JP3196288B2 - Spark plug for internal combustion engine - Google Patents
Spark plug for internal combustion engineInfo
- Publication number
- JP3196288B2 JP3196288B2 JP03433792A JP3433792A JP3196288B2 JP 3196288 B2 JP3196288 B2 JP 3196288B2 JP 03433792 A JP03433792 A JP 03433792A JP 3433792 A JP3433792 A JP 3433792A JP 3196288 B2 JP3196288 B2 JP 3196288B2
- Authority
- JP
- Japan
- Prior art keywords
- stress relaxation
- relaxation layer
- noble metal
- metal tip
- spark plug
- 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 - Fee Related
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Description
【０００１】[0001]
【産業上の利用分野】本発明は，発火部に貴金属チップ
を設けた内燃機関用スパークプラグの発火部の構成に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug for an internal combustion engine having a noble metal tip in a spark plug.
【０００２】[0002]
【従来技術】従来，内燃機関用のスパークプラグにおい
ては，中心電極及び接地電極の電極材料としてニッケル
基合金を用いたものがある。そして，その発火部には，
上記ニッケル基合金のみを用いるもの，該ニッケル基合
金を電極材料としてその表面に白金，白金合金からなる
貴金属チップを溶接したものとがある。即ち，エンジン
の燃焼室内で常時放電を行うスパークプラグの電極は，
耐熱耐食性が優れていると共に放電に対する耐消耗性の
良いことが要求される。この要求を満たす材料として，
前者のごとくニッケルにクロム等を添加したニッケル基
合金が従来より使用されてきた。2. Description of the Related Art A conventional spark plug for an internal combustion engine uses a nickel-based alloy as an electrode material for a center electrode and a ground electrode. And in the ignition part,
There are those using the above-mentioned nickel-based alloy alone, and those using the nickel-based alloy as an electrode material and welding a noble metal tip made of platinum or a platinum alloy to the surface thereof. That is, the electrode of the spark plug, which constantly discharges in the combustion chamber of the engine,
It is required to have excellent heat and corrosion resistance and good wear resistance to discharge. As a material that meets this requirement,
As described above, nickel-based alloys obtained by adding chromium or the like to nickel have been used.
【０００３】また，近年，後者のごとく，耐消耗性に非
常に優れた前記貴金属チップを発火部に備えたものが製
品化されるにあたっても，電極材料としては，相変わら
ず耐熱耐食性に優れたニッケル基合金が使用されてい
る。上記貴金属チップは，中心電極及び接地電極の発火
部において，少なくともその一方に溶接されている。上
記のごとく，貴金属チップを上記発火部の少なくとも一
方に溶接したスパークプラグにおいては，耐熱耐食性と
共に放電による耐消耗性にも非常に優れている。[0003] In recent years, as in the latter case, when a product having the noble metal tip having extremely excellent wear resistance in the ignition portion is commercialized, a nickel-based electrode having excellent heat resistance and corrosion resistance is still used as an electrode material. Alloys are used. The noble metal tip is welded to at least one of the ignition portions of the center electrode and the ground electrode. As described above, a spark plug in which a noble metal tip is welded to at least one of the ignition portions has extremely excellent heat resistance and corrosion resistance as well as wear resistance due to electric discharge.
【０００４】[0004]
【解決しようとする課題】しかしながら，発火部に上記
貴金属チップを溶接したスパークプラグにおいては，次
の問題がある。即ち，電極材料を構成するニッケル基合
金と貴金属チップとの間においては，その線膨張係数に
大きな差がある。そのため，高温のエンジン中で長期間
使用していると，熱応力により，貴金属チップがニッケ
ル基合金の電極材料より，剥離脱落するというおそれが
ある。However, the spark plug in which the noble metal tip is welded to the ignition portion has the following problem. That is, there is a large difference in the coefficient of linear expansion between the nickel base alloy and the noble metal tip constituting the electrode material. Therefore, when used in a high-temperature engine for a long period of time, there is a possibility that the noble metal tip will peel off from the nickel-based alloy electrode material due to thermal stress.
