JP4176407B2

JP4176407B2 - engine

Info

Publication number: JP4176407B2
Application number: JP2002213705A
Authority: JP
Inventors: 大浅利; 幾朗原; 広高岸; 和明下山
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2002-07-23
Filing date: 2002-07-23
Publication date: 2008-11-05
Anticipated expiration: 2022-07-23
Also published as: JP2004052707A

Description

【０００１】
【発明の属する技術分野】
本発明は、一端に動力入力部を有する第１カムシャフトと、一端部が第１カムシャフトに連動、連結される第２カムシャフトとが、相互に平行な軸線を有してシリンダヘッドに回転自在に支承され、第１および第２カムシャフトの一方の他端部に設けられた駆動ギヤに噛合する被動ギヤが、シリンダヘッドを含むエンジン本体に取付けられた補機に連なる補機駆動軸に設けられるエンジンに関する。
【０００２】
【従来の技術】
カムシャフトに設けられた駆動ギヤを、バキュームポンプおよび油圧ポンプに連なる補機駆動軸に設けられた被動ギヤに噛合させたエンジンが、たとえば特開平８−２６１００１号公報で知られている。
【０００３】
【発明が解決しようとする課題】
上記従来のものは、単一のカムシャフトを備えたＳＯＨＣ型エンジンであるが、一対のカムシャフトを備えるエンジンに、上記従来のものと同様な補機駆動構造を適用したときには、一対のカムシャフトに干渉することを避けつつ、エンジンを極力コンパクト化し得るように補機を駆動するための構造を構成することが望まれる。
【０００４】
本発明は、かかる事情に鑑みてなされたものであり、カムシャフトで補機を駆動するにあたって、コンパクト化を可能としたエンジンを提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するために、請求項１記載の発明は、一端に動力入力部を有する第１カムシャフトと、一端部が第１カムシャフトに連動、連結される第２カムシャフトとが、相互に平行な軸線を有してシリンダヘッドに回転自在に支承され、第１および第２カムシャフトの一方の他端部に設けられた駆動ギヤに噛合する被動ギヤが、シリンダヘッドを含むエンジン本体の前記軸線に沿う方向の一端部に取付けられた補機に連なる補機駆動軸に設けられるエンジンにおいて、第１および第２カムシャフトの軸線を結ぶ直線よりもシリンダヘッド側で前記両カムシャフト間に前記補機駆動軸の軸線が配置され、前記シリンダヘッドには、前記被動ギヤの一部を収容する凹部が、該凹部内に溜まったオイルを前記被動ギヤが掻き揚げて前記駆動ギヤおよび前記被動ギヤの噛合部を潤滑することができるようにして設けられ、前記被動ギヤの、前記補機側の側面に隣接配置されて前記補機駆動軸を支承する軸受部材が、シリンダ軸線に沿う方向から見て前記駆動ギヤに重なる位置に該軸受部材の一部が配置されるようにして底面をシリンダヘッドに締結され、前記駆動ギヤとの干渉を避ける切欠きが前記軸受部材の、前記補機とは反対側の側面に形成されることを特徴とする。
【０００６】
さらに請求項２記載の発明は、一端に動力入力部を有する第１カムシャフトと、一端部が第１カムシャフトに連動、連結される第２カムシャフトとが、相互に平行な軸線を有してシリンダヘッドに回転自在に支承され、第１および第２カムシャフトの一方の他端部に設けられた駆動ギヤに噛合する被動ギヤが、シリンダヘッドを含むエンジン本体の前記軸線に沿う方向の一端部に取付けられた補機に連なる補機駆動軸に設けられるエンジンにおいて、第１および第２カムシャフトの軸線を結ぶ直線よりもシリンダヘッド側で前記両カムシャフト間に前記補機駆動軸の軸線が配置され、前記シリンダヘッドには、前記被動ギヤの一部を収容する凹部が、該凹部内に溜まったオイルを前記被動ギヤが掻き揚げて前記駆動ギヤおよび前記被動ギヤの噛合部を潤滑することができるようにして設けられ、前記被動ギヤの、前記補機側の側面に隣接配置されて前記補機駆動軸を支承する軸受部材が、シリンダ軸線に沿う方向から見て前記駆動ギヤに重なる位置に該軸受部材の一部が配置されるようにして、複数のボルトによりシリンダヘッドに底面を締結され、前記複数のボルトのうち一部のボルトがシリンダ軸線に沿う方向から見て前記駆動ギヤと重なる位置を避けて前記補機駆動軸の両側に配置され、残余のボルトが前記シリンダ軸線に沿う方向から見て前記駆動ギヤと重なる位置に配置され、前記一部のボルトの頂面を通って前記両カムシャフトの軸線と平行な第１仮想平面と、前記残余のボルトの頂面を通って前記第１仮想平面と平行な第２仮想平面との間に、前記駆動ギヤの外周面のうち前記残余のボルトに対向する部分が配置されることを特徴とする。
【０００７】
このような請求項１，２記載の各特徴によれば、一対のカムシャフト間の間隔を拡げることなく、補機駆動軸を両カムシャフトの一方に近接させて、シリンダ軸線に沿う方向でエンジンのコンパクト化を図ることができる。しかも被動ギヤの一部を収容する凹部がシリンダヘッドに設けられることによってシリンダ軸線に沿う方向でのカムシャフトの高さを極力低くしてエンジンのコンパクト化に寄与することができ、また凹部内に溜まったオイルを被動ギヤが掻き揚げることにより、駆動ギヤおよび被動ギヤの噛合部を潤滑することができる。また補機駆動軸を支承する軸受部材を、シリンダ軸線に沿う方向でのカムシャフトの位置が高くなることを回避しつつ、カムシャフトの軸線に沿う方向で駆動ギヤに近接配置することができ、エンジンのコンパクト化に寄与することができる。
【０００８】
【発明の実施の形態】
以下、本発明の実施形態を、添付図面に示す本発明の一実施例に基づいて説明する。
【０００９】
図１〜図８は本発明の一実施例を示すものであり、図１はエンジンの一部縦断面図であって図３の１−１線に沿う断面図、図２はヘッドカバーを外した状態での図１の２−２線矢視図、図３は図２の３矢示部拡大図、図４は図１の４ー４線断面図、図５は図２の５矢示部拡大図、図６は図５の６−６線拡大断面図、図７は図６の７−７線断面図、図８は図７の８−８線断面図である。
【００１０】
