WO2022264997A1 - スパークプラグ - Google Patents
スパークプラグ Download PDFInfo
- Publication number
- WO2022264997A1 WO2022264997A1 PCT/JP2022/023733 JP2022023733W WO2022264997A1 WO 2022264997 A1 WO2022264997 A1 WO 2022264997A1 JP 2022023733 W JP2022023733 W JP 2022023733W WO 2022264997 A1 WO2022264997 A1 WO 2022264997A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- insulator
- alumina particles
- observation
- mirror
- observation regions
- Prior art date
Links
- 239000002245 particle Substances 0.000 claims abstract description 155
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 129
- 238000009826 distribution Methods 0.000 claims abstract description 29
- 238000005530 etching Methods 0.000 claims abstract description 29
- 239000011148 porous material Substances 0.000 claims abstract description 21
- 238000005498 polishing Methods 0.000 claims abstract description 8
- 238000005520 cutting process Methods 0.000 claims abstract description 7
- 239000012212 insulator Substances 0.000 claims description 159
- 230000002093 peripheral effect Effects 0.000 claims description 24
- 239000003566 sealing material Substances 0.000 claims description 2
- 239000000843 powder Substances 0.000 description 34
- 229910052751 metal Inorganic materials 0.000 description 28
- 239000002184 metal Substances 0.000 description 28
- 238000000034 method Methods 0.000 description 27
- 238000001878 scanning electron micrograph Methods 0.000 description 26
- 239000002002 slurry Substances 0.000 description 21
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 14
- 239000002994 raw material Substances 0.000 description 14
- 238000004519 manufacturing process Methods 0.000 description 13
- 239000003513 alkali Substances 0.000 description 12
- 238000000465 moulding Methods 0.000 description 12
- 239000000523 sample Substances 0.000 description 11
- 238000005259 measurement Methods 0.000 description 10
- 238000012360 testing method Methods 0.000 description 9
- 150000001875 compounds Chemical class 0.000 description 8
- 230000003628 erosive effect Effects 0.000 description 8
- 238000010298 pulverizing process Methods 0.000 description 8
- 238000007789 sealing Methods 0.000 description 8
- 230000002159 abnormal effect Effects 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000000227 grinding Methods 0.000 description 7
- 229910052759 nickel Inorganic materials 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 230000015556 catabolic process Effects 0.000 description 6
- 238000010304 firing Methods 0.000 description 6
- 239000011521 glass Substances 0.000 description 6
- 238000010191 image analysis Methods 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 238000002485 combustion reaction Methods 0.000 description 5
- 230000005684 electric field Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 230000001133 acceleration Effects 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 229910052741 iridium Inorganic materials 0.000 description 4
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 239000012141 concentrate Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005469 granulation Methods 0.000 description 3
- 230000003179 granulation Effects 0.000 description 3
- 238000012856 packing Methods 0.000 description 3
- 238000001694 spray drying Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000002788 crimping Methods 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- 238000007517 polishing process Methods 0.000 description 2
- 239000000454 talc Substances 0.000 description 2
- 229910052623 talc Inorganic materials 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004375 Dextrin Substances 0.000 description 1
- 229920001353 Dextrin Polymers 0.000 description 1
- 229920000084 Gum arabic Polymers 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 241000978776 Senegalia senegal Species 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 235000010489 acacia gum Nutrition 0.000 description 1
- 239000000205 acacia gum Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 235000019425 dextrin Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000003703 image analysis method Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 238000007561 laser diffraction method Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
- 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
-
- 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
-
- 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
- H01T13/34—Sparking plugs characterised by features of the electrodes or insulation characterised by the mounting of electrodes in insulation, e.g. by embedding
-
- 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
Definitions
- the present invention relates to spark plugs.
- a spark plug used in an internal combustion engine comprises a cylindrical insulator made of an alumina-based sintered body containing alumina as a main component, and a center electrode housed inside the insulator (for example, patent Reference 1).
- the center electrode consists of a rod-shaped electrode main body (electrode leg) whose tip is exposed from the insulator and whose rear end is housed inside the insulator, and an enlarged diameter part (electrode collar) connected to the rear end of the electrode main body. part).
- the enlarged diameter portion has a shape that expands in the radial direction from the electrode main body portion, and the center electrode is in a state in which such an enlarged diameter portion is engaged with the stepped raised portion of the inner wall of the insulator. Housed inside the insulator.
- An electrode head having a diameter smaller than that of the enlarged diameter portion is connected to the rear end of the enlarged diameter portion.
- the rear end portion of the center electrode that is, the enlarged diameter portion and the electrode head portion
- the inner wall of the insulator are spaced apart from each other in the radial direction. facing each other.
- a conductive sealing member is provided inside the insulator so as to fill the space between them and cover the rear end of the center electrode.
- the sealing member is made of a conductive composition containing, for example, B 2 O 3 —SiO 2 -based glass particles and metal particles (Cu, Fe, etc.).
- An object of the present invention is to provide a spark plug having an insulator with excellent withstand voltage performance.
- the present inventors found that in a spark plug comprising an insulator made of an alumina-based sintered body and a center electrode housed inside the insulator, a If abnormally grown alumina particles having a size of a certain size or more exist, when a high voltage is applied to the center electrode, an electric field tends to concentrate around the alumina particles, and near the alumina particles. was found to be the origin of breakdown of the insulator.
- the inventors of the present invention found that the average grain size of the alumina particles constituting the sintered body was abnormal in the inside of the specific portion of the middle body portion of the insulator. It was found that the withstand voltage performance and the like of the insulator can be secured when the particle size is within a predetermined range that is not the particle size during grain growth and the variation in the particle size of the alumina particles is suppressed. Arrived.
- Means for solving the above problems are as follows. Namely ⁇ 1> An insulator made of an alumina-based sintered body having a cylindrical shape extending along the axial direction, and an insulator having a front end exposed from the insulator and a rear end housed inside the insulator. a rod-shaped electrode main body portion inserted into the insulator; and a conductive sealing material housed inside the insulator and disposed on the rear end side of the center electrode, wherein the maximum diameter of the enlarged diameter portion is It is obtained by mirror-polishing the cut surface obtained by cutting the insulator in a direction perpendicular to the axial direction at a position 2 mm away from the diameter portion toward the rear end side along the axial direction.
- the ratio (porosity) of the area of all the pores included in the 20 first observation regions to the total area (100%) of the 20 first observation regions is 3.5% or less
- 20 second observation regions of 32 ⁇ m ⁇ 43 ⁇ m are set on a thermally etched surface obtained by thermally etching a mirror-polished surface so as to overlap with the reference position but not overlap with each other, 20 of the second observation regions are formed.
- A is 1.9 ⁇ m or more, where A is the average particle size of the alumina particles, and ⁇ is the standard deviation of the particle size of the alumina particles. .8 ⁇ m or less and (A+3 ⁇ ) is 3.0 ⁇ m or less.
- ⁇ 2> In the 20 second observation areas on the thermal etching surface, 60 representative alumina particles with a large major axis are selected by selecting the top 3 alumina particles with the largest major axis for each of the second observation areas. is selected, the frequency distribution of the aspect ratio of the representative alumina particles is regarded as a normal distribution, the average aspect ratio of the representative alumina particles is B, and the standard deviation of the aspect ratio of the representative alumina particles is ⁇ . , (B+3 ⁇ ) is 4.8 or less.
- ⁇ 4> The spark plug according to any one of ⁇ 1> to ⁇ 3>, wherein the number of pores is 600 or less in the 20 first observation areas on the mirror-polished surface.
- Sectional view along the axial direction of the spark plug according to Embodiment 1 Enlarged cross-sectional view of the vicinity of the electrode collar of the center electrode housed in the middle body of the insulator
- Explanatory drawing schematically showing the thermal etching surface of the middle body part of the insulator Explanatory drawing showing a SEM image corresponding to the second observation area
- FIG. 1 is a cross-sectional view of the spark plug 1 according to Embodiment 1 along the direction of the axis AX. 1 is the axis AX of the spark plug 1.
- the longitudinal direction of the spark plug 1 corresponds to the vertical direction in FIG.
- the lower side of FIG. 1 shows the front end side of the spark plug 1
- the upper side of FIG. 1 shows the rear end side of the spark plug 1.
- a spark plug 1 is attached to an automobile engine (an example of an internal combustion engine) and used to ignite an air-fuel mixture in a combustion chamber of the engine.
- a spark plug 1 mainly includes an insulator 2 , a center electrode 3 , a ground electrode 4 , a terminal fitting 5 , a metal shell 6 , a resistor 7 and sealing members 8 and 9 .
