WO2015093003A1 - スパークプラグ - Google Patents
スパークプラグ Download PDFInfo
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- WO2015093003A1 WO2015093003A1 PCT/JP2014/006115 JP2014006115W WO2015093003A1 WO 2015093003 A1 WO2015093003 A1 WO 2015093003A1 JP 2014006115 W JP2014006115 W JP 2014006115W WO 2015093003 A1 WO2015093003 A1 WO 2015093003A1
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- WIPO (PCT)
- Prior art keywords
- outer layer
- spark plug
- ground electrode
- content
- core
- Prior art date
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/39—Selection of materials for electrodes
-
- 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
Definitions
- the present invention relates to a spark plug.
- spark plugs have been used in internal combustion engines.
- the spark plug has an electrode that forms a gap.
- an electrode for example, a ground electrode having an outer layer portion excellent in oxidation resistance and a core portion excellent in thermal conductivity has been proposed. If such a ground electrode is employed, the oxidation resistance can be improved by lowering the temperature of the ground electrode.
- the ground electrode can deteriorate due to various causes.
- the ground electrode may be consumed by a spark. Further, the ground electrode may be oxidized by being exposed to the fuel gas. As described above, since the ground electrode can be deteriorated due to various causes, it is not easy to improve the durability of the ground electrode. *
- the main advantage of the present invention is to improve the durability of the ground electrode.
- a central electrode extending in the axial direction; A ground electrode that forms a gap with the tip surface of the central electrode; A spark plug having The ground electrode is An outer layer forming part of the surface of the ground electrode; A core part having an exposed surface that is part of the outer layer and formed of a material having a higher thermal conductivity than the outer layer, and is exposed from the outer layer; Have The outer layer is formed of a material containing nickel as a main component and 14 wt% or more of chromium, The core is formed of a material containing nickel having a higher content than the content of nickel in the outer layer, When the tip surface of the center electrode is projected in parallel with the axial direction, the exposed surface includes a portion of the ground electrode that overlaps the projected tip surface, Spark plug.
- the spark erosion resistance of the portion of the surface of the ground electrode where discharge can occur can be improved by the exposed core portion.
- the durability of the ground electrode can be improved.
- the spark plug according to any one of Application Examples 1 to 3 The chromium content of the core is zero, or less than the chromium content of the outer layer,
- the ground electrode has a diffusion layer formed between the core and the outer layer,
- the diffusion layer has a thickness of 5 ⁇ m or more. Spark plug.
- the spark plug according to any one of Application Examples 1 to 4 The core portion is a spark plug including 96 wt% or more of nickel and 0.05 wt% or more of at least one selected from yttrium or a rare earth element.
- the present invention can be realized in various aspects, and can be realized in aspects such as a spark plug, an internal combustion engine equipped with the spark plug, a spark plug manufacturing method, and the like.
- FIG. 1 is a schematic diagram showing the configuration of electrodes 20 and 30 of a spark plug 100.
- FIG. 3 is a schematic diagram of a graph used for calculating the thickness of a diffusion layer 34.
- FIG. It is the schematic which shows the structure of another embodiment of a ground electrode.
- FIG. 1 is a cross-sectional view of an example of the spark plug of the embodiment.
- the illustrated line CL indicates the central axis of the spark plug 100.
- the illustrated cross section is a cross section including the central axis CL.
- the central axis CL is also referred to as “axis line CL”
- the direction parallel to the central axis CL is also referred to as “axis line direction”.
- the radial direction of the circle centered on the central axis CL is also simply referred to as “radial direction”
- the circumferential direction of the circle centered on the central axis CL is also referred to as “circumferential direction”.
- the 1st direction D1 is a direction which goes to the electrodes 20 and 30 from the terminal metal fitting 40 mentioned later.
- the second direction D2 and the third direction D3 in the drawing are directions perpendicular to each other, and both are directions perpendicular to the first direction D1.
- the first direction D1 is also referred to as the front end direction D1
- the direction opposite to the first direction D1 is also referred to as the rear end direction D1r.
- 1 is referred to as the front end side of the spark plug 100
- the rear end direction D1r side in FIG. 1 is referred to as the rear end side of the spark plug 100. *
- the spark plug 100 includes an insulator 10 (hereinafter also referred to as “insulator 10”), a center electrode 20, a ground electrode 30, a terminal metal fitting 40, a metal shell 50, a conductive first seal portion 60, A resistor 70, a conductive second seal portion 80, a front end side packing 8, a talc 9, a first rear end side packing 6, and a second rear end side packing 7 are provided.
- insulator 10 insulator 10
- the insulator 10 is a substantially cylindrical member having a through hole 12 (hereinafter also referred to as “shaft hole 12”) extending along the central axis CL and penetrating the insulator 10.
- the insulator 10 is formed by firing alumina (other insulating materials can also be used).
- the insulator 10 includes a leg portion 13, a first reduced outer diameter portion 15, a distal end side body portion 17, a flange portion 19, and a second reduced outer diameter that are arranged in order from the front end side toward the rear end direction D1r. Part 11 and rear end side body part 18.
- the outer diameter of the first reduced outer diameter portion 15 gradually decreases from the rear end side toward the front end side.
- a reduced inner diameter portion 16 whose inner diameter gradually decreases from the rear end side toward the front end side is formed.
- the outer diameter of the second reduced outer diameter portion 11 gradually decreases from the front end side toward the rear end side.
- a rod-shaped center electrode 20 extending along the center axis CL is inserted on the distal end side of the shaft hole 12 of the insulator 10.
