JPH11260531A - Spark plug for internal combustion engine - Google Patents
Spark plug for internal combustion engineInfo
- Publication number
- JPH11260531A JPH11260531A JP10314919A JP31491998A JPH11260531A JP H11260531 A JPH11260531 A JP H11260531A JP 10314919 A JP10314919 A JP 10314919A JP 31491998 A JP31491998 A JP 31491998A JP H11260531 A JPH11260531 A JP H11260531A
- Authority
- JP
- Japan
- Prior art keywords
- insulator
- resistor
- center electrode
- spark plug
- internal combustion
- 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.)
- Pending
Links
Landscapes
- Spark Plugs (AREA)
Abstract
Description
【０００１】[0001]
【技術分野】本発明は，自動車，コージェネレーショ
ン，ガス圧送用ポンプ等に使用する内燃機関用のスパー
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 for an internal combustion engine used for an automobile, a cogeneration system, a gas pressure pump, and the like.
【０００２】[0002]
【従来技術】コージェネレーション（ガス燃料を用いた
大型発電機），ガス圧送用ポンプ等に用いられる大型の
エンジンにおいては，例えばハウジングねじ外径が１８
ｍｍ，碍子頭部の直径が１４ｍｍ，中心電極の直径が
２．５ｍｍ，全体長さが１１５ｍｍという，大型のスパ
ークプラグが用いられる。このような大型のスパークプ
ラグにおいては，特にメンテナンス性の向上及びプラグ
交換費用の低減等のため，長寿命プラグが強く求められ
ている。何故ならば，上記コージェネレーション，ガス
圧送用ポンプに用いる内燃機関は，自動車のごとく間欠
的に運転するものではなく，常時運転し続けるものだか
らである。2. Description of the Related Art In a large engine used for a cogeneration (a large generator using gas fuel), a gas pump, or the like, for example, the outer diameter of a housing screw is 18 mm.
A large spark plug having a diameter of 14 mm, a diameter of the insulator head of 14 mm, a diameter of the center electrode of 2.5 mm, and an overall length of 115 mm is used. In such a large-sized spark plug, a long-life plug is strongly demanded, particularly in order to improve maintenance and reduce plug replacement cost. This is because the internal combustion engine used for the cogeneration and gas pressure pumps does not operate intermittently like an automobile, but always operates.
【０００３】上記スパークプラグ９０は，図７に示すご
とく絶縁碍子４の貫通孔４１内に抵抗体６９を介在させ
ている。上記絶縁碍子４は，一方に中心電極２，低融点
ガラス７０，及び導電性焼結物７１を，他方に端子電極
２１を配置しており，上記抵抗体６９は上記端子電極２
１との間に介在するスプリング２３により固定されてい
る。また，該絶縁碍子４を保持するハウジング５には接
地電極３，及び内燃機関に螺着するための取付ねじ部５
１が設けられている。また，上記中心電極２と接地電極
３との間には火花ギャップＧを有している。The spark plug 90 has a resistor 69 interposed in a through hole 41 of the insulator 4 as shown in FIG. The insulator 4 has a central electrode 2, a low-melting glass 70, and a conductive sintered body 71 on one side, and a terminal electrode 21 on the other side.
1 is fixed by a spring 23 interposed therebetween. A housing 5 for holding the insulator 4 has a ground electrode 3 and a mounting screw 5 for screwing to the internal combustion engine.
1 is provided. Further, a spark gap G is provided between the center electrode 2 and the ground electrode 3.
【０００４】上記スパークプラグ９０の長寿命を確保す
るためには，火花放電ギャップＧの拡大を抑制し，火花
放電に必要な要求電圧の上昇を抑制しなければならな
い。上記ギャップ拡大の抑制のため，図７に示すごと
く，耐消耗性に優れた貴金属材料又はその合金材料から
なる貴金属チップ２８が放電部材として使用されてい
る。In order to ensure a long life of the spark plug 90, it is necessary to suppress the expansion of the spark discharge gap G and to suppress an increase in required voltage required for spark discharge. As shown in FIG. 7, a noble metal tip 28 made of a noble metal material or an alloy thereof having excellent wear resistance is used as a discharge member to suppress the above-mentioned gap expansion.
【０００５】しかし，近年の大型ガスエンジンにおいて
は，特に燃費向上，排ガス低減のために燃焼効率の向
上，高圧縮，かつリンバーンによる運転が図られてい
る。そのため，スパークプラグ９０に対しては要求電圧
の上昇，熱負荷及び点火エネルギーの増大等，より厳し
い使用環境が強いられることとなっている。[0005] However, in recent large-sized gas engines, particularly, in order to improve fuel economy and reduce exhaust gas, combustion efficiency has been improved, high compression, and operation by Linburn has been attempted. For this reason, a more severe use environment such as an increase in required voltage, an increase in heat load and an increase in ignition energy is imposed on the spark plug 90.
【０００６】ところで，一般にスパークプラグにおいて
は，火花放電に起因する電波雑音を低減するために，絶
縁碍子の貫通孔内部には抵抗体が挿入されている。そし
て，該抵抗体は，その電波防止性能を充分に発揮させる
ため，火花ギャップに対しできるだけ近い位置に配さて
いる。In general, in a spark plug, a resistor is inserted inside a through hole of an insulator to reduce radio noise caused by spark discharge. The resistor is disposed at a position as close as possible to the spark gap in order to sufficiently exhibit its radio wave prevention performance.
【０００７】[0007]
【解決しようとする課題】しかしながら，上記従来のス
パークプラグ９０には以下のような問題がある。即ち，
スパークプラグ９０は，上述のごとく大型ガスエンジン
に特有の，厳しい使用環境下で使用される。そのため，
抵抗体成分が部分的に焼損し抵抗値上昇を引き起こす。
その結果，場合によっては，エンジン失火に至ることも
ある。However, the conventional spark plug 90 has the following problems. That is,
As described above, the spark plug 90 is used in a severe use environment specific to a large gas engine. for that reason,
The resistor component is partially burned, causing an increase in the resistance value.
