JP2007080833A5

JP2007080833A5 -

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Publication number: JP2007080833A5
Application number: JP2006276963A
Authority: JP
Filing date: 2006-10-10
Publication date: 2007-05-24

Description

そして、その第一の構成においては、絶縁体の前端部分が主体金具の先端側開口部から突出して配置され、その主体金具の先端側開口端面に対応する位置における絶縁体の厚さをＣとしたときに、
Ｃ≧１．１ｍｍ；
となっており、
前記中心電極は、前記絶縁体から前記中心電極の先端部が突出して配置され、その突出側の絶縁体端面に対応する位置における前記中心電極の外径をＡとする一方、該中心電極の基端部が前記先端部よりも大径に形成されており、
また、前記絶縁体は、前端部が周方向の段部により縮径されて該段部が絶縁体側係合部とされ、前記主体金具に対し後方側開口部から挿入されるとともに、前記絶縁体側係合部が、前記取付ねじ部内において前記主体金具の内面から突出する金具側係合部とリング状のパッキンを介して係合するようになっており、前記中心電極の基端部の、前記パッキンの軸線方向前端内縁に対応する位置における外径をＡ’として、
Ａ’≧１．３Ａ；
となっていることを特徴とする。
第二の構成は、
前記絶縁体から前記中心電極の先端部が突出して配置され、その突出側の絶縁体端面に対応する位置における前記中心電極の外径をＡとしたときに、
Ｍ≦１２ｍｍ；
１．４ｍｍ≦Ａ≦１．９ｍｍ；
となっており、
前記中心電極は、前記絶縁体から前記中心電極の先端部が突出して配置され、その突出側の絶縁体端面に対応する位置における前記中心電極の外径をＡとする一方、該中心電極の基端部が前記先端部よりも大径に形成されており、
また、前記絶縁体は、前端部が周方向の段部により縮径されて該段部が絶縁体側係合部とされ、前記主体金具に対し後方側開口部から挿入されるとともに、前記絶縁体側係合部が、前記取付ねじ部内において前記主体金具の内面から突出する金具側係合部とリング状のパッキンを介して係合するようになっており、前記中心電極の基端部の、前記パッキンの軸線方向前端内縁に対応する位置における外径をＡ’として、
Ａ’≧１．３Ａ；
となっていることを特徴とする。
第三の構成は、
前記絶縁体は、前端部が周方向の段部により縮径されて該段部が絶縁体側係合部とされ、前記主体金具に対し後方側開口部から挿入されるとともに、前記絶縁体側係合部が、前記取付ねじ部内において前記主体金具の内面から突出する金具側係合部とリング状のパッキンを介して係合するようになっており、そのパッキンの軸線方向前端内縁に対応する絶縁体厚さをＧとして、
Ｍ≦１２ｍｍ；
Ｇ≧１．５ｍｍ；
となっており、
前記中心電極は、前記絶縁体から前記中心電極の先端部が突出して配置され、その突出側の絶縁体端面に対応する位置における前記中心電極の外径をＡとする一方、該中心電極の基端部が前記先端部よりも大径に形成されており、
また、前記絶縁体は、前端部が周方向の段部により縮径されて該段部が絶縁体側係合部とされ、前記主体金具に対し後方側開口部から挿入されるとともに、前記絶縁体側係合部が、前記取付ねじ部内において前記主体金具の内面から突出する金具側係合部とリング状のパッキンを介して係合するようになっており、前記中心電極の基端部の、前記パッキンの軸線方向前端内縁に対応する位置における外径をＡ’として、
Ａ’≧１．３Ａ；
となっていることを特徴とする。
第四の構成は、
前記絶縁体の前端部分は前記主体金具の先端側開口部から突出して配置され、その主体金具の内面と前記絶縁体外面との間には環状の隙間が形成されており、前記主体金具の先端側開口端面内縁における該隙間の幅をＥとして、
Ｍ≦１２ｍｍ；
Ｅ≧１．６ｍｍ；
となっていることを特徴とする。 In the first configuration, the front end portion of the insulator is disposed so as to protrude from the front end opening of the metal shell, and the thickness of the insulator at a position corresponding to the front end opening end surface of the metal shell is C. When
C ≧ 1.1 mm;
And
The center electrode is arranged such that the tip of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A, while the base of the center electrode is The end is formed with a larger diameter than the tip,
In addition, the insulator has a front end reduced in diameter by a step portion in the circumferential direction, the step portion serves as an insulator-side engagement portion, and is inserted into the metal shell from a rear opening, and the insulator side An engagement portion is adapted to engage with a fitting side engagement portion protruding from the inner surface of the metallic shell in the mounting screw portion via a ring-shaped packing, and the base end portion of the center electrode, The outer diameter at the position corresponding to the inner edge of the packing in the axial direction is A ′,
A ′ ≧ 1.3A;
It is characterized by becoming.
The second configuration is
