WO2023281956A1 - スパークプラグ - Google Patents
スパークプラグ Download PDFInfo
- Publication number
- WO2023281956A1 WO2023281956A1 PCT/JP2022/022751 JP2022022751W WO2023281956A1 WO 2023281956 A1 WO2023281956 A1 WO 2023281956A1 JP 2022022751 W JP2022022751 W JP 2022022751W WO 2023281956 A1 WO2023281956 A1 WO 2023281956A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- threaded portion
- spark plug
- effective diameter
- hole
- axial direction
- Prior art date
Links
- 229910052751 metal Inorganic materials 0.000 claims abstract description 26
- 239000002184 metal Substances 0.000 claims abstract description 26
- 239000012212 insulator Substances 0.000 claims description 16
- 230000002093 peripheral effect Effects 0.000 claims description 12
- 238000005516 engineering process Methods 0.000 abstract description 2
- 238000002485 combustion reaction Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 9
- 230000003647 oxidation Effects 0.000 description 7
- 238000007254 oxidation reaction Methods 0.000 description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000003566 sealing material Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000446 fuel Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 239000002826 coolant Substances 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 229910000990 Ni alloy Inorganic materials 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 238000013021 overheating Methods 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000575 Ir alloy Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000005388 borosilicate glass Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- 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
- H01T13/02—Details
- H01T13/16—Means for dissipating heat
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/32—Sparking plugs characterised by features of the electrodes or insulation characterised by features of the earthed electrode
-
- 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
- the present disclosure relates to spark plugs.
- Patent Document 1 As a spark plug for ignition used in an internal combustion engine, a spark plug that is attached to the engine head and generates spark discharge between the tip of the center electrode and the ground electrode is known (for example, Patent Document 1).
- a spark plug disclosed in Patent Literature 1 a through hole is formed in the metallic shell to penetrate in the radial direction, and a rod-shaped ground electrode extending in the radial direction is inserted into the through hole and fixed.
- the ground electrode becomes hot due to the combustion of the air-fuel mixture. Therefore, in a spark plug in which a ground electrode is inserted into a through hole formed in a metal shell and welded, the welded portion of the ground electrode may be oxidized due to overheating.
- the spark plug described in Patent Document 1 if the male thread of the metal shell is formed on the tip side in the axial direction of the welded portion of the ground electrode, then the tip side of the welded portion in the axial direction is formed. and the rear end side, and as a result, there is a possibility that stress is generated in the welded portion. Such oxidation and generation of stress in the welded portion may cause the ground electrode to come off, resulting in deterioration in the durability of the spark plug. Therefore, there has been a demand for a technology capable of improving the durability of spark plugs.
- a spark plug includes an insulator formed with a shaft hole extending in the axial direction, a center electrode arranged in the shaft hole and having a tip portion protruding toward the tip of the shaft hole, and an inner circumference of the insulator.
- a cylindrical metal shell having a threaded portion formed on its outer peripheral surface, one end of which is inserted into and welded to a through hole provided in the metal shell, and the other end of which is the tip of the center electrode; a ground electrode that forms a discharge gap between the ground electrode and the through hole, wherein the threaded portion includes a first threaded portion located on the rear end side of the through hole in the axial direction; a second threaded portion located on the tip side in the axial direction relative to the hole, wherein the effective diameter of the second threaded portion is larger than the effective diameter of the first threaded portion.
- the effective diameter of the second threaded portion located on the distal end side of the through hole in the axial direction is the effective diameter of the first threaded portion located on the rear end side of the through hole in the axial direction.
- the effective diameter of the second threaded portion may be 100.30% or more of the effective diameter of the first threaded portion.
- the effective diameter of the second threaded portion is 100.30% or more of the effective diameter of the first threaded portion, so the gap between the second threaded portion and the female thread of the engine head can be further reduced. It is possible to further promote the heat transfer of the ground electrode in the second threaded portion. As a result, the oxidation of the one end of the ground electrode can be further suppressed, the temperature difference between the first threaded portion and the second threaded portion can be further reduced, and the generation of stress at the one end can be further suppressed. Therefore, it is possible to further prevent the ground electrode from falling out of the through-hole during the heating and cooling cycle of the combustion chamber, thereby further improving the durability of the spark plug.
- the length of the second threaded portion may be shorter than the length of the first threaded portion in the axial direction.
- the length of the second threaded portion in the axial direction is shorter than the length of the first threaded portion, the length of the second threaded portion, which has a large effective diameter, along the axial direction can be shortened.
- the threaded portion can be easily screwed into the female thread formed on the engine head. , it is possible to suppress the deterioration of the assembleability of the spark plug.
- the present invention can be implemented in various forms, for example, it can be implemented in the form of a spark plug manufacturing method, an engine head with a spark plug attached, and the like.
- FIG. 2 is a partial cross-sectional view showing a schematic configuration of a spark plug;
- FIG. 2 is an enlarged cross-sectional view showing the vicinity of the tip of the spark plug;
- FIG. 1 is a partial cross-sectional view showing a schematic configuration of a spark plug 100 as one embodiment of the present disclosure.
- the external shape of the spark plug 100 is shown on the right side of the paper
- the cross-sectional shape of the spark plug 100 is shown on the left side of the paper, with the axis CA, which is the axial center of the spark plug 100, as the boundary.
- the lower side in FIG. 1 (the side on which the ground electrode 40 described later is arranged) along the axis CA is called the tip side
- the upper side in FIG. side) is called the rear end side
- the direction along the axis CA is called the axial direction AD.
- the engine head 90 to which the spark plug 100 is attached is indicated by a dashed line.
- the engine head 90 is generally provided with a coolant flow path (not shown) for circulating a coolant.
- the spark plug 100 is attached to the engine head 90 so that its tip side is exposed inside the combustion chamber 95 .
- a spark plug 100 includes an insulator 10 , a center electrode 20 , a metal shell 30 , a ground electrode 40 and a terminal metal fitting 50 .
- Axis CA of spark plug 100 coincides with the axes of insulator 10 , center electrode 20 , metal shell 30 , and terminal metal fitting 50 .
- the insulator 10 has a substantially tubular external shape in which a shaft hole 11 extending in the axial direction AD is formed. A part of the center electrode 20 is accommodated in the axial hole 11 on the front end side, and a part of the terminal fitting 50 is accommodated on the rear end side. Therefore, the insulator 10 holds the center electrode 20 on the inner peripheral side.
- the insulator 10 is housed in a shaft hole 31 of a metal shell 30 described later at its tip side portion and exposed from the shaft hole 31 at its rear end side portion.
- the insulator 10 is composed of an insulator formed by firing a ceramic material such as alumina.
- the center electrode 20 is a rod-shaped electrode extending along the axial direction AD and arranged in the axial hole 11 .
- a tip portion 21 of the center electrode 20 protrudes toward the tip side of the shaft hole 11 .
- a noble metal tip made of, for example, platinum or an iridium alloy may be joined to the distal end portion 21 .
- the center electrode 20 of this embodiment is made of a nickel alloy containing nickel as a main component.
- a front end side sealing material 61, a resistor 62, and a rear end side are arranged in order from the front end side to the rear end side.
- a side seal member 63 is arranged. Therefore, the center electrode 20 is electrically connected to the terminal fitting 50 at the rear end side through the front end side seal member 61 , the resistor 62 , and the rear end side seal member 63 .
- the resistor 62 contains ceramic powder, a conductive material, and glass as materials.
- the resistor 62 functions as an electrical resistance between the terminal fitting 50 and the center electrode 20, thereby suppressing the generation of noise when spark discharge is generated.
- the front end side sealing material 61 and the rear end side sealing material 63 each contain conductive glass powder as a material.
- the front end side sealing material 61 and the rear end side sealing material 63 contain a mixed powder of copper powder and calcium borosilicate glass powder as a material.
- the terminal fitting 50 is provided at the end of the spark plug 100 on the rear end side.
- the tip side of the terminal fitting 50 is accommodated in the shaft hole 11 of the insulator 10 , and the rear end side of the terminal fitting 50 is exposed from the shaft hole 11 .
- a high voltage cable (not shown) is connected to the terminal fitting 50 to apply a high voltage. This application causes a spark discharge to occur in a discharge gap G, which will be described later. A spark generated in the discharge gap G ignites the air-fuel mixture in the combustion chamber 95 .
