GB2094243A - Motor driven wheeled vehicles - Google Patents

Abstract

A motor driven wheeled vehicle comprises a tractor unit 10 carrying power unit 22 driving wheels thereof, and a passenger pod 11 coupled to the tractor by a universal joint 12 for horizontal and vertical pivotal movement relatively thereto, the power unit being controlled and the tractor unit being steered from the passenger pod. One pair of wheels 15 of the tractor unit is independently driven from the power unit so that steering of the tractor unit is effected by differential control of the drive to the wheels. The drive wheels may be driven by hydraulic or electric motors. The power unit may comprise a turbo-charged engine. A gyro system may be provided for controlling the suspension of the passenger pod. The passenger pod may be arranged to "bank" during travel of the vehicle around a bend. The vehicle may take the form of a motor car or a goods vehicle. <IMAGE>

Description

SPECIFICATION Improvements in or relating to motor driven wheeled vehicles The invention relates to motor driven wheeled vehicles. For convenience, throughout this specification the expression "motor car" will be used, but it should be understood that the invention is applicable to motor driven wheeled vehicles of all types including commerical vehicles for transport of goods and other special purposes as well as to motor cars for private use.

The present day motor car, although it has been improved and refined substantially throughout its history, remains fundamentally unchanged from its earliest design concept.

According to that original concept, which still persists to the present day, the power unit of a vehicle, usually an internal combustion engine, the gearbox, transmission, fuel tanks and all ancillary equipment concerned with powering the vehicle, are located within a vehicle body which also contains the seats for the occupants of the vehicle. Since the comfort and safety of the occupants requires that the compartment containing them be adequately sprung, it has always been the practice to provide spring suspension between the body and the wheels and to keep the unsprung weight of the vehicle as low as possible. As a result of the high sprung weight, the vehicle tends to be unstable and many of the refinements which have been made to motor vehicles over the years have been directed to expensive and complex expedients for controlling this inherent lack of stability.

The present invention sets out to provide a fundamentally different design concept for a motor vehicle which will be inherently more stable than the conventional design and may thus be simpler in construction and less costly to build.

The invention also provides an improved arrangement for powering and steering a motor vehicle.

Basically, the invention sets out to separate the power unit, and ancillary equipment for driving the vehicle, from the passenger compartment so that the passenger compartment may be designed solely to meet the safety and comfort requirements of the occupants, such design no longer having to be a compromise to permit the body also to accommodate the power unit. In effect, the invention sets out to apply to a motor driven vehicle the principle used in horse-drawn vehicles since time immemorial whereby the power unit, i.e. the horse, is external to the vehicle body and imparts motion to it without being carried by the body.

According to the invention, therefore, a motor driven wheeled vehicle comprises a tractor carrying a power unit driving the wheels thereof, and a trailer coupled to the tractor for horizontal and vertical pivotal movement relatively thereto, the trailer having a location for one or more occupants and means for controlling the power unit and steering the tractor from said location.

Preferably the tractor has at least one pair of wheels which are independently driven from the power unit, steering of the tractor being effected by differential control of the drive to said wheels. For example, the tractor may have four wheels, the front wheels being independently driven and the rear wheels being undriven. The rear wheels may, for example, be castor wheels.

The power unit preferably comprises individual motors driving the driven wheels respectively of the tractor and independently controllable to effect steering of the tractor.

For example, the motors may comprise hydraulic motors supplied with hydraulic fluid under pressure from an accumulator, the accumulator being pressurised by an hydraulic pump driven by an internal combustion engine. Alternatively, the motors may be electric motors powered by an electric generator driven by an internal combustion engine.

The trailer may include conventional forms of springing between the body and wheels thereof, and preferably the arrangement is such that the centre of gravity of the body is disposed below the longitudinal roll axis of the body. With such an arrangement the trailer body will "bank" into a curve around which the vehicle is driven.

The following is a more detailed description of various embodiments of the invention reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic side view, partly in section, of a motor vehicle in accordance with the invention, Figure 2 is a diagrammatic plan view of the tractor unit of the motor vehicle, and Figure 3 is a diagrammatic plan view of an alternative form of vehicle.

Referring to Figs. 1 and 2, the vehicle comprises a tractor unit indicated generally at 10 to which is connected a trailer unit in the form of a passenger "pod" 11. The passenger pod 11 is connected to the tractor unit by a ball-and-socket coupling 12, or any other suitable form of universal coupling permitting horizontal and vertical pivoting movement.

The coupling 1 2 is connected between forwardly extending arms 1 3 on the passenger pod and a fixed part of the body of the tractor unit.

The tyres of the wheels 15, 16, 1 7 and 18 are small, wide and inflated to a high pressure. The engine 22 may be of three, four, five or six cylinders and a turbo-charger may be provided if required. The tractor unit may be unsprung, or may have minimum springing sufficient to prevent major shocks being trans mitted to the power unit and ancillary equipment.

The passenger pod, the weight of which may comprise only about 20% of the total weight of the vehicle, is fitted out with the conventional fittings for the comfort and convenience of the passengers. The pod has ground-engaging wheels 14 adjacent the rear end thereof, the wheels being mounted on the pod by conventional springing and being provided with a conventional braking system. A gyro system may be provided controlling the suspension of the passenger pod 11 and its connection to the tractor unit through the arms 1 3 and joint 1 2 so as automatically to maintain the passenger pod level for the comfort of the passengers.

