EP0625813B1 - A spark plug - Google Patents

A spark plug Download PDF

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Publication number
EP0625813B1
EP0625813B1 EP94106786A EP94106786A EP0625813B1 EP 0625813 B1 EP0625813 B1 EP 0625813B1 EP 94106786 A EP94106786 A EP 94106786A EP 94106786 A EP94106786 A EP 94106786A EP 0625813 B1 EP0625813 B1 EP 0625813B1
Authority
EP
European Patent Office
Prior art keywords
layer
spark plug
plug according
annular element
central electrode
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
EP94106786A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0625813A1 (en
Inventor
Roberto Rossi
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.)
Federal Mogul Italy SRL
Original Assignee
Cooper Industries Italia 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 Cooper Industries Italia SpA filed Critical Cooper Industries Italia SpA
Publication of EP0625813A1 publication Critical patent/EP0625813A1/en
Application granted granted Critical
Publication of EP0625813B1 publication Critical patent/EP0625813B1/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
    • H01T13/46—Sparking plugs having two or more spark gaps
    • H01T13/467—Sparking plugs having two or more spark gaps in parallel connection
    • 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

Definitions

  • the present invention relates to spark plugs for internal combustion engines with controlled ignition.
  • the invention relates to a spark plug of the type comprising:
  • An object of the invention is to provide a spark plug of this type which is suitable for very much prolonged operation (a "long-life" plug).
  • “Long-life” plugs are known, the earth electrodes of which extend from the outer metal body of the plug to face the end surface or face of the central electrode according to a well-known geometrical arrangement. Layers of noble metal, typically platinum or an alloy thereof, are welded to this end surface of the central electrode and to the portion of the earth electrode which faces it, and, in use, the spark is struck between these layers.
  • the object of the present invention is to provide a "long-life" plug the cost of which is considerably reduced thus maintaining functionality and endurance characteristics just described.
  • a spark plug according to the invention for an internal combustion engine is generally indicated 1.
  • the plug comprises, in known manner, an outer, tubular metal body 2, a portion of which is threaded externally.
  • a substantially tubular element 3 of electrically insulating material, typically of ceramic material, ( Figure 2) is disposed in the body 2 in known manner.
  • An end portion 3a of the insulating element projects axially beyond the end of the metal body 2 which faces the combustion chamber in use.
  • a central electrode, indicated 4 extends through a portion of the insulating element 3 and projects axially beyond the end 3a of the insulating element.
  • a conductive core 5 is also disposed in the insulating element 3; one end of this core projects from the insulating element 3 axially and forms an electrical connection terminal 6.
  • a conductive or resistive sealing mastic is interposed between the central electrode 4 and the conductive core 5 within the insulating element 3.
  • annular element of metallic material onto which a rim 2a of the metal body 2 is turned over, is indicated 8 ( Figure 2).
  • the annular element 8 which is made, for example, of a nickel- or copper-based alloy, has a plurality of integral appendages 9 which extend from its inner edge towards the end portion 3a of the insulator in equiangularly spaced positions. These appendages constitute the earth electrodes of the plug.
  • annular element 8 with the integral appendages 9 which act as electrodes may be welded to the end of the outer metal body 2 of the plug, for example, by laser welding.
  • the central electrode 4 has a substantially disc-shaped end head 4a.
  • the annular element 10 is disposed around the central electrode 4 between the head 4a thereof and the end 3a of the insulating element 3 ( Figure 2). This annular element 10 may simply be fitted around the electrode and then clamped between the head 4a thereof and the insulator 3 or may be disposed around the stem of the central electrode 4 and then welded to the head 4a thereof.
  • the arrangement is such that, in operation, the sparks are struck between the annular element 10 and the earth electrodes 9.
  • Figure 4 shows a variant in which the plug 1 comprises one (or more) substantially arcuate earth electrodes 19 connected (for example, by welding) to the annular end surface of the metal body 2 with their ends facing the annular bimetal laminate element 10 which is welded to the central electrode 4.
  • the end surfaces of the earth electrodes 19 also partially face the ceramic insulating element 3 so that the plug is of the partial-surface discharge type.
  • the annular bimetal laminate element 10 has a smaller diameter than the end 3a of the ceramic insulating element 3.
  • Figures 5 and 6 show two embodiments similar to those shown in Figure 3 and Figure 4, respectively, but with the bimetal laminate element 10 projecting radially from the end 3a of the insulating element 3.
  • the annular element 10 may be formed by the hot or cold blanking of a bimetal laminate; the layer of noble material 10a is, for example, from 0.1 to 0.2 mm thick and the layer 10b of less expensive material is, for example, between 0.4 and 1 mm thick.
  • the layer 10a may be made of platinum, platinum-iridium, gold, gold-palladium, silver, or an alloy thereof.
  • the layer 10b may be made of nickel, or nickel-chrome, or of alloys thereof, for example, Inconel.
  • the annular element 10 may be replaced by portions of a ring or by a surfacing, also of bimetal laminate, as already described, thus achieving a considerable saving of material.
  • the formation of the annular element 10 as first described also allows the total thickness to be increased without greatly affecting costs, simply by increasing the thickness of the portion 10b which is of relatively less expensive material.
  • Such an increase in the thickness of the element 10 permits better and safer welding (for example, by laser) of the element 10 to the central electrode 4, at the same time improving the heat dissipation of the central electrode 4.

Landscapes

  • Spark Plugs (AREA)
EP94106786A 1993-05-19 1994-04-29 A spark plug Expired - Lifetime EP0625813B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO930344 1993-05-19
ITTO930344A IT1270362B (it) 1993-05-19 1993-05-19 Candela di accensione

Publications (2)

Publication Number Publication Date
EP0625813A1 EP0625813A1 (en) 1994-11-23
EP0625813B1 true EP0625813B1 (en) 1996-09-11

Family

ID=11411488

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94106786A Expired - Lifetime EP0625813B1 (en) 1993-05-19 1994-04-29 A spark plug

Country Status (4)

Country Link
EP (1) EP0625813B1 (it)
DE (1) DE69400504T2 (it)
ES (1) ES2092355T3 (it)
IT (1) IT1270362B (it)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5392490B2 (ja) * 2009-12-01 2014-01-22 ヤンマー株式会社 点火プラグ

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR497769A (fr) * 1919-04-02 1919-12-17 D Ussel Soc Ind Bougie d'allumage pour moteurs à explosions
GB578430A (en) * 1943-06-22 1946-06-27 Mallory Metallurg Prod Ltd Improvements in and relating to sparking plugs and the electrodes therefor
IT1241643B (it) * 1990-10-12 1994-01-25 Magneti Marelli Spa Candela di accensione

Also Published As

Publication number Publication date
ITTO930344A1 (it) 1994-11-19
IT1270362B (it) 1997-05-05
ES2092355T3 (es) 1996-11-16
EP0625813A1 (en) 1994-11-23
DE69400504T2 (de) 1997-03-20
DE69400504D1 (de) 1996-10-17
ITTO930344A0 (it) 1993-05-19

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