GB2353013A

GB2353013A - Vehicle brake cooling arrangement

Info

Publication number: GB2353013A
Application number: GB9918910A
Authority: GB
Inventors: Michael Neil Basnett
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-08-12
Filing date: 1999-08-12
Publication date: 2001-02-14
Anticipated expiration: 2019-08-12
Also published as: GB2353013B; GB9918910D0

Abstract

A vehicle has a gearbox (12) with a clutch assembly (16) and inboard brakes (22) on either side. The clutch assembly (16) includes a rotating member (30) with ribs (31) formed on it which form a fan for supplying cooling air through ducts (34,36) to the brakes (22). A further embodiment includes a bypass valve (38) which is opened at high speeds to allow ram air to be directed straight to the brakes (22), bypassing the fan.

Description

2353013 Vehicle Brake Cooling The present invention relates to the cooling

of vehicle brakes.

It is known from DE 41 38 464 A to provide a cooling air inlet with ducts leading both to a brake and an internal combustion engine and a valve for switching the air flow onto either the brake or the engine.

The present invention provides a vehicle having a transmission including a gear box, inboard brakes which are in a fixed position relative to the gear box, cooling ducts for supplying cooling air to the brakes and air driving means, driven from the transmission, for driving air through the ducts towards the brakes.

I Preferably the air driving means forms part of a clutch assembly of the transmission. For example the air driving means may comprise a fan operated by rotation of a flywheel.

Preferably the vehicle includes a bypass duct for allowing air flowing to the brakes to bypass the air driving means.

The present invention also provides a vehicle having a power train, a brake, ducting for supplying cooling air to the brake including an air driving duct having air driving means in it and a bypass duct arranged to bypass the air driving means, the air driving means being driven from the power train, and valve means arranged to open the air driving duct and close the bypass duct, or open the bypass duct and close the air driving duct.

Preferably the air driving means includes a rotating member in a space and the ducting is arranged, when the air driving duct is closed, to form a venturi pump so that passage of air through the bypass duct reduces the pressure in the space, thereby reducing the resistance to rotation of the rotating member.

Preferably the bypass duct is arranged to be opened when the vehicle is travelling above a predetermined speed.

Preferably the vehicle further comprises valve means for opening the bypass duct. The valve means may be arranged to be operated by the flow of air to open the bypass duct. Alternatively the vehicle may further comprise control means and sensing means, the control means being arranged to open the bypass duct in response to signals from the sensing means.

I Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a plan view of part of the front of a vehicle according to the invention, Figure 2 is a plan view corresponding to Figure 1 of the same vehicle in another condition, and Figure 3 is a section through a brake assembly forming part of the vehicle of Figure 1.

Referring to Figure 1 a vehicle 10 has a power train including a transmission, comprising a gearbox 12 mounted towards its front end 14 and a clutch assembly 16 mounted on the front of the gearbox 12, and an engine (not shown) providing torque to the clutch. Drive shafts 18 for the front wheels of the vehicle are connected via universal joints 20 to drive flanges which receive driving torque from the gearbox 12 via a differential mechanism, and brake disks 22 are also mounted on the drive flanges. The brake disks 22 and callipers are enclosed in brake housings 24 and coohng ducts 26 are provided connecting the brake housings 24 to air inlets 28 at the front of the vehicle.

The clutch assembly 16 includes a centrifugal fan 30 which can comprise a 5 series of radial ribs formed on the flywheel, or a separate member with radial ribs 31 on it mounted for rotation with the flywheel. The clutch assembly is housed in an enclosed space 32 and a fan feed duct 34 leads from the coohng duct 26 to the centre of the fan 30 and a fan output duct 36 leads from a point at the outer circumference of the space 32 back to the inlet duct 26 at a point further 10 downstream, i.e. closer to the brakes. A valve 38 is provided in the coohng duct 26 between ihe entrance to the fan feed duct 34 and the end of the fan output duct 36.

If the vehicle is travelling slowly the valve 38 closes off the coohng duct just downstream of the inlet to the fan feed duct 34 so that air entering through the air inlet 28 reaches the brake disk 22 via the fan 30. Because the fan 30 is driven by the flywheel and therefore is operating whenever the engine is running, a flow of air over the brake disks is maintained at low vehicle speeds, or when the vehicle is stationary. When the vehicle speed rises the valve 38 closes the fan feed duct and opens the fan bypass duct. This can be achieved either by electric or other controlled actuation of the valve, in response to sensors such as vehicle speed sensors, or simply by using a return spring on the valve so that above certain vehicle speeds, air pressure on the valve opens up the fan bypass duct. In any case, when the fan bypass is open the fan does not operate to force air towards the brakes, this being achieved simply by the higher pressure in front of the vehicle. However the passage of the air past the end of the fan output duct 36 acts as a venturi pump and reduces the air pressure in the space 32 around the clutch assembly. This reduces the amount of power used to rotate the fan while it is not in use.

Referring to Figure 3, in a second embodiment of the invention the brake assembly is modified slightly to improve the cooling effect of the air supplied through the cooling duct. Parts corresponding to those in Figures 1 and 2 are given the same reference numeral preceded by a 1. The drive flange 123 is shown with the brake disk 122 bolted to it and the flange 121 connected to the universal joint 120. The brake disk 122 has a relatively deep bell 122a so that the disk flange 122b is considerably outboard of the drive flange 123. The cooling duct 126 extends right in and opens into the brake disk housing 124 close to the periphery of the drive flange 123, inboard of the disk flange 122b and about the same distance from the disk axis as the inner edge of the disk flange 122b. The cooling duct therefore supplies air directly to the inner end of the cooling channels 122c through the disk flange 122b.

Claims

-5CLAIMS

1. A vehicle having a transmission including a gear box, inboard brakes which are in a fixed position relative to the gear box, cooling ducts for supplying cooling air to the brakes and air driving means, driven from the transmission, for driving air through the ducts towards the brakes.

2. A vehicle according to claim 1 wherein the air driving means forms part of a clutch assembly of the transmission.

3. A vehicle according to claim 2 wherein the air driving means comprises a fan operated by rotation of a flywheel.

I

4. A vehicle according to any foregoing claim including bypass duct for allowing air flowing to the brakes to bypass the air driving means.

5. A vehicle having a power train, a brake, ducting for supplying cooling air to the brake including an air driving duct having air driving means in it and a bypass duct arranged to bypass the air driving means, the air driving means being driven from the power train, and valve means arranged to open the air driving duct and close the bypass duct, or open the bypass duct and close the air driving duct.

6. A vehicle according to claim 5 wherein the air driving means includes a rotating member in a space and the ducting is arranged, when the air driving duct is closed, to form a venturi pump so that passage of air through the bypass duct reduces the pressure in the space, thereby reducing the resistance to rotation of the rotating member.

7. A vehicle according to any one of claims 4 to 6 wherein the bypass duct is arranged to be opened when the vehicle is travelling above a predetermined speed.

8. A vehicle according to claim 4 further comprising valve means for ope ning the bypass duct.

9. A vehicle according to any one of claims 5 to 8 wherein the valve means is arranged to be operated by the flow of air to open the bypass duct.

10. A vehicle according to any one of claims 5 to 8 further comprising control meaps and sensing means, the control means being arranged to open the bypass duct in response to signals from the sensing means.

11. A vehicle substantially as hereinbefore described with reference to the accompanying drawings.