先ず図１および図２において、このエンジンは、圧縮点火式のＤＯＨＣ型直列４気筒エンジンであり、エンジン本体１０の一部を構成するシリンダヘッド１１およびシリンダブロック１２間には、図示しないピストンの頂部を臨ませる燃焼室１３が第１〜第４の各気筒Ｃ１，Ｃ２，Ｃ３，Ｃ４毎にそれぞれ形成され、各燃焼室１３に開口する吸気弁口１４Ａ，１４Ｂおよび排気弁口１５Ａ，１５Ｂが気筒配列方向１６に沿う方向に並んだ各気筒Ｃ１〜Ｃ４毎に一対ずつシリンダヘッド１１に設けられるとともに、両吸気弁口１４Ａ，１４Ｂに連通可能な一対ずつの吸気ポート１７Ａ，１７Ｂならびに両排気弁口１５Ａ，１５Ｂに連通可能な一対ずつの排気ポート１８Ａ，１８Ｂがシリンダヘッド１１に設けられ、各燃焼室１３の中心部に臨むようにして図示しない燃料噴射弁がシリンダヘッド１１に取付けられる。
【００１１】
各吸気弁口１４Ａ，１４Ｂを開閉可能な吸気弁２０…がシリンダヘッド１１に設けられたガイド筒２１…に摺動可能に嵌合され、各吸気弁２０…の上端は、シリンダヘッド１１ならびにシリンダヘッド１１に結合されるヘッドカバー２４間に形成される動弁室２５内に前記ガイド筒２１…から突出され、各吸気弁２０…の上端に設けられたリテーナ２２…およびシリンダヘッド１１間にそれぞれ設けられる弁ばね２３…により各吸気弁２０…は閉弁方向に付勢される。また各排気弁口１５Ａ，１５Ｂを開閉可能な排気弁２６…がシリンダヘッド１１に設けられたガイド筒２７…に摺動可能に嵌合され、各排気弁２６…の上端は動弁室２５内に前記ガイド筒２７…から突出され、各排気弁２６…の上端に設けられたリテーナ２８…およびシリンダヘッド１１間にそれぞれ設けられる弁ばね２９…により各排気弁２６…は閉弁方向に付勢される。
【００１２】
気筒配列方向１６に沿って相互に平行な軸線を有する第１および第２カムシャフト３１，３２が、前記気筒配列方向１６に間隔をあけた位置で前記各カムシャフト毎にシリンダヘッド１１に設けられた複数の第１および第２軸受部３３Ａ，３３…、３４Ａ，３４…でそれぞれ回転自在に支承されるものであり、第１軸受部３３Ａ，３３…および第２軸受部３４Ａ，３４…は、シリンダヘッド１１に締結されるロアカムホルダ３５と、該ロアカムホルダ３５に締結される複数の排気側および吸気側のアッパカムホルダ３６…，３７…とで構成され、アッパカムホルダ３６…，３７…はロアカムホルダ３５とともに複数のボルト３８…によりシリンダヘッド１１に締結される。
【００１３】
図３を併せて参照して、ロアカムホルダ３５は、気筒配列方向１６に沿って延びる一対の外側縦枠３５ａ，３５ｂと、外側縦枠３５ａ，３５ｂの内方に配置されて気筒配列方向１６に沿って延びる一対の内側縦枠３５ｃ，３５ｄとを一体に有した一体枠構造に形成されるものであり、各排気弁２６…が配置される側の外側縦枠３５ａおよび内側縦枠３５ｃ間には、第１カムシャフト３１の下半部を受ける５つの下側軸受部３５ｄ…が各気筒Ｃ１〜Ｃ４を両側から挟むようにして設けられ、下側軸受部３５ｄ…と協働して第１軸受部３３Ａ，３３…を構成するようにして排気側のアッパカムホルダ３６…がロアカムホルダ３５に締結される。また各吸気弁２０…が配置される側の外側縦枠３５ｂおよび内側縦枠３５ｄ間には、第２カムシャフト３２の下半部を受ける５つの下側軸受部３５ｅ…が各気筒Ｃ１〜Ｃ４を両側から挟むようにして設けられ、下側軸受部３５ｅ…と協働して第２軸受部３４Ａ，３４…を構成するようにして吸気側のアッパカムホルダ３７…がロアカムホルダ３５に締結される。
【００１４】
複数の第１軸受部３３Ａ，３３…相互間で、各排気弁２６…が配置される側の外側縦枠３５ａおよび内側縦枠３５ｃは仕切り壁３５ｆ…で連結されており、また複数の第２軸受部３４Ａ，３４…相互間で、各吸気弁２０…が配置される側の外側縦枠３５ｂおよび内側縦枠３５ｄは仕切り壁３５ｇ…で連結される。
【００１５】
各排気弁２６…が配置される側の第１軸受部３３Ａ，３３…および仕切り壁３５ｆ…間には、第１カムシャフト３１の軸線と直交する平面内での揺動を可能として一端が油圧タペット４２を介してシリンダヘッド１１にピボット支持される排気側ロッカアーム４０がそれぞれ配置されており、各排気側ロッカアーム４０…の他端は、各排気弁２６…の上端に当接することで各排気弁２６…に連動、連結される。また各吸気弁２０…が配置される側の第２軸受部３４Ａ，３４…および仕切り壁３５ｇ…間には、第２カムシャフト３２の軸線と直交する平面内での揺動を可能として一端が油圧タペット４３を介してシリンダヘッド１１にピボット支持される吸気側ロッカアーム４１がそれぞれ配置されており、各吸気側ロッカアーム４１…の他端は、各吸気弁２０…の上端に当接することで各吸気弁２０…に連動、連結される。
【００１６】
図４を併せて参照して、各吸気弁２０…が配置される側の第２軸受部３４Ａ，３４…および仕切り壁３５ｇ…には、吸気側ロッカアーム４１…側に突出した突部４６…がそれぞれ設けられており、それらの突部４６…間に挟まれることにより吸気側ロッカアーム４１…の倒れが防止される。また各排気弁２６…が配置される側の第１軸受部３３Ａ，３３…および仕切り壁３５ｆ…にも、排気側ロッカアーム４０…側に突出した突部４６…がそれぞれ設けられており、それらの突部４６…間に挟まれることにより排気側ロッカアーム４０…の倒れが防止される。
【００１７】
各排気側ロッカアーム４０…の中間部には、第１カムシャフト３１と平行な軸線の支軸４７を介してローラ４８が回転自在に軸支され、また各吸気側ロッカアーム４１の中間部には、第２カムシャフト３２と平行な軸線の支軸４９を介してローラ５０が回転自在に軸支される。前記ローラ４８…，５０…は、第１および第２カムシャフト３１，３２に設けられた動弁カム３１ａ…，３２ａ…にそれぞれ転がり接触する。
【００１８】
複数の第２軸受部３４Ａ，３４…のうち気筒配列方向１６に沿う一端側に配置された一端側第２軸受部３４Ａから突出した部分で第２カムシャフト３２にはヘリカルギヤである第１被動ギヤ５２が設けられ、複数の第１軸受部３３Ａ，３３…のうち気筒配列方向１６に沿う一端側に配置された一端側第１軸受部３３Ａから突出した部分で第１カムシャフト３１には、第１被動ギヤ５２に噛合するヘリカルギヤであって第１被動ギヤ５２との噛合部よりも一端側第１軸受部３３Ａ側に突出した円筒状の突出部５８ａを有する第１駆動ギヤ５１と、第１駆動ギヤ５１に関して一端側第１軸受部３３Ａとは反対側に配置されるとともにカムチェーン５４が巻き掛けられる動力入力部としてのスプロケット５３とが固定される。
【００１９】
第１および第２カムシャフト３１，３２の一端部は、シリンダヘッド１１を含むエンジン本体１０と、該エンジン本体１０に結合されるチェーンケース５５との間に形成されるチェーン室５６に配置されるものであり、図示しないクランクシャフトからの動力を伝達するようにしてチェーン室５６内を走行するカムチェーン５４がスプロケット５３に巻き掛けられる。
【００２０】
