Electric actuator and actuator device

Abstract

The invention provides an electric actuator and an actuator device. The electric actuator includes a motor having a motor shaft, a transmission mechanism, and an output shaft. The motor shaft has an eccentric shaft portion centered on an eccentric axis. The transmission mechanism has: an external gear to which the rotation of the motor shaft is transmitted; an internally toothed gear; and a flange portion that transmits rotation of the external gear to the output shaft. The external gear has a plurality of through-holes. The flange part is provided with a plurality of protruding parts. The plurality of protrusions are inserted into each of the plurality of through-holes. When a first radius of a first pitch circle passing through the centers of the plurality of through-holes is Rch, a second radius of a second pitch circle passing through the centers of the plurality of protruding portions is Rcp, a hole radius of the plurality of through-holes is Rh, a radius of the plurality of protruding portions is Rp, and a maximum tolerance between the eccentric axis and the center of the external gear is D, Rh and D are smaller than Rp. The relationships Rcp > = {Rch * cos (thetah) + D} / cos (thetap), thetah = tan-1 (Rh / Rch), and thetap = tan-1 (Rp / Rcp) are satisfied.

Description

Technical Field

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

[0002] There is known an electric actuator that drives an object such as a parking switch mechanism based on a vehicle operation (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-247798 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the electric actuator as described above, when a rotational torque is applied to an output shaft connected to an object, the output shaft may rotate, thereby causing the position of components constituting the object to change. In order to suppress the positional change of components constituting the object, if components such as a stopper plate and a stopper are provided on the object, the number of parts of the object increases, and the manufacturing cost of the object increases.

[0008] In view of the above circumstances, one object of the present invention is to provide an electric actuator and an actuator device capable of suppressing the output shaft from rotating even when a rotational torque is applied to the output shaft.

[0009] Solutions to Solve Problems

[0010] One embodiment of the electric actuator of the present invention comprises: a motor having a motor shaft rotatable about a motor axis; a transmission mechanism connected to the motor shaft; an output shaft to which the rotation of the motor shaft is transmitted via the transmission mechanism; and a housing that accommodates the motor, the transmission mechanism, and the output shaft. The motor shaft has an eccentric shaft portion centered on an eccentric axis extending in a direction in which the motor axis extends. The transmission mechanism comprises: an annular external gear connected to the outer peripheral surface of the eccentric shaft portion via a bearing and to which the rotation of the motor shaft is transmitted; an annular internal gear disposed radially outward of the external gear and fixed to the housing; and an annular flange portion that transmits the rotation of the external gear to the output shaft. The external gear has a plurality of through-hole portions that penetrate the external gear in the axial direction and are disposed to surround the motor axis. The flange portion is provided with a plurality of protrusions that protrude in the axial direction from the flange portion and are disposed to surround the motor axis. Each of the above-mentioned multiple protrusions is inserted into each of the above-mentioned multiple through-hole portions. A portion of the internal gear portion arranged along the inner circumferential surface of the above-mentioned internal gear meshes with a portion of the external gear portion arranged along the outer circumferential surface of the above-mentioned external gear. The above-mentioned external gear portion and the above-mentioned internal gear portion are respectively involute gears. When the radius of the first pitch circle passing through the center of each of the multiple through-hole portions, that is, the first radius, is set to Rch, the radius of the second pitch circle passing through the center of each of the multiple protrusions, that is, the second radius, is set to Rcp, the radius of each of the multiple through-hole portions, that is, the hole radius, is set to Rh, the radius of each of the multiple protrusions, that is, the protrusion radius, is set to Rp, and the maximum tolerance between the above-mentioned eccentric axis in a direction orthogonal to the axial direction and the center of the above-mentioned external gear is set to D, the following relationship is satisfied: Rcp≥{Rch×cos(θh)+D} / cos(θp), θh=tan -1 (Rh / Rch), θp=tan -1 (Rp / Rcp).

[0011] An actuator device according to an aspect of the present invention includes: the electric actuator described above; and an object coupled to the output shaft. The electric actuator drives the object based on a shift operation of a vehicle.

[0012] Effects of the Invention

[0013] According to one aspect of the present invention, in the electric actuator and the actuator device, even if rotation torque is applied to the output shaft, rotation of the output shaft can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a side view showing a driving device according to one embodiment.

[0015] Figure 2It is a cross-sectional view showing an electric actuator according to an embodiment.

[0016] Figure 3 This is a first diagram showing a transmission mechanism according to an embodiment as viewed from one axial side.

[0017] Figure 4 This is a second diagram showing the transmission mechanism according to one embodiment as viewed from one axial side.

[0018] Figure 5 This is a diagram showing a transmission mechanism of an electric actuator according to a comparative example as viewed from one axial side.

[0019] Figure 6 This is a partially enlarged view of a transmission mechanism of an electric actuator according to a comparative example, viewed from one axial side.

[0020] Figure 7 This is a partially enlarged view of a transmission mechanism according to an embodiment as viewed from one axial side.

[0021] Figure 8 The third diagram is a diagram showing the transmission mechanism according to one embodiment as viewed from one axial side.

[0022] Explanation of symbols

[0023] 9—electric actuator, 10—housing, 20—motor, 23—motor shaft, 23b—eccentric shaft portion, 30—transmission mechanism, 31—external gear, 31b—through hole portion, 31c—external gear portion, 31d—external gear portion, 31e—first external gear portion, 31f—second contact portion, 32—internal gear, 32a—internal gear portion, 32b—internal gear portion, 42—flange portion, 43—protrusion, 43a—first protrusion, 43b—first contact portion, 46—output shaft, 53—third bearing (bearing), 70—parking switching mechanism (object), 100—actuator device, Ch—first pitch circle, Cp—second pitch circle, D—maximum tolerance, J1—motor axis, J2—eccentric axis, L1—first straight line, L2—second straight line, Rch—first radius, Rcp—second radius, Rh—hole radius, Rp—protrusion radius. DETAILED DESCRIPTION

[0024] In the following embodiment, as an example, a case where the object to be displaced and driven by the electric actuator 9 based on the vehicle operation is the parking switch mechanism 70 will be described. As a device equipped with the electric actuator 9 and the parking switch mechanism 70 of the present embodiment, the drive device 1 will be described.

[0025] In the following description, based on Figure 1The positional relationship of the drive device 1 of the present embodiment shown in the figure when it is mounted on a vehicle located on a horizontal road surface is specified in the vertical direction for description. In addition, in the figure, the XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction is a vertical direction with the +Z side as the upper side and the -Z side as the lower side. The X-axis direction is a direction orthogonal to the Z-axis direction, and is the direction in which the motor axis J1 of the electric actuator 9 appropriately shown in each figure extends. The motor axis J1 is an imaginary axis. In the present embodiment, the +X side is one side of the axial direction, and the -X side is the other side of the axial direction. The Y-axis direction is a direction orthogonal to both the X-axis direction and the Z-axis direction, and is the left-right direction of the vehicle. In the present embodiment, the +Y side is one side of the left-right direction of the vehicle, and the -Y side is the other side of the left-right direction of the vehicle.

