Electric actuator

Abstract

To provide a technique for suppressing the deformation of a raceway track of a rotary ring.SOLUTION: An electric actuator 1 includes a motor 2 having a rotary shaft 2a, a planetary gear mechanism 4 for decelerating the rotation of the rotary shaft 2a, a ball screw mechanism 6 having a screw shaft 30 to be rotationally driven by the planetary gear mechanism 4, for converting the rotating motion of the rotary shaft 2a into linear motion, and a rolling bearing 8 having an inner ring 24 provided on the screw shaft 30 in an integrally rotatable manner, for rotatably supporting the screw shaft 30, the planetary gear mechanism 4 including a plurality of planetary gears 14, and an annular carrier 16 having a first annular surface 16a abutting on a side face 24b in the axial direction of the inner ring 24 for holding the plurality of planetary gears 14, the first annular surface 16a having an engaging part 40 capable of transmitting the rotation of the carrier 16 to the inner ring 24, the side face 24b having an engaged part 42 engaged with the engaging part 40.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an electric actuator including a motor, a planetary gear mechanism, and a ball screw mechanism. A rolling bearing is externally fitted to the screw shaft included in the ball screw mechanism. The inner ring (rotating ring) of the rolling bearing and the screw shaft are integrally rotatable. A plurality of carrier pins for holding a plurality of planetary gears of the planetary gear mechanism are provided on the axial side surface of the inner ring. Therefore, the inner ring functions as a carrier of the planetary gear mechanism. Thus, the planetary gear mechanism transmits the rotation by the motor to the screw shaft via the inner ring of the rolling bearing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional example, the plurality of carrier pins are press-fitted and fixed in the hole portions provided on the side surface of the inner ring. Here, when a carrier pin is press-fitted into the hole portion, the influence of the strain generated by the press-fitting may reach the entire inner ring, and the orbit of the inner ring may be deformed. When the orbit of the inner ring is deformed, it may cause a decrease in the rotation accuracy of the screw shaft and a decrease in the life of the rolling bearing. Therefore, a measure for suppressing the deformation occurring in the orbit of the inner ring (rotating ring) has been desired.

Means for Solving the Problems

[0005] The electric actuator according to the embodiment includes a motor having a rotation axis, a planetary gear mechanism that decelerates the rotation of the rotation axis, a ball screw mechanism having a screw shaft that is rotationally driven by the planetary gear mechanism and that converts the rotational motion of the rotation axis into a linear motion, a rotating ring that is provided so as to be integrally rotatable with the screw shaft, and a rolling bearing that rotatably supports the screw shaft. The planetary gear mechanism includes a plurality of planetary gears, and an annular carrier that has a first annular surface that abuts against a side surface in the axial direction of the rotating ring and that holds the plurality of planetary gears. The first annular surface has a meshing portion capable of transmitting the rotation of the carrier to the rotating ring. The side surface has a meshed portion that meshes with the meshing portion.

Effect of the Invention

[0006] According to the present disclosure, deformation occurring in the orbit of the rotating ring can be suppressed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6A

Figure 6B

Mode for Carrying Out the Invention

[0008] First, the content of the embodiment will be listed and described. [Overview of the Embodiment] (1) The electric actuator according to the embodiment includes a motor having a rotating shaft, a planetary gear mechanism that decelerates the rotation of the rotating shaft, a ball screw mechanism having a screw shaft that is rotationally driven by the planetary gear mechanism and that converts the rotational motion of the rotating shaft into a linear motion, a rotating wheel that is provided so as to be integrally rotatable with the screw shaft, and a rolling bearing that rotatably supports the screw shaft. The planetary gear mechanism includes a plurality of planetary gears and an annular carrier that has a first annular surface that abuts against a side surface in the axial direction of the rotating wheel and holds the plurality of planetary gears. The first annular surface has a meshing portion capable of transmitting the rotation of the carrier to the rotating wheel. The side surface has a meshed portion that meshes with the meshing portion.

