Rotation device for use on compressor of vehicle air conditioning system, has screw engaging section comprising male and female threads at respective shaft part and pulley, where surfaces of threads have zinc-nickel alloy coating

摘要

The device has a belt pulley (100) rotated by a drive source (8) i.e. motor, and a shaft part (403) screwed with the belt pulley and integrally rotated with the belt pulley. A screw engaging section (402) of the belt pulley and shaft part is formed with a thread so that a tightening torque is advanced when a drive force of the drive source acts on the belt pulley. The screw engaging section has male and female threads formed at the respective shaft part and belt pulley. Surfaces of the male and/or female threads are provided with a zinc-nickel alloy coating.