Electric Actuator

Abstract

To provide an electric actuator that can built a magnetic sensor to a stator with a high positional accuracy.SOLUTION: The electric actuator includes a motor unit, a bus bar, a bus bar holder, a magnetic sensor, and a circuit board. The bus holder has a cylindrical part surrounding an outer peripheral surface of the stator. In the outer peripheral surface of the stator, there are formed a first regulation wall surface facing one side in a peripheral direction and a second regulation wall surface facing the other side in the peripheral direction. In an inner peripheral surface of the cylindrical part, there are a first contact surface in contact with the first regulation wall surface and a second contact surface in contact with the second regulation wall surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electric actuator. [Background technology]

[0002] It is known that in controlling the rotation of a motor in an electric actuator, a magnetic sensor is used to detect changes in a magnetic field. For example, Patent Document 1 discloses a configuration in which a magnetic sensor is attached to the underside of a circuit board by adhesive and faces a magnet that rotates together with the motor shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-5431 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above configuration, in order for the magnetic sensor to detect the rotation of the motor shaft with high accuracy, the magnetic sensor needs to be attached to the stator with high positional accuracy. However, there is a problem that it is difficult to attach the magnetic sensor to the stator with high positional accuracy because of the overlapping of an assembly error of the magnetic sensor to the circuit board, an assembly error of the circuit board to be installed in the case, and an assembly error of the stator to the case.

[0005] In view of the above circumstances, an object of the present invention is to provide an electric actuator in which a magnetic sensor can be assembled with high positional accuracy relative to a stator. [Means for solving the problem]

[0006] One aspect of an electric actuator of the present invention comprises a motor section having a rotor rotatable around a central axis extending in the axial direction and a stator surrounding the rotor from the radially outside, a busbar electrically connected to the stator, a busbar holder arranged on one axial side of the motor section and holding the busbar, a magnetic sensor detecting a magnetic field of a magnet of the rotor, and a circuit board arranged along a plane perpendicular to the central axis on one axial side of the busbar holder and electrically connected to the magnetic sensor and the busbar, wherein the busbar holder has a cylindrical portion surrounding an outer peripheral surface of the stator, the outer peripheral surface of the stator being provided with a first restricting wall surface facing one circumferential side and a second restricting wall surface facing the other circumferential side, and the inner peripheral surface of the cylindrical portion being provided with a first contact surface in contact with the first restricting wall surface and a second contact surface in contact with the second restricting wall surface. Effect of the Invention

[0007] According to one aspect of the present invention, in an electric actuator, a magnetic sensor can be assembled with high positional accuracy relative to a stator. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing an electric actuator of the present embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the electric actuator of this embodiment, taken along line II-II in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing a part of the electric actuator of the present embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing an electric actuator in a modified example of this embodiment, taken along line II-II in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an electric actuator according to an embodiment of the present invention will be described with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiment, and can be modified as desired within the scope of the technical concept of the present invention. In addition, in the following drawings, the scale and number of each structure may differ from the actual structure in order to make each configuration easier to understand.

[0010] In each figure, the Z-axis direction is the up-down direction with the positive side at the top and the negative side at the bottom. The axial direction of the central axis J1 shown appropriately in each figure is parallel to the Z-axis direction, i.e., the up-down direction. In the following description, unless otherwise specified, the direction parallel to the axial direction of the central axis J1 will be simply referred to as the "axial direction." Furthermore, unless otherwise specified, the radial direction centered on the central axis J1 will be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J1 will be simply referred to as the "circumferential direction."

[0011] In this embodiment, the upper side corresponds to one axial side, and the lower side corresponds to the other axial side. Note that the terms "upper side" and "lower side" are merely names used to describe the relative positional relationship of each part, and the actual positional relationship may be a relationship other than the positional relationship indicated by these names.

[0012] 1 to 3, the electric actuator 1 of this embodiment is, for example, an electric actuator mounted on a vehicle. As shown in Fig. 1 and Fig. 3, the electric actuator 1 includes a case 10, a partition member 15, a cover member 80, a motor section 20 having a motor shaft 21 that rotates around a central axis J1, a first bearing 53, a second bearing 51, a third bearing 52, a reduction gear mechanism 30, an output shaft 41, a magnetic sensor 63, a circuit board 70, a bus bar holder 140, and a bus bar 150.

[0013] 1, case 10 accommodates partition member 15, motor section 20, motor shaft 21, speed reduction mechanism 30, output shaft 41, magnetic sensor 63, circuit board 70, bus bar holder 140, and bus bar 150. Case 10 has an opening that opens to the upper side.

[0014] The case 10 has a cylindrical shape extending in the axial direction about the central axis J1. The case 10 has a board accommodating portion 13a, a case tube portion 13b, an output portion accommodating portion 13c, and a bearing holding portion 13d. The board accommodating portion 13a is a portion that accommodates the circuit board 70 and the bus bar holder 140. The board accommodating portion 13a opens upward. The board accommodating portion 13a is configured radially inside the upper portion of the case 10. The bottom surface of the board accommodating portion 13a is a second support surface 12 that supports and fixes the circuit board 70 and the bus bar holder 140. The second support surface 12 faces upward.

[0015] The case cylindrical portion 13b surrounds the radial outside of the motor portion 20. The output portion accommodating portion 13c is a portion that accommodates the output portion 46 described below. The bearing holding portion 13d holds a second bearing 51. The bearing holding portion 13d extends upward from the lower end portion of the case 10 around the central axis J1.

[0016] The lid member 80 covers the opening of the case 10 and is fixed to the case 10. The lid member 80 is a container-shaped member having a recess 16a that opens downward. The lid member 80 and the case 10 are fastened together by a plurality of bolts 201 (see FIG. 3) that axially penetrate the lid member 80. In this embodiment, the lid member 80 corresponds to a lid that covers the opening of the case 10 from above. The lid member 80 has a bearing holding portion 16b. The bearing holding portion 16b holds the first bearing 53. The bearing holding portion 16b extends downward about the central axis J1.

[0017] The motor unit 20 has a central axis J1. As shown in Fig. 1, the motor unit 20 has a rotor 22 and a stator 23. The rotor 22 has a motor shaft 21, a rotor core 22a, and a magnet 40.

[0018] The motor shaft 21 includes a first shaft portion 21a, a second shaft portion 21b, and a through hole 25. The first shaft portion 21a extends in the axial direction and is located on the upper side of the motor shaft 21. The second shaft portion 21b extends in the axial direction and is located on the lower side of the motor shaft 21. The diameter of the second shaft portion 21b is larger than the diameter of the first shaft portion 21a. More specifically, the outer diameter of the second shaft portion 21b is larger than the outer diameter of the first shaft portion 21a. The second shaft portion 21b is an eccentric shaft portion centered on an eccentric axis J2 that is 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 central axis J1. Therefore, the first shaft portion 21a is cylindrical and extends around the central axis J1. The second shaft portion 21b has an axial recess 26 on the lower side. The recessed portion 26 extends about the eccentric axis J2. Therefore, the second shaft portion 21b is cylindrical and extends about the eccentric axis J2. The upper side of the recessed portion 26 is connected to the lower side of the through hole 25. The second shaft portion 21b of the motor shaft 21 is supported by the third bearing 52 so as to be rotatable about the eccentric axis J2.

[0019] The output shaft 41 receives the rotation of the motor shaft 21 via the reduction gear mechanism 30. The output shaft 41 has a shaft portion 41a and a connecting portion 42. The shaft portion 41a is located on the upper side, and the connecting portion 42 is located on the lower side. The shaft portion 41a is cylindrical and extends around the central axis J1. The upper side of the shaft portion 41a is inserted 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 from the motor shaft 21 is supported by a first bearing 53 so as to be rotatable around the central axis J1. The upper end of the motor shaft 21 is supported by the cover member 80 via the first bearing 53.

[0020] The lower end of the connecting portion 42 protrudes downward from the motor shaft 21. The lower end of the connecting portion 42 protruding downward from the motor shaft 21 is supported by the second bearing 51 so as to be rotatable around the central axis J1. The lower end of the motor shaft 21 is supported by the case 10 via the second bearing 51. The axial end of the output shaft 41 is supported by the first bearing 53 and the second bearing 51 so as to be rotatable around the central axis J1. Therefore, the motor shaft 21, in which the shaft portion 41a of the output shaft 41 is passed through the through hole 25, is supported by the shaft portion 41a so as to be rotatable around the central axis J1.

[0021] The first bearing 53, the second bearing 51, and the third bearing 52 are each a rolling bearing having an inner ring and an outer ring located radially outside the inner ring. In this embodiment, the first bearing 53, the second bearing 51, and the third bearing 52 are, for example, ball bearings in which the inner ring and the outer ring are connected via a plurality of balls.

[0022] The upper side of the connecting part 42 is inserted into the recessed part 26 of the motor shaft 21. By inserting the upper side of the connecting part 42 into the recessed part 26 of the motor shaft 21, the axial length of the output shaft 41 can be shortened. Therefore, the axial length of the electric actuator 1 can be shortened, and the size can be reduced.

[0023] The connecting portion 42 has a cylindrical tube portion 44 extending about the central axis J1. A connecting recess 45 is provided on the inner diameter of the tube portion 44. The connecting recess 45 is recessed upward from the lower end of the output shaft 41. When viewed along the axial direction, the connecting recess 45 has a substantially circular shape centered on the central axis J1. A plurality of spline grooves are provided on the inner surface of the connecting recess 45 along the circumferential direction. Another member to which the driving force of the electric actuator 1 is output is inserted and connected to the connecting recess 45. The other member is, for example, a manual shaft in a vehicle. The electric actuator 1 drives the manual shaft based on a shift operation by the driver to switch the gears of the vehicle.

[0024] By having the connecting portion 42 have the connecting recess 45 recessed upward, the axial length of the output shaft 41 can be shortened compared to when the connecting portion 42 is axially projecting downward. Therefore, the axial length of the electric actuator 1 can be shortened and made compact. The first bearing 53 is held by the bearing holder 16b provided on the case 10, and the second bearing 51 is held by the bearing holder 13d provided on the case 10, so that the concentricity of the output shaft 41 with respect to the central axis J1 can be improved. The first bearing 53 is held by the bearing holder 16b provided on the case 10, and the second bearing 51 is held by the bearing holder 13d provided on the case 10, so that it is not necessary to provide separate holders for the first bearing 53 and the second bearing 51, which contributes to cost reduction and compactness of the electric actuator 1.

[0025] The rotor core 22a is fixed to an outer circumferential surface of the motor shaft 21. More specifically, the rotor core 22a is fixed to an outer circumferential surface of the first shaft portion 21a. The magnet 40 is fixed to the radially outer side of the rotor core 22a. A plurality of magnets 40 are arranged at intervals in the circumferential direction.

[0026] 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 radial outside of the rotor 22. An outer core surface 24a of the stator core 23a is fixed to the inner surface 14 of the case cylindrical portion 13b. In other words, the inner surface 14 of the case 10 surrounds the stator 23 from the radial outside. The coils 23b are attached to the teeth 23t (see FIG. 2) of the stator core 23a via insulators 29.

[0027] As shown in FIG. 2, the stator 23 has an outer peripheral surface 24b radially inward from the core outer peripheral surface 24a. The outer peripheral surface 24b is a surface facing the radially outward side of the insulator 29. The outer peripheral surface 24b is arranged for each magnetic pole. When viewed in the axial direction, the outer peripheral surface 24b is perpendicular to the circumferential magnetic pole center. The outer peripheral surface 24b of the stator 23 is provided with a groove 27 recessed radially inward. The groove 27 extends continuously in the axial direction. The groove 27 is substantially U-shaped when viewed in the axial direction, and has a first restricting wall surface 27a facing one circumferential side and a second restricting wall surface 27b facing the other circumferential side. The first restricting wall surface 27a and the second restricting wall surface 27b are inner wall surfaces of the groove 27. The groove 27 is arranged on the upper side and the lower side of the core outer peripheral surface 24a of the stator core 23a. The recessed groove 27 extends along the axial direction and opens to one axial side. A plurality of the recessed grooves 27 are arranged at intervals in the circumferential direction.

[0028] 1, the peripheral edge of stator core 23a is supported from below by peripheral wall portion 15b of partition member 15. The peripheral edge of stator core 23a contacts peripheral wall portion 15b of partition member 15 from one axial side. The partition member 15 is disposed on the other axial side of the motor section 20. The partition member 15 is disposed axially between the stator 23 and the reduction mechanism 30. The partition member 15 is in the shape of an annular plate. The peripheral wall section 15b extends from the outer periphery of the partition member 15 to one axial side. The outer periphery of the partition member 15 contacts the first support surface 11 of the case 10 from one axial side. The first support surface 11 is located on the other axial side of the inner surface 14. The first support surface 11 faces one axial side.

[0029] The busbar holder 140 is disposed above the rotor 22. The busbar holder 140 is disposed on one axial side of the motor section 20. The busbar holder 140 is in the shape of an annular plate. The busbar holder 140 has a holder body 148 and a collar member 143. The holder body 148 is made of an insulating resin material. The holder body 148 of the busbar holder 140 has a flange portion 140f that extends radially outward from a cylindrical portion 141 described later. The flange portion 140f of the busbar holder 140 contacts the second support surface 12 of the case 10 from one axial side. The second support surface 12 is located on one axial side of the inner surface 14. The second support surface 12 faces one axial side.

[0030] 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 orientation. The collar member 143 protrudes upward from the bus bar holder 140. An end face 143f on one axial side of the collar member 143 contacts the underside of the circuit board 70. An end face 143g on the other axial side of the collar member 143 contacts the second support surface 12. As a result, the bus bar holder 140 is sandwiched between the circuit board 70 and the second support surface 12 in the axial direction.

[0031] Screws 144 for fastening the circuit board 70 to the second support surface 12 are inserted into the collar member 143. The bus bar holder 140 and the circuit board 70 are screwed to the second support surface 12 of the case 10 by the screws 144 penetrating the circuit board 70 and the collar member 143 from above. For example, four screws 144 are provided. The bus bar holder 140 and the circuit board 70 are screwed to the second support surface 12 of the case 10 by the screws 144 from above at positions overlapping with the collar member 143 when viewed in the axial direction. The circuit board 70 is fastened to the second support surface 12 in the axial direction by the screws 144. The screwed circuit board 70 is disposed above the bus bar holder 140 with a gap therebetween. The dimension of the gap between the circuit board 70 and the bus bar holder 140 is a dimension in which the collar member 143 protrudes above the bus bar holder 140.

[0032] The busbar holder 140 has a cylindrical portion 141 extending downward. The cylindrical portion 141 is located radially outward from 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 from the core outer peripheral surface 24a of the stator 23. A lower end of the cylindrical portion 141 comes into contact with an upper side of the stator 23 when the busbar holder 140 is screwed to the second support surface 12.

[0033] When busbar holder 140 is screwed to second support surface 12 of case 10, the lower end of cylindrical portion 141 comes into contact with the upper side of stator 23, so that stator 23 is sandwiched between busbar holder 140 and first support surface 11 in the axial direction. Stator 23, supported from below by partition member 15, is positioned and fixed to case 10 in the axial direction.

[0034] As shown in FIG. 2, a convex streak portion 142 is provided on an inner peripheral surface 141a of a cylindrical portion 141 of a busbar holder 140. The convex streak portion 142 protrudes radially inward from the inner peripheral surface 141a of the cylindrical portion 141. The convex streak portion 142 extends in the axial direction. The circumferential position of the convex streak portion 142 is the same as the circumferential position of the concave groove 27 of the stator 23. The convex streak portion 142 protruding radially inward from the cylindrical portion 141 is inserted into the concave groove 27 on the upper side of the core outer peripheral surface 24a. The convex streak portion 142 faces the concave groove 27 in the radial direction. The convex streak portion 142 is substantially U-shaped when viewed in the axial direction, and has a first contact surface 142f and a second contact surface 142g. The first contact surface 142f and the second contact surface 142g are side surfaces facing both circumferential sides of the convex streak portion 142. The first contact surface 142f contacts the first restriction wall surface 27a, and the second contact surface 142g contacts the second restriction wall surface 27b.

