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:
Jun. 15, 1999
Filed:
Oct. 06, 1998
Kazunori Nakamura, Ibaraki, JP;
Ei Takahashi, Tsuchiura, JP;
Tsukasa Toyooka, Ibaraki-ken, JP;
Kouji Ishikawa, Ibaraki-ken, JP;
Tsuyoshi Nakamura, Ibaraki-ken, JP;
Yoichi Kowatari, Ibaraki-ken, JP;
Tadatoshi Shimamura, Ishioka, JP;
Genroku Sugiyama, Ibaraki-ken, JP;
Toichi Hirata, Ushiku, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A reference pump-delivery-rate calculating portion calculates a reference delivery rate of a hydraulic pump by referring to a table stored in a memory based on a control pilot pressure for the hydraulic pump. A target pump-delivery-rate calculating portion divides the reference delivery rate by a ratio of a maximum revolution speed to a target engine revolution speed, thereby calculating a target delivery rate. A target pump tilting calculating portion divides the target delivery rate by an actual engine revolution speed and a constant, thereby calculating a target tilting. A solenoid output current calculating portion calculates a drive current to provide the target tilting and outputs the drive current to a solenoid control valve. The pump delivery rate is thereby controlled with good response following input change of an operation instructing device.