EP0817341B1 - Spark plug - Google Patents
Spark plug Download PDFInfo
- Publication number
- EP0817341B1 EP0817341B1 EP97110583A EP97110583A EP0817341B1 EP 0817341 B1 EP0817341 B1 EP 0817341B1 EP 97110583 A EP97110583 A EP 97110583A EP 97110583 A EP97110583 A EP 97110583A EP 0817341 B1 EP0817341 B1 EP 0817341B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- alloy
- spark plug
- igniting portion
- central electrode
- igniting
- 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
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Classifications
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- 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
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- 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 a spark plug for use in internal combustion engines of the type as indicated in the preamble portion of claim 1.
- a spark plug of this type is disclosed in EP-A-0 243529.
- Ir is easy to oxidize and evaporate in a high temperature range of 900 to 1,000°C. Therefore, if it is directly used in the igniting portion of the electrode, it is more consumed by oxidation and evaporation than by spark. Therefore, the spark plug using Ir in the igniting portion of an electrode is highly durable under low-temperature conditions as in driving on city roads but their endurance drops considerably during continuous running at high speed.
- a spark plug according to the present invention is comprised of: a central electrode; an insulator provided exterior to the central electrode; a main metallic shell provided exterior to the insulator; a ground electrode coupled at one end to the main metallic shell and which has the other end disposed to face the central electrode; and an igniting portion that is secured to at least one of the central electrode and the ground electrode for forming a spark discharge gap; wherein the igniting portion is made of an alloy based on Ir which contains Rh in an amount ranging from 3 to 50 wt% (50 wt% being not inclusive).
- the igniting portion of an electrode which forms a spark discharge gap is made of an alloy that is mainly made of Ir and which contains an amount of Rh in the stated range. Therefore, the consumption due to oxidation and evaporation of the Ir component at high temperatures is effectively retarded to thereby realize a highly durable spark plug.
- the spark plug according to the present invention has a central electrode, an insulator provided exterior to the central electrode, a main metallic shell provided exterior to the insulator, a ground electrode coupled at one end to the main metallic shell and which has the other end disposed to face the central electrode, and an igniting portion that is secured to either the central electrode or the ground electrode or both for forming a spark discharge gap, wherein the igniting portion is made of an alloy based on Ir which contains Rh in an amount ranging from 3 to 50 wt% (50 wt% being not inclusive).
- the present inventors have found that if the igniting portion of an electrode which forms a spark discharge gap is made of an alloy that is mainly made of Ir and which contains an amount of Rh in the stated range, the consumption due to oxidation and evaporation of the Ir component at high temperatures is effectively retarded to thereby realize a highly durable spark plug.
- a chip made of a metal having the stated composition may be joined by welding to the ground electrode and/or the central electrode.
- the term "igniting portion" as used herein shall refer to that part of the joined chip which has not been subject to the effect of the compositional change due to welding (e.g., the portion other than that which has been alloyed with the constituent material of the ground or central electrode upon welding).
- the Rh content of the alloy is less than 3%, the effectiveness of Rh in retarding the oxidation and evaporation of Ir is insufficient to prevent premature consumption of the igniting portion. Hence, the endurance of the spark plug is reduced. In this case, the igniting portion is consumed primarily in the tip end face of the chip welded to the central electrode and/or the ground electrode. However, the lateral sides of the chip may also be consumed if the Rh content is reduced.
- the Rh content of the alloy is desirably adjusted to lie within such a range that the consumption of the igniting portion is unlikely to occur not only in the tip end face of the chip but also on its lateral sides.
- the Rh content of the alloy is 50 wt% or more, the melting point of the alloy will drop and the endurance of the spark plug will deteriorate accordingly.
- the Rh content of the alloy is preferably adjusted to lie within the range of 3 to 50 wt% (50 wt% being not inclusive), desirably 7 to 30 wt%, more desirably 15 to 25 wt%, most desirably 18 to 22 wt%.
