WO2013076887A1 - スパークプラグ - Google Patents

スパークプラグ Download PDF

Info

Publication number
WO2013076887A1
WO2013076887A1 PCT/JP2012/004908 JP2012004908W WO2013076887A1 WO 2013076887 A1 WO2013076887 A1 WO 2013076887A1 JP 2012004908 W JP2012004908 W JP 2012004908W WO 2013076887 A1 WO2013076887 A1 WO 2013076887A1
Authority
WO
WIPO (PCT)
Prior art keywords
ground electrode
center
electrode
spark plug
tip
Prior art date
Application number
PCT/JP2012/004908
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
かおり 鈴木
加藤　友聡
Original Assignee
日本特殊陶業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本特殊陶業株式会社 filed Critical 日本特殊陶業株式会社
Priority to CN201280057910.2A priority Critical patent/CN103947059B/zh
Publication of WO2013076887A1 publication Critical patent/WO2013076887A1/ja

Links

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
    • H01T21/06—Adjustment of spark gaps
    • 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 used for an internal combustion engine or the like.
  • a spark plug is attached to an internal combustion engine (engine) or the like, and is used to ignite an air-fuel mixture in a combustion chamber.
  • a spark plug is composed of an insulator having an axial hole extending in the axial direction, a center electrode inserted through the distal end side of the axial hole, a metal shell provided on the outer periphery of the insulator, and a tip of the metal shell.
  • a fixed ground electrode The ground electrode is bent back so that the tip of the ground electrode is opposed to the center electrode at a bent portion provided at a substantially intermediate portion of the ground electrode, and a spark discharge is generated between the tip of the ground electrode and the tip of the center electrode.
  • a gap is formed. A high voltage is applied to the spark discharge gap and spark discharge is generated, whereby the air-fuel mixture is ignited.
  • the distance from the spark discharge gap to the ground electrode along the direction orthogonal to the axis is relatively small. Therefore, the growth of flame nuclei generated in the spark discharge gap is likely to be hindered by the ground electrode as compared with the case where the distance is large. Further, when the ground electrode is disposed between the spark discharge gap and the combustion injection device in the case where the distance is relatively small, the spark discharge gap due to the presence of the ground electrode is compared with the case where the distance is large. Inflow inhibition of the air-fuel mixture will be more noticeable. That is, in a spark plug with a relatively small screw diameter and a reduced diameter, there is a greater concern about the decrease in ignitability. *
  • ground electrode thinner, it is possible to facilitate the growth of flame nuclei and to facilitate the flow of air-fuel mixture into the spark discharge gap, thereby realizing high ignitability in a spark plug with a reduced diameter. It is done.
  • the ground electrode is simply made thin, when the vibration associated with the operation of the internal combustion engine or the like is applied, the tip of the ground electrode rises away from the center electrode (the bent ground electrode is Gradually returning and deforming). This is because the internal stress remains in the ground electrode with bending, and the thin ground electrode is not strong enough against the internal stress. If the ground electrode rises, the spark discharge gap increases, and the discharge voltage increases, which may lead to a situation where the center electrode and the ground electrode are rapidly consumed or cannot be discharged. *
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to more reliably prevent rising at the tip of the ground electrode while realizing high ignitability in a spark plug having a reduced diameter. is there.
  • the spark plug of this configuration includes a cylindrical insulator having an axial hole extending in the axial direction, a center electrode inserted in the axial hole, a cylindrical metal shell provided on the outer periphery of the insulator, The base end of its own is fixed to the metal shell, and is bent toward the center electrode at the bent portion, and the tip of its own includes a ground electrode that forms a gap with the center electrode, A thread portion for mounting is formed on the outer periphery of the front end side of the metal shell, and the spark plug has a thread diameter of M10 or less, and the axis line at the base end portion of the ground electrode In an orthogonal cross section, the angle of the corner located on the ground electrode side among the corners formed by two tangent lines drawn from the axis to the outline of the ground electrode is 30 ° or less, Closest to the tip of the ground electrode In the cross section orthogonal to the central axis of the ground electrode at the site where the ground electrode is located, the center of gravity of the ground electrode is
  • the “thickness of the ground electrode” means the maximum thickness of the ground electrode in the cross section.
  • the spark plug of this configuration is the same as the configuration 1 described above, wherein the center of gravity of the ground electrode is 1 ⁇ 2 of the thickness of the ground electrode in a cross section orthogonal to the central axis of the ground electrode at an arbitrary portion of the bent portion.
  • the distance between the center of the ground electrode in the thickness direction and the center of gravity of the ground electrode is greater than the position of the ground electrode.
