EP0549368B1 - Electrode pour bougie d'allumage et sa méthode de fabrication - Google Patents

Electrode pour bougie d'allumage et sa méthode de fabrication Download PDF

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Publication number
EP0549368B1
EP0549368B1 EP19920311818 EP92311818A EP0549368B1 EP 0549368 B1 EP0549368 B1 EP 0549368B1 EP 19920311818 EP19920311818 EP 19920311818 EP 92311818 A EP92311818 A EP 92311818A EP 0549368 B1 EP0549368 B1 EP 0549368B1
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EP
European Patent Office
Prior art keywords
slug
front surface
electrode
firing tip
spark 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
EP19920311818
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German (de)
English (en)
Other versions
EP0549368A3 (fr
EP0549368A2 (fr
Inventor
Wataru Matsutani
Junichi Kagawa
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.)
Niterra Co Ltd
Original Assignee
NGK Spark Plug Co Ltd
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
Priority claimed from JP4114809A external-priority patent/JPH05234662A/ja
Application filed by NGK Spark Plug Co Ltd filed Critical NGK Spark Plug Co Ltd
Publication of EP0549368A2 publication Critical patent/EP0549368A2/fr
Publication of EP0549368A3 publication Critical patent/EP0549368A3/xx
Application granted granted Critical
Publication of EP0549368B1 publication Critical patent/EP0549368B1/fr
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
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/39—Selection of materials for electrodes
    • 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