【０００５】上記線膨張係数は，ニッケル基合金におい
ては，約１３×１０-6／℃，貴金属チップにおいては約
９×１０-6／℃である。そこで，上記線膨張係数の差に
起因する熱応力を軽減すべく，ニッケル基合金と貴金属
チップとの間に，両者の間の線膨張係数を有する，別個
の白金合金よりなる熱応力緩和用の応力緩和層を設ける
ことが提案されている（特公平３−２２０３３号公
報）。The linear expansion coefficient is about 13 × 10 −6 / ° C. for a nickel-based alloy and about 9 × 10 −6 / ° C. for a noble metal tip. Therefore, in order to reduce the thermal stress caused by the difference in the coefficient of linear expansion, a separate platinum alloy having a coefficient of linear expansion between the nickel base alloy and the noble metal tip is used. It has been proposed to provide a stress relaxation layer (Japanese Patent Publication No. 3-22033).
【０００６】しかし，従来の応力緩和層は，白金合金を
用いるものであるため，コスト高となる。一方，熱応力
緩和の点のみからすれば，応力緩和層は，貴金属チップ
と電極材料の線膨張係数の間の線膨張係数を有する材料
であれば良いこととなるが，スパークプラグはエンジン
の高温腐食雰囲気中で使用されるため，応力緩和層は充
分な耐熱耐食性も兼備する必要がある。本発明はかかる
従来の問題点に鑑み，応力緩和層が優れた耐熱耐食性を
有し，電極材料と貴金属チップとの間の熱応力を軽減で
き，かつ製造容易な内燃機関用スパークプラグを提供し
ようとするものである。However, since the conventional stress relaxation layer uses a platinum alloy, the cost is high. On the other hand, from the viewpoint of thermal stress relaxation only, the stress relaxation layer only needs to be a material having a linear expansion coefficient between that of the noble metal tip and the electrode material. Since it is used in a corrosive atmosphere, the stress relaxation layer must also have sufficient heat and corrosion resistance. SUMMARY OF THE INVENTION In view of the conventional problems, the present invention provides a spark plug for an internal combustion engine in which a stress relaxation layer has excellent heat and corrosion resistance, can reduce thermal stress between an electrode material and a noble metal tip, and is easy to manufacture. It is assumed that.
【０００７】[0007]
【課題の解決手段】本発明は，絶縁碍子と該絶縁碍子に
保持した中心電極と，上記絶縁碍子の外周に固定したハ
ウジングと，該ハウジングに設けられ上記中心電極と対
向させた接地電極とよりなり，かつ上記中心電極と接地
電極の少なくとも一方の電極材料にはその発火部に白金
又は白金合金よりなる貴金属チップを設けてなる内燃機
関用スパークプラグにおいて，上記貴金属チップと上記
電極材料との間には応力緩和層を介在させてなり，かつ
上記応力緩和層は，クロム８〜２０重量％とアルミニウ
ム，ニッケル，モリブデン，銅，チタン，ニオブ，ジル
コニウム及びセレンの中の１種以上からなる添加物０．
１〜５重量％とを含有する鉄合金により構成されている
ことを特徴とする内燃機関用スパークプラグにある。本
発明において最も注目すべきことは，中心電極及び接地
電極の一方又は双方に上記貴金属チップを溶接したスパ
ークプラグにおいて，上記貴金属チップと電極材料との
間には，上記鉄合金からなる応力緩和層を介設したこと
である。The present invention comprises an insulator, a center electrode held by the insulator, a housing fixed to the outer periphery of the insulator, and a ground electrode provided on the housing and facing the center electrode. A spark plug for an internal combustion engine, wherein at least one electrode material of the center electrode and the ground electrode is provided with a noble metal tip made of platinum or a platinum alloy at its ignition part. A stress relaxation layer interposed therebetween, and the stress relaxation layer comprises 8 to 20% by weight of chromium and aluminum.
