| 摘要 |
PURPOSE:To reduce overshoot in control, by providing a path which communicates a piston upper part room with a main value opening, and closing a main valve before pressure on a secondary side rises excessively, in a pilot type reducing valve. CONSTITUTION:A piston ring 25 is fitted in a groove after forming the groove on the peripheral wall of a piston 20, and it is housed slidably freely in a cylinder 22. The upper end of a piston bar 23 is connected to the lower plane of a movable wall 27 with a hemispherical plane 70, and the lower end is abutted with the main valve 18 in the value opening 14. The path 72 is provided from the upper plane to the lower plane of the movable wall 27 centering the axis of the piston bar 23, and a side opening 74 is opened at the side plane of the piston bar 23, then, it is communicated wit the path 72. When a flow rate passing the main valve opening 14 increases and the pressure on the secondary side starts to rise, the pressure is decreased because flow velocity is increased, and a fluid body on the upper part of the piston is sucked to the main valve opening via the path 72, thereby, the pressure is decreased further. In such a way, the main valve is operated so as to be closed before the main valve is opened excessively and the pressure is increased excessively.
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