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. 11, 2001
Filed:
Jul. 13, 2000
Kinya Takahashi, Tsuchiura, JP;
Yoshizumi Nishimura, Tsuchiura, JP;
Yusaku Nozawa, Ibaraki-ken, JP;
Nobuhiko Ichiki, Ibaraki-ken, JP;
Mitsuhisa Tougasaki, Ibaraki-ken, JP;
Hitachi Construction Machinery, Tokyo, JP;
Abstract
A recovery check valve,and a piston valve,are axially slidably disposed within a spool,in coaxial relation. An axial fluid passage,is formed within a cylindrical portion,of the piston valve,and a seat portion,for the recovery check valve is formed at an open end of the cylindrical portion,The cylindrical portion,of the piston valve is formed with a hole,through which a hydraulic fluid in the fluid chamber,is introduced to a bridge passage,when the spool,is operated so as to introduce a hydraulic fluid from a hydraulic pump to the bottom side of a hydraulic cylinder. Fluid passages,are formed within the spool so that a hydraulic fluid in the bridge passage,is introduced to the closed end of the piston valve through the fluid passages when the spool is operated in the opposite direction. With such a structure, the size of the valve apparatus can be set to the same size as the directional control valve not provided with the recovery check valve.