Method and device for controlling power output of engine for working machine

Abstract

An engine control device detects the state of work of a working vehicle such as a construction machine or the like, and controls the power output capacity of an engine automatically. A determination is made as to whether excavation or uphill traveling is being performed, based upon the detection signals from a hydraulic oil pressure detector for a hydraulic cylinder of an arm, detectors for arm and bucket operation commands, a shift operation detector for a transmission, a pitch angle detector for the vehicle body, a traveling acceleration detector, and an accelerator opening degree detector. When the result of this determination is that excavation or uphill traveling is being performed, the engine is controlled to operate at a high power capacity, while at other times it is controlled to operate at a low power output capacity.

1 . A wheel loader that is provided with a work apparatus and a travel apparatus that are driven by a power output of an engine and that carries out the excavation and loading work by operating the work apparatus while traveling by the travel apparatus, comprising:
 one or more detectors which detect one or more of variable values which indicate a state or states of one or more work loads which consume a power output from an engine; and   a controller which controls an upper limit output torque of said engine that said engine can output according to an engine rotational speed, based upon said detected one or more variable values which have been detected by said one or more detectors,   wherein said one or more work loads include a work apparatus which is provided to said wheel loader,   wherein said one or more detectors include a hydraulic oil pressure detector which detects a hydraulic oil pressure or pressures of one or more hydraulic cylinders for driving said work apparatus, and   wherein said controller determines whether or not excavation is being performed based upon said one or more variable values, and controls said upper limit output torque of said engine so that said upper limit output torque for when it is determined that said excavation is not being performed is lower than said upper limit output torque for when it is determined that said excavation is being performed.   
     
     
         2 . The wheel loader according to  claim 1 , wherein said one or more detectors include a work apparatus position detector which detects a position or an attitude of said work apparatus with respect to a reference value. 
     
     
         3 . The wheel loader according to  claim 1 , wherein said one or more work loads include a travel apparatus which is provided to said wheel loader. 
     
     
         4 . The wheel loader according to  claim 1 ,
 wherein said one or more hydraulic cylinders which drive the work apparatus are one or more lift cylinders of the wheel loader, and   wherein said one or more detectors detect the hydraulic oil pressure or pressures at bottom ends of said one or more lift cylinders of the wheel loader.