- the center electrode 20 includes a leg portion 25, a flange portion 24, and a head portion 23 that are arranged in order from the front end side toward the rear end direction D1r.
- a portion on the distal end side of the leg portion 25 is exposed outside the shaft hole 12 on the distal end side of the insulator 10.
- the other part of the center electrode 20 is disposed in the shaft hole 12.
- the surface of the flange portion 24 on the distal direction D1 side is supported by the reduced inner diameter portion 16 of the insulator 10.
- the center electrode 20 has an outer layer 21 and a core portion 22.
- the rear end portion of the core portion 22 is exposed from the outer layer 21 and forms the rear end portion of the center electrode 20.
- the other part of the core part 22 is covered with the outer layer 21. However, the entire core portion 22 may be covered with the outer layer 21.
- the outer layer 21 is formed using a material that has better corrosion resistance than the core 22, that is, a material that consumes less when exposed to combustion gas in the combustion chamber of the internal combustion engine.
- a material that has better corrosion resistance than the core 22 for example, nickel (Ni) or an alloy containing nickel as a main component (for example, Inconel ("INCONEL" is a registered trademark)) is used.
- the “main component” means a component having the highest content (hereinafter the same).
- As the content rate a value expressed in weight percent is adopted.
- the core portion 22 is formed of a material having a higher thermal conductivity than the outer layer 21, for example, a material containing copper (for example, copper or an alloy containing copper as a main component). *
- a terminal fitting 40 is inserted on the rear end side of the shaft hole 12 of the insulator 10.
- the terminal fitting 40 is formed using a conductive material (for example, a metal such as low carbon steel).
- the terminal fitting 40 includes a cap mounting portion 41, a flange portion 42, and a leg portion 43 that are arranged in order from the rear end side toward the distal end direction D1.
- the cap mounting portion 41 is exposed outside the shaft hole 12 on the rear end side of the insulator 10.
- the leg portion 43 is inserted into the shaft hole 12 of the insulator 10. *
- a columnar resistor 70 for suppressing electrical noise is disposed between the terminal fitting 40 and the center electrode 20.
- a conductive first seal portion 60 is disposed between the resistor 70 and the center electrode 20, and a conductive second seal portion 80 is disposed between the resistor 70 and the terminal fitting 40. .
- the center electrode 20 and the terminal fitting 40 are electrically connected through the resistor 70 and the seal portions 60 and 80.
- the resistor 70 includes, for example, glass particles (for example, B 2 O 3 —SiO 2 glass) as main components, ceramic particles (for example, TiO 2 ), and a conductive material (for example, Mg). , Are used.
- the seal portions 60 and 80 are formed using, for example, glass particles similar to the resistor 70 and metal particles (for example, Cu).
- the metal shell 50 is a substantially cylindrical member having a through hole 59 extending along the central axis CL and penetrating the metal shell 50.
- the metal shell 50 is formed using a low carbon steel material (other conductive materials (for example, metal materials) can also be used).
- the insulator 10 is inserted into the through hole 59 of the metal shell 50.
- the metal shell 50 is fixed to the outer periphery of the insulator 10.
- the distal end of the insulator 10 (in this embodiment, the portion on the distal end side of the leg portion 13) is exposed outside the through hole 59.
- the rear end of the insulator 10 (in this embodiment, the portion on the rear end side of the rear end side body portion 18) is exposed outside the through hole 59. *
- the metal shell 50 includes a body portion 55, a seat portion 54, a deformation portion 58, a tool engaging portion 51, and a caulking portion 53, which are arranged in order from the front end side to the rear end side.
- the seat part 54 is a bowl-shaped part.
- a screw portion 52 for screwing into a mounting hole of an internal combustion engine for example, a gasoline engine
- An annular gasket 5 formed by bending a metal plate is fitted between the seat portion 54 and the screw portion 52.
- the metal shell 50 has a reduced inner diameter portion 56 disposed on the distal direction D1 side with respect to the deformable portion 58.
- the inner diameter of the reduced inner diameter portion 56 gradually decreases from the rear end side toward the front end side.
- the front end packing 8 is sandwiched between the reduced inner diameter portion 56 of the metal shell 50 and the first reduced outer diameter portion 15 of the insulator 10.
- the front end side packing 8 is an iron O-ring (other materials (for example, metal materials such as copper) can also be used). *
- the shape of the tool engaging portion 51 is a shape (for example, a hexagonal column) with which the spark plug wrench is engaged.
- a caulking portion 53 is provided on the rear end side of the tool engaging portion 51.
- the caulking portion 53 is disposed on the rear end side of the second reduced outer diameter portion 11 of the insulator 10 and forms the rear end (that is, the end on the rear end direction D1r side) of the metal shell 50.
- the caulking portion 53 is bent toward the inner side in the radial direction. *
- an annular space SP is formed between the inner peripheral surface of the metal shell 50 and the outer peripheral surface of the insulator 10.
- the space SP is surrounded by the crimped portion 53 and the tool engaging portion 51 of the metal shell 50, and the second reduced outer diameter portion 11 and the rear end side body portion 18 of the insulator 10. It is space.
- a first rear end side packing 6 is disposed on the rear end side in the space SP.
- a second rear end side packing 7 is disposed on the front end side in the space SP.
- these rear end side packings 6 and 7 are iron C-rings (other materials are also employable).
- powder of talc (talc) 9 is filled. *
- the crimping portion 53 is crimped so as to be bent inward. And the crimping part 53 is pressed to the front end direction D1 side. Thereby, the deformation
- the front end side packing 8 is pressed between the first reduced outer diameter portion 15 and the reduced inner diameter portion 56 and seals between the metal shell 50 and the insulator 10. As a result, the gas in the combustion chamber of the internal combustion engine is prevented from leaking outside through the metal shell 50 and the insulator 10. In addition, the metal shell 50 is fixed to the insulator 10. *
- the ground electrode 30 is joined to the tip 501 of the metal shell 50 (that is, the end 501 on the tip direction D1 side).
- the ground electrode 30 is a rod-shaped electrode.
- the ground electrode 30 extends from the metal shell 50 in the distal end direction D1, bends toward the central axis CL, and reaches the distal end portion 38.
- the second direction D2 is a direction from the outer peripheral side toward the central axis CL along the ground electrode 30.
- the tip portion 38 forms a gap g with the tip surface 29 (surface 29 on the tip direction D1 side) of the center electrode 20.
- the ground electrode 30 is joined to the metal shell 50 so as to be electrically connected (for example, laser welding).
- the ground electrode 30 includes an outer layer 35 that forms part of the surface of the ground electrode 30, and a core portion 36 that includes an exposed surface 36 e that is a part of the outer layer 35 that is covered and exposed from the outer layer 35. Yes. Details of the configuration of the ground electrode 30 will be described later. *
- FIG. 2 is a schematic diagram showing the configuration of the electrodes 20 and 30 of the spark plug 100.
- FIG. 2A shows a cross-sectional view of a part of the spark plug 100 on the tip direction D1 side. Specifically, this cross section passes through the central axis CL and the bar-shaped central axis 30x of the ground electrode 30 (that is, the bar-shaped central axis 30x extending from the base end 31 toward the distal end portion 38). It is.
- FIG. 2B shows a schematic view of the distal end portion 38 of the ground electrode 30 as viewed from the rear end direction D1r side of the ground electrode 30 toward the distal end direction D1.
- 2C is a cross-sectional view perpendicular to the central axis 30x of the distal end portion 38 of the ground electrode 30 (specifically, a cross-sectional view taken along the line C2-C2 in FIG. 2A). Note that, on the right side of the center axis CL in FIG. 2A, the outer appearance of the center electrode 20, the insulator 10, and the metal shell 50 viewed in the third direction D3 is shown. *
- the ground electrode 30 is formed using a rod-shaped member having a substantially rectangular cross section. As shown in FIG. 2A, one end 31 (hereinafter referred to as “base end 31”) of the ground electrode 30 is joined to the distal end 501 of the metal shell 50. The ground electrode 30 extends from the base end 31 toward the distal end direction D1 and bends toward the central axis CL to reach the distal end portion 38. The distal end portion 38 faces the distal end surface 29 on the distal end direction D1 side of the distal end surface 29 of the center electrode 20 (that is, the surface on the distal end direction D1 side).
- the ground electrode 30 includes an outer layer 35 that forms part of the surface of the ground electrode 30, a core portion 36 that is partially covered by the outer layer 35, and an outer layer 35 and a core portion 36. And a diffusion layer 34 formed therebetween.
- the outer layer 35 is formed using a material containing nickel as a main component.
- the core part 36 is formed of a material having a higher thermal conductivity than the outer layer 35.
- the core part 36 is formed of a material containing nickel having a higher content than the content of the outer layer 35.
- the diffusion layer 34 is a layer formed by diffusing each component of the outer layer 35 and the core part 36.
- the core portion 36 extends from the proximal end 31 to the middle of the distal end portion 38.
- the outer layer 35 is omitted, and the core portion 36 is exposed.
- an exposed surface 36e that is an exposed portion of the surface of the core portion 36 is indicated by hatching.
- FIG. 2B shows a projection surface 29p obtained by projecting the tip surface 29 of the center electrode 20 in parallel with the center axis CL.
- the tip surface 29 is projected without changing its shape and size.
- the exposed surface 36e includes the entire projection surface 29p. That is, the exposed surface 36e of the core part 36 and the front end surface 29 of the center electrode 20 form a gap g.
- the outer layer 35 forms at least a portion of the surface of the ground electrode 30 opposite to the portion that forms the gap g, that is, a portion on the tip direction D1 side. *
- the reason why the core portion 36 is exposed in the portion of the surface of the ground electrode 30 that overlaps with the projection surface 29p, that is, the portion where discharge is likely to occur, is as follows. That is, since the ground electrode 30 is exposed to a cycle of gas compression and expansion and heating and cooling in the combustion chamber of the internal combustion engine, the surface of the ground electrode 30 is easily oxidized.
- the material of the ground electrode 30 by adopting a material having high durability against oxidation (for example, an alloy containing nickel and chromium as main components), the oxidation resistance of the ground electrode 30 can be improved. However, when such a material is used, durability against discharge (spark) may be low. *
- the portion where the discharge is likely to occur and the other portion of the surface of the ground electrode 30 are formed of different members. Specifically, a portion of the surface of the ground electrode 30 that overlaps the projection surface 29 p is formed by the exposed surface 36 e of the core portion 36. Accordingly, the occurrence of discharge at the portion other than the exposed surface 36e in the surface of the ground electrode 30 is suppressed.
- the material of the core portion 36 a material having high durability against discharge is adopted. For example, a material containing nickel whose content is higher than the content of nickel in the outer layer 35 can be used as the material of the core portion 36. When the nickel content is high, the high thermal conductivity of nickel can be maintained.
- the core part 36 easily releases heat generated by the discharge to the metal shell 50. As a result, durability against discharge can be improved.
- the other part of the surface of the ground electrode 30 is formed by the outer layer 35.
