AU709975B2 - Wheel alignment shock absorber - Google Patents

Description

(12) PATENT (11) Application No. AU 199716590 B2 (19) AUSTRALIAN PATENT OFFICE (10) Patent No. 709975 (54) Title Wheel alignment shock absorber (51) 6 International Patent Classification(s) B62D 007/22 F16F 007/09 B62D 007/20 (21) Application No: 199716590 (22) Application Date: 1997.03.27 Priority Data (31) Number (32) Date (33) Country PN9618 1996.05.01 AU (43) Publication Date: 1997.11.27 (43) Publication Journal Date 1997.11.27 (44) Accepted Journal Date 1999.09.09 (71) Applicant(s) Richard Gordon (72) Inventor(s) Richard Gordon (74) Agent/Attorney Richard Gordon,PO Box 120,Burswood WA 6100,Australia (56) Related Art US 5489113 DE 4216543 DE 4104445

AUSTRALIA

Patents Act 1990 R e gu lat ion 3.!2 Original Complete Specification Standard Patent Invention Title The following statement is a full description of this invention, including the best method of performing known to me:- ~Tr-T-

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-2- WHEEL ALIGNMENT SHOCK ABSORBER The present invention relates to a steerable wheel assembly and, more particularly, to a steerable wheel assembly which incorporates a shock absorber device to assist in maintaining the alignment of the steerable wheel(s).

The present invention also relates to a wheel alignment shock absorber device which is adapted to be incorporated in a steerable wheel assembly.

The invention has particular application to mobile land vehicles including automobiles, trucks and other vehicles with steerable ground-engaging wheels and the invention will hereinafter be described with reference to this exemplary application. It will be appreciated, however, that the present invention is not limited to this application but may be incorporated in any number of different situations involving steerable wheels.

Typically, automobiles, trucks and other wheeled vehicles include a pair of wheels, usually at a front end of the vehicle, which are rigidly mounted in a steering assembly to control the direction of the vehicle. Proper alignment of the two wheels is important for maintaining optimum steering control, ride comfort and tyre wear. Incorrect alignment of the steerable road wheels of land vehicles is known to have a significant adverse effect on the wear life of the S 20 tyres on those wheels. For example, research conducted within the Australian mining industry shows that tyre wear-life on correctly aligned steerable road wheels is approximately twice that of poorly aligned wheels.

°A major cause of incorrect wheel alignment in the steerable road wheels of vehicles are the lateral forces and impacts that the road wheels experience upon contact with objects such as curbing or windrows on or near the roadway while the vehicle is moving. When these lateral forces are imparted or applied to the wheels, the rigid linkages of the steering assembly in which the steerable wheels are incorporated can undergo a permanent deformation thereby altering the proper alignment of the steerable wheels.

It is therefore an aim of the present invention to provide a steerable wheel assembly which is able to sustain lateral impact and shock forces at the KW C. WINWORD\KATE\VARICUS\PWG\SPE:. 16590 Dn(C c w v, oo -3wheels without causing permanent deformation of the steering linkages and without creating a permanent misalignment of the steerable wheels.

According to one aspect of the present invention there is provided a steerable wheel assembly including at least one wheel rotatably mounted on an axle. The axle is mounted on a frame and is operatively interconnected with a steering control device adapted to pivot the axle relative to the frame about a pivot axis substantially perpendicular to the axle to actively steer the wheel in different directions. The assembly further includes a shock absorber device connected with the axle in such a way that lateral shock forces applied to the wheel are transmitted to and resiliently absorbed by the shock absorber device.

In at least one embodiment of the invention the shock absorber device is connected with the wheel axle laterally offset from the axle. Preferably the shock absorber device is connected with the axle in a plane which is substantially perpendicular to the pivot axis.

15 In a particularly preferred embodiment, the steerable wheel assembly S:includes a pair of wheels, each wheel mounted on an axle on the frame and operatively connected with the steering control device. The steering control :.:device is adapted to pivot each axle relative to the frame about a respective pivot axis to simultaneously steer both wheels in a chosen direction. The shock absorber device is connected with the wheels in such a way that lateral shocks 0 applied to one of the wheels are not substantially transmitted to the other of the wheels, thereby not affecting the chosen direction of the other wheel. In such an embodiment the shock absorber device may be incorporated in steering linkages operatively interconnecting the steering control device with the axle O such that lateral shocks applied to the wheel and resiliently absorbed by the shock absorber device are substantially not transmitted to the steering control device.

Typically the steerable wheel assembly will, as discussed above, include a pair of wheels with each wheel mounted on its own axle. In such an assembly the shock absorber device is preferably operatively connected with both of the pivotally mounted axles. Furthermore, the shock absorber device is preferably--double-acting to thereby provide both resilient compression and ~resilient extension in response to both compressive and tensile lateral shock C:\WINWORD\VIOLET\PHIL\SPECI\16590A.DOC 3a a a forces, respectively.

According to another aspect of the present invention there is provided a wheel alignment shock absorber which is adapted to be incorporated in the steering linkages of a steerable wheel assembly as described above to resiliently absorb lateral shock forces applied to the wheel(s). The shock absorber includes a rod slidably received within a housing sleeve with the rod having a piston member in operative engagement with a resiliently deformable /*k C:\WINWORD\VlOLET\PHIL\SPECI\1659A.DOC -4shock absorbing member on either side thereof within the housing. The shock absorber is thereby able to provide both resilient compression and resilient extension in response to compressive and tensile lateral shock forces, respectively.

In a preferred embodiment of this invention the resiliently deformable shock absorbing member includes a plurality of elastomeric biscuits or blocks which are desirably pre-compressed against the piston member to define a threshold of deforming force below which no deformation of the wheel alignment shock absorber will occur.

The present invention is thus able to provide a compressible selfcentring device incorporated in the steering linkages, such as track rods or tie rods, of a mobile land vehicle having steerable road wheels. In the event that the steerable road wheels impact with an object on or adjacent to the roadway, e the invention will allow the wheel assembly to momentarily and resiliently deform rather than experiencing any permanent deformation. This therefore prevents misalignment of the steerable wheel(s) developing as a result of permanent deformation of the steering linkages. That is, the compressibility and extendability provided by the shock absorber device incorporated in the steering tie rods or track rods means that forces applied to the road wheels 20 cause no permanent deformation of the steering linkages, but rather only momentary deformation of the shock absorber device. After the deforming force is removed the linkages are able to return to their normal positions.

*o*Accordingly, the invention can provide a pre-centred shock absorber device located within or contiguous with the steering track rods or tie rods of a vehicle. The wheel assembly of the invention allows the track rods or tie rods to shorten or lengthen momentarily in the event of a lateral force being applied to one or more of the steerable road wheels. This ability to resiliently absorb such forces enables the wheel alignment to remain undisturbed. Furthermore, an automatic self-centring function is provided by the invention so that after the lateral force is removed the track rods or tie rods return to their normal position.

The invention has the further advantage that shock forces applied/imparted at one of a pair of steerable wheels are effectively isolated from the other wheel.

KW C:\WINWORD\KATEVARIOCUPWG\SPECI\Si5 q DO( That is, only the wheel against which the shock force acts directly is substantially turned from the steered course. The other wheel, substantially isolated through the shock absorber device, is able to remain substantially oncourse. Furthermore, the steering assembly of the invention may be designed to limit the deflection of a wheel to a predetermined maximum allowable level.

The above and further features of the present invention will be more fully appreciated from the following detailed description of a preferred embodiment of the present invention with reference to the accompanying drawings in which: Fig. 1 is a schematic plan view showing a wheel assembly according to an embodiment of the present invention; Fig. 2 is a schematic partially sectioned side view of the shock absorber device incorporated in the steerable wheel assembly of Fig. 1.

Referring to Fig. 1 of the drawings, this embodiment of the invention provides a steerable wheel assembly 1 for a land vehicle such as an automobile or truck. The assembly 1 includes a pair of road wheels 2, each of which is rotatably mounted on an axle 3. The axles 3 are pivotably mounted to a frame, such as the chassis of the vehicle, and are adapted to pivot relative to the frame about a pivot axis 4 which extends substantially perpendicular to the axles 3. The axles 3 (in this case, stub-axles) extend substantially horizontally S 20 and the pivot axes 4 extends substantially vertically. Pivotable movement of each axle 3 about its respective pivot axis 4 turns or steers the wheels 2 to a °•odifferent direction.

*o*The wheel assembly 1 further includes a shock absorber device mounted between a pair of steering linkages 6 to which the wheel axles 3 are connected. The shock absorber device 5 lies in a substantially horizontal plane and is offset from the axles 3 by a distance X.

The steerable wheel assembly 1 of the invention provides a means for resiliently absorbing impact forces which are applied laterally to the wheels in the direction of the arrows A, B, C and D. The shock absorber device 5 is double-acting and is therefore able to resiliently compress or extend in response to either compressive or tensile lateral shock forces, respectively.