[0026] In the present embodiment, the direction parallel to the Z-axis direction is referred to as the "vertical direction", the direction parallel to the X-axis direction is referred to as the "axial direction", and the direction parallel to the Y-axis direction is referred to as the "left-right direction". In addition, the positive side (+Z side) of the Z-axis direction is referred to as the "upper side", and the negative side (-Z side) of the Z-axis direction is referred to as the "lower side". The positive side (+X side) of the X-axis direction is referred to as the "one axial side", and the negative side (-X side) of the X-axis direction is referred to as the "other axial side". The positive side (+Y side) of the Y-axis direction is referred to as the "one left-right side", and the negative side (-Y side) of the Y-axis direction is referred to as the "other left-right side". In addition, the upper side and the lower side are merely names used to illustrate the relative positional relationship of each part, and the actual configuration relationship, etc. may also be a configuration relationship, etc. other than the configuration relationship indicated by these names.

[0027] In addition, in the following description, the radial direction centered on the motor axis J1 is simply referred to as "radial direction", and the circumferential direction centered on the motor axis J1 is simply referred to as "circumferential direction". In each figure, the circumferential direction is indicated by the arrow θ1. The side (+θ1 side) to which the arrow θ1 in the circumferential direction points is referred to as "one circumferential side". The opposite side (-θ1 side) to the side to which the arrow θ1 in the circumferential direction points is referred to as "the other circumferential side". One circumferential side is the side that moves counterclockwise around the motor axis J1 when viewed from one axial side. The other circumferential side is the side that moves clockwise around the motor axis J1 when viewed from one axial side.

[0028] The first direction D1 appropriately shown in each drawing is a direction orthogonal to the axial direction. In the following description, the side (+D1 side) to which the arrow of the first direction D1 points is referred to as "one side of the first direction D1", and the opposite side (-D1 side) to which the arrow of the first direction D1 points is referred to as "the other side of the first direction D1".

[0029] The second direction D2 appropriately shown in each drawing is a direction orthogonal to both the axial direction and the first direction D1. In the following description, the side (+D2 side) to which the arrow of the second direction D2 points is referred to as "one side of the second direction D2", and the opposite side (-D2 side) to which the arrow of the second direction D2 points is referred to as "the other side of the second direction D2".

[0030] Figure 1 The drive device 1 of the present embodiment shown is mounted on a vehicle using a motor as a power source, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV). The drive device 1 includes a housing 2, a drive motor 3, a reduction gear 4, a differential device 5, a parking lock gear 6, and an actuator device 100. The actuator device 100 includes a parking switch mechanism 70 and an electric actuator 9.

[0031] The housing 2 accommodates a drive motor 3, a reduction gear 4, a differential device 5, and a parking switch mechanism 70. Although not shown in the figure, oil is accommodated in the housing 2. The reduction gear 4 is connected to the drive motor 3. The differential device 5 is connected to the reduction gear 4 and transmits the torque output from the drive motor 3 to the axle of the vehicle not shown. The parking lock gear 6 is connected to the axle of the vehicle via the reduction gear 4 and the differential device 5. The parking lock gear 6 has a plurality of tooth portions 6a.

[0032] The parking switch mechanism 70 is driven by the electric actuator 9 based on the gear shifting operation of the vehicle. The parking switch mechanism 70 switches the parking lock gear 6 between a locked state and an unlocked state. The parking switch mechanism 70 makes the parking lock gear 6 locked when the gear of the vehicle is in a parking state, and makes the parking lock gear 6 unlocked when the gear of the vehicle is in a state other than parking. The state other than parking includes, for example, the state of the vehicle's gear being in forward, neutral, reverse, and the like. The parking switch mechanism 70 includes a parking shaft 78, a rod 76, an annular member 73, a parking lock arm 77, and a support member 75.

[0033] The parking shaft 78 is connected to the electric actuator 9 and rotates around the motor axis J1 by the electric actuator 9. In the present embodiment, the parking shaft 78 extends in the axial direction along the motor axis J1. Figure 2 As shown, a plurality of axially extending spline grooves are provided along the circumferential direction at one axial end portion of the parking shaft 78 .

[0034] like Figure 1As shown, the rod 76 is connected to the parking shaft 78. When the parking shaft 78 rotates around the motor axis J1, the rod 76 moves in the left-right direction (Y-axis direction). The annular component 73 is connected to the rod 76. The annular component 73 is a roughly conical shape extending in the left-right direction. The annular component 73 can move in the left-right direction. Although the illustration is omitted, the outer peripheral surface of the annular component 73 is a conical surface whose outer diameter increases as it moves toward one side (+Y side) in the left-right direction. When the rod 76 moves in the left-right direction, the annular component 73 moves in the left-right direction together with the rod 76.

[0035] The support member 75 supports the annular member 73 so as to be movable in the left-right direction. In the present embodiment, the support member 75 supports the annular member 73 from the lower side. The support member 75 is fixed to the housing 2.

[0036] The parking lock arm 77 is arranged on the upper side of the annular member 73 and on the lower side of the parking lock gear 6. The parking lock arm 77 is supported rotatably around the rotation axis J3 by a cylindrical support shaft 79 extending in the left-right direction with the rotation axis J3 extending in the left-right direction as the center. The parking lock arm 77 includes an arm body 77a, a meshing portion 77b, and a contact portion 77c.

[0037] The arm body 77a extends from the support shaft 79 to one side in the axial direction. The contact portion 77c protrudes from the end portion of the arm body 77a on one side in the axial direction to one side in the axial direction. The contact portion 77c contacts the outer peripheral surface of the annular member 73 from the upper side. The meshing portion 77b protrudes from the arm body 77a to the upper side. A coil spring (not shown) is mounted on the support shaft 79. The coil spring applies an elastic force to the parking lock arm 77 in the counterclockwise direction when viewed from one side (+Y side) in the left-right direction with the rotation axis J3 as the center.

[0038] As described above, the outer diameter of the outer peripheral surface of the annular member 73 increases from the other side in the left-right direction (-Y side) toward one side in the left-right direction (+Y side). Therefore, when the annular member 73 moves to the other side in the left-right direction with the rotation of the parking shaft 78, the contact portion 77c is lifted upward, and the parking lock arm 77 rotates clockwise around the rotation axis J3 when viewed from one side in the left-right direction (+Y side). As a result, although not shown in the figure, the meshing portion 77b meshes with the teeth 6a of the parking lock gear 6, and the parking lock gear 6 is in a locked state.

[0039] In addition, when the annular member 73 moves to one side (+Y side) in the left-right direction with the rotation of the parking shaft 78, the contact portion 77c lifted by the outer peripheral surface of the annular member 73 moves downward by its own weight and the elastic force of the coil spring (not shown), and the parking lock arm 77 rotates counterclockwise around the rotation axis J3 as viewed from one side (+Y side) in the left-right direction. As a result, the meshing portion 77b is disengaged from the tooth portions 6a, and the parking lock gear 6 is in the unlocked state. As a result, when the electric actuator 9 is driven based on the shift operation of the vehicle, the parking lock arm 77 rotates around the rotation axis J3 via the parking shaft 78, the rod 76 and the annular member 73, and the parking lock gear 6 can be switched between the locked state and the unlocked state.

[0040] In addition, as described later, even if a rotation torque is applied from the parking shaft 78 to the output shaft 46 connected to the parking shaft 78, the electric actuator 9 of the present embodiment can suppress the rotation of the output shaft 46 about the motor axis J1. Therefore, even if a rotation torque is applied from the parking shaft 78 to the output shaft 46, the position change of the parking lock arm 77 can be suppressed. Therefore, in the parking switching mechanism 70 of the present embodiment, components such as a stopper plate and a stopper component that suppress the position change of the parking lock arm 77 are not provided.

[0041] The electric actuator 9 drives the parking switch mechanism 70 based on the vehicle shift operation. In this embodiment, the electric actuator 9 moves the parking lock arm 77 upward or downward via the parking shaft 78 and other components, thereby switching the parking lock gear 6 between the locked state and the unlocked state.

[0042] like Figure 2 As shown, the electric actuator 9 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 board 80, a rotation sensor 81, and a sensor magnet 45. The first bearing 51, the second bearing 52, and the third bearing 53 are, for example, ball bearings.

[0043] The housing 10 accommodates the parts of the electric actuator 9 including the motor 20, the transmission mechanism 30, and the output shaft 46. The housing 10 includes a housing body 11 and a cover member 12. The housing body 11 is substantially cylindrical with the motor axis J1 as the center. The housing body 11 includes an opening 11h opened on one side in the axial direction. The housing body 11 includes a first storage portion 11a and a second storage portion 11b.

[0044] The first housing portion 11a is a portion on the other axial side of the housing body 11. The first housing portion 11a has a bottom portion 11c located on the other axial side and a peripheral wall portion 11d extending from the radial outer edge of the bottom portion 11c to one axial side. The bottom portion 11c is provided with a hole portion 11e that penetrates the bottom portion 11c in the axial direction. The hole portion 11e is a substantially circular hole centered on the motor axis J1. The portion on one axial side of the hole portion 11e constitutes a first bearing retaining portion 11f that retains the first bearing 51.

[0045] The second housing portion 11b is a portion on one axial side 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 a cylindrical shape opened on one axial side. A step having a step surface 11g facing one axial side is provided on the inner circumferential surface of the second housing portion 11b.

[0046] The cover member 12 is fixed to the end of one axial side of the housing body 11. The cover member 12 closes the opening 11h of the housing body 11 from one axial side. The cover member 12 includes a cover body 12a that closes the opening 11h from one axial side and a second bearing retaining portion 12b that protrudes from the cover body 12a to the other axial side. The second bearing retaining portion 12b is cylindrical and is centered on the motor axis J1 and is open on the other axial side. The second bearing 52 is retained on the inner circumferential surface of the second bearing retaining portion 12b.

[0047] The motor 20 has a rotor 21 and a stator 22. The rotor 21 is rotatable about the motor axis J1. The rotor 21 has a motor shaft 23, a rotor core 24a, and a magnet 24b. The motor shaft 23 is rotatable about the motor axis J1. The motor shaft 23 is substantially cylindrical and extends axially about the motor axis J1. The motor shaft 23 is a hollow shaft. The motor shaft 23 is open on both sides in the axial direction. The motor shaft 23 extends across the interior of the first housing portion 11a and the interior of the second housing portion 11b. The motor shaft 23 has a main body portion 23a and an eccentric shaft portion 23b.

[0048] The main body 23a is a portion on one axial side of the motor shaft 23. The rotor core 24a is fixed to the outer peripheral surface of the main body 23a. The end portion on one axial side of the main body 23a is arranged inside the second housing portion 11b. The portion other than the end portion on one axial side of the main body 23a is arranged inside the first housing portion 11a.

[0049] The eccentric shaft portion 23b is the portion on the other axial 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 inside the first storage portion 11a. The eccentric shaft portion 23b is arranged on the other axial side of the rotor core 24a. When viewed from the axial direction, the inner circumference of the eccentric shaft portion 23b is a circular shape centered on the motor axis J1. When viewed from the axial direction, the outer circumference of the eccentric shaft portion 23b is a circular shape centered on an eccentric axis J2 that is eccentric relative to the motor axis J1. The eccentric axis J2 is an imaginary axis extending in the direction in which the motor axis J1 extends. As Figure 3 As shown, in the following description, the distance between the motor axis J1 and the eccentric axis J2 is referred to as the eccentricity A. Figure 3 In the embodiment, the eccentric axis J2 is located on one side (+D1 side) of the motor axis J1 in the first direction D1. When the motor shaft 23 rotates, the eccentric axis J2 revolves around the motor axis J1. Figure 3 In the transmission mechanism 30, the tolerance between the motor axis J1 and the eccentric axis J2 in the direction orthogonal to the axial direction is zero. Figure 2 As shown in FIG. 2 , the inner ring of the third bearing 53 is fitted and fixed to the outer peripheral surface of the eccentric shaft portion 23 b. Thus, the third bearing 53 is fixed to the motor shaft 23 .

[0050] The rotor core 24a is annular with the motor axis J1 as the center. The rotor core 24a is arranged inside the first storage portion 11a. The rotor core 24a is fixed to the outer peripheral surface of the main body 23a. The magnet 24b is fixed to the outer peripheral surface of the rotor core 24a. In this embodiment, a plurality of magnets 24b are arranged at intervals in the circumferential direction.

[0051] 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. Thus, the stator 22 is fixed to the housing 10.

[0052] The transmission mechanism 30 is arranged inside the first storage portion 11a. The transmission mechanism 30 is arranged on the other axial 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. The transmission mechanism 30 transmits the rotation of the motor shaft 23 around the motor axis J1 to the output shaft 46. That is, the rotation of the motor shaft 23 is transmitted to the output shaft 46 via the transmission mechanism 30. In the present embodiment, the transmission mechanism 30 is a speed reduction mechanism that reduces the rotation of the motor shaft 23 and transmits it to the output shaft 46. The transmission mechanism 30 may also be a speed increase mechanism that increases the rotation of the motor shaft 23 and transmits it to the output shaft 46, or may be a transmission mechanism that transmits the rotation of the same speed as the rotation of the motor shaft 23 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.

[0053] The external gear 31 is annular with the eccentric axis J2 as the center. The external gear 31 is fitted into the outer ring 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 3 As shown, the external gear 31 has a plurality of through-hole portions 31 b and an external gear portion 31 c.

[0054] 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 in shape. The plurality of through-hole portions 31b are arranged to surround the motor axis J1. The radius of each through-hole portion 31b is the hole radius Rh. In the present embodiment, eight through-hole portions 31b are provided.

[0055] Figure 3 The first pitch circle Ch shown is a circle passing through the center of each through hole portion 31b when viewed from the axial direction. When viewed from the axial direction, the center of the first pitch circle Ch, that is, the first center Cch, overlaps with the eccentric axis J2. The first center Cch is the center of the external gear 31. The radius of the first pitch circle Ch is the first radius Rch.

