CAPACITY CONTROLLER FOR VARIABLE CAPACITY TYPE LIQUID PRESSURE PUMP

摘要

PURPOSE:To enable full horse power control through cross sensing, by applying delivery pressure of its system and other system onto a control spool of a constant ratio reducing valve for applying secondary pressure onto a spool of a constant horse power control valve. CONSTITUTION:A piston 20 is arranged at one side of a spring loaded spool 19 of constant horse power control valves 3A, 3B for leading reduced delivery pressure of its system to control plungers 1b, 2b of liquid pressure pumps 1, 2, where secondary pressure P1 or negative pressure P2 of constant ratio reducing valves 4A, 4B are functioning onto a rear face chamber 28 thereof. Delivery pressure of its system is fed to the primary side of the constant ratio reducing valves 4A, 4B, where the delivery pressure of its system is functioning onto the first pressure receiving face A1 of its control spool 42 and the delivery pressure of other system is functioning onto second pressure receiving face A2. Consequently, the constant ratio reducing valves 4A, 4B are controlled by the delivery pressure of both liquid pressure pumps 1, 2 to enable full horse power control of both pumps through cross sensing and negative flow control is enabled by regulating the negative pressure P2.