[0009] According to the above configuration, the rotation of the carrier can be transmitted to the rotating wheel by the meshing of the meshing portion of the carrier and the meshed portion of the side surface of the rotating wheel. Therefore, unlike the above conventional example, it is not necessary to press-fit a carrier pin into the rotating wheel, and deformation occurring in the orbit of the rotating wheel can be suppressed. In addition, since high precision is required in forming a hole for press-fitting the carrier pin, a large number of processing man-hours are required, which has been a factor in cost increase. In this regard, in the present embodiment, since it is not necessary to press-fit a carrier pin into the rotating wheel, it is not necessary to form a hole, an increase in processing man-hours can be suppressed, and costs can be suppressed.

[0010] (2) In the electric actuator of (1) above, when the first annular surface further has a first opposing surface that faces and abuts against the side surface, the meshing portion includes a plurality of convex portions that protrude axially with respect to the first opposing surface and extend along the radial direction, and it is preferable that the directions in which the plurality of convex portions extend intersect each other. Since the plurality of convex portions extend along the radial direction, the rotation of the carrier can be effectively transmitted to the rotating wheel. In addition, since the directions in which the plurality of convex portions extend intersect each other, if the plurality of convex portions mesh with the meshing portions on the side surface, it is possible to suppress the relative displacement in the radial direction between the carrier and the rotating ring.

[0011] (3) In the electric actuator according to (2) above, when the carrier further has a second annular surface on the opposite side of the first annular surface, provided with a plurality of carrier pins for holding the plurality of planetary gears, the circumferential positions of the plurality of convex portions and the circumferential positions of the plurality of carrier pins may coincide with each other. In this case, the thickness of the carrier at the base end portion of the carrier pin increases by the amount of the convex portion. As a result, the rigidity of the base end portion of the carrier pin can be increased.

[0012] (4) In the electric actuator according to (2) above, when the carrier further has a second annular surface on the opposite side of the first annular surface, provided with a plurality of carrier pins for holding the plurality of planetary gears, the circumferential positions of the plurality of convex portions and the circumferential positions of the plurality of carrier pins may be different from each other. In this case, the restrictions imposed by the positions of the plurality of carrier pins when arranging the convex portions can be relaxed, and the convex portions can be appropriately arranged.

[0013] (5) In the electric actuator according to any one of (2) to (4) above, when the side surface further has a second opposing surface that opposes and abuts against the first opposing surface, the meshing portion may include a plurality of concave portions that are provided corresponding to the plurality of convex portions and are recessed axially with respect to the second opposing surface. In this case, the meshing portion and the meshed portion can surely mesh with each other.

[0014] (6) In the electric actuator according to any one of (1) to (5) above, the carrier may further have an engaging protrusion that is provided at a peripheral edge portion of the carrier and engages with a circumferential surface of the rotating ring so as to be held in a state where the first annular surface and the side surface are in contact with each other. In this case, for example, when transporting the electric actuator in a disassembled state or when assembling the electric actuator, the carrier can be easily temporarily assembled with respect to the inner ring, and the workability can be improved.

[0015] (7) Further, in the electric actuator, the meshing portion and the meshed portion may include side face splines that mesh with each other. Also in this case, the meshing portion and the meshed portion can surely mesh with each other.

[0016] [Details of Embodiment] Hereinafter, preferred embodiments will be described with reference to the drawings. Note that at least a part of each of the embodiments described below may be arbitrarily combined.

[0017] FIG. 1 is a cross-sectional view showing an example of an electric actuator according to an embodiment. In FIG. 1, a case where the electric actuator 1 is used in a brake system is illustrated. The brake system has a function of generating hydraulic pressure for operating the brake. The brake system includes a hydraulic unit that generates hydraulic pressure. The hydraulic unit has a piston P. When the piston P is pressed, the hydraulic unit generates hydraulic pressure for operating the brake.

[0018] The electric actuator 1 has a function of pressing the piston P. The electric actuator 1 includes a motor 2, a planetary gear mechanism 4, a ball screw mechanism 6, a rolling bearing 8, and a housing 10. The housing 10 houses the planetary gear mechanism 4, the ball screw mechanism 6, and the rolling bearing 8. The piston P is provided on one end side of the housing 10. The motor 2 is provided on the other end side of the housing.

