CN216290514U - Electric actuator - Google Patents

Abstract

The present invention provides an electric actuator, comprising: a motor having a drive shaft that rotates about a first central axis; a circuit board having an axial direction as a board thickness direction; and a plurality of electronic components mounted on the circuit board. A plurality of the electronic components include: a first element mounted on a first mounting surface of the circuit board facing one side in a board thickness direction; and a second element that is attached to a second attachment surface of the circuit board facing the other side in the plate thickness direction, and that has a dimension in the plate thickness direction that is larger than a dimension in the plate thickness direction of the first element. The axial position of the second element overlaps the axial position of the motor.

Description

Electric actuator

Technical Field

The present invention relates to an electric actuator.

Background

Electric actuators in which electronic components are housed inside a housing are known. Patent document 1 discloses an actuator including a motor, a circuit board having an electronic component mounted on one surface thereof, and a case housing the motor and the circuit board. In this actuator, the electronic components are disposed radially outside the motor, thereby achieving a reduction in thickness.

Patent document 1: japanese patent laid-open publication No. 2015-145168

A plurality of electronic components of various sizes are mounted on the circuit board. Therefore, when all the electronic components are arranged radially outward of the motor, the radial dimension of the actuator may be increased.

SUMMERY OF THE UTILITY MODEL

In view of the above circumstances, an object of the present invention is to provide an electric actuator capable of reducing the dimensions in the axial direction and the radial direction.

A first aspect of the present invention provides an electric actuator including: a motor having a drive shaft that rotates about a first central axis; a circuit board having an axial direction as a board thickness direction; and a plurality of electronic components mounted on the circuit board. A plurality of the electronic components include: a first element mounted on a first mounting surface of the circuit board facing one side in a board thickness direction; and a second element that is attached to a second attachment surface of the circuit board facing the other side in the plate thickness direction, and that has a dimension in the plate thickness direction that is larger than a dimension in the plate thickness direction of the first element. The axial position of the second element overlaps the axial position of the motor.

In the electric actuator according to the second aspect of the present invention, at least two of the second elements are arranged in the circumferential direction of the first central axis.

An electric actuator according to a third aspect of the present invention is the electric actuator according to the first or second aspect, including: a driven shaft that rotates about a second central axis extending in parallel with the first central axis; and a power transmission portion that transmits power from the drive shaft to the driven shaft, at least two of the second elements being arranged along a circumferential direction of the second central axis.

An electric actuator according to a fourth aspect of the present invention is the electric actuator according to the third aspect, wherein the electric actuator has a bearing for supporting the driven shaft so as to be rotatable, and at least a part of the second element is disposed inside a region surrounded by an outer shape of the motor, an outer shape of the bearing, and a common tangent line therebetween, as viewed in an axial direction.

An electric actuator according to a fifth aspect of the present invention is the electric actuator according to the third aspect, wherein the electric actuator includes a driven gear fixed to the driven shaft and to which power is transmitted from the motor side, and at least a part of the second element is disposed inside a pitch circle of the driven gear when viewed from the axial direction.

An electric actuator according to a sixth aspect of the present invention is the electric actuator according to the fifth aspect, wherein the driven gear is a sector gear, and at least a part of the second element overlaps a driving locus of the driven gear when viewed from the axial direction.

An electric actuator according to a seventh aspect of the present invention is the electric actuator according to the first or second aspect, wherein the second element is a capacitor or a choke coil.

According to the present invention, it is possible to provide an electric actuator that can be downsized in the axial direction and the radial direction.

Drawings

Fig. 1 is a sectional view of an electric actuator according to an embodiment.

Fig. 2 is a bottom view of an electric actuator according to an embodiment.

Description of the reference symbols

10: an electric actuator; 40: a motor; 41: a motor shaft (drive shaft); 50: a speed reduction mechanism (power transmission unit); 61: a driven shaft; 62: a driven gear; 65: a bearing; 70: a circuit board; 70 a: a first mounting surface (mounting surface); 73: an electronic component; 75: a first element; 76: a second element; 78: a choke coil; 79: a capacitor; c: a pitch circle; j1: a central axis (first central axis); j3: an output center axis (second center axis); p: an area; VL: common tangent line.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, XYZ coordinate systems are appropriately shown in the respective drawings. In the following description, the Z-axis direction is a vertical direction in which the positive side is an upper side and the negative side is a lower side. An axial direction of a central axis (first central axis) J1, which is an imaginary axis appropriately shown in each drawing, is parallel to the Z-axis direction, i.e., the vertical direction. In the following description, a direction parallel to the axial direction of the center axis J1 will be simply referred to as "axial direction". Unless otherwise specified, a radial direction about the central axis J1 is simply referred to as a radial direction, and a circumferential direction about the central axis J1 is simply referred to as a circumferential direction.

