Method and apparatus for electrochemical machining of spray holes in fuel injection nozzles
First Claim
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1. The method of electrochemically machining material at the inner end of least one spray hole formed in the body of a fuel injection nozzle for an internal combustion engine, comprising:
- providing an electrode within, and electrically insulated from, said body; and
maintaining said electrode at a negative electrical potential with respect to said body while applying a pressurized electrolyte to the exterior of said nozzle body so as to pass said electrolyte through said at least one spray hole inwardly of said body, thereby to electrochemically machine away portions of said body adjacent to the inner end of each said spray hole.
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Abstract
The inner end of a spray hole in a fuel injection nozzle for an internal injection engine is electrochemically machined by providing a negative electrode inside a chamber in said body, while applying an electrolyte under pressure to the exterior of the nozzle body, so as to cause the electrolyte to flow through the spray hole inwardly of said body. The electrolyte is preferably an aqueous solution of NaCl.
17 Citations
14 Claims
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1. The method of electrochemically machining material at the inner end of least one spray hole formed in the body of a fuel injection nozzle for an internal combustion engine, comprising:
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providing an electrode within, and electrically insulated from, said body; and maintaining said electrode at a negative electrical potential with respect to said body while applying a pressurized electrolyte to the exterior of said nozzle body so as to pass said electrolyte through said at least one spray hole inwardly of said body, thereby to electrochemically machine away portions of said body adjacent to the inner end of each said spray hole. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. The method of electrochemically machining material at the inner ends of a plurality of spray holes formed in the body of a ferrous-metal injection nozzle for an internal combustion engine, the inner ends of such spray holes before said machining defining small-radius corners in said body, said method comprising:
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providing an upright electrode the upper end of which extends within said body and is no greater than about 0.020 inch in diameter, said electrode being electrically insulated from said body; applying to the exterior of the portion of said body containing said spray holes an electrolyte under pressure to produce a flow of said electrolyte through said spray holes inwardly of said body; and while said inward flow is occurring, maintaining said electrode at a negative potential with respect to said body, thereby to electrochemically machine the material of said body at said inner ends of said spray holes and to increase the radii curvature of said corners, the current flowing through said electrolyte due to said potential being no greater than about 5 amperes. - View Dependent Claims (9, 10)
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11. Apparatus for treating the body of a fuel injection nozzle for an internal combustion engine, said body having at least one spray hole extending through it, said apparatus comprising:
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an upright elongated electrode, and means for positioning the upper end portion of said electrode within said body adjacent to said spray holes; means for biasing said electrode negative with respect to said body; and means for flowing an electrolyte inwardly through said spray holes, into the interior of said body and past said upper end portion of said electrode, while said electrode is biased negatively, to produce electrochemical machining of the portions of said body adjacent the inner ends of each of said at least one spray holes. - View Dependent Claims (12, 13, 14)
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Specification