| 摘要 |
PROBLEM TO BE SOLVED: To easily make inconspicuous the noise generated from a vacuum pump. SOLUTION: In the vacuum pump, the output shaft of an engine is connected to a pump drive means through a camshaft to match the phase of engine combustion noise with the phase of noise by intake air or exhaust gas. The four-cylinder engine C is so formed that its piston is positioned at a top dead center at the times of a, b, c, d, and e. The noise A near the engine becomes large at these positions. The exhaust noise from an exhaust valve and noise resulting from the exhaust noise are buried in noise during the combustion of the engine by synchronizing the phase of the noise from the engine with the phase of the noise generated by the opening of the exhaust valve of the vacuum pump. COPYRIGHT: (C)2006,JPO&NCIPI
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