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:
Apr. 24, 2012
Filed:
Nov. 18, 2003
Kazunori Nakamura, Tsuchiura, JP;
Yoichi Kowatari, Ibaraki-ken, JP;
Kouji Ishikawa, Ibaraki-ken, JP;
Yasushi Arai, Tsuchiura, JP;
Kazunori Nakamura, Tsuchiura, JP;
Yoichi Kowatari, Ibaraki-ken, JP;
Kouji Ishikawa, Ibaraki-ken, JP;
Yasushi Arai, Tsuchiura, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A current load rate of an engineis computed and a maximum absorption torque of at least one hydraulic pumpis controlled so that the load rate is held at a target value. Engine stalling can be prevented by decreasing the maximum absorption torque of the hydraulic pump under a high-load condition. When an engine output lowers due to environmental changes, the use of poor fuel or other reasons, the maximum absorption torque of the hydraulic pump can be decreased without a lowering of the engine revolution speed. Further, the present invention is adaptable for any kinds of factors causing a lowering of the engine output, such as those factors that cannot be predicted in advance or are difficult to detect by sensors. In addition, because of no necessity of sensors, such as environment sensors, the manufacturing cost can be reduced.