US3719850A - Spark plug especially for rotary piston internal combustion engines - Google Patents

Spark plug especially for rotary piston internal combustion engines Download PDF

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Publication number
US3719850A
US3719850A US00125253A US3719850DA US3719850A US 3719850 A US3719850 A US 3719850A US 00125253 A US00125253 A US 00125253A US 3719850D A US3719850D A US 3719850DA US 3719850 A US3719850 A US 3719850A
Authority
US
United States
Prior art keywords
housing
insulator
spark plug
inner part
plug
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.)
Expired - Lifetime
Application number
US00125253A
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English (en)
Inventor
M Schafer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daimler Benz AG
Original Assignee
Daimler Benz AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Daimler Benz AG filed Critical Daimler Benz AG
Application granted granted Critical
Publication of US3719850A publication Critical patent/US3719850A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01T13/02—Details
    • H01T13/16—Means for dissipating heat

Definitions

  • the invention relates to a spark plug, especially for rotary piston internal combustion engines of the type consisting essentially of a center electrode, an insulator and a plug housing which, at one end, serves as a ground electrode; whereby, between the insulator and the plug housing, a seal is provided and the plug housing supports itself in the engine housing by means of a shoulder in contact with the seal.
  • spark plugs of this type glow ignitions often occur because the spark plug becomes overheated as a result of insufficient heat removal. This is especially true with spark plugs used in rotary piston internal combustion engines, because in contrast to reciprocating piston internal combustion engines, the spark plug is surrounded to a lesser degree with cooling air as a result of the particular construction of the rotary piston engine.
  • the invention has the object to prevent overheating of the spark plug by providing an improved heat removing construction to thereby eliminate the cause for glow ignition.
  • the problem is solved in accordance with the present invention by forming the plug housing, at least between the shoulder and the seal, entirely or at least partly of a good heat-conducting material, preferably of copper or copper alloys.
  • the heat occurring in the spark plug is quickly conducted upwardly and absorbed by the engine housing through the plug shoulder. in this way, an accumulation of heat is avoided especially in the region of the seal between the insulator and plug housing where the center electrode and insulator transmit the largest amount of heat to the plug housing.
  • This heat can only be supplied to the engine housing in this area to a very small degree along the shortest path to the housing through the screw threads since the screw thread normally provided in this area, between the plug housing and the engine housing, is capable of satisfactory heat removal only in the relatively small area of the load-carrying portion of the threads.
  • the heat created in the area of the ground electrode may be more quickly removed when the plug housing between the ground electrode and the shoulder consists of a good heat-conducting material, which can conduct the heat upwardly to a point where it can be more efficiently transmitted to the engine housing.
  • the spark plug consists essentially of a center electrode 1, an insulator 2 and a metal plug housing 3 which is constructed at its lower end as a ground electrode 4.
  • a seal 5 is provided between the insulator 2 and the plug housing 3.
  • the plug housing 3 is screwed into the engine housing 7 of the rotary piston internal combustion engine by means of threaded portion 6 of the plug housing 3 and, at the same time, supports itself with a shoulder 8 and through the sealing ring 9 in the engine housing 7.
  • a cooling water space is designated at 10.
  • An opening 11 provides for the connection from the spark plug to a combustion chamber, not shown.
  • the plug housing 3 between the ground electrode 4 and shoulder 8 consists of a first radially inwardly directed, essentially annular layer 12 of copper and a second conventional layer of steel for the accommodation of the thread 6.
  • the higher heat-conductive layer 12, in the area of the ground electrode 4 and the seal 5 provides a good heat conducting path; whereas, the outer layer takes care of the required strength to effect securing of the plug in the housing.
  • the result is that heat is quickly carried through layer 12 to the upper portion of the plug housing 3 and through shoulder 8, the sealing ring 9 and the engine housing 7 into the cooling water in the colling water space 10; whereas, only a relatively small amount of heat flows through the threaded portion 6 to the engine housing 7.
  • 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.
  • said inner part of said housing includes an inwardly directed annular projection
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.

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  • Spark Plugs (AREA)
US00125253A 1970-03-17 1971-03-17 Spark plug especially for rotary piston internal combustion engines Expired - Lifetime US3719850A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702012516 DE2012516A1 (de) 1970-03-17 1970-03-17 Zündkerze, insbesondere fur Rotations kolben Brennkraftmaschinen

Publications (1)

Publication Number Publication Date
US3719850A true US3719850A (en) 1973-03-06

Family

ID=5765274

Family Applications (1)

Application Number Title Priority Date Filing Date
US00125253A Expired - Lifetime US3719850A (en) 1970-03-17 1971-03-17 Spark plug especially for rotary piston internal combustion engines

Country Status (4)

Country Link
US (1) US3719850A (show.php)
DE (1) DE2012516A1 (show.php)
FR (1) FR2084738A5 (show.php)
GB (1) GB1292019A (show.php)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4219003A (en) * 1977-09-16 1980-08-26 Toyo Kogyo Co., Ltd. Ignition means for rotary piston engines
US20060137642A1 (en) * 2003-07-10 2006-06-29 Bayerische Motoren Werke Aktiengesellschaft Plasma jet spark plug
US7477006B2 (en) * 2006-10-30 2009-01-13 Ngk Spark Plug Co., Ltd. Spark plug for internal combustion engine and method of manufacturing the same
WO2014001901A1 (en) * 2012-06-25 2014-01-03 Toyota Jidosha Kabushiki Kaisha Spark plug
WO2017186238A1 (de) * 2016-04-25 2017-11-02 Dkt Verwaltungs-Gmbh Zündkerze
DE102018107259B4 (de) 2017-04-12 2024-09-26 Niterra Co., Ltd. Zündkerze und Verbrennungsmotor umfassend dieselbe

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4219003A (en) * 1977-09-16 1980-08-26 Toyo Kogyo Co., Ltd. Ignition means for rotary piston engines
US20060137642A1 (en) * 2003-07-10 2006-06-29 Bayerische Motoren Werke Aktiengesellschaft Plasma jet spark plug
US7477008B2 (en) * 2003-07-10 2009-01-13 Bayerische Motoren Werke Aktiengesellschaft Plasma jet spark plug
US7477006B2 (en) * 2006-10-30 2009-01-13 Ngk Spark Plug Co., Ltd. Spark plug for internal combustion engine and method of manufacturing the same
WO2014001901A1 (en) * 2012-06-25 2014-01-03 Toyota Jidosha Kabushiki Kaisha Spark plug
WO2017186238A1 (de) * 2016-04-25 2017-11-02 Dkt Verwaltungs-Gmbh Zündkerze
DE102018107259B4 (de) 2017-04-12 2024-09-26 Niterra Co., Ltd. Zündkerze und Verbrennungsmotor umfassend dieselbe

Also Published As

Publication number Publication date
DE2012516A1 (de) 1971-09-30
FR2084738A5 (show.php) 1971-12-17
GB1292019A (en) 1972-10-11

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