US3868530A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spark plug
Assignee: Federal Mogul Ignition LLC
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Filing: 1973-07-05
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Granted: 1975-02-25
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Expires: 1993-07-05
Abstract
Abstract This invention relates to spark plugs for internal combustion engines and is particularly directed to a center electrode having a sparking tip composed of a precious metal and to the method of making the same. The known advantage of the use of a precious metal electrode is that considerably greater spark plug life is achieved. The invention achieves the advantage while greatly reducing the mass of precious metal employed. A further feature of the invention is the co-planar disposition of the end of the center electrode and its supporting insulator.
Inventors
- 👤 Carl J Eaton
- 👤 Richard S Podiak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:06
CPC Classifications
H; H01; H01T; H01T13/00; H01T13/20; H01T13/39
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
111 words
In a spark plug having a grounded shell, an insulator, at least one ground electrode carried by the shell, and a center electrode extending through said insulator and terminating in sparking relationship with said ground electrode, said center electrode being formed of metal having good spark corrosion resistant properties, the improvement comprising an axial recess in the firing end of the center electrode, said recess being larger in cross section at its inner end than at its outer end, and an insert of precious metal extending into and filling the recess, said insert being firmly supported by the adjacent electrode with its end exposed at the firing end of the electrode.
Claim 2
Dependent Claim
111 words
In a spark plug having a grounded shell, an insulator, at least one ground electrode carried by the shell, and a center electrode extending through said insulator and terminating in sparking relationship with said ground electrode, said center electrode being formed of metal having good spark corrosion resistant properties, the improvement comprising an axial recess in the firing end of the center electrode, said recess being larger in cross section at its inner end than at its outer end, and an insert of precious metal extending into and filling the recess, said insert being firmly supported by the adjacent electrode with its end exposed at the firing end of the electrode.
Claim 3
Dependent Claim
29 words
The improvement defined in claim 1 wherein the insert is a corrosion resistant metal alloy selected from the group consisting of gold, platinum, palladium, ruthenium, rhenium, rhodium and tungsten.
Claim 4
Dependent Claim
14 words
The improvement defined in claim 1 wherein the axial recess is frustoconical in shape.
Claim 5
Dependent Claim
22 words
The improvement defined in claim 1 wherein a portion of said precious metal insert extends outside the recess in the center electrode.
References Cited (Backward Citations)
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US2168206A
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US2406966A
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US2815463A
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US2783409A
Cited
US2955222A
Cited
US3315113A
Cited
US3407326A
Cited
US3548472A
Cited
US3803982A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-24 | 1978-08-26 | 1979-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-24 | 1982-08-26 | 1983-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-24 | 1986-08-26 | 1987-02-25 | $7700.00 | Window Closed / Lapsed |