| 摘要 |
PROBLEM TO BE SOLVED: To stabilize output of a negative pressure booster by avoiding reduction in supplied negative pressure to the negative pressure booster even if negative pressure of a negative pressure source reduces in a negative pressure supply device to the negative pressure booster provided with a first one-way valve arranged in a first negative pressure passage between the negative pressure booster and the negative pressure source and allowing air flow to the negative pressure source side, a surge tank arranged in a second negative pressure passage between the negative pressure booster and the negative pressure source and a second one-way valve being arranged in the second negative pressure passage between the surge tank an the negative pressure booster and allowing a flow of air to the surge tank side. SOLUTION: A third one-way valve 14 for allowing a flow of air to the negative pressure source 7 side is arranged in a second negative pressure passage 9 between the surge tank 11 and the negative pressure source 7. An opening-closing valve 13 connected in series to a second one-way valve 12 is arranged in the second negative pressure passage 9 between the surge tank 11 and the negative pressure booster 3. The opening-closing valve 13 is opened by a control unit 16 when detected negative pressure by a negative pressure detector 17 for detecting negative pressure in the negative pressure booster 3 is lower than a preset negative pressure. |
