JP2008249057A - Motor driven disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor driven disc brake for reducing the influence of travelling vibration on a parking brake mechanism. <P>SOLUTION: In the motor driven disc brake, the rotation of a motor 39 is reduced by a differential reduction gear mechanism and converted into linear motion by a ball ramp mechanism to move a piston forward, and a brake pad is thrust against a disc rotor 2 to generate braking force. In the parking brake mechanism 41, an engaging pawl member 54 is turned by a plunger 55A of a solenoid actuator 55 to engage with a pawl wheel 52 connected to a motor rotor, whereby the rotation is locked to hold a braking condition. The gravity center position of a whole movable part including the engaging pawl member 54 an the plunger 55A, is arranged parallel to a vibrating direction during travel and near a straight line passing through the turning center (a pin 53) of the engaging pawl member 54. Thus, no moment force works on the engaging pawl member 54 with vibration, reducing the load of the solenoid actuator 55. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric disk brake that generates a braking force by pressing a brake pad against a disk rotor by an electric motor, and more particularly, to an electric disk brake including a parking brake mechanism that can maintain the braking force in a non-energized state. Is.

  As an electric disc brake, the rotary motion of the rotor of the electric motor is converted into a linear motion of the piston using a rotation-linear motion conversion mechanism such as a ball screw mechanism or a ball ramp mechanism, and the brake pad is pressed against the disc rotor by the piston. Thus, a device that generates a braking force is known. The electric disc brake generates a desired braking force by detecting a driver's brake pedal depression force (or displacement amount) using a sensor and controlling the rotation of the electric motor based on the detected value by a control device. Can do.

In this type of electric disc brake, for example, as described in Patent Document 1, the braking state can be maintained even after energization of the electric motor is stopped by mechanically locking the rotation of the rotor of the electric motor. Some have a parking brake mechanism.
Japanese Patent Application Laid-Open No. 2005-9633

  In the electric disc brake described in Patent Document 1, a claw wheel is attached to the rotor of the electric motor, and an engagement claw that can be engaged and disengaged with a claw portion of the claw wheel by a solenoid actuator is provided to brake the rotor of the electric motor. After rotating to the position, the engaging claw is hooked on the claw wheel so that the braking state can be maintained in the non-energized state.

  However, the electric disc brake provided with the parking brake mechanism described in Patent Document 1 has the following problems. In the one described in Patent Document 1, the parking brake mechanism has an arm A rotatably supported by a pin C as shown in FIG. 4, and the arm A has a rotor of an electric motor. Parts such as an engaging claw T for locking (not shown), a plunger P of a solenoid actuator, a holding spring S1, and a spring S2 are connected. Then, the arm A is rotated about the pin C by the movement of the plunger P of the solenoid actuator, whereby the rotor is locked and unlocked by the engagement claw T. When the lock is released, electric power is supplied to the solenoid actuator to separate the engagement claw T from the claw wheel.

  In general, an electric disc brake is mounted under a spring of a suspension device of a vehicle, and thus vibrates up and down violently due to road surface unevenness while the vehicle is running. Due to this vibration, vertical acceleration a occurs in each part of the parking brake mechanism of the electric disc brake. At this time, the moment force M around the pin C acts on the arm A according to the position of the center of gravity of each component (distance from the pin C which is the rotation center of the arm A) by the acceleration a in the vertical direction. Become. The moment force M can be expressed by the following equation (1).

M = M1 + M2
= M1 ・ a ・ r1 + m2 ・ a ・ r2
= (M1 · r1 + m2 · r2) a (1)
here,
M1: Moment force acting on arm A (with engagement claw T, spring S2, etc. attached, hereinafter the same) M2: Moment force acting on plunger P m1: Mass of arm A m2: Mass of plunger P r1 : Distance from the center of rotation (pin C) to the center of gravity of arm A.
r2: Distance from the rotation center (pin C) to the center of gravity of the plunger P.

  For this reason, it is necessary to sufficiently increase the thrust force and holding force of the solenoid actuator so that the arm A does not rotate due to the moment force M due to vibration during traveling, and there is a problem that the solenoid actuator becomes large and power consumption increases. is there. Further, unlike the case of Patent Document 1, even in the case of using a spring to separate the engaging claw and the claw wheel, it is necessary to sufficiently increase the return force of the spring, and there is a problem that the spring is enlarged. .

