ACTUATOR FOR VALVE

PROBLEM TO BE SOLVED: To provide an actuator for a valve having both a mechanism of automatically opening or closing the valve when cutting off current, and a manual operation mechanism of the valve. SOLUTION: A driving gear 3 rotating by driving of a motor 2 is installed integrally rotatably with a sun gear 5 on the outer periphery of an output shaft 1 connected to a rotary shaft of a valve element of the valve. A plurality of planetary gears 6 and an internal gear 7 are arranged around a sun gear 5. A plate 14 is arranged to be connected to a collar part 1c of the output shaft 1 by a connecting shaft 16 penetrating through the planetary gears 6, Three of this plate 14, the sun gear 5 and the internal gear 7 are formed as an input member for rotating the output shaft 1 via revolution of the planetary gears 6. Among its members, the plate 14 is used for opening and closing the valve when cutting off the current, and the sun gear 5 is used for opening and closing the valve in ordinary use, and the valve is opened and closed thereby by manually rotating the internal gear 7 in the state of nonrotatably holding the sun gear 5. COPYRIGHT: (C)2010,JPO&INPIT