| 摘要 |
PURPOSE: To provide a variable pump controller which can output a positive signal without using any inverting amplifier based on the prerequisite that a negative control circuit is inexpensive. CONSTITUTION: A variable pump controller is provided with a variable pump P, a selector valve V arranged between the variable pump P and an actuator, and a neutral flow path 1 which is fully opened when the selector valve V is held in a neutral position. The variable pump controller is also provided with an output control valve C controlled on the basis of a pressure loss in the neutral flow path 1, a pilot pump PP, a pressure signal flow path 5 which takes out a pilot pressure controlled by means of the output control valve C in terms of a pressure signal, and a controlling means controlling discharge of the variable pump P on the basis of the pressure signal. The output control valve C is constructed of a body, a spool, which is arranged in the body freely slidably and moved by means of a pressure generated because of the pressure loss in the neutral flow path 1, and a throttle part 21, which is formed in the spool and lowers the pressure signal from the pressure signal flow path 5 according to a shift of the spool. |
