EP0549368B1 - An electrode for a spark plug and a method of manufacturing the same - Google Patents
An electrode for a spark plug and a method of manufacturing the same Download PDFInfo
- 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
- Authority
- 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
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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.
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Spark Plugs (AREA)
Description
Claims (16)
- An electrode (1,5) for a spark plug (100), comprising:an elongated blank metal (1,5) made of a nickel-based alloy and including a front surface;a firing tip (4) provided from a slug (4A) made of a noble metal or noble metal alloy, the slug (4A) having been placed on the front surface of the elongated blank metal (1,5) and having been laser beam welded so that the front surface of the elongate blank metal (1,5) is partly fused into the slug (4A);
- An electrode (1,5) for a spark plug (100), comprising:a column (10,50) including a front surface;a firing tip (4) provided from a slug (4A) made of a noble metal or noble metal alloy, the slug (4A) having been placed on the front surface of the column (10,50) and having been laser beam welded so that the front surface is partly fused into the slug (4A);
- An electrode (1,5) for a spark plug (100) according to claim 2, wherein the metallic clad (2,51) is made of a nickel-based alloy which includes 8.0 wt% iron and 15.0 wt% chromium.
- An electrode (1,5) for a spark plug (100) according to claim 1, 2 or 3 wherein the slug (4A) is made of a platinum-based alloy.
- An electrode (1,5) for a spark plug (100) according to any preceding claim, further comprising a dispersion layer (43) beneath the firing tip (4) in which a dispersion degree of the noble metal decreases with distance away from the firing tip (4).
- An electrode (1,5) for a spark plug (100) according to any preceding claim, wherein the diameter of the firing tip (4) is greater than 0.3 mm but smaller than the diameter of the front surface of the metallic clad (2,51) or blank.
- An electrode (1,5) for a spark plug (100) according to any preceding claim, wherein the slug (4A) is in the form of pellet or powder.
- An electrode (1,5) for a spark plug (100) according to any preceding claim, wherein a cone-shaped interface (45) is provided between the firing tip (4) and the front surface of the metallic clad (2,51) or blank.
- A method of manufacturing an electrode (1,5) for a spark plug (100) comprising the steps of:preparing an elongated blank metal (1,5) made of a nickel-based alloy and including a front surface;placing a slug (4A) on the front surface of the elongated blank metal (1,5), the slug (4A) being made of a noble metal or noble metal alloy; andlaser beam welding the slug (4A) to form a firing tip (4) so that the front surface is partly fused together with the slug (4A);
- A method of manufacturing an electrode (1,5) for a spark plug (100) comprising the steps of:providing a column (10,50) including a front surface;placing a slug (4A) on the front surface, the slug (4A) being made of a noble metal or noble metal alloy; andlaser beam welding the slug (4A) to form a firing tip (4) so that the front surface is partly fused together with the slug (4A);
- A method of manufacturing an electrode (1,5) for a spark plug (100) according to claim 10, wherein the slug (4A) is made of a platinum-based alloy, and the metallic clad (2,51) is made of a nickel-based alloy which includes 8.0 wt% iron and 15.0 wt% chromium.
- A method of manufacturing an electrode (1,5) for a spark plug (100) according to claim 9, 10 or 11 wherein the slug (4A) is in the form of pellet or powder.
- A method of manufacturing an electrode (1,5) for a spark plug (100) according to any one of claims 9 to 12, wherein the laser beams are such that a cone-shaped interface (45) is provided between the firing tip (4) and the end surface of the metallic clad (2,51) or blank.
- A method of manufacturing an electrode (1,5) for a spark plug (100) according to any one of claims 9 to 13, wherein the laser beams are released by energizing a laser beam device (L4) with a power source of 340V, and shot once or several times with a pulse width of 0.9 ms at the time of applying the laser beam welding.
- A method of manufacturing an electrode (1,5) for a spark plug (100) according to any one of claims 9 to 14, wherein the diameter of the firing tip (4) is preferably greater than 0.3 mm but smaller than the diameter of the front surface of the blank or clad (2,51).
- A spark plug (100) including the electrode (1,5) according to any one of claims 1 to 8 or an electrode (1,5) made by a method according to any one of claims 9 to 15.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP34690191 | 1991-12-27 | ||
JP346901/91 | 1991-12-27 | ||
JP114809/92 | 1992-05-07 | ||
JP4114809A JPH05234662A (en) | 1991-12-27 | 1992-05-07 | Electrode for spark plug and its manufacture |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0549368A2 EP0549368A2 (en) | 1993-06-30 |
EP0549368A3 EP0549368A3 (en) | 1994-02-16 |
EP0549368B1 true EP0549368B1 (en) | 1998-05-27 |
Family
ID=26453473
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19920311818 Expired - Lifetime EP0549368B1 (en) | 1991-12-27 | 1992-12-24 | An electrode for a spark plug and a method of manufacturing the same |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0549368B1 (en) |
DE (1) | DE69225686T2 (en) |
Families Citing this family (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3425973B2 (en) * | 1992-08-19 | 2003-07-14 | 日本特殊陶業株式会社 | Spark plug and manufacturing method thereof |
JP3344737B2 (en) * | 1992-09-10 | 2002-11-18 | 日本特殊陶業株式会社 | Spark plug manufacturing method |
JPH07249471A (en) * | 1994-03-10 | 1995-09-26 | Ngk Spark Plug Co Ltd | Spark plug |
JP3121309B2 (en) * | 1998-02-16 | 2000-12-25 | 株式会社デンソー | Spark plugs for internal combustion engines |
DE10015642A1 (en) * | 2000-03-29 | 2001-10-18 | Bosch Gmbh Robert | Spark plug for an internal combustion engine |
DE10027651C2 (en) * | 2000-06-03 | 2002-11-28 | Bosch Gmbh Robert | Electrode, method for its production and spark plug with such an electrode |
DE10134671A1 (en) * | 2001-07-20 | 2003-02-06 | Bosch Gmbh Robert | Applying precious metal tip to electrode used in production of a spark plug comprises welding tip to electrode, and fusing tip in first region and electrode in second region to form mixed alloy |
DE10149630C1 (en) * | 2001-10-09 | 2003-10-09 | Beru Ag | Spark plug and process for its manufacture |
DE10255187A1 (en) * | 2002-11-27 | 2004-06-24 | Robert Bosch Gmbh | Joining electrode of spark plug to precious metal section comprises joining precious metal section with electrode using heat from laser beam |
EP2036173B2 (en) | 2006-06-19 | 2016-06-15 | Federal-Mogul Corporation | Small diameter/long reach spark plug with improved insulator design |
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 (en) * | 2011-09-26 | 2013-03-28 | Robert Bosch Gmbh | Spark plug with side-mounted ground electrode |
DE102013105698B4 (en) | 2012-06-01 | 2019-05-02 | Federal-Mogul Ignition Company | spark plug |
US9318879B2 (en) | 2012-10-19 | 2016-04-19 | Federal-Mogul Ignition Company | Spark plug having firing pad |
CA3177639A1 (en) | 2020-06-18 | 2021-12-23 | Innio Jenbacher Gmbh & Co Og | Method for manufacturing an assembly for a spark plug and spark plug |
Family Cites Families (3)
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 (en) * | 1987-08-18 | 1989-03-02 | Bosch Gmbh Robert | METHOD FOR PRODUCING A SPARK PLUG FOR INTERNAL COMBUSTION ENGINES |
-
1992
- 1992-12-24 EP EP19920311818 patent/EP0549368B1/en not_active Expired - Lifetime
- 1992-12-24 DE DE1992625686 patent/DE69225686T2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
DE69225686D1 (en) | 1998-07-02 |
EP0549368A2 (en) | 1993-06-30 |
DE69225686T2 (en) | 1998-09-17 |
EP0549368A3 (en) | 1994-02-16 |
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