| 摘要 |
A traditional continuously-variable vane pump is subject to a significant energy loss as its displacement is controlled by the output pressure of the pump rather than the changing requirements of the lubrication system A vane pump (20) is provided which has an output pressure hat can be selected from a continuous range of pressures, independent of the operating speed of the pump The pump has first (68) and second (72) control chambers which create opposed forces on the pump control ring (40) to selectively move the pump control ring (40) between maximum displacement and minimum displacement positions. In one embodiment, the control chamber (68) which urges the pump control ring to the minimum displacement position is continually supplied with pressurized working fluid during operation of the pump while the control chamber (72) which urges the pump control ring to the maximum displacement position can selectively be supplied with pressurized working fluid, isolated, or can be relieved of pressurized working fluid to alter the displacement of the pump |