  • the thickness is 4% or more.
  • the spark plug of this configuration has the above-described cross-section in which the hardness of a portion of the ground electrode located closer to the center electrode than the center of gravity is greater than the center of the ground electrode than the center of gravity. It is characterized by being larger than the hardness of the part located on the opposite side to the electrode.
  • the gap is formed between a surface of the ground electrode on the side of the center electrode and a front end surface of the center electrode.
  • the two contacts are located between the two contacts.
  • the outline line located on the opposite side of the center electrode is formed by a plurality of line segments, a curved line that protrudes toward the side away from the center of gravity of the ground electrode, or one or more line segments and the curved line
  • the outer shape located between the two contacts and located on the side of the center electrode is A (mm), and the outer shape is located between the contacts and located on the opposite side of the center electrode.
  • the gap is formed between a surface of the ground electrode on the side of the center electrode and a tip surface of the center electrode, and the ground electrode Of the ground electrode from the center of the outline of the front end surface of the center electrode in a cross section orthogonal to the center axis of the ground electrode within a range along the central axis direction of the ground electrode corresponding to the portion forming the gap.
  • the length of the outer shape line located between the two contact points and located on the center electrode side is: It is 1.35 mm or more.
  • the gap is formed between a surface of the ground electrode on the side of the center electrode and a tip surface of the center electrode, and the axial direction When viewed from the distal end side, the distal end of the ground electrode is positioned closer to the proximal end side of the ground electrode than a portion of the distal end surface of the center electrode farthest from the proximal end portion of the ground electrode.
  • the spark plug of this configuration is characterized in that, in any of the above configurations 1 to 6, the ground electrode is formed of a metal containing 95 mass% or more of nickel.
  • the spark plug of configuration 1 in the cross section orthogonal to the axis at the base end portion of the ground electrode, it is located on the ground electrode side of the corner formed by the two tangent lines drawn from the axis to the outline of the ground electrode.
  • the angle of the angle is set to 30 ° or less. That is, the ground electrode is sufficiently thin (small in width), and the ground electrode can more reliably prevent the inhibition of the growth of the flame kernel and the inflow of the air-fuel mixture to the gap.
  • the spark diameter of the threaded portion is set to M10 or less, and an excellent ignitability can be realized in a spark plug in which the ignitability is further deteriorated. *
  • the tip of the ground electrode rises.
  • the internal stress remains in the ground electrode due to the bending, but two types of internal stress are considered to remain mainly in the ground electrode. That is, the central electrode side (bent inner side) portion of the bent portion of the ground electrode is a portion compressed along with the bending, and therefore the compressed inner portion is released in the direction (extending direction) to release the compressed state. Internal stress remains.
  • the portion of the bent portion on the side opposite to the center electrode (outside of the bend) is a portion that has been stretched along with the bend. (Tensile stress) remains.
  • the center of gravity of the ground electrode is 1 / th of the thickness of the ground electrode in a cross section orthogonal to the central axis of the ground electrode in a portion of the bent portion that is closest to the tip of the ground electrode.
  • the distance between the center of the ground electrode and the center of gravity along the thickness direction of the ground electrode is located closer to the surface side (bent inside) of the ground electrode than the position 2 and the thickness of the ground electrode. 4% or more. That is, the cross-sectional area of the portion of the bent portion that is closest to the tip of the ground electrode is located sufficiently outside the center of the bent portion.
  • the center of gravity of the ground electrode is located on the inner side of the bend than the position of 1 ⁇ 2 of the thickness of the ground electrode in the entire bent portion, and between the center and the center of gravity.
  • the distance along the thickness direction of the ground electrode is 4% or more of the thickness of the ground electrode. Therefore, the cross-sectional area of the portion of the ground electrode located on the outer side of the bend can be reduced over the entire bent portion, and the tensile stress remaining on the ground electrode can be further reduced. As a result, it is possible to more effectively prevent the rising of the tip of the ground electrode.
