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. 17, 1987
Filed:
Jul. 15, 1983
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A fluid control valve apparatus comprises logic valve means including a valve housing, a first valve member defined in the valve housing, and an axially movable valve body arranged in the first valve chamber, with the valve body including opposite end portions and a conical surface portion brought into contact with the conical surface portion when the valve body is moved in a valve closing direction. First and second hydraulic fluid chambers are defined in the valve housing and communicate with each other when the conical surface portion is out of contact with the valve seat and out of communication when the conical surface portion contacts the valve seat. A first pilot chamber in the valve housing, adjacent one end portion of the valve body, biases the valve body in a closing direction by a first pilot pressure signal. A second valve chamber is defined in the valve housing with an extension of the valve body being formed by extending the other end portion of the valve body through the first hydraulic fluid chamber, and is arranged in the second valve chamber for axial movement. An independent second pilot chamber biases the valve body in an opening direction by a second pilot pressure signal.