- the metal shell 30 has a substantially cylindrical external shape with a shaft hole 31 formed along the axial direction AD, and holds the insulator 10 in the shaft hole 31 . In other words, the metal shell 30 holds the insulator 10 on the inner peripheral side.
- the metal shell 30 is made of, for example, low-carbon steel, and is entirely plated with nickel plating, zinc plating, or the like.
- a tool engaging portion 32 and a screw portion 33 are formed on the outer peripheral surface of the metallic shell 30 . The tool engaging portion 32 engages with a tool (not shown) when attaching the spark plug 100 to the engine head 90 .
- the threaded portion 33 has a thread formed on the outer peripheral surface thereof in a region on the distal end side of the metallic shell 30 and is screwed into the female threaded portion 93 of the engine head 90 . A detailed description of the screw portion 33 will be given later.
- FIG. 2 is a cross-sectional view showing the vicinity of the tip of the spark plug 100 in an enlarged manner.
- the metal shell 30 is provided with a through hole 37 penetrating in the radial direction.
- the through hole 37 is formed on the distal end side of the distal end portion 21 of the center electrode 20 in the axial direction AD, and allows the outer peripheral surface and the inner peripheral surface of the metallic shell 30 to communicate with each other.
- the through hole 37 is provided at one location in the metal shell 30 in the circumferential direction.
- a ground electrode 40 is fixed to the through hole 37 .
- the through hole 37 has a stepped shape, and the inner diameter of the through hole 37 is formed larger on the outer peripheral side of the metal shell 30 than on the inner peripheral side.
- the ground electrode 40 is made of a rod-shaped metal member and arranged so as to extend in the radial direction.
- One end 41 of the ground electrode 40 is inserted into the through hole 37 and welded. Therefore, the one end portion 41 can also be called a welded portion.
- the other end 42 of the ground electrode 40 faces the tip 21 of the center electrode 20 .
- the other end 42 forms a discharge gap G for spark discharge with the tip 21 of the center electrode 20 .
- the ground electrode 40 of this embodiment is made of a nickel alloy containing nickel as a main component.
- the threaded portion 33 formed on the outer peripheral surface of the metal shell 30 has a first threaded portion 34 and a second threaded portion 35 .
- the first threaded portion 34 is positioned closer to the rear end in the axial direction AD than the through hole 37 is.
- the second screw portion 35 is positioned closer to the tip side in the axial direction AD than the through hole 37 is.
- the length of the second threaded portion 35 is shorter than the length of the first threaded portion 34 in the axial direction AD.
- the effective diameter of the second threaded portion 35 is larger than the effective diameter of the first threaded portion 34 .
- the term "effective diameter" indicates a value defined in JIS B 0205 2001.
- the effective diameter of the first threaded portion 34 can be obtained by calculating the average value of the values measured for each thread of the first threaded portion 34 .
- the effective diameter of the second threaded portion 35 can be obtained by calculating the average value of the values measured for each thread of the second threaded portion 35 .
- the effective diameter of the second threaded portion 35 is preferably 100.30% or more of the effective diameter of the first threaded portion 34 .
- the effective diameter of the second threaded portion 35 is preferably 101.00% or less of the effective diameter of the first threaded portion 34 .
- the threaded portion 33 is formed such that the effective diameter increases from the rear end side toward the front end side in the axial direction AD.
- the threaded portion 33 is formed such that the effective diameter of each thread of the first threaded portion 34 is substantially constant, and the effective diameter of each thread of the second threaded portion 35 is substantially constant. It may be formed such that the first threaded portion 34 and the second threaded portion 35 are continuously connected. In this case, the first threaded portion 34 and the second threaded portion 35 may be connected smoothly, or may be connected to form a step.
- the screw portion 33 can be formed by, for example, rolling or cutting.
- the effective diameter of the second threaded portion 35 is reduced to the second by making the tightening of the die weaker at the position where the second threaded portion 35 is formed than at the position where the first threaded portion 34 is formed. It may be formed larger than the effective diameter of the 1 screw portion 34 . Rolling may also be performed using a die having a step formed at a position corresponding to the formation position of the first screw portion 34 and the formation position of the second screw portion 35 .
