GB2039605A - Spark plug electrodes - Google Patents
Spark plug electrodes Download PDFInfo
- Publication number
- GB2039605A GB2039605A GB7934455A GB7934455A GB2039605A GB 2039605 A GB2039605 A GB 2039605A GB 7934455 A GB7934455 A GB 7934455A GB 7934455 A GB7934455 A GB 7934455A GB 2039605 A GB2039605 A GB 2039605A
- Authority
- GB
- United Kingdom
- Prior art keywords
- strip
- precious metal
- spark plug
- shell
- base metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000010970 precious metal Substances 0.000 claims abstract description 34
- 239000010953 base metal Substances 0.000 claims abstract description 26
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052709 silver Inorganic materials 0.000 claims abstract description 9
- 239000004332 silver Substances 0.000 claims abstract description 9
- 239000012212 insulator Substances 0.000 claims abstract description 8
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052737 gold Inorganic materials 0.000 claims abstract description 6
- 239000010931 gold Substances 0.000 claims abstract description 6
- 229910001316 Ag alloy Inorganic materials 0.000 claims abstract description 5
- 229910001020 Au alloy Inorganic materials 0.000 claims abstract description 5
- 239000003353 gold alloy Substances 0.000 claims abstract description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 10
- 229910045601 alloy Inorganic materials 0.000 claims description 7
- 239000000956 alloy Substances 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 239000010946 fine silver Substances 0.000 claims 1
- 239000002184 metal Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 230000003628 erosive effect Effects 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000009760 electrical discharge machining Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/39—Selection of materials for electrodes
Landscapes
- Spark Plugs (AREA)
Abstract
A spark plug comprises a threaded shell (12), an insulator, a centre electrode (13) positioned within a bore of the insulator, and a ground electrode (14) including a strip (16) of a precious metal selected from the group consisting of silver, silver alloys, gold and gold alloys, which strip overlays or is inlaid in a strip of base metal (15). The cross-sectional area of the precious metal overlay (16) or inlay is at least 15 percent that of the base metal strip. A portion of the exposed surface of the strip of precious metal is the part of the ground electrode which forms a spark gap with the centre electrode and another portion thereof is in thermal contact with the shell, whereby heat is transferred rapidly through the precious metal strip to the shell. <IMAGE>
Description
SPECIFICATION
An improved spark plug electrode
This invention relates to electrodes for spark plugs commonly fabricated entirely of a base metal, for example nickel or an alloy thereof. Because of high operating temperatures and arcing across the electrodes, the tips thereof are subject to severe pitting or erosion requiring frequent spark plug replacement. At the present state of the art, electrode wear or erosion is often a major limiting factor in spark plug life. Various ways have been suggested to use metals of high thermal conductivity to accelerate the dissipation of heat caused by the high operating temperatures and arcing to which electrodes are subjected in service.
U.S. Patent No. 1,515,866 granted November 18, 1924 to Louis F. Marten discloses spark plug electrodes plated with silver or a similar metal such as gold and copper. The patent suggests that, when a spark is generated across the electrodes, the heat is quickly dissipated through the coating, thus minimizing electrode temperature, providing greater resistance to oxidation, and minimizing pitting and erosion. However, copper is an unacceptable electrode material if posed in the combustion chamber because it corrodes readily. Even silver and gold applied by plating, are ineffective because it is practical to apply only a thin coating of either by this technique, inadequate to withstand the erosive effects of arc discharges and inadequate to transfer appreciable amounts of heat to an associated shell.
Rather than plating, U.S. Patent No.2,391,455 granted December 1945 to Franz R. Henzel; U.S.
Patent No.2,642,053 granted June16, 1953 to Arthur O. Dowson; and U.S. Patent No.3,146,370 granted
August 25,1964 to Robert J. Van Duyne et al suggest that only the tip of the ground electrode, i.e., that portion which is in spark gap relationship to the centre electrode, needs to be constructed by, or inlaid with, a material other than the usual base metal.
Still another type of electrode structure is suggested by such U.S. patents as No. 2,391,457 granted December 1945 to Chester F. Carlson; this patent discloses, as a spark plug electrode, a "composite wire or rod (which) comprises a core of a high thermal conductivity metal such as a silver, copper and their various alloys and a sheath of good resistance to spark erosion such as nickel."
The present invention is based on the discovery of a spark plug with an improved longer life ground electrode composed of a strip of base metal and a strip of precious metal.The spark plug comprising a threaded shell and an insulator assembly carried by said shell, a centre electrode positioned within a
bore of said insulator, a ground electrode structural
ly integral with said shell and positioned in spark gap
relationship with said centre electrode, said ground electrode being composed of a strip of base metal and a strip of a precious metal selected from the
group consisting of silver, silver alloys, gold, and
gold alloys there being means connecting said strip
of precious metal to said strip of base metal, the cross-sectional area of said precious metal strip being at least 15 volume percent that of said base metal strip, a portion of said precious metal strip being in spark gap relationship with said centre electrode and a portion thereof being in thermal contact with said shell, whereby heat is transferred rapidly through said precious metal strip to said shell, the preferred embodiment being one where the base metal is nickel or some alloy thereof, where the precious metal strip is pressure welded thereto, and where silver alloy and gold alloy strips have a coefficient of thermal conductivity, lambda, of at least 0.7.