As a result, in some cases, engine misfire may occur.
【０００８】例えば，現在大型ガスエンジンに採用され
ているスパークプラグ９０には，抵抗体６９として，予
め抵抗粉末を焼成し固めたソリッド抵抗体を使用してい
るものがある。該ソリッド抵抗体は，常温にて碍子内部
へ挿入され，スプリング２３と端子電極２１とにより固
定されている。For example, some spark plugs 90 currently used in large gas engines use a solid resistor obtained by firing and solidifying a resistor powder in advance as the resistor 69. The solid resistor is inserted into the insulator at normal temperature and fixed by the spring 23 and the terminal electrode 21.
【０００９】この場合，上述の厳しい使用環境下では，
上記抵抗体６９の両端部に配置される導電性焼結物７１
及びスプリング４１との両接触部における接触抵抗が徐
々に上昇する。その結果抵抗体６９が焼損し，エンジン
が失火しやすい。或いは，中心電極２と碍子の貫通孔４
１との間隙から伝わる高圧力のガスにより，シール性が
劣化しやすいという問題を生ずる。In this case, under the above-mentioned severe use environment,
Conductive sintered material 71 arranged at both ends of resistor 69
And the contact resistance at both contact portions with the spring 41 gradually increases. As a result, the resistor 69 is burned, and the engine is easily misfired. Alternatively, the center electrode 2 and the through hole 4 of the insulator
There is a problem that the high-pressure gas transmitted from the gap between the first and the second seals tends to deteriorate the sealing performance.
【００１０】そこで，他の抵抗体として，硼珪酸系ガラ
ス，ジルコニア，カーボンブラック等の，ガラス粉末−
セラミック粉末−カーボン系の抵抗材料を，高温炉中で
溶着し，円柱状に成形したものもある。しかし，この円
柱成形体を用いる場合でも，抵抗体が火花ギャップに近
い位置に配置された場合には，燃焼室から受ける熱によ
り長時間高温に晒されるため，抵抗値が上昇し，エンジ
ン失火に至るという問題がある。Therefore, as another resistor, a glass powder such as borosilicate glass, zirconia, or carbon black is used.
In some cases, a ceramic powder-carbon-based resistance material is welded in a high-temperature furnace and formed into a cylindrical shape. However, even when this cylindrical molded body is used, if the resistor is placed close to the spark gap, it will be exposed to high temperatures for a long time due to the heat received from the combustion chamber, causing the resistance to rise and causing engine misfire. There is a problem of reaching.
【００１１】本発明は，かかる従来の問題点に鑑みてな
されたもので，抵抗体の性能を長期間安定的に維持する
ことができ，長寿命の，内燃機関用のスパークプラグを
提供しようとするものである。The present invention has been made in view of such a conventional problem, and an object thereof is to provide a spark plug for an internal combustion engine, which can stably maintain the performance of a resistor for a long period of time and has a long life. Is what you do.
【００１２】[0012]
【課題の解決手段】請求項１の発明は，絶縁碍子の貫通
孔内に抵抗体を介在させて，一方に中心電極を，他方に
端子電極を配置してなる上記絶縁碍子と，該絶縁碍子を
保持するハウジングと，該ハウジングに設けられた接地
電極とよりなり，また上記ハウジングには内燃機関に螺
着するための取付ねじ部を有し，上記中心電極と接地電
極との間には火花ギャップを有してなる内燃機関用のス
パークプラグにおいて，上記抵抗体は，抵抗材料を溶着
させてなる溶着柱状抵抗体を用いてなり，かつ，上記絶
縁碍子における上記中心電極を配置した側の碍子先端面
から，上記溶着柱状抵抗体における中心電極側の抵抗体
先端面までの先端間距離をＴｍｍ，上記絶縁碍子の碍子
脚部の長さをＫｍｍとしたとき，Ｔ≧１．５Ｋの関係を
有していることを特徴とする内燃機関用のスパークプラ
グにある。According to the first aspect of the present invention, there is provided the above insulator having a resistor interposed in a through hole of the insulator, one of which is provided with a center electrode, and the other is provided with a terminal electrode, and the insulator. And a ground electrode provided in the housing. The housing has a mounting screw for screwing to an internal combustion engine, and a spark is provided between the center electrode and the ground electrode. In a spark plug for an internal combustion engine having a gap, the resistor comprises a welded columnar resistor formed by welding a resistance material, and the insulator on the side of the insulator on which the center electrode is disposed. When the distance between the tip from the tip face to the tip face of the resistor on the center electrode side of the welded columnar resistor is Tmm, and the length of the insulator leg of the insulator is Kmm, the relationship of T ≧ 1.5K is as follows. That you have In the spark plug for an internal combustion engine and butterflies.
【００１３】本発明において最も注目すべき点は，上記
絶縁碍子における上記碍子先端面から，上記溶着柱状抵
抗体における抵抗体先端面までの先端間距離をＴｍｍ，
上記絶縁碍子の碍子脚部の長さをＫｍｍとしたとき，Ｔ
≧１．５Ｋの関係を有していることにある。The most remarkable point in the present invention is that the distance between the tip from the tip of the insulator of the insulator to the tip of the resistor of the welded columnar resistor is Tmm,
When the length of the insulator leg of the insulator is Kmm, T
≧ 1.5K.
