Patent ID: 9512596
Filing Date: 2016-12-06
CPC Classification: E02F,F15B

Claim Text:
1. A boom actuating system for use with a hybrid excavator, comprising: an electric motor operated as a motor or a generator; an electricity storage device configured to store electricity generated in the electric motor; a hydraulic pump motor driven by the electric motor to supply hydraulic fluid to a boom; a boom control valve configured to selectively connect or disconnect an outlet line and an inlet line of the hydraulic pump motor to or from a head or a rod of a boom cylinder operating the boom; a motor bypass valve connected to the outlet line and the inlet line to interconnect the outlet line and the inlet line or disconnect the outlet line from the inlet line; and a controller configured to control the electric motor, the hydraulic pump motor, the boom control valve, and the motor bypass valve; wherein in a case where a flow rate discharged from the head of the boom after the descending of the boom is initiated is equal to or larger than a predetermined value, the controller operates the hydraulic pump motor, and switches the motor bypass valve so as to disconnect the outlet line and the inlet line.