Electric actuator

Abstract

An electric actuator is provided, which has a motor, an output shaft, a brake plate, an elastic member having a contacted portion, a first rotation sensor, a second rotation sensor, and a control unit. When an abnormality occurs in the second rotation sensor, the control unit performs the following processes: a process of rotating the motor to bring the contacted portion into contact with a first side wall portion located on the circumferential one end side of a first valley portion in the brake plate; a process of obtaining a first rotation angle detected by the first rotation sensor as a side wall position angle when the contacted portion is in contact with the first side wall portion; a reverse rotation process of reversely rotating the motor to an angle at which the first rotation angle corresponds to a target rotation angle based on the side wall position angle; and a stationary determination process of determining that the contacted portion is stationary at a parking position when the first rotation angle detected by the first rotation sensor continuously converges within a first tolerance with the target rotation angle as a reference value within a first specified time.

Description

Technical Field

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

[0002] For example, Patent Document 1 discloses a gear shift device that uses a motor as a drive source to switch the gear range. The gear shift device of Patent Document 1 includes: an encoder that outputs a pulse signal in synchronization with the rotation of the motor; a control unit that drives the motor based on the count value of the pulse signal (encoder count value) to control the switching position of the gear shift mechanism; and a braking mechanism that, when the gear shift mechanism is switched to the position of each gear, holds the gear shift mechanism in the position of each gear by engaging a engaging portion with a gear holding recess.

[0003] In the gear shift device of Patent Document 1, after rotating the motor until the engaging portion abuts against the P-gear wall (the side wall of the P-gear holding recess), the driving force of the motor is released. When the change amount of the encoder count value becomes equal to or less than a specified value, it is determined that the engaging portion is stationary at the position of the P-gear holding recess (P-gear valley position). In the gear shift device of Patent Document 1, the encoder count value obtained when it is determined that the engaging portion is stationary at the P-gear valley position is acquired (learned) as the encoder count value at the reference position.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-20459

[0005] In the technology of Patent Document 1 above, after rotating the motor until the engaging portion abuts against the P-gear wall, the driving force of the motor is released. However, it is also considered that the engaging portion moves to a position significantly deviated from the P-gear valley position in a state where the driving force of the motor is released. Even in this case, if the change amount of the encoder count value is equal to or less than a specified value, it is determined that the engaging portion is stationary at the P-gear valley position. Therefore, it is possible to erroneously learn the encoder count value obtained at a position significantly deviated from the P-gear valley position as the encoder count value at the reference position. Summary of the Invention

[0006] One aspect of the present invention is an electric actuator that switches a shift position. The electric actuator includes: a motor; an output shaft driven by the motor; a brake plate fixed to the output shaft and having a plurality of valleys, the plurality of valleys including a first valley corresponding to a parking position provided on one circumferential end side and a second valley corresponding to a non-parking position provided on the other circumferential end side; an elastic member having a contact portion that contacts one of the valleys by an elastic force generated on the elastic member as the brake plate rotates; a first rotation sensor that detects a first rotation angle that is the rotation angle of the motor; a second rotation sensor that detects a second rotation angle that is the rotation angle of the output shaft; and a control unit that controls the motor based on detection results of the first rotation angle and the second rotation angle. When an abnormality occurs in the second rotation sensor, the control unit performs the following processing: a process of rotating the motor to bring the contact portion into contact with a first side wall portion of the brake plate that is on the one circumferential end side of the first valley; a process of obtaining the first rotation angle detected by the first rotation sensor as a side wall position angle when the contact portion contacts the first side wall portion; a reverse rotation process of reversely rotating the motor to an angle at which the first rotation angle corresponds to a target rotation angle based on the side wall position angle; and a stationary determination process of determining that the contact portion is stationary at the parking position when the first rotation angle detected by the first rotation sensor continuously converges within a first tolerance with the target rotation angle as a reference value within a first specified time.

[0007] According to the above aspect of the present invention, an electric actuator is provided that can accurately determine, even when an abnormality occurs in a second rotation sensor that detects the rotation angle of an output shaft, that a contact portion is stationary in a first valley corresponding to a parking position among a plurality of valleys provided on a brake plate based on the rotation angle of a motor detected by a first rotation sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 FIG. is a view of a drive device having the electric actuator of the present embodiment as viewed from one side in the left-right direction of the vehicle.

[0009] Figure 2 FIG. is a perspective view of the electric actuator of the present embodiment.

[0010] Figure 3 FIG. is a block diagram showing a functional configuration of the electric actuator of the present embodiment.

[0011] Figure 4 FIG. is a flowchart showing a shift position switching process executed by a control unit of the electric actuator of the present embodiment.

[0012] Figure 5 This is a diagram schematically showing the situation where the contacted portion of the leaf spring member moves along the upper end surface of the brake plate during the execution of the shift position switching process.

[0013] Figure 6 This is a flowchart showing the parking position learning process executed by the control unit of the electric actuator according to the present embodiment.

[0014] Figure 7 This is a diagram schematically showing the situation where the contacted portion of the leaf spring member moves along the upper end surface of the brake plate during the execution of the parking position learning process.

[0015] Reference Numeral Explanation

[0016] 1: Driving device; 2: Housing; 3: Driving motor; 4: Reduction gear; 5: Differential device; 6: Parking lock gear; 10: Motor unit; 20: Motor; 30: Reducer; 40: Control unit; 51: First rotation sensor; 52: Second rotation sensor; 70: Parking switching mechanism; 71: Brake plate; 71a: First valley portion; 71b: Second valley portion; 71d: P side wall (first side wall portion); 76: Leaf spring member (elastic member); 76b: Contacted portion; 80: Output shaft; 100: Electric actuator. Detailed Embodiment

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0018] Figure 1 This is a diagram of the driving device 1 having the electric actuator 100 of the present embodiment as viewed from one side in the left - right direction of the vehicle. Figure 2 This is a perspective view showing the electric actuator 100 of the present embodiment. The driving device 1 of the present embodiment is mounted on an electric vehicle such as a hybrid electric vehicle (HEV), a plug - in hybrid electric vehicle (PHV), or an electric vehicle (EV), and is used as their driving source. As Figure 1 shown, the driving device 1 includes a housing 2, a driving motor 3, a reduction gear 4, a differential device 5, a parking lock gear 6, and an electric actuator 100. As Figure 1 and Figure 2 shown, the electric actuator 100 includes a motor unit 10, a parking switching mechanism 70, and an output shaft 80. The electric actuator 100 switches the shift position according to the shift operation of the vehicle.

[0019] In the following description, the vertical direction is defined and described based on the positional relationship when the drive device 1 is mounted on a vehicle located on a horizontal road surface. In addition, in the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction is the vertical direction with the +Z side as the upper side and the -Z side as the lower side. The X-axis direction is a direction perpendicular to the Z-axis direction and is the front-rear direction of the vehicle on which the drive device 1 is mounted. In the present embodiment, the +X side is one side in the front-rear direction of the vehicle, and the -X side is the other side in the front-rear direction of the vehicle. The Y-axis direction is a direction perpendicular to both the X-axis direction and the Z-axis direction and is the left-right direction of the vehicle. In the present embodiment, the +Y side is one side in the left-right direction of the vehicle, and the -Y side is the other side in the left-right direction of the vehicle.

[0020] In the present embodiment, the direction parallel to the Z-axis direction is referred to as the "vertical direction Z", the direction parallel to the X-axis direction is referred to as the "front-rear direction X", and the direction parallel to the Y-axis direction is referred to as the "left-right direction Y". In addition, the positive side (+Z side) of the Z-axis direction is referred to as the "upper side", and the negative side (-Z side) of the Z-axis direction is referred to as the "lower side". The positive side (+X side) of the X-axis direction is referred to as "one side in the front-rear direction", and the negative side (-X side) of the X-axis direction is referred to as "the other side in the front-rear direction". The positive side (+Y side) of the Y-axis direction is referred to as "one side in the left-right direction", and the negative side (-Y side) of the Y-axis direction is referred to as "the other side in the left-right direction".

[0021] The output shaft 80 is connected to the motor unit 10 and rotates through the motor unit 10. In the present embodiment, the output shaft 80 extends in the front-rear direction X with the central axis J1 as the center. In the following description, unless otherwise specified, the radial direction with the central axis J1 as the center is simply referred to as the "radial direction", and the circumferential direction with the central axis J1 as the center, that is, the direction around the central axis J1, is simply referred to as the "circumferential direction". As Figure 2 shown, the end portion on the front-rear direction side (+X side) of the output shaft 80 is a connected portion 81 connected to the motor unit 10. A plurality of spline grooves extending in the front-rear direction X are provided along the circumferential direction on the connected portion 81.

[0022] The housing 2 houses the drive motor 3, the reduction gear 4, the differential device 5, and the parking switching mechanism 70 inside. Although not shown in the drawings, oil is housed inside the housing 2. The reduction gear 4 is connected to the drive motor 3. The differential device 5 is connected to the reduction gear 4 and transmits the torque output from the drive motor 3 to the vehicle axle. The parking lock gear 6 is fixed to the gear provided on the reduction gear 4. The parking lock gear 6 is connected to the vehicle axle via the reduction gear 4 and the differential device 5. The parking lock gear 6 has a plurality of tooth portions 6a.

[0023] The parking switching mechanism 70 is driven by the motor unit 10 according to the shift operation of the vehicle. The parking switching mechanism 70 switches the parking lock gear 6 between a locked state and an unlocked state. When the shift position of the vehicle is the parking position (P range), the parking switching mechanism 70 makes the parking lock gear 6 in the locked state, and when the shift position of the vehicle is a non-parking position other than the parking position, the parking switching mechanism 70 makes the parking lock gear 6 in the unlocked state. The case where the shift position of the vehicle is a non-parking position includes, for example, the case where the shift position of the vehicle is the drive position (D range), the neutral position (N range), or the reverse position (R range). As Figure 2 shown, the parking switching mechanism 70 has a movable part 70a, a parking lock arm 77, a support member 75, and a leaf spring member 76.

[0024] The movable part 70a moves along the left-right direction Y according to the shift operation of the vehicle. That is, in the present embodiment, the left-right direction Y corresponds to the moving direction in which the movable part 70a moves. In addition, the vertical direction Z corresponds to the crossing direction that crosses the moving direction in which the movable part 70a moves, and the lower side corresponds to one side of the crossing direction. In the present embodiment, the motor unit 10 moves the movable part 70a via the output shaft 80. The position of the movable part 70a in the left-right direction Y is switched at least between the non-parking position and the parking position. That is, the movable part 70a moves between the parking position and the non-parking position through the output shaft 80. 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. 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 the parking position. The parking position is a position on the left-right direction side (+Y side) compared to the non-parking position. In Figure 2 it, the case where the movable part 70a is located in the non-parking position is shown.

[0025] The movable part 70a has a brake plate 71, a rod 72, a conical member 73, and a coil spring 74. The brake plate 71 is fixed to the output shaft 80. The brake plate 71 rotates through the output shaft 80. The brake plate 71 extends radially outward from the output shaft 80. In the present embodiment, the brake plate 71 extends upward from the output shaft 80. In the present embodiment, the brake plate 71 is in a plate shape with the plate surface facing the front-rear direction X. The width of the brake plate 71 becomes larger as it moves radially outward from the output shaft 80. The brake plate 71 has a plurality of valleys, and the plurality of valleys include a first valley 71a corresponding to the parking position provided on the circumferential one end side of the brake plate 71 and a second valley 71b corresponding to the non-parking position provided on the circumferential other end side of the brake plate 71. In addition, in Figure 2 it, the case where the brake plate 71 has only one second valley 71b as the second valley corresponding to the non-parking position is shown, but a plurality of second valleys may be provided on the brake plate 71.

[0026] The first valley portion 71a and the second valley portion 71b are provided at the radially outer end portions of the brake plate 71. The first valley portion 71a and the second valley portion 71b are recessed downward from the upper end portion of the brake plate 71. The first valley portion 71a and the second valley portion 71b penetrate the brake plate 71 in the front-rear direction X. The first valley portion 71a and the second valley portion 71b are arranged circumferentially. In the present embodiment, the first valley portion 71a and the second valley portion 71b are arranged in the left-right direction Y. The first valley portion 71a is located on the other side (-Y side) in the left-right direction of the second valley portion 71b. By providing the first valley portion 71a and the second valley portion 71b on the brake plate 71, a ridge portion 71c protruding radially outward is provided in the portion between the first valley portion 71a and the second valley portion 71b in the circumferential direction of the brake plate 71.

[0027] The rod 72 is configured to be movable along the left-right direction Y. The rod 72 has a connecting portion 72a and a rod main body 72b. The connecting portion 72a is in the shape of a rod extending in the front-rear direction X. The end portion on the front-rear direction one side (+X side) of the connecting portion 72a penetrates the brake plate 71 in the front-rear direction X and is fixed to the brake plate 71. Thus, the rod 72 is connected to the output shaft 80 via the brake plate 71. The rod main body 72b is in the shape of a rod extending in the left-right direction Y. In the present embodiment, the rod main body 72b extends from the end portion on the other side (-X side) in the front-rear direction of the connecting portion 72a to the left-right direction one side (+Y side). The rod main body 72b has a protrusion portion 72c in a portion close to the connecting portion 72a. A cylindrical member 72d extending in the left-right direction Y is fitted and fixed to the end portion on the left-right direction one side of the rod main body 72b.

[0028] The conical member 73 is in a conical shape through which the rod main body 72b passes. The conical member 73 extends in the left-right direction Y. A portion on the left-right direction one side (+Y side) of the outer peripheral surface of the conical member 73 is a tapered surface 73a whose outer diameter becomes smaller as it faces the left-right direction one side. The conical member 73 is movable relative to the rod main body 72b in the left-right direction Y.

[0029] 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 portion 72c in the left-right direction Y. The rod main body 72b is inserted into the coil spring 74. The end portion on the left-right direction other side (-Y side) of the coil spring 74 contacts the protrusion portion 72c. The end portion on the left-right direction one side (+Y side) of the coil spring 74 contacts the surface on the other side in the left-right direction of the conical member 73. The coil spring 74 expands and contracts by the relative movement of the conical member 73 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.

[0030] The parking lock arm 77 is located on the other side (-X side) in the front-rear direction of the movable part 70a. The parking lock arm 77 is supported by a support shaft 78 centered on a rotation axis J2 extending in the left-right direction Y so as to be rotatable. The parking lock arm 77 has a parking lock arm main body 77a and an engagement part 77b.

[0031] The parking lock arm main body 77a extends from the support shaft 78 toward the front-rear direction side (+X side). The end 77c on the front-rear direction side of the parking lock arm main body 77a contacts the movable part 70a from above. The engagement part 77b projects upward from the parking lock arm main body 77a. A torsion spring (not shown) is mounted on the support shaft 78. The torsion spring (not shown) applies an elastic force in the clockwise direction when viewed from the other side (-Y side) in the left-right direction around the rotation axis J2 to the parking lock arm 77.

