Fluid-filled power unit mount

Abstract

A power unit mount through which a power unit is supported on a vehicle body in a manner to insulate vibration transmission. The power unit mount is comprised of an elastomeric support body fixedly interposed between inner and outer cylindrical members which are connected respectively to the vehicle body and the power unit. The elastomeric support body is formed with a hollow defining a main fluid chamber. An elastomeric diaphragm is provided to define an auxiliary fluid chamber which is communicable with the main fluid chamber through first and second orifice passages which extend along the inner periphery of the outer cylindrical member. Liquid fills the main and auxiliary fluid chambers and the orifice passages. In the first orifice passages, the resonance point of the liquid is tuned to increase the loss factor of the power unit mount in response to relatively low frequency vibration, thereby dampening engine shake. In the second orifice passage, the resonance point of the liquid is tuned to lower the dynamic spring constant of the power unit mount in response to relatively high frequency vibration, thereby dampening idling vibration of the power unit. Additionally, a movable plate arrangement is disposed in the second orifice passage and adapted to close the orifice passage in response to the relatively low frequency vibration, thereby permitting fluid passage through only the first orifice passage during input of the relatively low frequency vibration.