JP2000346109A - Motor operated disc brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge a servo ratio without causing the generation of bending moment loads, and to reduce drag of brake pads in a motor-operated disc brake. SOLUTION: First and second ball ramp mechanisms 11, 12 and an electric motor 10 are provided in a caliper body 3. The rotation of a rotor 19 of the electric motor 10 is converted into linear motion by the first and second ball ramp mechanisms 11, 12 to uniformly press and release brake pads 5, 6 on and from a disc rotor through a piston 25 and a claw part 4 to generate braking force, and to prevent drag. A power ratio can be expanded by reducing the inclination of ball grooves 22, 23, 29 of the first and second ball ramp mechanisms 11, 12. Further, the generation of bending moment loads can be prevented by arranging the ball grooves 22, 23, 28, 29 along the circumferential directions of a central disc 15, first and second discs 20, 26 at equal intervals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric disc brake device for generating a braking force by the rotation of an electric motor.

[0002]

2. Description of the Related Art A so-called "dry brake" in which a braking force is generated by the output of an electric motor without using a brake fluid as a braking device for a vehicle such as an automobile.
Devices are known.

[0003] As a dry brake device, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-206766, the rotational motion of an electric motor is converted into advance and retreat of a piston by a ball screw mechanism, and a brake pad is disc-shaped by the piston. There is an electric disc brake device that generates a braking force by being pressed by a rotor. In this type of electric disc brake device, a brake pedal depression force (or displacement amount) by a driver is detected by a sensor, and a controller controls the rotation of the electric motor according to the detection to obtain a desired braking force. I have to.

Further, in the above-described electric disc brake device, various sensors are used to detect the vehicle state such as the rotation speed of each wheel, the vehicle speed, the vehicle acceleration, the steering angle, the vehicle lateral acceleration, etc. By controlling the rotation of the electric motor based on these detections, boost control, antilock control, traction control, vehicle stabilization control, and the like can be relatively easily incorporated.

[0005]

However, the above-mentioned conventional electric disk brake device using the ball screw mechanism has the following problems. In order to obtain a sufficiently large braking force by increasing the thrust of the piston, it is necessary to increase the output of the motor or to reduce the lead of the ball screw mechanism to increase the boosting ratio. However, when the output of the motor is increased, there arises a problem that the motor becomes larger and the power consumption increases. On the other hand, when reducing the lead of the ball screw, there is a limit to reducing the lead depending on the diameter of the ball.
There is a problem that a sufficient effect cannot be obtained.

Therefore, it is conceivable to increase the boost ratio by setting the thread groove of the ball screw mechanism to less than one pitch so that the lead can be set smaller than the diameter of the ball. However, in such a case, the ball does not circulate in the thread groove, and in order to ensure the operation of the ball screw mechanism, the ball is not completely filled in the thread groove and the ball is inserted. It is necessary to provide an area that does not exist. As a result, the thrust is not evenly generated in the entire thread groove, and a moment load is generated.
It is necessary to increase the strength of these support parts, which causes a problem that the weight increases and the manufacturing cost increases.
Further, the special screw structure increases the processing cost.

Further, in the above-described electric disc brake, one brake pad is pressed against the disc rotor and the caliper is moved by the reaction force of the other brake pad due to the restriction on the installation space of the ball screw mechanism, the motor, and the like. A caliper floating type structure in which a brake pad is pressed against a disk rotor is employed. For this reason, it is necessary to increase the rigidity of the thrust transmission path from the thrust generating mechanism to the claw portion,
There is a problem that the case of the electric motor becomes thick and the weight increases. Furthermore, with the caliper floating type structure, it is difficult for the brake pad on the claw part to return when braking is released,
There is a problem that the brake pad is easily dragged.

The present invention has been made in view of the above points, and can increase the boosting ratio without increasing the moment load, and can increase the rigidity of the thrust transmission path. Further, it is another object of the present invention to provide an electric disc brake capable of preventing a brake pad from being dragged.

[0009]

According to a first aspect of the present invention, a pair of brake pads arranged on both sides of a disk rotor and a piston opposed to one of the pair of brake pads are provided. A claw portion that straddles the disk rotor and faces the other of the pair of brake pads; an electric motor that rotates the rotor; and a first mechanism that converts the rotational motion of the rotor into linear motion to move the piston forward and backward. An electric disc brake comprising a ball ramp mechanism and a second ball ramp mechanism for converting the rotational motion of the rotor into a linear motion to move the claw portion forward and backward,
The first and second ball ramp mechanisms include a central disk that rotates with the rotor, and a first disk disposed opposite to one end of the central disk and connected to the piston.
A disk, and a second disk disposed opposite to the other end of the central disk and connected to the claw portion, the second disk being formed at a facing portion of each of the central disk and the first and second disks. A ball is interposed between the ball grooves.

