| 摘要 |
PURPOSE:To remove the occurrence of slippage of the seat position of a valve and secure airtightness by providing the inside periphery of a valve body, which has a built-in valve mechanism for opening and closing the boundary between a working pressure chamber and a negative pressure/air pressure chamber, with a retainer, and energizing a valve member toward a valve plunger chamber. CONSTITUTION:A pneumatic booster 1 is equipped with a power piston 6, which is supported freely sliding right and left by a housing, and the power piston 6 is driven by the pressure difference between a negative pressure chamber and a working pressure chamber being divided by a diaphragm. The power piston 6 has a valve body 23, which has a built-in valve mechanism 22 controlling the introduction and discharge of the air inside the working chamber, and a piston, which receives the pressure difference between a negative pressure chamber and the working pressure chamber, and has a valve member 57, which seats itself on the seat face 36 provided in the valve body 23. In this case, a valve member 57 is energized in closing direction by the spring 58 one end of which is supported by the retainer 56 having a stepped cylinder 65. |
