EP0429407A1 - A spark plug for motor vehicles - Google Patents
A spark plug for motor vehicles Download PDFInfo
- Publication number
- EP0429407A1 EP0429407A1 EP90830498A EP90830498A EP0429407A1 EP 0429407 A1 EP0429407 A1 EP 0429407A1 EP 90830498 A EP90830498 A EP 90830498A EP 90830498 A EP90830498 A EP 90830498A EP 0429407 A1 EP0429407 A1 EP 0429407A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- bush
- plug according
- metal body
- electrode
- earth
- 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- Withdrawn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
Images
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
- H01T13/32—Sparking plugs characterised by features of the electrodes or insulation characterised by features of the earthed electrode
Definitions
- the present invention relates to a spark plug for motor vehicles of the type comprising a hollow metal body in which a central insulated electrode is disposed for connection to a high-tension electrical supply, and at least one earth electrode cooperating with the central electrode and carried by the metal body.
- the earth electrode (or electrodes) is constituted by a metal bar welded (usually by arc welding) to one end of the metal body.
- the welding of the earth electrode is a critical operation since it introduces great variability in the heat rating of the plug.
- the subject of the present invention is a spark plug for motor vehicles of the type specified above, characterised in that the earth electrode is formed on a bush fixed to the metal body.
- the plug according to the present invention also enables the earth electrode to be made of any material, particularly corrosion-resistant materials which by their nature are unsuitable for welding.
- the bush can be shaped so as to provide any number of earth electrodes and these electrodes can have many different shapes.
- a spark plug for motor vehicles comprises a hollow metal body 2 in which is disposed a central electrode 4 surrounded by an insulating cover 6, for example, of ceramic material.
- the central electrode 4 has an end 8 by means of which it is connected in known manner to a high-tension electrical supply usually constituted by the ignition coil of the vehicle (not shown).
- the metal body 2 has a threaded portion 10 for fixing the plug 1 to the engine head and a hexagonal portion 12 which can be engaged by a socket spanner (not shown).
- a metal bush 16 shown in greater detail in Figures 3 and 4, is fixed to one end 14 of the metal body 2, in the manner which will be explained further below, and surrounds an end portion of the central electrode 4.
- the bush 16 has three appendages 18 which constitute the earth electrodes of the plug 1 and are spaced at 120° from each other, their ends being bent so as to assume the configuration shown in Figure 1 after the bush 16 has been fixed to the body 2.
- the body 2 has an annular projection 20 which projects from the cylindrical wall 22 of its cavity.
- the projection 20 has a trapezoidal outline in cross-section, the inclined sides of which are inclined to a radial line A at an angle B of substantially 30° ( Figure 2).
- the end 14 of the metal body 2 is heated (for example, by induction) to cause it to expand so that the bush 16 can be inserted in the body 2.
- the cooling of the body 2 causes radial interference which retains the bush 16.
- the edge of the bush 16 which faces inwardly of the body 2, indicated 24, is then upset against a first bearing surface 26 of the projection 20 by means of a punch.
- the outer surface of the bush 16 has a chamfer 28 which is urged against a second bearing surface 30 of the projection 20.
- the insulating cover 6 of the central electrode 4 also has a chamfer 32 which is urged axially against the edge 24 of the bush 16 as a result of the fixing of the cover 6 in the body 2 by the upsetting of the edge 34 of the body 2 against the cover 6.
- the contact between the surface of the chamfer 32 and the edge 24 of the bush 16 creates a gas-tight zone which avoids the need for the sealing ring which is usually interposed between the insulating cover 6 and the metal body 2.
- FIG. 5 shows a second embodiment of the plug according to the present invention.
- the bush 16 has a single electrode 18 which is bent after the bush 16 has been fixed to the body 2.
- the bush 16 it is possible to produce plugs with any number of earth electrodes and these electrodes can be formed in many different shapes.
- the earth electrodes 18 can be made of a corrosion-resistant material, even though such a material is not suitable for welding.
Landscapes
- Spark Plugs (AREA)
Abstract
A spark plug for motor vehicles comprises a hollow metal body (2) in which a central insulated electrode (4) is disposed for connection to a high-tension electrical supply. A bush (16) is fixed to the metal body (2) and at least one earth electrode (18) which cooperates with the central electrode (4) is formed thereon.
