JPWO2003071562A1

JPWO2003071562A1 - Ignition coil for internal combustion engine

Info

Publication number: JPWO2003071562A1
Application number: JP2003570372A
Authority: JP
Inventors: 大槻　英樹; 英樹大槻; 研司中林; 田中　宏幸; 宏幸田中; 義秋島津
Original assignee: Hitachi Ltd; Hitachi Car Engineering Co Ltd
Current assignee: Hitachi Ltd; Hitachi Automotive Systems Engineering Co Ltd
Priority date: 2002-02-21
Filing date: 2002-02-21
Publication date: 2005-06-16
Also published as: WO2003071562A1

Abstract

コイルケースに、閉磁路を形成するコアと、１次コイル及び２次コイルが内装される。１次コイル、２次コイルは一つのボビンに軸方向に並んで配置されている。ボビンの中央部に２次コイルが巻線される。１次コイルは、２次コイルの低電圧側と高電圧側に分割して巻かれる。２次コイルの低電圧側の引き出し線は、ボビンの一端外周に設けた溝を介してボビンと１次コイルの間を通され、かつボビン一端に設けた端子に接続される。１次コイルの巻線部をつなぐ引き出し線は、２次コイルに接触しないように掛け渡される。このように構成することで、一つのボビンに、軸方向に並ぶようにして１次コイルと２次コイルを巻線するタイプの独立点火型の点火コイルにおいて、小形にして出力向上を図ることができる。A core that forms a closed magnetic circuit, a primary coil, and a secondary coil are internally provided in the coil case. The primary coil and the secondary coil are arranged side by side in the axial direction on one bobbin. A secondary coil is wound around the center of the bobbin. The primary coil is divided and wound on the low voltage side and the high voltage side of the secondary coil. The lead wire on the low voltage side of the secondary coil is passed between the bobbin and the primary coil through a groove provided on the outer periphery of one end of the bobbin, and is connected to a terminal provided on one end of the bobbin. The lead wire connecting the winding portion of the primary coil is routed so as not to contact the secondary coil. With this configuration, the independent ignition type ignition coil in which the primary coil and the secondary coil are wound on one bobbin so as to be aligned in the axial direction can be reduced in size to improve the output. it can.