[0032] The parking lock arm 77 moves as the movable part 70a moves. More specifically, the parking lock arm 77 rotates around the rotation axis J2 as the rod 72 and the conical member 73 move in the left-right direction Y. When the brake plate 71 rotates from the non-parking position to the parking position as the output shaft 80 rotates, the rod 72 and the conical member 73 move to the left-right direction side (+Y side).

[0033] The outer diameter of the conical surface 73a of the conical member 73 increases as it goes from the left-right direction side (+Y side) toward the other side (-Y side) in the left-right direction. Therefore, when the conical member 73 moves to the left-right direction side, the end 77c of the parking lock arm 77 is lifted upward by the conical surface 73a, and the parking lock arm 77 rotates counterclockwise when viewed from the other side (-Y side) in the left-right direction around the rotation axis J2. As a result, although not shown, the engagement part 77b approaches the parking lock gear 6 and engages between the tooth parts 6a of the parking lock gear 6.

[0034] When the parking lock gear 6 and the parking lock arm 77 are engaged, the conical member 73 is also in a state of being located at the parking position, and the entire movable part 70a is in a state of being located at the parking position. That is, the parking lock arm 77 engages with the parking lock gear 6 connected to the axle when the movable part 70a is at the parking position. The conical member 73 is clamped in a state of being in contact with a contact part 75b (described later) in the support member 75 and the parking lock arm 77 at the parking position. By engaging the parking lock arm 77 with the parking lock gear 6, the parking lock gear 6 is in a locked state.

[0035] When the parking lock arm 77 approaches the parking lock gear 6, the engaging portion 77b sometimes contacts the tooth portion 6a according to the position of the tooth portion 6a of the parking lock gear 6. In this case, the parking lock arm 77 sometimes cannot move to the position where the engaging portion 77b engages between the tooth portions 6a. Even in such a case, in the present embodiment, since the conical member 73 can move in the left-right direction Y with respect to the rod 72, it is possible to allow the state where the conical member 73 is located on the other side (-Y side) in the left-right direction than the parking position while the rod 72 moves to the parking position. Thereby, it is possible to suppress the rotation of the output shaft 80 from being obstructed, and it is possible to suppress the application of a load to the motor unit 10 that rotates the output shaft 80.

[0036] In addition, in the state where the rod 72 is in the parking position and the conical member 73 is located on the other side (-Y side) in the left-right direction than the parking position, the coil spring 74 is in a state of being compressed and deformed. Therefore, an elastic force toward one side in the left-right direction (toward the +Y side) is applied to the conical member 73 by the coil spring 74. Thereby, a rotational torque in the counterclockwise direction when viewed from the other side (-Y side) in the left-right direction around the rotation axis J2 is applied from the coil spring 74 to the parking lock arm 77 via the conical member 73. Therefore, when the parking lock gear 6 rotates and the position of the tooth portion 6a is shifted, the parking lock arm 77 rotates so that the engaging portion 77b engages between the tooth portions 6a.

[0037] When the brake plate 71 rotates from the parking position to the non-parking position as the output shaft 80 rotates, the rod 72 and the conical member 73 move to the other side (-Y side) in the left-right direction. When the conical member 73 moves to the other side in the left-right direction, the end portion 77c of the parking lock arm 77 lifted by the conical member 73 moves downward due to its own weight and the elastic force of a torsion spring (not shown), so that the parking lock arm 77 rotates counterclockwise when viewed from one side (+Y side) in the left-right direction around the rotation axis J2. Thereby, the engaging portion 77b of the parking lock arm 77 separates from the parking lock gear 6 and disengages between the tooth portions 6a. In Figure 2 FIG. shows the parking lock arm 77 in a state of being disengaged from the parking lock gear 6.

[0038] When the parking lock arm 77 is disengaged from the parking lock gear 6, the conical member 73 is also in a state of being located in the non-parking position, and the entire movable portion 70a is in the non-parking position. That is, the parking lock arm 77 disengages from the parking lock gear 6 when the movable portion 70a is in the non-parking position. The conical member 73 is located on the other side (-Y side) in the left-right direction than the parking lock arm 77 in the non-parking position. By the parking lock arm 77 disengaging from the parking lock gear 6, the parking lock gear 6 becomes unlocked.

[0039] The support member 75 supports the movable portion 70a so as to be movable in the left - right direction Y. In the present embodiment, the support member 75 supports the movable portion 70a from below. The support member 75 is fixed to the inner side surface of the housing 2. The support member 75 has a base portion 75a, a contact portion 75b, and a leaf spring fixing portion 75c.

[0040] In the present embodiment, the base portion 75a is in the shape of a plate with its plate surface facing the vertical direction Z. The contact portion 75b projects upward from the base portion 75a. The contact portion 75b is the part that contacts the movable portion 70a to support the movable portion 70a. In the present embodiment, the contact portion 75b contacts the conical member 73 in the movable portion 70a from below and supports the movable portion 70a from below. The surface of the contact portion 75b on the side of the movable portion 70a is an arc - shaped curved surface that is recessed toward the side opposite to the movable portion 70a side when viewed along the left - right direction Y. Therefore, the conical member 73 having the conical surface 73a can be stably supported.

[0041] The leaf spring fixing portion 75c projects upward from the base portion 75a. The leaf spring fixing portion 75c is, for example, in the shape of a rectangular parallelepiped. The leaf spring fixing portion 75c is located at a position on the front - rear direction side (+X side) relative to the contact portion 75b. The leaf spring member 76 is fixed to the leaf spring fixing portion 75c of the support member 75. In the present embodiment, the leaf spring member 76 is fixed to the end portion on the other side (-Y side) in the left - right direction of the upper surface of the leaf spring fixing portion 75c. The leaf spring member 76 has a leaf spring main body portion 76a and a contacted portion 76b.

[0042] The leaf spring main body portion 76a is in the shape of a plate with its plate surface facing the vertical direction Z. The leaf spring main body portion 76a extends from the leaf spring fixing portion 75c to the other side (-Y side) in the left - right direction. The leaf spring main body portion 76a extends to the upper side of the brake plate 71. The leaf spring main body portion 76a has a slit 76c at the end portion on the other side in the left - right direction. The slit 76c penetrates the leaf spring main body portion 76a in the vertical direction Z. The slit 76c extends in the left - right direction Y. The slit 76c extends to the end portion on the other side in the left - right direction of the leaf spring main body portion 76a and divides the end portion on the other side in the left - right direction of the leaf spring main body portion 76a into two parts.

[0043] The contacted portion 76b is provided at the end portion on the other side (-Y side) in the left-right direction of the leaf spring main body portion 76a. In the present embodiment, the contacted portion 76b is a roller that is mounted on the leaf spring main body portion 76a so as to be rotatable about an axis extending in the front-rear direction X. The contacted portion 76b is provided between the front end portions of the leaf spring main body portion 76a that are divided into two by the slit 76c. The contacted portion 76b contacts either the first valley portion 71a or the second valley portion 71b by the elastic force generated in the leaf spring member 76 as the brake plate 71 rotates. When the movable portion 70a is in the parking position, the contacted portion 76b contacts the first valley portion 71a and is hooked on the inner side surface of the first valley portion 71a in the left-right direction Y. Thereby, the brake plate 71 and the rod 72 can be maintained in the parking position.

