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US 4,639,568 AGranted
Apparatus and method for finishing fuel injector spray tips using EDM
AssigneeEx-Cell-O Corporation
InventorsJohn M. Check, Myron C. Johnson
Life of this patent
Estimating the term…
Abstract
Apparatus and a method are provided to form the interior of a fuel injector spray tip by use of a cold forming punch to form a V-shaped spray tip interior configured to reduce fuel dribble and thereafter finishing the interior by use of an EDM electrode to form precision valve seat and fuel sack surfaces.
Claims8
In apparatus for forming the interior tip region of a dripless fuel injector spray tip having a pre-formed interior surface;
- means for cold deforming the pre-formed interior surface to form a V-shaped electrode tip relief space and a pre-shaped frusto-conical near net shape valve seat surface, said V-shaped space having an included angle less than the included angle of said pre-shaped frusto-conical near net shape valve seat surface, and electrode means for non-contact machining the frusto-conical surface to produce a precise valve seat and reduced valve tip volume to control fuel dribble, said electrode means including a tip accommodated by said tip relief space for preventing excessive electrode tip erosion.
A method for producing a dripless fuel sack volume in a fuel injector spray tip having a bore terminating at a frusto-conical surface with a blunt end surface comprising the steps of:
- cold deforming the blunt end surface and frusto-conical surface to produce a V-shaped electrode tip relief space and a near net shape valve seat, and thereafter non-contact machining the valve seat by use of a V-shaped electrode having its tip configured to be spaced from the tip at the relief space thereby to form a finished valve tip interior that accommodates a needle valve component while defining a reduced volume fuel cavity to reduce fuel dribble when the valve is closed.
Dependencies are inferred from the claim text.