Land vehicles – Body elevation or tilt – Establishing riding or trim height
Reexamination Certificate
1999-09-23
2001-07-31
English, Peter C. (Department: 3619)
Land vehicles
Body elevation or tilt
Establishing riding or trim height
C280S086757, C280S093512, C280S124103, C280S771000
Reexamination Certificate
active
06267388
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a modified racing vehicle such as a racing car.
BACKGROUND OF THE INVENTION
In order to extend access to motor racing events and to reduce the costs thereof, there exists a need for a racing car having a size such that it can run on a track suitable for a conventional go-kart but which retains the appearance and characteristics of a conventional single seater formula car.
To produce a suitable vehicle for this purpose it is desirable that the following objectives are met to a broad extent:
1. The size of the vehicle is such that it can run on a track suitable for a go-kart i.e. the vehicle is small compared with a conventional single seater formula racing car;
2. The vehicle is inexpensive to build and requires little maintenance;
3. The vehicle has sufficient in-built strength to resist significant damage from average crashes encountered on a racing circuit; and
4. The vehicle can be easily handled by a novice driver yet is challenging and exciting for the experienced driver.
To meet these objectives a racing vehicle can be designed which has a space frame chassis similar to that of a conventional single seater formula car but which has restricted dimensions to enable it to be raced successfully on go-kart tracks such as those presently in use, in particular the larger outdoor go-kart tracks. The limited size of the chassis of the vehicle thus produced leads to a reduction in the space available within it for components and restricts further design modifications to the vehicle.
To produce a vehicle having a chassis of suitable restricted size, it is proposed in the present invention to design the vehicle without a differential on the rear axle and without a resilient suspension component on the rear and front axles.
The proposed design of the invention creates an inherent handling problem, in that the fixed rear axle without a differential resists turns and tends to proceed in a straight line thereby creating understeer or an inherent resistance to turning corners in the vehicle. The removal of the resilient suspension components and the increased weight in comparison to a go-kart increases the severity of the problem.
Steering systems are known such as the double wishbone type, generally comprising a hub carrier for rotatably supporting a front wheel, and upper and lower linkages for connecting upper and lower ends of the hub carrier to a vehicle body. According to such conventional wishbone arrangements, the kingpin axis about which the hub is carried and about which the wheel rotates, is theoretically fixed even during the steering operation. The camber characteristics of the vehicle are determined by the castor angle, i.e. the inclination of the kingpin axis to the longitudinal axis of the vehicle. The cornering performance during steering is primarily influenced by the cornering power of an outer front wheel, situated on an outer side with reference to a cornering centre. During steering the vehicle body rolls, which tends to increase the camber angle of the outer front wheel and hence the tyre inclination angle with reference to the ground surface in the positive camber direction, thereby lowering the cornering power of the outer front wheel. Vehicles incorporating such systems require full suspension systems if they are to operate effectively.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a racing vehicle having dimensions such that it can run on a track suitable for a conventional go-kart and having substantially the characteristics of a single seater formula car except that it has substantially no differential on its rear axle and no resilient suspension on its rear and front axles and it is provided with weight transfer means to reduce the weight on the road of a rear inner wheel of a turn by transferring weight from the rear inner wheel to the rear outer wheel as the vehicle goes through its turn. The means of weight transfer produces an effect similar to a differential and enables the rear wheels to turn “differentially” notwithstanding that they are on a fixed, rotatable axle. Suitably the weight transfer means is a steering geometry of the front wheels designed with angles such as to create a twisting motion in the chassis as the front wheels of the vehicle are turned, which is transmitted directly to the rear axle through the chassis thereby producing the weight transfer required. The geometry which is suitable depends upon the dimensions of the vehicle, in particular upon its wheelbase.
SUMMARY OF THE INVENTION
Accordingly, the invention provides a vehicle of the type comprising a space frame chassis supporting a pair of non-steerable wheels, a pair of steerable wheels, and having a steering system including a steering member carrying a stub axle, upper and lower suspension linkages pivotally connecting upper and lower ends ol said steering member to the vehicle chassis, the steering member is supported by said linkages for pivotal movement about a kingpin axis through said upper and lower ends, wherein the steering geometry is arranged such that, for the radially outer steerable wheel with reference to a turning centre, a castor angle of the kingpin axis increases and the kingpin axis is inclined into the turn as the steering member pivots and said outer steerable wheel is lifted upwards forcing the chassis down whereby a downward force is exerted through said chassis to a non-steerable wheel that is the radially outer wheel with reference to said turning centre. The angles producing the effect are the castor angle and, especially, the Kingpin inclination angle. The castor angle is increased for the outer steerable wheel. A Kingpin inclination angle arises by virtue of a special angle (stub angle) present at or near a middle portion of the strut or steering member supporting the stub axle for the front wheel. Conveniently the stub axle is located on a substantially upright, lower portion of the strut.
The steering member may comprise a strut having a pair of sections set at an angle to each other. The angle, the stub angle, is preferably within the range 148° to 164°, more preferably within the range 155° to 160°. In a preferred embodiment the stub angle is 159°.
There are substantially no resilient suspension components associated with any of the wheel axles. The presence of resilient suspension components, such as suspension springs, would prevent the required transfer of weight to the outer rear wheel.
A further linkage may connect said lower linkage to the chassis so as to prevent or substantially limit pivotal movement of the lower linkage about an axis parallel with the longitudinal axis of the chassis. The lower linkage may comprise a pair of tie rods mounted at locations spaced apart on the vehicle chassis and mounted for pivotal movement around an axis parallel with the longitudinal axis of the chassis, whereby adjustment of the length of said further linkage allows adjustment of the ride height of the vehicle.
The upper linkage may comprise a pair of tie rods mounted at locations spaced apart on the vehicle chassis and mounted for pivotal movement around an axis normal to the longitudinal axis of the chassis. The tie rods of the upper and lower linkages may have retaining means at their ends distal from the chassis for retaining a portion of a respective end of said steering member so as to form upper and lower universal or omni-axial joints.
The tie rods are of adjustable lengths allowing control of the king pin inclination and castor angles. Setting the tie rods at desired lengths allows control of the lengths of the linkages and therefore the relative positions of the ends of the steering member, which determines both the castor angle and the kingpin inclination angle. The ride of the vehicle and the amount of weight transferred while cornering, can be controlled before use of the vehicle.
The vehicle may have a wheelbase within the range 1480 to 1580 millimeters. The vehicle may have an overall length within the range 2160 mm to 2760 mm, an overall width within the ra
English Peter C.
Formula GP Limited
Young & Thompson
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