationships of the respective portions, and the actual positional relationship and the like may be positional relationships other than the positional relationships indicated by these names and the like.

The electric pump 10 of the present embodiment shown in fig. 1 is mounted on a vehicle, for example. The electric pump 10 delivers fluid within the interior of the vehicle. The fluid delivered by the electric pump 10 is, for example, oil. The oil is, for example, ATF (Automatic Transmission Fluid). As shown in fig. 1, the electric pump 10 of the present embodiment includes a motor unit 20, a casing 30, a pump unit 40,

bearings

51 and 52, a bus bar unit 60, a sensor magnet 70, and an oil seal 80.

The motor unit 20 includes a rotor 20a and a stator 20 b. The rotor 20a has a shaft 21 and a rotor body 22. That is, the motor unit 20 includes a shaft 21 and a rotor body 22. Although not shown, the rotor body 22 includes a rotor core fixed to the outer peripheral surface of the shaft 21 and a rotor magnet fixed to the rotor core.

The shaft 21 extends in the axial direction along the center axis J. The shaft 21 has, for example, a cylindrical shape centered on the central axis J. The shaft 21 is rotatable about a central axis J extending in the axial direction. The shaft 21 is supported by

bearings

51 and 52 to be rotatable about the center axis J. The

bearings

51 and 52 are, for example, ball bearings. The shaft 21 includes a small diameter shaft portion 21a, a mounted portion 21b, a large diameter shaft portion 21c, a support portion 21d, and a torque transmission portion 21 e.

A rotor body 22 is fixed to the outer peripheral surface of the small diameter shaft portion 21 a. The small diameter shaft portion 21a protrudes axially on both sides of the rotor body 22. The upper end of the small diameter shaft portion 21a is rotatably supported about the center axis J by a bearing 52. That is, the bearing 52 rotatably supports a portion of the shaft 21 above the rotor body 22.

The attached portion 21b is connected to the upper side of the small diameter shaft portion 21a via a step. The outer diameter of the attached portion 21b is smaller than the outer diameter of the small-diameter shaft portion 21 a. In the present embodiment, the upper end of the attached portion 21b is the upper end of the shaft 21. The axial dimension of the attached portion 21b is smaller than the axial dimension of the small diameter shaft portion 21a, for example. The sensor magnet 70 is attached to the attached portion 21b via an attachment member 71.

The large diameter shaft portion 21c is connected to the lower side of the small diameter shaft portion 21a via a step. The large diameter shaft portion 21c has an outer diameter larger than that of the small diameter shaft portion 21 a. The dimension in the axial direction of the large diameter shaft portion 21c is smaller than the dimension in the axial direction of the small diameter shaft portion 21a, for example. The upper portion of the large-diameter shaft portion 21c is rotatably supported around the central axis J by a bearing 51. That is, the bearing 51 rotatably supports a portion of the shaft 21 below the rotor body 22.

The support portion 21d is connected to the lower side of the large diameter shaft portion 21c via a step. The outer diameter of the support portion 21d is smaller than the outer diameter of the large-diameter shaft portion 21c, for example. The outer diameter of the support portion 21d is, for example, the same as the outer diameter of the small-diameter shaft portion 21 a. The axial dimension of the support portion 21d is smaller than the axial dimension of the large diameter shaft portion 21c, for example. As shown in fig. 2, the support portion 21d is fitted in a fitting hole 44a of the inner rotor 41 described later. The support portion 21d supports the inner rotor 41 in a radial direction around the center axis J.

In the present embodiment, the torque transmission portion 21e is connected to the lower side of the support portion 21d via a step. That is, the torque transmission portion 21e is located below the support portion 21 d. In the present embodiment, the lower end of the torque transmission portion 21e is the lower end of the shaft 21. In the present embodiment, the outer diameter of the torque transmission portion 21e is smaller than the outer diameter of the support portion 21 d. The axial dimension of the torque transmission portion 21e is smaller than the axial dimension of the support portion 21d, for example.

As shown in fig. 3, the torque transmission portion 21e has a plurality of external teeth portions 21f on an outer peripheral surface. The outer teeth 21f project radially outward. The plurality of outer teeth 21f are arranged at equal intervals along the circumferential direction over the entire circumference. The external teeth 21f extend in the axial direction. As shown in fig. 2, the external teeth portion 21f extends to the lower end of the torque transmission portion 21e from a portion of the torque transmission portion 21e slightly separated from the support portion 21d, for example. In the present embodiment, the torque transmission portion 21e is a spline shaft portion.

The torque transmission portion 21e protrudes downward from the inner rotor 41 through a hole 44 described later. The lower end of the torque transmission portion 21e has a tapered portion 21g whose outer diameter decreases toward the lower side. In the present embodiment, the tapered portion 21g is provided in a portion of the torque transmission portion 21e where the external teeth portion 21f is provided. The outer diameter of the portion of the torque transmission portion 21e where the external teeth portions 21f are provided is, for example, the inner diameter of an imaginary cylinder passing through the outer peripheral surfaces of the plurality of external teeth portions 21 f. As shown in fig. 3, the tapered portion 21g includes, for example, reduced diameter portions 21h provided at the lower end portions of the plurality of external teeth portions 21 f. The radially outer surface of the reduced diameter portion 21h is located radially inward as it faces downward. The radial projecting height of the outer teeth 21f of the reduced diameter portion 21h becomes smaller toward the lower side.