The term "pressure welding" is used herein, and in the appended claims to describe a process wherein two metal strips are bonded together by an alloy formed by pressure and heat incident to the pressure at a temperature below the melting point of both strips of metal. Parts joined by this process are referred to herein as "pressure welded."
The term "lambda" is the quantity of heat in gram calories, transmitted per second through a plate of the material one centimeter thick and one square centimeter in area when the temperature difference between the two sides of the plate is one degree
Centigrate, i.e., g.-cal./(sec.) (sq.cm.) ("C./cm.). Lambda is used herein, and in the appended claims to refer to this coefficient.Unlike the plated silver coating, the strip of precious metal is a sufficient mass of metal to withstand the erosive effects of spark discharge at high operating temperatures and substantially to lower the temperature at which the electrode operates. The effectiveness of the precious metal at lowering electrode temperature requires that the strip extend the entire length of the ground electrode and into thermal contact with the shell, unlike the structures shown in the above-mentioned patents which concern only the tip of the ground electrode. Heat transfer through the precious metal is maximized because the strip extends from the tip or that portion in spark gap relationshjp with the centre electrode into thermal contact with the shell.
Costs are also minimized because of the discovery that the cross-sectional area of the precious metal inlay or overlay can be as little as 15 percent of that of the base metal strip.
It is an object of the present invention to provide a spark plug with an improved, longer life ground electrode composed of a strip of base metal and a strip of precious metal.
It is a further object to provide a spark plug with an improved, longer life ground electrode composed of a strip of base metal and a strip of precious metal wherein the size of the latter is minimized with respect to that of the base metal strip to reduce the expense thereof.
In the accompanying drawings:
Figure 1 is a vertical elevation of a spark plug in accordance with the invention.
Figure 2 is a perspective view showing the lower or firing end of the spark plug of Figure 1 wherein the ground electrode is composed of a strip of precious metal which overlays a strip of base metal and is exposed to the centre electrode.
Figure 3 is a perspective view similar to Figure 2, but showing a strip of precious metal which is inlaid in the strip of base metal.
Referring to Figure 1, a spark plug 10 comprises an insulator assembly 11 carried by a shell 12, a centre electrode 13 positioned within a bore (not illustrated) of the insulator, and a ground electrode 14structurally integral with the shell 12 and positioned in spark gap relationship with the centre electrode 13.
Referring to Figure 2, the ground electrode 14 is composed of a strip 15 of base metal and an overlay
16 of precious metal selected from the group consisting of silver, silver alloys, gold, and gold alloys, where the alloy strips have a coefficient of thermal conductivity, lambda, of at least 0.7. In the preferred embodiment, the strip 15 of base metal is nickel or an alloy thereof. The two strips 15 and 16 are pressure welded to one another.
A ground electrode 17 shown in Figure 3, is composed of a strip of base metal 18 and an inlaid strip 19 of precious metal. The cross-sectional area of the inlaid strip 19 is at least 15 percent that of the base metal strip 18. The strips 18 and 19 can be joined to one another by folding or creasing the base metal strip 15, placing a strip or wire of precious metal into the fold or crease, and finally pressure welding the composite.
Both Figure 2 and Figure 3 show the lower or firing end of the shell 12 wherein the strip 16 or 19 of precious metal extends the entire length of the ground electrode, one portion of the exposed surface being in spark gap relationship with the centre electrode 13 and another portion being in thermal contact with the shell 12, so that maximum heat transfer through the strip 16 or 19 of precious metal to the shell 12 is obtained. In one embodiment of the invention, the ground electrode 17 with a high purity (99.9 percent minimum) silver inlay (Figure 3) operated nearly 300"F. cooler and exhibited only approximately 20 percent of the metal loss exhibited by a conventional solid-nickel-alloy ground electrode.
Consequently, a spark plug constructed in accordance with this invention has a much longer and useful life than that of the ordinary spark plug.
Claims (7)
1. A spark plug comprising a threaded shell and an insulator assembly carried by said shell, a centre electrode positioned within a bore of said insulator, a ground electrode structurally integral with said shell and positioned in spark gap relationship with said centre electrode, said ground electrode being composed of a strip of base metal and a strip of a precious metal selected from the group consisting of silver, silver alloys, gold, and gold alloys there being means connecting said strip of precious metal to said strip of base metal, the cross-sectional area of said precious metal strip being at least 15 volume percent that of said base metal strip, a portion of said precious metal strip being in spark gap relationship with said centre electrode and a portion thereof being in thermal contact with said shell, whereby heat is transferred rapidly through said precious metal strip to said shell.