With this configuration, when the rotor is rotated by the electric motor, the first and second ball ramp mechanisms move the piston and the claw, respectively, and press and separate the brake pad against the disk rotor to brake. And release the brake. At this time, the thrust is evenly transmitted by the balls disposed between the central disks of the first and second ball ramp mechanisms and the ball grooves of the first and second disks.

The invention according to claim 2 is characterized in that a pair of brake pads arranged on both sides of the disk rotor, a piston provided on the caliper body facing one of the pair of brake pads, A claw portion that is fixed and faces the other of the pair of brake pads across the disk rotor; an electric motor provided on the caliper body; and a piston that converts a rotational motion of the rotor of the electric motor into a linear motion. A ball ramp mechanism for advancing and retreating the disc, wherein the ball ramp mechanism is disposed between the disc rotor and the electric motor and fixed to the caliper body; and A movable disk disposed between a disk rotor and the fixed disk and connected to the piston; A disk interposed between ball grooves formed in an opposing portion of the disk and the fixed disk, wherein the movable disk and the rotor of the electric motor are connected through the inside of the fixed disk. And

With this configuration, when the rotor is rotated by the electric motor, the movable disk of the ball ramp mechanism moves the piston and presses one of the brake pads against the disk rotor. The other brake pad is pressed against the disk rotor to generate a braking force. At this time, the ball ramp mechanism can be arranged near the disk rotor, and the rigidity of the thrust transmission path from the ball ramp mechanism to the pawl can be increased.

[0013]

Embodiments of the present invention will be described below 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 3, the electric disc brake 1 of the first embodiment has a caliper body 3 disposed on one side (usually inside the vehicle body) of a disc rotor 2 that rotates with wheels. The caliper body 3 is provided with a claw portion 4 extending to the opposite side across the disk rotor 2. Brake pads 5, 6 are provided on both sides of the disk rotor 2, that is, between the disk rotor 2 and the caliper body 3 and between the disk
Is provided. The brake pads 5 and 6 are movably supported along the axial direction of the disk rotor 2 by a carrier 7 fixed to the vehicle body.
Is guided by a carrier 7 via a slide pin 8 so as to be movable in the axial direction of the disk rotor 2.

A substantially cylindrical housing 9 of the caliper body 3
Inside, the electric motor 10, the first ball ramp mechanism 11, the second
A ball disc mechanism 12, a pad wear compensation mechanism 13, and a rotation detector 14 (for example, a resolver) are provided.
It is rotatably supported by 16. A cover 17 is attached to the rear end of the housing 5.

The electric motor 10 includes a stator 18 fixed to the inner peripheral portion of the housing 9 and a rotor 19 attached to the outer peripheral portion of the cylindrical portion 15a of the central disk 15 so as to face the inner peripheral portion of the stator 18. In addition, the rotor 19 can be rotated by a desired angle in response to a control signal (electric signal) from a controller (not shown), and can be rotated with a desired torque.

The first ball ramp mechanism 11 includes a central disk
And a cylindrical portion provided to face one end surface of the central disk 15 and inserted into the cylindrical portion 15a of the central disk 15.
The first disk 20a is integrally formed with a first disk 20 and a ball 21 (steel ball) interposed therebetween.

As shown in FIG. 4, three ball grooves 22 and 23 are formed on the opposing surfaces of the center disk 15 and the first disk 20 so as to extend in an arc along the circumferential direction. The three ball grooves 22 and 23 are extended at equal central angles (for example, 90 °) and arranged at equal intervals. As shown in FIG. 5, each of the ball grooves 22 and 23 is inclined in the same direction with a height difference Δh from the deepest part a at one end to the shallowest part b at the other end. Also, the central disk 15
Of each ball groove 22 of the first disk 20
In the original position, the deepest portions a are arranged so as to face each other, and the ball 21 is inserted between the deepest portions a. As a result, when the center disk 15 rotates with respect to the first disk 20, the ball 21 rolls in the ball grooves 22, 23 toward the shallowest portion b, and the first disk 20 moves in accordance with the rotation angle. It moves along the axial direction in a direction away from the center disk 15.

The rotation of the first disk 20 is restricted by inserting a pin 24 between the first disk 20 and the back metal of the brake pad 5, and the center disk 15 is rotated clockwise from its original position (rightward in FIG. 1). The first disk 20 moves to the left in FIG.
The brake pad 5 is pressed against the disk rotor 2 via a piston 25 (described later) attached to the disk 20.

The second ball ramp mechanism 12 includes a central disk
And a second disk 26 integrally provided with a cylindrical portion 26a provided so as to face the other end surface of the central disk 15 and surrounding the central disk 15 and the first disk 20.
And a ball 27 (steel ball) interposed between them.