Description

技術分野
本発明は、内燃機関用点火コイル（点火装置）に係り、特に内燃機関のシリンダヘッドのプラグホール内に収納して、点火プラグに直結して使用するのに適した筒形の点火コイルに関する。
背景技術
内燃機関用点火コイルとして、内燃機関の各気筒ごとに用意され、点火プラグに直結して使用される、いわゆる独立点火型の点火コイルが知られている。
この種の点火コイルは、磁路を形成するコアの周囲に１次コイルと２次コイルとを同心状に配置するタイプと、一つのボビンに、軸方向に並ぶようにして１次コイルの巻線部と２次コイルの巻線部を配置するタイプのものが知られている。
後者のタイプとしては、例えば、特開平２−２３０９６４号公報に開示されたものがある。
独立点火型の点火コイルは、内燃機関のシリンダヘッドのプラグホール内に収納して使用するために、コイル部のスペースが非常に狭く、この限られたスペースの中でいかに高出力の点火エネルギーを点火プラグに供給するかが課題となっていた。
本発明の目的は、一つのボビンに、軸方向に並ぶようにして１次コイルと２次コイルを巻線するタイプの独立点火型の点火コイルにおいて、小形にして出力向上を図ることができる内燃機関の点火コイル装置を提供することにある。
発明の開示
上記目的を達成するために、本発明は基本的には次のように構成する。
（１）一つのボビンに、１次コイルと２次コイルとを軸方向に並ぶようにして配置した独立点火型の内燃機関用点火コイルにおいて、次のように構成する。
すなわち、前記ボビンの中央部に前記２次コイルが巻線され、前記１次コイルは、前記２次コイルの低電圧側と高電圧側に分割して巻かれていることを特徴とする。
従来のこの種タイプの点火コイルは、一つのボビンの軸方向において一方の領域に１次コイルを配置し、他方の領域に２次コイルを配置していた。
これに対して、本発明は、ボビンの軸方向において、２次コイルの低電圧側と高電圧側に１次コイルを分割巻きする。このように１次コイルを分割巻きすることで、１次コイルと２次コイル間の結合係数を従来よりも高めることができる。そのために、限られたスペースの中で高出力の内燃機関用点火コイルを製作することができる。
（２）上記基本構成に付随して、次のようなコイル配線構造も提案する。
前記２次コイルの低電圧側の引き出し線は、前記ボビンの一端外周に設けた溝を介して前記ボビンと前記１次コイルの間を通され、このようにして２次コイルをボビン一端に設けた端子に接続されるようにした。
また、前記ボビンのうち前記２次コイルの低電圧側に隣接する一端外周を低電圧側外周、前記２次コイルの高電圧側に隣接する一端外周を高電圧側外周と定義すると、前記１次コイルは、前記ボビンの低電圧側外周から巻かれるようにする。そして、その低電圧側外周における１次コイル巻き終わりの引き出し線が前記２次コイルの外側に沿って低電圧側，高電圧側に設けたつば部に掛け渡されて、コイルの残りが前記高電圧側外周に巻かれており、前記高電圧側外周の１次コイル巻き終わりの引き出し線が再び前記２次コイルの外側に沿って前記ボビンの高電圧側，低電圧側のつば部に掛け渡されて端子と電気的に接続されるようにした。
このようにすれば、１次コイルを２次コイルの低電圧側，高電圧側の双方に分割巻きする場合であっても、両者のコイルの干渉をなくしてコイルの配線引廻しを行うことができる。
（３）さらに、次のような独立点火型の内燃機関用点火コイルを提案する。
前記１次コイルと２次コイルが一つのボビンに軸方向に並んで配置される。前記コアは、磁路に垂直な断面がＤの字形に積層した鋼板であり、閉磁路構造をなしている。前記ボビンも、軸方向に垂直な断面が前記コアの断面形状に合わせてある。前記コアは、閉磁路のうち平行配置される長手方向の磁路の一方（以下、「磁路Ａ」と称する）に前記ボビンが嵌合し、且つ前記磁路Ａと平行なもう一方の磁路（以下、「磁路Ｂ」と称する）が前記１次コイル、２次コイルの外側に沿って配置される。前記ボビンに配設される各つば部は、その外縁一部が直線をなし、この外縁一部に前記磁路Ｂの前記断面Ｄの字の直線辺に相当する側面があてがわれ或いは近接するように前記磁路Ｂが配置される。
このようにして、出力向上を図れる閉磁路タイプのコア全体が前記１次コイル、２次コイルと共に一つのコイル組立体としてコンパクトにまとめられて円筒のケースに収納されている。
（４）さらに次のような発明を提案する。
閉磁路を形成するコアと、前記コアの外周一部にボビンを介して配置される１次コイル及び２次コイルと、前記１次コイル及び２次コイルを駆動するための点火駆動回路ユニットとを備えた内燃機関用点火コイルにおいて、前記１次コイル，２次コイルを収容する筒状のケースに前記閉磁路型のコア全体と前記点火駆動回路ユニットを収納する。また、このボビンは、中央部に前記２次コイルを巻き、前記ボビンの両端には、前記２次コイルを挟むようにして前記１次コイルが分割巻きされていることを特徴とする。
２次コイルの軸方向の両側に１次コイルを配置することは、コイルの結合係数を高め、コイル組立体のコンパクト化及び収納性を高めることができる。そのため、コイルケースに点火コイルの駆動回路ユニットも収納可能になる。さらに、この駆動回路と合わせて閉磁路のコア全体も筒状ケースに収納することで、コイルケース内の部品の実装密度を高めることができる。
発明を実施するための最良の形態
本発明の実施例を、図面を用いて説明する。
まず、本実施例に係る点火コイルの構造を第１図〜７図により説明するのに先立ち、第８図により本実施例に係る点火コイルの電気回路について説明する。
図中、２は点火コイルの磁路を形成するためのコア、４は１次コイル、５は２次コイルである。
１次コイル４の一端４′と２次コイル５の低電圧側の一端５′は、バッテリ電源に通じる電源供給端子９Ａと接続されている。１次コイル４の他端４″は、点火駆動回路ユニット（以下、「イグナイタ」と称する）６のスイッチング回路１０５の端子１０Ａと接続されている。
２次コイル５の高電圧側の一端５′は、高電圧ダイオード２０及び高電圧端子１６を介して点火プラグ１０と電気的に接続されている。
イグナイタ６は、１次コイルのスイッチング素子となるメインの絶縁ゲート形バイポーラトランジスタ（以下「ＩＧＢＴ」という）１００及びサブＩＧＢＴ１０１と、１次コイル４に流れる電流を制限するための電流制限回路１０９と、電流検出抵抗１０２、点火信号の入力抵抗１０７、ブリーダ抵抗１０８等から構成されている。
電流検出抵抗１０２は、サブＩＧＢＴ１０１のエミッタとＧＮＤ間に設けられている。ＩＧＢＴ１０５のゲートとコレクタ間には、温度特性に優れたポリシリコンで構成した相方向ポリシリコンツェナーダイオード１０３を挿入し、１次電圧を４００〜５５０Ｖでクランプしている。
イグナイタ６の信号入力端子９ｃとグラウンド（ＧＮＤ）間には、ブリーダ抵抗１０８を挿入し、入力信号接続部の接点電流を１ｍＡ以上とし、端子９ＣのめっきをＳｎめっきでも十分な接続信頼性が得られるようにしている。
上記回路構成において、ＩＧＢＴ（スイッチング素子）１００により、１次コイル４に流れる１次電流を点火信号に基づき通電遮断することにより、２次コイル５に点火用の高電圧が誘起される。
高電圧ダイオード２０は、２次コイル５で発生した高電圧を、高電圧端子１６，スプリング１７（第１図参照）を介して点火プラグ１０に供給する場合に、過早着火を防止する役割をなす。
電源供給端子９Ａ（ＶＢ）、ＧＮＤ端子９Ｂ、点火信号入力端子９Ｃ（Ｓ）は、点火コイル装置のコネクタ部１Ｃ（第１図、第４図参照）に配置される。
ここで、点火コイルの構造について、第１図〜第７図により説明する。
点火コイルのケース（以下、「コイルケース」と称する）１は、熱可塑性合成樹脂、例えば、ポリブチレンテレフタレート（以下「ＰＢＴ」という）や、ポリフェニレンサルファイド（以下「ＰＰＳ」という）ＰＰＳ等）で細長の円筒状に成形して作られている。
コイルケース１は、コイル収納部１Ａと、点火プラグ接続部１Ｄと、イグナイタ６を収納するためのイグナイタケース１Ｂと、外部端子接続用のコネクタ部１Ｃとを一体に成形してなる。
コイル収納部１Ａには、閉磁路コア２、１次コイル４、２次コイル５が収納される。
イグナイタケース１Ｂは、例えばボックス形状をなし、その内部に点火コイルを駆動するためのイグナイタ６が収納される。
点火コイルのコア２は、略長方形の環状の閉磁路をなし、その長手方向の磁路Ａ，Ｂはコイルケース１の軸方向に向いて平行に配置されている。また、コア２は第６図に示すように２０１と２０２とに分割されており、その断面形状は、磁路に垂直な断面がＤの字形を呈している。コア２は、板厚０．２〜０．５ｍｍの珪素鋼板又は方向性珪素鋼板をプレス積層してなる。
分割コア２０１，２０２を一体に繋ぐことで環状の閉磁路が形成され、その繋ぎ目には、永久磁石８が介在する。永久磁石８は、１次コイル４Ａ，４Ｂにより励磁される磁気方向と逆方向に着磁されており、１次コイルを通電した時の磁気飽和を防止する役割をなす。
１次コイル４（４Ａ、４Ｂ）及び２次コイル５を巻くためのボビン３は、例えばＰＰＳや変成ポリフェニレンオキサイド（以下「変成ＰＰＯ」という）等の熱可塑性樹脂で成形されており、その軸方向に垂直な断面形状はコア２の断面形状と合わせて略Ｄの字形を呈している（第３図及び第６図参照）。
ボビン３には、中央部に２次コイル５が巻線されており、その２次コイル５は線径０．０３〜０．０６ｍｍ程度のエナメル線を用いて、合計１００００〜３００００回程度分割巻されている。この分割巻きは、２次コイル５の巻き線領域を複数のつば部３３により分けることにより行われる。
１次コイル４は、符号４Ａ、４Ｂに示すように、ボビン３の両端外周、すなわち２次コイル５の低電圧側と高電圧側に隣接して分割して巻かれている。
この１次コイル４の分割巻きは、２次コイル５を巻いた後に行われる。第３図にその巻線態様を模試的に示している。
第３図において、（ａ）はボビン３の正面図、（ｂ）はそのＤ方向矢視図、（ｃ）はＢ−Ｂ断面図、（ｄ）はＣ−Ｃ断面図、（ｅ）はＥ方向矢視図である。
第３図（ｂ）において、ボビン３に記されている矢印は１次コイル４の巻線経路である。
ここで、１次コイル４が分割巻きされるボビン両端外周のうち、２次コイル５の低電圧側に隣接する一端外周を低電圧側外周３Ａ、２次コイル５の高電圧側に隣接する一端外周を高電圧側外周３Ｂとする。
また、ボビン３の低電圧側の最端に形成されるつば部３１には、その端面に突起３７及び３８がコア（磁路）を挟んで対向配置されている。
突起３７には、１次コイル４の電源供給側の一端４′および２次コイル５の低電圧側の一端５′を電源端子９Ａに接続するための金具（中継端子；ピン）１２と、１次コイル４の巻き終わりの一端４″をイグナイタ６の端子１０Ａに接続するための金具（中継端子；ピン）１１がインサート成形されている。
まず、１次コイル４に先だって２次コイル５がボビン３の中央部に分割巻きされる。２次コイル５は、第３図（ａ），（ｂ）に示すように、その巻き始め側（低電圧側）の引き出し線５′が金具（中継端子）１２に絡げ（巻き付け）られる。その後、ボビン３の一端外周３Ａに設けた軸方向に延びる溝４１の中を通り、２次コイル５の巻線領域に案内され、巻線される。
溝４１は、１次コイル４との接触を配慮して、第７図に示すように、例えばボビン表面の一部に微小な２条のなだらかな凸部３００，３０１を形成することでその凸部間に確保される。また、溝４１の深さは、２次コイルの線径より大きくしてある。ボビン３のつば部のうち、溝４１の両端に配置されているつば部３１、３２には、Ｖ字形の切り込み３１３、３２３が形成されている〔第３図（ｂ）（ｃ）〕。この切り込み３１３，３２３の底部が溝４１に連通する。２次コイルの引き出し線５′は、この切り込み３１３、３２３を介してつば部３１及びつば部３２を通すようにしてある。
２次コイル５の高電圧側の引き出し線５″は、ボビン３の高電圧側のつば部３５に設けた案内溝３５３に案内されてボビン３の高電圧側一端に設けたつば部３６の案内溝３６１に掛け渡された後に高電圧ダイオード２０に接続される〔第３図（ｂ）（ｅ）〕。
高電圧ダイオード２０は、つば部３６の外側面につば部と一体に成形した支持部３９により保持されている。
１次コイル４は、第３図（ｂ）に示すように、一端４′が金具（中継端子）１２に絡げ（巻き付け）られた後、つば部３１に設けた切り欠き３１４からボビン３の低電圧側外周３Ａ〔第３図（ａ）〕に導かれて低電圧側外周３Ａに巻かれる。このようにして、１次コイルの一方の巻線部４Ａが形成される。その後、巻線部４Ａにおける１次コイル巻き終わりの引き出し線４Ａ′は、低電圧側のつば部３２に設けた案内溝３２１と高電圧側のつば部３５に設けた案内溝３５１に掛け渡される〔第３図（ａ）、（ｃ）、（ｄ）〕。したがって、１次コイル４の引き出し線４Ａ′は、２次コイル５の外側に沿って２次コイルと接触することなく高電圧側外周３Ｂに導かれる。そして１次コイル４の残りが符号４Ｂに示すように高電圧側外周３Ｂに巻かれる。
高電圧側外周３Ｂに巻かれた１次コイル巻き終わりの引き出し線４Ｂ′は、高電圧側つば部３５に設けた案内溝３５２から低電圧側つば部３２に設けた案内溝３２２さらには低電圧側一端のつば部３１の案内溝３１１に掛け渡され、つば部３１に設けた金具（中継端子）１１に絡げられている。したがって、１次コイルの引き出し線４Ｂ′も２次コイル５の外側に沿って（非接触状態）、中継端子１１と電気的に接続されることになる。
中継端子１１は、ボビンの低電圧側のつば部３２に設けた突起３８にインサート成形されており、その一端に上記引き出し線４Ｂ′が絡げられ、もう一端１１′が第４図に示すようにイグナイタ６の端子１０Ａ（第８図のＩＧＢＴ１００のコレクタ側）に接続されている。
