Splined vibration damping device using er fluids

Abstract

A vibration damping device for mounting between two spaced portions of a vehicle. An inner metal cylindrical housing forms an internal piston chamber and is connected at one end to the vehicle, with a piston which is slidably mounted within the piston chamber, being connected to another portion of the vehicle. An outer housing surrounds a portion of the inner housing and forms a fluid duct or flow channel between fluid chambers formed on opposite sides of the piston. An electrode is mounted in the fluid duct for applying a voltage across the duct to affect the viscosity of an electrorheological (ER) fluid flowing therethrough to increase the damping force of the device. The electrode includes a plurality of circumferentially spaced splines and intervening grooves extending longitudinally along the fluid duct. The bottom portions of the grooves have a decreased electric field applied thereto than do the splines, providing bleed grooves or leak paths for the ER fluid to decrease the shear-rate of the fluid. The inner housing has elongated projections which extend into the grooves of the electrode to provide a more uniform electric field along the fluid duct to control the amount of leakage through the bleed grooves. A secondary electrode ground may be formed in the grooves to control the electric field in the bleed grooves.