As shown in FIG. 6, three ball grooves 28 and 29 are formed on the opposing surfaces of the center disk 15 and the second disk 26 so as to extend in an arc along the circumferential direction. Similarly to the first ball ramp mechanism 11, the three ball grooves 28 and 29 are equally extended and equally spaced within a range of a central angle of 90 °. As shown in FIG.
Each of the ball grooves 28 and 29 is inclined in the same direction with a height difference Δh from the deepest part a at one end to the shallowest part at the other end b. Further, each ball groove 28 of the central disk 15 and each ball groove 29 of the second disk 26 are arranged so that the deepest portions a are opposed to each other at the original position, and are located between the deepest portions a. Ball 27 is loaded. As a result, when the center disk 15 rotates with respect to the second disk 26, the ball 27 rolls in the ball grooves 28 and 29 toward the shallowest portion b, and the second disk 26 is rotated according to the rotation angle. It moves along the axial direction in a direction away from the center disk 15.

The cylindrical portion 26a of the second disk 26 has a claw 4
Are integrally connected, and the first disk 20 is inserted into an opening 31 provided in the claw portion 4 on the outer peripheral side of the disk rotor 2.
The first disk 20, the claw portion 4 and the second disk 20 are slidably inserted through a pair of slide pins 33 screwed to the claw portion 4.
26 are guided so as to be relatively movable along the axial direction of the disk rotor 2, and their relative rotation is restricted. Then, when the center disk 15 rotates clockwise from its original position, the second disk 26 moves rightward in FIG. 1 and presses the brake pad 6 to the disk rotor 2 via the claw portion 4. Has become. The first disk 20
And the second disk 26 is biased toward the central disk 15 by return spring means (not shown).

Next, the pad wear compensation mechanism 13 will be described. The piston 25 is screwed into a screw portion 36 (adjustment screw) formed on the inner peripheral surface of the cylindrical portion 20a of the first disk 20,
When rotated counterclockwise (counterclockwise as viewed from the right in FIG. 1, the same applies hereinafter), it advances toward the brake pad 5 side. A cylindrical slide member 37 is coaxially and integrally attached to the rear end of the piston 25 by bolts 38. A substantially cylindrical rotating member 39 rotatably inserted into the center disk 15 is connected to a rear end portion of the first disk 20 by a leaf spring 40, and a sliding member 37 is included in the rotating member 39. It is fitted via a direction clutch 41.

As shown in FIG. 8, the rotating member 39 is a leaf spring.
The first disc 20 is elastically positioned in the rotation direction by the first disc 20 by the first disc 20.
A predetermined relative rotation is allowed. The one-way clutch 41 allows only the clockwise rotation of the rotation member 39 with respect to the slide member 37, and integrally rotates the slide member 37 with respect to the counterclockwise rotation of the rotation member. I have. Further, the slide member 37 is connected to the one-way clutch 41 by a spline 42, and is relatively movable in the axial direction with respect to the rotating member 39 and the one-way clutch 41.

An arcuate engaging groove 43 having a predetermined central angle range along the circumferential direction is formed on the rear end surface of the rotating member 39. In the center disk 15, a substantially cylindrical retainer 44 facing the rear end of the rotating member 39 is mounted. An engaging pin 45 inserted into the engaging groove 43 of the rotating member 39 is attached to the retainer 44. When the center disk 15 and the first disk 20 rotate relative to each other within a predetermined range, the engagement pin 45 moves in the engagement groove 43, and the relative rotation between the center disk 15 and the first disk 20 is increased. When the distance exceeds the predetermined range, the engaging pin 45 comes into contact with the end of the engaging groove 43 to rotate the rotating member 39.
The engagement groove 43 and the engagement pin 45
Together, the transmission mechanism transmits only the rotational displacement of the central disk 15 exceeding a predetermined range.

In the rotation detector 14, a stator 47 is mounted on a bracket 46 mounted on the cover 17, and a rotor 49 is mounted on a retainer 44 so as to face the stator 47 in the radial direction. The rotational displacement of the center disk 15, that is, the rotational displacement of the rotor 19 of the electric motor 10 can be detected based on the electromotive force or output frequency generated in accordance with the rotation of the rotor 49 with respect to 47.

The operation of the first embodiment configured as described above will now be described.

During braking, when the rotor 19 of the electric motor 10, that is, the center disk 15 rotates clockwise in response to a control signal from a controller (not shown), the balls 21 of the first and second ball ramp mechanisms 11 and 12 rotate. , 27 roll along the grooves 22, 23 and the grooves 28, 29, respectively, to move the first disk 20 and the second disk 26 in opposite directions with respect to the axial direction of the central disk 15 (directions away from the central disk 15). ), And the brake pads 5 and 6 are pressed against the disk rotor 2 by the piston 25 and the claw portion 4 to generate a braking force. The rotational force acting on the brake pads 5 and 6 is supported by the carrier 7, and the caliper body 3 moves along the slide pins 8 of the carrier 7, so that the sliding surfaces on both sides of the disk rotor 2 run out. In addition, an error in the separation distance between the brake pads 5 and 6 with respect to the disk rotor 2 before braking (the starting position at the time of braking) is absorbed. The braking force can be controlled based on the rotational displacement of the center disk 15 detected by the rotation detector 14.