In the present embodiment, a plan view means an axial view from above or below. The vertical direction, the upper side, and the lower side are only names for describing the relative positional relationship of the respective parts, and the actual arrangement relationship and the like may be an arrangement relationship other than the arrangement relationship and the like indicated by these names.

Fig. 1 is a sectional view of an electric actuator 10 of the present embodiment.

The electric actuator 10 is mounted to a vehicle. More specifically, the electric actuator 10 is mounted on a Shift-by-wire (Shift-by-wire) type actuator device that is driven in accordance with a Shift operation by a driver of the vehicle.

The electric actuator 10 has a motor 40, a speed reduction mechanism (power transmission portion) 50, an output portion 60, a housing 11, a bus bar unit 90, a circuit board 70, and a plurality of electronic components 73.

As shown in fig. 1, the motor 40 includes a motor shaft (drive shaft) 41, a first bearing 44a, a second bearing 44b, a third bearing 44c, a fourth bearing 44d, a rotor body 42, a stator 43, and a motor sensor magnet 45. The motor shaft 41 extends in the axial direction.

The first bearing 44a, the second bearing 44b, the third bearing 44c, and the fourth bearing 44d support the motor shaft 41 rotatably about the center axis J1. In the present embodiment, the first bearing 44a, the second bearing 44b, the third bearing 44c, and the fourth bearing 44d are, for example, ball bearings.

The eccentric shaft portion 41a, which is a portion of the motor shaft 41 supported by the third bearing 44c, has a cylindrical shape extending around an eccentric axis J2 that is parallel to the central axis J1 and is eccentric with respect to the central axis J1. The portion of the motor shaft 41 other than the eccentric shaft portion 41a has a columnar shape extending around the central axis J1.

The rotor body 42 is fixed to the motor shaft 41. The rotor body 42 includes a rotor core fixed to the motor shaft 41 and a rotor magnet fixed to an outer peripheral portion of the rotor core.

The stator 43 is disposed radially outward of the rotor body 42 with a gap therebetween. The stator 43 is annular surrounding the radially outer side of the rotor main body 42. The stator 43 includes, for example, a stator core, a plurality of insulators, and a plurality of coils. Each coil is attached to a tooth of the stator core via an insulator.

A holding recess 46 for holding the motor sensor magnet 45 is provided on the upper end surface of the motor shaft 41. The holding recess 46 is recessed toward the lower side and opened at the upper side. The holding recess 46 is circular in plan view about the central axis J1. The upper end surface of the motor shaft 41 provided with the holding recess 46 is disposed below the circuit board 70.

The motor sensor magnet 45 has a columnar shape centered on the central axis J1. The motor sensor magnet 45 is fitted into the holding recess 46. Thereby, the motor sensor magnet 45 is fixed to the upper end portion of the motor shaft 41. The motor sensor magnet 45 faces a lower surface (a second mounting surface 70b described later) of the circuit board 70 with a gap therebetween.

The speed reduction mechanism 50 is coupled to the motor 40. In the present embodiment, the speed reduction mechanism 50 is coupled to the lower side of the motor shaft 41. The speed reduction mechanism 50 is disposed below the rotor body 42 and the stator 43. The reduction mechanism 50 has an external gear 51, an internal gear 52, and an output gear 53. The speed reduction mechanism 50 may be coupled to the upper side of the motor shaft 41.

The external gear 51 has an annular plate shape extending in the radial direction of the eccentric axis J2 around the eccentric axis J2 of the eccentric shaft portion 41 a. A gear portion is provided on the radially outer side surface of the external gear 51. The external gear 51 is connected to the motor shaft 41 via a third bearing 44 c. Thereby, the speed reduction mechanism 50 is coupled to the motor shaft 41. The external gear 51 is fitted to the outer ring of the third bearing 44c from the radially outer side. Thereby, the third bearing 44c couples the motor shaft 41 and the externally toothed gear 51, and allows the motor shaft 41 and the externally toothed gear 51 to rotate relative to each other about the eccentric axis J2.

The external gear 51 has a plurality of holes 51a penetrating the external gear 51 in the axial direction. Although not shown, the plurality of holes 51a are arranged at equal intervals over the entire circumference in the circumferential direction around the eccentric axis J2. The hole 51a has a circular shape as viewed in the axial direction.

The internal gear 52 surrounds the radially outer side of the external gear 51. The gear portion of the internal gear 52 meshes with the gear portion of the external gear 51. The internal gear 52 has an annular shape centered on the central axis J1. The outer peripheral portion of the internal gear 52 has a polygonal shape such as a regular dodecagon, for example, and is fixed in a state of being stopped by a cap 14 described later.

The output gear 53 has an output gear main body 53a and a plurality of pins 53 b. The output gear main body 53a is disposed above the external gear 51 and the internal gear 52. The output gear main body 53a has an annular plate shape extending in the radial direction about the center axis J1. A gear portion is provided on the radially outer surface of the output gear body 53 a. The output gear main body 53a is connected to the motor shaft 41 via a fourth bearing 44 d.

The plurality of pins 53b are cylindrical and protrude downward from the lower surface of the output gear main body 53 a. Although not shown, the plurality of pins 53b are arranged at equal intervals in the circumferential direction over the entire circumference. The pin 53b has an outer diameter smaller than the inner diameter of the hole 51 a. The plurality of pins 53b pass through the plurality of holes 51a from the upper side, respectively. The outer peripheral surface of the pin 53b is inscribed in the inner peripheral surface of the hole 51 a. The inner peripheral surface of the hole 51a supports the external gear 51 via the pin 53b so as to be swingable around the central axis J1.

The output portion 60 is a portion that outputs the driving force of the electric actuator 10. The output portion 60 is disposed radially outward of the motor 40. The output unit 60 includes a driven shaft 61, a driven gear 62, and an output unit sensor magnet 63.

The driven shaft 61 has a cylindrical shape extending in the axial direction. Since the driven shaft 61 extends in the same direction as the motor shaft 41 in this way, the configuration of the speed reduction mechanism 50 for transmitting the rotation of the motor shaft 41 to the driven shaft 61 can be simplified. The driven shaft 61 is coupled to the motor shaft 41 via the reduction mechanism 50. In the present embodiment, the driven shaft 61 is cylindrical with the output central axis (second central axis) J3 as the center. The output center axis J3 extends parallel to the center axis J1. The output center axis J3 is arranged radially away from the center axis J1. That is, the motor shaft 41 and the driven shaft 61 are arranged apart from each other in the radial direction of the motor shaft 41. Therefore, the electric actuator 10 can be downsized in the axial direction compared to the case where the motor shaft 41 and the driven shaft 61 are arranged in line in the axial direction. Further, the motor shaft 41 and the driven shaft 61 may be arranged in the axial direction.

The driven shaft 61 is connected to the motor shaft 41 of the motor 40 via the reduction mechanism 50. The driven shaft 61 rotates about the output center axis J3 in accordance with the rotation of the motor 40. That is, the electric actuator 10 includes: a motor 40 having a motor shaft 41; a motor shaft 41; and a speed reduction mechanism 50 that transmits power from the motor shaft 41 to the driven shaft.

The driven shaft 61 is open on the lower side. The driven shaft 61 has spline grooves on an inner peripheral surface. The driven shaft 61 is disposed at a position overlapping the rotor body 42 in the radial direction of the motor shaft 41. A driven shaft (not shown) is inserted into and coupled to the driven shaft 61 from below. More specifically, the driven shaft 61 is coupled to the driven shaft by fitting a spline portion provided on the outer peripheral surface of the driven shaft into a spline groove provided on the inner peripheral surface of the driven shaft 61. The driving force of the electric actuator 10 is transmitted to the driven shaft via the driven shaft 61. Thereby, the electric actuator 10 rotates the driven shaft about the output center axis J3.