[0056] 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. In the present embodiment, the external gear portion 31c is composed of 79 external tooth portions 31d. That is, the number of teeth N1 of the external gear portion 31c is 79. The number of teeth N1 of the external gear portion 31c may be 78 or less, or may be 80 or more. In the present embodiment, the external gear portion 31c is an involute gear. Figure 3The first imaginary line La shown is an imaginary line connecting the eccentric axis J2 and the node of the external tooth portion 31d when viewed from the axial direction. The node of the external tooth portion 31d is a portion of the tooth surface of the external tooth portion 31d that contacts the internal tooth portion 32b described later of the internal gear 32. The first tangent line Ld is a tangent line that is tangent to the node of the external tooth portion 31d among the tangent lines tangent to the tooth surface of the external tooth portion 31d. The angle formed by the first imaginary line La and the first tangent line Ld is the pressure angle α1 of the external tooth portion 31d. In the present embodiment, the pressure angle α1 of each of the plurality of external tooth portions 31d is greater than 22° and less than 25.5°.

[0057] 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 2 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. That is, the internal gear 32 is fixed to the housing 10. Figure 3 As shown, the internal gear 32 has an internal gear portion 32 a.

[0058] The internal gear portion 32a is arranged along the inner circumferential 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 circumferential surface of the internal gear 32. In the present embodiment, the internal gear portion 32a is composed of 80 internal gear portions 32b. That is, the number of teeth N2 of the internal gear portion 32a is 80. The number of teeth N2 of the internal gear portion 32a may be 79 or less, or may be 81 or more. A portion of the internal gear portion 32a meshes with a portion of the external gear portion 31c. In the present embodiment, the internal gear portion 32a is an involute gear. Figure 3 The second imaginary line Lb shown is an imaginary line connecting the motor axis J1 and the node of the internal tooth portion 32b when viewed in the axial direction. The node of the internal tooth portion 32b is the portion of the tooth surface of the internal tooth portion 32b that contacts the node of the external tooth portion 31d. The second tangent Le is a tangent that is tangent to the tooth surface of the internal tooth portion 32b and is tangent to the node of the internal tooth portion 32b. The angle formed by the second imaginary line Lb and the second tangent Le is the pressure angle α2 of the internal tooth portion 32b. In the present embodiment, the pressure angle α2 of each of the multiple internal tooth portions 32b is greater than 22° and less than 25.5°. The pressure angle α1 and the pressure angle α2 can be the same angle as each other, or different angles from each other.

[0059] like Figure 2As shown, the flange portion 42 is arranged on the other axial side of the external gear 31. The flange portion 42 is arranged at a distance from the external gear 31 in the axial direction. The flange portion 42 is annular with the motor axis J1 as the center. The flange portion 42 is fixed to a portion of the output shaft 46 that is closer to the other axial side than the motor shaft 23. A plurality of protrusions 43 are provided on the flange portion 42.

[0060] In the present embodiment, the plurality of protrusions 43 are cylindrical and protrude from the flange 42 in one direction in the axial direction. In the present embodiment, the plurality of protrusions 43 and the flange 42 are part of the same single component. Figure 3 As shown, the outer diameter of each of the plurality of protrusions 43 is smaller than the inner diameter of each of the plurality of through-hole portions 31b. The radius of each protrusion 43 is the protrusion radius Rp. The protrusion radius Rp is smaller than the hole radius Rh. The plurality of protrusions 43 are arranged to surround the motor axis J1. In this embodiment, eight protrusions 43 are provided. Figure 2 As shown, each of the plurality of protrusions 43 is inserted into each of the plurality of through-holes 31b from the other axial side. Figure 3 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 .

[0061] Figure 3 The second pitch circle Cp shown is a circle passing through the center of each protrusion 43 when viewed from the axial direction. When viewed from the axial direction, the center of the second pitch circle Cp, i.e., the second center Ccp, overlaps with the motor axis J1. The radius of the second pitch circle Cp is the second radius Rcp. The size of the second radius Rcp is larger than the size of the first radius Rch. In the present embodiment, when the tolerance between the eccentric axis J2 in a direction orthogonal to the axial direction and the center of the first pitch circle Ch, i.e., the first center Cch, is zero, that is, when the eccentric axis J2 and the first center Cch overlap when viewed from the axial direction, the second pitch circle Cp surrounds the first pitch circle Ch from the radial outside. The second pitch circle Cp may not surround the first pitch circle Ch from the radial outside. Figure 4 The maximum tolerance D shown is the maximum deviation between the eccentric axis J2 and the first center Cch. The maximum tolerance D is a tolerance obtained by adding together multiple tolerances such as the concentricity of the outer peripheral surface of the eccentric shaft portion 23b and the third bearing 53, the tolerance of the outer diameter of the eccentric shaft portion 23b and the inner diameter of the third bearing 53, the concentricity of the third bearing 53 and the external gear 31, and the tolerance of the outer diameter of the third bearing 53 and the inner diameter of the external gear 31.

[0062] The output shaft 46 outputs the driving force of the electric actuator 9 to the parking switch mechanism 70. Figure 2As shown, the output shaft 46 extends in the axial direction. The output shaft 46 is rotatable around the motor axis J1. The rotation of the motor shaft 23 is transmitted to the output shaft 46 via the transmission mechanism 30. The output shaft 46 passes through the interior of the motor shaft 23 in the axial direction. The output shaft 46 protrudes from the motor shaft 23 to both axial sides. That is, at least a portion of the output shaft 46 is located inside the motor shaft 23. In addition, the output shaft 46 and the flange portion 42 can also be part of the same single component. The output shaft 46 has an output shaft body 41 and a mounting component 44 fixed to the outer peripheral surface of the output shaft body 41.

[0063] 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 around the motor axis J1. The output shaft body 41 has a connecting portion 41a and an extending portion 41b.

[0064] The connecting portion 41a is a portion on the other axial 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 to the other axial side. The end of the connecting portion 41a on the other axial side is inserted into the inside of the hole portion 11e. The end of the connecting portion 41a on one axial side is inserted into the inside 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.

[0065] The portion of the parking shaft 78 on one axial side can be inserted into the interior of the connecting portion 41a from the other axial side. When the plurality of spline grooves provided on the outer circumferential surface of the parking shaft 78 are engaged with the plurality of spline grooves provided on the inner circumferential surface of the connecting portion 41a, the connecting portion 41a and the parking shaft 78 are connected to each other. Thus, the parking switching mechanism 70, i.e., the object, is connected to the output shaft 46. The rotation of the motor shaft 23 is transmitted to the parking shaft 78 via the output shaft 46. Thus, the electric actuator 9 drives the parking switching mechanism 70.

[0066] The extension portion 41b is a portion on one axial 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 inside of the motor shaft 23 in the axial direction. The portion on one axial side of the extension portion 41b protrudes to one axial side than the motor shaft 23. The end portion on one axial side of the extension portion 41b is supported by the second bearing 52 so as to be rotatable around the motor axis J1.

[0067] In this embodiment, the outer diameter of the extension portion 41b is slightly smaller than the inner diameter of the main body portion 23a of the motor shaft 23. The extension portion 41b is loosely fitted inside the main body portion 23a. For example, lubricating oil may be placed in the gap between the extension portion 41b and the main body portion 23a.

[0068] The mounting member 44 is fixed to a portion of the outer peripheral surface of the extension portion 41b that is closer to one side of the motor shaft 23 in the axial direction. The mounting member 44 includes a fixed cylinder portion 44a and an annular portion 44b. The fixed cylinder portion 44a is a cylindrical shape that is centered on the motor axis J1 and is 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 a generally annular plate shape that expands radially outward from the end portion of the fixed cylinder portion 44a on the other side in the axial direction.

[0069] 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 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.

[0070] In the axial direction, a washer 61 is arranged between the main body 23a of the motor shaft 23 and the connecting portion 41a of the output shaft 46. In the axial direction, a washer 62 is arranged between the main body 23a and the annular portion 44b. The washers 61 and 62 are annular plates with the plate surface facing the axial direction. The washers 61 and 62 are, for example, sliding washers. The washers 61 and 62 respectively reduce the friction between the motor shaft 23 and the output shaft 46. Therefore, the output efficiency of the electric actuator 9 can be improved.

[0071] The control substrate 80 is arranged on one axial side of the stator 22. The control substrate 80 is fixed to the stepped surface 11g of the housing 10. The control substrate 80 is in the shape of a plate extending in the radial direction. Although not shown in the figure, the control substrate 80 is electrically connected to the multiple coil portions 22c of the stator 22, respectively. The control substrate 80 controls the power supplied to the multiple coil portions 22c, respectively. 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.

[0072] The rotation sensor 81 is fixed to the surface of the control substrate 80 facing one axial side. The rotation sensor 81 is axially opposed to 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 sensor magnet 45 by detecting the magnetic field of the sensor magnet 45. Thus, the rotation sensor 81 detects the rotation of the output shaft 46.

[0073] When power is supplied from the control board 80 to the motor 20 to rotate the motor shaft 23 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. Thus, the driving force of the motor shaft 23 is transmitted to the internal gear 32 via the external gear 31.

[0074] As described above, the internal gear 32 is fixed to the housing 10. Therefore, the external gear 31 rotates about the eccentric axis J2 by ​​the reaction force of the driving force transmitted to the internal gear 32. In this embodiment, the rotation of the external gear 31 is reduced relative to the rotation of the motor shaft 23.

[0075] The rotation of the external gear 31 about the eccentric axis J2 is transmitted to the flange portion 42 via the inner side surface of the through hole portion 31b and the protrusion 43, causing the flange portion 42 to rotate about the motor axis J1. As described above, the output shaft 46 is fixed to the flange portion 42, so the output shaft 46 rotates about the motor axis J1 together with the flange portion 42. That is, the rotation of the external gear 31 is transmitted to the output shaft 46 via 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.

[0076] Figure 5 A transmission mechanism 130 of an electric actuator 109 of a comparative example is shown. In the following description, components having the same form as those of the present embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

[0077] In the electric actuator 109, the plurality of protrusions 143 are cylindrical and protrude from the flange portion 42 to one side in the axial direction. The outer diameter of each protrusion 143 is smaller than the inner diameter of each through hole portion 31b. The radius of each protrusion 143 is the protrusion radius Rp. The protrusion radius Rp is smaller than the hole radius Rh. The plurality of protrusions 143 are arranged to surround the motor axis J1. In the present embodiment, eight protrusions 143 are provided.

[0078] The second pitch circle Cp2 of the comparative example is a circle passing through the center of each protrusion 143 when viewed from the axial direction. When viewed from the axial direction, the center Ccp2 of the second pitch circle Cp2 overlaps with the motor axis J1. The radius of the second pitch circle Cp2 is the second radius Rcp2. The size of the second radius Rcp2 is the same as the size of the first radius Rch. Figure 5In the embodiment, the eccentric axis J2 is located on one side (+D1 side) in the first direction D1 relative to the motor axis J1 when viewed in the axial direction. In addition, the maximum tolerance D between the eccentric axis J2 and the first center Cch is zero.

[0079] like Figure 6 As shown, the plurality of protrusions 143 include a first protrusion 143a. When the eccentric axis J2 is located on one side (+D1 side) of the motor axis J1 in the first direction D1 and the first center Cch is located on one side (+D2 side) of the second direction D2 than the eccentric axis J2 when viewed from the axial direction, the first protrusion 143a is arranged on one side of the motor axis J1 in the second direction D2. In this case, the first center Cch is located on one side of the motor axis J1 in the first direction D1 and on one side of the second direction D2. The portion of the first protrusion 143a on the other side (-D1 side) of the first direction D1 and on one side (+θ1 side) of the circumferential direction contacts the inner side surface of the through hole portion 31b. Figure 6 The first contact portion 143b shown is a portion of the outer circumference of the first protrusion 143a that contacts the inner circumference of the first through hole portion 31h inserted into the first protrusion 143a. When the angle formed by the third straight line L32 passing through the center of the first protrusion 143a and the motor axis J1 and the first straight line L12 passing through the first contact portion 143b and the motor axis J1 is set to θp2, the distance Lt2 between the motor axis J1 and the first contact portion 143b in the second direction D2 is Lt2 = RCp2 × cos (θp2). In addition, θp2 = tan -1 (Rp / Rcp2).

[0080] Figure 6 The passage portion Pc shown is a portion of the inner side surface of the first through hole portion 31h located on one side (+θ1 side) in the circumferential direction, and is a portion through which the first pitch circle Ch passes. When the angle formed by the fourth straight line L4 passing through the center of the first through hole 31h and the first center Cch and the fifth straight line L5 passing through the passage portion Pc and the first center Cch is set to θh, the distance Lc between the first center Cch and the passage portion Pc in the second direction D2 is Lc=RCh×cos(θh). In addition, θh=tan -1 (Rh / Rch).

[0081] In the electric actuator 109 of the comparative example, in the second direction D2, Lt2 < LC + D. Therefore, in the electric actuator 109 of the comparative example, the second radius Rcp2 satisfies the relationship Rcp2 < {Rch×cos(θh) + D} / cos(θp2). In other words, when the second radius Rcp2, the protrusion radius Rp, the first radius Rch, the hole radius Rh, and the maximum tolerance D satisfy the relationship Rcp2 < {Rch×cos(θh) + D} / cos(θp2), the relationship Lt < LC + D is satisfied in the second direction D2. In this case, the first contact portion 143b is located radially inward of the passing portion Pc. That is, the first contact portion 143b, which is the contact position of the first protrusion 143a and the first through hole portion 31h, is located radially inward of the portion of the inner peripheral surface of the first through hole portion 31h through which the first pitch circle Ch passes.

