Electric actuator

Abstract

The present invention provides an electric actuator having: a motor shaft that is driven by a motor unit to rotate about a central axis, the motor shaft having a through-hole in the axial direction; and an output shaft, one axial side of which is inserted into the through-hole, and the rotation of the motor shaft is transmitted to the output shaft. An axial recess connected to the through-hole is provided on the other axial side of the motor shaft. A connecting portion is provided on the other axial side of the output shaft, and the connecting portion connects to a driven body that receives the rotation of the output shaft from the other axial side. The one axial side of the connecting portion is inserted into the recess.

Description

Technical Field

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

[0002] There is known an electric actuator in which the rotation of a motor unit is transmitted via a speed reducer. For example, Patent Document 1 discloses an electric actuator in which a motor shaft, a reduction gear, and a spline as an interface with the vehicle side are formed on one shaft, and the spline protrudes.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-126032

[0004] Since a relatively large number of functional components are formed on one shaft, there is a problem that the size in the axial direction increases. Summary of the Invention

[0005] The present invention has been made in consideration of the above points, and an object thereof is to provide a compact electric actuator.

[0006] One aspect of the present invention is an electric actuator including: a motor shaft that is driven by a motor unit and rotates about a central axis, the motor shaft having a through hole in the axial direction; and an output shaft, one axial side of which is inserted into the through hole, the rotation of the motor shaft being transmitted to the output shaft, an axial recess connected to the through hole is provided on the other axial side of the motor shaft, a connecting portion is provided on the other axial side of the output shaft, the connecting portion is connected to a driven body to which the rotation of the output shaft is transmitted from the other axial side, and one axial side of the connecting portion is inserted into the recess.

[0007] According to one aspect of the present invention, a compact electric actuator can be provided. Brief Description of the Drawings

[0008] Figure 1 It is a cross-sectional view showing the electric actuator of the present embodiment.

[0009] Figure 2 It is a cross-sectional view showing the electric actuator of the present embodiment, which is Figure 1 a cross-sectional view taken along line II-II in

[0010] Figure 3 It is a schematic cross-sectional view showing a part of the electric actuator of the present embodiment.

[0011] Reference Signs Explanation

[0012] 10: Electric actuator; 12: Support surface; 15: Support member (partition member); 20: Motor unit; 21: Motor shaft; 21a: First shaft portion; 21b: Second shaft portion (eccentric shaft portion); 22: Rotor; 23: Stator; 24b: Outer peripheral surface; 25: Through hole; 30: Reduction mechanism; 40: Magnet; 41: Output shaft; 45: Connecting recess; 51: Second bearing; 52: Third bearing; 53: First bearing; 63: Magnetic sensor; 64: Conductive wire; 70: Circuit board; 140: Bus bar holder; 141: Peripheral wall portion; 142: Protrusion; 143: Spacer; 150: Bus bar; J1: Central axis; J2: Eccentric axis. Detailed implementation mode

[0013] Hereinafter, the electric actuator according to the embodiment of the present invention will be described with reference to the drawings. In addition, the scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention. In addition, in the following drawings, in order to easily understand each structure, the actual structure may sometimes be different from the scale, quantity, etc. in each structure.

[0014] In each figure, the Z-axis direction is the up-down direction with the positive side as the upper side and the negative side as the lower side. The axial direction of the central axis J1 appropriately shown in each figure is parallel to the Z-axis direction, that is, 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". In addition, 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".

[0015] In the present embodiment, the upper side corresponds to one side in the axial direction, and the lower side corresponds to the other side in the axial direction. In addition, the upper side and the lower side are only names for explaining the relative position relationship of each part, and the actual arrangement relationship, etc. can also be an arrangement relationship other than the arrangement relationship represented by these names.

[0016] Figures 1 to 3 The electric actuator 10 shown in the present embodiment is, for example, an electric actuator mounted on a vehicle. As Figure 1 and Figure 3 shown, the electric actuator 10 includes a housing 11, a partition member 15, a motor unit 20, a first bearing 53, a second bearing 51, a third bearing 52, a reduction mechanism 3, an output shaft 41, a magnetic sensor 63, a circuit board 70, and a bus bar holder 140, wherein the motor unit 20 has a motor shaft 21 that rotates about the central axis J1.

[0017] As Figure 1As shown, the housing 11 houses the partition member 15, the motor unit 20, the motor shaft 21, the reduction mechanism 30, the output shaft 41, the magnetic sensor 63, the circuit board 70, and the bus bar holder 140. The housing 11 has a lower housing 11A that is open on the upper side and an upper housing 11B that is fixed to the opening of the lower housing 11A.

[0018] The lower housing 11A has a cylindrical shape that extends in the axial direction with the central axis J1 as the center. The lower housing 11A has a substrate housing portion 13a, a housing cylinder portion 13b, an output portion housing portion 13c, and a bearing holder portion 13d. The substrate housing portion 13a is the part that houses the circuit board 70 and the bus bar holder 140. The substrate housing portion 13a is open on the upper side. The substrate housing portion 13a is formed on the radially inner side of the upper side portion of the lower housing 11A. The bottom surface of the substrate housing portion 13a is a support surface 12 that supports and fixes the circuit board 70 and the bus bar holder 140. The support surface 12 faces upward.

[0019] The housing cylinder portion 13b surrounds the radially outer side of the motor unit 20. The output portion housing portion 13c is the part that houses the output portion 46 described later. The bearing holder portion 13d holds the third bearing 52. The bearing holder portion 13d extends upward from the lower end portion of the housing 11 with the central axis J1 as the center.

[0020] The upper housing 11B is a container-shaped member having a recess 16a that is open on the lower side. The upper housing 11B and the lower housing 11A are fastened by a plurality of bolts that penetrate the upper housing 11B in the axial direction. In the present embodiment, the upper housing 11B corresponds to a lid portion that covers the opening of the lower housing 11A from above. The upper housing 11B has a bearing holder portion 16b. The bearing holder portion 16b holds the first bearing 53. The bearing holder portion 16b extends downward with the central axis J1 as the center.

[0021] The central axis of the motor unit 2 is the central axis J1. As Figure 1 shown, 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.

[0022] The motor shaft 21 has a first shaft portion 21a, a second shaft portion 21b, and a through hole 25. The first shaft portion 21a extends axially and is located on the upper side of the motor shaft 21. The second shaft portion 21b extends axially 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 centered on the central axis J1. Therefore, the first shaft portion 21a is in the shape of a cylinder extending centered on the central axis J1. The second shaft portion 21b has an axial recess 26 on the lower side. The recess 26 extends centered on the eccentric axis J2. Therefore, the second shaft portion 21b is in the shape of a cylinder extending centered on the eccentric axis J2. The upper side of the recess 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 a third bearing 52 so as to be rotatable about the eccentric axis J2.

[0023] The rotation of the motor shaft 21 is transmitted to the output shaft 41 via a speed reduction 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 in the shape of a cylinder extending centered on the central axis J1. The upper side of the shaft portion 41a extends into the through hole 25 of the motor shaft 21. The upper end portion of the shaft portion 41a protruding upward from the motor shaft 21 is supported by a first bearing 53 so as to be rotatable about the central axis J1. The upper end portion of the motor shaft 21 is supported on the housing 11 via the first bearing 53.

[0024] The lower end portion of the connecting portion 42 protrudes downward from the motor shaft 21. The lower end portion of the connecting portion 42 protruding downward from the motor shaft 21 is supported by a second bearing 51 so as to be rotatable about the central axis J1. The lower end portion of the motor shaft 21 is supported on the housing 11 via the second bearing 51. The axial end portion of the output shaft 41 is supported by the first bearing 53 and the second bearing 51 so as to be rotatable about the central axis J1. Therefore, the motor shaft 21 into which the shaft portion 41a of the output shaft 41 extends in the through hole 25 is supported by the shaft portion 41a so as to be rotatable about the central axis J1.

[0025] The first bearing 53, the second bearing 51, and the third bearing 52 are respectively rolling bearings having an inner ring and an outer ring located radially outside the inner ring. In the present 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.

[0026] The upper side of the connecting portion 42 is inserted into the recessed portion 26 of the motor shaft 21. By inserting the upper side of the connecting portion 42 into the recessed portion 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 10 can be shortened to miniaturize the electric actuator 10.

[0027] The connecting portion 42 has a cylindrical tube portion 44 extending around the central axis J1. A connecting recess 45 is provided in 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 is substantially circular around the central axis J1. A plurality of spline grooves are provided along the circumferential direction on the inner peripheral surface of the connecting recess 45. Other components that output the driving force of the electric actuator 10 are inserted and connected in the connecting recess 45. Other components are, for example, manual shafts in a vehicle. The electric actuator 10 drives the manual shaft according to the driver's shifting operation to switch the gears of the vehicle.

[0028] Since the connecting portion 42 has the connecting recess 45 recessed upward, the axial length of the output shaft 41 can be shortened compared to the case where the connecting portion 42 is a shaft protruding downward. Therefore, the axial length of the electric actuator 10 can be shortened to miniaturize the electric actuator 10. By holding the first bearing 53 by the bearing holding portion 16b provided in the housing 11 and holding the second bearing 51 by the bearing holding portion 13d provided in the housing 11, the coaxiality of the output shaft 41 with respect to the central axis J1 can be improved. By holding the first bearing 53 by the bearing holding portion 16b provided in the housing 11 and holding the second bearing 51 by the bearing holding portion 13d provided in the housing 11, there is no need to separately provide components for holding the first bearing 53 and the second bearing 51, which can contribute to cost reduction and miniaturization of the electric actuator 10.

[0029] 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 first shaft portion 21a. The peripheral edge portion of the rotor core 22a is supported from below by a partition member 15 described later, and the partition member 15 is supported from below by the lower housing 11A. The partition member 15 is a support member that supports the rotor core 22a from below. 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.

[0030] The stator 23 is located on the radially outer side of the rotor 22. The stator 23 has a stator core 23a and a plurality of coils 23b. The stator core 23a is in a circular ring shape surrounding the radially outer side of the rotor 22. The outer peripheral surface 24a of the stator core 23a is fixed to the inner peripheral surface of the housing tube portion 13b. The plurality of coils 23b are mounted on the teeth of the stator core 23a, for example, with an insulating member (not shown) interposed therebetween.

[0031] AsFigure 2 As shown, the stator 23 has an outer peripheral surface 24b at a position radially inside the outer peripheral surface 24a. The outer peripheral surface 24b is arranged for each magnetic pole. When observed in the axial direction, the outer peripheral surface 24b is perpendicular to the circumferential magnetic pole center. A groove portion 27 that is recessed radially inward is provided on the outer peripheral surface 24b of the stator 23. The groove portion 27 extends in the axial direction. The groove portions 27 are respectively arranged at positions above and below the outer peripheral surface 24a of the stator core 23a. A plurality of groove portions 27 are arranged at intervals in the circumferential direction.

[0032] The bus bar holder 140 is arranged above the rotor 22. The bus bar holder 140 has an annular plate shape. As Figure 1 shown, the bus bar holder 140 has a spacer 143. The spacer 143 has a cylindrical shape extending in the axial direction. The spacer 143 protrudes upward from the bus bar holder 140. The upper end of the spacer 143 is in contact with the lower side of the circuit board 70. The bus bar holder 140 and the circuit board 70 are screwed and fixed to the support surface 12 of the lower housing 11A by bolts 144 that penetrate the circuit board 70 and the spacer 143 from above. For example, 3 bolts 144 are provided. The bus bar holder 140 and the circuit board 70 are screwed and fixed from above by the bolts 144 at positions where they overlap with the spacer 143 when observed in the axial direction. The screwed circuit board 70 is arranged with a gap above the bus bar holder 140. The size of the gap between the circuit board 70 and the bus bar holder 140 is the size by which the spacer 143 protrudes upward from the bus bar holder 140.

[0033] The bus bar holder 140 has a peripheral wall portion 141 that extends downward. The peripheral wall portion 141 is located at a position radially outside the outer peripheral surface 24b of the stator 23. The peripheral wall portion 141 is located at a position radially inside the outer peripheral surface 24a of the stator 23. The lower end portion of the peripheral wall portion 141 is in contact with the upper side of the stator 23 when the bus bar holder 140 is screwed and fixed to the support surface 12.

[0034] When the bus bar holder 140 is screwed and fixed to the support surface 12 of the lower housing 11A, the lower end portion of the peripheral wall portion 141 is in contact with the upper side of the stator 23, whereby the stator 23 supported from below by the partition member 15 is axially positioned and fixed to the lower housing 11A.

[0035] As Figure 2As shown, the peripheral wall portion 141 of the bus bar holder 140 has a protruding portion 142 that protrudes radially inward. The protruding portion 142 extends axially. The circumferential position of the protruding portion 142 is the same as the circumferential position of the slot portion 27 of the stator 23. The protruding portion 142 is opposed to the slot portion 27 in the radial direction. The protruding portion 142 that protrudes radially inward of the peripheral wall portion 141 is inserted into the slot portion 27. The bus bar holder 140 with the protruding portion 142 inserted into the slot portion 27 and the stator 23 are positioned in the circumferential direction. When the bus bar holder 140 is received in the substrate receiving portion 13a while inserting the protruding portion 142 from above into the slot portion 27 that opens upward, the bus bar holder 140 can be positioned in the circumferential direction relative to the stator 23 and the lower housing 11A. Therefore, when the bus bar holder 140 is screwed to the support surface 12 of the lower housing 11A, the bus bar holder 140, the stator 23, and the lower housing 11A can be positioned relative to each other in the circumferential and axial directions.

[0036] The bus bar holder 140 holds the magnetic sensor 63, the wire 64, and the plurality of bus bars 150. In the present embodiment, the bus bar holder 140, the magnetic sensor 63, the wire 64, the spacer 143, and the plurality of bus bars 150 are an integrally formed body by resin molding. More specifically, the bus bar holder 140 is produced by insert molding with the magnetic sensor 63, the wire 64, the spacer 143, and the bus bar 150 as insert parts.

[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 fixed to the lower side of the bus bar holder 140. The magnetic sensor 63 is arranged to face the upper side of the magnet with a gap therebetween. As Figure 2 shown, three magnetic sensors 63 are arranged at intervals in the circumferential direction. The circumferential intervals between the magnetic sensors 63 are the same as the circumferential intervals of the magnetic poles. The magnetic sensor 63 detects the rotational position of the magnet 40 by detecting the magnetic field of the magnet 40, thereby detecting the rotation of the motor shaft 21.

[0038] In the electric actuator 10 according to the present embodiment, since the magnetic sensor 63 arranged on the bus bar holder 140 detects the magnetic field of the magnet 40, there is no need for an additional remaining substrate for mounting the magnetic sensor. In the electric actuator 10 according to the present embodiment, the magnetic sensor 63 and the bus bar holder 140 are an integrally formed body by resin molding, and when the bus bar holder 140 is screwed and assembled to the support surface 12 of the lower housing 11A, it can be positioned in the circumferential and axial directions with respect to the stator 23. In the electric actuator 10 according to the present embodiment, it is possible to suppress the reduction in the accuracy of the rotation control of the motor due to the advance angle deviation caused by the assembly accuracy.

[0039] One end of the conductive wire 64 is electrically connected to the magnetic sensor 63. The conductive wire 64 can be a terminal extending from the magnetic sensor 63 or a bus bar with one end side connected to the magnetic sensor 63. The conductive wire 64 penetrates through the bus bar holder 140 from inside the bus bar holder 140, and the other end side is electrically connected to the circuit board 70 by connection methods such as soldering, welding, and press-fitting.

[0040] The circuit board 70 is in a plate shape extending in a plane perpendicular to the axial direction. The circuit board 70 is housed in the lower housing 11A. More specifically, the circuit board 70 is housed in the substrate housing portion 13a. 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 unit 20. That is, an inverter circuit is mounted on the circuit board 70, for example.

