Electric actuator

Abstract

The utility model provides an electric actuator. The present invention is provided with: a motor having a motor shaft capable of rotating about a motor axis; an output shaft to which the rotation of the motor shaft is decelerated and transmitted; a first bearing that rotatably supports a portion on one axial side of one of the motor shaft and the output shaft; a second bearing that rotatably supports a portion of the one shaft on the other side in the axial direction; a first holding portion that holds the first bearing; and a second holding portion that holds the second bearing. The first bearing has: a first inner ring section fixed to one shaft; a first outer ring portion supported by the first holding portion from one side in the axial direction; and a plurality of first rolling bodies. The second bearing has: a second inner ring section fixed to the one shaft; a second outer ring portion supported by the second holding portion from the other side in the axial direction; and a plurality of second rolling bodies. The second holding portion has an elastic deformation portion that elastically deforms toward the other axial side and applies a force toward the one axial side to the second outer ring portion.

Description

Technical Field

[0001] The utility model relates to an electric actuator. Background Art

[0002] There is known an actuator which applies pressure to a bearing that rotatably supports a shaft body by means of an elastic member such as a wave washer, thereby suppressing the rattling of the shaft body (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2017-215019

[0005] The actuator as described above has an elastic component that applies pressure to the bearing, so the number of components of the actuator increases. In addition, since the elastic component needs to be assembled on the shaft body and the bearing, the manufacturing man-hour of the linear actuator increases. As a result, the manufacturing cost of the linear actuator increases. Utility Model Content

[0006] In view of the above situation, one of the objects of the present invention is to provide an electric actuator capable of suppressing an increase in manufacturing cost.

[0007] One mode of the electric actuator of the utility model comprises: a motor having a motor shaft rotatable about a motor axis; an output shaft to which the rotation of the motor shaft is decelerated and transmitted; a first bearing rotatably supporting a portion of one of the motor shaft and the output shaft on one axial side; a second bearing rotatably supporting a portion of the other axial side of the one shaft; a first retaining portion retaining the first bearing; and a second retaining portion retaining the second bearing. The first bearing comprises: a first inner ring portion fixed to the one shaft; a first outer ring portion arranged to face the first inner ring portion in a radial direction and supported by the first retaining portion from one axial side; and a plurality of first rolling elements located between the first inner ring portion and the first outer ring portion in a radial direction. The second bearing comprises: a second inner ring portion fixed to the one shaft; a second outer ring portion arranged to face the second inner ring portion in a radial direction and supported by the second retaining portion from the other axial side; and a plurality of second rolling elements located between the second inner ring portion and the second outer ring portion in a radial direction. The second holding portion includes an elastic deformation portion that elastically deforms toward the other axial side to apply a force toward the one axial side to the second outer ring portion.

[0008] The invention comprises a shell body for accommodating the motor shaft and the output shaft, the second retaining portion comprises a mounting portion mounted on the shell body, the elastic deformation portion comprises a retaining portion for retaining the second bearing and a connecting portion connecting the mounting portion and the retaining portion, and the axial dimension of the connecting portion is smaller than the axial dimension of the mounting portion.

[0009] The motor shaft is a hollow shaft, at least a portion of the output shaft is located inside the motor shaft, the output shaft is rotatable around the motor axis, the one shaft is the output shaft, and the housing body has the first retaining portion.

[0010] The housing body has an opening portion that opens to the other side in the axial direction, and the second holding portion is fixed to the housing body to close the opening portion.

[0011] The motor shaft is arranged on the other axial side of the output shaft, the output shaft is rotatable around the motor axis, the one shaft is the motor shaft, and the output shaft has the first holding portion.

[0012] The effects of the utility model are as follows.

[0013] According to one aspect of the present invention, it is possible to suppress an increase in the manufacturing cost of the electric actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a cross-sectional view showing the electric actuator according to the first embodiment.

[0015] Figure 2 This is a diagram of the transmission mechanism according to the first embodiment as viewed from the other axial side.

[0016] Figure 3 It is a first partially enlarged cross-sectional view showing the electric actuator according to the first embodiment.

[0017] Figure 4 This is a second partially enlarged cross-sectional view showing the electric actuator according to the first embodiment.

[0018] Figure 5 It is a cross-sectional view showing an electric actuator according to a second embodiment.

[0019] Figure 6 It is a first partially enlarged cross-sectional view showing the electric actuator according to the second embodiment.

[0020] Figure 7 It is a second partially enlarged cross-sectional view showing the electric actuator according to the second embodiment.

[0021] In the figure: 1, 201 - electric actuator, 11, 211 - housing body, 11f, 241a - first holding portion, 11m - opening portion, 12, 250 - second holding portion, 12a, 250a - mounting portion, 12d, 250c - elastic deformation portion, 12e, 250d - connecting portion, 12g, 250e - holding portion, 20, 220 - motor, 23, 221 - motor shaft, 46, 2 41—output shaft, 51, 257—first bearing, 51a, 257a—first inner ring portion, 51b, 257b—first outer ring portion, 51c, 257c—first rolling element, 52, 258—second bearing, 52a, 258a—second inner ring portion, 52b, 258b—second outer ring portion, 52c, 258c—second rolling element, J1, J3—motor axis, J2, J4—eccentric axis. DETAILED DESCRIPTION

[0022] In each figure, the Z-axis direction is an up-down direction with the positive side (+Z side) as the upper side and the negative side (-Z side) as the lower side. In the present embodiment, the lower side is equivalent to "one axial side" and the upper side is equivalent to "the other axial side". In addition, the up-down direction, the upper side and the lower side are names used only to explain the relative positional relationship of each part, and the actual configuration relationship may be a configuration relationship other than the configuration relationship indicated by these names.

[0023] <First embodiment>

[0024] The axial direction, which is the direction in which the motor axis J1 extends, shown appropriately in each figure, is parallel to the Z-axis direction, that is, the up-down direction. In the following description, the direction parallel to the axial direction of the motor axis J1 is simply referred to as the "axial direction". In addition, the radial direction centered on the motor axis J1 is simply referred to as the "radial direction", and the circumferential direction centered on the motor axis J1 is simply referred to as the "circumferential direction". In each figure, the circumferential direction is indicated by an arrow θ1.

[0025] Figure 1 The electric actuator 1 of the present embodiment shown is mounted on a vehicle. More specifically, the electric actuator 1 is mounted on, for example, an actuator device of a parking-by-wire system that is driven based on a shift operation of a driver of the vehicle. The electric actuator 1 includes a housing 10, a motor 20, a transmission mechanism 30, an output shaft 46, a first bearing 51, a second bearing 52, a third bearing 53, a control substrate 80, a rotation sensor 81, and a sensor magnet 45. In the present embodiment, the first bearing 51 and the second bearing 52 are ball bearings.

[0026] The housing 10 accommodates various parts of the electric actuator 1 including the motor 20, the transmission mechanism 30 and the output shaft 46. The housing 10 has a housing body 11 and a second retaining portion 12. That is, the electric actuator 1 has a second retaining portion 12. The housing body 11 is cylindrical with the motor axis J1 as the center. In the present embodiment, the housing body 11 is made of metal. The housing body 11 can be made of resin. The housing body 11 has an opening 11m that is open on the upper side, that is, on the other side of the axis. The housing body 11 has a first storage portion 11a and a second storage portion 11b.

[0027] The first storage portion 11a is a portion on the lower side of the housing body 11. The first storage portion 11a includes a bottom wall portion 11c, a peripheral wall portion 11d, and a first retaining portion 11f. That is, the electric actuator 1 includes the first retaining portion 11f. The bottom wall portion 11c is in the shape of an annular plate centered on the motor axis J1. The plate surface of the bottom wall portion 11c faces the axial direction. The peripheral wall portion 11d is in the shape of a cylinder extending upward from the radial outer edge of the bottom wall portion 11c.