2. A spark plug as claimed in claim 1, wherein said precious metal strip is fine silver of 99.9 weight percent minimum purity.
3. A spark plug as claimed in claim 1 or 2, wherein said precious metal strip has a coefficient of thermal conductivity, lambda, of at least 0.7.
3. A spark plug as claimed in claim 1 or 2, wherein said precious metal strip has a coefficient of thermal conductivity, lambda, of at least 0.7.
4. A spark plug as claimed in any of claims 1 to 3, wherein said base metal strip is nickel or an alloy thereof.
5. A spark plug as claimed in any of claims 1 to 4, wherein said precious metal strip overlays said strip of base metal and is pressure welded thereto.
6. A spark plug as claimed in any of claims 1 to 4, wherein said precious metal strip is an inlay within said strip of base metal and is pressure welded thereto.
7. A spark plug substantially as described with reference to, and as illustrated in, Figures 1 and 2, or
Figure 3 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US96846178A | 1978-12-11 | 1978-12-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2039605A true GB2039605A (en) | 1980-08-13 |
Family
ID=25514300
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7934455A Withdrawn GB2039605A (en) | 1978-12-11 | 1979-10-04 | Spark plug electrodes |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5580288A (en) |
| AU (1) | AU5106179A (en) |
| BE (1) | BE879567A (en) |
| DE (1) | DE2938985A1 (en) |
| FR (1) | FR2444352A1 (en) |
| GB (1) | GB2039605A (en) |
| IT (1) | IT1162684B (en) |
| MX (1) | MX146818A (en) |
| NL (1) | NL7908583A (en) |
| SE (1) | SE7908205L (en) |
| ZA (1) | ZA795133B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3076502A1 (en) * | 2015-04-02 | 2016-10-05 | NGK Spark Plug Co., Ltd. | Ignition plug |
| DE102017218313A1 (en) | 2017-10-13 | 2019-04-18 | Ford Global Technologies, Llc | Spark plug, combustion chamber arrangement and motor vehicle |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2210103B (en) * | 1987-09-17 | 1992-02-05 | Champion Spark Plug Europ | Spark plug for internal combustion engine |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB691280A (en) * | 1951-01-29 | 1953-05-06 | Baker & Co Inc | Sparking plug electrode |
| DE2120250A1 (en) * | 1971-04-26 | 1972-11-02 | Beru-Werk Albert Ruprecht, 7140 Ludwigsburg | Spark plug with precious metal electrodes |
| DE2256823C3 (en) * | 1972-11-20 | 1975-07-24 | W.C. Heraeus Gmbh, 6450 Hanau | spark plug |
-
1979
- 1979-09-21 AU AU51061/79A patent/AU5106179A/en not_active Abandoned
- 1979-09-26 DE DE19792938985 patent/DE2938985A1/en not_active Withdrawn
- 1979-09-27 ZA ZA00795133A patent/ZA795133B/en unknown
- 1979-10-03 SE SE7908205A patent/SE7908205L/en not_active Application Discontinuation
- 1979-10-04 GB GB7934455A patent/GB2039605A/en not_active Withdrawn
- 1979-10-22 BE BE0/197767A patent/BE879567A/en unknown
- 1979-10-23 FR FR7926265A patent/FR2444352A1/en not_active Withdrawn
- 1979-10-30 IT IT50698/79A patent/IT1162684B/en active
- 1979-11-09 JP JP14531779A patent/JPS5580288A/en active Pending
- 1979-11-13 MX MX180024A patent/MX146818A/en unknown
- 1979-11-27 NL NL7908583A patent/NL7908583A/en not_active Application Discontinuation
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3076502A1 (en) * | 2015-04-02 | 2016-10-05 | NGK Spark Plug Co., Ltd. | Ignition plug |
| US9705291B2 (en) | 2015-04-02 | 2017-07-11 | Ngk Spark Plug Co., Ltd. | Ignition plug |
| DE102017218313A1 (en) | 2017-10-13 | 2019-04-18 | Ford Global Technologies, Llc | Spark plug, combustion chamber arrangement and motor vehicle |
Also Published As
| Publication number | Publication date |
|---|---|
| IT7950698A0 (en) | 1979-10-30 |
| MX146818A (en) | 1982-08-24 |
| BE879567A (en) | 1980-02-15 |
| DE2938985A1 (en) | 1980-06-19 |
| SE7908205L (en) | 1980-06-12 |
| ZA795133B (en) | 1981-01-28 |
| JPS5580288A (en) | 1980-06-17 |
| NL7908583A (en) | 1980-06-13 |
| AU5106179A (en) | 1980-06-19 |
| FR2444352A1 (en) | 1980-07-11 |
| IT1162684B (en) | 1987-04-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |