JP7202222B2

JP7202222B2 - spark plug

Info

Publication number: JP7202222B2
Application number: JP2019041596A
Authority: JP
Inventors: 直樹西尾; 祐介棚橋; 佑典川嶋
Original assignee: NGK Spark Plug Co Ltd
Current assignee: NGK Spark Plug Co Ltd
Priority date: 2019-03-07
Filing date: 2019-03-07
Publication date: 2023-01-11
Anticipated expiration: 2039-03-07
Also published as: CN112204834A; JP2020145099A; CN112204834B; WO2020179304A1; DE112020000095T5

Description

本発明は、点火プラグに関する。 The present invention relates to spark plugs.

内燃機関（エンジン）に用いられる点火プラグは、特許文献１で開示される点火プラグのように、軸線方向に延びる軸孔を有する筒状の絶縁体と、絶縁体の外周に設けられる筒状の主体金具とを備えた構成が一般的である。特許文献１で開示される点火プラグは、絶縁体の先端側に中心電極が配され、主体金具の先端側に接地電極が設けられ、中心電極と接地電極との間で火花放電が行われる。 A spark plug used in an internal combustion engine (engine), like the spark plug disclosed in Patent Document 1, has a cylindrical insulator having a shaft hole extending in the axial direction and a cylindrical insulator provided on the outer periphery of the insulator. A structure including a metal shell is common. The spark plug disclosed in Patent Document 1 has a center electrode disposed on the tip side of the insulator and a ground electrode on the tip side of the metallic shell, and spark discharge occurs between the center electrode and the ground electrode.

特許文献１の点火プラグは、主体金具の内周面において、内向きに突出した突出部（突部２１）が設けられ、絶縁体の外周面には、突出部に対向した段部（係止部１４）が設けられている。突出部（凸部２１）は、先端側に向けて内径寸法が小さくなる第１傾斜面（縮径部２１Ａの表面）を有し、段部（係止部１４）は、先端側に向けて外径寸法が小さくなる第２傾斜面（係止部１４の表面）を有している。第１傾斜面と第２傾斜面との間には、環状の金属製パッキン２２が装着され、主体金具と絶縁体との間の気密性が確保される。 In the ignition plug of Patent Document 1, an inwardly protruding portion (protrusion 21) is provided on the inner peripheral surface of the metal shell, and a stepped portion (locking portion) facing the protruding portion is provided on the outer peripheral surface of the insulator. 14) is provided. The protruding portion (convex portion 21) has a first inclined surface (the surface of the diameter-reduced portion 21A) whose inner diameter dimension decreases toward the tip side, and the stepped portion (locking portion 14) has a It has a second inclined surface (the surface of the engaging portion 14) with a smaller outer diameter. A ring-shaped metal packing 22 is mounted between the first inclined surface and the second inclined surface to ensure airtightness between the metallic shell and the insulator.

特開２０１４－１３５１８９号公報JP 2014-135189 A

近年、点火プラグの小型化・細径化がより一層求められている。点火プラグを小型化・細径化するためには主体金具の突出部や絶縁体の段部のサイズを抑え、上述の第１傾斜面や第２傾斜面の面積を削減することが望ましいといえる。しかし、単に、第１傾斜面や第２傾斜面の面積を削減するだけでは、その分、傾斜面とパッキンとの接触面積が低下し、十分なシール効果を発揮できなくなる懸念がある。 In recent years, there has been an increasing demand for smaller and thinner spark plugs. In order to reduce the size and diameter of the spark plug, it is desirable to reduce the size of the protruding portion of the metal shell and the stepped portion of the insulator, and reduce the areas of the above-described first and second inclined surfaces. . However, simply reducing the areas of the first inclined surface and the second inclined surface reduces the contact area between the inclined surface and the packing, and there is a concern that a sufficient sealing effect cannot be exhibited.

このような問題に対する対策としては、主体金具の突出部と絶縁体の段部とがパッキンを挟み込む力をより増大させ、パッキンをより変形させて密着性を高めることが考えられる。突出部や段部がパッキンを挟み込む力をより増大させると、パッキンがより強く圧縮されるため、パッキンの一部が第１傾斜面と第２傾斜面の間から後端側の隙間（主体金具の内周面と絶縁体の外周面の隙間）に逃げるように変形しやすくなる。その結果、第１傾斜面及び第２傾斜面の後端側でも、パッキンが主体金具や絶縁体に接触することになり、接触面積が増すことになる。 As a countermeasure against such a problem, it is conceivable to increase the force with which the protrusion of the metallic shell and the stepped portion of the insulator sandwich the packing, thereby deforming the packing to improve adhesion. If the protrusion or stepped portion increases the force with which the packing is sandwiched, the packing will be compressed more strongly, so that a part of the packing will form a gap between the first inclined surface and the second inclined surface on the rear end side (main metal fitting). gap between the inner peripheral surface of the insulator and the outer peripheral surface of the insulator). As a result, the packing comes into contact with the metal shell and the insulator even on the rear end sides of the first inclined surface and the second inclined surface, increasing the contact area.

しかし、パッキンが第１傾斜面と第２傾斜面の間から後端側の隙間（主体金具の内周面と絶縁体の外周面の間の隙間）に入り込んだ場合、この隙間に入り込んだパッキンから絶縁体に対して過剰な力が加わる懸念がある。特に、後端側の隙間に入り込んだパッキンの一部が主体金具の内周面からも絶縁体の外周面からも圧力を受ける構成であると、主体金具の内周面からパッキンに加えられた力がパッキンを介して絶縁体の外周面に加わってしまうことになる。このような事態が生じると、絶縁体の内周面がパッキンの一部によって非常に強い力で押され、絶縁体の割れ等を招く懸念があった。 However, if the packing enters the gap on the rear end side (the gap between the inner peripheral surface of the metal shell and the outer peripheral surface of the insulator) from between the first inclined surface and the second inclined surface, the packing There is a concern that excessive force is applied to the insulator from the In particular, if a portion of the packing that has entered the gap on the rear end side receives pressure from both the inner peripheral surface of the metal shell and the outer peripheral surface of the insulator, the packing is subjected to pressure from the inner peripheral surface of the metal shell. Force will be applied to the outer peripheral surface of the insulator through the packing. If such a situation occurs, the inner peripheral surface of the insulator is pushed by a part of the packing with a very strong force, and there is a concern that the insulator may crack or the like.

本発明は上述した課題の少なくとも一つを解決するためになされたものであって、パッキンから絶縁体に過剰な力が加わることを抑制し得る点火プラグを、気密性の低下を抑制し得る構成で実現することを目的とする。 SUMMARY OF THE INVENTION The present invention has been made to solve at least one of the above-described problems, and provides a spark plug capable of suppressing excessive force applied from a packing to an insulator, and a structure capable of suppressing a decrease in airtightness. It is intended to be realized by

本発明の一態様である点火プラグは、
軸線方向に延びる軸孔を有し、前記軸孔の先端側に中心電極が配される筒状の絶縁体と、
前記絶縁体の外周に設けられる筒状の主体金具と、
前記絶縁体と前記主体金具との間に装着されるパッキンと、
を備え、
前記主体金具は、先端側ほど内径が小さくなる第１傾斜面を備えるとともに径方向の内側に突出する突出部を有し、
前記絶縁体は、先端側ほど外径が小さくなる第２傾斜面を備えるとともに前記第２傾斜面が前記第１傾斜面と対向して配される段部を有し、
前記パッキンは、前記第１傾斜面と前記第２傾斜面とに接触して配される点火プラグであって、
前記パッキンは、前記絶縁体の外周面のうち前記第２傾斜面より後端側の部分に接触し、前記主体金具の内周面のうち前記第１傾斜面より後端側の部分から離れている。 A spark plug, which is one aspect of the present invention,
a tubular insulator having an axial hole extending in the axial direction and having a center electrode disposed on the tip side of the axial hole;
a tubular metal shell provided on the outer periphery of the insulator;
a packing mounted between the insulator and the metal shell;
with
The metallic shell has a projecting portion that has a first inclined surface with an inner diameter that decreases toward the distal end and that projects radially inward,
The insulator has a stepped portion having a second inclined surface with an outer diameter that decreases toward the tip end, and the second inclined surface is arranged to face the first inclined surface,
The packing is a spark plug disposed in contact with the first inclined surface and the second inclined surface,
The packing is in contact with a portion of the outer peripheral surface of the insulator on the rear end side of the second inclined surface, and away from a portion of the inner peripheral surface of the metal shell on the rear end side of the first inclined surface. there is

上記の点火プラグは、パッキンが、第１傾斜面及び第２傾斜面のみならず「絶縁体の外周面のうち第２傾斜面より後端側の部分」に接触するため、その分、パッキンの接触面積が増す。よって、点火プラグの小型化によって第１傾斜面や第２傾斜面のサイズが低減しても、気密性の低下は抑えられる。一方で、パッキンが、「主体金具の内周面のうち第１傾斜面より後端側の部分」から離れているため、第１傾斜面よりも後端側では、パッキンが主体金具の内周面から押す力を受けなくなる。よって、第１傾斜面よりも後端側では、パッキンが径方向内側に押されることを抑えることができ、パッキンを介して絶縁体に過剰な力が加わることを抑制することができる。よって、上記構成によれば、パッキンから絶縁体に過剰な力が加わることを抑制し得る点火プラグを、気密性の低下を抑制し得る構成で実現しうる。 In the spark plug described above, the packing contacts not only the first inclined surface and the second inclined surface, but also "a portion of the outer peripheral surface of the insulator on the rear end side of the second inclined surface". Increased contact area. Therefore, even if the sizes of the first inclined surface and the second inclined surface are reduced due to the miniaturization of the spark plug, the deterioration of airtightness can be suppressed. On the other hand, since the packing is away from "the portion of the inner peripheral surface of the metal shell on the rear end side of the first inclined surface", the packing is located on the inner peripheral side of the metal shell on the rear end side of the first inclined surface. It will not receive the force pushing from the surface. Therefore, on the rear end side of the first inclined surface, it is possible to prevent the packing from being pushed radially inward, and it is possible to prevent excessive force from being applied to the insulator via the packing. Therefore, according to the above configuration, it is possible to realize a spark plug capable of suppressing excessive force applied from the packing to the insulator with a configuration capable of suppressing a decrease in airtightness.

