GB2288372A

GB2288372A - Pneumatic control of vehicle throttle and brakes

Info

Publication number: GB2288372A
Application number: GB9406201A
Authority: GB
Inventors: Christopher Goddard
Original assignee: UNIVERSAL MOBILITY Ltd
Current assignee: UNIVERSAL MOBILITY Ltd
Priority date: 1994-03-29
Filing date: 1994-03-29
Publication date: 1995-10-18
Also published as: GB9406201D0

Abstract

A control system for an invalid vehicle includes an air compressor delivering air to a reservoir, a brake actuator (2, Fig. 2) and a throttle actuator (4, Fig. 3) controlled in unison by a control mechanism 6. The control mechanism 6 comprises two miniature pressure regulators 30, 32 actuable by means of a simple operating lever 52 through the agency of a rack and pinion. The compressor may be electrically driven. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO CONTROL SYSTEMS FOR MOTORISED VEHICLES This invention concerns improvements in or relating to control systems for motorised vehicles.

In particular, but not exclusively, the present invention has reference to invalid vehicles for which the control systems have to be specially designed to enable the disabled to actuate the mechanisms required for the proper charge of the vehicle, namely steering, acceleration, and braking.

It is the practice to customise the usual vehicle control systems in order to allow the invalid driver to effect the requisite movements involved in controlling the vehicle as effortlessly as possible. Conventionally, the control systems are in essence servo systems using vacuum as the energy source since most internal combustion engines provide such a source without the provision of auxiliary equipment. The disadvantage of using vacuum as the energy source is its low intensity resulting in the need to employ bulky equipment in order to store any reasonable amounts of energy. In particular, the pipework has to be of large diameter and the relevant actuators require to be of large bore in order to provide the necessary force for their operational function. The resultant assembly and disposition of such macro-equipment are an unwelcome and potentially dangerous intrusion into the driver area of the vehicle just in front of the driver's seating position.

It is an object of the present invention to provide an improved control system for an invalid vehicle which affords the driver ease of control coupled with comfortable seating in the usual driving position.

According to the invention a control system for a motorised invalid vehicle includes a pneumatic power source, an air reservoir, an actuator for the brakes of the vehicle, a further actuator for the engine throttle, and a manual control mechanism including at least two pressure regulators interconnected between the air reservoir and the actuators and operable to initiate and vary the flow of air thereby to control the actuation of the brakes and the throttle.

The pneumatic power source may conveniently be a small electrically driven compressor arranged to deliver air to the reservoir in a circuit provided with the requisite filters and non-return valves.

The compressor may advantageously be controlled by a pressure switch having the requisite hysteresis to enable the reservoir to be maintained at a predetermined pressure, for example 7 bar. A second pressure switch may be employed for the purpose of giving a warning of low pressure in the system.

In a system which requires a back-up, a second reservoir is fitted and connected to the first by a non-return valve, the second reservoir being provided with its own low pressure warning pressure switch.

The control mechanism may consist of two miniature plunger-operated pressure regulators actuable by an operating lever. The lever may be connected to a pinion engaging a rack provided for each of the regulators which are so arrayed that the regulators are actuated in opposition one to the other. Thus, the brakes are applied as the throttle is moved to decelerate the vehicle and in the opposite vein the throttle is moved to accelerate the vehicle while the brakes are released.

The control mechanism is conveniently spring-loaded, the spring rate being variable to cater for different users.

The control mechanism is advantageously housed within a small box which can be disposed at any appropriate and convenient position within reach of the driver's position, there being no restriction in this respect since the control mechanism is connected within the pneumatic system by small bore pipes, preferably flexible.

The actuator for the brakes may be a pneumatic cylinder of conventional or rolling diaphragm type, and is arranged to apply force directly onto the brake pedal of the vehicle. The brake actuator may be connected directly to the control mechanism or via an air relay to boost the volume if the particular vehicle so requires.

The size of the cylinder is preferably selected such that the maximum braking force is achieved at the predetermined maximum pressure.

The throttle actuator may comprise a rolling diaphragm air cylinder fitted with a spring which has a rate to give full extension at the predetermined maximum pressure. The rolling diaphragm serves to reduce or prevent any stiction and results in little or no hysteresis thereby giving a cylinder extension that is proportional to the applied pressure.

By way of example only, one embodiment of control system for an invalid vehicle is described below with reference to the accompanying drawings in which: Figure 1 is a diagrammatic representation of a control mechanism; Figure 2 is a diagrammatic representation of a brake actuator in situ with a brake pedal; Figure 3 is a diagrammatic representation of a throttle actuator; Figure 4 is a circuit diagram of the control system.

Referring to the drawings, a control system for an invalid vehicle (not shown) includes a compressor 1 driven by an electric motor 3 which in use delivers air at 7 bar to a reservoir 5 feeding a brake actuator 2 and a throttle actuator 4 via a control mechanism 6.

