| 摘要 |
A control system is adapted to operate a fluid load (11) by output of a variable delivery pump (10) having a control cylinder (12) governed by flow and pressure responsive means for regulating the displacement of the pump (10). A flow control valve (13) has input and output ports (16, 17) connected respectively to the pump (10) and load (11) and by cooperation of a spool (33), subject at one end to pump pressure via pilot passage (44) and at the other end to a biasing force provided by a spring (34), with orifices (42, 43) provides a pump discharge flow that is inversely proportional to pump discharge pressure. A load sense control valve (14) has a spring biased spool (48) subject at one end to load pressure over a first pilot line (24) and subject at its other end to pump pressure over a second pilot line (23). A land (55) on the spool (48) determines the connection of the control cylinder (12) either to pump pressure at port (53) for regulating the delivery of the pump or to atmosphere at port (56) for relieving the regulation. By this means the pump displacement is adjusted to maintain substantially constant horsepower output under variable load conditions whereby the load (11) can utilize substantially constant horsepower approaching a prime mover input torque curve without requiring mechanical feedback indicative of the displacement of the pump (10). |
