WO2009116533A1 - スパークプラグ - Google Patents
スパークプラグ Download PDFInfo
- Publication number
- WO2009116533A1 WO2009116533A1 PCT/JP2009/055169 JP2009055169W WO2009116533A1 WO 2009116533 A1 WO2009116533 A1 WO 2009116533A1 JP 2009055169 W JP2009055169 W JP 2009055169W WO 2009116533 A1 WO2009116533 A1 WO 2009116533A1
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- WO
- WIPO (PCT)
- Prior art keywords
- insulator
- end side
- rear end
- length
- spark plug
- Prior art date
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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
- H01T13/38—Selection of materials for insulation
Definitions
- the present invention relates to a spark plug that is assembled in an internal combustion engine and ignites an air-fuel mixture.
- spark plugs for ignition are used in internal combustion engines.
- a general spark plug has an insulator that holds a center electrode in its own shaft hole, is held by a metal shell so as to surround the periphery of the radial direction, a ground electrode that is joined to the metal shell, a center electrode, A spark discharge gap is formed between the two.
- the air-fuel mixture is ignited by spark discharge performed in the spark discharge gap.
- the insulator is made thinner and its strength (rigidity) decreases as the diameter of the spark plug is reduced, cracks and cracks may occur when an external force is applied to the insulator in a direction perpendicular to the axial direction (bending direction). It becomes easy.
- the external force in the bending direction may be applied, for example, when a tool for installation collides with the rear end side body portion (insulator head portion) of the insulator exposed from the rear end of the metal shell when attaching the spark plug to the engine. There is.
- a terminal fitting electrically connected to the center electrode is exposed at the rear end of the insulator, but after the spark plug is attached to the engine, a voltage is applied to the terminal fitting to the spark discharge gap.
- a plug cap associated with the lead wire is fitted.
- the spark plug is subjected to vibration accompanying the driving of the engine in this state, a load due to the weight of the plug cap is generated, and there is a possibility that an external force in the bending direction is applied to the rear end side body portion of the insulator.
- the outer peripheral surface of the insulator is provided with a portion having a different outer diameter, and the insulator is generally held by the metal shell in such a manner that the portion is sandwiched in the axial direction by caulking. That is, the insulator is held in a form supported by the metal shell in the inner hole of the metal shell. For this reason, when an external force acting in the bending direction is applied to the rear end side body of the insulator, when the position receiving the external force is regarded as a power point, the side closer to the power point of the insulator among the support positions by the metal shell, that is, The support position on the rear end side serves as a fulcrum.
- the point of action corresponding to the force point is generated on the tip side of the insulator, but the support position on the tip side of the insulator by the metal shell serves to regulate the action at the point of action, that is, the movement of the insulator on the tip side.
- a load corresponding to an external force is applied to the insulator between the two support positions in the axial direction. For this reason, there has been a risk that cracks or cracks may occur in the insulator in the inner hole of the metal shell simply by improving the strength (rigidity) of the body portion on the rear end side of the insulator.
- the present invention has been made to solve the above problems, and by adjusting the balance of the strength (rigidity) of the insulator based on the support position of the insulator by the metal shell, it is possible to prevent local stress concentration.
- An object of the present invention is to provide a spark plug capable of increasing the proof stress and preventing the insulator from being cracked or broken.
- An insulator that holds the center electrode inside its own shaft hole, and a tool engaging portion for attachment to the internal combustion engine, and a caulking portion formed on the rear end side from the tool engaging portion, A portion from the shoulder portion to the step portion of the insulator is held between a shelf portion that protrudes inward in the radial direction and is formed in the inner hole at the front end side of the tool engaging portion.
- a spark plug comprising a metal shell, and an annular packing interposed between the shelf and the step, the axis line In the direction, the position of the rear end of the insulator is A, the position where the insulator and the packing first contact from the front end side of the insulator is B, and the position of the insulator first from the rear end side of the insulator.
