| 摘要 |
PURPOSE:To attain a stable flow control, by providing three contoured parts while cylinder chambers in a piston of an actuator and controlling a supply pressure. CONSTITUTION:An actuator 20 of a head cover has a cylinder 21 and a piston 22. The piston 22, which provides in its axial direction a small contoured part 22a, 22c and a large contoured part 22b, divides the cylinder 21 into cylinder chambers 23-25. The actuator 20 supplies a suction pressure to the first cylinder chamber 23, control pressure to the second cylinder chamber 24 and a low pressure to the third cylinder chamber 25. Accordingly, fixed reaction force acts on the piston over the total region of a stroke of the piston, and the responsiveness of a delivery amount control is uniformly obtained.
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