Hydraulic working machine

摘要

A hydraulic working machine has an assist electric motor connected to an engine and a hydraulic pump. 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. A specific revolution speed suitable for reducing the emissions of air pollutants is stored, and an engine is controlled using the specific revolution speed as a target revolution speed. The absorption torque of a hydraulic pump is subjected to high-pass filtering whereby a high-frequency component devoid of a trend component is obtained. Target assist torque is computed from the high-frequency component, and the assist electric motor 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.

主权项

1. A hybrid-driven hydraulic working machine comprising:
an engine; a hydraulic pump driven rotatably by said engine; an assist electric motor connected to said engine and said hydraulic pump; a plurality of actuators driven by hydraulic fluid delivered by said hydraulic pump; a plurality of operating devices each having an operating member, said operating devices operating said actuators by outputting an operation signal reflecting the operation of said operating member; a storage device that stores a specific revolution speed of said engine suitable for reducing the emissions of air pollutants contained in exhaust gas from said engine; an engine revolution speed setting device that sets said specific revolution speed stored in said storage device as a target revolution speed for said engine; an engine revolution speed control device that controls the revolution speed of said engine based on said target revolution speed for said engine, and an electric motor control device that computes differential torque between the absorption torque of said hydraulic pump and target output torque of said engine and that subjects said assist electric motor to power running control and generation control in accordance with the differential torque, wherein said electric motor control device includes:
a pump absorption torque acquiring device that acquires the absorption torque of said hydraulic pump, anda filter device that separates the absorption torque of said hydraulic pump acquired by said pump absorption torque acquiring device into a trend component as target torque for said engine and other component, and wherein said electric motor control device uses said other component separated by said filter device as said differential torque, and subjects said assist electric motor to power running control and generation control in such a manner that said trend component serves as the target output torque for said engine.