Engine Control System for Construction Machine

Abstract

Disclosed is an engine control system for a construction machine having an engine and a control device for controlling, via a directional control valve, a flow of pressure oil to be fed to a hydraulic actuator. The system is provided with a controller, which includes a manipulation state determination unit for the control device and an idle stop control unit for performing idle stop control when the control device is determined to have remained unmanipulated. The system also includes a temperature sensing device for a fluid relevant to the operation of the engine. The controller includes a unit for determining whether or not the temperature of the fluid is not higher than a predetermined temperature. When the temperature of the fluid is determined to be not higher than the predetermined temperature, the controller disables the idle stop control.

1 . An engine control system for a construction machine provided with an engine, a hydraulic pump drivable by the engine, a hydraulic actuator drivable by pressure oil delivered from the hydraulic pump, a directional control valve for controlling a flow of pressure oil to be fed from the hydraulic pump to the hydraulic actuator, and a control device for switchingly controlling the directional control valve, and
 said engine control system being provided with a controller, which includes a manipulation state determination unit for determining a manipulation state of the control device and an idle stop control unit for performing idle stop control to stop an operation of the engine when the control device is determined to have remained unmanipulated for a predetermined time at the manipulation state determination unit,   wherein the engine control system is provided with a temperature sensing device for detecting a temperature of a fluid relevant to the operation of the engine, the controller comprises a temperature determination unit for determining whether or not the temperature of the fluid as detected by the temperature sensing device is not higher than a predetermined temperature set beforehand, and, when the temperature of the fluid is determined to be not higher than the predetermined temperature at the temperature determination unit, the controller performs processing to disable the idle stop control by the idle stop control unit.   
     
     
         2 . The engine control system according to  claim 1 , wherein:
 the controller is provided with an idle operation control unit for holding an rpm of the engine at an idle rpm, which is a predetermined low rpm, when the control device is determined by the manipulation state determination unit to have been brought from a manipulated state to an unmanipulated state, and   the idle stop control unit performs processing to stop the operation of the engine when the control device is determined by the manipulation state determination unit to have been unmanipulated for a predetermined time from a start of idle operation control by the idle operation control unit.   
     
     
         3 . The engine control system according to  claim 1 , wherein:
 the fluid comprises working oil for driving the hydraulic actuator, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the working oil.   
     
     
         4 . The engine control system according to  claim 1 , wherein:
 the fluid comprises engine coolant for cooling the engine, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the engine coolant.   
     
     
         5 . The engine control system according to  claim 1 , wherein:
 the fluid comprises fuel for the engine, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the fuel.   
     
     
         6 . The engine control system according to  claim 1 , wherein:
 the fluid comprises air in a work environment where the construction machine is placed, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the air to be introduced into an intake pipe of the engine.   
     
     
         7 . The engine control system according to  claim 2 , wherein:
 the fluid comprises working oil for driving the hydraulic actuator, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the working oil.   
     
     
         8 . The engine control system according to  claim 2 , wherein:
 the fluid comprises engine coolant for cooling the engine, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the engine coolant.   
     
     
         9 . The engine control system according to  claim 2 , wherein:
 the fluid comprises fuel for the engine, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the fuel.   
     
     
         10 . The engine control system according to  claim 2 , wherein:
 the fluid comprises air in a work environment where the construction machine is placed, and the temperature sensing device comprises a temperature sensor for detecting a temperature of the air to be introduced into an intake pipe of the engine.