CN217282554U - Electric actuator - Google Patents

Abstract

The utility model provides an electric actuator, this electric actuator has: the bus bar holder includes a motor portion, a bus bar holder, a circuit board, and a case that houses the motor portion, the bus bar holder, and the circuit board. The housing has: an inner side surface surrounding the stator from a radially outer side; a 1 st bearing surface located on the other axial side of the inner side surface and facing the one axial side; and a 2 nd bearing surface located on one axial side of the inner side surface and facing the one axial side. The stator is axially sandwiched between the busbar holder and the 1 st bearing surface. The circuit board is axially fixed to the 2 nd support surface. The bus bar holder is sandwiched between the circuit board and the 2 nd bearing surface in the axial direction.

Description

Electric actuator

Technical Field

The utility model relates to an electric actuator.

Background

An electric actuator is known in which a plurality of components such as a motor portion having a rotor and a stator, a circuit board, and a bus bar are housed in a case. For example, patent document 1 discloses the following structure: the stator of the motor portion is fixed to the inner peripheral surface of the housing tube portion on one side with respect to the wall portion of the housing, and the circuit board is housed in a control board housing portion formed in the housing on the other side of the wall portion of the housing.

Patent document 1: japanese patent laid-open No. 2020 and 5431

In the above-described structure, it is necessary to assemble the stator, the circuit board, the bus bar, and the like separately to the housing, and there is a problem that assembling takes time. Further, while a motor unit represented by a stator is assembled from one side with respect to a wall portion of the housing, the circuit board needs to be assembled from the other side with respect to the wall portion of the housing. Therefore, the case needs to be turned over in the middle of the assembly process, which also causes a problem of labor-consuming assembly.

SUMMERY OF THE UTILITY MODEL

In view of the above, an object of the present invention is to provide an electric actuator capable of simplifying an assembly process.

One embodiment of the electric actuator of the present invention includes: a motor unit having a rotor rotatable about a central axis extending in an axial direction and a stator surrounding the rotor from a radially outer side; a bus bar electrically connected with the stator; a bus bar holder which is arranged on one side in the axial direction of the motor part and holds the bus bar; a circuit board that is disposed along a plane perpendicular to the central axis on one axial side of the bus bar holder, and that is electrically connected to the bus bar; and a case that houses the motor portion, the bus bar holder, and the circuit board, the case having: an inner side surface surrounding the stator from a radially outer side; a 1 st bearing surface located on the other axial side of the inner side surface and facing the one axial side; and a 2 nd bearing surface located on one axial side of the inner side surface and facing the one axial side, the stator being sandwiched between the bus bar holder and the 1 st bearing surface in the axial direction, the circuit board being fixed to the 2 nd bearing surface in the axial direction; the bus bar holder is sandwiched between the circuit board and the 2 nd bearing surface in the axial direction.

In the electric actuator according to the above aspect, the bus bar holder includes: a holder main body made of a resin material; and a collar member that is embedded in the holder body in an axial direction, wherein the bus bar holder is in contact with the circuit board at one axial end surface of the collar member, is in contact with the 2 nd support surface at the other axial end surface of the collar member, and a screw that fastens the circuit board to the 2 nd support surface is inserted into the collar member.

In the electric actuator according to the above aspect, the outer peripheral surface of the stator is provided with a recessed groove extending in the axial direction and opening to one axial side, the bus bar holder has a cylindrical portion surrounding the outer peripheral surface of the stator, and the inner peripheral surface of the cylindrical portion is provided with the raised strip portion inserted into the recessed groove.

In the electric actuator according to the above aspect, the electric actuator includes a magnetic sensor that detects a magnetic field of the magnet of the rotor, and the bus bar holder includes a magnetic sensor holding portion that holds the magnetic sensor.

In the electric actuator according to the above aspect, the electric actuator includes a speed reduction mechanism that is connected to the rotor on the other axial side of the motor unit and reduces the speed of the power of the rotor, and the case houses the speed reduction mechanism.

According to an aspect of the present invention, in the electric actuator, the assembly process can be simplified.

Drawings

Fig. 1 is a sectional view showing an electric actuator according to the present embodiment.