[0082] Next, the first pressing force F12 applied by the first protrusion 143a to the external gear 31 when the electric actuator 109 of the reverse drive comparative example is driven will be described. In reverse drive, a rotational torque is applied to the output shaft 46 to rotate the output shaft 46 about the motor axis J1, and the rotation of the output shaft 46 is transmitted to the motor shaft 23 via the transmission mechanism 30, and the motor shaft 23 is driven about the motor axis J1. In the electric actuator 109 of the comparative example, when a rotational torque that causes the output shaft 46 to rotate about the motor axis J1 in, for example, one circumferential direction (+θ1 side) is applied to the output shaft 46, each protrusion 143 tends to rotate in the one circumferential direction. As a result, while the position of the contact between the inner peripheral surface of the through hole portion 31b and the outer peripheral surface of the protrusion 143 changes, the external gear 31 tends to revolve about the motor axis J1. More specifically, the first center Cch, which is the center of the external gear 31, tends to revolve about the motor axis J1 toward the other circumferential direction (-θ1 side). As described above, in the electric actuator 109 of the comparative example, the first contact portion 143b is located radially inward of the first pitch circle Ch. Therefore, in reverse drive, the direction of the first pressing force F12, which is the force applied by the first protrusion 143a to the inner peripheral surface of the first through hole portion 31h, is inclined from the other circumferential direction toward the radial inside. Therefore, the component of the first pressing force F12 in the second direction D2 is directed toward the other side (-D2 side) of the second direction D2.

[0083] In addition, as described above, when a rotational torque toward one side (+θ1 side) in the circumferential direction is applied to the output shaft 46, the center of the external gear 31, that is, the first center Cch, intends to revolve around the motor axis J1 toward the other side (-θ1 side) in the circumferential direction. In addition, as described above, the first center Cch is located on one side (+D1 side) of the first direction D1 and on one side (+D2 side) of the second direction D2 than the motor axis J1. Therefore, when a rotational torque toward one side in the circumferential direction is applied to the output shaft 46, the component of the second direction D2 in the direction in which the first center Cch intends to move is toward the other side (-D2 side) of the second direction D2. Therefore, in the second direction D2, the direction in which the first pressing force F12 is directed and the direction in which the first center Cch intends to move are the same direction, so the external gear 31 can revolve around the motor axis J1 toward the other side in the circumferential direction. Therefore, in the electric actuator 109 of the comparative example, when a rotational torque is applied to the output shaft 46, the output shaft 46 and the motor shaft 23 are driven in reverse.

[0084] like Figure 7 As shown, the plurality of protrusions 43 include a first protrusion 43a. When the eccentric axis J2 is located on one side (+D1 side) of the motor axis J1 in the first direction D1 and the first center Cch is located on one side (+D2 side) of the eccentric axis J2 in the second direction D2, the first protrusion 43a is arranged on one side of the motor axis J1 in the second direction D2. In this case, the first center Cch is located on one side of the motor axis J1 in the first direction D1 and on one side of the second direction D2. The first contact portion 43b is a portion of the outer peripheral surface of the first protrusion 43a that contacts the inner peripheral surface of the first through hole portion 31h into which the first protrusion 43a is inserted. When the angle formed by the third straight line L3 passing through the center of the first protrusion 43a and the motor axis J1 and the first straight line L1 passing through the first contact portion 43b and the motor axis J1 is θp, the distance Lt between the motor axis J1 and the first contact portion 43b in the second direction D2 is Lt=RCp×cos(θp). In addition, θp = tan -1 (Rp / Rcp).

[0085] in addition, Figure 7 The passage portion Pc shown is a portion of the inner side surface of the first through hole portion 31h located on one side (+θ1 side) in the circumferential direction and is a portion through which the first pitch circle Ch passes. As described above, the distance Lc between the first center Cch in the second direction D2 and the passage portion Pc is Lc=RCh×cos(θh). In addition, θh=tan -1 (Rh / Rch).

[0086] In the electric actuator 9 of the present embodiment, Lt≥LC+D in the second direction D2. Therefore, in the electric actuator 9 of the present embodiment, the second radius Rcp satisfies the relationship of Rcp≥{Rch×cos(θh)+D} / cos(θp). In other words, when the second radius Rcp, the protrusion radius Rp, the first radius Rch, and the hole radius Rh satisfy the relationship of Rcp≥{Rch×cos(θh)+D} / cos(θp), in the second direction D2, the relationship of Lt≥LC+D is satisfied. In this case, the first contact portion 43b is located radially outside the passing portion Pc. That is, the first contact portion 43b, which is the contact position of the first protrusion 43a and the first through hole portion 31h, is located radially outside the portion of the inner circumferential surface of the first through hole portion 31h through which the first pitch circle Ch passes.

[0087] Next, the force applied by the first protrusion 43a to the external gear 31 when the electric actuator 9 of the present embodiment is driven in reverse, that is, the first pressing force F1 is described. When a rotational torque is applied to the output shaft 46 so that it rotates around the motor axis J1, for example, to one side of the circumference (+θ1 side), each protrusion 143 intends to rotate toward one side of the circumference. As described above, the first contact portion 43b is located radially outward of the portion of the inner circumferential surface of the first through hole portion 31h through which the first pitch circle Ch passes. Therefore, in reverse driving, the direction of the force applied by the first protrusion 43a to the inner circumferential surface of the first through hole portion 31h, that is, the first pressing force F1, is oriented in a direction inclined from the other side of the circumference to the radial outward. Therefore, the component of the second direction D2 of the first pressing force F1 is oriented toward one side of the second direction D2 (+D2 side).

[0088] In addition, as described above, when a rotational torque is applied to the output shaft 46 to rotate it toward one side (+θ1 side) in the circumferential direction, the component of the second direction D2 in the direction in which the first center Cch is to move is directed toward the other side (-D2 side) of the second direction D2. Therefore, in the second direction D2, the direction in which the first pressing force F1 is directed is opposite to the direction in which the first center Cch is to move. As a result, it is difficult for the external gear 31 to move in the second direction D2, so that the external gear 31 can be suppressed from revolving around the motor axis J1 toward the other side in the circumferential direction. Therefore, in the electric actuator 9 of the present embodiment, even if a rotational torque is applied to the output shaft 46, it is possible to suppress the output shaft 46 and the motor shaft 23 from being driven in the reverse direction.

[0089] According to the present embodiment, when the radius of the first pitch circle Ch passing through the center of each of the plurality of through-hole portions 31b, i.e., the first radius, is set to Rch, the radius of the second pitch circle Cp passing through the center of each of the plurality of protrusions 43, i.e., the second radius, is set to Rcp, the radius of each of the plurality of through-hole portions 31b, i.e., the hole radius, is set to Rh, the radius of each of the plurality of protrusions 43, i.e., the protrusion radius, is set to Rp, and the maximum tolerance between the eccentric axis J2 in the direction orthogonal to the axial direction and the center of the external gear 31 is set to D, the electric actuator 9 satisfies Rcp≥{Rch×cos(θh)+D} / cos(θp), θh=tan -1 (Rh / Rch),θp=tan -1 (Rp / Rcp) relationship. Therefore, as described above, the first contact portion 43b can be arranged radially outward of the portion of the inner circumferential surface of the first through hole portion 31h through which the first pitch circle Ch passes, so that even if a rotational torque is applied to the output shaft 46, the direction in which the first pressing force F1 is directed and the direction in which the first center Cch is intended to move can be opposite in the second direction D2. As a result, as described above, the external gear 31 can be suppressed from revolving around the motor axis J1. Therefore, even if a rotational torque is applied to the output shaft 46, the output shaft 46 and the motor shaft 23 can be suppressed from driving in reverse.