The rotation angle θ of the central disk 15 and the first and second angles
The relationship between the axial displacement δ of the disks 20, 26 and the positions of the balls 21, 27 is shown in FIGS. FIG. 9 shows that the rotation angle θ of the center disk 15 is 0 ° and the first and second disks 20 and 26
FIG. 10 shows a state where the axial displacement δ is 0, FIG. 10 shows a state where the rotation angle θ is 90 ° and the axial displacement δ is ΔL / 2 + ΔL / 2, and FIG. At 180 ° (maximum rotation angle), a state in which the axial displacement δ becomes ΔL + ΔL (maximum displacement) is shown.

At this time, the first and second ball ramp mechanisms 11 and 12 convert the rotary motion into a linear motion. However, by reducing the inclination of the ball grooves 22 and 23 and the ball grooves 28 and 29, the rotational displacement is reduced. Can be set sufficiently small, the boost ratio can be increased, the output of the electric motor 10 can be small, the power consumption can be reduced, and the motor can be reduced in size.

Also, three ball grooves 22, 2 are provided in the opposed portions of the central disk 15 and the first and second disks 22, 23 respectively.
By arranging 3, 28, and 29 at equal intervals along the circumferential direction, thrust is transmitted evenly between them, so that no moment load is generated and the brake pads 5,
6 can be pressed evenly, and a stable braking force can be obtained. As a result, the moment load acting on the support portions of the central disk 15 and the first and second disks 22 and 23 can be reduced, and the required strength can be reduced. Therefore, the size and weight of each portion can be reduced. Can be.

Further, first and second ball ramp mechanisms
The ball grooves 22 and 23 and the ball grooves 28 and 29 of 11 and 12 are arranged on the same circumference on both sides of the central disk 15, and between the ball grooves 22 and 23 and between the ball grooves 28 and 29, respectively. Since the interposed balls 21 and 27 are always arranged at the same position with respect to the disk portion of the central disk 15 (FIG. 9).
And FIG. 11), the load acting on the balls 21 and 27 due to the reaction force when the brake pads 5 and 6 are pressed during braking is directly applied to the portion of the central disk 15 between the balls 22 and 23 of the disk portion. Can be supported. As a result, only the compressive force from the balls 22 and 23 acts on the central disk 15 and no moment load or the like acts on the central disk 15, so that sufficient support rigidity can be obtained and the required strength is small. Therefore, the size and weight of each part can be reduced.

Further, first and second ball ramp mechanisms 11, 12 for driving the brake pads 5, 6 on both sides of the disk rotor 2 are arranged adjacent to the disk rotor 2,
By arranging the electric motor 10 on the outside, the first and second ball ramp mechanisms 11, 12 and the brake pads 5,
6 can be made sufficiently close, and the rigidity of the claw portion 4 and the cylindrical portion 26a for transmitting thrust therebetween can be easily obtained, so that the required strength can be reduced and the size and weight of each portion can be reduced. be able to.

At the time of release of braking, when the electric motor 10 is rotated in the reverse direction and the center disk 15 is rotated counterclockwise to the original position, the first disk 20 is returned by the spring force of the return spring means.
And the piston 25 and the pawl 4 together with the second disc 26
Recedes from the disk rotor 2 to the brake pads 5,
6 is separated and the braking is released. At this time, the piston is restricted by the first and second ball ramp mechanisms 11 and 12.
25 and the claw portion 4 are retracted by the same distance, so that the brake pads 5 and 6 on both sides can be evenly separated from the disk rotor 2, and the drag of the brake pads 5 and 6 can be reduced.

Next, the operation of the pad wear compensation mechanism 13 will be described with reference to FIG. When there is no wear on the brake pads 5 and 6, or after the wear adjustment described below is performed, the center disk 15 rotates a predetermined range between the non-braking position and the braking position of the brake pads 5 and 6. Move,
The engagement pin 45 is also in the non-braking position in the engagement groove 43 (FIG. 12).
(A)) and a predetermined range is moved between the braking position (FIG. 12 (B)).

When the brake pads 5 and 6 are worn, the amount of displacement of the center disk 15 is increased by the amount of wear during braking, and the engaging pin 45 contacts the end of the engaging groove 43 to rotate the rotating member 39 clockwise. (FIG. 12 (C)). At this time, the one-way clutch 41 allows the clockwise rotation of the rotation member 39 with respect to the slide member 37, so that the slide member 37, that is, the piston 25 does not rotate. Thereafter, when the braking is released and the engaging pin 45 moves to the non-braking position, the rotating member 39 rotates counterclockwise to the original rotating position. At this time, since the one-way clutch 41 prevents the relative rotation between the slide member 37 and the rotating member 39, the slide member 37, that is, the piston 25 rotates counterclockwise with the rotating member 39 (FIG. 12).
(D)), the adjusting screw part 36 advances the piston 25 toward the brake pad 5 by the amount of wear of the brake pads 5 and 6.

