JP2004324430A

JP2004324430A - Ignition device for internal combustion engine

Info

Publication number: JP2004324430A
Application number: JP2003116123A
Authority: JP
Inventors: Yoshitaka Sato; 美孝佐藤; Masahiko Aoyama; 雅彦青山
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2003-04-21
Filing date: 2003-04-21
Publication date: 2004-11-18

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition device for an internal combustion engine restraining water and steam from entering a plug hole. <P>SOLUTION: An ignition coil 3 has a coil flange part 4 for closing an opening part 21 of the plug hole 20, and an annular sealing plate 1 is interposed between a lower face 41 of the coil flange part 4 and a peripheral edge 210 of the opening part 21. A gas passage allowing gas exchange between the inside of the plug hole 20 and the outside of a cylinder head 2 is provided between the coil flange part 4 and the sealing plate 1. The gas passage is formed by providing an upper face 105 of the sealing plate 1 with a peripheral groove part formed along the circumferential direction, an outer passage leading to the outside of the cylinder head 2 from the outer peripheral side of the peripheral groove part, and an inner passage leading to the inside of the plug hole 20 from the inner peripheral side of the peripheral groove part, and bringing the sealing plate 1 and the coil flange part 4 into close contact. The depth of the peripheral groove part on the inner passage side is shallower than the depth of the peripheral groove part on the outer passage side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【技術分野】
本発明は，内燃機関の燃焼室において点火動作を行う点火プラグと該点火プラグに通電する点火コイルとを有する内燃機関用点火装置に関する。
【０００２】
【従来技術】
後述する図１，図２等に示すごとく，内燃機関のシリンダヘッドに設けたプラグホールは，底面に点火プラグが取り付けてあり，該点火プラグはプラグホールに挿入した点火コイルとプラグホール内において電気的に接続される。
プラグホールはシリンダヘッド外部に開口する開口部を有し，該開口部はコイル頭部の下方に設けたコイルフランジ部によって閉塞され，そしてゴミや水が入らないようにコイルフランジ部とプラグホール開口部周縁のシリンダヘッド外部表面との間に円盤状のシール板を設けて，プラグホールを閉鎖する。
【０００３】
しかしながら，プラグホール内のガスは，内燃機関の燃焼室における燃焼や点火コイル作動時の発熱等によって熱せられ膨張することがあり，プラグホールの完全密閉は問題がある。
更に，点火コイルと点火プラグとの間の通電等は高圧電流により行うことが多いため，オゾンが発生することもあり，プラグホール内の換気が必要となることもある。
従って，プラグホール内部とシリンダヘッド外部との間でガス交換ができるように，シール板とコイルフランジ部との間等にガス通路を設けるのが一般的である。
【０００４】
ガス通路の具体例として，従来知られている構成を図８，図９に記載する。
図８，図９に示すごとく，シール板９のコイルフランジ部側と対面する上面１０５に周溝部９０を設けて，コイルフランジ部とシール板９とを密接させる。これにより周溝部９０をガス通路として利用できる。
すなわち，図８，図９に示すごとく，上記周溝部９０は，環状のシール板９の上面１０５に設けた，複数の水溜部９１と各水溜部９１を連結する連結溝９２とからなる。
水溜部９１の深さは連結溝９２より深く，ある連結溝９２の内周側にプラグホール内部に通じる内部通路１２２を，また内部通路１２２を設けてない別の連結溝９２の外周側にシリンダヘッド外部に通じる外部通路１２１を設ける。
この構成にかかるシール板９をコイルフランジ部と密接することでガス通路となす。
【０００５】
プラグホール内部のガスは内部通路１２２，内部通路１２２を設けた連結溝９２，該連結溝９２と隣接する水溜部９１・・・を隔てて，外部通路１２１を設けた連結溝９２に入り，外部通路１２１を通過してシリンダヘッド外部に抜けることができる。
シリンダヘッド外部からの被水で，ガス通路に水が入った場合，水は連結溝９２より深い水溜溝９１に溜まって勢いが抑えられ，プラグホール内部に到達し難くなる。
【０００６】
【特許文献１】
特許第０３１４５８８０号公報
【０００７】
【解決しようとする課題】
しかしながら，上記従来構成の場合，浸入した水が水溜部９１に長時間留まって，水が揮発して水蒸気となってプラグホール内部に浸入することがあった。
この場合，点火プラグと点火コイルの接点が腐食して導通不良が発生したり，プラグホール内壁面と点火コイル間の高電圧リークが生じやすくなるおそれがあった。
【０００８】
本発明は，かかる従来の問題点に鑑みてなされたもので，プラグホールに水や水蒸気が入り難い内燃機関用点火装置を提供しようとするものである。
【０００９】
【課題の解決手段】
本発明は，点火プラグを底部に取り付けシリンダヘッド外部に開口した開口部を備えたプラグホールに対し上記開口部から挿入して点火プラグと電気的に導通する点火コイルを有する内燃機関用点火装置であって，
上記点火コイルは，上記プラグホールの開口部を閉塞するコイルフランジ部を有し，
上記コイルフランジ部の下面と上記開口部の周縁との間に環状のシール板を介装し，
上記コイルフランジ部と上記シール板との間に，上記プラグホール内部と上記シリンダヘッド外部との間でガス交換を可能とするガス通路を有し，
上記ガス通路は，上記シール板の上面に周方向に沿って形成した周溝部と，上記周溝部の外周側からシリンダヘッド外部に通じる外部通路と，上記周溝部の内周側からプラグホール内部に通じる内部通路とを設け，上記シール板と上記コイルフランジ部とを密接することで形成してなり，
上記内部通路側の周溝部の深さは，上記外部通路側の周溝部の深さよりも浅いことを特徴とする内燃機関用点火装置にある（請求項１）。
【００１０】
本発明にかかる内燃機関用点火装置において，プラグホール内部とシリンダヘッド外部との間でガス交換を行うガス通路は，シール板とコイルフランジ部との間に設けてある。シール板の上面に設けた内部通路と外部通路とを備えた周溝部がコイルフランジ部の下面に密接することで，周溝部がガス通路となる。
この構成において，内部通路側の周溝部を外部通路側の周溝部より浅くする。すなわち，周溝部を外部通路側から内部通路側に向かう昇り傾斜を有するように構成する。
【００１１】
こうすることで，シリンダヘッド外部から被水して，外部通路から水が浸入して外部通路側付近に水が溜まった際，水は内部通路側に向かう昇り傾斜を昇ることが困難であり，プラグホール内部への水の浸入を防ぐことができる。
そして，外部通路側付近に溜まった水は，外部通路側へ向かう傾斜を下って自然と外部通路から排水され，長時間ガス通路に水が溜まり難い。
【００１２】
以上，本発明によれば，プラグホールに水や水蒸気が入り難い内燃機関用点火装置を提供することができる。
【００１３】
【発明の実施の形態】
また，本発明の周溝部で最も深い部分は，外部通路と周溝部とが接続する領域に設けることが好ましく，周溝部で最も浅い部分を，内部通路と周溝部とが接続する領域に設けることが好ましい。
また，外部通路側から内部通路側に向かう昇り傾斜は，いわゆる単調増加的に構成することが好ましい。すなわち，周溝部における外部通路から内部通路に向かって水が通過すると想定される経路において，必ず外部通路に近いほうの深さがより深くなるような状態である。なお周溝部の底面の勾配は一様でなくともよい。
【００１４】
また，本発明において，上記内部通路側の周溝部の幅は，上記外部通路側の周溝部の幅よりも狭いことが好ましい（請求項２）。
外部通路側を幅広，内部通路側を幅狭とすることで，ガス通路に浸入した水を外部通路側付近で保持して，内部通路側への水の浸入を防ぐことができる。
そして，外部通路側付近に溜まった水は，外部通路側へ向かう傾斜を下って自然と外部通路から排水され，長時間ガス通路に水が溜まり難い。
また，周溝部の幅は後述する実施例１の図３に記載したよう漸次狭くなる構成だけでなくて，周溝部の途中に幅が狭くなる絞りを設けたり，不連続に幅を変更する構成とすることもできる。
【００１５】
また，上記周溝部の深さは，上記内部通路側から上記外部通路側に向かって連続的に変化し，上記周溝部の底面は滑らかな斜面からなることが好ましい（請求項３）。
