| 摘要 |
<p>Provided is an electric drive unit for a construction machine capable of increasing the operating time of the construction machine (which is limited by the electricity storage device mounted on the construction machine) from the currently possible operating time by use of the power generation operation of the motor/generator. The electric drive unit comprises an electricity storage device 7, a hydraulic pump 30 of the fixed displacement type which is driven by a motor/generator 29, a plurality of directional control valves 33, 34, etc. which respectively control the flow of hydraulic fluid supplied from the hydraulic pump 30 to a plurality of hydraulic actuators, a bidirectional converter 28 which performs variable control on the revolution speed of the motor/generator 29, and an LS control device 45 which controls the bidirectional converter 28 so that LS differential pressure Pls equals a target value Pgr. The bidirectional converter 28 performs regeneration control for converting the inertial force of the rotor of the motor/generator 29 into electric power and thereby charging the electricity storage device 7 when the revolution speed of the motor/generator 29 is decreased in response to an excess of the LS differential pressure Pls over the target value Pgr.</p> |
