Load sensing control system for hydraulic machine

A control system for a hydraulic pump in a hydraulic drive circuit of load sensing control type comprising at least one hydraulic pump of variable displacement type, at least one hydraulic actuator driven by a hydraulic fluid delivered from said hydraulic pump, and a flow control valve connected between said hydraulic pump and said actuator for controlling a flow rate of the hydraulic fluid supplied to said actuator, wherein a target displacement volume is determined based on a differential pressure deviation between a differential pressure between a delivery pressure of said hydraulic pump and a load pressure of said actuator and a target differential pressure whereby a displacement volume of said hydraulic pump is controlled so that said differential pressure between the delivery pressure and the load pressure is held at said target differential pressure, said control system for a hydraulic pump further comprising:

• (a) first means including said target differential pressure set as a variable value;
• (b) second means for determining a control factor that becomes larger as said differential pressure deviation calculated from said target differential pressure as a variable value is increased and becomes smaller as said differential pressure deviation is decreased, and also that becomes larger as said target differential pressure becomes smaller;
• and
• (c) third means for determining said target displacement volume based on said differential pressure deviation calculated from said target differential pressure as a variable value and said control factor.