[0035] Busbar holder 140, with protruding portion 142 inserted into recessed groove 27, is positioned circumferentially with respect to stator 23. When busbar holder 140 is accommodated in substrate accommodating portion 13a while protruding portion 142 is inserted from above into recessed groove 27 that opens upward, busbar holder 140 can be positioned circumferentially with respect to stator 23 and case 10. Therefore, when busbar holder 140 is screwed to second support surface 12 of case 10, busbar holder 140, stator 23, and case 10 can be positioned relative to each other in the circumferential and axial directions.

[0036] Holder body 148 holds magnetic sensor 63, conductive wire 64, and a plurality of bus bars 150. In this embodiment, holder body 148, magnetic sensor 63, conductive wire 64, collar member 143, and a plurality of bus bars 150 are formed into an integrated molded body by resin molding.

[0037] 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 in an accommodating recess 145 provided in the busbar holder 140. The accommodating recess 145 is provided on the lower surface of the busbar holder 140. The accommodating recess 145 is recessed from the lower surface of the busbar holder 140 to one axial side. The accommodating recess 145 is open to the other axial side. The magnetic sensor 63 is fixed to the busbar holder 140 by being inserted into the accommodating recess 145.

[0038] The magnetic sensor 63 is disposed above the magnet, facing it with a gap therebetween. As shown in Fig. 2, three magnetic sensors 63 are disposed at intervals in the circumferential direction. The circumferential interval between the magnetic sensors 63 is the same as the circumferential interval between the magnetic poles. The magnetic sensor 63 detects the magnetic field of the magnet 40 to detect the rotational position of the magnet 40, and thereby detects the rotation of the motor shaft 21.

[0039] As shown in FIG. 1, the conductive wire 64 connects the magnetic sensor 63 and the circuit board 70. 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 is inserted into an insertion hole 146 that penetrates from the accommodating recess 145 to one side in the axial direction. The conductive wire 64 penetrates the bus bar holder 140 from inside the bus bar holder 140, and the other end is electrically connected to the circuit board 70 by a connection method such as soldering, welding, or press fitting.

[0040] 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.

[0041] The circuit board 70 is disposed on one axial side of the bus bar holder 140. The circuit board 70 is plate-shaped and extends in a plane perpendicular to the axial direction. The circuit board 70 is accommodated in the case 10. More specifically, the circuit board 70 is accommodated in the board accommodating portion 13a. The circuit board 70 is a board electrically connected to the motor section 20. The circuit board 70 controls, for example, the current supplied to the motor section 20. That is, the circuit board 70 is equipped with, for example, an inverter circuit. The circuit board 70 is electrically connected to the motor section 20 via the bus bar 150.

[0042] The reduction mechanism 30 is connected to the rotor 22 on the other axial side of the motor unit 20. The reduction mechanism 30 reduces the power of the rotor 22. The reduction mechanism 30 is disposed radially outside the second shaft portion 21b of the motor shaft 21 and radially outside the connecting portion 42 of the output shaft 41. The 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 protrusions 43.

[0043] The external gear 31 is annular and extends radially about the eccentric shaft J2 of the second shaft portion 21b. A gear portion is provided on the radially outer surface of the external gear 31. The gear portion of the external gear 31 has a plurality of teeth arranged along the outer periphery of the external gear 31.

[0044] The external gear 31 is connected to the motor shaft 21. More specifically, the external gear 31 is connected to the second shaft portion 21b of the motor shaft 21 via the third bearing 52. As a result, the motor shaft 21 is connected to the reduction gear mechanism 30. The external gear 31 is fitted into the outer ring of the third bearing 52 from the outside in the radial direction. The second shaft portion 21b is fitted into the inner ring of the third bearing 52 from the outside in the radial direction. As a result, the third bearing 52 connects the motor shaft 21 and the external gear 31 to be relatively rotatable around the eccentric axis J2.