A holding recess 64 for holding the output section sensor magnet 63 is provided on the upper end surface of the driven shaft 61. The holding recess 64 is recessed toward the lower side and opened at the upper side. The holding recess 64 is circular in plan view with the output center axis J3 as the center. The upper end surface of the driven shaft 61 provided with the holding recess 64 is disposed below the circuit board 70.

The driven gear 62 is fixed to the driven shaft 61 and meshes with the output gear 53. In the present embodiment, the driven gear 62 is fixed to the outer peripheral surface of the driven shaft 61. The driven gear 62 extends from the driven shaft 61 toward the output gear 53. The driven gear 62 is a gear having a sector shape in a plan view. The driven gear 62 has a gear portion at an end portion on the output gear 53 side. The gear portion of the driven gear 62 meshes with the gear portion of the output gear 53. That is, the electric actuator 10 has a driven gear 62 fixed to the driven shaft 61 and to which power is transmitted from the motor 40 side.

The output portion sensor magnet 63 has a columnar shape centered on the output center axis J3. The output portion sensor magnet 63 is fitted into the holding recess 64. Thereby, the output portion sensor magnet 63 is fixed to the upper end portion of the driven shaft 61. The output portion sensor magnet 63 faces a lower surface (a second mounting surface 70b described later) of the circuit board 70 with a gap therebetween.

When the motor shaft 41 rotates about the center axis J1, the eccentric shaft 41a revolves in the circumferential direction around the center axis J1. The revolution of the eccentric shaft portion 41a is transmitted to the external gear 51 via the third bearing 44c, and the external gear 51 swings while changing the position at which the inner circumferential surface of the hole 51a is inscribed in the outer circumferential surface of the pin 53 b. Thereby, the position at which the gear portion of the external gear 51 meshes with the gear portion of the internal gear 52 changes in the circumferential direction. Therefore, the rotational force of the motor shaft 41 is transmitted to the internal gear 52 via the external gear 51.

Here, in the present embodiment, the internal gear 52 is fixed and therefore does not rotate. Therefore, the external gear 51 is rotated about the eccentric axis J2 by the reaction force of the rotational force transmitted to the internal gear 52. At this time, the direction in which the external gear 51 rotates is opposite to the direction in which the motor shaft 41 rotates. The rotation of the external gear 51 about the eccentric axis J2 is transmitted to the output gear 53 via the hole 51a and the pin 53 b. Thereby, the output gear 53 rotates about the center axis J1. The rotation of the motor shaft 41 is decelerated and transmitted to the output gear 53.

When the output gear 53 rotates, the driven gear 62 meshed with the output gear 53 rotates about the output center axis J3. Thereby, the driven shaft 61 fixed to the driven gear 62 rotates about the output center axis J3. In this way, the rotation of the motor 40 is transmitted to the output portion 60 via the speed reduction mechanism 50.

The bus bar unit 90 is located at an upper side of the rotor main body 42. The bus bar unit 90 is disposed on a lower surface of a partition wall 32a, which will be described later, of the housing 11. The bus bar unit 90 includes an arc-shaped bus bar holder 91 centered on the central axis J1 in a plan view, and a plurality of bus bars 92 held by the bus bar holder 91. The bus bar 92 is provided with, for example, six. In the case of the present embodiment, the bus bar holder 91 is manufactured by insert molding in which the bus bar 92 is an insert member.

One end 92a of the bus bar 92 protrudes upward from the upper surface of the bus bar holder 91. In the present embodiment, the end portion 92a of the bus bar 92 on one side is formed in a straight band shape extending in the axial direction, and penetrates the circuit board 70 from the lower side to the upper side. The end portion 92a is electrically connected to the circuit board 70 at a position penetrating the circuit board 70 by a connection method such as soldering, welding, press-fitting, or the like. Although not shown, the other end of the bus bar 92 grips a coil lead wire drawn from the coil of the stator 43 and is connected to the coil by welding or fusing. Thereby, the stator 43 and the circuit board 70 are electrically connected via the bus bar 92.