  The present invention has been made in view of the above points, and an object of the present invention is to provide an electric disc brake that reduces the influence on the parking brake mechanism due to vibration during traveling.

In order to solve the above problems, an invention according to claim 1 includes an electric motor and a rotation-linear motion conversion mechanism that converts rotation of the rotor of the electric motor into linear motion, and the rotation-linear motion conversion. A brake pad is pressed against the disk rotor by a mechanism to generate a braking force, and further, a claw wheel having a plurality of claw parts and rotating as the rotor rotates, and a claw wheel that is rotatably supported by the claw part. An engaging claw member that can be engaged and a driving means connected to the engaging claw member are provided, and the engaging claw member is rotated by the driving means and hooked on the claw portion of the claw wheel. In the electric disc brake provided with a parking brake mechanism that locks the rotation of the rotor and maintains the braking state,
The position of the center of gravity including the engaging claw member and the movable portion of the driving means connected to the engaging claw member is arranged substantially in the vicinity of a straight line parallel to a predetermined vibration direction and passing through the rotation center of the engaging claw member. It is characterized by that.
An electric disk brake according to a second aspect of the present invention is characterized in that, in the configuration of the first aspect, the drive means is a solenoid actuator, and the movable portion is a plunger of the solenoid actuator.
The electric disc brake according to a third aspect of the invention is characterized in that, in the configuration of the first or second aspect, urging means for urging the engaging claw member in a direction to separate the claw wheel from the claw wheel is provided. And

According to the electric disc brake of the first aspect of the present invention, even if acceleration is generated in each component due to vibration, no moment force acts on the engaging claw member, so that the load on the driving means can be reduced.
According to the electric disc brake of the second aspect of the invention, the load on the solenoid actuator can be reduced.
According to the electric disk brake of the invention of claim 3, it is possible to reduce the load on the urging means.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, the electric disc brake 1 according to the present embodiment is a caliper floating disc brake, and includes a disc rotor 2 that rotates together with wheels, and a non-rotating portion on the vehicle body side such as a suspension member ( A carrier 3 fixed to the disk rotor 2, a pair of brake pads 4 and 5 disposed on both sides of the disk rotor 2 and supported by the carrier 3, and a pair of slide pins disposed across the disk rotor 2. 6 and 6, an electric caliper 7 supported so as to be movable along the axial direction of the disk rotor 2 with respect to the carrier 3 is provided.

  The electric caliper 7 includes a caliper body 8, a piston unit 9, and a motor unit 10. The caliper body 8 includes a cylindrical cylinder part 11 having a through hole that opens to face one side of the disk rotor 2, a claw part 12 that extends from the cylinder part 11 across the disk rotor 2 to the opposite side, and a cylinder A pair of arm portions 13 extending in a substantially diametrical direction from the portion 11 and to which the pair of slide pins 6 and 6 are respectively attached are integrally formed. A guide bore 15 into which a piston 14 (described later) of the piston unit 9 is slidably fitted and a male screw 17 of an adjusting screw 16 (described later) attached to the piston unit 9 are screwed on the inner peripheral surface of the cylinder portion 11. A mating female screw 18 is formed.

  The piston unit 9 includes a bottomed cylindrical piston 14, a ball ramp mechanism 19 (rotation-linear motion conversion mechanism) and differential reduction mechanism 20 housed in the piston 14, and a pad wear compensation mechanism 21. It has become. The piston 14 is slidably fitted to the guide bore 15 of the caliper body 8, contacts the one brake pad 5, and is prevented from rotating by a pin 5A. The piston 14 and the guide bore 15 are sealed with a dust seal 22 and a seal ring 23.

  The ball ramp mechanism 19 is formed on a linearly moving disk 24 fixed to the bottom surface of the piston 14 and movable in the axial direction together with the piston 14, and a rotating disk 25 movable in the rotating direction. And a ball 28 inserted between the ball grooves 26 and 27 (inclined grooves). The rotating disk 25 is constantly urged toward the linear motion disk 24 by a plurality of wave washers or an integral coiled wave washer 29. When the linear motion disk 24 and the rotary disk 25 are rotated relative to each other, the balls 28 roll between the inclined ball grooves 26 and 27, so that the linear motion disk 24 and the rotary disk 25 correspond to the rotation angle. Move relative to the axis. Thereby, a rotational motion can be converted into a linear motion.