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CC..i -6- Referring to Fig. 2 of the drawings, the shock absorber device 5 includes a rod 7 slidably received within a sleeve type housing 8 having a generally cylindrical configuration. The rod 7 includes a piston 9 within the housing in operative engagement with a resiliently deformable shock absorbing member 10 on either side thereof. In the particular embodiment shown in Fig. 2, the shock absorbing members 10 on either side of the piston 9 include a plurality of elastomeric biscuits or discs 11. In an alternative form, however the resilient members 10 may simply comprise a single solid annular block of elastomeric material.

Each of the resilient members 10 is in contact at one end thereof with the piston 9. The other end of each of the resilient members abuts a seat 13.

One of the seats 13 is integral with the housing 8. The other of the two seats is threadably connected to the housing for pre-compressing the elastomeric biscuits 11. Each of the seats 13 includes a low-friction bushing 14 through which the rod 7 is slidably received for guiding and supporting the rod in the shock absorber device. Furthermore, the shock absorber device 5 may be incorporated within steering linkage members such as track or tie rods 15. A telescopic boot 16 may be provided over an end of the piston rod 7 at the low friction bushing 14 to seal the shock absorber device against the ingress of 20 water or other foreign matter.

When a lateral shock force impacts upon the wheels 2 the force is transferred through the linkage members 6 and 15 to the shock absorber device 5 where it causes momentary resilient deformation of the elastomeric biscuits 11. As mentioned earlier, the elastomeric biscuits can be pre-loaded under compression so that a certain threshold of force is required to produce deformation of the shock absorbing members. This ensures that the track/tie rod lengths remain unchanged other than when acted upon by the transient shock forces, and also ensures that the pre-stressed shock absorber device maintains the wheels of the assembly 1 in a centred and aligned orientation.

Naturally, the extent of pre-loading will be determined separately for each type of vehicle based upon the typical forces expected to act on the road wheels and other steering and suspension components.

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Claims (12)

1. A steerable wheel assembly including a pair of wheels, each wheel rotatably mounted on a respective axle and said axles being mounted on a frame and operatively interconnected with a steering control device adapted to pivot each axle relative to the frame about a respective pivot axis substantially perpendicular to each axle to actively steer the wheels in a chosen direction, the assembly further including a shock absorber device connected with said axles in such a way that a lateral shock force applied to one of said wheels is transmitted to and resiliently absorbed by the shock absorber device, and such that said shock force is substantially not transmitted to the other of said wheels so as to thereby not substantially affect the chosen direction of said other wheel.

2. A steerable wheel assembly as claimed in claim 1 wherein the shock absorber device is inter-connected with the wheel axles offset from said axles.

3. A steerable wheel assembly as claimed in claim 1 or claim 2 wherein the shock absorber device is pivotally connected with the axles and extends in a 0plane substantially perpendicular to the pivot axes for the axles.

4. A steerable wheel assembly as claimed in any one of the preceding claims wherein the shock absorber device is incorporated in steering linkages operatively interconnecting the steering control device with the axles such that lateral shocks applied to the wheels and resiliently absorbed by the shock absorber device are not substantially transmitted to the steering control device. A steerable wheel assembly as claimed in any one of the preceding claims wherein the wheels are ground-engaging wheels of a vehicle having substantially horizontal axles adapted to pivot relative to the vehicle frame about substantially vertical pivot axes.

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6. A steerable wheel assembly as claimed in any one of the preceding -claims wherein the shock absorber device is double-acting providing both resilient compression and resilient extension in response to compressive and tensile lateral shock forces, respectively.

7. A steerable wheel assembly as claimed in claim 6 wherein the shock absorber device includes a rod slidably received within a sleeve-type housing, said rod including a piston member in operative engagement with a resiliently deformable shock absorbing member on either side thereof within the housing.

8. A steerable wheel assembly as claimed in claim 7 wherein each of said resilient shock absorbing members includes a plurality of discrete elastomeric disc elements. 15

9. A steerable wheel assembly as claimed in claim 8 wherein the resilient shock-absorbing members are pre-stressed to impose a threshold level of force below which no deformation of the shock absorber device will occur.

10. A steerable wheel assembly substantially as herein described with 20 reference to the accompanying drawings. **9

11. A vehicle incorporating a steerable wheel assembly as claimed in any one of the preceding claims. a

12. A wheel alignment shock absorber device adapted to be incorporated in the steering linkages of a steerable wheel assembly as claimed in claim 4 to resiliently absorb lateral shock forces applied to said wheel, the shock absorber including a rod slidably received within a sleeve-type housing, the rod having a piston member in operative engagement with a resiliently deformable shock absorbing member on either side thereof within the housing, whereby the shock absorber is double-acting providing both resilient compression and resilient MR C:i'WINWORDMARY\NODELETE\ 6590.DOC