- the insulator 2 is a substantially cylindrical member extending in the direction of the axis AX and including a through hole 21 inside. Details of the insulator 2 will be described later.
- the metal shell 6 is a member used when the spark plug 1 is attached to an engine (specifically, an engine head). , low-carbon steel).
- a threaded portion 61 is formed on the outer peripheral surface of the metal shell 6 on the tip side.
- a ring-shaped gasket G is externally fitted to the rear end (so-called screw neck) of the threaded portion 61 .
- the gasket G is annular and formed by bending a metal plate. Such a gasket G is arranged between the rear end of the threaded portion 61 and the seat portion 62 arranged on the rear end side of the threaded portion 61, and when the spark plug 1 is attached to the engine, a spark is generated. It seals the gap formed between the plug 1 and the engine (engine head).
- a tool engaging portion 63 for engaging a tool such as a wrench when attaching the metal shell 6 to the engine is provided on the rear end side of the metal shell 6 .
- a thin crimped portion 64 bent radially inward is provided at the rear end portion of the metal shell 6 .
- the metal shell 6 also has a through hole 65 penetrating in the direction of the axis AX.
- the rear end of the insulator 2 protrudes greatly outward (upper side in FIG. 1) from the rear end of the metal shell 6 .
- the tip of the insulator 2 projects slightly outward (lower side in FIG. 1) from the tip of the metal shell 6 .
- An annular region is provided between the inner peripheral surface of the metal shell 6 from the tool engaging portion 63 to the crimping portion 64 and the outer peripheral surface of the insulator 2 (the outer peripheral surface of the rear cylindrical portion 25 described later). is formed, and the annular first ring member R1 and the annular second ring member R2 are arranged in the region in a state separated from each other in the direction of the axis AX.
- a powder of talc 10 is filled between the first ring member R1 and the second ring member R2.
- the rear end of the crimping portion 64 is bent radially inward and fixed to the outer peripheral surface of the insulator 2 (the outer peripheral surface of the rear cylindrical portion 25 described later).
- the metal shell 6 has a thin compression deformation portion 66 provided between the seat portion 62 and the tool engaging portion 63 .
- the compressively deformed portion 66 is compressively deformed when the caulking portion 64 fixed to the outer peripheral surface of the insulator 2 is pressed toward the distal end side during manufacture of the spark plug 1 .
- the insulator 2 is pressed forward within the metal shell 6 via the first ring member R1, the second ring member R2, and the talc 10 .
- the outer peripheral surface of the portion (the first expanded diameter portion 26 to be described later) that is a part of the insulator 2 and extends annularly is placed on the surface of the stepped portion 66 provided on the inner peripheral side of the metal shell 6.
- it is pressed while placing the packing P1 therebetween. Therefore, even if the gas in the combustion chamber of the engine enters the gap formed between the metal shell 6 and the insulator 2, the packing P1 provided in the gap prevents the gas from leaking to the outside. .
- the center electrode 3 is arranged inside the insulator 2 when the insulator 2 is mounted inside the metal shell 6 .
- the center electrode 3 includes a rod-shaped center electrode body 31 extending along the direction of the axis AX, and a substantially cylindrical (substantially disk-shaped) tip (center electrode tip) 32 attached to the tip of the center electrode body 31 .
- the center electrode main body 31 is a member whose length in the longitudinal direction is shorter than that of the insulator 2 and the metal shell 6, and is held in the through hole 21 of the insulator 2 so that the tip side thereof is exposed to the outside.
- the rear end of the center electrode main body 31 is accommodated inside the insulator 2 (through hole 21).
- the center electrode main body 31 includes an electrode base material 31A arranged outside and a core portion 31B embedded inside the electrode base material 31A.
- the electrode base material 31A is formed using, for example, nickel or an alloy containing nickel as a main component (eg, NCF600, NCF601).
- the core portion 31B is made of copper or a nickel-based alloy containing copper as a main component, which is superior in thermal conductivity to the alloy forming the electrode base material 31A.
- the center electrode body 31 includes an electrode collar portion 31a attached at a predetermined position in the direction of the axis AX, an electrode head portion 31b which is a portion on the rear end side of the electrode collar portion 31a, and and an electrode leg portion 31c, which is a portion on the tip side.
- the electrode leg portion (an example of the electrode body portion) 31c is a rod-shaped electrode inserted into the through-hole 21 of the insulator 2 so that the tip end is exposed from the insulator 2 and the rear end is accommodated inside the insulator 2. It is a member.
- the electrode collar portion (an example of the enlarged diameter portion) 31a continues to the rear end of the electrode leg portion (electrode main body portion) 31c and has a shape that expands radially from the electrode leg portion 31c.
- the electrode collar portion 31a is accommodated in the insulator 2 and engaged with a stepped portion 23a (described later) formed on the inner wall 21a of the insulator 2 .
- the tip of the electrode leg portion 31 c (that is, the tip of the center electrode main body 31 ) protrudes from the tip of the insulator 2 toward the tip side.
- the electrode collar portion 31a is a bar-shaped portion that is shorter than the electrode leg portion 31c and has a smaller diameter than the electrode collar portion 31a.
- the tip 32 has a substantially columnar shape (substantially disk shape) and is joined to the tip of the center electrode main body 31 (the tip of the electrode leg portion 31c) by resistance welding, laser welding, or the like.
- the tip 32 is made of a material whose main component is a noble metal with a high melting point (for example, an iridium-based alloy whose main component is iridium (Ir)).
- the terminal fitting 5 is a rod-shaped member extending in the direction of the axis AX, and is attached by being inserted into the rear end side of the through hole 21 of the insulator 2 .
- the terminal fitting 5 is arranged on the rear end side of the center electrode 3 in the insulator 2 (through hole 21 ).
- the terminal fitting 5 is made of a conductive metal material (for example, low carbon steel).
- the surface of the terminal fitting 5 may be plated with nickel or the like for the purpose of corrosion protection.
- the terminal fitting 5 includes a bar-shaped terminal leg portion 51 arranged on the front end side, a terminal flange portion 52 arranged on the rear end side of the terminal leg portion 51, and a terminal flange portion 52 arranged on the rear end side of the terminal flange portion 52.
- a cap mounting portion 53 is provided.
- the terminal leg portion 51 is inserted into the through hole 21 of the insulator 2 .
- the terminal collar portion 52 is a portion exposed from the rear end portion of the insulator 2 and engaged with the rear end portion.
- the cap attachment portion 53 is a portion to which a plug cap (not shown) to which a high-voltage cable is connected is attached, and a high voltage for generating spark discharge is applied from the outside via the cap attachment portion 53. .
- the resistor 7 is arranged in the through hole 21 of the insulator 2 between the front end of the terminal fitting 5 (the front end of the terminal leg portion 51) and the rear end of the center electrode 3 (the rear end of the center electrode main body 31). be.
- the resistor 7 has, for example, a resistance value of 1 k ⁇ or more (eg, 5 k ⁇ ), and has a function of reducing radio noise when sparks are generated.
- the resistor 7 is made of a composition containing glass particles as a main component, ceramic particles other than glass, and a conductive material.
- a gap is provided between the tip of the resistor 7 and the rear end of the center electrode 3 in the through hole 21, and the conductive sealing member 8 is arranged to fill the gap.
- a gap is also provided between the rear end of the resistor 7 and the tip of the terminal fitting 5 in the through hole 21, and the conductive sealing member 9 is arranged to fill the gap.
- Each of the sealing members 8 and 9 is made of a conductive composition containing, for example, B 2 O 3 —SiO 2 -based glass particles and metal particles (Cu, Fe, etc.).
- the ground electrode 4 comprises a ground electrode main body 41 joined to the tip of the metal shell 6 and a ground electrode tip 42 in the shape of a quadrangular prism.
- the ground electrode main body 41 is generally formed of a plate piece that is bent in a substantially L shape in the middle, and the rear end portion 41a thereof is joined to the front end of the metal shell 6 by resistance welding or the like. Thereby, the metal shell 6 and the ground electrode main body 41 are electrically connected.
- the ground electrode main body 41 is made of, for example, nickel or a nickel-based alloy containing nickel as a main component (for example, NCF600, NCF601), like the metal shell 6 .
- the ground electrode tip 42 is made of an iridium-based alloy containing iridium (Ir) as a main component.
- the ground electrode tip 42 is joined to the tip of the ground electrode main body 41 by laser welding.
- the ground electrode tip 42 at the tip of the ground electrode main body 41 and the tip 32 at the tip of the center electrode 3 are arranged to face each other while keeping a distance therebetween. That is, there is a gap SP between the tip 32 at the tip of the center electrode 3 and the ground electrode tip 42 at the tip of the ground electrode 4, and a high voltage is applied between the center electrode 3 and the ground electrode 4. is applied, a spark discharge is generated in the gap SP along the direction of the axis AX.
