JP2019058032A - Electric actuator - Google Patents

Abstract

To provide an electric actuator capable of exhibiting a high braking force even at a location where vibration occurs.SOLUTION: In an electric actuator that comprises a motor part 2 and a motion conversion mechanism for converting rotational motion of the motor part 2 into linear motion, the motion conversion mechanism is configured by a sliding screw mechanism 3 having a screw shaft 14 and a nut 15 screwed into the screw shaft 14. The electric actuator is provided with a reverse-input blocking clutch 4 for preventing rotation in both normal and reverse directions of the sliding screw mechanism 3 to a reverse input from an output side opposite to the motor part 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric actuator.

  In recent years, electrification has progressed to save power and reduce fuel consumption of vehicles, etc., for example, a system for operating an automatic transmission, brakes, steering, etc. of an automobile with the power of an electric motor has been developed and put on the market. . As an actuator used for such an application, an electric linear actuator using a ball screw mechanism that converts a rotary motion of an electric motor into a linear motion is known (see Patent Documents 1 and 2).

Japanese Patent Laying-Open No. 2015-75200 JP2015-86931A

  The ball screw mechanism has an advantage that the power transmission efficiency (positive efficiency) when the rotary motion from the motor is converted into a linear motion and transmitted is very good. However, since the reverse efficiency, that is, the power transmission efficiency when converting linear motion into rotational motion is also good, in an electric actuator using a ball screw mechanism, a straight line from the operation target side (output side) to the ball screw mechanism. When a load in the movement direction is applied, the ball screw mechanism rotates, and it is difficult to maintain the braking state of the output shaft (ball screw shaft).

  On the other hand, the slide screw mechanism has a feature that both the normal efficiency and the reverse efficiency are generally lower than those of the ball screw mechanism. In particular, when the lead angle of the thread portion is reduced (for example, when the lead angle is 0 to 5 °), the reverse efficiency is 0%, that is, the self-locking function that does not rotate even if there is reverse input from the output side works. . Therefore, by using the sliding screw mechanism having such a property for the electric actuator, the braking force against the reverse input can be increased.

  However, if vibrations generated by the engine, the vehicle body during travel, etc. are transmitted to the sliding screw mechanism, the nuts of the sliding screw mechanism may gradually reversely rotate due to the vibrations, and it may not be possible to maintain a high braking force. It was.

  Accordingly, an object of the present invention is to provide an electric actuator that can exhibit a high braking force even in a place where vibration occurs.

  In order to solve the above-described problems, the present invention provides an electric actuator including a motor unit and a motion conversion mechanism that converts a rotational motion of the motor unit into a linear motion, and the motion conversion mechanism includes a screw shaft and a nut that is screwed to the screw shaft. And a reverse input shut-off clutch that prevents the sliding screw mechanism from rotating in both forward and reverse directions against reverse input from the output side opposite to the motor unit.

  As described above, the electric actuator according to the present invention uses a sliding screw mechanism having a higher braking force with respect to reverse input than the ball screw mechanism as the motion conversion mechanism, and further includes a reverse input cutoff clutch. Even when the energization is stopped (when stopped), the sliding screw mechanism can be highly prevented from rotating with respect to the reverse input from the output side. In addition, the reverse input cutoff clutch prevents not only rotation in one direction but also rotation in both forward and reverse directions with respect to the reverse input. Therefore, even if vibration is transmitted to the electric actuator, the reverse input cutoff clutch is locked (sliding screw mechanism). The rotation prevention state) can be reliably maintained. Thereby, the position of the slide screw mechanism can be maintained when restarting, and an electric actuator capable of accurate position control can be provided.

  As the reverse input cutoff clutch, an input member that is rotated by input from the motor unit, an output member that rotates with the rotation of the input member and outputs the rotational force to the sliding screw mechanism, and is fixed so as not to rotate. When the drive is input from the motor unit, the stationary input member is disengaged from the stationary member and the output member by the rotating input member to allow the output member to rotate. It is possible to employ one having a lock member that engages with the output member and prevents the output member from rotating in both forward and reverse directions.

  Moreover, when providing the reduction gear which decelerates and transmits the rotational motion of a motor part, it is preferable to arrange | position a reverse input interruption | blocking clutch on the output side rather than a reduction gear.

