JPH10162931A - Spark plug - Google Patents
Spark plugInfo
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- JPH10162931A JPH10162931A JP33512296A JP33512296A JPH10162931A JP H10162931 A JPH10162931 A JP H10162931A JP 33512296 A JP33512296 A JP 33512296A JP 33512296 A JP33512296 A JP 33512296A JP H10162931 A JPH10162931 A JP H10162931A
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は内燃機関に使用され
るスパークプラグに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug used for an internal combustion engine.
【0002】[0002]
【従来の技術】従来、自動車エンジン等の内燃機関用の
スパークプラグとして、耐火花消耗性向上のために電極
の先端にPt(白金)合金のチップを溶接して発火部を
形成したものが使用されているが、白金は高価であるた
めチップ材料として安価なIr(イリジウム)を使用す
る提案がなされている。2. Description of the Related Art Conventionally, as a spark plug for an internal combustion engine such as an automobile engine, a spark plug formed by welding a Pt (platinum) alloy tip to the tip of an electrode to improve spark wear resistance has been used. However, since platinum is expensive, it has been proposed to use inexpensive Ir (iridium) as a chip material.
【0003】[0003]
【発明が解決しようとする課題】上述のプラグにおいて
チップをIrで構成した場合、Irは900〜1000
℃の高温域において酸化・揮発しやすい性質を有してい
るため、そのまま電極発火部に使用すると、火花消耗よ
りも酸化・揮発による消耗が問題となる欠点がある。従
って、市街地走行のような温度の低い条件であれば耐久
性はよいが、高速連続運転の場合には、耐久性が極端に
低下してしまう問題があった。一方、これとは別の問題
として、Irは常温及び高温のいずれにおいても延性あ
るいは展性に乏しいことから、発火部を形成するための
チップを鍛造、圧延あるいは打抜き等の加工により製造
しようとすると、材料歩留まりと製造能率が低下して量
産性が悪化する欠点がある。In the above-mentioned plug, when the chip is made of Ir, Ir is 900 to 1000.
Since it has the property of being easily oxidized and volatilized in a high temperature region of ° C., if it is used as it is in the electrode ignition portion, there is a disadvantage that consumption by oxidation and volatilization is more problematic than spark consumption. Therefore, durability is good under low temperature conditions such as running in an urban area, but there is a problem in that durability is extremely reduced in high-speed continuous operation. On the other hand, as another problem, since Ir has poor ductility or malleability at both room temperature and high temperature, it is necessary to manufacture a chip for forming a ignited portion by processing such as forging, rolling or punching. In addition, there is a disadvantage that the material yield and the production efficiency are reduced and mass productivity is deteriorated.
【0004】例えば、前述のチップの耐久性を改善する
ための一手段としては、適当な金属成分を合金に添加し
てIrの酸化・揮発による消耗を抑さえることが考えら
れるが、合金の加工性については必ずしも改善されなか
ったり、添加元素の種類によっては加工性が一層悪化す
ることもありうる。また、加工性の問題を回避するため
に、焼結法によりチップを製造する提案がなされている
が(例えば特開昭61−88479号公報)、焼結合金
製のチップは溶解合金製のチップに比べると耐久性に劣
る欠点がある。このように、Ir系のチップを使用した
プラグにおいて、チップの耐久性と量産性の双方に優れ
たものは未だ開発されておらず、該プラグの普及を妨げ
る大きな原因となっている。[0004] For example, as one means for improving the durability of the above-mentioned chip, it is conceivable to add a suitable metal component to the alloy to suppress the consumption of Ir by oxidation and volatilization. The workability is not necessarily improved, and the workability may be further deteriorated depending on the type of the added element. Further, in order to avoid the problem of workability, it has been proposed to manufacture chips by a sintering method (for example, Japanese Patent Application Laid-Open No. 61-88479). There is a drawback that the durability is inferior to the above. As described above, a plug using an Ir-based chip, which is excellent in both the durability and the mass productivity of the chip, has not been developed yet, and is a major factor hindering the spread of the plug.
【0005】本発明の課題は、Irを主体に構成されつ
つも、高温でのIr成分の酸化・揮発による消耗が起こ
りにくく、しかも加工性に優れた材料により発火部が構
成されたスパークプラグを提供することにある。An object of the present invention is to provide a spark plug which is mainly composed of Ir, is less likely to be consumed by oxidation and volatilization of an Ir component at a high temperature, and has an ignition portion made of a material having excellent workability. To provide.
