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:
Nov. 03, 1992
Filed:
Aug. 08, 1990
Takao Kuwabara, Hitachi, JP;
Eizo Kita, Kyoto, JP;
Hitachi, Ltd., Tokyo, JP;
Kansai Electric Power Co., Ltd., Osaka, JP;
Abstract
A variable-speed pump system comprising: a hydraulic machine having a flow adjusting means and including at least a pumping function; a rotary machine operatively connected to the hydraulic machine and including at least a motor function for rotating the hydraulic machine; a frequency converter for driving the rotary machine; and a control system for controlling variable-speed operation of the rotary machine according to a command signal from an external unit. The pump system also includes an electric power control system, a flow adjustment control system, and a rotational speed control system. The power control system has a negligibly small time constant, compared to the time constant of the rotational speed control system. The flow adjustment control system and/or the rotational speed control system has a means for setting a transmission function in such a manner that a mechanical load of the hydraulic machine is not reduced while the rotational speed thereof is increasing, and that the mechanical load is not increased while the rotational speed is lowering.