[0019] In the following description, the direction along the central axis C of the screw shaft 30 of the ball screw mechanism 6 is referred to as the axial direction. Further, the direction orthogonal to the central axis C is referred to as the radial direction. Further, the direction along the circle centered on the central axis C is referred to as the circumferential direction. Further, the direction from the motor 2 side toward the piston P side in the axial direction is referred to as the first axial direction, and the direction from the piston P side toward the motor 2 side in the axial direction is referred to as the second axial direction. The electric actuator 1 presses the piston P in the first axial direction.

[0020] The housing 10 includes a first housing portion 10a and a second housing portion 10b. The first housing portion 10a is disposed on the piston P side (first axial direction side) of the housing 10. The second housing portion 10b is disposed on the motor 2 side (second axial direction side) of the housing 10. The planetary gear mechanism 4, the ball screw mechanism 6, and the rolling bearing 8 are accommodated in an internal space formed when the first housing portion 10a and the second housing portion 10b are combined. The motor 2 is fixed to the end face 10b1 on the second axial direction side of the second housing portion 10b.

[0021] The motor 2 has a rotating shaft 2a. The motor 2 outputs a rotational force by the rotating shaft 2a. The axis center of the rotating shaft 2a coincides with the central axis C. The rotating shaft 2a is disposed in the through hole 10b2. The through hole 10b2 is a hole of the second housing portion 10b. The through hole 10b2 is a cylindrical hole. The center of the through hole 10b2 coincides with the central axis C.

[0022] The planetary gear mechanism 4 includes a sun gear 12, a plurality of planetary gears 14, an internal gear 18, and a carrier 16. The sun gear 12 is fixed to the rotating shaft 2a. The sun gear 12 has a hole portion 12a and a gear portion 12b. The rotating shaft 2a is inserted into the hole portion 12a. Therefore, the center of the hole portion 12a coincides with the central axis C. The sun gear 12 is fixed to the rotating shaft 2a so as to be integrally rotatable. The gear portion 12b is provided on the outer peripheral surface of the sun gear 12. The gear portion 12b is a gear centered on the central axis C. When the rotating shaft 2a rotates, the gear portion 12b also rotates.

[0023] The internal gear 18 is provided on the inner peripheral surface of the second housing portion 10b. Therefore, the internal gear 18 does not rotate with respect to the housing 10. The center of the internal gear 18 coincides with the central axis C.

[0024] The plurality of planetary gears 14 are arranged between the gear portion 12b of the sun gear 12 and the internal gear 18. The plurality of planetary gears 14 mesh with the sun gear 12 and the internal gear 18. The plurality of planetary gears 14 are arranged at equal intervals around the sun gear 12 centered on the central axis C. Note that there are three planetary gears 14 in this embodiment.

[0025] The carrier 16 is an annular member that rotatably holds the three planetary gears 14. The carrier 16 has a first annular surface 16a and a second annular surface 16b. The first annular surface 16a is the surface of the carrier 16 facing in the first axial direction. The second annular surface 16b is the surface of the carrier 16 facing in the second axial direction. The second annular surface 16b has a plurality (three) of carrier pins 20. The plurality of carrier pins 20 rotatably support the plurality of planetary gears 14. Therefore, when the rotating shaft 2a of the motor 2 rotates and the sun gear 12 rotates, the plurality of planetary gears 14 revolve around the sun gear 12 while rotating. Therefore, the plurality of carrier pins 20 move in the circumferential direction around the sun gear 12. As a result, the carrier 16 rotates around the central axis C. The planetary gear mechanism 4 decelerates the rotation of the rotating shaft 2a and outputs the decelerated rotation as the rotation of the carrier 16. The first annular surface 16a of the carrier 16 is in contact with the rolling bearing 8.

[0026] The rolling bearing 8 is, for example, a four-point contact ball bearing and rotatably supports the screw shaft 30 of the ball screw mechanism 6 with respect to the housing 10. The rolling bearing 8 includes an outer ring 22, an inner ring 24, a plurality of balls 26, and a cage 28. The outer ring 22 is fitted and fixed to the inner peripheral surface of the second housing portion 10b and the inner peripheral surface of the first housing portion 10a. The inner ring 24 is externally fitted and fixed to the end portion on the second axial direction side of the screw shaft 30. The inner ring 24 and the screw shaft 30 are rotatable integrally. The first annular surface 16a of the carrier 16 abuts against the side surface 24b on the second axial direction side of the inner ring 24. The first annular surface 16a has an engaging portion 40 capable of transmitting the rotation of the carrier 16 to the inner ring 24. Also, the side surface 24b of the inner ring 24 has an engaged portion 42 that engages with the engaging portion. By the engaging portion 40 and the engaged portion 42 engaging with each other, the rotation of the carrier 16 is transmitted to the inner ring 24. The engaging portion 40 of the carrier 16 and the engaged portion 42 of the inner ring 24 will be described in detail later.

[0027] The plurality of balls 26 are interposed between the outer ring raceway 22a and the inner ring raceway 24a so as to be freely rollable. The cage 28 holds the plurality of balls 26 in the circumferential direction. Thereby, the outer ring 22 and the inner ring 24 are relatively rotatable. Also, the outer ring 22 is a fixed ring fixed to the housing 10. The inner ring 24 is a rotating ring that rotates relative to the outer ring 22. In this way, the rolling bearing 8 is fixed to the inner peripheral surface of the housing 10 and rotatably supports the screw shaft 30 with respect to the housing 10. Also, the screw shaft 30 is restricted from moving in the axial direction by being fixed to the rolling bearing 8. Therefore, the rolling bearing 8 also supports the axial direction (thrust direction) load generated by the operation of the ball screw mechanism 6.

[0028] The ball screw mechanism 6 has a function of converting the rotational motion of the rotating shaft 2a into a linear motion. The ball screw mechanism 6 includes the above-described screw shaft 30, a nut 32, and a plurality of balls (not shown). The screw shaft 30 has a spiral screw groove 30a and a fixed surface 30b on its outer peripheral surface. The fixed surface 30b is a cylindrical surface provided at the end portion on the second axial direction side of the screw shaft 30. The fixed surface 30b is fitted and fixed to the inner peripheral surface 24d of the inner ring 24. The screw groove 30a is provided on the first axial direction side of the fixed surface 30b.

[0029] The nut 32 is a cylindrical member. The nut 32 is arranged so as to surround the screw groove 30a of the screw shaft 30. The nut 32 has a spiral screw groove 32a on its inner peripheral surface. The screw groove 32a constitutes a rolling path together with the screw groove 30a of the screw shaft 30. The rolling path is a spiral orbit provided between the screw groove 30a and the screw groove 32a. A plurality of balls are arranged so as to be rollable along the rolling path.

[0030] The end portion of the nut 32 on the first axial direction side protrudes from the housing 10. The nut 32 is inserted into the hole portion 10a1 of the first housing portion 10a. A seal member 11 is provided on the inner peripheral surface of the hole portion 10a1. The seal member 11 seals between the inner peripheral surface of the hole portion 10a1 and the outer peripheral surface 32c of the nut 32. A piston P is fixed to the end surface 32b of the nut 32 on the first axial direction side. Thereby, the piston P and the nut 32 are connected. The piston P and the nut 32 are integrally movable in the axial direction.

[0031] Also, the nut 32 is allowed to move axially with respect to the housing 10. On the other hand, the rotation of the nut 32 around the central axis C with respect to the housing 10 is restricted.

[0032] In the ball screw mechanism 6 having the above configuration, when the screw shaft 30 rotates, a plurality of balls transfer along the rolling path and move the nut 32 in the axial direction. The axial position of the nut 32 shown in FIG. 1 is the position closest to the rolling bearing 8. The nut 32 shown in FIG. 1 has not yet pressed the piston P. Therefore, when the nut 32 moves in the first axial direction from the position in FIG. 1, it presses the piston P. When the nut 32 in FIG. 1 moves in the first axial direction, the piston P is axially pressed by the nut 32, and the hydraulic unit generates hydraulic pressure.

