Patent ID: 8327984

Claim:
A magnetorheological damper assembly comprising; a cylinder extending along an axis for containing a magnetorheological fluid, a piston assembly slideably disposed in said cylinder and extending along said axis and separating said cylinder into a first chamber and a second chamber for sliding and reciprocal movement along said axis, said piston assembly including a piston body extending along said axis between a first end and a second end, said piston assembly defining an MR-fluid passageway extending between said first chamber and said second chamber for passing the magnetorheological fluid therethrough during said movement of said piston assembly, said piston body defining an outer body surface, said outer body surface defining at least one circumferential groove extending annularly thereabout, an electrical coil disposed in said circumferential groove and extending annularly about said piston body for selectively generating a magnetic field across said MR-fluid passageway to change the viscosity of the magnetorheological fluid passing through said MR-fluid passageway to increase or decrease the damping force of the magnetorheological damper assembly, said outer body surface further defining a first primary channel including a first primary channel first portion extending axially from said circumferential groove toward said second end of said piston body and extending radially inwardly to define a first primary channel first portion depth and defining a first portion width extending at least partially circumferentially about said piston body, a first segment of non-magnetic material being disposed in said first primary channel first portion for sealing said first primary channel first portion and for reducing the magnetic field passing across said MR-fluid passageway adjacent said first primary channel first portion, said outer body surface further defining a secondary channel extending from said circumferential groove toward said first end of said piston body to define a secondary channel length and extending radially inwardly to define a secondary channel depth and having a secondary channel width extending at least partially circumferentially about said piston body, said secondary channel extending from said circumferential groove to said first end of said piston body for reducing the magnetic field passing across said MR-fluid passageway adjacent said secondary channel.