[0028] The first retaining portion 11f retains the first bearing 51. The first retaining portion 11f includes a first cylindrical portion 11g and a first supporting portion 11h. The first cylindrical portion 11g is cylindrical with the motor axis J1 as the center. The first cylindrical portion 11g protrudes downward from the radial inner edge of the bottom wall portion 11c. The first cylindrical portion 11g supports the first bearing 51 from the radial outer side.

[0029] The first support portion 11h is in the shape of an annulus centered on the motor axis J1. The first support portion 11h protrudes radially inward from the lower end of the first tubular portion 11g. The first support portion 11h is located at a position lower than the first bearing 51. The first support portion 11h has a first support surface 11i. The first support surface 11i is a surface facing upward on the outer surface of the first support portion 11h. The first support surface 11i is in contact with the first bearing 51 in the axial direction. Therefore, the first support portion 11h supports the first bearing 51 from the lower side.

[0030] The second housing portion 11b is the upper portion of the housing body 11. The second housing portion 11b is connected to the first housing portion 11a in the axial direction. The second housing portion 11b is in the shape of a tube opened upward. A step having a step surface 11k facing upward is provided on the inner peripheral surface of the second housing portion 11b.

[0031] The second holding portion 12 is fixed to the upper end of the housing body 11. The second holding portion 12 blocks the opening 11m of the housing body 11 from the upper side. In this embodiment, the second holding portion 12 is made of metal. The second holding portion 12 can be made of resin. The second holding portion 12 has a mounting portion 12a, an annular protrusion 12b, and an elastic deformation portion 12d.

[0032] The mounting portion 12a is a portion of the second retaining portion 12 that is fixed to the housing body 11. The mounting portion 12a is in the shape of an annular plate that surrounds the motor axis J1. The plate surface of the mounting portion 12a faces the axial direction. The surface of the mounting portion 12a that faces downward is in contact with the upper end of the second storage portion 11b in the axial direction. The mounting portion 12a is fixed to the housing body 11 by bolts that are not shown. Thus, the second retaining portion 12 is fixed to the housing body 11.

[0033] The annular protrusion 12b is annular and surrounds the motor axis J1. The annular protrusion 12b protrudes downward from the radial inner edge of the mounting portion 12a. The outer peripheral surface of the annular protrusion 12b contacts the inner peripheral surface of the second housing portion 11b in the radial direction. Thus, the radial position of the second retaining portion 12 relative to the housing body 11 is determined.

[0034] The elastic deformation portion 12d blocks the opening portion 11m from the upper side. The elastic deformation portion 12d elastically deforms toward the upper side, and applies an elastic force toward the lower side to the second bearing 52. The elastic deformation portion 12d has a connecting portion 12e and a retaining portion 12g. The connecting portion 12e is in the shape of an annular plate centered on the motor axis J1. The plate surface of the connecting portion 12e faces the axial direction. The radial outer edge of the connecting portion 12e is connected to the radial inner edge of the mounting portion 12a. The radial inner edge of the connecting portion 12e is connected to the retaining portion 12g. The connecting portion 12e connects the mounting portion 12a and the retaining portion 12g. The axial dimension of the connecting portion 12e is smaller than the axial dimension of the mounting portion 12a.

[0035] The retaining portion 12g retains the second bearing 52. Thus, the second retaining portion 12 retains the second bearing 52. The retaining portion 12g is cylindrical and protrudes in the axial direction with the motor axis J1 as the center. The retaining portion 12g is open at the lower side. The inner peripheral surface of the retaining portion 12g supports the second bearing 52 from the radially outer side. The retaining portion 12g has a second support portion 12h.

[0036] The second support portion 12h protrudes radially inward from a portion of the upper end side of the inner side surface of the retaining portion 12g. The second support portion 12h is in the shape of an annulus centered on the motor axis J1. The second support portion 12h is located above the second bearing 52. The second support portion 12h has a second support surface 12i. The second support surface 12i is a surface facing downward on the outer side surface of the second support portion 12h. The second support surface 12i is in contact with the second bearing 52 in the axial direction. Therefore, the second support portion 12h supports the second bearing 52 from the upper side.

[0037] As described above, the axial dimension of the connecting portion 12e is smaller than the axial dimension of the mounting portion 12a. Therefore, in the present embodiment, it is easy to reduce the axial rigidity of the connecting portion 12e. Thus, it is easy to reduce the rigidity of the elastic deformation portion 12d. In addition, as described above, the radial outer edge of the connecting portion 12e is connected to the mounting portion 12a fixed to the housing body 11. Therefore, when a force in the axial direction is applied to the retaining portion 12g, the connecting portion 12e is elastically deformed in the axial direction with the radial outer edge as a fixed end. Thus, the retaining portion 12g moves in the axial direction.

[0038] The motor 20 is arranged inside the housing body 11. The motor 20 has a rotor 21 and a stator 22. The rotor 21 can rotate around the motor axis J1. The rotor 21 has a motor shaft 23, a rotor core 24a, and a magnet 24b. The motor shaft 23 can rotate around the motor axis J1. The motor shaft 23 is roughly cylindrical and extends axially around the motor axis J1. The motor shaft 23 is housed inside the housing body 11. The motor shaft 23 is a hollow shaft. The motor shaft 23 is open on both sides of the axial direction. The motor shaft 23 has a main body 23a and an eccentric shaft 23b.

[0039] The main body 23a is the upper portion of the motor shaft 23. The rotor core 24a is fixed to the outer peripheral surface of the main body 23a. The upper end of the main body 23a is arranged inside the second housing portion 11b. The portion of the main body 23a other than the upper end is arranged inside the first housing portion 11a.

[0040] The eccentric shaft portion 23b is a portion on the lower side of the motor shaft 23. The eccentric shaft portion 23b is connected to the main body portion 23a in the axial direction. The eccentric shaft portion 23b is arranged at a position lower than the rotor core 24a. When viewed from the axial direction, the inner peripheral surface of the eccentric shaft portion 23b is a circular shape centered on the motor axis J1. When viewed from the axial direction, the outer peripheral surface of the eccentric shaft portion 23b is a circular shape centered on the eccentric axis J2 that is eccentric relative to the motor axis J1. The eccentric axis J2 is an imaginary axis parallel to the motor axis J1. The inner ring portion of the third bearing 53 is fitted and fixed to the outer peripheral surface of the eccentric shaft portion 23b.

[0041] The rotor core 24a is annular and centered at the motor axis J1. The rotor core 24a is fixed to the outer peripheral surface of the main body 23a. The magnet 24b is fixed to the rotor core 24a. A plurality of magnets 24b are arranged at intervals in the circumferential direction.

[0042] The stator 22 is arranged radially outside the rotor 21 with a gap therebetween. The stator 22 includes: an annular stator core 22a surrounding the rotor core 24a from the radial outside; an insulator 22b mounted on the stator core 22a; and a plurality of coil portions 22c mounted on the stator core 22a via the insulator 22b. The outer peripheral surface of the stator core 22a is fixed to the inner peripheral surface of the peripheral wall portion 11d.

[0043] The transmission mechanism 30 is arranged inside the first storage portion 11a. The transmission mechanism 30 is arranged on the lower side of the rotor core 24a and the stator 22. The transmission mechanism 30 is connected to the motor shaft 23 and the output shaft 46. In the present embodiment, the transmission mechanism 30 is a speed reduction mechanism that reduces the rotation of the motor shaft 23 around the motor axis J1 and transmits it to the output shaft 46. The transmission mechanism 30 may be a speed increase mechanism that increases the rotation of the rotor 21 and transmits it to the output shaft 46, or may be a transmission mechanism that transmits the rotation at the same rotation speed as the rotation of the rotor 21 to the output shaft 46. The transmission mechanism 30 includes an external gear 31, an internal gear 32, a flange portion 42, and a plurality of protrusions 43.