- Ymax is the position of the position Y when taking
- LAXmax is the length between the position A and the position Xmax
- LBYmax is the length between the position B and the position Ymax
- the section modulus at the position Ymax of the insulator is ZYmax
- ⁇ A LAXmax / ZXmax
- ⁇ B (LAC ⁇ LBYmax) / (LBC ⁇ ZYmax)
- at least ⁇ A Either ⁇ B is 0.47 or more and 0.71 ⁇ ⁇ A / ⁇ B ⁇ 1.27 is satisfied.
- the spark plug of the invention according to claim 2 has a front end side body portion having a step portion on a front end side of its outer peripheral surface, and a diameter larger than the front end side body portion on the rear end side of the front end side body portion. And a shaft hole formed in the axial direction with a rear end side body portion having a diameter smaller than that of the middle body portion formed on the rear end side of the middle body portion via a shoulder portion.
- a tool engaging portion for attaching to the internal combustion engine, a caulking portion formed on the rear end side from the tool engaging portion, and the tool engaging portion
- a metal shell for holding a portion from the shoulder portion to the step portion of the insulator between the radially inwardly protruding shelf portions formed in the inner hole on the front end side, and the shelf
- An annular first packing interposed between the step portion and the step portion, the caulking portion of the metal shell, the shoulder portion of the insulator or A spark plug comprising an annular second packing interposed between the rear end side body portion, wherein the position of the rear end of the insulator is A in the axial direction, and the front end side of the insulator B is a position where the insulator and the first packing are contacted first, C is a position where the insulator and the second packing are contacted first from the rear end side of the insulator, and the position A and the position A length between the position C is LAC, a length between the position B and the position C is L
- a spark plug according to the first or second aspect of the invention, wherein the metal shell is attached to an internal combustion engine at a tip side of the tool engaging portion.
- a mounting screw portion formed with a screw thread is provided, and the nominal diameter of the screw thread of the mounting screw portion is M10 or less.
- the outer diameter of the rear end side body portion of the insulator is ⁇ 8.5 mm or less.
- the strength against local stress concentration can be increased by adjusting the balance of the size and section modulus of the insulator, Even when an external force is applied in the bending direction orthogonal to the axial direction, the stress generated according to the external force is dispersed and relaxed inside, and as a result, it is possible to prevent the insulator from being cracked or cracked. More specifically, as will be described below, the balance of the strength (rigidity) of the insulator is adjusted by defining the relationship between ⁇ A and ⁇ B described later.
- the insulator is held in the inner hole of the metal shell in a form supported by the caulking portion of the metal shell and the shelf through the packing. For this reason, when an external force is applied to the rear end side body of the insulator in the bending direction orthogonal to the axis, if the position where the external force is received is regarded as a power point, the insulation by the crimped part closer to the power point than the shelf
- the insulator support position (position C at which the crimping portion is in contact with the insulator on the rearmost end side) serves as a fulcrum.
- the present invention aims to reduce the diameter of the insulator in order to reduce the size of the spark plug, and when the insulator is subjected to an external force in the bending direction on the rear end side body portion, cracks are caused by local stress concentration.
- Insulators that may cause cracks or the like that is, insulators in which at least one of ⁇ A or ⁇ B has a value of 0.47 or more are targeted.
- insulators in which at least one of ⁇ A or ⁇ B has a value of 0.47 or more are targeted.
- the inventors in order to adjust the balance of strength (rigidity) so that local stress concentration can be alleviated in an insulator in which at least one of ⁇ A or ⁇ B is 0.47 or more.
- the resistance against local stress concentration can be increased by adjusting the balance of the size and section modulus of the insulator, the rear end side of the insulator Even if the body part receives an external force in a bending direction orthogonal to the axial direction, the stress generated according to the external force is dispersed and relaxed inside, and as a result, it is possible to prevent the insulator from being cracked or cracked. it can. More specifically, as will be described below, the balance of the strength (rigidity) of the insulator is adjusted by defining the relationship between ⁇ A and ⁇ B described later.