上記の点火プラグにおいて、軸線を通り軸線に沿った断面において、第１傾斜面に相当する直線を径方向外側に延長した直線と、第２傾斜面に相当する直線を径方向外側に延長した直線とが、交差する構成であってもよい。
このような構成によれば、パッキンが加圧によって変形する際に、第１傾斜面の先端と絶縁体の外周面との間の隙間（第２の隙間）よりも、第２傾斜面の後端と主体金具の内周面との間の隙間（第１の隙間）のほうにはみ出しやすくなる。 In the above spark plug, in a cross section along the axis passing through the axis, a straight line obtained by extending a straight line corresponding to the first inclined surface radially outward and a straight line obtained by extending a straight line corresponding to the second inclined surface radially outward may intersect with each other.
According to such a configuration, when the packing is deformed by pressurization, the gap (second gap) between the tip of the first inclined surface and the outer peripheral surface of the insulator is closer to the rear of the second inclined surface than the gap (second gap). It tends to protrude toward the gap (first gap) between the end and the inner peripheral surface of the metallic shell.

上記の点火プラグにおいて、絶縁体は、第２傾斜面の後端側に隣接するとともに一定の外径で軸線方向に続く第１外周面と、第２傾斜面の先端側に隣接するとともに一定の外径で軸線方向に続く第２外周面と、を有していてもよい。そして、主体金具は、第１傾斜面の後端側において第１外周面の周りに配置されるとともに一定の内径で軸線方向に続く第１内周面と、記第１傾斜面の先端側において第２外周面の周りに配置されるとともに一定の内径で軸線方向に続く第２内周面と、を有していてもよい。そして、第２内周面の後端と第２外周面との間隔が、第１外周面の先端と第１内周面との間隔よりも小さくなっていてもよい。
このような構成によれば、第２内周面の後端が第２外周面に近い位置まで及んでいるため、第１傾斜面の面積及び突出部の強度をより確保することができる。よって、突出部がパッキンから受ける面圧が高すぎることに起因する突出部の変形等を抑制することができる。 In the spark plug described above, the insulator includes a first outer peripheral surface adjacent to the rear end side of the second inclined surface and continuing in the axial direction with a constant outer diameter, and a first outer peripheral surface adjacent to the tip side of the second inclined surface and having a constant outer diameter. and a second outer circumferential surface that continues axially at the outer diameter. The metallic shell has a first inner peripheral surface arranged around the first outer peripheral surface on the rear end side of the first inclined surface and continuing in the axial direction with a constant inner diameter, and a front end side of the first inclined surface. a second inner peripheral surface disposed about the second outer peripheral surface and continuing axially with a constant inner diameter. The distance between the rear end of the second inner peripheral surface and the second outer peripheral surface may be smaller than the distance between the front end of the first outer peripheral surface and the first inner peripheral surface.
With such a configuration, the rear end of the second inner peripheral surface extends to a position close to the second outer peripheral surface, so that the area of the first inclined surface and the strength of the protruding portion can be further ensured. Therefore, it is possible to suppress deformation or the like of the protrusion due to excessively high surface pressure that the protrusion receives from the packing.

上記の点火プラグでは、主体金具の内周面において第１傾斜面の後端側に、径方向外側に全周に亘って窪んだ形状をなす窪み部が形成されていてもよい。そして、パッキンが、窪み部内における主体金具の内周面から離れた状態で窪み部に進入していてもよい。
このような構成によれば、パッキンが径方向内側に押されることをより効果的に抑えることができる。しかも、パッキンを第１傾斜面の後端に達する形で又は第１傾斜面の後端を跨ぐ形で接触させることができるため、パッキンと主体金具との接触面積をより大きくすることができる。 In the spark plug described above, a recessed portion having a shape recessed radially outward over the entire circumference may be formed on the inner peripheral surface of the metal shell on the rear end side of the first inclined surface. Then, the packing may enter the recess while being separated from the inner peripheral surface of the metal shell in the recess.
According to such a configuration, it is possible to more effectively prevent the packing from being pushed radially inward. Moreover, since the packing can be brought into contact with the rear end of the first inclined surface or straddle the rear end of the first inclined surface, the contact area between the packing and the metallic shell can be increased.

本発明によれば、パッキンから絶縁体に過剰な力が加わることを抑制し得る点火プラグを、気密性の低下を抑制し得る構成で実現する。 ADVANTAGE OF THE INVENTION According to this invention, the ignition plug which can control that excessive force is applied to an insulator from a packing is implement|achieved by the structure which can control the deterioration of airtightness.

図１は、第１実施形態の点火プラグを概略的に例示する部分断面図である。FIG. 1 is a partial cross-sectional view schematically illustrating the spark plug of the first embodiment. FIG. 図２は、図１の点火プラグの一部を拡大して示す拡大断面図であり、図１の一点鎖線Ｋにより囲んだ部分の断面に相当する断面図である。FIG. 2 is an enlarged cross-sectional view showing a part of the ignition plug in FIG. 1, and is a cross-sectional view corresponding to the cross-section of the portion surrounded by the dashed-dotted line K in FIG. 図３は、第２実施形態の点火プラグの一部を拡大して示す拡大断面図である。FIG. 3 is an enlarged cross-sectional view showing an enlarged part of the spark plug of the second embodiment.

＜第１実施形態＞
１．スパークプラグの全体構成
図１で示す第１実施形態の点火プラグ１は、図示しない内燃機関に取り付けられ、内燃機関の燃焼室内の燃焼ガスに着火するために用いられる。点火プラグ１は、絶縁体１０と、主体金具３０と、中心電極５０と、端子金具６０と、抵抗体６１とを備えている。本明細書では、点火プラグ１の軸線Ｘ（中心軸線）の方向を軸線方向とする。この軸線方向において、接地電極４２が設けられた側を先端側とし、それとは反対側（端子金具６０が絶縁体１０の外側に露出する側）を後端側とする。図１では、点火プラグ１の先端（前端）を符号Ｆで示し、点火プラグの後端を符号Ｒで示す。以下では、各構成部材において、図１の下側を先端側、上側を後端側として説明する。また、軸線方向を前後方向ともいい、先端側を前側、後端側を後ろ側ともいう。 <First Embodiment>
1. Overall Configuration of Spark Plug A spark plug 1 of the first embodiment shown in FIG. 1 is attached to an internal combustion engine (not shown) and used to ignite combustion gas in a combustion chamber of the internal combustion engine. The spark plug 1 includes an insulator 10 , a metal shell 30 , a center electrode 50 , a terminal metal fitting 60 and a resistor 61 . In this specification, the direction of the axis X (center axis) of the spark plug 1 is defined as the axial direction. In this axial direction, the side on which the ground electrode 42 is provided is the front end side, and the opposite side (the side where the terminal fitting 60 is exposed to the outside of the insulator 10) is the rear end side. In FIG. 1, the tip (front end) of the spark plug 1 is denoted by F, and the rear end of the spark plug is denoted by R. As shown in FIG. Below, in each component, the lower side of FIG. 1 will be described as the front end side, and the upper side will be described as the rear end side. The axial direction is also called the front-rear direction, the front end side is called the front side, and the rear end side is called the rear side.

絶縁体１０は、軸線方向に延びる軸孔１１を有する円筒状の部材である。絶縁体１０は、例えばアルミナ等の絶縁性セラミックス材料を焼成して形成されている。絶縁体１０は、主体金具３０の貫通孔３１に挿入された状態で、固定されている。絶縁体１０の先端は、主体金具３０の先端より先端側に突出する。絶縁体１０の後端は、主体金具３０の後端より後端側に突出する。 The insulator 10 is a cylindrical member having an axial hole 11 extending in the axial direction. The insulator 10 is formed by firing an insulating ceramic material such as alumina. The insulator 10 is fixed while being inserted into the through hole 31 of the metallic shell 30 . The tip of the insulator 10 protrudes further than the tip of the metallic shell 30 . The rear end of the insulator 10 protrudes rearward from the rear end of the metallic shell 30 .

