HYDRAULIC MACHINE

摘要

A hydraulic working machine is provided which has an assist electric motor connected to an engine and a hydraulic pump, the hydraulic working machine being structured in such a manner that the emissions of air pollutants in the exhaust gas from the engine are minimized regardless of fluctuations in the load torque of the hydraulic pump, that the increasing cost of installing an exhaust gas after-treatment device is lowered, and that the reliability of the engine is enhanced. A specific revolution speed suitable for reducing the emissions of air pollutants is stored, and an engine (7) is controlled using the specific revolution speed as a target revolution speed for the engine. The absorption torque of a hydraulic pump (6) is subjected to a high-pass filtering process whereby a high-frequency component devoid of a trend component is obtained. Target assist torque is computed from the high-frequency component, and an assist electric motor (10) is subjected to power running/generation control accordingly. A specific output torque range suitable for reducing the emissions of air pollutants is stored, and the target assist torque is corrected so that the trend component does not exceed the specific output torque range.