- the insulator 2 generally has a tubular shape (cylindrical shape) elongated along the direction of the axis AX, and as shown in FIG. contains.
- the insulator 2 is composed of a tubular (cylindrical) alumina-based sintered body containing alumina as a main component.
- the insulator 2 includes a long leg portion 22 disposed on the distal end side, a middle body portion 23 disposed on the rear end side of the long leg portion 22 and having a larger diameter than the long leg portion 22, and a middle body portion 23.
- a collar portion 24 which is arranged on the rear end side of the body and has a diameter larger than that of the middle body portion 23 .
- a first enlarged diameter portion 26 is provided between the long leg portion 22 and the middle body portion 23, and a second enlarged diameter portion 27 is provided between the middle body portion 23 and the collar portion 24. is provided.
- the long leg portion 22 has an overall elongated tube shape (cylindrical shape) whose outer diameter gradually increases from the front side to the rear side, and is larger than the middle body portion 23 and the first enlarged diameter portion 26 . It has a small outer diameter.
- the long leg portion 22 is exposed to the combustion chamber when the spark plug 1 is attached to the engine (engine head).
- the flange portion 24 is arranged substantially in the center of the insulator 2 in the direction of the axis AX and has an annular shape.
- a resistor 7 is arranged in the through hole 21 inside the collar portion 24 .
- the first enlarged diameter portion 26 is a portion that connects the long leg portion 22 and the middle body portion 23, and has a cylindrical shape (annular shape) whose outer diameter gradually increases from the front side to the rear side.
- the second enlarged diameter portion 27 is a portion that connects the middle body portion 23 and the collar portion 24, has an outer diameter larger than that of the first enlarged diameter portion 26, and gradually increases in diameter from the front side to the rear side. It has a cylindrical (annular) shape that grows larger.
- the middle body part 23 has a tubular shape (cylindrical shape) with an approximately uniform outer diameter in the direction of the axis AX.
- the middle body part 23 has a tubular shape (cylindrical shape) with an approximately uniform outer diameter in the direction of the axis AX.
- An annular stepped portion 23 a is provided on the inner side (inner peripheral surface side) of the intermediate body portion 23 near the tip, and the center electrode body 31 of the center electrode 3 is accommodated in the through hole 21 of the insulator 2 . In this state, the electrode collar portion (enlarged diameter portion) 31a of the center electrode main body 31 is locked by the surface of the stepped portion 23a.
- the thickness of the wall portion of the middle body portion 23 is greater than the thickness of the wall portion of the long leg portion 22 .
- the wall thickness of the portion of the middle body portion 23 where the stepped portion 23a is formed from the front end side is greater than the thickness of the wall portion of the portion behind the stepped portion 23a.
- the outer peripheral surface of the middle body part 23 is exposed to the atmosphere (air), and it can be said that it is in an environment where electricity can easily pass through compared to the long leg part 22 . Therefore, the middle body portion 23 is set to have a larger wall thickness than the long leg portion 22 .
- the “thickness of the middle body portion 23” means a portion of the middle body portion 23 where the thickness of the wall portion is substantially constant (that is, the rear end side of the stepped portion 23a). part) is the thickness of the wall.
- the thickness of the middle body portion 23 is not particularly limited as long as it does not impair the purpose of the present invention, but may be set in the range of 2.0 mm or more and 3.0 mm or less, for example.
- the insulator 2 further includes a tubular (cylindrical) rear tubular portion 25 connected to the rear end side of the flange portion 24 and extending in the direction of the axis AX.
- the rear tubular portion 25 has an outer diameter smaller than the outer diameter of the collar portion 24 .
- a rod-shaped terminal leg portion 51 and the like of the terminal fitting 5 are arranged in the through hole 21 inside the rear cylindrical portion 25 .
- FIG. 2 is an enlarged cross-sectional view of the vicinity of the electrode collar portion (enlarged diameter portion) 31a of the center electrode 3 (center electrode main body 31) accommodated in the middle body portion 23 of the insulator 2.
- FIG. 2 As shown in FIG. 2, in a state where the center electrode body 31 of the center electrode 3 is housed inside the insulator 2, an electrode collar portion (expanded diameter portion) 31a, which is the rear end portion of the center electrode body 31, is formed. Also, there is a gap between the electrode head 31b and the inner wall 21a of the insulator 2 .
- the seal member 8 described above is filled in the through hole 21 of the insulator 2 so as to fill the gap and cover the rear end of the center electrode body 31 .
- the seal member 8 contains alkaline components derived from glass particles and the like.
- the distance between the electrode collar portion (expanded diameter portion) 31a of the center electrode 3 and the inner wall 21a of the insulator 2 is narrower than the distance between the electrode head portion 31b and the inner wall 21a of the insulator 2.
- Heat transferred from the distal end side of the center electrode main body 31 of the center electrode 3 via the electrode collar portion (enlarged diameter portion) 31a tends to accumulate in such a portion.
- an electric field tends to concentrate at that location. Therefore, of the insulator 2, the portion of the middle body portion 23 that faces the electrode collar portion (enlarged diameter portion) 31a in the radial direction is placed under the most severe environment.
- the inner wall 21a of the middle body portion 23 is in a state of being in direct contact with the sealing member 8.
- Alkaline components derived from the member 8 are also in a state where they can come into contact with the inner wall 21 a of the middle body portion 23 .
- the insulator 2 of the present embodiment has excellent withstand voltage performance, etc., because the internal structure of the alumina-based sintered body constituting the middle body portion 23 satisfies at least the following conditions 1 and 2. .
- a reference position m1 which is a position 0.2 mm in the radial direction from the inner peripheral surface 2a of the insulator 2
- 20 first observation regions X are set so as to overlap but not overlap each other, 20 first observation regions X with respect to the total area (100%) of the 20 first observation regions X
- the area ratio (porosity) of all pores contained in is 3.5% or less.
- condition 1 will be described in detail with reference to FIGS.
- the "largest diameter portion of the electrode collar portion (diameter enlarged portion) 31a of the center electrode 3" shown in Condition 1 corresponds to the electrode collar portion (diameter enlarged portion) of the center electrode main body 31 of the center electrode 3, as shown in FIG. 31a, the diameter D of which is the largest.
- a straight line L1 is shown so as to cross the maximum diameter portion of the electrode collar portion (enlarged diameter portion) 31a while perpendicularly intersecting the axis AX.
- the insulator 2 is formed as will be described later. disconnected.
- the range from the maximum diameter portion of the electrode collar portion (expanded diameter portion) 31a to a position at least 2 mm away is the most durable (withstanding voltage performance, etc.).
- the electrode collar portion (expanded diameter portion) 31a A position 2 mm away from the maximum diameter portion toward the rear end side was set as a location for cutting the insulator 2 .
- the position 2 mm away from the rear end side is The reference position (the position indicated by the straight line L1) for setting is the position closest to the distal end in the portion with the maximum diameter.
- the location where the insulator 2 is cut is indicated by a straight line L2.
- the straight line L2 is shown to perpendicularly intersect the axis AX at a position 2 mm away from the straight line L1 toward the rear end side (upper side in FIG. 2).
- the straight line L2 extends across the middle body portion 23 of the insulator 2 in the radial direction.
- Condition 1 defines the state of the internal structure of the cut surface 230 obtained by radially cutting the middle body portion 23 along the straight line L2.
- FIG. 3 is an explanatory view schematically showing a mirror-polished surface 230a obtained by mirror-polishing the cut surface 230 of the middle body portion 23 of the insulator 2.
- FIG. FIG. 3 shows a mirror-polished cut surface 230 obtained by cutting the middle body portion 23 along the straight line L2 shown in FIG. Note that the cut surface 230 that has been mirror-finished by the mirror-polishing process described below is referred to as a mirror-polished surface 230a.
- the mirror-polishing treatment of the cut surface 230 is performed based on a known technique using abrasives such as a diamond whetstone and diamond paste.
- the mirror polishing process is performed until the surface roughness (Ra) of the cut surface 230 reaches, for example, about 0.001 ⁇ m.
- the mirror-polished surface 230a is observed using a scanning electron microscope (SEM). Therefore, the mirror-polished surface 230a may be subjected to carbon vapor deposition for imparting conductivity, if necessary.
- the acceleration voltage of the SEM is set to 20 kV and the magnification of the SEM is set to 500 when observing the mirror-polished surface 230a.
- the mirror-polished surface 230a has an annular shape as shown in FIG.