【００１４】上記において，Ｔが１．５Ｋ未満の場合に
は，内燃機関の燃焼室内の熱が上記碍子脚部に伝わって
溶着柱状抵抗体と中心電極側ガラスシールとの接触部に
おける温度が高温となり，抵抗値の上昇，抵抗体の焼
損，エンジン失火となるおそれがある。なお，Ｔの上限
は，雑音防止性能の点からＫの３倍未満とすることが好
ましい。In the above, when T is less than 1.5 K, the heat in the combustion chamber of the internal combustion engine is transmitted to the insulator legs, and the temperature at the contact portion between the welded columnar resistor and the center electrode side glass seal becomes high. This may lead to an increase in the resistance value, burnout of the resistor, and misfire of the engine. Note that the upper limit of T is preferably less than three times K in view of noise prevention performance.
【００１５】次に，本発明の作用効果につき説明する。
本発明においては，上記碍子先端面から抵抗体先端面ま
での先端間距離Ｔが，上記碍子脚部の長さＫの１．５倍
以上となるように溶着柱状抵抗体を設置してある。その
ため，中心電極先端部の温度が，例えば７００℃という
高温になって，その熱が上記碍子脚部に伝わっても，該
碍子脚部の先端から溶着柱状抵抗体までの上記先端間距
離Ｔが大きいので，溶着柱状抵抗体と中心電極との接触
部における温度は高温とならない。Next, the operation and effect of the present invention will be described.
In the present invention, the welding columnar resistor is installed so that the distance T between the tip of the insulator and the tip of the resistor is 1.5 times or more the length K of the insulator leg. Therefore, even if the temperature of the tip of the center electrode becomes high, for example, 700 ° C., and the heat is transmitted to the insulator leg, the distance T between the tip from the tip of the insulator leg to the welding columnar resistor is reduced. Since it is large, the temperature at the contact portion between the welded columnar resistor and the center electrode does not become high.
【００１６】即ち，燃焼室内において，上記絶縁碍子の
碍子脚部に伝わる熱は，上記碍子脚部の先端において最
も高温度である。そして，本発明においては，この碍子
脚部の碍子先端面から抵抗体先端面までの先端間距離Ｔ
を，上記碍子脚部の長さＫの１．５倍以上としてある。
つまり，溶着柱状抵抗体と中心電極側ガラスシールとの
接触部は，碍子脚部の付け根よりも更に奥の方に位置し
ている。That is, in the combustion chamber, the heat transmitted to the insulator legs of the insulator has the highest temperature at the tip of the insulator legs. In the present invention, the distance T between the tip of the insulator leg to the tip of the resistor from the tip of the insulator to the tip of the resistor.
Is 1.5 times or more the length K of the insulator leg.
That is, the contact portion between the welded columnar resistor and the glass seal on the center electrode side is located further back than the root of the insulator leg.
【００１７】そのため，内燃機関における高温度の燃焼
熱が，上記溶着柱状抵抗体と中心電極側ガラスシールの
接触部に直接伝わらず，この接触部の温度は低くなる。
それ故，上記接触部における接触抵抗の上昇を抑制する
ことができ，溶着柱状抵抗体と中心電極側ガラスシール
との接触状態も安定に維持でき，抵抗体の焼損，エンジ
ン失火のおそれもない。Therefore, high-temperature combustion heat in the internal combustion engine is not directly transmitted to the contact portion between the welded columnar resistor and the glass seal on the center electrode side, and the temperature of this contact portion is reduced.
Therefore, an increase in contact resistance at the contact portion can be suppressed, the contact state between the welded columnar resistor and the center electrode side glass seal can be stably maintained, and there is no risk of burning of the resistor and engine misfire.
【００１８】また，本発明においては，抵抗体として，
上記のごとき溶着柱状抵抗体を用いている。そのため，
抵抗体は，高温耐火性に優れ，中心電極側ガラスシール
との接触状態も良好に維持される。更に，上記溶着柱状
抵抗体を用いることにより，燃焼ガスの圧力が高くなっ
た場合でも，気密性を保持することができ，信頼性に優
れたスパークプラグを得ることができる。即ち，上記溶
着柱状抵抗体及びそれと同時に溶着される銅ガラスによ
りシールされているので，絶縁碍子の貫通孔を気密性良
くシールすることができる。従って，本発明によれば，
抵抗体の性能を長期間安定的に維持することができ，長
寿命の，内燃機関用のスパークプラグを提供することが
できる。Further, in the present invention, as the resistor,
The welding columnar resistor as described above is used. for that reason,
The resistor is excellent in high-temperature fire resistance, and the contact state with the glass seal on the center electrode side is well maintained. Further, by using the welded columnar resistor, even when the pressure of the combustion gas is increased, the hermeticity can be maintained, and a highly reliable spark plug can be obtained. That is, the through-hole of the insulator can be hermetically sealed because it is sealed by the welded columnar resistor and the copper glass welded at the same time. Therefore, according to the present invention,
It is possible to provide a spark plug for an internal combustion engine that can stably maintain the performance of a resistor for a long period of time and has a long life.
【００１９】次に，請求項２の発明のように，上記ハウ
ジングは，そのねじ部の直径が１８ｍｍ以上，そのねじ
リーチ部は１２ｍｍ以上であり，かつ上記絶縁碍子の碍
子頭部の直径は１２．５ｍｍ以上，また絶縁碍子の頭部
長さは４０ｍｍ以上であることが好ましい。この場合に
は，特にコージェネレーション，ガス圧送用ポンプとい
った大型ガスエンジン用のスパークプラグにおいて，本
発明の効果がより一層発揮される。Next, as in the second aspect of the present invention, the housing has a thread portion having a diameter of at least 18 mm, a screw reach portion having a diameter of at least 12 mm, and a diameter of the insulator head of the insulator being 12 mm or more. It is preferable that the insulator has a head length of at least 40 mm. In this case, the effect of the present invention is further exerted particularly in a spark plug for a large gas engine such as a cogeneration and a gas pressure pump.