[0044] The external gear 31 is annular with the eccentric axis J2 as the center. The external gear 31 is engaged with the outer ring portion of the third bearing 53. The external gear 31 is connected to the eccentric shaft portion 23b of the motor shaft 23 via the third bearing 53. Thus, the rotation of the motor shaft 23 is transmitted to the external gear 31. The external gear 31 can rotate relative to the motor shaft 23 around the eccentric axis J2. Figure 2 As shown, the external gear 31 has a plurality of through-hole portions 31 b and an external gear portion 31 c.

[0045] In the present embodiment, the plurality of through-hole portions 31b are holes that penetrate the external gear 31 in the axial direction. When viewed in the axial direction, the plurality of through-hole portions 31b are circular. The plurality of through-hole portions 31b are arranged around the motor axis J1. In the present embodiment, eight through-hole portions 31b are provided. The external gear portion 31c is provided along the outer peripheral surface of the external gear 31. The external gear portion 31c is composed of a plurality of external tooth portions 31d arranged along the outer peripheral surface of the external gear 31.

[0046] The internal gear 32 is disposed radially outside the external gear 31. The internal gear 32 surrounds the external gear 31 from the radial outside. The internal gear 32 is annular with the motor axis J1 as the center. Figure 1 As shown in FIG. 1 , the outer peripheral surface of the internal gear 32 is fixed to the inner peripheral surface of the peripheral wall portion 11d. Figure 2 As shown, the internal gear 32 has an internal gear portion 32a. The internal gear portion 32a is provided along the inner peripheral surface of the internal gear 32. The internal gear portion 32a is composed of a plurality of internal gear portions 32b arranged along the inner peripheral surface of the internal gear 32.

[0047] like Figure 1 As shown, the flange 42 is disposed below the external gear 31. The flange 42 is disposed axially spaced apart from the external gear 31. The flange 42 is annular centered on the motor axis J1. The flange 42 is fixed to the output shaft 46. A plurality of protrusions 43 are provided on the flange 42.

[0048] In this embodiment, the plurality of protrusions 43 are cylindrical in shape and protrude upward from the flange 42. Figure 2 As shown in FIG. 1 , the outer diameter of the protrusion 43 is smaller than the inner diameter of the through hole 31 b. The plurality of protrusions 43 are arranged around the motor axis J1. In the present embodiment, eight protrusions 43 are provided. Figure 1 As shown, each protrusion 43 is inserted into a different through hole portion 31b from the bottom. Figure 2 As shown, each protrusion 43 supports the external gear 31 via the inner side surface of the through hole portion 31 b so as to be swingable about the motor axis J1 .

[0049] like Figure 1 As shown, the output shaft 46 extends in the axial direction. The output shaft 46 is housed inside the housing body 11. The output shaft 46 can rotate around the motor axis J1. The rotation of the motor shaft 23 is decelerated and transmitted to the output shaft 46 via the transmission mechanism 30. The output shaft 46 passes through the inside of the motor shaft 23 in the axial direction. The output shaft 46 protrudes from the motor shaft 23 to both sides in the axial direction. That is, at least a portion of the output shaft 46 is located inside the motor shaft 23. The output shaft 46 has an output shaft body 41 and a mounting component 44.

[0050] The output shaft body 41 extends in the axial direction. The output shaft body 41 is supported by the first bearing 51 and the second bearing 52 so as to be rotatable about the motor axis J1. That is, the first bearing 51 and the second bearing 52 rotatably support the output shaft 46. The output shaft body 41 has a connecting portion 41a and an extending portion 41b.

[0051] The connecting portion 41a is a portion on the lower side of the output shaft body 41. The connecting portion 41a is cylindrical and extends axially with the motor axis J1 as the center. The connecting portion 41a is open at the lower side. The lower end of the connecting portion 41a is inserted into the interior of the first cylindrical portion 11g. The upper end of the connecting portion 41a is inserted into the interior of the eccentric shaft portion 23b. The connecting portion 41a is supported by the first bearing 51 so as to be rotatable around the motor axis J1.

[0052] A driven shaft (not shown) can be inserted from the bottom inside the connecting portion 41a. When the spline groove provided on the outer circumference of the driven shaft is engaged with the spline groove provided on the inner circumference of the connecting portion 41a, the connecting portion 41a and the driven shaft are connected to each other. Thus, the rotation of the motor shaft 23 is transmitted to the driven shaft via the output shaft 46.

[0053] The extension portion 41b is a portion on the upper side of the output shaft body 41. The extension portion 41b is cylindrical and extends axially with the motor axis J1 as the center. The extension portion 41b is connected to the connecting portion 41a in the axial direction. The extension portion 41b passes through the interior of the motor shaft 23 in the axial direction. The upper portion of the extension portion 41b protrudes upward from the motor shaft 23. The upper end of the extension portion 41b is supported by the second bearing 52 so as to be rotatable around the motor axis J1. As described above, the connecting portion 41a is supported by the first bearing 51 so as to be rotatable around the motor axis J1. That is, the first bearing 51 and the second bearing 52 respectively support one of the motor shaft 23 and the output shaft 46, namely the output shaft 46, so as to be rotatable. In the present embodiment, one shaft is the output shaft 46.

[0054] According to the present embodiment, the motor shaft 23 is a hollow shaft, at least a portion of the output shaft 46 is located inside the motor shaft 23, the output shaft 46 can rotate around the motor axis J1, one shaft is the output shaft 46, and the housing body 11 has a first retaining portion 11f. Therefore, since the output shaft 46 can be arranged inside the motor shaft 23, it is possible to suppress the electric actuator 1 from being enlarged in the radial direction.

[0055] In addition, in this embodiment, since the housing body 11 has the first holding portion 11f as described above, the number of components of the electric actuator 1 can be suppressed from increasing compared to a structure having a component that holds the first bearing 51 separately from the housing body 11. Therefore, an increase in the manufacturing cost of the electric actuator 1 can be suppressed.

[0056] The mounting member 44 is fixed to a portion of the outer peripheral surface of the extension portion 41b that is above the motor shaft 23. The mounting member 44 includes a fixed cylinder portion 44a and an annular portion 44b. The fixed cylinder portion 44a is cylindrical in shape with the motor axis J1 as the center and open on both sides in the axial direction. The fixed cylinder portion 44a is fixed to the outer peripheral surface of the extension portion 41b. The annular portion 44b is in the shape of a substantially annular plate that expands radially outward from the lower end of the fixed cylinder portion 44a.

[0057] The sensor magnet 45 is annular and surrounds the motor axis J1. The sensor magnet 45 is fixed to the outer peripheral surface of the fixed cylinder portion 44a. The radial outer edge of the sensor magnet 45 is located radially outward of the annular portion 44b and faces the rotation sensor 81 in the axial direction.

[0058] A washer 61 is arranged between the lower end of the main body 23a of the motor shaft 23 and the upper end of the connecting portion 41a of the output shaft 46. The washer 61 is in the shape of an annular plate surrounding the extension portion 41b. The washer 61 is in axial contact with the main body 23a and the connecting portion 41a, respectively. In addition, a washer 62 is arranged between the upper end of the main body 23a and the annular portion 44b. The washer 62 is in the shape of an annular plate surrounding the extension portion 41b. The washer 62 is in axial contact with the main body 23a and the annular portion 44b, respectively. The plate surfaces of the washers 61 and 62 face the axial direction. The washers 61 and 62 are, for example, sliding washers. The washers 61 and 62 reduce the friction between the motor shaft 23 and the output shaft 46.

