GB2345105A - A removable wheel and disc brake assembly - Google Patents

Abstract

A removable wheel and disc brake assembly comprises a wheel rim 1, a central carrier 17 located within the rim for mounting the assembly on hub 3 about which the rim and carrier rotate, a brake disc 6 secured to carrier flange 17, and a disc brake calliper 8 located within said rim. When the disc brake is fully applied, the whole assembly can be removed from the hub by virtue of interacting valves (31-36 and 41-46 Fig.6) on the hub and calliper, which close, when disengaged on removal of the assembly, and open, when engaged on mounting the assembly on the hub. Further embodiments of the wheel assembly (Figs.2 and 3) are also disclosed.

Description

Title : WHEEL ASSEMBLY FOR A MOTOR VEHICLE The present invention relates to a wheel assembly, particularly, but not solely for a racing car, and to a method and apparatus for using wheel assemblies.

According to one form of the invention there is provided a wheel assembly comprising a wheel rim and a brake disc connected thereto whereby when the wheel rim is attached to or removed from a vehicle the brake disc is simultaneously attached or removed. The wheel assembly may include one or more bearings for mounting the assembly on a driven or non-driven vehicle hub.

In another form of the invention there is provided a vehicle having a hub for a wheel and a brake fluid valve adapted to be opened and closed by the fitting to the vehicle or removal therefrom, respectively, of a wheel assembly.

In a further form of the invention there is provided a vehicle as hereinbefore defined in combination with a wheel assembly as hereinbefore defined. The wheel assembly may include brake pads and a brake calliper clamped onto the brake disc prior to the fitting of the wheel assembly to the vehicle.

In a known vehicle wheel arrangement the brake disc and the calliper are attached to the hub with the wheel bearing between them to allow the disc to turn freely when the brakes are not applied. The wheel rim and tyre are then bolted onto the outer, free moving part of the hub and are thus connected to the brake disc. The aim of the present invention is to allow the disc, the calliper and the bearings to be changed when the tyre/rim is changed. This is achieved in one form by redesigning the wheel rim and the vehicle hub so that the disc and the bearings are mounted not on the hub but on the rim. This allows them to be removed when the rim/tyre is changed/removed. This presents the problem of how to change the break calliper during this process. This is because whether in use or not the break calliper has to be locked to the hub. The preferred system proposed herein still requires that this is the case and is achieved by separating the calliper from the hub then linking the two again using a mounting system with valves and an electro-magnetic lock to hold the two together when in use.

Constructional embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 shows a cross-section of a non-driven wheel assembly according to the present invention; Figure 2 shows a cross-section of a driven wheel assembly according to the present invention; Figure 3 shows a cross-section of a non-driven or driven wheel assembly according to a further embodiment of the present invention; Figures 4A and 4B show rear and front views of a vehicle hub and Figures 4C and 4D show views from one side and the other side of the vehicle hub; Figures 5A and 5B show side and front views of a brake calliper; Figure 6 shows a cross-sectional view of a valve pair with the valves shown open on the left-hand side and closed on the right-hand side.

Figures 7A and 7B show front and side views of a preparation jig; Figure 8 shows a schematic perspective view of a racing car; Figures 9A and 9B show perspective exploded and assembled views of a nondriven wheel assembly; and Figures 10A and 10B show perspective exploded and assembled views of a driven wheel assembly.

As shown in Figure 1 a non-driven wheel assembly includes a wheel rim 1 having spokes or ribs 2 attached to the rim 1 by means of screws 12. A brake disc 6 is mounted on an annular flange 16 of a tubular brake disc carrier 17 by means of an O-ring or washer and screws 7. The flange 16 is integral with or firmly connected to the carrier 17 which is integral with or firmly connected to the spokes 2. On one end of the carrier 17 adjacent the spokes 2 there is mounted a bearing 13 by means of O-ring or washer and screws 14 and on the other end there is mounted a bearing 4 by means of O-ring or washer and screws 5. The inside bearing is present to keep the wheel tracking true as the outer main bearing is mounted on the extreme outer end of the vehicle hub.

A central hub 3, attached to a car, carries a hub mount 11 engaged by a calliper mount 10 having a calliper assembly 8 including callipers 9 either side of brake disc 6. The carrier 17 is rotatably mounted on the hub 3 by the bearings 4 and 13 and the wheel rim 1, spokes 2 and carrier 17 are held in place by wheel nut 15 which tightens against wheel-bearing 13 which protrudes through the spokes 2.

In a driven wheel assembly as shown in Figure 2 wheel rim 1, spokes 2 and carrier 17 are mounted on a driven axle 18 and non-rotatable fixed relative thereto by means of the wheel nut 15. The flange 16 is rotatably mounted on hub 3 by the bearing 4.

Figure 3 shows a wheel assembly for a driven or non-driven wheel. A wheel bearing 19 is connected to hub 3 by means of O-ring or washer and screws 20.

Internally the bearing 19 carries one end of an axle 21 fixed to the bearing 19 by means of a bush 22, bolt 23 extending through bush 22, and a nut 24. The wheel nut 15 locks the rim 1 and carrier 17 onto the axle 21 which can be freely rotatable or can be driven to allow power to be transferred to the wheel. If the wheel is to be driven a link is attached to the bush 22 to transfer power from the engine to bush 22.

As shown in Figures 4A to 4D the hub mount 11 on the hub 3 has a mount guide 25 and one end of which is a hub valve assembly 26. The calliper mount 10, as shown in Figures SA and SB, has a calliper mount guide 27 at one end of which is a calliper valve mount 28. The mount 28 and the assembly 26 each carry one half of a co-operating valve pair as described in Figure 6.

The hub valve comprises an engaging head 31 on a mounting spindle 32. An internal barrel 33 is mounted within mounting barrel 35 screwed into external barrel 34. A spring 36 works between barrels 33 and 35 to keep head 31 closed against external barrel 34 when the spring is extended. The calliper valve comprises an engaging head 41 mounted on engaging spindle 42 which is secured to a mounting barrel 43 at its end remote from head 41. Barrel 43 is screwed in to external barrel 44 containing an internal barrel 45. A spring 46 acts between barrels 43 and 45 to keep head 41 closed against internal barrel 45 when the spring is extended.

The valve pair, one half mounted in the calliper and one half mounted in the hub need, when closed, to be capable of maintaining the pressure of the brake fluid they are enclosing within the calliper system and the brake hoses within the car.

When the valves open and close there should be no leakage of air into the system that would cause the brakes to become"spongy". The valves should have only the absolute minimum of volume change within their chambers (the space within the valve) so that the pressure of the fluid within the systems remains constant as the valves are closed and open.

When the valves are closed the closure is made against the heads 31 and 41.

When the valves engage each other the spindle 42 in the calliper valve, which is fixed in position, forces spindle 32 in the hub valve backwards into the interior of hub valve thereby opening it. The mount 33 of this spindle 32 and head 31 works against a spring 36 but is also designed to keep the spring space dry and out of the flow of brake fluid.

As the spindle heads engage and open the hub valve, the outer barrel of the hub valve 34 engages the closure of the calliper valve 45. This part slides backwards to open the calliper valve. The closure 45 works against a spring 46 which keeps the valve closed when not engaged and is designed as with the hub valve to keep the spring space separate from the brake fluid.

Both valve opening processes occur simultaneously preventing any air from entering the system. Both valves are formed of two barrels, a spring and a sliding mount that works against the spring. They are designed to be easily constructed by placing the sliding parts 45 and 33 within the outer barrels 44 and 34, the springs are then introduced to the sliding parts and the bottom barrels 43 and 35 are then screwed into the back of the outer barrels 44 and 34. The bottom barrels 43 and 35 can then be screwed into the calliper and the hub mount respectively.

Finally as the valves engage an electro-magnetic plate 37 attached to the outer barrel 34 of the hub valve locks the two valves together. The plate 37 not only keeps the valves engaged but also keeps the calliper on the right line and prevents its moving laterally.