【００２０】次に，請求項３の発明のように，上記溶着
柱状抵抗体は，カーボン系抵抗材料とセラミック粉末と
ガラス粉末との混合物を高温下において溶着させたもの
であることが好ましい。この場合には，上記抵抗体は更
に高温耐火性に優れ，中心電極との接触状態も良好に維
持される。なお，上記カーボン系材料としては，カーボ
ンブラック等を，セラミック粉末としては，ジルコニア
等を用いる。ガラス粉末としては，硼珪酸系ガラス等を
用いる。Next, as in the third aspect of the present invention, it is preferable that the welded columnar resistor is formed by welding a mixture of a carbon-based resistance material, a ceramic powder and a glass powder at a high temperature. In this case, the resistor further has excellent high-temperature fire resistance, and the state of contact with the center electrode is maintained well. Note that carbon black or the like is used as the carbon-based material, and zirconia or the like is used as the ceramic powder. As the glass powder, borosilicate glass or the like is used.
【００２１】次に，請求項４の発明のように，上記溶着
柱状抵抗体における碍子頭部側の碍子頭部側先端面は，
上記ハウジングにおける上記碍子頭部側のハウジング先
端部よりも中心電極側にあることが好ましい。これによ
り，上記ハウジングのシールド部分により，電界強度を
効果的に抑制できる。上記碍子頭部側先端面が上記ハウ
ジングにおける上記碍子頭部側のハウジング先端部より
も中心電極側にない場合には，上記電界強度の抑制効果
が低下し，ノイズ強度が大きくなるおそれがある。Next, as in the invention of claim 4, the insulator head side tip surface of the welded columnar resistor on the insulator head side is:
It is preferable that the housing is located closer to the center electrode than the tip of the housing on the insulator head side. Thus, the electric field intensity can be effectively suppressed by the shield portion of the housing. If the front end surface of the insulator head side is not closer to the center electrode than the housing front end portion of the insulator head side of the housing, the effect of suppressing the electric field intensity may be reduced and the noise intensity may be increased.
【００２２】[0022]
【発明の実施の形態】実施形態例１ 本発明の実施形態例１にかかる内燃機関用のスパークプ
ラグにつき，図１，図２を用いて説明する。本例のスパ
ークプラグ１０は，図１に示すごとく，絶縁碍子４と，
該絶縁碍子４を保持するハウジング５と，該ハウジング
５に設けられた接地電極３とよりなる。そして，上記絶
縁碍子４の貫通孔４１内には，抵抗材料を溶着させてな
る溶着柱状抵抗体６及びその両端にそれぞれ銅ガラスを
溶着させた端子電極側ガラスシール８１及び中心電極側
ガラスシール８２を介在させ，一方に中心電極２を，他
方に端子電極２１を配置している。また，上記ハウジン
グ５は，内燃機関のエンジンブロックに螺着するための
取付ねじ部５１を有しており，上記中心電極２と接地電
極３との間には火花ギャップＧを有している。DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A spark plug for an internal combustion engine according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the spark plug 10 of this embodiment includes an insulator 4 and
It comprises a housing 5 for holding the insulator 4 and a ground electrode 3 provided on the housing 5. In the through-hole 41 of the insulator 4, a welded columnar resistor 6 formed by welding a resistive material, and a terminal electrode side glass seal 81 and a center electrode side glass seal 82 in which copper glass is welded to both ends thereof, respectively. , The center electrode 2 is arranged on one side, and the terminal electrode 21 is arranged on the other side. Further, the housing 5 has a mounting screw portion 51 for screwing to an engine block of the internal combustion engine, and has a spark gap G between the center electrode 2 and the ground electrode 3.
【００２３】そして，図１，図２に示すごとく，上記絶
縁碍子４における上記中心電極２を配置した側の碍子先
端面４４から，上記溶着柱状抵抗体６における中心電極
側の抵抗体先端面６１までの先端間距離をＴｍｍ，上記
絶縁碍子４の碍子脚部４５の長さをＫｍｍとしたとき，
Ｔ≧１．５Ｋの関係を有している。上記碍子脚部４５の
長さＫは，碍子先端面４４から碍子下部直線部分の端部
４６までの長さである。また，上記溶着柱状抵抗体６に
おける碍子頭部側の碍子頭部側先端面６２は，上記ハウ
ジング５における上記碍子頭部側のハウジング先端部５
２よりも中心電極側にある。As shown in FIG. 1 and FIG. 2, a tip end face 61 of the welded columnar resistor 6 on the side of the center electrode from a tip end face 44 of the insulator 4 on the side where the center electrode 2 is arranged. When the distance between the tip ends is Tmm and the length of the insulator leg 45 of the insulator 4 is Kmm,
It has a relationship of T ≧ 1.5K. The length K of the insulator leg 45 is a length from the insulator front end surface 44 to the end 46 of the insulator lower linear portion. In addition, the insulator head side tip surface 62 of the welding columnar resistor 6 on the insulator head side is connected to the housing tip portion 5 of the housing 5 on the insulator head side.
It is closer to the center electrode than 2.