  In the reverse input cutoff clutch, when the engagement state (locked state) of the lock member is released, if the output member receives the reverse input and rotates in the same direction as the input member and faster than the input member, the lock member again A phenomenon called “catch-up lock” that engages between the output member and the stationary member may occur. At this time, abnormal noise (vibration) is generated by repeatedly engaging and releasing the lock member. However, as described above, the reverse input cut-off clutch is arranged on the output side of the speed reducer, so that the reverse input cut-off clutch of the reverse input cut-off clutch is conversely arranged on the input side of the speed reducer. The difference in rotational speed between the input member and the output member can be reduced, and abnormal noise (vibration) when a catch-up lock occurs can be reduced.

  The output member and the nut of the sliding screw mechanism may be integrally formed.

  Thus, by integrally molding the output member and the nut, these assembling operations become unnecessary, and the manufacturing cost can be reduced.

  The surface of at least one of the threaded shaft of the sliding screw mechanism and the nut may be coated with a slidable resin to improve the power transmission efficiency of the sliding screw mechanism.

  In addition, by arranging the screw shaft of the sliding screw mechanism on the inner diameter side of the motor unit and the reverse input shut-off clutch, the inner diameter side space is used as the screw shaft arrangement space, and the axial dimension of the electric actuator is small. It is possible to ensure a long maximum movement distance in the axial direction of the screw shaft while achieving a reduction in size.

  According to the present invention, it is possible to provide an electric actuator having a high braking force against reverse input even when used in a place where vibration occurs.

It is a longitudinal cross-sectional view of the electric actuator which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the reverse input interruption | blocking clutch seen by the AA line of FIG. It is a figure which shows the locked state of a reverse input interruption | blocking clutch. It is a figure which shows the lock release state of a reverse input interruption | blocking clutch. It is a figure which shows the state in which torque transmission is performed by the reverse input interruption | blocking clutch. It is a longitudinal cross-sectional view of the electric actuator which concerns on the other real form of this invention. It is a longitudinal cross-sectional view of the speed reducer which looked at the BB line of FIG. (A) is a figure for demonstrating the speed difference of the input rotation speed from the motor part side, and the reverse input rotation speed from an output side in case the rotation after deceleration is input with respect to a reverse input interruption | blocking clutch. (B) is a figure for demonstrating the said speed difference in case the rotation before deceleration is input with respect to a reverse input interruption | blocking clutch.

  Hereinafter, the present invention will be described with reference to the accompanying drawings. In the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description will be given. Omitted.

  FIG. 1 is a longitudinal sectional view of an electric actuator according to an embodiment of the present invention.

  An electric actuator 1 shown in FIG. 1 includes a motor unit 2, a sliding screw mechanism 3 as a motion conversion mechanism that converts a rotational motion of the motor unit 2 into a linear motion, and a reverse input from the output side opposite to the motor unit 2. The reverse input cut-off clutch 4 that cuts off the torque is mainly configured.

  The motor unit 2 includes an electric motor including a stator 5 and a rotor 6 and a motor case 7 that houses the electric motor. The motor case 7 is divided into two parts for the convenience of assembly. A cylindrical case main body 8 that accommodates main portions of the stator 5 and the rotor 6 and one end of the case main body 8 (the right end in FIG. 1). And a case lid 9 that closes the opening. The case lid portion 9 is provided with a connector portion 10 for connecting a power line or a signal line to the stator 5 or a sensor.

  The stator 5 is fixed to the inner peripheral surface of the case body 8 so as not to rotate, and a stator core 5a formed of a plurality of electromagnetic steel plates laminated in the axial direction and a bobbin made of an insulating material attached to the stator core 5a. 5b and a stator coil 5c wound around the bobbin 5b.

