| 摘要 |
PROBLEM TO BE SOLVED: To prevent an over-charge of an electrical storage device due to an actuator regenerative electric power while avoiding addition of a regenerative resistance and the use of a large electrical storage device.SOLUTION: When a composite operation of revolving/boom lowering has occurred in a range such that a charging rate of an electrical storage device 12 is equal to or more than a set value, a generator operation of a generator motor 10 is stopped, and a flow quantity of a regeneration circuit 24, which is provided on a return side at the time of a boom lowering operation in a boom cylinder 6, is regulated by a flow quantity regulating valve 29 so as to limit a boom lowering regenerative electric power, so that an over-charge due to the boom lowering regenerative electric power can be prevented and a revolution brake performance can be assured. |
