Patent ID: 8459008

Claim:
A working machine comprising: a diesel engine; a variable displacement hydraulic pump driven by the diesel engine; exhaust gas treatment equipment having a filter capturing particulate matter in the exhaust gas of the engine; a cooling water temperature sensor that detects cooling water temperature of the engine; and a controller configured to increase at least one of revolution speed N of the engine, displacement volume q and discharge pressure P of the hydraulic pump from a state at low-idle time to increase an engine load, to compulsorily regenerate the filter by allowing fuel to stay in the exhaust gas of the engine to compulsorily elevate exhaust temperature and to instruct the controller to start the compulsory regeneration; and wherein the controller is further configured to keep, after the instruction is given to start the compulsory regeneration and when the cooling water temperature is lower than flame-out prevention temperature T 1 set to prevent occurrence of flame-out during the compulsory regeneration, at least one of the revolution speed N of the engine, the displacement volume q and discharge pressure P of the hydraulic pressure pump at a corresponding first target value (N 1 , q 1 , or P 1 ) set to allow the cooling water temperature to reach the flame-out prevention temperature T 1 or higher, wherein the controller is further configured to keep, after the instruction is given to start the compulsory regeneration and when the cooling water temperature is equal to or higher than the flame-out prevention temperature T 1 , at least one of the revolution speed N of the engine, the displacement volume q and discharge pressure P of the hydraulic pressure pump at a corresponding second target value (N 2 , q 2 , or P 2 ) that is a target value set to keep exhaust temperature at which the compulsory regeneration is possible and that is set lower than the first target value, and wherein the controller is further configured to start the compulsory regeneration after the instruction is given to start the compulsory regeneration and when the cooling water temperature is equal to or higher than the flame-out prevention temperature T 1 .