HYBRID WORK MACHINE

摘要

A hybrid work machine has an engine, an assist motor, a hydraulic pump which is driven by the total torque of the engine and the assist motor, and an electric storage device which accumulates electric power generated by the assist motor and supplies the electric power when the assist motor performs electric discharge. The continuous electric discharge from the electric storage device due to continuous operation at high load pressure can be suppressed without an operator experiencing an unusual operational characteristic. To this end, a pump flow rate correction control unit judges whether each hydraulic pump is in a high load operation state or not based on the output horsepower and/or the delivery pressure of each hydraulic pump and performs control such that the delivery flow rate gradually decreases when the hydraulic pump is in the high load operation state and this state continues beyond a predetermined time.

主权项

1. A hybrid work machine comprising:
an engine; an assist motor that is mechanically connected to the engine, performs electric discharge by generating a drive torque and generates electric power by generating a braking torque; at least one hydraulic pump driven by a total torque of the engine and the assist motor; a plurality of actuators driven by hydraulic fluid delivered from the hydraulic pump; an electric storage device that accumulates the electric power generated by the assist motor and supplies the electric power when the assist motor performs electric discharge; and a pump flow rate control device that performs limiting control for a maximum delivery flow rate of the hydraulic pump such that an output horsepower of the hydraulic pump does not exceed a predetermined pump output power reference value, and performs control such that the delivery flow rate of the hydraulic pump gradually decreases when the hydraulic pump remains in a predetermined high load operation state and the high load operation state continues beyond a predetermined time.