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. 23, 2013
Filed:
Jan. 30, 2008
Nobuei Ariga, Tsuchiura, JP;
Kouji Ishikawa, Kasumigaura, JP;
Hideo Karasawa, Tsuchiura, JP;
Yasuo Okano, Tsuchiura, JP;
Kazunori Nakamura, Tsuchiura, JP;
Youichi Kowatari, Kasumigaura, JP;
Nobuei Ariga, Tsuchiura, JP;
Kouji Ishikawa, Kasumigaura, JP;
Hideo Karasawa, Tsuchiura, JP;
Yasuo Okano, Tsuchiura, JP;
Kazunori Nakamura, Tsuchiura, JP;
Youichi Kowatari, Kasumigaura, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A pump torque control system is capable of preventing hunting due to interference between speed sensing control and control of an engine speed of a prime mover when the temperature of a hydraulic fluid is low. A maximum absorption torque is set in a regulatorthat controls displacement volumes of hydraulic pumpsandbased on a deviation between target and actual engine speeds of a prime mover. A second modification factor calculating sectionand a control gain modifying section, which are included in a controllerthat performs speed sensing control to ensure that the maximum absorption torque of the hydraulic pumpsandis reduced, change a control gain of the speed sensing control based on a value detected by the hydraulic temperature sensorto ensure that the control gain is reduced as the temperature of the hydraulic fluid is reduced.