Definitions

  • This invention relates to an electrode for a spark plug and a method of manufacturing the electrode in which an erosion-resistant firing tip is welded to a front end of a composite the electrode.
  • a firing tip is welded to a front end of a center electrode or a ground electrode.
  • the front end of the electrode is made of nickel-based alloy, while the firing tip made of a noble metal such as platinum, palladium, iridium and alloys thereof.
  • the firing tip is usually secured to the front end of the center electrode or the ground electrode by means of electrical resistance welding so as to form a dispersion layer at an interface between the firing tip and the front end of the center electrode.
  • an object of the invention to provide an electrode for a spark plug and method of manufacturing the electrode in which a firing tip is secured to a front end of the electrode by means of laser welding to fuse the firing tip into the front end of the electrode sufficiently, and thus effectively preventing the firing tip from inadvertently falling off the electrode so as to contribute to an extended service life with relatively low cost.
  • WO-A-89/01717 which forms the basis of the precharacterising portion of amended claims 1, 2, 9 and 10, discloses a method of producing a spark plug in which a noble metal piece is laser beam welded to an end of a metal electrode. A diffusion layer is formed between the noble metal piece and the end of the metal electrode. The tip portion of the noble metal piece does not contain material from the metal electrode.
  • the firing tip is positively fused into the end surface of the metallic electrode body to increase the welding strength between the firing tip and the end surface of the metallic electrode body.
  • the laser beam welding is carried out such that the cone-shaped interface is formed between the firing tip and the end surface of the metallic electrode body so as to decentralize the thermal stress occurred at the interface between the firing tip and the end surface of the metallic electrode body when the electrode is alternately exposed to heat-and-cool cycle in a combustion chamber of an internal combustion engine.
  • the center electrode 1 has a composite column 10 and a firing tip 4 secured to a front end of the composite column 10.
  • the composite column 10 has a nickel-alloyed clad 2 (2.5 mm in diameter) which includes 15.0 wt % chromium iron and 8.0 wt % iron.
  • a heat-conductor core 3 (1.3 mm in diameter) concentrically embedded which is made of copper or silver.
  • a front end portion of the nickel-alloyed clad 2 is diametrically reduced to provide a straight neck portion 21 (1.0 mm in diameter).
  • the firing tip 4 is concentrically placed on a front end surface 21a of the straight neck portion 21, and secured to the front end surface 21a by means of a laser beam welding.
  • the firing tip 4 is made of a platinum-based alloy which includes 20.0 wt % iridium. At the time of carrying out the laser beam welding, whole the firing tip 4 is thermally melted so that the straight neck portion 21 is partly fused into the firing tip 4 in the range of 0.5 wt % to 80.0 wt %.
  • the firing tip may be made of an alloy of nickel (Ni) and iridium (Ir).
  • the firing tip may be made from pellet or powder.
  • composite column 10 is integrally made of a single elongated blank metal.
  • the center electrode 1 thus assembled is manufactured as follows:
  • composite column 10 is integrally made of a single elongated blank metal.
  • the firing tip 4 has a semi-spherical or frustoconical head 41 as shown at solid line and dotted lines in Fig. 4.
  • the firing tip 4 further has a wedge-shaped base foundation 42 stuck in the front end surface 21a of the straight neck portion 21 to form a cone-shaped or bullet-shaped interface 45 between the base foundation 42 and the front end surface 21a of the straight neck portion 21. This makes it possible to enlarge a welding area between the base foundation 42 and the front end surface 21a of the straight neck portion 21 so as to increase the welding strength compared to a welding area made by means of electrical resistance welding.
  • the straight neck portion 21 is partly fused into the firing tip 4 in the range of 0.5 wt % to 80.0 wt %.
  • a dispersion layer 43 is formed at the interface 45, a thickness of which extends from several ⁇ m to several hundreds of ⁇ m.
  • a dispersion degree of the noble metal of the firing tip 4 decreases as being away from the base foundation 42.
  • the optimum range of 0.5 wt % to 80.0 wt % is obtained by alternately changing the laser welding condition and analysing the firing tip 4 repeatedly through an X-ray examination.
  • the lower limit of the diameter (C) of the firing tip 4 is determined by considering endurance experiment test results as described in detail hereinafter.
  • Fig.5 shows a front portion of a spark plug 100 into which the center electrode 1 is incorporated.
  • the spark plug 100 has a metallic shell 6 in which a tubular insulator 7 is placed. Within an inner space of the insulator 7, is the center electrode located. From a front end of the metallic shell, is a ground electrode 5 extended to form a spark gap (G) between the ground electrode 5 and the firing tip 4.
  • G spark gap
  • the firing tip 4 is thermally transferable relationship with the heat-conductor core 3, a metallic packing (not shown), the metallic shell 6, a metallic gasket (not shown) and a cylinder head of the internal combustion engine.
  • Figs. 6a, 6b show a second embodiment of the invention.
  • the slug 4A is placed on the ground electrode 5, and laser welded to the ground electrode 5 so as to form the firing tip 4.
  • Fig. 6c shows a third embodiment of the invention.
  • the ground electrode 5 has a composite elongation 50 in which a metallic clad 51 is made of a nickel-based alloy which includes 15.0 wt % chromium and 8.0 wt % iron.
  • a metallic clad 51 is made of a nickel-based alloy which includes 15.0 wt % chromium and 8.0 wt % iron.
  • a heat-conductor core 52 coaxially embedded which is preferably made of copper, nickel and silver in an appropriate combination or alone.
  • Fig. 6d shows a fourth embodiment of the invention.
  • a plurality of ground electrodes 5 are provided around the front end of the center electrode 1.
  • Each front end surface 5a of the ground electrodes 5 opposes an outer surface of the straight neck portion 21.
  • the firing tip 4 is secured to each front end surface 5a of the ground electrodes 5 by means of the laser welding.
  • To the outer surface of the straight neck portion 21, the firing tip 4 is welded so as to oppose each front end surface 5a of the ground electrodes 5.
  • Fig. 7 shows a graph indicating how long the firing tip 4 endures depending on how much the nickel-alloyed clad 2 is fused into the firing tip 4.
  • the spark plug 100 at shown Fig. 5 mounted on a 2000 cc, six-cylinder engine which is alternately run in accordance with heat-and-cool cycle from full throttle (5000 rpm ⁇ 1 min.) to an idle operation (rpm ⁇ 1 min.).
  • Fig. 8 shows a graph indicating how the spark gap (G) changes depending on how much the nickel-alloyed clad 2 is fused into the firing tip 4.
  • G spark gap
  • Fig. 5 mounted on a 1600 cc, four-cylinder engine which is operated at full throttle (5500 rpm) with full load.
  • Fig. 9 shows a graph indicating how the spark gap (G) changes due to spark erosion depending on how the diameter (C) of the firing tip 4 varies.
  • an endurance experiment is carried out with the spark plug 100 at shown Fig. 5 mounted on a 2000 cc, six-cylinder engine which is operated at full throttle 5500 rpm with full load.
  • Fig. 10a shows a graph indicating how long the firing tip 4 endures depending on how deep (B) the firing tip 4 is penetrated into the front end surface 21a of the straight neck portion 21 of the nickel-alloyd clad 2.
  • the spark plug 100 at shown Fig. 5 mounted on a 2000 cc, six-cylinder engine which is alternately run in accordance with heat-and-cool cycle from full throttle (5000 rpm ⁇ 1 min.) to an idle operation (rpm ⁇ 1 min.).
  • Fig. 10b shows a graph indicating a relationship between an amount of spark erosion (mm) and a time period (Hr) required for the firing tip to fall off.
  • Fig. 10b It is found from Fig. 10b that the firing tip 4 does not fall off th ground electrode 5 with the elapse of 400 Hrs as opposed to the counterpart ground electrode in which a firing tip is secured to the ground electrode by means of the electrical resistance welding. It is also found from Fig. 10b that a counterpart firing tip falls off the ground electrode with the elapse of approx. 200 Hrs although an amount of spark erosion of the firing tip is slightly greater than that of the counterpart firing tip.
  • heat-concuctor core 52 of the ground electrode 5 may be left off in the third embodiment of the invention.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Spark Plugs (AREA)

