Electrically controlled viscous elastic spring

DETAILED DESCRIPTION The present invention is directed to a spring which uses a fluid, such as electrorheological fluid or magnetic fluid, to provide control of spring characteristics such as spring rate and load-carrying capacity.
The spring is connectable between relatively movable parts to resist movement between the parts and to urge the parts to an initial, equilibrium position when the parts are moved therefrom.
The spring includes at least one sealed fluid chamber filled with electrorheological fluid or magnetic fluid.
An electrorheological fluid is a two-phase material in which its resistance to flow varies as a function of an electric field applied to the fluid.
A magnetic fluid is a two-phase material in which its resistance to flow varies as a function of a magnetic field applied to the fluid.
By controlling the resistance to flow of the fluid in the sealed fluid chamber, spring characteristics can be varied.
In accordance with one feature of the present invention, the spring includes a plurality of sealed fluid chambers with electrorheological fluid or magnetic fluid disposed therein.
The plurality of sealed fluid chambers is at least partially defined by an associated elastomeric member.
The spring further includes means for independently controlling the resistance to flow of the fluid within each of the plurality of sealed fluid chambers.
The means for independently controlling the resistance to flow of the fluid includes electrode means disposed within each of the plurality of sealed fluid chambers.
The electrode means within each of the plurality of sealed fluid chambers provides an energy field which acts on the fluid when the electrode means is connected to an electrical energy source.
The resistance to flow of the fluid varies as a function of the magnitude of the energy field acting on the fluid.
When the resistance to flow of the fluid varies, the spring characteristics vary.
In accordance with another feature of the present invention, a sealed fluid chamber containing electrorheological fluid or magnetic fluid is defined by a yieldable wall which enables the chamber to change in shape as the parts between which the spring acts move relatively