As shown in fig. 1, the stator 20b is radially opposed to the rotor 20a with a gap therebetween. In the present embodiment, the stator 20b is located radially outward of the rotor 20 a. The stator 20b has a stator core 23, an insulator 24, and a plurality of coils 25. The stator core 23 has a ring shape surrounding the rotor body 22. Although not shown, stator core 23 has a cylindrical core back portion centered on central axis J and a plurality of teeth extending radially inward from the core back portion. The plurality of coils 25 are attached to the plurality of teeth via insulators, respectively.

The housing 30 accommodates the motor section 20 and the pump section 40 therein. In the present embodiment, the casing 30 includes a casing main body 31, an annular member 32, and a pump cover 33. The casing main body 31, the annular member 32, and the pump cover 33 are, for example, members separate from each other. The casing main body 31, the annular member 32, and the pump cover 33 are made of aluminum, for example. The material of the casing body 31, the material of the annular member 32, and the material of the pump cover 33 are not particularly limited. The casing main body 31, the annular member 32, and the pump cover 33 may be made of, for example, resin or cast iron. For example, the housing main body 31 and the annular member 32 may be made of metal, and the pump cover 33 may be made of resin.

The housing main body 31 has a cylindrical shape with an open upper side. The housing main body 31 is, for example, cylindrical with the center axis J as the center. The housing main body 31 internally houses the motor unit 20. The housing body 31 has a bottom portion 31a, an outer cylindrical portion 31b, an inner cylindrical portion 31c, and a flange portion 31 h. The bottom portion 31a is located on the lower side of the rotor body 22 and the stator 20 b. The bottom 31a expands in the radial direction. For example, the bottom portion 31a has a circular shape centered on the central axis J when viewed in the axial direction. The bottom portion 31a has a central hole 31g that penetrates the bottom portion 31a in the axial direction. The central hole 31g is, for example, a circular hole centered on the central axis J. The lower portion of the shaft 21 opens into the central hole 31 g.

The outer tube 31b is cylindrical and extends upward from the radially outer peripheral edge of the bottom 31 a. The outer tube 31b is, for example, cylindrical and opens upward around the central axis J. The outer cylindrical portion 31b is located radially outward of the rotor 20a and the stator 20 b. The stator core 23 is fixed to the inner circumferential surface of the outer tube portion 31 b. The flange 31h projects radially outward from the upper end of the outer cylinder 31 b. The flange portion 31h is, for example, annular with the center axis J as the center.

The inner tube portion 31c has a tubular shape extending upward from the bottom portion 31 a. The inner tube portion 31c is, for example, cylindrical and has an upper opening centered on the central axis J. The inner cylindrical portion 31c is located radially inward of the outer cylindrical portion 31 b. The inner cylindrical portion 31c surrounds the central hole 31g when viewed in the axial direction. The upper end of the inner tube 31c is located below the upper end of the outer tube 31 b. The shaft 21 axially opens radially inward of the inner cylindrical portion 31 c. The inner cylindrical portion 31c includes a bearing holding portion 31d, an oil seal holding portion 31e, and a shaft fitting portion 31 f. The bearing holding portion 31d, the oil seal holding portion 31e, and the shaft fitting portion 31f are connected in this order from the upper side toward the lower side.

The bearing 51 is held radially inward of the bearing holding portion 31 d. The upper end of the bearing holding portion 31d is the upper end of the inner tube portion 31 c. The inner diameter of the oil seal holding portion 31e is smaller than the inner diameter of the bearing holding portion 31d, for example. A step is provided between the bearing holder 31d and the oil seal holder 31e on the inner peripheral surface of the inner cylindrical portion 31 c. A wave washer for applying a preload to the bearing 51 is disposed between the step and the axial direction of the bearing 51, for example. An oil seal 80 is held radially inside the oil seal holding portion 31 e.

The oil seal 80 is annular and surrounds the shaft 21. The oil seal 80 is, for example, annular with the center axis J as the center. The oil seal 80 is in contact with the outer peripheral surface of the shaft 21 over the entire circumference. More specifically, the oil seal 80 is in contact with the outer peripheral surface of the large diameter shaft portion 21c over the entire circumference. The oil seal 80 seals between the inner peripheral surface of the oil seal holding portion 31e and the outer peripheral surface of the shaft 21. The oil seal 80 prevents fluid that has flowed into the pump chamber 43, which will be described later, from leaking into the housing main body 31.

The shaft fitting portion 31f is connected to the bottom portion 31 a. The lower end of the shaft fitting portion 31f is the lower end of the inner cylindrical portion 31 c. The shaft 21 is fitted radially inside the shaft fitting portion 31 f. More specifically, the lower end of the large-diameter shaft portion 21c is fitted into the radially inner space of the shaft fitting portion 31 f. The inner diameter of the shaft fitting portion 31f is smaller than the inner diameter of the oil seal holding portion 31e, for example. A step is provided between the oil seal holding portion 31e and the shaft fitting portion 31f on the inner peripheral surface of the inner cylindrical portion 31 c. The inner diameter of the shaft fitting portion 31f is larger than the inner diameter of the central hole 31 g.

The ring member 32 is located on the lower side of the housing main body 31. The annular member 32 is annular and surrounds the center axis J. The outer peripheral edge of the annular member 32 has, for example, a circular shape centered on the central axis J when viewed in the axial direction. As shown in fig. 4, the inner peripheral edge of the annular member 32 has, for example, a circular shape centered on an eccentric axis E that is eccentric in the radial direction with respect to the central axis J when viewed in the axial direction. The eccentric axis E is parallel to the central axis J. As shown in fig. 1, the upper surface of the annular member 32 is in contact with the lower surface of the bottom portion 31 a. The outer diameter of the annular member 32 is, for example, the same as the outer diameter of the bottom portion 31 a.

The pump cover 33 is located below the annular member 32. The pump cover 33 includes a cover body portion 33a, a cover flange portion 33b, and a nozzle portion 33 c. The cover body 33a covers the inside of the annular member 32 from below. The upper surface of the cover body portion 33a contacts the radially inner peripheral edge portion of the lower surface of the annular member 32. The cover body portion 33a has, for example, a cylindrical shape centered on the central axis J. The outer diameter of the cover body 33a is larger than the inner diameter of the annular member 32.

The cover flange portion 33b projects radially outward from the upper end of the cover body portion 33 a. The cover flange portion 33b is, for example, annular with the center axis J as the center. The cover flange portion 33b is, for example, plate-shaped with its plate surface facing in the axial direction. The upper surface of the cover flange portion 33b contacts the radially outer portion of the lower surface of the annular member 32. The upper surface of the cover flange portion 33b and the upper surface of the cover body portion 33a are smoothly continuous, and constitute a flat surface perpendicular to the axial direction.

The outer diameter of the cover flange portion 33b is, for example, the same as the outer diameter of the annular member 32. The cover flange portion 33b is fixed to a lower surface of the annular member 32 by a plurality of bolts 36. The bolt 36 axially penetrates the cover flange portion 33b and the ring member 32, and is screwed into the housing main body 31 from the lower side. Thereby, the ring member 32 and the pump cover 33 are fastened together to the casing main body 31 by the plurality of bolts 36. A plurality of bolts 36 are provided at intervals along the circumferential direction.

As shown in fig. 2, in the present embodiment, the pump chamber 43 is constituted by the housing main body 31, the annular member 32, and the pump cover 33. The pump chamber 43 is a portion that houses an inner rotor 41 and an outer rotor 42, which will be described later, therein. The upper surface of the inner surfaces of the pump chamber 43 is formed by the lower surface of the bottom 31 a. The lower surface 43a of the inner surfaces of the pump chamber 43 is formed by the upper surface of the cover body 33 a. The radially outer surface of the inner surface of the pump chamber 43 is formed by the inner peripheral surface of the annular member 32. As shown in fig. 4, the pump chamber 43 has, for example, a circular shape centered on the eccentric axis E when viewed in the axial direction. As shown in fig. 2, a part of the shaft 21 is inserted into the pump chamber 43. More specifically, a lower portion of the support portion 21d and an upper portion of the torque transmission portion 21e are inserted into the pump chamber 43. In the present embodiment, the shaft 21 axially penetrates the pump chamber 43.

As shown in fig. 1, the nozzle portion 33c protrudes downward from the cover body portion 33 a. The nozzle portion 33c has, for example, a cylindrical shape centered on the central axis J. The outer diameter of the nozzle portion 33c is smaller than the outer diameter of the cap body portion 33 a.

The pump housing 33 has an inlet 34a and an outlet 34 b. The inlet 34a is provided in the cover body portion 33 a. The inlet 34a axially penetrates a portion of the cap body 33a located radially outward of the nozzle portion 33 c. The upper end of the inlet 34a opens into the annular member 32. That is, the upper end of the inlet 34a opens into the pump chamber 43. The outlet 34b is provided across the cover body portion 33a and the nozzle portion 33 c. The outlet 34b has a 1 st channel part 34c and a 2 nd channel part 34 d.

The 1 st flow path portion 34c extends obliquely radially inward from the upper surface of the cover body portion 33a toward the lower side. The upper end of the 1 st flow path portion 34c opens into the annular member 32. That is, the upper end of the outlet 34b opens into the pump chamber 43. The 1 st flow path portion 34c is provided at a position radially sandwiching the center axis J between the inlet 34a and the first flow path portion.

The 2 nd flow path portion 34d extends downward from the lower end of the 1 st flow path portion 34 c. The 2 nd flow path portion 34d extends from the cover body portion 33a to the nozzle portion 33c, and penetrates the nozzle portion 33c in the axial direction. The 2 nd flow path portion 34d has a circular shape centered on the center axis J in a cross section perpendicular to the axial direction, for example. The lower end of the 2 nd flow path portion 34d opens on the lower surface of the nozzle portion 33 c. By providing the 2 nd flow path portion 34d, the nozzle portion 33c is formed in a cylindrical shape centering on the central axis J.

As shown in fig. 2, the pump cover 33 has a concave portion 35 that is recessed from the upper surface of the pump cover 33 toward the lower surface. In the present embodiment, the recess 35 is recessed downward from a portion of the upper surface of the cover body portion 33a that constitutes a part of the inner surface of the pump chamber 43. That is, the recess 35 is provided on the lower surface 43a of the inner surfaces of the pump chamber 43. The inner peripheral edge of the recess 35 has, for example, a circular shape centered on the central axis J when viewed in the axial direction. The recess 35 is located radially between the inlet 34a and the outlet 34 b. The lower end of the shaft 21 is housed in the recess 35. The recess 35 has a large diameter portion 35a and a small diameter portion 35 b.

The large diameter portion 35a is an upper portion of the recess 35. The small diameter portion 35b is a lower portion of the recess 35. The inner diameter of the small diameter portion 35b is smaller than that of the large diameter portion 35 a. A step is provided between the inner circumferential surface of the large diameter portion 35a and the inner circumferential surface of the small diameter portion 35b in the axial direction. The torque transmission portion 21e axially opens into the large diameter portion 35 a. The lower end of the torque transmission portion 21e is inserted into the small diameter portion 35b from above. That is, the lower end of the shaft 21 is inserted into the small diameter portion 35 b. The bottom surface of the small diameter portion 35b is axially opposed to the lower end of the shaft 21 with a gap therebetween. The bottom surface of the small diameter portion 35b is the bottom surface of the recess 35, and is the surface located on the lower side of the inner surface of the recess 35.

As shown in fig. 1, the bus bar unit 60 is located at an upper side of the motor part 20 and the housing 30. The bus bar unit 60 closes the opening of the upper side of the housing main body 31. The bus bar unit 60 has a bus bar holder 61, a bus bar 62, a circuit board 63, and a magnetic sensor 64. The bus bar holder 61 is made of, for example, resin. In the present embodiment, the bus bar holder 61 holds the bearing 52. The bus bar holder 61 has a housing portion that houses the circuit board 63. The circuit board 63 is located on the upper side of the shaft 21. The circuit board 63 has a plate shape with a plate surface facing in the axial direction.

The bus bar 62 is held by the bus bar holder 61. A part of the bus bar 62 is embedded in the bus bar holder 61. The bus bar 62 includes, for example, a bus bar 62 connected to the circuit board 63 and a bus bar 62 electrically connected to the coil 25 of the stator 20 b.

The magnetic sensor 64 is mounted on a lower surface of the circuit board 63. The magnetic sensor 64 is disposed opposite to the upper side of the sensor magnet 70 with a gap therebetween. The magnetic sensor 64 can detect the magnetic field of the sensor magnet 70. The rotation of the rotor 20a can be detected by detecting the magnetic field of the sensor magnet 70 by the magnetic sensor 64. The magnetic sensor 64 is, for example, a magnetoresistive element. The magnetic sensor 64 may be a hall element such as a hall IC.

The pump section 40 is located on the lower side of the motor section 20. The pump section 40 is coupled to the shaft 21. The pump section 40 has an inner rotor 41, an outer rotor 42, and a pump chamber 43. The inner rotor 41 is coupled to the shaft 21. The inner rotor 41 rotates about the center axis J by the rotation of the shaft 21. As shown in fig. 2 and 3, the inner rotor 41 has an inner rotor body portion 41a and a protruding portion 41 b.

The inner rotor body portion 41a is located inside the pump chamber 43. The axial dimension of the inner rotor body 41a is substantially the same as the axial dimension of the pump chamber 43. As shown in fig. 3 and 4, the inner rotor body 41a is a gear having an external gear portion 41c on the outer surface in the radial direction. The external gear portion 41c has a plurality of teeth 41d protruding radially outward. The plurality of teeth 41d are arranged at equal intervals along the circumferential direction over the entire circumference. The tooth profile of the external gear portion 41c is, for example, a trochoid tooth profile. The external shape of the external gear portion 41c is constituted by a trochoid curve, for example, as viewed in the axial direction.

As shown in fig. 3, the protruding portion 41b protrudes from the inner rotor body portion 41a in the axial direction. In the present embodiment, the protruding portion 41b protrudes downward from the lower surface of the inner rotor body 41 a. The protruding portion 41b has, for example, a cylindrical shape centered on the central axis J. The axial dimension of the protruding portion 41b is smaller than the axial dimension of the inner rotor body 41a, for example.

As shown in fig. 2, in the present embodiment, the protruding portion 41b is inserted into the recess 35. More specifically, the protruding portion 41b is inserted into the inside of the large diameter portion 35 a. The outer diameter of the protruding portion 41b is smaller than the outer diameter of the inner rotor body portion 41a and the inner diameter of the large diameter portion 35a, and is larger than the inner diameter of the small diameter portion 35 b. A gap is provided between the outer peripheral surface of the protruding portion 41b and the inner peripheral surface of the large diameter portion 35a in the radial direction, for example, over the entire circumference. The lower surface of the protruding portion 41b is disposed away from the upper side of the upper step surface out of the steps provided between the large diameter portion 35a and the small diameter portion 35 b.

The inner rotor 41 has a hole portion 44 into which a part of the shaft 21 is inserted. The hole portion 44 is recessed from the upper side of the inner rotor 41 toward the lower side. The hole 44 is, for example, a circular hole centered on the central axis J. The hole portion 44 overlaps the central hole 31g when viewed in the axial direction. In the present embodiment, the hole 44 penetrates the inner rotor 41 in the axial direction. More specifically, the hole 44 axially penetrates the inner rotor body 41a and the protruding portion 41 b. That is, in the present embodiment, the hole portion 44 is provided across the inner rotor body portion 41a and the protruding portion 41 b. The lower part of the shaft 21 opens axially into the bore 44. In the present embodiment, the lower end of the shaft 21 protrudes below the inner rotor 41 through the hole 44. The hole 44 includes a fitting hole 44a and a coupling hole 44 b.

In the present embodiment, the fitting hole 44a is an upper portion of the hole 44. The fitting hole 44a is open on the upper side. The upper opening of the fitting hole 44a and the lower opening of the central hole 31g are axially opposed to each other. The fitting hole 44a is provided in the inner rotor body 41 a. The lower end of the fitting hole 44a is located above the lower surface of the inner rotor body 41 a.

The inner diameter of the fitting hole 44a is substantially the same as the inner diameter of the central hole 31g, for example. The inner diameter of the fitting hole 44a is slightly smaller than the inner diameter of the central hole 31g, for example. In the present embodiment, the inner diameter of the fitting hole 44a is smaller than the outer diameter of the protrusion 41 b. In other words, in the present embodiment, the outer diameter of the protruding portion 41b is larger than the inner diameter of the fitting hole 44 a. The support portion 21d is fitted in the fitting hole portion 44 a. Thereby, the support portion 21d supports the inner rotor 41 in the radial direction via the inner peripheral surface of the fitting hole portion 44 a. The support portion 21d is fitted into the fitting hole 44a with a clearance. More specifically, the lower portion of the support portion 21d is loosely fitted into the upper portion of the fitting hole 44 a.

In the present embodiment, the coupling hole 44b is a lower portion of the hole 44. The coupling hole 44b is continuous with the lower side of the fitting hole 44 a. The coupling hole 44b is open on the lower side. In the present embodiment, the coupling hole 44b is provided across the inner rotor body 41a and the protruding portion 41 b. The coupling hole 44b penetrates the protruding portion 41b in the axial direction. By providing the coupling hole 44b, the protruding portion 41b is formed in an annular shape centered on the central axis J. The inner diameter of the coupling hole 44b is smaller than the inner diameter of the fitting hole 44a and the inner diameter of the small diameter portion 35 b. The torque transmission portion 21e is inserted into the coupling hole 44 b. The axial dimension of the coupling hole 44b is smaller than the axial dimension of the fitting hole 44a, for example.

A step 44d is provided between the fitting hole 44a and the coupling hole 44b in the axial direction. The step 44d has a step surface 44e facing the upper side. The step surface 44e is a flat surface perpendicular to the axial direction. The step surface 44e is, for example, annular centered on the central axis J. The stepped surface 44e is located above the lower surface of the inner rotor body 41 a. The step surface 44e is located radially inward of the outer peripheral surface of the protruding portion 41 b.

As shown in fig. 3 and 4, the coupling hole 44b has a plurality of internal teeth 44c on the inner peripheral surface. The inner teeth 44c protrude radially inward. The plurality of inner teeth 44c are arranged at equal intervals along the circumferential direction over the entire circumference. The internal teeth 44c extend in the axial direction. The inner tooth portion 44c extends from an upper end to a lower end of the coupling hole portion 44b, for example. The plurality of inner teeth 44c intermesh with the plurality of outer teeth 21 f. Thereby, the outer teeth portions 21f are circumferentially hooked on the inner teeth portions 44c, and the torque transmission portion 21e of the shaft 21 is coupled to the coupling hole portion 44b around the central axis J. Thus, in the present embodiment, the torque transmission portion 21e can transmit torque to the inner rotor 41 via the external teeth portions 21f and the internal teeth portions 44 c. Therefore, the inner rotor 41 rotates about the central axis J in accordance with the rotation of the shaft 21 about the central axis J.

In the present embodiment, the coupling hole 44b is a spline hole. That is, in the present embodiment, the shaft 21 and the inner rotor 41 are coupled by spline coupling in which the torque transmission portion 21e as a spline shaft portion is engaged with the coupling hole portion 44b as a spline hole portion.

In the present specification, the phrase "the torque transmission portion is coupled to the coupling hole portion around the central axis" means that the torque transmission portion can transmit the torque around the central axis to the inner rotor through the coupling hole portion when the torque transmission portion rotates around the central axis. In the present specification, the phrase "the torque transmission portion is coupled to the coupling hole portion around the central axis" means that the torque transmission portion and the coupling hole portion include portions that can contact each other in a circumferential direction around the central axis. In the present embodiment, the plurality of outer teeth portions 21f and the plurality of inner teeth portions 44c can contact in the circumferential direction around the central axis J.

As shown in fig. 2, outer rotor 42 is located within pump chamber 43. The outer rotor 42 surrounds the inner rotor 41. The outer rotor 42 is located radially outward of the inner rotor 41. As shown in fig. 4, the outer rotor 42 has a ring shape centered on the eccentric axis E. That is, outer rotor 42 and pump chamber 43 are coaxially arranged. The outer rotor 42 is fitted in the pump chamber 43. The outer rotor 42 is disposed in the pump chamber 43 so as to be rotatable about the eccentric axis E.

The outer rotor 42 is a gear having an internal gear portion 42a on the radially inner side surface. The internal gear portion 42a has a plurality of teeth 42b protruding radially inward. The plurality of teeth 42b are arranged at equal intervals along the circumferential direction over the entire circumference. The tooth profile of the internal gear portion 42a is, for example, a trochoid tooth profile. The inner edge of the internal gear portion 42a is constituted by a trochoid curve, for example, as viewed in the axial direction. The internal gear portion 42a meshes with the external gear portion 41 c. More specifically, the tooth 41d of the external gear portion 41c and the tooth 42b of the internal gear portion 42a mesh with each other in a part of the circumferential direction. Thereby, the outer rotor 42 meshes with the inner rotor 41.