この構成にかかる周溝部の底面は，くぼみのような不連続に深さが変更される部分を持たない。そのため，万が一内部通路側へ水が浸入した際も自然な排水が期待できる。水は深いくぼみから浅い部分へと移動することは困難であり，底面に段差を持つ周溝部において内部通路側から外部通路側への水の移動は殆ど期待できないと考えられるためである。
【００１６】
また，本発明にかかる内燃機関用点火装置は，各種車両や自動車等のエンジンに用いることが好ましい。
各種車両や自動車等は洗車や降雨等でしばしばシリンダヘッドに対する被水が発生するため，本発明に記載するようなプラグホール内部への水，水蒸気の浸入防止機構を必要とするためである。
【００１７】
【実施例】
以下に，図面を用いて本発明の実施例について説明する。
（実施例１）
本例にかかる内燃機関用点火装置２００は，図１〜図７に示すごとく，点火プラグ３５を底部２５に取り付けシリンダヘッド２外部に開口した開口部２１を備えたプラグホール２０に対し上記開口部２１から挿入して点火プラグ３５と電気的に導通する点火コイル３を有する内燃機関用点火装置２００である。
【００１８】
図１，図２に示すごとく，上記点火コイル３は，上記プラグホール２０の開口部２１を閉塞するコイルフランジ部４を有し，上記コイルフランジ部４の下面４１と上記開口部周縁２１０との間に環状のシール板１を介装する。上記コイルフランジ部４と上記シール板１との間に，上記プラグホール２０内部と上記シリンダヘッド２外部との間でガス交換を可能とするガス通路を有する。
【００１９】
上記ガス通路は，図３〜図６に示すごとく，上記シール板１の上面１０５に周方向に沿って形成した周溝部１１と，上記周溝部１１の外周側１１１からシリンダヘッド２の外部に通じる外部通路１２１と，上記周溝部１１の内周側１１２からプラグホール２０の内部に通じる内部通路１２２とを設け，上記シール板１と上記コイルフランジ部４とを密接させることで形成する。
【００２０】
そして，図４，図５に示すごとく，上記内部通路１２２側の周溝部１１の深さは，上記外部通路１２１側の周溝部１１の深さよりも浅い。また，図３に示すごとく，上記内部通路１２２側の周溝部１１の幅Ｗ２は，上記外部通路１２１側の周溝部の幅Ｗ１よりも狭い。
更に，図７（ａ）に示すごとく，上記周溝部１１の深さは，上記内部通路１２２側から上記外部通路１２１側に向かって次第に変化し，上記周溝部１１の底面１００は滑らかな斜面からなる。
【００２１】
以下，詳細に説明する。
図１，図２に示すごとく，自動車エンジンにて用いる内燃機関用点火装置２００において，シリンダヘッド２に設けた円筒型のプラグホール２０の底部２５には点火プラグ３５が点火部がプラグホール２０外部のエンジン内に露出するよう取り付けてある。
シリンダヘッド２の外部に開口した開口部２１から該開口部２１より径大のコイル頭部３１が露出するよう点火コイル３をプラグホール２０に挿入し，点火コイル３のコイル円筒部３２の先端に設けた筒型の取付部３２２の内部に，点火プラグ３５のプラグ頭部３５１を挿入する。プラグ頭部３５１は取付部３２２の内部でコイル３２１と接触し，ここで点火プラグ３５と点火コイル３が電気的に導通する。
【００２２】
取付部３２２とプラグ頭部３５１とプラグホール２０の内壁面２５１との間の絶縁性が確保できるように，絶縁性のプラグキャップ３３を取付部３２２とプラブ頭部３５１の外周を覆うように設ける。
そして点火コイル３におけるコイル頭部３１の下方は開口部２１より径大のコイルフランジ部４が設けてあり，コイルフランジ部４とシリンダヘッド２の開口部周縁２１０との間にシール板１を介装する。
【００２３】
シール板１は，図２〜図６に示すごとく，中央に点火コイル３のコイル円筒部３２を挿通する挿通穴１９０を備えた環状部材である。挿通穴１９０の周辺は挿通穴１９０に向かって傾斜した傾斜面１９１からなる。
シール板１で，開口部２１と向き合う下面１０３は，開口部周縁２１０側に突出して環状のシール板１の周方向に沿って形成した環状脚部１０４を有し，該環状脚部１０４の先端と開口部周縁２１０とが当接することで，シール板１とシリンダヘッド２との間がシールされる。なお，上記シール板１は，サンプレン，ＥＰＤＭ，アクリル樹脂，シリコーンゴム，フッ素樹脂等の耐熱弾性絶縁体の樹脂や耐熱ゴムの円盤からなる。
【００２４】
そして，上記シール板１のコイルフランジ部４側を向いた上面１０５とコイルフランジ部４との間にガス通路が形成され，ここを通じて，プラグホール２０内部とシリンダヘッド２外部とのガス交換が行われる。
上記ガス通路は，主としてシール板１の上面１０５に設けた周溝部１１と内部通路１２２，外部通路１２１から形成される。
【００２５】
上記シール板１の上面１０５の周溝部１１等について説明する。
図３に示すごとく，周溝部１１は，シール板１の周方向に沿った環状溝からなり，環状溝の外側に位置する外周部１０１と内側に位置する内周部１０２とが，それぞれコイルフランジ部４に密接することで，コイルフランジ部４とシール板１との間をシールする。
ここで符号１１１が周溝部１１の外周壁面，符号１１２が内周壁面となる。符号１００は周溝部１１の底面である。外周壁面１１１からシール板１の外側面１９２に対して開口した外部通路１２１を有し，内周壁面１１２からシール板１の挿通穴１９０に対して開口した内部通路１２２を有する。
【００２６】
