| 摘要 |
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.
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