| 摘要 |
PCT No. PCT/EP85/00332 Sec. 371 Date Mar. 6, 1986 Sec. 102(e) Date Mar. 6, 1986 PCT Filed Jul. 6, 1985 PCT Pub. No. WO86/00671 PCT Pub. Date Jan. 30, 1986.A regulatable vane pump is provided with a piston operable by differential pressure responsive to booster steering flow demand wherein the piston movement controls a choke bore flow area. The differential pressure is effected by pump pressure on one face of the piston and consumer pressure on the opposite face of the piston, e.g., pressure in a booster steering servomotor. The choke bore has an aperture covered or uncovered by a choke plate carried by a pin on the piston. The choke plate is normally in position so as not to impede flow through the choke and the piston is in a position such that pump outlet flow is blocked from a bypass passage back to the pump inlet. However, with rise in vehicle speed under non-steering conditions, causing pressure on the one face of the piston to shift it along with the choke plate, the choke bore is closed, or partially so, and the unnecessary output pressure flow shunted back to pump inlet. Under steering conditions the back pressure on the opposite face of the piston reverses the piston to open the choke bore, all dependent on vehicle speed and rapidity of the steering operation.
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