, Nickel, molybdenum, copper, titanium, niobium, jill
Additive comprising at least one of conium and selenium
A spark plug for an internal combustion engine, comprising: an iron alloy containing 1 to 5% by weight . The most remarkable point in the present invention is that in a spark plug in which the noble metal tip is welded to one or both of a center electrode and a ground electrode, a stress relaxation layer made of the iron alloy is provided between the noble metal tip and the electrode material. It is interposed.
【０００８】上記鉄合金は，クロム（Ｃｒ）が８〜２０
重量％と鉄（Ｆｅ）が残部とからなる基本組成を有し，
アルミニウム，ニッケル，モリブデン，銅，チタン，ニ
オブ，ジルコニウム及びセレンの中の１種以上からなる
添加物０．１〜５重量％を含有する。Ｃｒが８重量％未
満では，スパークプラグが用いられる内燃機関の高温腐
食雰囲気中での使用に対して，酸化抵抗が低く，耐熱耐
食性が不充分である。一方，２０重量％を越えると，応
力緩和層の形状に鉄合金を成形，切断する際の加工性，
及び貴金属チップ，電極材料との溶接性が低下する。The above iron alloy has a chromium (Cr) content of 8-20.
Wt% iron (Fe) is have a basic composition comprising the remainder,
Aluminum, nickel, molybdenum, copper, titanium, d
Consists of one or more of the following: ob, zirconium, and selenium
Contains 0.1 to 5% by weight of additives . If the Cr content is less than 8% by weight, the oxidation resistance is low and the heat and corrosion resistance is insufficient for use in a high-temperature corrosive atmosphere of an internal combustion engine using a spark plug. On the other hand, if it exceeds 20% by weight, the workability when forming and cutting the iron alloy into the shape of the stress relaxation layer,
In addition, the weldability with noble metal tips and electrode materials is reduced.
【０００９】また，Ｃｒが８〜２０重量％の場合には，
応力緩和層の線膨張係数が約１０〜１１×１０-6／℃で
ある。一方，中心電極，接地電極の電極材料であるニッ
ケル基合金は，その線膨張係数が前記のごとく１３×１
０-6／℃である。また，貴金属チップの線膨張係数は約
９×１０-6／℃である。それ故，応力緩和層は，電極材
料と貴金属チップとの中間辺りの線膨張係数となり，電
極材料と貴金属チップの間の熱応力が大幅に軽減され
る。When the content of Cr is 8 to 20% by weight,
The coefficient of thermal expansion of the stress relaxation layer is about 10 to 11 × 10 −6 / ° C. On the other hand, the nickel-based alloy as the electrode material of the center electrode and the ground electrode has a linear expansion coefficient of 13 × 1 as described above.
0 -6 / ° C. The linear expansion coefficient of the noble metal tip is about 9 × 10 −6 / ° C. Therefore, the stress relaxation layer has a linear expansion coefficient around the middle between the electrode material and the noble metal tip, and the thermal stress between the electrode material and the noble metal tip is greatly reduced.
【００１０】また，上記鉄合金は，強度，耐酸化性の観
点よりクロムの他に，一般に鉄合金中に含有させる，炭
素（Ｃ），マンガン（Ｍｎ），珪素（Ｓｉ）を含有させ
ることが好ましい。上記Ｃは０．０６〜０．１８重量％
とすることが好ましい。上記Ｍｎは０．５〜１．２重量
％とすることが好ましい。また，上記Ｓｉは０．６〜
１．２重量％とすることが好ましい。[0010] The above-mentioned iron alloy may contain carbon (C), manganese (Mn), and silicon (Si), which are generally contained in an iron alloy, in addition to chromium from the viewpoint of strength and oxidation resistance. preferable. C is 0.06 to 0.18% by weight
It is preferable that The Mn is preferably set to 0.5 to 1.2% by weight. In addition, the above-mentioned Si is 0.6 to
Preferably, it is 1.2% by weight.
