JP3707851B2

JP3707851B2 - Ignition coil for internal combustion engine

Info

Publication number: JP3707851B2
Application number: JP02346596A
Authority: JP
Inventors: 正郎谷脇; 徹田中; 濃森山
Original assignee: 阪神エレクトリック株式会社
Priority date: 1996-01-18
Filing date: 1996-01-18
Publication date: 2005-10-19
Anticipated expiration: 2016-01-18
Also published as: JPH09199352A

Description

【０００１】
【発明の属する技術分野】
この発明は、エンジンの各気筒に設けられたプラグホールに挿入し、プラグホールの底にある点火プラグの頭部端子に高圧端子を押付け、点火プラグに高電圧を印加する細長い筒形の点火コイルに関する。
【０００２】
【従来の技術】
このように使用する点火プラグとして、開磁路鉄心を絶縁材料製の前端が閉じたボビンに挿入し、そのボビンの外に同心状に１次コイルと２次コイルを設け、これらを絶縁ケースの中に同心状に配置すると共に、ケース中にエポキシ樹脂を注型し、開磁路鉄心、ボビン、１次コイル及び２次コイルをエポキシ樹脂層中に固定し、絶縁ケースの外に硅素鋼板などを丸めた、割れ目を有する筒形のシールド部材を嵌合したものが特開平５−１３５９６７号により公知である。このシールド部材は、中心の開磁路鉄心と共に略閉磁路を構成し、点火コイルが外部から磁気的な影響を受けないように点火コイルを保護する。又、シールド部材の割れ目は、点火コイルの動作時に、シールド部材の表面に生じ易い不要な渦電流を減少させる。尚、高圧端子はボビンの閉鎖した前端部に絶縁材を介して取付けてあり、エポキシ樹脂層の前端から外に突出している。
【０００３】
【発明が解決しようとする課題】
点火コイルの外径は、点火コイルを内燃機関の各気筒のシリンダに設けたプラグホールに挿入して取付けるため、プラグホールの内径よりも小であるので、筒径のシールド部材はアース電位であるプラグホールの内面と接触することがない。そして、点火コイルの２次コイルには３万〜４万ボルトの高電圧が発生するため、導電性のシールド部材は帯電し、点火コイルを取り外す場合等、シールド部材に手を触れると感電することがある。又、点火コイルがプラグホール中に同心状に取付けられて居らず、これによって外装鉄心とプラグホールの内壁間の距離が場所によって異なる場合は、電界分布が一定にならず、点火コイルの出力特性が安定しなくなるという問題も生じる。
【０００４】
【課題を解決するための手段】
そこで本発明は、点火コイルに１次端子を電源電池に接続すると電池のアース側に接続されるアース端子を設け、外装鉄心を上記アース端子に電気的に接続しておくことにより上述した問題点を解消したのである。
【０００５】
【発明の実施の形態】
請求項１における内燃機関の点火コイルは、閉鎖した前端部に高圧端子を有する樹脂の細長い筒形ケースの内部の中心に開磁路鉄心、その外に同心状に１次コイルと、２次コイルを設け、前記筒形ケースの外に磁性金属板による円筒形の外装鉄心を嵌合し、この筒形ケースと外装鉄心の後部をアース端子を有する樹脂の後部筒に嵌合し、外装鉄心とアース端子を接続し、後部筒、及び筒形ケース中に注型した熱硬化性絶縁樹脂層中に開磁路鉄心と１次コイル及び２次コイルを固定しており、外装鉄心に後向きの突出部を設け、後部筒にあるアース端子には上記突出部が圧入される溝を設け、上記突出部をアース端子の溝に圧入して外装鉄心とアース端子を接続したことを特徴とする。
又、請求項２における内燃機関の点火コイルは、閉鎖した前端部に高圧端子を有する樹脂の細長い筒形ケースの内部の中心に開磁路鉄心、その外に同心状に１次コイルと、２次コイルを設け、前記筒形ケースの外に磁性金属板による円筒形の外装鉄心を嵌合し、この筒形ケースと外装鉄心の後部をアース端子を有する樹脂の後部筒に嵌合し、外装鉄心とアース端子を接続し、後部筒、及び筒形ケース中に絶縁オイルを注入し、開磁路鉄心と１次コイル及び２次コイルを絶縁オイル中に浸漬しており、外装鉄心に後向きの突出部を設け、後部筒にあるアース端子には上記突出部が圧入される溝を設け、上記突出部をアース端子の溝に圧入して外装鉄心とアース端子を接続したことを特徴とする。
請求項３における内燃機関の点火コイルは、閉鎖した前端部に高圧端子を有する樹脂の前部筒と、アース端子を有する樹脂の後部筒と、磁性金属板による円筒形の外装鉄心とを備え、前記外装鉄心の前端部を前部筒に、後端部を後部筒に夫々嵌合して固定し、外装鉄心で囲まれた内部の中心に開磁路鉄心を、開磁路鉄心の外に１次コイルと２次コイルを夫々同心状に設け、外装鉄心とアース端子を接続し、前部筒の内部、外装鉄心で囲まれた内部、及び後部筒の内部に熱硬化性絶縁樹脂を充填し、該絶縁樹脂層中に１次コイル、２次コイル、及び開磁路鉄心を固定しており、外装鉄心に後向きの突出部を設け、後部筒にあるアース端子には上記突出部が圧入される溝を設け、上記突出部をアース端子の溝に圧入して外装鉄心とアース端子を接続したことを特徴とする。
請求項４における内燃機関の点火コイルは、閉鎖した前端部に高圧端子を有する樹脂の前部筒と、アース端子を有する樹脂の後部筒と、磁性金属板による円筒形の外装鉄心とを備え、前記外装鉄心の前端部を前部筒に、後端部を後部筒に夫々嵌合して固定し、外装鉄心で囲まれた内部の中心に開磁路鉄心を、開磁路鉄心の外に１次コイルと２次コイルを夫々同心状に設け、外装鉄心とアース端子を接続し、前部筒の内部、外装鉄心で囲まれた内部、及び後部筒の内部に絶縁オイルを注入し、該絶縁オイル中に１次コイル、２次コイル、及び開磁路鉄心を浸漬しており、外装鉄心に後向きの突出部を設け、後部筒にあるアース端子には上記突出部が圧入される溝を設け、上記突出部をアース端子の溝に圧入して外装鉄心とアース端子を接続したことを特徴とする。
【０００６】
【実施例】
図示の請求項１，２，３，４の各実施例において、１は１次コイル、２は２次コイル、３は開磁路鉄心を示す。
開磁路鉄心３は、図２，図６に示すように多数枚の短冊形硅素鋼板を断面形状が円形に近くなるように積層して構成した周知のもので、その長さの途中を１次ボビン等の絶縁材で被い、１次コイル１はその絶縁材上に巻付けてある。２次コイル２は、図では省略したが２次ボビン４の外周に分割巻きで巻いてある。この２次ボビン４は前端が閉じ、後端が開放した筒形で、前端の中心には前向きの突起５と、後向きの筒部６を有し、後端部の外周からは複数（図では３つ）の突出片７が放射状に突出する（図９Ａ参照）。筒部６は開磁路鉄心の前端部を挿入し、２次ボビンの内部に開磁路鉄心を同心状に支持するためのものである。
【０００７】
図１から３に示した請求項１の点火コイルについて述べると、８は閉鎖した前端部の中心に高圧端子９を前向きに突出して取付けた外装用の樹脂製の細長い筒形ケースで、閉鎖した前端部の中心には前記２次ボビンの突起５を受入れる受入筒１０を後向きに備えている。
【０００８】
１１は後部外周から突出したコネクタ部１２に１次端子やアース端子１３を貫通状に装着した樹脂製の後部筒で、その外径は筒形ケース８の外径よりも大である。そして、後部筒は、図９Ｂに示したように、前端部の内周に筒形ケース８の後端部が嵌合する環状段部１４を有すると共に、内部の中心に開磁路鉄心の後端部を嵌合保持する支持筒１５を備えている。この支持筒１５は、後部筒の内周から半径方向内向きに突出する突出部１６で後部筒の内部に一体に支持されている。前述した２次ボビンの後端部の外周から突出する突出片６は筒形ケースの内周に接触する。筒形ケース８、後部筒１１はいずれも合成樹脂の成形品である。
【０００９】
１７は磁性金属板による円筒形の外装鉄心（筒形シールド部材）である。外装鉄心は例えば１巻き以上の長さ、つまり円周以上の長さの硅素鋼板を円筒形に丸め、鋼板の一部を内外に重合させて構成しても、１巻き以下の長さの硅素鋼板を円筒形に丸め、割れ目１８を有するように構成してもよい。又、鋼管などを所定の長さに輪切りにして構成してもよいし、そのように輪切りにした鋼管に軸方向の割れ目１８を１個所形成したものでもよい。図示の実施例では１巻き以下の長さの硅素鋼板を円筒形に丸めて構成したため割れ目１８を有する。外装鉄心１７の内径は、筒形ケース７の外径と同じか、それより少し小さくするか、外径を後部筒の環状段部１４の内径と同じか、それより少し大きくする。又、長さは筒形ケース７と同じか、それより少し短くする。
【００１０】
点火コイルを組立てるには、２次ボビンの前向きの突起５を筒形ケース８の受入筒１０に挿入すると共に、２次ボビンの後端の突出片７を筒形ケース８の内周後部に接触させて筒形ケースと２次ボビンを同心状に保ち、２次コイルの高圧端を筒形ケースの高圧端子９に電気的に接続する。硅素鋼板を円筒形に丸めた外装鉄心や、鋼管を輪切りにし、且つ割れ目を形成した外装鉄心の場合は直径を拡大することができるので、外装鉄心１７の直径を拡大し、外装鉄心１７の割れ目１８を拡げて該鉄心の直径を拡大し、後端を筒形ケースの後端に揃えて筒形ケース８の外に嵌め、必要ならば接着する。又、鋼管などを輪切りにしただけの外装鉄心は、直径を拡大できないため、その内径を筒形ケースの外径に合わせた鋼管を使用して作り、筒形ケースの外に後端を揃えて嵌め、接着して固定する。そして、開磁路鉄心３を１次コイルごと２次ボビンの内部に後から入れ、その前端部を２次ボビンの筒部６に挿入すると共に、開磁路鉄心の後部を後部筒の支持筒１５内に入れながら筒形ケースと外装鉄心の後部を後部筒の環状段部１４内に圧入し、開磁路鉄心の外に１次コイル、２次ボビン、筒形ケース、後部筒を同心状に保つ。そして、１次コイルの電線などを１次端子に、外装鉄心に取付けた電線を環状段部に設けた切欠き１４′に通す等してアース端子１３に電気的に接続する。
【００１１】
図３に示すように外装鉄心１７に後向きの突出部１９を設け、アース端子１３には上記突出部が圧入される溝１３′、後部筒の内周の環状段部１４に上記突出部１９が通る切欠き１４′を設けておくと、筒形ケースと外装鉄心の後部を後部筒の内周に圧入する際、前記突出部１９とアース端子の溝１３′の向きを一致させることにより突出部１９は切欠き１４′を通ってアース端子の溝１３′に同時に圧入され、外装鉄心とアース端子を電線で接続する半田付け等の作業が不要になる。
【００１２】
それから、後部筒１１の後端内部からエポキシ樹脂などの熱硬化性絶縁樹脂を真空注型する。これにより樹脂は２次ボビン４の中に後から流入し、２次ボビンの内周と、１次コイル１、開磁路鉄心３、支持筒１５との間を満たして固まると共に、２次ボビンの後端の放射状の突出片７，７の間隔を通じ筒形ケース８の内周と、２次ボビン、２次コイルとの間、及び後部筒１１の内部を満たして固まり、こうして固まった樹脂層２０で開磁路鉄心、１次コイル、２次ボビン、２次コイル、筒形ケース、後部筒は同心状に固定され、請求項１の点火コイルが完成する。
【００１３】
図４は請求項２の点火コイルであって、前述した請求項１と同様にして点火コイルを組立て、エポキシ樹脂などの熱硬化性絶縁樹脂の代りに、後部筒１１の後端内部から絶縁オイル３０を注入する。これにより絶縁オイルは２次ボビン４の中に後から流入し、２次ボビンの内周と、１次コイル１、開磁路鉄心３、支持筒１５との間を満たすと共に、２次ボビンの後端の放射状の突出片７，７の間隔を通じ筒形ケース８の内周と、２次ボビン、２次コイルとの間、及び後部筒１１の内部を満たし、開磁路鉄心、１次コイル、２次ボビン、２次コイルは絶縁オイル３０中に浸漬する。そして、後部筒１１の後端部には蓋３１を接着、高周波溶着などで取付け、絶縁オイルの洩れを防ぐ。
【００１４】
図５〜７に示した請求項３の点火コイルは、前述した円筒形の外装鉄心１７を筒形ケース８の代りに使用し、必要に応じ外装鉄心１７の内周に緩衝シート２１を円筒形に沿わせる。この外装鉄心も、請求項１や２の外装鉄心と同様に、例えば１巻き以上の長さ、つまり円周以上の長さの硅素鋼板を円筒形に丸め、鋼板の一部を内外に重合させて構成しても、１巻き以下の長さの硅素鋼板を円筒形に丸め、割れ目１８を有するように構成してもよい。又、鋼管などを所定の長さに輪切りにして構成してもよいし、そのように輪切りにした鋼管に軸方向の割れ目１８を１個所形成したものでもよい。図示の実施例では１巻き以下の長さの硅素鋼板を円筒形に丸めて構成したため割れ目１８を有するので、緩衝シート２１がその割れ目を内側から塞いでいる。尚、緩衝シート２１にはアラミドポリマー紙、合成樹脂のフィルム、ガラスクロスなどを使用する。緩衝シートは予め円筒状にしておいて外装鉄心に挿入してもよいし、シート状のものを丸めながら外装鉄心に挿入してもよい。
【００１５】
２２は閉鎖した前端部の中心に高圧端子８を前向きに突出して取付けた樹脂製の前部筒で、前部筒は外周の後部に直径が減少した環状段部２３を有し、且つ閉鎖した前端部の中心には２次ボビンの突起５を受入れる受入筒２４を後向きに備えている。尚、後部筒１１は請求項１，２で述べたものを使用し、その前端部の内周に設けた環状段部１４には外装鉄心１７の後部を圧入する。
【００１６】
請求項３の点火コイルを組立てるには２次ボビンの前向きの突起５を前部筒２２の受入筒２４に挿入し、２次コイルの高圧端を前部筒の高圧端子８に電気的に接続すると共に、内周に緩衝シート２１を嵌合した外装鉄心１７の前端部を前部筒の後部外周の環状段部２３に嵌合し、必要ならば接着して固定する。そして、開磁路鉄心３を１次コイルごと２次ボビンの内部に後から入れ、その前端部を２次ボビンの筒部６に挿入すると共に、開磁路鉄心の後部を後部筒の支持筒１５内に入れながら外装鉄心１７の後部を後部筒の環状段部１４内に圧入し、開磁路鉄心の外に前部筒、１次コイル、２次ボビン、外装鉄心、後部筒を同心状に保つ。尚、２次ボビンの後端の放射状の突出片７は外装鉄心の内周、又はその内側の緩衝シート２１に接触する。そして、１次コイルの電線などを１次端子に、外装鉄心に取付けた電線を環状段部に設けた切欠き１４′に通す等してアース端子１３に電気的に接続する。
【００１７】
この場合も、図３に示すように外装鉄心１７に後向きの突出部１９を設け、アース端子１３には上記突出部が圧入される溝１３′、後部筒の内周の環状段部１４に上記突出部１９が通る切欠き１４′を設けておくと、外装鉄心の後部を後部筒の内周の環状段部１４に圧入する際、前記突出部１９とアース端子の溝１３′の向きを一致させることにより突出部１９は切欠き１４′を通ってアース端子の溝１３′に同時に圧入され、外装鉄心とアース端子を電線で接続する半田付け等の作業が不要になる。
【００１８】
それから、後部筒１１の後端内部からエポキシ樹脂などの熱硬化性絶縁樹脂を真空注型する。これにより樹脂は２次ボビン４の中に後から流入し、２次ボビンの内周と、１次コイル１、開磁路鉄心３、保持筒１５との間を満たして固まると共に、２次ボビンの後端の放射状の突出片７，７の間隔を通じ緩衝シート２１、前部筒２２の内周と、２次ボビン、２次コイルとの間、及び後部筒１１の内部を満たして固まり、こうして固まった樹脂層２０で開磁路鉄心、１次コイル、２次ボビン、２次コイル、前部筒、後部筒、及び内周に緩衝シートを有する外装鉄心は同心状に固定される。尚、割れ目１８を有する外装鉄心の場合は、その割れ目を内側から緩衝シート２１が塞いでいるので、真空注型の際に、絶縁樹脂が割れ目から外に洩れることがない。
【００１９】
緩衝シート２１にアラミドポリマー紙を使用すると、耐絶縁性、耐熱性を向上させることができる。又、合成樹脂のフィルムを使用すると作業性、及びコストの面で有利であり、ガラスクロスを使用すると、絶縁樹脂が浸透して固まるため絶縁樹脂層２０との密着性が向上する。
【００２０】
請求項４の点火コイルも外装鉄心１７を筒形ケースの代りに使用し、請求項３の点火コイルと同様に組立て、エポキシ樹脂などの熱硬化性絶縁樹脂の代りに絶縁オイル３０を後部筒１１の後端内部から注入する。注入するのは絶縁オイルであって、絶縁樹脂層のようなクラックは発生しないので外装鉄心の内周に緩衝シート２１を設ける必要はないが、割れ目１８を有する場合は絶縁オイルが洩れるのを防ぐため、割れ目１８に内側又は外側から合成樹脂の板３２などを接着などで取付けて塞ぐ。これにより注入した絶縁オイルは２次ボビン４の中に後から流入し、２次ボビンの内周と、１次コイル１、開磁路鉄心３、保持筒１５との間を満たすと共に、２次ボビンの後端の放射状の突出片７，７の間隔を通じ外装鉄心１７、前部筒２２の内周と、２次ボビン、２次コイルとの間、及び後部筒１１の内部を満たし、開磁路鉄心、１次コイル、２次ボビン、２次コイルは絶縁オイル中に浸漬される。
【００２１】
請求項１から４のどの点火コイルも、使用するには、図１，図４，図５，図８に示すように筒形ケース８や前部筒２２の前端から同心状に突出する前向き筒２５に電気絶縁性で、弾力を有する、例えば合成ゴム製の筒形ブーツ２６を嵌めて延長状に保持し、この筒形ブーツを先頭にしてエンジンのプラグホール２７に挿入し、プラグホールの底から突出する点火プラグ２８の絶縁体の外に筒形ブーツを弾力的に嵌めることにより高圧端子９を点火プラグの頭部端子２９に圧接する。
【００２２】
請求項１から４のどの点火コイルでも、外装鉄心１７が硅素鋼板を円筒形に丸めたものであったり、割れ目１８を有すると前述したように点火コイルの動作時に、外装鉄心の表面に生じ易い不要な渦電流を減少させる効果を有し、鋼管を輪切りにしただけの外装鉄心の場合はその効果を有さないが、実用的には充分に使用できる。
【００２３】
図示の各実施形態では、後部筒１１に１次端子を取付けたものを使用したが、後部筒は１次端子を有さないものでもよい。又、請求項３の点火コイルでは、前部筒２２の環状段部２３と、後部筒１１の環状段部１４には、夫々緩衝シート２１ごと外装鉄心１７の前端部と、後端部とを嵌め、必要に応じ接着したが、前部筒の環状段部２３と、後部筒の環状段部１４に嵌めて固定するのは、外装鉄心の前端部と、後端部だけで、緩衝シートの前端部と後端部は嵌めなくてもよい。緩衝シート２１は割れ目１８を有する外装鉄心の場合、絶縁樹脂の洩れを防止する役目のほか、請求項３の点火コイルでは外装鉄心と熱硬化性絶縁樹脂層は緩衝シートが遮って直接接触させないため、樹脂層と外装鉄心との熱膨張差により外装鉄心から樹脂層中にクラックが入り、絶縁破壊を生じることがない。要するに外装鉄心を、熱硬化性樹脂を内部に注型するためのケースとして使用し、その内周の緩衝シートで熱ストレスによる応力を緩和し、絶縁性に優れた点火コイルを提供するのに役立つ。しかし、緩衝シートは必ずしも必要ではなく、割れ目を有する外装鉄心を使用する場合は、外装鉄心に割れ目を塞ぐ合成樹脂板などを接着して取付けるだけでもよい。
【００２４】
【発明の効果】
請求項１から４のどの点火コイルも、外装鉄心を有するので、中心の開磁路鉄心と共に略閉磁路を構成し、外部から磁気的影響を受けることがない。そして、この外装鉄心はアース端子に電気的に接続してあるので、１次端子を電源電池に接続する際、アース端子を電池のアース側に接続することにより外装鉄心は確実にアース電位になる。従って、外装鉄心に触れても感電することが無いと共に、２次コイルから外装鉄心に向う電界分布が一定になるので、外装鉄心とプラグホールの内壁間の距離が場所によって異なっても安定した出力が得られる。そして、請求項１から４に記載のように、外装鉄心に後向きの突出部を設け、アース端子には上記突出部が圧入される溝を設けておくと、外装鉄心の後部を後部筒の内周に圧入する際、前記突出部とアース端子の溝の向きを一致させることにより突出部はアース端子の溝に同時に圧入され、電気的に接続するので外装鉄心とアース端子を電線で接続する半田付け等の作業が不要になり、作業性が向上する。
【００２５】
更に、請求項３や４の点火コイルでは筒形ケースを使用せず、外装鉄心にケースの役目をさせるので、点火コイルの直径を小さくできると共に、直径を従来通りにすれば筒形ケースの肉厚分を他の部品に回すことができ、その分、絶縁性の確保や、性能、信頼性の向上が図れる。
【図面の簡単な説明】
