JPH0544149B2 - - Google Patents
Info
- Publication number
- JPH0544149B2 JPH0544149B2 JP8387783A JP8387783A JPH0544149B2 JP H0544149 B2 JPH0544149 B2 JP H0544149B2 JP 8387783 A JP8387783 A JP 8387783A JP 8387783 A JP8387783 A JP 8387783A JP H0544149 B2 JPH0544149 B2 JP H0544149B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- discharge
- thermal stress
- base material
- platinum
- 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
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 50
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 43
- 239000000463 material Substances 0.000 claims description 34
- 230000008646 thermal stress Effects 0.000 claims description 28
- 229910052697 platinum Inorganic materials 0.000 claims description 22
- 229910052759 nickel Inorganic materials 0.000 claims description 20
- 229910001260 Pt alloy Inorganic materials 0.000 claims description 9
- 238000002485 combustion reaction Methods 0.000 claims description 7
- 239000000956 alloy Substances 0.000 description 9
- 229910045601 alloy Inorganic materials 0.000 description 8
- 239000010953 base metal Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 239000012212 insulator Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 4
- 229910000990 Ni alloy Inorganic materials 0.000 description 3
- 229910001055 inconels 600 Inorganic materials 0.000 description 3
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 229910000575 Ir alloy Inorganic materials 0.000 description 2
- 229910018487 Ni—Cr Inorganic materials 0.000 description 2
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 150000003057 platinum Chemical class 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910002835 Pt–Ir Inorganic materials 0.000 description 1
- 229910001080 W alloy Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Landscapes
- Spark Plugs (AREA)
Description
【発明の詳細な説明】
本発明は自動車などの内燃機関に用いて好都合
な点火プラグに関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spark plug conveniently used in internal combustion engines such as automobiles.
従来この種の点火プラグとして、中心電極の火
花放電端に、耐熱、耐消耗性の白金より成る放電
部層を抵抗溶接法等で固定し、中心電極の火花放
電極の消耗を防ぐようになして長寿命化を図つた
ものがある。 Conventionally, in this type of spark plug, a discharge layer made of heat-resistant and wear-resistant platinum was fixed to the spark discharge end of the center electrode using resistance welding to prevent wear and tear on the spark discharge end of the center electrode. There are some products that have a longer lifespan.
しかしながら、従来の上記点火プラグによれ
ば、放電部層が脱落することが往々にして現われ
るという問題を有している。 However, the conventional spark plug has a problem in that the discharge layer often falls off.
そこで、本発明者はその放電部層の脱落の傾向
を調査したところ、放電部層と中心電極との接合
部に亀裂を生じており、この亀裂の部位で放電部
層が脱落していた。 Therefore, the present inventor investigated the tendency of the discharge layer to fall off, and found that a crack had occurred at the joint between the discharge layer and the center electrode, and the discharge layer had fallen off at the cracked site.
このことは、放電部層の白金と中心電極の母材
金属であるニツケルとの間の線膨張率の相違によ
る熱応力が大きく起因していると思われる。 This is thought to be largely caused by thermal stress due to the difference in linear expansion coefficient between platinum of the discharge layer and nickel, the base metal of the center electrode.
本発明は上記の点に鑑み、火花放電間〓を形成
する電極の母材金属と放電部層との間に、該母材
金属のニツケルを少なくとも含み白金合金より成
る熱応力緩和層を少なくとも２層として配置した
ことにより、放電部層の脱落を熱応力緩和層にて
抑止できる内燃機関用点火プラグを提供すること
を目的とするものである。 In view of the above points, the present invention provides at least two thermal stress relaxation layers containing at least nickel as the base metal and made of a platinum alloy between the base metal of the electrode forming the spark discharge gap and the discharge layer. It is an object of the present invention to provide a spark plug for an internal combustion engine that can prevent the discharging layer from falling off due to the thermal stress relaxation layer being arranged as a layer.