- a material having high durability against oxidation for example, an alloy of nickel and chromium
- the oxidation of the ground electrode 30 can be suppressed.
- a method of manufacturing such a ground electrode 30 can be adopted as a method of manufacturing such a ground electrode 30.
- the following method can be employed.
- a cup-shaped outer member formed of the material of the outer layer 35 is prepared, and the inner member formed of the material of the core portion 36 is inserted into the outer member.
- a rod-shaped member having an inner member and an outer member covering the inner member is formed by molding the outer shape of the outer member in a state where the inner member is inserted.
- the rod-shaped ground electrode before bending is formed by scraping the outer member of the portion that forms the gap g of the obtained rod-shaped member.
- the base electrode 31 of such a rod-shaped ground electrode is joined to the tip 501 of the metal shell 50 (for example, laser welding), and the ground electrode is bent so that an appropriate gap g is formed, whereby the ground electrode 30 is formed. Is done.
- the diffusion layer 34 can be formed in the process of forming the ground electrode 30 using the inner member and the outer member. For example, the outer member is pressed against the inner member by forming the outer shape of the outer member while the inner member is inserted. As a result, the diffusion layer 34 is formed.
- the rod-shaped ground electrode before bending may be annealed. By such heating of the ground electrode 30, the thick diffusion layer 34 can be formed. *
- FIG. 2 shows various dimensions Dg, 20D, 10P, 20P, 30H, 30W, 35T, and 36T of the spark plug 100.
- the distance Dg (FIG. 2A) is the distance of the gap g (hereinafter referred to as “gap distance Dg”).
- the gap distance Dg is the shortest distance between the two surfaces 29 and 36e forming the gap g.
- the tip diameter 20 ⁇ / b> D is the outer diameter of the tip surface 29 of the center electrode 20.
- the first protrusion length 10P is a length parallel to the central axis CL of the portion of the insulator 10 that protrudes from the tip 501 of the metal shell 50 toward the tip direction D1.
- the second protruding length 20P is a length parallel to the central axis CL of the portion of the center electrode 20 that protrudes from the tip 139 of the insulator 10 toward the tip direction D1.
- the height 30H (FIG. 2C) is the length in a direction parallel to the central axis CL of the substantially rectangular cross section of the ground electrode 30.
- the width 30 ⁇ / b> W is a length in a direction perpendicular to the central axis CL of the substantially rectangular cross section of the ground electrode 30.
- the outer layer thickness 35T is the thickness of the outer layer 35. When the thickness of the outer layer 35 changes according to the position on the outer layer 35, the minimum value of the thickness of the outer layer 35 is adopted as the outer layer thickness 35T.
- the core diameter 36T is the length of the core portion 36 in the radial direction (that is, the direction perpendicular to the central axis 30x).
- the maximum value of the length in the radial direction is adopted as the core diameter 36T. Further, when the length in the radial direction changes according to the position on the core portion 36, the maximum value of the length in the radial direction is adopted as the core diameter 36T.
- the outer layer 35 is formed of a material containing nickel (Ni) as a main component.
- Ni nickel
- a component other than nickel a component selected from chromium (Cr), aluminum (Al), and silicon (Si) is employed.
- the following method can be employed. First, after the outer layer 35 is dissolved with an acid, elements other than nickel are quantified by ICP emission spectroscopic analysis. The nickel content is calculated by subtracting the sum of the contents of elements other than nickel from 100%.
- the composition of other members (for example, the composition of the core portion 36) can be specified using the same method. *
- the aluminum content was 0.5, 1, 2 (wt%), an even better B evaluation was obtained. Therefore, it is preferable to employ a value selected from 0.5, 1, 2 (wt%) as the upper limit of the preferable range of the aluminum content.
- a value selected from 0.5, 1, 2 (wt%) as the upper limit of the preferable range of the aluminum content.
- a range of greater than zero wt% and 2 wt% or less can be employed.
- arbitrary values below the upper limit among said values are employable. For example, a range of 0.5 wt% or more may be employed. *
- the silicon content was 0.1, 0.5 (wt%), a better B evaluation was obtained. Therefore, it is preferable to adopt a value selected from 0.1 and 0.5 (wt%) as the upper limit of the preferable range of the silicon content.
- a preferable range of the silicon content a range of greater than zero wt% and 0.5 wt% or less can be employed.
- a minimum of the preferable range of the content rate of silicon arbitrary values below the minimum among said values are employable. For example, a range of 0.1 wt% or more may be employed.
- the aluminum content that yields an evaluation result equal to or higher than the B evaluation is 0.1, 1, 2, 3 (wt %)Met. Therefore, when the silicon content is in the range of 0.1 wt% or more and 0.5 wt% or less, any value among these values can be adopted as the upper limit of the preferable range of the aluminum content. .
- a preferable range of the aluminum content a range of greater than zero wt% and 3 wt% or less can be employed. Further, when the aluminum content was 0.1, 1, 2 (wt%), a better A evaluation was obtained.
- a value selected from 0.1, 1, 2 (wt%) as the upper limit of the preferable range of the aluminum content is preferable to employ.
- a range of the aluminum content a range of greater than zero wt% and 2 wt% or less can be employed.
- arbitrary values below the upper limit among said values are employable. For example, a range of 0.1 wt% or more may be employed.
- Evaluation results equal to or higher than B evaluation were obtained in each of the cases where the aluminum content was 0.1 wt% and 2 wt%.
- the silicon contents for which an evaluation result equal to or higher than the B evaluation was obtained were 0.1, 1, 2 (wt%). Therefore, when the aluminum content is in the range of 0.1 wt% or more and 2 wt% or less, any value of these values can be adopted as the upper limit of the preferable range of the silicon content.
