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. 12, 2001
Filed:
Aug. 12, 1999
Kawasaki Jukogyo Kabushiki Kaisha, Hyogo, JP;
Abstract
A control device for a variable displacement pump in which a discharge flow rate of a hydraulic operating fluid is varied by changing a variable element comprises a first negative feedback circuit,for controlling a pressure of the hydraulic operating fluid fed from the variable displacement pump, a second negative feedback circuit,, and change-over control means,. The first negative feedback circuit,has first pressure detecting means,for detecting the pressure of the hydraulic operating fluid, second pressure detecting means,for detecting a vent pressure of an electromagnetic relief valve, and a differential pressure calculation circuit,for calculating a difference between the pressures detected by the first and second pressure detecting means,and,. The change-over control means,performs change-over control by utilizing a differential pressure signal sent from the differential pressure calculation circuit,in such a manner that a relief flow rate of the hydraulic operating fluid is reduced when the pressure detected by the first pressure detecting means,is higher than a target pressure.