Electric actuator

Abstract

To provide an electric actuator capable of efficiently acquiring bottom position rotation angles of a plurality of valley parts.SOLUTION: An electric actuator comprises an output shaft, a motor, a speed reducer, a rotation sensor for detecting a rotation angle of the output shaft, a current sensor for detecting a value of a current flowing through the motor, and a control section for controlling the motor. An outer peripheral edge has first and second valley parts, each of which has a bottom part and two inclined planes connected on both sides of the bottom part. The control section performs: a first valley part acquisition step of rotating the output shaft, acquiring a detection angle of the rotation sensor when a current value detected by the current sensor becomes higher than a threshold value in a contact position positioned at the first valley part passing through the inclined planes, and acquiring a first bottom position rotation angle in a state of the contact position positioned at the bottom part of the first valley part on the basis of the acquired detection angle; and a second valley part acquisition step of estimating a second bottom position rotation angle in a state of the contact position positioned at the bottom part of the second valley part on the basis of the angle information acquired at the first valley part acquisition step.SELECTED DRAWING: Figure 10

Description

[Technical Field]

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

[0002] An electric actuator that drives a switching mechanism such as a parking lock mechanism based on vehicle operation is known (see, for example, Patent Document 1). The switching mechanism driven by the electric actuator has a detent plate with a valley portion on its outer periphery and a positioning mechanism that holds the rotation angle of the detent plate by fitting a detent roller of a leaf spring member into the valley portion of the detent plate. The switching mechanism holds the rotation angle of the detent plate by positioning the detent roller at the bottom of the valley portion of the detent plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-204043 Summary of the Invention [Problem to be solved by the invention]

[0004] In a switching mechanism driven by an electric actuator, there is a self-learning method that detects the motor drive current in the electric actuator when a detent roller is reciprocated at the valley of a detent plate, and obtains the bottom angle (bottom position rotation angle) based on the rotation angle (learning point) when the motor drive current exceeds a threshold. Conventionally, when a detent plate has multiple valleys, self-learning is performed individually for each valley, which takes a long time.

[0005] In view of the above circumstances, one object of the present invention is to provide an electric actuator that can efficiently obtain the bottom position rotation angles of a plurality of valleys of a detent plate (first member). [Means for solving the problem]

[0006] One aspect of the electric actuator of the present invention is an electric actuator that rotates a plate-shaped first member having a surface and an outer circumferential edge about a central axis perpendicular to the surface, and changes a contact position of a second member having a contact portion that contacts the outer circumferential edge, and includes an output shaft extending about the central axis and connected to the first member, a motor, a reducer that reduces the rotation of the motor to rotate the output shaft about the central axis, a rotation sensor that detects the rotation angle of the output shaft, a current sensor that detects the value of a current flowing through the motor, and a control unit that controls the motor. The outer circumferential edge has a bottom and first and second valleys that have two inclined surfaces connected to either side of the bottom. The control unit performs a first valley acquisition process in which the output shaft is rotated, and the detection angle of the rotation sensor is acquired when the current value detected by the current sensor exceeds a threshold value when the contact position located at the first valley portion passes through the inclined surface, and based on the acquired detection angle, acquires a first bottom position rotation angle in a state where the contact position is located at the bottom of the first valley portion; and a second valley acquisition process in which, based on the angle information acquired in the first valley acquisition process, estimates a second bottom position rotation angle in a state where the contact position is located at the bottom of the second valley portion. [Effects of the Invention]

[0007] According to the above aspect of the present invention, an electric actuator is provided that can efficiently obtain the bottom position rotation angles of the plurality of valleys of the detent plate (first member). [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a view of a drive device including an electric actuator according to an embodiment, viewed from one side in the left-right direction of a vehicle. [Figure 2] FIG. 2 is a perspective view showing a parking mechanism according to an embodiment. [Figure 3]FIG. 3 is a cross-sectional view of an electric actuator according to an embodiment. [Figure 4] FIG. 4 is a front view of the reducer according to one embodiment. [Figure 5] FIG. 5 is a schematic diagram of a detent plate and a contact portion according to an embodiment, showing an example of an initial state in a first valley acquisition step of a self-learning step. [Figure 6] FIG. 6 is a schematic diagram of a detent plate and a contact portion according to one embodiment, illustrating a first obtaining step in a first valley obtaining step of a self-learning process. [Figure 7] FIG. 7 is a graph showing the relationship between the current value of the motor and the movement angle in the first acquisition step according to one embodiment. [Figure 8] FIG. 8 is a schematic diagram of a detent plate and a contact portion according to one embodiment, illustrating a second obtaining step in a first valley obtaining step of a self-learning process. [Figure 9] FIG. 9 is a graph showing the relationship between the current value of the motor and the movement angle in the second acquisition step according to one embodiment. [Figure 10] FIG. 10 is a graph showing the relationship between the motor current value and the movement angle in the first acquisition step and the second acquisition step in one embodiment, all in one graph. [Figure 11] FIG. 11 is a schematic diagram of a detent plate and a contact portion according to an embodiment, showing an example of an initial state in the second valley portion obtaining step of the self-learning step. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0010] FIG. 1 is a view of a drive device 1 equipped with an electric actuator 10 of this embodiment, viewed from one side in the left-right direction of a vehicle.

[0011] The drive device 1 of this embodiment is mounted on an electrically powered vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV), and is used as the drive source thereof.

[0012] In the following description, the vertical direction will be defined based on the positional relationship when the drive unit 1 is mounted on a vehicle positioned on a horizontal road surface.

[0013] In the drawings, an XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system as appropriate. In the XYZ coordinate system, the Z axis direction is a vertical direction with the +Z side being the upper side and the -Z side being the lower side. The X axis direction is a direction perpendicular to the Z axis direction and corresponds to the longitudinal direction of the vehicle on which the drive unit 1 is mounted. The +X side is one side in the longitudinal direction of the vehicle, and the -X side is the other side in the longitudinal direction of the vehicle. The Y axis direction is a direction perpendicular to the X axis direction and the Z axis direction and corresponds to the lateral direction of the vehicle. In this embodiment, the +Y side is one side in the lateral direction of the vehicle, and the -Y side is the other side in the lateral direction of the vehicle.

[0014] In this embodiment, the direction parallel to the Z-axis direction is called the "vertical direction Z," the direction parallel to the X-axis direction is called the "front-rear direction X," and the direction parallel to the Y-axis direction is called the "left-right direction Y." The positive side (+Z side) of the Z-axis direction is called the "upper side," and the negative side (-Z side) of the Z-axis direction is called the "lower side." The positive side (+X side) of the X-axis direction is called the "one side in the front-rear direction," and the negative side (-X side) of the X-axis direction is called the "other side in the front-rear direction." The positive side (+Y side) of the Y-axis direction is called the "one side in the left-right direction," and the negative side (-Y side) of the Y-axis direction is called the "other side in the left-right direction."

[0015] As shown in FIG. 1, the drive device 1 includes a parking mechanism 100, a housing 2, a drive motor 3, a reduction gear 4, a differential gear 5, and a parking lock gear 6.

[0016] The parking mechanism 100 includes a switching mechanism 70 and an electric actuator 10.

[0017] The switching mechanism 70 has a connecting shaft 80 that is connected to the electric actuator 10. The connecting shaft 80 extends in the front-rear direction X about a central axis J1.

[0018] The electric actuator 10 rotates the connecting shaft 80 around the central axis J1.

[0019] In the following description, the radial direction centered on the central axis J1 may be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J1, i.e., around the axis of the central axis J1, may be simply referred to as the "circumferential direction."

[0020] The housing 2 accommodates therein the drive motor 3, the reduction gear 4, the differential gear 5, and the switching mechanism 70. Although not shown, the housing 2 accommodates oil therein.

[0021] The drive motor 3 is connected to a reduction gear 4 .

[0022] The reduction gear 4 is connected to a differential gear 5 .

[0023] The differential 5 transmits the torque output from the drive motor 3 via the reduction gear 4 to the axles of the vehicle.

[0024] The park lock gear 6 is fixed to a gear provided in the reduction gear 4. The park lock gear 6 is connected to the axle of the vehicle via the reduction gear 4 and the differential gear 5. The park lock gear 6 has a plurality of teeth 6a.

[0025] The switching mechanism 70 is driven based on a shift operation of the vehicle by the electric actuator 10. The switching mechanism 70 switches the parking lock gear 6 between a locked state and an unlocked state.

[0026] The switching mechanism 70 locks the parking lock gear 6 when the shift position of the vehicle is in the parking position (P range).

[0027] The switching mechanism 70 unlocks the parking lock gear 6 when the vehicle's shift position is a non-parking position other than the parking position. The case where the vehicle's shift position is a non-parking position includes, for example, the case where the vehicle's shift position is the drive position (D range), the neutral position (N range), the reverse position (R range), or the like.

[0028] FIG. 2 is a perspective view showing the parking mechanism 100 of this embodiment.

[0029] The switching mechanism 70 has a connecting shaft 80, a movable portion 70a, a park lock arm 77, a base member 75, and a leaf spring member (second member) 76.

[0030] The connecting shaft 80 connects the electric actuator 10 and the movable part 70a, and transmits the power of the electric actuator 10 to the movable part 70a. An end 81 on one side in the front-rear direction (+X side) of the connecting shaft 80 is connected to the electric actuator 10.

[0031] The end portion 81 is provided with a plurality of spline grooves extending in the front-rear direction X along the circumferential direction. The connecting shaft 80 is connected to a detent plate (first member) 71 of the movable portion 70a. The connecting shaft 80 rotates integrally with the detent plate 71 around the central axis J1 by the power of the electric actuator 10.

[0032] The movable portion 70a moves in the left-right direction Y based on a shift operation of the vehicle. That is, in this embodiment, the left-right direction Y corresponds to the movement direction in which the movable portion 70a moves.

[0033] Moreover, the vertical direction Z corresponds to an intersecting direction that intersects with the movement direction in which the movable portion 70a moves, and the lower side corresponds to one side of the intersecting direction.

[0034] In this embodiment, the electric actuator 10 moves the movable part 70a via the connecting shaft 80. The position of the movable part 70a in the left-right direction Y is switched at least between a non-parking position and a parking position. That is, the electric actuator 10 moves the movable part 70a between the parking position and the non-parking position.

[0035] The non-parking position is the position of the movable part 70a in the left-right direction Y when the shift position of the vehicle is other than the parking position.

[0036] The parking position is the position of the movable part 70a in the left-right direction Y when the shift position of the vehicle is in the parking position. The parking position is a position to one side in the left-right direction (+Y side) of the non-parking position. The movable part 70a shown in FIG. 2 is located in the non-parking position.

[0037] The movable portion 70 a includes a detent plate 71 , a rod 72 , a conical member 73 , and a coil spring 74 .

[0038] The detent plate 71 is fixed to a connecting shaft 80. The connecting shaft 80 rotates the detent plate 71 around a central axis J1.

[0039] The detent plate 71 extends radially outward from the connecting shaft 80. In this embodiment, the detent plate 71 extends upward from the connecting shaft 80.

[0040] In this embodiment, the detent plate 71 is plate-shaped with its plate surface facing the front-rear direction X. The detent plate 71 is generally fan-shaped. The detent plate 71 has a surface 71f that is perpendicular to the central axis J1 and an outer peripheral edge 71a that is the edge on the outside in the radial direction.

[0041] The outer peripheral edge 71a is provided with a first valley portion 79A and a second valley portion 79B.

[0042] The first valley portion 79A is provided on one circumferential side of the detent plate 71. That is, the first valley portion 79A is provided on one side (one-side outer peripheral edge) of the outer peripheral edge 71a of the detent plate 71. The first valley portion 79A corresponds to the parking position.

[0043] The second valley portion 79B is provided on the other circumferential side of the detent plate 71. In other words, the second valley portion 79B is provided on the other side (other-side outer peripheral edge) of the outer peripheral edge 71a of the detent plate 71. The second valley portion 79B corresponds to the non-parking position.

[0044] The first valley portion 79A and the second valley portion 79B are recessed radially inward from the central axis J1 at the outer circumferential edge of the detent plate 71. The first valley portion 79A and the second valley portion 79B penetrate the detent plate 71 in the front-rear direction X.

[0045] The first valley portion 79A and the second valley portion 79B are arranged side by side along the circumferential direction of the central axis J1. The first valley portion 79A is located on the other side in the left-right direction (-Y side) of the second valley portion 79B.

[0046] By providing the first valley portion 79A and the second valley portion 79B on the detent plate 71, a peak portion 71c protruding radially outward is provided in the circumferential portion of the detent plate 71 between the first valley portion 79A and the second valley portion 79B.

[0047] In the following description, when there is no need to distinguish between the first valley portion 79A and the second valley portion 79B, they will simply be referred to as valley portions 79. In this embodiment, a case will be described in which the detent plate 71 has only the second valley portion 79B as the valley portion 79 corresponding to the non-parking position, but the detent plate 71 may have multiple valley portions 79 corresponding to the non-parking positions. In other words, three or more valley portions 79 may be provided on the outer peripheral edge 71a of the detent plate 71.

[0048] The rod 72 is disposed so as to be movable along the left-right direction Y. The rod 72 has a connection portion 72a and a rod main body 72b.

[0049] The connecting portion 72a is rod-shaped and extends in the front-rear direction X. An end portion on one side (+X side) in the front-rear direction of the connecting portion 72a penetrates the detent plate 71 in the front-rear direction X and is fixed to the detent plate 71. In this way, the rod 72 is connected to the connecting shaft 80 via the detent plate 71.

[0050] The rod body 72b has a bar shape extending in the left-right direction Y. In this embodiment, the rod body 72b extends from an end of the connecting portion 72a on the other side in the front-rear direction (-X side) to one side in the left-right direction (+Y side).

[0051] The rod main body 72b has a protrusion 72c at a portion closer to the connecting portion 72a. A cylindrical member 72d extending in the left-right direction Y is fitted and fixed to one end of the rod main body 72b in the left-right direction.

[0052] The conical member 73 has a conical shape through which the rod main body 72b passes. The conical member 73 extends in the left-right direction Y. The outer peripheral surface of the conical member 73, on one side in the left-right direction (+Y side), is a tapered surface 73a whose outer diameter decreases toward one side in the left-right direction. The conical member 73 is movable in the left-right direction Y relative to the rod main body 72b.

[0053] The coil spring 74 extends in the left-right direction Y. The coil spring 74 is disposed between the conical member 73 and the protrusion 72c in the left-right direction Y. The rod main body 72b is passed through the coil spring 74.

[0054] An end portion of the coil spring 74 on the other left-right side (-Y side) contacts the protrusion 72c. An end portion of the coil spring 74 on one left-right side (+Y side) contacts the surface of the conical member 73 on the other left-right side. The coil spring 74 expands and contracts as the conical member 73 moves relative to the rod main body 72b in the left-right direction Y, and applies an elastic force in the left-right direction Y to the conical member 73.

[0055] The park lock arm 77 is located on the other side (-X side) in the front-rear direction of the movable part 70a. The park lock arm 77 is rotatably supported by a support shaft 78 that is centered on a rotation axis J3 that extends in the left-right direction Y. The park lock arm 77 has a park lock arm main body 77a and a meshing part 77b.

[0056] The park lock arm main body 77a extends to one side (+X side) in the front-rear direction from the support shaft 78. An end 77c on one side in the front-rear direction of the park lock arm main body 77a contacts the movable part 70a from above.

[0057] The meshing portion 77b protrudes upward from the parking lock arm main body 77a. A coil spring (not shown) is attached to the support shaft 78. The coil spring (not shown) applies an elastic force to the parking lock arm 77 in a clockwise direction around the rotation axis J3 when viewed from the other side in the left-right direction (-Y side).

[0058] The park lock arm 77 moves in accordance with the movement of the movable part 70a. More specifically, the park lock arm 77 rotates about the rotation axis J3 in accordance with the movement of the rod 72 and the conical member 73 in the left-right direction Y.

[0059] When the detent plate 71 rotates from the non-parking position to the parking position in conjunction with the rotation of the connecting shaft 80, the rod 72 and the conical member 73 move to one side in the left-right direction (+Y side).

[0060] The outer diameter of the tapered surface 73a of the conical member 73 increases from one side in the left-right direction (+Y side) to the other side in the left-right direction (-Y side). Therefore, when the conical member 73 moves to one side in the left-right direction, the end 77c of the parking lock arm 77 is lifted upward by the tapered surface 73a, and the parking lock arm 77 rotates counterclockwise around the rotation axis J3 as viewed from the other side in the left-right direction (-Y side). As a result, the meshing portion 77b approaches the parking lock gear 6 and meshes with the teeth 6a of the parking lock gear 6.

[0061] When the park lock gear 6 and the park lock arm 77 mesh with each other, the conical member 73 is also positioned in the parking position, and the entire movable portion 70a is positioned in the parking position.

[0062] That is, when the movable portion 70a is located in the parking position, the parking lock arm 77 meshes with the parking lock gear 6 connected to the axle.

[0063] In the parking position, the conical member 73 is sandwiched in contact with a support portion 75b (described later) of the base member 75 and a parking lock arm 77. When the parking lock arm 77 meshes with the parking lock gear 6, the parking lock gear 6 is brought into a locked state.

[0064] When the park lock arm 77 approaches the park lock gear 6, the meshing portion 77b may come into contact with the teeth 6a depending on the position of the teeth 6a of the park lock gear 6. In this case, the park lock arm 77 may not be able to move to a position where the meshing portion 77b meshes with the teeth 6a.

[0065] Even in such a case, in this embodiment, the conical member 73 can move in the left-right direction Y relative to the rod 72, so that the rod 72 can move to the parking position while allowing the conical member 73 to be positioned on the other left-right side (-Y side) of the parking position.

[0066] Therefore, it is possible to prevent the rotation of the connecting shaft 80 from being hindered, and it is possible to prevent a load from being applied to the electric actuator 10 that rotates the connecting shaft 80.

[0067] Furthermore, when the rod 72 is located in the parking position and the conical member 73 is located on the other side in the left-right direction (-Y side) from the parking position, the coil spring 74 is in a compressed and deformed state.

[0068] Therefore, an elastic force toward one side in the left-right direction (toward the +Y side) is applied by the coil spring 74 to the conical member 73. As a result, a rotational moment is applied from the coil spring 74 to the parking lock arm 77 via the conical member 73 in a direction that rotates counterclockwise about the rotation axis J3 as viewed from the other side in the left-right direction (toward the -Y side).

[0069] Therefore, when the parking lock gear 6 rotates and the toothed portions 6a are displaced, the parking lock arm 77 rotates and the meshing portions 77b mesh with the toothed portions 6a.

[0070] When the detent plate 71 rotates from the parking position to the non-parking position in conjunction with the rotation of the connecting shaft 80, the rod 72 and the conical member 73 move to the other side in the left-right direction (-Y side).

[0071] When the conical member 73 moves to the other side in the left-right direction, the end 77c of the parking lock arm 77, which was lifted by the conical member 73, moves downward due to its own weight and the elastic force of a coil spring (not shown), and the parking lock arm 77 rotates counterclockwise around the rotation axis J3 when viewed from one side in the left-right direction (+Y side).

[0072] As a result, the meshing portion 77b of the parking lock arm 77 moves away from the parking lock gear 6 and comes out from between the tooth portions 6a. In FIG.

[0073] When the park lock arm 77 disengages from the park lock gear 6, the conical member 73 also assumes a position in the non-parking position, and the entire movable portion 70a assumes a position in the non-parking position.

[0074] That is, when the movable part 70a is located in the non-parking position, the parking lock arm 77 disengages from the parking lock gear 6. In the non-parking position, the conical member 73 is located on the other left-right side (-Y side) of the parking lock arm 77. When the parking lock arm 77 disengages from the parking lock gear 6, the parking lock gear 6 is in an unlocked state.

[0075] The base member 75 supports the movable portion 70a so that it can move in the left-right direction Y. In this embodiment, the base member 75 supports the movable portion 70a from below. The base member 75 is fixed to the inner surface of the housing 2. The base member 75 has a base plate 75a, a support portion 75b, and a leaf spring fixing portion 75c.

[0076] In this embodiment, the base plate 75a is a plate-like plate whose surface faces the vertical direction Z.

[0077] The support portion 75b protrudes upward from the base plate 75a. The support portion 75b is a portion that comes into contact with the movable portion 70a and supports the movable portion 70a. In this embodiment, the support portion 75b comes into contact with the conical member 73 of the movable portion 70a from below and supports the movable portion 70a from below.

[0078] The surface of the support portion 75b facing the movable portion 70a is an arc-shaped curved surface that is concave on the side opposite to the movable portion 70a in a plan view from the left-right direction Y. Therefore, the support portion 75b can stably support the conical member 73 having the tapered surface 73a.

[0079] The plate spring fixing portion 75c protrudes upward from the base plate 75a. The plate spring fixing portion 75c has, for example, a rectangular parallelepiped shape. The plate spring fixing portion 75c is located on one side (+X side) in the front-rear direction relative to the support portion 75b.

[0080] The leaf spring component 76 is fixed to a leaf spring fixing portion 75c of the base component 75. In this embodiment, the leaf spring component 76 is fixed to an end portion on the other side in the left-right direction (-Y side) of the upper surface of the leaf spring fixing portion 75c. The leaf spring component 76 has a leaf spring main body portion 76a and a contact portion 76b.

[0081] The leaf spring main body 76a is plate-shaped with its plate surface facing the vertical direction Z. The leaf spring main body 76a extends from the leaf spring fixing portion 75c to the other side in the left-right direction (-Y side). The leaf spring main body 76a extends to the upper side of the detent plate 71. The leaf spring main body 76a has a slit 76c at its end on the other side in the left-right direction.

[0082] The slit 76c penetrates the leaf spring main body 76a in the vertical direction Z. The slit 76c extends in the left-right direction Y. The slit 76c extends to the other left-right end of the leaf spring main body 76a, dividing the other left-right end of the leaf spring main body 76a into two.

[0083] The contact portion 76b is provided at the end of the leaf spring main body 76a on the other side in the left-right direction (-Y side). In this embodiment, the contact portion 76b is a roller attached to the leaf spring main body 76a to be rotatable around an axis extending in the front-rear direction X.

[0084] The contact portion 76b is provided between the tip ends of the leaf spring main body 76a, which is bifurcated by the slit 76c.

[0085] The contact portion 76b is pressed against the outer peripheral edge 71a of the detent plate 71 by the elastic force generated in the leaf spring member 76. Here, the position of the outer peripheral edge 71a of the detent plate 71 that comes into contact with the contact portion 76b is referred to as a contact position P.

[0086] A contact portion 76b of the detent plate 71 is pressed against the outer peripheral edge 71a at the contact position P.

[0087] When the movable portion 70a is located in the parking position, the contact position P is located within the first valley portion 79A. As a result, the contact portion 76b is hooked in the left-right direction Y on the inner surface of the first valley portion 79A, maintaining the detent plate 71 and the rod 72 in the parking position.

[0088] When the movable portion 70a is located in the non-parking position, the contact position P is located within the second valley portion 79B. As a result, the contact portion 76b is hooked in the left-right direction Y against the inner surface of the second valley portion 79B, maintaining the detent plate 71 and the rod 72 in the non-parking position.

[0089] When the detent plate 71 rotates around the central axis J1, the contact position P moves relatively from the inside of one of the valley portions 79 to the other valley portion 79, climbing over the peak portion 71c.

[0090] When the contact position P overcomes the peaks 71c, the leaf spring member 76 receives a force from the peaks 71c through the contact portion 76b in the radial outward direction of the central axis J1, causing the leaf spring member 76 to elastically deform. That is, in this embodiment, the leaf spring member 76 is an elastic member that is pushed upward by the peaks 71c of the detent plate 71 and elastically deforms when the movable portion 70a moves between the non-parking position and the parking position.

[0091] As described above, the flat spring member 76 in this embodiment is an elastic member having a contact portion 76b that comes into contact with one of the plurality of valley portions 79 due to an elastic force generated as the detent plate 71 rotates.

[0092] In this embodiment, when the contact portion 76b moves between the first valley portion 79A and the second valley portion 79B, the contact portion 76b, which is a roller, moves while rolling on the upper end surface of the detent plate 71.

[0093] The contact portion 76b is a detent roller that moves along the outer peripheral edge 71a of the detent plate 71 and maintains the detent plate 71 in the parking position or the non-parking position.

[0094] The electric actuator 10 drives the switching mechanism 70 based on a shift operation of the vehicle. In this embodiment, the electric actuator 10 drives the switching mechanism 70 by moving the movable part 70a in the left-right direction Y via the connecting shaft 80, and switches the parking lock gear 6 between a locked state and an unlocked state.

[0095] More specifically, the electric actuator 10 rotates the detent plate 71 around a central axis J1 perpendicular to the surface 71f, thereby changing the contact position P of the leaf spring member 76 having a contact portion 76b that contacts the outer peripheral edge 71a.

[0096] FIG. 3 is a cross-sectional view of the electric actuator 10.

[0097] The electric actuator 10 includes a case 10A, a motor 20, a reducer 30, an output shaft 46, a first bearing 51, a second bearing 52, a third bearing 53, a control unit 90, a rotation sensor 95, a sensor magnet 45, and a current sensor 96.

[0098] The first bearing 51, the second bearing 52, and the third bearing 53 are, for example, ball bearings.

[0099] The case 10A accommodates therein each part of the electric actuator 10, including the motor 20, the reducer 30, and the output shaft 46. The case 10A has a case main body 11 and a cover member 12.

[0100] The case body 11 has a cylindrical shape centered on the central axis J1. The case body 11 has an opening 11h that opens to one axial side. The case body 11 has a first housing portion 11a and a second housing portion 11b.

[0101] The first housing portion 11a is a portion on the other axial side of the case body 11. The first housing portion 11a has a bottom plate portion 11c located on the other axial side, and a peripheral wall portion 11d extending from the radial outer edge of the bottom plate portion 11c to one axial side.

[0102] The bottom plate portion 11c is provided with a hole portion 11e that passes through the bottom plate portion 11c in the axial direction. The hole portion 11e is a substantially circular hole that is centered on the central axis J1.

[0103] A portion on one axial side of the hole portion 11e constitutes a first bearing holding portion 11f that holds the first bearing 51. The first bearing 51 is held by the first bearing holding portion 11f.

[0104] The second housing portion 11b is a portion on one axial side of the case body 11. The second housing portion 11b is axially connected to the first housing portion 11a. The second housing portion 11b is cylindrical and opens to one axial side. The inner peripheral surface of the second housing portion 11b is provided with a step having a step surface 11g facing one axial side.

[0105] The lid member 12 is fixed to one axial end of the case body 11. The lid member 12 closes the opening 11h of the case body 11 from one axial side.

[0106] The lid member 12 has a lid main body portion 12a that closes the opening 11h from one axial side, and a second bearing holding portion 12b that protrudes from the lid main body portion 12a to the other axial side.

[0107] The second bearing holder 12b is cylindrical and has its center on the central axis J1 and is open on the other axial side. The second bearing 52 is held on the inner peripheral surface of the second bearing holder 12b.

[0108] The motor 20 is, for example, a three-phase brushless DC motor. The motor 20 includes a rotor 21 and a stator 22.

[0109] The rotor 21 is rotatable about a central axis J1 and includes a motor shaft 23, a rotor core 24a, and a magnet 24b.

[0110] The motor shaft 23 is rotatable about a central axis J1. The motor shaft 23 has a generally cylindrical shape that extends axially around the central axis J1. The motor shaft 23 is a hollow shaft.

[0111] The motor shaft 23 is open on both axial sides and extends across the interior of the first housing portion 11a and the interior of the second housing portion 11b. The motor shaft 23 has a main body portion 23a and an eccentric shaft portion 23b.

[0112] The main body portion 23a is a portion on one axial side of the motor shaft 23. A rotor core 24a is fixed to the outer peripheral surface of the main body portion 23a. One axial end of the main body portion 23a is disposed inside the second housing portion 11b. The rest of the main body portion 23a other than the one axial end is disposed inside the first housing portion 11a.

[0113] The eccentric shaft portion 23b is a portion on the other axial side of the motor shaft 23. The eccentric shaft portion 23b is axially connected to the main body portion 23a. The eccentric shaft portion 23b is disposed inside the first accommodating portion 11a. The eccentric shaft portion 23b is disposed on the other axial side of the rotor core 24a.

[0114] In plan view from the axial direction, the inner peripheral surface of the eccentric shaft portion 23b has a circular shape centered on the central axis J1. In addition, in plan view from the axial direction, the outer peripheral surface of the eccentric shaft portion 23b has a circular shape centered on an eccentric axis J2 that is eccentric with respect to the central axis J1.

[0115] The eccentric axis J2 is an imaginary axis parallel to the central axis J1. An inner ring of a third bearing 53 is fitted onto and fixed to the outer peripheral surface of the eccentric shaft portion 23b. This fixes the third bearing 53 to the motor shaft 23. The eccentric shaft portion 23b rotates eccentrically as the rotor 21 rotates about the central axis J1. In other words, the motor 20 has the eccentric shaft portion 23b that rotates eccentrically.

[0116] The rotor core 24a has an annular shape centered on the central axis J1. The rotor core 24a is disposed inside the first housing portion 11a. The rotor core 24a is fixed to the outer peripheral surface of the main body portion 23a.

[0117] The magnet 24b is fixed to the outer peripheral surface of the rotor core 24a. In this embodiment, a plurality of magnets 24b are arranged at intervals in the circumferential direction.

[0118] The stator 22 is disposed radially opposite the rotor 21. The stator 22 is disposed radially outside the rotor 21 with a gap between the rotor 21 and the stator 22. The stator 22 is disposed inside the first housing portion 11a.

[0119] The stator 22 has an annular stator core 22a that surrounds the rotor core 24a from the radial outside, an insulator 22b attached to the stator core 22a, and a plurality of coil portions 22c attached to the stator core 22a via the insulator 22b.

[0120] The outer peripheral surface of the stator core 22a is fixed to the inner peripheral surface of the peripheral wall portion 11d, thereby fixing the stator 22 to the case 10A.

[0121] The reducer 30 is disposed inside the first housing portion 11a. The reducer 30 is disposed on the other axial side of the rotor core 24a and the stator 22. The reducer 30 is coupled to the motor shaft 23 and the output shaft 46.

[0122] The reducer 30 reduces the rotation of the motor 20 and transmits it to the output shaft 46, causing the output shaft 46 to rotate around the central axis J1. The reducer 30 has an external gear 31, an internal gear 32, a flange portion 42, and multiple protrusions 43.

[0123] The external gear 31 has an annular shape centered on the eccentric axis J2. The external gear 31 is fitted into the outer ring of the third bearing 53. The external gear 31 is connected to the eccentric shaft portion 23b of the motor shaft 23 via the third bearing 53. This allows the rotation of the motor shaft 23 to be transmitted to the external gear 31. The external gear 31 is rotatable relative to the motor shaft 23 around the eccentric axis J2.

[0124] FIG. 4 is a front view of the reducer 30. As shown in FIG.

[0125] The reducer 30 of this embodiment is an internal reducer. In this specification, the term "internal reducer" refers to a reducer that has an external gear 31 and an internal gear 32, and that reduces rotation when the meshing point between the external gear 31 and the internal gear 32 moves circumferentially.

[0126] The external gear 31 has a plurality of through-hole portions 31b and an external gear portion 31c. In this embodiment, each of the plurality of through-hole portions 31b is a hole that passes through the external gear 31 in the axial direction.

[0127] Each of the plurality of through-hole portions 31b has a circular shape when viewed from above in the axial direction. The plurality of through-hole portions 31b are arranged around the central axis J1. In this embodiment, eight through-hole portions 31b are provided.

[0128] The external gear portion 31c is provided along the outer circumferential surface of the external gear 31. The external gear portion 31c is configured by a plurality of external teeth portions 31d arranged along the outer circumferential surface of the external gear 31.

[0129] In this embodiment, the external gear portion 31c is configured by 79 externally toothed portions 31d. The number of teeth N1 of the external gear portion 31c may be 78 or less, or may be 80 or more. The tooth profile of the external gear 31 is an involute tooth profile.

[0130] 4 is a virtual line connecting the eccentric axis J2 and the pitch point 31f of the external tooth portion 31d in a plan view from the axial direction. The first virtual line L1 is a straight line perpendicular to the eccentric axis J2.

[0131] As shown in FIG. 4, the pitch point 31f is a portion of the tooth surface of the external tooth portion 31d that comes into contact with an internal tooth portion 32b of the internal gear 32, which will be described later.

[0132] The first tangent line L3 is a tangent line that is tangent to the tooth flank of the external tooth portion 31d and is tangent to the pitch point 31f. The angle between the first virtual line L1 and the first tangent line L3 is the pressure angle α1 of the external tooth portion 31d.

[0133] The pressure angle α1 is the pressure angle of the tooth profile of the external gear 31. In this embodiment, the pressure angle α1 of each of the plurality of external tooth portions 31d is equal to or greater than 22° and equal to or less than 25.5°.

[0134] The internal gear 32 is disposed radially outward of the external gear 31. The internal gear 32 surrounds the external gear 31 from the radially outward side. The internal gear 32 is annular and has its center on the central axis J1.

[0135] As shown in Fig. 3, the outer peripheral surface of the internal gear 32 is fixed to the inner peripheral surface of the peripheral wall portion 11d. That is, the internal gear 32 is fixed to the case 10A. As shown in Fig. 4, the internal gear 32 has an internal gear portion 32a.

[0136] The internal gear portion 32a is provided along the inner peripheral surface of the internal gear 32. The internal gear portion 32a is configured by a plurality of internal teeth portions 32b arranged along the inner peripheral surface of the internal gear 32.

[0137] In this embodiment, the internal gear portion 32a is configured by 80 internal gear portions 32b. The number of teeth N2 of the internal gear portion 32a may be 79 or less, or 81 or more.

[0138] A portion of the internal gear portion 32a meshes with a portion of the external gear portion 31c. That is, the internal gear 32 meshes with at least a portion of the external gear 31. In this embodiment, the teeth of the internal gear 32 are each an involute tooth profile.

[0139] 4 is a virtual line connecting the central axis J1 and the pitch point 32d of the internal tooth portion 32b in a plan view from the axial direction. The second virtual line L2 is a straight line perpendicular to the central axis J1.

[0140] As shown in FIG. 4, the pitch point 32d is a portion of the tooth surface of the internal tooth portion 32b that comes into contact with the pitch point 31f of the external tooth portion 31d.

[0141] The second tangent line L4 is a tangent line that is tangent to the pitch point 32d among the tangent lines that are tangent to the tooth surface of the internal tooth portion 32b. The angle between the second virtual line L2 and the second tangent line L4 is the pressure angle α2 of the internal tooth portion 32b.

[0142] The pressure angle α2 is the pressure angle of the tooth profile of the internal gear 32. In this embodiment, the pressure angle α2 of each of the multiple internal tooth portions 32b is equal to or greater than 22° and equal to or less than 25.5°.

[0143] The pressure angle α1 and the pressure angle α2 may be the same angle as each other, or may be different angles from each other. In this embodiment, the pressure angle α1 and the pressure angle α2 are the same angle as each other.

[0144] 3, the flange portion 42 is disposed on the other axial side of the external gear 31. The flange portion 42 is disposed axially apart from the external gear 31. The flange portion 42 has an annular shape centered on the central axis J1.

[0145] The flange portion 42 is fixed to a portion of the output shaft 46 on the other axial side of the motor shaft 23. The flange portion 42 is provided with a plurality of protrusions 43.

[0146] In this embodiment, each of the multiple protrusions 43 has a cylindrical shape and protrudes axially from the flange portion 42. In this embodiment, the multiple protrusions 43 and the flange portion 42 are part of the same single member.

[0147] 4, the outer diameter of each of the plurality of protrusions 43 is smaller than the inner diameter of each of the plurality of through-hole portions 31b. The plurality of protrusions 43 are arranged around the central axis J1.

[0148] In this embodiment, eight protrusions 43 are provided. As shown in Fig. 3, each of the plurality of protrusions 43 is inserted into a corresponding one of the plurality of through-holes 31b from the other axial side. As shown in Fig. 4, each of the protrusions 43 supports the external gear 31 via the inner surface of the through-hole 31b so that the external gear 31 can swing about the central axis J1.

[0149] The output shaft 46 outputs the driving force of the electric actuator 10 to the switching mechanism 70 via the connecting shaft 80. As shown in FIG. 3 , the output shaft 46 extends in the axial direction around a central axis J1. The output shaft 46 is rotatable around the central axis J1. The rotation of the motor shaft 23 is transmitted to the output shaft 46 via the reducer 30.

[0150] The output shaft 46 passes axially through the motor shaft 23. The output shaft 46 protrudes from the motor shaft 23 on both axial sides. That is, at least a portion of the output shaft 46 is located inside the motor shaft 23. The output shaft 46 and the flange portion 42 may be part of the same single member.

[0151] The output shaft 46 has an output shaft body 41 and a mounting member 44 fixed to the outer circumferential surface of the output shaft body 41 .

[0152] The output shaft body 41 extends in the axial direction. The output shaft body 41 is supported rotatably about the central axis J1 by a first bearing 51 and a second bearing 52. The output shaft body 41 has a connecting portion 41a and an extending portion 41b.

[0153] The connecting portion 41a is a portion on the other axial side of the output shaft body 41. The connecting portion 41a is cylindrical and extends axially around the central axis J1. The connecting portion 41a opens on the other axial side.

[0154] The other axial end of the connecting portion 41a is inserted into the hole 11e. The one axial end of the connecting portion 41a is inserted into the eccentric shaft portion 23b. The connecting portion 41a is supported by a first bearing 51 so as to be rotatable around the central axis J1.

[0155] An end portion 81 of the connecting shaft 80 can be inserted into the connecting portion 41a from the other axial side. A plurality of spline grooves provided on the outer peripheral surface of the end portion 81 of the connecting shaft 80 are fitted into a plurality of spline grooves provided on the inner peripheral surface of the connecting portion 41a, thereby connecting the connecting portion 41a and the connecting shaft 80 to each other.

[0156] In addition, the output shaft 46 is connected to a detent plate 71 (see FIG. 2) via a connecting shaft 80. The rotation of the output shaft 46 is transmitted to the detent plate 71 via the connecting shaft 80. In this way, the electric actuator 10 drives the switching mechanism 70.

[0157] The extension portion 41b is a portion on one axial side of the output shaft main body 41. The extension portion 41b is cylindrical and extends axially around the central axis J1. The extension portion 41b is axially connected to the connecting portion 41a. The extension portion 41b passes through the interior of the motor shaft 23 in the axial direction.

[0158] A portion of the extending portion 41b on one axial side protrudes further axially toward that side than the motor shaft 23. An end portion of the extending portion 41b on one axial side is supported by a second bearing 52 so as to be rotatable about the central axis J1.

[0159] As described above, the connecting portion 41a is supported rotatably about the central axis J1 by the first bearing 51. As a result, the output shaft 46 is supported by the case 10A via the first bearing 51 and the second bearing 52.

[0160] In this embodiment, the outer diameter of the extension 41b is slightly smaller than the inner diameter of the main body 23a of the motor shaft 23. The extension 41b is loosely fitted inside the main body 23a. The radial gap between the extension 41b and the main body 23a is small enough to allow the extension 41b to support the motor shaft 23 rotatably about the central axis J1.

[0161] Therefore, motor shaft 23 is supported by case 10A via output shaft 46, first bearing 51, and second bearing 52. This makes it possible to prevent motor shaft 23 from moving in the radial direction relative to case 10A.

[0162] The mounting member 44 is fixed to a portion of the outer circumferential surface of the extending portion 41b that is on one axial side of the motor shaft 23. The mounting member 44 has a fixed cylindrical portion 44a and an annular portion 44b.

[0163] The fixed cylinder portion 44a is cylindrical and has a center on the central axis J1 and is open on both axial sides. The fixed cylinder portion 44a is fixed to the outer peripheral surface of the extension portion 41b.

[0164] The annular portion 44b has a generally annular plate shape that extends radially outward from the other axial end of the fixed cylindrical portion 44a.

[0165] The sensor magnet 45 is annular and surrounds the central axis J1. The sensor magnet 45 is fixed to the outer peripheral surface of the fixed cylindrical portion 44a. The radially outer edge of the sensor magnet 45 is located radially outward of the annular portion 44b and faces the rotation sensor 95 in the axial direction.

[0166] A washer 61 is arranged axially between the other axial end of the main body 23a of the motor shaft 23 and one axial end of the connecting portion 41a of the output shaft 46.

[0167] The washer 61 has an annular plate shape that surrounds the extension portion 41b. The plate surface of the washer 61 faces the axial direction. The washer 61 contacts both the main body portion 23a and the connecting portion 41a in the axial direction. In addition, a washer 62 is disposed between one axial end of the main body portion 23a and the annular portion 44b.

[0168] The washer 62 is an annular plate that surrounds the extension portion 41b. The plate surface of the washer 62 faces the axial direction. The washer 62 contacts both the main body portion 23a and the annular portion 44b in the axial direction. The washers 61 and 62 are, for example, slip washers.

[0169] The control unit 90 controls the motor 20. The control unit 90 is disposed on one axial side of the stator 22. The control unit 90 has a substrate 91 and a plurality of elements (not shown) mounted on the substrate 91.

[0170] The substrate 91 is fixed to the stepped surface 11g of the case 10A. The substrate 91 is in the form of a plate that extends in the radial direction. An inverter circuit that supplies power to the motor 20 is provided on the substrate 91 and the elements mounted on the substrate 91.

[0171] Although not shown in the figure, the substrate 91 is electrically connected to each of the plurality of coil portions 22c of the stator 22. The control unit 90 controls the power supplied to each of the plurality of coil portions 22c. The substrate 91 is provided with a through hole 91a.

[0172] The through hole 91a has a circular shape centered on the central axis J1 in a plan view from the axial direction. The extension portion 41b of the output shaft 46 is passed through the through hole 91a in the axial direction.

[0173] A rotation sensor 95 and a current sensor 96 are mounted on the substrate 91. That is, the control unit 90 is connected to the rotation sensor 95 and the current sensor 96.

[0174] The control unit 90 controls the motor 20 based on the rotation angle detected by the rotation sensor 95 and the current value detected by the current sensor 96 .

[0175] The rotation sensor 95 is fixed to the peripheral edge of the through-hole 91a in a surface facing one axial side of the control unit 90. The rotation sensor 95 faces the radial outer edge of the sensor magnet 45 fixed to the output shaft 46 in the axial direction.

[0176] In this embodiment, the rotation sensor 95 is a magnetic sensor. The rotation sensor 95 is, for example, a Hall element such as a Hall IC. The rotation sensor 95 detects the rotation of the sensor magnet 45 by detecting the magnetic field of the sensor magnet 45. In this way, the rotation sensor 95 detects the rotation angle of the output shaft 46.

[0177] The rotation sensor 95 may detect the rotation angle of the motor shaft 23. In this case, the rotation sensor 95 calculates the rotation angle of the connecting shaft 80 from the detected rotation angle of the motor shaft 23 and the reduction ratio of the reducer 30. In other words, the rotation sensor 95 may indirectly detect the rotation angle of the output shaft 46.

[0178] The current sensor 96 detects the value of a current flowing through the motor 20. The current sensor 96 is, for example, a current sensor that uses a shunt resistor. The value of the current flowing through the motor 20 is the value of a current supplied to the stator 22 by the control unit 90.

[0179] The value of the current flowing through the motor 20 correlates with the torque output by the rotor 21 of the motor 20. By monitoring the value of the current flowing through the stator 22, the control unit 90 can monitor the reaction force acting on the rotor 21 when the rotor 21 rotates.

[0180] It is preferable that the control unit 90 removes noise by applying a low-pass filter to the detection value detected by the current sensor 96. The detection value of the current sensor 96 may be superimposed with noise caused by the surface roughness of the gears or magnetic pulsation between the rotor 21 and the stator 22. By including a low-pass filter in the control unit 90, it is possible to prevent the control unit 90 from erroneously detecting the current value due to such noise.

[0181] When power is supplied from the control unit 90 to the motor 20 and the motor shaft 23 rotates around the central axis J1, the eccentric shaft portion 23b revolves in the circumferential direction around the central axis J1. The revolution of the eccentric shaft portion 23b is transmitted to the external gear 31 via the third bearing 53.

[0182] The external gear 31 revolves around the central axis J1 while changing the position at which the inner peripheral surface of the through hole portion 31b contacts the outer peripheral surface of the protrusion 43. When the external gear 31 revolves around the central axis J1, the position at which the external gear portion 31c of the external gear 31 meshes with the internal gear portion 32a of the internal gear 32 changes in the circumferential direction. As a result, the driving force of the motor shaft 23 is transmitted to the internal gear 32 via the external gear 31.

[0183] As described above, the internal gear 32 is fixed to the case 10A. Therefore, the external gear 31 rotates around the eccentric axis J2 due to the reaction force of the driving force transmitted to the internal gear 32. At this time, the rotation of the external gear 31 is decelerated relative to the rotation of the motor shaft 23.

[0184] In the configuration of the reducer 30 of this embodiment, the reduction ratio of the rotation of the output shaft 46 to the rotation of the motor shaft 23, i.e., the reduction ratio R of the reducer 30, is expressed as R = (N2 - N1) / N1. As described above, in this embodiment, the number of teeth N1 of the external gear portion 31c is 79, and the number of teeth N2 of the internal gear portion 32a is 80.