  • the hardness of a portion of the ground electrode that is located closer to the center electrode (bent inside) than the center of gravity is the opposite side of the ground electrode from the center electrode (outside of the bend). It is made larger than the hardness of the part located in. Therefore, it is possible to improve the strength of the portion of the ground electrode located on the bent inner side while suppressing an increase in the tensile stress remaining on the bent electrode outer side (that is, the strength improvement can be achieved by increasing the hardness). Can be greater than the increase in stress). As a result, the strength of the ground electrode against internal stress can be improved, and the rising of the ground electrode can be more effectively prevented. *
  • the spark plug of Configuration 4 even when the spark plug is attached in a state where the ground electrode exists between the gap and the fuel injection device, the air-fuel mixture is peeled off on the side surface of the ground electrode. Therefore, the air-fuel mixture flowing from the ground electrode toward the gap can smoothly flow into the gap. As a result, the ignitability can be further improved.
  • the width of the surface (discharge surface) corresponding to the gap in the ground electrode is sufficiently large. Therefore, the gap is more difficult to expand compared to the case where the discharge surface has a small width (when it is assumed that the consumption amount of the ground electrode is the same for both the large discharge surface and the small discharge surface) In addition, the gap is less likely to expand when the width of the discharge surface is large). Further, since it becomes difficult to enlarge the gap, it is possible to suppress an increase in the discharge voltage accompanying the enlargement of the gap, and it is possible to further suppress the consumption of the electrode (expansion of the gap). As a result, durability can be further improved. *
  • the ground electrode is formed of a metal containing 95% by mass or more of nickel (Ni) having excellent thermal conductivity. Therefore, the wear resistance of the ground electrode can be improved, and the durability can be further improved.
  • (A) is an expanded sectional view which shows the shape of the ground electrode in another embodiment. It is an expanded sectional view which shows the shape of the ground electrode in another embodiment. It is an expanded sectional view which shows the shape of the ground electrode in another embodiment.
  • FIG. 1 is a partially cutaway front view showing a spark plug 1.
  • the direction of the axis CL ⁇ b> 1 of the spark plug 1 is the vertical direction in the drawing, the lower side is the front end side of the spark plug 1, and the upper side is the rear end side. *
  • the spark plug 1 includes an insulator 2 as a cylindrical insulator, a cylindrical metal shell 3 that holds the insulator 2, and the like. *
  • the insulator 2 is formed by firing alumina or the like, and in its outer portion, a rear end side body portion 10 formed on the rear end side, and a front end than the rear end side body portion 10.
  • a large-diameter portion 11 that protrudes radially outward on the side, a middle body portion 12 that is smaller in diameter than the large-diameter portion 11, and a tip portion that is more distal than the middle body portion 12.
  • the leg length part 13 formed in diameter smaller than this on the side is provided.
  • the large diameter portion 11, the middle trunk portion 12, and most of the leg long portions 13 are accommodated inside the metal shell 3.
  • a tapered step portion 14 is formed at the connecting portion between the middle body portion 12 and the long leg portion 13, and the insulator 2 is locked to the metal shell 3 at the step portion 14.
  • the insulator 2 is formed with a shaft hole 4 extending along the axis CL ⁇ b> 1, and a center electrode 5 is inserted and fixed to the tip side of the shaft hole 4.
  • the center electrode 5 includes an inner layer 5A made of a metal having excellent thermal conductivity [for example, copper, copper alloy, pure nickel (Ni), etc.] and an outer layer 5B made of an alloy containing Ni as a main component.
  • the center electrode 5 has a rod shape (cylindrical shape) as a whole, and a tip portion of the center electrode 5 projects from the tip of the insulator 2. *
  • a terminal electrode 6 is inserted and fixed on the rear end side of the shaft hole 4 in a state of protruding from the rear end of the insulator 2.
  • a cylindrical resistor 7 is disposed between the center electrode 5 and the terminal electrode 6 of the shaft hole 4. Both ends of the resistor 7 are electrically connected to the center electrode 5 and the terminal electrode 6 through conductive glass seal layers 8 and 9, respectively.
  • the metal shell 3 is formed in a cylindrical shape from a metal such as low carbon steel, and the spark plug 1 is attached to a combustion apparatus such as an internal combustion engine or a fuel cell reformer on the outer periphery of the tip end portion.
  • a threaded portion (male threaded portion) 15 is formed.
  • a seat portion 16 is formed on the rear end side of the screw portion 15 so as to protrude toward the outer peripheral side, and a ring-shaped gasket 18 is fitted into the screw neck 17 at the rear end of the screw portion 15.
  • a tool engaging portion 19 having a hexagonal cross section for engaging a tool such as a wrench when the metal shell 3 is attached to the combustion device is provided on the rear end side of the metal shell 3.
  • a caulking portion 20 that bends inward in the radial direction is provided at the rear end portion of the metal shell 3.
