JPH077690B2 - Spark plug for internal combustion engine - Google Patents
Spark plug for internal combustion engineInfo
- Publication number
- JPH077690B2 JPH077690B2 JP24237588A JP24237588A JPH077690B2 JP H077690 B2 JPH077690 B2 JP H077690B2 JP 24237588 A JP24237588 A JP 24237588A JP 24237588 A JP24237588 A JP 24237588A JP H077690 B2 JPH077690 B2 JP H077690B2
- Authority
- JP
- Japan
- Prior art keywords
- internal combustion
- combustion engine
- insulator
- intermediate electrode
- electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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- Spark Plugs (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） この発明は、内燃機関に使用されるスパークプラグに関
する。TECHNICAL FIELD The present invention relates to a spark plug used in an internal combustion engine.
（従来の技術） 従来、内燃機関に使用されるスパークプラグにおいて、
その絶縁体においては、アルミナによる焼結体が使用さ
れているものが一般的であるが、近年、絶縁体の急熱急
冷に伴う割れ等を防止するために、アルミナよりも耐熱
衝撃性が高い窒化ケイ素を絶縁体の材料として用いる、
例えば窒化ケイ素の焼結体よりなる絶縁体に高融点金属
又は炭化ケイ素の電極材を挿嵌した上、上記絶縁体及び
電極材を一体に焼結することによって強固に一体成形さ
せてなるもの（特開昭57−152689号、特開昭57−152690
号）や絶縁体を構成する成分である窒化ケイ素に含有さ
れる酸化鉄及び気泡率を制御することによって耐久性を
高めようとしてなるもの（特開昭58−123602号）があ
る。(Prior Art) Conventionally, in a spark plug used in an internal combustion engine,
As the insulator, a sintered body made of alumina is generally used, but in recent years, it has higher thermal shock resistance than alumina in order to prevent cracks and the like caused by rapid heating and quenching of the insulator. Using silicon nitride as the insulator material,
For example, a high melting point metal or silicon carbide electrode material is inserted into an insulator made of a sintered body of silicon nitride, and the insulator and the electrode material are integrally sintered to form a strong integral molding ( JP-A-57-152689, JP-A-57-152690
No.) and iron oxide contained in silicon nitride, which is a component of the insulator, and those which try to improve the durability by controlling the bubble ratio (JP-A-58-123602).
（発明が解決しようとする課題） しかしながら、上記従来のものにおいて、特開昭57−15
2689号及び特開昭57−152690号の場合、窒化ケイ素の焼
結体よりなる絶縁体に高融点金属又は炭化ケイ素の電極
材を使用するものであるが、電極材の高融点金属が非常
に高価であることから、その使用量はコストの面から限
定されてる上、中心電極を構成する導電性セラミック自
体が火花消耗に対する耐久力が低いことから、内燃機関
に損傷を与え易いものである。また、特開昭58−123602
号の場合には、絶縁体を構成する窒化ケイ素中に含まれ
る酸化鉄及び気泡によって生じる気孔の気孔率を抑制す
ることで、窒化ケイ素焼結体自体の有する耐電圧性能を
向上させ、その結果絶縁体貫通等を防止しようとするも
のであるが、窒化ケイ素焼結体に含まれる酸化鉄の含有
量や気孔率を抑制するだけでは、根本的に絶縁体貫通等
の障害を防ぐことはできないという欠点があった。そこ
で、この発明は上記従来のもののもつ欠点を改善するも
のであり、曲げ強度及び耐熱衝撃性に優れた窒化ケイ素
をスパークプラグの絶縁体に用いることができるように
するものである。(Problems to be Solved by the Invention) However, in the above-mentioned conventional one, the method disclosed in Japanese Patent Laid-Open No. 57-15
In the case of 2689 and JP-A-57-152690, a high melting point metal or a silicon carbide electrode material is used for an insulator made of a sintered body of silicon nitride, but the high melting point metal of the electrode material is very high. Since it is expensive, the amount used is limited in terms of cost, and since the conductive ceramic itself that constitutes the center electrode has low durability against spark consumption, it is likely to damage the internal combustion engine. In addition, JP-A-58-123602
In the case of No. 6, by suppressing the porosity of the pores generated by the iron oxide and bubbles contained in the silicon nitride forming the insulator, the withstand voltage performance of the silicon nitride sintered body itself is improved, and as a result, Although it is intended to prevent the penetration of the insulator, it is not possible to fundamentally prevent the obstacle such as the penetration of the insulator only by suppressing the content of iron oxide and the porosity contained in the silicon nitride sintered body. There was a drawback. Therefore, the present invention solves the above-mentioned drawbacks of the prior art, and makes it possible to use silicon nitride, which is excellent in bending strength and thermal shock resistance, as an insulator of a spark plug.
