Electric Actuator

Abstract

To provide an electric actuator which can prevent entry of foreign objects into a space where a substrate is housed.SOLUTION: An electric actuator 10 includes a motor 40, a speed reduction mechanism, a substrate 60, a housing 50, and a substrate cover 70. The speed reduction mechanism reduces a speed of rotation of the motor 40 to transmit the rotation to an output shaft. Electronic components related to drive control of the motor 40 are mounted on the substrate 60. The housing 50 has a case 51 and a cover 58 and houses the motor 40, the speed reduction mechanism 42, and the substrate 60 therein. The substrate cover 70 engages with the case 51 in the housing 50 and separates the motor 40 and the speed reduction mechanism from the substrate 60.SELECTED DRAWING: Figure 10

Description

[Technical Field]

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

[0002] Conventionally, there has been known a configuration in which a control circuit for controlling the drive of a motor body is integrally assembled with the motor body. For example, in Patent Document 1, a circuit board is housed in a control circuit housing recess formed in an end frame. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-192214 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the housing is composed of three members: a motor case, an end frame that houses the circuit board, and a motor cover, so that the circuit board is in a separate space from the motor. When configured in this way, in order to seal both the motor and the circuit board, sealing structures are required in two places: between the motor case and the end frame, and between the end frame and the motor cover.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electric actuator that can prevent the intrusion of foreign matter with a simple configuration. [Means for solving the problem]

[0006] The electric actuator of the present invention includes a motor (40), a reduction mechanism (42), a circuit board (60), a housing (50), and a circuit board cover (70). The reduction mechanism reduces the rotation of the motor and transmits it to the output shaft (15). The circuit board is mounted with electronic components related to the drive control of the motor. The housing has a case (51) and a cover (58), and accommodates the motor, the reduction mechanism, and the circuit board. The circuit board cover is separate from the housing and engages with the case inside the housing, separating the motor and reduction mechanism from the entire circuit board. The case, circuit board, circuit board cover, motor and reduction mechanism, and cover are stacked in this order. The motor is arranged so that the motor housing (401) is separate from the case, cover, and board cover, and the motor axis extends along the top surface of the board cover. The motor and reduction mechanism are arranged side by side between the board covers. This makes it possible to prevent foreign matter from entering the inside of the board cover with a relatively simple configuration. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram showing a parking lock system according to a first embodiment. [Figure 2] 1 is a perspective view showing a state in which a cover of the electric actuator according to the first embodiment is removed. FIG. [Figure 3] FIG. 2 is a perspective view showing a case according to the first embodiment. [Figure 4] FIG. 2 is a plan view showing the case according to the first embodiment. [Figure 5] FIG. 2 is a perspective view showing a state in which a substrate is assembled into the case according to the first embodiment. [Figure 6] FIG. 2 is a perspective view showing a state in which a board cover is assembled to the case according to the first embodiment. [Figure 7] FIG. 2 is a plan view showing a state in which a board cover is assembled to the case according to the first embodiment. [Figure 8] FIG. 2 is a perspective view showing a board cover according to the first embodiment. [Figure 9] FIG. 2 is a plan view showing the board cover according to the first embodiment. [Figure 10] FIG. 3 is a cross-sectional view taken along line XX in FIG. 2. [Figure 11] FIG. 1 is a cross-sectional view taken along line XI-XI of FIG. [Figure 12]FIG. 11 is a schematic cross-sectional view showing a portion XII in FIG. [Figure 13] 5 is a schematic cross-sectional view corresponding to the cross section taken along line XIII-XIII in FIG. 4. [Figure 14] FIG. 6 is a cross-sectional view showing an electric actuator according to a second embodiment. [Figure 15] FIG. 15 is a cross-sectional view showing the XV portion in FIG. [Figure 16] FIG. 10 is a cross-sectional view showing an electric actuator according to a third embodiment. [Figure 17] FIG. 10 is a cross-sectional view showing an electric actuator according to a fourth embodiment. [Figure 18] FIG. 10 is a cross-sectional view showing an electric actuator according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An electric actuator according to the present invention will be described below with reference to the drawings. In the following, substantially identical components in a plurality of embodiments will be designated by the same reference numerals, and description thereof will be omitted.