[0059] like Figure 1 As shown, the control substrate 80 is arranged at a position above the stator 22. The control substrate 80 is fixed to the step surface 11k of the housing 10. The control substrate 80 is a plate-shaped body extending in the radial direction. Although the illustration is omitted, an inverter circuit for supplying power to the motor 20 is provided on the control substrate 80. Although the illustration is omitted, the control substrate 80 is electrically connected to the plurality of coil portions 22c. The control substrate 80 controls the power supplied to the plurality of coil portions 22c. A through hole 80a is provided on the control substrate 80. When viewed in the axial direction, the through hole 80a is a circular shape centered on the motor axis J1. The extension portion 41b of the output shaft 46 passes through the through hole 80a in the axial direction. A rotation sensor 81 is mounted on the control substrate 80.

[0060] The rotation sensor 81 is fixed to the peripheral edge of the through hole 80a in the upper surface of the control substrate 80. The rotation sensor 81 is axially opposed to the radial outer edge of the sensor magnet 45. In the present embodiment, the rotation sensor 81 is a magnetic sensor. The rotation sensor 81 is, for example, a Hall element such as a Hall IC. The rotation sensor 81 detects the rotation of the output shaft 46 by detecting the magnetic field of the sensor magnet 45.

[0061] Next, the rotation transmission structure in which the rotation of the motor shaft 23 is reduced in speed and transmitted to the output shaft 46 through the transmission mechanism 30 in this embodiment is described. When the motor 20 is supplied with electric power from the control substrate 80 and the motor shaft 23 rotates around the motor axis J1, the eccentric shaft portion 23b revolves in the circumferential direction around the motor axis J1. The revolving of the eccentric shaft portion 23b is transmitted to the external gear 31 via the third bearing 53. The external gear 31 revolves around the motor axis J1 while changing the contact position between the inner peripheral surface of the through hole portion 31b and the outer peripheral surface of the protrusion 43. When the external gear 31 revolves around the motor axis J1, the meshing position of the external gear portion 31c of the external gear 31 and the internal gear portion 32a of the internal gear 32 changes in the circumferential direction. As a result, the driving force of the motor shaft 23 is transmitted to the internal gear 32 via the external gear 31.

[0062] As described above, the internal gear 32 is fixed to the housing 10. Therefore, the external gear 31 rotates around the eccentric axis J2 by ​​the reaction force of the driving force transmitted to the internal gear 32. At this time, the rotation of the external gear 31 is decelerated relative to the rotation of the motor shaft 23. The rotation of the external gear 31 is transmitted to the flange portion 42 via the inner side surface of the through hole portion 31b and the protrusion 43, and the flange portion 42 rotates around the motor axis J1. As described above, the output shaft 46 is fixed to the flange portion 42, so the output shaft 46 rotates around the motor axis J1 together with the flange portion 42. In this way, the rotation of the motor shaft 23 is transmitted to the output shaft 46 via the transmission mechanism 30.

[0063] like Figure 1 As shown, the first bearing 51 is arranged at a lower side than the transmission mechanism 30. As described above, the first bearing 51 is a ball bearing. The first bearing 51 supports the connecting portion 41a of the output shaft 46 so that it can rotate around the motor axis J1. The first bearing 51 rotatably supports the lower side of the output shaft 46, that is, the portion on one side of the axial direction. The first bearing 51 rotatably supports the output shaft 46, that is, one shaft. Figure 3 As shown, the first bearing 51 includes a first inner ring portion 51 a , a first outer ring portion 51 b , a plurality of first rolling elements 51 c , and a first cage 51 d .

[0064] The first inner ring portion 51a is in the shape of a ring centered on the motor axis J1. The first inner ring portion 51a surrounds the connecting portion 41a. In the present embodiment, the first inner ring portion 51a is fixed to the connecting portion 41a. That is, the first inner ring portion 51a is fixed to the output shaft 46. The first inner ring portion 51a can be pressed into the connecting portion 41a, or can be fixed to the connecting portion 41a by adhesive.

[0065] The first outer ring portion 51b is in an annular shape centered on the motor axis J1. The first outer ring portion 51b surrounds the first inner ring portion 51a from the radially outer side. The first outer ring portion 51b and the first inner ring portion 51a are arranged opposite to each other in the radial direction. In the present embodiment, the first outer ring portion 51b is loosely fitted in the inner peripheral surface of the first cylindrical portion 11g of the first retaining portion 11f. Therefore, the first outer ring portion 51b is supported by the first retaining portion 11f from the radially outer side. The surface of the first outer ring portion 51b facing the lower side is in contact with the first support surface 11i of the first retaining portion 11f in the axial direction. Therefore, the first outer ring portion 51b is supported by the first retaining portion 11f from the lower side, that is, from one axial side. Thus, the axial position of the first bearing 51 relative to the housing body 11 is determined. In addition, as described above, the output shaft 46 is fixed to the first inner ring portion 51a. Therefore, the axial position of the output shaft 46 relative to the housing body 11 is determined via the first bearing 51.

[0066] A plurality of first rolling elements 51c are located between the first inner ring portion 51a and the first outer ring portion 51b in the radial direction. The plurality of first rolling elements 51c are arranged along the circumferential direction. Each first rolling element 51c is spherical. The first retainer 51d retains the plurality of first rolling elements 51c. The first retainer 51d is in the shape of an annulus centered on the motor axis J1. A plurality of retaining holes, not shown, are provided along the circumferential direction on the first retainer 51d. A plurality of first rolling elements 51c are retained in each retaining hole. Each first rolling element 51c protrudes from each retaining hole to both sides in the radial direction and contacts the first inner ring portion 51a and the first outer ring portion 51b. Thus, the first inner ring portion 51a and the first outer ring portion 51b can rotate relative to each other around the motor axis J1 via the plurality of first rolling elements 51c.

[0067] like Figure 1 As shown in FIG. 1 , the second bearing 52 is disposed above the sensor magnet 45. As described above, the second bearing 52 is a ball bearing. The second bearing 52 supports the extension portion 41b of the output shaft 46 so that it can rotate around the motor axis J1. That is, the second bearing 52 supports the output shaft 46, i.e., the upper side of one shaft, i.e., the portion on the other axial side, so that it can rotate. Figure 4 As shown, the second bearing 52 includes a second inner ring portion 52a, a second outer ring portion 52b, a plurality of second rolling elements 52c, and a second retainer 52d.

[0068] The second inner ring portion 52a is in the shape of a ring centered on the motor axis J1. The second inner ring portion 52a surrounds the extension portion 41b. In the present embodiment, the second inner ring portion 52a is fixed to the extension portion 41b. That is, the second inner ring portion 52a is fixed to the output shaft 46. The second inner ring portion 52a may be pressed into the extension portion 41b, or may be fixed to the extension portion 41b by adhesive.

[0069] The second outer ring portion 52b is in the shape of an annulus centered on the motor axis J1. The second outer ring portion 52b surrounds the second inner ring portion 52a from the radial outside. The second outer ring portion 52b and the second inner ring portion 52a are arranged opposite to each other in the radial direction. In the present embodiment, the second outer ring portion 52b is gap-fitted into the inner circumferential surface of the retaining portion 12g. Therefore, the second outer ring portion 52b is supported from the radial outside by the second retaining portion 12. The surface of the second outer ring portion 52b facing the upper side is in axial contact with the second support surface 12i of the second retaining portion 12. Therefore, the second outer ring portion 52b is supported by the second retaining portion 12 from the upper side, that is, from the other axial side.

