To provide an apparatus for preventing the lag-down of an engine for a construction machine which can carry out the more accurate control of the pump torque.
The apparatus for preventing the lag-down of the engine comprises a vehicle body controller 13, and an electromagnetic valve 16, 41 etc. the vehicle body controller 13 composes a first torque control means for controlling a position control valve 8, a torque control valve 7 so as to obtain minimum pump torque Min corresponding to a target rotational speed of the engine when the non-operated state of an operation device 5 has continued for a monitoring time T1, and a second torque control means for controlling the position control valve 8 and the torque control valve 7 so as to keep the minimum pump torque Min for a required holding time T after operating the operation device 5 from a non-operated state, In addition, the holding time T is composed of the constant reference time T2, the suppression time T3 that follows the reference time T2 is the variable time, and the vehicle body controller 13 includes a calculating means for obtaining the suppression time T3 that is a variable time according to the load of the engine 1. By this apparatus, the more accurate pump torque control including pump torque control by position control can be carried out, and the lag-down of the engine occurring for an instant when the operating device is operated from the non-operated state is suppressed while preventing the deterioration of the driving performance of a hydraulic actuator.
ARAI YASUSHI
NAKAMURA KAZUNORI
KARASAWA HIDEO
KOMATSU HIDEKI
Ichiro Suzuki
Hirohiro Ichimura
Kazunori Satake