- a circular reference position m1 is set at a position 0.2 mm in the radial direction from the inner peripheral surface 2a side of the insulator 2 on such a mirror-polished surface 230a.
- 20 first observation regions X are set so that each overlaps the reference position m1 in plan view on the mirror-polished surface 230a but does not overlap each other.
- the first observation region X is a region set to grasp the state of the pores (voids) 11 in the internal tissue on the mirror-polished surface 230a (cut surface 230), and has a rectangular shape (rectangular shape). .
- the first observation region X is a rectangular (rectangular) region having one side length of 192 ⁇ m and the other side length of 255 ⁇ m (that is, 192 ⁇ m ⁇ 255 ⁇ m).
- the first observation area X is set so as to overlap a circular reference position m1, which is located 0.2 mm in the radial direction from the inner peripheral surface 2a side of the insulator 2 when viewed from above.
- a circular reference position m1 which is located 0.2 mm in the radial direction from the inner peripheral surface 2a side of the insulator 2 when viewed from above.
- the internal structure of the insulator 2 (middle body portion 23) on the inner peripheral surface 2 side is hypothetically an alkaline component. If the insulator 2 has been eroded by the insulator 2, the state of the original internal structure of the insulator 2 cannot be observed. Therefore, in this embodiment, as described above, the first observation area X is set so as to overlap with the reference position m1.
- a total of 20 such first observation regions X are set so as not to overlap each other on the mirror-polished surface 230a.
- these first observation areas X are preferably set so as to be arranged in an annular shape while maintaining a distance from each other on the annular mirror-polished surface 230a.
- a SEM image corresponding to the first observation region X is obtained by photographing the mirror-polished surface 230a in the range corresponding to the first observation region X using an SEM. SEM images are acquired for each of the 20 first observation regions X. FIG. That is, a total of 20 SEM images are acquired corresponding to a total of 20 first observation regions X.
- a total of 20 SEM images are subjected to image analysis processing using known image analysis software (for example, WinROOF (registered trademark), manufactured by Mitani Shoji Co., Ltd.) executed on a computer.
- image analysis software for example, WinROOF (registered trademark), manufactured by Mitani Shoji Co., Ltd.
- each SEM image is first subjected to size calibration based on the scale bar attached to the SEM image.
- FIG. 4 is an explanatory diagram showing a binarized image obtained by binarizing an SEM image.
- a binarized image can be obtained by converting the image into two gradations and eliminating intermediate gradations.
- the pores 11 are shown in black, and the other portion (ceramic portion) 12 is shown in white.
- all the pores (voids) 11 included in the first observation region X are extracted by a known image analysis technique. Further, when the pores 11 are extracted, the area of each pore 11 is also determined by a known image analysis method.
- ratio V the ratio (porosity) of the total area of all the pores 11 included in the 20 first observation regions X to the total area (100%) of the 20 first observation regions X.
- the internal structure of the insulator 2 (middle body portion 23) is formed so that the ratio V (porosity) in Condition 1 is 3.5% or less.
- the insulation having pores satisfying the condition 1 is obtained by applying pressure under a higher pressure condition than before.
- a body 2 is obtained.
- condition 2 will be described in detail with reference to FIGS.
- Condition 2 like Condition 1, defines the state of the internal tissue at the cut surface 230 of the same insulator 2 (midsection 23).
- Condition 2 the state of the internal rough region is observed not in the mirror-polished surface 230a described above, but in the state of the thermally-etched surface 230b obtained by thermally etching the mirror-polished surface 230a.
- Thermal etching is carried out by placing a sample (insulator 2) including the mirror-polished surface 230a in a predetermined electric furnace or the like, and performing the thermal etching under temperature conditions (for example, 1400° C.) about 200° C. lower than the firing temperature of the insulator 2. This is a process of holding for a predetermined time (for example, 1 hour) and then performing air cooling in the furnace. When such a treatment is performed, depressions are formed at the interfaces of the alumina particles existing on the cut surface 230 (thermal etching surface 230b), so that the alumina particles can be individually observed.
- the alumina-based sintered body forming the insulator 2 is a liquid phase sintered body, and the liquid phase (glass component) around the alumina particles at the cut surface 230 is removed by thermal etching.
- FIG. 5 is an explanatory view schematically showing the thermal etching surface 230b of the middle body portion 23 of the insulator 2.
- Thermally etched surface 230b is observed using a scanning electron microscope (SEM). Therefore, the thermal etching surface 230b may be subjected to carbon vapor deposition for imparting conductivity, if necessary.
- the acceleration voltage of the SEM during observation of the thermal etching surface 230b is set to 20 kV, and the magnification of the SEM is set to 3000 times.
- the thermal etching surface 230b has an annular shape like the mirror-polished surface 230a, and on such a thermal etching surface 230b, a circular A reference position m1 is set.
- the second observation area Y is an area set to grasp the state of alumina particles in the internal structure on the thermal etching surface 230b (cut surface 230).
- the second observation area Y is smaller in size than the first observation area X, but like the first observation area X, has a rectangular shape (rectangular shape).
- the second observation region Y is a rectangular (rectangular) region having one side length of 32 ⁇ m and the other side length of 43 ⁇ m (that is, 132 ⁇ m ⁇ 43 ⁇ m).
- the second observation area Y is set so as to overlap the reference position m1 when viewed in plan.
- the reason for setting the second observation area Y so as to overlap the reference position m1 is the same as the reason for setting the first observation area X so as to overlap the reference position m1 on the mirror-polished surface 230a.
- a total of 20 second observation regions Y are set on the thermal etching surface 230b so as not to overlap each other in plan view. As shown in FIG. 5, these second observation regions Y are preferably set so as to be arranged in a ring on the ring-shaped thermal etching surface 230b while maintaining equal intervals from each other.
- condition 2 the particle size distribution of the alumina particles contained in the 20 second observation regions Y set in this way is regarded as a normal distribution, the average particle size of the alumina particles is A, and the standard deviation of the particle size of the alumina particles is is ⁇ , A is 1.9 ⁇ m or more and 2.8 ⁇ m or less, and (A+3 ⁇ ) is defined to be 3.0 ⁇ m or less.
- the particle size of the alumina particles contained in the second observation area Y is obtained based on the SEM image of the thermal etching surface 230b in the range corresponding to the second observation area Y.
- FIG. 6 is an explanatory diagram showing a SEM image corresponding to the second observation area Y.
- FIG. A number of alumina particles 28 are shown in FIG.
- the SEM image is acquired by photographing the thermal etching surface 230b in the range corresponding to the second observation region Y using the SEM.
- SEM images are acquired for each of the 20 second observation regions Y.
- the grain size of the alumina particles is measured in accordance with JIS G0551 "ferrite/austenite grain size measurement" while using the SEM image corresponding to the second observation region Y. Then, the average particle size A of the alumina particles is obtained using the measurement result of the particle size of the alumina particles. In the case of this embodiment, the average particle diameter A of alumina particles is adjusted to 1.9 ⁇ m or more and 2.8 ⁇ m or less.
- the SEM image is appropriately binarized using known image analysis software (the same applies when measuring the long diameter of alumina particles, which will be described later).
- the internal structure of the insulator 2 (middle body portion 23) is formed such that (A+3 ⁇ ) is 3.0 ⁇ m or less.
- the insulator 2 that satisfies the condition 2 is, for example, an Al compound powder (alumina powder, etc.) with a narrow (sharp) particle size distribution from which small particles that promote abnormal grain growth are removed during manufacture. Obtained by using an Al compound powder (alumina powder, etc.) with a narrow (sharp) particle size distribution from which small particles that promote abnormal grain growth are removed during manufacture. Obtained by using an Al compound powder (alumina powder, etc.) with a narrow (sharp) particle size distribution from which small particles that promote abnormal grain growth are removed during manufacture. Obtained by using
- the insulator 2 when the internal structure of the insulator 2 (in particular, the middle body portion 23) satisfies at least the above conditions 1 and 2, the insulator 2 (the middle body portion 23) is composed of an alumina-based sintered body.
- the aggregate is dense, the particle size of the alumina particles (average particle size A) is large to some extent, and the particle size of most of the alumina particles is controlled to fall within a predetermined narrow range (A ⁇ 3 ⁇ ). Therefore, the presence of abnormally grown alumina grains, which may serve as a starting point for breakdown of the insulator, is substantially eliminated. Therefore, the insulator 2 of the spark plug 1 of the present embodiment is excellent in withstand voltage performance, has few pores into which alkali components penetrate, and is excellent in alkali erosion resistance.
