Abstract: A valve device comprising a stator 22 having a predetermined number of coils arranged with substantially equal intervals in peripheral directions of a stator core, a rotor having a plurality of permanent magnet magnetic poles 29 at positions corresponding to the coils on an outer peripheral surface of the stator 22, a current carrying means 37 commutating a direct current supplied from a power source through the rotor 28 and applying the current to the coils of the stator 22, a shaft member located in a center of the rotor 28 and being movable in a direction of the shaft in response to rotation of the rotor 28, and a valve member 45 opening and closing by movement of the shaft member 30 for providing excellent responsiveness of valve opening and closing operations.

Abstract: A speed control apparatus includes a plurality of switches disposed between a three phase AC power source and a motor, a low speed control device for feeding power having a frequency lower than the frequency of the power source to the motor under the turn-on control of the switches, and a phase shifting device for shifting the phase order for changing from high speed operation to low speed operation of the motor.