[0033] Here, the screw shaft 30 is integrally rotatable with the inner ring 24. The rotation of the carrier 16 is transmitted to the inner ring 24 as described above. Therefore, the screw shaft 30 is rotationally driven by the planetary gear mechanism 4 to which the rotational force of the motor 2 is applied. In this way, the electric actuator 1 decelerates the rotational motion of the rotary shaft 2a by the planetary gear mechanism 4, and further transmits the rotational motion to the screw shaft 30, thereby rotating the screw shaft 30 and converting it into a linear motion (motion along the central axis C) by the nut 32. The electric actuator 1 presses the piston P in the first axial direction by the linear motion of the nut 32.

[0034] FIG. 2 is a perspective view showing the carrier 16 and the inner ring 24. FIG. 3A is a front view of the second annular surface 16b of the carrier 16 in FIG. 2, and FIG. 3B is a front view of the first annular surface 16a of the carrier 16 in FIG. 2. As described above, the carrier 16 is an annular metal member. The carrier 16 is integrally formed including the carrier pins 20 by casting, forging, or the like. The carrier 16 has a first annular surface 16a and a second annular surface 16b. As shown in FIGS. 2 and 3A, the second annular surface 16b has a side surface 34 in addition to the three carrier pins 20 described above. The three carrier pins 20 project in the second axial direction from the side surface 34. The three carrier pins 20 are provided at equal intervals of 120 degrees in the circumferential direction.

[0035] As shown in FIGS. 2 and 3B, the first annular surface 16a has a first opposing surface 36 in addition to the meshing portion 40 described above. The first opposing surface 36 is a surface that opposes and abuts against the side surface 24b of the inner ring 24. The meshing portion 40 includes a plurality (two in the illustrated example) of convex portions 41. The two convex portions 41 project in the first axial direction with respect to the first opposing surface 36. The two convex portions 41 extend along the radial direction. The two convex portions 41 are provided from the outer peripheral surface 16c to the inner peripheral surface 16d. The outer peripheral surface 16c is the outer peripheral surface of the carrier 16. The inner peripheral surface 16d is the inner peripheral surface of the carrier 16.

[0036] The protruding height of the two convex portions 41 is constant along the radial direction. Also, the cross-section orthogonal to the longitudinal direction of the two convex portions 41 has a rectangular shape, and the width dimension in the direction orthogonal to the longitudinal direction of the two convex portions 41 and parallel to the first opposing surface 36 is constant. The directions in which the two convex portions 41 extend intersect with each other. More specifically, the directions in which the two convex portions 41 extend are orthogonal to each other.

[0037] Also, as shown in FIGS. 3A and 3B, the circumferential positions of the two convex portions 41 and the circumferential positions of the three carrier pins 20 are different from each other. By adopting such an arrangement, the constraints imposed by the positions of the three carrier pins 20 when arranging the convex portions 41 can be relaxed, and the convex portions 41 can be appropriately arranged.

[0038] FIG. 4 is a front view of the side surface 24b of the inner ring 24 in FIG. 2. As shown in FIGS. 2 and 4, the side surface 24b has a second opposing surface 38 in addition to the above-described meshed portion 42. The second opposing surface 38 is a surface that opposes and abuts against the first opposing surface 36 of the carrier 16. The meshed portion 42 includes a plurality (two in the illustrated example) of concave portions 43. The two concave portions 43 are recessed in the first axial direction with respect to the second opposing surface 38. The two concave portions 43 extend along the radial direction in the same manner as the convex portions 41. The two concave portions 43 are provided from the outer peripheral surface 24c to the inner peripheral surface 24d. The outer peripheral surface 24c is the outer peripheral surface of the inner ring 24. The inner peripheral surface 24d is the inner peripheral surface of the inner ring 24.

[0039] The depth of the two recesses 43 from the second opposing surface 38 is constant along the radial direction. Also, the cross-section orthogonal to the longitudinal direction of the two recesses 43 is rectangular, and the width dimension in the direction orthogonal to the longitudinal direction of the two recesses 43 and parallel to the first opposing surface 36 is constant. The directions in which the two recesses 43 extend are orthogonal to each other, similar to the two protrusions 41.

