Semi-active damper for vehicles and the like

Claim 1

In a hydraulic damper assembly for damping the transmission of motion between spaced and relatively movable members interconnected thereby, said assembly including a double-wall cylinder adapted to be connected to one of said members and having an inner fluid chamber and an outer annular fluid chamber encircling said inner chamber, a piston disposed within and movable longitudinally of said inner chamber, a rod connected to said piston and having an end portion extending from said cylinder and adapted to be connected to the other of said relatively movable members, the improvement comprising: means defining a pair of first and second parallel passageways interconnecting said inner and outer chambers adjacent one end thereof; means defining another pair of first and second parallel passageways interconnecting said chambers adjacent the opposite end thereof; pressure responsive check valve means associated with said first passageways for inhibiting fluid flow therethrough from said inner chamber to said outer chamber, and for at times permitting relatively free fluid flow through said first passageways from said outer chamber to said inner chamber; control valve means associated with said second passageways for controlling fluid flow therethrough, said control valve means including two movable control valve members associated with and located adjacent respective ones of said second passageways, each of said movable valve members being moveable between a flow-restricting position and a flow-permitting position wherein said valve member respectively permits only relatively restricted fluid flow and relatively unrestricted fluid flow through the therewith associated one of said second passageways, said control valve means having a first operating condition wherein one of said valve members occupies said flow-permitting position thereof while the other of said valve members occupies said flow-restricting position thereof, and having a second operating condition wherein said one of said valve members occupies said flow-restricting position thereof and said other of said valve members occupies said flow-permitting position thereof; electromagnetic drive means for selectively effecting rapid transition of said valve means between said operating conditions and for thereby effecting rapid and substantially simultaneous reversals of the positions of said valve members, the movements of each of said valve members between said flow-restricting and flow-permitting positions thereof being produced by electromagnetic forces imparted thereto by said drive means.