GB2251466A

GB2251466A - Disc brake

Info

Publication number: GB2251466A
Application number: GB9124224A
Authority: GB
Inventors: Hideyuki Terashima
Original assignee: Nissin Kogyo Co Ltd
Current assignee: Nissin Kogyo Co Ltd
Priority date: 1990-12-11
Filing date: 1991-11-14
Publication date: 1992-07-08
Anticipated expiration: 2011-11-14
Also published as: GB2251466B; GB9124224D0

Abstract

A disc brake of the reaction-force type has a caliper comprising two opposing clamping arms 51, 52 mounted on a bracket 6 in a sliding fashion via slide pins 11 passing through support portions 9 of the bracket. The bracket 6 also has portions 8 for taking up the torque of the first brake pad 31. The slide-pin support portions 9 and the first braking-torque support portions 8 are independent of each other on the body of the bracket 6, so that even if the first braking-torque support portions 8 deflect in use the deflections are not transmitted to the slide-pin support portions 9. Accordingly, no twists take place between the slide pins 11 and the slide-pin support portions 9. Further, the axes 04 of the respective slide pins are arranged in a region defined between second and third straight lines L2 and L3, so that the braking torque of the second friction pad 32 via second braking-torque support portions 34 on the brake caliper results in only a small turning moment on account of the shortened distances between the slide-pin support points 04 and the bracket fixation points 03. Accordingly, the brake caliper is permitted to slide smoothly, and the durability of the bracket can be enhanced. <IMAGE>

Description

Disk Brake The present invention relates to disk brakes of the reaction-force type such as are mainly used for vehicles such as automobiles.

A reaction-force-type disk brake may comprise: a first and a second friction pad disposed on opposite side surfaces of a brake disk so as to oppose each other; a brake caliper provided with a first and a second clamping arm for clamping the friction pads, opposite end portions of the brake caliper in the circumferential direction of the brake disk being supported by a pair of slide-pin support portions of a fixed bracket by means of slide pins at the buter periphery of the brake disk for sliding movements in the direction of the axis of rotation of the brake disk; an urging member such as a piston-cylinder unit provided on the first clamping arm and having a center of urging at a central position of the first friction pad in the circumferential direction of the brake disk for urging the first friction pad against the brake disk; a pair of first braking-torque support portions on the bracket for supporting the braking torque of the first friction pad; and a pair of second braking-torque support portions on the brake caliper for supporting the braking torque of the second friction pad. The bracket is fixed to a stationary member at a pair of fixing points disposed at one side of the brake disk on a straight line crossing a first straight line, which passes through the center of urging and the center of rotation of the brake disk, at a point which is closer to the center of rotation than is the center of urging itself. The fixing points are located on opposite sides of the first straight line.

A disk brake of this type is known from, e.g., Japanese Patent Application Laid-open No. 22660/1977.

In such a disk brake, the body of the bracket is provided with a protruding block used by the first braking-torque support portions for supporting the braking torque of the first friction pad and by the slide-pin support portions for supporting the pins on which the caliper slides.

During operation of the above disk brake, since the braking torque of the first friction pad is supported by the first braking-torque support portions, the first braking-torque support portions deflect to some degree, and hence so does the block on which these support portions are located. This deflection of the first braking-torque support portions is then directly transmitted to the slide-pin support portion. As a result a twist may arise between the slide pin and the slide-pin support portion, reducing the smoothness in slide of the brake caliper in an undesirable fashion.

In addition, the slide-pin support points of the slide-pin support portions in this known brake are arranged closer to the outer periphery of the brake disk than to a third straight line which is parallel to the second straight line and which passes through the urging center.

With the slide-pin support point arranged in this way the distance between the slide-pin support point and the fixing point is large. Therefore, when the braking torque of the second friction pad acts on the slide-pin support point via the second braking-torque support portion and the slide pin, a turning moment of relatively large magnitude is generated about the fixing point. This causes undesirable stresses on the bracket.