  The rotor 6 is disposed so as to be opposed to the inner side in the radial direction of the stator 5 via a gap, and has an annular rotor core 6a, a plurality of magnets 6b attached to the outer peripheral surface of the rotor core 6a, and the inner periphery of the rotor core 6a. It is comprised with the cyclic | annular rotor inner 6c fixed to the surface. The rotor core 6a is formed of, for example, a plurality of electromagnetic steel plates stacked in the axial direction. The axial length of the rotor inner 6c is longer than the axial length of the rotor core 6a, and the rotor inner 6c protrudes on both axial sides of the rotor core 6a. Bearings 11 and 12 are mounted on the outer peripheral surfaces of both end portions of the rotor inner 6c projecting on both sides in the axial direction, respectively. In the present embodiment, one (left side in FIG. 1) bearing 11 is disposed between one end of the rotor inner 6c in the axial direction and the case body 8, and the other (right side in FIG. 1) bearing 12 is the rotor inner 6c. Between the other axial end and the case lid 9. Thus, the rotor inner 6 c is rotatably supported with respect to the motor case 7 by the bearings 11, 12 interposed between the rotor inner 6 c and the motor case 7.

  The reverse input cutoff clutch 4 is accommodated in a cylindrical clutch case 13 that is different from the motor case 7. Further, two bearings 16 and 17 are accommodated on the inner peripheral side of the clutch case 13, and the sliding screw mechanism 3 is supported by these bearings 16 and 17. The clutch case 13 and the motor case 7 (the case main body portion 8 and the case lid portion 9) are integrally fixed using fastening means such as bolts.

  The sliding screw mechanism 3 includes a screw shaft 14 having a thread groove formed on the outer peripheral surface, and a cylindrical nut 15 having a screw groove screwed to the screw shaft 14 on the inner peripheral surface. The screw shaft 14 and the nut 15 are arranged coaxially with the rotor inner 6c. The nut 15 is rotatably supported by two bearings 16 and 17 disposed between the outer peripheral surface of the nut 15 and the inner peripheral surface of the clutch case 13. On the other hand, the screw shaft 14 is restricted so as not to rotate by a non-illustrated anti-rotation means, and advances and retreats in the axial direction when the nut 15 rotates. A hole portion (connecting portion) 14a for connecting to a corresponding portion of a used device (not shown) that is an operation target is provided at the tip end portion (left end portion in FIG. 1) of the screw shaft 14, and the screw shaft 14 is a shaft. The device used is operated by moving forward and backward in the direction. In the present embodiment, as shown in FIG. 1, the screw shaft 14 is disposed on the inner diameter side of the motor unit 2 and the reverse input cutoff clutch 4 with at least the screw shaft 14 retracted to the maximum extent. In this way, the inner diameter side space between the motor unit 2 and the reverse input cutoff clutch 4 can be used as a housing space for the screw shaft 14, and the axial dimension of the screw shaft can be reduced while reducing the axial dimension of the electric actuator. It is possible to ensure a long maximum movement distance.

  In addition, a boot 18 that prevents foreign matter such as dust and water from entering the electric actuator 1 is attached to the distal end side of the screw shaft 14. The boot 18 includes a small-diameter end 18a, a large-diameter end 18b, and a bellows 18c that extends and contracts in the axial direction by connecting them. The small-diameter end 18a is fixed to the outer peripheral surface of the screw shaft 14, and the large-diameter end The part 18 b is fixed to the outer peripheral surface of the clutch case 13.

Here, FIG. 2 is a longitudinal cross-sectional view of the reverse input cutoff clutch 4 as viewed in the direction of the arrows AA in FIG.
Hereinafter, the configuration of the reverse input cutoff clutch 4 will be described with reference to FIGS. 1 and 2.

  The reverse input cutoff clutch 4 includes an input member 19, an output member 20, an outer ring 21 as a stationary member, and a roller 22 as a lock member.

  The input member 19 is fixed to the outer peripheral surface of the end portion of the rotor inner 6c, and is configured to rotate integrally with the rotor inner 6c. A plurality of pockets 19a (see FIG. 2) are formed on the outer peripheral side of the input member 19, and two rollers 22 are accommodated in each pocket 19a. A spring member 23 is accommodated between the pair of rollers 22 in each pocket 19a. The pair of rollers 22 is pressed by the spring member 23 so as to be separated from each other in the circumferential direction.

  The output member 20 is integrally provided on the outer peripheral surface of the nut 15 of the sliding screw mechanism 3. In this way, by integrally molding the output member 20 and the nut 15, these assembling operations become unnecessary. Note that the output member 20 and the nut 15 may be configured separately. A plurality of holes 20 a are formed in the output member 20, and projecting portions 19 b that are provided in the input member 19 and project in the axial direction are inserted into the holes 20 a. When the input member 19 is rotated by the input from the motor unit 2, the rotation is transmitted to the output member 20 by the convex portion 19b coming into contact with the edge of the hole 20a. Contrary to this embodiment, the convex portion may be provided in the output member 20 and the hole portion may be formed in the input member 19. Moreover, the hole 20a may be a hole (concave part) having a bottom in addition to the through hole as shown in FIG.