【００１１】[0011]
【００１２】上記電極材料と貴金属チップとの間に応力
緩和層を溶接する方法としては，抵抗溶接等の方法があ
る。また，中心電極又は接地電極の電極材料としては，
例えば従来と同様のニッケル基合金を用いる。As a method of welding the stress relaxation layer between the electrode material and the noble metal tip, there is a method such as resistance welding. In addition, as the electrode material of the center electrode or the ground electrode,
For example, a nickel-base alloy similar to the conventional one is used.
【００１３】[0013]
【作用及び効果】本発明の内燃機関用スパークプラグに
おいては，貴金属チップと電極材料との間に，８〜２０
重量％のＣｒを含有する鉄合金を用いている。そのた
め，応力緩和層の耐熱耐食性は高い。即ち，内燃機関の
高温腐食雰囲気中で用いられるスパークプラグにおいて
は，上記のごとく，応力緩和層に対しても高温耐酸化性
が強く要求される。この点，本発明の応力緩和層は，Ｆ
ｅを主成分とするために高温下における酸化進行が懸念
される。しかし，本発明の応力緩和層は，８〜２０重量
％のＣｒを含有しているため，Ｃｒの酸化物が応力緩和
層の表面を緻密に覆い，内部への酸化進行を阻止する。
それ故，耐熱耐食性に優れている。In the spark plug for an internal combustion engine according to the present invention, between 8 and 20 are provided between the noble metal tip and the electrode material.
An iron alloy containing Cr by weight is used. Therefore, the thermal relaxation resistance of the stress relaxation layer is high. That is, in a spark plug used in a high-temperature corrosive atmosphere of an internal combustion engine, as described above, the high-temperature oxidation resistance is also required for the stress relaxation layer. In this regard, the stress relaxation layer of the present invention has
Since e is the main component, there is a concern that oxidation may proceed at high temperatures. However, since the stress relieving layer of the present invention contains 8 to 20% by weight of Cr, the oxide of Cr covers the surface of the stress relieving layer densely and prevents the progress of oxidation to the inside.
Therefore, it is excellent in heat resistance and corrosion resistance.
【００１４】また，８〜２０重量％のＣｒを含有する鉄
合金は，線膨張係数が約１０〜１１×１０-6／℃であ
り，前記のごとく，貴金属チップ及び電極材料の各線膨
張係数のほぼ中間位置にあり，これらの間の線膨張係数
の差異は約１〜３×１０-6／℃程度と小さい。そのた
め，線膨張係数差に起因する熱応力の発生は，大幅に低
減され，貴金属チップの剥離が発生するおそれはない。
また，従来のごとく，応力緩和層用の高価な白金合金材
料を別途準備する必要もない。それ故，スパークプラグ
の製造が容易で，コストも低下する。The iron alloy containing 8 to 20% by weight of Cr has a linear expansion coefficient of about 10 to 11 × 10 −6 / ° C., and as described above, the linear expansion coefficient of each of the noble metal tip and the electrode material. It is almost at an intermediate position, and the difference in the coefficient of linear expansion between them is as small as about 1 to 3 × 10 −6 / ° C. Therefore, the occurrence of thermal stress due to the difference in linear expansion coefficient is greatly reduced, and there is no possibility that the noble metal chip will be peeled off.
Further, it is not necessary to separately prepare an expensive platinum alloy material for the stress relaxation layer as in the related art. Therefore, the manufacture of the spark plug is easy and the cost is reduced.
【００１５】また，上記鉄合金は，アルミニウム，ニッ
ケル，モリブデン，銅，チタン，ニオブ，ジルコニウム
及びセレンの中の１種以上からなる添加物を，上述した
範囲で添加しているため，耐熱耐食性，加工性，強度が
一層向上し，また電極材料及び貴金属チップとの溶接性
も向上する。したがって，本発明によれば，応力緩和層
が優れた耐熱耐食性を有し，電極材料と貴金属チップと
の間の熱応力を軽減でき，かつ製造容易な内燃機関用ス
パークプラグを提供することができる。[0015] The above-mentioned iron alloy is made of aluminum, nickel , or the like.
Kel, molybdenum, copper, titanium, niobium, zirconium
And at least one additive of selenium, as described above.