  The differential speed reduction mechanism 20 includes an eccentric shaft 30, a ring-shaped spur gear 32 having two external teeth 32A and 32B supported rotatably by bearings 31A and 31B on an eccentric portion 31 of the eccentric shaft 30, a ball ramp An internal tooth 33 formed on the rotary disk 25 of the mechanism 19 and meshing with one external tooth 32A of the spur gear 32, and the other external tooth of the spur gear 32 supported rotatably with respect to the rotational shaft of the eccentric shaft 30. And a ring gear member 35 having internal teeth 34 that mesh with 32B. One end of the eccentric shaft 30 is rotatably supported by the rotary disk 25, the other end is extended into the motor unit 10, and an outer spline 36 is formed at the tip. One end of the ring gear member 35 is in contact with the end of the rotating disk 25 via a thrust bearing 37. Then, by rotating the eccentric shaft 30 and revolving the spur gear 32, the ring gear member having the rotary disk 25 having the internal teeth 33 meshing with the external teeth 32A of the spur gear 32 and the internal teeth 34 meshing with the external teeth 32B. 35 is differentially rotated, and by fixing one of these, the other can be decelerated and rotated at a predetermined reduction ratio.

  The pad wear compensation mechanism 21 includes a limiter 38 mounted between the linear motion disk 24 and the rotary disk 25 of the ball ramp mechanism 19, an adjustment screw 16 coupled to the ring gear member 35 of the differential reduction mechanism 20, and an adjustment. A wave washer 38A interposed between the ring gear member 35 connected to the screw 16 and the piston 14 is provided. The limiter 38 applies a biasing force in the return direction with a certain amount of play between the linear motion disk 24 and the rotary disk 25 by a torsion spring. The adjustment screw 16 has a male screw 17 (trapezoidal screw) formed on the outer periphery thereof, and the male screw 17 is screwed into a female screw 18 (trapezoidal screw) formed on the cylinder portion 11 of the caliper body 8. The adjustment screw 16 is held so as not to rotate with a constant holding force by the wave washer 38A, and is moved in the axial direction by the relative rotation of the male screw 17 and the female screw 18 by rotating against the holding force. Can do. The adjusting screw 16 receives the reaction force from the rotating disk 25 via the thrust bearing 37 and the ring gear member 35 and transmits the reaction force to the caliper body 8 via the male screw 17 and the female screw 18.

  The motor unit 10 is integrated with a motor 39 (electric motor), a resolver 40 for detecting the rotational position of the motor 39, and a parking brake mechanism 41 for holding the rotational position of the motor 39. The motor 39 includes a cylindrical motor case 44 that is attached to the base plate 43 coupled to the end of the caliper body 8 and is inserted into the adjustment screw 16 of the piston unit 9. A coil or the like is provided on the inner periphery of the motor case 44. A motor stator 45 is fixed. The motor case 44 includes a bottomed cylindrical motor case main body 44A and a motor case lid 44B that closes the opening thereof. Bearings 46 and 47 are attached to openings provided in the motor case main body 44A and the motor case lid 44B. A cylindrical motor rotor 48 (rotor) is rotatably supported by these bearings 46 and 47. The motor case 44 abuts on the inner periphery of the cylinder portion 11 of the caliper body 8 and is supported in the radial direction. An inner spline 49 that engages with the outer spline 36 of the eccentric shaft 30 of the piston unit 9 is formed on the inner peripheral portion of the motor rotor 48, and transmits rotational force between the motor rotor 48 and the eccentric shaft 30. These can be moved relative to each other in the axial direction.

  The resolver 40 includes a resolver stator 50 fixed to the base plate 43, and a resolver rotor 51 attached to the tip of the motor rotor 48 inserted through the base plate 43 and positioned on the inner periphery of the resolver stator 50. An electrical signal indicating the rotational position of the motor rotor 48 is output by relative rotation.

  As shown mainly in FIG. 1, the parking brake mechanism 41 is disposed on the outer peripheral side of the claw wheel 52 attached to the motor rotor 48 and the pin wheel 53 and is rotatably supported by the base plate 43. An engaging claw member 54 and a solenoid actuator 55 (driving means) that is fixed to the base plate 43 (FIG. 2) and drives the engaging claw member 54 are provided.