[0009] (First embodiment) The first embodiment is shown in Figures 1 to 13. As shown in Figure 1, an electric actuator 10 is applied to a parking lock system 1. The parking lock system 1 includes the electric actuator 10, a detent mechanism 20, and a parking lock mechanism 30.

[0010] The electric actuator 10 is a rotary type and is configured, for example, with a brushed DC motor and a reduction gear mechanism. The electric actuator 10 functions as a drive source for the detent mechanism 20 by rotating the output shaft 15. Details of the electric actuator 10 will be described later.

[0011] The detent mechanism 20 has a detent plate 21, a detent spring 25, etc., and transmits the rotational driving force output from the electric actuator 10 to the parking lock mechanism 30.

[0012] The detent plate 21 is fixed to the output shaft 15 and driven by the electric actuator 10. On the side of the detent spring 25 of the detent plate 21, two valleys 211, 212 and a peak 215 separating the valleys 211, 212 are provided.

[0013] The detent spring 25 is an elastically deformable plate-shaped member, and has a detent roller 26 at its tip. The detent spring 25 biases the detent roller 26 toward the rotation center of the detent plate 21.

[0014] When a rotational force greater than or equal to a predetermined value is applied to the detent plate 21, the detent spring 25 elastically deforms, and the detent roller 26 moves between the valleys 211 and 212. When the detent roller 26 fits into either of the valleys 211 or 212, the oscillation of the detent plate 21 is restricted, and the state of the parking lock mechanism 30 is fixed.

[0015] The parking lock mechanism 30 has a parking rod 31, a cone 32, a parking lever 33, a shaft 34, and a parking gear 35. The parking rod 31 is formed in a generally L-shape, and one end 311 is fixed to the detent plate 21. The other end 312 of the parking rod 31 is provided with a cone 32. The cone 32 is formed so that its diameter decreases toward the other end 312. When the detent plate 21 rotates in a direction in which the detent roller 26 fits into the valley 211 corresponding to the P range, the cone 32 moves in the direction of arrow P.

[0016] The parking lever 33 abuts against the conical surface of the cone 32 and is provided so as to be able to swing around a shaft 34. A protrusion 331 that can mesh with the parking gear 35 is provided on the parking lever 33 on the parking gear 35 side. When the cone 32 moves in the direction of arrow P due to rotation of the detent plate 21, the parking lever 33 is pushed up and the protrusion 331 meshes with the parking gear 35. On the other hand, when the cone 32 moves in the direction not indicated by arrow P, the meshing between the protrusion 331 and the parking gear 35 is released.

[0017] The parking gear 35 is connected to a drive shaft (not shown) and is provided so as to be able to mesh with a protrusion 331 of the parking lever 33. When the parking gear 35 meshes with the protrusion 331, rotation of the drive shaft is restricted. When the shift range is a range other than P, i.e., a not P range, the parking gear 35 is not locked by the parking lever 33, and rotation of the drive shaft is not prevented by the parking lock mechanism 30. Furthermore, when the shift range is P range, the parking gear 35 is locked by the parking lever 33, and rotation of the drive shaft is restricted.

[0018] 2 to 11, the electric actuator 10 includes a motor 40, a reduction mechanism 42, a housing 50, a board 60, and a board cover 70. As shown in FIG. 2, the motor 40 is placed horizontally on the board cover 70 so that the motor shaft is approximately parallel to the bottom surface of the case 51.

[0019] The reduction mechanism 42 has a worm gear 43, a helical gear 44, an intermediate gear 45, a driven plate 46, and a driven shaft 47. In this embodiment, the gears constituting the reduction mechanism 42 are made of metal, but at least a part of them may be made of resin.

[0020] The worm gear 43 rotates integrally with the motor shaft of the motor 40. The helical gear 44 meshes with the worm gear 43 and the large diameter portion of the intermediate gear 45. The intermediate gear 45 has a large diameter portion and a small diameter portion, and the large diameter portion meshes with the helical gear 44 and the small diameter portion meshes with the driven plate 46. The helical gear 44 and the intermediate gear 45 are rotatably supported by a cover 58.

[0021] The driven plate 46 and the driven shaft 47 are integrally formed. The driven shaft 47 is rotatably supported by the cover 58 and is connected to the output shaft 15. As a result, the rotation of the motor 40 is transmitted to the output shaft 15 via the worm gear 43, the helical gear 44, the intermediate gear 45, the driven plate 46, and the driven shaft 47.

[0022] The housing 50 has a case 51 and a cover 58 (see FIG. 10). The case 51 and the cover 58 are fixed and sealed with bolts or the like. The motor 40, the speed reduction mechanism 42, the circuit board 60, and the circuit board cover 70 are housed inside the housing 50. Hereinafter, the case 51 side of the inside of the housing 50 will be referred to as the lower side, and the cover 58 side as the upper side.

[0023] 3 and 4, the case 51 is made of, for example, resin. The case 51 has a case bottom 52 and a case peripheral wall 53 that stands along the outer edge of the case bottom 52, and is formed in a generally rectangular shape in a plan view. A cylindrical portion 54 is integrally formed with the case 51 at a location corresponding to the driven shaft 47. The cylindrical portion 54 is formed in a cylindrical shape that opens toward the driven shaft 47, and is provided so that its end surface can abut against the driven shaft 47. The abutment of the driven shaft 47 and the cylindrical portion 54 causes the case 51 to bear the axial load of the driven shaft 47.

[0024] A cover insertion groove 55 is formed in the case bottom 52. The cover insertion groove 55 is composed of a bottom surface 551, an inner wall 552 on the case center side, and an outer wall 553 on the case peripheral wall 53 side. The bottom surface 551 is formed to be higher than the board-facing surface 521 of the inner wall 552 on the case center side. The cover insertion groove 55 is provided with enlarged portions 556, 557 on which flange portions 76, 77 of the board cover 70 described below are disposed. Pins 558 are provided to stand in the enlarged portions 556, 557.

[0025] A board fixing portion 56 is formed on the case center side of the inner wall 552. Terminals 61 are molded into the case bottom 52, with one end protruding from the case bottom 52. The terminals 61 include a motor terminal connected to the motor 40 and a sensor terminal used to send and receive signals from a rotational position sensor (not shown) and the like.

[0026] 5, the circuit board 60 is placed on the circuit board fixing portion 56 and fixed to the case 51 by nuts 63 provided on the circuit board fixing portion 56 and bolts (not shown). Electronic components such as a microcomputer for controlling the drive of the motor 40 and switching elements that constitute a driver circuit are mounted on the circuit board 60. The circuit board 60 is connected to terminals 61.

[0027] As shown in FIGS. 6 to 9, the board cover 70 has a first bottom 71, a second bottom 72, a cover peripheral wall 75, and flanges 76, 77, and is integrally formed from, for example, resin. The board cover 70 is disposed inside the case peripheral wall 53 and houses the board 60 therein. The second bottom 72 has a step 73 formed therein so that it is lower than the first bottom 71. In this embodiment, by making the second bottom 72, on which the motor 40 and the reduction mechanism 42 are disposed, lower than the first bottom 71, it is possible to reduce the size in the vertical direction of the paper in FIG. 10 and the like. Furthermore, the second bottom 72 is formed so as to avoid the tubular portion 54.

[0028] A motor holding portion 721 and gear support portions 722, 723 are formed on the second bottom portion 72. The motor holding portion 721 is formed in a substantially rectangular shape along the axial direction of the motor 40. As shown in FIG. 10 , a motor pressing portion 581 is formed on the cover 58, and the motor 40 is held in the housing 50 such that the motor housing 401 is sandwiched radially between the board cover 70 and the cover 58. Also, by assembling the cover 58 to the case 51, it can be understood that the cover 58 presses the board cover 70 toward the case 51 via the motor 40. In this embodiment, the case 51, the board 60, the board cover 70, the motor 40 and the reduction mechanism 42, and the cover 58 are layered in this order.

[0029] 11, gear support portion 722 supports one end of the rotation shaft of helical gear 44, and gear support portion 723 supports one end of the rotation shaft of intermediate gear 45. As a result, board cover 70 is configured to bear the axial load of helical gear 44 and intermediate gear 45.

[0030] 8 and 9, flanges 76, 77 extending outward are formed on the tip end of cover peripheral wall 75. The tip end of cover peripheral wall 75, including flanges 76, 77, is formed to be flush with one another and is inserted into cover insertion groove 55. Holes 761, 771 are formed in flanges 76, 77, respectively. In this embodiment, two flanges 76, 77 are provided, but the number, arrangement, shape, etc. of the flanges may be different.

[0031] 12 and 13 are schematic cross-sectional views illustrating the assembly relationship between the case 51 and the board cover 70. As shown in Fig. 12 and 13, the tip surface 755 of the cover peripheral wall 75 abuts against the bottom surface 551 of the cover insertion groove 55, forming a so-called labyrinth structure. Hereinafter, the abutting surface between the tip surface 755 of the cover peripheral wall 75 and the bottom surface 551 of the cover insertion groove 55 will be referred to as the labyrinth abutting surface.

[0032] In this embodiment, the motor 40, the reduction mechanism 42, and the circuit board 60 are housed in the same housing 50. Therefore, by providing a circuit board cover 70 inside the housing 50, wear particles and the like generated by the motor 40 and the reduction mechanism 42 are prevented from entering the circuit board 60 side.

[0033] In this embodiment, the assembly location of the case 51 and the board cover 70 has a labyrinth structure, and foreign matter from outside the board cover 70 is prevented from entering at the labyrinth abutment surface. This makes it possible to omit a sealing member such as an adhesive for sealing the case 51 and the board cover 70.

[0034] Furthermore, in this embodiment, the board 60 is provided above the cover insertion groove 55. For example, if the electric actuator 10 is mounted on a vehicle with the cover 58 side facing up in the vertical direction, even if a foreign object enters the inside of the board cover 70 from the labyrinth abutment surface and climbs over the inner wall 552, it will fall vertically downward, i.e., on the side opposite the board 60, preventing the foreign object from reaching the board 60. Note that if the electric actuator 10 is mounted upside down, the labyrinth abutment surface will be vertically above the opening of the cover insertion groove 55, making it unlikely that the foreign object will reach the labyrinth abutment surface against gravity.

[0035] 7 and 13, pins 558 are inserted into holes 761, 771 formed in flanges 76, 77, and board cover 70 is fixed to case 51 by heat caulking or the like. In this embodiment, the board cover fixing surface, which is the surface pressed by pin 558, and the labyrinth abutment surface are formed on the same plane. This makes it possible to prevent gaps from being generated at the abutment points between case 51 and board cover 70, and to suppress the intrusion of foreign matter.

[0036] As described above, the electric actuator 10 includes the motor 40, the reduction mechanism 42, the circuit board 60, the housing 50, and the circuit board cover 70. The reduction mechanism 42 reduces the rotation of the motor 40 and transmits it to the output shaft 15. The circuit board 60 is mounted with electronic components related to the drive control of the motor 40. The housing 50 has a case 51 and a cover 58, and accommodates the motor 40, the reduction mechanism 42, and the circuit board 60 inside. The circuit board cover 70 accommodates the circuit board 60 inside, and engages with the case 51 inside the housing 50, separating the motor 40 and the reduction mechanism 42 from the circuit board 60.

