JPH11257381A - Disk brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a favorable positional relation between a motor rotor and a screw shaft even during replacement of a brake pad. SOLUTION: A caliper 3 is formed in the inner surface of its cylinder- extension part 31 with a line of axial groove 42, and a detent plate 33 having a projection 41 to be inserted into this groove 42 is mounted on the end of a screw shaft 8 distant from a pad 10 to regulate the rotation of the screw shaft 8 via the detent plate 33. Characteristically, the screw shaft 8 is not coupled to an inner pad 10a via any detent means. By this construction, even if a braking operation in which a brake rotor 9 has sliding movement causes the inner pad 10a to play at a carrier 2, the backlash is never transmitted to the screw shaft 8, which is therefore prevented from having any reciprocation amount deviation of the screw shaft 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc brake provided in an automobile, and more particularly to a motor-driven disc brake.

[0002]

2. Description of the Related Art As an example of a conventional motor-driven disk brake for moving a friction pad forward and backward by driving a motor, a motor is provided on a caliper that is supported so as to be displaceable with respect to a carrier, and the motor rotor is rotated by a motor rotor. Is provided with a screw shaft of a screw mechanism for converting the movement into the axial movement of the motor rotor, and the brake shaft movably supported by the carrier is pressed by the screw shaft moving forward and backward to generate a braking force. (An example of such a type of disc brake is disclosed in International Publication WO
No. 96/03301. ).

[0003]

By the way, in the above-mentioned disc brake, the detent means of the screw shaft for pressing the brake pad against the brake rotor is provided by, for example, implanting a detent pin on the brake pad pressing surface side of the screw shaft. The surface of the brake pad on the screw shaft side is provided with a hole into which the detent pin is fitted, and is provided between the screw shaft and the brake pad.

As described above, since the brake pad and the screw shaft are connected via the rotation preventing means, when the brake pad slides with respect to the carrier due to sliding of the brake rotor during the operation of the brake, The play is also transmitted to the screw shaft, and there is a possibility that the play between the screw shaft of the screw mechanism and the feed member may be loosened. As a result, the screw mechanism according to the rotation amount of the motor rotor may cause the play. There is a possibility that the amount of advance and retreat of the screw shaft may be out of order.

When the motor is rotated in the reverse direction to return the advancing / retreating position of the screw shaft of the screw mechanism to the home position when the brake pad is replaced, the brake pad is thicker than the initial one by the amount of wear of the friction material. Is thinner and closer to the brake rotor side, and if the screw shaft retreats to return to the origin, there is a possibility that the engagement of the detent means between the screw shaft and the brake pad may be released. Therefore, in order to solve such a problem, it is conceivable to lengthen the fitting length between the pin and the hole of the detent means. However, in such a case, the work of assembling the brake pad becomes difficult. Problem arises.

Further, when the amount of wear of the brake pad is grasped by the amount of advance and retreat of the screw shaft, and the amount of advance and retreat of the screw shaft is measured by the amount of rotation of the motor rotor, the amount of rotation is absolutely measured. When the encoder is used, when the brake pad is replaced, the screw shaft advance / retreat position is returned to the home position.If the brake pad is removed first, the screw shaft rotation restriction is released. Since the shaft rotates integrally with the motor rotor, the correspondence between the rotation position of the absolute encoder and the advance / retreat position of the screw shaft changes.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to suppress the influence on a rattling screw mechanism when braking a brake pad and to maintain a good correspondence between a motor rotor and a screw shaft. It is an object to provide a disc brake that can be used.

[0008]

According to the present invention, in order to achieve the above object, a screw mechanism comprising a screw shaft and a nut for guiding the screw shaft in the axial direction is housed in a caliper and held by the nut. The motor having the rotor to be driven is housed in the caliper, and a detent means for preventing rotation of the screw shaft is provided, and the pad is pressed against the brake rotor by the axial movement of the screw shaft to generate a braking force. In the disc brake to be rotated, the detent means is provided between the end of the screw shaft opposite to the pad and the caliper.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A disk brake according to an embodiment of the present invention will be described below with reference to FIGS.
1 and 2, a disc brake 1 includes a caliper 3 movably supported by a carrier 2 provided on a fixed portion of an automobile, a ball screw mechanism (screw mechanism) 4 housed in the caliper 3, and a ball screw A motor 7 having a rotor (hereinafter referred to as a motor rotor) 6 fitted to a nut 5 of the mechanism 4, and a pair of pads 10 pressed against a brake rotor 9 by the axial movement of a screw shaft 8 of the ball screw mechanism 4. (Hereinafter, the thing on the right side of FIG.
a, the one on the left is called the outer pad 10b. ) And a lid 11 for closing one opening (right side in FIG. 1) of a hollow portion 13 of the caliper 3 which will be described later. The inner pad 10a and the outer pad 10b are arranged inside and outside the vehicle body, respectively, and supported by the carrier 2 so as to be movable in the axial direction of the brake rotor 9.

In the disc brake 1, the screw shaft 8 moves leftward in FIG. 1 by the action of the motor 7 or the lid 11, and presses the inner pad 10a against the brake rotor 9, and the caliper 3 reacts with the carrier by the reaction. 1 with respect to FIG. 1, the claw 12 of the caliper 3 presses the outer pad 10b against the brake rotor 9 to generate a braking force.

The caliper 3 has a hollow portion 13 opened at both ends (left and right sides in FIG. 1), and has a motor housing portion 14 of a predetermined length (length in the left and right direction in FIG. 1) for housing the motor 7 in the hollow portion 13.
2, and the claw portion 12 connected to the motor accommodating portion 14 by bolts 15 and extending to the outer pad 10b side beyond the brake rotor 9 as shown in FIG. The opening (right side in FIG. 1) is closed by the lid 11 as described above.

The motor housing 14 extends from the end of the motor 7 toward the pad 10 (to the left in FIG. 1) by a predetermined length, and the claw 12 is connected to the end of the extension 17. I have. The apparatus disclosed in International Publication WO 96/03301 has a structure in which a heavy motor storage part and a ball screw mechanism are supported on the disk path base end side of a member constituting a claw part. It was necessary to remove the support portion of the ball screw mechanism, resulting in poor workability. On the other hand, in the present embodiment, as will be described later, the ball screw mechanism 4 is provided in the motor housing portion 14 (extended portion 17).
Are supported, so that when replacing the pad, the support portion of the ball screw mechanism 4 does not need to be removed, and the workability is improved accordingly.

The motor housing 14 is located on the side opposite to the pad 10 (see FIG.
The portion is extended in the right direction by a length L (the portion is referred to as an extension portion 19 for convenience). If the above-mentioned extension 19 is not provided, the rotation preventing portion 31 is attracted by the magnetic force of the magnet 18, and the motor housing 14 and the lid main body 1 are drawn.
The axis of 1A tends to shift, and it is difficult to align the axes. On the other hand, in the present embodiment, the extension portion 19 having the length L is
Since it functions as a 1A mounting guide, it is easy to align the axes. Note that the length L of the extension 19 is
8 is set so that the axis of the motor housing 14 and the lid main body 11A are aligned, and the dimensions are set so that the mounting operation can be easily performed.

On both sides of the motor housing 14 in the direction perpendicular to the axis of the brake rotor 9 in the caliper 3,
As shown in FIGS. 3 and 4, a pair of cylindrical portions 20 extending in the axial direction are provided. The cylindrical portion 20 is slidably fitted on a pin 22 bridged by two pairs of support portions 21 formed on the carrier 2, whereby the caliper 3 is movably mounted on the carrier 2. Supported. In this case, the caliper 3 is the cylindrical portion 20 and thus the caliper 3
The heavy “motor housing portion 14”, which accounts for a large part of the weight of the motor, is supported via the pin 22. In addition, one of the pair of support portions 21 formed on the carrier 2 (FIG. 4)
A hole 23 is formed in the support portion 21 (on the right side), and a screw hole 24 is formed in the other support portion 21 (on the left side in FIG. 4). The tip of the pin 22 is inserted into the hole 23. ,
A male screw 22b formed on the head 22a side of the pin 22 is screwed into the screw hole 24 so that the pin 22 forms a pair with the support portion 21.
It is attached to the bridge. As shown in FIGS. 4 and 5, one support portion 21 (right side in FIG. 4) is provided at a tip end of an arm portion 25 extending from the other support portion 21 (left side in FIG. 4). ing. In FIG. 4, reference numeral 26 denotes a sleeve fitted to the shaft of the pin 22, and reference numeral 26a denotes a boot interposed between the cylindrical portion 20 and the portion of the sleeve 26 on the support portion 21 side.

The lid 11 includes a lid body 11A and a lid body 11A.
A lid main body support portion 16 which is connected to the main body and closes one opening (right side in FIG. 1) of the hollow portion 13 together with the lid main body 11A;
Approximately. The lid main body 11A includes a cylinder main body 29 having a hydraulic chamber 28 communicating with a hydraulic pressure generation source (a master cylinder or the like) (not shown) via a port 27, and a piston slidably housed in the hydraulic chamber 28 of the cylinder main body 29. 30, a detent portion 31 extending from the cylinder body 29 and having a space having an inner diameter substantially equal to that of the hydraulic chamber 28;
Lid body supporting portion 1 formed on the outer peripheral side of cylinder body 29
6 and a flange portion 32 fixed to the base member 6. When the pressure oil is supplied to the hydraulic chamber 28, the piston 30 is rotated by a detent plate (detent member) 33 described later.
1 to push the screw shaft 8 leftward in FIG. 1 to generate a braking force.

The ball screw mechanism 4 comprises the screw shaft 8 and the nut 5 for guiding the screw shaft 8 in the axial direction. The nut 5 is rotatably provided on the caliper 3 (the caliper main body 14 and the encoder mounting plate 35 fixed to the caliper main body 14) via the bearing 34, and furthermore, on the motor housing 14 (extended portion 17). . A bearing retainer 36 is attached to the nut 5 by a bolt 60. The inner ring of the bearing 34 is held by the bearing retainer 36 and the nut 5, and the outer ring of the bearing 34 is held by the caliper 3.

On one end side (pad 10 side) of the screw shaft 8,
A pressure plate 37 that is in contact with the inner pad 10a is fixed by bolts (symbols omitted). The detent plate 33 is fixed to the other end of the screw shaft 8 (an end of the screw shaft 8 opposite to the pad 10) by a bolt (not shown). As shown in FIGS. 1 and 6, the rotation preventing plate 33 is fitted into a concave portion 38 formed at the end of the screw shaft 8,
A fitting portion 39 attached to the screw shaft 8 by bolts (symbols omitted); and the piston 3 connected to the fitting portion 39.
It comprises a disk portion 40 having a diameter substantially equal to 0 and one protruding portion 41 formed on the outer peripheral portion of the disk portion 40. A single groove 42 extending in the axial direction is provided on the inner peripheral side of the rotation preventing portion 31.
The protrusion 41 is inserted into the groove 42, the rotation of the screw shaft 8 is restricted via the rotation preventing plate 33, and the screw shaft 8 is movable in the axial direction. 39a in FIG.
Is a bolt hole into which the above-mentioned bolt (symbol is omitted) is inserted, and a pair of bolt holes 39a (two in total) are provided to face each other. However, the present invention is not limited to this, and a plurality of pairs of bolt holes 39 may be used.
a may be provided so that the bolt holes 39a are arranged at equal intervals in the circumferential direction. For example, two pairs of bolt holes 39a
And the four bolt holes 39a are 90 ° circumferentially.
They may be arranged at intervals. Further, the projecting portion 41 of the rotation preventing plate 33 is configured to abut on a wall portion (rotation preventing portion 31) on the axial direction side of the groove 42, whereby the zero point position (with respect to the brake rotor 9 of the screw shaft 8 relative to the brake rotor 9). The maximum distance movement position) can be regulated.

The motor 7 comprises a stator 43 having a predetermined width fitted into the hollow portion 13 of the motor housing portion 14 and the motor rotor 6 disposed in the stator 43. It is located at the center of the direction. The motor rotor 6 includes a sleeve 44 having a predetermined width to be fitted to the nut 5, and a plurality of the magnets 18 arranged circumferentially on the outer peripheral side of the sleeve 44 and press-fitted and fixed to the sleeve 44. A plurality of coils (symbols are omitted) are arranged on the stator 43 in the circumferential direction.

The motor 7 is connected to a controller (not shown) via a motor wire 45, and each coil is selectively energized based on a control signal from the controller. The motor rotor 6 and thus the nut 5 are rotated. The rotation of the nut 5 causes the screw shaft 8 to move in the axial direction (leftward in FIG. 1 [braking force generation direction],
It moves in the right direction in FIG. 1 [braking force release direction]). There is a certain correspondence between the number of rotations of the motor rotor 6 (the nut 5) and the amount of movement of the screw shaft 8 (and, consequently, the magnitude of the braking force and the amount of wear of the pad 10).

The disk brake 1 has an encoder 4 for detecting the number of rotations of the motor rotor 6 (nut 5).
6 (such as an incremental encoder whose absolute position cannot be detected) is provided. Encoder 46
Are located in a concave portion 48 formed in a portion of the claw portion 12 of the caliper 3 where the motor accommodating portion 14 is attached, with a rotary disk 47 having a slit (not shown) attached to the nut 5 by a bolt 63. The detection unit 49 is thus fixed to the motor storage unit 14 via the encoder mounting plate 35. The rotating disk 47 has a hole 47a large enough to accommodate the pressing plate 37 with a margin, and rotates with the nut 5 without being affected by the advancing and retreating of the pressing plate 37 (the screw shaft 8). A cover 61 made of a flexible material is provided between the pressurizing plate 37 and the motor housing 14, and the encoder 46 and the nut 5
Is protected from dust and the like. The cover 61
It has a substantially ring shape, an inner peripheral side portion is fitted in an annular groove (reference numeral omitted) provided on the outer peripheral side of the pressure plate 37, and an outer peripheral side portion is held in the motor housing 14 by bolts 62. The cover 61 is made of a flexible material, and can follow the forward and backward movements of the pressing plate 37 and the nut 5.

The encoder 46 detects the number of rotations of the nut 5 and thus the motor rotor 6 based on the number of times light is transmitted through the slit by the detector 49, and inputs this detection signal to the controller via the encoder wire 50. Like that. The controller uses the detection signal to perform feedback control or the like to grasp the position of the screw shaft 8 and control the motor 7 to generate a desired braking force. The detecting section 49 is provided near the bearing 34, and suppresses the influence of rotational fluctuation of the nut 5 (motor rotor 6), thereby improving detection accuracy.

The brake pedal (not shown) is provided with a pedal force sensor (not shown) for detecting the operation amount of the brake pedal, and this detection signal (pedal force signal) is inputted to the controller. The controller generates the control signal based on the treading force signal from the treading force sensor, and operates the motor 7 to move the screw shaft 8 to generate a braking force. The disc brake 1 is provided with a motor failure detecting means (not shown). Then, while the fluid pressure is shut off in a normal state, if the failure of the motor 7 (the motor 7 does not operate) is detected by the motor failure detection means, the hydraulic pressure generation source is changed to the depression force of the brake pedal instead of the operation of the motor 7. In response, pressure oil is supplied to the hydraulic chamber 28 through the port 27.

In the above-described disc brake 1, the motor rotor 6 (the nut 5) has the caliper 3 (the motor housing 14).
In this state, the stator 43 is inserted into the hollow portion 13 of the caliper 3 and assembled. In the present embodiment, as described above, the extension portion 19 is configured such that the motor housing portion 14 is longer than the end surface of the magnet 18 by the length L on the side opposite to the pad 10 (to the right in FIG. 1). Is provided, the extension 19 serves as a guide when the stator 43 is inserted. Therefore, when the stator 43 is inserted, it is possible to prevent the stator 43 from contacting the magnet 18 and causing the magnet 18 to be damaged.

In the disk brake 1 constructed as described above, when the brake pedal is depressed, the pedaling force signal detected by the pedaling force sensor is input to the controller, and the controller generates a control signal corresponding to the pedaling force signal. And
When the motor 7 is operated, the motor rotor 6 (nut 5) rotates according to the content of the pedaling force signal. When the nut 5 rotates, the screw shaft 8 stopped by the rotation preventing plate 33 moves leftward in FIG. 1 by an amount corresponding to the content of the treading force signal, and generates a braking force corresponding to the treading force.

In the case where the motor 7 has failed, the motor failure detecting means detects the failure of the motor 7, and instead of operating the motor 7, the hydraulic pressure generating source responds to the depression force of the brake pedal. To work. Then, pressure oil is supplied to the hydraulic chamber 28 through the port 27, and the piston 30 is pressed leftward in FIG. Thus, piston 3
When 0 is pressed, the screw shaft 8 applies a turning force to the nut 5 and moves the nut 5 to the left in FIG. 1 while rotating the nut 5 together with the motor rotor 6. For this reason, the inner pad 10a and the outer pad 10b are pressed by the brake rotor 9, and a braking force corresponding to the pedaling force is generated.

In the present embodiment, unlike the above-described prior art, the inner pad 10a and the screw shaft 8 are not connected via the rotation preventing means. Therefore, even if the inner pad 10a rattles with respect to the carrier 2 due to the sliding of the brake rotor 9 at the time of the brake operation, the rattling is not transmitted to the screw shaft 8. For this reason, it is possible to prevent the amount of advance and retreat of the screw shaft 8 that may be caused by the above-described related art from being disordered.

Further, in this embodiment, since the detent plate 33 is provided on the other end of the screw shaft 8, the thickness of the brake pad is reduced and the screw shaft retreats in the above-described conventional technique. There is no possibility that the detent means will come off when the brake pad is replaced.

Further, the amount of wear of the brake pad is grasped by the amount of movement of the screw shaft, the amount of movement of the screw shaft is measured by the amount of rotation of the motor rotor, and when the absolute encoder is used for measuring the amount of rotation, the brake If the brake pad is removed first when returning the screw shaft advance / retreat position to the home position when replacing the pad, the screw shaft will rotate integrally with the motor rotor because the rotation constraint of the screw shaft has been released. As a result, the correspondence between the rotational position of the absolute encoder and the advancing / retreating position of the screw shaft changes. On the other hand, in the present embodiment, the pad 10 is removed and the screw shaft 8 is returned to the initial position. Also, since the screw shaft 8 is rotationally constrained, the positional relationship between the motor rotor 6 of the motor 7 and the screw shaft 8 does not change, and the correspondence between them is maintained in a good state. It can be.

Since there is no need to provide a detent between the brake pad (inner pad 10a) and the nut 5, the motor 7 can be brought closer to the brake rotor 9 in the axial direction of the brake rotor 9, and thereby the caliper 3 Is also moved toward the brake rotor 9 side accordingly, so that the balance is improved. Further, since the moment of the caliper 3 with respect to the carrier 2 can be reduced, uneven wear can be prevented.

Further, in the present embodiment, a pin 22 is bridged between two pairs of supporting portions 21 provided on the carrier 2, and the cylindrical portions provided on both sides of the caliper 3 are connected to the two pins 22. Since the caliper 3 is supported by fitting the respective caliper 3, the caliper 3 is stably held by the carrier 2. The disc brake has a pin provided on the caliper,
There is a type in which the caliper is supported in an overhang state by being inserted into a hole formed in the carrier side. However, in this embodiment, as compared with this type of disc brake, the pair formed in the carrier 2 as described above is provided. The cylindrical portion 20 is fitted to the pin 22 bridged between the support portions 21 to support the caliper 3, so that the caliper 3 can be supported more stably.

In the above-described embodiment, the hydraulic pressure is shut off during normal operation to generate a braking force by driving the motor 7, while
When the motor 7 fails, the hydraulic pressure is communicated and the braking force is generated by using the hydraulic pressure instead of the operation of the motor 7 as an example. Alternatively, the operation by the brake fluid pressure may be assisted by the motor. May be configured.

A rotational speed sensor for the wheels is provided, and the control signal of the controller is adjusted in accordance with the rotational speed detected by the rotational speed sensor to adjust the rotational speed of the motor 7 and, consequently, the braking force. The wheel may be configured not to lock (that is, to operate the ABS).

In a normal case, the braking force may be generated by the hydraulic pressure source, while the motor 7 is controlled in accordance with the rotational speed detected by the rotational speed sensor of the wheel so that the wheel is not locked.

In the above embodiment, the case where the braking force is adjusted in accordance with the operation of the brake pedal has been described as an example. However, the present invention is not limited to this. Even in the case where the operation of the brake pedal is not involved, such as in a system (TCS or TRC), the braking force may be adjusted by controlling the motor 7 according to, for example, a detection signal from predetermined detection means. Good. In this case, compared with a case where a braking force is generated via a hydraulic system (a hydraulic pressure generation source or the like) in response to a detection signal from the detection unit, the number of control targets is reduced, and the responsiveness can be improved accordingly. it can.

In the above embodiment, the case where an oil liquid is used has been described as an example, but another liquid may be used instead.

Further, in the above-described embodiment, an example is described in which a hydraulic pressure source is provided and control can be performed by the hydraulic pressure source. However, the present invention is not limited to this, and does not have a hydraulic pressure source. You may.

In the above embodiment, the encoder 46
Although the case of a so-called light transmission type in which the number of rotations of the nut 5 and thus the motor rotor 6 is detected based on the number of times light is transmitted through the slit by the detection unit 49 is described as an example, a reflection type is used instead. It may be used.

In the above-described embodiment, the case where one protruding portion 41 is provided on the disk portion 40 and one groove 42 is provided correspondingly to the projecting portion 41 so as to prevent rotation is described as an example. The invention is not limited to this, and two or more protrusions 41 and two or more grooves 42 corresponding thereto may be provided to prevent rotation. In addition, a plurality of grooves 4
2, the position of the screw shaft 8 of the ball screw mechanism 4 may be easily adjusted.

[0039]

Since the present invention is a disc brake constructed as described above, unlike the prior art,
Since the brake pad and the screw shaft are not connected to each other via the rotation preventing means, rattling generated on the brake pad is not transmitted to the screw shaft, which is caused by the conventional technology. It is possible to prevent the screw shaft from moving in a reciprocating amount, which may cause a risk.

Further, in the prior art of the type in which the rotation preventing means is removed when the brake pad is replaced and the rotation of the screw shaft is released, the screw shaft rotates integrally with the motor rotor when the brake pad is replaced. On the other hand, when the pad is removed and the screw shaft is returned to the initial position (returning to the home position), the positional relationship between the motor rotor and the screw shaft is restricted due to the rotation of the screw shaft. The correspondence between the two can be maintained in a good state without any change.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a disc brake according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of the disc brake of FIG. 1 as viewed from a claw portion side.

FIG. 3 is a plan view of a partial cross section showing the disc brake of FIG. 1;

FIG. 4 is a cross-sectional view showing a pin portion of FIG. 1;

FIG. 5 is a partial sectional view of the disk brake of FIG. 1 as viewed from a hydraulic cylinder side.

FIG. 6 is a front view showing the detent plate of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc brake 3 Caliper 5 Nut 6 Motor rotor 7 Motor 9 Brake rotor 10 Pad 33 Detent plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadaaki Nakamura 1-6-3 Fujimi, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Tokiko Corporation (72) Inventor Hirotaka Oikawa 1-6-1, Fujimi, Kawasaki-ku, Kawasaki-ku, Kanagawa Prefecture No. Tokiko Corporation

Claims (1)

[Claims] 1. A screw mechanism comprising a screw shaft and a nut for guiding the screw shaft in an axial direction is housed in a caliper, and a motor having a rotor held by the nut is housed in the caliper. A disk brake for generating a braking force by pressing a pad against a brake rotor by moving the screw shaft in an axial direction, wherein the detent means comprises a pad on the screw shaft. A disc brake provided between the caliper and an end opposite to the disc brake.