- the insulator used for the spark plug of the invention according to claim 2 is supported by the crimping portion through the second packing of the metal shell and the shelf through the first packing. Retained in the hole. For this reason, when an external force is applied to the rear end side body of the insulator in the bending direction orthogonal to the axis, if the position where the external force is received is regarded as a power point, the insulation by the crimped part closer to the power point than the shelf
- the insulator support position (position C at which the second packing abuts the insulator on the most rear end side) serves as a fulcrum.
- the yield strength against bending between the position A and the position C of the insulator ⁇ A indicating the higher the smaller the value.
- ⁇ B indicating the proof stress against the stress applied to the position C is also higher as the value is smaller. Accordingly, if both the values of ⁇ A and ⁇ B are small, specifically, both are less than 0.47, the insulator originally has a sufficient resistance to bending, and therefore the balance of strength for adjusting the stress is adjusted. There is no need.
- the present invention aims to reduce the diameter of the insulator in order to reduce the size of the spark plug, and when the insulator is subjected to an external force in the bending direction on the rear end side body portion, cracks are caused by local stress concentration.
- Insulators that may cause cracks or the like that is, insulators in which at least one of ⁇ A or ⁇ B has a value of 0.47 or more are targeted.
- insulators in which at least one of ⁇ A or ⁇ B has a value of 0.47 or more are targeted.
- the inventors in order to adjust the balance of strength (rigidity) so that local stress concentration can be alleviated in an insulator in which at least one of ⁇ A or ⁇ B is 0.47 or more.
- the insulator design should satisfy 0.71 ⁇ ⁇ A / ⁇ B ⁇ 1.27.
- the present invention is preferably applied to a small-diameter spark plug that is subject to restrictions on the design of the insulator, and more specifically, it is formed on the mounting screw portion of the metal shell as in the invention according to claim 3.
- the present invention is preferably applied to a spark plug having a nominal thread diameter of M10 or less.
- the present invention is applicable to small-diameter spark plugs that require the outer diameter of the rear end side body of the insulator to be 8.5 mm or less, as in the invention according to claim 4. Is desirable.
- FIG. 1 is a longitudinal sectional view of a spark plug 100.
- FIG. It is sectional drawing of the insulator 10 for demonstrating the position and magnitude
- FIG. It is a fragmentary sectional view of spark plug 200 as a modification. It is a fragmentary sectional view of spark plug 300 as a modification. It is a fragmentary sectional view of spark plug 400 as a modification.
- FIG. 1 is a longitudinal sectional view of a spark plug 100.
- the axis O direction of the insulator 10 will be described as the vertical direction in the drawing, and the lower side will be described as the front end side of the spark plug 100 and the upper side as the rear end side.
- the spark plug 100 generally has an insulator 10 that holds the center electrode 20 on the front end side in its own shaft hole 12 and holds the terminal fitting 40 on the rear end side.
- the insulator 10 has a structure in which the periphery of the insulator 10 is surrounded and held by the metal shell 50. Further, the ground electrode 30 is joined to the tip 48 of the metal shell 50, the tip 31 of the ground electrode 30 is bent toward the tip 22 of the center electrode 20, and a spark discharge gap GAP is formed therebetween. Is formed.
- the shoulder portion 14 is a part of the middle torso portion 19, and at the upper portion (rear end portion) of the middle torso portion 19, the rear end side torso portion 18 having a diameter different from itself. It is the part which connects and.
- a front end side body portion 17 having an outer diameter smaller than that of the rear end side body portion 18 is formed on the front end side (lower side in FIG. 1) from the middle body portion 19, and further, the front end side from the front end side body portion 17.
- a leg length portion 13 having an outer diameter smaller than that of the distal end side body portion 17 is formed. The long leg portion 13 is reduced in diameter toward the tip side, and when the spark plug 100 is attached to the engine head (not shown) of the internal combustion engine, it is exposed to the combustion chamber.
- a step portion 11 is formed in a step shape between the leg length portion 13 and the front end side body portion 17.
- the metal shell 50 is a cylindrical metal fitting for fixing the spark plug 100 to an engine head of an internal combustion engine (not shown), and has an inner hole 59 penetrating in the direction of the axis O.