【0006】[0006]
【課題を解決するための手段及び作用・効果】上述の課
題を解決するために本発明のスパークプラグは、中心電
極と、その中心電極の外側に設けられた絶縁体と、一方
の端部側から中心電極を突出させた状態で、絶縁体の外
側に設けられた主体金具と、その主体金具に一端が結合
され、他端側が中心電極と対向するように配置された接
地電極と、それら中心電極と接地電極との少なくとも一
方に固着されて火花放電ギャップを形成する発火部とを
備え、その発火部が、Irを主体としてRhを3〜4
9.5重量%の範囲で含有し、さらにWを0.5〜12
重量%の範囲で含有した合金により構成されたことを特
徴とする。In order to solve the above-mentioned problems, a spark plug according to the present invention comprises a center electrode, an insulator provided outside the center electrode, and one end side. A metal shell provided outside the insulator with the center electrode protruding from the insulator, a ground electrode having one end coupled to the metal shell and the other end facing the center electrode; A spark portion that is fixed to at least one of the electrode and the ground electrode to form a spark discharge gap;
9.5% by weight, and W is 0.5 to 12%.
It is characterized by being constituted by an alloy contained in the range of weight%.
【0007】本発明者は、火花放電ギャップを形成する
発火部を、Irを主体として上記範囲のRhを含有する
合金により構成することで、高温でのIr成分の酸化・
揮発による消耗が効果的に抑制されるとともに、合金が
さらに上記範囲のWを含有することにより、その加工性
が劇的に改善されることを見い出したのである。これに
より、Ir系金属で発火部を構成した従来のスパークプ
ラグの問題点がことごとく解決され、ひいては発火部の
構成材料としてIrを主成分とする金属を使用しつつ
も、その耐久性(特に高速走行時の耐久性)と量産性の
双方に優れたスパークプラグを実現することができる。The present inventor has proposed that the ignition portion forming the spark discharge gap is made of an alloy mainly containing Ir and containing Rh in the above range, so that the oxidation of the Ir component at a high temperature can be achieved.
It has been found that the wear due to volatilization is effectively suppressed and the workability of the alloy is dramatically improved by further containing W in the above range. This solves all the problems of the conventional spark plug in which the ignition portion is made of an Ir-based metal, and furthermore, its durability (particularly high speed) while using a metal mainly composed of Ir as a constituent material of the ignition portion. It is possible to realize a spark plug that is excellent in both durability during running) and mass productivity.
【0008】なお、上記発火部は、表記組成の金属から
なるチップを、接地電極及び/又は中心電極に対し溶接
により接合して形成することができる。この場合、本明
細書でいう「発火部」とは、接合されたチップのうち、
溶接による組成変動の影響を受けていない部分(例え
ば、溶接により接地電極ないし中心電極の材料と合金化
した部分を除く残余の部分)を指すものとする。The ignition portion can be formed by joining a tip made of a metal having the above composition to a ground electrode and / or a center electrode by welding. In this case, the “ignition portion” in this specification refers to
It refers to a portion that is not affected by the composition change due to welding (for example, a remaining portion excluding a portion alloyed with the material of the ground electrode or the center electrode by welding).
【0009】この場合、チップは、原料を所定の組成と
なるように配合・溶解して得られる溶解合金に対し所定
の加工を施して得られる加工材で構成することができ
る。なお、ここでいう「加工」とは、圧延、鍛造、引き
抜き、切削、切断及び打抜きの少なくともいずれかの工
程を含んで行われるものを意味するものとする。この場
合、圧延、鍛造、あるいは打抜き等の加工は、合金を所
定の温度に昇温して行ういわゆる熱間加工(あるいは温
間加工)により行うことができる。その加工温度は合金
組成にもよるが、例えば700℃以上とするのがよい。
本発明のスパークプラグにおけるチップ材質において
は、とりわけ熱間打抜き加工に対する特性が良好であ
り、例えば溶解合金を熱間圧延により板状に加工し、さ
らにその板材を熱間打抜き加工により所定の形状に打ち
抜いてチップを形成するようにすれば、チップの製造効
率が著しく改善され、チップの製造単価を大幅に低減す
ることができる。なお、溶解合金を熱間圧延又は熱間鍛
造により線状あるいはロッド状に加工した後、これを長
さ方向に所定長に切断してチップを形成する方法も可能
である。In this case, the chip can be formed of a processed material obtained by subjecting a molten alloy obtained by mixing and melting the raw materials to a predetermined composition to a predetermined processing. Here, “processing” means a process including at least one of rolling, forging, drawing, cutting, cutting, and punching. In this case, processing such as rolling, forging, or punching can be performed by so-called hot working (or warm working) performed by raising the temperature of the alloy to a predetermined temperature. The processing temperature depends on the alloy composition, but is preferably, for example, 700 ° C. or higher.
