EP0181476B1 - Procédé de fabrication d'une bougie d'allumage pour moteurs à combustion interne - Google Patents

Procédé de fabrication d'une bougie d'allumage pour moteurs à combustion interne Download PDF

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Publication number
EP0181476B1
EP0181476B1 EP85112350A EP85112350A EP0181476B1 EP 0181476 B1 EP0181476 B1 EP 0181476B1 EP 85112350 A EP85112350 A EP 85112350A EP 85112350 A EP85112350 A EP 85112350A EP 0181476 B1 EP0181476 B1 EP 0181476B1
Authority
EP
European Patent Office
Prior art keywords
metal body
insulator
tubular metal
spark plug
annular zone
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
EP85112350A
Other languages
German (de)
English (en)
Other versions
EP0181476A1 (fr
Inventor
Eliseo Longhi
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.)
Industrie Magneti Marelli SRL
Original Assignee
Fabbrica Italiana Magneti Marelli SpA
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 Fabbrica Italiana Magneti Marelli SpA filed Critical Fabbrica Italiana Magneti Marelli SpA
Priority to AT85112350T priority Critical patent/ATE50090T1/de
Publication of EP0181476A1 publication Critical patent/EP0181476A1/fr
Application granted granted Critical
Publication of EP0181476B1 publication Critical patent/EP0181476B1/fr
Anticipated expiration legal-status Critical
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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
    • H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
    • H01T21/02—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs of sparking plugs
    • 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
    • H01T13/56—Sparking plugs characterised by having component parts which are easily assembled or disassembled

Definitions

  • This invention relates to a method of manufacturing a spark plug for internal combustion engines, particularly for motor vehicles, as described in the first part of claim 1 in which the assembly between metal body and ceramic insulation is obtained by rimming the body.
  • the insulating material is locked in tight seal relation on the inside of the body by means of rimming thetop end of the body on the insulator while the latter rests with a conical surface on a corresponding internal seat of the body itself.
  • Such a method has been used to manufacture spark plugs type CW7LP produced and distributed by the proprietor of the patent before the priority date.
  • the invention relates also to a method for manufacturing an external tubular metal body for such a spark plug.
  • the rimming operation can be obtained either by hot or cold working but in any case, to achieve a tight seal, the body is provided, under the hexagon, with an annular part of reduced section referred to infra as "collar" the function of which will also be explained hereafter.
  • the body In the case of rimming by hot working, the body is heated by allowing current to pass through it and the final rimming operation is effected as soon as the collar, in this case preheating collar, becomes incandescent.
  • the collar is obtained in the already pressed metal body by externally machining the body at a point below the hexagon.
  • the machining makes it possible to obtain an annular undercut in the body, but mainly to obtain a collar of very accurate thickness.
  • the part of the body comprised between the collar and the external seat maintains instead a greater thickness to provide a resting surface for the body on the engine, by means of a gasket.
  • the body requires adequate and successive finishing, i.e. turning, with a resulting increase in production costs of the spark plug.
  • the purpose of this invention is to provide a method of manufacturing a spark plug of the above mentioned type, but which does not require additional turning of the body, thereby affording a saving on labor and material.
  • Claim 2 describes a method for manufacturing an external tubular metal body for a spark plug manufactured according to Claim 1.
  • the spark plug manufactured by the method according to the invention has a body in which the outer diameter of the collar is equal to the outer diameter of the part comprised between the collar and the outer rest seat of the body and in which the internal diameter of the collar is greater than that of conventional spark plugs, which contributes substantially to determine the thickness of the collar itself.
  • the fabrication cost of the spark plug is approximately 30 percent lower because the only operation required is the pressing operation, which is now possible because the outer surface of the body comprised between the hexagon and the outer rest seat has no incompatible surfaces for an operation of this type.
  • the sizing of the outer seat is not affected because the outer collar is made thinner to a precise value which occurs at the expense of the widening of its port (i.e. the port at the level of the hexagon) and does not involve the underlying part of the body the thickness of which remains adequate.
  • number 10 identifies the ceramic insulating body of the spark plug and number 20 the metal body in which said insulating body is retained seal tight by rimming the top end or edge 21 of body 20.
  • the tight seal is provided both between said end 21 and top part 11 of insulator 10 and between internal seat 22 of body 20 and the corresponding conical surface 12 of insulator 10.
  • body 20 is provided, below hexagon 23, with an annular part or collar 24 with thickness "s" reduced with respect to that of the remaining part 25 comprised between said collar 24 and outer seat 26 of body 20.
  • Said thickness "s" is normally in the order of 1 millimeter.
  • Collar 24 is the part of body 20 that ensures, with its behaviour, a tight sealing of the metal body to the insulator, both in the case of hot and cold rimming.
  • body 20 is heated by the passage of an electric current between two electrodes connected respectively to edge 21 and outer seat 26.
  • the entire body 20, including annular collar 24, is obtained fully finished with a single pressing operation, and therefore does not require any further turning, and consequent loss of material is also avoided.
  • outer diameter 0, of collar 24 is equal to outer diameter D 2 of the portion 25 of the body comprised between said collar and outer seat 26 and because inside diameter D 3 of the collar and hence of the hole in body 20 at hexagon 23 is greater than that of known spark plugs with conventional metal body.
  • diameters D 1 and D 2 ensures that the body portion comprised between hexagon 23 and outer seat 26 presents on its external part a cylindrical surface which adapts well, like all other surfaces of the body, to a pressing operation.
  • part 25 of the body still has the necessary thickness to provide a seat 26 of adequate dimensions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Spark Plugs (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)

