A novel angle sensitive rotary magnetorheological damper

Abstract Traditional shear type rotary magnetorheological (MR) dampers have a constant working gap in the activation zone, and the damping force output is only controlled by the excitation current. By combining with closed-loop control algorithms and devices, variable damping force output can be achieved. However, this closed-loop control system is complex and requires additional control equipment. If the control system fails, it is impossible to achieve the output of damping force changes, which is unacceptable in some extremely high reliability, low-cost, and narrow space working conditions. In order to achieve variable damping force output of the rotary MR damper throughout the full piston stroke under constant excitation current, a novel variable positional damping rotary MR damper (VPD-RMRD) is proposed in this study. By presetting the size of the activation gap between the piston and cylinder at different angular positions, it is possible to achieve damping force variation output throughout the entire piston stroke without the need for additional control devices. This variable damping output method only requires a constant excitation current. The prototype of VPD-RMRD has been manufactured and subjected to performance testing. In order to verify the feasibility of applying VPD-RMRD to vibration reduction, this study applied it to the seat suspension system. The experimental results show that the maximum reduction in acceleration transmission rate is more than 20%. The proposal of VPD-RMRD provides a new solution for vibration reduction in narrow spaces, high reliability, and low-cost operating conditions.