[0070] A plurality of second rolling elements 52c are located between the second inner ring portion 52a and the second outer ring portion 52b in the radial direction. The plurality of second rolling elements 52c are arranged along the circumferential direction. Each second rolling element 52c is spherical. The second retainer 52d retains the plurality of second rolling elements 52c. The second retainer 52d is in the shape of an annulus centered on the motor axis J1. A plurality of retaining holes, not shown, are provided along the circumferential direction on the second retainer 52d. A plurality of second rolling elements 52c are retained in each retaining hole. Each second rolling element 52c protrudes from each retaining hole to both sides in the radial direction and contacts the second inner ring portion 52a and the second outer ring portion 52b. Thus, the second inner ring portion 52a and the second outer ring portion 52b can rotate relative to each other around the motor axis J1 via the plurality of second rolling elements 52c.

[0071] Figure 1 The first length L1 shown is the length in the axial direction between the upper end of the second housing portion 11 b of the case body 11 and the first supporting surface 11 i. Figure 4 The second length L2a before fixation shown is the length in the axial direction between the lower end of the mounting portion 12a of the second holding portion 12 which is not fixed to the housing body 11 and the second supporting surface 12i. Figure 1 The third length L3 shown is the axial length between the lower end of the first outer ring portion 51b fixed to the output shaft 46 and the upper end of the second outer ring portion 52b. In the present embodiment, the third length L3 is longer than the first length L1 plus the second length L2a before fixing. Therefore, when the second retaining portion 12 is fixed to the housing body 11 to which at least the output shaft 46, the first bearing 51, and the second bearing 52 are mounted, a force is applied upward to the retaining portion 12g from the first bearing 51. As a result, as Figure 4 As shown in FIG. 1 , the connection portion 12e of the elastic deformation portion 12d is elastically deformed upward, i.e., in the other axial direction, and the holding portion 12g moves upward. Therefore, the axial length between the lower end of the mounting portion 12a of the second holding portion 12 fixed to the housing body 11 and the second supporting surface 12i, i.e., the second length L2b after fixing is longer than the second length L2a before fixing. Figure 1 As shown, the length of the first length L1 plus the fixed second length L2b is the same as the third length L3.

[0072] like Figure 4As shown, since the elastic deformation portion 12d is elastically deformed toward the upper side, the elastic force Fe from the elastic deformation portion 12d toward the lower side is applied to the second outer ring portion 52b of the second bearing 52. That is, the elastic deformation portion 12d applies a force toward the lower side, that is, one axial side, to the second outer ring portion 52b. Therefore, the second retaining portion 12 and the second bearing 52 are stably in contact in the axial direction. Therefore, the second outer ring portion 52b is stably supported from the upper side by the second retaining portion 12. In addition, as described above, since the second bearing 52 is fixed to the output shaft 46, an elastic force Fe toward the lower side is applied to the output shaft 46 via the second bearing 52. Thus, the output shaft 46 can be pressed downward by the elastic force Fe of the elastic deformation portion 12d. In addition, as described above, since the first bearing 51 is fixed to the output shaft 46, an elastic force Fe is applied to the first bearing 51 via the output shaft 46. Therefore, as Figure 3 As shown, the lower end of the first outer ring portion 51b of the first bearing 51 is stably in contact with the first support surface 11i in the axial direction. Therefore, the first outer ring portion 51b is stably supported by the first retaining portion 11f from the lower side. As a result, the output shaft 46 can be stably in contact with the first retaining portion 11f and the second retaining portion 12 in the axial direction via the first bearing 51 and the second bearing 52. Therefore, the position of the output shaft 46 relative to the housing body 11 can be determined with high accuracy.

[0073] According to the present embodiment, the electric actuator 1 includes: a motor 20 having a motor shaft 23; an output shaft 46; a first bearing 51 that rotatably supports a portion of the output shaft 46, i.e., a lower side, i.e., one side in the axial direction; a second bearing 52 that rotatably supports a portion of the output shaft 46, i.e., an upper side, i.e., the other side in the axial direction; a first retaining portion 11f that retains the first bearing 51; and a second retaining portion 12 that retains the second bearing 52. The first bearing 51 includes a first inner ring portion 51a fixed to the output shaft 46 and a first outer ring portion 51b supported from below by the first retaining portion 11f. The second bearing 52 includes a second inner ring portion 52a fixed to the output shaft 46 and a second outer ring portion 52b supported from above by the second retaining portion 12. The second retaining portion 12 includes an elastic deformation portion 12d that elastically deforms upward and applies a force downward to the second outer ring portion 52b. Therefore, as described above, by the elastic deformation portion 12d provided on the second retaining portion 12 that retains the second bearing 52, the elastic force Fe toward the lower side can be applied to the output shaft 46 via the second bearing 52. As a result, the output shaft 46 can be stably supported from the lower side by the first retaining portion 11f via the first bearing 51. Therefore, the axial position of the output shaft 46 relative to the first retaining portion 11f and the second retaining portion 12 can be determined with high accuracy, and the output shaft 46 can be suppressed from shaking in the axial direction. Therefore, in the present embodiment, there is no need to separately provide elastic components such as wave washers and spacer rings that apply elastic force to the output shaft 46 in the axial direction. Therefore, the increase in the number of components of the electric actuator 1 can be suppressed. In addition, compared with the structure in which the second retaining portion 12 is provided with an elastic component separately, it is unnecessary to assemble the elastic component on the second bearing 52 and the output shaft 46, etc., so the increase in the manufacturing man-hours of the electric actuator 1 can be suppressed. As a result, the increase in the manufacturing cost of the electric actuator 1 can be suppressed.

[0074] In addition, in the present embodiment, as described above, since the axial position of the output shaft 46 relative to the housing body 11 can be determined with high accuracy, it is possible to suppress axial positional variation between the sensor magnet 45 fixed to the output shaft 46 and the rotation sensor 81 mounted on the control board 80 fixed to the housing body 11. Thus, the magnetic field of the sensor magnet 45 can be detected with high accuracy by the rotation sensor 81, and the rotation speed of the output shaft 46 can be stabilized.

[0075] According to the present embodiment, the second retaining portion 12 has a mounting portion 12a fixed to the housing body 11, and the elastic deformation portion 12d has a retaining portion 12g that retains the second bearing 52 and a connecting portion 12e that connects the mounting portion 12a and the retaining portion 12g, and the axial dimension of the connecting portion 12e is smaller than the axial dimension of the mounting portion 12a. Therefore, it is easy to reduce the axial rigidity of the elastic deformation portion 12d, and it is easy to elastically deform the elastic deformation portion 12d in the axial direction. Therefore, it is easy to suppress the elastic force Fe applied to the second bearing 52 from becoming too large. Therefore, it is easy to suppress the elastic force Fe applied to the plurality of second rolling elements 258c of the second bearing 52 from becoming too large, so that the output shaft 46 can be stably supported by the second bearing 52. Therefore, since the output shaft 46 can be smoothly rotated, the electric actuator 1 can be stably operated.

[0076] In addition, as described above, since the elastic force Fe applied to the second bearing 52 can be suppressed from becoming too large, when the second retaining portion 12 is fixed to the housing body 11, the force applied to the second retaining portion 12 toward the lower side can be suppressed from increasing. Therefore, the second retaining portion 12 can be easily fixed to the housing body 11, so that the increase in manufacturing man-hours of the electric actuator 1 can be suppressed.

[0077] According to the present embodiment, the housing body 11 has an opening 11m that is open on the upper side, that is, on the other side in the axial direction, and the second retaining portion 12 is fixed to the housing body 11 and blocks the opening 11m. Therefore, in the present embodiment, the output shaft 46 can be pressed downward via the second bearing 52 by the second retaining portion 12, and the opening 11m of the housing body 11 can be blocked. Therefore, for example, compared with a structure having a component for blocking the opening 11m separately from the second retaining portion 12, an increase in the number of components of the electric actuator 1 can be suppressed. Therefore, an increase in the manufacturing cost of the electric actuator 1 can be more appropriately suppressed.

