# US 5,344,081 A · Injector valve seat with recirculation trap > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,081 A - Document ID: US5344081A - Status: Granted - Kind: A - Application number: 08/117,888 - Filed: 1993-09-07 - Granted: 1994-09-06 - Earliest claimed: 1992-04-01 - Assignees: Siemens Automotive Corporation - Inventors: Russell J. Wakeman - Web page: https://patentgrep.com/patent/US5344081A ## CPC - F02M 61/1853: {Orifice plates} - B05B 1/3046: {the valve element, e.g. a needle, co-operating with a valve seat located downstream of the valve element and its actuating means, generally in the proximity of the outlet orifice (B05B1/308 takes precedence)} - Y10S 239/90: Electromagnetically actuated fuel injector having ball and seat type valve - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract An improvement in fuel flow through orifices of a thin disc orifice member is obtained by incorporating a radially inwardly open undercut in the seat member below the frustoconical seating surface and above the thin disc orifice member. The undercut provides a space that allows a fuel recirculation zone to be displaced further radially outwardly so that it poses less of an obstruction to flow toward the orifice. ## Claims ### Claim 1 A fuel injector comprising a body having an inlet at which pressurized liquid fuel is delivered to the fuel injector, a nozzle from which the fuel injector injects fuel, passage means for conveying fuel from said inlet to said nozzle, said nozzle comprising an orifice through which fuel is injected from the nozzle, said passage means comprising a seating surface that is disposed upstream of said orifice proximate said orifice and that converges in the downstream direction to give at the narrowest convergence of said seating surface a diameter that is spaced upstream and radially outwardly of said orifice, an electromechanically actuated mechanism comprising a valve member that is operated to selectively seat on and unseat from said seating surface and thereby allow and disallow fuel to be injected through said orifice, said seating surface and said valve member being constructed to have a coaction that, when said valve member is unseated from said seating surface to define a lift opening between them, directs the fuel in the direction of the convergence of said seating surface, said orifice being disposed out of the direction of the convergence of said seating surface such that fuel that has already passed through said lift opening and is flowing in the direction of convergence of said seating surface is required to execute a bend that diverges from the direction of the convergence of said seating surface before it passes through said orifice resulting in the creation of a fuel recirculation zone, said recirculation zone being characterized by some of the fuel approaching said orifice being recirculated as an eddy before it reaches said orifice, said passage means being formed as an undercut in the region of said recirculation zone, said undercut being disposed between said seating surface and said orifice and comprising a frustoconically expanding portion followed by a circular groove in the direction of said orifice, wherein a substantial portion of the recirculation zone occupies said undercut, such that the recirculation zone is displaced in a direction out of the path of said bend, thereby reducing a tendency of reduced fuel flow through one portion of said orifice in comparison to fuel flow through another portion of said orifice as a result of said eddy, whereby the flow through said one portion of said orifice more closely approaches the flow through said another portion of said orifice. ### Claim 2 (depends on 1) A fuel injector as set forth in claim 1 characterized further in that said seating surface and said undercut are embodied in a common part that is assembled into the fuel injector. ### Claim 3 (depends on 2) A fuel injector as set forth in claim 2 characterized further in that said orifice is in a thin disc orifice member that is assembled into the fuel injector and is disposed against said part. ### Claim 4 (depends on 3) A fuel injector as set forth in claim 3 characterized further in that said fuel injector has a main longitudinal axis and said orifice lies in a plane that is perpendicular to that axis. ### Claim 5 (depends on 3) A fuel injector as set forth in claim 3 characterized further in that said fuel injector has a main longitudinal axis and said orifice lies in a plane that is non-perpendicular to that axis. ### Claim 6 (depends on 3) A fuel injector as set forth in claim 3 characterized further in that said fuel injector has a main longitudinal axis and said thin disc orifice member comprises plural such orifices arranged circumferentially spaced apart from each other about that axis. ### Claim 7 (depends on 1) A fuel injector as set forth in claim 1 characterized further in that the upstream terminus of said undercut is spaced axially of the downstream terminus of said frustoconical seating surface.