JP4623316B2 - Electric disc brake - Google Patents

Description

  The present invention relates to an electric disc brake that generates a braking force by pressing a brake pad against a disc rotor by an electric motor.

  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, a ball ramp mechanism, etc., and the brake pad is pressed against the disc rotor, What 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 an electric disc brake using a ball ramp mechanism that has a linear motion stroke smaller than that of a ball screw mechanism or the like as a rotation-linear motion conversion mechanism, the operating stroke is insufficient for wear of the brake pad. It is necessary to make the ball ramp mechanism follow the wear. Therefore, for example, in the electric disc brake described in Patent Document 1, when the brake pad is worn and a gap is generated between the piston and the piston, the linear disc of the ball ramp mechanism is rotated, and the linear disc and the piston are moved. The piston is moved forward by an adjusting screw between the brake pads so that the brake pads are worn. As a result, even when the brake pad is worn, the pad clearance can always be kept constant regardless of the stroke of the ball ramp mechanism.
JP 2003-294667 A

  However, the electric disc brake described in Patent Document 1 has the following problems. When adjusting the wear of the brake pad, only the adjustment screw advances together with the piston toward the disc rotor, and the differential reduction mechanism, the ball ramp mechanism, and the electric motor do not advance. For this reason, the position of the center of gravity of the caliper including the claw portion moves in a direction away from the disc rotor by the amount of wear of the brake pad on the claw portion side. As a result, the bending moment acting on the support portion of the electric disc brake increases, causing problems such as rattling noise, dragging due to a decrease in sliding performance of the slide pin, and uneven wear of the brake pad.

  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 capable of reducing the change in the position of the center of gravity of the caliper with respect to wear of the brake pad.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a caliper body, an electric motor, a speed reduction mechanism for reducing the rotation of the electric motor, and a rotation for converting the rotation of the speed reduction mechanism into a linear motion. In a caliper floating type electric disc brake that is provided with a linear motion conversion mechanism and generates a braking force by pressing the brake pad against the disc rotor via the pressing member by the rotation-linear motion conversion mechanism,
The speed reduction mechanism and the rotation-linear motion conversion mechanism are integrated into the pressing member to form an integrated pressing unit. When the brake pad is worn, the pressing unit follows the wear of the brake pad. And moving away from the electric motor.
According to a second aspect of the present invention, in the electric disc brake according to the first aspect, the position of the brake pad relative to the disc rotor during non-braking is fixed to the pressing unit according to wear of the brake pad. A pad wear compensation mechanism for adjustment is provided.
An electric disk brake according to a third aspect of the present invention is the configuration according to the first or second aspect, wherein a rotating shaft that transmits a rotational force between the electric motor and the speed reduction mechanism is connected to the electric motor or the speed reduction mechanism. On the other hand, it is connected so as to be movable in the axial direction.
According to a fourth aspect of the present invention, there is provided the electric disc brake according to the third aspect, wherein the rotating shaft protrudes from the pressing unit and is connected to the electric motor so as to be movable in the axial direction. And
According to a fifth aspect of the present invention, there is provided the electric disc brake according to the third aspect, wherein the rotating shaft protrudes from the electric motor and is movably connected to the speed reduction mechanism.

According to the electric disc brake of the first aspect of the invention, when the brake pad is worn, the caliper body moves in a direction away from the disc rotor with respect to the wear of the brake pad. Since the pressing unit including the dynamic conversion mechanism moves toward the disc rotor following the wear of the brake pads, the change in the center of gravity is small, so the bending moment that acts on the caliper body support due to unsprung vibration etc. The increase in the noise becomes small, and rattle noise, drag, and uneven wear of the brake pad can be prevented.
According to the electric disc brake of the second aspect of the invention, the pad clearance can be adjusted to be constant with respect to wear of the brake pad.
According to the electric disc brake of the third aspect of the invention, the pressing unit follows the wear of the brake pad by moving the rotating shaft in the axial direction with respect to the wear of the brake pad relative to the electric motor or the speed reduction mechanism. It can be so.
According to the electric disc brake of the fourth aspect of the present invention, the pressing unit can follow the wear of the brake pad by moving the rotating shaft in the axial direction with respect to the wear of the brake pad. To do.
According to the electric disc brake of the fifth aspect of the present invention, the pressing unit can follow the wear of the brake pad by moving the rotating shaft in the axial direction with respect to the wear of the brake pad in the axial direction. To do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 to 4, 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, the pair of arm portions 3 </ b> A and 3 </ b> A of the carrier 3 is provided with an electric caliper 7 supported so as to be movable along the axial direction of the disk rotor 2. The electric caliper 7 includes a caliper body 8, a piston unit 9 (pressing unit), and a motor / control device unit 10.