絶縁体１０のうち中心電極５０を囲む部分には段部１３が設けられている。段部１３は、環状のパッキン１７を介して主体金具３０の突出部３５に係止される。段部１３には、先端側に向かって径寸法が小さくなるように傾斜した第２傾斜面２２が設けられている。 A step portion 13 is provided in a portion of the insulator 10 surrounding the center electrode 50 . The stepped portion 13 is locked to the projecting portion 35 of the metal shell 30 via an annular packing 17 . The stepped portion 13 is provided with a second inclined surface 22 that is inclined so that the diameter dimension decreases toward the distal end side.

絶縁体１０には、段部１３より先端側に脚部１２が設けられている。脚部１２は、点火プラグ１が内燃機関に取り付けられた状態において燃焼室に曝される部分であり、後述する先端側胴部１４よりも細く構成された部分である。 The insulator 10 is provided with a leg portion 12 on the tip side of the stepped portion 13 . The leg portion 12 is a portion that is exposed to the combustion chamber when the spark plug 1 is attached to the internal combustion engine, and is a portion that is thinner than a tip side body portion 14 described later.

絶縁体１０には、段部１３より後端側に先端側胴部１４が設けられている。先端側胴部１４は、段部１３の後端から鍔部１５の前端まで続くように配されるとともに一部が主体金具３０のねじ部３４の内側に配される部分である。先端側胴部１４の外周面は、軸線Ｘを中心とする円筒面である。先端側胴部１４の外径（外周面の径）は、段部１３の後端から鍔部１５の前端までの間の領域で一定であり、脚部１２の外径（外周面の径）より大きい。 The insulator 10 is provided with a tip-side trunk portion 14 on the rear end side of the stepped portion 13 . The tip-side body portion 14 is a portion that extends from the rear end of the stepped portion 13 to the front end of the collar portion 15 and is partially disposed inside the threaded portion 34 of the metallic shell 30 . The outer peripheral surface of the tip-side trunk portion 14 is a cylindrical surface centered on the axis X. As shown in FIG. The outer diameter (diameter of the outer peripheral surface) of the tip-side trunk portion 14 is constant in the region from the rear end of the stepped portion 13 to the front end of the collar portion 15, and the outer diameter (diameter of the outer peripheral surface) of the leg portion 12 is constant. greater than

絶縁体１０には、先端側胴部１４より後端側に鍔部１５が設けられている。鍔部１５は、絶縁体１０における軸線方向の略中央に位置し、先端側胴部１４及び後端側胴部１６よりも径方向外側に張り出した鍔状形態をなす。 The insulator 10 is provided with a collar portion 15 on the rear end side of the front end side trunk portion 14 . The collar portion 15 is positioned substantially in the center of the insulator 10 in the axial direction, and has a collar-like shape protruding radially outward from the front end side body portion 14 and the rear end side body portion 16 .

絶縁体１０には、鍔部１５よりも後端側に後端側胴部１６が設けられている。後端側胴部１６の外周面は、軸線Ｘを中心とする円筒面である。後端側胴部１６の外径（外周面の径）は、鍔部１５の後端から所定範囲に亘って一定である。鍔部１５の外径は、先端側胴部１４及び後端側胴部１６の外径より大きい。 The insulator 10 is provided with a rear end side body portion 16 on the rear end side of the flange portion 15 . The outer peripheral surface of the rear trunk portion 16 is a cylindrical surface centered on the axis X. As shown in FIG. The outer diameter (diameter of the outer peripheral surface) of the rear end side body portion 16 is constant over a predetermined range from the rear end of the collar portion 15 . The outer diameter of the collar portion 15 is larger than the outer diameters of the front end side body portion 14 and the rear end side body portion 16 .

主体金具３０は、導電性の金属材料（例えば低炭素鋼材）で形成されている。主体金具３０は、内燃機関のエンジンヘッドに点火プラグ１を固定するための金具である。主体金具３０は、軸線方向に貫通する貫通孔３１を有した円筒形状をなしている。主体金具３０は、絶縁体１０の外周に配され、加締めによって絶縁体１０に固定される。 The metal shell 30 is made of a conductive metal material (for example, low carbon steel). The metal shell 30 is a metal fitting for fixing the spark plug 1 to the engine head of the internal combustion engine. The metal shell 30 has a cylindrical shape with a through hole 31 passing therethrough in the axial direction. The metal shell 30 is arranged on the outer periphery of the insulator 10 and fixed to the insulator 10 by caulking.

主体金具３０は、主体金具３０をエンジンヘッドに取り付けるための工具（スパークプラグレンチ）に係合する工具係合部３２を備えている。工具係合部３２の外周面は、工具が係合する多角形状をなしている。工具係合部３２の後側には、薄肉の加締部３３が備えられている。加締部３３は、主体金具３０を絶縁体１０に加締める際に、絶縁体１０の後端側胴部１６に密着する。 The metal shell 30 has a tool engaging portion 32 that engages a tool (spark plug wrench) for mounting the metal shell 30 to the engine head. The outer peripheral surface of the tool engaging portion 32 has a polygonal shape with which the tool is engaged. A thin caulking portion 33 is provided on the rear side of the tool engaging portion 32 . The caulking portion 33 is in close contact with the rear-end side body portion 16 of the insulator 10 when the metal shell 30 is caulked to the insulator 10 .

主体金具３０は、内燃機関に設けられたねじ孔（図示しない雌ねじ部）に挿入しつつ固定するためのねじ部３４（雄ねじ部）を備えている。ねじ部３４の外周面にはねじ溝（雄ねじ溝）が形成されている。ねじ部３４の内周面には、周方向全体に亘って内側に突出するように突出部３５が形成されている。突出部３５は、絶縁体１０に設けられた段部１３とともにパッキン１７を挟み込むように機能する。なお、突出部３５付近の詳細は後述する。 The metal shell 30 has a threaded portion 34 (male threaded portion) for being inserted into and fixed to a threaded hole (female threaded portion, not shown) provided in the internal combustion engine. A thread groove (male thread groove) is formed on the outer peripheral surface of the threaded portion 34 . A protruding portion 35 is formed on the inner peripheral surface of the threaded portion 34 so as to protrude inward along the entire circumferential direction. The projecting portion 35 functions to sandwich the packing 17 together with the stepped portion 13 provided on the insulator 10 . Details of the vicinity of the projecting portion 35 will be described later.

主体金具３０は、ねじ部３４の後端側に、鍔状の座部３７を備えている。座部３７と工具係合部３２との間には、薄肉の圧縮変形部３８が設けられている。工具係合部３２及び加締部３３の内周面と、絶縁体１０の後端側胴部１６の外周面との間には、タルク（滑石）の粉末が充填される充填部３９が設けられている。充填部３９は、環状のシール部材（線パッキン）４１によって封止される。主体金具３０の座部３７から加締部３３にわたる部分は、内径が拡径する拡径部４３となっている。拡径部４３の内径は、座部３７において、先端側から後端側に向かって次第に大きくなる。拡径部４３の内側に絶縁体１０の鍔部１５の一部が入り込むように配されている。 The metal shell 30 has a flange-shaped seat portion 37 on the rear end side of the threaded portion 34 . A thin compression deformation portion 38 is provided between the seat portion 37 and the tool engaging portion 32 . A filling portion 39 filled with talc powder is provided between the inner peripheral surfaces of the tool engaging portion 32 and the crimping portion 33 and the outer peripheral surface of the rear end side trunk portion 16 of the insulator 10 . It is The filling portion 39 is sealed with an annular seal member (wire packing) 41 . A portion extending from the seat portion 37 of the metal shell 30 to the caulking portion 33 forms an enlarged diameter portion 43 having an enlarged inner diameter. The inner diameter of the expanded diameter portion 43 gradually increases from the front end side to the rear end side of the seat portion 37 . A portion of the collar portion 15 of the insulator 10 is arranged to enter inside the enlarged diameter portion 43 .

絶縁体１０は、主体金具３０の圧縮変形部３８の圧縮変形により、シール部材４１及びタルクを介して貫通孔３１内で先端側に押圧され、パッキン１７は第１傾斜面（突出部傾斜面）２１と第２傾斜面（段部傾斜面）２２とに密着する。このような構成により、燃焼室内のガスが主体金具３０と絶縁体１０の間の隙間を介して後端側に漏れることを防止する。 The insulator 10 is pressed forward in the through hole 31 via the sealing member 41 and talc due to the compressive deformation of the compressive deformation portion 38 of the metal shell 30, and the packing 17 forms the first inclined surface (protruding portion inclined surface). 21 and the second inclined surface (stepped inclined surface) 22 are in close contact with each other. Such a configuration prevents the gas in the combustion chamber from leaking to the rear end side through the gap between the metal shell 30 and the insulator 10 .

主体金具３０の先端には、例えば抵抗溶接によって接地電極４２が接合されている。接地電極４２と中心電極５０との間に、火花を発生される隙間である火花ギャップが形成される。 A ground electrode 42 is joined to the tip of the metallic shell 30 by resistance welding, for example. A spark gap is formed between the ground electrode 42 and the center electrode 50 to generate a spark.

中心電極５０は、耐腐食性及び耐熱性が高い金属、例えばニッケル（Ｎｉ）またはニッケルを主成分とする合金を用いて形成される。中心電極５０は、軸線方向に延びる棒状をなし、絶縁体１０の軸孔１１の先端側に配される。中心電極５０の先端は、絶縁体１０の先端より先端側に突出し、中心電極５０の後端は、先端側胴部１４の内部に位置している。 The center electrode 50 is made of a highly corrosion-resistant and heat-resistant metal such as nickel (Ni) or an alloy containing nickel as a main component. The center electrode 50 is rod-shaped and extends in the axial direction, and is disposed on the tip side of the shaft hole 11 of the insulator 10 . The tip of the center electrode 50 protrudes to the tip side from the tip of the insulator 10 , and the rear end of the center electrode 50 is positioned inside the tip-side trunk portion 14 .

