Patent ID: 8286763

Claim:
A magnetorheological (MR) piston assembly comprising; a piston core of ferromagnetic material including a main core of cylindrical shape extending along a central longitudinal axis from a first longitudinal end to a second longitudinal end said piston core including an outer circumferential surface and a first slot side and a second slot side defining a circumferential slot circumscribing said outer circumferential surface of said piston core and having an open top open to said outer circumferential surface and a closed bottom spaced from said open top by said first and second slot sides, an electric coil disposed in said circumferential slot for magnetically influencing said piston core, and characterized by said slot sides of said piston core extending radially inwardly at a constant angle from a narrow longitudinal length at said open top to a maximum longitudinal length greater than said narrow longitudinal length at said closed bottom to define a trapezoidal cross-section of said circumferential slot for maximizing magnetic influence of said electric coil on said piston core, and said peripheral core including a first peripheral core disposed about said main core and extending from said first longitudinal end to said first slot side and a second peripheral core disposed about said main core and extending from said second longitudinal end to said second slot side.