US Patent 7322570 Fluid-filled vibration damping device

A fluid-filled vibration damping device including: an elastic body connecting a first and a second mounting member, defining a pressure receiving chamber undergoing pressure fluctuation during input of vibration; an equilibrium chamber defined by a flexible layer for permitting its volume change; an orifice passage connecting the pressure receiving chamber and equilibrium chamber; a movable member; and a short passage for connecting two chambers with a length smaller than that of the orifice passage. When pressure in the pressure-receiving chamber increases, the movable member is displaced or deformed toward to close the equilibrium-chamber-side opening of the short passage to have the short passage substantially closed, while when pressure in the pressure-receiving chamber decreases, the movable member is displaced or deformed to have the short passage operative.