- the inner structure of the middle body portion 23 of the insulator 2 may be formed so as to satisfy the condition 3 described later in addition to the above conditions 1 and 2.
- ⁇ Condition 3> In the 20 second observation regions Y on the thermal etching surface 230b, by selecting the top three alumina particles with the largest major diameter d1 for each second observation region Y, 60 representative alumina particles with the largest major diameter d1 are selected.
- the frequency distribution of the aspect ratio of the representative alumina particles is regarded as a normal distribution, and the average aspect ratio of the representative alumina particles is B, and the standard deviation of the aspect ratio of the representative alumina particles is ⁇ , ( B+3 ⁇ ) is 4.8 or less.
- Condition 3 defines the state of 60 alumina particles with a large major axis d1 among the alumina particles in the internal structure of the thermal etching surface 230b (cut surface 230).
- the major diameter d1 and minor diameter d2 of the alumina particles in the second observation region Y are obtained by the intercept method.
- the crystal grains of the alumina particles that intersect at least one of the two diagonal lines are selected, and the maximum diameter of each selected crystal grain is obtained. This is defined as the long diameter d1 of the alumina particles.
- the maximum diameter is the maximum value when the outer diameter of the crystal grain is measured from all directions.
- the outer diameter of the crystal grains of the alumina particles on a straight line passing through the midpoint of the major axis d1 and perpendicular to the major axis d1 is defined as the minor axis d2 of the alumina particles.
- the long diameter d1 of the alumina particles is measured for all the alumina particles contained in the 20 second observation regions Y.
- the measurement of the short diameter d2 of the alumina particles may be performed at least for the representative alumina particles to be described later.
- 60 alumina particles having the large long diameter d1 are selected from the 20 second observation regions Y. Specifically, for each second observation region Y, the top three alumina particles having the largest length d1 are selected. A total of 60 alumina particles thus selected are referred to as "representative alumina particles”.
- the aspect ratio is obtained based on the major axis d1 and the minor axis d2.
- the aspect ratio (d1/d2) of representative alumina particles is the ratio of the major diameter d1 to the minor diameter d2.
- the average aspect ratio of the representative alumina particles is B
- the standard deviation of the aspect ratio of the representative alumina particles is ⁇
- (B + 3 ⁇ ) is
- the internal structure of the insulator 2 (middle body portion 23) may be formed so as to be 4.8 or less.
- FIG. 7 is an explanatory diagram showing an SEM image of a cut surface of an insulator containing alumina particles 280 that have undergone abnormal grain growth.
- FIG. 7 shows an SEM image of a cut surface (thermally etched surface) of the middle body portion of the insulator of the comparative example.
- the large alumina particles 280 shown in FIG. 7 are considerably larger than the surrounding alumina particles, and the vicinity of the alumina particles 280 tends to be the starting point of breakdown of the insulator.
- Condition 4 defines the state of representative alumina particles in the internal structure of the thermally etched surface 230b (cut surface 230).
- Alumina particles with an aspect ratio of 3.5 or more are likely to undergo abnormal grain growth, and such alumina particles are preferably not included in the internal structure of the middle body portion 23 of the insulator 2 .
- the number of pores is 600 or less in the 20 first observation regions X on the mirror-polished surface 230a.
- Condition 5 like Condition 1, defines the state of pores (voids) 11 in the internal tissue on the mirror-polished surface 230a (cut surface 230).
- the number of pores is preferably 600 or less.
- the porosity in the condition 1 can be easily controlled to a predetermined value, and the alkali erosion resistance can be easily improved.
- the insulator 2 is manufactured so as to satisfy the conditions 1 and 2 described above.
- the method for manufacturing the insulator 2 is not particularly limited as long as the finally obtained insulator 2 satisfies the conditions 1, 2 and the like.
- an example of a method for manufacturing the insulator 2 will be described.
- the method of manufacturing the insulator 2 mainly includes a slurry preparation process, a defoaming process, a granulation process, a molding process, a grinding process and a firing process.
- a slurry preparation process is a process of mixing raw material powder, a binder, and a solvent to prepare a slurry.
- the raw material powder powder of a compound that is converted into alumina by firing (hereinafter referred to as Al compound powder) is used as a main component.
- Al compound powder powder of a compound that is converted into alumina by firing
- alumina powder is used as the Al compound powder.
- a pulverization process is performed for the purpose of mixing and pulverizing the raw material powder.
- the pulverization step is performed using a wet pulverizer using a ball mill or the like.
- the diameter of the cobblestone used in the wet pulverizer is not particularly limited as long as it does not impair the purpose of the present invention, but it is preferably 3 mm or more and 20 mm or less, more preferably 3 mm or more and 10 mm or less, and still more preferably 3 mm or more and 6 mm. It is below. Also, as cobblestones, two or more kinds of cobblestones having different diameters may be combined.
- the raw material powder has a small variation in particle size (particle diameter) and has a sharp particle size distribution.
- particle size particle diameter
- the sintered density can be increased in the alumina-based sintered body obtained after sintering. Therefore, the alkali corrosion resistance of the insulator is improved.
- the particle size (particle size after pulverization) of the Al compound powder (alumina powder, etc.) is not particularly limited as long as it does not impair the object of the present invention. It is preferably 2.5 ⁇ m or less, more preferably 2.0 ⁇ m or less. When the particle size of the Al compound powder (alumina powder, etc.) is within such a range, the number of defects in the insulator is suppressed and an appropriate sintered density is obtained.
- the particle size is a volume-based median diameter (D50) measured by a laser diffraction method (manufactured by Nikkiso Co., Ltd., Microtrac particle size distribution analyzer, product name "MT-3000").
- the Al compound powder is preferably prepared so that the mass of the alumina-based sintered body after sintering (calculated as oxide) is 100% by mass, and is 90% by mass or more in terms of oxide. More preferably, it is 90% by mass or more and 98% by mass or less, and still more preferably 90% by mass or more and 97% by mass or less.
- the raw material powder may contain powder other than the Al compound powder as long as the object of the present invention is not impaired.
- the binder is added to the slurry for the purpose of improving the moldability of the raw material powder.
- binders include hydrophilic binders such as polyvinyl alcohol, aqueous acrylic resins, gum arabic and dextrin. You may use these individually or in combination of 2 or more types.
- the amount of the binder to be blended is not particularly limited as long as it does not impair the object of the present invention. It is blended at a ratio of 7 parts by mass.
- the solvent is used for purposes such as dispersing the raw material powder.
- solvents include water and alcohols. You may use these individually or in combination of 2 or more types.
- the amount of the solvent to be blended is not particularly limited as long as it does not impair the object of the present invention. It is blended at a ratio of 35 parts by mass.
- the slurry may optionally contain other components than the raw material powder, binder and solvent.
- a known stirring/mixing device or the like can be used for mixing the slurry.
- the slurry after the slurry production process may be subjected to a defoaming process.
- the defoaming step for example, the container containing the slurry after mixing (kneading) is placed in a vacuum defoaming device and placed in a low-pressure environment to decompress the air bubbles contained in the slurry. removed.
- the amount of air bubbles in the slurry can be grasped.
- the granulation step is a step of producing spherical granulated powder from a slurry containing raw material powder and the like.
- the method for producing the granulated powder from the slurry is not particularly limited as long as it does not impair the object of the present invention, and examples thereof include spray drying.
- a granulated powder having a predetermined particle size is obtained by spray-drying the slurry using a predetermined spray dryer.
- the particle size of the granulated powder is not particularly limited as long as it does not impair the purpose of the present invention.
- the molding step is a step of molding the granulated powder into a predetermined shape using a molding die to obtain a molded body.
- the molding process is performed by rubber press molding, die press molding, or the like.
- the pressure applied from the outer peripheral side to the mold (for example, the inner rubber mold and the outer rubber mold of a rubber press molding machine) (press pressure increase speed) is adjusted to increase stepwise.
- the upper limit of the pressure is not particularly limited as long as it does not impair the object of the present invention, but may be adjusted to 200 MPa or less, for example.
- the grinding step is a step of removing machining allowance from the molded body obtained after the molding step and polishing the surface of the molded body.
- machining allowance is removed and the surface of the compact is polished by grinding with a resinoid grindstone or the like. Through such a grinding process, the shape of the compact is adjusted.
- the sintering step is a step of sintering the compact shaped by the grinding step to obtain an insulator.
- firing step for example, firing is performed at 1450° C. or higher and 1650° C. or lower in an air atmosphere for 1 to 8 hours.
- the molded body is cooled to obtain the insulator 2 made of an alumina-based sintered body.
- the spark plug 1 of this embodiment is manufactured using the insulator 2 obtained as described above.