そして，図３に示すごとく，周溝部１１に対し外部通路１２１が開口する連結部１１３にかかる周溝部１１の幅Ｗ１が最も広く，内部通路１２２が開口する連結部１１４にかかる周溝部１１の幅Ｗ２が最も狭い。そして，連結部１１３と連結部１１４との間は連結部１１４に向けて漸次周溝部１１の幅が狭くなっていく。
なお，周溝部１１の幅とは，シール板１の中心位置Ｇを通る径方向の直線に沿って計った長さである。
更に，周溝部１１の深さも，図４，図５，図６に示すごとく，連結部１１３の深さが一番深く，連結部１１４の深さが一番浅い。そして，図７（ａ）に示すごとく，連結部１１３と連結部１１４との間は連結部１１４に向けて漸次浅くなっていき，底面１００に段差等は殆どなく滑らかな状態に構成される。なお，図７（ａ）は，周溝部１１の幅方向中心位置の軌跡であるＫ１（図３参照）に沿った周溝部１１の底面１００を示した説明図である。
なお，図７（ａ）においては底面１００の軌跡Ｋ１は滑らかに推移する形状となっているが，図７（ｂ）のように階段状に深さが変化する形状としてもよい。
ここでも階段状の底面は，連結部１１３から連結部１１４に向けて，漸次浅くなっていく。
【００２７】
また，上記シール板１の外部通路１２１と内部通路１２２は，シール板１の中心位置Ｇを挟んで径方向に対称的な位置にあるため，内部通路１２２から周溝部１１を経由して外部通路１２１に抜けるガス通路の経路長さは図３において上側の周溝部１１を経由する場合と，下側の周溝部１１を経由する場合とが略等しくなる。
【００２８】
次に本例にかかる作用効果について説明する。
本例の内燃機関用点火装置２００において，プラグホール２０内部とシリンダヘッド２外部とでガス交換を可能とするガス通路は，シール板１とコイルフランジ部４との間に形成される。
シール板１の上面１０５に設けた内部通路１２２と外部通路１２１とを備えた周溝部１１がコイルフランジ部４の下面４１に密接することで，周溝部１１がガス通路となる。周溝部１１の深さは連結部１１３が一番深く，連結部１１４が一番浅い。
そして，図７（ａ）に示すごとく，連結部１１３と連結１１４との間は連結１１４に向けて漸次浅くなっていき，底面１００に段差等は殆どなく滑らかな状態に構成される。すなわち，周溝部１１を外部通路１２１側から内部通路１２２側に向かう昇り傾斜を有するように構成する。
【００２９】
こうすることで，シリンダヘッド２外部から被水して，外部通路１２１から水が浸入して連結部１１３付近に水が溜まった際，水は内部通路１２２側に向かう昇り傾斜を昇ることができずに，プラグホール２０内部への水の浸入を防ぐことができる。そして，連結部１１３付近に溜まった水は，自然と外部通路１２１から排水される。よって，本例は長時間ガス通路に水が溜まり難い構成である。
【００３０】
以上，本例によれば，プラグホールに水や水蒸気が入り難い内燃機関用点火装置を提供することができる。
【００３１】
更に，本例は，連結部１１３近傍の周溝部１１の幅Ｗ１が最も広く，連結部１１４の近傍の幅Ｗ２が一番狭い。そして，連結部１１３と連結部１１４との間は連結部１１４に向けて漸次周溝部１１の幅が狭くなるよう構成する。この構成からも水は内部通路１２２側へ移動し難い。
また，上記周溝部１１の深さは，図７（ａ）に示すごとく，連結部１１３から連結部１１４に向かって連続的に変化し，底面１００は滑らかな昇り斜面である。段差のような不連続に深さが変更される部分がないため，万が一内部通路１２２側へ水が浸入した際も自然な排水を期待できる。
【図面の簡単な説明】
【図１】実施例１における，内燃機関用点火装置の全体を示す説明図。
【図２】実施例１における，コイルフランジ部とシール板との密接状態を示す説明図。
【図３】実施例１における，シール板の平面図。
【図４】実施例１における，シール板の内部通路を設けた連結部を矢線Ｂ方向からみた説明図。
【図５】実施例１における，シール板の外部通路を設けた連結部を矢線Ｃ方向からみた説明図。
【図６】実施例１における，シール板の図６にかかるＡ−Ａ矢視断面図。
【図７】実施例１における，（ａ）図３の破線Ｋ１に沿った断面の要部説明図，（ｂ）階段状に深さが変化する周溝部の断面の説明図。
【図８】従来における，シール板の平面図。
【図９】従来における，シール板のＤ−Ｄ矢視断面図。
【符号の説明】
１．．．シール板，
１００．．．底面，
１０５．．．上面，
１１．．．周溝部，
１２１．．．外部通路，
１２２．．．内部通路，
２．．．シリンダヘッド，
２００．．．内燃機関用点火装置，
２１．．．開口部，
２１０．．．開口部周縁，
２５．．．底部，
３．．．点火コイル，
３５．．．点火プラグ，
４．．．コイルフランジ部，
４１．．．下面，[0001]
【Technical field】
The present invention relates to an ignition device for an internal combustion engine having an ignition plug for performing an ignition operation in a combustion chamber of an internal combustion engine and an ignition coil for energizing the ignition plug.