The chip material in the spark plug of the present invention has particularly good properties for hot stamping, for example, a molten alloy is processed into a plate by hot rolling, and the plate is formed into a predetermined shape by hot stamping. If a chip is formed by punching, the chip manufacturing efficiency is significantly improved, and the chip manufacturing cost can be significantly reduced. Note that a method is also possible in which a molten alloy is worked into a linear shape or a rod shape by hot rolling or hot forging, and then cut into a predetermined length in a length direction to form a chip.
【0010】合金中のWの含有量が0.5重量%未満に
なると、合金の加工性改善効果が十分に達成できなくな
り、例えば加工中に割れやクラックなどが生じやすくな
って、チップを製造する際の材料歩留まりの低下につな
がる。また、熱間打抜き加工等によりチップを製造する
場合は、打抜き刃等の工具の消耗あるいは損傷が生じや
すくなり、製造効率が低下する。一方、12重量%を超
えると加工性は却って悪化し、同様に材料歩留まりの低
下や製造効率の悪化につながる。それ故、Rhの含有量
は前述の範囲で調整するのがよく、望ましくは2〜9重
量%の範囲で調整するのがよい。なお、最適のW含有量
はRhの含有量によって変化し、Rh含有量が18重量
%未満ではW含有量は1.5〜9.5重量%とするのが
よく、また、Rh含有量が18〜23重量%ではW含有
量は0.5〜9.5重量%とするのがよく、さらにRh
含有量が23重量%以上の場合はW含有量は0.5〜1
2重量%とするのがよい。If the content of W in the alloy is less than 0.5% by weight, the effect of improving the workability of the alloy cannot be sufficiently achieved, and for example, cracks and cracks are liable to occur during the processing, and the chip is manufactured. This leads to a decrease in the material yield when performing. Further, when chips are manufactured by hot punching or the like, tools such as punching blades are liable to be worn or damaged, and the manufacturing efficiency is reduced. On the other hand, when the content exceeds 12% by weight, the workability is rather deteriorated, which also leads to a decrease in material yield and a decrease in manufacturing efficiency. Therefore, the content of Rh is preferably adjusted in the above-mentioned range, and more preferably in the range of 2 to 9% by weight. The optimum W content varies depending on the Rh content. When the Rh content is less than 18% by weight, the W content is preferably set to 1.5 to 9.5% by weight. When the content is 18 to 23% by weight, the W content is preferably 0.5 to 9.5% by weight.
When the content is 23% by weight or more, the W content is 0.5 to 1%.
The content is preferably 2% by weight.
【0011】次に、合金中のRhの含有量が3重量%未
満になるとIrの酸化・揮発の抑制効果が不十分とな
り、チップが消耗しやすくなるためプラグの耐久性が低
下する。この場合、チップの消耗が起きる場所として
は、チップの先端面部分が第一に挙げられるが、Rh含
有量が減少するとチップの側面部でも消耗が進行するこ
とがある。このような状況になると、火花放電のための
チップの通電断面積が減少する結果、チップの先端面部
に電界が集中しやすくなり、消耗が加速度的に進行して
プラグの寿命が急速に尽きてしまうことにもつながる。
従って、Rhの含有量の調整は、チップの先端面部だけ
でなく、側面部における消耗もなるべく生じにくい範囲
を選定することが望ましいといえる。一方、Rhの含有
量が49.5重量%を超えると合金の融点が低下し、プ
ラグの耐久性が同様に低下する。以上のことから、Rh
の含有量は前述の範囲で調整するのがよく、望ましくは
7〜30重量%、より望ましくは15〜25重量%、最
も望ましくは18〜22重量%の範囲で調整するのがよ
い。Next, when the content of Rh in the alloy is less than 3% by weight, the effect of suppressing the oxidation and volatilization of Ir becomes insufficient, and the chip is easily consumed, so that the durability of the plug is reduced. In this case, the tip of the tip is the first place where the chip is consumed. However, if the Rh content is reduced, the tip may be consumed on the side face. In such a situation, as a result of a decrease in the current-carrying cross-sectional area of the chip for spark discharge, an electric field tends to concentrate on the tip end portion of the chip, and the consumption progresses at an accelerated rate, and the life of the plug is rapidly exhausted. It also leads to getting lost.
Therefore, it can be said that it is desirable to adjust the Rh content not only in the tip surface portion of the chip but also in a range in which wear on the side surface portion is less likely to occur. On the other hand, if the Rh content exceeds 49.5% by weight, the melting point of the alloy decreases, and the durability of the plug similarly decreases. From the above, Rh
Is preferably adjusted within the above-mentioned range, preferably from 7 to 30% by weight, more preferably from 15 to 25% by weight, and most preferably from 18 to 22% by weight.
