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. 13, 2018
Filed:
Mar. 17, 2014
Hitachi Construction Machinery Co., Ltd., Koka-shi, JP;
Kiwamu Takahashi, Koka, JP;
Yasutaka Tsuruga, Moriyama, JP;
Yoshifumi Takebayashi, Koka, JP;
Kazushige Mori, Koka, JP;
Natsuki Nakamura, Koka, JP;
Hitachi Construction Machinery Tierra Co., Ltd., Koka-shi, JP;
Abstract
In addition to a main pumphaving two delivery portsandand performing the load sensing control, two subsidiary pumpsandfor the load sensing control for respectively performing assist driving on a boom cylinderand an arm cylinderare provided. When driving the boom cylinderor the arm cylinder, a selector valveoris switched and flows of hydraulic fluid are merged together and supplied to the boom cylinderor the arm cylinder. When driving actuators other than the boom cylinderor the arm cylinder, only the hydraulic fluid from the main pump is supplied to the actuators. In short, the hydraulic drive system is configured so that two specific actuators having great demanded flow rates and tending to have a great load pressure difference between each other when driving at the same time can be driven with hydraulic fluid delivered from separate delivery ports. With this configuration, wasteful energy consumption due to pressure loss in a pressure compensating valve can be suppressed, and in cases of driving an actuator of a low demanded flow rate, the hydraulic pump can be used at a point where the volume efficiency is high.