The circuit board 70 is disposed above the motor 40, the bus bar unit 90, and the output unit 60. The circuit board 70 is located on the upper side of the motor shaft 41 and the driven shaft 61. The circuit board 70 has a plate shape with its plate surface facing in the axial direction. The circuit board 70 is connected to the coils of the stator 43 via the bus bar unit 90. The circuit board 70 is connected to a power supply via a connector portion, not shown. That is, the circuit board 70 is electrically connected with the motor 40 and the power supply.

The board surface of the circuit board 70 is perpendicular to the axial direction. The circuit board 70 extends along the XY plane. That is, the board 70 has the axial direction as the board thickness direction. The thickness direction of the circuit board 70 is the Z-axis direction. In the following description, the "thickness direction" refers to the thickness direction of the circuit board 70. One side in the thickness direction is an upper side, and the other side in the thickness direction is a lower side.

The circuit board 70 has a first mounting surface (mounting surface) 70a and a second mounting surface 70b facing opposite sides of each other in the board thickness direction. The first mounting surface 70a is an upper surface, and the second mounting surface 70b is a lower surface. A plurality of electronic components 73 are mounted on the first mounting surface 70a and the second mounting surface 70b, respectively. The circuit board 70 and the electronic components 73 function as an inverter device that controls the motor 40. The inverter device of the present embodiment includes a converter circuit and an inverter circuit.

The plurality of electronic components 73 include a plurality of first elements 75, a plurality of second elements 76, a motor sensor 71, and an output sensor 72. The first element 75 is mounted to the first mounting surface 70 a. The second element 76, the motor sensor 71, and the output sensor 72 are mounted on the second mounting surface 70 b. The height dimension of the second element 76 is greater than the height dimension of the first element 75.

Here, the height dimension of each electronic component 73 is a dimension of the circuit board 70 along the board thickness direction.

The motor sensor 71 is fixed to a portion of the second mounting surface 70b of the circuit board 70 that faces the motor sensor magnet 45 in the board thickness direction of the circuit board 70 with a gap therebetween. In the present embodiment, the motor sensor 71 is disposed on the central axis J1. The motor sensor 71 is a magnetic sensor that detects the magnetic field of the motor sensor magnet 45. The motor sensor 71 detects the rotation position of the motor sensor magnet 45 by detecting the magnetic field of the motor sensor magnet 45, thereby detecting the rotation of the motor shaft 41.

The output portion sensor 72 is fixed to a portion of the second mounting surface 70b of the circuit board 70 that faces the output portion sensor magnet 63 in the board thickness direction of the circuit board 70 with a gap therebetween. In the present embodiment, the output portion sensor magnet 63 is disposed on the output center axis J3. The output unit sensor 72 is a magnetic sensor that detects the magnetic field of the output unit sensor magnet 63. The output portion sensor 72 detects the rotation position of the output portion sensor magnet 63 by detecting the magnetic field of the output portion sensor magnet 63, thereby detecting the rotation of the driven shaft 61.

The plurality of first elements 75 include transistors and the like constituting a converter circuit and an inverter circuit. Some of the transistors function as a part of a converter circuit that converts an ac current input from a power supply into a dc current. In addition, a part of the transistors function as a part of an inverter circuit that converts a direct current into an alternating current and supplies the alternating current to the motor 40. The heat generation amount of the transistor is larger than that of the other electronic component 73. A heat sink 5 is disposed between the transistor and the case 11. Thereby, the heat of the transistor is released to the case 11.

The plurality of second elements 76 include choke coils 78 and capacitors 79. The second element 76 functions as a part of a converter circuit that converts an alternating current input from a power supply into a direct current.

The axial position of the second element 76 overlaps the axial position of the motor 40. The second element 76 is disposed radially outward of the motor 40. Among the electronic components mounted on the circuit board 70, the choke coil 78 and the capacitor 79 as the second element 76 have the largest height dimension. On the other hand, the motor 40 has the largest dimension in the axial direction among the members housed in the housing 11. Therefore, the axial position of the second element 76 overlaps with the axial position of the motor 40, and the housing space of the housing 11 can be reduced in the axial direction. As a result, the axial dimension of the electric actuator 10 can be reduced.

Further, according to the present embodiment, the first element 75 having a relatively small height dimension among the plurality of electronic components 73 is disposed on the first mounting surface 70a of the circuit board 70. Therefore, the circuit board 70 can be made smaller than in the case where the first element 75 is mounted to the second mounting surface 70b together with the second element 76. In addition, a part of the first element 75 disposed on the first mounting surface 70a overlaps the motor 40 when viewed from the axial direction. Therefore, although the axial dimension of the electric actuator 10 is slightly increased, the radial dimension of the electric actuator 10 can be significantly reduced. As a result, the electric actuator 10 can be downsized as a whole.

Fig. 2 is a bottom view of the electric actuator 10. In fig. 2, the housing 11 is not shown.

The electric actuator 10 has three capacitors 79 and one choke coil 78 as the second element 76. Here, the three capacitors 79 are referred to as a first capacitor 79A, a second capacitor 79B, and a third capacitor 79C, respectively.

In the present embodiment, the first capacitor 79A and the second capacitor 79B are arranged along the circumferential direction of the central axis J1. By configuring at least two second elements 76 to be arranged along the circumferential direction of the center axis J1 in this way, the electric actuator 10 can be downsized with respect to the radial dimension of the center axis J1.

In the present embodiment, the first to third capacitors 79A, 79B, 79C and the choke coil 78 are arranged along the circumferential direction of the output central axis J3. In this way, by configuring at least two second elements 76 to be arranged along the circumferential direction of the output center axis J3, the electric actuator 10 can be downsized with respect to the radial dimension of the output center axis J3.

As shown in fig. 2, when viewed from the axial direction, a pair of common tangents VL is assumed which are the outer shape of motor 40 (i.e., the outer shape of stator 43 in the present embodiment) and the outer shape of bearing 65 which rotatably supports driven shaft 61. In the present embodiment, the first capacitor 79A, the second capacitor 79B, and a part of the choke coil 78 are disposed inside the region P surrounded by the outer shape of the motor 40, the outer shape of the bearing 65, and the common tangent line VL therebetween, when viewed from the axial direction. The region P is an uncut region in the area of the electric actuator 10 projected in the axial direction, and therefore cannot contribute to downsizing. Since at least a part of the second element 76 is disposed inside the region P, the region outside the region P can be reduced in size. This can reduce the projection area of the electric actuator 10 in the axial direction.

Fig. 2 illustrates a pitch circle C of the driven gear 62. The first to third capacitors 79A, 79B, and 79C and the choke coil 78 are disposed inside the pitch circle C of the driven gear 62. The pitch circle C of the driven gear 62 virtually represents the operating range of the driven gear 62. According to the present embodiment, since at least a part of the second element 76 is disposed inside the pitch circle C when viewed from the axial direction, the projected area of the electric actuator 10 in the axial direction can be reduced in size. In the present embodiment, the driven gear 62 is a sector gear. In the driven gear 62, at least a part of the second element 76 overlaps with the driving locus of the driven gear as viewed in the axial direction. Therefore, the projected area of the electric actuator 10 in the axial direction can be reduced in size.

As shown in fig. 1, the housing 11 houses the motor 40, the speed reduction mechanism 50, the output portion 60, the circuit board 70, the electronic component 73, and the bus bar unit 90. The housing 11 includes a housing main body 12, a cover 13, and a cap 14. The cover 13 is fixed to an upper opening 12a of the housing main body 12. Cap 14 is fixed to opening 12b on the lower side of case body 12.

The housing main body 12 has: a square-cylindrical outer wall portion 30 that constitutes a housing of the electric actuator 10; a bottom wall portion 31 that extends radially inward from a lower end of the outer wall portion 30; and a motor housing portion 32 and a driven shaft holding portion 33 provided to the bottom wall portion 31. That is, the housing 11 has an outer wall portion 30, a bottom wall portion 31, a motor housing portion 32, and a driven shaft holding portion 33.

In the present embodiment, the outer wall portion 30 has a pentagonal square tubular shape when viewed in the axial direction. The outer wall portion 30 surrounds the motor housing portion 32 from the radially outer side. The upper opening of the outer wall 30 is an upper opening 12a of the housing main body 12. The circuit board 70 is housed inside the opening 12 a.

The bottom wall 31 has an opening that opens on the lower side. A cylindrical wall 31a protruding downward from the bottom wall 31 is provided at the periphery of the opening of the bottom wall 31. The opening surrounded by the cylindrical wall 31a is an opening 12b on the lower side of the case main body 12. The motor housing portion 32 and the driven shaft holding portion 33 are provided on the upper surface of the bottom wall portion 31.

