Boots – shoes – and leggings
Patent
1991-12-13
1994-03-22
Chin, Gary
Boots, shoes, and leggings
280707, 280840, B60G 1700
Patent
active
052970450
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a vehicle suspension system and particularly to a wheeled land vehicle suspension system.
In wheeled land vehicles it is common practice to provide a suspension system which serves to support the wheel and hub assemblies for movement relative to the chassis or body of the vehicle, with some form of springing being provided between each wheel and hub assembly and the chassis or body.
Under certain circumstances it can happen that a wheel and hub assembly reaches the limit of its possible movement towards the chassis or body, and in order to prevent the possibility of damage in such circumstances vehicles are generally provided with so-called `bump stop` in the form of a resilient member, often of rubber, against which part of the wheel and hub assembly strikes at the limit of its movement towards the chassis or body.
A disadvantage of such known bump stop arrangements is that striking of the wheel and hub assembly against the resilient member can occur with a high force resulting in jarring of the vehicle, and that after striking the resilient member the wheel and hub assembly rebounds, thus adversely affecting the ride quality and handling characteristics of the vehicle.
Recently vehicles have been developed having so-called active suspension systems (see for example EP-A-0114757 and U.S. Pat. No. 4,761,022) which utilize wheel and hub assembly suspension devices in the form of hydraulic actuators by which the wheel and hub assemblies are mounted to the chassis or body. These suspension devices are controlled by signals representing various movement parameters of the vehicle, such as heave, pitch, roll and warp modes of movement of the vehicle, and speed, and lateral and longitudinal acceleration of the vehicle, to obtain a desired ride quality and attitude for the vehicle under all driving conditions, the control signals being derived from appropriate transducers located at appropriate positions on the vehicle. In the system disclosed in U.S. Pat. No. 4,761,022 control signals are also obtained from steering angle and yaw rate sensors on the vehicle, the signals from these sensors being used to control the steering characteristics of the vehicle.
SUMMARY OF THE INVENTION
According to the present invention there is provided a suspension unit of a wheeled vehicle comprising a hydraulic actuator of which the displacement is variable by control of the flow of hydraulic fluid to at least one side of the piston and cylinder, a device to connect the actuator to the body and a wheel hub of the vehicle so that variation of the displacement of the actuator controls the height of the body above the wheel hub, transducers on the vehicle which generate signals indicative of one or more of force applied to the body of the actuator, longitudinal acceleration of the vehicle, lateral acceleration of the vehicle, speed of the vehicle and yaw rate of the vehicle, a control device to control the flow of fluid to and from the actuator, in response to signals generated by the transducers to control the vehicle suspension, said control device comprising a processor which generates a velocity demand signal which corresponds to a velocity required of the actuator and a hydraulic control circuit controlled by the velocity demand signal, a displacement detector device to detect when the actuator length approaches a desired maximum/minimum value and a device to modify the velocity demand signal which operates in response to the control signal generated by the displacement detector device to bring the extension/contraction of the actuator gradually to a stop as the desired maximum/minimum value is reached.
Preferably, the device to modify the velocity demand signal acts only as the actuator approaches a limit and not as the actuator moves away from a limit. The device to modify the velocity demand signal preferably comprises a device to weight the velocity demand signal selectively as a function of the displacement of the actuator and/or the value of the velocity demand signal
REFERENCES:
patent: 4579366 (1986-04-01), Doi et al.
patent: 4677263 (1987-06-01), Hamilton et al.
patent: 4700971 (1987-10-01), Doi et al.
patent: 4787649 (1988-11-01), Watanabe et al.
patent: 4801155 (1989-01-01), Fukushima et al.
patent: 4825370 (1989-04-01), Kurosawa
patent: 5062660 (1991-11-01), Satoh et al.
patent: 5141245 (1992-08-01), Kamimura et al.
Williams David. A.
Wright Peter G.
Chin Gary
Group Lotus PLC
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