When the tip of the center electrode protrudes from the insulator and is disposed, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A,
M ≦ 12 mm;
1.4 mm ≦ A ≦ 1.9 mm;
And
The center electrode is arranged such that the tip of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A, while the base of the center electrode is The end is formed with a larger diameter than the tip,
In addition, the insulator has a front end reduced in diameter by a step portion in the circumferential direction, the step portion serves as an insulator-side engagement portion, and is inserted into the metal shell from a rear opening, and the insulator side An engagement portion is adapted to engage with a fitting side engagement portion protruding from the inner surface of the metallic shell in the mounting screw portion via a ring-shaped packing, and the base end portion of the center electrode, The outer diameter at the position corresponding to the inner edge of the packing in the axial direction is A ′,
A ′ ≧ 1.3A;
It is characterized by becoming.
The third configuration is
The front end of the insulator is reduced in diameter by a step in the circumferential direction, and the step is used as an insulator-side engagement portion. The insulator is inserted into the metal shell from a rear opening, and the insulator-side engagement is performed. An insulator is adapted to engage with a fitting side engaging portion protruding from the inner surface of the metallic shell in the mounting screw portion via a ring-shaped packing, and corresponds to the inner edge of the packing in the axial direction front end The thickness is G,
M ≦ 12 mm;
G ≧ 1.5 mm;
And
The center electrode is arranged such that the tip of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A, while the base of the center electrode is The end is formed with a larger diameter than the tip,
In addition, the insulator has a front end reduced in diameter by a step portion in the circumferential direction, the step portion serves as an insulator-side engagement portion, and is inserted into the metal shell from a rear opening, and the insulator side An engagement portion is adapted to engage with a fitting side engagement portion protruding from the inner surface of the metallic shell in the mounting screw portion via a ring-shaped packing, and the base end portion of the center electrode, The outer diameter at the position corresponding to the inner edge of the packing in the axial direction is A ′,
A ′ ≧ 1.3A;
It is characterized by becoming.
The fourth configuration is
The front end portion of the insulator is disposed so as to protrude from the opening on the front end side of the metal shell, and an annular gap is formed between the inner surface of the metal shell and the outer surface of the insulator. E is the width of the gap at the inner edge of the side opening end surface.
M ≦ 12 mm;
E ≧ 1.6 mm;
It is characterized by becoming.