【図１】請求項１の点火コイルの一例の使用状態の断面図である。
【図２】図１のＩＩ−ＩＩ線での拡大断面図である。
【図３】図１の外装鉄心と、アース端子の斜視図である。
【図４】請求項２の点火コイルの一例の使用状態の断面図である。
【図５】請求項３の点火コイルの一例の使用状態の断面図である。
【図６】図５のＶＩＩ−ＶＩＩ線での拡大断面図である。
【図７】図５の外装鉄心と、緩衝シートの斜視図である。
【図８】請求項４の点火コイルの一例の使用状態の断面図である。
【図９】（Ａ）は各請求項に使用した２次ボビンを前から見た正面図、（Ｂ）は同じく後部筒を前から見た正面図である。
【符号の説明】
１１次コイル
２２次コイル
３開磁路鉄心
４２次ボビン
８樹脂の筒形ケース
９高圧端子
１１後部筒
１３アース端子
１３′ アース端子の溝
１７外装鉄心
１９外装鉄心の突出部
２０熱硬化性絶縁樹脂層
２１緩衝シート
２２前部筒
３０絶縁オイル
３１蓋[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an elongated cylindrical ignition coil that is inserted into a plug hole provided in each cylinder of an engine, presses a high voltage terminal against a head terminal of the ignition plug at the bottom of the plug hole, and applies a high voltage to the ignition plug. About.
[0002]
[Prior art]
As an ignition plug to be used in this way, an open magnetic circuit core is inserted into a bobbin whose front end is made of an insulating material, and a primary coil and a secondary coil are provided concentrically outside the bobbin. It is placed concentrically inside, and epoxy resin is cast in the case, and the open magnetic circuit core, bobbin, primary coil, and secondary coil are fixed in the epoxy resin layer, and the silicon steel sheet is outside the insulating case. the rounded, which fitted a shielding member of tubular shape having a split is known from JP-5-13 5 967. This shield member forms a substantially closed magnetic circuit together with the central open magnetic circuit core, and protects the ignition coil so that the ignition coil is not magnetically influenced from the outside. Further, the cracks in the shield member reduce unnecessary eddy currents that are likely to occur on the surface of the shield member during operation of the ignition coil. The high-voltage terminal is attached to the closed front end of the bobbin via an insulating material and protrudes outward from the front end of the epoxy resin layer.
[0003]
[Problems to be solved by the invention]
Since the outer diameter of the ignition coil is smaller than the inner diameter of the plug hole because the ignition coil is inserted and attached to the plug hole provided in the cylinder of each cylinder of the internal combustion engine, the cylindrical shield member is at ground potential. There is no contact with the inner surface of the plug hole. And, since a high voltage of 30,000 to 40,000 volts is generated in the secondary coil of the ignition coil, the conductive shield member is charged, and an electric shock is caused when the shield member is touched when the ignition coil is removed. There is. Also, if the ignition coil is not concentrically mounted in the plug hole, and the distance between the outer iron core and the inner wall of the plug hole varies depending on the location, the electric field distribution is not constant, and the output characteristics of the ignition coil There is also a problem that becomes unstable.