  • the metal shell 3 is reduced in diameter, and the screw diameter of the screw portion 15 is set to M10 or less.
  • a tapered step portion 21 for locking the insulator 2 is provided on the inner peripheral surface of the metal shell 3.
  • the insulator 2 is inserted from the rear end side to the front end side of the metal shell 3, and the step 14 of the metal shell 3 is locked to the step 21 of the metal shell 3. It is fixed to the metal shell 3 by caulking the opening on the rear end side in the radial direction, that is, by forming the caulking portion 20.
  • An annular plate packing 22 is interposed between the stepped portions 14 and 21. Thereby, the airtightness in the combustion chamber is maintained, and the fuel gas entering the gap between the leg long portion 13 of the insulator 2 exposed to the combustion chamber and the inner peripheral surface of the metal shell 3 is prevented from leaking outside.
  • annular ring members 23 and 24 are interposed between the metal shell 3 and the insulator 2 on the rear end side of the metal shell 3, and the ring member 23 , 24 is filled with talc 25 powder. That is, the metal shell 3 holds the insulator 2 via the plate packing 22, the ring members 23 and 24, and the talc 25.
  • the ground electrode 27 is bent at the distal end portion 26 of the metal shell 3 toward the center electrode 5 by a bent portion 27 ⁇ / b> B and the side surface of the distal end portion faces the distal end portion of the center electrode 5.
  • a spark discharge gap 28 is formed as a gap between the tip surface of the center electrode 5 and the surface 27S of the ground electrode 27 on the side of the center electrode 5, and the spark discharge gap 28 has an axis CL1. Spark discharge is performed in a direction substantially along.
  • the spark discharge gap 28 has a larger distance than the large distance.
  • the growth of flame nuclei generated in this way is likely to be inhibited by the ground electrode 27.
  • the spark due to the presence of the ground electrode 27 is larger than that of the large distance. Inhibition of the inflow of the air-fuel mixture to the discharge gap 28 tends to occur more remarkably.
  • the ground electrode 27 is made relatively thin in order to prevent a decrease in ignitability, and as shown in FIG. 3 (the insulator 2 and the like are not shown in FIG. 3).
  • the insulator 2 and the like are not shown in FIG. 3.
  • the angle ⁇ is 30 ° or less.
  • the angle ⁇ is set to 30 ° or less, the ignitability can be prevented from being lowered, but the strength against the internal stress remaining in the ground electrode 27 tends to be insufficient due to the bending. For this reason, the ground electrode 27 gradually returns and deforms due to the internal stress due to the vibration during the operation of the internal combustion engine or the like (the tip of the ground electrode 27 moves away from the tip of the center electrode 5). There is a risk of getting up).
  • the bent portion 27B is orthogonal to the central axis CL2 at a portion closest to the tip of the ground electrode 27.
  • the center of gravity GP of the ground electrode 27 is located closer to the surface 27S side of the ground electrode 27 than the position of half the thickness of the ground electrode 27 (center CP of the ground electrode 27).
  • a distance X along the thickness direction between the center CP of the ground electrode 27 and the center of gravity GP along the thickness direction of the ground electrode 27 (the direction of the straight line L1 orthogonal to the surface 27S in FIG. 4) is obtained.
  • the thickness is 4% or more of the thickness T of the ground electrode 27. *
  • the center of gravity GP is set to 1 ⁇ 2 of the thickness of the ground electrode 27 in a cross section orthogonal to the central axis CL2 at an arbitrary portion of the bent portion 27B. More preferably, the distance X is 4% or more of the thickness T, and the distance X is positioned closer to the surface 27S than the position (center CP). That is, it is more preferable that the center of gravity GP is located closer to the surface 27S than the center CP in the entire bent portion 27B, and the distance X is 4% or more of the thickness T.
  • the center of gravity GP is positioned closer to the surface 27S than the center CP, and the distance X is set to 4% or more of the thickness T, in a cross section orthogonal to the center axis CL2.
  • the surface 27S is a flat surface, and the other surface is a convex curved surface toward the outside.
  • the cross-sectional area of the portion of the ground electrode 27 that is located on the surface 27S side of the center CP along the thickness direction thereof is sufficiently larger than half of the cross-sectional area of the ground electrode 27. . *
  • the hardness of the portion of the ground electrode 27 that is located closer to the center electrode 5 than the center of gravity GP in the cross section is greater than the center of gravity GP of the ground electrode 27. Also, the hardness of the portion located on the side opposite to the center electrode 5 is made larger.
  • the difference in hardness is such that when the ground electrode 27 is formed, the processing rate of the portion located on the side of the surface 27S is larger than the processing rate of the portion positioned on the side opposite to the surface 27S. (The part located on the surface 27S side is greatly deformed).
