EXHAUST-GAS PURIFICATION SYSTEM FOR HYDRAULIC CONSTRUCTION EQUIPMENT

When an output value of an exhaust resistance sensor 34 has reached or exceeded a set value ”Pa, a controller 20 executes recovery control of a filter of an exhaust gas purification device 32 after conducting exhaust temperature increasing control by operating a pump discharge pressure increasing device (solenoid proportional valve) 38 so that exhaust gas temperature as an output value of an exhaust temperature sensor 33 reaches a preset value Ta. Thus, the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature irrespective of the operating environment and the fuel consumption can be kept at a minimum necessary level.