端子金具６０は、導電性の金属材料（例えば、低炭素鋼）により形成されている。端子金具６０は、軸線方向に延びる棒状の部材であり、絶縁体１０の軸孔１１の後端側に配される。端子金具６０の後端部は、絶縁体１０より後端側に突出している。端子金具６０には、電源供給部材から火花放電を発生させるための高電圧が印加される。 The terminal fitting 60 is made of a conductive metal material (for example, low carbon steel). The terminal fitting 60 is a rod-shaped member extending in the axial direction and arranged on the rear end side of the shaft hole 11 of the insulator 10 . A rear end portion of the terminal fitting 60 protrudes rearward from the insulator 10 . A high voltage for generating spark discharge is applied to the terminal fitting 60 from a power supply member.

抵抗体６１は、軸孔１１内において中心電極５０と端子金具６０との間に配される。抵抗体６１は、例えば導電性材料と、ガラス粒子と、ガラス粒子以外のセラミック粒子とを含む組成物で形成されている。 The resistor 61 is arranged between the center electrode 50 and the terminal fitting 60 within the shaft hole 11 . The resistor 61 is made of a composition containing, for example, a conductive material, glass particles, and ceramic particles other than the glass particles.

軸孔１１のうち抵抗体６１と中心電極５０との間の隙間は、導電性の先端側シール部材６２によって埋められている。先端側シール部材６２は、中心電極５０及び抵抗体６１に接触し、中心電極５０と抵抗体６１とを離間している。先端側シール部材６２は、絶縁体１０と中心電極５０とを封着固定する部材である。 A gap between the resistor 61 and the center electrode 50 in the axial hole 11 is filled with a conductive distal end side sealing member 62 . The tip-side sealing member 62 is in contact with the center electrode 50 and the resistor 61 and separates the center electrode 50 and the resistor 61 . The tip-side sealing member 62 is a member that seals and fixes the insulator 10 and the center electrode 50 .

軸孔１１のうち抵抗体６１と端子金具６０との間は、導電性の後端側シール部材６３によって埋められている。後端側シール部材６３は、端子金具６０及び抵抗体６１に接触し、端子金具６０と抵抗体６１とを離間している。後端側シール部材６３は、絶縁体１０と端子金具６０とを封着固定する部材である。先端側シール部材６２及び後端側シール部材６３は、抵抗体６１を介して中心電極５０と端子金具６０とを電気的、物理的に接続している。先端側シール部材６２及び後端側シール部材６３は、導電性を有する材料、例えばガラス粒子と金属粒子とを含む組成物で形成されている。 The space between the resistor 61 and the terminal fitting 60 in the shaft hole 11 is filled with a conductive rear end side sealing member 63 . The rear end side seal member 63 is in contact with the terminal fitting 60 and the resistor 61 to separate the terminal fitting 60 and the resistor 61 . The rear end side sealing member 63 is a member that seals and fixes the insulator 10 and the terminal fitting 60 . The front end side sealing member 62 and the rear end side sealing member 63 electrically and physically connect the center electrode 50 and the terminal fitting 60 via the resistor 61 . The leading end side sealing member 62 and the trailing end side sealing member 63 are made of a conductive material such as a composition containing glass particles and metal particles.

２．パッキン付近の構成
次に、パッキン１７付近の構成を更に詳述する。
図２のように、パッキン１７は、絶縁体１０と主体金具３０との間に装着される部材であり、具体的には、パッキン１７は、第１傾斜面２１と第２傾斜面２２とに接触して配される。パッキン１７は、絶縁体１０の外周面のうち第２傾斜面２２より後端側の部分に接触し、主体金具３０の内周面のうち第１傾斜面２１より後端側の部分から離れている。なお、本明細書において、主体金具３０の内周面とは、主体金具３０の内壁面のうち軸線Ｘ側に面する内面を意味し、傾斜した状態で軸線Ｘ側に面していてもよい。但し、軸線Ｘ側に向いていない面は、「主体金具３０の内周面」には該当しない。 2. Configuration around Packing Next, the configuration around the packing 17 will be described in further detail.
As shown in FIG. 2, the packing 17 is a member mounted between the insulator 10 and the metal shell 30. Specifically, the packing 17 is provided between the first inclined surface 21 and the second inclined surface 22. Distributed in contact. The packing 17 contacts a portion of the outer peripheral surface of the insulator 10 on the rear end side of the second inclined surface 22 , and is separated from a portion of the inner peripheral surface of the metallic shell 30 on the rear end side of the first inclined surface 21 . there is In this specification, the inner peripheral surface of the metal shell 30 means the inner surface of the inner wall surface of the metal shell 30 that faces the axis X side, and may face the axis X side in an inclined state. . However, the surface not facing the axis X side does not correspond to the "inner peripheral surface of the metallic shell 30".

第１傾斜面２１は、先端側ほど内径が小さくなるように傾斜して構成された面であり、径方向内側に突出する突出部３５の後端部付近に構成された面である。第１傾斜面２１は、軸線Ｘの周りに環状に配置される面であり、軸線Ｘを通るいずれの方向で点火プラグ１を切断した切断面においても軸線Ｘに対する角度が一定角度となるように傾斜する面である。また、第１傾斜面２１は、軸線Ｘを通るいずれの方向で点火プラグ１を切断した切断面においても軸線Ｘと直交する仮想平面に対する角度θｓが一定角度となるように傾斜した面である。第１傾斜面２１は、周方向全体に亘ってパッキン１７を径方向内側且つ後方側に押すように作用する面である。なお、図２では、軸線Ｘと直交する仮想平面を符号Ｚ１で例示している。 The first inclined surface 21 is a surface that is inclined so that the inner diameter becomes smaller toward the tip side, and is a surface that is formed in the vicinity of the rear end portion of the protruding portion 35 that protrudes radially inward. The first inclined surface 21 is a surface that is annularly arranged around the axis X, and is arranged so that the angle with respect to the axis X is constant in any cross-sectional plane obtained by cutting the spark plug 1 in any direction passing through the axis X. It is a sloping surface. Further, the first inclined surface 21 is a surface inclined so that the angle θs with respect to a virtual plane perpendicular to the axis X is a constant angle even on a cut surface obtained by cutting the spark plug 1 in any direction passing through the axis X. The first inclined surface 21 is a surface that acts to push the packing 17 radially inward and rearward over the entire circumferential direction. In addition, in FIG. 2, the imaginary plane orthogonal to the axis line X is illustrated with the code|symbol Z1.

第２傾斜面２２は、先端側ほど外径が小さくなる傾斜して構成された面であり、段部１３において第１傾斜面２１と対向して配される面である。第２傾斜面２２は、軸線Ｘの周りに環状に配置される面であり、軸線Ｘを通るいずれの方向で点火プラグ１を切断した切断面においても軸線Ｘに対する角度が一定角度となるように傾斜する面である。また、第２傾斜面２２は、軸線Ｘを通るいずれの方向で点火プラグ１を切断した切断面においても軸線Ｘと直交する仮想平面に対する角度θｉが一定角度となるように傾斜した面である。第２傾斜面２２は、周方向全体に亘ってパッキン１７を径方向外側且つ前方側に押すように作用する面である。なお、図２では、軸線Ｘと直交する仮想平面を符号Ｚ２で例示している。 The second inclined surface 22 is a surface configured to be inclined such that the outer diameter becomes smaller toward the tip side, and is a surface arranged to face the first inclined surface 21 in the stepped portion 13 . The second inclined surface 22 is a surface that is annularly arranged around the axis X, and is arranged so that the angle with respect to the axis X is a constant angle in any cross-sectional plane obtained by cutting the spark plug 1 in any direction passing through the axis X. It is a sloping surface. Further, the second inclined surface 22 is a surface inclined so that the angle θi with respect to a virtual plane perpendicular to the axis X is a constant angle even when the spark plug 1 is cut in any direction passing through the axis X. The second inclined surface 22 is a surface that acts to push the packing 17 radially outward and forward along the entire circumferential direction. In addition, in FIG. 2, the imaginary plane orthogonal to the axis line X is illustrated with the code|symbol Z2.

本構成では、第１傾斜面２１の後端が、第２傾斜面２２の後端よりも径方向外側且つ先端側（前側）に位置し、第２傾斜面２２の先端（前端）よりも後端側（後ろ側）に位置している。更に、第１傾斜面２１の先端（前端）が、第２傾斜面２２の先端（前端）よりも径方向外側且つ先端側（前側）に位置している。 In this configuration, the rear end of the first inclined surface 21 is located radially outside and on the front end side (front side) of the rear end of the second inclined surface 22 and rearward of the front end (front end) of the second inclined surface 22 . It is located on the edge side (rear side). Furthermore, the tip (front end) of the first inclined surface 21 is located radially outside and on the tip side (front side) of the tip (front end) of the second inclined surface 22 .