Since it is added in the range , the heat resistance and corrosion resistance, workability, and strength are further improved, and the weldability with the electrode material and the noble metal tip is also improved. Therefore, according to the present invention, it is possible to provide a spark plug for an internal combustion engine in which the stress relaxation layer has excellent heat and corrosion resistance, can reduce the thermal stress between the electrode material and the noble metal tip, and is easy to manufacture. .
【００１６】[0016]
実施例１ 本発明の実施例にかかる内燃機関用スパークプラグにつ
き，図１及び図２を用いて説明する。本例のスパークプ
ラグ２は，絶縁碍子２０と，該絶縁碍子２０に保持した
中心電極４と，絶縁碍子２０の外周に固定したハウジン
グ２５と，該ハウジング２５に設けられて，上記中心電
極４との間にギャップ３０を設けて対向させた接地電極
３とよりなる。Embodiment 1 A spark plug for an internal combustion engine according to an embodiment of the present invention will be described with reference to FIGS. The spark plug 2 of this embodiment includes an insulator 20, a center electrode 4 held by the insulator 20, a housing 25 fixed to the outer periphery of the insulator 20, and the center electrode 4 provided on the housing 25. And a ground electrode 3 opposed to the gap 30.
【００１７】上記中心電極４の発火部には，応力緩和層
５を溶接し，更にその先端面に白金合金よりなる貴金属
チップ１を溶接している。また，上記接地電極３の発火
部にも，同様に応力緩和層５を介して貴金属チップ１を
溶接している。そして，上記応力緩和層は，いずれもＣ
ｒ８〜２０重量％を含有する鉄合金により構成されてい
る。また，中心電極４及び接地電極３の電極材料は，い
ずれもニッケル基合金である。また，上記両電極材料と
応力緩和層５とは，抵抗溶接により溶接されている。ま
た，応力緩和層５と貴金属チップ１との間は，抵抗溶接
により溶接されている。A stress relaxation layer 5 is welded to the ignition portion of the center electrode 4, and a noble metal tip 1 made of a platinum alloy is welded to the tip surface. The noble metal tip 1 is also welded to the ignition portion of the ground electrode 3 via the stress relaxation layer 5. Each of the stress relaxation layers is made of C
It is composed of an iron alloy containing 8 to 20% by weight of r. The electrode materials of the center electrode 4 and the ground electrode 3 are both nickel-based alloys. The two electrode materials and the stress relaxation layer 5 are welded by resistance welding. The stress relaxation layer 5 and the noble metal tip 1 are welded by resistance welding.
【００１８】次に，上記絶縁碍子２０は高純度のアルミ
ナよりなり，リング状の気密パッキン２４及びリング２
３を介してハウジング２５の内孔にかしめ固定されてい
る。中心電極４は，その下方先端部を，絶縁碍子２０の
下方に突出させて該絶縁碍子２０に保持してある。ま
た，絶縁碍子２０の軸孔２２には，上部に端子４２１を
有する中軸４２が挿入され，導電性のガラスシール材４
４により，上記中心電極４と一体的に加熱融着してあ
る。また，接地電極３はハウジング２５の環状端面２５
１に接合されている。Next, the insulator 20 is made of high-purity alumina, and has a ring-shaped hermetic packing 24 and a ring 2.
It is caulked and fixed to the inner hole of the housing 25 via 3. The center electrode 4 is held by the insulator 20 with its lower end protruding below the insulator 20. A central shaft 42 having a terminal 421 at the top is inserted into the shaft hole 22 of the insulator 20, and the conductive glass seal material 4
4, the central electrode 4 is integrally heated and fused. The ground electrode 3 is connected to the annular end face 25 of the housing 25.
1.
【００１９】実施例２ 次に，実施例１に示したスパークプラグにつき，応力緩
和層における，鉄合金の組成を種々に変えて，評価試験
を行い，その結果を表１に示した。即ち，応力緩和層と
しては，クロム（Ｃｒ）を０〜２４重量％，カーボン
（Ｃ）を０．１０〜０．１５重量％，マンガン（Ｍｎ）
を０．７〜１．０重量％，珪素（Ｓｉ）を０．８〜１．
０重量％，残部が鉄（Ｆｅ）よりなる鉄合金を用いた。
そして，エンジンでの各応力緩和層の酸化試験，エンジ
ン中での貴金属チップの接合の信頼性試験を実施した。
上記酸化試験は応力緩和層の耐熱耐食性に関するもので
ある。以下，その詳細について述べる。Example 2 Next, an evaluation test was performed on the spark plug shown in Example 1 by changing the composition of the iron alloy in the stress relaxation layer in various ways, and the results are shown in Table 1. That is, as the stress relaxation layer, 0 to 24% by weight of chromium (Cr), 0.10 to 0.15% by weight of carbon (C), and manganese (Mn)
0.7 to 1.0% by weight, and silicon (Si) 0.8 to 1.
An iron alloy consisting of 0% by weight and the balance iron (Fe) was used.
Then, an oxidation test of each stress relaxation layer in the engine and a reliability test of bonding of the noble metal tip in the engine were performed.
The above oxidation test relates to the heat and corrosion resistance of the stress relaxation layer. The details are described below.
【００２０】エンジン試験は，４サイクル，６気筒，２
０００ｃｃのエンジンを用い，高温一定条件となるフル
スロットル耐久テストを１００時間実施した。応力緩和
層の酸化試験は，中心電極４に関して，図３に例示する
ように，上記エンジン試験後における応力緩和層５の内
部への酸化物５１の生成深さを測定し，評価した。The engine test was performed in four cycles, six cylinders, and two cylinders.
Using a 2,000 cc engine, a full throttle endurance test was performed for 100 hours under constant high temperature conditions. In the oxidation test of the stress relaxation layer, as shown in FIG. 3, the depth of formation of the oxide 51 inside the stress relaxation layer 5 after the engine test was measured for the center electrode 4 and evaluated.
【００２１】評価に当たっては，従来の経験から，図３
に示すごとく，応力緩和層５において，両端からの酸化
深さの和Ａ＋Ｂが，接合部の直径Ｃの２５％以下であれ
ば信頼性が十分確保できることが分かっており，表１の
下に記した判定基準で判断した。上記接合の信頼性試験
は応力緩和層の溶接部の耐熱耐食性に関するものであ
る。以下その詳細について述べる。エンジン試験は，４
サイクル，６気筒，２０００ｃｃのエンジンを用い，繰
り返し熱応力が発生する様にアイドリング１分とフルス
ロットル１分の繰り返しを１００時間実施した。In the evaluation, based on the conventional experience, FIG.
As shown in Table 1, it is known that if the sum A + B of the oxidation depth from both ends of the stress relaxation layer 5 is 25% or less of the diameter C of the joint, sufficient reliability can be secured. Judgment was made based on the judgment criteria. The above joint reliability test relates to the heat and corrosion resistance of the welded portion of the stress relaxation layer. The details will be described below. Engine test is 4
Using a cycle, 6-cylinder, 2000cc engine, 1 minute of idling and 1 minute of full throttle were repeated for 100 hours so that thermal stress was repeatedly generated.
【００２２】貴金属チップ１と応力緩和層５との間の接
合の信頼性は，中心電極４に関して，図４に例示するよ
うに，上記エンジン試験後の熱応力による接合面の酸化
が，中心電極４と応力緩和層５との接合面に比べ，応力
緩和層５と貴金属チップ１との接合面の方が顕著であっ
た。そこで，応力緩和層５と貴金属チップ１との接合面
への酸化深さ５２の状態で評価した。試験品の判定にあ
たっては，従来の経験から，両端からの酸化深さの和Ｄ
＋Ｅが，接合部の直径Ｆの２５％以下であれば信頼性が
十分確保できることが分かっており，表１の下に記した
判定基準で判断した。その評価結果を表１に示す。The reliability of the joint between the noble metal tip 1 and the stress relieving layer 5 depends on the center electrode 4 as shown in FIG. The bonding surface between the stress relaxation layer 5 and the noble metal tip 1 was more remarkable than the bonding surface between the stress relaxation layer 5 and the stress relaxation layer 5. Therefore, the evaluation was performed in the state of the oxidation depth 52 to the joint surface between the stress relaxation layer 5 and the noble metal tip 1. In the judgment of the test sample, the sum of the oxidation depth D
It is known that if + E is 25% or less of the diameter F of the joint, it is known that the reliability can be sufficiently ensured. Table 1 shows the evaluation results.