  The outer peripheral surface of the output member 20 is disposed so as to face the inner peripheral surface of the portion where the pocket 19a of the input member 19 is provided. Of the outer peripheral surface of the output member 20, a convex clutch surface (cam surface) 20b that abuts two flat surfaces is formed at a portion corresponding to each pocket 19a.

  The outer ring 21 is formed in a cylindrical shape and is fixed to the inner peripheral surface of the clutch case 13 so as not to rotate. Between the inner peripheral surface 21a of the outer ring 21 and the clutch surface 20b of the output member 20, a wedge-shaped gap 24 having a width smaller than the diameter of the roller 22 is formed at both ends in the circumferential direction (rotation direction). A roller 22 is accommodated in the gap 24.

The configuration of the reverse input cutoff clutch 4 is summarized as follows.
That is, the reverse input cutoff clutch 4 is an output member configured to rotate integrally with the input member 19 configured to rotate integrally with the rotor inner 6 c of the motor unit 2 and the nut 15 of the slide screw mechanism 3. The input member 19 and the output so as to transmit the rotation from the input member 19 to the output member 20 by contacting the member 20, the hole provided in one of the input member 19 and the output member 20, and the edge of the hole. A convex portion provided on the other side of the member 20, an outer ring 21 as a stationary member fixed so as not to rotate, a pocket 19a provided in the input member 19, and an outer periphery of the output member 20 at a portion corresponding to the pocket 19a Between the clutch surface (cam surface) 20b provided on the surface, the inner peripheral surface 21a of the outer ring 21 and the clutch surface 20b of the output member 20, the width is reduced at both ends in the circumferential direction. Having a wedge-shaped gap 24, a pair of rollers 22 serving as a locking member which is accommodated in a wedge shape gap 24, and a spring member 23 that presses to separate from each other circumferentially with a pair of rollers 22.

  Subsequently, the operation of the electric actuator according to the present embodiment will be described focusing on the function of the reverse input cutoff clutch 4.

  First, the state shown in FIG. 3 is a stopped state in which the motor unit is not driven. In this state, the pair of rollers 22 is pressed by the spring members 23 in the reduction direction of the wedge-shaped gap 24, and engages both the clutch surface 20 b of the output member 20 and the inner peripheral surface 21 a of the outer ring 21 to output the output member 20. It is in the locked state that prevents the rotation of. Further, in this state, there is a rotational direction gap δ1 between the hole surface 19c constituting the pocket 19a of the input member 19 and each roller 22. The rotational direction gap δ1 is set smaller than the rotational direction gap δ2 between the convex portion 19b of the input member 19 and the hole 20a of the output member 20 (δ1 <δ2).

  When the motor unit starts driving from the stopped state and the rotor inner rotates, the input member 19 rotates integrally therewith. For example, as shown in FIG. 4, when the input member 19 starts to rotate in the clockwise direction in the figure, the rotation direction gap is set as described above (δ1 <δ2). The surface 19c contacts the roller 22 at the rear in the rotation direction. At this time, the convex portion 19 b of the input member 19 is not in contact with the hole surface of the hole portion 20 a of the output member 20. When the roller 22 at the rear in the rotational direction is pushed in the clockwise direction by the hole surface 19c of the input member 19 and moves in the wedge-shaped gap 24 against the elastic force of the spring member 23, the roller 22 against the output member 20 and the outer ring 21 is moved. The engagement (locked state) of the roller 22 at the rear in the rotational direction is released. It should be noted that the roller 22 at the front in the rotational direction does not contribute to locking against clockwise rotation. As a result, the output member 20 is allowed to rotate clockwise.

  As shown in FIG. 5, when the input member 19 further rotates clockwise, the convex portion 19 b of the input member 19 comes into contact with the hole surface of the hole portion 20 a of the output member 20. Thereby, clockwise input torque is transmitted from the input member 19 to the output member 20, and the output member 20 rotates clockwise.