【0012】[0012]
【発明の実施の形態】以下、本発明のいくつかの実施の
形態を図面を用いて説明する。図1に示す本発明の一例
たるスパークプラグ100は、筒状の主体金具1、先端
部21が突出するようにその主体金具1の内側に嵌め込
まれた絶縁体2、先端に形成された発火部31を突出さ
せた状態で絶縁体2の内側に設けられた中心電極3、及
び主体金具1に一端が溶接等により結合されるとともに
他端側が側方に曲げ返されて、その側面が中心電極3の
先端部と対向するように配置された接地電極4等を備え
ている。また、接地電極4には上記発火部31に対向す
る発火部32が形成されており、それら発火部31と、
対向する発火部32との間の隙間が火花放電ギャップg
とされている。DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings. A spark plug 100 as an example of the present invention shown in FIG. 1 has a cylindrical metal shell 1, an insulator 2 fitted inside the metal shell 1 so that a distal end portion 21 protrudes, and a firing portion formed at the distal end. One end is connected to the center electrode 3 provided inside the insulator 2 and the metal shell 1 by welding or the like while the other end 31 is protruded, and the other end is bent to the side. 3 is provided with a ground electrode 4 and the like arranged so as to face the distal end portion. Further, the ground electrode 4 is provided with a firing portion 32 facing the firing portion 31.
The gap between the opposing firing part 32 is the spark discharge gap g.
It has been.
【0013】絶縁体2は、例えばアルミナあるいは窒化
アルミニウム等のセラミック焼結体により構成され、そ
の内部には自身の軸方向に沿って中心電極3を嵌め込む
ための孔部6を有している。また、主体金具1は、低炭
素鋼等の金属により円筒状に形成されており、スパーク
プラグ100のハウジングを構成するとともに、その外
周面には、プラグ100を図示しないエンジンブロック
に取り付けるためのねじ部7が形成されている。The insulator 2 is made of a ceramic sintered body such as alumina or aluminum nitride, and has a hole 6 for fitting the center electrode 3 along its own axial direction. . The metal shell 1 is formed of a metal such as low-carbon steel in a cylindrical shape, forms a housing of the spark plug 100, and has a screw on its outer peripheral surface for attaching the plug 100 to an engine block (not shown). The part 7 is formed.
【0014】次に、中心電極3及び接地電極4の本体部
3a及び4aはNi合金等で構成されている。一方、上
記発火部31及び対向する発火部32は、Rhを3〜4
9.5重量%、望ましくは7〜30重量%、より望まし
くは15〜25重量%、最も望ましくは18〜22重量
%の範囲で含有し、さらにWを0.5〜12重量%、望
ましくは2〜9重量%の範囲で含有する合金により構成
される。Next, the body portions 3a and 4a of the center electrode 3 and the ground electrode 4 are made of a Ni alloy or the like. On the other hand, the firing part 31 and the opposing firing part 32 set Rh at 3 to 4
9.5% by weight, preferably 7 to 30% by weight, more preferably 15 to 25% by weight, most preferably 18 to 22% by weight, and further contains W 0.5 to 12% by weight, preferably It is composed of an alloy containing from 2 to 9% by weight.
【0015】図2に示すように、中心電極3の本体部3
aは先端側が縮径されるとともにその先端面が平坦に構
成され、ここに上記発火部を構成する合金組成からなる
円板状のチップを重ね合わせ、さらにその接合面外縁部
に沿ってレーザー溶接、電子ビーム溶接、抵抗溶接等に
より溶接部Bを形成してこれを固着することにより発火
部31が形成される。また、対向する発火部32は、発
火部31に対応する位置において接地電極4にチップを
位置合わせし、その接合面外縁部に沿って同様に溶接部
Bを形成してこれを固着することにより形成される。な
お、発火部31及び対向する発火部32のいずれか一方
を省略する構成としてもよい。この場合には、発火部3
1又は対向する発火部32と接地電極4又は中心電極3
との間で火花放電ギャップgが形成される。これらチッ
プは、例えば表記組成となるように各合金成分を配合・
溶解することにより得られる溶解合金を熱間圧延により
板状に加工し、その板材を熱間打抜き加工により所定の
チップ形状に打ち抜いて形成されたものが使用されてい
る。なお、チップは、合金を熱間圧延又は熱間鍛造によ
り線状あるいはロッド状に加工した後、これを長さ方向
に所定長に切断して形成したものを使用してもよい。As shown in FIG. 2, the main body 3 of the center electrode 3
As for a, the tip side is reduced in diameter and the tip end surface is flattened, a disk-shaped chip made of an alloy composition constituting the ignition portion is superimposed thereon, and laser welding is performed along the outer edge of the joining surface. The welding portion B is formed by electron beam welding, resistance welding, or the like, and is fixed to form the ignition portion 31. Further, the opposing firing portion 32 is formed by aligning the tip with the ground electrode 4 at a position corresponding to the firing portion 31, forming a welded portion B along the outer edge of the joint surface, and fixing the same. It is formed. Note that a configuration may be employed in which one of the firing portion 31 and the facing firing portion 32 is omitted. In this case, the firing part 3
1 or opposing firing part 32 and ground electrode 4 or center electrode 3
And a spark discharge gap g is formed. For these chips, for example, each alloy component is blended so as to have the indicated composition.