[0044] Particularly, in the case where the coil spring 74 is provided as in the present embodiment, the reaction force of the elastic force generated by the compression deformation of the coil spring 74 due to the engagement portion 77b contacting the tooth portion 6a is applied to the rod 72 and the brake plate 71 toward the other side in the left-right direction (toward the -Y side). According to the present embodiment, even in such a case, by hooking the contacted portion 76b on the first valley portion 71a, the movement of the brake plate 71 toward the other side in the left-right direction (-Y side) can be suppressed. Therefore, the brake plate 71 and the rod 72 can be stably maintained in the parking position.

[0045] On the other hand, when the brake plate 71 is moved from the parking position to the non-parking position by rotating the output shaft 80 by the motor unit 10, the leaf spring main body portion 76a is elastically deformed by being pressed upward by the peak portion 71c of the brake plate 71. Thereby, the contacted portion 76b is detached from the first valley portion 71a. When the movable portion 70a is in the non-parking position, the contacted portion 76b contacts the second valley portion 71b and is hooked on the inner side surface of the second valley portion 71b in the left-right direction Y. Thereby, the brake plate 71 and the rod 72 can be maintained in the non-parking position.

[0046] In the present embodiment, when the contacted portion 76b moves between the first valley portion 71a and the second valley portion 71b, the contacted portion 76b relatively moves from the inside of one valley portion over the peak portion 71c to the other valley portion. When the contacted portion 76b crosses over the peak portion 71c, the leaf spring member 76 is elastically deformed by the force directed upward from the peak portion 71c via the contacted portion 76b. That is, in the present embodiment, the leaf spring member 76 is an elastic member that is elastically deformed when the movable portion 70a moves between the non-parking position and the parking position by being pressed upward by the peak portion 71c of the brake plate 71. Thus, the leaf spring member 76 in the present embodiment is an elastic member having the contacted portion 76b, and the contacted portion 76b contacts any one of the plurality of valley portions by the elastic force generated in the leaf spring member 76 as the brake plate 71 rotates. Further, in the present embodiment, when the contacted portion 76b moves between the first valley portion 71a and the second valley portion 71b, the contacted portion 76b, which is a roller, moves in a rolling manner on the upper end surface of the brake plate 71.

[0047] The motor unit 10 drives the parking switching mechanism 70 according to a shift operation of the vehicle. In the present embodiment, the motor unit 10 drives the parking switching mechanism 70 by moving the movable portion 70a in the left-right direction Y via the output shaft 80, and switches the parking lock gear 6 between the locked state and the unlocked state.

[0048] As Figure 1 shown, the motor unit 10 includes a motor 20 and a speed reducer 30. The speed reducer 30 is connected to the motor 20. The motor 20 rotates the output shaft 80 via the speed reducer 30. The motor 20 is, for example, a three-phase brushless DC motor. The speed reducer 30 decelerates the rotation of the motor 20. The output shaft 80 is connected to the speed reducer 30. The rotation of the motor 20 decelerated by the speed reducer 30 is transmitted to the output shaft 80. That is, the output shaft 80 is driven by the motor 20 via the speed reducer 30.

[0049] As Figure 3 shown, in addition to the motor unit 10, the parking switching mechanism 70, and the output shaft 80, the electric actuator 100 further includes a first rotation sensor 51, a second rotation sensor 52, and a control unit 40. The control unit 40 is communicably connected to an upper control device 200 via a communication cable (not shown). The upper control device 200 is, for example, an ECU (Electronic Control Unit) mounted on the vehicle.

[0050] The first rotation sensor 51 detects a first rotation angle that is the rotation angle of the motor 20 The first rotation sensor 51 represents the first rotation angle The signal of the detection result is output to the control unit 40. The second rotation sensor 52 detects a second rotation angle θ which is the rotation angle of the output shaft 80. The second rotation sensor 52 outputs a signal representing the detection result of the second rotation angle θ to the control unit 40. The first rotation sensor 51 and the second rotation sensor 52 are, for example, Hall sensors, incremental encoders, or absolute encoders, etc. In the following description, the first rotation angle is sometimes referred to as the motor rotation angle, and the second rotation angle θ is referred to as the output shaft rotation angle.

[0051] The control unit 40 controls the motor 20 based on the detection results of the motor rotation angle and the output shaft rotation angle θ. The control unit 40 communicates with the upper control device 200 according to a specified communication protocol. The specified communication protocol is, for example, the CAN (Controller Area Network) communication protocol. The control unit 40 is, for example, a microprocessor such as an MCU (Microcontroller Unit). When the control unit 40 receives a shift position switching instruction from the upper control device 200, it executes Figure 4 the shift position switching process shown.

[0052] Figure 4 is a flowchart showing the shift position switching process executed by the control unit 40. As Figure 4 shown, when the control unit 40 receives a shift position switching instruction from the upper control device 200, the control unit 40 first obtains an output shaft target angle θt corresponding to the indicated shift position (step S1). For example, table data representing the correspondence between the shift position and the output shaft target angle θt is pre-stored in the internal memory of the control unit 40. The control unit 40 obtains the output shaft target angle θt corresponding to the indicated shift position by referring to the table data stored in the internal memory.

[0053] Next, the control unit 40 starts the position PID control of the motor 20 based on the output shaft target angle θt and the output shaft rotation angle θ detected by the second rotation sensor 52 (step S2). Specifically, the control unit 40 calculates an operation amount for making the deviation between the output shaft target angle θt and the output shaft rotation angle θ zero through PID operation, and supplies a drive current corresponding to the calculated operation amount to the motor 20, thereby rotating the motor 20. As a result, the output shaft 80 rotates right or left toward the output shaft target angle θt corresponding to the indicated shift position.

[0054] In the present embodiment, "the output shaft 80 rotates right" means that the output shaft 80 rotates clockwise around the central axis J1 when viewed from the front-rear direction side (+X side). That is, the right-handed direction is the same as Figure 2The direction opposite to the direction towards which the arrow indicating the rotation angle θ of the output shaft 80 points. In addition, in the present embodiment, "the output shaft 80 rotates counterclockwise" means that the output shaft 80 rotates counterclockwise about the central axis J1 when viewed from the front-rear direction side (+X side). That is, the left-handed direction is the same as the direction towards which the arrow indicating the rotation angle θ of the output shaft 80 points. Figure 2 The same direction as the direction towards which the arrow indicating the rotation angle θ of the output shaft 80 points.

[0055] For example, when the shift position before executing the shift position switching process is a non-parking position, the contact portion 76b of the leaf spring member 76 is located in the second valley portion 71b of the brake plate 71 before executing the shift position switching process. In this case, assuming that an instruction to switch to the parking position is issued from the upper control device 200, the control unit 40 calculates, by PID operation, the operation amount at which the deviation between the output shaft target angle θt corresponding to the parking position and the output shaft rotation angle θ becomes zero, and supplies the drive current corresponding to the calculated operation amount to the motor 20, thereby rotating the motor 20. As a result, the output shaft 80 rotates to the right towards the output shaft target angle θt corresponding to the parking position.

[0056] In this way, when the output shaft 80 rotates to the right towards the output shaft target angle θt corresponding to the parking position, the brake plate 71 sharing the central axis J1 with the output shaft 80 also rotates to the right towards the output shaft target angle θt corresponding to the parking position. When the brake plate 71 rotates to the right towards the output shaft target angle θt corresponding to the parking position, the leaf spring main body portion 76a is pressed upward by the peak portion 71c of the brake plate 71 and elastically deformed. Thus, as Figure 5 shown in "State A" of, the contact portion 76b detaches from the second valley portion 71b corresponding to the non-parking position and moves in a rolling manner from the second valley portion 71b towards the first valley portion 71a along the upper end surface of the brake plate 71. In addition, when the brake plate 71 rotates to the right towards the output shaft target angle θt corresponding to the parking position, the rod 72 and the conical member 73 move from the non-parking position towards the parking position along the left-right direction Y.