- a spark plug 100 has a tubular main metallic shell 1, an insulator 2 fitted into the metallic shell 1 in such a way that the tip end 21 protrudes from the metallic shell 1, a central electrode 3 provided within the insulator 2 in such a way that the igniting portion 31 formed at the tip end protrudes from the insulator 2, and a ground electrode 4 coupled at one end to the main metallic shell 1 as by welding and which has the other end bent laterally such that its lateral side faces the tip end of the central electrode 3.
- the ground electrode 4 has an igniting portion 32 formed in such a way that it faces the igniting portion 31 of the central electrode 3; the clearance between the two igniting portions 31 and 32 forms a spark discharge gap g.
- the insulator 2 is a sinter of a ceramic material such as alumina or aluminum nitride as a main constituent, and it has an axial bore 6 through which the central electrode 3 is to be fitted.
- the main metallic shell 1 is a cylinderical form made of a metal such as a low-carbon steel and which provides a housing for the spark plug 100.
- the circumference of the metallic shell 1 has a threaded portion 7 formed to assist in the mounting of the spark plug 100 on an engine block (not shown).
- the main body 3a of the central electrode 3 and the main body 4a of the ground electrode 4 are both typically made of a Ni alloy.
- the igniting portion 31 of the central electrode 3 and the opposed firing portion 32 of the ground electrode 4 are both made of an alloy based on Ir and which contains Rh in an amount ranging from 3 to 50 wt% (50 wt% being not inclusive).
- the Rh content of the alloy is desirably adjusted to lie within a range of 7 to 30 wt%, more desirably 15 to 25 wt%, most desirably 18 to 22 wt%.
- the main body 3a of the central electrode 3 tapers at the tip end and its tip end face is formed flat.
- a disk-shaped chip having an alloy formula for the igniting portion 31 in placed on the flat tip end face and laser welding, electron beam welding, resistance welding or other suitable welding technique is applied to the periphery of the joined surfaces to torn a weld line W, whereby the chip is securely fixed to the tip end face of the central electrode 3 to form the igniting portion 31.
- a similar chip is placed on the ground electrode 4 in registry with the position of the igniting portion 31 and a weld line W is similarly formed on the periphery of the joined surfaces, whereby the chip is securely fitted to the ground electrode 4 to form the igniting portion 32.
- the chips may be formed from a molten material obtained by mixing the necessary alloy ingredients to give the stated formula and melting the mixture; alternatively, the chips may be formed from a sinter obtained by shaping into a compact a suitable alloy powder or a mixture of the powders of elemental metal components in specified proportions and sintering the compact.
- a raw material made of the molten alloy may be subjected to a working process including at least one of rolling, forging, drawing, cutting, shearing and blanking steps, whereby the chips are produced in a specified shape. Steps such as rolling, forging and cutting may be performed with the alloy being heated to a specified temperature (to effect "hot” or “warm” working). The temperature for these steps which is variable with the alloy composition may typically be at least 700°C.
- a molten alloy may be hot rolled to a sheet, which is hot blanked to chips of a specified shape; alternatively, the molten alloy may be hot rolled or forged to a wire or rod shape, which is cut to chips of a specified length.
- the iridium (Ir) which is the chief component of the chips has low ductility or malleability in its elemental form; however, in the presence of added Rh, the workability of the Ir is improved such that the resulting alloy can be rolled or forged into a sheet, a rod or a wire with great ease compared to the case where Rh is not added.
- defects such as cracking are less likely to occur in the raw alloy material being in the process of rolling or forging and this in turn contributes to improvements in the efficiency of chip production and the materials yield. It should be noted here that the workability of the raw alloy material will increase with increasing Rh addition.
- either one of the two opposed igniting portions 31 and 32 may be omitted. If this is the case, the spark discharge gap g is formed between the igniting portion 31 (or the opposed igniting portion 32) and the ground electrode 4 (or the central electrode 3).
- the spark plug 100 operates according to the following mode of action.
- the spark 100 is fitted on an engine block by means of the threaded portion 7 and used as a source to ignite an air-fuel mixture that is supplied into the combustion chamber.
