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. 09, 2004
Filed:
May. 16, 2003
Shinji Seto, Tokyo, JP;
Yasuhide Takeda, Tokyo, JP;
Daisuke Ebisawa, Tokyo, JP;
Masayuki Uchiyama, Tokyo, JP;
Atsuji Watanabe, Tokyo, JP;
Hideo Kawamoto, Tokyo, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In a hydraulic pressure actuating apparatus for a circuit breaker, contacts of the circuit breaker have a moving contact and a stationary contact for turning on/off current. A shaft, at an end portion of which is attached the moving contact, and at the other end of which is attached a piston, is received within a cylinder. A directional control valve exchanges oil pressure for actuating the piston. For changing over the directional control valve, pilot valves are provided. Each pilot valve has a pair of valve bodies, each opposing to each other, and springs. One of the valve bodies is able to stroke up to contact with the valve body of the other valve body, therefore giving no ill influences upon actuating time, even if drawback occurs in the pilot valves in the hydraulic pressure actuating apparatus for the circuit breaker.