[0037] By providing the board cover 70 inside the housing 50, the number of sealing points can be limited to one, the case 51 and the cover 58, thereby simplifying the configuration of the housing 50. Furthermore, it is possible to prevent foreign matter such as wear powder generated from the motor 40 and the reduction mechanism 42 from reaching the board 60 and causing an abnormality such as a short circuit.

[0038] The board cover 70 has bottoms 71 and 72 and a peripheral cover wall 75. The case 51 is formed with a cover insertion groove 55 into which the tip end of the peripheral cover wall 75 is inserted. The cover insertion groove 55 is made up of a bottom surface 551 that abuts against a tip end surface 755 of the peripheral cover wall 75, an inner wall 552 formed on the inner periphery of the bottom surface, and an outer wall 553 that faces the inner wall 552 and is formed on the outer periphery of the bottom surface 551. The abutment between the bottom surface 551 of the cover insertion groove 55 and the tip end surface 751 of the peripheral cover wall 75 forms a so-called labyrinth structure, which makes it possible to prevent foreign matter from entering the interior of the board cover 70 even if the case 51 and the board cover 70 are not completely sealed.

[0039] The board 60 is disposed closer to the bottoms 71 and 72 than the cover insertion groove 55. In other words, the board 60 is disposed higher on the paper surface in Fig. 10 etc. than the cover insertion groove 55. This prevents the board 60 from reaching the motor 40 and the speed reduction mechanism 42 even if the motor 40 and the speed reduction mechanism 42 are mounted vertically higher than the board 60 and a foreign object enters the board cover 70.

[0040] The board cover 70 has flanges 76, 77 whose tip ends extend outward on the same plane as a tip surface 755. The cover insertion groove 55 is formed with enlarged portions 556, 557 that correspond to the flanges 76, 77 and where the inner wall 552 and the outer wall 553 are spaced apart more than in other locations. The case 51 and the board cover 70 are fixed at the contact points between the flanges 76, 77 and the enlarged portions 556, 557. By configuring the fixing surfaces of the case 51 and the board cover 70 to be on the same plane as the labyrinth contact surfaces, it is possible to prevent gaps from forming between the case 51 and the board cover 70 and to inhibit the intrusion of foreign matter into the board cover 70.

[0041] The motor 40 has a motor housing 401 sandwiched radially between the board cover 70 and the cover 58. This makes it possible to suppress radial vibration of the motor 40. Furthermore, by pressing the board cover 70 in the insertion direction into the cover insertion groove 55 by the cover 58 via the motor housing 401, it is possible to bias the board cover 70 so that no gaps form on the labyrinth abutment surface, without the need for a separate fixing structure such as a screw.

[0042] The board cover 70 is formed with gear support portions 722, 723 that support the shaft portions of the helical gear 44 and intermediate gear 45, which are at least one of the gears that make up the speed reduction mechanism 42. This allows the overall size to be made smaller than when a separate member is used to provide a structure for bearing the axial load of the gears 44, 45.

[0043] The motor 40 drives the parking lock mechanism 30. This simplifies the configuration of the electric actuator 10 related to driving the parking lock mechanism 30.

[0044] (Second embodiment) 14 and 15 show a second embodiment. In this embodiment, the board cover 170 differs from the above-described embodiment, and this point will be mainly described. The board cover 170 has a bottom 171 and a peripheral cover wall 175. The tip side of the peripheral cover wall 175 is inserted into the cover insertion groove 55, and the tip surface 775 comes into contact with the bottom surface 551 of the cover insertion groove 55 to form a labyrinth structure, as in the above-described embodiment.

[0045] The cover peripheral wall 175 has an inclined portion 176 that inclines from the outer wall 553 side toward the inner wall 552. The inclination start point S of the inclined portion 176 is located closer to the labyrinth contact surface than the end face of the outer wall 553. In other words, if the height of the inclination start point S from the labyrinth contact surface is h1 and the height from the labyrinth contact surface to the outer wall 553 is h2, then h2 > h1. In FIG. 15, the position of the labyrinth contact surface is indicated by "R."