  • a metal type MP having a hole HO corresponding to the cross-sectional shape of the ground electrode 27 is used to plasticize a wire WM having a circular cross-section that becomes the ground electrode 27.
  • the angle ⁇ is set to 30 ° or less. And flows into the spark discharge gap 28.
  • the flow of the air-fuel mixture flowing into the spark discharge gap 28 may not be constant (disturbance may occur), or the air-fuel mixture flowing around the ground electrode 27 may be directed from the spark discharge gap 28 toward the ground electrode 27. There is a risk of flowing (backflowing).
  • backflowing if the flow of the air-fuel mixture is disturbed or backflowed in the spark discharge gap 28, there is a possibility that the air-fuel mixture will be ignited and flame kernel growth may be hindered.
  • the distal end of the electrode 27 is configured to be positioned closer to the proximal end portion of the ground electrode 27 than the portion 5E farthest from the proximal end portion of the ground electrode 27 in the distal end surface of the center electrode 5.
  • the width of the portion corresponding to the spark discharge gap 28 in the ground electrode 27 is sufficiently large.
  • two tangent lines TL5 and TL6 that are in contact with the outline of the ground electrode 27 are drawn from the outline center CO of the front end surface of the center electrode 5.
  • the length C of the outline OL3 of the ground electrode 27 located between the contacts P3 and P4 and located on the center electrode 5 side is 1. It is set to 35 mm or more. *
  • the ground electrode 27 is made of a metal containing 95% by mass or more of Ni in order to improve its wear resistance. In order to further improve wear resistance, the ground electrode 27 may contain manganese (Mn), chromium (Cr), or aluminum (Al). *
  • the cross-sectional shape of the ground electrode 27 is the same throughout the entire area along the central axis CL2 of the ground electrode 27.
  • the angle ⁇ is set to 30 ° or less, and the ground electrode 27 is sufficiently thin. Accordingly, it is possible to more reliably prevent the flame electrode from being inhibited from growing by the ground electrode 27 and the mixture from flowing into the spark discharge gap 28. As a result, the spark diameter of the threaded portion 15 is set to M10 or less, and excellent ignitability can be realized in the spark plug 1 in which the ignitability is further deteriorated.
  • the center of gravity GP of the ground electrode 27 is the thickness of the ground electrode 27 in a cross section orthogonal to the central axis CL2 of the ground electrode 27 at the portion of the bent portion 27B that is closest to the tip of the ground electrode 27.
  • Between the center CP of the ground electrode 27 and the center of gravity GP along the thickness direction of the ground electrode 27 and located on the surface 27S side (bent inside) of the ground electrode 27 with respect to the position of 1/2 of The distance X is 4% or more of the thickness T of the ground electrode 27. That is, in the bent portion 27B, the portion closest to the tip of the ground electrode 27 has a sufficiently small cross-sectional area at a portion located outside the bent from the center CP.
  • the tensile stress at the portion of the bent portion 27B that is closest to the tip of the ground electrode 27 acts directly on the tip of the ground electrode 27 and is a major factor that causes the ground electrode 27 to rise. Therefore, reducing the tensile stress at the portion of the bent portion 27B that is closest to the tip of the ground electrode 27 effectively acts to suppress the rise of the ground electrode 27.
  • the hardness of the portion of the ground electrode 27 that is located closer to the center electrode 5 (bent inside) than the center of gravity GP is on the opposite side of the center electrode 5 from the center of gravity GP of the ground electrode 27. It is made larger than the hardness of the site
  • the length B (mm) of the outline OL1 and the length A (mm) of the outline OL2 are configured to satisfy 1.43 ⁇ B / A ⁇ 1.91. Accordingly, even when the spark plug 1 is attached in a state where the ground electrode 27 exists between the spark discharge gap 28 and the fuel injection device, the air-fuel mixture is peeled off on the side surface of the ground electrode 27. In addition, the air-fuel mixture flowing from the ground electrode 27 toward the spark discharge gap 28 can smoothly flow into the spark discharge gap 28. As a result, flame nuclei can be grown more reliably and ignitability can be further improved. *
  • the length C of the outline OL3 is 1.35 mm or more, and the width of the surface (discharge surface) corresponding to the spark discharge gap 28 in the ground electrode 27 is sufficiently large. Accordingly, the spark discharge gap 28 is more difficult to expand compared to a discharge surface having a small width. Further, since the spark discharge gap 28 is difficult to expand, an increase in the discharge voltage accompanying the expansion of the spark discharge gap 28 can be suppressed, and consumption of the electrodes 5 and 27 (expansion of the spark discharge gap 28) is further suppressed. can do. As a result, durability can be further improved. *
  • the distal end of the ground electrode 27 is closer to the proximal end portion side of the ground electrode 27 than the portion 5E farthest from the proximal end portion of the ground electrode 27 on the distal end surface of the center electrode 5. Is located. Therefore, the growth inhibition of the flame kernel due to the tip of the ground electrode 27 can be more reliably suppressed, and the flame nucleus can be grown larger. As a result, even better ignitability can be achieved. *
