US3719850A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spark plug especially for rotary piston internal combustion engines
Assignee: Daimler Benz AG
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Filing: 1971-03-17
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Granted: 1973-03-06
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Expires: 1991-03-17
Abstract
Abstract Spark plug for rotary piston internal combustion engines having a two-part outer conductive housing including an outer threaded portion of high strength and an inner portion having a high heat conductivity so that heat is conducted longitudinally away from the discharge end of the plug to an area where it will be more efficiently conducted to the engine housing.
Inventors
- 👤 M Schafer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:35
CPC Classifications
H; H01; H01T; H01T13/00; H01T13/02; H01T13/16
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
121 words
Spark plug, especially for rotary piston internal combustion engines, comprising a center electrode, an insulator surrounding said center electrode, and a conductive housing surrounding said insulator, said housing consisting at least in part of an outer threaded part and an inner thermally conductive part of higher thermal conductivity than said outer threaded part in heat contact with said insulator for conducting heat longitudinally of said plug away from said threaded portion, said inner part of said housing being separated from said insulator along the major interior surface thereof so as to provide a gap between said inner part and said insulator, while being in thermally conductive communication with said insulator only at a specified portion thereof to provide heat contact therebetween.
Claim 2
Dependent Claim
121 words
Spark plug, especially for rotary piston internal combustion engines, comprising a center electrode, an insulator surrounding said center electrode, and a conductive housing surrounding said insulator, said housing consisting at least in part of an outer threaded part and an inner thermally conductive part of higher thermal conductivity than said outer threaded part in heat contact with said insulator for conducting heat longitudinally of said plug away from said threaded portion, said inner part of said housing being separated from said insulator along the major interior surface thereof so as to provide a gap between said inner part and said insulator, while being in thermally conductive communication with said insulator only at a specified portion thereof to provide heat contact therebetween.
Claim 3
Dependent Claim
121 words
Spark plug, especially for rotary piston internal combustion engines, comprising a center electrode, an insulator surrounding said center electrode, and a conductive housing surrounding said insulator, said housing consisting at least in part of an outer threaded part and an inner thermally conductive part of higher thermal conductivity than said outer threaded part in heat contact with said insulator for conducting heat longitudinally of said plug away from said threaded portion, said inner part of said housing being separated from said insulator along the major interior surface thereof so as to provide a gap between said inner part and said insulator, while being in thermally conductive communication with said insulator only at a specified portion thereof to provide heat contact therebetween.
Claim 4
Dependent Claim
121 words
Spark plug, especially for rotary piston internal combustion engines, comprising a center electrode, an insulator surrounding said center electrode, and a conductive housing surrounding said insulator, said housing consisting at least in part of an outer threaded part and an inner thermally conductive part of higher thermal conductivity than said outer threaded part in heat contact with said insulator for conducting heat longitudinally of said plug away from said threaded portion, said inner part of said housing being separated from said insulator along the major interior surface thereof so as to provide a gap between said inner part and said insulator, while being in thermally conductive communication with said insulator only at a specified portion thereof to provide heat contact therebetween.
Claim 5
Dependent Claim
79 words
Spark plug, as defined in claim 1, wherein said inner part of said housing includes an inwardly directed annular projection, and wherein a thermally conductive seal is provided between said insulator and said inwardly directed annular projection of said inner part of said housing providing said heat contact between said insulator and said inner part of said housing, so that said insulator and said inner part of said housing are bridged only by said seal and said annular projection.
Claim 6
Dependent Claim
29 words
Spark plug, as defined in claim 2, wherein said housing is provided with a shoulder portion spaced from said threaded part and providing a support surface for said plUg.
Claim 7
Dependent Claim
30 words
Spark plug, as defined in claim 3, wherein said inner part of said housing is made of a material selected from a group essentially consisting of copper and copper alloys.
Claim 8
Dependent Claim
47 words
Spark plug, as defined in claim 1, wherein one end of said housing is positioned adjacent an exposed end of said center electrode thereby forming a discharge gap therebetween, said inner and outer parts of said housing being provided at the end thereof forming said discharge gap.
Claim 9
Dependent Claim
38 words
Spark plug, as defined in claim 2, wherein said housing is provided with an outer shoulder portion spaced from said threaded part and forming a support surface for said plug communicating with said inner part of said housing.
Claim 10
Dependent Claim
30 words
Spark plug, as defined in claim 6, wherein said inner part of said housing is made of a material selected from a group essentially consisting of copper and copper alloys.
Claim 11
Dependent Claim
24 words
Spark plug, as defined in claim 1, wherein said inner and outer housing parts are annular concentric layers forming one end of said housing.
Claim 12
Dependent Claim
23 words
Spark plug, as defined in claim 8, wherein said outer part is made of steel and said inner part is made of copper.
Claim 13
Dependent Claim
39 words
Spark plug, as defined in claim 3, wherein said inner part of said housing extends only from the area of said shoulder portion to beyond said inwardly directed annular projection to an area adjacent the end of said insulator.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-05 | 1976-09-04 | 1977-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-05 | 1980-09-04 | 1981-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-05 | 1984-09-04 | 1985-03-06 | $7700.00 | Window Closed / Lapsed |