[0004]
[Means for Solving the Problems]
Accordingly, the present invention provides the above-mentioned problem by providing a ground terminal to be connected to the ground side of the battery when the primary terminal is connected to the power source battery in the ignition coil, and electrically connecting the exterior iron core to the ground terminal. Has been eliminated.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The ignition coil for an internal combustion engine according to claim 1 has an open magnetic circuit core in the center of an elongated cylindrical case of resin having a high voltage terminal at a closed front end, a primary coil and a secondary coil concentrically outside. the provided, fitted outside the outer core of the circle cylindrical that by the magnetic metal plate of said cylindrical casing, fitted rear portion of the tubular casing and the outer core to the rear barrel of a resin having a ground terminal, The outer core and the ground terminal are connected, and the open magnetic circuit core, primary coil, and secondary coil are fixed in the rear cylinder and the thermosetting insulating resin layer cast in the cylindrical case. Providing a rearward projecting part, a ground terminal in the rear cylinder is provided with a groove into which the projecting part is press-fitted, and the projecting part is press-fitted into the ground terminal groove to connect the outer core and the grounding terminal. To do.
An ignition coil for an internal combustion engine according to claim 2 has an open magnetic circuit core in the center of an elongated cylindrical case of resin having a high-voltage terminal at a closed front end, a primary coil concentrically outside the core, and 2 the following coils provided, fitted outside the exterior core circle cylindrical that by the magnetic metal plate of said cylindrical casing, fitting the rear portion of the tubular casing and the outer core to the rear barrel of a resin having a ground terminal and connects the outer core and the ground terminal, a rear cylinder, and injecting an insulating oil into the tubular casing, and by immersing the open magnetic circuit iron core and the primary coil and the secondary coil in the insulating oil, the outer core The ground terminal on the rear cylinder is provided with a groove into which the projecting part is press-fitted, and the projecting part is press-fitted into the ground terminal groove to connect the outer iron core and the ground terminal. And
The ignition coil for an internal combustion engine according to claim 3 includes a resin front tube having a high voltage terminal at a closed front end, a resin rear tube having a ground terminal, and a cylindrical outer iron core made of a magnetic metal plate, The front end of the outer core is fitted and fixed to the front cylinder and the rear end is fitted to the rear cylinder, and the open magnetic circuit core is placed in the center of the interior surrounded by the outer core, outside the open magnetic circuit core. A primary coil and a secondary coil are provided concentrically, the exterior core and the ground terminal are connected, and the interior of the front cylinder, the interior surrounded by the exterior core, and the interior of the rear cylinder are filled with thermosetting insulating resin. A primary coil, a secondary coil, and an open magnetic circuit core are fixed in the insulating resin layer , a rearward projecting portion is provided on the outer core, and the projecting portion is press-fitted into the ground terminal in the rear cylinder. And press the projecting part into the groove of the ground terminal to connect the armature and the ground terminal. Characterized in that it was.
The ignition coil for an internal combustion engine according to claim 4 includes a resin front tube having a high voltage terminal at a closed front end, a resin rear tube having a ground terminal, and a cylindrical outer iron core made of a magnetic metal plate, The front end of the outer core is fitted and fixed to the front cylinder and the rear end is fitted to the rear cylinder, and the open magnetic circuit core is placed in the center of the interior surrounded by the outer core, outside the open magnetic circuit core. A primary coil and a secondary coil are provided concentrically, the outer core and the ground terminal are connected, and insulating oil is injected into the inside of the front cylinder, the inside surrounded by the outer iron core, and the rear cylinder, insulating oil primary coil during the secondary coil, and open and the magnetic path core is immersed, the rearward projecting portions provided on the outer core, the groove to the ground terminal on the rear cylinder the projecting portion is press-fitted The projecting part was press-fitted into the ground terminal groove to connect the outer core and the ground terminal. And wherein the door.
[0006]
【Example】
In the illustrated embodiments of claims 1, 2, 3 and 4, 1 is a primary coil, 2 is a secondary coil, and 3 is an open magnetic circuit core.
The open magnetic circuit core 3 is a well-known one formed by laminating a plurality of strip-shaped silicon steel plates so that the cross-sectional shape is close to a circle as shown in FIGS. 2 and 6. The primary coil 1 is covered with an insulating material such as a secondary bobbin and is wound on the insulating material. The secondary coil 2 is wound around the outer periphery of the secondary bobbin 4 by split winding, although omitted in the drawing. The secondary bobbin 4 has a cylindrical shape with the front end closed and the rear end open. The front bobbin 4 has a front projection 5 and a rear cylinder 6 at the center of the front end. Three projecting pieces 7 project radially (see FIG. 9A). The cylindrical part 6 is for inserting the front end part of the open magnetic circuit core and supporting the open magnetic circuit core concentrically inside the secondary bobbin.
[0007]
The ignition coil according to claim 1 shown in FIGS. 1 to 3 will be described. Reference numeral 8 denotes an exterior resin elongated cylindrical case in which a high-voltage terminal 9 is protruded and attached to the center of a closed front end portion. At the center of the front end portion, a receiving cylinder 10 for receiving the protrusion 5 of the secondary bobbin is provided rearward.
[0008]
Reference numeral 11 denotes a resin rear tube in which a primary terminal and a ground terminal 13 are attached in a penetrating manner to the connector portion 12 protruding from the outer periphery of the rear portion, and the outer diameter thereof is larger than the outer diameter of the cylindrical case 8. As shown in FIG. 9B, the rear cylinder has an annular step portion 14 in which the rear end portion of the cylindrical case 8 is fitted on the inner periphery of the front end portion, and the rear of the open magnetic circuit core at the center of the inside. A support tube 15 that fits and holds the end portion is provided. The support cylinder 15 is integrally supported inside the rear cylinder by a protrusion 16 that protrudes radially inward from the inner periphery of the rear cylinder. The protruding piece 6 protruding from the outer periphery of the rear end portion of the secondary bobbin mentioned above contacts the inner periphery of the cylindrical case. The cylindrical case 8 and the rear cylinder 11 are both molded products of synthetic resin.
[0009]
Reference numeral 17 denotes a cylindrical outer iron core (cylindrical shield member) made of a magnetic metal plate. Even if the outer iron core has a length of 1 turn or more, that is, a silicon steel sheet with a length of more than the circumference is rounded into a cylindrical shape and a part of the steel sheet is polymerized inside and outside, the silicon with a length of 1 turn or less You may comprise so that a steel plate may be rounded cylindrically and it may have the crack 18. FIG. Further, a steel pipe or the like may be cut into a predetermined length, or a steel pipe that is cut in such a manner may have one axial crack 18 formed therein. In the illustrated embodiment, a silicon steel sheet having a length of one turn or less is rolled into a cylindrical shape, and therefore has a crack 18. The inner diameter of the outer core 17 is the same as or slightly smaller than the outer diameter of the cylindrical case 7, or the outer diameter is equal to or slightly larger than the inner diameter of the annular step 14 of the rear cylinder. The length is the same as or slightly shorter than the cylindrical case 7.
[0010]
To assemble the ignition coil, the forward projection 5 of the secondary bobbin is inserted into the receiving cylinder 10 of the cylindrical case 8, and the protruding piece 7 at the rear end of the secondary bobbin is in contact with the inner peripheral rear part of the cylindrical case 8. Thus, the cylindrical case and the secondary bobbin are kept concentric, and the high voltage end of the secondary coil is electrically connected to the high voltage terminal 9 of the cylindrical case. In the case of an exterior iron core obtained by rounding a silicon steel plate into a cylindrical shape, or an exterior iron core formed by cutting a steel pipe and forming a crack, the diameter can be increased. Therefore, the diameter of the exterior iron core 17 can be increased, and the outer core 17 can be cracked. 18 is expanded to increase the diameter of the iron core, the rear end is aligned with the rear end of the cylindrical case, and is fitted outside the cylindrical case 8, and bonded if necessary. In addition, since the outer core that is simply cut into a steel pipe cannot be expanded in diameter, it is made using a steel pipe whose inner diameter matches the outer diameter of the cylindrical case, and the rear end is aligned outside the cylindrical case. Fit, glue and fix. Then, the open magnetic path iron core 3 is inserted into the secondary bobbin together with the primary coil, the front end portion thereof is inserted into the cylindrical portion 6 of the secondary bobbin, and the rear portion of the open magnetic path iron core is the support cylinder of the rear cylinder. 15, the rear portion of the cylindrical case and the outer iron core is press-fitted into the annular stepped portion 14 of the rear cylinder while being placed in the outer cylinder 15, and the primary coil, secondary bobbin, cylindrical case, and rear cylinder are concentric outside the open magnetic circuit core. Keep on. Then, the primary coil wire and the like are electrically connected to the ground terminal 13 by passing the wire attached to the outer iron core through the notch 14 ′ provided in the annular step portion.
[0011]
As shown in FIG. 3, the outer iron core 17 is provided with a rearward projecting portion 19, the ground terminal 13 has a groove 13 ′ into which the projecting portion is press-fitted, and the projecting portion 19 is formed in the annular step 14 on the inner periphery of the rear cylinder. By providing a notch 14 'that passes therethrough, when the cylindrical case and the rear portion of the outer iron core are press-fitted into the inner periphery of the rear cylinder, the protruding portion 19 and the ground terminal groove 13' are aligned so that the protruding portion 19 is simultaneously press-fitted into the groove 13 'of the ground terminal through the notch 14', so that the operation of soldering for connecting the outer iron core and the ground terminal with an electric wire becomes unnecessary.
[0012]
Then, a thermosetting insulating resin such as an epoxy resin is vacuum-cast from inside the rear end of the rear cylinder 11. As a result, the resin flows into the secondary bobbin 4 later, fills the space between the inner periphery of the secondary bobbin, the primary coil 1, the open magnetic path core 3, and the support cylinder 15 and hardens the secondary bobbin. Through the interval between the radially projecting pieces 7 and 7 at the rear end, the resin layer is solidified by filling the inner circumference of the cylindrical case 8, the space between the secondary bobbin and the secondary coil, and the interior of the rear cylinder 11. At 20, the open magnetic path iron core, the primary coil, the secondary bobbin, the secondary coil, the cylindrical case, and the rear cylinder are fixed concentrically, and the ignition coil according to claim 1 is completed.
[0013]
FIG. 4 shows an ignition coil according to claim 2, wherein the ignition coil is assembled in the same manner as in claim 1, and insulating oil is introduced from the rear end inside the rear cylinder 11 instead of a thermosetting insulating resin such as epoxy resin. 30 is injected. As a result, the insulating oil flows into the secondary bobbin 4 later and fills the space between the inner periphery of the secondary bobbin, the primary coil 1, the open magnetic circuit core 3, and the support cylinder 15, and the secondary bobbin Through the interval between the radial protrusions 7 and 7 at the rear end, the inner circumference of the cylindrical case 8, the space between the secondary bobbin and the secondary coil, and the inside of the rear cylinder 11 are filled, and the open magnetic circuit core and the primary coil The secondary bobbin and the secondary coil are immersed in the insulating oil 30. Then, a lid 31 is attached to the rear end portion of the rear cylinder 11 by adhesion, high frequency welding or the like to prevent leakage of insulating oil.
[0014]
The ignition coil according to claim 3 shown in FIGS. 5 to 7 uses the above-described cylindrical outer iron core 17 instead of the cylindrical case 8 and, if necessary, a buffer sheet 21 on the inner periphery of the outer iron core 17. Along. Similarly to the outer core of claim 1 or 2, for example, a silicon steel plate having a length of 1 turn or more, that is, a length of a circumference or more is rounded into a cylindrical shape, and a part of the steel plate is polymerized inside and outside. Alternatively, a silicon steel plate having a length of one turn or less may be rounded into a cylindrical shape so as to have a crack 18. Further, a steel pipe or the like may be cut into a predetermined length, or a steel pipe that is cut in such a manner may have one axial crack 18 formed therein. In the illustrated embodiment, a silicon steel plate having a length of one turn or less is rolled into a cylindrical shape and thus has a crack 18, so that the buffer sheet 21 closes the crack from the inside. The buffer sheet 21 is made of aramid polymer paper, synthetic resin film, glass cloth, or the like. The buffer sheet may be cylindrical in advance and inserted into the outer core, or the sheet may be inserted into the outer core while rolling the sheet.
[0015]
Reference numeral 22 denotes a resin front tube having a high voltage terminal 8 projecting forward and attached to the center of the closed front end portion. The front tube has an annular step portion 23 having a reduced diameter at the rear portion of the outer periphery and is closed. In the center of the front end, a receiving cylinder 24 for receiving the projection 5 of the secondary bobbin is provided rearward. The rear cylinder 11 uses the one described in claims 1 and 2, and the rear portion of the outer iron core 17 is press-fitted into the annular step portion 14 provided on the inner periphery of the front end portion.
[0016]
To assemble the ignition coil of claim 3, the forward projection 5 of the secondary bobbin is inserted into the receiving cylinder 24 of the front cylinder 22, and the high voltage end of the secondary coil is electrically connected to the high voltage terminal 8 of the front cylinder. At the same time, the front end portion of the outer core 17 having the buffer sheet 21 fitted on the inner periphery thereof is fitted to the annular step portion 23 on the outer periphery of the rear portion of the front tube, and if necessary, bonded and fixed. Then, the open magnetic path iron core 3 is inserted into the secondary bobbin together with the primary coil, the front end portion thereof is inserted into the cylindrical portion 6 of the secondary bobbin, and the rear portion of the open magnetic path iron core is the support cylinder of the rear cylinder. 15, the rear portion of the outer iron core 17 is press-fitted into the annular stepped portion 14 of the rear cylinder while being placed in the outer cylinder 15, and the front cylinder, the primary coil, the secondary bobbin, the outer iron core, and the rear cylinder are concentric outside the open magnetic path iron core. Keep on. The radial protruding piece 7 at the rear end of the secondary bobbin is in contact with the inner periphery of the outer iron core or the buffer sheet 21 inside thereof. Then, the primary coil wire and the like are electrically connected to the ground terminal 13 by passing the wire attached to the outer iron core through the notch 14 ′ provided in the annular step portion.
[0017]
Also in this case, as shown in FIG. 3, a rearward projecting portion 19 is provided on the outer iron core 17, the groove 13 'into which the projecting portion is press-fitted into the ground terminal 13, and the annular step 14 on the inner periphery of the rear cylinder. By providing a notch 14 'through which the protrusion 19 passes, the direction of the protrusion 19 and the groove 13' of the ground terminal coincide with each other when the rear part of the outer core is press-fitted into the annular step 14 on the inner periphery of the rear cylinder. By doing so, the projecting portion 19 is simultaneously press-fitted into the groove 13 'of the ground terminal through the notch 14', and the work such as soldering for connecting the outer core and the ground terminal with an electric wire becomes unnecessary.
[0018]
Then, a thermosetting insulating resin such as an epoxy resin is vacuum-cast from inside the rear end of the rear cylinder 11. As a result, the resin flows into the secondary bobbin 4 later, fills the space between the inner periphery of the secondary bobbin, the primary coil 1, the open magnetic path core 3, and the holding cylinder 15 and hardens the secondary bobbin. Through the interval between the radially protruding pieces 7 and 7 at the rear end, the buffer sheet 21, the inner periphery of the front cylinder 22, the space between the secondary bobbin and the secondary coil, and the interior of the rear cylinder 11 are solidified and thus solidified. With the solidified resin layer 20, the open magnetic circuit core, the primary coil, the secondary bobbin, the secondary coil, the front cylinder, the rear cylinder, and the exterior iron core having the buffer sheet on the inner periphery are fixed concentrically. In the case of an exterior iron core having a crack 18, since the buffer sheet 21 is closed from the inside, the insulating resin does not leak out from the crack during vacuum casting.
[0019]
When an aramid polymer paper is used for the buffer sheet 21, the insulation resistance and heat resistance can be improved. Use of a synthetic resin film is advantageous in terms of workability and cost, and use of a glass cloth improves the adhesion with the insulating resin layer 20 because the insulating resin penetrates and hardens.
[0020]
The ignition coil of claim 4 also uses the outer iron core 17 instead of the cylindrical case, and is assembled in the same manner as the ignition coil of claim 3, and the rear cylinder 11 is replaced with insulating oil 30 instead of a thermosetting insulating resin such as epoxy resin. Inject from the back end. Insulating oil is injected and cracks such as the insulating resin layer do not occur. Therefore, it is not necessary to provide the buffer sheet 21 on the inner periphery of the outer iron core. However, when the crack 18 is present, the insulating oil is prevented from leaking. Therefore, the synthetic resin plate 32 or the like is attached to the crack 18 from inside or outside by adhesion or the like. The insulating oil thus injected flows into the secondary bobbin 4 later, fills the space between the inner periphery of the secondary bobbin, the primary coil 1, the open magnetic circuit core 3, and the holding cylinder 15, and the secondary bobbin. Through the space between the radially protruding pieces 7 and 7 at the rear end of the bobbin, the outer core 17, the inner periphery of the front tube 22, the space between the secondary bobbin and the secondary coil, and the interior of the rear tube 11 are filled to open the magnet. The road iron core, primary coil, secondary bobbin, and secondary coil are immersed in insulating oil.
[0021]
In order to use any of the ignition coils of claims 1 to 4, as shown in FIGS. 1, 4, 5, and 8, a forward-facing cylinder that projects concentrically from the front end of the cylindrical case 8 or the front cylinder 22 A cylindrical boot 26 made of, for example, synthetic rubber, which is electrically insulating and elastic, is fitted and held in an extended shape, and is inserted into the plug hole 27 of the engine with the cylindrical boot as the head, and the bottom of the plug hole The high voltage terminal 9 is pressed against the head terminal 29 of the spark plug by elastically fitting a cylindrical boot outside the insulator of the spark plug 28 protruding from the head.
[0022]
In any of the ignition coils according to claims 1 to 4, when the outer iron core 17 is formed by rolling a silicon steel plate into a cylindrical shape or has a crack 18, as described above, the outer iron core 17 is likely to be generated on the surface of the outer iron core during the operation of the ignition coil. It has the effect of reducing unnecessary eddy currents, and in the case of an armored iron core that is simply made by cutting a steel pipe, it does not have that effect, but it can be used practically.
[0023]
In the illustrated embodiments, the rear cylinder 11 with the primary terminal attached is used, but the rear cylinder may not have the primary terminal. In the ignition coil of claim 3, the annular step 23 of the front tube 22 and the annular step 14 of the rear tube 11 are respectively provided with a front end portion and a rear end portion of the outer iron core 17 together with the buffer sheet 21. It is fitted and bonded as necessary, but it is only the front end portion and the rear end portion of the outer iron core that is fitted and fixed to the annular step portion 23 of the front tube and the annular step portion 14 of the rear tube. The front end and the rear end need not be fitted. In the case of the outer iron core having the crack 18, the buffer sheet 21 serves to prevent leakage of the insulating resin. In the ignition coil according to claim 3, the outer iron core and the thermosetting insulating resin layer are blocked by the buffer sheet and are not in direct contact with each other. A crack does not enter the resin layer from the outer iron core due to a difference in thermal expansion between the resin layer and the outer iron core, and dielectric breakdown does not occur. In short, the exterior iron core is used as a case for casting thermosetting resin inside, and the buffer sheet on the inner periphery helps to relieve stress caused by thermal stress and provide an ignition coil with excellent insulation. . However, the buffer sheet is not necessarily required, and when an exterior iron core having a crack is used, a synthetic resin plate or the like that closes the crack may be attached and attached to the exterior iron core.
