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:
May. 09, 2000
Filed:
Dec. 09, 1998
John G Purnell, Catonsville, MD (US);
Alan J Becnel, Annapolis, MD (US);
The United States of America as represented by the Secretary of the Navy, Washington, DC (US);
Abstract
The invention features a unique surface configuration which fosters atmosric ventilation and thereby uncomplicatedly reduces drag which is normally associated with implementation of shrouding for a marine impeller. Typical inventive embodiments include a blunt trailing edge and a circumferentially stepped impeller shroud (below the blunt trailing edge), the harmonious union of which affords a generally smooth and unbroken surface which encourages drag-defeating air circulation. During marine navigation, circulation of the air generally describes a path wherein the air first travels linearly downward along the blunt trailing edge, then travels curvingly downward (both clockwise and counterclockwise) along the circumferential step, forming a circumferential air pocket which extends a backward distance increasing in accordance with increasing navigational speed; upon attainment of a threshold navigational speed, the air pocket (virtually) completely surrounds the shroud. According to the invention, many a conventional outboard open propeller assembly can be facilely converted to an inventive outboard shrouded impeller assembly which produces equal or superior performance.