【００２４】また，上記スパークプラグ１０は通常のス
パークプラグに比べて大きい形状を有している。即ち，
本例のスパークプラグ１０において，ハウジング５の取
付ねじ部５１の直径は１８ｍｍ，ねじリーチは２０．６
ｍｍである。また，碍子頭部４２の直径は１４ｍｍ，長
さは５４ｍｍである。なお，上記溶着柱状抵抗体６は，
カーボン系抵抗材料としてのカーボンブラックと，セラ
ミック粉末としてのジルコニアと，ガラス粉末としての
硼珪酸系ガラスとの混合物を８７０℃の高温下におい
て，直径５ｍｍ，長さ１０ｍｍの円柱状に溶着させたも
のである。また，図１に示すごとく，本例におけるスパ
ークプラグ１０は，従来のスパークプラグと異なり，碍
子頭部４２の外周にコルゲーションのない平坦面を有し
ている（図７と比較）。なお，絶縁碍子４とハウジング
５のかしめ部分には，該かしめ部分を封止するための，
封止材としてのリング５５とタルク５６を介在させてあ
る（図２）The spark plug 10 has a larger shape than a normal spark plug. That is,
In the spark plug 10 of this example, the diameter of the mounting screw portion 51 of the housing 5 is 18 mm, and the screw reach is 20.6.
mm. The diameter of the insulator head 42 is 14 mm, and the length is 54 mm. The welded columnar resistor 6 is
A mixture of carbon black as a carbon-based resistance material, zirconia as a ceramic powder, and borosilicate glass as a glass powder welded at a high temperature of 870 ° C. in a columnar shape having a diameter of 5 mm and a length of 10 mm. It is. Further, as shown in FIG. 1, the spark plug 10 in the present example has a flat surface without corrugation on the outer periphery of the insulator head 42, unlike the conventional spark plug (compare with FIG. 7). The caulked portion of the insulator 4 and the housing 5 is provided with a seal for sealing the caulked portion.
A ring 55 and a talc 56 as sealing materials are interposed (FIG. 2).
【００２５】次に作用効果につき述べる。本発明におい
ては，上記碍子先端面４４から抵抗体先端面６１までの
先端間距離Ｔが，上記碍子脚部４５の長さＫの１．５倍
以上の位置となるように，溶着柱状抵抗体６を設置して
ある。そのため，中心電極先端部２９が７００℃という
高温になって，その熱が上記碍子脚部４５に伝わって
も，上記先端間距離Ｔが大きいので，溶着柱状抵抗体６
と中心電極２との接触部７における温度は高温とならな
い。Next, the function and effect will be described. In the present invention, the welding columnar resistor is so arranged that the distance T between the tip from the insulator tip surface 44 to the resistor tip surface 61 is at least 1.5 times the length K of the insulator leg 45. 6 is installed. Therefore, even if the temperature of the center electrode tip portion 29 becomes as high as 700 ° C. and the heat is transmitted to the insulator legs 45, the distance T between the tips is large.
The temperature at the contact portion 7 between the electrode and the center electrode 2 does not become high.
【００２６】即ち，燃焼室内において，上記絶縁碍子４
の碍子脚部４５に伝わる熱は，上記碍子脚部４５先端部
において最も高温度である。本例においては，上記先端
間距離Ｔを，上記碍子脚部４５の長さＫよりも１．５倍
として，溶着柱状抵抗体６と中心電極側ガラスシール８
２との接触部７を，碍子脚部４５の付け根４６よりも更
に奥の方に位置している。That is, in the combustion chamber, the insulator 4
The heat transmitted to the insulator leg 45 has the highest temperature at the tip of the insulator leg 45. In this embodiment, the distance T between the tips is set to 1.5 times the length K of the insulator leg 45, and the welding columnar resistor 6 and the center electrode side glass seal 8 are formed.
The contact portion 7 with the base 2 is located further back than the base 46 of the insulator leg 45.
【００２７】そのため，内燃機関における高温度の燃焼
熱が，上記溶着柱状抵抗体６と中心電極側ガラスシール
８２の接触部７に直接伝わらず，この接触部７の温度は
低くなる。それ故，上記接触部７における接触抵抗の上
昇を抑制することができ，溶着柱状抵抗体６と中心電極
側ガラスシール８２との接触状態も安定に維持でき，抵
抗体の焼損，エンジン失火のおそれもない。Therefore, high-temperature combustion heat in the internal combustion engine is not directly transmitted to the contact portion 7 between the welded columnar resistor 6 and the center electrode side glass seal 82, and the temperature of the contact portion 7 is lowered. Therefore, an increase in contact resistance at the contact portion 7 can be suppressed, the contact state between the welded columnar resistor 6 and the center electrode side glass seal 82 can be maintained stably, and there is a risk of burnout of the resistor and engine misfire. Nor.
【００２８】また，本例においては，上記カーボン系抵
抗材料等を用いた上記溶着柱状抵抗体６を用いている。
そのため，抵抗体６は，高温耐火性に優れ，中心電極側
ガラスシール８２との接触状態も良好に維持される。ま
た，溶着柱状抵抗体６，端子電極側ガラスシール８１及
び中心電極側ガラスシール８２を用いているので，絶縁
碍子４の貫通孔を気密性良くシールすることができる。In this embodiment, the welding columnar resistor 6 using the carbon-based resistance material or the like is used.
Therefore, the resistor 6 is excellent in high-temperature fire resistance, and the state of contact with the glass seal 82 on the center electrode side is well maintained. Further, since the welding columnar resistor 6, the terminal electrode-side glass seal 81 and the center electrode-side glass seal 82 are used, the through hole of the insulator 4 can be hermetically sealed.
【００２９】また，上記溶着柱状抵抗体６における碍子
頭部側先端面６２は，上記ハウジング５における上記碍
子頭部側のハウジング先端部５２よりも中心電極側にあ
る。そのため，上記ハウジング５のシールド部分によ
り，電界強度を効果的に抑制できる。従って，本発明に
よれば，抵抗体の性能を長期間安定的に維持することが
でき，長寿命の，内燃機関用のスパークプラグを提供す
ることができる。The front end face 62 of the welding columnar resistor 6 on the insulator head side is closer to the center electrode than the housing tip 52 of the housing 5 on the insulator head side. Therefore, the electric field intensity can be effectively suppressed by the shield portion of the housing 5. Therefore, according to the present invention, it is possible to provide a spark plug for an internal combustion engine that can stably maintain the performance of a resistor for a long period of time and has a long life.
