Apparatus for damping courses of motion

An apparatus for damping courses of motion of two bodies or masses separated from each other and moving relative to one another and in their absolute positions at variable speeds, in particular for damping resilient wheel suspension systems in vehicles, road vehicles, buses, railways and the like, comprising a cylinder, a piston displaceable in said cylinder, first and second work chambers in said cylinder, said cylinder and said piston being connected to a respective one of said bodies, a single variable pressure medium damper control valve being arranged to effect a variable flow of a pressure medium to and fro between one work chamber and other work chamber of said first and second work chambers, a signal control means, first sensor means adapted to determine a relative speed of said two bodies relative to one another and to direct a corresponding first signal to said signal control means, second sensor means adapted to determine an absolute speed of at least one of the bodies independently of one another to thereby produce a corresponding second signal which is directed to said signal control means, said first and second signals representing a combined damping force (F.sub.d =B.sub.A.v+B.sub.p V.sub.rel) having an active damping coefficient (B.sub.A) and a passive damping coefficient (B.sub.p) correlated to a body velocity V and a relative speed V.sub.rel respectively, said variable pressure medium damper control valve including a valve adjusting member being configured such that said valve adjusting member effectively moves in at least one of two axial movement directions in accordance with a signal received from said signal control means, one movement direction supplying a tension stage and one movement direction supplying a compression stage, a first fluid line (14a") that connects said first work chamber (12a) via a first flow connection (23a) to one portion of said variable pressure medium damper control valve and a second fluid line (14b") that connects said second work chamber via a second flow connection (23b) with a second portion of said variable pressure medium damper control valve, at least one-way check valve connected in series with said pressure medium variable damper control valve and one of said first and second work chambers, a position of said valve adjusting member relative to said first and second connection (23a and 23b) being controlled via said first and second sensor means and said signal control means, said valve adjusting member being adapted to assume different positions relative to said first and second flow connections thereby providing a lesser pressure medium relative to said second flow connection with a simultaneous greater pressure medium flow relative to said first flow connection and vice versa to generate different flow resistances for said damping force (F) applied and acting in different directions and further to generate asymmetrical damping properties for a respective predetermined position of said valve adjusting member as determined by said signal control means for said valve adjusting member to enable the movement of said valve adjusting member continuously out of a maximum opening position for at least one of said compression stage and said tension stage and into an arbitrary intermediate position to thereby attain a semi-active damper system, such that whatever a combined damping force determined by said signal control means in accordance with signals from said first and second sensor means has a algebraic sign (+ or -) opposite that of the damping forces made necessary by said courses of motion of the two bodies, said damping force is substantially reduced to zero (F.congruent.0) and said vehicle has a smooth ride.