| 摘要 |
<p>A vehicle engine has an air intake providing a manifold vacuum P2, a throttle 3 and an ambient air supply 4. Instead of a vacuum pump, a passive vacuum booster system is provided to supply the vacuum reservoir 6. In this system a piston pump 10 is operated by the differential pressure between the manifold vacuum P2 and ambient P1, in order to produce a higher vacuum P3 in the reservoir 6. To this end the booster pump has large and small chambers 12, 14 with a common piston arrangement 13, 15. The smaller chamber 14 empties the reservoir 6 via an arrangement of check valves 32, 34, and the piston reciprocates under the control of a valve arrangement 20, possibly with additional electronic control.</p> |