- the igniting portion 31 and the opposed igniting portion 32 define the spark discharge gap g; since both igniting portions are made of the aforementioned alloy, their consumption due to the oxidation and evaporation of Ir is sufficiently retarded to ensure that the spark discharge gap g will not increase for a prolonged period, thereby extending the life of the spark plug 100.
- the result is shown in Fig. 3 in terms of the relationship between the Rh content of the alloy and the increase in the spark discharge gap.
- the result is shown in Fig. 5 in terms of the relationship between the Rh content of the alloy and the increase in the spark discharge gap.
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Spark Plugs (AREA)
- Ignition Installations For Internal Combustion Engines (AREA)
Description
- The present invention relates to a spark plug for use in internal combustion engines of the type as indicated in the preamble portion of
claim 1. A spark plug of this type is disclosed in EP-A-0 243529. - Conventional spark plugs for use in internal combustion engines such as automotive engines have the igniting portion formed of a platinum (Pt) alloy chip welded to the tip end of an electrode in order to improve its resistance to spark consumption. However, in view of the high cost of platinum, it has been proposed to use less expensive iridium (Ir) as a chip material.
- A problem with the use of Ir as a material to constitute the igniting portion of the spark plug is that Ir is easy to oxidize and evaporate in a high temperature range of 900 to 1,000°C. Therefore, if it is directly used in the igniting portion of the electrode, it is more consumed by oxidation and evaporation than by spark. Therefore, the spark plug using Ir in the igniting portion of an electrode is highly durable under low-temperature conditions as in driving on city roads but their endurance drops considerably during continuous running at high speed.
- It is an object of the present invention to provide a spark plug having an igniting portion chiefly made of Ir and which yet is sufficiently resistant to consumption by oxidation and evaporation of the Ir component at elevated temperatures to assure high endurance not only during driving on city roads but also during continuous running at high speed.
- The above object is achieved by the subject matter of
claim 1. - A spark plug according to the present invention is comprised of: a central electrode; an insulator provided exterior to the central electrode; a main metallic shell provided exterior to the insulator; a ground electrode coupled at one end to the main metallic shell and which has the other end disposed to face the central electrode; and an igniting portion that is secured to at least one of the central electrode and the ground electrode for forming a spark discharge gap; wherein the igniting portion is made of an alloy based on Ir which contains Rh in an amount ranging from 3 to 50 wt% (50 wt% being not inclusive).
- According to the present invention, the igniting portion of an electrode which forms a spark discharge gap is made of an alloy that is mainly made of Ir and which contains an amount of Rh in the stated range. Therefore, the consumption due to oxidation and evaporation of the Ir component at high temperatures is effectively retarded to thereby realize a highly durable spark plug.
- In the accompanying drawings:
- Fig. 1 is a partial front sectional view of the spark plug of the invention;
- Fig. 2 is a sectional view showing enlarged the essential part of the same spark plug;
- Fig. 3 is a graph showing the relationship between the Rh content of the alloy forming the igniting portions of the spark plug and the increase in the spark discharge gap (in Example 1 under condition A);
- Fig. 4 is a graph showing the relationship between the Rh content of the alloy forming the igniting portions of the spark plug and the increase in the spark discharge gap (in Example 1 under condition B); and
- Fig. 5 is a graph showing the relationship between the Rh content of the alloy forming the igniting portions of the spark plug and the increase in the spark discharge gap (in Example 1 under condition C).
-
- Detailed description of the present invention will be described as follows.
- The spark plug according to the present invention has a central electrode, an insulator provided exterior to the central electrode, a main metallic shell provided exterior to the insulator, a ground electrode coupled at one end to the main metallic shell and which has the other end disposed to face the central electrode, and an igniting portion that is secured to either the central electrode or the ground electrode or both for forming a spark discharge gap, wherein the igniting portion is made of an alloy based on Ir which contains Rh in an amount ranging from 3 to 50 wt% (50 wt% being not inclusive).
