| 摘要 |
PROBLEM TO BE SOLVED: To widen to the utmost the control range of a minute flow, meanwhile set the flow large at full opening, by changing the flow passage area in the most approached opposed condition between the nearly straight part and multi- stepped slopes and a plurality of throttle parts based on the position of a valve element. SOLUTION: The closed part 17c of a valve element 17 on the most descent position is brought in contact with the bottom part of a valve seat 5 to be in the full closed condition. Under the condition, for example, when a motor 19 such as a pulse motor is rotationally moved by a pulse signal or the like, an output shaft 23 is rotationally moved, and threadedly engaging the thread part 23a of the output shaft 23 with an insert thread 22, a connector 21 is elevated. When the connector 21 is elevated, the valve element 17 is moved upward through a connector shaft 20. Namely, at first a minute flow passage area between the first throttle part of the valve seat 5 and the lower end part position of the vertical part of the valve element is changed to a minute flow passage area part between the first throttle part and the lower end part position of a micro-taper face having long stroke.
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