Patent ID: 9476437
Filing Date: 2016-10-25
CPC Classification: E02F,F04B,F15B

Claim Text:
1. A boom driving device, comprising: a boom cylinder that elongates to rotate a boom upward in response to a supply of working fluid to a working chamber and contracts to rotate the boom downward in response to discharge of the working fluid from the working chamber; a boom change-over valve that displaces between a pump position connecting the working chamber to a pump and a tank position connecting the working chamber to a tank while increasing a connecting cross-sectional area between the working chamber and the tank when displacing towards the tank position; a power generator; a regenerative passage that is branched off at a position upstream of the boom change-over valve from a passage connecting the working chamber to the tank and supplies a part of the working fluid discharged from the working chamber to drive the generator to rotate; a regenerative control valve that opens and closes the regenerative passage; a sensor that detects a displacement position of the boom change-over valve; a programmable controller programmed to: