Magnetorheological fluid damper with optimum damping

The present invention relates generally to damping devices used in controlled damping applications such as semi-active vehicle suspension systems. More particularly, the present invention relates to high performance controlled damping devices using magnetorheological (MR) fluid. An improved magnetorheological fluid damper is provided which more closely approximates ideal performance requirements including increased turn-up ratio and stiction free performance near zero velocity for realistic automotive applications. The MR damper includes a magnetic flux leakage reduction device positioned at each end of the magnetic damper piston assembly to create a magnetic flux isolation barrier causing magnetic flux to extend through an annular flow gap thereby minimizing flux leakage into other areas such as a piston rod and associated hollow tube. The magnetic flux leakage reduction devices are formed of a non-magnetic material and completely cover a respective adjacent axial face of a piston core. A laminar flow enhancing feature is also provided for enhancing laminar flow and minimizing turbulence in the annular flow gap thereby advantageously reducing the off-state force and increasing the turn-up ratio.