In Figure 7 a wheel 50 is shown on a preparation jig which has a rolling road or rollers 52 on a base or pedestal 53 having a safety cover 54 with a window. The pedestal contains drive means for the rollers 52 and stabilising ballast in the form of, for example, a block of concrete. A hub mount is bolted onto the jig and is interchangeable so that an un-driven wheel may be mounted on the jig; the hub mount shown being for a driven wheel. An axle passes through the back of the jig mount and the hub so that a wheel can be positioned on the jig properly in the same manner as it would be on a car. A wheel can be balanced on the rolling road, brake disc and pads pre-heated to make them more effective when they are added to the car and brake pads and calliper locked onto the brake disc so that the wheel assembly is ready for application to a car. The wheel assembly is introduced laterally as in the case of known wheels. The wheel assembly is marked so that when the mark is at an identifiable position, e. g. 12 o'clock, the calliper valve mount 28 just engages the open end of the mount guide 25 remote from the hub valve assembly 26. The wheel assembly is turned clockwise and calliper mount guide 27 slides in the mount guide 25 until calliper valve mount 28 reaches hub valve assembly 26 and stops at the closed end of the mount guide 25. The wheel assembly is then pushed laterally towards the car which causes compression of springs 36 and 46 and opening of hub and calliper valves. The dimensions of calliper valve mount 28, mount guide 27 and mount guide 25 are such that when mount 28 and guide 27 are engaged in guide 25 but mount 28 has not reached hub valve assembly 26, guide 27 will be held within the guide 25 but will not be completely located until mount 28 reaches assembly 26.

The mount 28 and guide 27 are designed to prevent the calliper from moving. The engagement of the calliper mount 27 in the mount guide 25 is designed to prevent the possibility of the calliper pitching, yawing or rolling. Lateral movement away from the centre line of the car would potentially cause the valves to disengage and the inboard brake pad to rub against the disc and would be detrimental to the braking capacity of the car. Such lateral movement is prevented by the electromagnetic lock 37.

In the racing car shown in Figure 8 a master brake cylinder 60 with enlarged fluid reservoir is acted on by brake pedal 61. A steering wheel 62 has a park brake switch or button and an on-board computer 63 with known software for optimum vehicle operation is provided with additional software to control wheel assemblies in accordance with the present invention. A cable 65 connects the park brake switch to the computer 63 to allow the switch to operate and a cable 66 connects the master cylinder 60 to the computer 63 so that the computer can monitor the brake fluid pressure and adjust it through an adjustment unit 68 which provides information to the computer on brake fluid pressure and adjusts the pressure in response to instructions of the computer in accordance with the additional software. Cables 67 connect the computer 63 to the hub valves so that the electro magnetic locks can be operated and can also be used for data collection. Brake hoses 64 link the master cylinder 60 to the hub valves and brake callipers.

Wheel changing procedure is as follows :- 1. When the car comes to a halt the driver engages the parking brake button on the steering wheel. This sets the brake pressure to its highest level locking the calliper on to the brake discs. At the same time the computer turns off the electro-magnetic lock. The requirement that the brakes are on during a tyre change is not unusual as drivers are at present required to apply the brakes so that the wheel nut can be removed.

2. The wheel nut is removed and the rim/tyre (including brake disc, calliper and optionally the wheel bearings) are then removed with a lateral movement away from the car. This movement separates the now unlocked valves closing them automatically so that pressure is maintained in the car and the calliper.

3. The new wheel assembly is introduced first laterally then in a clockwise direction to engage the mount, then finally laterally to engage the brake valves. This final movement opens the valves but as pressure is high in the brake fluid in the car the brakes remain locked on.

4. The wheel nuts are replaced and tightened.

5. When instructed the driver turns the parking brake off. This releases the brakes but at the same time instructs the computer to engage the electro magnetic lock to prevent outward lateral movement in of the brake callipers.

6. The computer monitors the brake fluid pressure and adjusts it to minimum levels as necessary.

The minimum pressure in the brake fluid system is taken to be equal to A and is the state of the system when no pressure is applied on the brake pedal. The peak pressure is taken to be equal to B and is the state of the system either when the brake pedal is fully depressed or the parking brake is applied. Then for each percentage amount C that the brake pedal is depressed the pressure in the system may be taken to be X = A+ [ (B-A)/100] xC.

