| 摘要 |
PURPOSE: To reduce stress generated on a diaphragm so as to extend the service life thereof by supporting at least most of the diaphragm working area between fluid compression and induction in a piston device. CONSTITUTION: A peripheral portion 4a of a piston head 4 extends to and engages with a peripheral portion 8a of a diaphragm 8 to reduce the volune of a vacuum chamber 3 when a piston 1 descends from the TDC (Top-Dead- Center) position. The oil stored in the vacuum chamber 3 is pressed out and returned to an oil tank 13 via an oil bore 31 and a non-return valve 30. When the piston head descends, the pressure in a liquid chamber 20 is increased and the engaged portion of the peripheral portion 8a of the diaphragm and the peripheral portion 4a of the piston head 4 expands simultaneously. The diaphragm 8 approaches a wall surface 23 of the liquid chamber 20 and compressed liquid is discharged through an outlet valve 25. Thus, the portion of the diaphragm that is not supported is reduced during the working period of the piston, therefore, the total stress on the diaphragm is reduced. |
