Design and development of a wedge shaped magnetorheological clutch

This paper presents a novel drum magnetorheological clutch design having a wedge shaped boundary. The converging film formed due to the direction of motion of the magnetorheological clutch and the inclination of the wedge planes helps to produce the pressure generating mechanism in the magnetorheological grease film. The resistance force developed due to this mechanism in the proposed case exceeds that of the conventional drum clutch. The proposed wedge shaped drum magnetorheological clutch consists of bimetallic discs made up of aluminium and mild steel. Mild steel disc has a certain number of inclined sliders shaped like a wedge at its boundary, which is immersed in the magnetorheological grease. The yield stress of the magnetorheological grease varies as a function of the magnetic field created by electric current passing through the electromagnet. Bingham model has been employed in the present study to analyse theoretically the torque generated by wedge-shaped drum magnetorheological clutch. The proposed magnetorheological drum clutch with wedge shaped boundary and conventional drum clutch have been designed and fabricated with similar material parameters and magnetic circuits. The experiment has been performed for the different current values (0 A, 0.25 A and 0.52 A). Torque results are plotted and compared for both cases. Experimental results suggest that the proposed wedge shaped drum magnetorheological clutch produces more torque than the conventional drum magnetorheological clutch, and thus it has better performance.