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:
Dec. 08, 2020
Filed:
Jan. 16, 2018
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Hiromasa Takahashi, Abiko, JP;
Shohei Sugiki, Tsuchiura, JP;
Kenji Hiraku, Kasumigaura, JP;
Juri Shimizu, Hitachinaka, JP;
Teppei Saitoh, Mito, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A construction machine is provided which includes a hydraulic closed circuit in which a single rod hydraulic cylinder is driven directly by a bidirectionally tiltable variable displacement pump and can stably speed up the contraction action of the single rod hydraulic cylinder. In the case where a contraction action of a hydraulic cylinderis instructed through an operation leverwhen a differential pressure obtained by subtracting the pressure of a cap chamberfrom the pressure of a rod chamberis equal to or lower than a first threshold value a set to a level equal to or higher than a selection setting pressure of a flushing valvea controllercloses a rod side selector valveto disable rod assist action for supplying hydraulic fluid from a second hydraulic pumpto the rod chamber, and when the differential pressure is higher than the first threshold value, the controlleropens the rod side selector valve to enable the rod assist action.