Abstract: A vertical spring return valve actuator includes a motor, a first worm gear and a second worm gear driving a sun gear of a planetary gear unit. The sun gear and planetary gears are rotated in a state where a ring gear is fixed by a brake unit during time of a normal operation. Also, a spring shaft, which is coupled to an output shaft of a planetary gear carrier operated cooperatively with the planetary gears , is rotated to permit a valve to be closed. At the time of a blackout, the brake unit is released, so that a spiral spring is unwound to permit the valve to be opened. Further, the valve is opened or closed manually through a valve manual opening and closing unit having a rotation member, a variable worm and a steering wheel.

Abstract: A spring return valve comprising a motor, a first worm member, a second planetary gear member, a second worm member, an elastic member, and a valve attached to said second worm wheel is provided. Since the first and the second planetary gear are installed between the first worm shaft and the second worm shaft and the elastic member is fitted onto the second worm shaft, the load applied on the output shaft can be reduced a lot, the opening and/or closing operation is very easy even if the elastic coefficient is small, thereby the reduction in size is possible.

Abstract: The present invention relates to a vertical spring return valve actuator wherein at the time of a normal operation, a first worm gear 110 and a second worm gear 120 are operated by means of the activation of a motor 115, and the operation of the second worm gear allows a sun gear 131 of a planetary gear unit 130 to be operated. The sun gear and planetary gears 133 are rotated in a state where a ring gear 135 is fixed by means of a brake unit 160. Also, a spring shaft 151, which is coupled to an output shaft 141 of a planetary gear carrier 142 operated cooperatively with the planetary gears 133 of the planetary gear unit 130, is rotated to permit a valve to be closed. On the other hand, at the time of emergency like a blackout, the brake unit is released, so that a spiral spring 55 is unwound to permit the valve to be opened. Further, even during the blackout, the valve is opened or closed manually through a valve manual opening and closing unit 170 having a variable worm 172 and a steering wheel 177.