以下本発明を具体的実施例により詳細に説明す
る。第１図、第２図において１はアルミナ磁器よ
りなる絶縁碍子で、中心に軸穴１ａが設けてあ
る。２は炭素鋼よりなる中軸で、絶縁碍子１の軸
穴１ａのうち上部に挿通してある。３は円筒状の
ハウジングで、耐熱、耐蝕性の金属で構成してあ
り、このハウジング３の内側にリング状気密パツ
キン４およびかしめリング５を介して上記絶縁碍
子１が固定してある。なおハウジング３には内燃
機関のシリンダブロツクに固定するためのネジ部
３ａが設けてある。６は中心電極であり、母材金
属としてニツケル−クロム（Ni−Cr）合金もし
くはインコネル600（商品名）から構成してある。
７は本発明の要部である３層タイプの白金層であ
り、中心電極６の先端に抵抗溶接法により接合し
てある。この３層タイプの白金層７は放電部層７
ａと熱応力緩和層７ｂ，７ｃから成つている。放
電部層７ａは白金合金、例えば白金（Pt）70重
量％乃至90重量％、イリジウム（Ir）30重量％乃
至10重量％から成り、熱応力緩和層７ｂは白金と
卑金属の合金、例えばPt90重量％、ニツケル10
重量％、熱応力緩和層７ｃはPt80重量％、ニツ
ケル20重量％から成つている。８は耐熱、耐蝕性
金属からなる接地電極で、中心電極６と同様の母
材金属で構成してある。９は白金チツプ層で、接
地電極８に抵抗溶接法により接合されている。こ
の白金チツプ層９は上記放電部層７ａと同様の
Pt合金で構成してある。１０は絶縁碍子１の軸
穴１ａ内に封着した導電性ガラスシール層であ
り、銅粉末と低融点ガラスとの混合物から構成さ
れており、このシール層１０で中軸２と中心電極
６とを電気的に接続すると共に、両者を絶縁碍子
１の軸穴１ａに移動なきよう固定してある。 The present invention will be explained in detail below using specific examples. In FIGS. 1 and 2, 1 is an insulator made of alumina porcelain, and a shaft hole 1a is provided in the center. Reference numeral 2 denotes a center shaft made of carbon steel, which is inserted into the upper part of the shaft hole 1a of the insulator 1. Reference numeral 3 denotes a cylindrical housing, which is made of heat-resistant and corrosion-resistant metal. The insulator 1 is fixed to the inside of the housing 3 via a ring-shaped airtight packing 4 and a caulking ring 5. The housing 3 is provided with a threaded portion 3a for fixing it to a cylinder block of an internal combustion engine. Reference numeral 6 denotes a center electrode, which is made of a nickel-chromium (Ni-Cr) alloy or Inconel 600 (trade name) as a base metal.
Reference numeral 7 denotes a three-layer type platinum layer, which is an important part of the present invention, and is joined to the tip of the center electrode 6 by resistance welding. This three-layer type platinum layer 7 is the discharge part layer 7.
a and thermal stress relaxation layers 7b and 7c. The discharge layer 7a is made of a platinum alloy, for example, 70% to 90% by weight of platinum (Pt) and 30% to 10% by weight of iridium (Ir), and the thermal stress relaxation layer 7b is made of an alloy of platinum and a base metal, for example, 90% by weight of Pt. %, Nickel 10
The thermal stress relaxation layer 7c is composed of 80% by weight of Pt and 20% by weight of nickel. A ground electrode 8 is made of a heat-resistant and corrosion-resistant metal, and is made of the same base metal as the center electrode 6. 9 is a platinum chip layer, which is joined to the ground electrode 8 by resistance welding. This platinum chip layer 9 is similar to the discharge layer 7a.
It is made of Pt alloy. A conductive glass seal layer 10 is sealed in the shaft hole 1a of the insulator 1, and is made of a mixture of copper powder and low-melting glass. In addition to being electrically connected, both are fixed in the shaft hole 1a of the insulator 1 so as not to move.
なお、上記３重層７は、放電部層７ａの素材と
緩和層７ｂ，７ｃの素材とを重ねて圧延し、熱処
理後にプレスにて打抜いて製造する。 The triple layer 7 is manufactured by stacking and rolling the material of the discharge layer 7a and the materials of the relaxation layers 7b and 7c, and punching them out with a press after heat treatment.
従来例では、白金製放電部層を中心電極およ
び／または接地電極の放電面に使用することによ
り、該電極の耐消耗性の大幅な向上を図つてい
る。しかし、放電部層は白金とイリジウムの合
金、もしくは白金とタングステンの合金、もしく
は白金とイリジウムに若干のNiを点火した合金
から成つていて単一のチツプで構成してあり、そ
の線膨張係数は約８〜９×10-6／℃であり、放電
部層とは約５×10-6／℃の差がある。ところが、
点火プラグは高負荷、低負荷と種々の運転条件で
使用され、即ち高温、低温が繰返され、この冷熱
繰返しと線膨張差により放電部層と両電極との間
でそれぞれ繰返し熱応力を受け、一般的には第３
図Ａのａに示すように横亀裂が発生したり、第３
図Ｂのｂに示すように接合面の酸化が生じ、最後
は放電部層７が脱落する。なお、接地電極８側の
白金チツプは横亀裂が生じるが、接地電極８は中
心電極６より高温となるため、この電極自体の消
耗により白金チツプ９自体は脱落する。この対策
には種々の方法が考えられるが、非常に温度が高
くなるエンジンや、プラグの電極温度が高くなる
例えば第４図に示すような電極構成（従来より３
〜７mmほど突出したプラグ）には必ずしも有効と
いえない。 In the prior art, a platinum discharge layer is used on the discharge surface of the center electrode and/or the ground electrode to significantly improve the wear resistance of the electrode. However, the discharge layer is composed of a single chip made of an alloy of platinum and iridium, an alloy of platinum and tungsten, or an alloy of platinum and iridium with a small amount of Ni ignited, and its linear expansion coefficient is about 8 to 9×10 -6 /°C, and there is a difference of about 5×10 -6 /°C from the discharge layer. However,
Spark plugs are used under various operating conditions such as high load and low load, that is, high and low temperatures are repeated, and due to the repeated cooling and heating and the difference in linear expansion, the spark plugs are subjected to repeated thermal stress between the discharge layer and both electrodes. Generally the third
As shown in Figure A, horizontal cracks may occur, or third cracks may occur.
As shown in FIG. Note that horizontal cracks occur in the platinum chip on the ground electrode 8 side, but since the ground electrode 8 becomes hotter than the center electrode 6, the platinum chip 9 itself falls off due to wear of this electrode itself. Various methods can be considered to counter this problem, such as the electrode configuration shown in Figure 4 (conventional 3
It is not necessarily effective for plugs that protrude by ~7 mm.
そこで、本発明は電極温度が上昇した場合にも
上記横亀裂が生じないようにするものである。そ
のためには、熱応力を減ずる必要がある。この熱
応力を減ずるため、上記放電部層７の部分を線膨
張が母材６ａのNi合金とできるだけ合うようPt
とNiとの合金から構成した熱応力緩和層７ｂ，
７ｃと白金合金製の放電部層７ａとに分けた。こ
こで、熱応力緩和層７ｂ，７ｃは前述したPt−
Ni合金から構成してある。一方、放電部層７ａ
は前述したPt−Ir合金、もしくはこの合金組成に
２重量％乃至５重量％のNiが添加された合金か
ら構成してある。かかる合金組成により、母材６
ａと放電部層７ａとの間の線膨張は徐々に変化し
ている。即ち、母材６ａと放電部層７ａとの間に
これらと中間の線膨張係数を有する熱応力緩和層
７ｂ，７ｃを設けることにより、熱応力を大幅に
減少し、前記横亀裂および接合面の酸化の発生を
抑制することができた。 Therefore, the present invention is intended to prevent the above-mentioned transverse cracks from occurring even when the electrode temperature rises. For this purpose, it is necessary to reduce thermal stress. In order to reduce this thermal stress, the discharge section layer 7 is made of Pt so that its linear expansion matches that of the Ni alloy of the base material 6a as much as possible.
