IE913823A1 - Vehicle - Google Patents

Abstract

The air spring (13) associated with a wheel-and-axle unit (12) is inflated from a compressor (14) via a pipeline (15) incorporating a flow controller (16) with a vent (17) to atmos.. The pressure of air in another line (21) to the air brake controller (18) is a function of load. A jointed linkage (31, 32) responsive to ground clearance produces an electrical signal (35) for a warning device (26) located in the driver's cab. ADVANTAGE - Driver is alerted automatically to loss of pressure and can take action against risk of redn. of braking force under full load.

Description

This invention relates to a vehicle of a kind incorporating a gas suspension system having a gas suspension unit for containing a selectively variable quantity of gas.

In a vehicle of this type control means such as a valve is provided between the suspension unit(s) and a source of pressurised gas, usually air, automatically to vary the mass of gas in the unit(s) such that the sprung part of the vehicle is at a prescribed height or within a prescribed height range irrespective of the load carried by the vehicle. Commonly a vehicle of this type is provided also with a manual override facility so that when for example it is at rest an operator can exhaust the pressurised gas from the suspension unit(s) either to atmosphere or to a reservoir in order to lower the sprung part of the vehicle for loading or unloading purposes. Similarly the manual override may alternatively or additionally allow more pressurised gas to be admitted to the suspension unit(s) to elevate the sprung part of the vehicle during loading or unloading.

A safety problem can arise, however, if the operator omits to disengage the manual override control before the vehicle is set in motion.

If the sprung part has been elevated, the resulting increase in centre of gravity adversely affects the stability of the vehicle when cornering, with a consequential safety risk.

Furthermore, if the sprung part has been lowered, possibly onto lower bump stops, it will no longer be properly sprung and damped; the load carried by the is then potentially subjected to vibration loads of a level greater and again stability when adversely affected.

A further problem arises, road type vehicle as opposed to vehicle and shock desirable , than may cornering be is particularly in a a rail vehicle, if 2. the braking system is arranged to provide a level of braking which is a function of the pressure of gas in the suspension unit(s). In this case if the manual override has resulted in no significant pressure in the suspension unit(s), the braking system will operate at a low level of maximum braking effort on the assumption that the vehicle is unloaded, and this will be extremely dangerous if the vehicle in fact is fully loaded and might require full braking capability in an emergency.

The present invention seeks to provide a vehicle in which the aforementioned problem is mitigated or overcome .

In accordance with one of its aspects the present invention provides a vehicle having a gas suspension system in which a gas suspension unit is arranged to contain a selectively variable quantity of gas, gas control means normally operable automatically to control the mass of gas in the gas suspension unit to maintain a sprung part of the vehicle at a prescribed height or height range, manually operable override means to disable automatic operation of the gas control means, sensing means responsive to the height of the vehicle and comprising transducer means which facilitates provision of an electrical signal which is a function of the height of the vehicle, and warning means operable in response to a signal received from the sensing means to provide the vehicle operator with a warning signal at least when the vehicle is in motion if the sprung part of the vehicle is not at said height or height range .

Preferably the warning means provides a warning signal when the vehicle power unit, e g internal combustion engine, is operational, but not when the vehicle is stationary with its power unit inoperative. The warning means may be arranged to provide a warning signal only at such times as the vehicle ignition system is switched on in the case of an internal combustion 3. engine type power unit.

The sensing means may comprise a flexible or telescopic mechanical link device which interconnects between sprung and unsprung parts of the vehicle, and may comprise transducer means such as a variable resistance potentiometer which facilitates provision of an electrical signal which is a function of the height of the vehicle. A particularly suitable transducer is a ceramic based potentiometer, and which may be of a rotary or linear form. The sensing means alternatively may be of a substantially non-mechanical type, e g an ultrasonic device adapted to provide said electrical signal.

The vehicle may incorporate a braking system of a kind in which a brake warning signal is given to the vehicle operator in the event of a defect in the braking system. The braking system may be of the kind in which the level of braking effort available is a function of the apparent load carried by the vehicle, and which may be sensed by means responsive to the pressure of gas in suspension unit(s). In a vehicle having said brake warning signal, the present invention further provides that the warning device for providing that signal shall serve also as the warning means for providing a warning in the event of the vehicle being in motion, or having the power unit operational, with the override means also in operation to disable the gas control means.

A particular advantage of arranging in the vehicle that the sensing means is responsive to the height of the vehicle is that not only does it provide a safety feature that takes into account the possibility of the vehicle operator omitting to disable the manual override means but it also provides a warning in the event that there is a failure in the air suspension to result in loss of pressure. In the event of loss of pressure in the air suspension system in the case of a vehicle having a braking system which operates 4. as a function of the apparent vehicle load as sensed by the pressure of gas in the air suspension units, loss of air pressure will normally result in only a lower level of braking effort being available even though the vehicle might be fully loaded; the risks arising in such a situation are substantially mitigated by the present invention insofar as loss of air pressure will result in the sensing means causing the warning means to operate and provide a warning signal.

One embodiment of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawing showing part of a vehicle in accordance with the present invention and with selected components indicated in block diagram form.

The sprung part 11 of a vehicle is supported relative to a vehicle wheel and axle structure 12 by means of an air suspension unit 13 of known construction. The air suspension unit 13 is connected to an air supply pump 14 via a pipe 15 which incorporates a flow control device 16 arranged by means not shown but known in the art normally to allow pressurised air into the suspension unit 13 or vent from its outlet port 17 automatically thereby to maintain the sprung part 11 of the vehicle at a prescribed height (usually within a prescribed height range ).

The vehicle additionally comprises an air brake system having a control unit 18 which applies air pressure to the brakes via a pipe 19 at a pressure level which depends on the level of brake effort applied by the vehicle driver (at input 20 of the unit 18) and the pressure of air as communicated to the unit 18 from the air suspension unit 13 via pipe 21, this pressure being a function of the load carried by the vehicle during normal operating conditions.

An electrical supply in the form of a conventional battery 25 is connected via the brake . control unit 18 to a brake warning buzzer and light unit 26 located in the vehicle cab. This operates in known manner to provide a brake warning in the event of a loss of air pressure in the brake system when the ignition control 27 is in an on condition. Thus at all times when the vehicle power unit 29 is operating or potentially available for operation the brake warning system is functional.

In addition to the aforedescribed components of the vehicle and which are arranged in a manner substantially known in the art, the vehicle comprises a cranked link arrangement 30 comprising two arms 31,32 pivotally connected to one another at 33. The lower arm 31 is pivotally secured to the lower unsprung half of the air suspension unit 13 and the other arm 32 is connected at its end furthest from the end 33 to move in unison with the wiper arm of a rotary ceramic potentiometer 3 5 secured to the sprung part 11 of the vehicle. The potentiometer 35 is arranged to connect electrically with the brake warning device 26. The warning device 26 incorporates an electronic control unit which compares the resistance of the potentiometer with the range of resistances associated with the vehicle being at a normal operating height and in the event of the resistance being outside the normal range and in the event of the vehicle ignition being switched on as indicated by the connection 28 between the ignition switch and brake warning device, the brake warning device will operate to give a warning signal.

Claims (12)

CLAIMS :

1. A vehicle comprising a gas suspension system having a gas suspension unit arranged to contain a selectively variable quantity of gas, gas control means normally operable automatically to control the mass of gas in the gas suspension unit to maintain a sprung part of the vehicle at a prescribed height or height range, manually operable override means to disable automatic operation of the gas control means, sensing means responsive to the height of the vehicle and comprising transducer means which facilitates provision of an electrical signal which is a function of the height of the vehicle, and warning means operable in response to a signal received from the sensing means to provide the vehicle operator with a warning signal at least when the vehicle is in motion if the sprung part of the vehicle is not at said height or height range.

2. A vehicle according to claim 1 wherein the vehicle comprises a vehicle power unit and the warning means is able to provide a warning signal when the vehicle power unit is operational but not when the vehicle is stationary with its power unit inoperative.

3. A vehicle according to claim 1 or claim 2 wherein the vehicle comprises an internal combustion engine power unit and the warning means is arranged to provide a warning signal only at such times as the vehicle ignition system is powered.

4. A vehicle according to any one of the preceding claims wherein the sensing means comprises a mechanical link device which interconnects between sprung and unsprung parts of the vehicle.

5. A vehicle according to claim 4 wherein the sensing means comprises a flexible link device.

6. A vehicle according to claim 4 wherein the sensing means comprises a telescopic mechanical link device .

7. A vehicle according to any one of the preceding 7 . claims wherein the transducer means comprises a ceramic based potentiometer.

8. A vehicle according to any one of claims 1 to 3 wherein the sensing means comprises an ultrasonic device .

9. A vehicle according to any one of the preceding claims and comprising a braking system of a kind in which a brake warning signal is given to the vehicle operator in the event of a defect in the braking system.

10. A vehicle according to claim 9 wherein a warning device for providing said warning signal serves also as the warning means for providing a warning in the event of the vehicle being in motion, or having the power unit operational, with the override means also in operation to disable the gas control means. 11. A vehicle according to claim 9 or claim 10 wherein the braking system is of a kind in which the level of braking effort available is a function of the apparent load carried by the vehicle . 12. A vehicle according to claim 11 wherein the apparent load carried by the vehicle is sensed by means responsive to the pressure of gas in a gas suspension unit.

11. 13. A vehicle constructed and arranged substantially as hereinbefore described with reference to the accompanying drawing.

12. 14. A vehicle according to any one of the preceding claims and which is a road type vehicle.