[0090] like Figure 8 As shown, the external gear portion 31c has a first external gear portion 31e. The plurality of external gear portions 31d include the first external gear portion 31e. The tooth surface of the first external gear portion 31e facing one side in the circumferential direction (+θ1 side) contacts a portion of the internal gear portion 32a. More specifically, the tooth surface of the first external gear portion 31e facing one side in the circumferential direction contacts the surface of the internal gear portion 32b facing the other side in the circumferential direction (-θ1 side). The portion of the first external gear portion 31e that contacts the internal gear portion 32a is the second contact portion 31f. Figure 8 The second straight line L2 shown is a straight line passing through both the second contact portion 31f and the eccentric axis J2. In the present embodiment, the first angle θa formed by the first straight line L1 and the second straight line L2 is 148° or more. Figure 8 The second pressing force F2 shown is a reaction force applied from the internal tooth portion 32b to the second contact portion 31f when the external gear 31 rotates to one side (+θ1 side) in the circumferential direction. The second pressing force F2 is a force in the normal direction of the tooth surface of the internal tooth portion 32b in contact with the first external tooth portion 31e. In the present embodiment, the second pressing force F2 is in a direction inclined from the other side (-D1 side) of the first direction D1 to the other side (-D2 side) of the second direction D2. The component of the second pressing force F2 in the second direction D2 is in the direction of the other side of the second direction D2.

[0091] According to the present embodiment, the external gear portion 31c has a first external gear portion 31e whose tooth surface facing one side (+θ1 side) in the circumferential direction contacts a part of the internal gear portion 32a, and a straight line passing through the first contact portion 43b, which is a portion of the outer circumferential surface of the first protrusion 43a in contact with the through hole portion 31b, and the motor axis J1 is set as the first straight line L1, and a straight line passing through the second contact portion 31f, which is a portion of the first external gear portion 31e in contact with the internal gear portion 32a, and the eccentric axis J2 is set as the second straight line L2, and the first angle θa, that is, the angle formed by the first straight line L1 and the second straight line L2 is 148° or more. As described above, the component of the second direction D2 of the first pressing force F1 is directed to one side (+D2 side) of the second direction D2. In the present embodiment, the first angle θa is 148° or more, so the component of the second direction D2 of the second pressing force F2 is easily directed to the other side (-D2 side) of the second direction D2 which is the opposite direction to the direction in which the component of the second direction D2 of the first pressing force F1 is directed. That is, in the second direction D2, it is easy to make the direction in which the first pressing force F1 is directed and the direction in which the second pressing force F2 is directed opposite to each other. As a result, it is more difficult for the external gear 31 to move in the second direction D2, so that the external gear 31 can be more appropriately suppressed from revolving around the motor axis J1. Therefore, even if a rotational torque is applied to the output shaft 46, the output shaft 46 and the motor shaft 23 can be more appropriately suppressed from being driven in the reverse direction.

[0092] According to the present embodiment, the pressure angles of the plurality of external tooth portions 31d constituting the external gear portion 31c and the pressure angles of the plurality of internal tooth portions 32b constituting the internal gear portion 32a are respectively 22° or more and 25.5° or less. When the pressure angles of the external tooth portion 31d and the pressure angles of the internal tooth portion 32b are less than 22°, the sizes of the tooth roots of the external tooth portion 31d and the tooth roots of the internal tooth portion 32b are too small, and thus, when the electric actuator 9 is operated, the external tooth portion 31d and the internal tooth portion 32b may be damaged. In addition, when the pressure angles of the external tooth portion 31d and the pressure angles of the internal tooth portion 32b are greater than 25.5°, when the electric actuator 9 is operated, the circumferential component of the force applied from the external tooth portion 31d to the internal tooth portion 32b becomes too small, and thus, the circumferential component of the reaction force applied from the internal tooth portion 32b to the external tooth portion 31d is reduced. As a result, the rotation torque of the external gear 31 rotating around the eccentric axis J2 is reduced, so the driving efficiency of the electric actuator 9 is easily reduced. In contrast, in the present embodiment, as described above, the pressure angles of the plurality of external tooth portions 31d and the pressure angles of the plurality of internal tooth portions 32b are respectively 22° or more and 25.5° or less, so that the external tooth portions 31d and the internal tooth portions 32b can be prevented from being damaged, and the driving efficiency of the electric actuator 9 can be prevented from being reduced.

[0093] 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, and the output shaft 46 can rotate around the motor axis J1. Therefore, compared with the case where the output shaft 46 is arranged radially outside the motor shaft 23, the electric actuator 9 can be prevented from being enlarged in the radial direction.

[0094] According to the present embodiment, the actuator device 100 includes an electric actuator 9 and an object connected to an output shaft 46, and the electric actuator 9 drives the object based on the gear shifting operation of the vehicle. Therefore, when the electric actuator 9 and the object are stopped, even if a rotational torque is applied from the object to the output shaft 46, the electric actuator 9 can be suppressed from being driven in reverse, so that the output shaft 46 can be suppressed from rotating. Thus, when the electric actuator 9 and the object are stopped, the position change of each component constituting the object can be suppressed. Therefore, it is not necessary to provide a stopper plate and a stopper component and other components for suppressing the position change of each component constituting the object in the actuator device 100. Therefore, it is possible to suppress an increase in the number of parts of the actuator device 100 and an increase in the manufacturing cost of the actuator device 100.

[0095] According to the present embodiment, the object is the parking switch mechanism 70 driven based on the shift operation of the vehicle. Therefore, when the electric actuator 9 is mounted on the actuator device 100 of the parking-by-wire method, even if the rotation torque is applied from the parking switch mechanism 70 to the output shaft 46, the electric actuator 9 can be suppressed from being driven in reverse, so that the output shaft 46 can be suppressed from rotating. Therefore, it is not necessary to provide components such as a stopper plate and a stopper member in the actuator device 100, so the number of parts of the actuator device 100 and the manufacturing cost of the actuator device 100 can be suppressed.

[0096] 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 spirit of the present invention. In addition, the present invention is not limited to the embodiments.

[0097] The structure of the transmission mechanism is not limited to the present embodiment. For example, the pressure angle of the external gear portion and the pressure angle of the internal gear portion may be less than 22° or greater than 25.5°. In addition, the number of teeth of the external gear portion and the number of teeth of the internal gear portion are not particularly limited. In addition, the transmission mechanism may increase the speed of the rotation of the motor shaft and transmit it to the output shaft, or may transmit the rotation at the same speed as the rotation of the motor shaft to the output shaft.

[0098] Alternatively, 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, the plurality of protrusions protrude from the external gear toward the output flange, that is, toward the other axial side, and are inserted into the through-holes. In addition, the number of protrusions and the number of through-holes provided on the transmission mechanism may be seven or less, or nine or more, respectively.

[0099] In addition, the plurality of protrusions and the flange portion may be separate bodies. In this case, each of the plurality of protrusions is fixed to each of the plurality of holes penetrating the flange portion by press fitting or the like.

