Vibration damping device with an electrode and having rolling lobes of

Abstract

A vibration damping device includes axially spaced first and second end members adapted to be mounted on spaced apart structures. An intermediate member is mounted within an open end of the second end member. A center member consisting of a rigid tube having a hollow bore and a lower piston is connected to the first end member and extends through the interior of the intermediate member. The tube forms an annular orifice which extends about a rigid electrode rod which extends through the rigid tube and which is also connected to the first end member and piston but electrically isolated therefrom. A pair of elastomeric sleeves extend between the intermediate member and first end member and between the intermediate member and the piston to form a pair of fluid chambers communicating with the orifice and adapted to contain an electrorheological fluid. Each of the sleeves has a rolling lobe with circular centers and different radii of curvature. However, the circular centers of the rolling lobes lie on a common imaginary axially extending cylinder whereby the effective areas of the fluid chambers remain substantially equal as the device moves between jounce and rebound positions to reduce the spring rate effect on the damper. Even though the rolling lobes have the same circular centers the radii of the lobe forming walls are different which enables nesting of the piston within the intermediate member to reduce the axial height of the device without affecting its stroke length.