なお、上記Ａの値が１．４ｍｍ未満になると、中心電極の熱引きが悪くなり、発火部（高融点金属チップ）の耐消耗性の不足を招く場合がある。他方、Ａの値が２．０ｍｍを超えた場合には、主体金具と中心電極との間に確保できる絶縁体厚さＣあるいは隙間幅Ｅを確保するためのスペースが不足し、横飛び発生あるいは絶縁体の厚み減少による絶縁強度不足につながる場合がある。なお、Ａの値は、望ましくは１．４ｍｍ〜１．９ｍｍ、さらに望ましくは１．４〜１．８ｍｍとなっているのがよい。 If the value of A is less than 1.4 mm, the heat extraction of the center electrode is worsened, which may lead to insufficient wear resistance of the ignition part (refractory metal tip). On the other hand, when the value of A exceeds 2.0 mm, there is insufficient space for securing the insulator thickness C or gap width E that can be secured between the metal shell and the center electrode, It may lead to insufficient insulation strength due to a decrease in the thickness of the insulator. The value of A is desirably 1.4 mm to 1.9 mm , and more desirably 1.4 to 1.8 mm.

また、絶縁体は、前端部が周方向の段部により縮径されて該段部が絶縁体側係合部とされ、主体金具に対し後方側開口部から挿入されるとともに、絶縁体側係合部が、取付ねじ部内において主体金具の内面から突出する金具側係合部とリング状のパッキンを介して係合させることができる。そのパッキンの軸線方向前端内縁に対応する絶縁体厚さをＧとした場合、Ｇ≧１．５ｍｍとなっていることが望ましい。絶縁体は、一般にはパッキンとの係合部が段付面に形成され、パッキンの軸線方向前端内縁位置（以下、パッキン内縁位置という）は、この段付面形成により谷底となる部分において電界集中を受けやすい傾向にある。そして、絶縁体は、この段付面を境に先端側が縮径して薄肉となる構造を有しているので、電界集中しやすい上記部分は特に貫通破壊等を起こしやすくなる。そこで、上記のように、この部分における絶縁体厚さＧを１．５ｍｍ以上に確保することで、絶縁体の絶縁強度を効果的に高めることができる。

In addition, the insulator has a front end that is reduced in diameter by a step portion in the circumferential direction, and the step portion serves as an insulator-side engagement portion, and is inserted from the rear opening to the metal shell, and the insulator-side engagement portion However, it can be engaged with the metal fitting side engaging part which protrudes from the inner surface of the metallic shell in the mounting screw part via the ring-shaped packing. When the insulator thickness corresponding to the inner edge in the axial direction of the packing is G, it is desirable that G ≧ 1.5 mm . Insulators are generally formed on the stepped surface with the engaging part of the packing, and the axial front edge inner edge position of the packing (hereinafter referred to as packing inner edge position) is the electric field concentration at the bottom of the valley due to the stepped surface formation It tends to be susceptible. And since the insulator has a structure in which the tip side is reduced in diameter and becomes thin with this stepped surface as a boundary, the above-mentioned portion where the electric field is likely to concentrate is particularly likely to cause through breakdown. Therefore, as described above, the insulation strength of the insulator can be effectively increased by securing the insulator thickness G in this portion to 1.5 mm or more.

Claims

The center electrode is formed in the shape of a shaft, and a refractory metal chip mainly composed of Ir is fixed to the tip thereof, the shaft-shaped insulator covering the outside thereof, and the tube is formed in a cylindrical shape whose both ends are open. A metal shell disposed on the outside of the electrode, a base end side of which is coupled to the metal shell, and a tip side thereof is bent back sideways so that a side surface faces the refractory metal tip of the center electrode tip, and the high melting point A grounding electrode that forms a spark gap with the metal tip;
In the axial direction of the center electrode, the side where the spark gap is formed is the front side, and the opposite side is the rear side, and a mounting screw portion is formed on the outer peripheral surface of the front end side of the metal shell, and the mounting screw portion Let M be the outer diameter of
Further, the front end portion of the insulator is disposed so as to protrude from the front end opening of the metal shell, and when the thickness of the insulator at a position corresponding to the front end opening end surface of the metal shell is C,
M ≦ 12 mm;
C ≧ 1.1 mm;
It has become,
The center electrode is arranged such that the tip of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A, while the base of the center electrode is The end is formed with a larger diameter than the tip,
In addition, the insulator has a front end reduced in diameter by a step portion in the circumferential direction, the step portion serves as an insulator-side engagement portion, and is inserted into the metal shell from a rear opening, and the insulator side An engagement portion is adapted to engage with a fitting side engagement portion protruding from the inner surface of the metallic shell in the mounting screw portion via a ring-shaped packing, and the base end portion of the center electrode, The outer diameter at the position corresponding to the inner edge of the packing in the axial direction is A ′,
A ′ ≧ 1.3A;
Spark plug characterized by becoming .

The tip of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A, while the outer diameter of the refractory metal tip is B. As
1.4 mm ≦ A ≦ 2.0 mm;
0.4 mm ≦ B ≦ 1.0 mm;
The spark plug according to claim 1.

A center electrode formed with a shaft and having a high melting point metal chip mainly composed of a metal element whose main melting point is higher than Pt at the tip, a shaft-like insulator covering the outside, and both ends open. A metal fitting that is formed in a cylindrical shape and disposed outside the center electrode, and a refractory metal tip having a proximal end coupled to the metal fitting and a distal end bent back to the side so that the side surface is the distal end of the center electrode And a ground electrode that forms a spark gap with the refractory metal tip,
In the axial direction of the center electrode, the side where the spark gap is formed is the front side, and the opposite side is the rear side, and a mounting screw portion is formed on the outer peripheral surface of the front end side of the metal shell, and the mounting screw portion Let M be the outer diameter of
Further, when the tip end portion of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A,
M ≦ 12 mm;
1.4 mm ≦ A ≦ 1.9 mm;
It has become,
The center electrode is arranged such that the tip of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A, while the base of the center electrode is The end is formed with a larger diameter than the tip,
In addition, the insulator has a front end reduced in diameter by a step portion in the circumferential direction, the step portion serves as an insulator-side engagement portion, and is inserted into the metal shell from a rear opening, and the insulator side An engagement portion is adapted to engage with a fitting side engagement portion protruding from the inner surface of the metallic shell in the mounting screw portion via a ring-shaped packing, and the base end portion of the center electrode, The outer diameter at the position corresponding to the inner edge of the packing in the axial direction is A ′,
A ′ ≧ 1.3A;
Spark plug characterized by becoming .