【００３０】なお，上記スパークプラグ１０の碍子頭部
４２はコルゲーションの無い平坦面を有している。その
ため，上記絶縁碍子４の径方向に対する強度が向上し，
焼成時における絶縁碍子４の曲りも抑制される。The insulator head 42 of the spark plug 10 has a flat surface without corrugation. Therefore, the strength of the insulator 4 in the radial direction is improved,
The bending of the insulator 4 during firing is also suppressed.
【００３１】実施形態例２ 本例においては，図３に示すごとく，上記先端間距離Ｔ
と，上記溶着柱状抵抗体６の中心電極側ガラスシール８
２との接触部７（図１，図２）における温度との関係を
測定した。即ち，上記碍子脚部の長さＫを一定（Ｋ＝７
ｍｍ）とし，Ｔの異なる種々の絶縁碍子を用いたスパー
クプラグについて評価を行った。その他の構造は，実施
形態例１と同様である。Embodiment 2 In this embodiment, as shown in FIG.
And the center electrode side glass seal 8 of the welded columnar resistor 6
2 and the temperature at the contact portion 7 (FIGS. 1 and 2) were measured. That is, the length K of the insulator leg is fixed (K = 7).
mm), and spark plugs using various insulators having different T were evaluated. Other structures are the same as those of the first embodiment.
【００３２】評価に当っては，天然ガスを燃料とする，
４０Ｌ，４サイクル，８気筒の大型ガスエンジンを使用
した。その運転条件は，エンジン回転数１８００ｒｐｍ
にて行った。In the evaluation, natural gas is used as fuel.
A 40L, 4-cycle, 8-cylinder large gas engine was used. The operating conditions were as follows: engine speed 1800 rpm
I went in.
【００３３】上記測定の結果を，図３に示す。同図よ
り，Ｔが大きいほど上記溶着柱状抵抗体の中心電極側ガ
ラスシール８２との接触部７における温度は低いことが
分かる。FIG. 3 shows the result of the above measurement. It can be seen from the figure that the larger the T, the lower the temperature of the welded columnar resistor at the contact portion 7 with the center electrode side glass seal 82.
【００３４】実施形態例３ 本例においては，図４に示すごとく，従来のソリッド抵
抗体を内臓したスパークプラグ（自社試作品）と，本発
明にかかる溶着柱状抵抗体を内臓したスパークプラグに
おける，上記溶着柱状抵抗体と中心電極側ガラスシール
８２との接触部７における，接触抵抗について比較し
た。その他の構造は，実施形態例１と同様である。Embodiment 3 In this embodiment, as shown in FIG. 4, a conventional spark plug (in-house prototype) incorporating a solid resistor and a spark plug incorporating a welded columnar resistor according to the present invention are used. The contact resistance at the contact portion 7 between the welded columnar resistor and the center electrode side glass seal 82 was compared. Other structures are the same as those of the first embodiment.
【００３５】評価に当っては，実施形態例２と同じエン
ジンを使用した。その運転条件は，エンジン回転数１８
００ｒｐｍにて行った。上記条件の下，運転時間に対す
る上記両スパークプラグの上記接触抵抗値変化率を測定
した。なお，上記接触抵抗値変化率とは，初期抵抗値を
Ｒ0，運転後抵抗値をＲ1としたとき｛（Ｒ1−Ｒ0）／Ｒ
0｝×１００の値である。上記抵抗値とは，中心電極先
端部２９と端子電極２１との間の抵抗値である。上記抵
抗値Ｒ0，Ｒ1を，上記両者間の抵抗値について測定する
こととしたのは，図５に示すごとく，上記接触部７の抵
抗値は，上記両者間の抵抗値を測定しても略同一の結果
が得られるためである。In the evaluation, the same engine as that of the second embodiment was used. The operating conditions are engine speed 18
The test was performed at 00 rpm. Under the above conditions, the rate of change in the contact resistance value of the two spark plugs with respect to the operation time was measured. The above-mentioned contact resistance change rate is defined as ｛(R 1 −R 0 ) / R, where R 0 is the initial resistance and R 1 is the resistance after operation.
0 ｝ 100. The resistance value is a resistance value between the center electrode tip portion 29 and the terminal electrode 21. The resistance values R 0 and R 1 were measured for the resistance value between the two. As shown in FIG. 5, the resistance value of the contact portion 7 was determined by measuring the resistance value between the two. This is because substantially the same result can be obtained.
【００３６】上記測定の結果を，図４に示す。同図よ
り，上記両スパークプラグの上記接触抵抗値変化率に，
顕著な差があることが分かる。即ち，ソリッド抵抗体内
臓プラグにおける上記接触抵抗値変化率は，運転時間と
共に急激に上昇し，３０００時間経過時には，１０4％
となり，エンジン失火発生の可能性が出てくる。一方，
溶着柱状抵抗体内臓プラグにおける上記接触抵抗は，目
標寿命である運転時間４０００時間を超えても特に上昇
していない。但し，上記目標寿命はガスエンジンメーカ
ーからの要求を基に定めた値である。FIG. 4 shows the results of the above measurement. From the figure, it can be seen that the contact resistance change rates of both spark plugs are
It can be seen that there is a significant difference. That is, the change rate of the contact resistance value of the solid resistance built-in plug increases sharply with the operation time, and after 3000 hours, 10 4 %.
And the possibility of engine misfire appears. on the other hand,
The contact resistance of the welded columnar resistance built-in plug does not particularly increase even when the operation time exceeds the target life of 4000 hours. However, the target life is a value determined based on requests from gas engine manufacturers.