- a step may be provided between the forming position of the first threaded portion 34 and the forming position of the second threaded portion 35 in the cylindrical metal shell 30 .
- the formation position of 34 and the formation position of the second screw portion 35 may be formed in a tapered shape in advance.
- the first threaded portion 34 and the second threaded portion 35 are formed integrally, but may be formed separately.
- the through hole 37 may be formed before the threaded portion 33 is formed, or may be formed after the threaded portion 33 is formed.
- the ground electrode 40 is exposed to combustion of the air-fuel mixture and is in a high temperature state. Therefore, in the spark plug 100 in which the ground electrode 40 is inserted into the through hole 37 formed in the metal shell 30 and welded, the one end 41 of the ground electrode 40 may be oxidized due to overheating.
- the second screw portion 35 is formed on the tip side of the through hole 37 in the axial direction AD. 2 screw portion 35 and female screw portion 93 of engine head 90 can be screwed together.
- the engine head 90 is generally provided with a coolant flow path, by screwing the second threaded portion 35 and the female threaded portion 93 together, the heat transfer path of the ground electrode 40 can be achieved even on the distal end side, which tends to be heated to a higher temperature. can be ensured. Therefore, it is possible to suppress an excessive temperature rise of the one end portion 41 of the ground electrode 40 , thereby suppressing oxidation of the one end portion 41 of the ground electrode 40 .
- the vicinity of the tip of the spark plug 100 tends to become hotter toward the tip side in the axial direction AD. Therefore, if the second threaded portion 35 is formed on the distal end side in the axial direction AD of the through hole 37 to which the ground electrode 40 is fixed, the second threaded portion 35 and the through hole 37 are axially axially advanced. A temperature difference may occur between the first threaded portion 34 formed on the tip side of the .
- the effective diameter of the second threaded portion 35 is larger than the effective diameter of the first threaded portion 34, so the contact area between the second threaded portion 35 and the female threaded portion 93 can be increased. .
- the gap between the second threaded portion 35 and the female threaded portion 93 can be reduced. Therefore, the heat of the ground electrode 40 can be effectively dissipated on the distal end side, where the temperature tends to be higher, so that the oxidation of the one end portion 41 of the ground electrode 40 can be further suppressed.
- the effective diameter of the second threaded portion 35 is larger than the effective diameter of the first threaded portion 34, that is, the effective diameter of the first threaded portion 34 is smaller than the effective diameter of the second threaded portion 35, the first thread The contact area between the portion 34 and the female screw portion 93 can be reduced. In other words, the gap between the first threaded portion 34 and the female threaded portion 93 can be increased.
- the spark plug 100 of the present embodiment it is possible to promote the heat transfer of the ground electrode 40 at the second threaded portion 35 to suppress the oxidation of the one end portion 41, and to prevent the first threaded portion 34 from It is possible to suppress the occurrence of stress in the one end portion 41 by reducing the temperature difference with the screw portion 35 . As a result, it is possible to prevent the ground electrode 40 from falling out of the through hole 37 during the thermal cycle of the combustion chamber 95, so that the durability of the spark plug 100 can be improved.
- the effective diameter of the second threaded portion 35 is larger than the effective diameter of the first threaded portion 34, airtightness between the second threaded portion 35 and the engine head 90 can be ensured. As a result, it is possible to prevent the mixture of fuel from leaking from the combustion chamber. Further, since the one end portion 41 of the ground electrode 40 is inserted into the through-hole 37 and welded, even if the through-hole 37 expands due to thermal cycles, the ground electrode 40 is prevented from falling out of the through-hole 37. can be suppressed.
- the effective diameter of the second threaded portion 35 is 100.30% or more of the effective diameter of the first threaded portion 34, the gap between the second threaded portion 35 and the female threaded portion 93 is further reduced, Heat dissipation of the ground electrode 40 in the portion 35 can be further promoted.
- oxidation of the one end portion 41 can be further suppressed, and the temperature difference between the first threaded portion 34 and the second threaded portion 35 can be further reduced, thereby further suppressing the generation of stress in the one end portion 41 . Therefore, it is possible to further prevent the ground electrode 40 from falling out of the through-hole 37 during the thermal cycle of the combustion chamber 95, so that the durability of the spark plug 100 can be further improved.