【００２３】表１より知られるごとく，応力緩和層５に
おける酸化物の生成深さ（図３参照）は，Ｃｒが８重量
％以上の場合には，２０％以下となり，耐熱耐食性に優
れていることが分かる。また，応力緩和層と貴金属チッ
プとの接合面における酸化物の生成深さ（図４参照）
は，Ｃｒが６重量％以上の場合には，酸化が殆どないこ
とが分かる。一方，Ｃｒ量が多い場合には，エンジン試
験の結果に関しては問題ないが，Ｃｒが２０重量％を越
えると加工性，溶接性の面で，応力緩和層への適用が困
難となる。以上より，鉄合金中に含有させるＣｒは，８
〜２０重量％が適切であることが分かる。As can be seen from Table 1, the formation depth of the oxide in the stress relaxation layer 5 (see FIG. 3) is 20% or less when Cr is 8% by weight or more, and is excellent in heat resistance and corrosion resistance. You can see that. Also, the depth of oxide formation at the joint surface between the stress relaxation layer and the noble metal tip (see Fig. 4)
Shows that when Cr is 6% by weight or more, there is almost no oxidation. On the other hand, when the Cr content is large, there is no problem with respect to the result of the engine test, but when Cr exceeds 20% by weight, application to the stress relaxation layer becomes difficult in terms of workability and weldability. From the above, Cr contained in the iron alloy is 8%.
It turns out that -20% by weight is appropriate.
【００２４】[0024]
【表１】 [Table 1]
【００２５】実施例３ 本例は，実施例２に示した応力緩和層の中，試料Ｎｏ５
（Ｃｒ含量８重量％）を基準として，これに前記添加物
を添付した鉄合金を用い，実施例２と同様の評価試験を
行った例である。その結果を表２に示す。上記添加物と
しては，表２に示す８種類の中の１種又は２種以上を
０．１〜５重量％添加した。各応力緩和層は，Ｃｒ８重
量％，Ｃ０．０８重量％，Ｍｎ及びＳｉ０．９重量％，
上記添加物０．１〜５重量％及び残部Ｆｅからなる。Embodiment 3 In this embodiment, sample No. 5 was used in the stress relaxation layer shown in embodiment 2.
This is an example in which an evaluation test similar to that of Example 2 was performed on the basis of (Cr content 8% by weight) using an iron alloy to which the above additive was added. Table 2 shows the results. As the above additives, 0.1 to 5% by weight of one or more of the eight types shown in Table 2 was added. Each stress relaxation layer is composed of 8% by weight of Cr, 0.08% by weight of C, 0.9% by weight of Mn and Si,
The additive consists of 0.1 to 5% by weight and the balance Fe.
【００２６】表２より知られるごとく，上記添加物を含
有させることにより，応力緩和層における酸化物の生成
深さ（表２のＫ）が，試料Ｎｏ５の場合よりも少なくな
り，耐熱耐食性が一層向上することが分かる。また，応
力緩和層と貴金属チップとの接合面における酸化深さ
（表２のＳ）に関しては，試料Ｎｏ５よりも若干劣るも
のもあるが，Ｎｏ５と同等又はそれより優れるものが多
い。また，応力緩和層の加工性はＮｏ５と同様であっ
た。このように，上記添加物の添加により，耐熱耐食
性，熱応力の軽減及び加工性ともに優れた応力緩和層が
得られる。As can be seen from Table 2, the inclusion depth of the oxide in the stress relaxation layer (K in Table 2) becomes smaller than that of the sample No. 5 by adding the above additive, and the heat and corrosion resistance is further improved. It can be seen that it improves. The oxidation depth (S in Table 2) at the joint surface between the stress relaxation layer and the noble metal tip is slightly inferior to sample No. 5, but is often equal to or better than No. 5. The workability of the stress relaxation layer was similar to that of No. 5. Thus, by adding the above-mentioned additives, a stress relaxation layer excellent in both heat resistance and corrosion resistance, reduction of thermal stress and workability can be obtained.