- the structure of the spark plug 1 other than the insulator 2 is the same as the known structure as described above.
- Example 1 (Preparation of test sample) Insulators having the same basic configuration as the spark plug insulators exemplified in the first embodiment were manufactured by the same manufacturing method as in the first embodiment (a total of three insulators were manufactured). The thickness of the middle body portion of the insulator is 3 mm. In the slurry preparation process, when the raw material powder was pulverized with a wet pulverizer, cobbles with a diameter of 3 mm ( ⁇ 3 mm) and cobbles with a diameter of 10 mm ( ⁇ 10 mm) were used at a ratio of 50% by mass and 50% by mass, respectively. .
- test sample was prepared by attaching a rod-shaped center electrode main body inside an insulator to a metal shell.
- the test sample was placed in a high-pressure chamber, and carbon dioxide gas (CO 2 ) was supplied to the high-pressure chamber at a pressure of about 5 MPa. It was applied at 1 kV/sec. Earthing (grounding) at that time was performed from the metal shell. Then, the breakdown voltage when penetrating the insulator was measured. The results are shown in Table 1.
- a pre-processed insulator was prepared for measuring the alkali corrosion withstand voltage. Specifically, when the center electrode body is mounted inside the insulator, the tip of the center electrode body is not exposed from the long leg part, and the thickness of the long leg part is substantially constant. was insulated in advance. Then, a rod-shaped center electrode body was mounted inside such an insulator, and the opening at the tip of the insulator was closed, which was assembled to the metal shell to prepare a test sample. In order to suppress concentration of an electric field on the tip of the center electrode body, the tip of the center electrode body is chamfered.
- the test sample was placed in a heating furnace maintained at about 200° C., and a voltage of 35 kV was applied from the tip of the center electrode body of the test sample for 100 hours. Earthing (grounding) at that time was performed from the metal shell. In this way, by continuously applying a voltage to the insulator of the test sample, a predetermined portion (electrode flange (expanded diameter portion)) of the middle body portion of the insulator faces in the radial direction without external discharge. Electric field concentration was generated in the portion where the contact point was located, and the predetermined portion was forcibly corroded with alkali.
- the presence or absence of alkali erosion can be determined by measuring the presence or absence of alkali metals such as Na and alkaline earth metals using an electron beam probe microalanizer (EPMA).
- EPMA electron beam probe microalanizer
- the resulting insulator was placed perpendicular to the axial direction at a position 2 mm away from the maximum diameter portion of the electrode flange (enlarged diameter portion) of the center electrode toward the rear end along the axial direction. cut in the direction Then, the cut surface of the obtained insulator was mirror-polished, and the structure of the cut surface (mirror-polished surface) was observed with an SEM (model "JSM-IT300LA", manufactured by JEOL Ltd.). The acceleration voltage of the SEM was set to 20 kV, and the magnification of the SEM was set to 500 times.
- the first observation area X of 192 ⁇ m ⁇ 255 ⁇ m is overlapped with the reference position, which is a position 0.2 mm in the radial direction from the inner peripheral surface of the insulator, so as not to overlap each other. was set, and a total of 20 SEM images corresponding to the 20 first observation regions were acquired. Then, the SEM images are subjected to image analysis processing using image analysis software (WinROOF (registered trademark), manufactured by Mitani Shoji Co., Ltd.), and the total area (100%) of the 20 first observation regions X , the area ratio (porosity) of all the pores included in the 20 first observation regions X was determined. The results are shown in Table 1.
- the insulator including the mirror-polished surface was kept in a predetermined electric furnace at 1400° C. for 1 hour, and then allowed to cool in the electric furnace. In this manner, thermal etching was performed on the mirror-polished surface of the test sample.
- a cut surface (thermally etched surface) of the obtained test sample was observed with an SEM.
- the acceleration voltage of the SEM was set to 20 kV, and the magnification of the SEM was set to 3000 times.
- a second observation area Y of 32 ⁇ m ⁇ 43 ⁇ m was formed so as to overlap the reference position, which is a position 0.2 mm in the radial direction from the inner peripheral surface of the insulator, but not to overlap each other.
- the reference position which is a position 0.2 mm in the radial direction from the inner peripheral surface of the insulator, but not to overlap each other.
- the grain size of the alumina grains in the 20 second observation regions Y was measured by performing image analysis processing based on JIS G0551 "ferrite/austenite grain size measurement”.
- the average particle size A of the alumina particles was obtained using the measurement result of the particle size of the alumina particles. The results are shown in Table 1.
- the particle size distribution of the alumina particles contained in the 20 second observation regions is regarded as a normal distribution, and the value of (A + 3 ⁇ ) [ ⁇ m] is obtained when the standard deviation of the particle size of the alumina particles is ⁇ . .
- the results are shown in Table 1.
- each alumina particle contained in the 20 second observation regions the major axis and minor axis of each alumina particle were measured by the intercept method. Then, for each second observation region, from among the measured long diameters of each alumina particle, by selecting the top three alumina particles with the largest long diameter, a total of 60 alumina particles with a large long diameter are used as representative alumina particles. elected.
- the aspect ratio (d1/d2) was determined based on the major axis and minor axis of each.
- the average aspect ratio B was determined for the selected 60 representative alumina particles. The results are shown in Table 1.
- Example 2 to 9 Insulators of Examples 2 to 9 were produced in the same manner as in Example 1, except that in the slurry production process, the ratio of cobblestones used when pulverizing the raw material powder was changed as appropriate.
- Comparative Example 1 In the slurry preparation process, when pulverizing the raw material powder with a wet pulverizer, 10% by mass and 40% by mass of cobbles with a diameter of 3 mm ( ⁇ 3 mm), cobbles with a diameter of 10 mm ( ⁇ 10 mm), and diameters of 30 mm ( ⁇ 30 mm), respectively.
- An insulator of Comparative Example 1 was produced in the same manner as in Example 1, except that , was used at a rate of 50% by mass.
- Comparative Examples 2 to 4 Insulators of Comparative Examples 2 to 4 were produced in the same manner as in Comparative Example 1, except that the ratio of cobblestones used in pulverizing the raw material powder in the slurry production process was changed as appropriate.
- Examples 1 to 9 were superior to Comparative Examples 1 to 4 in room temperature withstand voltage and alkali erosion withstand voltage.
- Examples 1 to 9 were superior to Example 5 in room temperature withstand voltage and alkali erosion withstand voltage.
- Examples 1 to 9 were superior to Examples 5 and 6 in room temperature withstand voltage and alkali erosion withstand voltage.
- Examples 1 to 4 and Examples 7 to 9 had excellent alkali erosion withstand voltage results.