  • the ground electrode 27 is formed of a metal containing 95% by mass or more of Ni having excellent thermal conductivity. Therefore, the wear resistance of the ground electrode 27 can be improved, and the durability can be further improved.
  • the angle ⁇ can be varied by changing the thickness of the ground electrode after setting the screw diameter of the screw portion to M10, M12, or M14.
  • the sample of the changed spark plug was produced and the ignitability evaluation test was done about each sample.
  • the outline of the ignitability evaluation test is as follows. That is, a sample was attached to a four-cylinder engine with a displacement of 1.5 L so that the ground electrode was positioned between the fuel injection device and the spark discharge gap. Then, the ignition timing was gradually advanced while the engine was operated, and the ignition angle (° CA) when the variation rate of the average combustion pressure reached 20% was measured.
  • FIG. 9 shows the test results of the test.
  • the test result of the sample with the angle ⁇ of 30 ° is shown by a black circle
  • the test result of the sample with the angle ⁇ of 32 ° is shown by a black triangle
  • the test of the sample with the angle ⁇ of 34 ° Results are shown as black squares.
  • the test result of the sample with an angle ⁇ of 36 ° is shown by a white circle
  • the test result of a sample with an angle ⁇ of 38 ° is shown by a white triangle
  • the test result of a sample with an angle ⁇ of 40 ° is shown. Indicated by a white square.
  • the distance from the axis to the center of the ground electrode base end surface along the direction orthogonal to the axis is 3.6 mm, and the sample with the screw diameter M12 is 4 mm.
  • the distance was set to 5.1 mm.
  • the ground electrode was relatively thin and the angle ⁇ was 30 ° or less. That is, the ground electrode used was not so high in strength against internal stress that it was likely to rise up in the ground electrode.
  • the ground electrode does not rise even when a large vibration is applied over a long period of time, even though the angle ⁇ is 30 ° or less.
  • the center of gravity of the ground electrode is located closer to the center electrode side (inner side of the bend) than the center (thickness center) of the bent portion closest to the tip of the ground electrode, and the deviation rate is 4%.
  • This is considered to be because the cross-sectional area of the portion located on the opposite side (bent outer side) from the center electrode with respect to the thickness center is reduced, and consequently the tensile stress acting on the tip of the ground electrode is reduced. It is done. *
  • the tensile stress generated in the portion of the bent portion that is closest to the tip of the ground electrode acts directly on the tip of the ground electrode and becomes a major factor that causes the ground electrode to rise. For this reason, it is considered that reducing the tensile stress at the portion of the bent portion that is closest to the tip of the ground electrode effectively acts in terms of suppressing the rise of the ground electrode.
  • the bent electrode is closest to the tip of the ground electrode.
  • the center of gravity of the ground electrode is positioned closer to the surface of the ground electrode than the position (center) of the ground electrode in a cross section perpendicular to the center axis of the ground electrode It can be said that the distance along the thickness direction between the center of the ground electrode and the center of gravity along the thickness direction of the ground electrode is preferably 4% or more of the thickness of the ground electrode.
  • the hardness of the portion of the ground electrode that is located closer to the center electrode than the center of gravity is the portion of the ground electrode that is located on the opposite side of the center electrode from the center of gravity.
  • Each sample was prepared, and the above-described rise resistance test was performed on each sample. In this test, the engine was operated for 100 hours in a fully open state (5600 rpm), and vibration was applied to the sample under more severe conditions. Table 1 shows the test results of the test.
  • the hardness of the portion of the ground electrode located closer to the center electrode than the center of gravity is It can be said that the hardness is preferably larger than the hardness of the portion located on the opposite side of the center electrode from the center of gravity.
  • the ratio (B / A) of the length B of the outline OL1 to the length A of the outline OL2 is changed by changing the outer peripheral shape of the portion corresponding to the spark discharge gap in the axial direction of the ground electrode.
  • Samples of spark plugs with various changes were made, and airflow analysis tests were performed on each sample.
  • the outline of the airflow analysis test is as follows. That is, the tip of the sample was placed in a tube with an air flow rate of 20 m / s in a state where the ground electrode was positioned on the windward side (upstream side) (a state where the wind hits the back surface of the ground electrode).
  • spark plug samples in which the length C of the outline OL3 in the range RA was variously changed were prepared, and a desktop spark durability test was performed on each sample.
  • the outline of the desktop spark durability test is as follows. That is, after attaching a sample to a predetermined chamber, the inside of the chamber was set to an atmospheric atmosphere, and the pressure in the chamber was set to 0.4 MPa. Then, the voltage was applied to the sample (spark discharge gap) by a full-transistor ignition device with a frequency of applied voltage of 60 Hz (that is, voltage applied at a rate of 3600 times per minute) Spark discharge using the electrode as the negative electrode was generated over 100 hours.
  • FIG. 11 shows the results of the test.
  • the size of the spark discharge gap before the test was 0.9 mm, and the angle ⁇ was 30 ° or less.
  • the size and constituent materials of the center electrode are the same, and the amount of consumption of the center electrode accompanying spark discharge is constant (that is, the difference in gap increase amount is caused only by the consumption of the ground electrode). . *
  • the sample having a length C of 1.35 mm or more has an extremely small gap increase even when the angle ⁇ is 30 ° or less and there is a concern about the rapid expansion of the spark discharge gap. It became clear that we could do it. This is because the width of the surface (discharge surface) corresponding to the spark discharge gap of the ground electrode is sufficiently large, so that the spark discharge gap is less likely to be expanded compared to the one with a small discharge surface width. This is considered to be due to the fact that the increase in the discharge voltage is suppressed due to the fact that the spark discharge gap has become difficult to expand. *
  • the length C is set to 1.35 mm or more. Is preferable. *
  • the portion of the central electrode that is farthest from the proximal end portion of the ground electrode is used as a reference, and the proximal end side of the ground electrode from the reference along the central axis of the ground electrode is determined.
  • spark plug samples in which the distance E from the reference along the central axis to the tip of the ground electrode was variously changed were produced, and a critical air-fuel ratio confirmation test was performed on each sample.
  • the outline of the limit air-fuel ratio confirmation test is as follows.
  • the air-fuel ratio when the engine torque fluctuation rate exceeded 5% was specified as the limit air-fuel ratio.
  • FIG. 12 shows the results of the test. In addition, it means that it is excellent in ignitability, so that a limit air fuel ratio is large.
  • the distance E is positive because the tip of the ground electrode is farther away from the portion of the tip end surface of the center electrode that is farthest from the base end of the ground electrode when viewed from the tip end side in the axial direction. It means that it is located on the proximal end side (that is, at least a part of the distal end surface of the center electrode is visible when viewed from the distal end side in the axial direction). *
  • the distal end of the ground electrode when viewed from the distal end side in the axial direction, is from the portion of the distal end surface of the center electrode that is farthest from the proximal end portion of the ground electrode Also, it can be said that it is preferable to be configured to be positioned on the base end side of the ground electrode.
  • FIG. 13 shows the results of the test.
  • the distance E was set to +0.3 mm.
  • the size and constituent materials of the center electrode are the same, and the amount of consumption of the center electrode accompanying spark discharge is constant (that is, the difference in gap increase amount is caused only by the consumption of the ground electrode). . *
  • the ground electrode is preferably formed of a metal containing 95 mass% or more of Ni in order to improve the wear resistance of the ground electrode and realize further excellent durability.
  • the outline OL1 of the ground electrode 27 is a curved curve that protrudes toward the side away from the center of gravity GP of the ground electrode 27.
  • the outline OL1 only needs to be formed by a plurality of line segments, a curved line convex toward the side away from the center of gravity GP, or one or more line segments and the curved line. Therefore, as shown in FIGS. 14 (a) and 14 (b), grounding is performed so that an outline OL1 located between both contacts P1 and P2 and located on the opposite side of the center electrode 5 is formed by a plurality of line segments.
  • the electrodes 31 and 32 may be configured.
  • the ground electrode 33 may be configured such that the outline OL1 is formed by both a line segment and a curved line that protrudes toward the side away from the center of gravity GP.
  • the ground electrode 34 may be configured such that the outline OL1 is formed by a plurality of curved lines that are convex toward the side away from the center of gravity GP.
  • the spark discharge gap 28 is formed between the center electrode 5 and the ground electrode 27, but a metal containing a noble metal (for example, platinum or iridium) at the tip of the center electrode 5.
  • a spark discharge gap 28 may be formed between the chip and the ground electrode 27.
  • the tool engaging portion 19 has a hexagonal cross section, but the shape of the tool engaging portion 19 is not limited to such a shape.
  • it may be a Bi-HEX (deformed 12-angle) shape [ISO 22777: 2005 (E)].

