A damper includes housing bounding a chamber. A barrier is movably disposed within the chamber so as to divide at least a portion of the chamber into a pressure compartment and a control compartment each having a volume, the volume of the pressure compartment and the control compartment each being adjustable...http://www.google.fr/patents/US7124865?utm_source=gb-gplus-shareBrevet US7124865 - Pressure regulating dampers