図２の例では、絶縁体１０において第２傾斜面２２よりも後端側に第１外周面７１が設けられ、第２傾斜面２２よりも先端側に第２外周面７２が設けられ、パッキン１７は、第１外周面７１及び第２外周面７２のいずれにも接触する。一方で、主体金具３０において第１傾斜面２１よりも後端側に第１内周面９１が設けられ、パッキン１７は、第１内周面９１に接触しない配置となっている。 In the example of FIG. 2 , the insulator 10 is provided with a first outer peripheral surface 71 on the rear end side of the second inclined surface 22 , and a second outer peripheral surface 72 on the front end side of the second inclined surface 22 . 17 contacts both the first outer peripheral surface 71 and the second outer peripheral surface 72 . On the other hand, the metallic shell 30 is provided with the first inner peripheral surface 91 on the rear end side of the first inclined surface 21 , and the packing 17 is arranged so as not to contact the first inner peripheral surface 91 .

第１外周面７１は、第２傾斜面２２の後端側に隣接するとともに一定の外径で軸線方向に続く面である。第１外周面７１は、第２傾斜面２２の後端を先端位置として軸線方向（前後方向）の一定範囲（上述の拡径部４３の先端まで）に亘って一定の外径で続いている。第１外周面７１は、軸線Ｘを中心とする円筒面である。 The first outer peripheral surface 71 is a surface adjacent to the rear end side of the second inclined surface 22 and continuing in the axial direction with a constant outer diameter. The first outer peripheral surface 71 continues with a constant outer diameter over a certain range (to the tip of the enlarged diameter portion 43 described above) in the axial direction (front-rear direction) with the rear end of the second inclined surface 22 as the tip position. . The first outer peripheral surface 71 is a cylindrical surface centered on the axis X. As shown in FIG.

第２外周面７２は、第２傾斜面２２の先端側に隣接するとともに一定の外径で軸線方向に続く面である。第２外周面７２は、第２傾斜面２２の先端を後端位置として軸線方向（前後方方向）の一定範囲に亘って一定の外径で続いている。第２外周面７２は、軸線Ｘを中心とする円筒面である。 The second outer peripheral surface 72 is a surface adjacent to the tip side of the second inclined surface 22 and continuing in the axial direction with a constant outer diameter. The second outer peripheral surface 72 continues with a constant outer diameter over a certain range in the axial direction (front-rear direction) with the tip of the second inclined surface 22 being the rear end position. The second outer peripheral surface 72 is a cylindrical surface centered on the axis X. As shown in FIG.

第１内周面９１は、第１傾斜面２１の後端側において第１外周面７１の周りに配置されるとともに一定の内径で軸線方向に続く面である。第１内周面９１は、第１傾斜面２１の後端を先端位置として軸線方向（前後方向）の一定範囲に亘って一定の内径で続いている。第１内周面９１は、軸線Ｘを中心とする円筒面であり、第１内周面９１の先端（前端）は、第１外周面７１の先端（前端）よりも先端側（前側）に配置されている。 The first inner peripheral surface 91 is a surface that is arranged around the first outer peripheral surface 71 on the rear end side of the first inclined surface 21 and continues in the axial direction with a constant inner diameter. The first inner peripheral surface 91 continues with a constant inner diameter over a certain range in the axial direction (front-rear direction) with the rear end of the first inclined surface 21 being the leading end position. The first inner peripheral surface 91 is a cylindrical surface centered on the axis X, and the tip (front end) of the first inner peripheral surface 91 is located on the tip side (front side) of the tip (front end) of the first outer peripheral surface 71. are placed.

第２内周面９２は、第１傾斜面２１の先端側において第２外周面７２の周りに配置されるとともに一定の内径で軸線方向に続く面である。第２内周面９２は、第１傾斜面２１の先端を後端位置として軸線方向（前後方向）の一定範囲に亘って一定の内径で続いている。第２内周面９２は、軸線Ｘを中心とする円筒面であり、第２内周面９２の後端は、第２外周面７２の後端よりも先端側（前側）に配置されている。 The second inner peripheral surface 92 is a surface that is arranged around the second outer peripheral surface 72 on the distal end side of the first inclined surface 21 and continues in the axial direction with a constant inner diameter. The second inner peripheral surface 92 continues with a constant inner diameter over a certain range in the axial direction (front-rear direction) with the tip of the first inclined surface 21 being the rear end position. The second inner peripheral surface 92 is a cylindrical surface centered on the axis X, and the rear end of the second inner peripheral surface 92 is arranged on the front side (front side) of the rear end of the second outer peripheral surface 72. .

このような構成において、第２内周面９２の後端と第２外周面７２との間隔Ｈが、第１外周面７１の先端と第１内周面９１との間隔Ｇよりも小さくなっている。つまり、第２内周面９２の後端の位置で軸線Ｘと直交する方向に点火プラグ１を切断した切断面での第２内周面９２の内径と第２外周面７２の外径との差は、第１外周面７１の先端の位置で軸線Ｘと直交する方向に点火プラグ１を切断した切断面での第１内周面９１の内径（図２で示す内径Ａに相当）と第１外周面７１の外径（図２で示す外径Ｃに相当）との差よりも小さい。換言すれば、第１外周面７１の先端の位置で軸線Ｘと直交する方向に点火プラグ１を切断した切断面での第１内周面９１の内側の面積と第１外周面７１の内側の面積との差は、第２内周面９２の後端の位置で軸線Ｘと直交する方向に点火プラグ１を切断した切断面での第２内周面９２の内側の面積と第２外周面７２の内側の面積との差よりも大きい。よって、製造段階でパッキン１７が塑性変形する際に、第２内周面９２と第２外周面７２との間の隙間１０２よりも第１内周面９１と第１外周面７１との間の隙間１０１のほうへパッキン１７の一部が入り込みやすくなっている。 In such a configuration, the distance H between the rear end of the second inner peripheral surface 92 and the second outer peripheral surface 72 is smaller than the distance G between the front end of the first outer peripheral surface 71 and the first inner peripheral surface 91. there is That is, the difference between the inner diameter of the second inner peripheral surface 92 and the outer diameter of the second outer peripheral surface 72 at a cut surface obtained by cutting the spark plug 1 in a direction orthogonal to the axis X at the rear end of the second inner peripheral surface 92 is The difference is the inner diameter of the first inner peripheral surface 91 (corresponding to the inner diameter A shown in FIG. 2) of the first inner peripheral surface 91 (corresponding to the inner diameter A shown in FIG. 1 outer diameter (corresponding to the outer diameter C shown in FIG. 2). In other words, the area of the inner side of the first inner peripheral surface 91 and the inner area of the first outer peripheral surface 71 on the cut surface obtained by cutting the spark plug 1 in the direction orthogonal to the axis X at the position of the tip of the first outer peripheral surface 71 The difference between the area and the area is the inner area of the second inner peripheral surface 92 and the second outer peripheral surface on a cut surface obtained by cutting the spark plug 1 in the direction perpendicular to the axis X at the position of the rear end of the second inner peripheral surface 92 . greater than the difference with the inner area of 72 . Therefore, when the packing 17 is plastically deformed in the manufacturing stage, the gap between the first inner peripheral surface 91 and the first outer peripheral surface 71 is larger than the gap 102 between the second inner peripheral surface 92 and the second outer peripheral surface 72 . Part of the packing 17 can easily enter into the gap 101 .

図２のように、パッキン１７は、第１傾斜面２１に接する第１接触面８１、第２傾斜面２２に接する第２接触面８２、第１外周面７１に接する第３接触面８３、及び第２外周面７２に接する第４接触面８４を有している。第１接触面８１は、第１傾斜面２１の先端から後端近傍にわたっているが、第１傾斜面２１の後端からは離間している。第２接触面８２は、第２傾斜面２２の全体にわたっている。第３接触面８３は、第１外周面７１の先端から後端側の所定領域にわたっている。第４接触面８４は、第２外周面７２の後端から軸線方向において第１傾斜面２１の先端と等しい位置まで、もしくは第１傾斜面２１の先端より若干後端寄りの位置までわたっている。 As shown in FIG. 2, the packing 17 has a first contact surface 81 in contact with the first inclined surface 21, a second contact surface 82 in contact with the second inclined surface 22, a third contact surface 83 in contact with the first outer peripheral surface 71, and It has a fourth contact surface 84 that contacts the second outer peripheral surface 72 . The first contact surface 81 extends from the front end of the first inclined surface 21 to the vicinity of the rear end, but is separated from the rear end of the first inclined surface 21 . The second contact surface 82 extends over the entire second inclined surface 22 . The third contact surface 83 extends from the front end of the first outer peripheral surface 71 to a predetermined area on the rear end side. The fourth contact surface 84 extends from the rear end of the second outer peripheral surface 72 to a position equal to the tip of the first inclined surface 21 in the axial direction, or to a position slightly closer to the rear end than the tip of the first inclined surface 21 . .

