| 摘要 |
PURPOSE:To enable the discharge capacity to be varied by providing a plurality of pistons engaging a notch of the vane side end face to chuck the vane in a pump housing without raising the temperature of discharged gas. CONSTITUTION:When intake pressure is reduced to extend a bellows 40 and open a valve 38, then pressure in a chamber 37 is reduced to move downward a control piston 28 so that a communicating hole 33 is opened to a discharging chamber 16 and discharging pressure is supplied to a chamber 20 through the communicating hole 33, an annular groove 22 and a communicating hole 21. Also, a piston 17 is slided toward a vane 6 by the discharging pressure and the rod 17a engages a notch 6a formed on the side end face of the vane 6 to chuck the vane 6. Thus, the spring-out of the vane 6 can be regulated to reduce discharge capacity.
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