The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 12, 2019
Filed:
Dec. 12, 2014
Doosan Infracore Co., Ltd., Incheon, KR;
Byung Il Kang, Incheon, KR;
Ki Hwan Hong, Incheon, KR;
DOOSAN INFRACORE CO., LTD., Incheon, KR;
Abstract
The present disclosure relates to a closed circuit hydraulic system for a construction machine including a plurality of actuators and a plurality of hydraulic pumps selectively supplying working oil to the plurality of actuators bidirectionally and the closed circuit hydraulic system includes: a charge line selectively connected with a low-pressure side hydraulic line which returns to the hydraulic pump from the actuator among hydraulic lines connecting the hydraulic pumps and the actuators; a charge pump supplying a supplement flow to the charge line; and a variable relief valve selectively changing a normal mode to limit a pressure of the charge line to a predetermined pressure or less and a boost mode to limit the pressure of the charge line to a pressure lower than the pressure of the charge line in the normal mode.