The brake actuator 2 is in the form of an air cylinder 8 to which air is supplied through the control mechanism 6 from the reservoir, the piston rod of the cylinder being pivotally connected to a brake pedal 10. The brake pedal 10 is pivotally mounted on a structure 12 and also carries a push rod 13 extending through the bulkhead 14 to the master cylinder (not shown) of the braking system of the vehicle.

Referring now to Figure 3, the throttle actuator 4 comprises a cylinder 15 within which there is located a spring-loaded piston 16 carried on a rod 18 extending through one end of the cylinder, the other end being provided with a pressure port 17. The piston 16 carries a rolling diaphragm 20 suitably affixed thereto and to the cylinder 14, the diaphragm affording essentially no hysteresis and giving piston movement proportional to the applied air pressure. The piston rod 18 carries a yoke 22 for connection to the throttle (not shown) of the vehicle.

Referring to Figure 1, the control mechanism 6 for the control system includes two miniature pressure regulators 30, 32 each comprising a cylinder 34, 36 respectively within which move plungers (not shown) with connecting rods 38, 40. Each cylinder has appropriate ports 42 for the supply and discharge of air dependent upon the position of the respective plunger and these ports are connected between the reservoir and the brake and throttle actuators and act as servos therefor.

Each connecting rod 38, 40 carries a rack 44, 46 engaging a pinion 48 carried on a rotatable shaft 50. An operating lever 52 is attached to the shaft 50 such that rotation thereof occasions the rectilinear movement of the racks 44, 46 in opposite directions, the effect being that when one regulator causes pressure to be applied to operate the brake cylinder 8, the other regulator operates to reduce the throttle opening.

Thus with one simple movement of the lever 52, control of vehicle propulsion is achieved, by means of two miniature regulators which can easily be disposed in a small space at any convenient location in the driver area within the vehicle. Since the throttle actuator acts directly on the throttle there is no intrusion into the driver area, and the disposition of the brake actuator in direct association with the brake pedal can easily be accommodated without any significant consumption of the available space.

Referring now to Figure 4, there is shown a circuit diagram of the control system according to the invention which includes a compressor 1 driven by an electric motor 3 delivering air to a primary system including a reservoir 5 along a line 7 provided with a pressure switch 9 connected to an audible and visual alarm (not shown). Air is fed to the brake actuator 2 and the throttle actuator 4 along line 11 via the control mechanism 6.

The throttle actuator 2 is fed by a line 19 from the regulator 30, while the brake actuator 4 is fed by line 21 from the regulator 32 via a shuttle valve 23.

The compressor 1 also delivers air through a non-return valve 59 to an optional secondary or stand-by brake system shown at 60 which comprises a permanently charged reservoir 62 feeding into a line 63 provided with a secondary alarm switch 65. The line 63 is connected to a solenoid valve 67 which is operable by an emergency button (not shown), the valve 67 feeding a line 69 connected via the shuttle valve 23 to the brake actuator 4.

In the event that the primary system should fail an audible and visual alarm is actuated by the switch 9 and the driver of the vehicle can depress an emergency button to operate the valve 67 thereby causing air to pass directly to the brake actuator 4 to effect arrest of the vehicle.

The advantage of the instant invention is the miniaturisation of the control system which affords the ability of invalid vehicle designers to focus upon amenity for the disabled.

Claims

CLAIM8:

1. A control system for a motorised invalid vehicle including a pneumatic power source, an air reservoir, an actuator for the brakes of the vehicle, a further actuator for the engine throttle, and a manual control mechanism including at least two pressure regulators interconnected between the air reservoir and the actuators and operable to initiate and vary the flow of air thereby to control the actuation of the brakes and the throttle.

2. A control system according to Claim 1 in which the pneumatic power source is an electrically driven compressor arranged to deliver air to the reservoir.

3. A control system according to Claim 1 or 2 in which the compressor is controlled by a pressure switch having the requisite hysteresis to enable the reservoir to be maintained at a predetermined pressure.

4. A control system according to Claim 3 in which a further pressure switch is employed and is adapted to give a warning of low pressure in the system.

5. A control system according to any one of the preceding Claims 3 or 4 in which a second reservoir is fitted as a back-up and is connected to the first by a non-return valve, the second reservoir being provided with its own low pressure warning pressure switch.

6. A control system according to any one of the preceding claims in which the control mechanism consists of two miniature plunger-operated pressure regulators actuable by an operating lever.

7. A control system according to Claim 6 in which the lever is connected to a pinion engaging a rack provided for each of the regulators which are so arrayed that the regulators are actuated in opposition one to the other.

8. A control system according to any one of the preceding claims in which the control mechanism is conveniently spring-loaded, the spring rate being variable.

9. A control system substantially as hereinbefore described with reference to the accompanying drawings.