Suspension apparatus of automotive vehicle

Abstract

A fluid cylinder unit is disposed between a vehicle body and each of wheels and suspension characteristics are changed by changing the control amount of operating fluid to be supplied to or discharged from the fluid cylinder. The control amount is given based on predetermined conditions using the traveling state of the vehicle such as vehicle height, velocity of displacing the vehicle height and vertical acceleration as a parameter. A filter causes a gain of the control amount to be reduced as the frequency of vibration gets larger. A time constant of the filter is so set to become larger as the operated control amount gets larger when the control amount is smaller than a predetermined value, while the time constant is set to the predetermined value when the control amount is equal to or larger than the predetermined value. Specifically, the control amount Q is determined by the following formula: Q=Qc/(1+k.times.Qo.times.S) (where Qc is a control amount operated; k is a constant; S is a Laplace's operator; and Qo is a time constant set to Qo=Qc when Qc is lower than a predetermined value W, and to W when Qc is equal to or larger than the predetermined value W.) The filter can prevent oscillation without causing any decrease in sensitivity to control.

Dependencies are inferred from the claim text.