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Spark Plugs (AREA)
Abstract
Description
上述した中心電極の後端側の部分と、絶縁体の内壁とが、径方向で互いに対向している箇所は、スパークプラグの使用時に、中心電極の先端側から後端側へ移動してきた熱が溜まり易く、しかも、中心電極に高電圧が印加された際に、電界が集中し易い。特に、中心電極の後端側の中でも、径方向に広がった形状の拡径部が、径方向で絶縁体の内壁と対向する箇所は、隙間がより狭くなっており、熱の集中や、電界の集中が起こり易い。そのため、絶縁体の中でも、径方向において、中心電極の拡径部と対向している部分は、最も過酷な環境下に置かれていると言える。
本発明者等は、アルミナ基焼結体からなる絶縁体と、絶縁体の内部に収容される中心電極とを備えたスパークプラグにおいて、その絶縁体の中胴部における特定箇所の内部に、ある一定以上の大きさを有する異常粒成長したアルミナ粒子が存在していると、中心電極に高電圧が印加された際に、そのアルミナ粒子の周りに電界が集中し易く、そして、そのアルミナ粒子付近が、絶縁体の破壊時の起点となっていることをつきとめた。
<1> 軸線方向に沿って延びた筒状をなし、アルミナ基焼結体からなる絶縁体と、 先端が前記絶縁体から露出し、かつ後端が前記絶縁体の内部に収容されるように前記絶縁体に挿入される棒状の電極本体部と、前記電極本体部の後端に連なり、前記電極本体部から径方向に広がった形をなし、かつ前記絶縁体の内壁と係止する拡径部と、を有する中心電極と、前記絶縁体の内部に収容され、かつ前記中心電極の前記後端側に配される導電性シール材とを備えるスパークプラグであって、前記拡径部の最大径の部分から前記軸線方向に沿って前記後端側へ2mm離れた位置で、前記絶縁体を前記軸線方向に対して垂直な方向に切断して得られる切断面を鏡面研磨することで得られる鏡面研磨面において、前記絶縁体の内周面側から径方向に0.2mmの位置である基準位置と重なりつつ、互いに重ならないように192μm×255μmの第1観察領域を20個設定した場合に、20個の前記第1観察領域の総面積(100%)に対する、20個の前記第1観察領域に含まれる全ての気孔の面積の割合(気孔率)が3.5%以下であり、前記鏡面研磨面をサーマルエッチングすることで得られるサーマルエッチング面において、前記基準位置と重なりつつ、互いに重ならないように32μm×43μmの第2観察領域を20個設定した場合に、20個の前記第2観察領域に含まれるアルミナ粒子の粒度分布を正規分布とみなして、前記アルミナ粒子の平均粒径をA、前記アルミナ粒子の粒径の標準偏差をσとしたときに、Aが1.9μm以上2.8μm以下であり、(A+3σ)が、3.0μm以下であるスパークプラグ。
本発明によれば、耐電圧性能等に優れる絶縁体を備えたスパークプラグを提供することができる。
本発明の実施形態1に係るスパークプラグ1を、図1~図6を参照しつつ説明する。図1は、実施形態1に係るスパークプラグ1の軸線AX方向に沿った断面図である。図1に示される上下方向に延びた一点鎖線は、スパークプラグ1の軸線AXであり、図1において、スパークプラグ1の長手方向(軸線AX方向)が、図1の上下方向に対応する。図1の下側に、スパークプラグ1の先端側が示され、図1の上側に、スパークプラグ1の後端側が示される。
中心電極3の電極鍔部(拡径部)31aの最大径の部分から軸線AX方向に沿って、スパークプラグ1の後端側へ2mm離れた位置で、絶縁体2を軸線AX方向に対して垂直な方向に切断して得られる切断面230を鏡面研磨することで得られる鏡面研磨面230aにおいて、絶縁体2の内周面2a側から径方向に0.2mmの位置である基準位置m1と重なりつつ、互いに重ならないように192μm×255μmの第1観察領域Xを20個設定した場合に、20個の第1観察領域Xの総面積(100%)に対する、20個の第1観察領域Xに含まれる全ての気孔の面積の割合(気孔率)が3.5%以下である。
鏡面研磨面230aをサーマルエッチングすることで得られるサーマルエッチング面230bにおいて、基準位置m1と重なりつつ、互いに重ならないように32μm×43μmの第2観察領域Yを20個設定した場合に、20個の第2観察領域に含まれるアルミナ粒子の粒度分布を正規分布とみなして、アルミナ粒子の平均粒径をA、アルミナ粒子の粒径の標準偏差をσとしたときに、Aが1.9μm以上2.8μm以下であり、(A+3σ)が、3.0μm以下である。
サーマルエッチング面230bにおける20個の第2観察領域Yにおいて、第2観察領域Y毎に、長径d1の大きい上位3個のアルミナ粒子を選出することで、長径d1の大きい60個の代表アルミナ粒子を選出した場合に、代表アルミナ粒子のアスペクト比の度数分布を正規分布とみなして、前記代表アルミナ粒子の平均アスペクト比をB、前記代表アルミナ粒子のアスペクト比の標準偏差をσとしたときに、(B+3σ)が4.8以下である。
サーマルエッチング面230bにおける20個の第2観察領域Yにおいて、代表アルミナ粒子のうち、アスペクト比が3.5以上のものが2個以下である。
鏡面研磨面230aにおける20個の第1観察領域Xにおいて、気孔の数が600個以下である。
スラリー作製工程は、原料粉末、バインダー及び溶媒を混合してスラリーを作製する工程である。原料粉末は、主成分として、焼成によりアルミナに転化する化合物の粉末(以下、Al化合物粉末)が使用される。Al化合物粉末としては、例えば、アルミナ粉末が使用される。
スラリー作製工程後のスラリーに対して、必要に応じて、脱泡工程を行ってもよい。脱泡工程では、例えば、混合(混錬)後のスラリーの入った容器を、真空脱泡装置内に配置して、減圧して低気圧環境下に置くことで、スラリー内に含まれる気泡が取り除かれる。脱泡前後のスラリーの密度を比較することで、スラリー中の気泡量を把握することができる。
造粒工程は、原料粉末等を含むスラリーから、球状の造粒粉を作製する工程である。スラリーから造粒粉を作製する方法としては、本発明の目的を損なわない限り特に制限はないが、例えば、スプレードライ法が挙げられる。スプレードライ法では、所定のスプレードライヤー装置を利用して、スラリーを噴霧乾燥することにより、所定の粒径を備えた造粒粉が得られる。なお、造粒粉の粒径は、本発明の目的を損なわない限り、特に制限はないが、例えば、212μm pass≧95%以下が好ましく、180μm pass≧95%以下がより好ましい。
成形工程は、造粒粉を、成形型を利用して所定形状に成形することで成形体を得る工程である。成形工程は、ラバープレス成形や金型プレス成形等によって行われる。本実施形態の場合、成形型(例えば、ラバープレス成形機の内ゴム型及び外ゴム型)を外周側から印加する圧力(プレス昇圧速度)は、段階的に上昇するように調整される。また、従来よりも高い圧力の範囲(例えば、100MPa以上)に調整されることが好ましい。なお、圧力の上限値は、本発明の目的を損なわない限り特に制限はないが、例えば、200MPa以下に調整されてもよい。
研削工程は、成形工程後に得られた成形体の加工取り代の除去や成形体の表面を研磨等する工程である。研削工程では、レジノイド砥石等を研削することにより、加工取り代の除去や成形体の表面の研磨等が行われる。このような研削工程により、成形体の形状が整えられる。
焼成工程は、研削工程により形状が整えられた成形体を焼成して、絶縁体を得る工程である。焼成工程では、例えば、大気雰囲気下で、1450℃以上1650℃以下で1~8時間焼成する。焼成後、成形体を冷却することにより、アルミナ基焼結体からなる絶縁体2が得られる。
(試験サンプルの作製)
上記実施形態1で例示したスパークプラグの絶縁体と、基本的な構成が同じである絶縁体を、上記実施形態1と同様の製造方法で作製(合計3本作製)した。なお、絶縁体の中胴部の厚みは、3mmである。また、スラリー作製工程において、原料粉末を湿式粉砕機で粉砕する際、直径3mmの玉石(φ3mm)と、直径10mmの玉石(φ10mm)とを、それぞれ50質量%、50質量%の割合で使用した。
絶縁体の内部に棒状の中心電極本体を装着させたものを、主体金具に組み付けて試験サンプルを作製した。その試験サンプルを高圧チャンバー内に設置し、その高圧チャンバー内に炭酸ガス(CO2)を約5MPaの圧力で供給した状態で、試験サンプルの中心電極本体の先端部より、電圧を昇圧速度0.1kV/secで印加した。その際のアース(接地)は、主体金具より行った。そして、絶縁体を貫通した際のブレイクダウン電圧を測定した。結果は、表1に示した。
アルカリ浸食耐電圧を測定するために予め加工が施された絶縁体を用意した。具体的には、絶縁体の内部に中心電極本体が装着された際に、中心電極本体の先端が脚長部から露出せず、かつ脚長部の厚みが略一定となるように、脚長部の周りに予め絶縁加工を施した。そして、そのような絶縁体の内部に棒状の中心電極本体を装着させつつ、絶縁体の先端の開口部を閉塞したものを、主体金具に組み付けて試験サンプルを作製した。なお、中心電極本体の先端に電界が集中することを抑制するため、中心電極本体の先端にはR面取りが施されている。その試験サンプルを、約200℃に保たれた加熱炉内に設置し、試験サンプルの中心電極本体の先端部より、35kVの電圧を100時間印加した。その際のアース(接地)は、主体金具より行った。このようにして、試験サンプルの絶縁体に電圧を印加し続けることで、外部放電することなく、絶縁体の中胴部の所定箇所(電極鍔部(拡径部)と径方向で、対向している部分)に、電界集中が発生し、その所定箇所を強制的にアルカリ浸食させた。なお、アルカリ浸食の有無は、絶縁体に対して、電子線プローブマイクロアラナイザー(EPMA)を用いてNa等のアルカリ金属やアルカリ土類金属の有無を測定することで判断できる。
得られた絶縁体について、中心電極の電極鍔部(拡径部)の最大径の部分から軸線方向に沿って、後端側へ2mm離れた位置で、絶縁体を軸線方向に対して垂直な方向に切断した。そして、得られた絶縁体の切断面を鏡面状に研磨し、その切断面(鏡面研磨面)の組織をSEM(型式「JSM-IT300LA」、日本電子株式会社製)で観察した。SEMの加速電圧は、20kVに設定し、SEMの倍率は、500倍に設定した。そして、その切断面(鏡面研磨面)において、絶縁体の内周面側から径方向に0.2mmの位置である基準位置と重なりつつ、互いに重ならないように192μm×255μmの第1観察領域Xを20個設定し、それら20個の第1観察領域に対応した合計20個のSEM画像を取得した。そして、それらのSEM画像に対して、画像解析ソフト(WinROOF(登録商標)、三谷商事株式会社製)による画像解析処理を実行して、20個の第1観察領域Xの総面積(100%)に対する、20個の第1観察領域Xに含まれる全ての気孔の面積の割合(気孔率)を求めた。結果は、表1に示した。
鏡面研磨面を含む上記絶縁体を、所定の電気炉に入れた状態で、1400℃で1時間保持し、その後、電気炉内で放冷を行った。このようにして、試験サンプルの鏡面研磨面に対して、サーマルエッチングを行った。得られた試験サンプルの切断面(サーマルエッチング面)を、SEMで観察した。SEMの加速電圧は、20kVに設定し、SEMの倍率は、3000倍に設定した。