次に、点火プラグ１の作用及び効果を例示する。
上記の点火プラグ１は、パッキン１７が、第１傾斜面２１及び第２傾斜面２２のみならず「絶縁体１０の外周面のうち第２傾斜面２２より後端側の部分」に接触するため、その分、パッキン１７の接触面積が増す。よって、点火プラグ１の小型化によって第１傾斜面２１や第２傾斜面２２のサイズが低減しても、気密性の低下は抑えられる。一方で、パッキン１７が、「主体金具３０の内周面のうち第１傾斜面２１より後端側の部分」から離れているため、第１傾斜面２１よりも後端側では、パッキン１７が主体金具３０の内周面から押す力を受けなくなる。よって、第１傾斜面２１よりも後端側では、パッキン１７が径方向内側に押されることを抑えることができ、パッキン１７を介して絶縁体１０に過剰な力が加わることを抑制することができる。よって、上記構成によれば、パッキン１７から絶縁体１０に過剰な力が加わることを抑制し得る点火プラグ１を、気密性の低下を抑制し得る構成で実現しうる。 Next, the action and effect of the spark plug 1 will be illustrated.
In the spark plug 1 described above, the packing 17 contacts not only the first inclined surface 21 and the second inclined surface 22 but also "a portion of the outer peripheral surface of the insulator 10 on the rear end side of the second inclined surface 22". , the contact area of the packing 17 increases accordingly. Therefore, even if the sizes of the first inclined surface 21 and the second inclined surface 22 are reduced due to the miniaturization of the spark plug 1, a decrease in airtightness can be suppressed. On the other hand, since the packing 17 is separated from "the portion of the inner peripheral surface of the metal shell 30 that is on the rear end side of the first inclined surface 21", the packing 17 is located on the rear end side of the first inclined surface 21. Pushing force from the inner peripheral surface of the metal shell 30 is no longer received. Therefore, on the rear end side of the first inclined surface 21 , it is possible to prevent the packing 17 from being pushed radially inward, and it is possible to prevent excessive force from being applied to the insulator 10 via the packing 17 . can. Therefore, according to the above configuration, it is possible to realize the spark plug 1 capable of suppressing the application of excessive force from the packing 17 to the insulator 10 with a configuration capable of suppressing deterioration of airtightness.

具体的には、図２のように、主体金具３０の第１内周面９１の内径Ａは、塑性変形後のパッキン１７のうち最も径方向の外側に位置する外周縁の径寸法（外径Ｂ）より大きくなっている。更に、パッキン１７の外径Ｂは、絶縁体１０の第１外周面７１の外径Ｃより大きくなっている。このようにすれば、パッキン１７の外縁の径（外径Ｂ）を絶縁体１０の第１外周面７１の外径Ｃより大きくして接触面積を確保しつつ、第１内周面９１の内径Ａよりも小さくして第１内周面９１に接触しない構成とすることができる。 Specifically, as shown in FIG. 2, the inner diameter A of the first inner peripheral surface 91 of the metal shell 30 is the diameter dimension (outer diameter B) is larger. Furthermore, the outer diameter B of the packing 17 is larger than the outer diameter C of the first outer peripheral surface 71 of the insulator 10 . In this way, the outer diameter (outer diameter B) of the outer edge of the packing 17 is made larger than the outer diameter C of the first outer peripheral surface 71 of the insulator 10 to secure the contact area, while the inner diameter of the first inner peripheral surface 91 is increased. It can be made smaller than A so that it does not come into contact with the first inner peripheral surface 91 .

上記の点火プラグ１は、図２のように、軸線Ｘを通り軸線Ｘに沿った断面において、第１傾斜面２１に相当する直線を径方向外側に延長した直線Ｌ１と、第２傾斜面２２に相当する直線を径方向外側に延長した直線Ｌ２とが、交差する構成となっている。このような関係は、軸線Ｘを通り軸線Ｘに沿ったいずれの方向の断面においても成立するものであり、図２はそのうちの一つの方向の断面について例示するものである。このような構成によれば、パッキン１７が加圧によって変形する際に、第１傾斜面２１の先端と絶縁体１０の外周面との間の隙間（第２の隙間）よりも、第２傾斜面２２の後端と主体金具３０の内周面との間の隙間（第１の隙間）のほうにはみ出しやすくなる。 As shown in FIG. 2, the spark plug 1 described above includes a straight line L1 obtained by extending a straight line corresponding to the first inclined surface 21 radially outward and a second inclined surface 22 in a cross section along the axis X through the axis X. A straight line L2 extending radially outward from a straight line corresponding to , intersects. Such a relationship is established in any cross-section passing through the axis X and along the axis X, and FIG. 2 illustrates a cross-section in one of these directions. According to such a configuration, when the packing 17 is deformed by pressurization, the gap (second gap) between the tip of the first inclined surface 21 and the outer peripheral surface of the insulator 10 is closer to the second inclined surface than the second inclined surface. The gap (first gap) between the rear end of the surface 22 and the inner peripheral surface of the metal shell 30 tends to protrude.

点火プラグ１において、角度θｉ（絶縁体１０の第２傾斜面２２と軸線方向と直交する仮想平面とのなす角度）は、２０～３０度の範囲が望ましい。第２傾斜面２２の角度θｉが２０度未満である場合、第２傾斜面２２に対して略直角方向に作用する圧力が過大になる虞がある。第２傾斜面２２の角度θｉが２０度以上であれば、そのような問題が生じにくい。 In the ignition plug 1, the angle θi (the angle between the second inclined surface 22 of the insulator 10 and the imaginary plane perpendicular to the axial direction) is desirably in the range of 20 to 30 degrees. If the angle θi of the second inclined surface 22 is less than 20 degrees, there is a possibility that the pressure acting on the second inclined surface 22 in a substantially perpendicular direction may become excessive. If the angle θi of the second inclined surface 22 is 20 degrees or more, such a problem is less likely to occur.

点火プラグ１において、角度θｓ（主体金具３０の第１傾斜面２１と軸線方向と直交する仮想平面とのなす角度）は、２０～３０度の範囲が望ましい。第１傾斜面２１の角度θｓが３０度以上である場合、主体金具３０の第１傾斜面２１におけるパッキン１７との接触面積が小さくなり、第１傾斜面２１に作用する応力が過大になって、突出部３５の変形を招く虞がある。第１傾斜面２１の角度θｓが３０度未満であれば、そのような問題が生じにくい。 In the spark plug 1, the angle θs (the angle between the first inclined surface 21 of the metallic shell 30 and the virtual plane perpendicular to the axial direction) is preferably in the range of 20 to 30 degrees. When the angle θs of the first inclined surface 21 is 30 degrees or more, the contact area between the first inclined surface 21 of the metal shell 30 and the packing 17 becomes small, and the stress acting on the first inclined surface 21 becomes excessive. , the protrusion 35 may be deformed. If the angle θs of the first inclined surface 21 is less than 30 degrees, such problems are less likely to occur.

第１傾斜面２１の角度θｓと第２傾斜面２２の角度θｉとの関係は、第１傾斜面２１の角度θｓが第２傾斜面２２の角度θｉより大きいような非平行の関係であることが望ましい。第１傾斜面２１の角度θｓが第２傾斜面２２の角度θｉより小さい場合、パッキン１７が径方向の外側に広がりやすい。第１傾斜面２１の角度θｓが第２傾斜面２２の角度θｉより大きければ、パッキン１７が径方向外側に広がりにくくなり、パッキン１７が第１内周面９１から離れた状態を実現しやすい。 The relationship between the angle θs of the first inclined surface 21 and the angle θi of the second inclined surface 22 is a non-parallel relationship such that the angle θs of the first inclined surface 21 is greater than the angle θi of the second inclined surface 22. is desirable. When the angle θs of the first inclined surface 21 is smaller than the angle θi of the second inclined surface 22, the packing 17 tends to expand radially outward. If the angle θs of the first inclined surface 21 is greater than the angle θi of the second inclined surface 22 , the packing 17 is less likely to expand radially outward, and the packing 17 is likely to be separated from the first inner peripheral surface 91 .

上記の点火プラグ１において、絶縁体１０は、第２傾斜面２２の後端側に隣接するとともに一定の内径で軸線方向に続く第１外周面７１と、第２傾斜面２２の先端側に隣接するとともに一定の内径で軸線方向に続く第２外周面７２と、を有する。そして、主体金具３０は、第１傾斜面２１の後端側において第１外周面７１の周りに配置されるとともに一定の内径で軸線方向に続く第１内周面９１と、第１傾斜面２１の先端側において第２外周面７２の周りに配置されるとともに一定の内径で軸線方向に続く第２内周面９２と、を有する。そして、第２内周面９２の後端と第２外周面７２との間隔Ｈが、第１外周面７１の先端と第１内周面９１との間隔Ｇよりも小さくなっている。このような構成によれば、第２内周面９２の後端が第２外周面７２に近い位置まで及んでいるため、第１傾斜面２１の面積及び突出部３５の強度をより確保することができる。よって、突出部３５がパッキン１７から受ける面圧が高すぎることに起因する突出部３５の変形等を抑制することができる。 In the spark plug 1 described above, the insulator 10 is adjacent to the rear end side of the second inclined surface 22 and adjacent to the first outer peripheral surface 71 that continues in the axial direction with a constant inner diameter, and to the tip end side of the second inclined surface 22 . and a second outer peripheral surface 72 that continues axially with a constant inner diameter. The metallic shell 30 is arranged around the first outer peripheral surface 71 on the rear end side of the first inclined surface 21 and continues in the axial direction with a constant inner diameter. a second inner peripheral surface 92 disposed around the second outer peripheral surface 72 at the distal end thereof and continuing axially with a constant inner diameter. The distance H between the rear end of the second inner peripheral surface 92 and the second outer peripheral surface 72 is smaller than the distance G between the front end of the first outer peripheral surface 71 and the first inner peripheral surface 91 . According to such a configuration, since the rear end of the second inner peripheral surface 92 extends to a position close to the second outer peripheral surface 72, the area of the first inclined surface 21 and the strength of the projecting portion 35 can be further secured. can be done. Therefore, deformation or the like of the protrusion 35 due to excessively high surface pressure that the protrusion 35 receives from the packing 17 can be suppressed.