  The caliper main body 8 has a cylindrical cylinder portion 11 formed of a through hole having one end opposed to one side of the disk rotor 2, and a claw portion 12 extending from the cylinder portion 11 to the opposite side across the disk rotor 2. A pair of boss portions 13 extending from the cylinder portion 11 substantially in the diameter direction and to which the pair of slide pins 6 and 6 are respectively attached are integrally formed. A guide bore 15 into which the piston 14 of the piston unit 9 is slidably fitted, and a female screw 18 to which a male screw 17 of an adjustment screw 16 attached to the piston unit 9 is screwed, are fitted on the inner peripheral surface of the cylinder part 11. Is formed.

  As shown in FIG. 5, the piston unit 9 includes a bottomed cylindrical piston 14, a ball ramp mechanism 19 (rotation-linear motion conversion mechanism) and a differential reduction mechanism 20 (deceleration mechanism) housed in the piston 14. ) And the pad wear compensation mechanism 21 are integrated (unitized). 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 includes a linear motion disk 24 fixed to the bottom surface of the piston 14, a rotation disk 25 that can rotate and move in the axial direction, and a ball groove 26 formed on the surfaces facing each other. 27 (inclined groove) and a ball 28 (rolling element) inserted. The rotating disk 25 is always urged toward the linear motion disk 24 by a spring 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 reduction mechanism 20 includes a rotary shaft 30, a ring-shaped external gear member 32 having two external teeth 32A and 32B that are rotatably fitted to the eccentric portion 31 of the rotary shaft 30 by bearings 31A and 31B, An internal tooth 33 that is formed on the rotating disk 25 of the ball ramp mechanism 19 and meshes with one external tooth 32A of the external gear member 32, and is rotatably supported by a bearing 35A with respect to the rotating shaft 30 and the external gear member 32 And a rotating member 35 having an inner tooth 34 that meshes with the other outer tooth 32B. A rotating disk 25 is rotatably supported at one end of the rotating shaft 30 by a bearing 25A. The other end portion side of the rotating shaft 30 protrudes from the piston unit 9 and extends into the motor unit 10, and an outer spline 36 is formed at the tip portion thereof.

  One end of the rotating member 35 is in contact with the end of the rotating disk 25 via a ball thrust bearing 37 and is pressed against the rotating disk 25 by a spring 29 to urge the rotating disk 25 toward the linearly moving disk 24. ing. The center distance between the external gear member 32 and the rotating disk 25 in which the external teeth 32A and the internal teeth 33 mesh with each other, and the center distance between the external gear member 32 and the rotary member 35 in which the external teeth 32B and the internal teeth 34 mesh with each other. Since it is determined by one rotating shaft 30, the positioning accuracy can be increased. Further, a lateral force is applied to the rotating disk 25 and the rotating member 35 by the reaction force caused by the meshing of these gears. However, due to the biasing force of the spring 29 and the reaction force from the brake pad 5 transmitted to the rotating disk 25. It is possible to prevent the rotating disk 25 and the rotating member 35 from falling and to eliminate the rattling and prevent the generation of vibration and noise.

  Then, by rotating the rotary shaft 30 and revolving the external gear member 32, the rotary disk 25 having the internal teeth 33 meshing with the external teeth 32A of the external gear member 32 and the internal teeth 34 meshing with the external teeth 32B are provided. By rotating differentially with the rotating member 35 and fixing one of them, the other can be rotated at a predetermined reduction ratio. In addition, by making the number of teeth of the external teeth 32A and the external teeth 32B of the differential reduction mechanism 20 the same, the external teeth 32A and the external teeth 32B can be machined integrally, and the manufacturing cost can be reduced. it can.