Claims (16)

  1. Electrode (1, 5) pour bougie d'allumage (100), comprenant:
    une ébauche métallique allongée (1, 5), en alliage à base de nickel et comportant une surface antérieure;
    une pointe d'allumage (4) réalisée à partir d'une pastille (4A) en métal noble ou en alliage de métaux nobles, la pastille (4A) ayant été placée sur la surface antérieure de l'ébauche métallique allongée (1, 5) et ayant été soudée par faisceau laser de façon que la surface antérieure de l'ébauche métallique allongée (1, 5) soit partiellement amalgamée avec la pastille (4A);
       caractérisée en ce que la pastille (4A) a été entièrement fondue par la chaleur du soudage par faisceau laser de façon que la surface antérieure de l'ébauche métallique allongée (1, 5) soit partiellement amalgamée avec la pastille (4A) pour former une partie fondue à partir de laquelle la pointe d'allumage (4) est formée et qui contient le métal de la surface antérieure de l'ébauche métallique allongée (1, 5) dans une proportion comprise entre 0,5 % en poids et 80,0 % en poids.
  2. Electrode (1, 5) pour bougie d'allumage (100), comprenant:
    une colonne (10, 50) comportant une surface antérieure;
    une pointe d'allumage (4) réalisée à partir d'une pastille (4A) en métal noble ou en alliage de métaux nobles, la pastille (4A) ayant été placée sur la surface antérieure de la colonne (10, 50) et ayant été soudée par faisceau laser de façon que la surface antérieure soit partiellement amalgamée avec la pastille (4A);
       caractérisée en ce que la colonne (10, 50) est une colonne composite (10, 50) ayant une âme (3, 52) conductrice de la chaleur enrobée, par extrusion, d'une enveloppe métallique (2, 51), l'enveloppe métallique (2, 51) comportant la surface antérieure, et en ce que la pastille (4A) a été entièrement fondue par la chaleur du soudage par faisceau laser de façon que la surface antérieure de l'enveloppe métallique (2, 51) soit partiellement amalgamée avec la pastille (4A) pour former une partie fondue à partir de laquelle la pointe d'allumage (4) est formée et qui contient le métal de la surface antérieure de l'enveloppe métallique (2, 51) dans une proportion comprise entre 0,5 % en poids et 80,0 % en poids.
  3. Electrode (1, 5) pour bougie d'allumage (100) selon la revendication 2, dans lequel l'enveloppe métallique (2, 51) est en alliage à base de nickel qui contient 8,0 % en poids de fer et 15,0 % en poids de chrome.
  4. Electrode (1, 5) pour bougie d'allumage (100) selon la revendication 1, 2 ou 3, dans laquelle l'élément (4A) est en alliage à base de platine.
  5. Electrode (1, 5) pour bougie d'allumage (100) selon l'une quelconque des revendications précédentes, comprenant en outre, sous la pointe d'allumage (4), une couche de dispersion (43) dans laquelle le degré de dispersion du métal noble diminue à mesure qu'augmente la distance par rapport à la pointe d'allumage (4).
  6. Electrode (1, 5) pour bougie d'allumage (100) selon l'une quelconque des revendications précédentes, dans laquelle le diamètre de la pointe d'allumage (4) est supérieur à 0,3 mm mais inférieur au diamètre de la surface antérieure de l'enveloppe métallique (2, 51) ou de l'ébauche.
  7. Electrode (1, 5) pour bougie d'allumage (100) selon l'une quelconque des revendications précédentes, dans laquelle la pastille (4A) est sous la forme de boulettes ou de poudre.
  8. Electrode (1, 5) pour bougie d'allumage (100) selon l'une quelconque des revendications précédentes, dans laquelle une interface (45) de forme de conique est intercalée entre la pointe d'allumage (4) et la surface antérieure de l'enveloppe métallique (2, 51) ou de l'ébauche.
  9. Procédé de fabrication d'une électrode (1, 5) pour bougie d'allumage (100), comprenant les étapes consistant à:
    réaliser une ébauche métallique allongée (1, 5) en alliage à base de nickel et comportant une surface antérieure;
    placer une pastille (4A) sur la surface antérieure de l'ébauche métallique allongée (1, 5), la pastille (4A) étant en métal noble ou en alliage de métaux nobles; et
