EP0633637A1 - A spark plug - Google Patents
A spark plug Download PDFInfo
- Publication number
- EP0633637A1 EP0633637A1 EP94110340A EP94110340A EP0633637A1 EP 0633637 A1 EP0633637 A1 EP 0633637A1 EP 94110340 A EP94110340 A EP 94110340A EP 94110340 A EP94110340 A EP 94110340A EP 0633637 A1 EP0633637 A1 EP 0633637A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- layer
- insulating element
- metal body
- plug according
- 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.)
- Withdrawn
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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
- H01T13/38—Selection of materials for insulation
-
- 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
- H01T13/14—Means for self-cleaning
Definitions
- the present invention relates to spark plugs for internal combusion engines with controlled ignition.
- the invention relates to a spark plug of the type comprising: an outer tubular metal body, a tubular insulating element disposed in the body, a central electrode which extends through the insulating element and projects axially beyond the end of the insulating element which faces the combustion chamber in use, and at least one earth electrode which extends from the outer metal body towards the side surface of the portion of the central electrode which projects from the insulator.
- An object of the invention is to provide a spark plug of the type specified above which prevents the deposition of carbon particles on the end of the ceramic insulating element.
- the object of the present invention is to provide a spark plug for internal combustion engines with controlled ignition which is highly resistant to fouling during the pre-sale life of the motor-vehicle in which it is mounted.
- the plug 1 comprises, in known manner, an outer tubular metal body 2, a portion 2' of which is threaded externally.
- An end portion 3a of the insulating element 3 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 beyond the end 3a of the insulating element.
- a conductor core 5 is also disposed in the insulating element 3. One end of the core projects axially from the insulating element 3 and forms an electrical connection terminal 6.
- the plug 1 also comprises one (or more) substantially arcuate earth electrodes 9 which are connected (for example, by welding) to the annular end surface of the metal body 2 and the ends of which face the central electrode 4.
- moisture and carbon particles are deposited on the surfaces 11 of the insulating element 3 which are directly exposed to the atmosphere of the combustion chamber near the central electrode 4 or which face the outer tubular metal body 2, and the moisture and carbon particles stick to the rough ceramic surface, forming a continuous electrically-conductive layer which, as already stated, may short-circuit the central electrode 4 to the metal body 2 at high voltages, preventing discharge to the earth electrode 9 and consequently rendering the plug unserviceable.
- a covering layer 13 of waterproof and anti-adhesive material for example of fluorocarbon polymer or a Polytetrafluoroethylene dispersion (Teflon Oil) on the walls 11 drastically reduces fouling, by preventing the binding of the carbon particles by virtue of the waterproofing and anti-adhesive properties of the aforementioned substances.
- the layer 13 of waterproof and anti-adhesive material may be deposited by the usual spraying, mechanical application, or immersion techniques, possibly followed by a hot cross-linking treatment.
- the layer 13 of waterproof and anti-adhesive material is conveniently a few ⁇ m (microns) thick.
- the thickness of the coating material, its chemical composition, and/or the application techniques may be varied.
Landscapes
- Spark Plugs (AREA)
Abstract
The plug (1) has a layer (13) of fluorocarbon polymer on the surfaces (11) of the insulating element (3) which are directly exposed to the atmosphere near the central electrode (4) and/or which face the outer tubular metal body (2) so as to prevent the insulating element (3) from being fouled by carbon residues.
Description
- The present invention relates to spark plugs for internal combusion engines with controlled ignition.
- More specifically, the invention relates to a spark plug of the type comprising:
an outer tubular metal body,
a tubular insulating element disposed in the body,
a central electrode which extends through the insulating element and projects axially beyond the end of the insulating element which faces the combustion chamber in use, and
at least one earth electrode which extends from the outer metal body towards the side surface of the portion of the central electrode which projects from the insulator. - An object of the invention is to provide a spark plug of the type specified above which prevents the deposition of carbon particles on the end of the ceramic insulating element.
- As it is known, conventional spark plugs are subjected to very heavy use during the movement of the motor vehicles in which they are fitted in storage yards and, in general, during the short movements necessary to transport the motor vehicles from the place of construction to the commercial network, and this may lead to the insulator of the plug being fouled with carbon substances which may short-circuit the central electrode to the outer metal body with the result that it is impossibile to obtain useful sparks.
- The object of the present invention is to provide a spark plug for internal combustion engines with controlled ignition which is highly resistant to fouling during the pre-sale life of the motor-vehicle in which it is mounted.
- This object is achieved, according to the invention, by means of a spark plug for internal combustion engines with controlled ignition having the specific characteristics recited in the following claims.
- Further characteristics and advantages of the invention will become clear from the detailed description which follows with reference to the appended drawing provided purely by way of non-limiting example, in which a spark plug, partially sectioned along its longitudinal centreline is generally indicated 1.
- The plug 1 comprises, in known manner, an outer
tubular metal body 2, a portion 2' of which is threaded externally. - A substantially tubular element 3 of electrically insulating material, typically ceramic material, is disposed in the
body 2, in known manner. - An end portion 3a of the insulating element 3 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 beyond the end 3a of the insulating element.