A thermal stress relaxation layer 7b composed of an alloy of and Ni,
7c and a discharge layer 7a made of platinum alloy. Here, the thermal stress relaxation layers 7b and 7c are the Pt-
It is made of Ni alloy. On the other hand, the discharge layer 7a
is composed of the aforementioned Pt-Ir alloy or an alloy in which 2% to 5% by weight of Ni is added to this alloy composition. With this alloy composition, the base material 6
The linear expansion between a and the discharge layer 7a changes gradually. That is, by providing thermal stress relaxation layers 7b and 7c having linear expansion coefficients intermediate between the base material 6a and the discharge layer 7a, thermal stress can be significantly reduced and the lateral cracks and bonding surfaces can be reduced. It was possible to suppress the occurrence of oxidation.
第５図の線図ａに従来の構成の点火プラグの中
心電極温度に対する前記横亀裂及び接合面の酸化
の状況を示す。評価は、排気量2600c.c.、水冷４サ
イクルエンジンにて１分アイドル→１分W.O.T
の冷熱サイクル実験を実施した結果である。な
お、従来のプラグは基本構成は第１図と同じであ
り、中心電極母材に20Ir−2Ni−残部Ptの組成の
白金チツプを0.3mmの厚みで接合したものである。
この従来例は電極温度800℃近傍が限界であり、
さらに厳しい条件では使用できない。これは、第
６図の線図ａに示す如く、母材６と放電チツプ７
（上記白金チツプ）との線膨張係数差があまりに
も大きいために熱応力を生じているのが原因であ
る。第６図の線図ｂに本発明の２種の緩和層７
ｂ，７ｃを設けた場合の線膨張係数の推移を示し
ている。即ち、放電部側緩和層７ｂは90重量％
Pt−10重量％Ni、母材側緩和層７ｃは80重量％
Pt−20重量％Niの合金組成を有している。なお、
各層７ｂ，７ｃの厚さは共に0.1mmでしなる。こ
の線図ｂによると、従来に比べ緩やかに線膨張係
数が変化しているのがわかる。 Diagram a in FIG. 5 shows the lateral cracks and oxidation of the joint surface with respect to the temperature of the center electrode of a conventional spark plug. Evaluation is 1 minute idle → 1 minute WOT with a water-cooled 4-stroke engine with a displacement of 2600 c.c.
These are the results of a cooling and heating cycle experiment. The basic structure of the conventional plug is the same as that shown in FIG. 1, in which a platinum chip having a composition of 20Ir-2Ni with the balance Pt is bonded to a center electrode base material with a thickness of 0.3 mm.
The limit for this conventional example is an electrode temperature of around 800°C.
It cannot be used under more severe conditions. As shown in diagram a in FIG. 6, the base material 6 and the discharge chip 7
This is because the difference in the coefficient of linear expansion between the metal and the platinum chip is so large that thermal stress is generated. Diagram b in FIG. 6 shows two types of relaxation layers 7 of the present invention.
7b and 7c are shown, showing the change in linear expansion coefficient. That is, the discharge part side relaxation layer 7b has a content of 90% by weight.
Pt-10wt%Ni, base material side relaxation layer 7c is 80wt%
It has an alloy composition of Pt-20%Ni by weight. In addition,
The thickness of each layer 7b and 7c is both 0.1 mm. According to this diagram b, it can be seen that the coefficient of linear expansion changes more slowly than in the past.
第５図の線図ｂは、この構成において、緩和層
厚さt1，t2共に0.1mmとしたときの状況を示したも
のである。ここで、第６図における母材６ａはイ
ンコネル600（商品名）相当で、15.5Cr−8Fe−
0.5Mn−Ni残量で、放電部層７ａは、78重量％
Pt−20重量％Ir−２重量％Niを使用した。 Diagram b in FIG. 5 shows the situation when the relaxation layer thicknesses t 1 and t 2 are both 0.1 mm in this configuration. Here, the base material 6a in FIG. 6 is equivalent to Inconel 600 (trade name), and is 15.5Cr-8Fe-
With a remaining amount of 0.5Mn-Ni, the discharge layer 7a has a content of 78% by weight.