[0046] When the electric actuator 10 is mounted on a vehicle with its height direction perpendicular to the vertical direction, foreign matter falling from above in the vertical direction is guided along the inclined portion 176 in a direction away from the labyrinth abutment surface. This makes it possible to prevent foreign matter from entering the inside of the board cover 70, regardless of the mounting direction of the electric actuator 10. In Figures 14 and 15, the upper side in the vertical direction is designated as "top" and the lower side in the vertical direction is designated as "bottom."

[0047] In this embodiment, the peripheral wall 175 has an inclined portion 176 that inclines from the outer wall 553 side to the inner wall 552 side. The inclination start point S of the inclined portion 176 is closer to the bottom surface 551 than the end face of the outer wall 553. As a result, even if the electric actuator 10 is mounted with one side of the labyrinth structure facing upward in the vertical direction, foreign matter that falls onto the board cover 70 slides down the inclined portion 176 in the direction of gravity and moves away from the labyrinth abutment surface side. This makes it possible to prevent foreign matter from entering the inside of the board cover 70 regardless of the mounting orientation. In addition, the same effects as those of the above embodiment are achieved.

[0048] (Third embodiment) The third embodiment is shown in Fig. 16. Although Fig. 16 shows the board cover 70 of the first embodiment, it may also be the board cover 170 of the second embodiment. The same applies to the fourth and fifth embodiments.

[0049] In the third embodiment, an elastic member 81 is provided between the motor 40 and the board cover 70. This makes it possible to suppress radial vibration of the motor 40. Furthermore, because the board cover 70 can be held down from above, the leading end surface 755 of the board cover 70 can be properly abutted against the bottom surface 551 of the cover insertion groove 55. This simplifies the configuration compared to, for example, a case where a fixing structure such as a screw is provided to press the board cover 70 against the case 51. Note that, although the elastic member 81 is provided separately here, the board cover 70 itself may be configured to have elasticity.

[0050] In this embodiment, an elastic member 81 is provided between the motor 40 and the board cover 70. This absorbs positional variations between the motor 40 and the board cover 70, making it possible to hold the motor 40 appropriately and also preventing a gap from forming between the leading end surface 755 of the board cover 70 and the bottom surface 551 of the cover insertion groove 55. This also provides the same effects as the above embodiment.

[0051] (Fourth and fifth embodiments) A fourth embodiment is shown in FIG. 17, and a fifth embodiment is shown in FIG. 18. In the fourth and fifth embodiments, elastic members 82, 83 are provided between the substrate 60 and the substrate cover 70. In the fourth embodiment, the elastic member 82 is provided between the substrate 60 and the second bottom 72, and in the fifth embodiment, the elastic member 83 is provided between the substrate 60 and the first bottom 71. The number and locations of the elastic members are arbitrary. By providing the elastic members 82, 83 between the substrate 60 and the substrate cover 70, vibration of the substrate 60 can be suppressed. In addition, the same effects as the above embodiments can be achieved.

[0052] In the embodiment, the first bottom 71, the second bottom 72 and the bottom 171 correspond to the "bottom", the cover peripheral walls 75, 175 correspond to the "periphery wall", the elastic member 81 corresponds to the "motor holding elastic member", and the elastic members 82, 83 correspond to the "board holding elastic member".

[0053] (Other embodiments) In the above embodiment, the reduction mechanism is composed of a worm gear, a helical gear, an intermediate gear, etc. In other embodiments, the configuration of the reduction mechanism and the number of reduction stages may differ from those in the above embodiment. For example, in the above embodiment, the helical gear and the intermediate gear are rotatably supported by the cover. In other embodiments, the gears constituting the reduction gear may be configured to be rotatably supported by the case or the board cover. Also, in the above embodiment, the driven plate and the driven shaft are integrally formed, but in other embodiments, they may be separate. In the above embodiment, the board is fixed to the case with bolts or the like. In other embodiments, fixing members and fixing methods other than bolts may be used to fix the board to the case, such as heat caulking.