（課題を解決するための手段） そのために、融点が1850℃以上である貴金属からなり、
直径が1mm以下である貴金属ワイヤーの発火部電極を、
導電性セラミック焼結体からなる中間電極の先端に接合
した上、この中間電極を未焼成窒化ケイ素絶縁体の先端
側の軸孔に挿嵌し、一体に同時焼成し、さらには貴金属
ワイヤーと導電性セラミック焼結体からなる中間電極と
の接合部において、上記中間電極側に先端に向かって細
径となるテーパー部を設け、溶接によって一体に接合し
てなるものである。(Means for solving the problem) Therefore, a noble metal having a melting point of 1850 ° C. or higher,
Ignition electrode of precious metal wire with a diameter of 1 mm or less,
After joining to the tip of the intermediate electrode made of a conductive ceramic sintered body, this intermediate electrode is inserted into the shaft hole on the tip side of the unfired silicon nitride insulator, co-fired together, and the precious metal wire and conductive In the joint portion with the intermediate electrode made of a porous ceramic sintered body, a taper portion having a smaller diameter toward the tip is provided on the side of the intermediate electrode and integrally joined by welding.
（作用） 上記構成を具えるので、導電性セラミック焼結体からな
る中間電極の先端に接合する貴金属ワイヤーを直径1mm
以下とすることによって、火花消耗を最低限にしつつ放
電電圧を低く抑えることができ、このため絶縁体の貫通
破壊が防止できる。また、貴金属ワイヤーと導電性セラ
ミック焼結体からなる中間電極との接合部において、上
記中間電極側に先端に向かって細径となるテーパー部を
設けることによって、両者高融点であるために、接合す
る時に熱集中が起こり易くできて溶接が容易となるもの
である。(Operation) With the above configuration, the diameter of the noble metal wire to be joined to the tip of the intermediate electrode made of the conductive ceramic sintered body is 1 mm.
By setting the following, it is possible to suppress the discharge voltage to a low level while minimizing spark consumption, and thus to prevent breakthrough of the insulator. Further, in the joint portion between the noble metal wire and the intermediate electrode made of a conductive ceramic sintered body, a tapered portion having a smaller diameter toward the tip is provided on the intermediate electrode side, so that both have a high melting point, At the time of welding, heat concentration can easily occur and welding becomes easy.