Pt-20% by weight Ir-2% by weight Ni was used.
第７図は、放電部側緩和層７ｂの材質と母材側
緩和層７ｃの材質との組合せ実験を行つた結果で
ある。評価は第５図と同様であるが、温度は点火
プラグの機能限界である950℃電極温度で実施し
た。緩和層材質は、95重量％〜50重量％Ni間で
実施した。なお、Ni含有量は、50重量％以上と
なる酸化が著しいため、50重量％までとした。こ
の図から明らかな如く、母材側緩和層７ｃは、放
電部側緩和層７ｂよりもNi含有量が５重量％程
度多くなつているものが良好であり、Ni含有量
の多い緩和層材料においては、使用範囲が狭くな
り実用上不利になる。火花消耗、酸化消耗の点で
最も望ましいのは、放電部緩和層95〜85重量％
Pt−５〜15重量％Niと母材側緩和層75〜80重量
％Pt−20〜25重量％Niとの組合せである。なお、
これは、２つの緩和層厚さt1，t2を共に0.1mmとし
た例である。 FIG. 7 shows the results of a combination experiment of the material of the discharge part side relaxation layer 7b and the material of the base material side relaxation layer 7c. The evaluation was the same as in Figure 5, but the temperature was 950°C, which is the functional limit of the spark plug. The material of the relaxation layer was between 95% by weight and 50% by weight Ni. Note that the Ni content was set to 50% by weight or less since oxidation is significant when it exceeds 50% by weight. As is clear from this figure, the base material side relaxation layer 7c is good when the Ni content is about 5% higher than that of the discharge part side relaxation layer 7b, and in the relaxation layer material with a high Ni content, , the range of use is narrowed and it is disadvantageous in practice. In terms of spark consumption and oxidation consumption, the most desirable discharge part relaxation layer is 95 to 85% by weight.
This is a combination of Pt-5 to 15 wt% Ni and base material side relaxation layer 75 to 80 wt% Pt-20 to 25 wt% Ni. In addition,
This is an example in which the two relaxation layer thicknesses t 1 and t 2 are both 0.1 mm.
次に、２つの緩和層の厚さの組合せについての
例を第８図に示す。第８図中、○印は、放電部側
緩和層材料として90重量％Pt−10重量％Ni、母
材側緩和層材料として80重量％Pt−20重量％Ni
を用いたもの、△印は、同様に放電部側緩和層材
料として80重量％Pt−20重量％Ni、母材側緩和
層材料として70重量％Pt−30重量％Niを用いた
ものであり、ほぼ同一傾向にある。放電部側緩和
装置厚さt1と母材側緩和層厚さt2との関係は、t1
＜0.1mmの場合、t2≧0.1mm、かつt1≧0.1mmの場合、
t2≧0.05mmが望ましい組合せである。 Next, FIG. 8 shows an example of a combination of the thicknesses of two relaxation layers. In Fig. 8, the circles indicate 90% Pt-10% Ni by weight as the material for the relaxation layer on the discharge part side, and 80% Pt-20% by weight as the material for the relaxation layer on the base metal side.
Similarly, the material using 80 wt% Pt-20 wt% Ni as the relaxation layer material on the discharge part side and 70 wt% Pt-30 wt% Ni as the material of the relaxation layer on the base metal side are used. , the trend is almost the same. The relationship between the discharge part side relaxation device thickness t 1 and the base material side relaxation layer thickness t 2 is t 1
<0.1mm, t 2 ≧0.1mm, and t 1 ≧0.1mm,
A desirable combination is t 2 ≧0.05mm.