- The present inventors have found that if the igniting portion of an electrode which forms a spark discharge gap is made of an alloy that is mainly made of Ir and which contains an amount of Rh in the stated range, the consumption due to oxidation and evaporation of the Ir component at high temperatures is effectively retarded to thereby realize a highly durable spark plug.
- In order to form the igniting portion, a chip made of a metal having the stated composition may be joined by welding to the ground electrode and/or the central electrode. The term "igniting portion" as used herein shall refer to that part of the joined chip which has not been subject to the effect of the compositional change due to welding (e.g., the portion other than that which has been alloyed with the constituent material of the ground or central electrode upon welding).
- If the Rh content of the alloy is less than 3%, the effectiveness of Rh in retarding the oxidation and evaporation of Ir is insufficient to prevent premature consumption of the igniting portion. Hence, the endurance of the spark plug is reduced. In this case, the igniting portion is consumed primarily in the tip end face of the chip welded to the central electrode and/or the ground electrode. However, the lateral sides of the chip may also be consumed if the Rh content is reduced. In such an extreme situation, the cross-sectional area of the chip through which a current is applied to cause spark discharge will decrease and the applied electric field tends to concentrate on the tip end face of the chip, whereby the consumption of the igniting portion will proceed at an accelerated rate and the life of the spark plug comes to an end prematurely. Therefore, the Rh content of the alloy is desirably adjusted to lie within such a range that the consumption of the igniting portion is unlikely to occur not only in the tip end face of the chip but also on its lateral sides. On the other hand, if the Rh content of the alloy is 50 wt% or more, the melting point of the alloy will drop and the endurance of the spark plug will deteriorate accordingly. Therefore, the Rh content of the alloy is preferably adjusted to lie within the range of 3 to 50 wt% (50 wt% being not inclusive), desirably 7 to 30 wt%, more desirably 15 to 25 wt%, most desirably 18 to 22 wt%.
- Embodiments of the invention will now be described with reference to the accompanying drawings as follows.
- Fig. 1 shows an embodiment of the present invention. In the drawing, a
spark plug 100 has a tubular mainmetallic shell 1, aninsulator 2 fitted into themetallic shell 1 in such a way that thetip end 21 protrudes from themetallic shell 1, acentral electrode 3 provided within theinsulator 2 in such a way that theigniting portion 31 formed at the tip end protrudes from theinsulator 2, and aground electrode 4 coupled at one end to the mainmetallic shell 1 as by welding and which has the other end bent laterally such that its lateral side faces the tip end of thecentral electrode 3. Theground electrode 4 has anigniting portion 32 formed in such a way that it faces theigniting portion 31 of thecentral electrode 3; the clearance between the twoigniting portions - The
insulator 2 is a sinter of a ceramic material such as alumina or aluminum nitride as a main constituent, and it has anaxial bore 6 through which thecentral electrode 3 is to be fitted. The mainmetallic shell 1 is a cylinderical form made of a metal such as a low-carbon steel and which provides a housing for thespark plug 100. The circumference of themetallic shell 1 has a threadedportion 7 formed to assist in the mounting of thespark plug 100 on an engine block (not shown). - The
main body 3a of thecentral electrode 3 and themain body 4a of theground electrode 4 are both typically made of a Ni alloy. Theigniting portion 31 of thecentral electrode 3 and theopposed firing portion 32 of theground electrode 4 are both made of an alloy based on Ir and which contains Rh in an amount ranging from 3 to 50 wt% (50 wt% being not inclusive). The Rh content of the alloy is desirably adjusted to lie within a range of 7 to 30 wt%, more desirably 15 to 25 wt%, most desirably 18 to 22 wt%. - As shown in Fig. 2, the
main body 3a of thecentral electrode 3 tapers at the tip end and its tip end face is formed flat. A disk-shaped chip having an alloy formula for the ignitingportion 31 in placed on the flat tip end face and laser welding, electron beam welding, resistance welding or other suitable welding technique is applied to the periphery of the joined surfaces to torn a weld line W, whereby the chip is securely fixed to the tip end face of thecentral electrode 3 to form theigniting portion 31. To form the opposedigniting portion 32, a similar chip is placed on theground electrode 4 in registry with the position of the ignitingportion 31 and a weld line W is similarly formed on the periphery of the joined surfaces, whereby the chip is securely fitted to theground electrode 4 to form theigniting portion 32. The chips may be formed from a molten material obtained by mixing the necessary alloy ingredients to give the stated formula and melting the mixture; alternatively, the chips may be formed from a sinter obtained by shaping into a compact a suitable alloy powder or a mixture of the powders of elemental metal components in specified proportions and sintering the compact. - If the chips are formed of a molten alloy, a raw material made of the molten alloy may be subjected to a working process including at least one of rolling, forging, drawing, cutting, shearing and blanking steps, whereby the chips are produced in a specified shape. Steps such as rolling, forging and cutting may be performed with the alloy being heated to a specified temperature (to effect "hot" or "warm" working). The temperature for these steps which is variable with the alloy composition may typically be at least 700°C.