- a preferable range of the silicon content a range greater than zero wt% and equal to or less than 2 wt% can be employed.
- arbitrary values below the upper limit among said values are employable. For example, a range of 0.1 wt% or more can be employed. *
- the nickel content of the core portion 36 is 96.9 wt%.
- the core portion 36 contains nickel having a higher content than the nickel content of the outer layer 35. Therefore, the durability against discharge can be improved as compared with the case where the nickel content of the core portion 36 is lower than that of the outer layer 35. Further, the thermal conductivity of the core portion 36 can be made higher than that of the outer layer 35.
- the chromium content (1 wt%) in the core portion 36 is less than the chromium content in the outer layer 35. . Therefore, compared with the case where the chromium content rate of the core part 36 is more than the chromium content rate of the outer layer 35, durability against discharge can be improved. Further, the thermal conductivity of the core portion 36 can be made higher than that of the outer layer 35.
- Second evaluation test A second evaluation test using a sample of the spark plug 100 will be described. In the second evaluation test, the amount of wear of the core portion 36 of the ground electrode 30 and the strength of the ground electrode 30 when the internal combustion engine was operated were evaluated. Table 2 below shows the sample number, the content (unit: weight percent) of the components (Ni, Cr, Al, Si, Y, Nd) contained in the core portion 36, and the evaluation results. Yes. The blank content indicates 0 wt%. *
- the core part 36 is formed of a material containing nickel (Ni) as a main component.
- Ni nickel
- a component selected from chromium (Cr), aluminum (Al), silicon (Si), yttrium (Y), and neodymium (Nd) is employed.
- Nominal diameter of screw part 52 M14 First protrusion length 10P: 3 mm Second protrusion length 20P: 3 mm Gap distance Dg: 1.1 mm Tip diameter 20D: 2.5 mm Height 30H: 1.6mm Width 30W: 2.8mm Composition of outer layer 35: nickel (84.5 wt%), chromium (14 wt%), aluminum (1 wt%), silicon (0.5 wt%)
- a 6-cylinder gasoline engine with a displacement of 2000 cc was used as the internal combustion engine.
- a sample of the spark plug 100 was mounted on an internal combustion engine, and the throttle was fully opened to operate at a rotational speed of 5000 rpm.
- the consumption amount of the ground electrode 30 was measured, and the presence or absence of deformation of the ground electrode 30 was confirmed.
- the consumption amount the difference in volume of the ground electrode 30 before and after the test was adopted.
- the volume of the ground electrode 30 was calculated using an X-ray CT scanner.
- the consumed part of the ground electrode 30 was mainly the core part 36.
- the A evaluation of the consumption amount indicates that the consumption amount by operation is less than 1.0 mm 3
- the B evaluation of the consumption amount indicates that the consumption amount by operation is 1.0 mm 3 or more.
- a strength A rating indicates that the ground electrode 30 was not deformed
- a strength B rating indicates that the ground electrode 30 was deformed.
- the presence or absence of deformation of the ground electrode 30 was confirmed by comparing the projections of the ground electrode 30 before and after operation.
- the projected view of the ground electrode 30 represents the same shape as the outer shape of the ground electrode 30 shown in FIG. 2A, and was obtained by projecting the ground electrode 30 in parallel with the third direction D3.
- the content rate of yttrium and neodymium from which A evaluation with comparatively favorable strength was obtained was 0.05, 0.1, 1, 2, 3, 4, 5, 6 (wt%). Therefore, any value among these values can be adopted as the lower limit of the preferable range of the content of yttrium and neodymium in the core portion 36. For example, a range of 0.05 wt% or more can be adopted as a preferable range of the content of yttrium and neodymium. In addition, any value above the lower limit of the above values can be adopted as the upper limit. For example, a range of 6 wt% or less can be adopted as a preferable range of the content of yttrium and neodymium. *
- rare earth elements have similar chemical properties. Therefore, a material containing at least one selected from yttrium and rare earth elements in addition to nickel as a main component can be adopted as the material of the core portion 36.
- rare earth elements include Nd, La, Ce, Dy, Er, Yb, Pr, Pm, Sm, Eu, Gd, Tb, Ho, Tm, and Lu.
- the content of the selected element the same range as the above-described preferable range of the content of yttrium and neodymium can be employed. When a plurality of elements are selected, it is preferable that the total value of their contents is in the above-described preferable range.
- the content rate of nickel with which A evaluation of comparatively favorable consumption was obtained is 96, 96.9, 96.95, 96.98, 97, 98, 99, 99.9, 99.95, 99. .98, 100 (wt%). Therefore, any value among these values can be adopted as the lower limit of the preferable range of the nickel content of the core 36.
- a range of 96 wt% or more can be adopted as a preferable range of the nickel content.
- a value of 4 wt% or less can be adopted as the content of at least one selected from yttrium and rare earth elements.
- the nickel content of the core portion 36 is preferably larger than the nickel content of the outer layer 35.
- any value above the lower limit of the above values can be adopted as the upper limit.
- a range of 100 wt% or less can be employed.
- the chromium content of the core portion 36 of samples (that is, all samples) for which A evaluation was obtained at least one of the consumption amount and the strength was 0, 0.5, 1, 1.5, 2 ( wt%). Therefore, any value among these values can be adopted as the upper limit of the preferable range of the chromium content in the core portion 36. For example, a range of 2 wt% or less can be adopted as a preferable range of the chromium content. Moreover, any value below the upper limit among the above values can be adopted as the lower limit. For example, a range of zero wt% or more can be adopted. Further, the chromium content in the outer layer 35 of each sample was 14 wt%. Thus, since the chromium content of the core portion 36 is smaller than the chromium content of the outer layer 35, the durability of the core portion 36 against discharge can be improved while improving the durability of the outer layer 35 against oxidation. *
- FIG. 3 is a schematic diagram of a graph used for calculating the thickness of the diffusion layer 34.