[0024]
【The invention's effect】
Since any ignition coil according to claims 1 to 4 has an outer core, it forms a substantially closed magnetic path together with the central open magnetic path core and is not magnetically influenced from the outside. Since the outer core is electrically connected to the ground terminal, when the primary terminal is connected to the power supply battery, the outer core is surely at the ground potential by connecting the ground terminal to the ground side of the battery. . Therefore, there is no electric shock even when touching the outer core, and since the electric field distribution from the secondary coil to the outer core is constant, stable output can be achieved regardless of the distance between the outer core and the inner wall of the plug hole. Is obtained. Further, as described in claims 1 to 4 , when a rearward projecting portion is provided in the outer iron core and a groove into which the projecting portion is press-fitted is provided in the ground terminal, the rear portion of the outer iron core is placed inside the rear cylinder. When press-fitting to the circumference, by aligning the direction of the groove of the protrusion and the ground terminal, the protrusion is simultaneously press-fitted into the groove of the ground terminal and electrically connected. Work such as attaching becomes unnecessary, and workability is improved.
[0025]
Furthermore, in the ignition coil according to claims 3 and 4, the cylindrical case is not used, and the outer iron core serves as the case, so that the diameter of the ignition coil can be reduced and the diameter of the cylindrical case can be reduced by changing the diameter to the conventional value. The thickness can be turned to other parts, and insulation can be secured, and performance and reliability can be improved accordingly.
[Brief description of the drawings]
FIG. 1 is a sectional view of an example of an ignition coil according to claim 1 in use.
FIG. 2 is an enlarged cross-sectional view taken along the line II-II in FIG.
3 is a perspective view of the exterior iron core and the ground terminal of FIG. 1. FIG.
FIG. 4 is a sectional view of an example of the ignition coil according to claim 2 in use.
FIG. 5 is a sectional view of an example of the ignition coil according to claim 3 in use.
6 is an enlarged cross-sectional view taken along line VII-VII in FIG.
7 is a perspective view of the exterior iron core of FIG. 5 and a buffer sheet. FIG.
FIG. 8 is a sectional view of an example of the ignition coil according to claim 4 in use.
FIG. 9A is a front view of a secondary bobbin used in each claim as seen from the front, and FIG. 9B is a front view of the rear cylinder as seen from the front.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Primary coil 2 Secondary coil 3 Open magnetic path iron core 4 Secondary bobbin 8 Resin cylindrical case 9 High voltage terminal 11 Rear cylinder 13 Ground terminal 13 'Groove of earth terminal 17 Armored iron core 19 Projection 20 of armored iron core Thermosetting Insulating resin layer 21 Buffer sheet 22 Front cylinder 30 Insulating oil 31 Lid

Claims

An open magnetic circuit iron core is provided at the center of the inside of a long cylindrical resin case having a high-voltage terminal at the closed front end, and a primary coil and a secondary coil are provided concentrically outside the cylindrical case. fitted outer core of by that circle cylindrical metal plate, fitted rear portion of the tubular casing and the outer core to the rear barrel of a resin having a ground terminal, and connect the outer core and the ground terminal, the rear barrel And an ignition coil of an internal combustion engine in which an open magnetic circuit core, a primary coil, and a secondary coil are fixed in a thermosetting insulating resin layer cast in a cylindrical case ,
The exterior iron core is provided with a rearward projecting part, the ground terminal on the rear cylinder is provided with a groove into which the projecting part is press-fitted, and the projecting part is press-fitted into the ground terminal groove to connect the exterior iron core and the grounding terminal. An ignition coil for an internal combustion engine.

An open magnetic circuit iron core is provided at the center of the inside of a long cylindrical resin case having a high-voltage terminal at the closed front end, and a primary coil and a secondary coil are provided concentrically outside the cylindrical case. fitted outer core of by that circle cylindrical metal plate, fitted rear portion of the tubular casing and the outer core to the rear barrel of a resin having a ground terminal, and connect the outer core and the ground terminal, the rear barrel And an ignition coil of an internal combustion engine in which insulating oil is injected into the cylindrical case, and the open magnetic circuit core, the primary coil, and the secondary coil are immersed in the insulating oil .
The exterior iron core is provided with a rearward projecting part, the ground terminal on the rear cylinder is provided with a groove into which the projecting part is press-fitted, and the projecting part is press-fitted into the ground terminal groove to connect the exterior iron core and the grounding terminal. An ignition coil for an internal combustion engine.

A resin front tube having a high voltage terminal at the closed front end, a resin rear tube having a ground terminal, and a cylindrical outer iron core made of a magnetic metal plate, the front end of the outer iron core being a front tube The rear end part is fitted and fixed to the rear cylinder, and the open magnetic circuit core is concentrically formed in the center surrounded by the outer core, and the primary coil and the secondary coil are concentric outside the open magnetic circuit core. The outer iron core and the ground terminal are connected to each other, and the inside of the front tube, the inner portion surrounded by the outer iron core, and the inner portion of the rear tube are filled with thermosetting insulating resin, and the primary coil is placed in the insulating resin layer. In the ignition coil of the internal combustion engine in which the secondary coil and the open magnetic circuit core are fixed ,
The exterior iron core is provided with a rearward projecting part, the ground terminal on the rear cylinder is provided with a groove into which the projecting part is press-fitted, and the projecting part is press-fitted into the ground terminal groove to connect the exterior iron core and the grounding terminal. An ignition coil for an internal combustion engine.

A resin front tube having a high voltage terminal at the closed front end, a resin rear tube having a ground terminal, and a cylindrical outer iron core made of a magnetic metal plate, the front end of the outer iron core being a front tube The rear end part is fitted and fixed to the rear cylinder, and the open magnetic circuit core is concentrically formed in the center surrounded by the outer core, and the primary coil and the secondary coil are concentric outside the open magnetic circuit core. Insulating oil is injected into the interior of the front cylinder, the interior surrounded by the exterior core, and the interior of the rear cylinder. The primary coil and the secondary coil are injected into the insulating oil. In an ignition coil of an internal combustion engine in which an open magnetic path iron core is immersed ,
The exterior iron core is provided with a rearward projecting part, the ground terminal on the rear cylinder is provided with a groove into which the projecting part is press-fitted, and the projecting part is press-fitted into the ground terminal groove to connect the exterior iron core and the grounding terminal. An ignition coil for an internal combustion engine.