- the length of the second threaded portion 35 is shorter than the length of the first threaded portion 34 in the axial direction AD, the length of the second threaded portion 35 having a large effective diameter along the axial direction AD can be shortened.
- the female threaded portion 93 formed in the engine head 90 can be threaded into the metal shell 30 . Since the portion 33 can be easily screwed together, deterioration of the assembleability of the spark plug 100 can be suppressed.
- spark plugs 100 having screw portions 33 with different effective diameters were produced. More specifically, as Examples 1 to 5, spark plugs 100 in which the effective diameter of the second threaded portion 35 was larger than the effective diameter of the first threaded portion 34 were produced. Further, as Comparative Example 1, a spark plug was manufactured in which the effective diameter of the second threaded portion 35 and the effective diameter of the first threaded portion 34 were the same, that is, the effective diameter of the threaded portion 33 was constant in the axial direction AD. . Further, as comparative examples 2 and 3, spark plugs were manufactured in which the effective diameter of the second threaded portion 35 was smaller than the effective diameter of the first threaded portion 34 . In the example and the comparative example, the nominal diameter was set to M10, the configurations other than the effective diameter of the screw portion 33 were the same, and the number of samples was set to 10 for each.
- Table 1 shows the results of the durability test.
- Comparative Example 1 Compared to Comparative Example 1, which had the same diameter, the number of cycles until falling off was increased by 3% or more, indicating that the durability was particularly improved. On the other hand, in Comparative Examples 2 and 3 in which the effective diameter of the second threaded portion 35 is smaller than the effective diameter of the first threaded portion 34, the effective diameter of the second threaded portion 35 is the same as the effective diameter of the first threaded portion 34. As compared with Comparative Example 1, which is , no durability improvement effect was observed.
- the configuration of the threaded portion 33 in the above embodiment is merely an example, and can be changed in various ways.
- the length of the second threaded portion 35 may be the same as the length of the first threaded portion 34 or longer than the length of the first threaded portion 34 .
- the effective diameter of the second threaded portion 35 is not limited to 100.30% or more of the effective diameter of the first threaded portion 34, and may be any value exceeding 100% of the effective diameter of the first threaded portion 34. may With this configuration as well, the effective diameter of the second threaded portion 35 is made larger than the effective diameter of the first threaded portion 34, so that the durability of the spark plug 100 can be improved.
- the spark plug 100 in the above embodiment is merely an example, and various modifications are possible.
- the spark plug 100 may be a pre-chamber plug in which a cover is provided at the tip of the metallic shell 30 to form an auxiliary combustion chamber.
- the present invention is not limited to the above-described embodiments, and can be implemented in various configurations without departing from the spirit of the present invention.
- the technical features in the embodiments corresponding to the technical features in the respective modes described in the outline of the invention are used to solve some or all of the above problems, or Substitutions and combinations may be made as appropriate to achieve part or all.
- the technical feature is not described as essential in this specification, it can be deleted as appropriate.
