Height adjustment in a vehicle fitted with air suspension

Details Height adjustment in a vehicle fitted with air suspension Height adjustment in a vehicle fitted with air suspension

1990-10-15

1992-09-01

Noland, Tom

Measuring and testing

Instrument proving or calibrating

Volume of flow, speed of flow, volume rate of flow, or mass...

280707, 36457104, G01D 1800, B60G 17015

Patent

active

051428970

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to a method of calibrating a height sensor in an electronically controlled height regulating device of an air spring suspension system of a vehicle. The invention includes an apparatus for calibrating the height sensor.


BACKGROUND OF THE INVENTION

Hitherto, when calibrating the height sensor of an air spring suspension, it has been necessary first to bring the height of the vehicle body to a suitable reference height, that is to say, the desired height. This entails the use of a lifting device, such as a vehicle hoist, a lifting platform or under-frame blocks. The height sensor is then adjusted, for example, by adjusting its fixing, until it delivers the correct electrical value associated with that height. Such an expenditure and measuring technique do not lend the method to mass production techniques.


SUMMARY OF THE INVENTION

It is an object of the invention to provide a calibration method which does not require any additional mechanical appliances for it to be carried out.
This object is met by the calibration method of the invention. According to a feature of the method of the invention, the height regulating function is disabled and the air springs are controlled externally to bring the body height to a desired null position whereafter the height sensor reading (h.sub.n) for this null position is programmed into the regulating device to serve as a reference value or an initial reference value for the height regulation. The air spring suspension is itself used as a mechanical jack for raising or lowering the vehicle body to a desired height at which adjustments may be made.
It is only necessary for the height sensor to be fixed in a roughly adjusted position as the final calibration can be effected purely electronically. Thus, the height sensor is secured in a roughly adjusted position after the vehicle body is brought to the desired null position and before the height sensor reading is programmed into the regulating device.
The extreme limits between which the height adjustment may be made can be established by programming the null position into the regulating device. The vehicle body is then raised by using the air springs until the air springs are fully expanded and the corresponding height sensor reading is programmed into the regulating device as a maximum height value. Also, and after programming the null position into the regulating device, the vehicle body is lowered by using the air springs until the body is resting on its stops and the corresponding height sensor reading is programmed into the regulating device as a minimum height value.
The commands for carrying out the method can be entered into the electronic control device of the height regulating device by plugging in a separate test device. Alternatively, an existing remote control can be adapted or programmed to carry out the calibration.
The invention includes apparatus for calibrating a height sensor in a height regulating device of an air spring suspension system of a vehicle.
The reference signal, or a signal from which the reference signal may be derived, is preferably stored in a non-volatile memory.
One embodiment of the apparatus comprises a test device and such a test device can be a small commercially available computer.
In another embodiment, a conventional remote control can be programmed to be used as such a test device.


BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described, by way of example, with reference to the accompanying drawing, in which:
FIG. 1 is a diagram of an air suspension system for a vehicle fitted with a height regulating system; and
FIG. 2 is a block diagram of the height regulating system and calibrating apparatus in accordance with the invention.


DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows diagrammatically a part of a vehicle body 10 attached to an axle 12 by an air suspension 14. The air suspension 14 comprises an air spring bellows 16 and a height measuring sensor 20, each arranged between the vehicle b

REFERENCES:
patent: 4575115 (1986-03-01), Tatemoto et al.
patent: 4593920 (1986-06-01), Natsume et al.
patent: 4761608 (1988-08-01), Franklin et al.

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