【００３７】以上の結果は，以下の理由によるものと考
えられる。即ち，従来のソリッド抵抗体の場合には，該
ソリッド抵抗体と中心電極との接触は固体同士の接触で
あるため接触抵抗が大きく，微小なスパークが発生す
る。この微小なスパークにより，上記ソリッド抵抗体の
炭素成分が焼損する。そのため，上記ソリッド抵抗体の
抵抗値が更に上昇する。これに対し，上記溶着柱状抵抗
体の場合には，中心電極との接触部はガラス成分により
密着しており，接触抵抗が極めて小さい。そのため，中
心電極と溶着柱状抵抗体との間におけるスパークの発生
が抑制され，長時間にわたり接触抵抗の変化が生じな
い。The above results are considered to be due to the following reasons. That is, in the case of the conventional solid resistor, since the contact between the solid resistor and the center electrode is a contact between solids, the contact resistance is large and a minute spark is generated. This minute spark burns out the carbon component of the solid resistor. Therefore, the resistance value of the solid resistor further increases. On the other hand, in the case of the welded columnar resistor, the contact portion with the center electrode is more closely adhered to the glass component, and the contact resistance is extremely small. Therefore, the occurrence of spark between the center electrode and the welded columnar resistor is suppressed, and the contact resistance does not change for a long time.
【００３８】実施形態例４ 本例においては，図６に示すごとく，上記スパークプラ
グの碍子先端面から抵抗体先端面までの先端間距離Ｔ
と，上記絶縁碍子の碍子脚部の長さＫとの比Ｔ／Ｋによ
る，上記溶着柱状抵抗体と中心電極の接触部における接
触抵抗値変化率について測定した。Embodiment 4 In this embodiment, as shown in FIG. 6, a tip-to-tip distance T from the insulator tip face to the resistor tip face of the spark plug described above.
The rate of change of the contact resistance value at the contact portion between the welded columnar resistor and the center electrode was measured based on the ratio T / K between the length of the insulator leg and the length K of the insulator leg.
【００３９】評価に当っては，実施形態例３と同じエン
ジン，運転条件にて行った。上記条件の下，Ｔ／Ｋ＝
１．０，１．２，１．３５，１．５，２．０のスパーク
プラグについて測定した。The evaluation was performed under the same engine and operating conditions as in the third embodiment. Under the above conditions, T / K =
Measurements were made for spark plugs of 1.0, 1.2, 1.35, 1.5, and 2.0.
【００４０】上記測定の結果を，図６に示す。同図よ
り，Ｔ／Ｋが大きいほど，上記接触抵抗値変化率の上昇
は少ないことが分かる。そして，目標寿命である４００
０時間経過時に，エンジン失火のおそれのある接触抵抗
値変化率１０4％未満を保つためには，Ｔ／Ｋが１．５
以上であれば問題ないことが分かる。FIG. 6 shows the result of the above measurement. It can be seen from the figure that the larger the T / K, the smaller the increase in the contact resistance value change rate. And the target life of 400
In order to keep the contact resistance value change rate of less than 10 4 % at which the engine may be misfired after 0 hours, T / K must be 1.5 or less.
If it is above, it turns out that there is no problem.
【図１】実施形態例１にかかる，内燃機関用のスパーク
プラグの一部断面正面図。FIG. 1 is a partial cross-sectional front view of a spark plug for an internal combustion engine according to a first embodiment.
【図２】実施形態例１にかかる，スパークプラグの溶着
柱状抵抗体付近の一部断面正面図。FIG. 2 is a partial cross-sectional front view of the vicinity of a welding columnar resistor of a spark plug according to the first embodiment.
【図３】実施形態例２にかかる，先端間距離Ｔと，溶着
柱状抵抗体の中心電極との接触部における温度との関係
を示す線図。FIG. 3 is a diagram showing a relationship between a distance T between tips and a temperature at a contact portion of a welded columnar resistor with a center electrode according to a second embodiment.
【図４】実施形態例３にかかる，各種抵抗体と中心電極
との接触部における，接触抵抗値変化率を示す線図。FIG. 4 is a diagram showing a contact resistance value change rate at a contact portion between various resistors and a center electrode according to a third embodiment.
【図５】実施形態例３にかかる，エンジン運転前と運転
後における，溶着柱状抵抗体の位置による中心電極先端
部との間の抵抗値の変化を示す線図。FIG. 5 is a diagram showing a change in resistance value between a position of a welded columnar resistor and a tip of a center electrode according to a third embodiment before and after engine operation.
【図６】実施形態例４にかかる，溶着柱状抵抗体と中心
電極との接触部における，Ｔ／Ｋを変化させたときの，
接触抵抗値変化率を示す線図。FIG. 6 is a graph showing the relationship between T / K at a contact portion between a welded columnar resistor and a center electrode according to a fourth embodiment.
FIG. 3 is a diagram illustrating a contact resistance value change rate.
【図７】従来例にかかる，内燃機関用のスパークプラグ
の一部断面正面図。FIG. 7 is a partial cross-sectional front view of a spark plug for an internal combustion engine according to a conventional example.