A material formed by processing a molten alloy obtained by melting into a plate by hot rolling and punching the plate into a predetermined chip shape by hot punching is used. The chip may be formed by processing the alloy into a linear shape or a rod shape by hot rolling or hot forging, and then cutting the alloy into a predetermined length in the length direction.
【0016】以下、スパークプラグ100の作用につい
て説明する。すなわち、スパークプラグ100は、その
ねじ部7においてエンジンブロックに取り付けられ、燃
焼室に供給される混合気への着火源として使用される。
ここで、その火花放電ギャップgを形成する発火部31
及び対向する発火部32が前述の合金で構成されること
で、Irの酸化・揮発による発火部の消耗が抑制される
ので、長期に渡って火花放電gが拡大せず、プラグ10
0の寿命を伸ばすことができる。また、合金組成が前述
の範囲に設定されることで、発火部31及び32を構成
するチップを熱間圧延及び熱間打抜きにより極めて能率
よく製造できる。The operation of the spark plug 100 will be described below. That is, the spark plug 100 is attached to the engine block at the screw portion 7 and used as an ignition source for the air-fuel mixture supplied to the combustion chamber.
Here, the ignition portion 31 forming the spark discharge gap g
And since the opposing ignition part 32 is made of the above-mentioned alloy, the consumption of the ignition part due to the oxidation and volatilization of Ir is suppressed, so that the spark discharge g does not expand for a long time and the plug 10
0 life can be extended. Further, by setting the alloy composition in the above-described range, the chips constituting the ignition portions 31 and 32 can be manufactured extremely efficiently by hot rolling and hot punching.
【0017】[0017]
(実施例1)所定量のIr、Rh及びWを配合・溶解す
ることにより、Rhを15、20及び25重量%の各比
率で含有し、さらにWを0〜13重量%(0重量%及び
13重量%は比較例)の各種比率で含有して、残部が実
質的にIrである合金を作製した。この合金に対し熱間
圧延(温度700℃以上)を施して、これを厚さ0.5
mmの板材に加工した。なお、圧延中は試料温度が常に7
00℃以上に保持されるよう、一定パス毎に所定の炉を
用いて試料を加熱した。次いで、上記得られた板材を7
00℃以上に保持し、その状態で所定の金型により直径
0.7mm、厚さ0.5mmの円板状のチップを打ち抜く加
工を連続して行った。そして、打抜きを1000回以上
繰り返しても正常に打抜きが行えたものを「○」、80
0回程度でチップに割れや欠けが生じたり金型に損傷が
生じたものを「△」、100回未満でチップに割れや欠
けが生じたり金型に損傷が生じたものを「×」として評
価した。結果を表1に示す。(Example 1) By mixing and dissolving predetermined amounts of Ir, Rh and W, Rh is contained in respective proportions of 15, 20, and 25% by weight, and W is further contained in an amount of 0 to 13% by weight (0% by weight and 0% by weight). 13% by weight was prepared in various ratios of Comparative Example), and the balance was substantially Ir. This alloy is subjected to hot rolling (at a temperature of 700 ° C. or higher) to a thickness of 0.5 mm.
It was processed into a plate material of mm. During rolling, the sample temperature was always 7
The sample was heated using a predetermined furnace for each fixed pass so as to be maintained at a temperature of 00 ° C. or higher. Next, the obtained plate material was
The temperature was maintained at 00 ° C. or higher, and in this state, a process of punching out a disk-shaped chip having a diameter of 0.7 mm and a thickness of 0.5 mm using a predetermined mold was continuously performed. Then, a sample which was able to be normally punched even when the punching was repeated 1,000 times or more was evaluated as "O", 80
"△" indicates that the chip was broken or chipped or the mold was damaged in about 0 times, and "x" was the chip that was cracked or chipped or was damaged in less than 100 times. evaluated. Table 1 shows the results.
【0018】[0018]
【表1】 [Table 1]
【0019】チップ材料として、Wの含有量が本発明の
請求項の範囲内である合金を使用した場合は、その熱間
打抜き加工性が良好であることがわかる。When an alloy having a W content within the scope of the claims of the present invention is used as a chip material, it is understood that the hot stamping workability is good.