Claims (2)

1. Procédé de fabrication d'une bougie d'allumage pour moteurs à combustion interne comportant un isolateur (10) qui porte une électrode centrale et un corps métallique tubulaire (20) qui, à l'une de ses extrémités, présente une portion (25) qui déborde à l'extérieur et qui est monté sur l'isolateur (10); le procédé comportant les étapes consistant à
disposer de l'isolateur (10),
mettre en forme le corps métallique tubulaire (20) par une opération de pressage,
disposer du corps métallique tubulaire (20) présentant une zone annulaire intermédiaire (24) d'épaisseur réduite prédéterminée (s) inférieure à l'épaisseur des portions voisines du corps (20),
placer l'isolateur (10) à l'intérieur du corps métallique tubulaire (20),
fixer mécaniquement le corps métallique tubulaire (20) sur l'isolateur (10),
provoquer une déformation permanente de ladite zone annulaire (24) du corps métallique tubulaire (20) de façon à determiner une contraction axiale dudit corps métallique (20), resserrant ainsi de façon étanche ledit corps métallique (20) sur l'isolateur (10);
caractérisé en ce que, au co\rs de ladite opération de pressage, on conforme la portion du corps (20) qui va de ladite extrémité de ce corps à ladite zone annulaire intermédiaire (24) de façon que le diamètre intérieur (D3) de ladite zone annulaire intermédiaire (24) diffère du diamètre extérieur (D2) de la même zone (24) d'une valeur qui correspond à ladite épaisseur réduite prédéterminée (s).
2. Procédé de fabrication, pour une bougie d'allumage fabriquée selon la revendication 1, d'un corps métallique tubulaire extérieur (20) à fixer de façon étanche sur un isolateur (10) portant une électrode centrale dans une bougie d'allumage pour moteurs à combustion interne; le corps (20) présentant, à l'une de ses extrémités, une portion (25) débordant vers l'extérieur; le procédé comportant les étapes consistant à:
mettre en forme le corps métallique tubulaire (20) au moyen d'une opération de pressage, et
disposer dudit corps métallique tubulaire (20) présentant une zone annulaire intermédiaire (24) d'épaisseur réduite prédéterminée (s) inférieure à l'épaisseur des portions voisines du corps (20), ladite zone annulaire étant prévue pour être déformée en permanence dans la condition montée du corps métallique (20) de façon à provoquer une contraction axiale dudit corps métallique (20) pour le serrer de façon étanche sur l'isolateur (10);
caractérisé en ce qu'au cours de ladite opération de pressage, on conforme la portion du corps (20) qui va de ladite extrémité du corps à ladite zone annulaire intermédiaire (24) de façon que le diamètre intérieur (D3) d'une zone annulaire intermédiaire (24) de ce corps diffère du diamètre extérieur (D2) de la même zone (24) d'une valeur qui correspond à ladite épaisseur réduite prédéterminée (s).
EP85112350A 1984-11-07 1985-09-29 Procédé de fabrication d'une bougie d'allumage pour moteurs à combustion interne Expired - Lifetime EP0181476B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85112350T ATE50090T1 (de) 1984-11-07 1985-09-29 Verfahren zur herstellung einer zuendkerze fuer verbrennungsmotoren.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT2348284 1984-11-07
IT23482/84A IT1178625B (it) 1984-11-07 1984-11-07 Candela di accensione per motori a combustione interna, particolarmente di autoveicoli

Publications (2)

Publication Number Publication Date
EP0181476A1 EP0181476A1 (fr) 1986-05-21
EP0181476B1 true EP0181476B1 (fr) 1990-01-31

Family

ID=11207486

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85112350A Expired - Lifetime EP0181476B1 (fr) 1984-11-07 1985-09-29 Procédé de fabrication d'une bougie d'allumage pour moteurs à combustion interne

Country Status (6)

Country Link
EP (1) EP0181476B1 (fr)
JP (1) JPS61118990A (fr)
AT (1) ATE50090T1 (fr)
DE (1) DE3575822D1 (fr)
ES (1) ES8609834A1 (fr)
IT (1) IT1178625B (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5837858B2 (ja) * 2012-06-06 2015-12-24 日本特殊陶業株式会社 点火プラグ

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0071577A1 (fr) * 1981-07-30 1983-02-09 ESPADA ANSTALT, Universal Marketing Bougie d'allumage

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1570320A (en) * 1919-10-27 1926-01-19 Albert E Serewicz Spark plug and method of making same
DE433840C (de) * 1924-05-31 1926-09-07 Allg Elek Citaets Ges Fa Zuendkerze
US1662878A (en) * 1927-06-20 1928-03-20 George N Barcus Spark plug
CH317554A (de) * 1952-09-30 1956-11-30 Bosch Gmbh Robert Verfahren zum Fliesspressen von Hohlkörpern

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0071577A1 (fr) * 1981-07-30 1983-02-09 ESPADA ANSTALT, Universal Marketing Bougie d'allumage

Also Published As

Publication number Publication date
ATE50090T1 (de) 1990-02-15
IT8423482A1 (it) 1986-05-07
EP0181476A1 (fr) 1986-05-21
IT8423482A0 (it) 1984-11-07
ES8609834A1 (es) 1986-09-01
JPS61118990A (ja) 1986-06-06
IT1178625B (it) 1987-09-09
ES547590A0 (es) 1986-09-01
DE3575822D1 (de) 1990-03-08

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