[0185] Therefore, the reduction ratio R in this embodiment is 1 / 79. According to the reducer 30 of this embodiment, the reduction ratio R of the rotation of the output shaft 46 to the rotation of the motor shaft 23 can be made relatively large, and the rotation torque of the output shaft 46 to the rotation torque of the motor shaft 23 can be made large.

[0186] The rotation of the external gear 31 about the eccentric axis J2 is transmitted to the flange portion 42 via the inner surface of the through-hole portion 31b and the protrusion 43, causing the flange portion 42 to rotate about the central axis J1.

[0187] As described above, the output shaft 46 is fixed to the flange portion 42. Therefore, the output shaft 46 rotates around the central axis J1 together with the flange portion 42. That is, the flange portion 42 transmits the rotation of the external gear 31 to the output shaft 46. In this way, the rotation of the motor shaft 23 is transmitted to the output shaft 46 via the reducer 30.

[0188] 4, as the pressure angle α1 of the external tooth portion 31d increases, the tooth flanks of the external tooth portion 31d face radially outward. On the other hand, as the pressure angle α2 of the internal tooth portion 32b increases, the tooth flanks of the internal tooth portion 32b face radially inward.

[0189] Therefore, as the pressure angle α1 and the pressure angle α2 increase, the circumferential component of the force applied from the external tooth portion 31d to the internal tooth portion 32b decreases. This reduces the circumferential component of the reaction force applied from the internal tooth portion 32b to the external tooth portion 31d, thereby reducing the rotational torque with which the external gear 31 rotates about the eccentric axis J2. In other words, as the pressure angle α1 and the pressure angle α2 increase, the efficiency of drive transmission between the external gear 31 and the internal gear 32 decreases.

[0190] According to this embodiment, as described above, the pressure angle α1 of the plurality of external tooth portions 31d and the pressure angle α2 of the plurality of internal tooth portions 32b are 25.5° or less. Therefore, it is possible to prevent the drive transmission efficiency between the external gear 31 and the internal gear 32 from decreasing too much, and it is also possible to prevent the drive efficiency of the electric actuator 10 from decreasing too much.

[0191] In this embodiment, during reverse driving of the electric actuator 10, a rotational torque is applied to the output shaft 46 to rotate the output shaft 46 about the central axis J1, and the rotation of the output shaft 46 is transmitted to the motor shaft 23 via the reducer 30 to drive the motor shaft 23 about the central axis J1. In this embodiment, during reverse driving, the supply of power from the control unit 90 to the stator 22 is stopped.

[0192] Here, if the pressure angle α1 and the pressure angle α2 each become larger than 22°, the reverse drive torque of the electric actuator 10 becomes too large, making it impossible to reverse drive the electric actuator 10. The reverse drive torque is the rotational torque applied to the output shaft 46, and is the rotational torque required to reverse drive the electric actuator 10.

[0193] The tooth profiles of the external gear 31 and the internal gear 32 are involute tooth profiles. The pressure angle α1 of the tooth profile of the external gear 31 and the pressure angle α2 of the tooth profile of the internal gear 32 are 22° or more. This makes it possible to prevent the electric actuator 10 from being reverse-driven.

[0194] Furthermore, even if the number of teeth of the external gear portion 31c and the number of teeth of the internal gear portion 32a are different from those in this embodiment, by setting the pressure angles α1 and α2 to 22° or more, reverse driving of the electric actuator 10 can be similarly prevented.

[0195] Regardless of the number of teeth of the external gear portion 31c and the internal gear portion 32a, when the pressure angles α1 and α2 are 22° or greater, the component of the force applied to the external gear 31 that presses the external gear 31 against the motor shaft 23 becomes greater than the component that moves the external gear 31 in a direction that disengages the external gear 31d and the internal gear portion 32b, causing the external gear 31 to revolve around the central axis J1, thereby preventing the electric actuator 10 from driving in reverse.

[0196] When the pressure angles α1 and α2 are 22° or greater, the more rotational torque is applied to reversely drive the output shaft 46, the more strongly the external tooth portion 31d and the internal tooth portion 32b mesh with each other due to the reaction force of the force pressing the external gear 31 against the motor shaft 23, and therefore the reverse drive torque becomes infinite, preventing the electric actuator 10 from reversely driving.

[0197] Next, a control method by the control unit 90 of this embodiment will be described. The electric actuator 10 assembled to the switching mechanism 70 performs a self-learning process.

[0198] In the self-learning process, the control unit 90 stores the rotation angles (bottom position rotation angles) of the detent plate 71 when the contact portion 76b is located at the bottom (first bottom) 79ca of the first valley portion 79A and the bottom (second bottom) 79cb of the second valley portion 79B. The stored bottom position rotation angles are used to control the rotation angle of the output shaft 46.

[0199] Fig. 5 is a schematic diagram of the detent plate 71 and contact portion 76b of this embodiment, showing the initial state of the self-learning process. Fig. 6 is a schematic diagram of the detent plate 71 and contact portion 76b of this embodiment, showing the first acquisition step in the first valley acquisition step of the self-learning process.

[0200] In Fig. 5 and Fig. 6, one circumferential side (one side outer peripheral edge) is indicated by +θ, and the other circumferential side (other side outer peripheral edge) is indicated by -θ.

[0201] As shown in FIG. 5, the first valley portion 79A of the detent plate 71 has a first bottom portion (bottom portion) 79ca, a first inclined surface (inclined surface) 79d, and a second inclined surface (inclined surface) 79e.

[0202] The first bottom portion 79ca is a portion that is perpendicular to the radial direction of the central axis J1.

[0203] The first inclined surface 79d extends continuously to one circumferential side (+θ) of the first bottom portion 79ca. That is, the first inclined surface 79d continues from the first bottom portion 79ca to one outer peripheral edge of the first bottom portion 79ca (one side of the outer peripheral edge 71a).

[0204] The second inclined surface 79e extends continuously to the other circumferential side (-θ) of the first bottom portion 79ca. That is, the second inclined surface 79e continues from the first bottom portion 79ca to the other-side outer peripheral edge of the first bottom portion 79ca (the other side of the outer peripheral edge 71a). The first inclined surface 79d and the second inclined surface 79e are each smoothly curved.

[0205] In the first valley portion 79A, the first inclined surface 79d and the second inclined surface 79e are symmetrical with respect to a reference line L5 that passes through the first bottom portion 79ca and the central axis J1 in a plan view in the axial direction.

[0206] In the following description, the "inclination angle" of each portion of the outer peripheral edge 71a of the detent plate 71 means the angle of each portion relative to the circumferential direction (direction perpendicular to the radial direction) when viewed axially of the detent plate 71. The inclination angle of the first valley portion 79A at the first bottom portion 79ca is 0°.

[0207] The first inclined surface 79d has a first region 79da and a second region 79db.

[0208] The first region 79da is located closer to the first bottom 79ca than the second region 79db. The first region 79da continues to the first bottom 79ca. The first region 79da has a concave curved surface that recesses radially inward. The center of curvature of the first region 79da is located radially outward from the outer circumferential edge 71a. The inclination angle of the first region 79da gradually increases with increasing distance from the first bottom 79ca.

[0209] The second region 79db is located farther from the first bottom 79ca than the first region 79da. The second region 79db has a curved surface that is convex radially outward. The center of curvature of the second region 79db is located radially inward relative to the outer circumferential edge 71a. The inclination angle of the second region 79db gradually decreases with increasing distance from the first bottom 79ca.

[0210] A first boundary 79dc is provided between the first region 79da and the second region 79db. The first boundary 79dc is an inflection point where the curvature direction is reversed.

[0211] The second inclined surface 79e has a third region 79ea and a fourth region 79eb.

[0212] The third region 79ea is located closer to the first bottom 79ca than the fourth region 79eb. The third region 79ea continues to the first bottom 79ca. The third region 79ea has a concave curved surface that recesses radially inward. The center of curvature of the third region 79ea is located radially outward from the outer circumferential edge 71a. The inclination angle of the third region 79ea gradually increases with increasing distance from the first bottom 79ca.

[0213] The fourth region 79eb is located farther from the first bottom 79ca than the third region 79ea. The fourth region 79eb has a curved surface that is convex radially outward. The center of curvature of the fourth region 79eb is located radially inward relative to the outer circumferential edge 71a. The inclination angle of the fourth region 79eb gradually decreases with increasing distance from the first bottom 79ca.

[0214] A second boundary 79ec is provided between the third region 79ea and the fourth region 79eb. The second boundary 79ec is an inflection point where the curvature direction is reversed.

[0215] In the switching mechanism 70 of this embodiment immediately after assembly, the contact portion 76b is disposed inside one of the valley portions 79 of the detent plate 71.

[0216] In the initial state of the self-learning process for the first valley portion 79A, the contact position P is preferably located at the first bottom portion 79ca.

[0217] However, in the switching mechanism 70 immediately after assembly, due to variations in assembly or the like, the initial position of the contact position P in the initial state of the self-learning process may be positioned at a position displaced from the first bottom portion 79ca.

[0218] In this embodiment, as shown in FIG. 5, a case will be described in which, in the initial state of the self-learning process, the contact position P between the contact portion 76b and the outer circumferential edge 71a is located in the first region 79da of the first valley portion 79A.

[0219] The self-learning step of this embodiment includes a first valley acquisition step and a second valley acquisition step.

[0220] The first valley acquisition step is a step of acquiring a first bottom position rotation angle, which is the bottom position rotation angle of the first valley 79A. The second valley acquisition step is a step of acquiring a second bottom position rotation angle, which is the bottom position rotation angle of the second valley 79B.

[0221] The first valley acquisition step and the second valley acquisition step each include a first acquisition step, a second acquisition step, and a calculation step.

[0222] First, the first obtaining step in the first valley obtaining step will be described.

[0223] 6, the control unit 90 rotates the detent plate 71 to the other circumferential side (-θ) about the central axis J1 by driving the motor 20. For example, the control unit 90 rotates the detent plate 71 to the other circumferential side (-θ) to such an extent that the contact position P passes over the first boundary portion 79dc.

[0224] As a result, the contact position P moves relatively to one circumferential side (+θ) (one-side outer peripheral edge) with respect to the detent plate 71. In the first obtaining step shown in Fig. 6, the contact position P moves radially outward from the central axis J1 along the first inclined surface 79d.

[0225] While rotating the detent plate 71, the control unit 90 monitors the rotation angle of the output shaft 46 detected by the rotation sensor 95 and the current value of the motor 20 detected by the current sensor 96. The rotation angle of the output shaft 46 means the rotation angle of the detent plate 71.

[0226] In the following description, the angle by which contact position P moves relative to detent plate 71 as detent plate 71 rotates will be referred to as the “movement angle.” The movement angle of contact position P is an angle that is equal in absolute value to the rotation angle of detent plate 71 but has reversed sign.

[0227] FIG. 7 is a graph showing the relationship between the current value (absolute value) of the motor 20 and the movement angle of the contact position P around the central axis J1 in the first acquisition step.

[0228] The first acquisition process is a process in which the control unit 90 drives the motor 20 and acquires the detected angle of the rotation sensor 95 as the first rotation angle (detection angle) θa when the current value detected by the current sensor 96 exceeds the first threshold value (threshold value) Ia when the contact position P passes the first inclined surface 79d.

[0229] When the contact position P moves to one circumferential side (+θ) along the first inclined surface 79d, the reaction force that the contact portion 76b exerts on the detent plate 71 also increases, and the value of the current flowing through the motor 20 also gradually increases. The control unit 90 acquires, as the first rotation angle θa, the angle detected by the rotation sensor when the current value exceeds a preset first threshold value Ia.

[0230] The current value of the motor 20 in the first acquisition step increases relatively rapidly when the contact position P passes through the first region 79da, and increases relatively gradually when the contact position P passes through the second region 79db.

[0231] In this embodiment, it is preferable to set the first rotation angle θa within the first region 79da. This allows the control unit 90 to monitor whether the current value has exceeded the first threshold Ia in the region where the current value increases rapidly, making it easier to accurately determine whether the first threshold Ia has been exceeded. This allows the control unit 90 to obtain a more accurate first rotation angle θa. Note that the first rotation angle θa may also be set within the second region 79db.

[0232] After performing the first acquisition step, the control unit 90 may perform a return step of returning the contact position P to the initial state shown in FIG.

[0233] The contact position P immediately after the first acquisition process is located in the second region 79db of the first inclined surface 79d or on one circumferential side (+θ) of the second region 79db. In the returning process, the control unit 90 rotates the detent plate 71 by a fixed angle to one circumferential side (+θ). More specifically, in the returning process, the control unit 90 rotates the detent plate 71 by the same angle as the rotation angle of the detent plate 71 in the first acquisition process, in the opposite direction from the first acquisition process.

[0234] As a result, the control unit 90 moves the contact position P to the other circumferential side (-θ), and moves the contact position P to the first region 79da of the first valley portion 79A.

[0235] The contact position P after the return process does not need to exactly match the initial position in the first acquisition process, and may be positioned slightly shifted to one side or the other in the circumferential direction from the initial position. By going through the return process, the electric actuator 10 completes preparations for performing the second acquisition process.

[0236] Next, the second obtaining step in the first valley obtaining step will be described.

[0237] 8 is a schematic diagram of the detent plate 71 and the contact portion 76b of this embodiment, illustrating the second acquisition step in the first valley acquisition step of the self-learning process. In FIG. 8, one circumferential side (one-side outer peripheral edge) is indicated by +θ, and the other circumferential side (the other-side outer peripheral edge) is indicated by −θ.

[0238] 8, the control unit 90 rotates the detent plate 71 to one circumferential side (+θ) about the central axis J1 by driving the motor 20. For example, the control unit 90 rotates the detent plate 71 to one circumferential side (+θ) to such an extent that the contact position P passes over the second boundary portion 79ec.

[0239] As a result, the contact position P moves relatively to the other circumferential side (-θ) with respect to the detent plate 71, and moves radially outward from the central axis J1 along the second inclined surface 79e via the first bottom portion 79ca.

[0240] While rotating the detent plate 71 , the control unit 90 monitors the rotation angle of the output shaft 46 detected by the rotation sensor 95 and the current value of the motor 20 detected by the current sensor 96 .

[0241] FIG. 9 is a graph showing the relationship between the current value (absolute value) of the motor 20 and the movement angle of the contact position P around the central axis J1 in the second acquisition step.

[0242] It should be noted that, since the rotation direction of the motor 20 is reversed between the first acquisition process and the second acquisition process, the positive and negative signs of the actual measured current values ​​are reversed between the first acquisition process and the second acquisition process.

[0243] The second acquisition process is a process in which the control unit 90 drives the motor 20 and acquires the detected angle of the rotation sensor 95 as the second rotation angle (detection angle) θb when the current value detected by the current sensor 96 exceeds the second threshold value (threshold value) Ib when the contact position P passes over the second inclined surface 79e.

[0244] When the contact position P moves to the other circumferential side (-θ) along the second inclined surface 79e, the reaction force that the contact portion 76b exerts on the detent plate 71 also increases, and the value of the current flowing through the motor 20 also gradually increases.

[0245] The control unit 90 acquires the angle detected by the rotation sensor 95 when the current value exceeds a preset second threshold value Ib as the second rotation angle θb.

[0246] In this embodiment, the first threshold value Ia and the second threshold value Ib are different values, but they may be the same value. The first threshold value Ia and the second threshold value Ib in the first acquisition step and the second acquisition step are set appropriately depending on the shape of the first valley portion 79A.

[0247] The current value of the motor 20 in the second obtaining step increases relatively rapidly when the contact position P passes through the third region 79ea, and increases relatively gradually when the contact position P passes through the fourth region 79eb.

[0248] In this embodiment, it is preferable to set the second rotation angle θb within the third region 79ea. This allows the control unit 90 to monitor whether the second threshold value Ib has been exceeded in the region where the current value increases rapidly, making it easier to accurately determine whether the second threshold value Ib has been exceeded. This allows the control unit 90 to obtain a more accurate second rotation angle θb. Note that the second rotation angle θb may also be set within the fourth region 79eb.

[0249] FIG. 10 is a graph that combines the graphs of the relationship between the movement angle of the contact position P and the current value (absolute value) shown in FIGS. 7 and 9 into one graph.

[0250] The control unit 90 performs a calculation step after the first acquisition step and the second acquisition step.

[0251] In the calculation step, the control unit 90 stores the rotation angle between the first rotation angle θa and the second rotation angle θb as the first bottom position rotation angle θc in the state where the contact position P is located at the first bottom 79ca.

[0252] In the calculation step, the control unit 90 stores the angle obtained by dividing the first rotation angle θa and the second rotation angle θb by a preset ratio as the first bottom position rotation angle θc.

[0253] In this embodiment, the control unit 90 sets the central angle between the first rotation angle θa and the second rotation angle θb as the first bottom position rotation angle θc of the first valley portion 79A. That is, the control unit 90 in this embodiment stores "1:1" as the preset ratio.

[0254] In the calculation step, the control unit 90 stores the angle obtained by dividing the first rotation angle θa and the second rotation angle θb at a ratio of 1:1 as the first bottom position rotation angle θc. That is, the first bottom position rotation angle θc in this embodiment is expressed by the following equation. θc=(θa+θb) / 2

[0255] The first bottom position rotation angle θc stored in this embodiment is used as a stop position of the detent plate 71 when the switching mechanism 70 is operated by the motor 20.

[0256] 5, the contact position P is located in the first region 79da, shifted from the first bottom portion 79ca. Therefore, the contact position P after the returning step is also located in the first region 79da.

[0257] In this embodiment, in the second acquisition process, the contact position P moves from the first region 79da to the fourth region 79eb via the first bottom 79ca. Therefore, the movement angle of the contact position P until the second rotation angle θb is acquired in the second acquisition process is larger than the movement angle of the contact position P until the first rotation angle θa is acquired in the first acquisition process. That is, in the first valley acquisition process, the amount of rotation of the detent plate 71 is larger in the second acquisition process than in the first acquisition process.

[0258] For example, in the second acquisition step of the first valley acquisition step, the control unit 90 controls the motor 20 so that the amount of rotation of the detent plate 71 is increased compared to the first acquisition step, thereby acquiring the second rotation angle θb. For example, when the control unit 90 is unable to acquire the second rotation angle θb before the rotation angle of the detent plate 71 reaches a preset target angle, the control unit 90 rotates the detent plate 71 beyond the target angle until the second rotation angle θb is acquired.

[0259] After acquiring the first bottom position rotation angle θc in the first valley acquisition step, the control unit 90 performs the second valley acquisition step. In the second valley acquisition step, the control unit 90 acquires the second bottom position rotation angle, which is the bottom position rotation angle of the second valley 79B.

[0260] 11 is a schematic diagram of the detent plate 71 and the contact portion 76b of this embodiment, showing an example of the initial state in the second valley portion acquisition process of the self-learning process. In FIG. 11, one circumferential side (one-side outer peripheral edge) is indicated by +θ, and the other circumferential side (other-side outer peripheral edge) is indicated by −θ.

[0261] In this embodiment, after performing the first valley acquisition process, the control unit 90 drives the motor 20 and rotates the detent plate 71 to one circumferential side (+θ) around the central axis J1, thereby moving the contact position P to the other circumferential side (-θ), and positions the contact position P at the initial position of the second valley acquisition process shown in Figure 11.

[0262] The second valley portion 79B has a second bottom portion (bottom portion) 79cb, a third inclined surface (inclined surface) 79f, and a fourth inclined surface (inclined surface) 79g.

[0263] The second bottom portion 79cb is a portion that is perpendicular to the radial direction of the central axis J1. In the second valley portion 79B, the inclination angle of the second bottom portion 79cb is 0°.

[0264] The third inclined surface 79f extends continuously to one circumferential side (+θ) of the second bottom portion 79cb. That is, the third inclined surface 79f continues from the second bottom portion 79cb to one outer peripheral edge of the second bottom portion 79cb (one side of the outer peripheral edge 71a).

[0265] The fourth inclined surface 79g extends continuously toward the other circumferential side (-θ) of the second bottom portion 79cb. That is, the fourth inclined surface 79g continues from the second bottom portion 79cb to the other-side outer peripheral edge of the second bottom portion 79cb (the other side of the outer peripheral edge 71a). The third inclined surface 79f and the fourth inclined surface 79g are each smoothly curved.

[0266] In this embodiment, the first valleys 79A and the second valleys 79B have the same shape. That is, the first bottoms 79ca and the second bottoms 79cb have the same shape. The first inclined surfaces 79d and the third inclined surfaces 79f have the same shape. The second inclined surfaces 79e and the fourth inclined surfaces 79g have the same shape.

[0267] The control unit 90 estimates the second bottom position rotation angle in a state in which the contact position P is located at the second bottom 79cb of the second valley 79B, based on the angle information acquired in the first valley acquisition step.

[0268] The contact position P shown in Fig. 11 indicates the initial position of the contact position P in the second valley portion obtaining step. The contact position P shown in Fig. 11 is located at the second bottom portion 79cb.

[0269] 11 is a position in the second valley obtaining step that corresponds to the initial position of the contact position P in the first valley obtaining step. The imaginary contact position P1 is located on the third inclined surface 79f.

[0270] In the second valley acquisition step, the control unit 90 performs the self-learning step by setting the contact position P located on the second bottom portion 79cb located on the other circumferential side (-θ) of the imaginary contact position P1 as the initial position.

[0271] In the second valley acquisition step, the control unit 90 estimates the second bottom position rotation angle based on, for example, the first rotation angle θa or the second rotation angle θb acquired in the first acquisition step.

[0272] Furthermore, the control unit 90 may estimate the second bottom position rotation angle based on the first bottom position rotation angle θc acquired in the first acquisition step, for example.

[0273] In this embodiment, the control unit 90 sets the estimated second bottom position rotation angle in the second valley acquisition step as the initial position in the self-learning step.

[0274] After estimating the second bottom-position rotation angle, the control unit 90 performs the first acquisition step, the second acquisition step, and the calculation step in the second valley acquisition step.

[0275] In the first acquisition step of the second valley acquisition step, the control unit 90 drives the motor 20 and acquires the detected angle (third rotation angle) of the rotation sensor 95 when the current value detected by the current sensor 96 exceeds a threshold value (third threshold value) when the contact position P passes over the third inclined surface 79f.

[0276] Specifically, the control unit 90 drives the motor 20 to rotate the detent plate 71 from the initial state shown in FIG. 11 to the other circumferential side (−θ) around the central axis J1.

[0277] As a result, the contact position P moves relatively to one circumferential side (+θ) (one-side outer peripheral edge) with respect to the detent plate 71. In the first acquisition step of the second valley portion acquisition step, the contact position P moves radially outward from the center axis J1 along the third inclined surface 79f.

[0278] While rotating the detent plate 71 , the control unit 90 monitors the rotation angle of the output shaft 46 detected by the rotation sensor 95 and the current value of the motor 20 detected by the current sensor 96 .

[0279] When the contact position P moves to one circumferential side (+θ) along the third inclined surface 79f, the reaction force that the contact portion 76b exerts on the detent plate 71 also increases, and the value of the current flowing through the motor 20 also gradually increases. The control unit 90 acquires, as the third rotation angle, the angle detected by the rotation sensor when the current value exceeds a preset third threshold value.

[0280] In the second valley acquisition step, the control unit 90 may perform a return step of returning the contact position P to the initial state shown in FIG. 11 after performing the first acquisition step.

[0281] The contact position P immediately after the first acquisition step is performed is located on the third inclined surface 79f or on one circumferential side (+θ) of the third inclined surface 79f. In the returning step, the control unit 90 rotates the detent plate 71 by a fixed angle to one circumferential side (+θ). More specifically, in the returning step, the control unit 90 rotates the detent plate 71 by the same angle as the rotation angle of the detent plate 71 in the first acquisition step of the second valley acquisition step, in the opposite direction from the first acquisition step of the second valley acquisition step.

[0282] As a result, the control unit 90 moves the contact position P to the other circumferential side (-θ), and moves the contact position P to the second bottom portion 79cb.

[0283] In the second valley acquisition process, the contact position P after the return process does not need to exactly match the initial position in the first acquisition process, and may be positioned slightly shifted to one side or the other in the circumferential direction from the initial position. By going through the return process, the electric actuator 10 completes preparations for performing the second acquisition process of the second valley acquisition process.

[0284] In the second acquisition step of the second valley acquisition step, the control unit 90 drives the motor 20 and acquires the detected angle (fourth rotation angle) of the rotation sensor 95 when the current value detected by the current sensor 96 exceeds a threshold value (fourth threshold value) when the contact position P passes over the fourth inclined surface 79g.

[0285] Specifically, in the second obtaining step of the second valley obtaining step, the control unit 90 drives the motor 20 to rotate the detent plate 71 to one side (+θ) in the circumferential direction about the central axis J1.

[0286] As a result, the contact position P moves relatively to the other circumferential side (-θ) with respect to the detent plate 71, and moves radially outward from the center axis J1 along the fourth inclined surface 79g.

[0287] While rotating the detent plate 71 , the control unit 90 monitors the rotation angle of the output shaft 46 detected by the rotation sensor 95 and the current value of the motor 20 detected by the current sensor 96 .

[0288] In the second valley acquisition process, as in the first valley acquisition process, the positive and negative signs of the measured current values ​​are reversed between the first acquisition process and the second acquisition process.

[0289] When the contact position P moves to the other circumferential side (-θ) along the fourth inclined surface 79g, the reaction force that the contact portion 76b exerts on the detent plate 71 also increases, and the value of the current flowing through the motor 20 also gradually increases.

[0290] The control unit 90 acquires, as a fourth rotation angle, the angle detected by the rotation sensor 95 when the current value exceeds a fourth threshold value set in advance.

[0291] In this embodiment, since the first valley 79A and the second valley 79B have the same shape, the first threshold value Ia and the third threshold value are the same value, and the second threshold value Ib and the fourth threshold value are the same value, but these may also be different values. The third threshold value and the fourth threshold value in the second valley acquisition step are set appropriately depending on the shape of the second valley 79B.

[0292] In the second valley acquisition step, the control unit 90 performs a calculation step after the first acquisition step and the second acquisition step.

[0293] In the calculation step of the second valley acquisition step, the control unit 90 stores a rotation angle between the third rotation angle and the fourth rotation angle as the second bottom position rotation angle when the contact position P is located at the second bottom 79cb.

[0294] In the calculation step of the second valley acquisition step, the control unit 90 stores an angle obtained by dividing the third rotation angle and the fourth rotation angle by a preset ratio as the second bottom position rotation angle.

[0295] Here, when the control unit 90 performs the second valley acquisition step, it estimates the second bottom-position rotation angle based on the angle information acquired in the first valley acquisition step.

[0296] In the calculation step of the second valley acquisition process, the control unit 90 stores the rotation angle calculated based on the third rotation angle and the fourth rotation angle as the latest second bottom position rotation angle. That is, in the calculation step of the second valley acquisition process, the control unit 90 updates the second bottom position rotation angle based on the rotation angle between the third rotation angle and the fourth rotation angle.

[0297] The second bottom position rotation angle updated by the control unit 90 is used as a stop position of the detent plate 71 when the switching mechanism 70 is operated by the motor 20.

[0298] In the first valley obtaining step described above, the initial position of the contact position P is shifted from the first bottom portion 79ca to one circumferential side (+θ) and is located in the first region 79da, as shown in FIG.

[0299] The initial position of contact position P in the self-learning process is preferably located at the bottom of valley portion 79 (for example, first bottom portion 79ca), but may be located at a position shifted from the bottom due to variations in assembly, etc. In this case, the amount of movement until the current value detected by current sensor 96 exceeds the threshold may increase at contact position P passing through the inclined surface of valley portion 79, compared to when the initial position of contact position P is at the bottom.

[0300] For example, in the second acquisition step of the first valley acquisition step described above, the control unit 90 rotates the detent plate 71 a greater amount than in the first acquisition step when acquiring the second rotation angle θb.

[0301] In the second valley acquisition process, if the second acquisition process is performed using a virtual contact position P1, which corresponds to the initial position of the contact position P in the first valley acquisition process, as the initial position, the control unit 90 needs to rotate the detent plate 71 more than in the first acquisition process when acquiring the fourth rotation angle.

[0302] Here, as described above, in the second valley acquisition process, the control unit 90 of this embodiment estimates the second bottom position rotation angle based on the angle information acquired in the first valley acquisition process, and sets the estimated second bottom position rotation angle as the initial position of the self-learning process.

[0303] 11, in the second valley acquisition process of this embodiment, the initial position of contact position P either coincides with second bottom 79cb or, if not, is located near second bottom 79cb. That is, the second bottom-position rotation angle estimated by control unit 90 based on the angle information acquired in the first valley acquisition process is not significantly different from second bottom 79cb. More specifically, the difference between the initial position and second bottom 79cb in the second valley acquisition process can be made smaller than the difference between the initial position and first bottom 79ca in the first valley acquisition process.

[0304] The control unit 90 calculates the initial position of the contact position P in the first valley acquisition step shown in FIG. 5 based on, for example, the first rotation angle θa, the second rotation angle θb, or the first bottom position rotation angle θc.

[0305] The control unit 90 estimates the second bottom position rotation angle based on the calculated initial position of the contact position P in the first valley portion obtaining step and the shape of the detent plate 71.

[0306] In this embodiment, the first valleys 79A and the second valleys 79B have the same shape. Also, in this embodiment, the second bottom position rotation angle is, for example, the first bottom position rotation angle plus 23°.

[0307] In the initial state of the first valley acquisition process shown in Figure 5, if the contact position P is located at a position shifted 3° to one circumferential side (+θ) from the first bottom 79ca, the virtual contact position P1 shown in Figure 11 is located at a position shifted 3° to one circumferential side (+θ) from the second bottom 79cb.

[0308] Therefore, the control unit 90 estimates the second bottom position rotation angle as the angle obtained by adding 26° to the first bottom position rotation angle, and performs the second valley acquisition process using the estimated second bottom position rotation angle as the initial position of the contact position P.

[0309] The control unit 90 may estimate the second bottom position rotation angle by subtracting a predetermined angle from the angle information acquired in the first valley acquisition process, or may estimate the second bottom position rotation angle by using a predetermined function.

[0310] Even if the switching mechanism 70 is assembled with the contact position P positioned at a position offset from the first bottom 79ca, the control unit 90 can estimate the second bottom position rotation angle based on the angle information acquired in the first valley acquisition process, thereby aligning the initial position of the contact position P in the second valley acquisition process with the second bottom 79cb or positioning it near the second bottom 79cb.

[0311] Therefore, in the second valley acquisition process, the control unit 90 does not need to control the motor 20 to increase the amount of rotation of the detent plate 71 according to the angle by which the initial position of the contact position P deviates from the second bottom 79cb, and can efficiently perform the second valley acquisition process and acquire the second bottom position rotation angle. This allows the second valley acquisition process to be completed in a shorter time than the first valley acquisition process.

[0312] In this embodiment, the first bottom position rotation angle θc of the first valley portion 79A is used to control the motor 20 as the stop position of the detent plate 71 in the parking state. On the other hand, the second bottom position rotation angle of the second valley portion 79B is used to control the motor 20 as the stop position of the detent plate 71 in the non-parking state.

[0313] The first valley portion 79A and the second valley portion 79B may have different shapes. When the control unit 90 estimates the second bottom position rotation angle, the predetermined angle to be added to or subtracted from the angle information acquired in the first valley portion acquisition process is set appropriately depending on the shape of the detent plate 71.

[0314] In the present embodiment, the angle information acquired in the first valley acquisition process is used to determine the initial position of the contact position P in the second valley acquisition process. However, in the second valley acquisition process, the control unit 90 may acquire the second bottom position rotation angle of the second bottom 79cb by performing a calculation using the angle information acquired in the first valley acquisition process.

[0315] For example, the second valley acquisition step may be a step of acquiring the second bottom position rotation angle of the second bottom portion 79cb by adding 23° to the first bottom position rotation angle acquired in the first valley acquisition step. In this case, the rotation angle when the contact position P is located on the second bottom portion 79cb can be acquired by performing only the calculation without actually driving the detent plate 71, and the time required for the second valley acquisition step can be further reduced.

[0316] However, in this case, the acquired rotation angle includes dimensional errors (errors in the relative position of the second bottom portion 79cb with respect to the first bottom portion 79ca) during manufacturing of the detent plate 71. For this reason, as shown in the above-described embodiment, the angle information acquired in the first valley portion acquisition process is used only to acquire the initial position of the contact position P in the second valley portion acquisition process, and self-learning is performed from that initial position, thereby improving the accuracy of acquiring the second bottom position rotation angle, which is the rotation angle of the detent plate 71 when the contact position P is located on the second bottom portion 79cb.

[0317] The electric actuator 10 of this embodiment is an electric actuator that rotates a plate-shaped first member 71 having a surface 71f and an outer peripheral edge 71a around a central axis J1 perpendicular to the surface 71f, and changes the contact position of a second member 76 having a contact portion 76b that contacts the outer peripheral edge 71a, and is equipped with an output shaft 46 that extends around the central axis J1 and is connected to the first member 71, a motor 20, a reducer 30 that slows the rotation of the motor 20 and rotates the output shaft 46 around the central axis J1, a rotation sensor 95 that detects the rotation angle of the output shaft 46, a current sensor 96 that detects the value of the current flowing through the motor 20, and a control unit 90 that controls the motor 20.

[0318] The outer peripheral edge 71a has a first valley portion 79A and a second valley portion 79B each having a bottom portion and two inclined surfaces connected to both sides of the bottom portion.

[0319] The control unit 90 rotates the output shaft 46 and acquires the detected angle of the rotation sensor 95 when the current value detected by the current sensor 96 exceeds a threshold value when the contact position P located in the first valley portion 79A passes over the inclined surface.

[0320] In addition, the control unit 90 performs a first valley acquisition process to acquire the first bottom position rotation angle θc when the contact position P is located at the bottom 79ca of the first valley 79A based on the acquired detection angle, and a second valley acquisition process to estimate the second bottom position rotation angle when the contact position P is located at the bottom 79cb of the second valley 79B based on the angle information acquired in the first valley acquisition process.

