| 摘要 |
A pull-type booster includes a hollow body in which a movable wall is movably received to divide an interior thereof into a negative pressure chamber and a pressure-variable chamber. The movable wall has a tubular portion extending outwardly of the body and having an axial internal bore. The tubular portion is disposed in a room or chamber. A tubular cover member is mounted around the tubular portion to cover it and has an inlet in communication with the internal bore. An air tube has one end connected to the inlet, and the other end of the air tube is disposed outside of the room. A valve device is mounted within the internal bore for communicating the inlet with the pressure-variable chamber through the internal bore to introduce the ambient air outside of the room into the pressure-variable chamber via the air tube when the valve device is in a pressure-differential generating position, thereby moving the movable wall relative to the body due to a pressure differential between the negative pressure chamber and the pressure-variable chamber.
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