[0100] The application of the electric actuator of the present invention is not particularly limited. The electric actuator may also be mounted on an actuator device of a shift-by-wire type that is driven based on a shift operation by a driver. In addition, the electric actuator may also be mounted on a machine other than a vehicle. In addition, the various structures described above in this specification can be appropriately combined within a range that does not contradict each other.

[0101] Furthermore, the present technology can take the following structures.

[0102] (1) An electric actuator comprising: a motor having a motor shaft rotatable about a motor axis; a transmission mechanism connected to the motor shaft; an output shaft to which the rotation of the motor shaft is transmitted via the transmission mechanism; and a housing that accommodates the motor, the transmission mechanism, and the output shaft, the motor shaft having an eccentric shaft portion centered about an eccentric axis extending in a direction in which the motor axis extends, the transmission mechanism having: an annular external gear connected to an outer peripheral surface of the eccentric shaft portion via a bearing and to which the rotation of the motor shaft is transmitted; an annular internal gear arranged on a radially outer side of the external gear and fixed to the housing; and an annular flange portion that transmits the rotation of the external gear to the output shaft, the external gear having a plurality of through-hole portions axially penetrating the external gear and arranged to surround the motor axis, the flange portion being provided with a flange portion protruding axially from the flange portion and arranged to surround A plurality of protrusions are arranged on the motor axis, each of the plurality of protrusions is inserted into each of the plurality of through-holes, a portion of the internal gear portion arranged along the inner circumferential surface of the internal gear meshes with a portion of the external gear portion arranged along the outer circumferential surface of the external gear, the external gear portion and the internal gear portion are respectively involute gears, when the radius of the first pitch circle passing through the center of each of the plurality of through-holes, i.e., the first radius, is set to Rch, the radius of the second pitch circle passing through the center of each of the plurality of protrusions, i.e., the second radius, is set to Rcp, the radius of each of the plurality of through-holes, i.e., the hole radius, is set to Rh, the radius of each of the plurality of protrusions, i.e., the protrusion radius, is set to Rp, and the maximum tolerance between the eccentric axis in a direction orthogonal to the axial direction and the center of the external gear is set to D, the following relationship is satisfied: Rcp≥{Rch×cos(θh)+D} / cos(θp), θh=tan -1 (Rh / Rch), θp=tan -1 (Rp / Rcp).

[0103] (2) An electric actuator according to (1), wherein when the eccentric axis is located on one side of a first direction orthogonal to the axial direction than the motor axis when viewed from the axial direction, the plurality of protrusions include a first protrusion, the first protrusion is arranged on one side of a second direction orthogonal to both the axial direction and the first direction than the motor axis, and a portion on the other side of the first direction and on one side in the circumferential direction contacts the inner side surface of the through hole portion, the external gear portion has a first external tooth portion whose tooth surface facing one side in the circumferential direction contacts a portion of the internal gear portion, a straight line passing through a portion of the outer circumferential surface of the first protrusion that contacts the through hole portion, i.e., the first contact portion, and the motor axis is set as a first straight line, a straight line passing through a portion of the first external tooth portion that contacts the internal gear portion, i.e., the second contact portion, and the eccentric axis is set as a second straight line, and an angle formed by the first straight line and the second straight line is greater than 148°.

[0104] (3) An electric actuator according to (1) or (2), wherein the pressure angles of the plurality of external teeth constituting the external gear portion and the pressure angles of the plurality of internal teeth constituting the internal gear portion are respectively greater than 22° and less than 25.5°.

[0105] (4) An electric actuator according to any one of (1) to (3), wherein the motor shaft is a hollow shaft, at least a portion of the output shaft is located inside the motor shaft, and the output shaft is rotatable about the motor axis.

[0106] (5) An actuator device comprising: the electric actuator according to any one of (1) to (4); and an object connected to the output shaft, wherein the electric actuator drives the object based on a shift operation of a vehicle.

Claims

1. An electric actuator, characterized in that: have: a motor having a motor shaft rotatable about a motor axis; a transmission mechanism connected to the motor shaft; an output shaft to which the rotation of the motor shaft is transmitted via the transmission mechanism; and a housing that accommodates the motor, the transmission mechanism, and the output shaft; The motor shaft has an eccentric shaft portion centered on an eccentric axis extending in a direction in which the motor axis extends. The transmission mechanism comprises: an annular external gear connected to the outer peripheral surface of the eccentric shaft portion via a bearing and to which the rotation of the motor shaft is transmitted; an annular internal gear, which is disposed radially outside the external gear and fixed to the housing; and an annular flange portion that transmits the rotation of the externally toothed gear to the output shaft, The externally toothed gear has a plurality of through-hole portions that penetrate the externally toothed gear in the axial direction and are arranged to surround the motor axis. The flange portion is provided with a plurality of protrusions which protrude from the flange portion in the axial direction and are arranged to surround the motor axis. Each of the plurality of protrusions is inserted into each of the plurality of through-holes. A portion of the internal gear portion provided along the inner peripheral surface of the internal gear meshes with a portion of the external gear portion provided along the outer peripheral surface of the external gear. The external gear part and the internal gear part are involute gears respectively. When the radius of the first pitch circle passing through the center of each of the plurality of through-hole portions, i.e., the first radius, is set as Rch, the radius of the second pitch circle passing through the center of each of the plurality of protrusions, i.e., the second radius, is set as Rcp, the radius of each of the plurality of through-hole portions, i.e., the hole radius, is set as Rh, the radius of each of the plurality of protrusions, i.e., the protrusion radius, is set as Rp, and the maximum tolerance between the eccentric axis and the center of the external gear in a direction orthogonal to the axial direction is set as D, the following relationship is satisfied: Rcp≥{Rch×cos(θh)+D} / cos(θp), θh=tan -1 (Rh / Rch), θp=tan -1 (Rp / Rcp)。 2. The electric actuator according to claim 1, characterized in that: When the eccentric axis is located on one side of the motor axis in a first direction orthogonal to the axial direction when viewed from the axial direction, The plurality of protrusions include a first protrusion, the first protrusion being arranged on one side of a second direction orthogonal to both the axial direction and the first direction relative to the motor axis, and a portion on the other side of the first direction and one side of the circumferential direction being in contact with an inner side surface of the through hole portion, The external gear portion includes a first external gear portion whose tooth surface facing one side in the circumferential direction contacts a portion of the internal gear portion. A straight line passing through a portion of the outer peripheral surface of the first protrusion that contacts the through hole portion, i.e., a first contact portion, and the motor axis is set as a first straight line, and a straight line passing through a portion of the first external tooth portion that contacts the internal gear portion, i.e., a second contact portion, and the eccentric axis is set as a second straight line, An angle formed by the first straight line and the second straight line is greater than or equal to 148°.

3. The electric actuator according to claim 1 or 2, characterized in that: The pressure angles of the plurality of external teeth constituting the external gear portion and the pressure angles of the plurality of internal teeth constituting the internal gear portion are respectively not less than 22° and not more than 25.5°.

4. The electric actuator according to claim 1 or 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.

5. An actuator device, characterized in that: have: The electric actuator according to any one of claims 1 to 4; and an object connected to the output shaft, The electric actuator drives the object based on a shift operation of the vehicle.

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