Design Analysis in Frictional Fan Clutch Driven by SMA Spring

Abstract

This paper presents a fan clutch driven by SMA spring actuator. Based on shape memory effect of SMA, the operational principle of the fan clutch driven by SMA is introduced. The equation of the output displacement of SMA actuator in free stroke is derived. The normal pressure between driving and driven discs of the clutch generated by SMA actuators is analyzed to compute the torque transmission ability in the disc-type fan clutch. The characteristic of transmission torque is studied in detail. The results indicate that the change of temperatures has a tremendous influence on the normal pressure between driving and driven discs of the fan clutch, and the transmission torque of the fan clutch changes rapidly according to the temperatures of airflow from radiator.