In this way, the piston 25 is advanced by an amount corresponding to the wear of the brake pads 5 and 6, so that even if the strokes of the first and second ball ramp mechanisms 11 and 12 are short, the wear of the brake pads 5 and 6 can be reduced. Compensation can be made and long term use of the brake pads can be enabled.

In the above embodiment, the central disk 1
5, three ball grooves 22, 23, 28, and 29 are provided on opposing surfaces of the first and second disks 20, 26, respectively, but the present invention is not limited to this. Four or more can be arranged, and thrust can be transmitted evenly by three or more ball grooves.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

As shown in FIGS. 13 to 16, an electric disc brake 50 according to the second embodiment has a caliper on one side (usually inside the vehicle body) of a disc rotor 51 which rotates with wheels (not shown). A main body 52 is disposed, and the caliper main body 52 is formed in a substantially C-shaped
And a claw portion 53 extending to the opposite side across the rim is integrally connected by a bolt 53A. Brake pads 54 and 54 are provided on both sides of the disk rotor 51, that is, between the disk rotor 51 and the caliper body 52 and between the tip of the claw 53.
55 are provided. The brake pads 54 and 55 are supported by a carrier 56 fixed to the vehicle body so as to be movable in the axial direction of the disk rotor 51, so that the braking torque is received by the carrier 56.
52 is slidably guided along the axial direction of the disk rotor 51 by a slide pin 57 attached to a carrier 56.

An electric motor 59 and a rotation detector 60 are provided in a substantially cylindrical case 58 of the caliper main body 52 to which the annular flange 53B of the claw 53 is connected. Is inserted into the rotor 62 of the electric motor 59 from the side of the annular flange 53B. A cover 63 is attached to the rear end of the case 58 with bolts 63A.

The electric motor 59 is rotatable by the bearings 65 and 66 on the stator 64 fixed to the inner peripheral portion of the case 58 and opposed to the inner peripheral portion of the stator 64 by the bearing 58 and 66, and moves in the axial direction. And a rotatably supported rotor 62.
The rotation detector 60 includes a resolver stator fixed to a resolver case 67 attached to the case 52 by bolts 67A.
68, and a resolver rotor 69 fixed to the rotor 62 so as to face the resolver stator 68, and detects the rotation speed (rotation speed) of the rotor 62 based on the relative rotation of these. The cover 63 has an electric motor 59 and a rotation detection
The electric motor 59 rotates the rotor 62 by a desired angle at a desired torque in response to a control signal (electric signal) from a controller (not shown). It has become.
The connector 70 and the cable 71 are inclined with respect to the axial direction of the disk rotor 51 and extend radially outward to avoid interference with members such as arms, links, knuckles, and struts of the suspension device of the vehicle. Have been.

The ball lamp unit 61 includes an electric motor 59
A ball ramp mechanism 72 that converts the rotational motion of the rotor 62 into a linear motion, and a piston 73 that presses the brake pad 54
And an adjustment nut 74 interposed therebetween, and a limiter mechanism 75 for transmitting the rotation of the ball ramp mechanism 72 to the adjustment nut 74.

The ball ramp mechanism 72 is in contact with the flange portion 53B of the claw portion 53, and is fixed to an annular fixed disk 77 by a pin 76 so as not to rotate, and a movable disk 78 disposed opposite to the fixed disk 77. And a ball 79 (steel ball) interposed between them. The movable disk 78 is integrally formed with a cylindrical portion 80 that is inserted into the fixed disk 77 and extends to the inside of the case 58. The cylindrical portion 80 is spline-coupled to the inner peripheral portion of the rotor 62. Play is provided.

Similarly to the second ball ramp mechanism of the first embodiment, three opposing surfaces of the fixed disk 77 and the movable disk 78 are each provided with three ball grooves 81, which extend in an arc along the circumferential direction. 82 are formed, and a ball 79 is inserted between them.
The three balls 79 are in the ball groove 8 by the relative rotation with 78.
The fixed disk 77 and the movable disk 78 move relative to each other in the axial direction according to the rotation angle by rolling in the insides 1 and 82.

The adjusting nut 74 comprises a cylindrical portion 83 and a flange portion 84 formed outside one end thereof.
Is inserted into the cylindrical portion 80 of the movable disk 78, and is rotatably supported by a slide bearing 85. The flange portion 84 is in contact with one end of the movable disk 78 and is rotatably supported by a thrust bearing 86. The cylindrical portion 83 of the adjusting nut 74 extends to the inside of the rotor 62 in the case 58, and a limiter mechanism 75 is mounted on the outer periphery of the distal end.