  The pad wear compensation mechanism 21 includes a limiter 38 mounted between the linear motion disk 24 and the rotation disk 25 of the ball ramp mechanism 19, an adjustment screw 16 coupled to the rotation member 35 of the differential reduction mechanism 20, and a rotation. A cup 38B coupled to the member 35 and a wave washer 38A interposed between the piston 14 and the cup 38B are provided. As shown in FIG. 6, the limiter 38 allows relative rotation of the linear motion disk 24 and the rotating disk 25 within a certain range, and the rotating disk rotates by a certain amount of play to form the rotating disk 25. After the projected portion 25B comes into contact with a contact portion 38D attached to one end of a coil spring 38C (spring means) which is a torsion spring, the spring in the return direction by the coil spring 38C with respect to the rotation of the rotary disk 25 Power is given. The adjustment screw 16 has a male screw 17 (trapezoidal screw) formed on the outer peripheral portion thereof, and the male screw 17 is screwed to a female screw 18 (trapezoidal screw) formed on the inner peripheral portion of the cylinder portion 11 of the caliper body 8. Thereby, the connection of the rotating member 35 constituting the differential reduction mechanism 20 to the cylinder portion 11 can be used also as the adjustment screw 16 of the pad wear compensation mechanism 21, and the number of parts and the processing portion can be reduced. . The adjusting screw 16 is held together with the rotating member 35 by a wave washer 38A with a constant holding force against the rotation. By rotating the adjusting screw 16 against the holding force, the adjusting screw 16 is axially rotated by the relative rotation of the male screw 17 and the female screw 18. Can be moved to. Further, the adjusting screw 16 receives the reaction force from the rotating disk 25 via the thrust bearing 37 and the rotating 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, a resolver 40 that detects the rotational position of the motor 39, and a parking brake mechanism 41 that holds 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 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 rotation 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 rotation 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 that is attached to the tip of the motor rotor 48 inserted through the base plate 43 and is 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. In addition, the parking brake mechanism 41 operates a lock mechanism (not shown) by an electric actuator to lock the rotation of the rotor 48.

Next, the operation of the present embodiment configured as described above will be described.
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. FIG. 7 shows the electric disc brake 1 in a braking state. 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 vehicle controller detects the vehicle state such as the rotational speed of each wheel, the vehicle speed, the vehicle acceleration, the steering angle, and the vehicle lateral acceleration using various sensors, and the electric motor 39 is rotated based on these detections. By controlling, 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 rotating shaft 30 is rotated by the rotor 48 during braking, the external gear member 32 revolves due to the eccentric rotation of the eccentric portion 31, and the rotating disk 25 and the rotating member 35 meshed with the external teeth 32 </ b> A and 32 </ b> B of the external gear member 32. Rotates differentially. At this time, normally, the rotation of the rotating 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 rotating member 35. The rotation is securely locked. Therefore, the rotary disk 25 can rotate against the spring force of the coil spring 38C of the limiter 38.

  If the brake pads 4 and 5 are worn and the disk rotor 2 is not pressed even if the rotating disk 25 exceeds the range of play of the limiter 38, the spring force of the coil spring 38C of the limiter 38 acts on the rotating disk 25, The rotating disk 25 is fixed, and the adjusting screw 16 rotates against the holding force of the wave washer 38A together with the rotating member 35. 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 coil spring 38C of the limiter 38, and the piston 14 advances by the ball ramp mechanism 19. In this way, the piston unit 9 can be moved forward by the adjusting screw 16 as much as the brake pads 4 and 5 are worn, and the wear of the brake pads 4 and 5 can be compensated. The clearance with the rotor 2 can be kept constant. The electric disc brake 1 with the brake pads 4 and 5 worn is shown in FIG.

  At this time, the motor / control device unit 10 including the electric motor 39 together with the caliper body 8 moves in the direction away from the disk rotor 2 by the amount of wear of the brake pad 4 on the claw 12 side, whereas the piston 14 side The piston unit 9 including the ball ramp mechanism 19, the differential reduction mechanism 20, and the pad wear compensation mechanism 21 moves toward the disc rotor 2 by the amount of wear of the brake pad 5. As a result, the change in the position of the center of gravity of the electric caliper 7 with respect to the disk rotor 2 is reduced as compared with the conventional example described in Patent Document 1. Therefore, the bending moment of the arm portion 3A of the carrier 3 generated by the unsprung vibration or the like through the slide pin 6 due to the center of gravity of the electric caliper 7 being separated from the disk rotor 2 due to wear of the brake pads 4 and 5. Since the increase is reduced and the posture of the electric caliper 7 is stabilized, it is possible to reduce the occurrence of dragging due to rattle noise and slide pin slidability, uneven wear of the brake pads, and the like.

