Patent ID: 8807545

Claim:
A liquid-sealed antivibration device comprising: a first mounting part to be mounted on one of a vibration source side and a support side; a second mounting part to be mounted on the other of the vibration source side and the support side; an antivibration base body formed of an elastomer which is interposed between the first mounting part and the second mounting part; a main liquid chamber whose chamber wall is partially formed of the antivibration base body and in which a liquid is sealed; a first sub liquid chamber whose chamber wall is partially formed of a first diaphragm formed of an elastomer and in which a liquid is sealed; a partition element which partitions the main liquid chamber and the first sub liquid chamber; and a first orifice flow passage which connects the main liquid chamber with the first sub liquid chamber, wherein the partition element comprises: a second diaphragm which is formed of an elastomer and includes an outer peripheral portion which is liquid-tightly held by the partition element and a flexible membrane portion which is arranged inside the outer peripheral portion; a second sub liquid chamber which is divided from the main liquid chamber by way of the second diaphragm; a second orifice flow passage which connects the first sub liquid chamber and the second sub liquid chamber to each other while being tuned to a frequency range higher than a frequency range to which the first orifice flow passage is tuned; and a counter wall which faces a membrane surface of the flexible membrane portion on a main liquid chamber side in an opposed manner with a space defined therebetween on a main liquid chamber side of the second diaphragm, and in the flexible membrane portion, a valve portion which is brought into contact with a partition element wall surface around an opening of the second orifice flow passage and closes the opening while surrounding the opening is formed into a surrounding wall shape such that the valve portion is raised from the membrane surface of the flexible membrane portion, a space surrounded by the valve portion inside the valve portion having the surrounding wall shape forms the second sub liquid chamber, a through hole is formed in the flexible membrane portion outside the valve portion, and a projection which is brought into pressure contact with the counter wall is formed on the membrane surface of the flexible membrane portion on a main liquid chamber side, and the valve portion and the projection are held in a compressed state between the partition element wall surface around the opening and the counter wall, and further wherein the valve portion is configured to be in contact with the partition element well surface in a non-flexural state, and is configured to be moved away from the partition element wall surface by flexural deformation of the second diaphragm when a flow rate of the second orifice flow passage becomes a predetermined amount or more.