Control system for controlling input power to variable displacement hydraulic pumps of a hydraulic system

A control system for controlling input power to hydraulic pumps of a hydraulic system including a prime mover, a plurality of variable displacement hydraulic pumps driven by said primer mover and operation devices for respectively varying displacement volumes of said plurality of hydraulic pumps, said control system comprising:

• rotational detecting means for detecting actual rotational speed of said prime mover;
• pressure detecting means for detecting discharge pressure of each of said plurality of hydraulic pumps;
• a control unit which includes
• first computing means for determining, for said plurality of hydraulic pumps, respective input torque control values concerning input torque distribution on the basis of a respective representative pressure, said respective representative pressure being obtained on the basis of discharge pressure of the other hydraulic pumps of said plurality of hydraulic pumps detected by said pressure detecting means,
• second computing means for determining, for said plurality of hydraulic pumps, respective input torque on the basis of respective input torque control values concerning input torque distribution determined by said first computing means,
• third computing means for determining, for said plurality of hydraulic pumps, respective object displacement volume signals from respective input torque determined by said second computing means and respective discharge pressure detected by said pressure detecting means,
• selecting means for comparing said respective object displacement volume signals determined by said third computing means and respective displacement volume signals determined by said operation devices to select respective smaller displacement volume signals;
• and
• control means for controlling an inclined angle of a swash plate of each of said plurality of hydraulic pumps in accordance with respective displacement volume signals selected by said selecting means.