（実施例） この発明を図に示す実施例により更に説明する。（１）
は、この発明の実施例である内燃機関用スパークプラグ
であり、この内燃機関用スパークプラグ（１）は、絶縁
体（２）、主体金具（３）と外側電極（８）より構成さ
れ、絶縁体（２）は窒化ケイ素を主成分とし、上記絶縁
体（２）の軸孔（14）には先端に融点が1850℃以上であ
る貴金属（例えばイリジウム、白金−イリジウム合金
等）からなり、直径が1mm以下である貴金属ワイヤーの
発火部電極（４）を接合する、更に二珪化モリブデン焼
結体等からなる導電性セラミック焼結体の中間電極
（５）を挿嵌、保持し、上記主体金具（３）には、内燃
機関に取り付けるためのネジ部（６）を外周に具え、ま
た、外側電極（８）は上記内燃機関用スパークプラグ
（１）の先端の開口部（７）において、発火部電極
（４）の方向に互いに直角となるように内方に突出して
なる複数の電極から構成されるものである。この中心電
極としては上記導電性セラミック焼結体からなる中間電
極（５）の先端に直径が1mm以下であるイリジウム等の
貴金属ワイヤーの発火部電極（４）を溶接によって接合
した後、これらをY2O3を焼結助剤として添加した窒化ケ
イ素をCIP成形法によって成形した未焼成絶縁体（２）
に内挿し、ガス圧焼結法によって一体に同時焼成してな
るものである。この同時焼成においては、100atm程度、
窒素雰囲気下、1800〜1900℃の条件で焼成を行うもので
ある。さらに、上記導電性セラミック焼結体よりなる中
間電極（５）と貴金属ワイヤーからなる発火部電極
（４）との接合部（９）において、中間電極（５）側に
先端に向かって細径となるようにテーパー部（10）を設
けることができ、こうすることにより、これに発火部電
極（４）を溶接するときに熱が集中し易くなり、溶接が
正確になると共に、その接合強度も向上するものであ
る。(Example) The present invention will be further described with reference to an example shown in the drawings. (1)
Is a spark plug for an internal combustion engine according to an embodiment of the present invention. The spark plug (1) for an internal combustion engine is composed of an insulator (2), a metal shell (3) and an outer electrode (8). The body (2) contains silicon nitride as a main component, and the shaft hole (14) of the insulator (2) is made of a noble metal (eg, iridium, platinum-iridium alloy) having a melting point of 1850 ° C. or more at the tip, and has a diameter of Is joined to the ignition part electrode (4) of a noble metal wire having a diameter of 1 mm or less, and further, an intermediate electrode (5) of a conductive ceramic sintered body made of a molybdenum disilicide sintered body or the like is inserted and held, and (3) is provided with a screw portion (6) for attaching to an internal combustion engine, and the outer electrode (8) is ignited at an opening (7) at the tip of the spark plug (1) for an internal combustion engine. They are perpendicular to each other in the direction of the partial electrodes (4) It is those composed of a plurality of electrodes formed by protruding inwardly. As the center electrode, an electrode (4) for igniting a precious metal wire such as iridium having a diameter of 1 mm or less is welded to the tip of the intermediate electrode (5) made of the above-mentioned conductive ceramic sintered body, and then these Unfired insulator formed by CIP molding of silicon nitride with 2 O 3 added as a sintering aid (2)
And is co-fired integrally by a gas pressure sintering method. In this simultaneous firing, about 100 atm,
In a nitrogen atmosphere, the firing is performed at 1800 to 1900 ° C. Further, in the joint portion (9) of the intermediate electrode (5) made of the above-mentioned conductive ceramic sintered body and the ignition part electrode (4) made of a noble metal wire, the diameter becomes smaller toward the tip toward the intermediate electrode (5) side. The tapered portion (10) can be provided so that heat is easily concentrated when the ignition portion electrode (4) is welded to the tapered portion (10), the welding is accurate, and the joint strength is also high. It will improve.
なお、（11）は、端子電極であり、ガラスシール材（1
2）及び抵抗体（13）と共に、絶縁体（２）内の軸孔（1
4）に加熱封着されるものである。In addition, (11) is a terminal electrode, and the glass sealing material (1
2) and resistor (13) together with shaft hole (1) in insulator (2)
It is heat-sealed to 4).
