Fluid-filled elastic mount having vacuum-receiving chamber partially defined by elastic member for isolating high-frequency vibrations

A fluid-filled elastic mount for flexibly connecting two members, comprising:

• a first support member and a second support member which are respectively fixed to the two members to be flexibly connected, and which are spaced apart form each other in a load-receiving direction in which vibrations are applied to the elastic mount;
• an elastic body interposed between said first and second support members for elastically connecting the first and second support members;
• said elastic body at least partially defining a pressure-receiving chamber which is filled with a non-compressible fluid, a pressure of said fluid in said pressure-receiving chamber changing due to elastic deformation of said elastic body upon application of the vibrations in said load-receiving direction;
• a first flexible diaphragm partially defining a first equilibrium chamber filled with said non-compressible fluid, said first flexible diaphragm being elastically deformable so as to permit a volumetric change of said first equilibrium chamber to absorb a pressure change of said fluid in said first equilibrium chamber;
• means for defining a first orifice passage which communicates with said pressure-receiving chamber and said first equilibrium chamber so as to permit flow of said fluid therebetween;
• a second flexible diaphragm partially defining a second equilibrium chamber filled with said non-compressible fluid, said second flexible diaphragm being elastically deformable so as to permit a volumetric change of said second equilibrium chamber to absorb a pressure change of said fluid in said second equilibrium chamber;
• a fixed partition plate separating said pressure-receiving chamber and said second equilibrium chamber;
• means for defining a second orifice passage through said fixed partition plate so as to permit flow of said fluid between said pressure-receiving chamber and said second equilibrium chamber, said second orifice passage having a ratio of a cross sectional area thereof to a length thereof, which ratio is higher than that of said first orifice passage;
• a movable elastic restriction member which is opposed to said second flexible diaphragm to at least partially define an air-tight vacuum-receiving chamber, such that said second equilibrium chamber is separated from said vacuum-receiving chamber only by said second flexible diaphragm, said vacuum-receiving chamber permitting elastic deformation of said second flexible diaphragm;
• and
• pressure control means for selectively applying a vacuum pressure to said vacuum-receiving chamber to draw said second flexible diaphragm onto said elastic restriction member, so as to restrict free deformation of said second flexible diaphragm and permit oscillation of the second flexible diaphragm with said elastic restriction member.