Fluid-filled elastic mount having two differently tuned orifices and

Abstract

A fluid-filled elastic mount including an elastic body interposed between an inner and an outer sleeve, a pressure-receiving chamber disposed between the two sleeves, a first and a second equilibrium chambers partially defined by respective flexible diaphragms for absorbing pressure chambes in the two equilibrium chambers: a first and a second air chamber corresponding to the first and second equilibrium chambers, for permitting elastic deformation of the respective diaphragms; and a first and a second orifice passage for fluid communication between the pressure-receiving and the first and the second equilibrium chambers. The second orifice passage has a ratio of its cross sectional area to its circumferential length, which is higher than that of the first orifice passage. The elastic mount further includes a pressure control device connected to the second air chamber for changing a pressure in the second air chamber. This pressure control device includes a switch device which is operable between a first position for communication of the second air chamber with a first pressure and a second position for communication of the second air chamber with a second pressure higher than the first pressure, so that the fluid flows only through the first orifice passage when the switch device is placed in the first position, and through the second orifice passage when the switch device is placed in the second position.