GB2346182A

GB2346182A - Brake disc pad

Info

Publication number: GB2346182A
Application number: GB9901661A
Authority: GB
Inventors: Dene Stephen Williams
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-01-27
Filing date: 1999-01-27
Publication date: 2000-08-02
Also published as: GB9901661D0

Abstract

A brake disc pad 10 has a groove formed in a back plate parallel to but offset from the radial centre line of the pad. This is to produce a pad with non-symmetrical stiffness thereby to reduce standing wave vibrations in the pad which cause brake squeal.

Description

Pipe Brakes The present invention relates to disc brakes for vehicles and in particular to the problem of brake squeal.

Analysis has established that brake squeal in disc brakes is partly due to vibrations set up in the brake pads. The$e vibrations tend to be symmetrical about the radial centreline of the pads, with a node at each end of the pad and an antinode in the centre. The present invention aims to make use of this analysis to provide an improved disc brake.

Accordingly the present invention provides a pad for a disc brake having radially inner and radially outer edges and two ends and a centre line arranged to extend in use radially of a brake disc, the pad comprising a back plate and a friction lining, wherein the back plate is arranged so as to have a stiffness which varies in a non-symmetrical manner about the centre line.

Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a section through a brake pad according to the invention, and Figure 2 is a front view of the pad of Figure 1.

A pad 10 for a disc brake comprises a back plate 12 with a friction lining 14 mounted on it. The pad has parallel ends, 16,18, a radially inner edge 20 arranged in use to be nearest the axis of the brake disc which the pad operates on, and a radially outer edge 22 arranged to be, in'use, furthest from that axis. The pad is therefore approximately symmetrical in hape about a centre line 24 which runs parallel to the two ends 16,18 and in a direction which will be radial to the disc when the pad is in use.

When the pad 10 is in use it is compressed against a brake disc by one or more pistons acting on the back plate. As discussed above the problem of brake squeal is, in part, caused by vibrations set up in the disc. These vibrations tend to take the form of a standing wave with a node at each end 16,18 of the pad and an anti-node on the centre line 24. In order to counteract the tendency for such wave patterns to form, the back plate, which is otherwise of uniform thickness, is formed with a groove 26 running down it, parallel to the centre line 24 and offset from it to one side. In the embodiment shown the groove 26 has one edge substantially on the centre line 24. The effect of the groove 26 is to produce a region, in this case a line, of reduced stiffness running down the back plate, to one side of the centre line 24. This gives the back plate 12, and therefore the whole pad 10, a stiffness which is non-symmetrical about the centre line 24. This tends to prevent a standing wave such as that described above from occurring.

It will be appreciated that the cross section of the groove is not critical and could take a variety of forms. Similarly instead of a single groove, either a plurality of grooves, or a row of cut-outs, blind bores, or depressions running parallel to the centre line thereby forming a line of reduced stiffness could be used.

A line of through bores or apertures right through the back plate could also be used.

Claims

CLAIMS 1. A pad for a disc brake having radially inner and radially outer edges and two ends and a centre line arranged to extend in use radially of a brake disc, the pad comprising a back plate and a friction lining, wherein the back plate is arranged so as to have a stiffness which varies in a non-symmetrical manner about the centre line.
2. A pad according to claim 1 wherein the back plate comprises a plate of substantially uniform thickness with one or more cut-outs formed in it to provide a region of reduced stiffness.
3. A pad according to claim 2 wherein the region comprises a line of reduced stiffness extending across the back plate parallel to the centre line.
4. A brake disc pad substantially as hereinbefore described with reference to the accompanying drawings.