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:
Jul. 24, 1990
Filed:
Sep. 26, 1989
Yusaku Nozawa, Ibaraki, JP;
Kazumasa Yuasa, Tsuchiura, JP;
Wataru Ootu, Ibaraki, JP;
Kinya Takahashi, Ibaraki, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A pressure control valve has a main valve element of seat type slidably accommodated in a valve case for controlling communication between inlet and outlet sections of the valve case by movement of the main valve element, a control chamber defined within the valve case and between the valve case and an end face of the main valve remote from the outlet section for biasing the main valve element in a valve closing direction, and a variable restriction variable in its opening in response to the movement of the main valve element for communication between the control chamber and the inlet section of the valve case. There are provided first and second pilot lines for communication between the control chamber and the outlet section of the valve case, first and second pilot valve elements arranged respectively in the first and second pilot lines, a first valve drive unit operative in response to the pressure of the inlet section of the valve case for opening the first pilot valve element when the pressure reaches a first predetermined value, and a second valve drive unit operative in response to differential pressure between the pressure of the inlet section of the valve case and signal pressure introduced to a signal port for opening the second pilot valve element when the differential pressure reaches a second predetermined value.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile