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. 02, 2014
Filed:
Aug. 17, 2010
Hiroyasu Nishikawa, Tokyo, JP;
Seiichi Akiyama, Tokyo, JP;
Yusuke Shimizu, Tokyo, JP;
Atsunobu Doi, Tokyo, JP;
Sei Shimahara, Tokyo, JP;
Manabu Nakanishi, Kobe, JP;
Masashi Shibata, Kobe, JP;
Hiroyasu Nishikawa, Tokyo, JP;
Seiichi Akiyama, Tokyo, JP;
Yusuke Shimizu, Tokyo, JP;
Atsunobu Doi, Tokyo, JP;
Sei Shimahara, Tokyo, JP;
Manabu Nakanishi, Kobe, JP;
Masashi Shibata, Kobe, JP;
Caterpillar SARL, Geneva, CH;
Abstract
A hydraulic pump driven by an engine, a hydraulic actuator, and a negative control circuit are provided on an open center hydraulic circuit, for guiding the hydraulic pressure in the center bypass to the hydraulic pump, as a negative control pressure. A negative control pressure control device controls the negative control pressure to an arbitrary value is also provided. The pump characteristic of the hydraulic pump is set such that the discharge flow rate is minimized when the negative control pressure in the negative control circuit is equal to or greater than a first predetermined pressure. Furthermore, an idling detection device that detects whether the hydraulic actuator is in a non-operated state or not is provided. The negative control pressure is forcefully controlled to the first predetermined pressure or higher when the non-operating state is detected.