| 摘要 |
A vacuum pump has a bulb whose wall is composed of elastic material and has a first protuberance projecting into the interior of the bulb and a second protuberance projecting outwardly of the bulb. The first protuberance has an air intake passageway for communicating with a chamber that is to be evacuated and the second protuberance has an air exhaust passageway communicating with the interior of the bulb. Each of the protuberances has a slit that is pressed closed by the inherent elasticity of the protuberance material so they serve as check valves. When the bulb is squeezed air pressure developed in the bulb acts on the interior air intake protuberance to close its slit and the slit in the exterior air exhaust protuberance is forced open to exhaust air from the bulb. When the squeezed bulb is relieved the elastic bulb expands to create negative pressure in the bulb which closes the exhaust slit and opens the air intake slit.
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