（発明の効果） 以上のとおり、導電性セラミック焼結体の中間電極先端
に細径の貴金属ワイヤーからなる発火部電極を接合する
と共に、絶縁体を一体焼結をするから、発火部電極の火
花消耗を低減させ、さらに放電電圧を低下させることに
よって、絶縁体の先端部において貫通の起こりにくい、
耐熱衝撃性に富んだスパークプラグとすることができそ
の上、中間電極の発火部電極との接合部をテーパー部と
することにより、接合強度を向上することができる等の
優れた効果を有するものである。(Effects of the Invention) As described above, since the ignition part electrode made of a noble metal wire having a small diameter is joined to the tip of the intermediate electrode of the conductive ceramic sintered body and the insulator is integrally sintered, the spark of the ignition part electrode is sparked. By reducing the consumption and further reducing the discharge voltage, penetration does not easily occur at the tip of the insulator,
A spark plug with excellent thermal shock resistance can be formed, and in addition, by forming a taper at the joint between the intermediate electrode and the ignition part electrode, it is possible to improve the joint strength and the like. Is.
第１図は、この発明の実施例である内燃機関用スパーク
プラグの部分断面図であり、第２図は、その要部拡大部
分断面図、第３図は、この発明の実施例である内燃機関
用スパークプラグの先端方向からの正面図である。 １……内燃機関用スパークプラグ、２……絶縁体、３…
…主体金具、４……発火部電極、５……中間電極、６…
…ネジ部、７……開口部、８……外側電極、９……接合
部、10……テーパー部、11……端子電極、12……ガラス
シール材、13……抵抗体、14……軸孔FIG. 1 is a partial sectional view of a spark plug for an internal combustion engine which is an embodiment of the present invention, FIG. 2 is an enlarged partial sectional view of an essential part thereof, and FIG. 3 is an internal combustion engine which is an embodiment of the present invention. It is a front view from the front end direction of the engine spark plug. 1 ... Spark plug for internal combustion engine, 2 ... Insulator, 3 ...
… Metal shell, 4 …… Ignition part electrode, 5 …… Intermediate electrode, 6…
… Screw part, 7 …… Opening part, 8 …… Outer electrode, 9 …… Joining part, 10 …… Taper part, 11 …… Terminal electrode, 12 …… Glass sealing material, 13 …… Resistance body, 14 …… Shaft hole
Claims (2)
直径が1mm以下である貴金属ワイヤーの発火部電極を、
導電性セラミック焼結体からなる中間電極の先端に接合
した上、この中間電極を未焼成窒化ケイ素の絶縁体の先
端側の軸孔に挿嵌し、一体に同時焼成してなる内燃機関
用スパークプラグ。1. A noble metal having a melting point of 1850 ° C. or higher,
Ignition electrode of precious metal wire with a diameter of 1 mm or less,
A spark for an internal combustion engine, which is formed by joining it to the tip of an intermediate electrode made of a conductive ceramic sintered body, inserting this intermediate electrode into a shaft hole on the tip side of the insulator of unfired silicon nitride, and co-firing together. plug.
間電極との接合部において、上記中間電極側に先端に向
って細径となるテーパー部を設けると共に、溶接によっ
て一体に接合してなる請求項（１）記載の内燃機関用ス
パークプラグ。2. A joining portion between a noble metal wire and an intermediate electrode made of a conductive sintered body is provided with a taper portion having a small diameter toward the tip on the intermediate electrode side and integrally joined by welding. A spark plug for an internal combustion engine according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24237588A JPH077690B2 (en) | 1988-09-29 | 1988-09-29 | Spark plug for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24237588A JPH077690B2 (en) | 1988-09-29 | 1988-09-29 | Spark plug for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0294274A JPH0294274A (en) | 1990-04-05 |
| JPH077690B2 true JPH077690B2 (en) | 1995-01-30 |
Family
ID=17088235
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24237588A Expired - Lifetime JPH077690B2 (en) | 1988-09-29 | 1988-09-29 | Spark plug for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH077690B2 (en) |
-
1988
- 1988-09-29 JP JP24237588A patent/JPH077690B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0294274A (en) | 1990-04-05 |
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