- the metal shell 50 holds the insulator 10 in the inner hole 59 so as to surround a portion from a part of the rear end side body portion 18 of the insulator 10 to the leg long portion 13.
- the metal shell 50 is made of an iron-based material, and has a tool engaging portion 51 to which a spark plug wrench (not shown) is fitted, and a mounting screw in which a screw thread to be screwed into a mounting hole (not shown) of the engine head is formed. Part 52.
- a bowl-shaped seal portion 54 is formed between the tool engaging portion 51 and the mounting screw portion 52 of the metal shell 50.
- An annular gasket 5 formed by bending a plate is fitted into a screw neck 49 between the mounting screw portion 52 and the seal portion 54.
- the insulator 10 is pressed toward the front end side in the metal shell 50 through the packings 6, 7 and the talc 9.
- the step portion 11 of the insulator 10 is supported via the annular packing 8 on the shelf portion 56 formed so as to protrude inwardly at the position of the mounting screw portion 52 in the inner hole 59 of the metal shell 50.
- the metal shell 50 and the insulator 10 are integrated. At this time, the airtightness between the metal shell 50 and the insulator 10 is maintained by the packing 8 and combustion gas is prevented from flowing out.
- the buckling portion 58 is configured to bend outwardly and deform with the addition of a compressive force during caulking, and the main metal fitting 50 is made to have a longer compression length in the direction of the axis O of the talc 9. The airtightness inside is increased.
- the packing 6 corresponds to the “second packing” in the present invention
- the packing 8 corresponds to the “first packing” in the present invention.
- the ground electrode 30 is a rod-shaped electrode member made of a metal having high corrosion resistance.
- a nickel alloy such as Inconel (trade name) 600 or 601 is used.
- the ground electrode 30 has a substantially rectangular cross section in the longitudinal direction, and a base portion 32 on one end side in the extending direction is joined to the distal end surface 57 of the metal shell 50 by welding. Further, the distal end portion 31 on the other end side in the extending direction of the ground electrode 30 is bent so that one surface 33 faces the distal end portion 22 side of the center electrode 20.
- a spark discharge gap GAP is formed between the tip 31 of the ground electrode 30 and the tip 22 of the center electrode 20 provided with the electrode tip 90.
- FIG. 2 is a cross-sectional view of the insulator 10 for explaining the position and size of the portion set in the insulator 10.
- the insulator 10 is configured such that a portion from a part of the rear end side body portion 18 to the leg long portion 13 is accommodated in the inner hole 59 of the metal shell 50. It is held by the metal fitting 50. More specifically, in the inner hole 59 of the metal shell 50, the packing 8 disposed on the shelf portion 56 and the packings 6 and 7 disposed on the tool engaging portion 51 and the crimping portion 53 are insulated. The step 10 of the insulator 10 is in contact with the shoulder 14 and the rear end side body 18. The insulator 10 is held by the metal shell 50 by being crimped while being supported in the inner hole 59 of the metal shell 50 through the packings 6, 7, and 8.
- the strength (rigidity) of the insulator 10 itself on both sides in the axis O direction so that the load applied to the acting point side when the rear end side body portion 18 receives an external force in the bending direction can be alleviated.
- the position of the rear end of the insulator 10 in the direction of the axis O is a position A.
- the position where the insulator 10 is first supported by the metal shell 50 from the rear end side of the insulator 10, that is, the position where the packing 6 is disposed in the present embodiment is the position C, which is regarded as the fulcrum described above.
- ⁇ A LAXmax / ZXmax (1)
- ⁇ B (LAC ⁇ LBYmax) / (LBC ⁇ ZYmax) (2) It is defined as In the spark plug 100 of the present embodiment, at least one of ⁇ A or ⁇ B is 0.47 or more, and when ⁇ A / ⁇ B is obtained, 0.71 ⁇ ⁇ A / ⁇ B ⁇ 1.27 is satisfied. Is stipulated.
- ⁇ A represents a resistance to bending of the insulator 10 between the position A and the position C
- ⁇ B represents a bending force between the position A and the position C of the insulator 10. Accordingly, the proof stress against the stress applied between the position B and the position C is shown.
