Patent ID: 6311964
Filing Date: 2001-11-06
Classification: F16F

Abstract:
A fluid-filled vibration damping device comprising:a first mounting member and a second mounting member including a cylindrical portion, which are spaced apart from each other such that one of axially opposite open end of said cylindrical portion of said second mounting member is opposed to said first mounting member;an elastic body elastically connecting said first and second mounting member such that said open end of said cylindrical portion of said second mounting member is fluid-tightly closed by said elastic body;a flexible diaphragm fluid-tightly closing the other open end of said cylindrical portion of said second mounting member;a partition member having a generally cylindrical shape, which is disposed between said elastic body and said flexible diaphragm and fixedly supported by said second mounting member, said partition member cooperating with said elastic body to define therebetween a pressure-receiving chamber filled with a non-compressible fluid, to which a vibrational load is applied, and cooperating with said flexible diaphragm to define therebetween an equilibrium chamber filled with the non-compressible fluid, the volume of which is variable;a first orifice passage formed in said partition member for fluid communication between said pressure-receiving chamber and said equilibrium chamber;a second orifice passage formed in said partition member and communicating at a first open end thereof with said pressure-receiving chamber and at a second open end thereof with said equilibrium chamber for fluid communication between said pressure-receiving chamber and said equilibrium, said second orifice passage being tuned to a frequency band higher than a frequency band to which the first orifice passage is tuned,said second orifice passage including a pair of split passages formed at respective circumferential positions of said partition member that are opposed to each other in a diametric direction of said partition member, and each extending in a circumferential direction of said partition member with a circumferential length substantially equal to a value corresponding to a half of an entire circumference of said partition member, said pair of said split passages being open at ones of opposite circumferential ends thereof to said pressure-receiving chamber through said first open end of said second orifice passage, and being joined together at the other circumferential ends at a first circumferential position of said partition member and radially inwardly extend from said first circumferential position to a substantially central portion of said partition member at which the other circumferential ends of said split passages are open to said equilibrium chamber through said second open end of said second orifice passage;a pair of movable members respectively disposed in diametrically-opposite radially intermediate portions of said partition member so as to extend between said respective split passages and said second open end of said second orifice passage, each of said pair of movable members being displaceable by a suitable amount of distance, based on a pressure difference between a pressure of the fluid in said pressure-receiving chamber which is applied to one of opposite surfaces of said movable member, and a pressure of the fluid in said equilibrium chamber which is applied to the other surface of said movable member; andan actuator disposed on one of opposite sides of said flexible diaphragm remote from said equilibrium chamber and being operable to displace said flexible diaphragm in a direction toward and away from said second open end of said second orifice passage formed in said partition member, so as to close and open said second open end of said second orifice passage, for inhibiting and permitting said fluid communication through said second orifice passage.