The limiter mechanism 75 is a cylindrical part of the adjusting nut 74.
A limiter 87 and a spring holder 88
Are rotatably fitted to each other, and are connected to each other by a coil spring 89. The limiter 87 and the spring holder 88 are engaged with each other so as to be able to rotate relative to each other within a predetermined range, and a predetermined set load is applied to the rotation direction by a coil spring 89. Accordingly, the coil spring 89 can be rotated clockwise (clockwise as viewed from the left in FIG. 13, the same applies to the second embodiment hereinafter) against the set load of the coil spring 89. An engagement concave portion 87A formed in the limiter 87 is provided with an engagement convex portion
The limiter 87 can rotate relative to the cylindrical portion 80 within a predetermined range. A clutch spring 90 (coil spring) is wound around the outer periphery of the tip of the cylindrical portion of the adjustment nut 74, and one end of the clutch nut is connected to a spring holder 89. The diameter of the clutch spring 90 is increased by torsion. By acting as a one-way clutch by reducing the diameter, only the clockwise rotation of the spring holder 89 is transmitted to the cylindrical portion 83 of the adjustment nut 74.

The piston 73 is screwed into a screw portion 91 formed on the inner periphery of the adjusting nut 74, and advances toward the brake pad 54 when the adjusting nut 74 rotates clockwise with respect to the piston 73. It has become. In the cylindrical portion 83 of the adjustment nut 74, a rotation preventing rod 92 whose one end is fixed to the resolver case 67 by a nut 92A is inserted, and the other end of the rotation preventing rod 92 is slidable on the piston 73 in the axial direction. And is engaged so as to restrict rotation. A plurality of disc springs 95 are interposed between a flange portion 93 formed in an intermediate portion of the rotation preventing rod 92 and a flange portion 94 formed in the cylindrical portion 83 of the adjustment nut 74, and the spring force is provided. The adjustment nut 74 is biased rightward in FIG. And the non-rotating rod 92 is
The urging force (set load of the disc spring 95) on the adjustment nut 74 can be adjusted by moving the axial position of.

The ball ramp mechanism 72, the adjusting nut 74, and the piston 73 are provided with a case 96 for covering them and integrally sub-assembling the ball lamp unit 61. The case 96 is adjusted with the front end flange of the case 96. nut
A wave washer 97 for providing an appropriate resistance to the rotation of the adjustment nut 74 is interposed between the flange portion 84 and the flange portion 84. In the drawing, reference numeral 98 denotes a piston boot, and 99 denotes a pin boot.

The operation of the second embodiment configured as described above will now be described.

At the time of braking, when the rotor 62 of the electric motor 59 rotates clockwise with a predetermined torque in response to a signal from a controller (not shown), the spline joint is moved through the movable disc 80a of the ball ramp mechanism 72 via 80A. 78 rotates,
The ball 79 rolls along the ball grooves 81 and 82 to advance the movable disk 78 toward the brake pad 54 along the axial direction. This thrust is transmitted to the adjustment nut 74 via the thrust bearing 86, and further transmitted to the piston 73 via the screw portion 91, so that one of the brake pads 54 is pressed against the disk rotor 51, and the reaction force thereof causes the caliper main body. 52 is the carrier
The claw portion 53 moves along the slide pin 57 of 56 and presses the other brake pad 55 against the disk rotor 51, and a braking force is generated according to the torque of the electric motor 59.

At this time, as in the first embodiment, by reducing the inclination of the ball grooves 81 and 82 of the ball ramp mechanism 72, the lead for the rotational displacement can be set sufficiently small, so that the boosting ratio is increased. Can be larger,
The output of the electric motor 59 can be small, and power consumption can be reduced and the size of the motor can be reduced. In addition, since the three ball grooves 81 and 82 are arranged at equal intervals along the circumferential direction in each of the fixed disk 77 and the movable disk 78, the thrust is transmitted evenly between them, so that the bending moment load is Without causing brake pads
54 and 55 can be pressed evenly, and a stable braking force can be obtained. As a result, the bending moment load acting on the support portions of the fixed disk 77 and the movable two disk 78 can be reduced, and the required strength can be reduced. Therefore, the size and weight of each portion can be reduced.

A ball ramp mechanism 72 for driving the brake pads 5 and 6 on both sides of the disk rotor 2 is arranged adjacent to the disk rotor 51 and fixed inside the substantially C-shaped claw 53. By arranging the electric motor 59 on the outside, the distance between the ball ramp mechanism 72 and the brake pads 5 and 6 can be sufficiently reduced, and the thrust can be directly transmitted by the claw 53. With this, the electric motor
Since the case 58 of 59 does not directly receive the load at the time of braking, it becomes possible to make the case 58 thinner and use lightweight materials,
It is possible to promote weight reduction and heat radiation of the electric motor 59. In addition, since the reaction force at the time of braking does not directly act on the bearing of the rotor 62, the structure of the bearing of the electric motor 59 can be simplified.

