Development of a Passive Magnetorheological Fluid Clutch With Field-Blocking Mechanism

This paper introduces a new torque variation mechanism for a magnetorheological fluid (MRF) clutch which uses permanent magnets. Previous prototypes of this clutch changed the position of the permanent magnets in and out of the clutch to vary the transmitted torque. The new design uses a field-blocking mechanism, a steel cylinder which covers the magnets, to vary the transmitted torque. The steel cylinder moves in and out the clutch, covering the magnets, and thus alter the intensity of the magnetic field the MRF experiences. Magnetostatic simulations of the magnetic field behavior inside the clutch and fluid dynamic simulations were carried out with the objective of finding the torque transmission capability. A mathematical model was also used for this purpose, where the magnetostatic simulation results were used to estimate the transmitted torque at several clutch configurations. Finally, several experimental measurements were carried out to determine the real behavior of the clutch and compare and verify the simulations and mathematical model results.