Fig. 2 is a sectional view showing the electric actuator according to the present embodiment, and is a sectional view taken along line II-II in fig. 1.

Fig. 3 is an exploded view showing a part of the electric actuator of the present embodiment.

Description of the reference symbols

1: an electric actuator; 10: a housing; 11: the 1 st bearing surface; 12: a 2 nd bearing surface; 14: an inner side surface; 20: a motor section; 22: a rotor; 23: a stator; 24 b: an outer peripheral surface; 27: a groove; 30: a speed reduction mechanism; 40: a magnet; 63: a magnetic sensor; 70: a circuit board; 140: a bus bar holder; 141: a cylindrical portion; 142: a raised strip portion; 143: a collar member; 143 f: an end face; 143g of: an end face; 144: a screw; 145: a magnetic sensor holding unit; 148: a holder body; 150: a bus bar; j1: a central axis.

Detailed Description

Hereinafter, an electric actuator according to an embodiment of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and may be arbitrarily changed within the scope of the technical idea of the present invention. In the drawings below, in order to facilitate understanding of each structure, the actual structure may be different from the scale, the number, and the like of each structure.

In each figure, the Z-axis direction is a vertical direction in which the positive side is an upper side and the negative side is a lower side. The axial direction of the center axis J1 shown in the drawings is parallel to the Z-axis direction, i.e., the vertical direction. In the following description, unless otherwise specified, a direction parallel to the axial direction of the central axis J1 will be simply referred to as an "axial direction". Unless otherwise specified, a radial direction about the central axis J1 is simply referred to as a "radial direction", and a circumferential direction about the central axis J1 is simply referred to as a "circumferential direction".

In the present embodiment, the upper side corresponds to one axial side, and the lower side corresponds to the other axial side. The upper side and the lower side are only names for describing the relative positional relationship of the respective parts, and the actual arrangement relationship may be an arrangement relationship other than the arrangement relationship indicated by these names.

The electric actuator 1 of the present embodiment shown in fig. 1 to 3 is, for example, an electric actuator mounted on a vehicle. As shown in fig. 1 and 3, the electric actuator 1 includes a housing 10, a partition member 15, a cover member 80, a motor unit 20 having a motor shaft 21 that rotates about a central axis J1, a 1 st bearing 53, a 2 nd bearing 51, a 3 rd bearing 52, a speed reduction mechanism 30, an output shaft 41, a magnetic sensor 63, a circuit board 70, a bus bar holder 140, and a bus bar 150.

As shown in fig. 1, the case 10 houses the partition member 15, the motor section 20, the motor shaft 21, the speed reduction mechanism 30, the output shaft 41, the magnetic sensor 63, the circuit board 70, the bus bar holder 140, and the bus bar 150. The housing 10 has an opening portion opened to the upper side.

The housing 10 is cylindrical and extends in the axial direction around a central axis J1. The housing 10 includes a substrate housing portion 13a, a housing tube portion 13b, an output portion housing portion 13c, and a bearing holding portion 13 d. The board housing portion 13a is a portion that houses the circuit board 70 and the bus bar holder 140. The substrate accommodating portion 13a is open to the upper side. The substrate accommodating portion 13a is formed radially inside the upper portion of the housing 10. The bottom surface of the substrate accommodating portion 13a is the 2 nd support surface 12 for supporting and fixing the circuit board 70 and the bus bar holder 140. The 2 nd bearing surface 12 faces upward.

The housing cylindrical portion 13b surrounds the radial outside of the motor portion 20. The output unit housing portion 13c is a portion that houses an output unit 46 described later. The bearing holding portion 13d holds the 2 nd bearing 51. The bearing holding portion 13d extends upward from the lower end portion of the housing 10 around the center axis J1.

The cover member 80 covers the opening of the housing 10 and is fixed to the housing 10. The lid member 80 is a container-shaped member having a recess 16a that opens downward. The cover member 80 and the housing 10 are fastened by a plurality of bolts 201 (see fig. 3) that penetrate the cover member 80 in the axial direction. In the present embodiment, the cover member 80 corresponds to a cover portion that covers the opening of the housing 10 from above. The cover member 80 has a bearing holding portion 16 b. The bearing holding portion 16b holds the 1 st bearing 53. The bearing holding portion 16b extends downward around the center axis J1.

The central axis of the motor portion 20 is a central axis J1. As shown in fig. 1, the motor unit 20 includes a rotor 22 and a stator 23. The rotor 22 includes a motor shaft 21, a rotor core 22a, and a magnet 40.

The motor shaft 21 has a 1 st shaft portion 21a, a 2 nd shaft portion 21b, and a through hole 25. The 1 st shaft portion 21a extends in the axial direction and is located above the motor shaft 21. The 2 nd shaft portion 21b extends in the axial direction and is located below the motor shaft 21. The diameter of the 2 nd shaft portion 21b is larger than the diameter of the 1 st shaft portion 21 a. More specifically, the outer diameter of the 2 nd shaft portion 21b is larger than the outer diameter of the 1 st shaft portion 21 a. The 2 nd shaft portion 21b is an eccentric shaft portion centered on an eccentric axis J2 eccentric with respect to the central axis J1. The eccentric axis J2 is parallel to the central axis J1. The through hole 25 extends around the center axis J1. Therefore, the 1 st shaft portion 21a is cylindrical and extends around the central axis J1. The 2 nd shaft portion 21b has an axial recess 26 on the lower side. The recess 26 extends centered on the eccentric axis J2. Therefore, the 2 nd shaft portion 21b is cylindrical and extends about the eccentric axis J2. The upper side of the recess 26 is connected to the lower side of the through hole 25. The 2 nd shaft portion 21b of the motor shaft 21 is supported by the 3 rd bearing 52 so as to be rotatable about the eccentric axis J2.

The rotation of the motor shaft 21 is transmitted to the output shaft 41 via the speed reduction mechanism 30. The output shaft 41 has a shaft portion 41a and a coupling portion 42. The shaft 41a is located on the upper side, and the coupling portion 42 is located on the lower side. The shaft portion 41a is cylindrical and extends around a central axis J1. The upper side of the shaft portion 41a passes through the through hole 25 of the motor shaft 21. The upper end of the shaft portion 41a protrudes upward from the motor shaft 21. The upper end of the shaft portion 41a protruding upward of the motor shaft 21 is supported by the 1 st bearing 53 to be rotatable about the center axis J1. The upper end of the motor shaft 21 is supported by the cover member 80 via the 1 st bearing 53.

The lower end of the coupling portion 42 protrudes downward of the motor shaft 21. The lower end of the coupling portion 42 projecting downward of the motor shaft 21 is supported by the 2 nd bearing 51 so as to be rotatable about the central axis J1. The lower end of the motor shaft 21 is supported by the housing 10 via a 2 nd bearing 51. The axial end portion of the output shaft 41 is supported by the 1 st bearing 53 and the 2 nd bearing 51 so as to be rotatable about the center axis J1. Therefore, the motor shaft 21, in which the shaft portion 41a of the output shaft 41 passes through the through hole 25, is supported by the shaft portion 41a so as to be rotatable about the center axis J1.

The 1 st bearing 53, the 2 nd bearing 51, and the 3 rd bearing 52 are rolling bearings each having an inner ring and an outer ring located radially outward of the inner ring. In the present embodiment, the 1 st bearing 53, the 2 nd bearing 51, and the 3 rd bearing 52 are, for example, ball bearings in which an inner ring and an outer ring are coupled via a plurality of balls.

The upper side of the coupling portion 42 is inserted into the recess 26 of the motor shaft 21. The axial length of the output shaft 41 can be shortened by inserting the upper side of the coupling portion 42 into the recess 26 of the motor shaft 21. Therefore, the axial length of the electric actuator 1 can be shortened to achieve miniaturization.

The coupling portion 42 has a cylindrical tube portion 44 extending about the central axis J1. The cylindrical portion 44 has a coupling recess 45 in an inner diameter. The coupling recess 45 is recessed upward from the lower end of the output shaft 41. The coupling recess 45 is substantially circular when viewed in the axial direction, centered on the central axis J1. A plurality of spline grooves are provided in the circumferential direction on the inner circumferential surface of the coupling recess 45. Other members that output the driving force of the electric actuator 1 are inserted into and coupled to the coupling recess 45. The other component is for example a manual axle in a vehicle. The electric actuator 1 drives the manual shaft based on a shift operation by the driver, thereby switching the gears of the vehicle.

Since the coupling portion 42 has the coupling recess 45 recessed upward, the axial length of the output shaft 41 can be shortened as compared with a case where the coupling portion 42 is in a shaft shape protruding downward. Therefore, the axial length of the electric actuator 1 can be shortened and the size can be reduced. The 1 st bearing 53 is held by the bearing holding portion 16b provided in the housing 10, and the 2 nd bearing 51 is held by the bearing holding portion 13d provided in the housing 10, whereby the coaxiality of the output shaft 41 with respect to the center axis J1 can be improved. Since the 1 st bearing 53 is held by the bearing holding portion 16b provided in the housing 10 and the 2 nd bearing 51 is held by the bearing holding portion 13d provided in the housing 10, it is not necessary to separately provide a member for holding the 1 st bearing 53 and the 2 nd bearing 51, which contributes to cost reduction and downsizing of the electric actuator 1.

The rotor core 22a is fixed to the outer peripheral surface of the motor shaft 21. More specifically, the rotor core 22a is fixed to the outer peripheral surface of the 1 st shaft portion 21 a. Magnet 40 is fixed to the radial outside of rotor core 22 a. The plurality of magnets 40 are arranged at intervals in the circumferential direction.

The stator 23 is located radially outside the rotor 22. The stator 23 has a stator core 23a, a plurality of coils 23b, and an insulator 29. The stator core 23a is annular and surrounds the rotor 22 radially outward. The outer core peripheral surface 24a of the stator core 23a is fixed to the inner surface 14 of the case tube portion 13 b. In other words, the inner surface 14 of the casing 10 surrounds the stator 23 from the radially outer side.

The plurality of coils 23b are attached to the teeth 23t (see fig. 2) of the stator core 23a via the insulator 29.

As shown in fig. 2, the stator 23 has an outer peripheral surface 24b at a position radially inward of the core outer peripheral surface 24 a. The outer peripheral surface 24b is a surface of the insulator 29 facing radially outward. The outer peripheral surface 24b is disposed for each magnetic pole. The outer peripheral surface 24b is perpendicular to the magnetic pole center in the circumferential direction when viewed in the axial direction. A concave groove 27 recessed radially inward is provided on the outer peripheral surface 24b of the stator 23. The groove 27 extends continuously in the axial direction. The grooves 27 are respectively arranged on the upper and lower sides of the core outer peripheral surface 24a of the stator core 23 a. The groove 27 extends in the axial direction and is open to one axial side. The plurality of grooves 27 are arranged at intervals in the circumferential direction.

As shown in fig. 1, the peripheral edge portion of the stator core 23a is supported by the peripheral wall portion 15b of the partition member 15 from below. The peripheral edge portion of the stator core 23a contacts the peripheral wall portion 15b of the partition member 15 from one axial side.

The partition member 15 is disposed on the other axial side of the motor unit 20. The partition member 15 is disposed between the stator 23 and the reduction mechanism 30 in the axial direction. The partition member 15 has a circular plate shape. The peripheral wall portion 15b extends from the outer peripheral portion of the partition member 15 to one axial side. The outer peripheral portion of the partition member 15 contacts the 1 st support surface 11 of the housing 10 from one axial side. The 1 st bearing surface 11 is located on the other axial side of the inner side surface 14. The 1 st bearing surface 11 faces one side in the axial direction.

The bus bar holder 140 is disposed above the rotor 22. The bus bar holder 140 is disposed on one axial side of the motor unit 20. The bus bar holder 140 has a circular ring plate shape. The busbar holder 140 has a holder main body 148 and a collar member 143. The holder main body 148 is made of an insulating resin material. The holder body 148 of the confluence holder 140 has a flange portion 140f that expands radially outward from a cylindrical portion 141 described later. The flange portion 140f of the bus bar holder 140 contacts the No. 2 bearing surface 12 of the housing 10 from the axial direction side. The 2 nd bearing surface 12 is located on one axial side of the inner side surface 14. The 2 nd bearing surface 12 faces one side in the axial direction.