[0078] <Second Embodiment>

[0079] Figure 5 2 is a cross-sectional view showing the electric actuator 201 of the present embodiment. In the electric actuator 201 of the present embodiment, the motor shaft 221 and the output shaft 241 are arranged in parallel in the axial direction. The electric actuator 201 includes a housing 210, a motor 220, a transmission mechanism 230, an output shaft 241, a first bearing 257, a second bearing 258, a third bearing 255, and a control substrate 280. In the present embodiment, the first bearing 257 and the second bearing 258 are ball bearings.

[0080] The housing 210 accommodates the motor 220 and the transmission mechanism 230. The housing 210 has a housing body 211 and a cover member 214 for accommodating the motor 220 and the transmission mechanism 230. In the present embodiment, the housing body 211 is made of metal. The housing body 211 has a motor housing 212 and a transmission mechanism housing 213. The motor housing 212 is open to the lower side on both sides of the axial direction, and the transmission mechanism housing 213 is open to the upper side. The interior of the motor housing 212 and the interior of the transmission mechanism housing 213 are connected to each other. A cover member 214 is fixed to the upper end of the motor housing 212.

[0081] The motor 220, the control substrate 280, the second retaining portion 250 and the second bearing 258 are housed inside the motor housing 212. The motor housing 212 has a housing cylinder 212a and a wall portion 212b. The housing cylinder 212a is cylindrical and extends axially with the motor axis J3 as the center. The housing cylinder 212a is open on both sides of the axial direction. The upper opening of the housing cylinder 212a is blocked by a cover member 214.

[0082] In addition, the direction in which the motor axis J3 extends, that is, the axial direction, as shown appropriately in each figure is parallel to the up-down direction (Z-axis direction). In the following description, the direction parallel to the axial direction of the motor axis J3 is referred to as the "axial direction", the radial direction centered on the motor axis J3 is referred to as the "radial direction", and the circumferential direction centered on the motor axis J3 is referred to as the "circumferential direction".

[0083] The wall portion 212b is an annular plate extending radially inward from the inner circumferential surface of the housing cylindrical portion 212a. The wall portion 212b has a hole portion 212h penetrating the wall portion 212b in the axial direction. In the present embodiment, the hole portion 212h is a circle centered on the motor axis J3.

[0084] The transmission mechanism housing 213 is disposed below the motor housing 212. A portion of the motor shaft 221, the transmission mechanism 230, the output shaft 241, the first bearing 257, and the third bearing 255 are housed inside the transmission mechanism housing 213. The transmission mechanism housing 213 includes a bottom wall portion 213a, a cylinder portion 213b, and a protruding cylinder portion 213c.

[0085] The bottom wall portion 213a is in the shape of an annular plate centered on the motor axis J3. The bottom wall portion 213a is arranged at a position lower than the transmission mechanism 230. The cylinder portion 213b is in the shape of a cylinder protruding upward from the radial outer edge of the bottom wall portion 213a. The cylinder portion 213b is open on the upper side. The cylinder portion 213b is in contact with the housing cylinder portion 212a in the axial direction. The cylinder portion 213b is fixed to the housing cylinder portion 212a. The protruding cylinder portion 213c is in the shape of a cylinder protruding downward from the radial inner edge of the bottom wall portion 213a. The protruding cylinder portion 213c is open on both sides in the axial direction.

[0086] The motor 220 includes a rotor 222 having a motor shaft 221 and a stator 223. The rotor 222 has an annular rotor core 222a fixed to the outer peripheral surface of the motor shaft 221 and a magnet 222b fixed to the rotor core 222a. The motor shaft 221 is housed inside the housing body 211. The motor shaft 221 is rotatable around the motor axis J3. The motor shaft 221 is supported by a first bearing 257 and a second bearing 258 so as to be rotatable around the motor axis J3. That is, the first bearing 257 and the second bearing 258 respectively rotatably support the motor shaft 221 and one of the output shafts 241, namely, the motor shaft 221. In the present embodiment, one of the shafts is the motor shaft 221.

[0087] The motor shaft 221 has an eccentric shaft portion 221a centered on an eccentric axis J4 eccentric to the motor axis J3. The eccentric axis J4 is parallel to the motor axis J3. The eccentric shaft portion 221a is located below the rotor core 222a. The inner ring portion of the third bearing 255 is fitted into the eccentric shaft portion 221a. The motor shaft 221 is connected to the transmission mechanism 230 via the third bearing 255.

[0088] The stator 223 is radially opposed to the rotor 222. The stator 223 is fixed to the inner peripheral surface of the housing tube 212a. Thus, the stator 223 is held on the motor housing 212. The other structures of the stator 223 are the same as those of the stator 22 of the first embodiment.

[0089] The transmission mechanism 230 is arranged on the lower side of the stator 223 and connected to the motor shaft 221 and the output shaft 241. The transmission mechanism 230 includes an external gear 231, an internal gear 233, and a flange portion 242. The external gear 231 is connected to the eccentric shaft portion 221a via the third bearing 255. A plurality of through-hole portions 231a are provided on the external gear 231. The internal gear 233 is fixed to the inner circumferential surface of the cylinder portion 213b. The flange portion 242 is fixed to the output shaft 241. The flange portion 242 is provided with a plurality of protrusions 243. The plurality of protrusions 243 extend upward from the flange portion 242 and are respectively inserted into the plurality of through-hole portions 231a of the external gear 231. The other structures of the external gear 231, the internal gear 233, and the flange portion 242 are the same as the other structures of the external gear 31, the internal gear 32, and the flange portion 42 of the first embodiment.

[0090] The output shaft 241 is arranged on the lower side of the transmission mechanism 230. The output shaft 241 extends in the axial direction. The output shaft 241 is housed inside the housing body 211. The output shaft 241 is arranged on the lower side of the motor shaft 221. That is, the motor shaft 221 is arranged on the upper side of the output shaft 241, that is, on the other axial side. The output shaft 241 decelerates and transmits the rotation of the motor shaft 221 via the transmission mechanism 230. Thus, the output shaft 241 can rotate around the motor axis J3. The output shaft 241 has a first retaining portion 241a and an output shaft portion 241b. That is, the electric actuator 201 has a first retaining portion 241a.

[0091] The first retaining portion 241a retains the first bearing 257. The first retaining portion 241a is connected to the flange portion 242. The first retaining portion 241a is in the shape of a tube extending axially with the motor axis J3 as the center. The first retaining portion 241a extends downward from the radial inner edge of the flange portion 242. The first retaining portion 241a has a bottom and is open on the upper side. The first retaining portion 241a is supported from the lower side by the bottom wall portion 213a via the cylindrical cup member 216 and the cylindrical fourth bearing 256. Thus, the axial position of the output shaft 241 relative to the housing body 211 is determined. In addition, the first retaining portion 241a is supported from the radial outside by the protruding cylinder portion 213c via the cup member 216 and the fourth bearing 256. Thus, the radial position of the output shaft 241 relative to the housing body 211 is determined. The first retaining portion 241a supports the first bearing 257 from the radial outside. As Figure 6 As shown, the first holding portion 241a has a first supporting portion 241d.

[0092] The first support portion 241d protrudes radially inward from a portion of the lower end side of the inner circumferential surface of the first retaining portion 241a. The first support portion 241d is in the shape of an annulus centered on the motor axis J3. The first support portion 241d is located at a position lower than the first bearing 257. The first support portion 241d has a first support surface 241e. The first support surface 241e is a surface facing upward on the outer surface of the first support portion 241d. The first support surface 241e is in contact with the first bearing 257 in the axial direction. Therefore, the first support portion 241d supports the first bearing 257 from the lower side.