- A conductor core 5 is also disposed in the insulating element 3. One end of the core projects axially from the insulating element 3 and forms an
electrical connection terminal 6. - The plug 1 also comprises one (or more) substantially arcuate earth electrodes 9 which are connected (for example, by welding) to the annular end surface of the
metal body 2 and the ends of which face thecentral electrode 4. - In the event of cold starting followed by travel over very short distances and subsequent stoppage for long periods, moisture and carbon particles are deposited on the
surfaces 11 of the insulating element 3 which are directly exposed to the atmosphere of the combustion chamber near thecentral electrode 4 or which face the outertubular metal body 2, and the moisture and carbon particles stick to the rough ceramic surface, forming a continuous electrically-conductive layer which, as already stated, may short-circuit thecentral electrode 4 to themetal body 2 at high voltages, preventing discharge to the earth electrode 9 and consequently rendering the plug unserviceable. - In order to prevent this, the Applicant has found that a covering
layer 13 of waterproof and anti-adhesive material, for example of fluorocarbon polymer or a Polytetrafluoroethylene dispersion (Teflon Oil) on thewalls 11 drastically reduces fouling, by preventing the binding of the carbon particles by virtue of the waterproofing and anti-adhesive properties of the aforementioned substances. - The
layer 13 of waterproof and anti-adhesive material may be deposited by the usual spraying, mechanical application, or immersion techniques, possibly followed by a hot cross-linking treatment. - The
layer 13 of waterproof and anti-adhesive material is conveniently a few µm (microns) thick. - Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the present invention.
- For example, the thickness of the coating material, its chemical composition, and/or the application techniques may be varied.
Claims (6)
- A spark plug comprising
an outer tubular metal body (2),
a tubular insulating element (3) disposed in the body (2),
a central electrode (4) which extends through the insulating element (3) and projects axially beyond the end (3a) of the insulating element (3) which faces the combustion chamber in use,
at least one earth electrode (9) which extends from the outer metal body (2) towards the side surface of the portion of the central electrode (4) which projects from the insulator (3),
characterized in that a layer (13) of waterproof and anti-adhesive material is deposited on the surfaces (11) of the insulating element (3) which are directly exposed to the atmosphere of the combustion chamber near the central electrode (4) and/or which face the outer tubular metal body (2). - A plug according to Claim 1, characterized in that the layer (13) is made of fluorocarbon polymer.
- A plug according to Claim 2, characterized in that the layer (13) is deposited by spraying.
- A plug according to Claim 2, characterized in that the layer (13) is deposited by mechanical application.
- A plug according to Claim 2, characterized in that the layer (13) is deposited by immersion,
- A plug according to Claims 3 to 5, characterized in that the layer (13) is subjected to a hot cross-linking treatment.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ITTO930494A IT1261082B (en) | 1993-07-06 | 1993-07-06 | IGNITION CANDLE |
ITTO930494 | 1993-07-06 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0633637A1 true EP0633637A1 (en) | 1995-01-11 |
Family
ID=11411607
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94110340A Withdrawn EP0633637A1 (en) | 1993-07-06 | 1994-07-04 | A spark plug |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0633637A1 (en) |
IT (1) | IT1261082B (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3152877C2 (en) * | 1980-07-22 | 1985-08-14 | Ngk Spark Plug Co., Ltd., Nagoya, Aichi | Spark plug |
JPH01231281A (en) * | 1988-03-08 | 1989-09-14 | Ngk Spark Plug Co Ltd | Ignition plug with excellent anti-pollution property |
US4937484A (en) * | 1988-05-16 | 1990-06-26 | Nippondenso Co., Ltd. | Sparking plug |
EP0390065A1 (en) * | 1989-03-28 | 1990-10-03 | NGK Spark Plug Co. Ltd. | Spark plug for internal combustion engine |
EP0497189A2 (en) * | 1991-01-23 | 1992-08-05 | Matsushita Electric Industrial Co., Ltd. | Water- and oil-repelling absorbed film and method of manufacturing the same |
-
1993
- 1993-07-06 IT ITTO930494A patent/IT1261082B/en active IP Right Grant
-
1994
- 1994-07-04 EP EP94110340A patent/EP0633637A1/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3152877C2 (en) * | 1980-07-22 | 1985-08-14 | Ngk Spark Plug Co., Ltd., Nagoya, Aichi | Spark plug |
JPH01231281A (en) * | 1988-03-08 | 1989-09-14 | Ngk Spark Plug Co Ltd | Ignition plug with excellent anti-pollution property |
US4937484A (en) * | 1988-05-16 | 1990-06-26 | Nippondenso Co., Ltd. | Sparking plug |
EP0390065A1 (en) * | 1989-03-28 | 1990-10-03 | NGK Spark Plug Co. Ltd. | Spark plug for internal combustion engine |
EP0497189A2 (en) * | 1991-01-23 | 1992-08-05 | Matsushita Electric Industrial Co., Ltd. | Water- and oil-repelling absorbed film and method of manufacturing the same |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 13, no. 558 (E - 858)<3906> 12 December 1989 (1989-12-12) * |
Also Published As
Publication number | Publication date |
---|---|
ITTO930494A1 (en) | 1995-01-06 |
IT1261082B (en) | 1996-05-08 |
ITTO930494A0 (en) | 1993-07-06 |
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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): DE ES FR GB 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: 19950712 |