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Spark Plugs (AREA)
PCT/JP2012/004908 2011-11-25 2012-08-02 スパークプラグ WO2013076887A1 (ja)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201280057910.2A CN103947059B (zh) 2011-11-25 2012-08-02 火花塞

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2011-256878 2011-11-25
JP2011256878A JP5331190B2 (ja) 2011-11-25 2011-11-25 スパークプラグ

Publications (1)

Publication Number Publication Date
WO2013076887A1 true WO2013076887A1 (ja) 2013-05-30

Family

ID=48469359

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2012/004908 WO2013076887A1 (ja) 2011-11-25 2012-08-02 スパークプラグ

Country Status (3)

Country Link
JP (1) JP5331190B2 (zh)
CN (1) CN103947059B (zh)
WO (1) WO2013076887A1 (zh)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017174681A (ja) 2016-03-24 2017-09-28 株式会社デンソー 内燃機関用のスパークプラグ
US10826279B1 (en) 2019-08-28 2020-11-03 Federal-Mogul Ignition Llc Spark plug ground electrode configuration
JP7543955B2 (ja) 2021-03-16 2024-09-03 株式会社デンソー スパークプラグ、スパークプラグの製造方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50157732A (zh) * 1974-06-12 1975-12-19
JPH05182743A (ja) * 1991-12-27 1993-07-23 Ngk Spark Plug Co Ltd スパークプラグ用接地電極の製造方法
JPH08213149A (ja) * 1995-02-01 1996-08-20 Ngk Spark Plug Co Ltd スパークプラグ
JP2003007423A (ja) * 2001-06-20 2003-01-10 Ngk Spark Plug Co Ltd スパークプラグ
WO2009153927A1 (ja) * 2008-06-18 2009-12-23 日本特殊陶業株式会社 スパークプラグ
JP2010086951A (ja) * 2008-09-02 2010-04-15 Ngk Spark Plug Co Ltd スパークプラグ

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5165751B2 (ja) * 2008-09-02 2013-03-21 日本特殊陶業株式会社 スパークプラグ

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50157732A (zh) * 1974-06-12 1975-12-19
JPH05182743A (ja) * 1991-12-27 1993-07-23 Ngk Spark Plug Co Ltd スパークプラグ用接地電極の製造方法
JPH08213149A (ja) * 1995-02-01 1996-08-20 Ngk Spark Plug Co Ltd スパークプラグ
JP2003007423A (ja) * 2001-06-20 2003-01-10 Ngk Spark Plug Co Ltd スパークプラグ
WO2009153927A1 (ja) * 2008-06-18 2009-12-23 日本特殊陶業株式会社 スパークプラグ
JP2010086951A (ja) * 2008-09-02 2010-04-15 Ngk Spark Plug Co Ltd スパークプラグ

Also Published As

Publication number Publication date
JP2013114754A (ja) 2013-06-10
JP5331190B2 (ja) 2013-10-30
CN103947059A (zh) 2014-07-23
CN103947059B (zh) 2015-12-02

Similar Documents

Publication Publication Date Title
EP2221931B1 (en) Spark plug
JP5331112B2 (ja) 内燃機関用スパークプラグ
JP4928626B2 (ja) スパークプラグ
US8288931B2 (en) Spark plug having a center electrode and a ground electrode provided with no noble metal member
EP2216862B1 (en) Spark plug
JP5331114B2 (ja) 内燃機関用スパークプラグ
EP2036173B2 (en) Small diameter/long reach spark plug with improved insulator design
JPWO2009017101A1 (ja) 内燃機関用スパークプラグ
WO2014125811A1 (ja) 点火プラグ
JP5331190B2 (ja) スパークプラグ
JP4648485B1 (ja) スパークプラグ
JP5622991B2 (ja) スパークプラグ
US10256610B2 (en) Spark plug
JP5715652B2 (ja) スパークプラグ及びその製造方法
JP5616858B2 (ja) 点火プラグ
JP2006092956A (ja) スパークプラグ
JP5809664B2 (ja) スパークプラグ
JP5606404B2 (ja) スパークプラグ
JP5816126B2 (ja) スパークプラグ
JP6781141B2 (ja) スパークプラグ
JP2010251216A (ja) 内燃機関用スパークプラグ
JP5723250B2 (ja) スパークプラグ及びその製造方法
JP2009151996A (ja) 内燃機関用スパークプラグ

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: 12850830

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12850830

Country of ref document: EP

Kind code of ref document: A1