上記の巻線態様を採用することにより、２次コイル５の低電圧側の引き出し線５′は、ボビン３の一端外周に設けた溝４１を介してボビン３と１次コイル４（４Ａ）の間を通され、かつボビン一端に設けた端子１２に接続することができる。溝４１は、２次コイル５の線径よりも深くしている。したがって、２次コイル５の引き出し線５′は、１次コイルの巻線領域３Ａを１次コイル４に接触することなく引き出し可能になる。
また、１次コイル４を巻線する時に２次コイル５の引き出し線５′が干渉することがなくなり、２次コイル５の断線を防ぐことができる。さらに、１次コイル４の分割巻線の引き出し線４Ａ′、４Ｂ′を２次コイル５上に掛け渡すことにより、２次コイルの低電圧側と高電圧側に１次コイル４を分割巻きすることが可能になる。
断面Ｄの字形のコアにおける磁路Ａにボビン３が嵌合する。磁路Ａと平行なもう一方の磁路Ｂは、１次コイル４（４Ａ，４Ｂ）及び２次コイル５の外側に沿って配置される。ボビン３に配設される各つば部３１、３２、３３、３５、３６は、その外縁一部３１′、３２′、３３′、３５′、３６′が直線状にカットされ、この外縁一部に磁路Ｂにおける平坦面（磁路Ｂにおける断面Ｄの字のうち直線辺に相当する側面）があてがわれ或いは近接するように配置される。
したがって、コア２、１次コイル４、２次コイル５を、コンパクトに組立てることが可能になり、閉磁路全体が１次コイル、２次コイルと共に円筒のケース１に収納可能になる。
１次コイルの引き出し線を掛け渡す案内溝３１１、３２１、３２２、３５１、３５２や２次コイルの高圧側引き出し線を掛け渡す案内溝３５３、３６１は、つば部３１、３２、３５、３６のカット部３１′、３２′、３５′、３６′の傍らに設けた突起３１５、３２５、３５５、３６２に設けられている。
これらの案内溝に１次コイル、２次コイルの引き出し線４Ａ′、４Ｂ′、５″を通すことにより、次のような利点がある。１次コイルの引き出し線４Ａ′、４Ｂ′は、２次コイル５の巻線部外径やケース１の内径に接触することを防止できる。また、２次コイル５については１次コイル４Ｂの外径やケース１の内径に接触することを防止することができる。ボビン１は、断面形状が、楕円状であってもよい。
ボビン３は、コア２と２次コイル５の間に配置され、２次コイル５で発生した高電圧を絶縁する役目もある。
ボビン３に設けた２次コイル用の複数のつば部３３には、２次コイル５を分割巻きするための切り欠き３２７が設けられている。
本実施例のイグナイタケース１Ｂ及びコネクタ部１Ｃは、コイルケース１と一体に成形されているが、別体に成形されてもよい。
コネクタ部１Ｃには、電源供給端子９Ａ、ＧＮＤ端子９Ｂ、点火信号入力端子９Ｃがインサート成形により固定されている。端子９Ａは、基板７の下中継端子１２と接続され（第３図（ｂ）参照）、端子９Ｂはイグナイタ６のグランド端子１０Ｂと接続され、端子９Ｃはイグナイタ６の信号入力端子１０Ｃに接続されている。
イグナイタ６は、第９図に示すようにＩＧＢＴ１０５をヒートシンク１１０上に接合し、このヒートシンク１１０を放熱用の銅又はアルミニウムの金属板１１２にシリコン接着剤１１１を介して接着してなる。
イグナイタケース１Ｂには、点火コイルを取り付けるための突起２１０、２１１及び取り付け穴２１３、２１４が設けられている。
ボビン３内周とコア２の外周間には、可とう性エポキシを真空下（例えば４Ｔｏｒｒ以下）で注入，硬化するか、或いは第２図に示すようにコア２の周りにシリコンゴム２３０を被せるか、コア２の周りにシリコンゴムを成形するか、コア２の周りに熱収縮チューブを被せる。それによって、２次コイル５とコア２の間の電界集中及び応力集中を防止している。
このような点火コイルの組立体（コア２、１次コイル４、２次コイル５）及びイグナイタ６を挿入した後に、エポキシ樹脂６０をコイルケース１及びイグナイタケース１Ｂ内に真空下（例えば４Ｔｏｒｒ以下）で注入される。
点火プラグが挿入される部分１Ｄには、２次電流を供給する機能を兼ねるスプリング１７が内装されている。コイルケース１には、プラグホール内に挿入したときにプラグホールに水が侵入せず、且つ換気ができるようなプラグホールシール６１を取付けている。
本実施例によれば、次のような効果を奏する。
一つのボビンに１次コイル４及び２次コイル５を巻き、かつボビン中央部に２次コイル５を、その低電圧側と高電圧側の両端に１次コイルを分割巻きすることで、１次コイルと２次コイルの結合係数を上げることができ、限られたスペースの中で高出力の内燃機関用点火コイルを実現することができる。また、１次コイルを２次コイルと干渉させることなく２次コイルの低電圧側、高電圧側に分割巻きすることができ、コイルの巻き線作業が行い易く、また、コイル切断を防止して品質保証を高めることができる。
第１０図に本発明の他の実施例を示す。第１０図において、既述した第１実施例と同一の符号は同一或いは共通する要素を示す。
本実施例において、１次コイル４の分割巻き、２次コイル５の分割巻きの態様及び１次コイル，２次コイルの全体的なレイアウトは、既述した実施例と同様である。
ここでは、相違点について説明する。
既述したように、一つのボビン３における２次コイル５の低電圧側と高電圧側とに１次コイル４Ａ、４Ｂを配置することは、コイルの結合係数を高め、コイル組立体のコンパクト化及び収納性を高めることができる。
したがって、筒状のコイルケース１の内部に、１次コイル４，２次コイル５と共に閉磁路型のコア２全体とイグナイタ６を収納するスペースを確保することが可能になる。本実施例では、このコイルケース１の空きスペースを有効利用してイグナイタ６を収納する。
ここで、コイルケース１の軸方向におけるコイル挿入側の一端を上側、点火プラグと接続する側を下側とした場合に、コイルケース１の上部に外部端子と接続するためのコネクタ部１Ｃが形成されている。また、イグナイタ６の設置部がコネクタ部１Ｃの位置より低い位置に設定されている。
また、本実施例では、第１実施例よりも点火コイル装着部１Ｄ及びスプリング１７の短縮化を図っている。本実施例によれば、点火コイルのより一層のコンパクト化を図ることができる。また、スプリング１７を短縮することで、点火ノイズの発生を抑える効果がある。
産業上の利用可能性
本発明によれば、ボビン中央部に２次コイルを、その低電圧側と高電圧側の両端に１次コイルを分割して巻くことにより、１次コイルと２次コイルの結合係数を上げることができ、限られたスペースの中で高出力の内燃機関用点火コイルを提供することができる。
【図面の簡単な説明】
第１図は、本発明の第１実施例に係る内燃機関用点火コイルの縦断面図、第２図は、上記実施例の見方を変えた縦断面図（Ａ−Ａ線断面図）、第３図は、上記実施例に係る点火コイルの１次コイル及び２次コイルの巻き線のレイアウト及びその引き出し構造を模式的に示す説明図、第４図は、上記実施例に係る点火コイルの上面図、第５図は、上記実施例のコイルケースを内部実装部品を取り外して示す縦断面図、第６図は、上記実施例に用いるコアの分解状態を示す正面図及び分解された各コアの端面側からみた図、第７図は、上記実施例に用いるボビンの部分拡大断面図、第８図は、上記実施例に用いるイグナイタの回路図、第９図は、上記イグナイタの構成を示す断面図、第１０図は、本発明の第２実施例に係る内燃機関用点火コイルの縦断面図。TECHNICAL FIELD The present invention relates to an ignition coil (ignition device) for an internal combustion engine, and more particularly, a cylindrical ignition coil suitable for being housed in a plug hole of a cylinder head of an internal combustion engine and directly connected to the ignition plug. About.
Background Art As an ignition coil for an internal combustion engine, a so-called independent ignition type ignition coil that is prepared for each cylinder of an internal combustion engine and is directly connected to an ignition plug is known.
This type of ignition coil includes a type in which a primary coil and a secondary coil are arranged concentrically around a core that forms a magnetic path, and a primary coil wound on a single bobbin so as to be aligned in the axial direction. A type in which a wire portion and a winding portion of a secondary coil are arranged is known.
As the latter type, for example, there is one disclosed in JP-A-2-230964.
The independent ignition type ignition coil is housed in the plug hole of the cylinder head of the internal combustion engine, so the space of the coil part is very narrow, and how high the ignition energy can be obtained in this limited space. The problem was whether to supply the spark plug.
SUMMARY OF THE INVENTION An object of the present invention is an internal combustion type ignition coil in which a primary coil and a secondary coil are wound on a single bobbin so as to be aligned in the axial direction, and the output can be reduced to improve the output. An object of the present invention is to provide an ignition coil device for an engine.
DISCLOSURE OF THE INVENTION In order to achieve the above object, the present invention is basically configured as follows.
(1) An independent ignition type ignition coil for an internal combustion engine in which a primary coil and a secondary coil are arranged on one bobbin so as to be aligned in the axial direction is configured as follows.
That is, the secondary coil is wound around a central portion of the bobbin, and the primary coil is divided and wound on a low voltage side and a high voltage side of the secondary coil.
In this type of conventional ignition coil, a primary coil is disposed in one region in the axial direction of one bobbin, and a secondary coil is disposed in the other region.
On the other hand, in the present invention, the primary coil is dividedly wound on the low voltage side and the high voltage side of the secondary coil in the axial direction of the bobbin. Thus, by dividing and winding the primary coil, the coupling coefficient between the primary coil and the secondary coil can be increased as compared with the prior art. Therefore, a high output ignition coil for an internal combustion engine can be manufactured in a limited space.