When the brake is released, the electric motor 59 is rotated in the reverse direction, and the movable disc 78 is rotated counterclockwise to the original position.
The adjustment nut 74 and the piston 73 are retracted, the brake pads 54 and 55 are separated from the disk rotor 51, and the braking is released.

Next, compensation of wear of the brake pads 54 and 55 will be described with reference to FIGS. Since the relative positional relationship between the piston 73 and the brake pad 54 and between the claw portion 53 and the brake pad 55 are the same, FIGS.
In FIG. 18, only the relationship between the piston 73 and the brake pad 54 is shown.

When there is no wear on the brake pad 54 or after the wear adjustment described later is performed, as shown in FIG. 17, during braking, the rotation of the rotor 62 causes the piston 73 to rotate.
When the brake pad 54 moves forward from the non-braking position (A) by the pad clearance C to the braking start position (B) where the brake pad 54 contacts the disk rotor 51, the engaging projection 80B of the cylindrical portion 80 of the movable disk 78 is moved to the limiter. It rotates along the engaging concave portion 87A of 87 and moves from one end to the other end of the engaging concave portion 80B. Further, when the piston 73 presses the brake pad 54 against the disk rotor 51 and moves to the braking position (D), the engaging projection 80B rotates the limiter 87 clockwise, and the rotational force is applied to the coil spring 89 and the clutch spring. It is transmitted to the adjustment nut 74 via 90. At this time, the piston
Since 73 presses the brake pad 5 and a large frictional force is generated in the screw portion 91 between the piston 73 and the adjustment nut 74, the coil spring 89 bends and the adjustment nut 74 does not rotate. When the piston 73 retreats to the non-braking position (A) due to the reverse rotation of the movable disk 78 when the braking is released, the engaging projection 80B abuts against one end of the engaging recess 80B, and the limiter 62 and the spring holder 88 are engaged. Is rotated counterclockwise, but the piston 73 does not rotate because the clutch spring 90 expands in diameter and idles. In this way, pad wear is not adjusted and constant pad clearance is maintained.

When the brake pad 54 is worn, as shown in FIG. 18, during braking, the brake pad 54 is moved from the non-braking position (A) to the position (B) by the pad clearance C due to the clockwise rotation of the rotor 62 during braking. Move up to the engaging convex
Even if 80B moves from one end of the engagement recess 87A to the other end,
The piston 73 does not press the brake pad 54 due to the wear W. When the rotor 62 further rotates, the movable disk 78
And the adjustment nut 74 is positioned toward the disk rotor 51 (D)
The piston 73 moves forward to bring the brake pad 54 into contact with the disk rotor 51. During this time, the engagement projection 80B rotates the limiter 87 clockwise, and the rotational force is applied to the adjustment nut via the coil spring 89 and the clutch spring 90.
However, since the piston 73 does not press the brake pad 54 and a large frictional force is not generated in the screw portion 91 between the piston 73 and the adjustment nut 74, the adjustment nut 74 is transmitted.
Rotates clockwise to further advance the piston 73 toward the brake pad 54 to adjust the wear of the pad. And
When the piston 73 moves to the position (E) at which the brake pad 54 is pressed against the disk rotor 51, a large frictional force is generated in the screw portion 91 between the piston 73 and the adjusting nut 74.
The bending of the coil spring 89 causes the rotation of the adjustment nut 74 to stop. When the piston 73 is retracted to the non-braking position (A) by the counterclockwise rotation of the rotor 62 at the time of braking release, the engaging projection 80B comes into contact with one end of the engaging recess 87A, and the limiter 87 is rotated counterclockwise. However, since the clutch spring 90 expands in diameter and idles, the adjustment nut 74 does not rotate. In this manner, the gap W between the brake pad 54 and the piston 73 at the non-braking position caused by the wear is reduced to W ', and one operation is performed by a fixed percentage of the wear amount of the brake pad 54. Thus, the piston 73 can be advanced from the adjustment nut 74 to the brake pad 54 side. By repeating this, the wear of the pad can be adjusted, and the same effect as in the first embodiment can be obtained.

[0058]

As described above in detail, according to the electric disc brake of the first aspect of the present invention, the pistons and the pawls are moved by the first and second ball ramp mechanisms so that the brake pads on both sides are disc rotored. Press evenly,
Since they can be separated, it is possible to prevent the brake pad from being dragged. Further, since thrust can be transmitted evenly by the balls interposed between the central discs of the first and second ball ramp mechanisms and the ball grooves of the first and second discs, the bending acting on these support portions can be transmitted. Moment load can be reduced.