[0041] As Figure 3 shown, one end portion 150a of the bus bar 150 holds the coil lead wire drawn out from the coil 23b of the stator 23 and is connected to the coil 23b by soldering or welding. The other end portion 150b of the bus bar 150 protrudes upward from the upper surface of the bus bar holder 140. In the present embodiment, the other end portion 150b of the bus bar 150 penetrates the circuit board 70 from the lower side to the upper side. The end portion 150b is electrically connected to the circuit board 70 by connection methods such as soldering, welding, and press-fitting at the position where it penetrates the circuit board 70. Thus, the circuit board 70 is electrically connected to the motor unit 20 via the bus bar 150.

[0042] 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 partition member 15 is disposed axially between the stator 23 and the reduction mechanism 30. The reduction mechanism 30 includes an external gear 31, an internal gear 32, an output portion 46, and a plurality of protruding portions 43.

[0043] The external gear 31 is in an annular plate shape extending in the radial direction of the eccentric axis J2 with the eccentric axis J2 of the eccentric shaft portion 21b as the center. 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 circumference 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 eccentric shaft portion 21b of the motor shaft 21 via the third bearing 52. Thus, the motor shaft 21 is connected to the reduction mechanism 30. The external gear 31 is fitted with the outer ring of the third bearing 52 from the radial outside. The eccentric shaft portion 21b is fitted with the inner ring of the third bearing 52 from the radial outside. Thus, the third bearing 52 connects the motor shaft 21 and the external gear 31 so as to be relatively rotatable about the eccentric axis J2.

[0045] In the present embodiment, the external gear 31 has a plurality of hole portions 31a. In the present embodiment, the hole portions 31a penetrate the external gear 31 in the axial direction. The plurality of hole portions 31a are arranged along the circumferential direction. More specifically, the plurality of hole portions 31a are arranged at equal intervals within one circumference along the circumferential direction centered on the eccentric axis J2. When observed in the axial direction, the hole portions 31a are circular in shape. The inner diameter of the hole portions 31a is larger than the outer diameter of the protruding portions 43. Additionally, the hole portions 31a may be holes with bottoms.

[0046] The internal gear 32 is located on the radially outer side of the external gear 31 and is annular, surrounding the external gear 31. In the present embodiment, the internal gear 32 is circularly annular centered on the central axis J1. The radially outer edge portion of the internal gear 32 is disposed in a stepped portion 13e that is recessed radially inward on the inner circumferential surface of the housing cylinder portion 13b and is fixed. Thus, the speed reduction mechanism 30 is held by the lower housing 11A. The internal gear 32 meshes with the external gear 31. A gear portion is provided on the radially inner side surface of the internal gear 32. The gear portion of the internal gear 32 has a plurality of tooth portions arranged along the inner circumference 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 on a part of the circumferential direction.

[0047] The output portion 46 is in the shape of an annular plate that extends radially centered on 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 plurality of protruding portions 43 are fixed to the output portion 46, for example, by 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 protruding portions 43 are cylindrical. The plurality of protruding portions 43 are arranged along the circumferential direction. More specifically, the plurality of protruding portions 43 are arranged at equal intervals within one circumference along the circumferential direction centered on the central axis J1. The number of the protruding portions 43 is, for example, eight.

[0049] The plurality of protruding portions 43 are respectively inserted into the plurality of hole portions 31a. The outer circumferential surface of the protruding portion 43 is inscribed in the inner circumferential surface of the hole portion 31a. Thus, the plurality of protruding portions 43 support the external gear 31 via the inner side surface of the hole portion 31a so as to be swingable about the central axis J1.

[0050] In the present embodiment, when observed along the radial direction, the hole portions 31a and the protruding portions 43 overlap with the third bearing 52 and the second shaft portion 21b. In other words, the hole portions 31a, the protruding portions 43, the third bearing 52, and the second shaft portion 21b respectively have portions that are located at the same position in the axial direction.

