GB2221265A

GB2221265A - Drum brakes

Info

Publication number: GB2221265A
Application number: GB8818213A
Authority: GB
Inventors: Mervyn Brian Packer; David William Gardener
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1988-07-30
Filing date: 1988-07-30
Publication date: 1990-01-31
Also published as: GB8818213D0

Abstract

A drum brake includes an annular backing plate (12) which is supported adjacent its inner periphery, coaxially of an axle (14) on suspension member (13), by means of a plurality of angularly spaced bolts (15). A resilient metal strap (25) is secured at one end to suspension member (13) by a bolt (15), the other end of the strap (25) acting against the backing plate (12) at a non-nodal position on its outer periphery and serving to damp out vibrations in the backing plate (12). The invention is also applicable to the damping of vibrations in the discs of disc brakes. In an alternative embodiment the metal strap 25 may be welded to the suspension member. <IMAGE>

Description

BRAKES The present invention relates to brakes and in particular to the damping of vibrations in brakes.

In conventional brakes, components which are connected centrally to a support member and extend annularly, for example the backing plates of drum brakes or the discs of disc brakes, tend to vibrate at their outer peripheries generating significant noise levels. The present invention provides means for damping such vibrations and reducing the noise generated.

According to one aspect of the present invention, a brake includes an annular member which is supported adjacent its inner periphery, means being provided to apply a load to the outer periphery of the annular member.

Preferably the means for applying a load to the annular member comprises a resilient metal strap which is connected at one end to a support mernber or to a portion of the annular member adjacent its supported inner periphery. The strap may engage the outer periphery under compression.

Alternatively the strap may be secured to the outer periphery and stressed to apply torsional load to the annular member. The load applied to the annular member will depend upon its dimensions and in particular its thickness but typically will be of the order of 50N to 15own.

Various embodiments of the invention are now described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates, in cross section, a drum brake in accordance with the present invention; Figure 2 illustrates the brake disc of a disc brake in accordance with the present invention; Figure 3 illustrates the back plate of an alternative form of drum brake in accordance with the present invention; and Figure 4 illustrates a modification to the embodiment illustrated in Figure 3.

Figure 1 illustrates a drum brake in which the brake drum 10 is mounted for rotation on a hub 11. An annular backing plate 12 is mounted on a suspension member 13 coaxially of the axle 14, by means of a plurality of angularly spaced bolts 15 (only one shown). The brake shoes and actuating mechanisms have been omitted for clarity.

The backing plate 12 has an outer peripheral flange 16 which extends into a circumferential groove 17 in the cylindrical wall 18 of the drum 10. An annular dust cover 19 with further flange 20 which extends axially around the outer face of wall 18, is spot welded to the outer periphery of the backing plate 12.

A resilient metal strap 25 is secured to the suspension member 13 by bolt 15. The strap 25 is bent so that when secured to the suspension member 13 it will engage the dust cover 19 under compression at a non-nodal position on the backing plate 12, and apply a load of the order of 50N thereto.

Optionally, in order to avoid metal to metal contact between the strap 25 and dust cover 19, which may lead to fretting corrosion, a layer of non-metallic material may be provided therebetween. Such material may for example be in the form of a plastic coating on the end of the strap 25 or a pad of gasket-type material which is stuck to one of the surfaces. A suitable gasket material is commercially available as WOLVERINE.

With the above arrangement, vibration of the backing plate 12 will be damped by frictional engagement of the strap 25.

Figure 2 illustrates a brake disc with similar damping means to that illustrated in Figure 1. In this embodiment, a metal strap 25 is secured by one of the bolts 30 by which the disc 31 is secured to the hub 11, so that strap 25 engages the outer periphery of the bell portion 32 of disc 31, a load of between 50N and 150N being applied to the disc 31. Again the strap 25 will act to frictionally damp vibrations in the disc 31. As with the embodiment illustrated in Figure 1, a layer of the material may be interposed between the strap 25 and disc 31. Selection of a non-nodal position is less relevant in the case of the disc since the vibration wave remains stationery relative to the rotating disc.

In both of the embodiments illustrated in Figures 1 and 2, additional straps 25 may be provided to engage at angularly spaced locations about the periphery of the backing plate 12 or disc 31.

On the backing plate 12 illustrated in Figure 3, a resilient metal strap 40 is spot welded or secured by other suitable means at one end 41 to the dust cover 19 at a non-nodal position. The strap 40 which in its relaxed state is of the configuration shown in broken line, is deformed so that its other end 43 engages an inner peripheral portion of the backing plate 12 and is spot welded or secured by other suitable means thereto. The stressing of the strap 40 will thus apply a torque between the supported inner peripheral portion of the backing plate 12 and the unsupported outer periphery, which will pretension the backing plate 12 and dampen any vibrations therein which have a magnitude less than the pre-tensioning load.

In the embodiment illustrated in Figure 4, the strap 45 is bent so that it will abut the backing plate 12 when end 46 is spot welded to the dust cover 19, but end 47 extends away from the backing plate 12 and must be deformed into engagement with the inner peripheral portion of the backing plate 12 to be secured thereto.

In the embodiments illustrated in Figures 3 and 4, straps 40 or 45 may be provided at angularly spaced non-nodal positions around the backing plate 12. The straps 40 or 45 may alternatively be provided by tabs formed integrally of the dust cover 19.

Claims

1. A brake including an annular member which is supported adjacent its inner periphery, means being provided to apply a load to the outer periphery of the annular member.

2. A brake according to Claim 1 in which a resilient metal strap is connected at one end to a support member, the end of the strap engaging the annular member adjacent its outer periphery.

3. A brake according to Claim 1 in which a resilient metal strap is connected at one end adjacent the inner supported periphery of the annular member, the other end of the strap engaging the annular member adjacent its outer periphery.

4. A brake according to Claim 2 or 3 in which the metal strap frictionally engages the annular member adjacent its outer periphery.

5. A brake according to Claim 4 in which a non-metallic interlayer is provided between the strap and outer periphery of the annular member.

6. A brake according to Claim 5 in which a plastic coating is provided on the end of the strap that engages the outer periphery of the annular member.

7. A brake according to Claim 5 in which a pad of gasket material is stuck to one of the frictionally engaging surfaces.

8. A brake according to Claim 1 or 2 in which the end of the strap is secured to the annular member adjacent its outer periphery, the strap being deformed to provide a torque which pre-tensions the annular member.

9. A brake according to Claim 8 in which the strap forms an integral part of an annular formation secured to the outer periphery of the annular member.

10. A brake according to any one of Claims 1 to 9 in which a load of from 50N to 150N is applied to the annular member adjacent its outer periphery.

11. A brake according to any one of Claims 1 to 10 in which a plurality of means are provided to apply loads to the annular member adjacent its outer periphery, at angularly spaced non-nodal positions.

12. A brake substantially as described herein with reference to, and as shown in, Figures 1, 2, 3 and 4 of the accompanying drawings.