- ⁇ A and ⁇ B attention is paid to ⁇ A and ⁇ B, and the relationship ⁇ A / ⁇ B between them is set so that the insulator 10 can obtain sufficient strength (rigidity) to prevent the occurrence of cracks and cracks. Find it.
- the strength (rigidity) of the insulator 10 is higher. Therefore, when both ⁇ A and ⁇ B of the insulator 10 are less than 0.47, the insulator 10 obtains sufficient strength (rigidity) regardless of the value of ⁇ A / ⁇ B and prevents the occurrence of cracks and cracks. It can be confirmed from the evaluation test of Example 1 described later. That is, if both ⁇ A and ⁇ B are less than 0.47, the insulator 10 has sufficient strength to prevent cracks and cracks without strictly adjusting the balance of the size and section modulus of each part of the insulator 10. Can be obtained.
- the present invention is preferably applied to the small-diameter spark plug 100, that is, to the spark plug 100 in which at least one of ⁇ A or ⁇ B tends to be 0.47 or more. More specifically, the present invention may be applied to the spark plug 100 in which the nominal diameter of the thread formed on the attachment screw portion 52 of the metal shell 50 is M10 or less.
- the spark plug 100 having such a size, there is a limit in securing its own rigidity when the metal shell 50 is thinned, so that the size that can be secured as the outer diameter of the insulator 10 is limited. Therefore, the section modulus of the insulator 10 tends to be small, and as a result, the values of ⁇ A and ⁇ B tend to be large. In addition, for the spark plug 100 in which the outer diameter of the rear end side body portion 18 of the insulator 10 is required to be ⁇ 8.5 mm or less by design, the section modulus is likely to be small as described above. Since the values of ⁇ A and ⁇ B tend to be large values, it is desirable to apply the present invention.
- the present invention can be modified in various ways.
- the metal shell 50 when the insulator 10 is held by the metal shell 50, the metal shell 50 is not directly in contact with the insulator 10, but the insulator 10 is held by the metal shell 50 via the packings 6, 7, 8. It was set as the form to support.
- the packing 6 when the insulator 10 is supported by the metal shell 50, the packing 6 is the one that abuts the insulator 10 on the rearmost end side in the direction of the axis O. Therefore, the packing 6 is the rear end of the insulator 10. It acted as a fulcrum when an external force in the bending direction was applied to the side body 18. Therefore, although the arrangement position of the packing 6 in the direction of the axis O is the position C, the position C is not necessarily limited to the arrangement position of the packing 6.
- the contact position of the crimped portion 353 that first contacts the insulator 310 from the rear end side in the direction of the axis O may be the position C.
- the packing 406 interposed between the crimped portion 453 of the metal shell 450 and the insulator 410 is not brought into contact with the rear end side body portion 418, and is a shoulder portion. You may make it contact
- the position C is the same as that of the present embodiment, and since the packing 406 first contacts the insulator 410 from the rear end side in the axis O direction, the position where the packing 406 contacts the insulator 410 is determined. , Position C may be used.
- the insulator 10 can obtain sufficient strength (rigidity) and can prevent the occurrence of cracks and cracks. An evaluation test was conducted to confirm the above.
- Example 1 In this evaluation test, several types of metal shells with a nominal thread diameter of the mounting screw portion of M10 and different lengths in the direction of the axis O are prepared, and there are 14 types and 39 types of insulators with dimensions that can be assembled to these metal shells. Designed. Specifically, each insulator was designed so that the length LAC between the position A and the position C was 26 mm in the dimension of the spark plug after assembly. The length LBC between the position B and the position C of the insulator was varied in a range of 25 to 33 mm according to the type of the metal shell that can be assembled.
- the current product 1 and the current product 2 both have ⁇ A and ⁇ B of less than 0.47, and have sufficient strength regardless of the location of the insulator. It was. Test samples A-1, A-2, B-3, and C-3 with both ⁇ A and ⁇ B less than 0.47 have sufficient resistance to bending, regardless of the location of the insulator, as with the current product. Good results were obtained in the impact test regardless of the value of ⁇ A / ⁇ B. On the other hand, in any of the other test samples, either one or both of ⁇ A and ⁇ B have a value of 0.47 or more, and depending on the part of the insulator, sufficient resistance to bending can be obtained. There is no fear.
- test samples C-2, E-3 which are adjusted so that ⁇ A / ⁇ B falls within the range of 0.71 to 1.27 by adjusting the balance of the size and section modulus of the insulator.
- F-3, F-4, G-1, G-2, H-1, H-2, K-3, K-4, L-1, and L-2 good results were obtained in the impact test. It was.
- the balance is adjusted. By doing so, it has been found that the stress generated by the impact from the outside is dispersed and relaxed inside, and as a result, it is possible to prevent the insulator from being cracked or cracked.
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Abstract
Description
10 絶縁碍子
11 段部
12 軸孔
14 肩部
17 先端側胴部
18 後端側胴部
19 中胴部
20 中心電極
50 主体金具
51 工具係合部
52 取付ねじ部
53 加締部
56 棚部
59 内孔
100 スパークプラグ
Z=(π/32)×(D14-D24)/D1 ・・・ (a)
従って、軸孔の内径D2の上限値は、上記式(a)に基づき外径D1と断面係数Zの値によって定まり、断面係数Zの上限値は、上記式(a)に基づき外径D1と軸孔の内径D2の値によって定まるものである。
τA=LAXmax/ZXmax ・・・ (1)
τB=(LAC・LBYmax)/(LBC・ZYmax) ・・・ (2)
と定義する。本実施の形態のスパークプラグ100では、少なくともτAまたはτBのいずれか一方が0.47以上であると共に、τA/τBを求めたときに、0.71≦τA/τB≦1.27を満たすことを規定している。
IX=MX/ZX=(F・LAX)/ZX・・・(3)
となる。同様に、位置Yの部位における曲げによって発生する絶縁碍子10の引張張力IYを求めると、
IY=MY/ZY={(LAC/LBC)・F・LBY}/ZY=(LAC・F・LBY)/(LBC・ZY)・・・(4)
となる。
この評価試験では、取付ねじ部のねじ山の呼び径がM10で軸線O方向の長さが異なる主体金具を数種類用意し、それらの主体金具に組み付け可能な寸法の絶縁碍子を14分類39種類、設計した。具体的に、どの絶縁碍子も組み立て後のスパークプラグの寸法で位置Aと位置Cとの間の長さLACが26mmとなるように設計を行った。そして、絶縁碍子の位置Bと位置Cとの間の長さLBCを、組み付け可能な主体金具の種類に合わせ25~33mmの範囲で異ならせた。さらに、例えば軸孔の内径を異ならせることにより、絶縁碍子の各部位の肉厚を異ならせ、断面係数ZXmax,ZYmaxがテストサンプル間で異なる組み合わせとなるように設計した。このように、設計値(LAC,LBC,LXmax,LYmax,ZXmax,ZYmaxの値)を互いに異ならせた14分類39種類の絶縁碍子を各種10本ずつ作成し、それぞれに対応する主体金具に組み付けて、試験用のスパークプラグのテストサンプルを組み立てた。また、比較用に、位置Aと位置Cとの間の長さLACが26mmで、取付ねじ部のねじ山の呼び径がM10より大きなスパークプラグの現行品を2種類、それぞれ10本ずつ用意した。なお、各テストサンプルや現行品の識別用のサンプル番号については、後述する表1に示す通りである。
