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:
Dec. 17, 2013
Filed:
Nov. 02, 2011
Tomohiro Numajiri, Tokyo, JP;
Tomohiro Numajiri, Tokyo, JP;
Mitsubishi Heavy Industries, Ltd., Tokyo, JP;
Abstract
A pitch driving unit according to the present invention is equipped with hydraulic actuators that change the pitch angles of wind turbine blades; a hydraulic pump that supplies oil to the hydraulic actuators; a high-pressure oil line that guides the oil discharged from the hydraulic pump to the hydraulic actuators; a low-pressure oil line that returns the oil discharged from the hydraulic actuators to the hydraulic pump; and a pressure control unit that stores a surplus amount of the oil and that refills the low-pressure oil line with the oil so as not to generate negative pressure at an oil intake portion of the hydraulic pump, wherein the hydraulic actuators, the hydraulic pump, the high-pressure oil line, the low-pressure oil line, and the pressure control unit constitute a closed hydraulic circuit that does not open to the atmosphere, the closed hydraulic circuit being filled with the oil.