The collar member 143 has a cylindrical shape extending in the axial direction. The collar member 143 is embedded in the flange portion 140f of the holder main body 148 in an axial direction. The collar member 143 protrudes toward the upper side of the bus bar holder 140. An end surface 143f on one axial side of the collar member 143 contacts the lower side of the circuit board 70. The other axial end surface 143g of the collar member 143 contacts the 2 nd bearing surface 12. Thereby, the bus bar holder 140 is sandwiched between the circuit board 70 and the 2 nd support surface 12 in the axial direction.

A screw 144 for fastening the circuit board 70 to the 2 nd support surface 12 is inserted into the collar part 143. The bus bar holder 140 and the circuit board 70 are screwed to the No. 2 support surface 12 of the housing 10 by screws 144 penetrating the circuit board 70 and the collar member 143 from the upper side. The screws 144 are provided with, for example, four. The bus bar holder 140 and the circuit board 70 are screwed by screws 144 from the upper side at positions overlapping the collar member 143 when viewed in the axial direction. The circuit board 70 is fastened axially to the 2 nd support surface 12 by screws 144. The circuit board 70 after the screw fastening is disposed above the bus bar holder 140 with a gap. The size of the gap between the circuit board 70 and the bus bar holder 140 is the size of the collar member 143 protruding toward the upper side of the bus bar holder 140.

The busbar holder 140 has a cylindrical portion 141 extending downward. The cylindrical portion 141 is located radially outward of the outer peripheral surface 24b of the stator 23. The cylindrical portion 141 surrounds the outer peripheral surface 24b of the stator 23. The cylindrical portion 141 is located radially inward of the core outer peripheral surface 24a of the stator 23. The lower end of the cylindrical portion 141 contacts the upper side of the stator 23 when the bus bar holder 140 is screwed to the 2 nd support surface 12.

When the bus bar holder 140 is screwed to the 2 nd support surface 12 of the housing 10, the lower end of the cylindrical portion 141 contacts the upper side of the stator 23, and the stator 23 is axially sandwiched between the bus bar holder 140 and the 1 st support surface 11. The stator 23 supported by the partition member 15 from the lower side is positioned and fixed to the housing 10 in the axial direction.

As shown in fig. 2, the cylindrical portion 141 of the busbar holder 140 has a raised strip 142. The ridge 142 protrudes radially inward on the inner circumferential surface of the cylindrical portion 141. The raised strip 142 extends in the axial direction. The circumferential position of the raised strip portion 142 is the same as the circumferential position of the groove 27 of the stator 23. The raised strip 142 is diametrically opposed to the groove 27. The ridge 142 protruding radially inward of the cylindrical portion 141 is inserted into the groove 27 above the core outer circumferential surface 24 a. The bus bar holder 140, in which the raised strip 142 is inserted into the groove 27, is positioned circumferentially with the stator 23. When the busbar holder 140 is accommodated in the board accommodating portion 13a while the raised strip 142 is inserted from above into the concave groove 27 that opens upward, the busbar holder 140 can be positioned in the circumferential direction with respect to the stator 23 and the housing 10. Therefore, when the bus bar holder 140 is screwed to the 2 nd support surface 12 of the housing 10, the bus bar holder 140, the stator 23, and the housing 10 can be positioned relative to each other in the circumferential direction and the axial direction.

The holder body 148 holds the magnetic sensor 63, the conductive wire 64, and the plurality of bus bars 150. In the present embodiment, the holder main body 148, the magnetic sensor 63, the conductive wire 64, the collar member 143, and the plurality of bus bars 150 are molded bodies that are integrated by resin molding. In more detail, the bus bar holder 140 is manufactured by insert molding with the magnetic sensor 63, the conductive wire 64, the collar member 143, and the bus bar 150 as insert members.

The magnetic sensor 63 can detect the magnetic field of the magnet 40. The magnetic sensor 63 is, for example, a hall element. The magnetic sensor 63 is held by the magnetic sensor holding portion 145 of the bus bar holder 140. The magnetic sensor holding part 145 is provided on the lower surface of the bus bar holder 140. The magnetic sensor holding portion 145 is recessed toward one axial side from the lower surface of the bus bar holder 140. The magnetic sensor 63 is inserted into the magnetic sensor holder 145 and fixed to the bus bar holder 140.

