Hybrid excavator having a system for reducing actuator shock

摘要

Disclosed is a hybrid excavator which reduces the impact generated at the start of the operation of the boom cylinder, or the like, of a hybrid excavator. The hybrid excavator according to the present invention comprises: a hydraulic pump motor connected to an electric motor and operated in the forward or reverse direction; a hydraulic cylinder connected to the hydraulic pump motor and operated in an expanding manner; a first and second hydraulic valve installed in a first and second passage, respectively, between the hydraulic pump motor and the hydraulic cylinder, for blocking the first and second passages when switched by an external control signal; a third hydraulic valve installed in the connecting path connected to first and second dividing passages.

主权项

1. A hybrid excavator provided with an actuator impact reduction system, wherein the actuator impact reduction system comprises:
an electric motor; a hydraulic pump-motor connected to the electric motor and configured to be driven in a forward or reverse direction; a hydraulic cylinder configured to be expanded and contracted by a hydraulic fluid that is supplied along first and second flow paths connected to the hydraulic pump-motor; first and second hydraulic valves installed in the first and second flow paths between the hydraulic pump-motor and the hydraulic cylinder, respectively, and configured to be shifted to control the first and second flow paths in response to a control signal applied thereto from outside; a third hydraulic valve installed in a connection path connected to first and second branch flow paths that are branch-connected to the first and second flow paths on an upstream side of the first and second hydraulic valves and the first and second flow paths on a downstream side of the first and second hydraulic valves, respectively, and configured to be shifted to compensate for or bypass a flow rate of the hydraulic fluid in order to overcome a difference in flow rate of the hydraulic fluid, which occurs due to a difference in cross section between a large chamber and a small chamber of the hydraulic cylinder; and first and second pilot chambers configured to supply a pressure of the first and second flow paths to the third hydraulic valve as a pilot signal pressure so as to shift the third hydraulic valve, the first and second pilot chambers being formed to have different cross sections, wherein a ratio of the cross section between the first and second pilot chambers of the third hydraulic valve is made equal to a ratio of the cross section between the small chamber and the large chamber of the hydraulic cylinder.