Fluid filled type vibration damping device

A fluid-filled type vibration-damping device comprising:

• a first mounting member;
• a second mounting member;
• a main rubber elastic body elastically connecting the first and second mounting member;
• a partition member that is supported by the second mounting member;
• a pressure-receiving chamber defined to one side of the partition member, whose wall is defined in part by the main rubber elastic body, giving rise to pressure fluctuations at times of vibration input;
• an equilibrium chamber defined to another side of the partition member and whose wall is defined in part by a flexible film;
• a non-compressible fluid filling the pressure-receiving chamber and the equilibrium chamber;
• a main orifice passage interconnecting the pressure-receiving chamber and the equilibrium chamber;
• at least one intermediate chamber formed in the partition member to be separately from the pressure-receiving chamber and the equilibrium chamber and filled with a non-compressible fluid;
• an input-end moveable plate having restricted deformation, situated at a section of the intermediate chamber opening towards the pressure-receiving chamber, and adapted to undergo displacement in response to pressure from the pressure-receiving chamber directed onto a face on an opposite side from the intermediate chamber so as to transmit pressure from the pressure-receiving chamber to the intermediate chamber and give rise to pressure fluctuations in the intermediate chamber;
• an output-end moveable plate situated at a different section of the intermediate chamber opening toward the equilibrium chamber, and adapted to transmit pressure fluctuations of the intermediate chamber to the equilibrium chamber to dispel pressure fluctuations of the intermediate chamber, and having restricted deformation such that an amount of capacity variability permitted in association with displacement is smaller than that of the input-end moveable plate;
• and
• a sub-orifice passage interconnecting the intermediate chamber and the equilibrium chamber,
• wherein at least one of the input-end moveable plate and the output-end moveable plate is composed of a moveable plate member comprising a rigid constraining plate sheathed with film-like rubber, the constraining plate having irregular shape of varying outside diameter dimension in a circumferential direction and provided with alternating small-diameter portions and large-diameter portions in the circumferential direction;
• sections defining the small-diameter portions of the constraining plate constitute elastic film portions composed of single-layer structure of film-like rubber;
• a plurality of elastic contacting projections that project out to either side in a plate thickness direction are integrally formed in the elastic film portions that have been provided at multiple locations along a circumference of an outside peripheral section of the moveable plate member, the plurality of elastic contacting projections being adapted to come into initial contact with the partition member during displacement of the moveable plate member in the plate thickness direction;
• restraining elastic ribs that connect in the circumferential direction with the plurality of elastic contacting projections and that extend in the circumferential direction through the outside peripheral section of the moveable plate member are integrally formed with the elastic film portions in the large-diameter portions of the constraining plate, with the restraining elastic ribs being adapted to come into contact against the partition member after the elastic contacting projections do during displacement of the moveable plate member in the plate thickness direction;
• and
• inward-extending ribs that extend diametrically inward on the large-diameter portions of the constraining plate are formed at multiple locations along a circumference of the restraining elastic ribs, with the inward-extending ribs adapted to also come into contact against the partition member during displacement of the moveable plate member in the plate thickness direction.