The magnetic sensor 63 is disposed opposite to the upper side of the magnet with a gap therebetween. As shown in fig. 2, three magnetic sensors 63 are arranged at intervals in the circumferential direction. The magnetic sensors 63 are circumferentially spaced from each other by the same circumferential spacing as the magnetic poles. The magnetic sensor 63 detects the rotation position of the magnet 40 by detecting the magnetic field of the magnet 40, thereby detecting the rotation of the motor shaft 21.

As shown in fig. 1, one end of the conductive wire 64 is electrically connected to the magnetic sensor 63. The conductive wire 64 may be a terminal extending from the magnetic sensor 63, or may be a bus bar having one end connected to the magnetic sensor 63. The conductive wire 64 penetrates the bus bar holder 140 from the inside of the bus bar holder 140, and the other end side is electrically connected to the circuit board 70 by a connection method such as soldering, welding, or press-fitting.

One end of the bus bar 150 is electrically connected to the stator 23. The other end of the bus bar 150 is electrically connected to the circuit board 70.

The circuit board 70 is disposed on one axial side of the bus bar holder 140. The circuit board 70 is plate-shaped extending in a plane perpendicular to the axial direction. The circuit board 70 is received in the housing 10. More specifically, the circuit board 70 is housed in the board housing portion 13 a. The circuit board 70 is a substrate electrically connected to the motor unit 20. The circuit board 70 controls, for example, the current supplied to the motor section 20. That is, an inverter circuit is mounted on the circuit board 70, for example. The circuit board 70 is electrically connected to the motor portion 20 via the bus bar 150.

The speed reduction mechanism 30 is connected to the rotor 22 on the other axial side of the motor unit 20. The speed reduction mechanism 30 reduces the speed of the power of the rotor 22. The speed reduction mechanism 30 is disposed radially outward of the 2 nd shaft portion 21b of the motor shaft 21 and radially outward of the coupling portion 42 of the output shaft 41. The speed reduction mechanism 30 is disposed below the motor unit 20. The reduction mechanism 30 has an external gear 31, an internal gear 32, an output portion 46, and a plurality of protruding portions 43.

The external gear 31 is in the form of an annular plate extending in the radial direction of the eccentric axis J2 about the eccentric axis J2 of the 2 nd shaft portion 21 b. A gear portion is provided on the radially outer side surface of the external gear 31. The gear portion of the external gear 31 has a plurality of tooth portions arranged along the outer periphery of the external gear 31.

The external gear 31 is coupled to the motor shaft 21. More specifically, the external gear 31 is coupled to the 2 nd shaft portion 21b of the motor shaft 21 via the 3 rd bearing 52. Thereby, the motor shaft 21 is coupled to the speed reduction mechanism 30. The external gear 31 is fitted to the outer ring of the 3 rd bearing 52 from the radially outer side. The 2 nd shaft portion 21b is fitted to the inner race of the 3 rd bearing 52 from the radially outer side. Thus, the 3 rd bearing 52 connects the motor shaft 21 and the externally toothed gear 31 to be rotatable relative to each other about the eccentric axis J2.

In the present embodiment, the external gear 31 has a plurality of holes 31 a. In the present embodiment, the hole 31a penetrates the external gear 31 in the axial direction. The plurality of holes 31a are arranged in the circumferential direction. More specifically, the plurality of holes 31a are arranged at equal intervals along the circumferential direction around the eccentric axis J2. The hole portion 31a has a circular shape when viewed in the axial direction. The inner diameter of the hole portion 31a is larger than the outer diameter of the projection 43. The hole 31a may have a bottom.

The internal gear 32 is positioned radially outward of the external gear 31, and is annular so as to surround the external gear 31. In the present embodiment, the internal gear 32 is annular with the center axis J1 as the center. The radially outer edge portion of the internal gear 32 is disposed and fixed on a step portion 13e recessed radially inward provided on the inner peripheral surface of the housing tube portion 13 b. Thereby, the reduction mechanism 30 is held by the housing 10. The internal gear 32 meshes with the external gear 31. A gear portion is provided on a radially inner side surface of the ring gear 32. The gear portion of the internal gear 32 has a plurality of teeth arranged along the inner periphery of the internal gear 32. In the present embodiment, the gear portion of the internal gear 32 meshes with the gear portion of the external gear 31 only in a part in the circumferential direction.