    souder l'élément (4A) par faisceau laser pour former une pointe d'allumage (4) de façon que la surface antérieure soit partiellement amalgamée avec la pastille (4A);
       caractérisé en ce que la chaleur du soudage par faisceau laser fait fondre toute la pastille (4A) de façon que la surface antérieure de l'ébauche métallique allongée (1, 5) soit partiellement amalgamée avec la pastille (4A) pour former une partie fondue à partir de laquelle la pointe d'allumage (4) est formée et qui contient le métal de la surface antérieure de l'ébauche métallique allongée (1, 5) dans une proportion comprise entre 0,5 % en poids et 80,0 % en poids.
  10. Procédé de fabrication d'une électrode (1, 5) pour bougie d'allumage (100), comprenant les étapes consistant à:
    réaliser une colonne (10, 50) comportant une surface antérieure;
    placer une pastille (4A) sur la surface antérieure, la pastille (4A) étant en métal noble ou en alliage de métaux nobles; et
    souder la pastille (4A) par faisceau laser pour former une pointe d'allumage (4) de façon que la surface antérieure soit partiellement amalgamée avec la pastille (4A);
       caractérisé en ce que la colonne (10, 50) est une colonne composite (10, 50) ayant une âme (3, 52) conductrice de la chaleur enrobée, par extrusion, d'une enveloppe métallique (2, 51), l'enveloppe métallique (2, 51) comportant la surface antérieure, et en ce que la chaleur du soudage par faisceau laser fait entièrement fondre la pastille (4A) de façon que la surface antérieure de l'enveloppe métallique (2, 51) soit partiellement amalgamée avec la pastille (4A) pour former une partie fondue à partir de laquelle la pointe d'allumage (4) est formée et qui contient le métal de la surface antérieure de l'enveloppe métallique (2, 51) dans une proportion comprise entre 0,5 % en poids et 80,0 % en poids.
  11. Procédé de fabrication d'électrode (1, 5) pour bougie d'allumage (100) selon la revendication 10, dans lequel la pastille (4A) est en alliage à base de platine, et l'enveloppe métallique (2, 51) est en alliage à base de nickel contenant 8,0 % en poids de fer et 15,0 % en poids de chrome.
  12. Procédé de fabrication d'électrode (1, 5) pour bougie d'allumage (100) selon la revendication 9, 10 ou 11, dans lequel la pastille (4A) se présente sous la forme de boulettes ou de poudre.
  13. Procédé de fabrication d'électrode (1, 5) pour bougie d'allumage (100) selon l'une quelconque des revendications 9 à 12, dans lequel les faisceaux laser sont tels qu'une interface (45) de forme conique est formée entre la pointe d'allumage (4) et la surface d'extrémité de l'enveloppe métallique (2, 51) ou de l'ébauche.
  14. Procédé de fabrication d'électrode (1, 5) pour bougie d'allumage (100) selon l'une quelconque des revendications 9 à 13, dans lequel les faisceaux laser sont émis en excitant un dispositif (L4) d'émission de faisceaux laser avec une source de courant de 340 V et sont appliqués une ou plusieurs fois avec une durée d'impulsions de 0,9 ms au moment de la réalisation du soudage par faisceau laser.
  15. Procédé de fabrication d'électrode (1, 5) pour bougie d'allumage (100) selon l'une quelconque des revendications 9 à 14, dans lequel le diamètre de la pointe d'allumage (4) est de préférence supérieur à 0,3 mm mais inférieur au diamètre de la surface antérieure de l'ébauche ou de l'enveloppe (2, 51).
  16. Bougie d'allumage (100) comprenant l'électrode (1, 5) selon l'une quelconque des revendications 1 à 8 ou une électrode (1, 5) fabriquée à l'aide d'un procédé selon l'une quelconque des revendications 9 à 15.
EP19920311818 1991-12-27 1992-12-24 Electrode pour bougie d'allumage et sa méthode de fabrication Expired - Lifetime EP0549368B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP34690191 1991-12-27
JP346901/91 1991-12-27
JP4114809A JPH05234662A (ja) 1991-12-27 1992-05-07 スパークプラグ用電極およびその製造方法
JP114809/92 1992-05-07