ところで、前記放電部層７ａは火花放電による
消耗だけを考えれば、Ptのみでよい。しかし、
Ptのみであると、第９図Ａに示すごとく、放電
部層７ａに縦亀裂ｂを生じる。この亀裂を押さえ
るためにはIrを添加するこがよく、この亀裂発生
率をIrの添加量との関係を第９図Ｂに示す。同図
より明らかなごとく、Irの添加量は10重量％乃至
30重量％がよく、より好ましい範囲は15重量％乃
至30重量％がよい。30重量％を越えると、放電部
層７ａを構成する材料自体の硬度が上昇し、所望
形状に加工できない。なお、上記Irの量はPtと合
計して100重量％の値である。 By the way, the discharge layer 7a may be made of only Pt, considering only wear due to spark discharge. but,
When only Pt is used, vertical cracks b occur in the discharge layer 7a, as shown in FIG. 9A. In order to suppress these cracks, it is preferable to add Ir, and the relationship between the crack occurrence rate and the amount of Ir added is shown in FIG. 9B. As is clear from the figure, the amount of Ir added is between 10% by weight and
The amount is preferably 30% by weight, and the more preferable range is 15% to 30% by weight. If it exceeds 30% by weight, the hardness of the material constituting the discharge layer 7a increases, making it impossible to form it into the desired shape. Note that the above amount of Ir is 100% by weight in total with Pt.
次に、接地電極８に設ける白金チツプ層９は、
該電極８の母材であるNi合金の線膨張率に近似
させるとともに耐消耗性の両面を狙つて、Niの
含有量を５重量％乃至60重量％にするのがよく、
より好ましくは５重量％乃至20重量％がよい。こ
の白金チツプ層９において、Niの含有量が増す
と、却つて酸化による消耗が進行する。ちなみ
に、接地電極８は中心電極６に比較して約100℃
程度温度が高く、白金チツプ層９中のNiの酸化
の進行度合が中心電極６側より速いため、白金チ
ツプ層９におけるNiの含有量は少なめがよい。 Next, the platinum chip layer 9 provided on the ground electrode 8 is
In order to approximate the coefficient of linear expansion of the Ni alloy that is the base material of the electrode 8 and to improve wear resistance, the Ni content is preferably 5% to 60% by weight.
More preferably, it is 5% to 20% by weight. As the Ni content increases in this platinum chip layer 9, consumption due to oxidation progresses. By the way, the temperature of the ground electrode 8 is about 100℃ compared to the center electrode 6.
Since the temperature is relatively high and the progress of oxidation of Ni in the platinum chip layer 9 is faster than that on the center electrode 6 side, the content of Ni in the platinum chip layer 9 is preferably small.
本発明は上述の実施例に限定されず、以下のご
とく種々の変形が可能である。 The present invention is not limited to the above-described embodiments, but can be modified in various ways as described below.
(1) 接地電極９が正極性となる点火回路を用いた
場合には、この接地電極９の方に中心電極６で
用いた、放電部層７ａと２つの熱応力緩和層７
ｂ，７ｃとの組合せを採用すればよい。(1) When using an ignition circuit in which the ground electrode 9 has positive polarity, the discharge layer 7a and the two thermal stress relaxation layers 7 used in the center electrode 6 are attached to the ground electrode 9.
A combination with b and 7c may be adopted.
(2) 中心電極６と接地電極９との両方に、放電部
層７ａ、熱応力緩和層７ｂ，７ｃを設けてもよ
い。(2) Both the center electrode 6 and the ground electrode 9 may be provided with the discharge layer 7a and the thermal stress relaxation layers 7b and 7c.
(3) 中心電極６を単品の状態で例えば1000℃、３
時間という熱処理を施すことにより、熱応力緩
和層７ｃと中心電極６の母材６ａとの接合部に
合金層部を形成してもよい。これにより、熱応
力の緩和を一層図ることができる。なお、上記
合金層の厚さは少なくとも10μが望ましい。(3) For example, heat the center electrode 6 as a single item at 1000°C, 3
An alloy layer portion may be formed at the joint portion between the thermal stress relaxation layer 7c and the base material 6a of the center electrode 6 by performing heat treatment for a certain period of time. Thereby, thermal stress can be further alleviated. Note that the thickness of the alloy layer is preferably at least 10 μm.
(4) 中心電極６の先端の径を例えば0.7mm乃至1.2
mmとして先細形状にしてもよい。かかる形状に
より、着火性の向上を図ることができる。(4) For example, set the diameter of the tip of the center electrode 6 to 0.7 mm to 1.2 mm.
It may be tapered as mm. Such a shape can improve ignitability.
(5) 中心電極６側の３重白金層７の大きさは直径
0.9mm、肉厚0.4mm（約5.5mg±２mgの重畳）がよ
く、接地電極８側の白金チツプ層９の大きさは
直径0.7mm、肉厚0.3mm（約2.5mg±１mgの重畳）
がよい。この程度の寸法、重畳であれば、価格
的に満足できるとともに寿命的にも満足でき
る。(5) The size of the triple platinum layer 7 on the center electrode 6 side is the diameter
The platinum chip layer 9 on the ground electrode 8 side has a diameter of 0.7 mm and a thickness of 0.3 mm (approx. 2.5 mg ± 1 mg overlap).
Good. With dimensions and overlaps of this order, it is satisfactory in terms of cost and life.
(6) 中心電極６の母材は93重量％Ni、２重量％
Cr、３重量％Mn、２重量％Siで構成してもよ
い。(6) The base material of the center electrode 6 is 93% Ni by weight and 2% by weight
It may be composed of Cr, 3% by weight Mn, and 2% by weight Si.
(7) 各層７ａ，７ｂ，７ｃ，９には不可避的不純
物が入つてもよい。(7) Each layer 7a, 7b, 7c, and 9 may contain unavoidable impurities.
(8) 第１０図に示す如く、熱応力緩和層は３層と
し、７ｂに90重量Pt−10重量％Ni、７ｃに80
重量％Pt−20重量％Ni、７ｄに70重量％Pt−
30重量％Niとした構成にしても前述と同様の
効果は得られる。(8) As shown in Figure 10, the thermal stress relaxation layer has three layers: 90wt Pt-10wt% Ni for 7b and 80wt% Ni for 7c.
wt% Pt-20 wt% Ni, 70 wt% Pt- on 7d
The same effect as described above can be obtained even if the composition is made of 30% by weight Ni.
以上述べたごとく本発明によれば、電極に設け
た白金製放電部層と上記電極の母材との間に、該
母材に含まれるニツケルを含有した白金製熱応力
緩和層を介在せしめたから、放電部層と電極の母
材との間の熱応力を緩和層で緩和することがで
き、従つて放電部層の脱落を抑止できるという優
れた効果を奏する。 As described above, according to the present invention, a platinum thermal stress relaxation layer containing nickel contained in the base material is interposed between the platinum discharge layer provided on the electrode and the base material of the electrode. This provides an excellent effect in that the thermal stress between the discharge layer and the base material of the electrode can be relaxed by the relaxation layer, and therefore the discharge layer can be prevented from falling off.
第１図は本発明点火プラグの一実施例を示す半
断面図、第２図は第１図の要部を拡大して示す断
面図、第３図Ａ，Ｂは従来の説明に供する部分断
面図、第４図は本発明の説明に供する半断面図、
第５図Ａ，Ｂおよび第６図は本発明の説明に供す
る特性図、第７図および第８図、ならびに第９図
Ａ，Ｂは本発明の説明に供する特性図、第１０図
は本発明の他の実施例を示す断面図である。
６……中心電極、７……３重白金層、７ａ……
放電部層、７ｂ，７ｃ……熱応力緩和層。
Fig. 1 is a half-sectional view showing an embodiment of the spark plug of the present invention, Fig. 2 is an enlarged sectional view showing the main part of Fig. 1, and Fig. 3 A and B are partial cross-sections for explaining the conventional FIG. 4 is a half-sectional view for explaining the present invention,
5A, B, and 6 are characteristic diagrams for explaining the present invention, FIGS. 7, 8, and 9A, B are characteristic diagrams for explaining the present invention, and FIG. 10 is a characteristic diagram for explaining the present invention. FIG. 7 is a sectional view showing another embodiment of the invention. 6... Center electrode, 7... Triple platinum layer, 7a...
Discharge layer, 7b, 7c...thermal stress relaxation layer.
Claims (1)
間隙を形成し、前記一方の電極に白金を含む耐消
耗性の放電部層を設けた内燃機関用点火プラグで
あつて、 前記放電部層と前記一方の電極の母材との間
に、該母材を構成するニツケルを含有した白金合
金より成る少なくとも２つの熱応力緩和層が配置
してあり、該２つの熱応力緩和層のうち前記放電
部層に接する側は、前記母材に接する側に比べて
ニツケルの含有量が少なくしてある内燃機関用点
火プラグ。 ２ 前記放電部層に接する側の前記熱応力緩和層
内に占めるニツケルの含有量をＡ、前記中心電極
の母材に接する側の前記熱応力緩和層内に占める
ニツケルの含有量をＢとしたとき、次のいずれか
を満足している特許請求の範囲第１項記載の内燃
機関用点火プラグ。 イ；5wt％≦Ａ≦10wt％のとき、 20wt％≦Ｂ≦50wt％ ロ；10wt％≦Ａ≦20wt％のとき、 25wt％≦Ｂ≦50wt％ ハ；20wt％≦Ａ≦30wt％のとき、 30wt％≦Ｂ≦50wt％ ニ；30wt％≦Ａ≦40wt％のとき、 35wt％≦Ｂ≦50wt％ ホ；40wt％≦Ａ≦10wt％のとき、 45wt％≦Ｂ≦50wt％ ３ 前記放電部層に接する側の前記熱応力緩和層
の厚さ寸法をt1、前記中心電極の母材に接する側
の前記熱応力緩和層の厚さ寸法をt2としたとき、 t1＜0.1mmのときはt2≧0.1mm t1＜0.1mmのときはt2≧0.05mm である特許請求の範囲第２項記載の内燃機関用点
火プラグ。[Scope of Claims] 1. A spark plug for an internal combustion engine, wherein a spark discharge gap is formed between at least two opposing electrodes, and a wear-resistant discharge layer containing platinum is provided on one of the electrodes, comprising: At least two thermal stress relieving layers made of a platinum alloy containing nickel constituting the base material are disposed between the discharge layer and the base material of the one electrode, and the two thermal stress relieving layers The spark plug for an internal combustion engine has a side in contact with the discharge layer that has a lower nickel content than the side in contact with the base material. 2 The content of nickel in the thermal stress relieving layer on the side in contact with the discharge layer is A, and the content of nickel in the thermal stress relieving layer on the side in contact with the base material of the center electrode is B. A spark plug for an internal combustion engine according to claim 1, which satisfies any of the following: A; When 5wt%≦A≦10wt%, 20wt%≦B≦50wt% B; When 10wt%≦A≦20wt%, 25wt%≦B≦50wt% C; When 20wt%≦A≦30wt%, 30wt%≦B≦50wt% D; When 30wt%≦A≦40wt%, 35wt%≦B≦50wt% E; When 40wt%≦A≦10wt%, 45wt%≦B≦50wt% 3. The discharge part layer When the thickness dimension of the thermal stress relaxation layer on the side in contact with is t 1 and the thickness dimension of the thermal stress relaxation layer on the side in contact with the base material of the center electrode is t 2 , when t 1 <0.1 mm The spark plug for an internal combustion engine according to claim 2, wherein t 2 ≧0.1mm and t 2 ≧0.05mm when t 1 <0.1mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8387783A JPS59209292A (en) | 1983-05-12 | 1983-05-12 | Ignition plug for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8387783A JPS59209292A (en) | 1983-05-12 | 1983-05-12 | Ignition plug for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59209292A JPS59209292A (en) | 1984-11-27 |
| JPH0544149B2 true JPH0544149B2 (en) | 1993-07-05 |
Family
ID=13814884
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8387783A Granted JPS59209292A (en) | 1983-05-12 | 1983-05-12 | Ignition plug for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59209292A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102014223792A1 (en) * | 2014-11-21 | 2016-05-25 | Robert Bosch Gmbh | Spark plug electrode, process for its manufacture and spark plug |
-
1983
- 1983-05-12 JP JP8387783A patent/JPS59209292A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59209292A (en) | 1984-11-27 |
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