[0321] According to the electric actuator 10 of this embodiment, even if the initial position of contact position P in the first valley acquisition process is shifted from the first bottom 79ca due to assembly variations or the like, the control unit 90 can correct the initial position of contact position P in the second valley acquisition process based on the angle information acquired in the first valley acquisition process. Furthermore, in the second valley acquisition process, the second bottom position rotation angle of the second bottom 79cb can also be calculated based on the angle information acquired in the first valley acquisition process.

[0322] According to the above-described configuration, the time required for the second valley obtaining step can be shortened compared to when the first valley obtaining step and the second valley obtaining step are performed separately. In other words, it is possible to provide an electric actuator 10 that can efficiently obtain the bottom position rotation angles of the multiple valleys 79 of the first member 71.

[0323] In the second valley acquisition step, the control unit 90 of this embodiment may estimate the second bottom position rotation angle based on the detected angle of the first valley 79A acquired in the first valley acquisition step.

[0324] Even if the initial position of the contact position P in the first acquisition process is positioned at a position shifted from the first bottom 79ca, the control unit 90 can efficiently acquire the second bottom position rotation angle by estimating the second bottom position rotation angle based on the first rotation angle θa or the second rotation angle θb, which are the detected angles of the first valley 79A.

[0325] In the second valley acquisition step, the control unit 90 of this embodiment may estimate the second bottom position rotation angle based on the first bottom position rotation angle θc of the first valley 79A acquired in the first valley acquisition step.

[0326] The control unit 90 can efficiently acquire the second bottom position rotation angle by estimating the second bottom position rotation angle based on the first bottom position rotation angle θc acquired in the first valley acquisition process, even if the initial position of the contact position P in the first acquisition process is positioned at a position shifted from the first bottom 79ca.

[0327] In the first valley acquisition process, the control unit 90 of this embodiment may acquire a first rotation angle θa, which is the detected angle at one inclined surface 79d of the first valley 79A, and a second rotation angle θb, which is the detected angle at the other inclined surface 79e of the first valley 79A, and may acquire the rotation angle between the first rotation angle θa and the second rotation angle θb as the first bottom position rotation angle θc.

[0328] The control unit 90 can appropriately set the stop position of the detent plate 71 by setting the rotation angle between the first rotation angle θa and the second rotation angle θb as the first bottom position rotation angle θc.

[0329] The control unit 90 of this embodiment may estimate the second bottom-position rotation angle by adding or subtracting a predetermined angle to the angle information acquired in the first valley acquisition step.

[0330] The control unit 90 can efficiently estimate the second bottom-position rotation angle by adding or subtracting a predetermined angle to the angle information acquired in the first valley acquisition step.

[0331] The control unit 90 of this embodiment rotates the output shaft 46, and sets the second bottom position rotation angle estimated based on the angle information acquired in the first valley acquisition process as the initial position of the contact position P in the second valley acquisition process.The control unit 90 then acquires, as the third rotation angle, the detection angle of the rotation sensor 95 when the current value detected by the current sensor 96 when the contact position P located in the second valley 79B passes over one inclined surface 79f of the second valley 79B exceeds a threshold value, and acquires, as the fourth rotation angle, the detection angle of the rotation sensor 95 when the current value detected by the current sensor 96 when the contact position P located in the second valley 79B passes over the other inclined surface 79g of the second valley 79B exceeds a threshold value.The control unit 90 may then update the second bottom position rotation angle based on the rotation angle between the third rotation angle and the fourth rotation angle.

[0332] The control unit 90 can accurately acquire the second bottom position rotation angle by estimating the second bottom position rotation angle based on the angle information acquired in the first valley acquisition process, and then updating the second bottom position rotation angle based on the third rotation angle and fourth rotation angle in the second valley 79B.

[0333] Although the embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments and their modifications are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0334] For example, in the above embodiment, the state in which the contact portion 76b is located in the first valley portion 79A is the parking state, and the state in which the contact portion 76b is located in the second valley portion 79B is the non-parking state. However, depending on the configuration of the switching mechanism 70 shown in FIG. 2, the state in which the contact portion 76b is located in the first valley portion 79A may be the non-parking state, and the state in which the contact portion 76b is located in the second valley portion 79B may be the parking state.

[0335] The use of the electric actuator to which the present invention is applied is not particularly limited. The configuration of the reducer is not limited to that of the present embodiment, and for example, as long as each of the external gear portion and the internal gear portion is an involute gear and each of the pressure angles of the external gear portion and the internal gear portion is 22° or greater, the pressure angles of the external gear portion and the internal gear portion are not particularly limited.

[0336] Furthermore, the number of teeth of the external gear portion and the number of teeth of the internal gear portion are not particularly limited. Furthermore, the multiple protrusions may be provided on the external gear, and the multiple through-holes may be provided on the output flange portion. In this case, each of the multiple protrusions protrudes from the external gear toward the output flange portion, i.e., toward the other axial side, and is inserted into the through-hole.

[0337] The number of protrusions and the number of through-holes provided in the transmission mechanism may each be seven or less, or nine or more. The protrusions and the flange may be separate bodies. In this case, each of the protrusions is fixed by press-fitting or the like into each of the holes that penetrate the flange.

[0338] The control unit may also store the second bottom position rotation angle estimated based on the angle information acquired in the first valley portion acquisition process as the stop position of the detent plate 71 in the non-parking state. In this case, the control unit does not need to reciprocate the contact portion 76b relative to the detent plate 71 in the second valley portion acquisition process, and therefore the self-learning process can be performed more efficiently.

[0339] The present technology can be configured as follows. (1) An electric actuator that rotates a plate-shaped first member having a surface and an outer periphery around a central axis perpendicular to the surface, and changes a contact position of a second member having a contact portion that contacts the outer periphery, comprising: an output shaft that extends around the central axis and is connected to the first member; a motor; a reducer that reduces the rotation of the motor and rotates the output shaft around the central axis; a rotation sensor that detects the rotation angle of the output shaft; a current sensor that detects the value of current flowing through the motor; and a control unit that controls the motor, wherein the outer periphery has a bottom and two inclined surfaces connected to both sides of the bottom. the control unit performs a first valley acquisition process of rotating the output shaft, acquiring a detection angle of the rotation sensor when a current value detected by the current sensor exceeds a threshold value when the contact position located at the bottom of the first valley portion based on the acquired detection angle, and a second valley acquisition process of estimating a second bottom position rotation angle when the contact position is located at the bottom of the second valley portion based on angle information acquired in the first valley acquisition process. (2) The electric actuator according to (1), wherein in the second valley acquisition step, the control unit uses the detected angle of the first valley acquired in the first valley acquisition step as the angle information. (3) The electric actuator according to (1), wherein in the second valley portion acquisition process, the control unit uses the first bottom position rotation angle of the first valley portion acquired in the first valley portion acquisition process as the angle information. (4) An electric actuator according to any one of (1) to (3), wherein in the first valley portion acquisition process, the control unit acquires a first rotation angle, which is the detected angle on one of the inclined surfaces of the first valley portion, and a second rotation angle, which is the detected angle on the other inclined surface of the first valley portion, and acquires the rotation angle between the first rotation angle and the second rotation angle as the first bottom position rotation angle. (5) An electric actuator according to any one of (1) to (4), wherein the control unit estimates the second bottom position rotation angle by adding or subtracting a predetermined angle to the angle information acquired in the first valley portion acquisition process. (6) The electric actuator described in any one of (1) to (5), wherein the control unit rotates the output shaft, sets the second bottom position rotation angle as the initial position of the contact position in the second valley portion acquisition process, and then acquires, as a third rotation angle, the detection angle of the rotation sensor when the current value detected by the current sensor exceeds a threshold value when the contact position located in the second valley portion passes through one of the inclined surfaces of the second valley portion, acquires, as a fourth rotation angle, the detection angle of the rotation sensor when the current value detected by the current sensor exceeds a threshold value when the contact position located in the second valley portion passes through the other inclined surface of the second valley portion, and updates the second bottom position rotation angle based on the rotation angle between the third rotation angle and the fourth rotation angle. [Explanation of symbols]

[0340] 10...electric actuator, 20...motor, 30...reduction gear, 46...output shaft, 71...detent plate (first member), 71a...outer periphery, 71f...surface, 76...leaf spring member (second member) 2 members), 76b...contact portion, 79A...first valley portion, 79B...second valley portion, 79ca...bottom portion (first bottom portion), 79cb...bottom portion (second bottom portion), 79d...inclined surface (first inclined surface), 79e...inclined surface (second inclined surface), 79f...inclined surface (third inclined surface), 79g...inclined surface (fourth inclined surface), 90...control portion, 95...rotation sensor, 96...current sensor, Ia...threshold value (first threshold value), Ib...threshold value (second threshold value), J1...central axis, P...contact position, θa...first rotation angle, θb...second rotation angle, θc...first bottom position rotation angle

Claims

1. An electric actuator that rotates a plate-shaped first member having a surface and an outer peripheral edge about a central axis perpendicular to the surface, and changes a contact position of a second member having a contact portion that contacts the outer peripheral edge, an output shaft extending about the central axis and connected to the first member; A motor; a reducer that reduces the rotation speed of the motor to rotate the output shaft around the central axis; a rotation sensor for detecting a rotation angle of the output shaft; a current sensor for detecting a current value flowing through the motor; a control unit that controls the motor; Equipped with the outer periphery has a first valley portion and a second valley portion each having a bottom portion and two inclined surfaces connected to either side of the bottom portion; The control unit a first valley portion acquisition process for rotating the output shaft, acquiring a detection angle of the rotation sensor when a current value detected by the current sensor exceeds a threshold value when the contact position located at the first valley portion passes through the inclined surface, and acquiring a first bottom position rotation angle in a state where the contact position is located at the bottom of the first valley portion based on the acquired detection angle; a second valley portion acquisition step of estimating a second bottom position rotation angle in a state where the contact position is located at the bottom of the second valley portion based on the angle information acquired in the first valley portion acquisition step; To do Electric actuator.

2. the control unit, in the second valley portion acquiring step, sets the detected angle of the first valley portion acquired in the first valley portion acquiring step as the angle information. The electric actuator according to claim 1 .

3. the control unit, in the second valley portion acquiring step, sets the first bottom position rotation angle of the first valley portion acquired in the first valley portion acquiring step as the angle information. The electric actuator according to claim 1 .

4. In the first valley portion acquiring step, the control unit acquiring a first rotation angle, which is the detected angle at one of the inclined surfaces of the first valley portion, and a second rotation angle, which is the detected angle at the other inclined surface of the first valley portion; A rotation angle between the first rotation angle and the second rotation angle is acquired as the first bottom position rotation angle. The electric actuator according to claim 1 .

5. the control unit estimates the second bottom-position rotation angle by adding or subtracting a predetermined angle to the angle information acquired in the first bottom-position acquisition step. The electric actuator according to any one of claims 1 to 4.

6. The control unit The output shaft is rotated, and the second bottom position rotation angle is set to an initial position of the contact position in the second valley portion acquisition process, and then acquiring, as a third rotation angle, a detection angle of the rotation sensor at a time when a current value detected by the current sensor exceeds a threshold value when the contact position located in the second valley portion passes through one of the inclined surfaces of the second valley portion; acquiring, as a fourth rotation angle, a detection angle of the rotation sensor at a time when a current value detected by the current sensor exceeds a threshold value when the contact position located in the second valley portion passes through the other inclined surface of the second valley portion; updating the second bottom position rotation angle based on a rotation angle between the third rotation angle and the fourth rotation angle; The electric actuator according to claim 5.

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