  Thus, when the output member 20 rotates with the rotation of the input member 19, the nut 15 (see FIG. 1) of the slide screw mechanism 3 integrally molded with the output member 20 rotates, and the screw shaft 14 moves in the axial direction. Move in one direction (forward or backward). On the other hand, when the input member 19 rotates counterclockwise from the stop state shown in FIG. 3, the output member 20 rotates counterclockwise by the reverse operation to the above, and accordingly, the screw shaft 14 is rotated. Moves to the other in the axial direction. Thereafter, when driving is stopped due to the absence of input from the motor unit, the pair of rollers 22 is engaged with the clutch surface 20b of the output member 20 and the inner peripheral surface 21a of the outer ring 21 by the elastic force of the spring member 23. Return to state.

  Here, in the locked state shown in FIG. 3, when reverse input in the linear motion direction acts on the screw shaft of the sliding screw mechanism from the operation target side (output side), the reverse input is performed in the order of the screw shaft and nut. To the output member of the reverse input cutoff clutch. However, at this time, since the output member is in a locked state, rotation of the output member due to reverse input is prevented. Specifically, in FIG. 3, when a clockwise reverse input torque is applied to the output member 20, the clockwise rearward roller 22 is engaged with the output member 20 and the outer ring 21. The clockwise rotation of the output member 20 is prevented. On the other hand, when a counterclockwise reverse input is applied to the output member 20, the counterclockwise rear roller 22 is engaged with the output member 20 and the outer ring 21. Is prevented from rotating counterclockwise. Thus, in the locked state, rotation of the output member in both forward and reverse directions with respect to reverse input is prevented, so that rotation of the nut of the slide screw mechanism integrated with the output member in both forward and reverse directions is also prevented. Thereby, the screw shaft can be held at a predetermined axial position.

  Subsequently, another embodiment of the electric actuator according to the present invention will be described focusing on portions different from the above embodiment. In the embodiment described below, members having the same function or shape as those of the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 6 is a longitudinal sectional view of an electric actuator according to another embodiment of the present invention.

  The electric actuator 1 shown in FIG. 6 includes a speed reducer 26 between the motor unit 2 and the reverse input cutoff clutch 4. The reduction gear 26 is accommodated in a cylindrical reduction gear case 25, and the reduction gear case 25 is connected between the motor case 7 and the clutch case 13 by using fastening means such as bolts. It is fixed integrally with.

FIG. 7 is a longitudinal cross-sectional view of the speed reducer 26 as viewed along the line BB in FIG.
Hereinafter, the configuration and operation of the speed reducer 26 will be described in detail with reference to FIGS. 6 and 7.

  The speed reducer 26 includes a sun gear 27 as an input rotating body, a ring gear 28 as an orbital ring disposed on the outer periphery of the sun gear 27, and a planetary rotation rotatably disposed between the sun gear 27 and the ring gear 28. It is a planetary gear speed reducer having a plurality of planetary gears 29 as a body and a carrier 30 as an output rotating body that holds each planetary gear 29.

  The sun gear 27 is fixed coaxially to the outer peripheral surface of the rotor inner 6c and rotates integrally with the rotor inner 6c. Each planetary gear 29 is disposed between the sun gear 27 and the ring gear 28 and is assembled so as to mesh with them. Each planetary gear 29 is rotatably attached to a support shaft 31 provided on the carrier 30 via a bearing 32. The carrier 30 is inserted and fixed to the inner peripheral surface of the input member 19 of the reverse input cutoff clutch 4 and rotates integrally with the input member 19.

  In the electric actuator 1 including the speed reducer 26 as described above, when the motor unit 2 starts driving and the rotor inner 6c rotates, the sun gear 27 of the speed reducer 26 rotates integrally therewith. As the sun gear 27 rotates, the plurality of planetary gears 29 revolve along the ring gear 28 while rotating, and the carrier 30 rotates as the planetary gear 29 revolves. As a result, the rotation of the motor unit 2 is decelerated and transmitted to the input member 19 of the reverse input cutoff clutch 4.