[0002]
[Prior art]
As shown in FIGS. 1 and 2 to be described later, a plug hole provided in the cylinder head of the internal combustion engine has a spark plug attached to the bottom surface, and the spark plug is electrically connected to an ignition coil inserted in the plug hole and inside the plug hole. Connected.
The plug hole has an opening that opens to the outside of the cylinder head, the opening is closed by a coil flange provided below the coil head, and the coil flange and the plug hole are opened to prevent dust and water from entering. A disc-shaped sealing plate is provided between the outer peripheral surface of the cylinder head and the outer surface of the cylinder head to close the plug hole.
[0003]
However, the gas in the plug hole may be heated and expanded due to combustion in the combustion chamber of the internal combustion engine or heat generated during operation of the ignition coil, and there is a problem in completely sealing the plug hole.
Furthermore, since current between the ignition coil and the ignition plug is often performed by a high-voltage current, ozone may be generated, and ventilation in the plug hole may be required.
Therefore, a gas passage is generally provided between the seal plate and the coil flange so that gas can be exchanged between the inside of the plug hole and the outside of the cylinder head.
[0004]
FIGS. 8 and 9 show a conventionally known configuration as a specific example of the gas passage.
As shown in FIGS. 8 and 9, a circumferential groove portion 90 is provided on the upper surface 105 of the seal plate 9 facing the coil flange portion side, and the coil flange portion and the seal plate 9 are brought into close contact. Thus, the circumferential groove 90 can be used as a gas passage.
That is, as shown in FIGS. 8 and 9, the peripheral groove portion 90 includes a plurality of water reservoir portions 91 provided on the upper surface 105 of the annular seal plate 9 and a connection groove 92 connecting the water reservoir portions 91.
The depth of the water reservoir 91 is deeper than the connection groove 92, and an inner passage 122 communicating with the inside of the plug hole is provided on the inner periphery of one connection groove 92, and a cylinder is provided on the outer periphery of another connection groove 92 having no internal passage 122. An external passage 121 communicating with the outside of the head is provided.
A gas passage is formed by bringing the seal plate 9 according to this configuration into close contact with the coil flange portion.
[0005]
The gas inside the plug hole enters the connecting groove 92 provided with the external passage 121 through the internal passage 122, the connecting groove 92 provided with the internal passage 122, and the water reservoir 91 adjacent to the connecting groove 92. It can pass through the passage 121 and escape to the outside of the cylinder head.
When water enters the gas passage due to water from the outside of the cylinder head, the water accumulates in the water storage groove 91 deeper than the connection groove 92, and the force is suppressed, so that it is difficult to reach the inside of the plug hole.
[0006]
[Patent Document 1]
Japanese Patent No. 03145880
[Problem to be solved]
However, in the case of the above-described conventional configuration, the water that has entered may stay in the water reservoir 91 for a long time, and the water may evaporate and become water vapor and enter the inside of the plug hole.
In this case, there is a possibility that the contact point between the ignition plug and the ignition coil is corroded and a conduction failure occurs, or a high voltage leak easily occurs between the inner wall surface of the plug hole and the ignition coil.
[0008]
The present invention has been made in view of such a conventional problem, and has as its object to provide an ignition device for an internal combustion engine in which water and water vapor hardly enter a plug hole.
[0009]
[Means for solving the problem]
The present invention relates to an ignition device for an internal combustion engine having an ignition coil which is inserted into a plug hole provided with an opening opened to the outside of a cylinder head through the opening and which is electrically connected to the ignition plug. So,
The ignition coil has a coil flange for closing an opening of the plug hole,
An annular seal plate is interposed between the lower surface of the coil flange and the periphery of the opening,
A gas passage between the coil flange portion and the seal plate for allowing gas exchange between the inside of the plug hole and the outside of the cylinder head;
The gas passage has a circumferential groove formed on the upper surface of the seal plate along the circumferential direction, an external passage communicating from the outer peripheral side of the peripheral groove to the outside of the cylinder head, and a gas passage extending from the inner peripheral side of the peripheral groove to the inside of the plug hole. An internal passage communicating with the seal plate and the coil flange portion are formed in close contact with each other.
An internal combustion engine ignition device according to claim 1, wherein a depth of the peripheral groove on the inner passage side is smaller than a depth of the peripheral groove on the outer passage side.
[0010]
In the ignition device for an internal combustion engine according to the present invention, a gas passage for performing gas exchange between the inside of the plug hole and the outside of the cylinder head is provided between the seal plate and the coil flange portion. When the peripheral groove provided with the internal passage and the external passage provided on the upper surface of the seal plate is in close contact with the lower surface of the coil flange, the peripheral groove serves as a gas passage.
In this configuration, the peripheral groove on the internal passage side is made shallower than the peripheral groove on the external passage side. That is, the peripheral groove is configured to have an upward slope from the external passage side to the internal passage side.
