Hydraulic engine mount with air bladder tuning

Abstract

A hydraulic mount assembly is disclosed having expandable primary and secondary fluid chambers, an orifice track for damping action and a damping decoupler. During low level dynamic loading of the mount, hydraulic pressure activates the decoupler. At higher level loading, fluid passes through the orifice track between the two chambers providing the damping action. An expandable pneumatic bladder is mounted within the primary chamber. A control system including two one-way valves governs ingress and egress of outside air to the pneumatic bladder, thereby selectively reducing the overall damping and dynamic rate characteristics in response to sensed vehicle operating conditions. This reduction is accomplished by allowing the bladder to inflate with air providing a relatively soft, engine isolating mount. Alternatively, the control system allows controlled bladder deflation, selectively returning the mount to relatively hard characteristics. The inflation or deflation of the bladder is accomplished by the pumping action of the fluid within the hydraulic mount itself. The pressure within the bladder is maintained at a level below a maximum limit thereby assuring that the bladder does not over inflate, causing the mount to return to relatively hard characteristics.