The center electrode is formed in the shape of a shaft, and a refractory metal chip mainly composed of Ir is fixed to the tip thereof, the shaft-shaped insulator covering the outside thereof, and the tube is formed in a cylindrical shape whose both ends are open. A metal shell disposed on the outside of the electrode, a base end side of which is coupled to the metal shell, and a tip side thereof is bent back to the side so that the side surface faces the refractory metal tip at the tip of the center electrode. And a ground electrode that forms a spark gap between the
In the axial direction of the center electrode, the side where the spark gap is formed is the front side, and the opposite side is the rear side, and a mounting screw portion is formed on the outer peripheral surface of the front end side of the metal shell, and the mounting screw portion Let M be the outer diameter of
In addition, the insulator has a front end reduced in diameter by a step portion in the circumferential direction, the step portion serves as an insulator-side engagement portion, and is inserted into the metal shell from a rear opening, and the insulator side The engaging portion engages with the metal fitting engaging portion protruding from the inner surface of the metal shell through the ring-shaped packing in the mounting screw portion, and corresponds to the inner edge in the axial front end of the packing. The insulator thickness is G,
M ≦ 12 mm;
G ≧ 1.5 mm;
It has become,
The center electrode is arranged such that the tip of the center electrode protrudes from the insulator, and the outer diameter of the center electrode at a position corresponding to the insulator end surface on the protruding side is A, while the base of the center electrode is The end is formed with a larger diameter than the tip,
In addition, the insulator has a front end reduced in diameter by a step portion in the circumferential direction, the step portion serves as an insulator-side engagement portion, and is inserted into the metal shell from a rear opening, and the insulator side An engagement portion is adapted to engage with a fitting side engagement portion protruding from the inner surface of the metallic shell in the mounting screw portion via a ring-shaped packing, and the base end portion of the center electrode, The outer diameter at the position corresponding to the inner edge of the packing in the axial direction is A ′,
A ′ ≧ 1.3A;
Spark plug characterized by becoming .

The inner diameter dimension at the end opening end face of the metal shell is larger than 7.2 mm,
The front end portion of the insulator is disposed so as to protrude from the opening on the front end side of the metal shell, and an annular gap is formed between the inner surface of the metal shell and the outer surface of the insulator. The width of the gap at the inner edge of the side opening end face is E, the projected dimension of the insulator from the front end opening end face of the metal shell is F, and the spark gap interval is D,
0.8 mm ≦ D ≦ 1.4 mm;
E ≧ 1.3 mm;
1.0 mm ≦ F ≦ 4.0 mm;
The spark plug according to any one of claims 1 to 4.

The center electrode is formed in the shape of a shaft, and a refractory metal chip mainly composed of Ir is fixed to the tip thereof, the shaft-shaped insulator covering the outside thereof, and the tube is formed in a cylindrical shape whose both ends are open. A metal shell disposed on the outside of the electrode, a base end side of which is coupled to the metal shell, and a tip side thereof is bent back to the side so that the side surface faces the refractory metal tip at the tip of the center electrode. And a ground electrode that forms a spark gap between the
In the axial direction of the center electrode, the side where the spark gap is formed is the front side, and the opposite side is the rear side, and a mounting screw portion is formed on the outer peripheral surface of the front end side of the metal shell, and the mounting screw portion Let M be the outer diameter of
The front end portion of the insulator is disposed so as to protrude from the opening on the front end side of the metal shell, and an annular gap is formed between the inner surface of the metal shell and the outer surface of the insulator. The width of the gap at the inner edge of the opening side end face of
M ≦ 12 mm;
E ≧ 1.6 mm;
Spark plug characterized by becoming.

The spark plug according to any one of claims 1 to 6, wherein the refractory metal tip is mainly composed of Ir, W, Re, or Mo.

The spark plug according to claim 7, wherein the refractory metal tip is mainly composed of an Ir alloy containing Ir as a main component and one or more of Pt, Rh, Ru, Pd and Re added .

The refractory metal chip is based on the Ir alloy, and includes oxides, carbides, nitrides of one or more elements selected from Y, Zr, Si, La, W, Ni and Cr. one or spark plug of claim 8, wherein is obtained by mixing two or more borides.