  The claw wheel 52 is fitted to the rear end portion (right end portion in FIG. 2) of the motor rotor 48 and is fixed so as to rotate together with the motor rotor 48 by a key 56. A large number of claw portions 57 are formed on the outer peripheral portion of the claw wheel 52 at regular intervals.

  The engaging claw member 54 is extended on both sides with a pin 53 that is the center of rotation, and an engaging claw portion 63 is formed at one end of the engaging claw member 54. The engaging claw portion 63 can be engaged with and detached from one of the claw portions 57 of the claw wheel 52. The claw portion 57 of the claw wheel 52 and the engagement claw portion 63 of the engagement claw member 54 are formed in a bowl shape having an inclination in a certain direction, and when engaged with each other, the counterclockwise of the claw wheel 52 in FIG. The rotation in the direction (braking release direction) is locked, and the force for rotating the engaging claw member 54 in the unlocking direction is generated for the rotation in the clockwise direction (braking direction). ing. Moreover, in this Embodiment, although the claw part 57 of the claw wheel 52 is formed in the shape where the top part and the bottom part are flat, it does not need to have such a flat shape.

  In the solenoid actuator 55, the tip end of the plunger 55A (movable part) has a pin 53 which is the center of rotation with respect to the other end part of the engaging claw member 54 (one end part where the engaging claw part 63 is formed). The end of the claw wheel 52 is connected to the claw portion 57 of the claw wheel 52 by rotating the engagement claw member 54 by energization. , Can be withdrawn. More specifically, the plunger 55 </ b> A has a compression spring 55 </ b> B (biasing means) on the outer periphery thereof, and the engagement claw portion 63 is normally detached from the claw portion 57 of the claw wheel 52 by the spring force of the compression spring 55 </ b> B. Thus, the engaging claw member 54 is rotated by energizing the solenoid actuator 55 so that the engaging claw portion 63 is engaged with the claw portion 57 of the claw wheel 52. However, the present invention is not limited to this, and a tension spring is provided in place of the compression spring 55 </ b> B, and the engagement claw member 54 is rotated by energizing the solenoid actuator 55. You may make it detach from. Further, by using a solenoid actuator 55 that can hold the plunger 55A at both end positions by a permanent magnet or the like without providing a spring, the engagement claw member 54 is moved to the engagement / disengagement position, and then in a non-energized state. Plunger 55A can be held at each position.

  Here, as shown in FIG. 3, the engaging claw member 54 is extended to both sides with the pin 53 being the rotation center as described above, but its center of gravity (indicated by reference numeral m1). Is arranged on the side of the engaging claw 63 with respect to the pin 53, and a plunger 55A is connected to the opposite end thereof. Note that the center of gravity of the plunger 55A is denoted by reference numeral m2. As a result, the moment force M around the pin 53 acting on the engaging claw member 54 with respect to the vertical acceleration (vibration direction) acceleration a caused by the unsprung vibration of the vehicle can be expressed by the following equation (2). it can.

M = M1-M2
= M1 · a · r1−m2 · a · r2
= (M1 · r1−m2 · r2) a (2)
here,
M1: Moment force acting on the engaging claw member 54 M2: Moment force acting on the plunger 55A m1: Mass of the engaging claw member 54 m2: Mass of the plunger 55A r1: Engaging claw member from the rotation center (pin 53) Distance to 54 center of gravity.
r2: Distance from the rotation center (pin 53) to the center of gravity of the plunger 55A.

  The product (m1 · r1) of the mass m1 of the engaging claw member 54 and the distance r1 from the rotation center (pin 53) to the center of gravity of the engagement claw member 54, the mass m2 of the plunger 55A and the rotation center ( The form (shape, size, mass, etc.) of each part is set so that the product (m2 · r2) with the distance r2 from the pin 53) to the center of gravity of the plunger 55A is as equal as possible (m1 · r1 = m2 · r2). Has been. That is, the center of gravity including the engaging claw member 54 and the movable portion such as the plunger 55A connected thereto is parallel to the direction of acceleration a (vibration direction) and the rotation center of the engaging claw portion 54 (pin 53). It is arranged almost on the straight line passing through.