Publications (3)

Publication Number Publication Date
EP0549368A2 EP0549368A2 (fr) 1993-06-30
EP0549368A3 EP0549368A3 (fr) 1994-02-16
EP0549368B1 true EP0549368B1 (fr) 1998-05-27

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EP19920311818 Expired - Lifetime EP0549368B1 (fr) 1991-12-27 1992-12-24 Electrode pour bougie d'allumage et sa méthode de fabrication

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EP (1) EP0549368B1 (fr)
DE (1) DE69225686T2 (fr)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3425973B2 (ja) * 1992-08-19 2003-07-14 日本特殊陶業株式会社 スパークプラグおよびその製造方法
JP3344737B2 (ja) * 1992-09-10 2002-11-18 日本特殊陶業株式会社 スパークプラグの製造方法
JPH07249471A (ja) * 1994-03-10 1995-09-26 Ngk Spark Plug Co Ltd スパークプラグ
JP3121309B2 (ja) * 1998-02-16 2000-12-25 株式会社デンソー 内燃機関用のスパークプラグ
DE10015642A1 (de) * 2000-03-29 2001-10-18 Bosch Gmbh Robert Zündkerze für eine Brennkraftmaschine
DE10027651C2 (de) * 2000-06-03 2002-11-28 Bosch Gmbh Robert Elektrode, Verfahren zu deren Herstellung und Zündkerze mit einer derartigen Elektrode
DE10134671A1 (de) * 2001-07-20 2003-02-06 Bosch Gmbh Robert Verfahren zur Anbringung einer Edelmetallspitze auf einer Elektrode, Elektrode und Zündkerze
DE10149630C1 (de) * 2001-10-09 2003-10-09 Beru Ag Zündkerze und Verfahren zu ihrer Herstellung
DE10255187A1 (de) * 2002-11-27 2004-06-24 Robert Bosch Gmbh Verfahren zum Verbinden einer Elektrode mit einem Edelmetallabschnitt
WO2007149839A2 (fr) 2006-06-19 2007-12-27 Federal-Mogul Corporation Bougie d'allumage à petit diamètre / longue portée avec pointe d'allumage hémisphérique à bordure
US7851984B2 (en) 2006-08-08 2010-12-14 Federal-Mogul World Wide, Inc. Ignition device having a reflowed firing tip and method of construction
DE102011083452A1 (de) * 2011-09-26 2013-03-28 Robert Bosch Gmbh Zündkerze mit seitenangestellter Masseelektrode
US9130356B2 (en) 2012-06-01 2015-09-08 Federal-Mogul Ignition Company Spark plug having a thin noble metal firing pad
US9318879B2 (en) 2012-10-19 2016-04-19 Federal-Mogul Ignition Company Spark plug having firing pad
JP2023536781A (ja) 2020-06-18 2023-08-30 インニオ ジェンバッハー ゲーエムベーハー アンド コー オーゲー スパークプラグのためのアセンブリを製造する方法およびスパークプラグ

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4699600A (en) * 1981-04-30 1987-10-13 Nippondenso Co., Ltd. Spark plug and method of manufacturing the same
US4904216A (en) * 1983-09-13 1990-02-27 Ngk Spark Plug Co., Ltd. Process for producing the center electrode of spark plug
DE3727526A1 (de) * 1987-08-18 1989-03-02 Bosch Gmbh Robert Verfahren zum herstellen einer zuendkerze fuer brennkraftmaschinen

Also Published As

Publication number Publication date
EP0549368A3 (fr) 1994-02-16
DE69225686D1 (de) 1998-07-02
EP0549368A2 (fr) 1993-06-30
DE69225686T2 (de) 1998-09-17

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