- Stated more specifically, a molten alloy may be hot rolled to a sheet, which is hot blanked to chips of a specified shape; alternatively, the molten alloy may be hot rolled or forged to a wire or rod shape, which is cut to chips of a specified length. The iridium (Ir) which is the chief component of the chips has low ductility or malleability in its elemental form; however, in the presence of added Rh, the workability of the Ir is improved such that the resulting alloy can be rolled or forged into a sheet, a rod or a wire with great ease compared to the case where Rh is not added. Stated specifically, defects such as cracking are less likely to occur in the raw alloy material being in the process of rolling or forging and this in turn contributes to improvements in the efficiency of chip production and the materials yield. It should be noted here that the workability of the raw alloy material will increase with increasing Rh addition.
- If desired, either one of the two opposed
igniting portions - The
spark plug 100 operates according to the following mode of action. Thespark 100 is fitted on an engine block by means of the threadedportion 7 and used as a source to ignite an air-fuel mixture that is supplied into the combustion chamber. Theigniting portion 31 and the opposedigniting portion 32 define the spark discharge gap g; since both igniting portions are made of the aforementioned alloy, their consumption due to the oxidation and evaporation of Ir is sufficiently retarded to ensure that the spark discharge gap g will not increase for a prolonged period, thereby extending the life of thespark plug 100. - Specified amounts of Ir and Rh were mixed and melted to prepare alloy samples containing various amounts of Rh in the range of 0 to 60 wt%, with the balance being substantially composed of Ir (comparative samples: Rh = 0 and 60 wt%). The samples were hot rolled to sheets, from which disk-shaped chips measuring 0.7 mm in diameter and 0.5 mm in thickness were sliced by electrical discharge machining. A chip prepared from a molten alloy consisting of 13 wt% Ir and the balance Pt was also fabricated as a comparison. The thus fabricated chips were used to form the igniting
portion 31 of thespark plug 100 and the opposed igniting portion 32 (to provide a spark discharge gap g of 1.1 mm). The individual plugs were subjected to performance tests under the following conditions. - A six-cylinder gasoline engine (piston displacement = 3,000 cc) was fitted with the plug under test and operated continuously at full throttle for 300 hours at a rotational speed of 6,000 rpm (with the temperature of the central electrode rising to about 900°C); after the engine operation, the increase in the spark discharge gap g on the plug was measured. The result is shown in Fig. 3 in terms of the relationship between the Rh content of the alloy and the increase in the spark discharge gap.
- A four-cylinder gasoline engine (piston displacement = 2,000 cc) was fitted with the plug under test and operated for 1,000 hours through cycles, each consisting of 1-min idling, 30-min running et full throttle and a rotational speed of 3,500 rpm and 20-min running at half throttle and a rotational speed of 2,000 rpm, with the temperature of the central electrode rising to about 780°C; after the engine operation, the increase in the spark discharge gap g on the plug was measured. The result is shown in Fig. 4 in terms of the relationship between the Rh content of the alloy and the increase in the spark discharge gap.
- The result of the test under condition B indicates that the plugs using chips made of alloy formulae within the range of the invention experienced only small increases in the spark discharge gap g whereas the comparative plugs (Rh = 60 wt%, and Pt-Ir alloy) had the spark discharge gap increased markedly. The difference of the invention samples with respect to the comparisons was more pronounced under condition A of a higher load than condition B. It is also clear from Fig. 3 that the increase in the spark discharge gap decreased stepwise as the range of the Rh content varied from that of 3 to 50 wt% to 7 to 30 wt% and then to 15 to 25 wt%; in particular, the plugs using chips containing 15 to 25 wt% of Rh exhibited a very high level of endurance in spite of the hostile operating condition.
- It should also be noted that compared to a raw material that was solely composed of elemental Ir in the absence of Rh, the raw alloy materials containing 15 to 25 wt% of Rh tended to develop less cracking when the were hot rolled to sheets.
- Specified amounts of Ir and Rh were mixed and melted to prepare alloy samples containing Rh in 15, 18, 20, 22 and 25 wt%, with the balance being substantially composed of Ir. Chips were fabricated from these alloy samples and used to produce spark plugs as in Example 1. The plugs were subjected to a performance test under the following condition C which was more hostile than condition A employed in Example 1.
- A four-cylinder gasoline engine (piston displacement = 1,600 cc) was fitted with the plug under test and operated continuously at full throttle for 300 hours at a rotational speed of 6,250 rpm (with the temperature of the central electrode rising to about 950°C); after the engine operation, the increase in the spark discharge gap g on the plug was measured. The result is shown in Fig. 5 in terms of the relationship between the Rh content of the alloy and the increase in the spark discharge gap.
- It is clear from Fig. 5 that even under condition C which was more hostile than condition B, the plugs using the chips containing 18 to 22 wt% of Rh experienced smaller increases in the gap and proved to be more durable than the pugs using the chips containing Rh in amounts outside the stated range.
Claims (4)
- A spark plug comprising: a central electrode (3); an insulator (2) provided exterior to said central electrode; a metallic shell (1) provided exterior to said insulator; a ground electrode (4) having one end coupled to the main metallic shell and having another end facing said central electrode; and an igniting portion (31, 32) that is secured to at least one of said central electrode (3) and said ground electrode (4) for forming a spark discharge gap (g); wherein said igniting portion (31,32) is made of Rh containing alloy based on Ir,
characterised in that,
said alloy comprises Rh in an amount ranging from 3 - 50 wt. %; 50 wt. % not being inclusive. - A spark plug according to claim 1, wherein the alloy of which said igniting portion is made contains Rh in an amount ranging from 7 to 30 wt%.
- A spark plug according to claim 1, wherein the alloy of which said igniting portion is made contains Rh in an amount ranging from 15 to 25 wt%.
- A spark plug according to claim 1, wherein the alloy of which said igniting portion is made contains Rh in an amount ranging from 18 to 22 wt%.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99122560A EP0975075A3 (en) | 1996-06-28 | 1997-06-27 | A method for producing a spark plug |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18834796 | 1996-06-28 | ||
JP18834796 | 1996-06-28 | ||
JP188347/96 | 1996-06-28 | ||
JP335119/96 | 1996-11-28 | ||
JP33511996 | 1996-11-28 | ||
JP33511996A JP3461670B2 (en) | 1996-06-28 | 1996-11-28 | Spark plug and its manufacturing method |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99122560A Division EP0975075A3 (en) | 1996-06-28 | 1997-06-27 | A method for producing a spark plug |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0817341A1 EP0817341A1 (en) | 1998-01-07 |
EP0817341B1 true EP0817341B1 (en) | 2000-09-06 |
EP0817341B2 EP0817341B2 (en) | 2003-12-10 |
Family
ID=26504866
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99122560A Withdrawn EP0975075A3 (en) | 1996-06-28 | 1997-06-27 | A method for producing a spark plug |
EP97110583A Expired - Lifetime EP0817341B2 (en) | 1996-06-28 | 1997-06-27 | Spark plug |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99122560A Withdrawn EP0975075A3 (en) | 1996-06-28 | 1997-06-27 | A method for producing a spark plug |
Country Status (6)
Country | Link |
---|---|
US (1) | USRE43758E1 (en) |
EP (2) | EP0975075A3 (en) |
JP (1) | JP3461670B2 (en) |
KR (1) | KR100355886B1 (en) |
CN (1) | CN1059293C (en) |
DE (1) | DE69703011T3 (en) |
Families Citing this family (5)
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JP2002231412A (en) * | 2001-01-31 | 2002-08-16 | Ngk Spark Plug Co Ltd | Method of manufacturing spark plug and manufacturing device |
JP4121342B2 (en) * | 2001-11-13 | 2008-07-23 | 日本特殊陶業株式会社 | Metal part for plug with chromate coating and method for manufacturing the same |
BRPI0903497A2 (en) * | 2008-03-27 | 2015-06-23 | Ngk Spark Plug Co | Spark Plug and Method for Making Spark Plug |
DE102010032412B4 (en) * | 2010-07-27 | 2012-03-08 | Dkt Verwaltungs-Gmbh | Method for producing a starting electrode for a prechamber spark plug and prechamber spark plug |
JP7057935B2 (en) * | 2016-12-22 | 2022-04-21 | 石福金属興業株式会社 | Heat resistant Ir alloy |
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JP3562533B2 (en) | 1994-08-03 | 2004-09-08 | 株式会社デンソー | Spark plug for internal combustion engine |
GB9418705D0 (en) † | 1994-09-16 | 1994-11-16 | Johnson Matthey Plc | Improvements in high temperature articles |
GB2302367B (en) * | 1995-06-15 | 1998-11-25 | Nippon Denso Co | Spark plug for internal combustion engine |
JP2877035B2 (en) | 1995-06-15 | 1999-03-31 | 株式会社デンソー | Spark plug for internal combustion engine |
JPH09219274A (en) * | 1995-12-06 | 1997-08-19 | Denso Corp | Spark plug |
US5973443A (en) | 1996-05-06 | 1999-10-26 | Alliedsignal Inc. | Spark plug electrode tip for internal combustion engine |
JP3000955B2 (en) | 1996-05-13 | 2000-01-17 | 株式会社デンソー | Spark plug |
GB2479540A (en) | 2010-04-13 | 2011-10-19 | Adam Ford | Corrupting and erasing data on a storage device when computer casing is broken |
-
1996
- 1996-11-28 JP JP33511996A patent/JP3461670B2/en not_active Expired - Lifetime
-
1997
- 1997-06-26 KR KR1019970027677A patent/KR100355886B1/en not_active IP Right Cessation
- 1997-06-27 CN CN97113548A patent/CN1059293C/en not_active Expired - Lifetime
- 1997-06-27 EP EP99122560A patent/EP0975075A3/en not_active Withdrawn
- 1997-06-27 DE DE69703011T patent/DE69703011T3/en not_active Expired - Lifetime
- 1997-06-27 EP EP97110583A patent/EP0817341B2/en not_active Expired - Lifetime
-
2006
- 2006-07-31 US US11/495,524 patent/USRE43758E1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
EP0817341A1 (en) | 1998-01-07 |
JP3461670B2 (en) | 2003-10-27 |
CN1059293C (en) | 2000-12-06 |
EP0975075A2 (en) | 2000-01-26 |
KR100355886B1 (en) | 2002-12-26 |
EP0975075A3 (en) | 2000-02-02 |
DE69703011D1 (en) | 2000-10-12 |
EP0817341B2 (en) | 2003-12-10 |
JPH1074575A (en) | 1998-03-17 |
DE69703011T3 (en) | 2004-05-27 |
CN1170980A (en) | 1998-01-21 |
DE69703011T2 (en) | 2001-01-11 |
USRE43758E1 (en) | 2012-10-23 |
KR980006677A (en) | 1998-03-30 |
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