  Further, the outer spline 36 of the rotating shaft 30 slides in the inner spline 49 of the rotor 48 only during the wear compensation when the brake pads 4 and 5 do not press the disk rotor 2, and the brake pads 4 and 5 Since it does not slide at the time of braking to be pressed, a large torque of the electric motor 39 does not act on the spline coupling portion at the time of sliding, so that mechanical loss due to sliding resistance and wear on the tooth surfaces of the outer and inner splines 36 and 49 are reduced. Can do.

  Next, a second embodiment of the present invention will be described with reference to FIG. In addition, with respect to the said 1st Embodiment, the same code | symbol is attached | subjected to the same part, and only a different part is demonstrated in detail.

  In the first embodiment, the end portion having the outer spline 36 of the rotating shaft 30 protrudes from the piston unit 9 and is inserted into the inner spline 49 provided in the rotor 48 of the electric motor 39. On the other hand, as shown in FIG. 9, in the electric disc brake 52 according to the second embodiment, the rotating shaft 30 is formed in a substantially cylindrical shape, provided with an inner spline 30 </ b> A on the inner periphery, and the rotor 48. A shaft portion 53 (rotating shaft) having an outer spline 53A is projected, and the shaft portion 53 is inserted into the rotating shaft 30 so that the outer spline 53A and the inner spline 30A are spline-coupled.

  Thereby, while transmitting a rotational force between the motor rotor 48 and the rotating shaft 30, these can be relatively moved to an axial direction, and there can exist an effect | action and effect similar to the said 1st Embodiment.

  In the first and second embodiments, the rotary shaft 30 and the rotor 48 transmit rotational force and can be moved relative to each other in the axial direction by spline coupling. The rotational force may be transmitted by coupling or the like, and may be relatively movable in the axial direction. In the first and second embodiments, a roller ramp mechanism can be used instead of the ball ramp mechanism, and other known rotation-linear motion conversion mechanisms can also be used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a non-braking state in an electric disc brake according to a first embodiment of the present invention. It is a side view of the electric disc brake shown in FIG. It is a top view of the electric disc brake shown in FIG. It is a front view of the electric disc brake shown in FIG. It is a longitudinal cross-sectional view of the piston unit of the electric disc brake shown in FIG. FIG. 2 is an exploded perspective view of a limiter and a rotating disk of the electric disk brake shown in FIG. 1. FIG. 2 is a longitudinal sectional view showing a braking state in the electric disc brake shown in FIG. 1. FIG. 2 is a longitudinal sectional view showing a state where a brake pad is worn in the electric disc brake shown in FIG. 1. In the electric disk brake which concerns on 2nd Embodiment of this invention, it is a longitudinal cross-sectional view which shows a non-braking state.

Explanation of symbols

  1 electric disc brake, 2 disc rotor, 4, 5 brake pad, 8 caliper body, 9 piston unit (pressing unit), 19 ball ramp mechanism (rotation-linear motion conversion mechanism), 20 differential reduction mechanism (deceleration mechanism), 21 Pad wear compensation mechanism, 30 rotating shaft, 39 electric motor, 53 shaft (rotating shaft)

Claims (5)

The caliper body is provided with an electric motor, a speed reduction mechanism that reduces the rotation of the electric motor, and a rotation-linear motion conversion mechanism that converts the rotation of the speed reduction mechanism into a linear motion. In the caliper floating type electric disk brake that generates a braking force by pressing the brake pad against the disk rotor via the pressing member,
The speed reduction mechanism and the rotation-linear motion conversion mechanism are integrated into the pressing member to form an integrated pressing unit. When the brake pad is worn, the pressing unit follows the wear of the brake pad. An electric disc brake that moves in a direction away from the electric motor. 2. The pressing unit includes a pad wear compensation mechanism that adjusts a position of the brake pad with respect to the disk rotor during non-braking in accordance with wear of the brake pad. Electric disc brake. The rotary shaft for transmitting a rotational force between the electric motor and the speed reduction mechanism is connected to the electric motor or the speed reduction mechanism so as to be movable in the axial direction. The electric disc brake described in 1. 4. The electric disc brake according to claim 3, wherein the rotating shaft protrudes from the pressing unit and is connected to the electric motor so as to be movable in the axial direction. The electric disk brake according to claim 3, wherein the rotating shaft protrudes from the electric motor and is movably connected to the speed reduction mechanism.

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