Description
- The present invention relates to a spark plug for motor vehicles of the type comprising a hollow metal body in which a central insulated electrode is disposed for connection to a high-tension electrical supply, and at least one earth electrode cooperating with the central electrode and carried by the metal body.
- In known plugs, the earth electrode (or electrodes) is constituted by a metal bar welded (usually by arc welding) to one end of the metal body.
- The welding of the earth electrode is a critical operation since it introduces great variability in the heat rating of the plug.
- In order to resolve this problem, the subject of the present invention is a spark plug for motor vehicles of the type specified above, characterised in that the earth electrode is formed on a bush fixed to the metal body.
- As will become clear in the course of the detailed description which follows, in addition to the fact that it does not need weldingl the plug according to the present invention also enables the earth electrode to be made of any material, particularly corrosion-resistant materials which by their nature are unsuitable for welding. Moreover, the bush can be shaped so as to provide any number of earth electrodes and these electrodes can have many different shapes.
- Further characteristics and advantages of the present invention will become clear from the detailed description which follows with reference to the appended drawings, provided purely by way of non-limiting example, in which:
- Figure 1 is an axial section of a plug according to the present invention,
- Figure 2 is an axial section of a part of the plug according to the present invention,
- Figure 3 is an axial section of the element indicated III in Figure 2,
- Figure 4 is a view taken on the arrow IV of Figure 3,
- Figure 5 is a section corresponding to Figure 1, showing a second embodiment of the plug according to the present invention, and
- Figure 6 is a view of the part indicated by the arrow VI in Figure 1, on an enlarged scale.
- With reference to Figure 1, a spark plug for motor vehicles, indicated 1, comprises a
hollow metal body 2 in which is disposed acentral electrode 4 surrounded by aninsulating cover 6, for example, of ceramic material. Thecentral electrode 4 has an end 8 by means of which it is connected in known manner to a high-tension electrical supply usually constituted by the ignition coil of the vehicle (not shown). - In known manner, the
metal body 2 has a threadedportion 10 for fixing the plug 1 to the engine head and ahexagonal portion 12 which can be engaged by a socket spanner (not shown). - A
metal bush 16, shown in greater detail in Figures 3 and 4, is fixed to oneend 14 of themetal body 2, in the manner which will be explained further below, and surrounds an end portion of thecentral electrode 4. Thebush 16 has threeappendages 18 which constitute the earth electrodes of the plug 1 and are spaced at 120° from each other, their ends being bent so as to assume the configuration shown in Figure 1 after thebush 16 has been fixed to thebody 2. - As can be seen in Figures 1, 2 and 6, the
body 2 has anannular projection 20 which projects from thecylindrical wall 22 of its cavity. Theprojection 20 has a trapezoidal outline in cross-section, the inclined sides of which are inclined to a radial line A at an angle B of substantially 30° (Figure 2). - The
end 14 of themetal body 2 is heated (for example, by induction) to cause it to expand so that thebush 16 can be inserted in thebody 2. The cooling of thebody 2 causes radial interference which retains thebush 16. The edge of thebush 16 which faces inwardly of thebody 2, indicated 24, is then upset against a first bearingsurface 26 of theprojection 20 by means of a punch. The outer surface of thebush 16 has achamfer 28 which is urged against a second bearingsurface 30 of theprojection 20. - The
insulating cover 6 of thecentral electrode 4 also has achamfer 32 which is urged axially against theedge 24 of thebush 16 as a result of the fixing of thecover 6 in thebody 2 by the upsetting of theedge 34 of thebody 2 against thecover 6. The contact between the surface of thechamfer 32 and theedge 24 of thebush 16 creates a gas-tight zone which avoids the need for the sealing ring which is usually interposed between theinsulating cover 6 and themetal body 2. - Figure 5 shows a second embodiment of the plug according to the present invention. The parts which correspond to those described above are indicated by the same reference numerals. In this second embodiment, the
bush 16 has asingle electrode 18 which is bent after thebush 16 has been fixed to thebody 2. - By virtue of the
bush 16, it is possible to produce plugs with any number of earth electrodes and these electrodes can be formed in many different shapes. Moreover, theearth electrodes 18 can be made of a corrosion-resistant material, even though such a material is not suitable for welding.