[0093] like Figure 5 As shown, the output shaft portion 241b is in the shape of a column extending downward from the first retaining portion 241a. The output shaft portion 241b is in the shape of a cylinder centered on the motor axis J3. The lower portion of the output shaft portion 241b passes through the protruding cylinder portion 213c in the axial direction and is located outside the housing 210. The rotation transmission structure in which the rotation of the motor shaft 221 in this embodiment is reduced in speed and transmitted to the output shaft 241 through the transmission mechanism 230 is the same as the rotation transmission structure of the first embodiment described above.

[0094] The control substrate 280 is in the shape of a plate extending in a direction orthogonal to the motor axis J3. The control substrate 280 is arranged at a position above the motor shaft 221. The control substrate 280 is accommodated inside the motor housing 212. Although not shown in the figure, the control substrate 280 is electrically connected to a plurality of coil portions of the stator 223. Other structures of the control substrate 280 are the same as those of the control substrate 80 of the first embodiment.

[0095] The second holding portion 250 is fixed to the wall portion 212b of the housing body 211. In this embodiment, the second holding portion 250 is made of metal. The second holding portion 250 may be made of resin. Figure 7 As shown, the second holding portion 250 has a mounting portion 250 a and an elastic deformation portion 250 c.

[0096] The mounting portion 250a is a portion of the second retaining portion 250 that is fixed to the housing body 211. The mounting portion 250a is in the shape of an annular plate that surrounds the motor axis J3. The plate surface of the mounting portion 250a faces the axial direction. The mounting portion 250a is arranged at a position higher than the wall portion 212b. The mounting portion 250a is in contact with the wall portion 212b in the axial direction. The mounting portion 250a is fixed to the wall portion 212b by bolts. Thus, the second retaining portion 250 is fixed to the housing body 211.

[0097] The elastic deformation portion 250c is roughly cylindrical with the motor axis J3 as the center. The elastic deformation portion 250c elastically deforms upward, applying an elastic force Fe toward the lower side to the second bearing 258. The elastic deformation portion 250c has a connecting portion 250d and a retaining portion 250e. The connecting portion 250d is in the shape of an annular plate with the motor axis J3 as the center. The plate surface of the connecting portion 250d faces the axial direction. The radial outer edge of the connecting portion 250d is connected to the radial inner edge of the mounting portion 250a. The radial inner edge of the connecting portion 250d is connected to the retaining portion 250e. The connecting portion 250d connects the mounting portion 250a and the retaining portion 250e. The axial dimension of the connecting portion 250d is smaller than the axial dimension of the mounting portion 250a.

[0098] The retaining portion 250e retains the second bearing 258. Therefore, the second retaining portion 250 retains the second bearing 258. The retaining portion 250e is cylindrical and protrudes axially with the motor axis J3 as the center. The retaining portion 250e is open on both sides of the axial direction. The retaining portion 250e passes through the hole portion 212h of the wall portion 212b in the axial direction. The inner peripheral surface of the retaining portion 250e supports the second bearing 258 from the radially outer side. The retaining portion 250e has a second support portion 250f.

[0099] The second support portion 250f protrudes radially inward from the upper end of the inner side surface of the retaining portion 250e. The second support portion 250f is in the shape of an annulus centered on the motor axis J3. The second support portion 250f is located above the second bearing 258. The second support portion 250f has a second support surface 250g. The second support surface 250g is a surface facing downward on the outer side surface of the second support portion 250f. The second support surface 250g is in contact with the second bearing 258 in the axial direction. Therefore, the second support portion 250f supports the second bearing 258 from the upper side.

[0100] As described above, the axial dimension of the connecting portion 250d is smaller than the axial dimension of the mounting portion 250a. Therefore, it is easy to reduce the axial rigidity of the connecting portion 250d. That is, it is easy to reduce the axial rigidity of the elastic deformation portion 250c. In addition, as described above, the radially outer end of the connecting portion 250d is connected to the mounting portion 250a fixed to the shell body 211. Therefore, in this embodiment, similar to the above-mentioned first embodiment, when an axial force is applied to the retaining portion 250e, the connecting portion 250d is elastically deformed in the axial direction with the radial outer edge as the fixed end. Therefore, the retaining portion 250e moves in the axial direction.

[0101] like Figure 5 As shown in FIG. 2 , the first bearing 257 is disposed below the transmission mechanism 230. As described above, the first bearing 257 is a ball bearing. The first bearing 257 rotatably supports the lower side of the motor shaft 221, that is, the portion on one axial side. Figure 6 As shown, the first bearing 257 has a first inner ring portion 257a, a first outer ring portion 257b, a plurality of first rolling elements 257c, and a first retainer 257d. The structures of the plurality of first rolling elements 257c and the first retainer 257d of this embodiment are the same as the structures of the plurality of first rolling elements 51c and the first retainer 51d of the first embodiment.

[0102] The first inner ring portion 257a is in an annular shape with the motor axis J3 as the center. The first inner ring portion 257a surrounds the motor shaft 221. In the present embodiment, the first inner ring portion 257a is fixed to the motor shaft 221.

[0103] The first outer ring portion 257b is in an annular shape with the motor axis J3 as the center. The first outer ring portion 257b surrounds the first inner ring portion 257a from the radially outer side. The first outer ring portion 257b and the first inner ring portion 257a are arranged opposite to each other in the radial direction. In the present embodiment, the first outer ring portion 257b is loosely fitted in the inner peripheral surface of the first retaining portion 241a of the output shaft 241. Therefore, the first outer ring portion 257b is supported by the first retaining portion 241a from the radially outer side. The surface of the first outer ring portion 257b facing the lower side is in contact with the first support surface 241e of the first retaining portion 241a in the axial direction. Therefore, the first outer ring portion 257b is supported by the first retaining portion 241a from the lower side, that is, from one axial side. Therefore, the axial position of the first bearing 257 relative to the output shaft 241 is determined. In addition, as described above, the motor shaft 221 is fixed to the first inner ring portion 257a. Therefore, the axial position of the motor shaft 221 relative to the output shaft 241 is determined via the first bearing 257. As described above, the axial position of the output shaft 241 relative to the housing body 211 is determined by the cup member 216 and the fourth bearing 256. Therefore, the axial position of the motor shaft 221 relative to the housing body 211 is determined by the first bearing 257, the output shaft 241, the cup member 216 and the fourth bearing 256.

[0104] like Figure 5 As shown in FIG. 2 , the second bearing 258 is disposed above the rotor core 222a. As described above, the second bearing 258 is a ball bearing. The second bearing 258 rotatably supports the upper side of the motor shaft 221, that is, the portion on the other axial side. Figure 7 As shown, the second bearing 258 has a second inner ring portion 258a, a second outer ring portion 258b, a plurality of second rolling elements 258c, and a second retainer 258d. The structures of the plurality of second rolling elements 258c and the second retainer 258d of this embodiment are the same as the structures of the plurality of second rolling elements 52c and the second retainer 52d of the first embodiment described above.

[0105] The second inner ring portion 258a is in an annular shape with the motor axis J3 as the center. The second inner ring portion 258a surrounds the motor shaft 221. In the present embodiment, the second inner ring portion 258a is fixed to the motor shaft 221.