[0054] In the above embodiment, the case and the board cover are fixed by heat caulking. In other embodiments, the case and the board cover may be fixed by a method other than heat caulking, and the fixing method, fixing location, etc. may be set arbitrarily. In the above embodiment, a step is provided on the bottom of the board cover. In other embodiments, a step may not be provided on the bottom of the board cover.

[0055] In the above embodiment, the motor is a brushed DC motor. In other embodiments, the motor may be a motor other than a brushed DC motor. In the above embodiment, two valleys are provided on the detent plate. In other embodiments, the number of valleys is not limited to two and may be three or more. Furthermore, the detent mechanism, parking lock mechanism, etc. may be different from those in the above embodiment.

[0056] In the above embodiment, the electric actuator is applied to a parking lock system. In other embodiments, the electric actuator may be applied to an in-vehicle system other than a parking lock system, or a drive system other than an in-vehicle system. As described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. [Explanation of symbols]

[0057] 10 Electric actuator 15 Output shaft 40 Motor 42 Reduction mechanism 50···Housing 51 Case 55 Cover insertion groove 58···Cover 60... board 70, 170 Circuit board cover 75, 175... Cover peripheral wall (peripheral wall)

Claims

1. a motor (40); a speed reduction mechanism (42) that reduces the rotation of the motor and transmits it to an output shaft (15); a substrate (60) on which electronic components related to the drive control of the motor are mounted; a housing (50) having a case (51) and a cover (58) and accommodating the motor, the reduction mechanism, and the substrate therein; a substrate cover (70, 170) that is separate from the housing and engages with the case inside the housing to separate the motor and the reduction mechanism from the entire substrate; Equipped with the case, the substrate, the substrate cover, the motor and the reduction mechanism, and the cover are stacked in this order; The motor has a motor housing (401) that is separate from the case, the cover, and the board cover, and is disposed so that the motor axis extends in a direction along the top surface of the board cover, The motor and the reduction mechanism are arranged side by side between the board cover and the cover.

2. The substrate cover has a bottom (71, 72, 171) and a peripheral wall (75, 175), 2. The electric actuator according to claim 1, wherein the case comprises a bottom surface (551) that abuts against the tip surface (755) of the peripheral wall, an inner wall (552) formed on the inner periphery of the bottom surface, and an outer wall (553) that faces the inner wall and is formed on the outer periphery of the bottom surface, and a cover insertion groove (55) into which the tip side of the peripheral wall is inserted is formed.

3. The electric actuator according to claim 2 , wherein the substrate is disposed closer to the bottom than the cover insertion groove.

4. The substrate cover has a flange portion (76, 77) whose tip side is on the same plane as the tip surface and extends to the outer circumferential side, The cover insertion groove is formed with an enlarged portion (556, 557) corresponding to the flange portion and in which the inner wall and the outer wall are spaced apart from each other.

4. The electric actuator according to claim 2, wherein the case and the board cover are fixed together at a contact point between the flange and the expanded portion.

5. The peripheral wall (175) has an inclined portion (176) inclined from the outer wall side to the inner wall side, The electric actuator according to any one of claims 2 to 4, wherein the inclination start point of the inclined portion is closer to the bottom surface than the end surface of the outer wall.

6. The electric actuator according to any one of claims 1 to 5, wherein the motor housing is sandwiched between the board cover and the cover from the radial direction.

7. 7. The electric actuator according to claim 6, wherein a motor holding elastic member (81) is provided between the motor and the board cover.

8. An electric actuator according to any one of claims 1 to 7, wherein the substrate cover is formed with a gear support portion (722, 723) that supports the shaft portion of at least one gear (44, 45) that constitutes the reduction mechanism.

9. The electric actuator according to any one of claims 1 to 8, wherein a board holding elastic member (82, 83) is provided between the board and the board cover.

10. The electric actuator according to any one of claims 1 to 9, wherein the motor drives a parking lock mechanism (30).

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