Apparatus for the road-surface-dependent control of shock absorbers in a vehicle suspension system

Claim 1

Apparatus for controlling of a vehicle suspension system in response to road surface conditions, comprising: sensor means, mounted on the vehicle, for producing electrical signals representative of road surface undulations; circuit means, connected to the sensor means, for receiving the electrical signals from the sensor means and for processing these signals to produce control signals representative of the average heights of the road surface undulations; damping means for damping vibrations in the vehicle suspension system, said damping means having at least two chambers which communicate via a controllable bypass, wherein one of said chambers becomes smaller during compression of the suspension system and another of said chambers becomes smaller during expansion of the suspension system, said damping means having at least one of a controllable throttle and a controllable valve in said bypass; and means for connecting the control signals produced by the circuit means to the controllable bypass, and for controlling the bypass with said signals; wherein, the circuit means produces a first control signal (H) which is representative of the average height of the overall road surface undulations, and a second control signal (w) which is representative of a ratio of average heights for long-wave and short-wave undulations, and wherein said circuit means further processes the first and second control signals to produce at least one of a third control signal (F) for controlling the controllable throttle and a fourth signal (P) for controlling the controllable valve, in accordance with the following relationships: P=a.sub.o +a.sub.1 H+a.sub.2 w+a.sub.3 Hw F=b.sub.o +b.sub.1 H+b.sub.2 w+b.sub.3 Hw where, a o -a 3 and b o -b 3 are predetermined constants.