GB2211253A

GB2211253A - Ventilated brake disc

Info

Publication number: GB2211253A
Application number: GB8724296A
Authority: GB
Inventors: Adrian David Campbell
Original assignee: Jaguar Cars Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 1987-10-16
Filing date: 1987-10-16
Publication date: 1989-06-28
Also published as: GB8724296D0

Abstract

A ventilated brake disc, for example for use on a vehicle, comprises first and second braking surface plates (1 and 2 respectively) which are substantially annular and are spaced apart axially. The first and second braking surface plates incorporate respective first and second radially extending braking surfaces (5 and 6) against which, in use, brake pads are urged. For connecting the brake disc to a wheel hub, generally triangular portions (12) of a disc mounting element (7) extend radially between the first and second braking surface plates and are connected at their apices (12a) with each of the first and second braking surface plates (1, 2) by transverse elements (13) intermediate the radially inner and the radially outer extent of the first and second braking surfaces (5, 6). <IMAGE>

Description

VENTILATED BRAKE DISC The present invention relates to a ventilated brake disc, for example for use on a vehicle.

Ventilated brake discs are known for use on vehicles, the ventilation assisting in cooling the disc and resulting in improved braking performance. However, in the known brake discs, the friction between the disc and the brake pads under braking generates heat which causes distortion in the disc and reduces braking performance.

It is an object of the present invention to provide a ventilated brake disc which has reduced thermal distortion.

According to the present invention there is provided a ventilated brake disc which comprises: first and second braking surface plates which are substantially annular and are spaced apart axially, the first and second braking surface plates incorporating respective first and second radially extending braking surfaces; and a disc mounting element for connection to a wheel hub, the disc mounting element extending radially between the first and second braking surface plates and being connected with each of the first and second braking surface plates intermediate the radially inner and the radially outer extent of the first and second braking surfaces.

The first and second braking surface plates may be spaced apart axially by at least one fin extending between the plates. Preferably the brake disc includes a plurality of radially extending fins extending between the plates.

The disc mounting element is preferably connected with the braking surface plates substantially midway between the radially inner and the radially outer extent of the first and second braking surfaces.

The brake disc may include a plurality of apertures formed through the disc mounting element and arranged around the disc mounting element in a circumferential direction.

The disc mounting element is preferably belled.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a cross-sectional view, taken in a radial direction, through a part of a ventilated brake disc according to the present invention; and Figure 2 is an elevational view, taken in an axial direction, of part of the ventilated brake disc shown in Figure 1.

The figures show a ventilated brake disc which comprises first and second braking surface plates 1 and 2 respectively. The plates 1 and 2 are substantially annular and are spaced apart axially by a plurality of radially extending fins 3 and 4. Fins 3 have a greater length than fins 4. Machined onto the outer surfaces of the plates 1 and 2 are respective first and second braking surfaces 5 and 6 against which, in use, brake pads (not shown) are urged.

A disc mounting element 7 is generally bell-shaped and comprises a generally annular inner portion 8, a conical portion 9 and an outer portion 10. The conical portion 9 has a small included angle and close to the transformation with the outer portion 10 is formed with a plurality of apertures 11 which are arranged around the conical portion 9. The outer portion 10 is formed with a plurality of generally triangular elements 12 which are connected at their apices 12a to the inner sides of the plates 1 and 2 by way of a transverse element 13 of substantially circular cross-section. The connection between the disc mounting element 7 and the plates 1 and 2 is substantially midway between the radially inner and the radially outer extent of the first and second braking surfaces 5,6.It will be noted that the braking surface 6 extends radially inwardly a greater distance than the braking surface 5. However, the additional distance is small and therefore has no significance so far as the present invention is concerned.

The brake disc is made by integrally casting the disc in a single operation and subsequently machining the braking surfaces and any other areas that may be required.

In use of the ventilated brake disc according to the present invention, when the brake is energised brake pads (not shown) are urged against the braking surfaces 5 and 6. Friction slows the rate of rotation of the brake disc and generates heat which causes the temperature of the brake disc to rise. Because the disc mounting element 7 is connected directly to the braking surface plates 1 and 2 intermediate the radially inner and the radially outer extent of the braking surfaces, the braking surface plates are unconstrained at their inner and outer peripheral edges. The braking surface plates are therefore able to expand and contract freely and, in addition, there is no build-up of heat at either of the peripheries relative to the other. This results in reduced thermal distortion of the braking surfaces. Due to the connection of the disc mounting element 7 directly to both braking surface plates 1 and 2, heat generated during use of the brakes is conducted away from both plates at substantially equal rates. This contributes to a further reduction in thermal distortion. We have also found that the connection between the disc mounting element 7 and the braking surface plates 1 and 2 intermediate the radially inner and the radially outer extent of the braking surfaces 5 and 6 provides an improved mechanical structure which in itself also improves braking performance.

Claims

1. A ventilated brake disc which comprises: first and second braking surface plates which are substantially annular and are spaced apart axially, the first and second braking surface plates incorporating respective first and second radially extending braking surfaces; and a disc nounting element for connection to a wheel hub, the disc mounting element extending radially between the first and second braking surface plates and being connected with each of the first and second braking surface plates intermediate the radially inner and the radially outer extent of the first and second braking surfaces.

2. A brake disc as claimed in claim 1, wherein the first and second braking surface plates are spaced apart axially by at least one fin extending between the plates.

3. A brake disc as claimed in claim 2 and including a plurality of radially extending fins extending between the plates.

4. A brake disc as claimed in claim 1, 2 or 3, wherein the disc mounting element is connected with the braking surface plates substantially midway between the radially inner and the radially outer extent of the first and second braking surfaces.

5. A brake disc as claimed in any preceding claim and including a plurality of apertures formed through the disc mounting element and arranged around the disc mounting element in a circumferential direction.

6. A brake disc as climed in any preceding claim, wherein the disc mounting element is belled.

7. A ventilated brake disc substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.