GB2467564A

GB2467564A - Vehicle chassis with a further driven member

Info

Publication number: GB2467564A
Application number: GB0901916A
Authority: GB
Inventors: David Andrew Vines
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-02-06
Filing date: 2009-02-06
Publication date: 2010-08-11
Anticipated expiration: 2029-02-06
Also published as: WO2010089583A1; GB0901916D0; GB2467564B

Abstract

Vehicle chassis apparatus 10 comprises a support element 12, two rotatable wheels 16 held in spaced relationship by the support element 12, drive means 14 supported by the support element 12 for driving the wheels 16, and a rotatable ground-engagable driven member 18 interposed between the wheels 16. The driven member 18 has a diameter which is less than the wheels 16 and is drivable by the drive means 14 for moving the apparatus 10 when the wheels 16 are spaced from the ground.

Description

Vehicle Chassis Apparatus The present invention relates to vehicle chassis apparatus, particularly but not necessarily exclusively for an All Terrain Vehicle or ATV.

Off-road vehicles despite having significantly greater ground clearance than on-road vehicles can still often bottom-out'. This often happens when ruts in a track or path are so deep that the chassis grounds on the earth between the ruts, and the driven wheels in the ruts lose traction. The vehicle then has to be rocked, pushed or pulled until the driven wheels regain enough traction to move the vehicle onwards.

The above situation applies in particular to two wheel drive off-road vehicles, such as AT'V racing-quad bikes. Tn this case, only the rear two wheels are driven in order to keep the weight of the vehicle down. However, this leads to a greater problem for the rider in getting the machine moving again following grounding.

The present invention seeks to provide a solution to this problem.

According to a first aspect of the invention, there is provided vehicle chassis apparatus comprising a support element, two rotatable wheels held in spaced relationship by the support element, drive means supported by the support element for driving the wheels, and a rotatable ground-engagable driven member interposed between the wheels, the driven member having a diameter which is less than the wheels and being drivable by the drive means for moving the apparatus when the wheels are spaced from the ground.

Preferable and/or optional aspects of the invention are set forth in claims 2 to 20, inclusive.

According to a second aspect of the invention, there is provided an ATV having vehicle chassis apparatus in accordance with the first aspect of the invention.

Preferably, the vehicle is only rear wheel drive.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a diagrammatic end view of a first embodiment of vehicle chassis apparatus from a rear axle, when in use, and in accordance with the first aspect of the invention; Figure 2 shows an exploded view of the vehicle chassis apparatus; and Figures 3 to 6 shows diagrammatic end views of second to fifth embodiments of vehicle chassis apparatus, again from the rear axle, and in accordance with the first aspect of the invention.

Referring firstly to Figures 1 and 2 of the drawings, there is shown vehicle chassis apparatus 10 for a race-type All Terrain Vehicle or ATV which comprises a rigid, typically metal, support element 12, being in this case a rear swing arm, drive means 14 supported by the support element 12, two rear wheels 16 which are supported by the support element 12 for rotation by the drive means 14, and a driven member 18 interposed between the wheels 16.

The swing arm 12 includes two, preferably parallel, spaced arm elements 20 and a stem which pivotably connects the arm elements 20 to the rest of the chassis. The swing arm 12 is thus generally Y-shaped in plan.

Axle bearings 22 are provided adjacent to distal ends of the arm elements 20 for supporting a, preferably one-piece, live axle 24. A brake disc 26 is splined to the axle 24 adjacent to an inboard face of one arm element 20, and a brake calliper and calliper housing is typically mounted on the arm element 20.

As well as the axle 24, the drive means 14 includes a sprocket hub 28 which is splined to the axle 24 adjacent to an inboard face of the other arm element 20, on the opposite side to the brake disc 26. A chain sprocket 30 is mounted to the sprocket hub 28 in fixed angular relationship. A drive chain 32, typically being drivable through a transmission by an internal combustion engine, is entrained on the chain sprocket 30, which thus rotates the chain sprocket 30, sprocket hub 28 and finally the axle 24.

The driven member 18 is intermediate the brake disc 26 and sprocket hub 28, and includes a driven hub 34 which is provided on the axle 24. In this embodiment, the driven hub 34 is angularly fixed to the sprocket hub 28. However, additionally or alternatively, the driven hub 34 can be splined to the axle 24 or keyed.

The driven member 18 also includes a driven wheel 40 which is angularly fixed to the driven hub 34, typically using bolts, thereby allowing simple removal. The driven wheel 40 includes a rigid rim 36 and an inflatable tyre 38 provided on the rim 36. The driven wheel 40 is substantially midway between the brake disc 26 and the sprocket hub 28. In total, the diameter of the driven wheel 40 is less than the diameter of the outboard main wheels 16, and preferably a sidewall to sidewall width is also less. However, the diameter of the driven wheel 40, and preferably the diameter of the rim 36 itself, is greater than the other elements on the axle 24, such as the brake disc 26, driven hub 34 and chain sprocket 30.

Although the driven member 18 is or includes a driven wheel 40, it may be or include a paddle or other kind of rotatable ground-engagable member for moving the vehicle forward on grounding.

The swing arm 12 may include only one arm element 20 with the main wheels 16 being to either side thereof In this case, the driven hub 34 and driven wheel 40 are provided at one side of the arm element 20. To enable the driven member 18 to be easily removed, a keyed clamping hub can be utilised as the driven hub 34. This allows straightforward retro-fit to existing swing arm arrangements. Tt also enables simplified removal of the driven member 18, for example, for cleaning and maintenance, without requiring the entire rear axle 24 to be stripped down.

Preferably, the driven member 18 is interposed between the brake disc 26 and the chain sprocket 30. However, with referral to Figures 3 to 6, second to fifth embodiments will now be briefly described. In these embodiments, like references refer to like parts, and

further detailed description is omitted.

The second embodiment of vehicle chassis apparatus 10 includes a swing arm 12 with a single arm element 20 midway between the main wheels 16. The brake disc 26 and the chain sprocket 30 are provided outboard of the swing arm 12, on opposite sides, and a rotatable ground-engagable driven member 18 is provided intermediate the brake disc 26 and wheel 16 on one side and the chain sprocket 30 and wheel 16 on the other side.

In this case, the width of the driven members 18 is less than the width of the wheels 16.

The driven members 18 can be conveniently angularly fixed to the axle 24 by splining and/or keying, such as by using the keyed clamping hub mentioned above.

Referring to Figure 4, the third embodiment of vehicle chassis apparatus 10 again includes a swing arm 12 with a single arm element 20 midway between the main wheels 16. The brake disc 26 and the chain sprocket 30 are provided outboard of the swing arm 12, as in the second embodiment described above, and a rotatable ground-engagable driven member 18 is provided intermediate the brake disc 26 and wheel 16 on one side and the chain sprocket 30 and wheel 16 on the other side. In this case, however, the widths of the driven members 18 are greater than the widths of the wheels 16, so that the driven members 18 extend along the majority of the exposed longitudinal extent of the axle 24 from the wheels 16 towards the brake disc 26 and chain sprocket 30, respectively. The driven members 18 can again be conveniently angularly fixed to the axle 24 by splining and/or keying, such as by using the keyed clamping hub mentioned above.

Referring to Figure 5, the fourth embodiment of vehicle chassis apparatus 10 is shown.

In this case, the swing arm 12 may have a single arm element 20 or two arm elements as described above. Two driven members 18 are provided in spaced apart relationship and coaxial with the axle 24. Each driven member 18 is fastened to a respective one of the main wheels 16, so as to be angularly fixed relative thereto. The driven member 18 may also be connected to the axle 24, for example, by splining and/or keying. Widths of the driven members 18 are less than the widths of the main wheels 16, similar to the second embodiment, but the widths of the driven members 18 may be greater as in the third embodiment.

The fifth embodiment of vehicle chassis apparatus 10, shown in Figure 6, is similar to that of the fourth embodiment except that the driven members 18 are frusto-conical. The original swing arm 12, axle 24 and drive means 14 can be retained, and the driven members 18 can abut the main wheel rim or be spaced therefrom along the longitudinal extent of the normally exposed axle 24.

In the second to fifth embodiments, the driven member or driven members can be retro-fitted to the existing arrangement. It is preferable to utilise pairs of driven members for stability purposes. However, it may be feasible to utilise only one driven member.