(2) Along with the above basic configuration, the following coil wiring structure is also proposed.
The lead-out wire on the low voltage side of the secondary coil is passed between the bobbin and the primary coil through a groove provided on the outer periphery of the bobbin, and thus the secondary coil is provided at one end of the bobbin. I was connected to the terminal.
Further, if one end outer periphery adjacent to the low voltage side of the secondary coil of the bobbin is defined as a low voltage side outer periphery and one end outer periphery adjacent to the high voltage side of the secondary coil is defined as a high voltage side outer periphery, The coil is wound from the outer periphery of the bobbin on the low voltage side. Then, a lead wire at the end of the primary coil winding on the outer periphery of the low voltage side is stretched along the outer side of the secondary coil to a collar portion provided on the low voltage side and the high voltage side, and the rest of the coil is the high voltage side. It is wound around the outer periphery of the voltage side, and the lead wire at the end of winding of the primary coil on the outer periphery of the high voltage side again spans the high voltage side and low voltage side collars of the bobbin along the outside of the secondary coil. To be electrically connected to the terminal.
In this way, even when the primary coil is divided and wound on both the low voltage side and the high voltage side of the secondary coil, the coil can be routed without interference between the coils. it can.
(3) Further, the following independent ignition type ignition coil for an internal combustion engine is proposed.
The primary coil and the secondary coil are arranged on one bobbin side by side in the axial direction. The core is a steel plate having a D-shaped cross section perpendicular to the magnetic path, and has a closed magnetic circuit structure. The bobbin also has a cross section perpendicular to the axial direction that matches the cross-sectional shape of the core. In the core, the bobbin is fitted to one of the magnetic paths in the longitudinal direction arranged in parallel among the closed magnetic paths (hereinafter referred to as “magnetic path A”), and the other magnet is parallel to the magnetic path A. A path (hereinafter referred to as “magnetic path B”) is disposed along the outside of the primary coil and the secondary coil. Each of the flange portions arranged on the bobbin has a part of the outer edge thereof formed in a straight line, and a part of the outer edge of the collar part corresponding to the straight side of the cross section D of the magnetic path B is assigned or close to the side part. Thus, the magnetic path B is arranged.
In this way, the entire closed magnetic circuit type core capable of improving the output is compactly collected as one coil assembly together with the primary coil and the secondary coil, and stored in a cylindrical case.
(4) The following invention is further proposed.
A core that forms a closed magnetic path; a primary coil and a secondary coil that are disposed on a part of the outer periphery of the core via a bobbin; and an ignition drive circuit unit that drives the primary coil and the secondary coil. In the ignition coil for an internal combustion engine provided, the entire closed magnetic circuit type core and the ignition drive circuit unit are housed in a cylindrical case that houses the primary coil and the secondary coil. Further, the bobbin is characterized in that the secondary coil is wound around a central portion, and the primary coil is separately wound around both ends of the bobbin so as to sandwich the secondary coil.
Arranging the primary coils on both sides of the secondary coil in the axial direction can increase the coupling coefficient of the coils, and can make the coil assembly more compact and easier to store. Therefore, the drive circuit unit of the ignition coil can be stored in the coil case. In addition, the entire core of the closed magnetic circuit is housed in the cylindrical case together with the drive circuit, so that the mounting density of the components in the coil case can be increased.
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.
First, prior to describing the structure of the ignition coil according to the present embodiment with reference to FIGS. 1 to 7, the electric circuit of the ignition coil according to the present embodiment will be described with reference to FIG.
In the figure, 2 is a core for forming the magnetic path of the ignition coil, 4 is a primary coil, and 5 is a secondary coil.
One end 4 ′ of the primary coil 4 and one end 5 ′ on the low voltage side of the secondary coil 5 are connected to a power supply terminal 9 </ b> A that communicates with the battery power source. The other end 4 ″ of the primary coil 4 is connected to a terminal 10A of the switching circuit 105 of the ignition drive circuit unit (hereinafter referred to as “igniter”) 6.
One end 5 ′ on the high voltage side of the secondary coil 5 is electrically connected to the spark plug 10 via a high voltage diode 20 and a high voltage terminal 16.
The igniter 6 includes a main insulated gate bipolar transistor (hereinafter referred to as “IGBT”) 100 and a sub-IGBT 101 serving as a switching element of the primary coil, a current limiting circuit 109 for limiting a current flowing through the primary coil 4, It comprises a current detection resistor 102, an ignition signal input resistor 107, a bleeder resistor 108 and the like.
The current detection resistor 102 is provided between the emitter of the sub IGBT 101 and GND. Between the gate and the collector of the IGBT 105, a phase-direction polysilicon Zener diode 103 made of polysilicon having excellent temperature characteristics is inserted, and the primary voltage is clamped at 400 to 550V.