[0040] The dimensions and arrangements of the respective parts of these two recesses 43 are set such that when the first opposing surface 36 and the second opposing surface 38 are brought into contact, the two recesses 43 and the two protrusions 41 mesh with each other. That is, the two recesses 43 are provided corresponding to the two protrusions 41. Thus, in this embodiment, the meshing portion 40 of the carrier 16 has two protrusions 41, and the meshed portion 42 of the inner ring 24 has two recesses 43 that mesh with the meshing portion 40 of the carrier 16. As a result, the meshing portion 40 and the meshed portion 42 can surely mesh with each other, and the meshing portion 40 can transmit the rotation of the carrier 16 to the inner ring 24.

[0041] According to the above configuration, the rotation of the carrier 16 can be transmitted to the inner ring 24 by the meshing portion 40 of the carrier 16 and the meshed portion 42 on the side surface 24b of the inner ring 24 meshing with each other. Therefore, unlike the above conventional example, it is not necessary to press-fit a carrier pin into the inner ring, and deformation occurring in the raceway of the inner ring can be suppressed. Also, in the formation of the hole for press-fitting the carrier pin, high precision is required, which requires a large number of processing steps and is a factor in cost increase. In this regard, in this embodiment, since it is not necessary to press-fit the carrier pin 20 into the inner ring 24, there is no need to form a hole, the increase in processing steps can be suppressed, and the cost can be suppressed.

[0042] In addition, in the present embodiment, the extending directions of the two convex portions 41 intersect each other, and further, since the two convex portions 41 extend along the radial direction, the rotation of the carrier 16 is transmitted to the inner ring 24 through the entire longitudinal directions of the two convex portions 41. Therefore, the rotation of the carrier 16 can be effectively transmitted to the inner ring 24. Also, since the extending directions of the two convex portions 41 intersect each other, if the two convex portions 41 mesh with the two concave portions 43 of the meshing portion 42, it is possible to suppress the relative displacement in the radial direction between the carrier 16 and the inner ring 24.

[0043] FIG. 5 is a diagram showing the carrier 16 according to the modified example. In this modified example, it is different from the above embodiment in that three convex portions 41 are provided, and the circumferential positions of the three convex portions 41 and the circumferential positions of the three carrier pins 20 coincide with each other.

[0044] The three convex portions 41 of this modified example are provided at equal intervals of 120 degrees in the circumferential direction. In this case, the thickness of the carrier 16 at the base end portion of the carrier pin 20 increases by the amount of the convex portion 41. As a result, the rigidity of the base end portion of the carrier pin 20 can be increased.

[0045] FIG. 6A is a perspective view showing the carrier 16 according to another modified example. In this modified example, it is different from the above embodiment in that the carrier 16 further has a plurality of engaging protrusions 50.

[0046] The plurality of engaging protrusions 50 engage with the outer peripheral surface 24c of the inner ring 24 and have a function of holding the carrier 16 on the inner ring 24 so that the first annular surface 16a and the side surface 24b are in contact with each other. In the present embodiment, three engaging protrusions 50 are provided corresponding to the three carrier pins 20. The three engaging protrusions 50 are provided at the peripheral edge portion of the carrier 16. The three engaging protrusions 50 protrude from the first annular surface 16a in the first axial direction.

[0047] FIG. 6B is a cross-sectional view showing a main part of the carrier 16 in a state where it is mounted on the inner ring 24. As shown in FIG. 6B, the engaging projection 50 has a main body portion 50a and a curved portion 50b. The main body portion 50a is a belt-shaped member that extends from the peripheral edge of the carrier 16 along the outer peripheral surface 24c of the inner ring 24. The curved portion 50b is a member provided at the tip of the main body portion 50a. The curved portion 50b is curved radially inward from the main body portion 50a. The curved portion 50b is fitted into the outer peripheral groove 24c1. The outer peripheral groove 24c1 is a groove that is recessed radially with respect to the outer peripheral surface 24c of the inner ring 24.

[0048] By the curved portion 50b being fitted into the outer peripheral groove 24c1, the engaging projection 50 engages with the inner ring 24. When the engaging projection 50 engages with the inner ring 24, the carrier 16 is held in a state where the first annular surface 16a of the carrier 16 and the side surface 24b of the inner ring 24 are in contact. Further, the engaging projection 50 can be elastically deformed appropriately. Therefore, by elastically deforming the engaging projection 50, the engagement by the engaging projection 50 can be easily released. Therefore, the carrier 16 can be easily attached to and detached from the inner ring 24.

