Land vehicles – Wheeled – Running gear
Patent
1984-09-20
1986-12-02
Love, John J.
Land vehicles
Wheeled
Running gear
280611, 280DIG1, B60G 1126
Patent
active
046259937
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention relates to vehicle suspension systems.
The ride qualities of conventional road vehicles cannot be optimised because the springs and dampers of the suspension cannot be arranged to deal with all the various modes of movement of the vehicle body. Moreover, current development of road passenger vehicles tends towards weight reduction and improved aerodynamic efficiency, primarily in order to achieve reduced fuel consumption. However, the loads to be carried are not reduced. The suspension systems of such vehicles are consequently required to accommodate an effectively widening range of load conditions. It is consequently necessary to select spring rates so as to obtain what is necessarily a compromise between desired ride characteristics and desired control of vehicle attitude under various load and manoeuvre conditions.
The invention is accordingly concerned with an improved vehicle suspension system permitting control of the ride of the vehicle and its attitude to be achieved substantially independently. Preferably, the system is capable of keeping a vehicle substantially stable in all planes of movement, irrespective of external forces.
The invention accordingly provides a vehicle suspension system comprising wheel suspension devices the displacement of which can be varied, and means responsive to the loading of the suspension devices to feed back to the devices electric signals effecting a predetermined displacement.
The invention also provides an active vehicle suspension system comprising an hydraulic actuator for supporting each wheel, means for sensing the position of the actuator piston, and means for effecting positive adjustment of the piston position.
The invention also provides an active vehicle suspension system for a road vehicle, the system comprising a hydraulic actuator associated with each road wheel, means responsive to forces acting on the actuator pistons and to the displacements of the actuator pistons to generate signals representative of forces corresponding to at least one of the heave pitch roll and warp modes of vehicle movement, and a control system for treating the signals to obtain control signals for effecting desired piston displacement.
The hydraulic actuators or rams employed in the active suspension systems of the invention may replace or may be used in parallel with passive spring and damper type suspension elements as are solely employed in conventional systems. For example, the vehicle suspension springs may be retained to support the deadweight of the vehicle, so that the hydraulic actuators are effective only in respect of dynamic movements during driving of the vehicle. The actuators are preferably fitted concentrically within the springs. Each actuator is associated with a first transducer, for example, a load cell, and a second transducer, for example a linear variable displacement transformer, for sensing load and piston position or displacement respectively, and with means, such as an electrically driven servo control valve, for moving the piston to a position dependent on the transducer outputs. The command signals supplied to the control valves are generated by a control system comprising a digital, analogue or hybrid computer, the programming of which can if desired be selectively variable by the vehicle driver.
The transducer signals representative of the loads reacted by the actuators and the instantaneous load values can be employed to generate signals corresponding to the three rigid body modes, heave, pitch and roll as well as the warp mode. The signals are scaled by the control system computer to provide signals corresponding to desired generalised displacements in the modes, which provide output signals to the servo valves to effect appropriate piston displacement.
The outputs of the eight transducers, two associated with the suspension of each of four road wheels, can thus be fed into a computer which implements a control law based on the following considerations.
In a second order system driven by motion y of the attachment p
REFERENCES:
patent: 3124368 (1964-03-01), Corley et al.
patent: 3625539 (1971-12-01), Crouch et al.
patent: 3770292 (1973-11-01), Palazzetti
patent: 3836161 (1974-09-01), Buhl
patent: 3881736 (1975-05-01), Wilfert
patent: 4054295 (1977-10-01), Elliott
patent: 4065154 (1977-12-01), Glaze I
patent: 4185845 (1980-01-01), Misch et al.
patent: 4333668 (1982-06-01), Hendrickson et al.
patent: 4371191 (1983-02-01), Goldberg et al.
Williams David A.
Wright Peter G.
Group Lotus Public Limited Company
Love John J.
Rice Kenneth R.
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