【0020】次に、表記各組成の合金のうち、Ir−1
5重量%Rh−9重量%W、及びIr−25重量%Rh
−11重量%Wの2種類と、比較例としてRh及びWを
含有しないIr金属を用いて、これを前述と同様の熱間
圧延及び打抜き加工により直径0.7mm、厚さ0.5mm
の円板状の試験片に加工し、さらに大気中にて1100
℃で20時間保持した後、各試験片の重量減少を測定し
た。その結果を図3に示す。すなわち、Rh及びWを表
記組成で含有する合金の試験片についてはIrの酸化揮
発が抑制されるので、比較例の試験片に比べてその重量
減少が小さくなっていることがわかる。このことは、そ
のような合金でスパークプラグのチップを作製すれば、
プラグの温度が上昇する高速・高負荷運転状態において
もチップの消耗が抑制され、プラグの耐久性が高められ
ることを示唆するものである。Next, of the alloys of the respective compositions, Ir-1
5% by weight Rh-9% by weight W and Ir-25% by weight Rh
Using two kinds of -11% by weight W and an Ir metal containing no Rh and W as a comparative example, this was subjected to hot rolling and punching in the same manner as described above to obtain a diameter of 0.7 mm and a thickness of 0.5 mm.
Into a disk-shaped test piece, and
After holding at 20 ° C. for 20 hours, the weight loss of each test piece was measured. The result is shown in FIG. That is, it can be seen that, since the oxidation and volatilization of Ir is suppressed in the test piece of the alloy containing Rh and W in the indicated composition, the weight loss is smaller than that of the test piece of the comparative example. This means that if you make a spark plug tip with such an alloy,
This suggests that even in a high-speed / high-load operation state in which the temperature of the plug increases, chip consumption is suppressed, and the durability of the plug is improved.
【0021】(実施例2)所定量のIr、Rh及びWを
配合・溶解することにより、Wを6重量%、Rhを0〜
60重量%の各種比率で含有し残部が実質的にIrで構
成された合金(ただし、Rh=0及び60重量%は比較
例)を用意し、これを用いて実施例1と同様の熱間圧延
及び打抜き加工により、直径0.7mm、厚さ0.5mmの
円板状のチップを作製した。なお、比較例として、Pt
−13重量%Ir溶解合金を用いたチップも作製した。
それらチップを用いて、図1に示すスパークプラグ10
0の発火部31及び対向する発火部32を形成するとと
もに(火花放電ギャップgの幅1.1mm)、各プラグの
性能試験を以下の条件にて行った。条件A(連続高速運
転を想定):6気筒ガソリンエンジン(排気量3000
cc)にそれらプラグを取り付け、スロットル全開状態、
エンジン回転数6000rpmにて300時間連続運転
し(中心電極温度約900℃)、運転終了後のプラグの
火花放電ギャップgの拡大量を測定した。図4は、その
結果を、合金中のRhの含有量と火花放電ギャップ増加
量との関係で示したものである。条件B(市街地運転を
想定):4気筒ガソリンエンジン(排気量2000cc)
にそれらプラグを取り付け、アイドリング1分→エンジ
ン回転数3500rpm、全開状態で30分→エンジン
回転数2000rpm、半開状態で20分を1サイクル
として、1000時間運転し(中心電極温度約780
℃)、運転終了後のプラグの火花放電ギャップgの拡大
量を測定した。図5は、その結果を、合金中のRhの含
有量と火花放電ギャップ増加量との関係で示したもので
ある。(Example 2) By mixing and dissolving predetermined amounts of Ir, Rh and W, W is 6% by weight and Rh is 0 to 0%.
An alloy containing 60% by weight in various proportions and the balance being substantially composed of Ir (Rh = 0 and 60% by weight is a comparative example) was prepared, and the same hot working as in Example 1 was performed using this. A disk-shaped chip having a diameter of 0.7 mm and a thickness of 0.5 mm was produced by rolling and punching. In addition, as a comparative example, Pt
A chip using a -13 wt% Ir molten alloy was also manufactured.
The spark plug 10 shown in FIG.
A sparking portion 31 of 0 and an opposing firing portion 32 were formed (the width of the spark discharge gap g was 1.1 mm), and a performance test of each plug was performed under the following conditions. Condition A (assuming continuous high-speed operation): 6-cylinder gasoline engine (displacement 3000
cc) with those plugs, throttle fully open,
The engine was operated continuously at an engine speed of 6000 rpm for 300 hours (center electrode temperature: about 900 ° C.), and the amount of expansion of the spark discharge gap g of the plug after the operation was measured. FIG. 4 shows the results in relation to the content of Rh in the alloy and the increase in the spark discharge gap. Condition B (assuming city driving): 4-cylinder gasoline engine (displacement 2000 cc)
The engine is operated for 1000 hours with one cycle of idling 1 minute → engine speed 3500 rpm, fully open state for 30 minutes → engine speed 2000 rpm, half open state for 20 minutes as one cycle (center electrode temperature about 780).
