Patent ID: 7828126

Claim:
A magnetorheological (MR) piston ( 12 ) comprising: a) first and second MR piston end plates ( 36 and 38 ) having corresponding first and second orifices ( 44 and 46 ); b) an MR piston core ( 40 ) having a central longitudinal axis ( 16 ) and disposed longitudinally between and attached to the first and second MR piston end plates ( 36 and 38 ); c) an MR piston ring ( 42 ) attached to the first and second MR piston end plates ( 36 and 38 ) and radially spaced apart from the MR piston core ( 40 ) creating a gap ( 48 ) therebetween, wherein the gap ( 48 ) is in fluid communication with the first and second orifices ( 44 and 46 ) to overall define an MR passageway ( 22 ); d) a main electric coil ( 24 ) disposed in the MR piston core ( 40 ) to magnetically energize the gap ( 48 ) of the MR passageway ( 22 ); and e) an electromagnetic valve ( 26 ) operatively connected to the MR passageway ( 22 ), wherein the electromagnetic valve ( 26 ) has an electromagnetic-valve coil ( 32 ), a spring-loaded restrictor plate ( 50 ), a first state which magnetically attracts the spring-loaded restrictor plate ( 50 ) toward the electromagnetic-valve coil ( 32 ) when the electromagnetic-valve coil ( 32 ) is electrically activated, and a second state which releases the magnetically-attracted spring-loaded restrictor plate ( 50 ) to partially, but not completely, restrict the MR passageway ( 22 ) when the electromagnetic-valve coil ( 32 ) is not electrically activated.