Hydraulic compression stop member for a hydraulic shock-absorber for a vehicle suspension with pressure relief device

A hydraulic stop member for hydraulic shock-absorbers, in particular for twin-tube hydraulic shock-absorbers for vehicle suspensions, the hydraulic stop member being designed to operate during the compression stroke of the shock-absorber to hydraulically dissipate kinetic energy when the shock-absorber is close to an end-of-travel position of the compression stroke,

• wherein the hydraulic stop member comprises
• a cup-shaped body which is mounted in a compression chamber of the shock-absorber, enclosed by an inner cylindrical tube of the shock-absorber, so as to be arranged coaxially to said inner cylindrical tube,
• a piston which is mounted at an end of a rod of the shock-absorber, coaxially thereto, so as to slide in the cup-shaped body when the shock-absorber is close to the end-of-travel position of the compression stroke, wherein the cup-shaped body comprises a side wall separate from said inner cylindrical tube and a bottom wall, the side wall and the bottom wall defining, along with the piston, a working chamber in which a damping fluid of the shock-absorber is compressed by the piston when the latter slides in the working chamber towards the bottom wall of the cup-shaped body, and
• a seal ring which is mounted around the piston to close the working chamber at the upper and thereof when the piston slides in the working chamber towards the bottom wall of the cup-shaped body, the hydraulic stop member having a bypass conduit configured to connect the working chamber with a portion of the compression chamber placed above the seal ring, and
• that further comprises a pressure relief valve that acts to keep the bypass conduit closed as long as the pressure in the working chamber remains below a given threshold value and to open the bypass conduit, thereby allowing discharge of the damping fluid from the working chamber to the compression chamber through the bypass conduit, when the pressure in the working chamber exceeds said threshold value.