＜第２実施形態＞
次に、第２実施形態に係る点火プラグ２０１について、主に図３を参照して説明する。 <Second embodiment>
Next, a spark plug 201 according to a second embodiment will be described mainly with reference to FIG.

本実施形態の点火プラグ２０１は、主体金具３０の内周面に窪み部２１０が形成されている点、及び窪み部２１０に入り込むようにパッキン１７が形成されている点以外は第１実施形態の点火プラグ１と同様である。よって、第１実施形態と同様の構成には同一符号を付して重複する説明を省略する。例えば、図１の構成のうち領域Ｋで示す内部構造以外は図１で示す点火プラグ１と同一である。よって、以下の説明では、図３の領域以外の説明については適宜図１を参照することとする。 The ignition plug 201 of this embodiment is the same as that of the first embodiment, except that a depression 210 is formed on the inner peripheral surface of the metallic shell 30 and that the packing 17 is formed so as to enter the depression 210. It is the same as the spark plug 1. Therefore, the same reference numerals are assigned to the same configurations as in the first embodiment, and overlapping descriptions are omitted. For example, the configuration shown in FIG. 1 is the same as the spark plug 1 shown in FIG. 1 except for the internal structure indicated by region K. Therefore, in the following description, FIG. 1 will be referred to as appropriate for descriptions other than the regions in FIG.

図３で示す点火プラグ２０１は、全体構成については図１で示す第１実施形態の構成と同様であり、絶縁体１０と、絶縁体１０の外周に設けられる筒状の主体金具３０とを有する。絶縁体１０は、軸線方向に延びる軸孔（軸孔１１と同様の構成）を有し、軸孔の先端側に中心電極（中心電極５０と同様の構成）が配される筒状のものである。主体金具３０は、径方向の内側に突出する突出部３５を有し、突出部３５には、先端側ほど内径が小さくなる第１傾斜面２１が設けられる。絶縁体１０は、段部１３を有し、段部１３には、先端側ほど外径が小さくなる第２傾斜面２２が設けられ、第２傾斜面２２が第１傾斜面２１と対向して配される。パッキン１７は、絶縁体１０と主体金具３０との間に装着され、主体金具３０の第１傾斜面２１と絶縁体１０の第２傾斜面２２とに接触して配される。更に、第１外周面７１及び第２外周面７２にも接触して配される。 A spark plug 201 shown in FIG. 3 has the same overall configuration as that of the first embodiment shown in FIG. . The insulator 10 is cylindrical and has an axial hole (structure similar to that of the shaft hole 11) extending in the axial direction, and a center electrode (structure similar to that of the center electrode 50) disposed on the tip side of the shaft hole. be. The metal shell 30 has a protruding portion 35 that protrudes radially inward, and the protruding portion 35 is provided with a first inclined surface 21 having an inner diameter that decreases toward the distal end. The insulator 10 has a stepped portion 13 , and the stepped portion 13 is provided with a second inclined surface 22 having a smaller outer diameter toward the tip side, and the second inclined surface 22 faces the first inclined surface 21 . distributed. The packing 17 is mounted between the insulator 10 and the metal shell 30 and arranged in contact with the first inclined surface 21 of the metal shell 30 and the second inclined surface 22 of the insulator 10 . Furthermore, it is arranged in contact with the first outer peripheral surface 71 and the second outer peripheral surface 72 as well.

本構成でも、パッキン１７は、絶縁体１０の外周面のうち第２傾斜面２２より後端側の部分に接触し、主体金具３０の内周面のうち第１傾斜面２１より後端側の部分から離れている。但し、本構成では、主体金具３０の内周面において第１傾斜面２１の後端側に窪み部２１０が形成され、窪み部２１０は、全周に亘って径方向外側に窪んだ形状をなす。パッキン１７は、窪み部２１０における主体金具３０の内周面（後述する第３面２１３）から離れた状態で窪み部２１０に進入している。 Also in this configuration, the packing 17 is in contact with the portion of the outer peripheral surface of the insulator 10 on the rear end side of the second inclined surface 22 , and the inner peripheral surface of the metal shell 30 on the rear end side of the first inclined surface 21 . away from the part. However, in this configuration, a recessed portion 210 is formed on the rear end side of the first inclined surface 21 on the inner peripheral surface of the metal shell 30, and the recessed portion 210 has a shape that is recessed radially outward over the entire circumference. . The packing 17 enters the recessed portion 210 while being separated from the inner peripheral surface (the third surface 213 described later) of the metal shell 30 in the recessed portion 210 .

窪み部２１０は、主体金具３０の全周にわたって周方向に連続した形態で形成されている。具体的には、軸線Ｘを通り軸線Ｘに沿ったいずれの方向の断面においても、径方向外側に向かって窪んだ形態で窪み部２１０が設けられ、上記いずれの方向の断面においても、窪み部２１０は図３のような形態をなす。窪み部２１０は、第１傾斜面２１の後端から径方向外側に広がる第１面２１１と、第１面２１１と軸線方向に対向する第２面２１２とを有している。軸線Ｘを通り軸線Ｘに沿ったいずれの方向の断面においても、第１面２１１は、軸線方向に略直交している。第１面２１１は、径方向の寸法（幅）Ｙａが全周に亘り一定の環状をなしている。第２面２１２は、第１面２１１と略平行をなしている。第２面２１２の径方向の寸法（幅）は、第１面２１１の径方向の寸法（幅）Ｙａと概ね等しい。第２面２１２の内周縁は、第１内周面９１の先端に連なっている。 The recessed portion 210 is formed in a form continuous in the circumferential direction over the entire circumference of the metallic shell 30 . Specifically, in any cross section along the axis X passing through the axis X, the recessed portion 210 is provided so as to be recessed radially outward. 210 has a form as shown in FIG. The recessed portion 210 has a first surface 211 that extends radially outward from the rear end of the first inclined surface 21 and a second surface 212 that axially faces the first surface 211 . The first surface 211 is substantially orthogonal to the axial direction in any cross section along the axial line X that passes through. The first surface 211 has an annular shape with a constant radial dimension (width) Ya over the entire circumference. The second surface 212 is substantially parallel to the first surface 211 . The radial dimension (width) of the second surface 212 is substantially equal to the radial dimension (width) Ya of the first surface 211 . The inner peripheral edge of the second surface 212 continues to the tip of the first inner peripheral surface 91 .

窪み部２１０は、第１面２１１の外周縁から第２面２１２の外周縁にわたる第３面２１３を有しており、この第３面２１３が「窪み部内における主体金具の内周面」の一例に相当する。第３面２１３は、軸線Ｘを中心とする円筒面であり、軸線方向の一定範囲に亘って内径が一定とされている。第３面２１３は、「主体金具３０の内壁面のうち軸線Ｘ側に面する内面」であり、「主体金具３０の内周面」の一例に相当する。一方、第１面２１１は、軸線Ｘ側に向いていない面であるため、「主体金具３０の内周面」には該当しない。 The recessed portion 210 has a third surface 213 extending from the outer peripheral edge of the first surface 211 to the outer peripheral edge of the second surface 212. The third surface 213 is an example of "the inner peripheral surface of the metal shell in the recessed portion." corresponds to The third surface 213 is a cylindrical surface centered on the axis X, and has a constant inner diameter over a certain range in the axial direction. The third surface 213 is "the inner surface of the inner wall surface of the metallic shell 30 facing the axis X side" and corresponds to an example of "the inner peripheral surface of the metallic shell 30". On the other hand, the first surface 211 does not correspond to the "inner peripheral surface of the metal shell 30" because it is a surface that does not face the axis X side.

パッキン１７は、周方向全周に亘って窪み部２１０に進入している。パッキン１７のうち第１傾斜面２１の後端より径方向の外側に進出した進出部分は、第１面２１１の外縁から離れており、第２面２１２及び第３面２１３からも離れている。上記進出部分の径方向の寸法（幅）Ｘａは、第１面２１１の径方向の寸法（幅）Ｙａより小さい。また、上記進出部分の軸線方向の大きさ（高さ）Ｘｂは、窪み部２１０の軸線方向の大きさ（高さ）Ｙｂより小さい。窪み部２１０の軸線方向の大きさ（高さ）Ｙｂは、第１面２１１と第２面２１２との軸線方向の距離に相当し、第１内周面９１の先端と第１傾斜面２１の後端との間の軸線方向の距離にも相当し、第３面２１３の軸線方向の大きさ（高さ）にも相当する。 The packing 17 enters the recessed portion 210 along the entire circumference. A portion of the packing 17 that extends radially outward from the rear end of the first inclined surface 21 is separated from the outer edge of the first surface 211 and is also separated from the second surface 212 and the third surface 213 . The radial dimension (width) Xa of the advancing portion is smaller than the radial dimension (width) Ya of the first surface 211 . Further, the axial size (height) Xb of the advancing portion is smaller than the axial size (height) Yb of the recessed portion 210 . The axial size (height) Yb of the recessed portion 210 corresponds to the axial distance between the first surface 211 and the second surface 212 , and the distance between the tip of the first inner peripheral surface 91 and the first inclined surface 21 . It also corresponds to the distance in the axial direction from the rear end, and also corresponds to the size (height) of the third surface 213 in the axial direction.