Claims (4)
- 自身の外周面の先端側に段部を有する先端側胴部と、当該先端側胴部の後端側に前記先端側胴部よりも大径の中胴部と、当該中胴部の後端側に肩部を介して形成された前記中胴部よりも小径の後端側胴部とを備え、軸線方向に形成された自身の軸孔の内部で中心電極を保持する絶縁碍子と、
内燃機関への取り付けのための工具係合部を備え、この工具係合部より後端側に形成された加締部、および前記工具係合部よりも先端側にて自身の内孔に形成された径方向内向きに突出する棚部の間に、前記絶縁碍子の前記肩部から前記段部までの部位を保持する主体金具と、
前記棚部と前記段部との間に介在される環状のパッキンと
を備えたスパークプラグであって、
前記軸線方向において、
前記絶縁碍子の後端の位置をA、
前記絶縁碍子の先端側から最初に前記絶縁碍子と前記パッキンとが接触する位置をB、
前記絶縁碍子の後端側から最初に前記絶縁碍子と前記加締部とが接触する位置をC、
前記位置Aと前記位置Cとの間の長さをLAC、
前記位置Bと前記位置Cとの間の長さをLBC、
前記位置Aと前記位置Cとの間における任意の位置をX、
前記位置Bと前記位置Cとの間における任意の位置をY、
前記位置Aと前記位置Xとの間の長さをLAX、
前記位置Bと前記位置Yとの間の長さをLBY、
前記絶縁碍子の前記位置Xの部位における断面係数をZX、
前記絶縁碍子の前記位置Yの部位における断面係数をZY、
LAX/ZXが最大値をとるときの前記位置Xの位置をXmax、
LBY/ZYが最大値をとるときの前記位置Yの位置をYmax、
前記位置Aと前記位置Xmaxとの間の長さをLAXmax、
前記位置Bと前記位置Ymaxとの間の長さをLBYmax、
前記絶縁碍子の前記位置Xmaxの部位における断面係数をZXmax、
前記絶縁碍子の前記位置Ymaxの部位における断面係数をZYmax
とし、
τA=LAXmax/ZXmax、
τB=(LAC・LBYmax)/(LBC・ZYmax)
としたときに、
少なくともτAまたはτBのいずれか一方が0.47以上であると共に、
0.71≦τA/τB≦1.27を満たすスパークプラグ。 - 自身の外周面の先端側に段部を有する先端側胴部と、当該先端側胴部の後端側に前記先端側胴部よりも大径の中胴部と、当該中胴部の後端側に肩部を介して形成された前記中胴部よりも小径の後端側胴部とを備え、軸線方向に形成された自身の軸孔の内部で中心電極を保持する絶縁碍子と、
内燃機関への取り付けのための工具係合部を備え、この工具係合部より後端側に形成された加締部、および前記工具係合部よりも先端側にて自身の内孔に形成された径方向内向きに突出する棚部の間に、前記絶縁碍子の前記肩部から前記段部までの部位を保持する主体金具と、
前記棚部と前記段部との間に介在される環状の第1パッキンと、
前記主体金具の前記加締部と、前記絶縁碍子の前記肩部または前記後端側胴部との間に介在される環状の第2パッキンと
を備えたスパークプラグであって、
前記軸線方向において、
前記絶縁碍子の後端の位置をA、
前記絶縁碍子の先端側から最初に前記絶縁碍子と前記第1パッキンとが接触する位置をB、
前記絶縁碍子の後端側から最初に前記絶縁碍子と前記第2パッキンとが接触する位置をC、
前記位置Aと前記位置Cとの間の長さをLAC、
前記位置Bと前記位置Cとの間の長さをLBC、
前記位置Aと前記位置Cとの間における任意の位置をX、
前記位置Bと前記位置Cとの間における任意の位置をY、
前記位置Aと前記位置Xとの間の長さをLAX、
前記位置Bと前記位置Yとの間の長さをLBY、
前記絶縁碍子の前記位置Xの部位における断面係数をZX、
前記絶縁碍子の前記位置Yの部位における断面係数をZY、
LAX/ZXが最大値をとるときの前記位置Xの位置をXmax、
LBY/ZYが最大値をとるときの前記位置Yの位置をYmax、
前記位置Aと前記位置Xmaxとの間の長さをLAXmax、
前記位置Bと前記位置Ymaxとの間の長さをLBYmax、
前記絶縁碍子の前記位置Xmaxの部位における断面係数をZXmax、
前記絶縁碍子の前記位置Ymaxの部位における断面係数をZYmax
とし、
τA=LAXmax/ZXmax、
τB=(LAC・LBYmax)/(LBC・ZYmax)
としたときに、
少なくともτAまたはτBのいずれか一方が0.47以上であると共に、
0.71≦τA/τB≦1.27を満たすスパークプラグ。 - 前記主体金具は前記工具係合部よりも先端側に、内燃機関への取り付けのためのねじ山が形成された取付ねじ部を備え、
当該取付ねじ部の前記ねじ山の呼び径がM10以下である請求項1または2に記載のスパークプラグ。 - 前記絶縁碍子の前記後端側胴部の外径がφ8.5mm以下である請求項1乃至3のいずれかに記載のスパークプラグ。
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CN2009801096352A CN101978564B (zh) | 2008-03-18 | 2009-03-17 | 火花塞 |