When the inner rotor 41 is rotated about the center axis J by the shaft 21, torque is transmitted to the outer rotor 42 via the outer gear portion 41c and the inner gear portion 42a, and the outer rotor 42 is rotated about the eccentric axis E. Thereby, the fluid is sucked from the inlet 34a into the gap between the external gear portion 41c and the internal gear portion 42a in the pump chamber 43. The fluid sucked in is transported in the circumferential direction along with the rotation of the inner rotor 41 and the outer rotor 42, and is discharged from the outlet 34 b. In this way, the pump section 40 can transport fluid from the inlet 34a to the outlet 34 b.

According to the present embodiment, the shaft 21 has the support portion 21d that supports the inner rotor 41 in the radial direction about the central axis J, and the hole portion 44 of the inner rotor 41 has the fitting hole portion 44a, and the support portion 21d is fitted inside the fitting hole portion 44 a. Therefore, the inner rotor 41 can be positioned in the radial direction by the support portion 21d which is a part of the shaft 21. Thereby, the inner rotor 41 can be positioned in the radial direction with respect to the shaft 21 regardless of the dimensional accuracy of the housing 30, the assembly accuracy of the housing 30, and the like. Further, since the inner rotor 41 can be directly positioned in the radial direction by the shaft 21, the shaft 21 and the inner rotor 41 can be arranged with high shaft accuracy as compared with a case where a portion for positioning the inner rotor 41 is provided in another member such as the housing 30. This can improve the shaft accuracy of the inner rotor 41 with respect to the shaft 21. Therefore, torque can be appropriately transmitted to the inner rotor 41 through the torque transmission portion 21e of the shaft 21. This enables the electric pump 10 to be driven efficiently.

Further, due to the pressure of the fluid or the like, a relatively large force is easily applied to a portion supporting the inner rotor 41 in the radial direction. Therefore, in order to support the inner rotor 41 in the radial direction by a member other than the shaft 21, it is necessary to form the other member by a material having a relatively high strength. Specifically, for example, when a column portion protruding upward is provided in the pump cover 33 and the inner rotor 41 is radially supported by inserting the column portion into a hole provided in the inner rotor 41, the pump cover 33 needs to be made of a relatively high-strength material.

In contrast, according to the present embodiment, since the member supporting the inner rotor 41 in the radial direction is the shaft 21, it is possible to manufacture the other members than the shaft 21 from a material having relatively low strength. Specifically, for example, since it is not necessary to support the inner rotor 41 in the radial direction by the pump cover 33, the pump cover 33 can be made of a material having relatively low strength such as aluminum or resin. This can improve the degree of freedom in designing the pump cover 33.

For example, when the shaft 21 is press-fitted into a hole of the inner rotor 41 to fix the inner rotor 41 and the shaft 21, the inner rotor 41 can be positioned in the radial direction by the shaft 21 through the hole into which the shaft 21 is press-fitted, and torque can be transmitted from the shaft 21 to the inner rotor 41. However, in this case, the maximum torque that can be transmitted from the shaft 21 to the inner rotor 41 tends to be small. Further, since the shaft 21 needs to be press-fitted into the hole, the assembling performance of the electric pump 10 is easily lowered.

In contrast, according to the present embodiment, the shaft 21 is provided with a torque transmission portion 21e for transmitting torque to the inner rotor 41 and a support portion 21d for positioning the inner rotor 41. Thus, the inner rotor 41 can be positioned by the support portion 21d, and therefore, the inner rotor 41 does not need to be positioned in the torque transmission portion 21 e. Therefore, the torque transmission portion 21e does not need to be press-fitted into the inner rotor 41, and a connection method in which the maximum torque that can be transmitted is larger than the press-fitting can be adopted as a connection method of the torque transmission portion 21e and the inner rotor 41. Thereby, the inner rotor 41 can be appropriately positioned in the radial direction via the support portion 21d, and the torque transmittable from the shaft 21 to the inner rotor 41 can be increased. Further, by simply inserting the shaft 21 into the hole 44, unlike the press-fitting, the inner rotor 41 is easily positioned in the radial direction with respect to the shaft 21, and the shaft 21 and the inner rotor 41 are easily coupled. Therefore, the assembling property of the electric pump 10 can be improved. Unlike the press-fitting, the fluid flowing into the pump chamber 43 easily enters the radial gap between the shaft 21 and the inner rotor 41. Therefore, when the fluid is oil, for example, the impact or the like when the shaft 21 contacts the inner rotor 41 can be buffered by the fluid.

Further, according to the present embodiment, the torque transmission portion 21e has a plurality of external teeth portions 21f on the outer peripheral surface, and the coupling hole portion 44b has a plurality of internal teeth portions 44c on the inner peripheral surface, which mesh with the plurality of external teeth portions 21 f. Therefore, by meshing the plurality of external teeth portions 21f with the plurality of internal teeth portions 44c, torque can be appropriately transmitted from the shaft 21 to the inner rotor 41. Therefore, the maximum torque that can be transmitted from the shaft 21 to the inner rotor 41 can be appropriately increased.