Furthermore, the first embodiment may be provided with a swing arm having only one arm element. In this case, it may be preferable that the arm element is cranked so as to be offset, thereby allowing the driven member to be centralised relative to the pivot of the swing arm.

Although the support element is described as a swing arm, the support element may be any kind of suspension element for any kind of drivable, preferably motorised, vehicle.

Similarly, the drive means described above includes a chain sprocket for a drive chain and a single live axle. However, any kind of drive train can be utilised, including a shaft drive, and/or two axles, which may be independent, for example, being coupled via a differential, could be utilised.

Since the or each driven member is angularly fixed relative to the main wheels, the or each driven member rotates permanently with the wheels at the same rate of revolution.

However, it may be feasible to include a clutch, such as a sprag clutch, whereby the driven member can freewheel when it is out of engagement with the ground, but which engages the wheel automatically when the driven member contacts the ground.

The vehicle chassis apparatus described above, or parts thereof, such as the or each driven member, can be retro-fitted to an existing vehicle, and thus may be provided as a kit of parts.

It is thus possible to provide vehicle chassis apparatus which provides motive force to the vehicle when the outboard driven wheels are spaced from the ground. It is also possible to provide vehicle chassis apparatus in which the driven wheels include a further smaller rotatable ground-engagable driven member interposed therebetween which provides motive force to the vehicle on grounding. The driven member can be a wheel, paddle, belt, strap or chain, for example, and is preferably simply removable for cleaning and maintenance purposes. The driven member is also preferably retro-fittable to provide vehicle chassis apparatus on an existing off-road vehicle, such as an ATV.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

Claims 1. Vehicle chassis apparatus comprising a support element, two rotatable wheels held in spaced relationship by the support element, drive means supported by the support element for driving the wheels, and a rotatable ground-engagable driven member interposed between the wheels, the driven member having a diameter which is less than the wheels and being drivable by the drive means for moving the apparatus when the wheels are spaced from the ground.
2. Vehicle chassis apparatus as claimed in claim 1, wherein the driven member is coaxial with the wheels.
3. Vehicle chassis apparatus as claimed in claim 1 or claim 2, wherein the drive means includes at least one drive axle, the wheels bring provided at outboard ends thereof and the driven member being intermediate the outboard ends.
4. Vehicle chassis apparatus as claimed in claim 3, wherein the drive member is angularly fixed to said at least one drive axle.
5. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein the support element includes a swing arm, the driven member being provided at one side of the swing arm.
6. Vehicle chassis apparatus as claimed in claim 5, wherein the swing arm includes two spaced arm elements, the wheels being provided outboard of respective arm elements and the driven member being provided between the arm elements.
7. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein the driven member is driven permanently with the wheels.
8. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein the driven member is angularly fixed relative to the wheels.
9. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein two said driven members are provided in spaced relationship.
10. Vehicle chassis apparatus as claimed in claim 9, wherein each said driven member is directly connected to a respective wheel.
11. Vehicle chassis apparatus as claimed in claim 9 or claim 10, wherein each said driven member is frusto-conical.
12. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein the driven member is a secondary wheel.
13. Vehicle chassis apparatus as claimed in claim 12, wherein the secondary wheel has an unloaded sidewall to sidewall width which is less than those of the main said wheels.
14. Vehicle chassis apparatus as claimed in any one of claims 1 to 11, wherein the driven member is a paddle.
15. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein the driven member is interposed midway between the wheels.
16. Vehicle chassis apparatus as claimed in any one of claims 1 to 14, wherein the driven member is offset from a midpoint between the wheels.
17. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein the drive means includes a drive sprocket and brake disc which are interposed between the wheels.
18. Vehicle chassis apparatus as claimed in claim 17, wherein the driven member is intermediate the drive sprocket and brake disc.
19. Vehicle chassis apparatus as claimed in any one of the preceding claims, wherein the driven member has a diameter which is less than the wheels but greater than any other element on the rotational axes of the wheels.
20. Vehicle chassis apparatus as claimed in any one of the preceding claims, in the form of a kit of parts.
21. Vehicle chassis apparatus substantially as hereinbefore described with reference to the accompanying drawings.
22. An ATV having vehicle chassis apparatus as claimed in any one of the preceding claims.
23. An ATV as claimed in claim 22, wherein the vehicle is only rear wheel drive.