US12/933,192 US8143773B2 (en) | 2008-03-18 | 2009-03-17 | Spark plug |
EP09722380.4A EP2256882B1 (en) | 2008-03-18 | 2009-03-17 | Spark plug |
KR1020107020783A KR101525277B1 (ko) | 2008-03-18 | 2009-03-17 | 스파크 플러그 |
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JP (1) | JP4913765B2 (ja) |
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JP5492244B2 (ja) * | 2012-04-09 | 2014-05-14 | 日本特殊陶業株式会社 | 点火プラグ |
US8981634B2 (en) | 2012-05-09 | 2015-03-17 | Federal-Mogul Ignition Gmbh | Spark plug with increased mechanical strength |
WO2015053399A1 (ja) * | 2013-10-11 | 2015-04-16 | 日本特殊陶業株式会社 | スパークプラグ |
DE102019126831A1 (de) | 2018-10-11 | 2020-04-16 | Federal-Mogul Ignition Llc | Zündkerze |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2003168540A (ja) * | 2001-11-30 | 2003-06-13 | Ngk Spark Plug Co Ltd | スパークプラグ |
JP2003282218A (ja) * | 2002-01-17 | 2003-10-03 | Denso Corp | スパークプラグ |
JP2006100250A (ja) | 2004-08-31 | 2006-04-13 | Denso Corp | 内燃機関用のスパークプラグ及びこれを用いた点火装置 |
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US6407487B1 (en) * | 1998-02-27 | 2002-06-18 | Ngk Spark Plug Co., Ltd. | Spark plug, alumina insulator for spark plug, and method of manufacturing the same |
WO2004088698A2 (en) * | 2003-02-12 | 2004-10-14 | Advanced Lighting Technologies, Inc. | An improved plasma lamp and method |
JP2005129377A (ja) | 2003-10-24 | 2005-05-19 | Denso Corp | スパークプラグ |
CN100514778C (zh) * | 2004-08-31 | 2009-07-15 | 株式会社电装 | 火花塞 |
JP4191773B2 (ja) * | 2006-08-29 | 2008-12-03 | 日本特殊陶業株式会社 | スパークプラグ |
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JP2003168540A (ja) * | 2001-11-30 | 2003-06-13 | Ngk Spark Plug Co Ltd | スパークプラグ |
JP2003282218A (ja) * | 2002-01-17 | 2003-10-03 | Denso Corp | スパークプラグ |
JP2006100250A (ja) | 2004-08-31 | 2006-04-13 | Denso Corp | 内燃機関用のスパークプラグ及びこれを用いた点火装置 |
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EP2256882B1 (en) | 2020-04-29 |
EP2256882A1 (en) | 2010-12-01 |
CN101978564A (zh) | 2011-02-16 |
KR101525277B1 (ko) | 2015-06-02 |
JP4913765B2 (ja) | 2012-04-11 |
KR20100126400A (ko) | 2010-12-01 |
EP2256882A4 (en) | 2013-04-03 |
US8143773B2 (en) | 2012-03-27 |
US20110018422A1 (en) | 2011-01-27 |
CN101978564B (zh) | 2012-11-21 |
JP2009224268A (ja) | 2009-10-01 |
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