[0011]
In this way, when water is applied from the outside of the cylinder head and water infiltrates from the external passage and accumulates near the external passage, it is difficult for the water to rise and incline toward the internal passage. Water can be prevented from entering the inside of the plug hole.
The water accumulated near the external passage is naturally drained from the external passage down the slope toward the external passage, and it is difficult for the water to accumulate in the gas passage for a long time.
[0012]
As described above, according to the present invention, it is possible to provide an ignition device for an internal combustion engine in which water and water vapor hardly enter the plug hole.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferably, the deepest part of the peripheral groove of the present invention is provided in a region where the external passage and the peripheral groove are connected, and the shallowest part of the peripheral groove is provided in a region where the internal passage and the peripheral groove are connected. Is preferred.
Further, it is preferable that the upward inclination from the external passage side to the internal passage side is configured to be monotonically increasing. That is, in a path in which water is assumed to pass from the external passage to the internal passage in the circumferential groove, the depth closer to the external passage is necessarily greater. The slope of the bottom surface of the peripheral groove may not be uniform.
[0014]
In the present invention, the width of the peripheral groove on the internal passage side is preferably smaller than the width of the peripheral groove on the external passage side.
By making the outer passage side wider and the inner passage side narrower, water that has entered the gas passage can be held near the outer passage side, and water can be prevented from entering the inner passage side.
The water accumulated near the external passage is naturally drained from the external passage down the slope toward the external passage, and it is difficult for the water to accumulate in the gas passage for a long time.
In addition to the configuration in which the width of the peripheral groove is gradually reduced as shown in FIG. 3 of the first embodiment described later, a configuration in which the width is reduced in the middle of the peripheral groove or the configuration in which the width is discontinuously changed. It can also be.
[0015]
Further, it is preferable that the depth of the peripheral groove portion continuously changes from the internal passage side to the external passage side, and the bottom surface of the peripheral groove portion is formed of a smooth slope.
The bottom surface of the circumferential groove portion according to this configuration does not have a portion such as a depression whose depth is changed discontinuously. Therefore, natural drainage can be expected even if water enters the internal passage. This is because it is difficult for water to move from a deep depression to a shallow portion, and it is considered that almost no movement of water from the internal passage side to the external passage side can be expected in the circumferential groove having a step on the bottom surface.
[0016]
Further, the ignition device for an internal combustion engine according to the present invention is preferably used for engines of various vehicles and automobiles.
This is because various vehicles, automobiles, and the like often receive water on the cylinder head due to car washing or rainfall, and thus require a mechanism for preventing water and water vapor from entering the inside of the plug hole as described in the present invention.
[0017]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Example 1)
As shown in FIGS. 1 to 7, the ignition device 200 for an internal combustion engine according to the present embodiment has a spark plug 35 attached to a bottom 25 and an opening 21 having an opening 21 opened to the outside of the cylinder head 2. This is an ignition device 200 for an internal combustion engine having an ignition coil 3 inserted from 21 and electrically connected to an ignition plug 35.
[0018]
As shown in FIGS. 1 and 2, the ignition coil 3 has a coil flange 4 for closing the opening 21 of the plug hole 20, and the lower surface 41 of the coil flange 4 and the periphery 210 of the opening. An annular seal plate 1 is interposed therebetween. A gas passage is provided between the coil flange portion 4 and the seal plate 1 to allow gas exchange between the inside of the plug hole 20 and the outside of the cylinder head 2.
[0019]
As shown in FIGS. 3 to 6, the gas passage communicates with the peripheral groove 11 formed along the circumferential direction on the upper surface 105 of the seal plate 1 and the outside of the cylinder head 2 from the outer peripheral side 111 of the peripheral groove 11. An external passage 121 and an internal passage 122 communicating from the inner peripheral side 112 of the peripheral groove portion 11 to the inside of the plug hole 20 are provided, and the seal plate 1 and the coil flange portion 4 are formed in close contact.
[0020]
As shown in FIGS. 4 and 5, the depth of the peripheral groove 11 on the inner passage 122 side is smaller than the depth of the peripheral groove 11 on the outer passage 121 side. Further, as shown in FIG. 3, the width W2 of the peripheral groove 11 on the side of the internal passage 122 is smaller than the width W1 of the peripheral groove on the side of the external passage 121.
Further, as shown in FIG. 7A, the depth of the peripheral groove portion 11 gradually changes from the internal passage 122 side to the external passage 121 side, and the bottom surface 100 of the peripheral groove portion 11 is formed from a smooth slope. Become.
[0021]
The details are described below.
As shown in FIGS. 1 and 2, in an ignition device 200 for an internal combustion engine used in an automobile engine, an ignition plug 35 is provided at the bottom 25 of a cylindrical plug hole 20 provided in the cylinder head 2. It is installed to be exposed inside the engine.