スラリー作製工程において、原料粉末を粉砕する際に使用する玉石の比率を、適宜、変更したこと以外は、実施例1と同様にして、実施例2~9の絶縁体を作製した。
スラリー作製工程において、原料粉末を湿式粉砕機で粉砕する際、直径3mmの玉石(φ3mm)と、直径10mmの玉石(φ10mm)と、直径30mm(φ30mm)とを、それぞれ10質量%、40質量%、50質量%の割合で使用したこと以外は、実施例1と同様にして、比較例1の絶縁体を作製した。
スラリー作製工程において、原料粉末を粉砕する際に使用する玉石の比率を、適宜、変更したこと以外は、比較例1と同様にして、比較例2~4の絶縁体を作製した。
Claims (4)
- 軸線方向に沿って延びた筒状をなし、アルミナ基焼結体からなる絶縁体と、
先端が前記絶縁体から露出し、かつ後端が前記絶縁体の内部に収容されるように前記絶縁体に挿入される棒状の電極本体部と、前記電極本体部の後端に連なり、前記電極本体部から径方向に広がった形をなし、かつ前記絶縁体の内壁と係止する拡径部と、を有する中心電極と、
前記絶縁体の内部に収容され、かつ前記中心電極の前記後端側に配される導電性シール材とを備えるスパークプラグであって、
前記拡径部の最大径の部分から前記軸線方向に沿って前記後端側へ2mm離れた位置で、前記絶縁体を前記軸線方向に対して垂直な方向に切断して得られる切断面を鏡面研磨することで得られる鏡面研磨面において、前記絶縁体の内周面側から径方向に0.2mmの位置である基準位置と重なりつつ、互いに重ならないように192μm×255μmの第1観察領域を20個設定した場合に、20個の前記第1観察領域の総面積(100%)に対する、20個の前記第1観察領域に含まれる全ての気孔の面積の割合(気孔率)が3.5%以下であり、
前記鏡面研磨面をサーマルエッチングすることで得られるサーマルエッチング面において、前記基準位置と重なりつつ、互いに重ならないように32μm×43μmの第2観察領域を20個設定した場合に、20個の前記第2観察領域に含まれるアルミナ粒子の粒度分布を正規分布とみなして、前記アルミナ粒子の平均粒径をA、前記アルミナ粒子の粒径の標準偏差をσとしたときに、Aが1.9μm以上2.8μm以下であり、(A+3σ)が、3.0μm以下であるスパークプラグ。 - 前記サーマルエッチング面における20個の前記第2観察領域において、前記第2観察領域毎に、長径の大きい上位3個のアルミナ粒子を選出することで、長径の大きい60個の代表アルミナ粒子を選出した場合に、前記代表アルミナ粒子のアスペクト比の度数分布を正規分布とみなして、前記代表アルミナ粒子の平均アスペクト比をB、前記代表アルミナ粒子のアスペクト比の標準偏差をσとしたときに、(B+3σ)が4.8以下である請求項1に記載のスパークプラグ。
- 前記サーマルエッチング面における20個の前記第2観察領域において、前記代表アルミナ粒子のうち、前記アスペクト比が3.5以上のものが2個以下である請求項2に記載のスパークプラグ。
- 前記鏡面研磨面における20個の前記第1観察領域において、前記気孔の数が600個以下である請求項1から請求項3の何れか一項に記載のスパークプラグ。
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE112022003085.2T DE112022003085T5 (de) | 2021-06-14 | 2022-06-14 | Zündkerze |
CN202280041653.7A CN117529859A (zh) | 2021-06-14 | 2022-06-14 | 火花塞 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2021098896A JP7305708B2 (ja) | 2021-06-14 | 2021-06-14 | スパークプラグ |
JP2021-098896 | 2021-06-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2022264997A1 true WO2022264997A1 (ja) | 2022-12-22 |
Family
ID=84526473
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2022/023733 WO2022264997A1 (ja) | 2021-06-14 | 2022-06-14 | スパークプラグ |
Country Status (4)
Country | Link |
---|---|
JP (1) | JP7305708B2 (ja) |
CN (1) | CN117529859A (ja) |
DE (1) | DE112022003085T5 (ja) |
WO (1) | WO2022264997A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN117669098A (zh) * | 2024-01-31 | 2024-03-08 | 潍柴动力股份有限公司 | 一种火花塞设计方法、装置、设备和火花塞 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007250379A (ja) * | 2006-03-16 | 2007-09-27 | Ngk Spark Plug Co Ltd | 内燃機関用スパークプラグ及びその製造方法 |
JP2019009053A (ja) * | 2017-06-27 | 2019-01-17 | 日本特殊陶業株式会社 | スパークプラグ |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP6843809B2 (ja) | 2018-10-03 | 2021-03-17 | 日本特殊陶業株式会社 | スパークプラグ |
-
2021
- 2021-06-14 JP JP2021098896A patent/JP7305708B2/ja active Active
-
2022
- 2022-06-14 CN CN202280041653.7A patent/CN117529859A/zh active Pending
- 2022-06-14 WO PCT/JP2022/023733 patent/WO2022264997A1/ja active Application Filing
- 2022-06-14 DE DE112022003085.2T patent/DE112022003085T5/de active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007250379A (ja) * | 2006-03-16 | 2007-09-27 | Ngk Spark Plug Co Ltd | 内燃機関用スパークプラグ及びその製造方法 |
JP2019009053A (ja) * | 2017-06-27 | 2019-01-17 | 日本特殊陶業株式会社 | スパークプラグ |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN117669098A (zh) * | 2024-01-31 | 2024-03-08 | 潍柴动力股份有限公司 | 一种火花塞设计方法、装置、设备和火花塞 |
CN117669098B (zh) * | 2024-01-31 | 2024-05-17 | 潍柴动力股份有限公司 | 一种火花塞设计方法、装置、设备和火花塞 |
Also Published As
Publication number | Publication date |
---|---|
DE112022003085T5 (de) | 2024-03-28 |
JP7305708B2 (ja) | 2023-07-10 |
CN117529859A (zh) | 2024-02-06 |
JP2022190529A (ja) | 2022-12-26 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP4690230B2 (ja) | 内燃機関用スパークプラグ及びその製造方法 | |
JP4756087B2 (ja) | スパークプラグ及びスパークプラグの製造方法 | |
JP4607253B2 (ja) | スパークプラグ及びスパークプラグの製造方法 | |
EP2413441B1 (en) | Spark plug | |
US8093791B2 (en) | Spark plug having particular insulator | |
JP5211251B1 (ja) | スパークプラグ | |
JP4651732B1 (ja) | スパークプラグ | |
US20140336035A1 (en) | Insulator for spark plug and spark plug | |
WO2022264997A1 (ja) | スパークプラグ | |
JP6843809B2 (ja) | スパークプラグ | |
EP3148021B1 (en) | Spark plug | |
CN104009398A (zh) | 绝缘体及火花塞 | |
JPH0712969B2 (ja) | アルミナ磁器および点火プラグ | |
JP6440602B2 (ja) | スパークプラグ | |
US9302942B2 (en) | Alumina sintered body and spark plug | |
JP5349670B1 (ja) | スパークプラグ | |
WO2022265008A1 (ja) | スパークプラグ | |
WO2022264996A1 (ja) | スパークプラグ |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 22824985 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 18567558 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 202280041653.7 Country of ref document: CN |
|
WWE | Wipo information: entry into national phase |
Ref document number: 112022003085 Country of ref document: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 22824985 Country of ref document: EP Kind code of ref document: A1 |