[0057] The control unit 40 determines whether the output shaft rotation angle θ detected by the second rotation sensor 52 satisfies the following conditional expression (1) while performing position PID control of the motor 20 (step S3). In other words, in step S3, the control unit 40 determines whether the output shaft rotation angle θ converges within a tolerance range with the output shaft target angle θt as the reference value and ±1° as the allowable error. In addition, in the following conditional expression (1), as an example, the allowable error is set to ±1°, but the value of the allowable error is not limited to ±1°.

[0058] θt - 1° ≤ θ ≤ θt + 1°…(1)

[0059] In the case where the answer in the above step S3 is "No", that is, when the output shaft rotation angle θ detected by the second rotation sensor 52 does not satisfy the conditional expression (1), the contacted portion 76b is inferred not to be within the range of ±1° centered on the valley portion corresponding to the indicated shift position among the plurality of valley portions of the brake plate 71. In this case, the control unit 40 performs position PID control of the motor 20 while repeating the process of step S3 at regular time intervals.

[0060] On the other hand, in the case where the answer in the above step S3 is "Yes", that is, when the output shaft rotation angle θ detected by the second rotation sensor 52 satisfies the conditional expression (1), the contacted portion 76b is inferred to be within the range of ±1° centered on the valley portion corresponding to the indicated shift position among the plurality of valley portions of the brake plate 71. In this case, the control unit 40 determines whether a predetermined time has elapsed in a state where the output shaft rotation angle θ satisfies the conditional expression (1) (step S4). In other words, in step S4, the control unit 40 determines whether a predetermined time has elapsed in a state where the contacted portion 76b is within the range of ±1° centered on the valley portion corresponding to the indicated shift position. As an example, the predetermined time in step S4 is 20 milliseconds, but the predetermined time is not limited to 20 milliseconds.

[0061] For example, as described above, when the indicated shift position is the parking position and the brake plate 71 continues to rotate to the right toward the output shaft target angle θt corresponding to the parking position, as Figure 5 shown in "State B", the contacted portion 76b crosses over the ridge portion 71c of the brake plate 71 and enters the range of ±1° centered on the first valley portion 71a corresponding to the parking position. Thus, when the contacted portion 76b enters the range of ±1° centered on the first valley portion 71a, that is, when the output shaft rotation angle θ detected by the second rotation sensor 52 satisfies the conditional expression (1), the control unit 40 starts timing and determines whether a predetermined time has elapsed in a state where the contacted portion 76b is within the range of ±1° centered on the first valley portion 71a.

[0062] In the case where the answer in the above step S4 is "No", that is, when the predetermined time has not elapsed in a state where the output shaft rotation angle θ satisfies the conditional expression (1), the control unit 40 repeats the process of step S4 at regular time intervals until the predetermined time elapses. On the other hand, in the case where the answer in the above step S4 is "Yes", that is, when the predetermined time has elapsed in a state where the output shaft rotation angle θ satisfies the conditional expression (1), the control unit 40 stops supplying the drive current to the motor 20 by stopping the position PID control of the motor 20 (step S5).

[0063] When the supply of drive current to the motor 20 is stopped, the torque of the motor 20 becomes zero, so the output shaft 80 and the brake plate 71 are in a state where they can rotate freely. On the other hand, the leaf spring main body portion 76a is pressed upward by the mountain portion 71c of the brake plate 71 and elastically deformed, thereby generating a downward elastic force that presses the contacted portion 76b against the upper end surface of the brake plate 71. Therefore, if the contacted portion 76b is within the range of ±1° centered on the valley portion corresponding to the indicated shift position and the brake plate 71 is in a state where it can rotate freely, the brake plate 71 rotates by means of the downward elastic force generated in the leaf spring main body portion 76a. As a result, the contacted portion 76b moves in a rolling manner along the upper end surface of the brake plate 71 toward the valley portion.

[0064] For example, as described above, when the indicated shift position is the parking position, as Figure 5 shown in "State B" of, if the contacted portion 76b is within the range of ±1° centered on the first valley portion 71a corresponding to the parking position and the brake plate 71 is in a state where it can rotate freely, the brake plate 71 rotates to the right by means of the downward elastic force generated in the leaf spring main body portion 76a. As a result, as Figure 5 shown in "State C" of, the contacted portion 76b moves in a rolling manner along the upper end surface of the brake plate 71 toward the first valley portion 71a.

[0065] After stopping the supply of drive current to the motor 20, the control unit 40 determines whether the output shaft rotation angle θ detected by the second rotation sensor 52 satisfies the following conditional expression (2) (step S6). In other words, in step S6, the control unit 40 determines whether the output shaft rotation angle θ converges within a tolerance range with the output shaft target angle θt as the reference value and ±2° as the allowable error. In addition, in the following conditional expression (2), as an example, the allowable error is set to ±2°, but the value of the allowable error is not limited to ±2°. However, for reasons described later, the allowable error in the conditional expression (2) is preferably set to a value larger than the allowable error in the conditional expression (1).

[0066] θt - 2° ≤ θ ≤ θt + 2°…(2)

[0067] If the result in the above step S6 is "no", that is, if the output shaft rotation angle θ detected by the second rotation sensor 52 does not satisfy the conditional expression (2), it is inferred that the contacted portion 76b is not within the range of ±2° centered on the valley portion corresponding to the indicated shift position among the multiple valley portions of the brake plate 71. In this case, the control unit 40 returns to the process of step S2 and starts the position PID control of the motor 20 again.

[0068] As described above, when the drive current supply to the motor 20 is stopped, the output shaft 80 and the brake plate 71 are in a state where they can rotate freely. Therefore, after the drive current supply to the motor 20 is stopped, the brake plate 71 rotates significantly by the downward elastic force generated in the leaf spring main body portion 76a, and the contact portion 76b may move to a position significantly deviated from the valley portion corresponding to the indicated shift position. Therefore, when the rotation angle θ of the output shaft after the drive current supply to the motor 20 is stopped does not satisfy the conditional expression (2), that is, when it is inferred that the contact portion 76b has moved to a position significantly deviated from the valley portion corresponding to the indicated shift position due to the stop of the drive current supply to the motor 20, the control unit 40 retries the switching of the shift position by restarting the position PID control of the motor 20. The reason why the allowable error in the conditional expression (2) is set to a value larger than the allowable error in the conditional expression (1) is to accurately detect the situation where the contact portion 76b has moved to a position significantly deviated from the valley portion corresponding to the indicated shift position due to the stop of the drive current supply to the motor 20.

[0069] On the other hand, when the answer in the above step S6 is "Yes", that is, when the rotation angle θ of the output shaft detected by the second rotation sensor 52 satisfies the conditional expression (2), it is inferred that the contact portion 76b is located within ±2° of the valley portion corresponding to the indicated shift position among the plurality of valley portions of the brake plate 71. In this case, the control unit 40 determines whether a predetermined time has elapsed in a state where the rotation angle θ of the output shaft satisfies the conditional expression (2) (step S7). In other words, in step S7, the control unit 40 determines whether a predetermined time has elapsed in a state where the contact portion 76b is located within ±2° of the valley portion corresponding to the indicated shift position. As an example, the predetermined time in step S7 is 20 milliseconds, but the predetermined time is not limited to 20 milliseconds.