The output portion 46 is in the form of an annular plate extending radially about a central axis J1. Output portion 46 is located on the lower side of external gear 31. The output portion 46 is fixed to the outer peripheral surface of the output shaft 41. More specifically, the output portion 46 is fixed to the outer peripheral surface of the coupling portion 42 of the output shaft 41.

The plurality of projections 43 are fixed to the output portion 46 by, for example, welding. The plurality of protruding portions 43 protrude upward from the output portion 46. That is, the plurality of protruding portions 43 protrude from the output portion 46 toward the external gear 31. The projection 43 has a cylindrical shape. The plurality of projections 43 are arranged in the circumferential direction. More specifically, the plurality of protrusions 43 are arranged at equal intervals around the circumference around the central axis J1. The number of the projections 43 is, for example, eight.

The plurality of protruding portions 43 are inserted into the plurality of hole portions 31a, respectively. The outer peripheral surface of the protruding portion 43 is inscribed in the inner peripheral surface of the hole portion 31 a. Thereby, the plurality of projecting portions 43 support the external gear 31 via the inner side surface of the hole portion 31a so as to be swingable around the central axis J1.

In the present embodiment, the hole 31a and the protruding portion 43 overlap the 3 rd bearing 52 and the 2 nd shaft portion 21b when viewed in the radial direction. In other words, the hole 31a, the protruding portion 43, the 3 rd bearing 52, and the 2 nd shaft portion 21b have portions located at the same position in the axial direction.

When the motor shaft 21 rotates about the center axis J1, the 2 nd shaft portion 21b as an eccentric shaft portion revolves in the circumferential direction around the center axis J1. The revolution of the 2 nd shaft portion 21b is transmitted to the external gear 31 via the 3 rd bearing 52, and the external gear 31 swings while changing the inscribed position of the inner circumferential surface of the hole 31a and the outer circumferential surface of the protruding portion 43. Thereby, the position at which the gear portion of the external gear 31 meshes with the gear portion of the internal gear 32 changes in the circumferential direction. Therefore, the rotational force of the motor shaft 21 is transmitted to the internal gear 32 via the external gear 31.

Here, in the present embodiment, the internal gear 32 is fixed so as not to rotate. Therefore, the external gear 31 rotates about the eccentric axis J2 by the reaction force of the rotational force transmitted to the internal gear 32. At this time, the external gear 31 rotates in the opposite direction to the motor shaft 21. The rotation of external gear 31 about eccentric axis J2 is transmitted to output portion 46 via hole portion 31a and protruding portion 43. Thereby, the output shaft 41 rotates about the center axis J1. In this way, the rotation of the motor shaft 21 is transmitted to the output shaft 41 via the speed reduction mechanism 30.

The rotation of the output shaft 41 is decelerated with respect to the rotation of the motor shaft 21 by the reduction mechanism 30. Specifically, in the configuration of the speed reduction mechanism 30 according to the present embodiment, the speed reduction ratio R of the rotation of the output shaft 41 to the rotation of the motor shaft 21 is represented by- (N2-N1)/N2. The negative sign at the beginning of the expression indicating the reduction ratio R indicates that the rotation direction of the reduced output shaft 41 is opposite to the rotation direction of the motor shaft 21. N1 is the number of teeth of the external gear 31, and N2 is the number of teeth of the internal gear 32. For example, when the number of teeth N1 of the external gear 31 is 59 and the number of teeth N2 of the internal gear 32 is 60, the reduction ratio R is-1/60.

As described above, according to the electric actuator 1 of the present embodiment, fastening of the circuit board 70 to the housing 10 can fix not only the circuit board 70 but also the bus bar holder 140 and the stator 23 to the housing 10, and thus the assembly process can be simplified. Further, since the other components can be assembled to the housing 10 in order from the axial side, it is not necessary to turn the housing 10 upside down, and the assembly process can be simplified.