１０．．．スパークプラグ， ２．．．中心電極， ２９．．．中心電極先端部 ３．．．接地電極， ４．．．絶縁碍子， ４２．．．碍子頭部， ４５．．．碍子脚部， ５．．．ハウジング， ６．．．溶着柱状抵抗体， ７．．．接触部， ８１．．．端子電極側ガラスシール， ８２．．．中心電極側ガラスシール， 10. . . Spark plug, 2. . . Center electrode, 29. . . 2. Center electrode tip . . Ground electrode, 4. . . Insulator, 42. . . Insulator head, 45. . . Insulator legs, 5. . . Housing, 6. . . 6. welded columnar resistor; . . Contact part, 81. . . 82. Terminal electrode side glass seal . . Center electrode side glass seal,
Claims (4)
て，一方に中心電極を，他方に端子電極を配置してなる
上記絶縁碍子と，該絶縁碍子を保持するハウジングと，
該ハウジングに設けられた接地電極とよりなり，また上
記ハウジングには内燃機関に螺着するための取付ねじ部
を有し，上記中心電極と接地電極との間には火花ギャッ
プを有してなる内燃機関用のスパークプラグにおいて，
上記抵抗体は，抵抗材料を溶着させてなる溶着柱状抵抗
体を用いてなり，かつ，上記絶縁碍子における上記中心
電極を配置した側の碍子先端面から，上記溶着柱状抵抗
体における中心電極側の抵抗体先端面までの先端間距離
をＴｍｍ，上記絶縁碍子の碍子脚部の長さをＫｍｍとし
たとき，Ｔ≧１．５Ｋの関係を有していることを特徴と
する内燃機関用のスパークプラグ。An insulator having a resistor interposed in a through hole of the insulator, a central electrode disposed on one side, and a terminal electrode disposed on the other side; a housing for holding the insulator;
A ground electrode provided on the housing; the housing having a mounting screw for screwing to an internal combustion engine; and a spark gap between the center electrode and the ground electrode. In spark plugs for internal combustion engines,
The resistor is formed of a welded columnar resistor formed by welding a resistive material, and is connected to the center electrode side of the welded columnar resistor from the front end surface of the insulator where the center electrode is arranged. A spark plug for an internal combustion engine having a relationship of T ≧ 1.5K, where Tmm is the distance between the tips to the tip of the resistor and Kmm is the length of the insulator leg of the insulator. plug.
グは，そのねじ部の直径が１８ｍｍ以上，そのねじリー
チ部は１２ｍｍ以上であり，かつ上記絶縁碍子の碍子頭
部の直径は１２．５ｍｍ以上，また絶縁碍子の頭部長さ
は４０ｍｍ以上であることを特徴とする内燃機関用のス
パークプラグ。2. The invention according to claim 1, wherein said housing has a thread portion having a diameter of at least 18 mm, a screw reach portion having a diameter of at least 12 mm, and a diameter of an insulator head of said insulator of at least 12.5 mm. A spark plug for an internal combustion engine, wherein a head length of the insulator is 40 mm or more.
抵抗体は，カーボン系抵抗材料とセラミック粉末とガラ
ス粉末との混合物を高温下において溶着させたものであ
ることを特徴とする内燃機関用のスパークプラグ。3. The internal combustion engine according to claim 1, wherein the welding columnar resistor is formed by welding a mixture of a carbon-based resistance material, a ceramic powder, and a glass powder at a high temperature. Spark plug.
上記溶着柱状抵抗体における碍子頭部側の碍子頭部側先
端面は，上記ハウジングにおける上記碍子頭部側のハウ
ジング先端部よりも中心電極側にあることを特徴とする
内燃機関用のスパークプラグ。4. The method according to claim 1, wherein:
A spark plug for an internal combustion engine, wherein a front end face of the welded columnar resistor on the insulator head side is located closer to a center electrode than a tip end of the housing on the insulator head side of the housing.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10314919A JPH11260531A (en) | 1998-01-09 | 1998-11-05 | Spark plug for internal combustion engine |
| US09/207,661 US6130498A (en) | 1997-12-26 | 1998-12-09 | Spark plug with specific measured parameters |
| DE19860102A DE19860102A1 (en) | 1997-12-26 | 1998-12-23 | Spark plug for IC engine |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10-15009 | 1998-01-09 | ||
| JP1500998 | 1998-01-09 | ||
| JP10314919A JPH11260531A (en) | 1998-01-09 | 1998-11-05 | Spark plug for internal combustion engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11260531A true JPH11260531A (en) | 1999-09-24 |
Family
ID=26351068
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10314919A Pending JPH11260531A (en) | 1997-12-26 | 1998-11-05 | Spark plug for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11260531A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002198156A (en) * | 2000-12-26 | 2002-07-12 | Denso Corp | Manufacturing method of spark plug |
| JP2007122879A (en) * | 2004-10-12 | 2007-05-17 | Ngk Spark Plug Co Ltd | Spark plug |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05152053A (en) * | 1991-11-30 | 1993-06-18 | Ngk Spark Plug Co Ltd | Spark plug for internal combustion engine |
| JPH0945458A (en) * | 1995-08-02 | 1997-02-14 | Ngk Spark Plug Co Ltd | Spark plug having resistance |
| JPH09106879A (en) * | 1995-10-11 | 1997-04-22 | Denso Corp | Spark plug for internal combustion engine |
-
1998
- 1998-11-05 JP JP10314919A patent/JPH11260531A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05152053A (en) * | 1991-11-30 | 1993-06-18 | Ngk Spark Plug Co Ltd | Spark plug for internal combustion engine |
| JPH0945458A (en) * | 1995-08-02 | 1997-02-14 | Ngk Spark Plug Co Ltd | Spark plug having resistance |
| JPH09106879A (en) * | 1995-10-11 | 1997-04-22 | Denso Corp | Spark plug for internal combustion engine |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002198156A (en) * | 2000-12-26 | 2002-07-12 | Denso Corp | Manufacturing method of spark plug |
| JP4517505B2 (en) * | 2000-12-26 | 2010-08-04 | 株式会社デンソー | Manufacturing method of spark plug |
| JP2007122879A (en) * | 2004-10-12 | 2007-05-17 | Ngk Spark Plug Co Ltd | Spark plug |
| JP4693112B2 (en) * | 2004-10-12 | 2011-06-01 | 日本特殊陶業株式会社 | Spark plug |
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