° C), and the amount of expansion of the spark discharge gap g of the plug after the operation was completed was measured. FIG. 5 shows the results in the relationship between the content of Rh in the alloy and the increase in the spark discharge gap.
【0022】条件Bにおいては、チップの合金組成範囲
が本発明の範囲に属するプラグについては、火花放電ギ
ャップgの増加が小さいのに対し、比較例(Rh60重
量%以上、及びPt−Ir合金)のプラグは火花放電ギ
ャップが著しく拡大していることがわかる。また、それ
よりも高負荷の条件Aにおいては、実施例と比較例との
間における火花放電ギャップ増加量の差がさらに顕著と
なっている。また、Rhの含有量範囲が3〜40重量%
から7〜30重量%へ、さらには15〜25重量%へと
変化するに伴い、ギャップ増加量が段階的に減少してお
り、特にRh含有量が15〜25重量%であるチップを
使用したプラグにおいては、厳しい運転条件にも拘わら
ず、非常に良好な耐久性を示していることがわかる。Under the condition B, the spark discharge gap g of the plug whose alloy composition range falls within the range of the present invention is small, whereas the comparative example (Rh 60% by weight or more and Pt-Ir alloy) It can be seen that the spark discharge gap of the plug is significantly widened. Further, under the higher load condition A, the difference in the spark discharge gap increase amount between the embodiment and the comparative example is further remarkable. Further, the content range of Rh is 3 to 40% by weight.
From 7 to 30% by weight, and further from 15 to 25% by weight, the amount of increase in the gap is gradually reduced, and in particular, a chip having a Rh content of 15 to 25% by weight was used. It can be seen that the plug shows very good durability despite severe operating conditions.
【0023】(実施例3)所定量のIr、Rh及びWを
配合・溶解することにより、Wを6重量%、Rhを1
5、18、20、22及び25重量%の各比率でそれぞ
れ含有し、残部が実質的にIrで構成された合金を用意
し、これをチップ材料として用いて実施例1と同様のプ
ラグを作製した。そして、これらプラグに対し実施例1
の条件Aよりもさらに厳しい下記条件Cにて性能試験を
行った。条件C:4気筒ガソリンエンジン(排気量16
00cc)にそれらプラグを取り付け、スロットル全開状
態、エンジン回転数6250rpmにて300時間連続
運転し(中心電極温度約950℃)、運転終了後のプラ
グの火花放電ギャップgの拡大量を測定した。図6は、
その結果を、合金中のRhの含有量と火花放電ギャップ
増加量との関係で示したものである。(Example 3) A predetermined amount of Ir, Rh and W are blended and dissolved to obtain 6% by weight of W and 1% of Rh.
5, 18, 20, 22, and 25% by weight of each alloy were prepared, and the balance was substantially composed of Ir. An alloy was prepared as a chip material, and a plug similar to that of Example 1 was manufactured. did. The first embodiment is applied to these plugs.
The performance test was performed under the following condition C, which is more severe than the condition A. Condition C: 4-cylinder gasoline engine (displacement 16
00 cc), the throttle was fully opened, and the engine was continuously operated at an engine speed of 6250 rpm for 300 hours (center electrode temperature: about 950 ° C.). FIG.
The results are shown in the relationship between the content of Rh in the alloy and the increase in spark discharge gap.
【0024】該結果によれば、Rhの含有量範囲が18
〜22重量%であるチップを使用したプラグにおいて
は、Rh含有量が該範囲外にあるチップを使用したもの
に比べて、条件Bよりさらに厳しい条件Cにおいてもギ
ャップ増加量が小さく、より良好な耐久性を示している
ことがわかる。According to the results, the content range of Rh was 18
In a plug using a chip having a content of 2222% by weight, the gap increase amount is smaller even under the condition C which is more severe than the condition B as compared with a plug using a chip whose Rh content is out of the above range, and the better. It turns out that it shows durability.
【図1】本発明のスパークプラグを示す正面部分断面
図。FIG. 1 is a front partial sectional view showing a spark plug of the present invention.
【図2】その要部を示す拡大断面図。FIG. 2 is an enlarged sectional view showing a main part thereof.
【図3】実施例の各試験片の酸化による重量減少の値を
示すグラフ。FIG. 3 is a graph showing the value of weight loss due to oxidation of each test piece of the example.
【図4】発火部を構成する合金中のRh含有量と、火花
放電ギャップの拡大量との関係を示すグラフ(実施例
2:条件A)。FIG. 4 is a graph showing the relationship between the Rh content in the alloy constituting the ignition portion and the amount of expansion of the spark discharge gap (Example 2: Condition A).
【図5】発火部を構成する合金中のRh含有量と、火花
放電ギャップの拡大量との関係を示すグラフ(実施例
2:条件B)。FIG. 5 is a graph showing the relationship between the Rh content in the alloy constituting the ignition portion and the amount of expansion of the spark discharge gap (Example 2: Condition B).