According to the present embodiment, the collar member 143 embedded in the holder main body 148 can provide a gap between the circuit board 70 and the holder main body 148. This facilitates mounting of components on the other surface of the circuit board 70 in the axial direction. In addition, the slow movement of the holder body 148 due to the fastening pressure can be suppressed.

According to the present embodiment, the stator 23 is positioned in the circumferential direction by inserting the raised strip portions 142 into the grooves 27. Further, the stator 23 can be held by the bus bar holder 140 by fastening the raised strip portions 142 to the recessed grooves 27. This makes it possible to construct a subassembly of the bus bar holder 140, the bus bar 150, and the stator 23, and to improve the workability in the connecting step of the bus bar 150 and the stator 23.

According to the present embodiment, since the bus bar holder 140 includes the magnetic sensor holding portion 145, the magnetic sensor 63 can be easily and accurately assembled.

According to the present embodiment, since all the components of the electric actuator 1 having the speed reduction mechanism 30 can be assembled to the housing 10 in this order from one axial side, it is not necessary to turn the housing 10 upside down, and the assembly process can be simplified.

While the embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other changes in the configurations can be made without departing from the scope of the present invention. The present invention is not limited to the embodiments.

For example, although the circuit board is fastened by the screws 144 in the above embodiment, other methods than fastening by the screws 144, such as pressure bonding and thermocompression bonding, may be exemplified.

The electric actuator according to the present invention may be a motor without a speed reduction mechanism as long as it is a device capable of moving a target object by being supplied with electric power. The electric actuator may be an electric pump having a pump section driven by a motor section. The use of the electric actuator is not particularly limited. The electric actuator may be mounted on a shift-by-wire type actuator device that is driven based on a shift operation by a driver. The electric actuator may be mounted on a device other than the vehicle. In addition, the respective structures described in the present specification can be appropriately combined within a range not inconsistent with each other.

Claims (5)

1. An electric actuator, characterized in that,

the electric actuator includes:

a motor unit having a rotor rotatable about a central axis extending in an axial direction and a stator surrounding the rotor from a radially outer side;

a bus bar electrically connected with the stator;

a bus bar holder which is arranged on one side in the axial direction of the motor part and holds the bus bar;

a circuit board that is disposed along a plane perpendicular to the central axis on one axial side of the bus bar holder, and that is electrically connected to the bus bar; and

a case that houses the motor part, the bus bar holder, and the circuit board,

the housing has:

an inner side surface surrounding the stator from a radially outer side;

a 1 st bearing surface located on the other axial side of the inner side surface and facing the one axial side; and

a 2 nd bearing surface located on and facing the axial one side of the inner side surface,

the stator is sandwiched between the busbar holder and the 1 st bearing surface in the axial direction,

the circuit board is fastened to the 2 nd bearing surface in the axial direction,

the bus bar holder is sandwiched between the circuit board and the 2 nd bearing surface in the axial direction.

2. The electric actuator according to claim 1,

the bus bar holder has:

a holder main body made of a resin material; and

a collar member embedded in the holder body in an axial direction,

the bus bar holder is in contact with the circuit board at an end surface on one axial side of the collar member and in contact with the 2 nd bearing surface at an end surface on the other axial side of the collar member,

a screw for fastening the circuit board to the 2 nd support surface is inserted into the collar member.

3. The electric actuator according to claim 1 or 2,

the peripheral surface of the stator is provided with a groove which extends along the axial direction and is opened towards one axial side,

the bus bar holder has a cylindrical portion surrounding an outer peripheral surface of the stator,

the inner peripheral surface of the cylindrical portion is provided with a ridge portion inserted into the recessed groove.

4. The electric actuator according to claim 1 or 2,

the electric actuator has a magnetic sensor that detects a magnetic field of a magnet of the rotor,

the bus bar holder has a magnetic sensor holding portion that holds the magnetic sensor.

5. The electric actuator according to claim 1 or 2,

the electric actuator includes a speed reduction mechanism that is connected to the rotor on the other axial side of the motor unit and reduces the speed of the power of the rotor,

the housing houses the speed reduction mechanism.

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