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Abstract
Description
図1は、本開示の一実施形態としてのスパークプラグ100の概略構成を示す部分断面図である。図1では、スパークプラグ100の軸心である軸線CAを境界として、紙面右側にスパークプラグ100の外観形状を示し、紙面左側にスパークプラグ100の断面形状を示している。以下の説明では、軸線CAに沿った図1の下方側(後述する接地電極40が配置されている側)を先端側と呼び、図1の上方側(後述する端子金具50が配置されている側)を後端側と呼び、軸線CAに沿った方向を軸線方向ADと呼ぶ。図1では、説明の便宜上、スパークプラグ100が取り付けられるエンジンヘッド90を破線で示している。エンジンヘッド90には、一般に、冷却媒体を循環させる図示しない冷媒流路が設けられている。スパークプラグ100は、その先端側が燃焼室95内に露出するようにエンジンヘッド90に取り付けられている。
以下、実施例により本発明をさらに具体的に説明するが、本発明は以下の実施例に限定されるものではない。
以下の表1に示すように、ネジ部33の有効径が互いに異なるスパークプラグ100を作製した。より具体的には、実施例1~5として、第2ネジ部35の有効径が第1ネジ部34の有効径よりも大きいスパークプラグ100を作製した。また、比較例1として、第2ネジ部35の有効径と第1ネジ部34の有効径とが同じである、すなわちネジ部33の有効径が軸線方向ADにおいて一定であるスパークプラグを作製した。また、比較例2、3として、第2ネジ部35の有効径が第1ネジ部34の有効径よりも小さいスパークプラグを作製した。実施例と比較例とにおいて、いずれも呼び径はM10とし、ネジ部33の有効径以外の構成は互いに同じとし、サンプル数はそれぞれ10とした。
実施例のスパークプラグ100と比較例のスパークプラグ100とを、エンジンヘッド90を再現したブッシュに組み付け、主体金具30の軸孔31側から、接地電極40の一端部41周辺をバーナーで加熱した。接地電極40の電極温度1000℃の加熱2分と接地電極40の電極温度200℃の冷却1分とを冷熱サイクルの1サイクルとして、接地電極40が主体金具30の貫通孔37から脱落するまで冷熱サイクルを繰り返し実施した。各試料において、接地電極40が脱落したサイクル数を求め、比較例1におけるサイクル数を基準として耐久性を評価した。評価基準を以下に示す。
A:脱落までのサイクル数が3%以上増加しており、耐久性向上効果が大きい
B:脱落までのサイクル数が1%以上3%未満増加しており、耐久性向上効果がある
C:脱落までのサイクル数の増加が有意には認められず、耐久性向上効果がない
上記実施形態におけるネジ部33の構成は、あくまで一例であり、種々変更可能である。例えば、軸線方向ADにおいて、第2ネジ部35の長さは、第1ネジ部34の長さと同じであってもよく、第1ネジ部34の長さよりも長くてもよい。また、例えば、第2ネジ部35の有効径は、第1ネジ部34の有効径の100.30%以上に限らず、第1ネジ部34の有効径の100%を超える任意の値であってもよい。このような構成によっても、第2ネジ部35の有効径が第1ネジ部34の有効径よりも大きく形成されることによって、スパークプラグ100の耐久性を向上できる。
Claims (3)
- 軸線方向に延びる軸孔が形成された絶縁体と、
前記軸孔に配置され、自身の先端部が前記軸孔の先端側に突出する中心電極と、
前記絶縁体を内周側に保持し、外周面にネジ部が形成された筒状の主体金具と、
一端部が前記主体金具に設けられた貫通孔に挿入されて溶接され、他端部が前記中心電極の前記先端部との間で放電ギャップを形成する接地電極と、
を備えるスパークプラグであって、
前記ネジ部は、前記貫通孔よりも前記軸線方向の後端側に位置する第1ネジ部と、前記貫通孔よりも前記軸線方向の先端側に位置する第2ネジ部と、を有し、
前記第2ネジ部の有効径は、前記第1ネジ部の有効径よりも大きいことを特徴とする、スパークプラグ。 - 請求項1に記載のスパークプラグにおいて、
前記第2ネジ部の有効径は、前記第1ネジ部の有効径の100.30%以上であることを特徴とする、スパークプラグ。 - 請求項1または請求項2に記載のスパークプラグにおいて、
前記軸線方向において、前記第2ネジ部の長さは、前記第1ネジ部の長さよりも短いことを特徴とする、スパークプラグ。
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US18/559,754 US20240243556A1 (en) | 2021-07-09 | 2022-06-06 | Spark plug |
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JP (1) | JP2023010082A (ja) |
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JP6954944B2 (ja) * | 2019-03-15 | 2021-10-27 | 日本特殊陶業株式会社 | 点火プラグ |
JP6986041B2 (ja) * | 2019-04-01 | 2021-12-22 | 日本特殊陶業株式会社 | スパークプラグ |
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WO2021140756A1 (ja) * | 2020-01-10 | 2021-07-15 | 日本特殊陶業株式会社 | スパークプラグ |
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JP7392563B2 (ja) * | 2020-04-24 | 2023-12-06 | 株式会社デンソー | 内燃機関用のスパークプラグ |
JP7501129B2 (ja) * | 2020-06-09 | 2024-06-18 | 株式会社デンソー | 内燃機関用のスパークプラグ |
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JP2023010082A (ja) | 2023-01-20 |
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