  Since the operation after input to the reverse input cutoff clutch is the same as the operation in the above embodiment, the description thereof is omitted. Therefore, also in the present embodiment, during driving input from the motor unit, the locked state of the reverse input cutoff clutch is released, and the rotation of the output member is allowed. On the other hand, when the input is not input from the motor unit, the reverse input shut-off clutch is in the locked state, so that even if reverse input is applied from the output side, the forward and reverse of the nut of the slide screw mechanism against the reverse input Bi-directional rotation is prevented.

  In the present embodiment, as shown in FIG. 6, the screw shaft 14 is disposed on the inner diameter side of the motor unit 2, the speed reducer 26, and the reverse input cutoff clutch 4 with at least the screw shaft 14 retracted to the maximum extent. Is done. By doing in this way, the inner diameter side space of the motor unit 2, the speed reducer 26, and the reverse input cutoff clutch 4 can be used as a housing space for the screw shaft 14, and the axial dimension of the electric actuator can be reduced as in the above embodiment. It is possible to ensure a long maximum movement distance in the axial direction of the screw shaft while reducing the size.

  As described above, the electric actuator according to each embodiment of the present invention uses a sliding screw mechanism having a higher braking force against reverse input than the ball screw mechanism as a motion conversion mechanism, and further includes a reverse input cutoff clutch. As a result, even when the energization of the motor unit is stopped (when stopped), the sliding screw mechanism can be highly prevented from rotating with respect to the reverse input. In addition, the reverse input cutoff clutch prevents not only rotation in one direction but also forward and reverse rotation with respect to the reverse input, so even if vibration is transmitted to the electric actuator, the locked state by the reverse input cutoff clutch is reliably maintained. can do. As described above, since the electric actuator according to the present invention can exhibit a high braking force against reverse input even when used in a place where vibration occurs, for example, an electric parking brake mechanism for an automobile including a motorcycle, It is suitable for a vehicle height adjusting device.

  On the other hand, since the electric actuator according to the present invention uses a sliding screw mechanism with poor power transmission efficiency, the power transmission efficiency (positive efficiency) from the motor unit is higher than that of an electric actuator using a ball screw mechanism. It tends to decrease. Therefore, although the reverse input prevention function of the slide screw mechanism itself is somewhat lowered, in order to improve power transmission efficiency (normal efficiency), PTFE or the like is baked on the surface of at least one thread groove of the screw shaft and nut. The surface of the thread groove may be covered with a slidable resin having a low friction coefficient.

  Further, in a configuration including a speed reducer such as the electric actuator shown in FIG. 6, the reverse input cutoff clutch is arranged on the output side of the speed reducer, and the rotational motion decelerated by the speed reducer is input to the reverse input cutoff clutch. By configuring so, abnormal noise (vibration) in a phenomenon called “catch-up lock” can be reduced. “Catch-up lock” is a state in which a reverse input (reaction force) from the output side is acting on the electric actuator, and when the reverse input cutoff clutch is unlocked (the state shown in FIG. 4). When the output member 20 receives a reverse input and rotates in the same direction as the input member 19 and faster than the input member 19, the output member 20 catches up with the roller 22, and the roller 22 again rotates. And the outer ring 21 are engaged and become a locked state. Thereafter, the roller 22 is pushed out by the input member 19 that continues to rotate and is unlocked, and the operation that the output member 20 starts to rotate along with the rotation is repeated. As a result, abnormal noise (vibration) occurs in the reverse input cutoff clutch.

  Therefore, in the embodiment shown in FIG. 6, the rotational motion decelerated by the speed reducer is input to the reverse input cutoff clutch, whereby the speed between the rotation of the input member and the rotation of the output member in the reverse input cutoff clutch. The difference is made small so that abnormal noise (vibration) when catch-up lock occurs can be reduced. For example, as shown in FIG. 8A, in the configuration in which the reverse input cutoff clutch is arranged on the output side from the reduction gear, the input rotational speed from the motor unit is 2000 rpm, and the reverse input rotational speed from the output side is 500 rpm. When the input rotation is reduced to 1/10 by the speed reducer, the input rotation (2000 rpm) from the motor unit is reduced to 1/10 200 rpm and input to the reverse input cutoff clutch. The speed difference between the input rotation (200 rpm) and the reverse input rotation (500 rpm) in the clutch is 300 rpm. On the other hand, as shown in FIG. 8B, when the reverse input cutoff clutch is arranged on the input side from the reduction gear, the input rotation (2000 rpm) from the motor unit is not decelerated and the reverse input cutoff clutch Further, the reverse input rotation (500 rpm) from the output side is accelerated to 5000 rpm, which is 10 times through the speed reducer, and is input to the reverse input cutoff clutch. The difference in speed between 2000 rpm) and reverse input rotation (5000 rpm) is 3000 rpm.

  As described above, the speed difference between the input rotation and the reverse input rotation in the reverse input cutoff clutch is such that a speed reducer is disposed between the motor unit and the reverse input cutoff clutch, and the rotational motion decelerated by the speed reducer is reverse input cut off. Since the configuration is such that the input to the clutch is smaller, it is possible to reduce the noise (vibration) associated with the re-engagement of the roller when a catch-up lock occurs.

  As mentioned above, although embodiment of the electric actuator which concerns on this invention was described, this invention is not limited to the said embodiment at all, In the range which does not deviate from the summary of this invention, it can implement with a various form. Of course.

  In the above-described embodiment, the radial gap type electric motor in which the stator and the rotor are arranged to face each other with a gap in the radial direction is exemplified as the electric motor. However, a motor having an arbitrary configuration can be adopted. . For example, an axial gap type electric motor in which the stator and the rotor are arranged so as to face each other with a gap in the axial direction may be used.

  Moreover, in the said embodiment, although the planetary gear reduction gear was illustrated as a reduction gear, a reduction gear is not restricted to this. For example, a sun roller as an input rotator that rotates integrally with the motor unit, an orbit ring disposed on the outer periphery of the sun roller, and a planetary rotator disposed rotatably between the sun roller and the orbit ring. A traction drive type planetary speed reducer having a plurality of planetary rollers and a carrier as an output rotating body that holds each planetary roller may be adopted. It is also possible to use a speed reducer having a configuration other than the planetary speed reducer.

  Further, the reverse input cutoff clutch is not limited to that of the above embodiment. Other configurations may be applied as long as the sliding screw mechanism can be prevented from rotating in both forward and reverse directions with respect to reverse input. Further, the sliding screw mechanism is not limited to a mechanism that rotates the nut and advances and retracts the screw shaft in the axial direction as in the above embodiment, but may be a mechanism that rotates the screw shaft and advances and retracts the nut. .

DESCRIPTION OF SYMBOLS 1 Electric actuator 2 Motor part 3 Sliding screw mechanism (motion conversion mechanism)
4 Reverse input cutoff clutch 14 Screw shaft 15 Nut 19 Input member 20 Output member 21 Outer ring (stationary member)
22 Roller (locking member)
26 Reducer

Claims (6)

In an electric actuator comprising a motor unit and a motion conversion mechanism that converts a rotational motion of the motor unit into a linear motion,
The motion conversion mechanism is constituted by a sliding screw mechanism having a screw shaft and a nut screwed to the screw shaft,
An electric actuator comprising a reverse input shut-off clutch that prevents the sliding screw mechanism from rotating in both forward and reverse directions against reverse input from an output side opposite to the motor unit. The reverse input cutoff clutch is
An input member that rotates by an input from the motor unit;
An output member that rotates with the rotation of the input member and outputs the rotational force to the sliding screw mechanism;
A stationary member fixed so as not to rotate;
At the time of driving input from the motor unit, the rotating input member is disengaged from the stationary member and the output member by the rotating input member to allow rotation of the output member, and at the time of stop not input from the motor unit, The electric actuator according to claim 1, further comprising: a lock member that engages with the stationary member and the output member to prevent the output member from rotating in both forward and reverse directions. A speed reducer that decelerates and transmits the rotational motion of the motor unit;
The electric actuator according to claim 2, wherein the reverse input cut-off clutch is disposed on the output side of the speed reducer.   The electric actuator according to claim 2 or 3, wherein the output member and a nut of the sliding screw mechanism are integrally molded.   The electric actuator according to any one of claims 1 to 4, wherein a surface of at least one thread groove of the screw shaft and the nut of the sliding screw mechanism is covered with a slidable resin.   The electric actuator according to any one of claims 1 to 5, wherein a screw shaft of the sliding screw mechanism is disposed on an inner diameter side of the motor unit and the reverse input cutoff clutch.

Images