- the horizontal axis indicates a position P on an analysis line to be described later, and the vertical axis indicates the intensity I of the characteristic X-ray of chromium.
- FIG. 2A shows an example of the analysis line AL.
- the analysis line AL is a straight line from the outer layer 35 to the core portion 36 through the diffusion layer 34 on the cross section of the ground electrode 30. Specifically, a straight line orthogonal to the boundary on the cross section orthogonal to the boundary between the outer layer 35 and the core portion 36 (that is, the diffusion layer 34) is employed as the analysis line AL.
- the left portion indicates the core portion 36 and the right portion indicates the outer layer 35. *
- the ground electrode 30 of the sample of the spark plug 100 was cut in a cross section passing through the central axis CL of the spark plug 100 and the central axis 30x of the ground electrode 30. Then, along the analysis line AL on the cross section, the line analysis profile of the intensity distribution of the characteristic X-rays of chromium was measured by electron beam microanalysis (EPMA).
- EPMA electron beam microanalysis
- SEM / EDS scanning electron microscope / energy dispersive X-ray analyzer
- JSM-6490LA manufactured by JEOL Ltd.
- the acceleration voltage was set to 20 kV
- the magnification was set to 1500 times.
- FIG. 3 indicates the intensity of the measured characteristic X-ray.
- a large strength I indicates that the chromium content is high.
- a graph G shown in FIG. 3 shows a correspondence relationship between the intensity I and the position P represented by the measured line analysis profile (hereinafter, this graph G is referred to as “chrome distribution G”).
- chrome distribution G In order to reduce the influence of noise, it is preferable to remove a minute intensity fluctuation component having a wavelength of less than 1 ⁇ m by filtering.
- the average of the intensity I in the outer layer 35 is calculated as the first intensity I1
- the average of the intensity I in the core portion 36 is calculated as the second intensity I2.
- the chromium content in the core 36 is less than the chromium content in the outer layer 35.
- the second intensity I2 is smaller than the first intensity I1.
- the strength I increases from the second strength I 2 to the first strength I 1 from the core portion 36 toward the outer layer 35.
- the layer in which the chromium content varies from the content of the core portion 36 to the content of the outer layer 35 corresponds to the diffusion layer 34.
- a difference dI in FIG. 3 is a difference between the first intensity I1 and the second intensity I2.
- two threshold values Iu and Id of intensity I were calculated according to the following arithmetic expression.
- First threshold Iu first intensity I1-0.01 * difference dI
- second threshold Id second intensity I2 + 0.01 * difference dI (the symbol “*” is a multiplication symbol) and a straight line LIu representing the first threshold Iu
- the distance T between the first position P1 represented by the intersection of the chrome distribution G and the second position P2 represented by the intersection of the straight line LId representing the second threshold value Id and the chrome distribution G is diffused. This was calculated as the thickness T of the layer 34.
- the thickness T of the diffusion layer 34 the thickness of the layer in which the chromium content changes greatly is calculated. *
- composition configurations Samples of 7 different configurations (hereinafter referred to as “composition configurations”) with “A-37” were tested.
- composition configurations Eight kinds of different thickness samples having different thicknesses T of the diffusion layers 34 were manufactured.
- the ground electrode 30 was heated to diffuse chromium from the outer layer 35 to the core portion 36.
- the thickness T was adjusted by adjusting the diffusion processing time (the longer the diffusion processing time, the larger the thickness T).
- the other configurations were the same except that the thickness T of the diffusion layer 34 was different. *
- thickness T with which favorable A evaluation was obtained was 5, 10, 15, 20, 25, 30 ( ⁇ m). Therefore, any value among these values can be adopted as the lower limit of the preferable range of the thickness T of the diffusion layer 34.
- a preferable range of the thickness T of the diffusion layer 34 is a range of 5 ⁇ m or more.
- any value above the lower limit of the above values can be adopted as the upper limit.
- a range of 30 ⁇ m or less can be adopted as a preferable range of the thickness T of the diffusion layer 34.
- the chromium content rate of the core part 36 is less than the chromium content rate of the outer layer 35. . Therefore, the durability of the core portion 36 against discharge and the durability of the outer layer 35 against oxidation can be improved.
- the evaluation results in Table 3 were common to the seven types of composition configurations.
- the seven types of compositional configurations include a configuration that does not include aluminum and silicon (No. A-10), a configuration that includes aluminum but does not include silicon (No. A-15), and includes aluminum.
- the structure including silicon (A-21) and the structure including both aluminum and silicon (A-26, A-31, A-35, A-37) are included.
- 0, 0.1, 0.5, and 2 (wt%) were evaluated as the aluminum content.
- 0, 0.1, 0.5, and 1 (wt%) were evaluated as the silicon content.
- the preferable range of the thickness T of the diffusion layer 34 can be applied to various compositions of the outer layer 35. As a result, it is estimated that it can apply also to the other composition structure different from seven types of composition structures. *
- FIG. 4 is a schematic view showing the configuration of another embodiment of the ground electrode.
- 4A is a cross section including the central axis CL of the spark plug 100b and the central axis 30xb of the rod-shaped ground electrode 30b extending from the base end 31b to the tip end portion 38b, as in FIG. 2A. is there.