Claims (9)
1. A spark plug for motor vehicles, comprising a hollow metal body (2) in which a central insulated electrode (4) is disposed for connection to a high-tension electrical supply, and at least one earth electrode (18) cooperating with the central electrode (4), characterised in that the earth electrode (18) is formed on a bush (16) fixed to the metal body (2).
2. A plug according to Claim 1, characterised in that the bush (16) is inserted with radial interference in one end of the metal body (2) and surrounds an end portion of the central electrode (4).
3. A plug according to Claim 2, characterised in that an annular projection (20) is formed on the inner cylindrical surface of the metal body (2) and has a first bearing surface (26) against which an edge (24) of the bush (16) facing inwardly of the metal body (2) is upset.
4. A plug according to Claim 3, characterised in that the insulating cover (6) of the central electrode (4) has a chamfer (32) which is urged axially against the bent edge (24) of the bush (16) so as to constitute a gas-tight zone.
5. A plug according to Claim 3, characterised in that a chamfer (28) is formed on the outer surface of the bush (16) and is urged against a second bearing surface (30) of the projection (20).
6. A plug according to Claim 3, characterised in that the annular projection (20) of the annular body (2) has a trapezoidal outline in cross-section, the inclined sides of which constitute the first and second bearing surfaces (26, 30).
7. A plug according to Claim 6, characterised in that the first and second bearing surfaces (26, 30) of the annular projection (20) are inclined to a radial line (A) at an angle (B) of between 15° and 45°.
8. A plug according to Claim 7, characterised in that the angle (B) of inclination of the first and second bearing surfaces (26, 30) to the radial line (A) is substantially 30°.
9. A plug according to any one of the preceding claims, characterised in that the bush (16) has three earth electrodes (18) spaced at 120° from each other.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT6796689 | 1989-11-07 | ||
IT67966A IT1238515B (en) | 1989-11-07 | 1989-11-07 | SPARK PLUG FOR MOTOR VEHICLES |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0429407A1 true EP0429407A1 (en) | 1991-05-29 |
Family
ID=11306798
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90830498A Withdrawn EP0429407A1 (en) | 1989-11-07 | 1990-10-30 | A spark plug for motor vehicles |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0429407A1 (en) |
JP (1) | JPH03165480A (en) |
IT (1) | IT1238515B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9306375B2 (en) | 2012-07-17 | 2016-04-05 | Ngk Spark Plug Co., Ltd. | Spark plug |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4965471B2 (en) * | 2008-01-23 | 2012-07-04 | 日本特殊陶業株式会社 | Spark plug |
CN104488151B (en) * | 2012-07-17 | 2017-02-22 | 日本特殊陶业株式会社 | Spark plug, and production method therefor. |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR563308A (en) * | 1923-02-22 | 1923-12-03 | Removable spark plug for internal combustion engines | |
FR765542A (en) * | 1933-03-04 | 1934-06-12 | Spark plug | |
FR1112548A (en) * | 1954-10-13 | 1956-03-15 | J M J Ets | Advanced spark plug |
-
1989
- 1989-11-07 IT IT67966A patent/IT1238515B/en active IP Right Grant
-
1990
- 1990-10-30 EP EP90830498A patent/EP0429407A1/en not_active Withdrawn
- 1990-10-31 JP JP2297018A patent/JPH03165480A/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR563308A (en) * | 1923-02-22 | 1923-12-03 | Removable spark plug for internal combustion engines | |
FR765542A (en) * | 1933-03-04 | 1934-06-12 | Spark plug | |
FR1112548A (en) * | 1954-10-13 | 1956-03-15 | J M J Ets | Advanced spark plug |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9306375B2 (en) | 2012-07-17 | 2016-04-05 | Ngk Spark Plug Co., Ltd. | Spark plug |
Also Published As
Publication number | Publication date |
---|---|
JPH03165480A (en) | 1991-07-17 |
IT8967966A0 (en) | 1989-11-07 |
IT8967966A1 (en) | 1991-05-07 |
IT1238515B (en) | 1993-08-18 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): BE DE ES FR GB IT SE |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19911130 |