A bleeder resistor 108 is inserted between the signal input terminal 9c of the igniter 6 and the ground (GND), the contact current of the input signal connection portion is set to 1 mA or more, and even if the plating of the terminal 9C is Sn plating, sufficient connection reliability is obtained. I am trying to do it.
In the above circuit configuration, the IGBT (switching element) 100 cuts off the primary current flowing through the primary coil 4 based on the ignition signal, thereby inducing a high voltage for ignition in the secondary coil 5.
The high voltage diode 20 serves to prevent premature ignition when the high voltage generated in the secondary coil 5 is supplied to the spark plug 10 via the high voltage terminal 16 and the spring 17 (see FIG. 1). Eggplant.
The power supply terminal 9A (VB), the GND terminal 9B, and the ignition signal input terminal 9C (S) are arranged in the connector portion 1C (see FIGS. 1 and 4) of the ignition coil device.
Here, the structure of the ignition coil will be described with reference to FIGS.
An ignition coil case (hereinafter referred to as “coil case”) 1 is elongated with a thermoplastic synthetic resin such as polybutylene terephthalate (hereinafter referred to as “PBT”) or polyphenylene sulfide (hereinafter referred to as “PPS”) PPS. It is made by molding into a cylindrical shape.
The coil case 1 is formed by integrally forming a coil housing portion 1A, a spark plug connection portion 1D, an igniter case 1B for housing the igniter 6, and a connector portion 1C for connecting external terminals.
A closed magnetic path core 2, a primary coil 4, and a secondary coil 5 are housed in the coil housing portion 1A.
The igniter case 1B has a box shape, for example, and an igniter 6 for driving the ignition coil is housed therein.
The core 2 of the ignition coil forms a substantially rectangular annular closed magnetic path, and the magnetic paths A and B in the longitudinal direction are arranged in parallel in the axial direction of the coil case 1. Further, the core 2 is divided into 201 and 202 as shown in FIG. 6, and the cross-sectional shape thereof is a D-shaped cross section perpendicular to the magnetic path. The core 2 is formed by press lamination of a silicon steel plate or a directional silicon steel plate having a thickness of 0.2 to 0.5 mm.
An annular closed magnetic path is formed by connecting the split cores 201 and 202 together, and a permanent magnet 8 is interposed at the joint. The permanent magnet 8 is magnetized in a direction opposite to the magnetic direction excited by the primary coils 4A and 4B, and serves to prevent magnetic saturation when the primary coil is energized.
The bobbin 3 for winding the primary coil 4 (4A, 4B) and the secondary coil 5 is formed of a thermoplastic resin such as PPS or modified polyphenylene oxide (hereinafter referred to as “modified PPO”), and its axial direction. The cross-sectional shape perpendicular to the cross-sectional shape of the core 2 is substantially D-shaped together with the cross-sectional shape of the core 2 (see FIGS. 3 and 6).
A secondary coil 5 is wound around the center of the bobbin 3, and the secondary coil 5 is divided into a total of about 10,000 to 30000 turns using an enameled wire having a wire diameter of about 0.03 to 0.06 mm. Has been. This divided winding is performed by dividing the winding region of the secondary coil 5 by a plurality of collar portions 33.
As shown by reference numerals 4A and 4B, the primary coil 4 is divided and wound adjacent to the outer periphery of both ends of the bobbin 3, that is, the low voltage side and the high voltage side of the secondary coil 5.
The split winding of the primary coil 4 is performed after the secondary coil 5 is wound. FIG. 3 schematically shows the winding mode.
3, (a) is a front view of the bobbin 3, (b) is a view taken in the direction of the arrow D, (c) is a cross-sectional view along BB, (d) is a cross-sectional view along CC, and (e) is a cross-sectional view. It is an E direction arrow directional view.
In FIG. 3 (b), the arrow marked on the bobbin 3 is the winding path of the primary coil 4.
Here, among the outer circumferences of both ends of the bobbin on which the primary coil 4 is divided and wound, the outer circumference of one end adjacent to the low voltage side of the secondary coil 5 is the one end adjacent to the low voltage side outer circumference 3A The outer periphery is the high voltage side outer periphery 3B.
Further, on the flange portion 31 formed at the extreme end of the bobbin 3 on the low voltage side, protrusions 37 and 38 are disposed opposite to each other with the core (magnetic path) interposed therebetween.
The protrusion 37 includes a metal fitting (relay terminal; pin) 12 for connecting one end 4 ′ on the power supply side of the primary coil 4 and one end 5 ′ on the low voltage side of the secondary coil 5 to the power supply terminal 9 </ b> A, A metal fitting (relay terminal; pin) 11 for connecting one end 4 ″ of the winding end of the next coil 4 to the terminal 10A of the igniter 6 is insert-molded.
First, prior to the primary coil 4, the secondary coil 5 is divided and wound around the central portion of the bobbin 3. As shown in FIGS. 3 (a) and 3 (b), the secondary coil 5 has a lead wire 5 ′ on the winding start side (low voltage side) tangled (wound) around a metal fitting (relay terminal) 12. After that, the bobbin 3 is guided to the winding region of the secondary coil 5 through the axially extending groove 41 provided on the outer periphery 3 </ b> A of the bobbin 3 and wound.
Considering the contact with the primary coil 4, the groove 41 is formed, for example, as shown in FIG. 7 by forming minute, gentle two-row convex portions 300, 301 on a part of the bobbin surface. Secured between clubs. Further, the depth of the groove 41 is larger than the wire diameter of the secondary coil. V-shaped cuts 313 and 323 are formed in the collar portions 31 and 32 arranged at both ends of the groove 41 in the collar portion of the bobbin 3 (FIGS. 3B and 3C). The bottoms of the cuts 313 and 323 communicate with the groove 41. The secondary coil lead wire 5 ′ passes through the collar portion 31 and the collar portion 32 through the notches 313 and 323.
The lead wire 5 ″ on the high voltage side of the secondary coil 5 is guided by a guide groove 353 provided in the high voltage side collar portion 35 of the bobbin 3 to guide the collar portion 36 provided at one end on the high voltage side of the bobbin 3. After being passed over the groove 361, it is connected to the high voltage diode 20 (FIGS. 3B and 3E).
The high voltage diode 20 is held by a support portion 39 formed integrally with the collar portion on the outer surface of the collar portion 36.
As shown in FIG. 3 (b), the primary coil 4 has one end 4 ′ entangled (wrapped) around the metal fitting (relay terminal) 12, and then the notch 314 provided in the collar portion 31 to the bobbin 3. It is guided to the low voltage side outer periphery 3A [FIG. 3 (a)] and wound around the low voltage side outer periphery 3A. In this way, one winding portion 4A of the primary coil is formed. Thereafter, the lead wire 4A ′ at the end of winding of the primary coil in the winding portion 4A is stretched over the guide groove 321 provided in the low voltage side flange portion 32 and the guide groove 351 provided in the high voltage side flange portion 35. [FIGS. 3 (a), (c), (d)]. Accordingly, the lead wire 4A ′ of the primary coil 4 is led along the outer side of the secondary coil 5 to the outer periphery 3B on the high voltage side without coming into contact with the secondary coil. The remainder of the primary coil 4 is wound around the high voltage side outer periphery 3B as indicated by reference numeral 4B.
The lead wire 4B ′ at the end of winding of the primary coil wound around the high voltage side outer periphery 3B extends from the guide groove 352 provided in the high voltage side collar portion 35 to the guide groove 322 provided in the low voltage side collar portion 32 and further to the low voltage. It is stretched over the guide groove 311 of the flange 31 at one end of the side and is entangled with the metal fitting (relay terminal) 11 provided on the flange 31. Therefore, the lead wire 4B ′ of the primary coil is also electrically connected to the relay terminal 11 along the outside of the secondary coil 5 (non-contact state).
The relay terminal 11 is insert-molded into a projection 38 provided on the flange portion 32 on the low voltage side of the bobbin. The lead wire 4B 'is entangled at one end, and the other end 11' is as shown in FIG. Is connected to the terminal 10A of the igniter 6 (the collector side of the IGBT 100 in FIG. 8).
By adopting the winding mode described above, the lead-out line 5 'on the low voltage side of the secondary coil 5 is connected to the bobbin 3 and the primary coil 4 (4A) via a groove 41 provided on the outer periphery of one end of the bobbin 3. It can be connected to a terminal 12 that is passed through and provided at one end of the bobbin. The groove 41 is deeper than the wire diameter of the secondary coil 5. Therefore, the lead wire 5 ′ of the secondary coil 5 can be drawn without contacting the winding region 3 </ b> A of the primary coil with the primary coil 4.
Further, when the primary coil 4 is wound, the lead wire 5 ′ of the secondary coil 5 does not interfere, and the disconnection of the secondary coil 5 can be prevented. Further, the primary coil 4 is dividedly wound on the low voltage side and the high voltage side of the secondary coil by passing the lead wires 4A ′ and 4B ′ of the divided winding of the primary coil 4 on the secondary coil 5. It becomes possible.
The bobbin 3 is fitted into the magnetic path A in the core having a D-shaped cross section. The other magnetic path B parallel to the magnetic path A is disposed along the outside of the primary coil 4 (4A, 4B) and the secondary coil 5. Each of the flange portions 31, 32, 33, 35, and 36 disposed on the bobbin 3 has its outer edge portions 31 ′, 32 ′, 33 ′, 35 ′, and 36 ′ cut in a straight line. Are arranged such that a flat surface in the magnetic path B (a side surface corresponding to a straight side of the cross-section D in the magnetic path B) is applied to or close to the magnetic path B.
Accordingly, the core 2, the primary coil 4, and the secondary coil 5 can be assembled in a compact manner, and the entire closed magnetic circuit can be accommodated in the cylindrical case 1 together with the primary coil and the secondary coil.
The guide grooves 311, 321, 322, 351, 352 for passing the lead wire of the primary coil and the guide grooves 353, 361 for passing the high-voltage side lead wire of the secondary coil are cut off of the collar portions 31, 32, 35, 36. Protrusions 315, 325, 355, and 362 provided beside the portions 31 ′, 32 ′, 35 ′, and 36 ′.
By passing the primary coil and secondary coil lead wires 4A ', 4B', 5 "through these guide grooves, the following advantages are obtained. The primary coil lead wires 4A ', 4B' are 2 Contact with the outer diameter of the winding portion of the secondary coil 5 and the inner diameter of the case 1 can be prevented, and the secondary coil 5 can be prevented from contacting the outer diameter of the primary coil 4B and the inner diameter of the case 1. The bobbin 1 may have an elliptical cross-sectional shape.
The bobbin 3 is disposed between the core 2 and the secondary coil 5 and also serves to insulate high voltage generated in the secondary coil 5.
The plurality of flange portions 33 for the secondary coil provided on the bobbin 3 are provided with notches 327 for separately winding the secondary coil 5.
The igniter case 1B and the connector portion 1C of the present embodiment are formed integrally with the coil case 1, but may be formed separately.
A power supply terminal 9A, a GND terminal 9B, and an ignition signal input terminal 9C are fixed to the connector portion 1C by insert molding. The terminal 9A is connected to the lower relay terminal 12 of the substrate 7 (see FIG. 3B), the terminal 9B is connected to the ground terminal 10B of the igniter 6, and the terminal 9C is connected to the signal input terminal 10C of the igniter 6. ing.
As shown in FIG. 9, the igniter 6 is formed by bonding an IGBT 105 on a heat sink 110 and bonding the heat sink 110 to a heat-dissipating copper or aluminum metal plate 112 via a silicon adhesive 111.
The igniter case 1B is provided with protrusions 210 and 211 and attachment holes 213 and 214 for attaching the ignition coil.
Between the inner periphery of the bobbin 3 and the outer periphery of the core 2, a flexible epoxy is injected and cured under vacuum (for example, 4 Torr or less), or the core 2 is covered with a silicone rubber 230 as shown in FIG. Alternatively, silicon rubber is molded around the core 2 or a heat-shrinkable tube is put around the core 2. Thereby, electric field concentration and stress concentration between the secondary coil 5 and the core 2 are prevented.
After the ignition coil assembly (core 2, primary coil 4, secondary coil 5) and igniter 6 are inserted, the epoxy resin 60 is placed in the coil case 1 and igniter case 1B under vacuum (for example, 4 Torr or less). Injected with.
A spring 17 having a function of supplying a secondary current is incorporated in the portion 1D into which the spark plug is inserted. The coil case 1 is provided with a plug hole seal 61 that prevents water from entering the plug hole and allows ventilation when inserted into the plug hole.
According to the present embodiment, the following effects can be obtained.
The primary coil 4 and the secondary coil 5 are wound around one bobbin, the secondary coil 5 is wound around the center of the bobbin, and the primary coil is separately wound around both the low voltage side and the high voltage side. The coupling coefficient between the coil and the secondary coil can be increased, and a high output ignition coil for an internal combustion engine can be realized in a limited space. In addition, the primary coil can be divided and wound on the low voltage side and the high voltage side of the secondary coil without interfering with the secondary coil, making it easy to perform coil winding work and preventing coil cutting. Quality assurance can be enhanced.
FIG. 10 shows another embodiment of the present invention. In FIG. 10, the same reference numerals as those of the first embodiment described above denote the same or common elements.
In this embodiment, the split winding of the primary coil 4, the split winding of the secondary coil 5, and the overall layout of the primary and secondary coils are the same as those of the above-described embodiments.
Here, the differences will be described.
As described above, the arrangement of the primary coils 4A and 4B on the low voltage side and the high voltage side of the secondary coil 5 in one bobbin 3 increases the coupling coefficient of the coils and makes the coil assembly compact. And storage property can be improved.
Therefore, it is possible to secure a space for accommodating the entire closed magnetic circuit type core 2 and the igniter 6 together with the primary coil 4 and the secondary coil 5 in the cylindrical coil case 1. In this embodiment, the igniter 6 is accommodated by effectively using the empty space of the coil case 1.
Here, when one end on the coil insertion side in the axial direction of the coil case 1 is set to the upper side and the side connected to the spark plug is set to the lower side, a connector portion 1C for connecting to an external terminal is formed on the upper portion of the coil case 1. Has been. Moreover, the installation part of the igniter 6 is set to a position lower than the position of the connector part 1C.
Further, in this embodiment, the ignition coil mounting portion 1D and the spring 17 are shortened compared to the first embodiment. According to this embodiment, the ignition coil can be made more compact. Further, shortening the spring 17 has an effect of suppressing the generation of ignition noise.
INDUSTRIAL APPLICABILITY According to the present invention, a primary coil and a secondary coil are formed by dividing and winding a secondary coil at the center of the bobbin and dividing the primary coil around both ends of the low voltage side and the high voltage side. Thus, it is possible to provide an ignition coil for an internal combustion engine with high output in a limited space.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an ignition coil for an internal combustion engine according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view (A-A sectional view) showing a different view of the above embodiment. FIG. 3 is an explanatory view schematically showing the layout of the primary coil and secondary coil windings of the ignition coil according to the above embodiment and the drawing structure thereof, and FIG. 4 is a top view of the ignition coil according to the above embodiment. FIG. 5 is a longitudinal sectional view showing the coil case of the above embodiment with the internal mounting parts removed, and FIG. 6 is a front view showing the disassembled state of the core used in the above embodiment and the disassembled cores. FIG. 7 is a partial enlarged cross-sectional view of the bobbin used in the above embodiment, FIG. 8 is a circuit diagram of the igniter used in the above embodiment, and FIG. 9 is a cross section showing the configuration of the above igniter. 10 and 10 show an ignition coil for an internal combustion engine according to the second embodiment of the present invention. Longitudinal sectional view.

Claims

An ignition coil mounted in each plug hole of a cylinder head of an internal combustion engine, comprising: a core that forms a magnetic path; and a primary coil and a secondary coil that are disposed on the outer periphery of the core via bobbins, In the ignition coil for an internal combustion engine, the primary coil and the secondary coil are arranged on one bobbin in the axial direction.
Ignition for internal combustion engine, wherein the secondary coil is wound around a central portion of the bobbin, and the primary coil is divided into a low voltage side and a high voltage side of the secondary coil. coil.

An ignition coil mounted in each plug hole of a cylinder head of an internal combustion engine, comprising: a core that forms a magnetic path; and a primary coil and a secondary coil that are disposed on the outer periphery of the core via bobbins, In the ignition coil for an internal combustion engine, the primary coil and the secondary coil are arranged on one bobbin in the axial direction.
The secondary coil is wound around a central portion of the bobbin, and the primary coil is divided and wound on a low voltage side and a high voltage side of the secondary coil,
A lead-out line on the low voltage side of the secondary coil is passed between the bobbin and the primary coil through a groove provided on one outer periphery of the bobbin, and is connected to a terminal provided on one end of the bobbin. An ignition coil for an internal combustion engine.

An ignition coil mounted in each plug hole of a cylinder head of an internal combustion engine, comprising: a core that forms a magnetic path; and a primary coil and a secondary coil that are disposed on the outer periphery of the core via bobbins, In the ignition coil for an internal combustion engine, the primary coil and the secondary coil are arranged on one bobbin in the axial direction.
The secondary coil is wound around a central portion of the bobbin, and the primary coil is divided and wound on a low voltage side and a high voltage side of the secondary coil,
If one end outer periphery adjacent to the low voltage side of the secondary coil of the bobbin is defined as a low voltage side outer periphery and one end outer periphery adjacent to the high voltage side of the secondary coil is defined as a high voltage side outer periphery, the primary coil is Winding from the outer periphery of the low voltage side of the bobbin, and the lead wire at the end of winding of the primary coil on the outer periphery of the low voltage is hung on the collar portion provided on the low voltage side and the high voltage side along the outside of the secondary coil The remaining primary coil is wound around the outer periphery of the high voltage side, and the lead wire at the end of the primary coil winding on the outer periphery of the high voltage side is again extended along the outer side of the secondary coil with the high voltage of the bobbin. An ignition coil for an internal combustion engine, wherein the ignition coil is stretched over a flange on the side and the low voltage side and electrically connected to a terminal.

The ignition coil for an internal combustion engine according to claim 3, wherein a guide groove for passing a lead wire of the primary coil is formed in a low voltage side and a high voltage collar portion of the bobbin.

A flange provided at one end of the bobbin includes a metal fitting for connecting one end of the primary coil on the power supply side and one end of the secondary coil on the low voltage side to a power terminal, and winding of the primary coil. The ignition coil for an internal combustion engine according to any one of claims 1 to 4, wherein a metal fitting for connecting one end of the end to a terminal of a switching element of the ignition drive circuit is insert-molded.

5. The internal combustion engine according to claim 1, wherein the core is a rectangular annular core that forms a closed magnetic path, and the entire annular core is housed in a cylindrical case together with a primary coil and a secondary coil. Ignition coil for engine.

An ignition coil mounted in each plug hole of a cylinder head of an internal combustion engine, comprising: a core that forms a magnetic path; and a primary coil and a secondary coil that are disposed on the outer periphery of the core via bobbins. In an ignition coil for an internal combustion engine,
The primary coil and the secondary coil are arranged side by side in the axial direction on one bobbin,
The core is a steel plate in which a cross section perpendicular to the magnetic path is laminated in a D shape, and has a closed magnetic circuit structure,
The bobbin also has a cross section perpendicular to the axial direction matched to the cross-sectional shape of the core,
In the core, the bobbin is fitted to one of the magnetic paths in the longitudinal direction arranged in parallel among the closed magnetic paths (hereinafter referred to as “magnetic path A”), and the other magnet is parallel to the magnetic path A. A path (hereinafter referred to as "magnetic path B") is disposed along the outside of the primary coil and secondary coil,
Each of the flange portions arranged on the bobbin has a part of the outer edge thereof formed in a straight line, and a part of the outer edge of the collar part corresponding to the straight side of the cross section D of the magnetic path B is assigned or close to the side part. The magnetic path B is arranged as follows,
An ignition coil for an internal combustion engine, wherein the entire closed magnetic path of the core is housed in a cylindrical case together with the primary coil and the secondary coil.

The ignition coil for an internal combustion engine according to claim 7, wherein the secondary coil is wound around a central portion of the bobbin, and the primary coil is separately wound around both ends of the secondary coil on a low voltage side and a high voltage side.

A core that forms a closed magnetic path; a primary coil and a secondary coil that are disposed on a part of the outer periphery of the core via a bobbin; and an ignition drive circuit unit that drives the primary coil and the secondary coil. In the internal combustion engine ignition coil provided,
The entire closed magnetic circuit type core and the ignition drive circuit unit are housed in a cylindrical case that houses the primary coil and the secondary coil,
An ignition coil for an internal combustion engine, wherein the secondary coil is wound around a central portion of the bobbin, and the primary coil is separately wound around both ends of the bobbin so as to sandwich the secondary coil.

When one end on the coil insertion side in the axial direction of the cylindrical case is the upper side and the side connected to the spark plug is the lower side, a connector part for connecting to an external terminal is formed on the upper part of the cylindrical case, The ignition coil for an internal combustion engine according to claim 9, wherein an installation portion of the ignition drive circuit unit is set at a position lower than a position of the connector portion.

The ignition coil for an internal combustion engine according to any one of claims 7 to 10, wherein the closed magnetic path is formed by assembling at least two divided cores into one, and a permanent magnet is disposed at the joint.