[0106] The second outer ring portion 258b is in the shape of an annulus centered on the motor axis J3. The second outer ring portion 258b surrounds the second inner ring portion 258a from the radial outside. The second outer ring portion 258b and the second inner ring portion 258a are arranged opposite to each other in the radial direction. In the present embodiment, the second outer ring portion 258b is gap-fitted into the inner circumferential surface of the retaining portion 250e. Therefore, the second outer ring portion 258b is supported from the radial outside by the second retaining portion 250. The surface of the second outer ring portion 258b facing the upper side is in axial contact with the second support surface 250g of the second retaining portion 250. Therefore, the second outer ring portion 258b is supported by the second retaining portion 250 from the upper side, that is, from the other axial side.

[0107] In this embodiment, similarly to the first embodiment, when the second holding portion 250 is fixed to the housing body 211 to which at least the motor shaft 221, the output shaft 241, the first bearing 257, and the second bearing 258 are mounted, a force is applied to the holding portion 250e from the second bearing 258 toward the upper side. As a result, the connection portion 250d of the elastic deformation portion 250c is elastically deformed toward the upper side, that is, toward the other side of the axial direction, and the holding portion 250e moves toward the upper side. Therefore, similarly to the first embodiment, an elastic force Fe from the elastic deformation portion 250c toward the lower side is applied to the second outer ring portion 258b of the second bearing 258. That is, the elastic deformation portion 250c applies a force toward the lower side, that is, toward one side of the axial direction, to the second outer ring portion 258b. Therefore, the second outer ring portion 258b is stably supported from the upper side by the second holding portion 250. In addition, since the second bearing 258 is fixed to the motor shaft 221, an elastic force Fe is applied to the motor shaft 221 via the second bearing 258. Therefore, the motor shaft 221 can be pressed downward by the elastic force Fe of the elastic deformation portion 250c. In addition, as described above, since the first bearing 257 is fixed to the motor shaft 221, the elastic force Fe is applied to the first bearing 257 via the motor shaft 221. Figure 6 As shown, the first outer ring portion 257b is stably supported by the first retaining portion 241a from the bottom. As a result, the motor shaft 221 can be stably in axial contact with the first retaining portion 241a and the second retaining portion 250 via the first bearing 257 and the second bearing 258. Therefore, the axial position of the motor shaft 221 relative to the housing body 211 can be determined with high precision.

[0108] According to the present embodiment, the motor shaft 221 is arranged on the upper side of the output shaft 241, that is, on the other axial side, the output shaft 241 can rotate around the motor axis J3, one shaft is the motor shaft 221, and the output shaft 241 has a first retaining portion 241a. Therefore, since the motor shaft 221 and the output shaft 241 can be arranged side by side in the axial direction, it is possible to suppress the electric actuator 201 from being enlarged in the radial direction.

[0109] In addition, in this embodiment, since the output shaft 241 has the first holding portion 241a, it is possible to suppress an increase in the number of components of the electric actuator 201 compared to a structure having a component that holds the first bearing 257 separately from the output shaft 241. Therefore, it is possible to more appropriately suppress an increase in the manufacturing cost of the electric actuator 201.

[0110] In addition, in the present embodiment, the first bearing 257 includes a first inner ring portion 257a fixed to the motor shaft 221 and a first outer ring portion 257b supported from the bottom by the first holding portion 241a, and the second bearing 258 includes a second inner ring portion 258a fixed to the motor shaft 221 and a second outer ring portion 258b supported from the top by the second holding portion 250. The second holding portion 250 includes an elastic deformation portion 250c, which elastically deforms upward and applies a downward force to the second outer ring portion 258b. Therefore, as in the first embodiment described above, the elastic force Fe directed downward can be applied to the motor shaft 221 through the second bearing 258 by the elastic deformation portion 250c. As a result, as described above, the axial position of the motor shaft 221 relative to the first holding portion 241a and the second holding portion 250 can be determined with high accuracy, so that the motor shaft 221 can be prevented from shaking in the axial direction. Therefore, in this embodiment, there is no need to separately provide elastic components such as wave washers and spacer rings that apply elastic force to the motor shaft 221 in the axial direction. Therefore, as in the first embodiment described above, it is possible to suppress an increase in the number of components and manufacturing man-hours of the electric actuator 201. As a result, it is possible to suppress an increase in the manufacturing cost of the electric actuator 201.

[0111] The embodiments of the present invention are described above, but the various structures and their combinations in the embodiments are examples, and addition, omission, substitution and other changes of structures can be made without departing from the scope of the purpose of the present invention. In addition, the present invention is not limited to the embodiments.

[0112] The structure of the electric actuator is not limited to the present embodiment. For example, the motor shaft and the output shaft may be arranged side by side in the radial direction. In this case, only one of the motor shaft and the output shaft may be supported by the first bearing held by the first holding portion and the second bearing held by the second holding portion so as to be rotatable, or both shafts may be supported by the first bearing held by the first holding portion and the second bearing held by the second holding portion so as to be rotatable. In addition, shafts other than the motor shaft and the output shaft may be supported by the first bearing held by the first holding portion and the second bearing held by the second holding portion so as to be rotatable.

[0113] The structure of the transmission mechanism is not limited to the present embodiment. For example, a plurality of protrusions may be provided on the external gear and a plurality of through-holes may be provided on the output flange. In this case, each of the plurality of protrusions protrudes from the external gear toward the output flange, that is, toward the lower side, and is inserted into the through-hole portion. In addition, the number of protrusions and the number of through-holes provided in the transmission mechanism may be 7 or less, or 9 or more, respectively.

[0114] The application of the electric actuator of the utility model is not particularly limited. The electric actuator can be mounted on an actuator device of a shift-by-wire system driven based on a shift operation of a driver. In addition, the electric actuator can also be mounted on equipment other than a vehicle. Note that the above structures described in this specification can be appropriately combined within the scope of non-contradiction.

Claims

1. An electric actuator, characterized in that: have: a motor having a motor shaft rotatable about a motor axis; An output shaft to which the rotation of the motor shaft is decelerated and transmitted; a first bearing that rotatably supports a portion of one of the motor shaft and the output shaft on one axial side; a second bearing that rotatably supports a portion of the one shaft on the other axial side; A first holding portion that holds the first bearing; and a second holding portion, which holds the second bearing, The first bearing comprises: a first inner ring portion fixed to the one shaft; a first outer ring portion arranged radially opposite to the first inner ring portion and supported from one axial side by the first retaining portion; and a plurality of first rolling elements located radially between the first inner ring portion and the first outer ring portion. The second bearing comprises: a second inner ring portion fixed to the one shaft; a second outer ring portion arranged radially opposite to the second inner ring portion and supported from the other axial side by the second retaining portion; and a plurality of second rolling elements located radially between the second inner ring portion and the second outer ring portion. The second holding portion includes an elastic deformation portion that elastically deforms toward the other side in the axial direction and applies a force toward one side in the axial direction to the second outer ring portion.

2. The electric actuator according to claim 1, characterized in that: A housing body for accommodating the motor shaft and the output shaft is provided, The second holding portion has a mounting portion mounted on the housing body. The elastic deformation portion includes a holding portion for holding the second bearing and a connecting portion for connecting the mounting portion and the holding portion. An axial dimension of the connection portion is smaller than an axial dimension of the mounting portion.

3. The electric actuator according to claim 2, characterized in that: The motor shaft is a hollow shaft. At least a portion of the output shaft is located inside the motor shaft, The output shaft is rotatable about the motor axis. The one shaft is the output shaft. The housing body includes the first holding portion.

4. The electric actuator according to claim 2 or 3, characterized in that: The housing body has an opening portion that opens toward the other axial side. The second holding portion is fixed to the housing body and closes the opening.

5. The electric actuator according to claim 1 or 2, characterized in that: The motor shaft is arranged on the other axial side of the output shaft. The output shaft is rotatable about the motor axis. The one shaft is the motor shaft. The output shaft includes the first holding portion.

Images