[0051] When the motor shaft 21 rotates about the central axis J1, the second shaft portion 21b, which is an eccentric shaft portion, revolves circumferentially about 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 swings while the position where the inner peripheral surface of the hole portion 31a is inscribed with the outer peripheral surface of the protruding portion 43 changes. As a result, the position where 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.

[0052] Here, in the present embodiment, the internal gear 32 is fixed and thus does not 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 direction in which the external gear 31 rotates is opposite to the direction in which the motor shaft 21 rotates. The rotation of the external gear 31 about the eccentric axis J2 is transmitted to the output portion 46 via the hole portion 31a and the protruding portion 43. As a result, the output shaft 41 rotates about the central 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.

[0053] The rotation of the output shaft 41 is decelerated with respect to the rotation of the motor shaft 21 by the speed reduction mechanism 30. Specifically, in the structure of the speed reduction mechanism 30 of the present embodiment, the reduction ratio R of the rotation of the output shaft 41 with respect to the rotation of the motor shaft 21 is represented by R = -(N2 - N1) / N2. The negative sign at the beginning of the expression representing the reduction ratio R indicates the direction with respect to the rotation of the motor shaft 21, and the direction of rotation of the decelerated output shaft 41 is the opposite direction. 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] In this way, according to the speed reduction mechanism 30 of the present embodiment, the reduction ratio R of the rotation of the output shaft 41 with respect to the rotation of the motor shaft 21 can be made large. Therefore, the rotational torque of the output shaft 41 can be made large.

[0055] The electric actuator to which the present invention is applied may be any device that can move an object by being supplied with power, and may also be a motor without a speed reduction mechanism. In addition, the electric actuator may be an electric pump having a pump portion driven by a motor portion. The use of the electric actuator is not particularly limited. The electric actuator may also be mounted on a by-wire type actuator device that is driven according to the shift operation of the driver. In addition, the electric actuator may also be mounted on equipment other than a vehicle. In addition, the respective structures described in this specification can be appropriately combined within a range where they do not conflict with each other.

Claims

1. An electric actuator having: A motor shaft driven by a motor unit to rotate about a central axis, the motor shaft having a through hole in the axial direction; An output shaft, one axial side of which is inserted into the through hole, and the rotation of the motor shaft is transmitted to the output shaft; and A reduction mechanism connected to a portion on the other axial side of the motor shaft, On the other axial side of the motor shaft, an axial recess connected to the through hole is provided, On the other axial side of the output shaft, a connecting portion is provided, and the connecting portion is connected to a driven body that receives the rotation of the output shaft from the other axial side, One axial side of the connecting portion is inserted into the recess, The motor unit has a rotor capable of rotating about the central axis, The motor shaft has: A first shaft portion fixed to the rotor; and A second shaft portion located on the other axial side of the first shaft portion, the diameter of the second shaft portion being larger than the diameter of the first shaft portion, The motor shaft is supported by a third bearing at the second shaft portion, The recess is provided in the second shaft portion, and at least a part of the recess overlaps with the third bearing when viewed from a direction perpendicular to the axial direction.

2. The electric actuator according to claim 1, wherein Both the end on the one axial side and the end on the other axial side of the output shaft protrude from the motor shaft, The end on the one axial side of the output shaft is supported on the housing via a first bearing, The connecting portion at the end on the other axial side of the output shaft is supported on the housing via a second bearing.

3. The electric actuator according to claim 1 or 2, wherein The connecting portion has a cylindrical portion, The inner diameter of the cylindrical portion has a connecting recess for connecting to the driven body.

4. The electric actuator according to claim 1 or 2, wherein The motor unit has a stator that is radially opposed to the rotor with a gap therebetween, The stator has: A stator core in a circumferential ring shape; and An insulating member mounted on the stator core, The end on the one axial side of the third bearing is axially located between the end on the other axial side of the rotor and the end on the other axial side of the insulating member.

5. The electric actuator according to claim 1 or 2, wherein The rotation of the motor shaft is transmitted to the output shaft via the reduction mechanism.

6. The electric actuator according to claim 3, wherein When viewed from a direction perpendicular to the axial direction, the connecting recess at least partially overlaps with the reduction mechanism.

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