【図6】発火部を構成する合金中のRh含有量と、火花
放電ギャップの拡大量との関係を示すグラフ(実施例
3:条件C)。FIG. 6 is a graph showing the relationship between the Rh content in the alloy constituting the ignition portion and the amount of expansion of the spark discharge gap (Example 3: Condition C).
1 主体金具 2 絶縁体 3 中心電極 4 接地電極 31 発火部(チップ) 32 対向する発火部(チップ) g 火花放電ギャップ REFERENCE SIGNS LIST 1 metal shell 2 insulator 3 center electrode 4 ground electrode 31 firing part (tip) 32 opposing firing part (tip) g spark discharge gap
Claims (6)
られた絶縁体と、前記絶縁体の外側に設けられた主体金
具と、その主体金具に一端が結合され、他端側が前記中
心電極と対向するように配置された接地電極と、それら
中心電極と接地電極との少なくとも一方に固着されて火
花放電ギャップを形成する発火部とを備え、 その発火部が、Irを主体としてRhを3〜49.5重
量%の範囲で含有し、さらにWを0.5〜12重量%の
範囲で含有した合金により構成されることを特徴とする
スパークプラグ。1. A center electrode, an insulator provided outside the center electrode, a metal shell provided outside the insulator, one end of the metal shell is coupled to the metal shell, and the other end is connected to the center electrode. A spark electrode that is fixed to at least one of the center electrode and the ground electrode to form a spark discharge gap. A spark plug characterized by comprising an alloy containing up to 49.5% by weight and further containing W in a range of 0.5 to 12% by weight.
9重量%の範囲で含有する請求項1記載のスパークプラ
グ。2. An alloy constituting the ignition portion, wherein W is 2 to 2.
The spark plug according to claim 1, which is contained in a range of 9% by weight.
〜30重量%の範囲で含有する請求項1又は2に記載の
スパークプラグ。3. The alloy constituting the ignition part has a Rh of 7
The spark plug according to claim 1, wherein the content of the spark plug is in the range of about 30% by weight.
5〜25重量%の範囲で含有する請求項1又は2に記載
のスパークプラグ。4. The alloy constituting the ignition portion has a Rh of 1
The spark plug according to claim 1, wherein the content of the spark plug is 5 to 25% by weight.
8〜22重量%の範囲で含有する請求項1又は2に記載
のスパークプラグ。5. The alloy constituting the ignition portion has a Rh of 1
The spark plug according to claim 1, wherein the content of the spark plug is in a range of 8 to 22% by weight.
ように配合・溶解して得られる溶解合金に対し、圧延、
鍛造、引き抜き、切削、切断及び打抜きの少なくともい
ずれかの工程を含む加工を施して得られる加工材により
形成されたものである請求項1ないし5のいずれかに記
載のスパークプラグ。6. The igniter is formed by rolling and rolling a molten alloy obtained by mixing and melting a raw material so as to have a predetermined composition.
The spark plug according to any one of claims 1 to 5, wherein the spark plug is formed of a work material obtained by performing a process including at least one of forging, drawing, cutting, cutting, and punching.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP33512296A JP3878262B2 (en) | 1996-11-28 | 1996-11-28 | Spark plug |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP33512296A JP3878262B2 (en) | 1996-11-28 | 1996-11-28 | Spark plug |
Publications (2)
Publication Number | Publication Date |
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JPH10162931A true JPH10162931A (en) | 1998-06-19 |
JP3878262B2 JP3878262B2 (en) | 2007-02-07 |
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ID=18285026
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JP33512296A Expired - Fee Related JP3878262B2 (en) | 1996-11-28 | 1996-11-28 | Spark plug |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004007782A1 (en) * | 2002-07-13 | 2004-01-22 | Johnson Matthey Public Limited Company | Alloy |
KR100644319B1 (en) * | 2004-12-30 | 2006-11-10 | 주식회사 세림테크 | Spark Plug with Iridium-Rhodium Alloy Electrode Tip including Tungsten |
-
1996
- 1996-11-28 JP JP33512296A patent/JP3878262B2/en not_active Expired - Fee Related
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004007782A1 (en) * | 2002-07-13 | 2004-01-22 | Johnson Matthey Public Limited Company | Alloy |
US7481971B2 (en) | 2002-07-13 | 2009-01-27 | Johnson Matthey Public Limited Company | Iridium alloy |
KR100644319B1 (en) * | 2004-12-30 | 2006-11-10 | 주식회사 세림테크 | Spark Plug with Iridium-Rhodium Alloy Electrode Tip including Tungsten |
Also Published As
Publication number | Publication date |
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JP3878262B2 (en) | 2007-02-07 |
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