[0049] As described above, since the carrier 16 of the present embodiment has the engaging projection 50 that engages with the inner ring 24 so that the carrier 16 is held in a state where the first annular surface 16a and the side surface 24b are in contact, for example, when transporting the electric actuator 1 in a disassembled state or when assembling the electric actuator 1, the carrier 16 can be easily temporarily assembled with respect to the inner ring 24, and the workability can be improved.

[0050] 〔Others〕 The embodiments disclosed this time are illustrative in all respects and not restrictive. For example, in the above-described embodiment, the case where the engaging portion 40 includes two convex portions 41 and the engaged portion 42 includes two concave portions 43 has been exemplified. However, the number of the convex portions 41 and the concave portions 43 may be three or more. Further, the engaging portion 40 may have a plurality of concave portions, and the engaged portion 42 may have a plurality of convex portions. Further, the engaging portion 40 and the engaged portion 42 may be side face splines that engage with each other. Also in this case, the engaging portion 40 and the engaged portion 42 can surely engage with each other.

[0051] The scope of the rights of the present invention is not limited to the above-described embodiment, and includes all modifications within the scope equivalent to the configuration described in the claims.

Explanation of Reference Numerals

[0052] 1 Electric actuator 2 Motor 2a Rotating shaft 4 Planetary gear mechanism 6 Ball screw mechanism 8 Rolling bearing 14 Planetary gear 16 Carrier 16a First annular surface 16b Second annular surface 20 Carrier pin 22 Outer ring 24 Inner ring 24b Side surface 24c Outer peripheral surface 30 Screw shaft 36 First opposing surface 38 Second opposing surface 40 Engaging portion 41 Convex portion 42 Engaged portion 43 Concave portion 50 Engagement protrusion

Claims

1. A motor having a rotating shaft, A planetary gear mechanism for decelerating the rotation of the rotating shaft, A ball screw mechanism having a screw shaft that is rotationally driven by the planetary gear mechanism and that converts the rotational motion of the rotating shaft into linear motion, A rolling bearing having a rotating wheel that is integrally rotatable with the screw shaft and that rotatably supports the screw shaft, The planetary gear mechanism includes A plurality of planetary gears, An annular carrier having a first annular surface that abuts against a side surface in the axial direction of the rotating wheel and that holds the plurality of planetary gears, The first annular surface has an engagement portion capable of transmitting the rotation of the carrier to the rotating wheel, The side surface has an engaged portion that engages with the engagement portion An electric actuator.

2. The first annular surface further has a first opposing surface that faces and abuts against the side surface, The engagement portion includes a plurality of convex portions that protrude axially with respect to the first opposing surface and extend along the radial direction, The directions in which the plurality of convex portions extend intersect each other The electric actuator according to Claim 1.

3. The carrier further has a second annular surface on the opposite side of the first annular surface, provided with a plurality of carrier pins for holding the plurality of planetary gears, The circumferential positions of the plurality of convex portions and the circumferential positions of the plurality of carrier pins coincide with each other The electric actuator according to Claim 2.

4. The carrier further has a second annular surface on the opposite side of the first annular surface, provided with a plurality of carrier pins for holding the plurality of planetary gears, The circumferential positions of the plurality of convex portions and the circumferential positions of the plurality of carrier pins are different from each other The electric actuator according to Claim 2.

5. The side surface further has a second opposing surface that faces and abuts against the first opposing surface, The engaged portion is provided corresponding to the plurality of convex portions and includes a plurality of concave portions that are recessed axially with respect to the second opposing surface The electric actuator according to Claim 2.

6. The carrier further has an engagement protrusion that is provided at a peripheral portion of the carrier and that engages with a circumferential surface of the rotating wheel so as to be held in a state where the first annular surface and the side surface are in contact with each other The electric actuator according to any one of Claims 1 to 5.

7. The engagement portion and the engaged portion include side face splines that engage with each other The electric actuator according to Claim 1.

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