JP2001343038A - Motor drive disc brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor driven disc brake which enables an increase in adjustment magnitude per single operation of a pad wear adjustment mechanism and also enables retraction of a piston by rotation of a motor. SOLUTION: When a first disc 62 is rotated by an electric motor 49, the first disc 62 and a limiter 101 rotate relatively to one another within the existing pad clearance, and then first disc 62 and a second disc 63 rotate relatively to each other, and then a piston 70 moves forward through a ball ramp mechanism 51. Subsequently, then both disc 62 and 63 are rotated integrally by the limiter 101, and the piston is moved further forward by the incremental wear of brake pads 44, 45 by means of a threaded portions 71, 73. With the brake pads 44, 45 being pressed against a disc rotor 41, the screw portions 71, 73 are locked up, and the first and second discs 62, 63 are caused to rotate in relative manner and then the piston 70 moves forward by means of the ball ramp mechanism 51. At the time of replacement of the brake pads 44, 45, the piston 70 can be moved backward by rotating the screw portions 71, 73 through the electric motor 49.

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 for generating a braking force by converting a rotary motion of a rotor of an electric motor into a linear motion of a piston.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 60-206766, the rotational movement of a rotor of an electric motor is converted into advance and retreat of a piston by a ball screw mechanism.
2. Description of the Related Art There is known an electric disc brake which generates a braking force by pressing a brake pad against a disc rotor with a piston. In this type of electric disc brake, a brake pedal depression force (or displacement amount) by a driver is detected by a sensor, and the controller controls the rotation of the electric motor according to the detection to obtain a desired braking force.

[0003] In the above-described electric disc brake,
By using various sensors, the vehicle speed such as the rotation speed of each wheel, the vehicle speed, the vehicle acceleration, the steering angle, the vehicle lateral acceleration, etc. are detected, and the controller controls 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.

Some electric disc brakes convert a rotary motion of an electric motor into a linear motion of a piston using a ball ramp mechanism. By using the ball ramp mechanism, the boosting ratio can be increased, and the miniaturization and power saving of the electric motor can be promoted. However, in the ball ramp mechanism, the rotation angle of the rotor is limited, and the displacement of the linear motion of the piston cannot be increased. Therefore, the piston cannot sufficiently follow the wear of the brake pad only by the displacement of the ball ramp mechanism. Therefore, by providing a pad wear follow-up mechanism, and utilizing the rotation of the motor at the time of braking or braking release, mechanically moving the piston against wear of the brake pad, an appropriate pad clearance can always be obtained. Like that.

Conventionally, as a pad wear following mechanism applicable to an electric disk brake, for example, a coil spring, a one-way clutch and an irreversible screw are provided so that the wear following operation is performed by utilizing the rotation of a rotor of an electric motor. The following are known (see JP-A-55-69337 and WO 99/02885).

[0006]

In addition, various wear following mechanisms that can be applied to electric disc brakes have been proposed, but all of them have a small adjustment amount for one operation and require a piston. In the case of retreating, it is necessary to rely on manual operation, and there is a problem that it takes time to replace the pad.

[0007] The present invention has been made in view of the above points, and it is possible to increase the adjustment amount of one operation,
It is another object of the present invention to provide an electric disc brake having a pad wear adjusting mechanism capable of retracting a piston by rotation of a motor.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a pair of brake pads arranged on both sides of a disk rotor and a pair of brake pads provided on a caliper body. A piston opposed to one of the brake pads, a claw fixed to the caliper main body and facing the other of the pair of brake pads across the disk rotor, an electric motor, and a pair of disks and a pair of disks interposed between the disks. A ball ramp mechanism for driving the piston by converting the rotational motion of the rotor of the electric motor into a linear motion, and driving one of the discs of the ball ramp mechanism by the electric motor. Connected to the rotor of the motor, screwing the other disk to the caliper body via a screw, and rotating both disks relatively By driving the piston, and rotating the other disk, the disk advances and retreats by the screw portion.
With this configuration, at the time of braking and braking release, the rotor of the electric motor is rotated, and both disks are relatively rotated to drive the piston by the ball ramp mechanism. Further, when the braking is released, by further rotating the rotor of the electric motor, the other disk can be rotated together with one disk of the ball ramp mechanism, and the other disk can be moved by the screw portion.

According to a second aspect of the present invention, in the electric disk brake according to the first aspect, the electric current flowing through the electric motor is monitored, and the brake pad presses the disk rotor based on a change in the electric current. A point is detected, and based on this point, the wear of the brake pad is adjusted by rotating the disk screwed to the caliper body by the electric motor. With this configuration, by detecting an increase in current due to an increase in the load on the electric motor,
The point at which the brake pad presses the disk rotor can be detected, and the pad clearance can be kept constant based on this point.

The invention according to claim 3 is characterized in that a pair of brake pads arranged on both sides of the disk rotor, a piston provided on the caliper body and facing one of the pair of brake pads, and fixed to the caliper body. A claw portion facing the other of the pair of brake pads across the disk rotor, an electric motor, and balls interposed between the first and second disks and the disks; An electric disc brake comprising a ball ramp mechanism that drives the piston by converting the rotational motion of the rotor into a linear motion, wherein the rotor of the electric motor is connected to a first disc of the ball ramp mechanism, The piston is screwed to the two disks via a screw portion, the first and second disks are connected to each other via a spring means, and the first and second disks are connected. Are rotated integrally by the spring force of the spring means, whereby the piston is moved forward and backward by the screw portion, and the first and second disks are relatively rotated against the spring force of the spring means. This causes the piston to move forward and backward. With this configuration, when the brake pad is not pressing the disk rotor, a large load does not act on the screw portion, and the resistance of the screw portion is small. Then, the second disk is rotated integrally by the spring force of the spring means, and the piston is moved by the screw portion. On the other hand, when the brake pad is pressing the disk rotor, a large load acts on the screw portion and the resistance of the screw portion increases, so that when the rotor of the electric motor is rotated, the first and second disks are rotated. The piston is driven by the ball ramp mechanism by relatively rotating against the spring force of the spring means.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. The first embodiment will be described with reference to FIGS. As shown in FIG. 1, an electric disc brake 1 according to an embodiment of the present invention includes a caliper body 3 on one side (usually inside the vehicle body) of a disc rotor 2 that rotates with wheels (not shown). The caliper body 3 is integrally formed with a claw portion 4 formed in a substantially C-shape and extending to the opposite side across the disk rotor 2.

Brake pads 5 and 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 tip of the claw portion 4, respectively. The brake pads 5, 6 are movably supported along the axial direction of the disk rotor 2 by a carrier (not shown) fixed to the vehicle body, so that the carrier receives braking torque, The caliper body 3 is slidably guided along the axial direction of the disk rotor 2 by a slide pin (not shown) attached to the carrier.

A cylindrical case 7 with a bottom is attached to the caliper body 3 on the side opposite to the claw portion 4. Caliper body 3
Is provided with a ball lamp mechanism 8, and inside the case 7,
An electric motor 9 and a rotation detector 10 are provided.

The electric motor 9 includes a stator 11 fixed to an inner peripheral portion of a case 11, and a cylindrical rotor 13 inserted into the stator 11 and supported by the case 11 by a bearing 12. The rotation detector 10 includes a resolver stator 14 fixed to the case 7 side and a resolver rotor 15 attached to the rotor 13.
This is for detecting the rotational position of. And electric motor
A controller (not shown) is connected to the rotation detector 9 and the rotation detector 10.
13 can be rotated by a desired angle at a desired torque.

The ball ramp mechanism 8 comprises an annular movable disk 16 and a support disk 17, and a plurality of balls 18 (steel balls) interposed between the pair of disks. The support disk 17 is integrally provided with a cylindrical portion 20 having a screw portion 19 (male screw) formed on the outer periphery. Cylindrical part 20
Is screwed into a screw portion 21 (female screw) formed on the inner periphery of the caliper main body 3, and the tip end thereof is inserted into the rotor 13. The screw portion 19 and the screw portion 21 form an irreversible screw, and the cylindrical portion 20 does not move even when a force acts in the axial direction, but counterclockwise when viewed from the right side of the figure ( Hereinafter, simply rotating in the counterclockwise direction) moves to the disk rotor 2 side.

The movable disk 16 is integrally formed with a cylindrical sleeve 22 having a smaller diameter than the cylindrical portion 20. The sleeve 22 is inserted into the cylindrical portion 20 and extends to the inside of the rotor 13, and an enlarged diameter portion 23 is formed at the distal end thereof. Expanded part 23
A spline 24 is formed on the outer periphery of the. A small diameter portion 25 is formed in the rotor 13, and a spline 24 of the sleeve 22 is slidably spline-coupled to a spline 26 formed on the inner periphery of the small diameter portion 25.

On the opposing surfaces of the movable disk 16 and the support disk 17, there are formed three arc-shaped ball grooves 27, 28 extending in the circumferential direction, respectively. These ball grooves
27 and 28 are extended in the range of the same central angle (for example, 90 °) and are inclined in the same direction. And ball groove 27,
The ball 18 is inserted between the balls 28, and the ball 18 rolls in the ball grooves 27 and 28 by the relative rotation of the support disk 17 and the movable disk 16, whereby the movable disk 16 and the support disk 17 are moved in the axial direction. Relative displacement. At this time, when the movable disk 16 is rotated clockwise (hereinafter simply referred to as clockwise) as viewed from the right side of the drawing with respect to the support disk 17, they are displaced in a direction away from each other.

A compression spring 29 is interposed between the distal end of the cylindrical portion 20 of the support disk 17 and the base end of the enlarged diameter portion 23 of the sleeve 22 of the movable disk 16, and the compression spring 29 is moved by the spring force. The disc 16 and the support disc 17 are urged so as to sandwich the ball 18.

A piston 30 is provided between the brake pad 5 and the movable disk 16, and a thrust bearing 31 is interposed between the piston 30 and the movable disk 16. The piston 30 is supported by the brake pad 5 so as not to rotate by the pin 32. The piston 30 is provided with a rod portion 33 that is slidably inserted into the sleeve 22 of the movable disk 16. The rod portion 33 is formed by the enlarged diameter portion 23 of the sleeve 22.
The spring support 34 is extended to the inside of the
A compression spring 36 is interposed between the piston 30 and the shoulder 35 in the sleeve 22.
16 are urged so as to sandwich the thrust bearing 31.

Next, the operation of the embodiment constructed as described above will be described. In the non-braking state, as shown in FIG. 4, the ball 18 is at the deepest end of the ball grooves 27, 28,
The movable disk 16 is at the initial position closest to the support disk 17. At the time of braking, by rotating the rotor 13 of the electric motor 9 clockwise by a control signal from the controller, the movable disk 16 rotates clockwise (the direction indicated by the arrow F in FIG. 4) via the splines 24 and 26. . As a result, the ball 18 rolls in the grooves 27 and 28 to move the movable disk.
16 is advanced, and the piston 30 presses one brake pad 5 against the disk rotor 2. The caliper body 3 moves along the slide pin of the carrier due to the reaction force,
The pawl 4 presses the other brake pad 6 against the disk rotor 2. In this way, a braking force is generated according to the torque of the electric motor 9, and the braking force can be controlled by the control signal.

When braking is released, the rotor 13 of the electric motor 9
By rotating the spline 2 counterclockwise.
The movable disk 16 rotates counterclockwise (in the direction indicated by the arrow R in FIG. 5) via 4 and 26. The movable disk 16 and the support disk 17 are urged by a spring 29 in a direction to pinch the ball 18, and the piston 30 and the support disk 17
Since the thrust bearing 31 is urged in the direction to pinch the thrust bearing 31 by the counterclockwise rotation of the movable disk 16, the movable disk 16 and the piston 30 move backward, and the caliper body 3 moves along the slide pin of the carrier. Then, the brake pads 5, 6 are separated from the disk rotor 2.

At the time of the braking and the release of the braking, the support disk 17 does not rotate due to the frictional force between the screw portions 19 and 21. In the state where the brake pads 5 and 6 are pressing the disk rotor 2 during braking, the screw portions 19 and 21
Therefore, a large load acts in the axial direction to increase the frictional force, so that even if a large torque acts on the support disk 17, the support disk 17 does not rotate.

Next, adjustment of wear of the brake pads 5 and 6 will be described. When the movable disk 16 is rotated clockwise from the initial position during braking, as shown in FIG. 3, the thrust (load) of the electric motor 9 is small until the brake pads 5 and 6 abut against the disk rotor. The current flowing through the motor 9 is small. Brake pads 5 and 6 are disk rotor 2
After that, the load on the electric motor 9 increases, and the current flowing through the motor increases. Thereby, by monitoring the current flowing through the electric motor 9, displacement from the initial position of the movable disk 16 until the brake pads 5, 6 abut on the disk rotor 2 (rotation angle from the initial position of the electric motor 9), That is, the pad clearance θ can be detected. Then, the increment Δ of the pad clearance θ
By calculating θ, the amount of wear of the brake pads 5 and 6 can be detected.

The controller increases the increment Δθ of the pad clearance θ during braking, that is, the brake pad
If the wear of 5, 6 is detected, the electric motor
The 9 rotor 13 is further rotated counterclockwise from the initial position. At this time, as shown in FIG. 4, since the ball 18 is in contact with the deepest end of the groove, the support disk 17 is moved counterclockwise together with the movable disk 16 (in the direction indicated by arrow F ′ in FIG. 4). , And is advanced to the disk rotor 2 side by the screw portions 19 and 21. In this way, by rotating the electric motor 9 counterclockwise in accordance with the increment Δθ of the pad clearance θ to advance the support disk 17, the piston 30 can follow the wear of the brake pads 5, 6. In addition, the pad clearance θ can always be kept constant (see FIG. 2).

When the piston 30 is retracted, for example, when replacing the brake pads 5, 6, the movable disk 16 is rotated clockwise by the electric motor 9 as shown in FIG.
(In the direction indicated by the arrow R ′ in FIG. 5) to bring the ball 18 into contact with the shallow end of the groove, and then further rotate clockwise, so that the support disk 17 is moved together with the movable disk 16. It rotates clockwise and retreats from the disk rotor 2 side by the screw portions 19 and 21. In this way, the piston 30
Can be easily moved backward by the electric motor 9.

Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 6 and 7, an electric disc brake 40 according to the present embodiment includes a caliper body 42 on one side (usually inside the vehicle body) of a disc rotor 41 that rotates with wheels (not shown). A claw portion 43 formed substantially in a C-shape and extending to the opposite side across the disk rotor 41 is integrally connected to the caliper body 41. Brake pads 44, 45 are provided on both sides of the disk rotor 41, that is, between the disk rotor 41 and the caliper body 41 and between the tip of the claw portion 43, respectively.
Is provided. The brake pads 44 and 45 are supported by a carrier 46 fixed to the vehicle body so as to be movable in the axial direction of the disk rotor 41, so that the braking torque is received by the carrier 46.
Is guided slidably along the axial direction of the disk rotor 41 by a slide pin (not shown) attached to the carrier 46.

A substantially cylindrical case 48 is connected to the caliper body 42 by bolts 47, and an electric motor 49 and a rotation detector 50 are provided in the case 48. Inside the caliper body 42, a ball ramp mechanism 51 and a speed reduction mechanism 52 are provided.
Is inserted. A cover 53 is attached to the rear end of the case 48 with bolts 54.

The electric motor 49 includes a stator 55 fixed to the inner peripheral portion of the case 48, a bearing 56 inserted into the stator 55,
And a rotor 58 rotatably supported by the case 48 by 57. The rotation detector 50 includes a resolver stator 59 fixed to the case 48 and a resolver rotor 60 attached to the rotor 58, and detects the rotational position of the rotor 58 based on their relative rotation. A controller (not shown) is connected to the electric motor 49 and the rotation detector 50 via a connector 61 so that the rotor 58 can be rotated by a desired angle with a desired torque by a control signal from the controller. Has become.

The ball ramp mechanism 51 includes an annular first and second annular
It is composed of disks 62 and 63 and a plurality of balls 64 (steel balls) interposed therebetween. The first disk 62
It is rotatably supported by the caliper body 42 by the bearing 65,
A cylindrical portion 66 inserted into the rotor 58 is formed integrally. The second disk 63 is formed integrally with a cylindrical sleeve 67 having a smaller diameter than the cylindrical portion 66, and the sleeve 67 is inserted into the cylindrical portion 66.

In the ball ramp mechanism 51, similarly to the first embodiment, a ball 64 is inserted between ball grooves 68 and 69 formed in the first and second discs 62 and 63, and the first and second discs are formed. The first disk 62 and the second disk 63 are relatively displaced in the axial direction by the balls 64 rolling in the ball grooves 68 and 69 due to the relative rotation of the two disks 62 and 63. At this time, when the first disk 62 rotates counterclockwise with respect to the second disk 63, they are displaced in a direction separating from each other.

A piston 70 is provided between the second disk 63 and the brake pad 44. The piston 70 has
A cylindrical portion 72 having a screw portion 71 formed on the outer periphery is provided.
The cylindrical portion is inserted into the sleeve 67 of the second disk 63,
It is screwed into a screw portion 73 formed on the inner periphery. A two-chamfered portion 76 of a shaft 75 attached to the case 48 via a bracket 74 is fitted in the cylindrical portion 72 to support the piston 70 from rotating. The screw portion 71 and the screw portion 73 form an irreversible screw, and the piston 70 does not move even when a force is applied in its axial direction.
By rotating the disk counterclockwise, the disk rotor
It moves to the 41 side.

A plurality of disc springs 79 (compression springs) are interposed between spring supports 77 and 78 formed on the outer periphery of the shaft 75 and the inner periphery of the sleeve 67 of the second disk 63, respectively. The two disks 63 are biased so as to sandwich the ball 64 between the first disk and the ball 64. The shaft 75 is attached to the bracket 74 by an adjusting screw 80 and a lock nut 81. In addition, the second disk 63 is given an appropriate resistance to its rotation by the pressing of the waveform washer 82.

Next, the speed reduction mechanism 52 will be described. An eccentric shaft 83 is formed at one end of a rotor 58 of the electric motor 49, and an eccentric plate 85 is rotatably mounted on an outer peripheral portion of the eccentric shaft 83 via a bearing 84. The caliper body 42 has an eccentric plate 85
A fixing plate 86 is fixed so as to be opposed to. On the opposing surfaces of the eccentric plate 85 and the fixed plate 86, a plurality of holes 87, 88 (concave portions) are formed along the circumferential direction, and a ball 89 (steel ball) is provided between these holes 87, 88. By interposing the Oldham mechanism,
The eccentric plate 85 which revolves is supported. One end surface of the eccentric plate 85 is opposed to the first disk 62, and cycloid grooves 90 and 91 are formed on these opposed surfaces, and a ball 92 (steel ball) is inserted between the cycloid grooves 90 and 91. Have been.

A cylindrical spring holder 93 is attached to the outer periphery of the distal end of the sleeve 67 of the second disk 63 by a pin 94 so as not to rotate. Spring holder 93
Is engaged with the distal end of the cylindrical portion 66 of the first disk 62 to limit the relative rotation thereof to a certain range. A coil spring 95 (spring means) is wound around the spring holder 93, the coil spring 95 is twisted with a predetermined set load, one end of the coil spring 95 is connected to the spring holder 93, and the other end is connected to the spring holder 93. 1 Cylindrical part 66 of disk 62
Is joined to.

Next, the operation of the present embodiment configured as described above will be described. In the non-braking state, the ball 64 of the ball ramp mechanism 51 is at the deepest end of the ball grooves 68, 69, and the first disk 62 and the second disk 63 are at the closest positions. During braking, when the rotor 58 of the electric motor 49 is rotated clockwise, the eccentric plate 85 revolves and the cycloid groove 90,
The first disk 62 is rotated by the action of the
With respect to 8, the motor rotates counterclockwise at a constant rotation ratio N represented by the following equation. N = (d−D) / D where, d: reference circle diameter of cycloid groove 90 D: reference circle diameter of cycloid groove 91 That is, the first disk 62 has a constant reduction ratio α (= It is decelerated at 1 / N) and rotates counterclockwise, and the torque is amplified accordingly.

The rotational force of the first disk 62 is transmitted to the second disk 63 via the coil spring 95. Piston 7
Before 0 presses the brake pads 44 and 45, the piston 70
The load in the axial direction hardly acts on the first disk 62 and the resistance generated in the threaded portions 71 and 73 between the piston 70 and the second disk 63 is small. Rotates together with the second disk 63
Relative rotation occurs between the piston and the piston 70, and the threaded portions 71, 73
Causes the piston 70 to advance toward the disk rotor 41. Then, the piston 70 presses the one brake pad 44 against the disk rotor 41, and the caliper body 42 moves along the slide pin of the carrier 46 due to the reaction force,
The pawl portion 43 presses the other brake pad 45 against the disk rotor 41.

The brake pads 44 and 45 are
After being pressed by the coil spring 95, a large axial load acts on the piston 70 due to the reaction force, so that the resistance of the threaded portions 71 and 73 increases, exceeding the set load of the coil spring 95, and causing the coil spring 95 to bend. And the first and second disk rotors 62,
Relative rotation occurs between 63. As a result, the ball 64 rolls in the ball grooves 68 and 69 to advance the second disk 63, and the brake pads 44 and 45 are pressed against the disk rotor 41 by the piston 70.

When the braking is released, the rotor 58 of the electric motor 49 is released.
Is rotated counterclockwise, the first disk 62 rotates clockwise via the speed reduction mechanism 52, and while the brake pads 44, 45 are pressed by the disk rotor 41,
The first and second discs 62 and 63 rotate relative to each other, and the second disc 63
After the brake pads 44 and 45 are separated from the disk rotor 41, the first and second disks 62 and 63 rotate integrally, and the pistons 70 are further retracted by the action of the screw portions 71 and 73.

As in the first embodiment, the electric motor 49
By monitoring the current flowing through the brake pad 4
By detecting the point at which 4, 45 presses the disk rotor 41, by retracting the piston 70 from that position by a certain distance corresponding to a predetermined pad clearance,
The pad clearance can always be kept constant.

Next, the operation when the brake pads 44 and 45 are not worn (including the case where the wear adjustment described later is performed) will be described with reference to FIG. When the rotor 58 of the electric motor 49 rotates during braking, before the brake pads 44 and 45 press the disc rotor 41, the first and second discs 6 are moved.
2 and 63 rotate together, and piston 7
0 moves forward (A). Piston 70 is equivalent to pad clearance δ
The brake pads 44, 45
After pressing 41, (B), since the resistance of the screw portions 71, 73 increases, the first and second disks 62, 63 relatively rotate, and the second disk 63 moves forward by the ball ramp mechanism 51. , Further pressing the brake pads 44, 45 against the disk rotor 41
(C).

When the brake is released, when the rotor 58 is rotated in the reverse direction, the first and second disks 62 and 63 rotate relative to each other until the brake pads 44 and 45 separate from the disk rotor 41, and the ball ramp mechanism 51 rotates the first and second disks 62 and 63. 2 Disc 63 retreats
(D). After that, by rotating the rotor 58 by a fixed angle corresponding to the pad clearance δ, the first and second disks 62 and 63 rotate integrally, and by the screw portions 71 and 73,
Piston 70 retracts by pad clearance δ
(E). In this way, a constant pad clearance can always be maintained.

Next, the case of adjusting the wear of the brake pads 44 and 45 will be described with reference to FIG. When braking is started and the rotor 58 of the electric motor 49 rotates, before the brake pads 44 and 45 press the disc rotor 41,
1. The second disks 62 and 63 rotate together, and the piston 70 advances by the threaded portions 71 and 73 (A). At this time, piston 7
Even if 0 advances by the pad clearance δ, the brake pads 44 and 45 are worn,
Is not pressed (B). When the piston 70 advances by the wear of the pad by the further integral rotation of the first and second disks 62 and 63, the brake pads 44 and 45 press the disk rotor 41 (C). Brake pads 44 and 45 are disk rotor 4
After pressing 1, the resistance of the threaded portions 71 and 73 increases, so that the first and second disks 62 and 63 rotate relative to each other, and the second disk 63 moves forward by the ball ramp mechanism 51, and the brake pad 44 and 45 are further pressed against the disk rotor 41
(D).

At the time of braking release, when the rotor 58 is rotated in the reverse direction, the first and second disks 62 and 63 rotate relative to each other until the brake pads 44 and 45 separate from the disk rotor 41, and the ball ramp mechanism 51 rotates the first and second disks 62 and 63. 2 Disc 63 retreats
(E). Thereafter, by further rotating the rotor 58 by a certain angle corresponding to the pad clearance δ, the first,
The second disks 62 and 63 rotate together, and the pistons 70 are retracted by the pad clearance δ by the threaded portions 71 and 73 (F).

Thus, regardless of the amount of wear of the brake pads 44 and 45, the piston 70 follows the wear of the brake pads 44 and 45 by one adjustment operation shown in (A) to (C). And a constant pad clearance can always be maintained.

Next, a case where the piston 70 is retracted when replacing the brake pads 44 and 45 will be described with reference to FIG. As shown in FIG. 10A, when the first disc 62 is rotated clockwise by the electric motor 49 in the non-braking state, the balls 64 of the ball ramp mechanism 51 are rotated.
Are located at the deepest ends of the ball grooves 68, 69, and since no load is applied to the screw portions 71, 73, the first and second disks 62, 63 rotate integrally, As shown in (B),
The piston 70 is retracted by the action of the screw portions 71 and 73. In this way, the piston 70 can be easily retracted by the rotation of the rotor 58 of the electric motor 49.

After that, the brake pads 44 and 45 are replaced,
By executing the braking operation, a predetermined pad clearance can be quickly obtained by one adjustment operation in the same manner as in the wear adjustment described above.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. Note that the third embodiment has a generally similar structure to the second embodiment, except that the pad wear adjustment mechanism is different. Hereinafter, the same parts as those of the second embodiment will be the same. Only different parts will be described in detail with reference numerals.

As shown in FIG. 11, in the electric disc brake 100 of this embodiment, a cylindrical limiter 101 is interposed between the spring holder 93 and the coil spring 95 and the cylindrical portion 66 of the first disc. I have. Spring holder 9
A coil spring 95 is wound around 3 and the limiter 101, and the coil spring 95 is twisted with a predetermined set load, one end of the coil spring 95 is connected to the spring holder 93, and the other end is connected to the limiter 101. ing. Limiter 1
01 is engaged with the distal end portion of the cylindrical portion 66 of the first disk 62 so as to be able to rotate relatively by a predetermined angle corresponding to the pad clearance.

The operation of the present embodiment having such a configuration will be described with reference to FIGS. 12, 13 and 10. FIG. The operation when the brake pads 44 and 45 are not worn (including the case where the wear adjustment described later is performed) will be described with reference to FIG. During braking, when the first disk 62 rotates due to rotation of the rotor 58 of the electric motor 49, the brake pad 4
Before 4, 45 presses the disk rotor 41 (for the pad clearance), since the rotational force of the first disk 62 is not transmitted to the second disk 63 due to the relative rotation of the first disk 62 and the limiter 101, the first, The second disks 62 and 63 rotate relatively to advance the piston 70 toward the disk rotor 41 (A). After the piston 70 advances by the pad clearance δ and the brake pads 44 and 45 press the disk rotor 41, the limiter 101 applies the rotational force of the first disk 62 to the coil spring.
95 to the first disk 63, but the threaded portions 71, 73
The coil spring 95 is flexed and the first and second discs 62 and 63 are relatively rotated, and the ball ramp mechanism 51 causes the second disc 63 to move forward to move the brake pads 44 and 45. Further press against disc rotor 41
(C).

At the time of braking release, when the rotor 58 is rotated in the reverse direction, the first and second disks 62 and 63 are driven by the spring force of the disc spring 79.
Are relatively rotated, and the piston 70 retreats until the brake pads 44 and 45 are separated from the disk rotor 41 (D). Thereafter, by further rotating the rotor 58 by a certain angle corresponding to the pad clearance δ, the first disk 62 rotates relative to the limiter 101, and the piston 70 retreats by the pad clearance δ (E). In this way, a constant pad clearance can always be maintained.

Next, the case of adjusting the wear of the brake pads 44 and 45 will be described with reference to FIG. When braking is started and the first disk 62 is rotated by rotation of the rotor 58 of the electric motor 49, before the brake pads 44 and 45 press the disk rotor 41, the first disk 62 and the limiter 101 are pressed.
The rotational force of the first disk 62 is not transmitted to the second disk 63 due to the relative rotation with the first and second disks 62, 63.
Rotate relative to each other to advance the piston 70 toward the disk rotor 41 (A). At this time, even if the piston 70 advances by the pad clearance δ, the brake pads 44 and 45 do not press the disk rotor 41 because they are worn (B).

When the first disk 62 further rotates, the limiter 101 transmits the rotating force to the second disk via the coil spring 95, but the brake pads 44, 45 do not press the disk rotor 41, and Since no large load is applied to the portions 71 and 73, the first and second disks 62 and 63 rotate integrally via the coil spring 95. As a result, the piston 70 advances by the action of the screw portions 71, 73, and when the piston advances by the amount of wear of the pad, the brake pads 44, 45 press the disk rotor 41 (C). After the brake pads 44 and 45 press the disk rotor 41, the resistance of the threaded portions 71 and 73 increases, so that the coil spring 95 bends and the first and second disks 62 and 63 rotate relatively, and the ball ramp mechanism By 51, the second disk 63 moves forward, and further presses the brake pads 44, 45 against the disk rotor 41.
(D).

When the brake is released, when the rotor 58 is rotated in the reverse direction, the first and second disks 62 and 63 are actuated by the spring force of the disc spring 79.
Rotate relative to each other, and the piston 70 moves backward until the brake pads 44 and 45 are separated from the disk rotor 41 (E). Thereafter, by further rotating the rotor 58 by a certain angle corresponding to the pad clearance δ, the first disk 62 rotates relative to the limiter 101, and the piston 70 retreats by the pad clearance δ (F).

Thus, regardless of the amount of wear on the brake pads 44, 45, the piston 70 follows the wear on the brake pads 44, 45 by one adjustment operation shown in (A) to (C) above. And a constant pad clearance can always be maintained.

Next, the case where the piston 70 is retracted when the brake pads 44 and 45 are replaced will be described. As in the second embodiment, as shown in FIG. 10A, in the non-braking state, the first disc 6 is driven by the electric motor 49.
When 2 is rotated clockwise, the ball 64 of the ball ramp mechanism 51 is at the deepest end of the ball groove 68, 69, and no load is applied to the threaded portions 71, 73.
1, the second disks 62 and 63 rotate integrally, and as shown in FIG. 10 (B), the piston 70 retreats by the action of the screw portions 71 and 73. In this way, the piston 70 can be easily retracted by the rotation of the rotor 58 of the electric motor 49.

After that, the brake pads 44 and 45 are replaced,
By executing the braking operation, a predetermined pad clearance can be quickly obtained by one adjustment operation in the same manner as in the wear adjustment described above.

In the second and third embodiments, the rotation of the electric motor is reduced by the speed reduction mechanism to amplify the torque transmitted to the ball ramp mechanism. However, the ball ramp mechanism is directly controlled by the rotor of the electric motor. It can be configured to be driven.

[0058]

As described above, according to the electric disk brake of the first aspect, at the time of braking and braking release, the rotor of the electric motor is rotated and the two disks are rotated relative to each other, whereby the ball ramp mechanism is provided. By driving the piston, the brake pad can be pressed and separated from the disk rotor. Further, at the time of braking release, by further rotating the rotor of the electric motor, one of the disks of the ball ramp mechanism is rotated together with the other disk, and the other disk is moved by the screw portion, and the brake pad is worn. Can be followed.
Further, when replacing the brake pad, etc., by rotating the rotor of the electric motor, the other disk is rotated together with one disk of the ball ramp mechanism,
The other disk is retracted by the screw portion, so that the piston can be easily and quickly retracted.

According to the electric disk brake of the second aspect of the present invention, the point at which the brake pad presses the disk rotor can be detected by detecting an increase in current caused by an increase in the load on the electric motor. , The pad clearance can be maintained constant.

According to the electric disc brake of the third aspect of the present invention, when the brake pad is not pressing the disc rotor, a large load does not act on the screw portion and the resistance of the screw portion is small. When the rotor of the motor is rotated, the first and second disks rotate integrally by the spring force of the spring means, and the piston is moved by the screw portion. On the other hand, when the brake pad is pressing the disk rotor, a large load is applied to the screw portion, and the resistance of the screw portion increases.
First, the second disk relatively rotates against the spring force of the spring means, and the piston is driven by the ball ramp mechanism.
As a result, a braking force is generated by the ball ramp mechanism, and the piston can follow the wear of the brake pad by the screw portion. When the brake pad is replaced, the piston can be easily and quickly retracted by the screw portion by rotating the rotor of the electric motor.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a state where a brake pad of the apparatus of FIG. 1 is worn.

FIG. 3 is a graph showing a relationship between a displacement of a piston of the device of FIG. 1 and a current of an electric motor.

FIG. 4 is an explanatory view showing a state in which the ball ramp mechanism of the apparatus shown in FIG. 1 is at an initial position.

FIG. 5 is an explanatory view showing a state in which the ball ramp mechanism of the apparatus shown in FIG. 1 has been maximally displaced.

FIG. 6 is a longitudinal sectional view of a second embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a cylindrical portion, a sleeve and a spring holder of the apparatus of FIG. 6 taken along the line AA.

FIG. 8 is an explanatory diagram showing an operation of the device of FIG. 6 when the brake pad is not worn.

FIG. 9 is an explanatory diagram showing an operation of the device of FIG. 6 when the brake pad is worn.

FIG. 10 is an explanatory view showing the operation of the apparatus shown in FIGS. 6 and 11 when the piston is retracted when the brake pad is replaced or the like.

FIG. 11 is a longitudinal sectional view of a third embodiment of the present invention.

FIG. 12 is an explanatory diagram showing an operation of the device of FIG. 11 when the brake pad is not worn.

FIG. 13 is an explanatory diagram showing an operation of the device of FIG. 11 when the brake pad is worn.

[Explanation of symbols]

 1 Electric disc brake 2 Disc rotor 3 Caliper body 4 Claw 5,6 Brake pad 8 Ball ramp mechanism 9 Electric motor 13 Rotor 16 Movable disc 17 Support disc 18 Ball 19,21 Screw

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3J058 AA43 AA48 AA53 AA63 AA69 AA73 AA78 AA87 BA57 CC15 CC56 CC62 CC77 DA04 DA18 DA24 FA01

Claims (3)

[Claims] 1. A pair of brake pads arranged on both sides of a disk rotor, a piston provided on a caliper body and 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, a pair of discs, and a ball interposed between the discs, and a ball ramp mechanism for driving the piston by converting a rotary motion of a rotor of the electric motor into a linear motion. By connecting one disk of the ball ramp mechanism to the rotor of the electric motor, screwing the other disk to the caliper body via a screw portion, and rotating both disks relatively, the piston The electric disc brake is characterized in that the disc is moved forward and backward by the screw portion by driving the other disc and rotating the other disc. Monitoring a current flowing through the electric motor;
Based on the change in the current, a point at which the brake pad presses the disk rotor is detected, and based on this point, the disk screwed to the caliper body is rotated by the electric motor. 2. The electric disc brake according to claim 1, wherein the pad wear is adjusted. 3. A pair of brake pads arranged on both sides of a disk rotor, a piston provided on a caliper body and 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 motor, and a ball ramp mechanism configured of a first disk, a second disk, and a ball interposed between the disks, and configured to convert a rotational motion of a rotor of the electric motor into a linear motion to drive the piston. An electric disc brake comprising: a rotor of the electric motor connected to a first disc of the ball ramp mechanism, and a piston screwed to a second disc via a screw portion; The first and second discs are connected to each other via a spring means, and the first and second disks are rotated integrally by the spring force of the spring means, whereby the piston is moved forward and backward by the screw portion, and And an electric disc brake for moving the piston forward and backward by rotating the second disc relatively against the spring force of the spring means.