Further, according to the present embodiment, the inner rotor 41 has an inner rotor body portion 41a and a protruding portion 41b protruding from the inner rotor body portion 41a in the axial direction. The hole 44 is provided across the inner rotor body 41a and the protrusion 41 b. Therefore, the axial dimension of the hole 44 can be increased by the amount of the protrusion 41b without increasing the axial dimension of the inner rotor body 41 a. Thus, even if a part of the hole 44 is the fitting hole 44a, the axial dimension of the coupling hole 44b can be easily secured. Therefore, the inner rotor 41 can be appropriately coupled to the shaft 21 through the coupling hole 44 b. Therefore, torque can be easily transmitted from the shaft 21 to the inner rotor 41 via the torque transmission portion 21 e.

Further, according to the present embodiment, the fitting hole 44a is provided in the inner rotor body 41a, and the coupling hole 44b is provided across the inner rotor body 41a and the protruding portion 41 b. Therefore, the boundary between the fitting hole 44a and the coupling hole 44b is located above the surface on which the protruding portion 41b is provided, i.e., the lower surface of the inner rotor body 41 a. Specifically, in the present embodiment, the stepped surface 44e, which is the boundary between the fitting hole 44a and the coupling hole 44b, is disposed above the lower surface of the inner rotor body 41 a. Thus, compared to the case where the stepped surface 44e is located at the same position in the axial direction as the lower surface of the inner rotor body 41a or at a position below the lower surface of the inner rotor body 41a, the connecting portion between the inner rotor body 41a and the protruding portion 41b is easily made thick. Therefore, the rigidity of the inner rotor 41 can be improved.

In the present embodiment, the inner diameter of the coupling hole 44b is smaller than the inner diameter of the fitting hole 44a, and the outer diameter of the torque transmission portion 21e is smaller than the outer diameter of the support portion 21 d. Therefore, an assembly method can be adopted in which the torque transmission portion 21e is provided at the lower end portion of the shaft 21 and inserted into the hole portion 44 from above. Further, since the torque transmission portion 21e can be provided at the lower end portion of the shaft 21, the torque transmission portion 21e can be easily manufactured by machining or the like, as compared with a case where the torque transmission portion 21e is provided at an axially intermediate portion of the shaft 21.

In addition, according to the present embodiment, the outer diameter of the protruding portion 41b is larger than the inner diameter of the fitting hole 44 a. Therefore, compared to the case where the outer diameter of the protruding portion 41b is equal to or smaller than the inner diameter of the fitting hole portion 44a, the connecting portion between the inner rotor body portion 41a and the protruding portion 41b is easily made thick. Therefore, the rigidity of the inner rotor 41 can be further improved.

In addition, according to the present embodiment, the recess 35 that accommodates the protruding portion 41b therein is provided on the lower surface of the inner surface of the pump chamber 43. Therefore, the protruding portion 41b protruding in the axial direction can be avoided by the recess 35. Thus, even if the projection 41b is provided, the axial dimension of the pump chamber 43 does not need to be increased. Therefore, the entire electric pump 10 can be prevented from being enlarged in the axial direction.

In addition, according to the present embodiment, the concave portion 35 has: a large diameter portion 35a into which the protruding portion 41b is inserted; and a small diameter portion 35b into which a lower end portion of the shaft 21 is inserted, the small diameter portion 35b having an inner diameter smaller than that of the large diameter portion 35 a. Therefore, the lower end portion of the shaft 21 and the protruding portion 41b are easily avoided by the recessed portion 35, and the area where the recessed portion 35 is provided is easily reduced. This makes it easy to suppress a decrease in rigidity of the member provided with the recess 35, that is, the pump cover 33 in the present embodiment. In particular, when the recess 35 is provided between the inlet 34a and the outlet 34b as in the present embodiment, the thickness between the inlet 34a and the recess 35 and between the outlet 34b and the recess 35 can be increased. Therefore, even if the inlet 34a, the outlet 34b, and the recess 35 are provided in the pump cover 33, a decrease in rigidity of the pump cover 33 can be suppressed.

Further, according to the present embodiment, the torque transmission portion 21e protrudes downward from the inner rotor 41 through the hole portion 44, and the lower end portion of the torque transmission portion 21e has the tapered portion 21g whose outer diameter decreases downward. By providing the tapered portion 21g at the lower end of the torque transmission portion 21e, the torque transmission portion 21e can easily pass through the hole 44 from above. Therefore, the assembling property of the electric pump 10 can be improved. Further, since the outer diameter of the torque transmission portion 21e is reduced in the tapered portion 21g, the tapered portion 21g may be difficult to be appropriately coupled to the coupling hole portion 44 b. Specifically, in the present embodiment, the lower end portions of the external teeth portions 21f may be difficult to mesh with the internal teeth portions 44c because the protruding height of the lower end portions of the external teeth portions 21f is low. In contrast, according to the present embodiment, since the portion where the tapered portion 21g is provided can be made to protrude downward from the inner rotor 41, the torque transmission portion 21e and the coupling hole portion 44b can be appropriately coupled even when the tapered portion 21g is provided. Therefore, torque can be easily transmitted from the shaft 21 to the inner rotor 41 via the torque transmission portion 21 e.

The present invention is not limited to the above embodiment, and other structures and other methods may be adopted within the scope of the technical idea of the present invention. The method of connecting the torque transmission part and the coupling hole part around the central axis is not particularly limited. The torque transmission portion and the coupling hole portion may be coupled around the central axis by providing flat surfaces facing each other on the torque transmission portion and the coupling hole portion, respectively. In this case, the torque transmission portion and the coupling hole portion may be coupled around the central axis by the D-notch portion, for example. The outer diameter of the support portion and the outer diameter of the torque transmission portion are not particularly limited. The torque transmission portion may have an outer diameter larger than that of the support portion. The outer diameter of the torque transmission portion and the outer diameter of the support portion may be the same.