[0070] For example, as described above, when the indicated shift position is the parking position, as Figure 5 shown in "State C", if the drive current supply to the motor 20 is stopped while the contact portion 76b is within ±1° of the first valley portion 71a corresponding to the parking position, the brake plate 71 rotates to the right by the downward elastic force generated in the leaf spring main body portion 76a. As a result, the contact portion 76b moves in a rolling manner along the upper end face of the brake plate 71 toward the first valley portion 71a. And, as Figure 5As shown in "State D", when the contacted portion 76b reaches the first valley portion 71a, the contacted portion 76b is hooked on the inner side surface of the first valley portion 71a in the left - right direction Y, and thus the brake plate 71 stops. As a result, the brake plate 71 and the movable portion 70a (lever 72, conical member 73) are in a state of being located at the parking position, and the parking lock gear 6 is locked by the parking lock arm 77.

[0071] That is, after stopping the supply of the drive current to the motor 20, by determining whether a predetermined time has elapsed in a state where the output shaft rotation angle θ satisfies the conditional expression (2), it is possible to determine whether the brake plate 71 and the movable portion 70a are in a state of being located at the indicated shift position.

[0072] In the case where the answer in the above - mentioned step S7 is "no", that is, in the case where the predetermined time has not elapsed in a state where the output shaft rotation angle θ satisfies the conditional expression (2), it is inferred that the contacted portion 76b has not reached the valley portion corresponding to the indicated shift position, and the brake plate 71 and the movable portion 70a are not in a state of being located at the indicated shift position. In this case, the control unit 40 repeats the process of step S7 at a certain time interval until the predetermined time has elapsed.

[0073] On the other hand, in the case where the answer in the above - mentioned step S7 is "yes", that is, in the case where the predetermined time has elapsed in a state where the output shaft rotation angle θ satisfies the conditional expression (2), it is inferred that the contacted portion 76b has reached the valley portion corresponding to the indicated shift position, and the brake plate 71 and the movable portion 70a are also in a state of being located at the indicated shift position. In this case, the control unit 40 determines that the switching of the shift position has ended, and notifies the upper - level control device 200 that the switching of the shift position has ended (step S8).

[0074] The above is the description of the shift - position switching process executed by the control unit 40. However, as can be understood from the above description, in the case of an abnormality such as a failure of the second rotation sensor 52, the output shaft rotation angle θ cannot be detected, and thus the control unit 40 cannot execute the shift - position switching process. Therefore, for example, when the control unit 40 detects an abnormality of the second rotation sensor 52 by performing an initial process at startup in the present embodiment, it notifies the upper - level control device 200 of the abnormality of the second rotation sensor 52. Then, when the control unit 40 receives a parking - position learning instruction from the upper - level control device 200, it executes Figure 6 the parking - position learning process shown. The parking - position learning process is a process of learning the motor rotation angle corresponding to the parking position as the parking - position angle.

[0075] Figure 6 is a flowchart showing the parking - position learning process executed by the control unit 40. AsFigure 6 As shown in Figure 6 , when the control unit 40 receives a parking position learning instruction from the host control device 200, it first performs the following processing: by starting the position PID control of the motor 20, the motor 20 is rotated so that the contacted portion 76b abuts against the first side wall portion 71d located on the circumferential one end side of the first valley portion 71a in the brake plate 71 (step S11). In the following description, the first side wall portion 71d is sometimes referred to as the "P side wall".

[0076] For example, a side wall target angle is pre-stored in the internal memory of the control unit 40 This side wall target angle is the target value of the motor rotation angle required for the contacted portion 76b to abut against the P side wall 71d In step S11, the control unit 40 calculates, by PID operation, the deviation between the side wall target angle stored in the internal memory and the motor rotation angle detected by the first rotation sensor 51 to be zero, and supplies a drive current corresponding to the calculated operation amount to the motor 20, thereby rotating the motor 20. As a result, the output shaft 80 and the brake plate 71 rotate in the direction in which the contacted portion 76b moves toward the P side wall 71d, that is, rotate to the right.

[0077] In addition, in the present embodiment, the motor 20 is connected to the output shaft 80 via the reduction gear 30. Therefore, the motor rotation angle which is the rotation angle of the motor 20 is inconsistent with the output shaft rotation angle θ which is the rotation angle of the output shaft 80 and the brake plate 71. Therefore, in order to control the output shaft rotation angle θ by the position PID control of the motor 20 based on the motor rotation angle it is necessary to convert the motor rotation angle and the side wall target angle which is its target value into the output shaft rotation angle θ. Hereinafter, for the sake of simplicity of description, it is assumed that the motor rotation angle is consistent with the output shaft rotation angle θ. That is, in the following description, the control unit 40 does not need to convert the motor rotation angle etc. into the output shaft rotation angle θ.

[0078] As Figure 7 shown in "state E", when the brake plate 71 rotates to the right, the contacted portion 76b moves in a rolling manner along the upper end surface of the brake plate 71 toward the P side wall 71d. Then, when a predetermined time has elapsed since the brake plate 71 started rotating to the right, as Figure 7As shown in the "State F", the contact portion 76b abuts against the P side wall 71d, and the brake plate 71 stops. That is, when the contact portion 76b abuts against the P side wall 71d, the motor 20 is in a non-rotatable state (locked state).

[0079] The control unit 40 performs position PID control of the motor 20 according to the motor rotation angle while determining whether the motor 20 is in a locked state according to the motor rotation angle detected by the first rotation sensor 51 (step S12). For example, when the motor rotation angle detected by the first rotation sensor 51 does not change, or when the change in the motor rotation angle becomes extremely small, etc., it is determined that the motor 20 is in a locked state.

[0080] If the result in step S12 is "no", that is, when the motor 20 is not in a locked state, it is inferred that the contact portion 76b does not abut against the P side wall 71d. In this case, the control unit 40 performs position PID control of the motor 20 while repeating the process of step S12 at regular time intervals.

[0081] On the other hand, if the result in step S12 is "yes", that is, when the motor 20 is in a locked state, it is inferred that the contact portion 76b abuts against the P side wall 71d. In this case, the control unit 40 performs the following process: when the contact portion 76b abuts against the P side wall 71d, it obtains the motor rotation angle detected by the first rotation sensor 51 as the side wall position angle (step S13).

[0082] When the control unit 40 obtains the side wall position angle as described above , it performs a reverse rotation process of rotating the motor 20 in the reverse direction from the side wall position angle to an angle corresponding to the target rotation angle (step S14). In the present embodiment, the target rotation angle is obtained by subtracting the design value of the rotation angle from the P side wall 71d to the first valley portion 71a (motor rotation angle ) from the side wall position angle. In step S14, the control unit 40 calculates the target rotation angle through PID operation and the motor rotation angle detected by the first rotation sensor 51 ​​​The operation amount that makes the deviation zero is obtained, and a drive current corresponding to the calculated operation amount is supplied to the motor 20, thereby rotating the motor 20 in the reverse direction. As a result, the output shaft 80 and the brake plate 71 rotate in the direction in which the contact portion 76b moves from the P side wall 71d to the first valley portion 71a, that is, rotate to the left.

[0083] As Figure 7 shown in "State G", after the contact portion 76b abuts against the P side wall 71d, when the brake plate 71 rotates to the left, the contact portion 76b moves in a rolling manner along the upper end surface of the brake plate 71 from the P side wall 71d toward the first valley portion 71a.