- FIG. 4B is a schematic view of the ground electrode 30b as seen from the rear end direction D1r side of the ground electrode 30b toward the front end direction D1, similarly to FIG. 2B.
- the configuration other than the ground electrode 30b is the same as the configuration of the spark plug 100 shown in FIGS.
- the elements of the spark plug 100b the same elements as those of the spark plug 100 are denoted by the same reference numerals and description thereof is omitted. *
- the ground electrode 30b includes an outer layer 35b, a core portion 36b, and a diffusion layer 34b.
- the difference from the ground electrode 30 of the first embodiment shown in FIG. 2 is that the exposed surface 36eb of the core portion 36b faces the front end surface 29 of the center electrode 20 on the center electrode 20 side of the surface of the ground electrode 30b.
- This is a point extending from the portion (that is, the portion including the projection surface 29p) to the virtual plane 13p.
- the virtual plane 13p is a plane perpendicular to the central axis CL including the tip 139 of the insulator 10. That is, the exposed surface 36eb of the core portion 36 includes a surface that continues from the portion facing the tip surface 29 of the center electrode 20 to the virtual plane 13p and faces the center electrode 20.
- the ground electrode 30b can be adopted as a method of manufacturing the ground electrode 30b.
- a rod-shaped member having an inner member and an outer member covering the inner member is formed.
- the bar-shaped ground electrode before bending is formed by scraping the outer member of the portion corresponding to the exposed surface 36eb of the obtained bar-shaped member.
- the ground electrode 30b is formed by joining the base end 31b of such a rod-shaped ground electrode to the tip 501 of the metal shell 50 (for example, laser welding) and bending the ground electrode so that an appropriate gap g is formed. To do. *
- the above-mentioned preferable range is applicable as each of the composition of the outer layer 35b, the composition of the core part 36b, and the thickness T of the diffusion layer 34b.
- the configuration of the spark plug is not limited to the configuration described in FIGS. 1, 2, and 4, and various configurations can be employed.
- a part of the projection surface 29p of the tip surface 29 of the center electrode 20 may overlap with the outer layer of the ground electrode.
- a part of the projection surface 29p may protrude beyond the ground electrode without overlapping the ground electrode.
- a noble metal tip may be provided in a portion of the center electrode 20 where the gap g is formed.
- materials containing various noble metals such as platinum (Pt), iridium (Ir), rhodium (Rh), ruthenium (Ru), palladium (Pd), gold (Au) as main components can be adopted. It is. In this case, the tip surface of the noble metal tip is adopted as the tip surface of the center electrode.
- the size of the core portion is large and the thickness of the outer layer is thin.
- the thickness of the outer layer (for example, the outer layer thickness 35T in FIG. 2) is preferably smaller than half the length of the core portion in the radial direction (for example, the core diameter 36T in FIG. 2).
- the thickness of the outer layer is smaller than a value of 1/8 of the length of the core portion in the radial direction.
- the thickness of the outer layer is preferably 0.5 mm or less, which is the thickness of the sample of the first evaluation test.
- leg part 29 ... tip surface, 29p ... projection surface, 30, 30b ... ground electrode, 30W ... width, 30x, 30xb ... central axis, 31, 31b ... proximal end, 34, 34b ... diffusion layer, 35, 35b ... outer layer, 36, 36b ... core, 36T ... core diameter, 36e, 36eb ... exposed surface, 38, 38b ... tip 40 ... terminal fitting, 41 ... cap mounting part, 42 ... collar part, 43 ... leg part, 50 ... metallic shell, 51 ... tool engaging part, 52 ... screw Part, 53 ... caulking part, 54 ... seat part, 55 ... trunk part, 56 ... reduced inner diameter part, 58 ... deformation part, 59 ...