The axial positions of the support portion and the torque transmission portion are not particularly limited. In the above embodiment, the axial positions of the support portion 21d and the torque transmission portion 21e may be reversed. That is, the support portion 21d may be located below the torque transmission portion 21 e. In this case, the outer diameter of the support portion 21d may be smaller than the outer diameter of the torque transmission portion 21e, and the inner diameter of the fitting hole may be smaller than the inner diameter of the coupling hole. The shaft may have another portion between the support portion and the torque transmission portion in the axial direction. The torque transmitting portion may not have a tapered portion. The axial dimension of the support portion and the axial dimension of the torque transmission portion are not particularly limited. The axial dimension of the support portion and the axial dimension of the torque transmission portion may be the same as each other. The axial dimension of the support portion may be smaller than the axial dimension of the torque transmission portion.

The fitting hole may be provided across the inner rotor body and the protruding portion, and the coupling hole may be provided in the protruding portion. The fitting hole may be provided across the inner rotor body and the protruding portion, and the coupling hole may be provided in the inner rotor body. The fitting hole and the coupling hole may be provided without crossing the inner rotor body and the protruding portion. That is, the fitting hole portion may be provided in one of the inner rotor body portion and the protruding portion, and the coupling hole portion may be provided in the other of the inner rotor body portion and the protruding portion. The outer diameter of the protruding portion may be the same as the inner diameter of the fitting hole portion, or may be smaller than the inner diameter of the fitting hole portion. The inner rotor may also have no protrusions.

The dimension in the axial direction of the fitting hole and the dimension in the axial direction of the coupling hole are not particularly limited. The dimension in the axial direction of the fitting hole and the dimension in the axial direction of the coupling hole may be the same. The dimension in the axial direction of the fitting hole may be smaller than the dimension in the axial direction of the coupling hole. The hole provided in the inner rotor may not axially penetrate the inner rotor. That is, the hole portion may be a hole having a bottom. The hole may have another portion between the fitting hole and the coupling hole in the axial direction. The inner diameter of the recess provided in the inner surface of the pump chamber may be uniform over the entire axial range. The recess may not be provided.

The use of the electric pump to which the present invention is applied is not particularly limited. The electric pump may be mounted on a device other than the vehicle. The fluid to be delivered by the electric pump is not particularly limited, and may be water, for example. The respective structures and the respective methods described above in the present specification can be appropriately combined within a range not inconsistent with each other.

Claims

1. An electric pump is characterized in that the pump is provided with a pump body,

the electric pump comprises:

a motor unit having a shaft rotatable about a central axis extending in an axial direction; and

a pump section located on one axial side of the motor section and coupled to the shaft,

the pump section includes:

an inner rotor coupled to the shaft; and

an outer rotor surrounding and meshing with the inner rotor,

the inner rotor has a hole portion into which a portion of the shaft is inserted,

the shaft has:

a support portion that supports the inner rotor in a radial direction centered on the central axis; and

a torque transmission portion that transmits torque to the inner rotor,

the hole portion has:

a fitting hole portion into which the support portion is fitted; and

and a coupling hole portion into which the torque transmission portion is inserted and which is coupled to the coupling hole portion around the central axis.

2. The electric pump of claim 1,

the torque transmission part has a plurality of external teeth parts on an outer peripheral surface,

the coupling hole has a plurality of internal teeth portions on an inner peripheral surface thereof, the internal teeth portions meshing with the plurality of external teeth portions.

3. The electric pump of claim 1,

the inner rotor has:

an inner rotor body portion; and

a protrusion protruding from the inner rotor body in an axial direction,

the hole is provided across the inner rotor body and the protruding portion.

4. The electric pump of claim 3,

the fitting hole portion is provided in the inner rotor body portion,

the coupling hole portion is provided across the inner rotor body portion and the protruding portion.

5. The electric pump of claim 4,

the inner diameter of the connecting hole is smaller than the inner diameter of the fitting hole,

the torque transmission portion has an outer diameter smaller than an outer diameter of the support portion.

6. The electric pump of claim 5,

the outer diameter of the protruding portion is larger than the inner diameter of the fitting hole portion.

7. The electric pump of claim 3,

the pump section has a pump chamber that houses the inner rotor and the outer rotor therein,

a recess is provided on one of the inner side surfaces of the pump chamber in the axial direction, and the recess accommodates the protruding portion therein.

8. The electric pump of claim 7,

the hole portion penetrates the inner rotor in the axial direction,

an end portion of the shaft on one axial side protrudes to one axial side than the inner rotor and is accommodated inside the recess,

the recess has:

a large diameter portion into which the protruding portion is inserted; and

and a small diameter portion into which an end portion of the shaft on one side in the axial direction is inserted, the small diameter portion having an inner diameter smaller than an inner diameter of the large diameter portion.

9. The electric pump according to any one of claims 1 to 8,

the hole portion penetrates the inner rotor in the axial direction,

the torque transmission part is positioned on one side in the axial direction than the support part and protrudes to one side in the axial direction than the inner rotor through the hole part,

the torque transmission portion has a tapered portion at an end portion on one side in the axial direction, and the tapered portion has an outer diameter that decreases toward the one side in the axial direction.