Hydraulically damped elastic engine mount

Claim 1

A resilient mounting device having hydraulic damping for vibrationally damping a motor vehicle engine, said mounting device having a longitudinal axis along which damping is prevalent, said mounting device having opposite first and second rigid end portions with mounting means thereat, said end portions being at either end of said longitudinal axis; an elastic connecting element resiliently connecting said first and second end portions and forming with them a cavity for two chambers in controllable fluid communication, each with the other, said two chambers for containing damping fluid, and being disposed one adjacent the other along said longitudinal axis; a first of said two chambers being a compression chamber defined in part by said first rigid end portion which is sealed for permitting a build-up of pressures substantially above and below ambient pressure about said mounting device; a second of said two chambers being an unpressurized equalization chamber defined in part by a bellows means wherein said bellows means further defines in combination with the second rigid end portion, a third chamber, said second rigid end portion defining therein airflow evacuation openings for substantially equalizing pressure in said second of said two chambers with said ambient pressure about said mounting device; said two chambers being separated by circular partition means, said partition means having a circular outer flexible peripheral portion and a circular rigid inner portion, said rigid inner portion being disposed within said outer peripheral portion of said partition means, said outer peripheral portion comprising a flexible suspension element for holding said rigid inner portion elastically suspended between and movable within said two chambers and damping a first type of pressure differences between said two chambers; said rigid inner portion having a central axis, which is generally perpendicular to said longitudinal axis defined therethrough, and having a continuous channel connecting said first and said second chambers, said channel following a circular route having a predetermined length, being radially displaced from and about said central axis in said rigid inner portion; said partition means having valve means which are normally biased in a closed position to keep said valve means closed when a pressure difference between said first chamber and said secod chamber is below a first predetermined pressure differential and to keep said valve means in a closed position when a pressure difference between said second chamber and said first chamber is below a first predetermined pressure differential, said valve means being disposed in said partition means and moving therewith for opening and relieving a pressure between said chambers in a range of pressures greater than said predetermined pressure differentials, thereby minimizing cavitation and pressure peaks substantially above said ambient pressure in said damping fluid in said first chamber.