【００２７】[0027]
【表２】 [Table 2]
【図１】実施例１にかかる内燃機関用スパークプラグの
要部拡大図。FIG. 1 is an enlarged view of a main part of a spark plug for an internal combustion engine according to a first embodiment.
【図２】実施例１にかかる内燃機関用スパークプラグの
一部断面図。FIG. 2 is a partial cross-sectional view of the spark plug for an internal combustion engine according to the first embodiment.
【図３】実施例２の評価試験における，応力緩和層の酸
化状態を示す説明図。FIG. 3 is an explanatory diagram showing an oxidation state of a stress relaxation layer in an evaluation test of Example 2.
【図４】実施例２の評価試験における，応力緩和層と貴
金属チップの接合部の酸化状態を示す説明図。FIG. 4 is an explanatory view showing an oxidized state of a joint between a stress relaxation layer and a noble metal tip in an evaluation test of Example 2.
１．．．貴金属チップ， ２０．．．絶縁碍子， ２５．．．ハウジング， ３．．．接地電極， ４．．．中心電極， ５．．．応力緩和層， ５１，５２．．．酸化物， 1. . . Precious metal tip, 20. . . Insulator, 25. . . Housing, 3. . . Ground electrode, 4. . . Center electrode, 5. . . Stress relaxation layer, 51, 52. . . Oxide,
Claims (1)
極と，上記絶縁碍子の外周に固定したハウジングと，該
ハウジングに設けられ上記中心電極と対向させた接地電
極とよりなり，かつ上記中心電極と接地電極の少なくと
も一方の電極材料にはその発火部に白金又は白金合金よ
りなる貴金属チップを設けてなる内燃機関用スパークプ
ラグにおいて， 上記貴金属チップと上記電極材料との間には応力緩和層
を介在させてなり，かつ上記応力緩和層は，クロム８〜
２０重量％と，アルミニウム，ニッケル，モリブデン，
銅，チタン，ニオブ，ジルコニウム及びセレンの中の１
種以上からなる添加物０．１〜５重量％とを含有する鉄
合金により構成されていることを特徴とする内燃機関用
スパークプラグ。An insulator, a center electrode held by the insulator, a housing fixed to an outer periphery of the insulator, a ground electrode provided on the housing and opposed to the center electrode, and the center electrode is provided. In a spark plug for an internal combustion engine, wherein a noble metal tip made of platinum or a platinum alloy is provided at a firing portion of at least one of an electrode material and a ground electrode, a stress relaxation layer is provided between the noble metal tip and the electrode material. And the stress relaxation layer is made of chromium 8
20% by weight , aluminum, nickel, molybdenum,
1 of copper, titanium, niobium, zirconium and selenium
A spark plug for an internal combustion engine, comprising an iron alloy containing 0.1 to 5% by weight of an additive composed of at least one kind .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03433792A JP3196288B2 (en) | 1992-01-23 | 1992-01-23 | Spark plug for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03433792A JP3196288B2 (en) | 1992-01-23 | 1992-01-23 | Spark plug for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05205848A JPH05205848A (en) | 1993-08-13 |
| JP3196288B2 true JP3196288B2 (en) | 2001-08-06 |
Family
ID=12411333
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03433792A Expired - Fee Related JP3196288B2 (en) | 1992-01-23 | 1992-01-23 | Spark plug for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3196288B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101191107B1 (en) | 2005-11-18 | 2012-10-15 | 페더럴-모걸 코오포레이숀 | Method of forming a spark plug with multi-layer firing tip |
-
1992
- 1992-01-23 JP JP03433792A patent/JP3196288B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05205848A (en) | 1993-08-13 |
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