The operation of the present embodiment configured as described above will be described next.
At the time of braking, a control current is supplied from a controller (not shown) to the motor 39 based on the brake operation of the driving vehicle to rotate the motor rotor 48 in the braking direction. The rotation of the motor rotor 48 is decelerated at a predetermined reduction ratio by the differential reduction mechanism 20 and converted into a linear motion by the ball ramp mechanism 19 to advance the piston 14. As the piston 14 advances, one brake pad 5 is pressed against the disc rotor 2, and the caliper body 8 moves along the slide pin 6 of the carrier 3 due to the reaction force, and the claw portion 12 moves the other brake pad 4. The disc rotor 2 is pressed to generate a braking force. Further, at the time of releasing the brake, the piston 14 is moved backward by rotating the motor rotor 48 backward to separate the brake pads 4 and 5 from the disc rotor 2.

  The controller detects various vehicle conditions such as the rotational speed of each wheel, vehicle speed, vehicle acceleration, steering angle, and vehicle lateral acceleration using various sensors, and controls the rotation of the motor 39 based on these detections. Thus, boost control, antilock control, traction control, vehicle stabilization control, and the like can be executed.

Next, the operation of the differential reduction mechanism 20 and the pad wear compensation mechanism 21 will be described.
When the eccentric shaft 30 is rotated by the motor rotor 48 at the time of braking, the spur gear 32 revolves due to the eccentric rotation of the eccentric portion 31, and the rotating disk 25 and the ring gear member 35 engaged with the external teeth 32 </ b> A and 32 </ b> B of the spur gear 32 are different. Dynamic rotation. At this time, normally, the rotation of the ring gear member 35 together with the adjusting screw 16 is fixed by the wave washer 38A, while the rotating disk 25 can freely rotate within the range of play of the limiter 38. Rotates. As a result, the ball ramp mechanism 19 advances the piston 14 and presses the brake pads 4 and 5 against the disc rotor 2. After the brake pads 4 and 5 start to press the disk rotor 2, the reaction force acts on the male screw 17 and the female screw 18, thereby increasing the frictional force between them and adjusting the screw 16, that is, the ring gear member 35. The rotation is securely locked. Therefore, the rotary disk 25 can rotate against the spring force of the limiter 38.

  When the brake pads 4 and 5 are worn and the disk 25 is not pressed even when the rotating disk 25 exceeds the range of play of the limiter 38, the spring force of the limiter 38 acts on the rotating disk 25, and the rotating disk 25 is The adjusting screw 16 is rotated together with the ring gear member 35 against the holding force of the wave washer 38A. Thereby, the adjustment screw 16 moves forward by the relative rotation of the male screw 17 and the female screw 18 to advance the piston unit 9. When the brake pads 4 and 5 move forward by the amount of wear and press the disk rotor 2, as described above, the frictional force of the male screw 17 and the female screw 18 is increased by the reaction force, and the rotation of the adjusting screw 16 is locked. Is done. Thereafter, the rotary disk 25 rotates against the spring force of the limiter 38 and the piston 14 advances by the ball ramp mechanism 19. In this way, the piston unit 9 can be advanced by the adjusting screw 16 by the amount of wear of the brake pads 4 and 5, and wear of the brake pads 4 and 5 can be compensated.

Next, the operation of the parking brake mechanism 41 will be described.
When operating the parking brake, first, the motor rotor 48 is rotated in the braking direction to press the brake pads 4 and 5 against the disc rotor 2 with a desired force. In this state, the solenoid actuator 55 is operated to press the engagement claw portion 63 of the engagement claw member 54 against the claw portion 57 of the claw wheel 52. At this time, the claw portions 63 and the claw portions 57 may not be engaged because the top portions interfere with each other. Next, the motor rotor 48 is rotated in the braking release direction so that the engaging claw portion 63 and the claw portion 57 are reliably engaged. Then, after the energization to the motor 39 is stopped and the pressing force of the brake pads 4 and 5 to the disc rotor 2 is confirmed, the energization to the solenoid actuator 55 is stopped and the engagement claw portion 63 and the claw portion 57 Maintains the engaged state. Thereby, the braking state can be maintained in a state where energization to the motor 39 and the solenoid actuator 55 is stopped.

  When releasing the operation of the parking brake, the energizing claw 63 of the engaging claw member 54 is not energized to the solenoid actuator 55 but is slightly rotated in the braking direction by energizing the motor rotor 48. And the claw portion 52 of the claw wheel 52 is loosely engaged, and the engagement claw member 54 is rotated in a direction to release the engagement between the engagement claw portion 63 and the claw portion 57 by the biasing force of the compression spring 55B. The braking force is released by rotating the motor rotor 48 in the braking release direction by the reaction force from the brake pads 4 and 5 and the spring force of the wave washer 29 or by energizing the motor rotor 48 in the braking release direction.

Next, the case where the disc brake 1 vibrates in the vertical direction due to the unsprung vibration while the vehicle is running and the vertical acceleration a occurs in the engaging claw portion 54 will be described.
The product (m1 · r1) of the mass m1 of the engaging claw member 54 and the distance r1 from the center of rotation (pin 53) to the center of gravity of the engaging claw member 54, the mass m2 of the plunger 55A and the center of rotation (pin 53) ) To the center of gravity of the plunger 55A so that the product (m2 · r2) is as equal as possible (m1 · r1 = m2 · r2), that is, the engaging claw member 54 and the plunger connected thereto Since the center of gravity including the movable part such as 55A is arranged in the vicinity of a straight line parallel to the direction of the acceleration a and passing through the rotation center (pin 53) of the engaging claw member 54, The moment force M hardly occurs in the engaging claw member 54 with respect to the acceleration a (M≈0). As a result, the spring force of the compression spring 55B and the thrust force and holding force of the solenoid actuator 55 can be reduced, and the power consumption can be reduced and the size and weight can be reduced.

  The form of the engaging claw member 54, its rotation center (pin 53), the plunger 55A (plunger) connected to the engaging claw member 54, etc. is not limited to the above, but the whole including these movable parts. It is only necessary that the position of the center of gravity is arranged in the vicinity of a straight line passing through the center of rotation of the engaging claw member 54 in parallel with the direction of the acceleration a. In the present embodiment, the claw wheel 52 is provided on the motor rotor 48. However, the claw wheel 52 is a part that rotates with the rotation of the motor rotor 48, so that the rotation of the claw wheel 52 is fixed and held. What is necessary is just to provide in the site | part which can hold | maintain the position of piston 14, for example, you may make it provide in the rotating disk 25. FIG.

It is a longitudinal cross-sectional view by the AA line of FIG. 2 which shows the electric disc brake which concerns on 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the electric disc brake shown in FIG. It is explanatory drawing which shows the moment force which acts when the acceleration of a vertical direction arises in the parking brake mechanism of the electric disc brake shown in FIG. It is explanatory drawing which shows the moment force which acts when the acceleration of a vertical direction arises in the parking brake mechanism of the conventional electric disc brake.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electric disc brake, 2 Disc rotor, 4, 5 Brake pad, 39 Motor (electric motor), 41 Parking brake mechanism, 48 Motor rotor (rotor), 52 Claw wheel, 54 Engagement claw member, 53 pin (rotation center) , 55 Solenoid actuator (driving means), 55A Plunger (movable part), 57 Claw part

Claims (3)

An electric motor and a rotation-linear motion conversion mechanism that converts the rotation of the rotor of the electric motor into a linear motion, and the brake pad is pressed against the disk rotor by the rotation-linear motion conversion mechanism to generate a braking force; Further, a claw wheel having a plurality of claw portions and rotating as the rotor rotates, an engagement claw member that is rotatably supported and engageable with the claw portion, and is coupled to the engagement claw member A parking brake mechanism that holds the braking state by locking the rotation of the rotor by rotating the engaging claw member by the driving means and hooking it on the claw portion of the claw wheel. In the equipped electric disc brake,
The position of the center of gravity including the engaging claw member and the movable portion of the driving means connected to the engaging claw member is arranged substantially in the vicinity of a straight line parallel to a predetermined vibration direction and passing through the rotation center of the engaging claw member. Electric disc brake characterized by that. 2. The electric disc brake according to claim 1, wherein the driving means is a solenoid actuator, and the movable portion is a plunger of the solenoid actuator. 3. The electric disc brake according to claim 1, further comprising an urging unit that urges the engaging claw member in a direction in which the engaging claw member is separated from the claw wheel.

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