[0045] In this embodiment, the external gear 31 has a plurality of holes 31a. In this embodiment, the holes 31a penetrate the external gear 31 in the axial direction. The plurality of holes 31a are arranged along the circumferential direction. More specifically, the plurality of holes 31a are arranged at equal intervals around one circumference along the circumferential direction centered on the eccentric axis J2. The holes 31a are circular when viewed in the axial direction. The inner diameter of the hole 31a is larger than the outer diameter of the protrusion 43. The hole 31a may be a hole having a bottom.

[0046] The internal gear 32 is located radially outside the external gear 31 and is annular in shape surrounding the external gear 31. In this embodiment, the internal gear 32 is annular in shape centered on the central axis J1. The radial outer edge of the internal gear 32 is disposed and fixed to a step portion 13e recessed radially inwardly on the inner surface of the case cylindrical portion 13b. This allows the reduction mechanism 30 to be held in the case 10. The internal gear 32 meshes with the external gear 31. A gear portion is provided on the radial inner surface of the internal gear 32. The gear portion of the internal gear 32 has a plurality of teeth arranged along the inner circumference of the internal gear 32. In this embodiment, the gear portion of the internal gear 32 meshes with the gear portion of the external gear 31 only in a portion of the circumferential direction.

[0047] The output portion 46 has an annular plate shape that expands in the radial direction about the central axis J1. The output portion 46 is located below the external gear 31. The output portion 46 is fixed to the outer circumferential surface of the output shaft 41. More specifically, the output portion 46 is fixed to the outer circumferential surface of the connecting portion 42 of the output shaft 41.

[0048] The multiple protrusions 43 are fixed to the output portion 46 by, for example, welding. The multiple protrusions 43 protrude upward from the output portion 46. That is, the multiple protrusions 43 protrude from the output portion 46 toward the external gear 31. The protrusions 43 are cylindrical. The multiple protrusions 43 are arranged along the circumferential direction. More specifically, the multiple protrusions 43 are arranged at equal intervals around one circumference along the circumferential direction centered on the central axis J1. The number of protrusions 43 is, for example, eight.

[0049] The multiple protrusions 43 are inserted into the multiple hole portions 31a, respectively. The outer peripheral surface of the protrusion 43 is inscribed in the inner surface of the hole portion 31a. As a result, the multiple protrusions 43 support the external gear 31 via the inner surface of the hole portion 31a so as to be swingable around the central axis J1.

[0050] In this embodiment, the hole 31a and the protrusion 43 overlap with the third bearing 52 and the second shaft portion 21b when viewed in the radial direction. In other words, the hole 31a, the protrusion 43, the third bearing 52, and the second shaft portion 21b each have a portion located at the same position as each other in the axial direction.

[0051] When the motor shaft 21 rotates around the central axis J1, the second shaft portion 21b, which is an eccentric shaft portion, revolves in the circumferential direction around the central axis J1. The revolution of the second shaft portion 21b is transmitted to the external gear 31 via the third bearing 52, and the external gear 31 oscillates while changing the position where the inner surface of the hole portion 31a and the outer circumferential surface of the protrusion 43 are inscribed. As a result, the position where the gear portion of the external gear 31 and the gear portion of the internal gear 32 mesh with each other 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.

[0052] Here, in this embodiment, the internal gear 32 is fixed and does not rotate. Therefore, the external gear 31 rotates around the eccentric axis J2 due to the reaction force of the rotational force transmitted to the internal gear 32. At this time, the direction of rotation of the external gear 31 is opposite to the direction of rotation of the motor shaft 21. The rotation of the external gear 31 around the eccentric axis J2 is transmitted to the output portion 46 via the hole portion 31a and the protrusion portion 43. As a result, the output shaft 41 rotates around the central axis J1. In this way, the rotation of the motor shaft 21 is transmitted to the output shaft 41 via the reduction mechanism 30.

[0053] The rotation of the output shaft 41 is reduced relative to the rotation of the motor shaft 21 by the reduction gear mechanism 30. Specifically, in the configuration of the reduction gear mechanism 30 of this embodiment, the reduction ratio R of the rotation of the output shaft 41 to the rotation of the motor shaft 21 is expressed as R=-(N2-N1) / N2. The negative sign at the beginning of the equation expressing the reduction ratio R indicates that the rotation direction of the output shaft 41, which is reduced, 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. As an 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.

