Fluid filled type vibration damping device

A fluid filled type vibration damping device comprising:

• a first mounting member;
• a second mounting member of tubular shape, the first mounting member being disposed on a side of one opening of the second mounting member;
• a main rubber elastic body elastically connecting the first mounting member and the second mounting member;
• a flexible film by which an other opening of the second mounting member is sealed off fluid-tightly, thereby forming between opposing faces of the main rubber elastic body and the flexible film a fluid chamber in which a non-compressible fluid is sealed;
• a partition member supported by the second mounting member, with the fluid chamber divided by the partition member into a primary fluid chamber whose wall is partially defined by the main rubber elastic body and an auxiliary fluid chamber whose wall is partially defined by the flexible film, and with an orifice passage connecting the primary fluid chamber and the auxiliary fluid chamber being formed;
• an elastic rubber film being disposed to partially define the primary fluid chamber disposed on one side thereof;
• and
• a pressure operating chamber having an attraction face being disposed on an opposite side from the primary fluid chamber with the elastic rubber film interposed therebetween, the pressure operating chamber being arranged to be applied with a negative pressure in order to deform and attract the elastic rubber film onto the attraction face of the pressure operating chamber, wherein:
• the elastic rubber film has a dome shape being convex with respect to a primary fluid chamber side, and the attraction face of the pressure operating chamber has an inverted dome shape being concave with respect to the primary fluid chamber side,
• the attraction face is formed with a plurality of negative pressure suction grooves including an outer circumferential groove extending in a circumferential direction at an outer peripheral portion of the attraction face and opening to the pressure operating chamber,
• a negative pressure suction bore for introducing the negative pressure to the pressure operating chamber is connected to the plurality of negative pressure suction grooves,
• the plurality of negative pressure suction grooves include a diametric groove extending continuously in a diametric direction of the attraction face and opening to the pressure operating chamber, while connecting at both ends to the outer circumferential groove,
• the negative pressure suction bore opens to a connecting portion of the outer circumferential groove and the diametric groove,
• the diametric groove has a depthwise dimension that gradually increases from a longitudinally intermediate portion thereof toward the negative pressure suction bore,
• the diametric groove has an enlarged width portion in which a groove width dimension is gradually increased toward the negative pressure suction bore, and
• the elastic rubber film includes a plurality of thick walled reinforcing ribs each extending radially from an outer peripheral portion of the elastic rubber film with a radial length not enough to reach a central portion of the elastic rubber film, while being disposed so as to be spaced away from one another in the circumferential direction so that thin walled portions of thin rubber elastic body are formed between circumferentially adjacent ones of the reinforcing ribs, and a central curved portion having a wall thickness thinner than the reinforcing ribs, the central curved portion having an inverted dome shape projecting toward the pressure operating chamber, wherein the central curved portion is formed in the central portion of the elastic rubber film, and wherein the central curved portion is surrounded by radially inner ends of the plurality of the reinforcing ribs.