本実施形態の構成でも、第１実施形態と同様の効果が得られる。更に、本実施形態の構成によれば、パッキン１７が径方向内側に押されることをより効果的に抑えることができる。しかも、第１傾斜面２１の後端を跨ぐ形でパッキン１７を接触させることができるため、パッキン１７と主体金具３０との接触面積をより大きくすることができる。 The configuration of this embodiment also provides the same effects as those of the first embodiment. Furthermore, according to the configuration of the present embodiment, it is possible to more effectively prevent the packing 17 from being pushed radially inward. Moreover, since the packing 17 can be brought into contact with the rear end of the first inclined surface 21, the contact area between the packing 17 and the metal shell 30 can be increased.

なお、本実施形態の構成でも、軸線Ｘ（図１）を通り軸線Ｘに沿った断面おいて、第１傾斜面２１に相当する直線を径方向外側に延長した直線と、第２傾斜面２２に相当する直線を径方向外側に延長した直線とが、交差する。よって、この点に関し、第１実施形態と同様の効果が得られる。 Also in the configuration of the present embodiment, in a cross section along the axis X ( FIG. 1 ), a straight line obtained by extending a straight line corresponding to the first inclined surface 21 radially outward and the second inclined surface 22 and a straight line extending radially outward from the straight line corresponding to . Therefore, regarding this point, the same effect as in the first embodiment can be obtained.

＜他の実施形態＞
本発明は、本明細書の実施形態の各態様や変形例に限られるものではなく、その趣旨を逸脱しない範囲において種々の構成で実現できる。例えば、発明の概要の欄に記載した各形態中の技術的特徴に対応する実施形態、実施例、変形例中の技術的特徴は、先述の課題の一部又は全部を解決するために、あるいは、先述の効果の一部又は全部を達成するために、適宜、差し替えや、組み合わせを行うことができる。特に、上述した実施形態や後述する実施形態の様々な技術的特徴は、矛盾のない範囲であらゆる組み合わせが可能である。また、その技術的特徴が本明細書中に必須なものとして説明されていなければ、適宜、削除できる。変更例としては、例えば、以下のようなものが該当する。 <Other embodiments>
The present invention is not limited to each aspect or modification of the embodiments of this specification, and can be implemented in various configurations without departing from the scope of the invention. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each form described in the outline of the invention are used to solve some or all of the above problems, or In order to achieve some or all of the above effects, replacements and combinations can be made as appropriate. In particular, various technical features of the embodiments described above and the embodiments described later can be combined in any consistent manner. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate. Examples of modifications include the following.

上述した実施形態では、パッキン１７が隙間１０２に入り込んでいないが、パッキン１７は隙間１０２に入り込んでいてもよい。この場合、パッキン１７が第２内周面９２から離れて配置されるとともに第２外周面７２に接触して配置される構成とし、後端側と同様の効果を生じさせてもよい。 Although the packing 17 does not enter the gap 102 in the embodiment described above, the packing 17 may enter the gap 102 . In this case, the packing 17 may be arranged apart from the second inner peripheral surface 92 and in contact with the second outer peripheral surface 72 to produce the same effect as the rear end side.

上述した実施形態では、間隔Ｇが間隔Ｈより大きいが、間隔Ｇと間隔Ｈの関係は等しくてもよいし、間隔Ｈが間隔Ｇより大きくてもよい。 Although the interval G is larger than the interval H in the above-described embodiment, the interval G and the interval H may be equal, or the interval H may be larger than the interval G.

上述した実施形態では、第１外周面７１、第２外周面７２、第１内周面９１及び第２内周面９２は軸線Ｘに平行な構成（軸線Ｘを中心とする円筒面）となっているが、第１外周面、第２外周面、第１内周面及び第２内周面のいずれか１又は複数若しくは全てが軸線に対して傾斜したテーパ面とされていてもよい。 In the above-described embodiment, the first outer peripheral surface 71, the second outer peripheral surface 72, the first inner peripheral surface 91, and the second inner peripheral surface 92 are configured parallel to the axis X (cylindrical surfaces centered on the axis X). However, one or more or all of the first outer peripheral surface, the second outer peripheral surface, the first inner peripheral surface, and the second inner peripheral surface may be tapered surfaces that are inclined with respect to the axis.

第２実施形態では、窪み部２１０を例示したが、窪み部の形状は図３で例示した形状とは異なる形状であってもよい。例えば、窪み部２１０の第１面２１１と第２面２１２の関係は非平行であってもよいし、第１面２１１及び第２面２１２のいずれか又は両方が曲面であってもよい。 Although the recess 210 is illustrated in the second embodiment, the shape of the recess may be different from the shape illustrated in FIG. For example, the relationship between the first surface 211 and the second surface 212 of the recess 210 may be non-parallel, or one or both of the first surface 211 and the second surface 212 may be curved surfaces.

第２実施形態では、窪み部２１０は、主体金具３０の全周にわたって連続した形態で形成されているが、窪み部は主体金具３０の周方向に所定間隔をあけて複数個所に形成されていてもよい。 In the second embodiment, the depressions 210 are formed continuously over the entire circumference of the metal shell 30, but the depressions are formed at a plurality of locations on the metal shell 30 at predetermined intervals in the circumferential direction. good too.

１，２０１…点火プラグ
１０…絶縁体
１１…軸孔
１３…段部
１７…パッキン
２１…第１傾斜面
２２…第２傾斜面
３０…主体金具
３５…突出部
５０…中心電極
７１…第１外周面
７２…第２外周面
９１…第１内周面
９２…第２内周面
２１０…窪み部
Ｘ…軸線 DESCRIPTION OF SYMBOLS 1,201... Spark plug 10... Insulator 11... Shaft hole 13... Step part 17... Packing 21... First inclined surface 22... Second inclined surface 30... Metal shell 35... Protruding part 50... Center electrode 71... First outer periphery Surface 72... Second outer peripheral surface 91... First inner peripheral surface 92... Second inner peripheral surface 210... Recess X... Axis line

Claims

a tubular insulator having an axial hole extending in the axial direction and having a center electrode disposed on the tip side of the axial hole;
a tubular metal shell provided on the outer periphery of the insulator;
a packing mounted between the insulator and the metal shell;
with
The metallic shell has a projecting portion that has a first inclined surface with an inner diameter that decreases toward the distal end and that projects radially inward,
The insulator has a stepped portion having a second inclined surface with an outer diameter that decreases toward the tip end, and the second inclined surface is arranged to face the first inclined surface,
The packing is a spark plug disposed in contact with the first inclined surface and the second inclined surface,
The metal shell has a first inner peripheral surface on the rear end side of the first inclined surface,
The insulator has a first outer peripheral surface adjacent to the rear end side of the second inclined surface and continuing in the axial direction with a constant outer diameter,
The packing contacts the first outer peripheral surface of the outer peripheral surface of the insulator on the rear end side of the second inclined surface, and the inner peripheral surface of the metallic shell on the rear end side of the first inclined surface. a spark plug that is separated from the portion and does not contact the first inner peripheral surface .

In a cross section along the axis passing through the axis, a straight line obtained by extending a straight line corresponding to the first inclined surface radially outward and a straight line obtained by extending a straight line corresponding to the second inclined surface radially outward. , intersect.

The insulator has a second outer peripheral surface adjacent to the tip side of the second inclined surface and continuing in the axial direction with a constant outer diameter,
The metal shell is arranged around the first outer peripheral surface and has a constant inner diameter that continues in the axial direction, and the second outer peripheral surface on the tip end side of the first inclined surface. a second inner peripheral surface disposed therearound and continuing in the axial direction with a constant inner diameter;
3. The distance between the rear end of the second inner peripheral surface and the second outer peripheral surface is smaller than the distance between the tip of the first outer peripheral surface and the first inner peripheral surface. spark plug.

a tubular insulator having an axial hole extending in the axial direction and having a center electrode disposed on the tip side of the axial hole;
a tubular metal shell provided on the outer periphery of the insulator;
a packing mounted between the insulator and the metal shell;
with
The metallic shell has a projecting portion that has a first inclined surface with an inner diameter that decreases toward the distal end and that projects radially inward,
The insulator has a stepped portion having a second inclined surface with an outer diameter that decreases toward the tip end, and the second inclined surface is arranged to face the first inclined surface,
The packing is a spark plug disposed in contact with the first inclined surface and the second inclined surface,
The packing is in contact with a portion of the outer peripheral surface of the insulator on the rear end side of the second inclined surface, and away from a portion of the inner peripheral surface of the metal shell on the rear end side of the first inclined surface. cage,
A recessed portion having a shape recessed radially outward over the entire circumference is formed on the inner peripheral surface of the metal shell on the rear end side of the first inclined surface,
A spark plug in which the packing enters the recess while being separated from the inner peripheral surface of the metal shell in the recess.