[0054] Thus, according to the electric actuator 1 of the present embodiment, the first restricting wall surface 27a and the second restricting wall surface 27b of the stator 23 are brought into contact with the first contact surface 142f and the second contact surface 142g of the cylindrical portion 141, thereby positioning the bus bar holder 140 and the stator 23 in the circumferential direction. This makes it possible to improve the accuracy of the circumferential position of the magnetic sensor 63 and the stator 23 held by the bus bar holder 140. Therefore, the magnetic sensor 63 can be assembled to the stator 23 with high positional accuracy.

[0055] According to this embodiment, the first regulating wall surface 27a and the second regulating wall surface 27b are inner wall surfaces of the groove 27, and the first contact surface 142f and the second contact surface 142g are side surfaces of the convex rib portion 142. Therefore, by inserting the convex rib portion 142 into the groove 27, the busbar holder 140 holding the magnetic sensor 63 is easily positioned circumferentially relative to the stator 23 with high positional accuracy.

[0056] According to this embodiment, stator 23 is positioned in the circumferential direction by inserting convex rib portion 142 into concave groove 27. In addition, by making convex rib portion 142 fastenable with respect to concave groove 27, bus bar holder 140 holding magnetic sensor 63 is easily positioned with high positional accuracy in the circumferential direction relative to stator 23.

[0057] According to this embodiment, bus bar holder 140 has accommodating recess 145 and insertion hole 146, so that magnetic sensor 63 and conductive wire 64 can be attached easily and with high accuracy.

[0058] According to this embodiment, in the electric actuator 1 having the speed reducing mechanism 30, the magnetic sensor 63 can be assembled with high positional accuracy.

[0059] (Modification) 4 is a cross-sectional view showing an electric actuator according to a modified example of the embodiment described above. The electric actuator 1B according to this modified example differs from the electric actuator 1 described above mainly in the structures of the stator 23B and the bus bar holder 140B. Note that the same components as those in the embodiment described above are denoted by the same reference numerals and their description will be omitted.

[0060] As shown in FIG. 4, a recessed groove 27B is provided on an inner peripheral surface 141a of a cylindrical portion 141 of a bus bar holder 140B. The recessed groove 27B is recessed radially outward on the inner peripheral surface 141a of the cylindrical portion 141. The recessed groove 27B extends in the axial direction. The recessed groove 27B extends along the axial direction and opens to the other axial side. The recessed groove 27B faces the protruding strip portion 142B in the radial direction. The recessed groove 27B is substantially U-shaped when viewed in the axial direction, and has a first restricting wall surface 27c and a second restricting wall surface 27d. The first restricting wall surface 27c and the second restricting wall surface 27d are inner wall surfaces of the recessed groove 27B.

[0061] The outer peripheral surface 24b of the stator 23B is provided with a convex streak portion 142B that protrudes radially outward. The convex streak portion 142B is inserted into the concave groove 27B. The convex streak portion 142B extends continuously in the axial direction. The circumferential position of the convex streak portion 142B is the same as the circumferential position of the concave groove 27B of the bus bar holder 140B. The convex streak portion 142B is substantially U-shaped when viewed in the axial direction, and has a first contact surface 142h facing one circumferential side and a second contact surface 142i facing the other circumferential side. The first contact surface 142h and the second contact surface 142i are side surfaces facing both circumferential sides of the convex streak portion 142B. A plurality of the convex streak portions 142B are arranged at intervals in the circumferential direction. The first contact surface 142h contacts the first restricting wall surface 27c. The second contact surface 142i contacts the second restriction wall surface 27d.

[0062] Bus bar holder 140B, with protruding strip portions 142B inserted into recessed grooves 27B, is positioned relative to stator 23B in the circumferential direction.

[0063] According to the present embodiment, the stator 23B is positioned in the circumferential direction by inserting the convex streak portion 142B into the concave groove 27B. This improves the accuracy of the circumferential position of the magnetic sensor 63 and the stator 23 held by the bus bar holder 140. Therefore, the magnetic sensor 63 can be assembled with high positional accuracy.