The ignition coil 3 is inserted into the plug hole 20 so that the coil head 31 having a larger diameter than the opening 21 is exposed from the opening 21 opened to the outside of the cylinder head 2. The plug head 351 of the ignition plug 35 is inserted into the inside of the provided cylindrical mounting portion 322. The plug head 351 contacts the coil 321 inside the mounting portion 322, and the ignition plug 35 and the ignition coil 3 are electrically connected.
[0022]
An insulating plug cap 33 is provided so as to cover the outer periphery of the mounting portion 322 and the plug head 351 so that insulation between the mounting portion 322, the plug head 351 and the inner wall surface 251 of the plug hole 20 can be ensured. .
Below the coil head 31 of the ignition coil 3 is provided a coil flange portion 4 having a diameter larger than that of the opening portion 21, and a seal plate 1 is interposed between the coil flange portion 4 and the peripheral portion 210 of the opening portion of the cylinder head 2. Dress.
[0023]
As shown in FIGS. 2 to 6, the seal plate 1 is an annular member provided with an insertion hole 190 at the center for inserting the coil cylindrical portion 32 of the ignition coil 3. The periphery of the insertion hole 190 includes an inclined surface 191 that is inclined toward the insertion hole 190.
The lower surface 103 of the seal plate 1 facing the opening 21 has an annular leg 104 protruding toward the periphery 210 of the opening and formed along the circumferential direction of the annular seal plate 1. The contact between the sealing plate 1 and the cylinder head 2 is achieved by the contact between the sealing plate 1 and the peripheral edge 210 of the opening. The seal plate 1 is made of a heat-resistant elastic insulating resin such as sampler, EPDM, acrylic resin, silicone rubber, and fluororesin, or a disk made of heat-resistant rubber.
[0024]
A gas passage is formed between the upper surface 105 of the seal plate 1 facing the coil flange portion 4 and the coil flange portion 4, through which gas exchange between the inside of the plug hole 20 and the outside of the cylinder head 2 is performed. Be done.
The gas passage is mainly formed by the peripheral groove 11 provided on the upper surface 105 of the seal plate 1, the internal passage 122, and the external passage 121.
[0025]
The peripheral groove 11 on the upper surface 105 of the seal plate 1 will be described.
As shown in FIG. 3, the peripheral groove portion 11 is formed of an annular groove along the circumferential direction of the seal plate 1, and an outer peripheral portion 101 located outside the annular groove and an inner peripheral portion 102 located inside the annular groove are coil flanges, respectively. Close contact with the portion 4 seals the gap between the coil flange portion 4 and the seal plate 1.
Here, reference numeral 111 denotes an outer peripheral wall surface of the peripheral groove portion 11, and reference numeral 112 denotes an inner peripheral wall surface. Reference numeral 100 denotes a bottom surface of the circumferential groove 11. It has an external passage 121 opening from the outer peripheral wall surface 111 to the outer surface 192 of the seal plate 1, and has an internal passage 122 opening from the inner peripheral wall surface 112 to the insertion hole 190 of the seal plate 1.
[0026]
As shown in FIG. 3, the width W1 of the peripheral groove 11 over the connecting portion 113 where the external passage 121 is open with respect to the peripheral groove 11 is the widest, and the width of the peripheral groove 11 over the connecting portion 114 where the internal passage 122 opens. W2 is the narrowest. The width of the circumferential groove 11 gradually decreases toward the connecting portion 114 between the connecting portions 113 and 114.
The width of the circumferential groove 11 is a length measured along a radial straight line passing through the center position G of the seal plate 1.
Further, as shown in FIGS. 4, 5, and 6, the depth of the circumferential groove 11 is the deepest in the connecting portion 113 and the lowest in the connecting portion 114. Then, as shown in FIG. 7A, the space between the connecting portions 113 and 114 gradually becomes shallower toward the connecting portion 114, and the bottom surface 100 has a smooth state with almost no steps. FIG. 7A is an explanatory diagram showing the bottom surface 100 of the circumferential groove 11 along K1 (see FIG. 3), which is the locus of the center position of the circumferential groove 11 in the width direction.
In FIG. 7A, the locus K1 of the bottom surface 100 has a smoothly changing shape, but may have a shape in which the depth changes stepwise as shown in FIG. 7B.
Also in this case, the stepped bottom gradually becomes shallower from the connecting portion 113 toward the connecting portion 114.
[0027]
Further, since the outer passage 121 and the inner passage 122 of the seal plate 1 are radially symmetrical with respect to the center position G of the seal plate 1, the outer passage 121 and the outer passage In FIG. 3, the path length of the gas passage passing through 121 is substantially equal between the case where the gas passes through the upper peripheral groove 11 and the case where it passes through the lower peripheral groove 11.
[0028]
Next, the operation and effect according to this example will be described.
In the ignition device 200 for an internal combustion engine of the present embodiment, a gas passage allowing gas exchange between the inside of the plug hole 20 and the outside of the cylinder head 2 is formed between the seal plate 1 and the coil flange portion 4.