[0084] The control unit 40 performs position PID control of the motor 20 based on the motor rotation angle while determining whether the motor rotation angle detected by the first rotation sensor 51 satisfies the following conditional expression (3) (step S15). In other words, in step S15, the control unit 40 determines whether the motor rotation angle converges within a second tolerance range with the target rotation angle as the reference value and ±α as the allowable error. As an example, the value of α is 1°, but the value of α is not limited to 1°.

[0085]

[0086] If the result in the above step S15 is "no", that is, if the motor rotation angle detected by the first rotation sensor 51 does not satisfy the conditional expression (3), it is inferred that the contact portion 76b is not within the range of ±α centered on the first valley portion 71a corresponding to the parking position. In this case, the control unit 40 performs position PID control of the motor 20 while repeating the process of step S15 at regular time intervals.

[0087] On the other hand, if the result in the above step S15 is "yes", that is, if the motor rotation angle detected by the first rotation sensor 51 satisfies the conditional expression (3), it is inferred that the contact portion 76b is within the range of ±α centered on the first valley portion 71a corresponding to the parking position. In this case, the control unit 40 determines whether the second specified time has elapsed in a state where the motor rotation angle satisfies the conditional expression (3) (step S16). In other words, in step S16, the control unit 40 determines whether the second specified time has elapsed in a state where the contact portion 76b is within the range of ±α centered on the first valley portion 71a corresponding to the parking position. As an example, the second specified time in step S16 is 10 milliseconds, but the second specified time is not limited to 10 milliseconds.

[0088] As Figure 7 shown in “State G” of Figure 7 , after the contacted portion 76b comes into contact with the P side wall 71d, if the brake plate 71 continues to rotate leftward, the contacted portion 76b intrudes into the range of ±α centered on the first valley portion 71a corresponding to the parking position. Thus, when the contacted portion 76b intrudes into the range of ±α centered on the first valley portion 71a corresponding to the parking position, that is, when the motor rotation angle detected by the first rotation sensor 51 satisfies the conditional expression (3), the control unit 40 starts timing and determines whether the second specified time has elapsed while the contacted portion 76b is within the range of ±α centered on the first valley portion 71a.

[0089] In the case where the answer in the above step S16 is “No”, that is, when the second specified time has not elapsed in the state where the motor rotation angle satisfies the conditional expression (3), the control unit 40 repeats the process of step S16 at regular time intervals until the second specified time elapses. On the other hand, in the case where the answer in the above step S16 is “Yes”, that is, when the second specified time has elapsed in the state where the motor rotation angle satisfies the conditional expression (3), the control unit 40 stops supplying the drive current to the motor 20 by stopping the position PID control of the motor 20 (step S17).

[0090] Thus, after the control unit 40 executes the reverse rotation process, it executes the following process: when the motor rotation angle detected by the first rotation sensor 51 continuously converges within the second tolerance with respect to the target rotation angle as the reference value within the second specified time, the control of the motor 20 is stopped. In addition, after the control unit 40 stops the control of the motor 20, it executes the stationary determination process described later, and the detailed content will be described later.

[0091] When the supply of the drive current to the motor 20 is stopped, the torque of the motor 20 becomes zero, so the output shaft 80 and the brake plate 71 are in a state where they can rotate freely. On the other hand, the leaf spring main body portion 76a is elastically deformed by being pressed upward by the peak portion 71c of the brake plate 71, thereby generating a downward elastic force that presses the contacted portion 76b against the upper end surface of the brake plate 71. Therefore, as Figure 7 shown in “State H” of Figure 7 , if the contacted portion 76b is within the range of ±α centered on the first valley portion 71a and the brake plate 71 is in a state where it can rotate freely, the brake plate 71 rotates rightward by the downward elastic force generated in the leaf spring main body portion 76a. As a result, as Figure 7As shown in "State I", the contacted portion 76b moves in a rolling manner along the upper end surface of the brake plate 71 toward the first valley portion 71a.

[0092] After stopping the supply of drive current to the motor 20, the control unit 40 determines the motor rotation angle detected by the first rotation sensor 51 to check if it satisfies the following conditional expression (4) (step S18). In other words, in step S18, the control unit 40 determines whether the motor rotation angle converges within the first tolerance range with the target rotation angle as the reference value and ±β as the allowable error. As an example, the value of β is 2°, but the value of β is not limited to 2°. However, for reasons described later, the first tolerance is preferably larger than the second tolerance In other words, the allowable error β of the first tolerance is preferably larger than the allowable error α of the second tolerance.

[0093]

[0094] In the case where the answer in the above step S18 is "no", that is, when the motor rotation angle detected by the first rotation sensor 51 does not satisfy the conditional expression (4), it is inferred that the contacted portion 76b is not within the range of ±β centered on the first valley portion 71a corresponding to the parking position. In this case, the control unit 40 returns to the process of step S11 and performs again the process of bringing the contacted portion 76b into contact with the P side wall 71d.

[0095] As described above, when the supply of drive current to the motor 20 is stopped, the output shaft 80 and the brake plate 71 are in a state where they can rotate freely. Therefore, after stopping the supply of drive current to the motor 20, the brake plate 71 rotates significantly by the downward elastic force generated in the leaf spring main body portion 76a, and the contacted portion 76b may move to a position significantly deviated from the first valley portion 71a corresponding to the parking position. Therefore, when the motor rotation angle does not satisfy the conditional expression (4) after stopping the supply of drive current to the motor 20, that is, when it is inferred that the contacted portion 76b has moved to a position significantly deviated from the first valley portion 71a due to the stop of the supply of drive current to the motor 20, the control unit 40 performs again the process of bringing the contacted portion 76b into contact with the P side wall 71d, thereby retrying the learning process of the parking position. The reason why the first tolerance is preferably larger than the second tolerance is to accurately detect the situation where the contacted portion 76b has moved to a position significantly deviated from the first valley portion 71a due to the stop of the supply of drive current to the motor 20.

[0096] On the other hand, in the case where the answer in the above step S18 is "yes", that is, when the motor rotation angle detected by the first rotation sensor 51 When conditional expression (4) is satisfied, it is estimated that the contacted portion 76b is located within the range of ±β centered at the first valley portion 71a. In this case, the control unit 40 determines that the motor rotation angle Whether the first prescribed time has passed under the condition that conditional expression (4) is satisfied (step S19). In other words, in step S19, the control unit 40 determines whether the first prescribed time has passed under the condition that the contacted portion 76b is located within the range of ±β centered on the first valley portion 71a. As an example, the first prescribed time in step S19 is 20 milliseconds, but the first prescribed time is not limited to 20 milliseconds. It is preferred that the first prescribed time is longer than the second prescribed time.

[0097] like Figure 7 As shown in "State H" of FIG. 1 , if the brake plate 71 is in a state where it can rotate freely while the contact portion 76b is located within the range of ±α centered on the first valley portion 71a, the brake plate 71 rotates to the right due to the downward elastic force generated by the leaf spring main body 76a. As a result, Figure 7 As shown in "State I" of FIG. 7 , the contacted portion 76b moves in a rolling manner along the upper end surface of the brake plate 71 toward the first valley portion 71a. Then, when the contacted portion 76b reaches the first valley portion 71a, the contacted portion 76b is hooked on the inner side surface of the first valley portion 71a in the left-right direction Y, thereby stopping the brake plate 71. As a result, the brake plate 71 and the movable portion 70a (rod 72, conical member 73) are in the parking position, and the parking lock gear 6 is locked by the parking lock arm 77.