The motor housing portion 32 has a cylindrical shape surrounding the motor 40 from the radially outer side. In the present embodiment, the motor housing portion 32 has a cylindrical shape that is open on the lower side with the center axis J1 as the center. The motor housing portion 32 holds the motor 40 inside. More specifically, the stator 43 of the motor 40 is fixed to the inner circumferential surface of the motor case 32. The motor case 32 includes a cylindrical portion 32b extending upward from the bottom wall 31 and an annular plate-shaped partition wall 32a extending radially inward from an upper end of the cylindrical portion 32 b.

The partition wall 32a is located between the stator 43 and the bus bar unit 90 in the axial direction. The partition wall 32a has a bearing holding portion 32c at the center as viewed in the axial direction. The bearing holding portion 32c is cylindrical and extends in the axial direction. The second bearing 44b is held on the inner peripheral surface of the bearing holding portion 32 c. The partition wall 32a also serves as a bearing holder, and thus the electric actuator 10 can be prevented from being enlarged in the axial direction.

The circuit board 70 is fixed to the partition wall 32a by a plurality of bolts 96. The bolts 96 penetrate the circuit board 70 in the board thickness direction from the upper side of the circuit board 70, and are fastened to the screw holes of the partition wall 32 a. Thereby, the housing main body 12 supports the circuit board 70.

The driven shaft holding portion 33 is cylindrical and extends upward from the bottom wall portion 31. A part of the side surface of the driven shaft holding portion 33 is connected to the side surface of the motor housing portion 32. The driven shaft holding portion 33 has a hole portion 33a axially penetrating the driven shaft holding portion 33. A cylindrical bearing 65 is fitted inside the hole 33 a. The bearing 65 is a sliding bearing. Driven shaft 61 is fitted inside bearing 65. The bearing 65 supports the driven shaft 61 rotatably about the output center axis J3. That is, the electric actuator 10 has a bearing 65 that rotatably supports the driven shaft 61.

While various embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are examples, and additions, omissions, substitutions, and other modifications of the configurations can be made without departing from the spirit of the present invention. The present invention is not limited to the embodiments.

The application of the electric actuator to which the present invention is applied is not particularly limited, and the electric actuator may be mounted on a device other than a vehicle. In addition, the respective structures described in the present specification can be appropriately combined within a range not inconsistent with each other.

Claims (7)

1. An electric actuator, characterized in that,

the electric actuator includes:

a motor having a drive shaft that rotates about a first central axis;

a circuit board having an axial direction as a board thickness direction; and

a plurality of electronic components mounted on the circuit board,

a plurality of the electronic components include:

a first element mounted on a first mounting surface of the circuit board facing one side in a board thickness direction; and

a second element that is attached to a second attachment surface of the circuit board facing the other side in a plate thickness direction and has a dimension in the plate thickness direction larger than a dimension of the first element in the plate thickness direction,

the axial position of the second element overlaps the axial position of the motor.

2. The electric actuator according to claim 1,

at least two of the second elements are arranged along a circumference of the first central axis.

3. The electric actuator according to claim 1 or 2,

the electric actuator includes:

a driven shaft that rotates about a second central axis extending in parallel with the first central axis; and

a power transmission unit that transmits power from the drive shaft to the driven shaft,

at least two of the second elements are arranged along a circumference of the second central axis.

4. The electric actuator according to claim 3,

the electric actuator has a bearing for supporting the driven shaft so that the driven shaft can rotate,

at least a part of the second element is disposed inside a region surrounded by an outer shape of the motor, an outer shape of the bearing, and a common tangent line therebetween, when viewed in an axial direction.

5. The electric actuator according to claim 3,

the electric actuator has a driven gear fixed to the driven shaft and to which power is transmitted from the motor side,

at least a part of the second element is disposed inside a pitch circle of the driven gear when viewed in an axial direction.

6. The electric actuator according to claim 5,

the driven gear is a sector gear which is,

at least a portion of the second element overlaps with a drive locus of the driven gear when viewed from the axial direction.

7. The electric actuator according to claim 1 or 2,

the second element is a capacitor or a choke coil.

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