| 摘要 |
The diaphragm of a vacuum booster device is normally placed in intimate contact with the disc portion of the booster piston due to the pressure difference between the first and second working chambers. The diaphragm has through-holes which the tie rods penetrate, and the peripheral portion of each through-hole is resiliently pushed to the disc portion of the booster piston by means of an elastic member. When the booster piston is manually operated while no vacuum pressure is stored in the first working chamber, the air in the first working chamber compressed by the advance of the booster piston is discharged into the second working chamber through the through-hole of the diaphragm, thus insuring smooth manual operation of the booster piston. When vacuum pressure is stored in the first working chamber, the peripheral portion of the through-hole of the diaphragm is resiliently pushed to the disc portion of the booster piston by the elastic member, thereby reliably closing the through-hole of the diaphragm and preventing unnecessary leakage of the vacuum pressure from the first working chamber to the second working chamber.
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