[0098] That is, after the supply of the driving current to the motor 20 is stopped, by determining whether the motor 20 is rotated at an angle of Whether the first predetermined time has passed under the condition that conditional expression (4) is satisfied can determine whether the brake plate 71 and the movable portion 70a are in the parking position. In addition, by making the first predetermined time longer than the second predetermined time, sufficient time can be ensured for the contacted portion 76b to move to the first valley portion 71a, so that it can be determined with higher accuracy that the contacted portion 76b reaches the first valley portion 71a and the brake plate 71 and the movable portion 70a are in the parking position.

[0099] If the answer in step S19 is "No", that is, when the motor rotation angle is When the first predetermined time has not passed while conditional expression (4) is satisfied, it is inferred that the contacted portion 76b has not reached the first valley portion 71a corresponding to the parking position, and the brake plate 71 and the movable portion 70a are not in the parking position. In this case, the control unit 40 repeats the process of step S19 at a certain time interval until the first predetermined time has passed.

[0100] On the other hand, in the case where the determination in step S19 is "Yes", that is, when the motor rotation angle has passed the first specified time in a state where the condition of expression (4) is satisfied, it is inferred that the contacted portion 76b has reached the first valley portion 71a corresponding to the parking position, and the brake plate 71 and the movable portion 70a are also in a state of being located at the parking position. In this case, the control unit 40 determines that the contacted portion 76b is stationary at the parking position, and at this time, acquires (learns) the motor rotation angle detected by the first rotation sensor 51 as the parking position angle (step S20). In this way, the control unit 40 performs the following stationary determination process: when the motor rotation angle continuously converges within the first tolerance range with the target rotation angle as the reference value within the first specified time, it is determined that the contacted portion 76b is stationary at the parking position.

[0101] As described above, when an abnormality occurs in the second rotation sensor 52, the control unit 40 performs the parking position learning process, thereby learning the motor rotation angle corresponding to the parking position as the reference position as the parking position angle. When the control unit 40 receives a shift position switching instruction from the upper control device 200, based on the parking position angle obtained through the parking position learning process and the motor rotation angle detected by the first rotation sensor 51, the control unit 40 performs position PID control of the motor 20, thereby performing the switching of the shift position. As long as the motor rotation angle is inconsistent with the output shaft rotation angle θ, it is only necessary to perform a process of converting the parking position angle and the motor rotation angle into the output shaft rotation angle θ.

[0102] As described above, in the present embodiment, when an abnormality occurs in the second rotation sensor 52, the control unit 40 performs the following processes: a process of rotating the motor 20 to bring the contacted portion 76b into contact with the P side wall 71d of the brake plate 71; when the contacted portion 76b comes into contact with the P side wall 71d, acquiring the motor rotation angle detected by the first rotation sensor 51 as the side wall position angle ; a reverse rotation process of reversely rotating the motor 20 from the side wall position angle to an angle corresponding to the motor rotation angle equal to the target rotation angle ; and a stationary determination process, when the motor rotation angle continuously converges within the first tolerance range with the target rotation angle within the first specified time When within the first tolerance with respect to the reference value, it is determined that the contacted portion 76b is stationary at the parking position.

[0103] According to the present embodiment, even when an abnormality occurs in the second rotation sensor 52 that detects the rotation angle θ of the output shaft, it is possible to accurately determine, based on the motor rotation angle detected by the first rotation sensor 51, that the contacted portion 76b is stationary at the first valley portion corresponding to the parking position among the plurality of valley portions provided in the brake plate 71. When it is determined that the contacted portion 76b is stationary at the parking position, by learning the motor rotation angle detected by the first rotation sensor 51 as the parking position angle, it is possible to improve the learning accuracy of the parking position angle corresponding to the parking position as the reference position.

[0104] In the present embodiment, after performing the reverse rotation process, the control unit 40 performs a process of stopping the control of the motor 20 when the motor rotation angle detected by the first rotation sensor 51 continues to converge within the second tolerance with respect to the target rotation angle as the reference value within the second specified time, and performs the above-described stationary determination process after stopping the control of the motor 20. Thus, since it is determined through two-stage determination that the contacted portion 76b is stationary at the parking position, it is possible to more accurately determine that the contacted portion 76b is stationary at the first valley portion 71a corresponding to the parking position.

[0105] In the present embodiment, the first tolerance is greater than the second tolerance Accordingly, it is possible to accurately detect a situation where the supply of drive current to the motor 20 is stopped due to the stop of the control of the motor 20, and the contacted portion 76b moves to a position significantly deviated from the first valley portion 71a corresponding to the parking position.

[0106] In the present embodiment, the first specified time is longer than the second specified time.

[0107] Accordingly, it is possible to more accurately determine, based on the motor rotation angle detected by the first rotation sensor 51, that the contacted portion 76b is stationary at the first valley portion 71a corresponding to the parking position among the plurality of valley portions provided in the brake plate 71.

[0108] In the present embodiment, the target rotation angle is a design value obtained by subtracting the rotation angle from the P side wall 71d to the first valley portion 71a (motor rotation angle ) from the side wall position angle The obtained value. Thus, it is possible to more accurately determine that the contacted portion 76b is stationary at the first valley portion 71a corresponding to the parking position among the plurality of valley portions provided in the brake plate 71 based on the motor rotation angle detected by the first rotation sensor 51. And more accurately determine that the contacted portion 76b is stationary at the first valley portion 71a corresponding to the parking position among the plurality of valley portions provided in the brake plate 71.

[0109] The present invention is not limited to the above-described embodiments, and the respective structures described in this specification can be appropriately combined within a range where they do not contradict each other.

Claims

1. An electric actuator that switches the shift position, wherein, The electric actuator has: a motor; an output shaft driven by the motor; a brake plate fixed to the output shaft, having a plurality of valleys, the plurality of valleys including a first valley corresponding to a parking position provided on one circumferential end side and a second valley corresponding to a non-parking position provided on the other circumferential end side; an elastic member having a contact portion that contacts any one of the valleys by an elastic force generated on the elastic member as the brake plate rotates; a first rotation sensor that detects a first rotation angle that is the rotation angle of the motor; a second rotation sensor that detects a second rotation angle that is the rotation angle of the output shaft; and a control unit that controls the motor based on the detection results of the first rotation angle and the second rotation angle. When an abnormality occurs in the second rotation sensor, the control unit performs the following processing: a process of rotating the motor to bring the contact portion into contact with a first side wall portion of the brake plate located on the one circumferential end side of the first valley; a process of obtaining the first rotation angle detected by the first rotation sensor as a side wall position angle when the contact portion contacts the first side wall portion; a reverse rotation process of reversely rotating the motor to an angle at which the first rotation angle corresponds to a target rotation angle based on the side wall position angle; and a stationary determination process of determining that the contact portion is stationary at the parking position when the first rotation angle detected by the first rotation sensor continuously converges within a first tolerance with the target rotation angle as a reference value within a first specified time.

2. The electric actuator according to claim 1, wherein, After performing the reverse rotation process, the control unit performs the following processing: when the first rotation angle detected by the first rotation sensor continuously converges within a second tolerance with the target rotation angle as a reference value within a second specified time, the control of the motor is stopped. After stopping the control of the motor, the stationary determination process is performed.

3. The electric actuator according to claim 2, wherein, The first tolerance is larger than the second tolerance.

4. The electric actuator according to claim 2, wherein, The first specified time is longer than the second specified time.

5. The electric actuator according to claim 3, wherein, The first specified time is longer than the second specified time.

6. The electric actuator according to any one of claims 1 to 5, wherein, The target rotation angle is a value obtained by subtracting a designed value of the rotation angle from the first side wall portion to the first valley from the side wall position angle.

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