According to the present invention there is provided a reaction-force-type disk brake unit comprising a first and a second friction pad to be disposed on the opposite sides of a brake disk so as to oppose each other; a mounting bracket for fixing to a stationary member and having a slide pin support portion at each end; a brake caliper provided with a first and a second clamping arm for clamping the friction pads respectively, opposite end portions of the brake caliper in the circumferential direction of the brake disk being supported by the slide-pin support portions of the fixed bracket via slide pins so that the caliper is capable of sliding movements in the direction of the axis of rotation of the brake disk; an urging member provided on the first clamping arm and having a center of urging at a central position of the first friction pad in the circumferential direction of the brake disk for urging the first friction pad against the brake disk; a pair of first braking-torque support portions on the bracket for supporting the braking torque of the first friction pad; and a pair of second braking-torque support portions on the brake caliper for supporting the brake torque of the second friction pad; wherein the slide-pin support portions and the first braking-torque support portions are arranged independently on the bracket.

Embodiments of the present invention provide a reaction-force-type disk brake in which the deflection of the braking-torque support piston is prevented from being transmitted to the slide-pin support portion and in which the turning moment of the braking torque about the fixing point can be made small.

Preferably the slide-pin support portions and the first braking torque support portions are constituted by separate projections from the main body of the bracket. These projections may extend from each end of the bracket body, approximately at right angles to each other.

In one embodiment of the present invention, there is provided a reaction force type disk brake comprising a first and a second friction pad disposed on opposite side surfaces of a brake disk so as to oppose to each other; a brake caliper provided with a first and a second clamping arm for clamping both the friction pads; opposite end portions of the brake caliper in a circumferential direction of the brake disk being supported by a pair of slide-pin support portions of a fixed bracket through slide pins at an outer periphery of the brake disk for sliding movements in a direction of a rotational axis of the brake disk; an urging member provided on the first clamping arm and having a center of urging at a central position of the first friction pad in the circumferential direction of the brake disk for urging the first friction pad to the brake disk; a pair of first braking-torque support portions mounted on the bracket for supporting a braking torque of the first friction pad; and a pair of second braking-torque support portions mounted on the brake caliper for supporting a brake torque of the second friction pad; wherein a pair of fixing points of the bracket to a stationary member are disposed at one side of the brake disk on a second straight line crossing a first straight line which passes the center of urging and a center of rotation of the brake disk at a portion closer to the center of rotation than the center of urging so that the fixing points are located on opposite sides of the first straight line, and wherein the slide-pin support portions and the first brakingtorque support portions are independently mounted on a body of the bracket, and slide-pin support points of both the slide-pin support portions are arranged in a region defined between the second straight line and a third straight line which passes through the center of urging in parallel with the second straight line.

According to this arrangement, since the first brakingtorque support-portion and the slide-pin support portion are independently provided in the body of the bracket, the deflection of the first braking-torque support portion is not transmitted to the slide-pin support portion. Thus, a twist between the slide pin and the slide-pin support portion due to a braking torque can be prevented from occurring, and the brake caliper is permitted to smoothly slide at all times.

Moreover, by disposing both the slide-pin support points in the specific region as described above, turning moments which arise about the respective fixing points during supporting the braking torque can be made small. Thus, the durability of the bracket can be improved.

The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments taken with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 to 9 illustrate a first embodiment of the present invention, in which Fig. 1 is a plan view of a reaction force type disk brake, Fig. 2 is a view taken along an arrow 2 in Fig. 1, Fig. 3 is a view taken along an arrow 3 in Fig. 1, Fig. 4 is a sectional view taken along a line 4 - 4 in Fig. 2, Fig. 5 is a perspective view of a bracket, Fig. 6 is a sectional view taken along a line 6 - 6 in Fig. 2, Fig. 7 is a sectional view taken along a line 7 - 7 in Fig. 1, Fig. 8 is a sectional view taken along a line 8 - 8 in Fig. 2, and Fig. 9 is a perspective view showing the relationship between a vehicle body and the disk brake; Fig. 10 illustrates a second embodiment and is a view corresponding to Fig. 3; and Fig. 11 illustrates a modification of the second embodiment and is a view corresponding to Fig. 3.

The first embodiment of the present invention will be described with reference to Figs. 1 to 9.

The drawings illustrate a reaction force type disk brake D for an automobile. Referring to Figs 1 l to 4, a brake disk 1 is rotatable with a wheel in the direction of an arrow a during forward travel of the automobile and in a direction of an arrow b during backward travel7 respectively.

First and second friction pads 31 32 are disposed in an opposed relation to opposite side surfaces of the brake disk 1, and these pads 31 32 clamped by first and second clamping arms 51 52 of a brake caliper 4. Opposite ends of the brake caliper 4 located in a circumferential direction of the brake disk 1 are supported by a bracket 6 so as to be slidable along an axis of rotation c of the brake disk 1 at an outer periphery thereof. The bracket 6 is fixed to a knuckle 7 which is a stationary member.

As shown in Figs. 5 and 7, the body 6a of the bracket 6 is formed in a plate-like shape of a narrow width so as to face one side surface of the brake disk 1, A pair of first braking-torque support portions 8 stands on an intermediate portion of the body 6a in an opposed relation to each other, while a pair of cylindrical slide-pin support portions 9 are continuously provided at opposite ends of the body 6a with axes of the support portions 9 being parallel to the axis of rotation c of the brake disk 1.

Thus, the first braking-torque support portions 8 and the slide-pin support portions 9 are provided on the body 6a independently of each other.

As clearly shown in Figs. 1 and 6, each of the first and second clamping arms 51,- 52 has a pair of lugs 10 at opposite ends of each arm in the circumferential direction of the brake disk 1. Slide pins 11 are provided to extend between the two pairs of opposed lugs 10 of both the arms 51 52 and are slidably fitted in the slide-pin support portions 9 of the bracket 6, respectively.Each slide pin 11 is provided at a base end thereof with an external thread portion lla which is threaded in a tapped hole 12 formed in each lug 10 on the side of the first clamping arm 51 while a tip end of each slide pin 11 is fitted in a pin hole 13 formed in each lug 10 on the side of the second clamping arm The portiors of each slide pin 11 between the lug 10 and the slide-pin support portion 9 are covered with expansion dust-proof boot 15.

The brake caliper 4 comprises a block 171 having the first clamping arm 51 and a block 172 having the second clamping arm 52 A pair of opposing protrusions of both the blocks 17 172 are butted, thereby to form a pair of bridge portions 16 which connect the end parts of both the clamping arms 51' 52 in the circumferential direction of the brake disk 1. Both the blocks 171, 172 are secured by two pairs of connecting bolts 18, 19 at the bridge portions 16.

A window 21 is defined by the first and second clamping arms 51 52 and both the bridge portions 16. Both the inner ends of the window 21 in the circumferential direction of the brake disk 1 are formed with stepped portions 22 which extend along the axis of rotation c.

Each of the friction pads 31 32 comprises a back plate 23, and a lining 24 joined to this back plate. As clearly shown in Fig. 7, hook portions 23a formed at opposite ends of each back plate 23 in the circumferential direction of the brake disk 1 are suspended on the stepped portions 22 through retainers 25 for slide movements along the axis of rotation c.

As clearly shown in Fig. 8, at the central part of the window 21 in the circumferential direction of the brake disk 1 a pin hole 26 is formed through the first and second clamping arms 51' 52 so as to extend along the axis of rotation c, and a hanger pin 27 is removably inserted into the pin holes 26 between the arms 51 and The back plates 23 of both the friction pads 31 32' are provided at the central portions of the plates 23 in the circumferential direction of the brake disk 1 with projections 23b, and the hanger pin 27 is inserted through both through-holes 28 formed in the projections 23b. Thus the friction pads 31 32 are suspended by the hanger pin 27.

The hanger pin 27 is prevented from slipping out toward the first clamping arm 51 by abutment of a stop 29 provided on the end of the hanger pin 27 at the side of the second clamping arm 52 on an edge of the pin hole 26.

On the other hand, the hanger pin 27 is prevented from slipping out toward the second clamping arm 52 by engagement of a hook-shaped slip-out-preventing plate 31 with an end portion of this hanger pin which is projected from the outer side surface of the first clamping arm 51 whereupon the plate 31 is secured to the first clamping arm 51 by a screw 32. The tip end of the screw 32 abuts against the hanger pin 27 so as to urge this hanger pin against the inner peripheral surface of the pin hole 26. Thus, the hanger pin 27 is prevented from loosening or rattling in the axial and radial directions thereof.

As clearly shown in Figs. 1 and 7, a pad spring 33 is retained to the hanger pin 27, and the opposite ends of the pad spring 33 resiliently urge the hook portions 23a of the first and second friction pads 31 32 against the stepped portions 22. Thus the friction pads 31 32 are prevented from rattling.

As clearly shown in Fig. 7, the opposite end faces of the back plate 23 of the first friction pad 31 in the circumferential direction of the brake disk 1 abut against the first braking-torque support portions 8, respectively.

Likewise, as shown in Fig. 7, a pair of second braking-torque support portions 34 for supporting the braking torque of the second friction pad 32 are protrusively provided at the base ends of both the constituent parts of the bridge portion 16 in the block 172 on the side of the second clamping arm 52i the opposite end faces of the back plate 23 of the second friction pad 32 in the circumferential direction of the brake disk 1 abut against both the second braking-torque support portions 34, respectively.

In the above construction, changing operations of the friction pads 31 32 are conducted through the window 21.

As clearly shown in Figs. 2 and 4, a pair of cylinders 35 whose openings are directed to the first friction pad 31 are formed along the circumferential direction of the brake disk 1 in the part of the first clamping arm 5 between the connecting bolts 18. One of the cylinders 35 communicates with a known master cylinder through a pressureoil-introducing port 36, and interiors of both the cylinders 35 communicate with each other through a communicating hole 37.

A piston 38 as an urging member, which urges the first friction pad 31 against the brake disk 1, is slidably fitted in each cylinder 35.

As shown in Fig. 7, the urging center 1 of the two pistons 38 exists at the central position of the first friction pad 31 in the circumferential direction of the brake disk 1, that is, at the bisectional point of a straight line connecting the axes of both the pistons 38r in the illustrated embodiment.

A pair of fixing points of the bracket 6 to the knuckle 7, i.e. a pair of centers 03 of fixing bolt inserting holes 39 in the illustrated embodiment are disposed at one side of the brake disk 1 on a second straight line L2 crossing (at right angles in the illustrated embodiment) a first straight line L1 which passes the urging center 0 1 and the center of rotation 02 of the brake disk 1 at a portion closer to the center 2 than the center 1 In addition, the centers 03 are respectively located on either side- of the first straight line L1.

The slide-pin support points of the slide-pin support portions 9, that is, the centers 04 of pin-inserting holes 40 in the illustrated embodiment, are respectively arranged in a region defined between the second straight line L2 and a third straight line L3 which passes through the urging center 1 in parallel with this second straight line L2.

As clearly shown in Fig. 3, three reinforcing ribs 41 which are substantially straight are formed on the outer side surface of the second clamping arm 52 and substantially in parallel with one another so as to extend near to opposite end portions of this clamping arm 52 in the circumferential direction of the brake disk 1.

Next, the operation of this embodiment will be described.

When, during forward travel of the automobile, pressure oil is supplied from the master cylinder (not shown) into both the cylinders 35 through the pressure-oil-introducing port 36 by operating a brake pedal or the like, both the pistons 38 are advanced by the hydraulic pressure against the first friction pad 31. Consequently, the friction pad is ismoved while sliding on the stepped portion 22 of the brake caliper 4 and the hanger pin 27 and is urged against ohe side surface of the brake disk 1.Then, by a reaction attendant upon the urging, the brake caliper 4 is slidingly moved in the opposite direction to the pistons 38 through the slide pins 11 and the second friction pad 32 is urged against the other side surface of the brake disk 1 by the second clamping arm 52 Thus, braking is applied to the brake disk 1.

During such braking, the braking torque of the first friction pad 31 is supported by the first braking-torque support portions 8 of the bracket 6, while the braking torque of the second friction pad 32 is supported by the second braking-torque support portions 34 of the brake caliper 4.

In this case, when the first braking-torque support portions 8 of the bracket 6 support the braking torque of the first friction pad 31 the portions 8 deflect to a greater or lesser extent. However, since the first braking-torque support portions 8 and the slide-pin support portions 9 are independent of each other, these deflections are not transmitted to the slide-pin support portions 9. Thus, twists between the slide pins 11 and the slide-pin support portions 9 due to the braking torque are prevented from occurring.

Furthermore, the relationship between the slidepin support points 04 and the fixing points 03 of the bracket 6 is such that the distance between the points 04 and 03 is shortened. Therefore, even when the braking torque of the second friction pad 32 acts on the slide-pin support points 04 through the second braking-torque support portions 34 as well as the slide pins 11, turning moments generated about the fixing points 03 are relatively small. Thus, the durability of the bracket 6 can be enhanced.

Fig. 9 shows the arrangement of the disk brake D on a vehicle body B. The brake caliper 4 is disposed so that the window 21 is directed towards the front of the vehicle with the second clamping arm 52 located on the side of a wheel W, and the bracket 6 is fixed to the knuckle 7. The brake disk 1 is secured to a hub 42 for mounting the wheel W.

With the brake caliper 4 disposed in this manner, an airstream is introduced into the brake caliper 4 through the window 21, and the reinforcing ribs 41 function also as cooling fins. Therefore, the friction pads 31 32 and the brake caliper 4 can be efficiently cooled.

Fig. 10 illustrates the second embodiment of the present invention. This embodiment has an arrangement similar to that of the first embodiment except that, in a second arch clamping arm 52 which extends along the arc shape of a brake disk 1, a pair of lugs 10 located at opposite ends of this arm 52 in the circumferential direction of the brake disk 1 are connected by a tie bar 44.

If both the lugs 10 are connected by the tie bar 44 as described above, when a braking torque is supported on the side of the second clamping arm 52' it is possible to restrain the displacement of one of the lugs 10 by the tie bar 44. Thus, twists between slide pins 11 and slidepin support portions 9 can be prevented from occurring, thereby to facilitate the smooth slide movement of the brake caliper 4.

In addition, Fig. 11 illustrates a modification of the second embodiment. A connection portion 45 for connecting a tie bar 44 with a second clamping arm 52 is provided at the intermediate portion of the tie bar 44, thereby enhancing the strength of the tie bar 44.

Claims

CLAIMS:

1. A reaction-force-type disk brake unit comprising a first and a second friction pad to be disposed on the opposite sides of a brake disk so as to oppose each other; a mounting bracket for fixing to a stationary member and having a slide pin support portion at each end; a brake caliper provided with a first and a second clamping arm for clamping the friction pads respectively, opposite end portions of the brake caliper in the circumferential direction of the brake disk being supported by the slide-pin support portions of the fixed bracket via slide pins so that the caliper is capable of sliding movements in the direction of the axis of rotation of the brake disk; an urging member provided on the first clamping arm and having a center of urging at a central position of the first friction pad in the circumferential direction of the brake disk for urging the first friction pad against the brake disk; a pair of first braking-torque support portions on the bracket for supporting the braking torque of the first friction pad; and a pair of second braking-torque support portions on the brake caliper for supporting the brake torque of the second friction pad; wherein the slide-pin support portions and the first braking-torque support portions are arranged independently on the bracket.

2. A disc brake unit according to claim 1 in which the bracket has a generally longitudinal body with fixing points at each end for fixing to the vehicle, and the slide-pin support portions on the one hand and the first braking-torque support portions on the other hand are constituted respectively by two separate pairs of projections from the ends of the bracket body.

3. A disc brake unit according to claims 1 or 2, in which fixing points of the bracket to the stationary member are disposed at one side of the brake disc on a second straight line crossing a first straight line which passes the center of urging and the center of rotation of the brake disc at a point which is closer to the center of rotation than is the center of urging, the fixing points being located on the opposite sides of the first straight line.

4. A disc brake unit according to claim 3 in which the slide-pin support points of the two slide-pin support portions are arranged in a region defined between the second straight line and a third straight line which passes through the center of urging in parallel with the second straight line.

5. A disc brake unit according to any preceding claim, wherein a pair of lugs is provided at opposite end portions of the second clamping arm in the circumferential direction of said brake disk for supporting the slide pins.

6. A disc brake unit according to claim 5 in which the lugs are connected by a tie bar.

7. A disc brake unit substantially as described herein with reference to any of the embodiments shown in the accompanying drawings.