Torque control device for hydraulic pump in hydraulic construction equipment

Abstract

A torque control system for a hydraulic pump in a hydraulic construction machine wherein if an engine output lowers due to change of the environment, modification gain calculating portions 70m-70u and a torque modification value calculating portion 70v receive signals detected by sensors 75-82 and estimate a lowering of the engine output power as a torque modification value ΔTFL. A speed sensing torque deviation modifying portion 70i subtracts the torque modification value ΔTFL from a speed sensing torque deviation ΔT1. A resulting torque modification ΔTNL is added to a pump base torque TR0 to determine a suction torque TR1 (target maximum suction torque), and a resulting signal is output to a solenoid control valve 32. The solenoid control valve 32 controls respective servo valves 22 for total horsepower control, thereby controlling the maximum suction torque of the hydraulic pumps 1, 2. As a result, even when the output power of a prime mover lowers, a reduction of the revolution speed of the prime mover can be suppressed at a high load.

Dependencies are inferred from the claim text.