When the peripheral groove 11 provided with the internal passage 122 and the external passage 121 provided on the upper surface 105 of the seal plate 1 is in close contact with the lower surface 41 of the coil flange 4, the peripheral groove 11 becomes a gas passage. The depth of the circumferential groove 11 is the deepest at the connecting portion 113 and the shallowest at the connecting portion 114.
Then, as shown in FIG. 7A, the portion between the connecting portion 113 and the connecting portion 114 gradually becomes shallower toward the connecting portion 114, and the bottom surface 100 has a smooth state with almost no steps. That is, the circumferential groove 11 is configured to have a rising slope from the external passage 121 to the internal passage 122.
[0029]
By doing so, when water is applied from the outside of the cylinder head 2 and water infiltrates from the external passage 121 and accumulates in the vicinity of the connecting portion 113, the water can rise upward and incline toward the internal passage 122. Therefore, intrusion of water into the plug hole 20 can be prevented. Then, the water accumulated near the connecting portion 113 is naturally drained from the external passage 121. Therefore, this embodiment has a configuration in which water hardly accumulates in the gas passage for a long time.
[0030]
As described above, according to the present embodiment, it is possible to provide an ignition device for an internal combustion engine in which water and water vapor hardly enter the plug hole.
[0031]
Further, in this example, the width W1 of the peripheral groove portion 11 near the connecting portion 113 is the widest, and the width W2 near the connecting portion 114 is the narrowest. The width of the circumferential groove portion 11 between the connecting portion 113 and the connecting portion 114 is gradually reduced toward the connecting portion 114. Also from this configuration, it is difficult for water to move to the internal passage 122 side.
As shown in FIG. 7A, the depth of the peripheral groove portion 11 continuously changes from the connecting portion 113 toward the connecting portion 114, and the bottom surface 100 is a smoothly rising slope. Since there is no discontinuous portion where the depth is changed, such as a step, natural drainage can be expected even if water intrudes into the internal passage 122 side.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an entire ignition device for an internal combustion engine according to a first embodiment.
FIG. 2 is an explanatory diagram showing a close contact state between a coil flange portion and a seal plate in the first embodiment.
FIG. 3 is a plan view of a seal plate according to the first embodiment.
FIG. 4 is an explanatory diagram of the connecting portion provided with the internal passage of the seal plate in the first embodiment as viewed from the direction of arrow B;
FIG. 5 is an explanatory view of the connecting portion provided with the external passage of the seal plate in the first embodiment as viewed from the direction of arrow C;
FIG. 6 is a cross-sectional view of the seal plate taken along line AA of FIG. 6 according to the first embodiment.
FIGS. 7A and 7B are explanatory diagrams of a main part of a cross section taken along a broken line K1 in FIG. 3, and FIGS. 7B and 7B are explanatory diagrams of a cross section of a circumferential groove portion whose depth changes stepwise.
FIG. 8 is a plan view of a conventional seal plate.
FIG. 9 is a cross-sectional view of the seal plate taken along line DD in the related art.
[Explanation of symbols]
1. . . Sealing plate,
100. . . Bottom,
105. . . Upper surface,
11. . . Circumferential groove,
121. . . External passage,
122. . . Internal passage,
2. . . cylinder head,
200. . . Ignition device for internal combustion engine,
21. . . Aperture,
210. . . Around the opening,
25. . . bottom,
3. . . Ignition coil,
35. . . Spark plug,
4. . . Coil flange,
41. . . Bottom,

Claims

An ignition device for an internal combustion engine, comprising: an ignition coil having a spark plug attached to a bottom thereof and having an opening opened to the outside of a cylinder head and inserted through the opening to electrically communicate with the spark plug.
The ignition coil has a coil flange for closing an opening of the plug hole,
An annular seal plate is interposed between the lower surface of the coil flange and the periphery of the opening,
A gas passage between the coil flange portion and the seal plate for allowing gas exchange between the inside of the plug hole and the outside of the cylinder head;
The gas passage has a circumferential groove formed on the upper surface of the seal plate along the circumferential direction, an external passage communicating from the outer peripheral side of the peripheral groove to the outside of the cylinder head, and a gas passage extending from the inner peripheral side of the peripheral groove to the inside of the plug hole. An internal passage communicating with the seal plate and the coil flange portion are formed in close contact with each other.
The ignition device for an internal combustion engine according to claim 1, wherein a depth of the peripheral groove portion on the internal passage side is smaller than a depth of the peripheral groove portion on the external passage side.

2. The ignition device for an internal combustion engine according to claim 1, wherein a width of the peripheral groove on the inner passage side is smaller than a width of the peripheral groove on the outer passage side.

3. The internal combustion engine according to claim 1, wherein the depth of the peripheral groove portion gradually changes from the internal passage side toward the external passage side, and a bottom surface of the peripheral groove portion is formed as a smooth slope. Ignition device.