[0064] Although one embodiment of the present invention has been described above, each configuration and their combination in the embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiment.

[0065] For example, in the above-described embodiment, the stator 23 is positioned circumferentially by inserting the convex strips 142, 142B into the concave grooves 27, 27B, but the busbar holder 140 may be integrally molded by insert molding using the magnetic sensor 63, the conductive wire 64, the collar member 143, and the busbar 150 as insert members.

[0066] In addition, the electric actuator to which the present invention is applied may be a device that can move a target object by supplying electric power, and may be a motor without a reduction mechanism. In addition, the electric actuator may be an electric pump that includes 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 the driver's shift operation. In addition, the electric actuator may be mounted on equipment other than a vehicle. Note that the configurations described in this specification may be appropriately combined within a range that does not contradict each other. [Explanation of symbols]

[0067] Reference Signs List 1, 1B...electric actuator, 10...case, 20...motor portion, 22...rotor, 23, 23B...stator, 24b...outer peripheral surface, 27, 27B...groove, 27a, 27c...first restricting wall surface, 27b, 27d...second restricting wall surface, 30...reduction mechanism, 40...magnet, 63...magnetic sensor, 64...conductive wire, 70...circuit board, 140, 140B...bus bar holder, 141...cylindrical portion, 141a...inner peripheral surface, 142, 142B...protruding strip portion, 142f, 142h...first contact surface, 142g, 142i...second contact surface, 145...receiving recess, 146...insertion hole, 150...bus bar, J1...center axis

Claims

1. a motor section including a rotor rotatable about a central axis extending in an axial direction and a stator surrounding the rotor from the radially outer side; a case extending in an axial direction about the central axis and surrounding a radially outer side of the motor unit; A bus bar electrically connected to the stator; a bus bar holder arranged on one axial side of the motor unit and holding the bus bar; a magnetic sensor held by the bus bar holder and detecting a magnetic field of a magnet of the rotor; a circuit board disposed along a plane perpendicular to the central axis on one axial side of the bus bar holder, the circuit board being electrically connected to the magnetic sensor and the bus bar, the bus bar holder has a cylindrical portion surrounding an outer circumferential surface of the stator, the bus bar holder is in contact with the case from one axial side, The outer circumferential surface of the stator is a first restriction wall surface facing one circumferential direction; a second restriction wall surface facing the other circumferential side; The inner circumferential surface of the cylindrical portion is a first contact surface that contacts the first restriction wall surface; A second contact surface that contacts the second restriction wall surface is provided. Electric actuator.

2. A groove is provided on an outer circumferential surface of the stator, the groove extending along the axial direction and opening to one side in the axial direction. a protruding portion to be inserted into the recessed groove is provided on an inner peripheral surface of the cylindrical portion, the first restriction wall surface and the second restriction wall surface are inner wall surfaces of the groove, The first contact surface and the second contact surface are side surfaces of the protruding portion. The electric actuator according to claim 1 .

3. a groove extending along the axial direction and opening to the other axial direction side is provided on an inner peripheral surface of the cylindrical portion, The stator has an outer peripheral surface provided with a protruding portion to be inserted into the recessed groove, the first regulating wall surface and the second regulating wall surface are side surfaces of the protruding rib portion, The first contact surface and the second contact surface are inner wall surfaces of the groove. The electric actuator according to claim 1 .

4. The bus bar holder includes: an accommodating recess that opens to the other axial side; an insertion hole penetrating from the accommodating recess to one side in the axial direction; The magnetic sensor is accommodated in the accommodation recess, A conductive wire connecting the magnetic sensor and the circuit board is inserted through the insertion hole. The electric actuator according to any one of claims 1 to 3.

5. a reduction mechanism connected to the rotor on the other axial side of the motor unit and configured to reduce the power of the rotor; a case that accommodates the motor unit, the bus bar, the bus bar holder, the magnetic sensor, the circuit board, and the reduction gear mechanism. The electric actuator according to any one of claims 1 to 4.

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