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Abstract
Description
前記中心電極の先端面との間でギャップを形成する接地電極と、
を有するスパークプラグであって、
前記接地電極は、
前記接地電極の表面の一部を形成する外層と、
前記外層に一部が被覆され前記外層よりも熱伝導率が高い材料で形成され、前記外層から露出した部分である露出面を備える芯部と、
を有し、
前記外層は、主成分としてのニッケルと、14wt%以上のクロムと、を含む材料で形成されており、
前記芯部は、前記外層のニッケルの含有率よりも高い含有率のニッケルを含む材料で形成されており、
前記中心電極の前記先端面を前記軸線方向と平行に投影した場合に、前記露出面は、前記接地電極のうちの前記投影された前記先端面と重なる部分を、含む、
スパークプラグ。
前記露出面は、前記投影された前記先端面の全体と、重なる、
スパークプラグ。
前記軸線方向に延びる軸孔が形成され、前記軸孔の先端側に前記中心電極が配置される絶縁体を有し、
前記露出面は、前記絶縁体の先端を含む前記軸線方向に垂直な仮想平面まで続くとともに前記中心電極と対向する面を、含む、
スパークプラグ。
前記芯部のクロムの含有率は、ゼロ、または、前記外層のクロムの含有率未満であり、
前記接地電極は、前記芯部と前記外層との間に形成された拡散層を有し、
前記拡散層の厚さは、5μm以上である、
スパークプラグ。
前記芯部は、ニッケルを96wt%以上、イットリウムまたは希土類元素から選ばれる少なくとも1種を0.05wt%以上含む、スパークプラグ。
前記外層は、0wt%より大きく、かつ、2wt%以下のアルミニウムを含む、スパークプラグ。
前記外層は、0wt%より大きく、かつ、0.5wt%以下のシリコンを含む、スパークプラグ。
第1突出長10P :3mm
第2突出長20P :3mm
ギャップ距離Dg :1.1mm
先端径20D :2.5mm
高さ30H :1.6mm
幅30W :2.8mm
外層厚さ35T :0.5mm
芯部36の組成 :ニッケル(96.9wt%)、クロム(1wt%)、アルミニウム(2wt%)、イットリウム(0.1wt%)
ネジ部52の呼び径 :M14
第1突出長10P :3mm
第2突出長20P :3mm
ギャップ距離Dg :1.1mm
先端径20D :2.5mm
高さ30H :1.6mm
幅30W :2.8mm
外層35の組成 :ニッケル(84.5wt%)、クロム(14wt%)、アルミニウム(1wt%)、シリコン(0.5wt%)
Claims (7)
- 軸線方向に延びる中心電極と、
前記中心電極の先端面との間でギャップを形成する接地電極と、
を有するスパークプラグであって、
前記接地電極は、
前記接地電極の表面の一部を形成する外層と、
前記外層に一部が被覆され前記外層よりも熱伝導率が高い材料で形成され、前記外層から露出した部分である露出面を備える芯部と、
を有し、
前記外層は、主成分としてのニッケルと、14wt%以上のクロムと、を含む材料で形成されており、
前記芯部は、前記外層のニッケルの含有率よりも高い含有率のニッケルを含む材料で形成されており、
前記中心電極の前記先端面を前記軸線方向と平行に投影した場合に、前記露出面は、前記接地電極のうちの前記投影された前記先端面と重なる部分を、含む、
スパークプラグ。 - 請求項1に記載のスパークプラグであって、
前記露出面は、前記投影された前記先端面の全体と、重なる、
スパークプラグ。 - 請求項1または2に記載のスパークプラグであって、
前記軸線方向に延びる軸孔が形成され、前記軸孔の先端側に前記中心電極が配置される絶縁体を有し、
前記露出面は、前記絶縁体の先端を含む前記軸線方向に垂直な仮想平面まで続くとともに前記中心電極と対向する面を、含む、
スパークプラグ。 - 請求項1から3のいずれか1項に記載のスパークプラグであって、
前記芯部のクロムの含有率は、ゼロ、または、前記外層のクロムの含有率未満であり、
前記接地電極は、前記芯部と前記外層との間に形成された拡散層を有し、
前記拡散層の厚さは、5μm以上である、
スパークプラグ。 - 請求項1から4のいずれか1項に記載のスパークプラグであって、
前記芯部は、ニッケルを96wt%以上、イットリウムまたは希土類元素から選ばれる少なくとも1種を0.05wt%以上含む、スパークプラグ。 - 請求項1から5のいずれか1項に記載のスパークプラグであって、
前記外層は、0wt%より大きく、かつ、2wt%以下のアルミニウムを含む、スパークプラグ。 - 請求項1から6のいずれか1項に記載のスパークプラグであって、
前記外層は、0wt%より大きく、かつ、0.5wt%以下のシリコンを含む、スパークプラグ。
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WO2018211752A1 (ja) * | 2017-05-19 | 2018-11-22 | 住友電気工業株式会社 | 電極材料、点火プラグ用電極、及び点火プラグ |
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JP6280899B2 (ja) * | 2015-08-31 | 2018-02-14 | 日本特殊陶業株式会社 | スパークプラグ |
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JPH03208281A (ja) * | 1990-01-08 | 1991-09-11 | Ngk Spark Plug Co Ltd | 内燃機関のスパークプラグ |
JPH11111426A (ja) * | 1997-10-02 | 1999-04-23 | Denso Corp | スパークプラグおよびその製造方法 |
JP2007165291A (ja) * | 2005-11-16 | 2007-06-28 | Ngk Spark Plug Co Ltd | 内燃機関用スパークプラグ |
JP2007265842A (ja) * | 2006-03-29 | 2007-10-11 | Ngk Spark Plug Co Ltd | 内燃機関用スパークプラグ |
-
2013
- 2013-12-17 JP JP2013260278A patent/JP5901605B2/ja active Active
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH03208281A (ja) * | 1990-01-08 | 1991-09-11 | Ngk Spark Plug Co Ltd | 内燃機関のスパークプラグ |
JPH11111426A (ja) * | 1997-10-02 | 1999-04-23 | Denso Corp | スパークプラグおよびその製造方法 |
JP2007165291A (ja) * | 2005-11-16 | 2007-06-28 | Ngk Spark Plug Co Ltd | 内燃機関用スパークプラグ |
JP2007265842A (ja) * | 2006-03-29 | 2007-10-11 | Ngk Spark Plug Co Ltd | 内燃機関用スパークプラグ |
Cited By (5)
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WO2018211752A1 (ja) * | 2017-05-19 | 2018-11-22 | 住友電気工業株式会社 | 電極材料、点火プラグ用電極、及び点火プラグ |
CN110651055A (zh) * | 2017-05-19 | 2020-01-03 | 住友电气工业株式会社 | 电极材料、火花塞用电极以及火花塞 |
JPWO2018211752A1 (ja) * | 2017-05-19 | 2020-03-26 | 住友電気工業株式会社 | 電極材料、点火プラグ用電極、及び点火プラグ |
US11196235B2 (en) | 2017-05-19 | 2021-12-07 | Sumitomo Electric Industries, Ltd. | Electrode material spark plug electrode, and spark plug |
JP7140112B2 (ja) | 2017-05-19 | 2022-09-21 | 住友電気工業株式会社 | 電極材料、点火プラグ用電極、及び点火プラグ |
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