According to the electric disc brake of the second aspect of the present invention, the ball ramp mechanism is disposed near the disc rotor, and the thrust of the ball ramp mechanism can be directly transmitted to the claw portion. The case does not directly receive the load at the time of braking, the case can be made thinner and a lightweight material can be used, and the weight can be reduced and the heat dissipation of the electric motor can be promoted. Further, since the reaction force at the time of braking does not directly act on the bearing of the rotor, the structure of the bearing of the electric motor can be simplified.

[Brief description of the drawings]

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

FIG. 2 is a plan view of the apparatus of FIG.

FIG. 3 is a side view of the apparatus of FIG. 1;

FIG. 4 is a front view showing an arrangement of ball grooves of a first ball ramp mechanism of the apparatus of FIG. 1;

5 is a cross-sectional view of the ball groove of FIG. 4 taken along line BB.

FIG. 6 is a front view showing an arrangement of ball grooves of a second ball ramp mechanism of the apparatus shown in FIG. 1;

7 is a cross-sectional view of the ball groove of FIG. 6 taken along line CC.

FIG. 8 is a longitudinal sectional view of the cylindrical portion and the rotating member of the first disk taken along line AA in FIG. 1;

FIG. 9 is a diagram showing axial displacements of first and second disks, ball grooves, and positions of balls when the rotation angle of the central disk is 0 °.

FIG. 10 shows a first case in which the rotation angle of the center disk is 90 °.
FIG. 8 is a diagram illustrating axial displacement of a second disk, positions of ball grooves, and positions of balls.

FIG. 11 is a diagram showing the axial displacement of the first and second disks, the positions of the ball grooves and the balls when the rotation angle of the center disk is 180 °.

FIG. 12 is an explanatory diagram showing an operation of a pad wear compensation mechanism of the apparatus of FIG.

FIG. 13 is a longitudinal sectional view of an electric disc brake according to a second embodiment of the present invention.

FIG. 14 is a side view showing the device of FIG. 13 partially broken away.

15 is a plan view showing the device of FIG. 13 with a part cut away.

FIG. 16 is a front view showing the device of FIG. 13 partially broken away.

FIG. 17 is an explanatory view showing the operation of the pad wear compensation mechanism of the apparatus shown in FIG. 13 when the pad has no wear.

FIG. 18 is an explanatory view showing an operation when the pad of the pad wear compensation mechanism of the apparatus of FIG. 13 is worn.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric disc brake 2 Disc rotor 4 Claw 10 Electric motor 11 1st ball ramp mechanism 12 2nd ball ramp mechanism 15 Central disc 19 Rotor 20 1st disc 22,23,28,29 Ball groove 21,27 Ball 25 Piston 26 2nd disc 50 electric disc brake 51 disc rotor 52 caliper main body 53 pawl 54,55 brake pad 59 electric motor 62 rotor 72 ball ramp mechanism 73 piston 77 fixed disc 78 movable disc 79 ball

Continued on the front page F term (reference) 3J058 AA43 AA48 AA53 AA63 AA73 AA78 AA87 BA16 BA37 BA62 BA63 BA68 CC15 CC25 CC35 CC58 FA01

Claims (2)

[Claims] 1. A pair of brake pads arranged on both sides of a disk rotor, a piston facing one of the pair of brake pads, and a claw portion straddling the disk rotor and facing the other of the pair of brake pads. An electric motor for rotating the rotor, and a first for moving the piston forward and backward by converting the rotational movement of the rotor into a linear movement.
An electric disc brake comprising a ball ramp mechanism and a second ball ramp mechanism for converting the rotational motion of the rotor into a linear motion to move the claw portion forward and backward, wherein the first and second ball ramp mechanisms are: A central disk rotating with the rotor, a first disk disposed opposite one end of the central disk and connected to the piston;
A disk, and a second disk disposed opposite to the other end of the central disk and connected to the claw portion, the second disk being formed at a facing portion of each of the central disk and the first and second disks. An electric disc brake characterized in that balls are interposed between ball grooves. 2. A pair of brake pads arranged on both sides of a disk rotor, a piston provided on a caliper body facing one of the pair of brake pads, and straddling the disk rotor fixed to the caliper body. A claw portion facing the other of the pair of brake pads,
An electric disc brake comprising: an electric motor provided on the caliper main body; and a ball ramp mechanism for converting a rotational motion of a rotor of the electric motor into a linear motion to move the piston forward and backward. A fixed disk disposed between the disk rotor and the electric motor and fixed to the caliper body, and a movable disk disposed between the disk rotor and the fixed disk and connected to the piston. A ball interposed between ball grooves formed in a portion facing the movable disk and the fixed disk, wherein the movable disk and the rotor of the electric motor are connected through the inside of the fixed disk. An electric disc brake, characterized in that: