Patent ID: 7255088

Claim:
An engine control system for a construction machine comprising an engine ( 10 ), at least one variable displacement hydraulic pump ( 1 , 2 ) driven by said engine, a plurality of hydraulic actuators ( 50 - 56 ) driven by a hydraulic fluid delivered from said hydraulic pump, a plurality of flow control valves ( 5 a - 5 i ) for controlling respective flow rates of the hydraulic fluid supplied from said hydraulic pump to said plurality of hydraulic actuators, operating means ( 38 - 44 ) for operating said plurality of flow control valves, a fuel injector ( 14 ) for controlling a revolution speed of said engine, input means ( 71 ) for commanding a target revolution speed (NR 1 ) of said engine, and fuel injection amount control means ( 80 ) for computing a target fuel injection amount (FN 1 ) based on the target revolution speed and controlling said fuel injector, wherein said engine control system comprises status variable detecting means ( 73 - 78 ) for detecting a status variable related to a load of said hydraulic pump ( 1 , 2 ), and target revolution speed modifying means ( 70 f - 70 r ) for computing a target revolution speed (NR 2 ) for use in control based on a change of the status variable such that the target revolution speed for use in control increases from the target revolution speed (NR 1 ) set in accordance with a command from said input means ( 71 ), and then moderately returns to the target revolution speed set in accordance with the command from said input means, said fuel injection amount control means ( 80 ) computing the target fuel injection amount (FN 1 ) based on the target revolution speed for use in control.