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:
Oct. 07, 1986
Filed:
Jan. 14, 1985
Jack Stifelman, Bloomington, MN (US);
Patrick Fisher, Bloomington, MN (US);
John F Connelly, Minnetonka, MN (US);
Donaldson Company, Inc., Minneapolis, MN (US);
Abstract
The present invention is directed to a duplex filter apparatus which provides for a first primary filter path and a second path for secondary filtration. The first path includes a shutoff valve on one side of the primary filter and a check valve on the downstream side. The second path includes a regulating bypass valve on the upstream side of the secondary filter and a check valve on the downstream side. The regulating bypass valve gradually shifts fluid flow from the first path to the second path when differential pressure across the primary filter increases beyond a predetermined level. A reservoir return bypass valve directs fluid flow gradually from the secondary filter when differential pressure across the secondary filter increases beyond a predetermined level. Bleed valves are provided to relieve pressure on filter elements when the filter elements are isolated so that servicing may occur.