GB2161226A

GB2161226A - Disc brake

Info

Publication number: GB2161226A
Application number: GB08416895A
Authority: GB
Inventors: Masahito Okajima
Original assignee: Tokico Ltd
Current assignee: Tokico Ltd
Priority date: 1984-07-03
Filing date: 1984-07-03
Publication date: 1986-01-08
Also published as: GB8416895D0; DE3425406A1

Abstract

The brake includes a stationary carrier 2, a pair of friction pads 4, 8 disposed on opposite sides of a rotatable disc D, each friction pad having a rigid backing plate 3, 7, a piston 10 for pressing pad 4 against the disc D and a shim 5 interposed between the backing plate 3 of friction pad 4 and piston 10, at least the trailing circumferential end of the shim being formed to constitute a tongue portion (5b, Figure 4) inserted between the backing plate 3 and the carrier 2 to transmit torque but to reduce squeal. As shown, both ends have tongue portions (5b). As shown a shim 6 is interposed between backing plate 7 of pad 8 and arm portion 1b of sliding caliper 1 and this shim 6 has tongue portions 6c to prevent shim 6 from escaping as well as tongue portion(s) 6b on circumferential (opposite) end(s). Shim 5 may also have tongue portions similar to 6c. <IMAGE>

Description

SPECIFICATION Disc brake This invention relates to a disc brake.

One of conventional disc brake comprises a stationary carrier, a caliper mounted on the carrier and being slidable in the direction parallel to the axis of a rotatable disc, a pair of friction pads disposed on opposite sides of the disc, and a piston incorporated in the caliper for pressing directly one of the friction pads against one surface of the disc.

The caliper has a leg portion straddling a part of the outer circumference of the disc to extend to the rear surface of the other friction pad, so that when the piston presses the one friction pad against the disc the reaction force thereof displaces the caliper in the direction opposite to the movement of the piston and the leg portion of the caliper applies the pressing force on the other friction pad. The friction pad usually comprises a rigid backing plate and a friction material attached thereon.

In the disc brake of the kind aforementioned, it is sometimes observed squal sounds in actuating the brake due to vibrations of the disc, friction pads, the piston or the caliper in the direction parallel to the axis of the disc. For suppressing squal sounds, it has been proposed to interpose a thin, flat plate usually called as a shim between the friction pads and the piston or the leg portion of the caliper.

The shim is effective in controlling or damping the vibrations of the friction pad in the direction parallel to the axis of the disc, however, in case when one or both friction pads are slidably mounted on the stationary carrier so that the braking torque generating in the friction pad during the actuation of the brake is transmitted directly to the carrier, the friction pad tends to vibrate in the direction of the rotation of the disc. In such cases, the shim of prior art is not effective to reduce or damp the vibrations of the friction pad since the shim is a flat plate extending a plane perpendicular to the axis of the rotation of the disc.

The present invention aims to relieve aforesaid shortcomings and, according to the invention, the circumferential opposite end portions of the shim are bent generally orthogonally to constitute tongue portions which are inserted between the backing plate of the friction pad and the carrier.

The braking torque generated in the friction pad in applying brakes is transmitted to the carrier through the tongue portion of the trailing side with respect to the rotational direction of the disc. The shim can effectively restrict vibrations in the rotational direction of the disc thereby reducing squeal sounds.

The invention will hereinafter be explained in detail with reference to accompanying drawings illustrating preferred embodiments of the invention, in which: Figure 1 is a longitudinal sectional view of a disc brake according to the invention; Figure 2 is a rear view of the disc brake of Fig. 1; Figure 3 is a perspective view of a shim incorporated in the disc brake of Figs. 1 and 2; and Figure 4 is a perspective view of another shim.

The disc brake illustrated in the drawings comprises a stationary carrier 2 adapted to be mounted on a non- rotatable part of a vehicle, a caliper 1 slidably mounted on the carrier 2 by means of a pair of parallel pins (not shown) so that the caliper 1 can displace in the transverse direction in Fig. 1 or in the direction parallel to the axis of a rotatable disc D, and a pair of friction pads 4 and 8. The friction pads have rigid backing plates 3 and 7 respectively and are disposed on opposite sides of the disc D. The caliper 1 has a generally inverted U shaped configuration in Fig. 1 to straddle a part of the outer periphery of the disc D and has two arm portions la and 1b. A piston 10 is provided in a cylinder bore of one arm portion 1a for pressing the friction pad 4 against one surface of the disc D.

Another arm portion 1b extends to the rear side of the another friction pad 8 and, when the caliper 1 displaces rightwards in Fig. 1 due to the reaction force of the piston 10, the arm portion 1b presses the another friction pad 8 against the disc D.

According to the invention, a shim 5 is interposed between the piston 10 and the backing plate 3 of the friction pad 4 and, a shim 6 is interposed between the backing plate 7 of the friction pad 8 and the arm portion 1b of the caliper 1. The circumferential opposite ends of the shim 5 are bent to form tongue portions 5b and 5b as shown in Fig. 4 and, the tongue portions 5b are inserted between the circumferential opposite ends of the backing plate 3 of the friction pad 4 and the circumferentially spaced arm portions 2a and 2b of the carrier 2 respectively.In actuating the brake, braking torque is generated in the friction pad 4 and is transmitted through the backing plate 3 and the tongue portion 5b of the trailing side (the right side as viewed in Fig. 2) to the arm portion 2b of the carrier 2.

Similarly, a shim 6 is disposed between the backing plate 7 of the friction pad 8 and the arm portion 1 b of the caliper 1. The shim 6 has tongue portions 6b and 6b on circumferentially opposite ends and tongue portions 6c and Sc on radially outer ends, as shown in Fig. 3. The tongue portions 6b and 6b are inserted respectively between the arm portions 2a and 2b of the carrier 2 and the backing plate 7 of the friction pad 8. The tongue portions 6c and Sc are disposed radially outwards of the backing plate 7 thereby preventing the shim 6 from escaping out.

The function of the shims 5 and 6 will now be explained.

When the bracking force is applied on friction pads 4 and 8 to clamp the disc D therebetween, the friction pads tend to vibrate in the rotational direction of the disc D, however, the tongue portions 5b and 6b of the shins 5 and 6 are interposed between the arm portion 2b of the carrier 2 and the backing plates 3 and 7 of the friction pads 4 and 8 respectively thereby restricting the vibrations of the friction material and backing plates of the friction pads 4 and 8 in the rotational direction of the disc D thereby preventing effectively squeal sounds. The shims 5 and 6 can act also as heat in sulating members, which prevent effectively the heat generating between the disc D and the friction pads 4 and 8 from being transmitted to the carrier 2.The main portions or flat surface portions 5a and 6a of the shims 5 and 6 act to restrict vibrations of friction pads 4 and 8 in the direction parallel to the axis of the disc D, thus, it is possible to reduce substantially squeal sounds.

The shims 5 and 6 are preferably formed of metal plate such as stainless steel.

In the embodiment, tongue portions 6c and 6c on the radially outer end are provided on the shim 6 only, but the shim 5 may also have similar tongue portions, further, the tongue portions 5b, 6b of the leading side with respect to the rotation of the disc D may be omitted particularly when the disc brake is mounted on a two-wheeled vehicle.

According to the invention, the vibrations of the friction pads in the direction of the rotational direction of the disc and in the direction parallel to the axis of the disc can effectively suppressed by the shim, thus, it is possible to effectively reduce squeal sounds.

Claims

1. A disc brake including a stationary carrier, a pair of friction pads disposed on opposite sides of a rotatable disc, each friction pad having a rigid backing plate and a friction material attached thereto, means for pressing the friction pads against the disc, at least one of said friction pads being slidably mounted on the carrier with circumferential opposite ends of said on friction pad being slidably guided by the carrier, and a shim interposed between the backing plate of said one friction pad and said pressing means, wherein the circumferential opposite ends of said shim are formed to constitute tongue portions which are inserted between the backing plate and the carrier.

2. A disc brake according to Claim 1 wherein the braking torque in actuating the disc brake is transmitted from the friction pad to the carrier through the tongue portion of the shim.

3. A disc brake according to Claim 1 wherein said passing means comprises a caliper slidably mounted on the carrier and a hydraulic piston incorporated in the caliper.

4. A disc brake according to claim 1 wherein a second tongue portion is formed on the shim which is bent to extend radially outwards of the backing plate for engaging therewith.

5. A disc brake substantially as hereinbefore described with reference to, and as illustrated in Figures 1 to 3 or these Figures as modified by Figure 4.