The onboard computer should be able to monitor the pressure within the brake fluid system and the level of the depression of the brake pedal and therefore measure the discrepancy between what the brake fluid pressure is and what it should be. The pressure in the system should then be adjusted by means of a mechanical piston attached to the master cylinder. While such a system would provide more constant brake pressures and therefore more constant brake performance throughout a race, it will also allow the computer to adjust the pressure in the brake fluid system each time new callipers are applied to (and old ones are removed from) the car.

To further expedite the mounting of a wheel assembly onto a racing car the hub 3, carrier 17, axle 18 and/or axle 21 may be tapered or frusto-conical and the respective tapers adapted to each so as to be complimentary.

Claims (14)

1. CLAIMS 1. A wheel assembly comprising a wheel rim (1), and a central carrier (17) located within the rim for receiving a mounting assembly axle about which the rim and carrier are to rotate, characterised in that a disc brake unit (6,8,9) is located within said wheel rim and is axially movable as a unit, whereby when the wheel rim is mounted on or removed from the axle, the brake unit is simultaneously mounted or removed.
2. 2. An assembly as claimed in claim 1, characterised in that the brake disc (6) of said brake assembly is removably carried on an annular flange (16) mounted to rotate with the central carrier (17).
3. 3. An assembly as claimed in claim 2, characterised in that the central carrier is provided at or near each end with a bearing (5,13) for rotatably supporting the assembly on said axle, said annular flange being axially located between said bearings.
4. 4. An assembly as claimed in claim 3, characterised in that the bearings are mounted on said carrier (17) so as to be removable therewith.
5. 5. An assembly as claimed in claim 2, characterised in that the annular flange is provided with a bearing (4) which serves to support said assembly rotatably on said axle.
6. 6. An assembly as claimed in claim 5, characterised in that said bearing is mounted on said annular flange so as to be removable therewith.
7. 7. A wheel assembly as claimed in claim 2, in combination with a wheel mounting assembly, characterised in that the wheel mounting assembly comprises an axle (21) rotatably mounted on a driving hub (3) by means of a bearing (14), said axle having a distal end portion for closely engaging a central bore of the carrier (17) and a shoulder which engages the flange (16) when the wheel assembly is secured to the wheel mounting assembly.
8. 8. A wheel assembly as claimed in any one of claims 2 to 6, or the combination of claim 7, characterised in that the brake unit comprises a calliper which engages on each side of the brake disc (6) said calliper having a mount for coupling engagement with a hub mount (11) carried by the mounting assembly, whereby movement of the calliper is prevented during rotation of the wheel rim.
9. 9. A wheel assembly as claimed in claim 8, characterised in that the calliper mount (10) engages an aperture formed in the hub mount (11).
10. 10. A wheel assembly as claimed in claim 8 or 9, characterised in that a brake fluid valve is provided with coupling portions (26,28) mounted respectively on the calliper mount and hub mount, said valve being adapted to enable fluid coupling between said coupling portions when said calliper mount is in engagement with the aperture in said hub mount and to close off the fluid coupling at the hub mount at the moment the wheel assembly is removed from the wheel mounting.
11. 11. A wheel assembly as claimed in claim 10, characterised in that each of the coupling portions comprises a spring-loaded slide valve (33,45) which close off the coupling portions to prevent egress of brake fluid when the coupling portions are separated from each other, the fluid within the calliper brake thereby holding the brake on.
12. 12. A combination as claimed in any of claims 8 to 11, wherein the wheel assembly and the wheel mounting assembly are each provided with alignment means to ensure speedy inter-engagement of the calliper mount with the hub mount.
13. 13. A combination as claimed in claim 12, wherein the alignment means are visual marks or inter-engageable structural elements.
14. 14. A wheel assembly or combination as claimed in any one of claims 1 to 12 substantially as described with reference to the accompanying drawings.