The passenger pod 11 may be of semimonocoque construction for lightness. Preferably, the centre of gravity of the pod is disposed below the longitudinal roll axis thereof so that as the vehicle travels along a curved path the pod tends to "bank" into the curve.

This differs from the conventional arrangement in which the centre of gravity of a vehicle is disposed above the roll axis, so that the vehicle body tends to lean outwardly away from the curve, leading to discomfort for the passengers and instability for the vehicle. The passenger pod may be ballasted to keep the centre of gravity low, and the ballast may be in the form of an automatically displaceable weight, such as a body of liquid, which moves under centrifugal force to enhance the banking effect.

As best seen in Fig. 2, the tractor unit 10 has front wheels 1 5 and 1 6 and rear wheels 17 and 18. The rear wheels 17 and 18 may be castor wheels and may be provided with a conventional hydraulic braking system controlled from the driver's position in the passenger pod 11.

The front wheels 1 5 and 16 are individually driven by hydraulic motors 19 and 20 respectively. Hydraulic fluid under pressure is supplied to the motors from an accumulator tank 21, and the flow of hydraulic fluid from the accumulator to the motors is controlled from the driver's location in the passenger pod. The accumulator tank is pressurised by a diesel or petrol engine 22 mounted on the tractor vehicle and operating a pump (not shown). The fuel tank 23 for the engine 22 is also mounted on the tractor unit.

Control of the speed of the vehicle is effected by the driver controlling the flow of hydraulic fluid between the accumulator and the motors 1 9 and 20. The driver has no direct control of the engine 22. The engine 22 is automatically controlled to maintain at all times the required hydraulic pressure in the accumulator tank 21. To achieve this the engine may be controlled by a microprocessor and may thus be arranged to run at the most efficient speed to give the best possible fuel economy. In fact the engine will normally run at substantially constant speed except at times when high performance is required and rapid repressurisation of the accumulator tank 21 is necessary. The microprocessor controlling the operation of the engine 22 may be located either on the tractor unit or in the passenger pod.

Steering of the vehicle is effected by differentially controlling the speeds of rotation of the wheels 1 5 and 1 6 of the tractor unit.

Thus the overall speed of rotation of the hydraulic motors 1 9 and 20 is controlled by an accelerator pedal operated by the driver, but the motors are also capable of differential speeds to effect steering, the relative speeds of the two motors being controlled by turning a steering wheel. Thus, when the driver turns the steering wheel to the right the speed of the wheel 1 5 is increased relative to the speed of rotation of the wheel 16. Similarly for turning to the left the wheel 1 6 is rotated at the faster speed.

The hydraulic system driving the front wheels 1 5 and 1 6 may also be used as a braking system, the motors 1 9 and 20, when braking is being effected, pumping hydraulic fluid under pressure back into the accumulator tank 21 and building up the pressure therein.

There is thus a considerable saving in energy due to a high proportion of the kinetic energy of the vehicle being stored as pressure in the accumulator tank 21 when the vehicle is slowed down.

Although hydraulic motors 1 9 and 20 are preferred, the wheels 1 5 and 1 6 could be driven by independently controlled electric motors powered by a generator driven by the engine 22. Alternatively, the engine 22 might even be arranged to store power in a rotatable flywheel, suitable transmission being provided to drive the wheels of the tractor unit from the flywheel as required.

Fig. 3 shows an alternative arrangement in which the tractor unit 24 is only a two wheeled unit. The two wheels 25 and 26 are independently driven and controlled as described in relation to the Fig. 2 arrangement and the engine and the hydraulic accumulator tank are mounted on the tractor unit, as before.

Claims (9)

1. A motor driven wheeled vehicle comprising a tractor carrying a power unit driving the wheels thereof, and a trailer coupled to the tractor for horizontal and vertical pivotal movement relatively thereto, the trailer having a location for one or more occupants and means for controlling the power unit and steering the tractor from said location.

2. A motor vehicle according to claim 1, wherein the tractor has at least one pair of wheels which are independently driven from the power unit, steering of the tractor being effected by differential control of the drive to said wheels.

3. A motor vehicle according to claim 1, wherein the tractor has four wheels, the front wheels being independently driven and the rear wheels being undriven.

4. A motor vehicle according to claim 3, wherein the rear wheels of the tractor are castor wheels.

5. A motor vehicle according to any of claims 1 to 4, wherein the power unit comprises individual motors driving the driven wheels respectively of the tractor and independently controllable to effect steering of the tractor.

6. A motor vehicle according to claim 5, wherein the motor comprises hydraulic motors supplied with hydraulic fluid under pressure from an accumulator, the accumulator being pressurised by an hydraulic pump driven by an internal combustion engine.

7. A motor vehicle according to claim 5, wherein the motors are electric motors powered by an electric generator driven by an internal combustion engine.

8. A motor vehicle according to any of claims 1 to 7, wherein the trailer includes springing between the body and wheels thereof, and wherein the arrangement is such that the centre of gravity of the body is disposed below the longitudinal roll axis of the body.

9. A motor driven wheeled vehicle substantially as hereinbefore described with reference to the accompanying drawings.