Fluid-filled type vibration damping device

A fluid-filled type vibration damping device comprising:

• a first mounting member;
• a second mounting member having a cylinder portion;
• a main rubber elastic body elastically connecting the first and second mounting members;
• a partition member supported by the second mounting member;
• a pressure-receiving chamber whose wall is partially defined by the main rubber elastic body;
• an equilibrium chamber whose wall is partially defined by a flexible film, the pressure-receiving chamber and the equilibrium chamber being disposed on either side of the partition member and filled with a non-compressible fluid;
• a first orifice passage and a second orifice passage interconnecting the pressure-receiving chamber and the equilibrium chamber, with the second orifice passage being tuned to a higher frequency than the first orifice passage;
• and
• an elastic movable member attached to the partition member,
• wherein a clasped portion clasped by the partition member is provided to the elastic movable member, and a switching portion is provided to an outer peripheral side of the clasped portion and positioned in a fluid flow path of the second orifice passage, while fluid pressure of the pressure-receiving chamber is exerted on one side of the switching portion and fluid pressure of the equilibrium chamber is exerted on another side of the switching portion,
• wherein an abutting portion is provided to the switching portion so as to project to opposite sides as viewed in a lengthwise direction of the second orifice passage, wherein a thin portion is provided between the clasped portion and the switching portion so that a tilting motion of the switching portion is permitted relative to the clasped portion through elastic deformation of the thin portion,
• wherein a switching mechanism is constituted for opening the second orifice passage through a gap formed between an outside peripheral face of the switching portion and an inside face of the second orifice passage while closing the second orifice passage by the tilting motion of the switching portion around the thin portion relative to the clasped portion based on relative pressure fluctuations of the pressure-receiving chamber and the equilibrium chamber so that an outside peripheral face of the abutting portion of the switching portion comes into abutment against the inside face of the second orifice passage, and wherein a valve portion is integrally formed on an inner peripheral side of the clasped portion, wherein a short-circuit passage is formed in the partition member for interconnecting the pressure-receiving chamber and the equilibrium chamber, and the valve portion is disposed on the short-circuit passage, and wherein a relief mechanism is constituted for closing the short-circuit passage by an abutment of an inside peripheral face of the valve portion against an inside face of the short-circuit passage while permitting fluid flow through the short-circuit passage between the pressure-receiving chamber and the equilibrium chamber by elastic deformation of the valve portion so as to be spaced away from the inside face of the short-circuit passage due to negative pressure of the pressure-receiving chamber acting on the valve portion.