第１駆動ギヤ５１は、フリクションゴム５７を相互間に介装せしめた第１および第２ギヤ５８，５９をせらし構造で組み合わせて成るものである。第１ギヤ５８は、第１カムシャフト３１を同軸に囲繞する円筒状の突出部５８ａ，５８ｂを軸方向両側に一体に有しており、これらの突出部５８ａ，５８ｂは、第１カムシャフト３１に設けられた環状の段部３１ａおよびスプロケット５３間に挟まれ、スプロケット５３に係合するボルト６０が第１カムシャフト３１に同軸に螺合される。しかも第１ギヤ５８およびスプロケット５３の内周および第１カムシャフト３１の外周間にはキー６１が挿入されており、ボルト６０およびキー６１により、第１駆動ギヤ５１およびスプロケット５３が第１カムシャフト３１に固定される。
【００２１】
ところで、第１駆動ギヤ５１および第１被動ギヤ５２の噛合部よりも一端側第１軸受部３３Ａ側に突出した突出部５８ａが第１ギヤ５８に一体に設けられるのは、第１および第２ギヤ５８，５９間を経て第１被動ギヤ５２との噛合部に潤滑油を導くための油路６２を、ボルト６０の第１カムシャフト３１への螺合部を避けて第１カムシャフト３１の外面との間に形成するためであり、第１カムシャフト３１内には、一端側第１軸受部３３Ａに対応する部分でロアカムホルダ３５に設けられたオイル供給路６３および前記油路６２間を結ぶ油路６４が同軸に形成される。
【００２２】
図３で明示するように、前記一端側第１軸受部３３Ａは、前記一端側第２軸受部３４Ａに対して第１駆動ギヤ５１から遠ざかる側にオフセットして配置されている。
【００２３】
しかも第１カムシャフト３１に対応する両排気弁口１５Ａ，１５Ｂのうち一端側第１軸受部３３Ａ寄りの排気弁口１５Ａは、第２カムシャフト３２に対応する両吸気弁口１４Ａ，１４Ｂのうち一端側第２軸受部３４Ａよりの吸気弁口１４Ａよりも第１駆動ギヤ５１とは反対側にオフセットして配置される。
【００２４】
ところで、第２カムシャフト３２に対応する側でシリンダヘッド１１に設けられる一対の吸気弁口１４Ａ，１４Ｂのうち、一端側第２軸受部３４Ａに近い側に配置される吸気弁口１４Ａに連なってシリンダヘッド１１に設けられる吸気ポート１７Ａは燃焼室１３内にスワールを生じさせる形状に形成されている。
【００２５】
また一端側第１軸受部３３Ａに隣接する排気側ロッカアーム４０および前記一端側第１軸受部３３Ａ間の間隔は一端側第２軸受部３４Ａに隣接する吸気側ロッカアーム４１および一端側第２軸受部３４Ａ間の間隔よりも狭く設定される。
【００２６】
さらに一端側第１軸受部３３Ａの第１駆動ギヤ５１側の側面は、ロアカムホルダ３５およびアッパカムホルダ３６…をシリンダヘッド１１に締結する複数のボルト３８…のうち一端側第１軸受部３３Ａに対応する部分のボルト３８を挿通すべく一端側第１軸受部３３Ａに設けられた一対のボス部６５，６５よりも第１カムシャフト３１の軸方向内方に配置されている。
【００２７】
図５〜図８を併せて参照して、第１カムシャフト３１の他端部にはヘリカルギヤである第２駆動ギヤ６８が設けられ、ヘリカルギヤである第２被動ギヤ６９が、エンジン本体１０におけるシリンダヘッド１１に取付けられた補機としての高圧燃料ポンプ７０に連なる補機駆動軸７１に設けられる。第２駆動ギヤ６８は、フリクションゴム７２を相互間に介装せしめた第３および第４ギヤ７３，７４をせらし構造で組み合わせて成るものである。
【００２８】
補機駆動軸７１は、シリンダヘッド１１とは別体の軸受部材７５を３本のボルト７７，７８，７９…でシリンダヘッド１１に締結することで構成される軸受部７６で回転自在に支承されており、高圧燃料ポンプ７０が備える回転軸７０ａにオルダムジョイント８０を介して連結されている。
【００２９】
ところで、補機駆動軸７１の軸線は、第１および第２カムシャフト３１、３２の軸線を結ぶ直線Ｌよりもシリンダヘッド１１側に配置されており、前記軸受部７６は、シリンダ軸線に沿う方向から見て第２駆動ギヤ６８に一部が重なる位置でシリンダヘッド１１に設けられ、第２駆動ギヤ６８との干渉を避ける切欠き７５ａが軸受部７６における軸受部材７５に形成されている。
【００３０】
軸受部７６を構成する軸受部材７５をシリンダヘッド１１に締結する３本のボルト７７，７８，７９のうち、２本のボルト７７，７８は、シリンダ軸線に沿う方向から見て第２駆動ギヤ６８とは重ならない位置で補機駆動軸７１の両側に配置されるのに対し、残余のボルト７９は、軸受部材７５のシリンダヘッド１１への締結剛性を高めるために、シリンダ軸線に沿う方向から見て第２駆動ギヤ６８に一部が重なる位置で前記軸受部材６５をシリンダヘッド１１に締結するように配置される。
【００３１】
しかも前記各ボルト７７〜７９のうちの一部である２本のボルト７７，７８の頂面を通って第１および第２カムシャフト３１，３２の軸線と平行な第１仮想平面Ｐ１と、前記残余のボルト７９の頂面を通って第１仮想平面Ｐ１と平行な第２仮想平面Ｐ２との間に、第２駆動ギヤ６８の外周面のうち前記残余のボルト７９に対向する部分が配置されており、前記切欠き７５ａは、前記残余のボルト７９の第２駆動ギヤ６８との干渉を避け得るようにして軸受部７６の軸受部材７５に形成されている。
【００３２】
ところで、第１および第２カムシャフト３１，３２の一端側で相互に噛合する第１駆動ギヤ５１および第１被動ギヤ５２はヘリカルギヤであり、高圧燃料ポンプ７０を駆動するために第１カムシャフト３１の他端部に設けられた第２駆動ギヤ６８ならびに第２駆動ギヤ６８に噛合するようにして補機駆動軸７１に設けられた第２被動ギヤ６９もヘリカルギヤであり、第１および第１被動ギヤ５１，５２の噛合により図５の矢印８１で示すように第１カムシャフト３１に生じるスラスト力と、第２駆動ギヤ６８および第２被動ギヤ６９の噛合によって図５の矢印８２で示すように第１カムシャフト３１に生じるスラスト力とが、相互に逆向きとなるように設定される。
【００３３】
また図６および図７で明示するように、シリンダヘッド１１には第２被動ギヤ６９の一部を収容する凹部８３が設けられており、それによってシリンダ軸線に沿う方向での第１カムシャフト３１の高さを極力低くしてエンジンのコンパクト化に寄与することができる。しかも凹部８３内に溜まったオイルを第２被動ギヤ６９が掻き揚げることにより、第２駆動ギヤ６８および第２被動ギヤ６９の噛合部を潤滑することができる。
【００３４】
次にこの実施例の作用について説明すると、気筒配列方向１６に間隔をあけた位置で前記各カムシャフト３１，３２毎にシリンダヘッド１１に設けられた複数の第２軸受部３４Ａ，３４…のうち前記気筒配列方向１６に沿う一端側に配置された一端側第２軸受部３４Ａから突出した部分で第２カムシャフト３２には第１被動ギヤ５２が設けられ、気筒配列方向１６に間隔をあけた位置で前記各カムシャフト毎にシリンダヘッド１１に設けられた複数の第１軸受部３３Ａ，３３…のうち前記気筒配列方向１６に沿う一端側に配置された一端側第１軸受部３３Ａから突出した部分で第１カムシャフト３１には、第１被動ギヤ５２に噛合するとともに前記被動ギヤ５２との噛合部よりも一端側第１軸受部３３Ａ側に突出した円筒状の突出部５８ａを有する第１駆動ギヤ５１が固定されており、一端側第１軸受部３３Ａが、一端側第２軸受部３４Ａよりも第１駆動ギヤ５１から遠ざかる側にオフセットして配置されている。
【００３５】
したがって一端側第１軸受部３３Ａの一端側第２軸受部３４Ａに対するオフセット配置にともなって生じたスペースに突出部５８ａを配置することで、第１駆動ギヤ５１および第１被動ギヤ５２をよりシリンダヘッド１１側に近接させることができ、エンジンのコンパクト化を図ることができる。
【００３６】
しかも第１駆動ギヤ５１に関して一端側第１軸受部３３Ａとは反対側で第１カムシャフト３１にはクランクシャフトからの動力を入力するためのスプロケット５３が固定されており、スプロケット５３をよりシリンダヘッド１１側に近接させて、両カムシャフト３１，３２の軸線に沿う方向でエンジンをより一層コンパクト化することができる。またクランクシャフトからの動力が直接入力されない吸気弁２０…側の第２カムシャフト３２に設けられた第１被動ギヤ５２を一端側第２軸受部３４Ａに近接させることで、第２カムシャフト３２のトルク変動を抑制することができる。
【００３７】
また燃焼室１３に開口する吸気弁口１４Ａ，１４Ｂおよび排気弁口１５Ａ，１５Ｂが、前記両カムシャフト３１，３２の軸線に沿う方向に並んで各気筒Ｃ１〜Ｃ４毎に一対ずつシリンダヘッド１１に設けられ、第１カムシャフト３１に対応する両排気弁口１５Ａ，１５Ｂのうち一端側第１軸受部３３Ａ寄りの排気弁口１５Ａが、第２カムシャフト３２に対応する両吸気弁口１４Ａ，１４Ｂのうち一端側第２軸受部３４Ａ寄りの吸気弁口１４Ａよりも第１駆動ギヤ５１とは反対側にオフセットして配置されるので、一端側第２軸受部３４Ａに対する一端側第１軸受部３３Ａのオフセットに応じて、吸気弁口１４Ａおよび排気弁口１５Ａ相互のオフセットを行なうことにより、エンジンをカムシャフト３１，３２の軸線方向でより一層コンパクト化することができる。
【００３８】
しかも第１カムシャフト３１に対応する側でシリンダヘッド１１に一対の排気弁口１５Ａ，１５Ｂが設けられ、第２カムシャフト３２に対応する側でシリンダヘッド１１に設けられる一対の吸気弁口１４Ａ，１４Ｂのうち、一端側第２軸受部３４Ａに近い側に配置される吸気弁口１４Ａに連なってシリンダヘッド１１に設けられる吸気ポート１７Ａが燃焼室１３内にスワールを生じさせる形状に形成されており、上述の吸気弁口１４Ａおよび排気弁口１５Ａ相互のオフセットと相まって燃焼室１３にスワールを効果的に形成して燃焼効率を向上することができる。
【００３９】
また第１および第２カムシャフト３１，３２の軸線と直交する平面内での揺動を可能として一端がシリンダヘッド１１にピボット支持される複数の排気側および吸気側ロッカアーム４０…，４１…の他端が排気弁２６…および吸気弁２０…にそれぞれ連動、連結され、前記各第１および第２軸受部３３Ａ，３３…；３４Ａ，３４…は、前記排気側および吸気側ロッカアーム４０…，４１…の両側に配置されて前記各ロッカアーム４０…，４１…の倒れを防止する突部４６…を有してシリンダヘッド１１に締結されるロアカムホルダ３５と、該ロアカムホルダ３５に締結される複数の排気側および吸気側のアッパカムホルダ３６…，３７…とで構成され、一端側第１軸受部３３Ａに隣接する排気側ロッカアーム４０および前記一端側第１軸受部３３Ａ間の間隔が、一端側第２軸受部３４Ａに隣接する吸気側ロッカアーム４１および前記一端側第２軸受部３４Ａ間の間隔よりも狭く設定されている。このため、一端側第１軸受部３３Ａを排気側ロッカアーム４０に近接させることにより、一端側第１軸受部３３Ａに対応する部分でロアカムホルダ３５に設けられる突部４６の突出量を小さくし、ロアカムホルダ３５の軽量化ひいてはエンジン全体の軽量化を図ることができる。
【００４０】
さらに一端側第１軸受部３３Ａの第１駆動ギヤ５１側の側面は、前記ロアカムホルダ３５および排気側のアッパカムホルダ３６…をシリンダヘッド１１に締結する複数のボルト３８…のうち一端側第１軸受部３３Ａに対応する部分のボルト３８…を挿通すべく一端側第１軸受部３３Ａに設けられた一対のボス部６５…よりも第１カムシャフト３１の軸方向内方に配置されるので、一端側第１軸受部３３Ａの一端側第２軸受部３４Ａに対するオフセット量を比較的大きくし、エンジンをより一層コンパクト化することができる。
【００４１】
さらに第１カムシャフト３１の他端部に設けられた第２駆動ギヤ６８に噛合する第２被動ギヤ６９が、エンジン本体１０のシリンダヘッド１１に取付けられた高圧燃料ポンプ７０に連なる補機駆動軸７１に設けられ、第１および第２カムシャフト３１，３２の軸線を結ぶ直線Ｌよりもシリンダヘッド１１側で両カムシャフト３１，３２間に補機駆動軸７１の軸線が配置されている。
【００４２】
したがって第１および第２カムシャフト３１，３２間の間隔を拡げることなく、補機駆動軸７０を第１カムシャフト３１に近接させて、シリンダ軸線に沿う方向でエンジンのコンパクト化を図ることができる。
【００４３】
また補機駆動軸７１を支承する軸受部７６が、シリンダ軸線に沿う方向から見て第２駆動ギヤ６８に一部が重なる位置でシリンダヘッド１１に設けられ、第２駆動ギヤ６８との干渉を避ける切欠き７５ａが軸受部７６に形成されているので、補機駆動軸７１を支承する軸受部７６を、シリンダ軸線に沿う方向でのカムシャフト３１，３２の位置が高くなることを回避しつつ、第１カムシャフト３１の軸線に沿う方向で第２駆動ギヤ６８に近接配置することができ、これによってもエンジンのコンパクト化に寄与することができる。
【００４４】
ところで、軸受部７６は補機駆動軸７１を回転自在に支承する軸受部材７５を３本のボルト７７，７８，７９でシリンダヘッド１１に締結することにより構成されるものであり、３本のボルト７７〜７９のうち２本のボルト７７，７８は、シリンダ軸線に沿う方向から見て第２駆動ギヤ６８とは重ならない位置で補機駆動軸７１の両側に配置されるのに対し、残余のボルト７９は、軸受部材７５のシリンダヘッド１１への締結剛性を高めるために、シリンダ軸線に沿う方向から見て第２駆動ギヤ６８に一部が重なる位置で前記軸受部材６５をシリンダヘッド１１に締結するように配置される。
【００４５】
しかも前記各ボルト７７〜７９のうちの一部である２本のボルト７７，７８の頂面を通って第１および第２カムシャフト３１，３２の軸線と平行な第１仮想平面Ｐ１と、前記残余のボルト７９の頂面を通って第１仮想平面Ｐ１と平行な第２仮想平面Ｐ２との間に、第２駆動ギヤ６８の外周面のうち前記残余のボルト７９に対向する部分が配置されている。
【００４６】
したがって第１および第２カムシャフト３１，３２間の間隔を拡げることなく、補機駆動軸７１を両カムシャフト３１，３２の一方である第１カムシャフト３１に近接させることができるとともに、軸受部材７５をシリンダ軸線に沿う方向でのカムシャフトの位置が高くなることを回避しつつカムシャフト３１，３２の軸線に沿う方向で第２駆動ギヤ６８に近接配置することができ、これによってもエンジンのコンパクト化に寄与することができる。
【００４７】
さらに第１および第２カムシャフト３１，３２の一端部に設けられて相互に噛合する第１駆動ギヤ５１および第１被動ギヤ５２がヘリカルギヤであり、第１駆動ギヤ５１および第１被動ギヤ５２の噛合により第１カムシャフト３１に生じるスラスト力と、ヘリカルギヤである第２駆動ギヤ６８および第２被動ギヤ６９の噛合によって第１カムシャフト３１に生じるスラスト力とが相互に逆向きに設定されるので、第１および第２カムシャフト３１，３２の一端部に設けられる第１駆動ギヤ５１および第１被動ギヤ５２や、高圧燃料ポンプ７０を駆動するための第２駆動ギヤ６８および第２被動ギヤ６９の耐久性を向上することができる。
【００４８】
以上、本発明の実施例を説明したが、本発明は上記実施例に限定されるものではなく、特許請求の範囲に記載された本発明を逸脱することなく種々の設計変更を行うことが可能である。
【００４９】
たとえば上記実施例では、補機である高圧燃料ポンプ７０がシリンダヘッド１１に取付けられていたが、エンジン本体１０のシリンダヘッド１１以外の部分たとえばシリンダブロック１２に補機が取付けられていてもよく、その場合、補機駆動軸７１の軸線が両カムシャフト３１，３２の軸線を結ぶ直線Ｌよりもシリンダヘッド１１側で両カムシャフト３１，３２間に配置されていればよい。
【００５０】
また本発明を、たとえばクランクシャフトの軸線を鉛直方向とした船外機などのような船舶推進機用エンジンにも適用することも可能である。
【００５１】
【発明の効果】
以上のように本発明によれば、一対のカムシャフト間の間隔を拡げることなく、補機駆動軸を両カムシャフトの一方に近接させて、シリンダ軸線に沿う方向でエンジンのコンパクト化を図ることができる。しかも被動ギヤの一部を収容する凹部がシリンダヘッドに設けられることによってシリンダ軸線に沿う方向でのカムシャフトの高さを極力低くしてエンジンのコンパクト化に寄与することができ、また凹部内に溜まったオイルを被動ギヤが掻き揚げることにより、駆動ギヤおよび被動ギヤの噛合部を潤滑することができる。しかも補機駆動軸を支承する軸受部材を、それのシリンダ軸線に沿う方向でのカムシャフトの位置が高くなることを回避しつつ、カムシャフトの軸線に沿う方向で駆動ギヤに近接配置することができ、エンジンのコンパクト化に寄与することができる。
【図面の簡単な説明】
【図１】エンジンの一部縦断面図であって図３の１−１線に沿う断面図
【図２】ヘッドカバーを外した状態での図１の２−２線矢視図
【図３】図２の３矢示部拡大図
【図４】図１の４ー４線断面図
【図５】図２の５矢示部拡大図
【図６】図５の６−６線拡大断面図
【図７】図６の７−７線断面図
【図８】図７の８−８線断面図
【符号の説明】
１０・・・エンジン本体
１１・・・シリンダヘッド
３１・・・第１カムシャフト
３２・・・第２カムシャフト
５３・・・動力入力部としてのスプロケット
６８・・・駆動ギヤ
６９・・・被動ギヤ
７０・・・補機としての高圧燃料ポンプ
７１・・・補機駆動軸
７５・・・軸受部材
７５ａ・・切欠き
７６・・・軸受部
７７，７８，７９・・ボルト
Ｌ・・・・直線
Ｐ１・・・第１仮想平面
Ｐ２・・・第２仮想平面[0001]
BACKGROUND OF THE INVENTION
 In the present invention, a first camshaft having a power input portion at one end and a second camshaft linked to and connected to the first camshaft at one end rotate with respect to the cylinder head with mutually parallel axes. A driven gear that is freely supported and meshes with a drive gear provided at one of the other ends of the first and second camshafts is connected to an accessory drive shaft connected to an accessory attached to the engine body including the cylinder head. It relates to the engine provided.
[0002]
[Prior art]
 An engine in which a drive gear provided on a camshaft is engaged with a driven gear provided on an accessory drive shaft connected to a vacuum pump and a hydraulic pump is known, for example, in Japanese Patent Application Laid-Open No. 8-261001.
[0003]
[Problems to be solved by the invention]
 The conventional one is an SOHC type engine having a single camshaft. However, when an auxiliary drive structure similar to the conventional one is applied to an engine having a pair of camshafts, a pair of camshafts is used. It is desirable to construct a structure for driving the auxiliary machine so that the engine can be made as compact as possible while avoiding interference with the engine.
[0004]
 The present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine that can be made compact when an auxiliary machine is driven by a camshaft.
[0005]
[Means for Solving the Problems]
 In order to achieve the above object, according to the first aspect of the present invention, there is provided a first camshaft having a power input portion at one end, and a second camshaft whose one end portion is linked and connected to the first camshaft. An engine main body including a cylinder head, and a driven gear that is rotatably supported by the cylinder head having an axis parallel to the shaft and meshes with a drive gear provided at one other end of the first and second camshafts.One end portion in a direction along the axisIn the engine provided on the accessory drive shaft connected to the accessory mounted on the cylinder, the axis of the accessory drive shaft is between the camshafts on the cylinder head side with respect to the straight line connecting the axes of the first and second camshafts. The cylinder head has a recess for accommodating a part of the driven gear, and the driven gear lifts up oil accumulated in the recess to lubricate the meshing portion of the drive gear and the driven gear. Is provided so thatA part of the bearing member is located at a position where the bearing member, which is disposed adjacent to the side surface on the auxiliary machine side of the driven gear and supports the auxiliary machine drive shaft, overlaps the drive gear when viewed from the direction along the cylinder axis. The bottom surface is fastened to the cylinder head in such a manner that a notch that avoids interference with the drive gear is formed on the side surface of the bearing member opposite to the auxiliary machine.It is characterized by.
[0006]
 Further claims2The described inventionA first camshaft having a power input portion at one end and a second camshaft whose one end portion is linked and connected to the first camshaft are rotatably supported by the cylinder head with mutually parallel axes. The driven gear meshing with the drive gear provided at one other end of the first and second camshafts is connected to an auxiliary machine attached to one end in the direction along the axis of the engine body including the cylinder head. In the engine provided on the accessory drive shaft, the axis of the accessory drive shaft is disposed between the camshafts on the cylinder head side with respect to the straight line connecting the axes of the first and second camshafts. The recessed portion that houses a part of the driven gear can lubricate the meshing portion of the drive gear and the driven gear by the driven gear scooping up the oil accumulated in the recessed portion. It provided Te Unishi, the driven gear, adjacent to the side surface of the auxiliary sideA bearing member disposed to support the accessory drive shaft;A part of the bearing member is arranged at a position overlapping the drive gear when viewed from the direction along the cylinder axis,To cylinder head with multiple boltsFasten the bottomAnd saidpluralAvoid positions where some of the bolts overlap the drive gear when viewed from the direction along the cylinder axis.On both sides of the auxiliary drive shaftA first imaginary plane that is disposed at a position where the remaining bolts overlap with the drive gear when viewed from the direction along the cylinder axis, and is parallel to the axis of the two camshafts through the top surfaces of the bolts. And a portion of the outer peripheral surface of the drive gear that faces the remaining bolt is disposed between the second virtual plane parallel to the first virtual plane through the top surface of the remaining bolt. Characterized by.
[0007]
 Such claims1,2 describedEach featureAccording to the above, the auxiliary machine drive shaft is brought close to one of the camshafts without increasing the distance between the pair of camshafts.Thus, the engine can be made compact in the direction along the cylinder axis. In addition, by providing the cylinder head with a recess that accommodates part of the driven gear, the camshaft height in the direction along the cylinder axis can be reduced as much as possible, contributing to the downsizing of the engine. When the driven gear lifts up the accumulated oil, the meshing portion of the drive gear and the driven gear can be lubricated. AlsoThe bearing member that supports the accessory drive shaft can be disposed close to the drive gear in the direction along the camshaft axis while avoiding an increase in the position of the camshaft in the direction along the cylinder axis. Can contribute to downsizing.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
 Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.
[0009]
 1 to 8 show an embodiment of the present invention. FIG. 1 is a partial longitudinal sectional view of an engine, and is a sectional view taken along line 1-1 of FIG. 3, and FIG. 2 is a head cover removed. FIG. 3 is a sectional view taken along the line 2-2 in FIG. 1, FIG. 3 is an enlarged view taken along the line 3-4 in FIG. 2, FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. 5, FIG. 7 is a sectional view taken along line 7-7 in FIG. 6, and FIG. 8 is a sectional view taken along line 8-8 in FIG.
[0010]
 1 and 2, this engine is a compression ignition type DOHC type in-line four-cylinder engine. Between a cylinder head 11 and a cylinder block 12 constituting a part of the engine body 10, the top of a piston (not shown) is provided. Is formed in each of the first to fourth cylinders C1, C2, C3, and C4, and intake valve ports 14A and 14B and exhaust valve ports 15A and 15B that open to the respective combustion chambers 13 are cylinders. A pair of each of the cylinders C1 to C4 arranged in the direction along the arrangement direction 16 is provided in the cylinder head 11, and a pair of intake ports 17A, 17B and both exhaust valve ports that can communicate with both the intake valve ports 14A, 14B. A pair of exhaust ports 18A, 18B that can communicate with 15A, 15B are provided in the cylinder head 11 and face the center of each combustion chamber 13. Unishi fuel injection valve (not shown) Te is attached to the cylinder head 11.
[0011]
 An intake valve 20 that can open and close each intake valve port 14A, 14B is slidably fitted to a guide cylinder 21 provided in the cylinder head 11, and the upper end of each intake valve 20 is connected to the cylinder head 11 and the cylinder. A guide chamber 21 is formed in a valve operating chamber 25 formed between the head covers 24 coupled to the head 11 and is provided between a retainer 22 provided at the upper end of each intake valve 20 and the cylinder head 11. The intake valves 20 are biased in the valve closing direction by the valve springs 23. Further, exhaust valves 26 that can open and close the exhaust valve ports 15A and 15B are slidably fitted into guide cylinders 27 provided in the cylinder head 11, and the upper ends of the exhaust valves 26 are in the valve chamber 25. Each of the exhaust valves 26 is urged in the valve closing direction by a retainer 28 provided at the upper end of each exhaust valve 26 and a valve spring 29 provided between the cylinder heads 11. Is done.
[0012]
 First and second camshafts 31 and 32 having axes parallel to each other along the cylinder arrangement direction 16 are provided on the cylinder head 11 for each camshaft at a position spaced from each other in the cylinder arrangement direction 16. The first and second bearing portions 33A, 33 ..., 34A, 34 ... are rotatably supported by the first and second bearing portions 33A, 33 ..., and the second bearing portions 34A, 34 ... The lower cam holder 35 fastened to the cylinder head 11 and a plurality of exhaust side and intake side upper cam holders 36, 37... Fastened to the lower cam holder 35. The upper cam holders 36, 37. At the same time, the cylinder head 11 is fastened by a plurality of bolts 38.
[0013]
 Referring also to FIG. 3, the lower cam holder 35 is disposed inside the pair of outer vertical frames 35 a and 35 b extending along the cylinder arrangement direction 16 and the outer vertical frames 35 a and 35 b and extends along the cylinder arrangement direction 16. And a pair of inner vertical frames 35c, 35d that are integrally formed, and is formed between the outer vertical frame 35a and the inner vertical frame 35c on the side where the exhaust valves 26 are arranged. The five lower bearing portions 35d that receive the lower half of the first camshaft 31 are provided so as to sandwich the cylinders C1 to C4 from both sides, and cooperate with the lower bearing portions 35d to form the first bearing portion 33A. , 33... Are configured to be fastened to the lower cam holder 35. Further, between the outer vertical frame 35b and the inner vertical frame 35d on the side where the intake valves 20 are arranged, five lower bearing portions 35e that receive the lower half of the second camshaft 32 are cylinders C1 to C4. Are arranged on both sides, and the intake side upper cam holders 37 are fastened to the lower cam holder 35 so as to form the second bearing portions 34A, 34... In cooperation with the lower bearing portions 35e.
[0014]
 Between the plurality of first bearing portions 33A, 33..., The outer vertical frame 35a and the inner vertical frame 35c on the side where the exhaust valves 26 are arranged are connected by a partition wall 35f. Between the bearing portions 34A, 34..., The outer vertical frame 35b and the inner vertical frame 35d on the side where the intake valves 20 are arranged are connected by a partition wall 35g.
[0015]
 Between the first bearing portions 33A, 33,... And the partition wall 35f on the side where the exhaust valves 26 are arranged, one end can be hydraulically oscillated within a plane perpendicular to the axis of the first camshaft 31. Exhaust-side rocker arms 40 pivotally supported by the cylinder head 11 via tappets 42 are arranged, and the other ends of the respective exhaust-side rocker arms 40 are in contact with the upper ends of the respective exhaust valves 26. 26 and so on. Further, between the second bearing portions 34A, 34,... On the side where the intake valves 20 are arranged and the partition wall 35g, one end is allowed to swing within a plane perpendicular to the axis of the second camshaft 32. An intake side rocker arm 41 pivotally supported by the cylinder head 11 via a hydraulic tappet 43 is arranged, and the other end of each intake side rocker arm 41 is in contact with the upper end of each intake valve 20. Interlocked and connected to the valve 20.
[0016]
 Referring to FIG. 4 as well, the second bearing portions 34A, 34,... And the partition walls 35g on the side where the intake valves 20 are disposed have protrusions 46 protruding toward the intake side rocker arm 41. Each of them is provided, and the intake side rocker arms 41 are prevented from falling by being sandwiched between the protrusions 46. Further, the first bearing portions 33A, 33,... And the partition wall 35f on the side where the exhaust valves 26 are arranged are also provided with protrusions 46 protruding toward the exhaust side rocker arm 40, respectively. The exhaust-side rocker arms 40 are prevented from falling by being sandwiched between the protrusions 46.
[0017]
 A roller 48 is rotatably supported by an intermediate portion of each exhaust-side rocker arm 40 through a support shaft 47 having an axis parallel to the first camshaft 31, and an intermediate portion of each intake-side rocker arm 41 has an intermediate portion. A roller 50 is rotatably supported via a support shaft 49 having an axis parallel to the second camshaft 32. The rollers 48, 50, ... are in rolling contact with the valve cams 31a, 32a provided on the first and second camshafts 31, 32, respectively.
[0018]
 A first driven gear which is a helical gear on the second camshaft 32 at a portion protruding from one end side second bearing portion 34A disposed on one end side along the cylinder arrangement direction 16 among the plurality of second bearing portions 34A, 34. 52, and the first camshaft 31 includes a first camshaft 31 that protrudes from one end side first bearing portion 33A disposed on one end side along the cylinder arrangement direction 16 among the plurality of first bearing portions 33A, 33. A first drive gear 51 having a cylindrical projection 58a which is a helical gear meshing with the first driven gear 52 and projecting toward the first bearing portion 33A side from the meshing portion with the first driven gear 52; A sprocket 53 serving as a power input portion around which the cam chain 54 is wound is fixed while being arranged on the opposite side to the first bearing portion 33A on the one end side with respect to the drive gear 51.
[0019]
 One end portions of the first and second camshafts 31 and 32 are disposed in a chain chamber 56 formed between the engine body 10 including the cylinder head 11 and a chain case 55 coupled to the engine body 10. The cam chain 54 that travels in the chain chamber 56 is wound around the sprocket 53 so as to transmit power from a crankshaft (not shown).
[0020]
 The first drive gear 51 is formed by combining first and second gears 58 and 59 having a friction rubber 57 interposed therebetween in a slender structure. The first gear 58 has cylindrical protrusions 58 a and 58 b that coaxially surround the first camshaft 31 on both sides in the axial direction, and these protrusions 58 a and 58 b are integrated with the first camshaft 31. A bolt 60 that is sandwiched between an annular step portion 31 a provided on the sprocket 53 and the sprocket 53 and engages with the sprocket 53 is screwed coaxially with the first camshaft 31. In addition, a key 61 is inserted between the inner periphery of the first gear 58 and the sprocket 53 and the outer periphery of the first camshaft 31, and the first drive gear 51 and the sprocket 53 are connected to the first camshaft by the bolt 60 and the key 61. 31 is fixed.
[0021]
 By the way, the first and second protrusions 58a that protrude toward the one end side first bearing portion 33A from the meshing portion of the first drive gear 51 and the first driven gear 52 are provided integrally with the first gear 58. An oil passage 62 for guiding the lubricating oil to the meshing portion with the first driven gear 52 via the gears 58 and 59 is avoided, and the screw portion of the bolt 60 with respect to the first camshaft 31 is avoided. This is because the oil supply passage 63 and the oil passage 62 provided in the lower cam holder 35 are connected to each other in the first camshaft 31 at a portion corresponding to the first bearing portion 33A on the one end side. An oil passage 64 is formed coaxially.
[0022]
 As clearly shown in FIG. 3, the one end side first bearing portion 33 A is arranged offset to the side away from the first drive gear 51 with respect to the one end side second bearing portion 34 A.
[0023]
 Moreover, the exhaust valve port 15A near the first bearing portion 33A among the both exhaust valve ports 15A and 15B corresponding to the first camshaft 31 is out of the both intake valve ports 14A and 14B corresponding to the second camshaft 32. The intake valve port 14A from the one end side second bearing portion 34A is offset from the first drive gear 51 on the opposite side.
[0024]
 By the way, of the pair of intake valve ports 14A and 14B provided in the cylinder head 11 on the side corresponding to the second camshaft 32, the intake valve port 14A is arranged on the side closer to the one end side second bearing portion 34A. The intake port 17 A provided in the cylinder head 11 is formed in a shape that generates a swirl in the combustion chamber 13.
[0025]
 Further, the distance between the exhaust side rocker arm 40 adjacent to the one end side first bearing portion 33A and the one end side first bearing portion 33A is the same as the intake side rocker arm 41 and the one end side second bearing portion 34A adjacent to the one end side second bearing portion 34A. It is set narrower than the interval between them.
[0026]
 Further, the side surface on the first drive gear 51 side of the one end side first bearing portion 33A corresponds to the one end side first bearing portion 33A among the plurality of bolts 38 for fastening the lower cam holder 35 and the upper cam holder 36 to the cylinder head 11. The first camshaft 31 is disposed inward in the axial direction from the pair of boss portions 65, 65 provided in the first bearing portion 33A on one end side so that the bolt 38 of the portion to be inserted can be inserted.
[0027]
 Referring also to FIGS. 5 to 8, a second drive gear 68 that is a helical gear is provided at the other end of the first camshaft 31, and a second driven gear 69 that is a helical gear is connected to a cylinder in the engine body 10. An auxiliary machine drive shaft 71 connected to a high-pressure fuel pump 70 as an auxiliary machine attached to the head 11 is provided. The second drive gear 68 is formed by combining third and fourth gears 73 and 74 having a friction rubber 72 interposed therebetween in a slender structure.
[0028]
 The auxiliary machine drive shaft 71 is rotatably supported by a bearing portion 76 formed by fastening a bearing member 75 separate from the cylinder head 11 to the cylinder head 11 with three bolts 77, 78, 79. The high-pressure fuel pump 70 is connected to a rotating shaft 70 a via an Oldham joint 80.
[0029]
 By the way, the axis line of the accessory drive shaft 71 is disposed on the cylinder head 11 side with respect to the straight line L connecting the axis lines of the first and second camshafts 31 and 32, and the bearing portion 76 is in the direction along the cylinder axis line. A notch 75 a is formed in the bearing member 75 in the bearing portion 76 so as to avoid interference with the second drive gear 68. The notch 75 a is provided in the cylinder head 11 at a position partially overlapping the second drive gear 68.
[0030]
 Of the three bolts 77, 78, 79 that fasten the bearing member 75 constituting the bearing portion 76 to the cylinder head 11, the two bolts 77, 78 are the second drive gear 68 as viewed from the direction along the cylinder axis. The remaining bolts 79 are arranged on both sides of the accessory drive shaft 71 at positions that do not overlap with each other, whereas the remaining bolts 79 are viewed from the direction along the cylinder axis in order to increase the fastening rigidity of the bearing member 75 to the cylinder head 11. Thus, the bearing member 65 is arranged to be fastened to the cylinder head 11 at a position partially overlapping the second drive gear 68.
[0031]
 In addition, the first virtual plane P1 parallel to the axes of the first and second camshafts 31 and 32 through the top surfaces of the two bolts 77 and 78 which are a part of the bolts 77 to 79, and A portion of the outer peripheral surface of the second drive gear 68 facing the remaining bolt 79 is disposed between the second virtual plane P2 parallel to the first virtual plane P1 through the top surface of the remaining bolt 79. The notch 75a is formed in the bearing member 75 of the bearing portion 76 so as to avoid interference of the remaining bolt 79 with the second drive gear 68.
[0032]
 Incidentally, the first drive gear 51 and the first driven gear 52 that mesh with each other on one end side of the first and second camshafts 31 and 32 are helical gears, and the first camshaft 31 is used to drive the high-pressure fuel pump 70. The second drive gear 68 provided on the other end of the second drive gear 68 and the second driven gear 69 provided on the accessory drive shaft 71 so as to mesh with the second drive gear 68 are also helical gears. As shown by the arrow 82 in FIG. 5, the thrust force generated in the first camshaft 31 as shown by the arrow 81 in FIG. 5 due to the engagement of the gears 51 and 52 and the engagement of the second drive gear 68 and the second driven gear 69. The thrust force generated in the first camshaft 31 is set to be opposite to each other.
[0033]
 As clearly shown in FIGS. 6 and 7, the cylinder head 11 is provided with a recess 83 that accommodates a part of the second driven gear 69, thereby the first camshaft 31 in the direction along the cylinder axis. Can be made as low as possible to contribute to making the engine more compact. In addition, when the second driven gear 69 lifts up the oil accumulated in the recess 83, the meshing portion of the second drive gear 68 and the second driven gear 69 can be lubricated.
[0034]
 Next, the operation of this embodiment will be described. Among the plurality of second bearing portions 34A, 34... Provided in the cylinder head 11 for each of the camshafts 31, 32 at positions spaced in the cylinder arrangement direction 16. A first driven gear 52 is provided on the second camshaft 32 at a portion protruding from one end side second bearing portion 34 A arranged on one end side along the cylinder arrangement direction 16, and is spaced from the cylinder arrangement direction 16. .. Of the plurality of first bearing portions 33A, 33... Provided on the cylinder head 11 for each camshaft at a position protruding from one end-side first bearing portion 33A disposed on one end side along the cylinder arrangement direction 16. The first camshaft 31 has a cylindrical protruding portion 58a that meshes with the first driven gear 52 and protrudes toward the first bearing portion 33A from the meshing portion with the driven gear 52. First and driving gear 51 is fixed to one end first bearing portion 33A are arranged to be offset to the side away from the first drive gear 51 than the end side second bearing section 34A.
[0035]
 Therefore, the first drive gear 51 and the first driven gear 52 can be made more cylinder heads by disposing the projecting portion 58a in the space generated by the offset arrangement of the one end side first bearing portion 33A with respect to the one end side second bearing portion 34A. The engine can be made compact.
[0036]
 Moreover, a sprocket 53 for inputting power from the crankshaft is fixed to the first camshaft 31 on the side opposite to the first bearing portion 33A on the one end side with respect to the first drive gear 51, and the sprocket 53 is further connected to the cylinder head. The engine can be made more compact in the direction along the axis of both camshafts 31 and 32 by being close to the 11 side. Further, the first driven gear 52 provided on the second camshaft 32 on the intake valve 20... Side where the power from the crankshaft is not directly inputted is brought close to the one end side second bearing portion 34 A. Torque fluctuation can be suppressed.
[0037]
 The intake valve ports 14A and 14B and the exhaust valve ports 15A and 15B that open to the combustion chamber 13 are arranged in a line along the axis of the camshafts 31 and 32 and are paired with the cylinder head 11 for each of the cylinders C1 to C4. Among the exhaust valve ports 15A and 15B corresponding to the first camshaft 31, the exhaust valve port 15A near the first bearing portion 33A on the one end side is both intake valve ports 14A and 14B corresponding to the second camshaft 32. Since the intake valve port 14A near the one end side second bearing portion 34A is offset to the opposite side to the first drive gear 51, the one end side first bearing portion 33A with respect to the one end side second bearing portion 34A is disposed. The engine is made more compact in the axial direction of the camshafts 31 and 32 by offsetting the intake valve port 14A and the exhaust valve port 15A in accordance with the offset of the camshafts 31 and 32. It can be.
[0038]
 Moreover, a pair of exhaust valve ports 15A and 15B are provided in the cylinder head 11 on the side corresponding to the first camshaft 31, and a pair of intake valve ports 14A and 14A provided on the cylinder head 11 on the side corresponding to the second camshaft 32. 14B, an intake port 17A provided in the cylinder head 11 connected to an intake valve port 14A disposed on the side closer to the one end side second bearing portion 34A is formed in a shape that generates a swirl in the combustion chamber 13. Combining with the offset between the intake valve port 14A and the exhaust valve port 15A described above, swirl can be effectively formed in the combustion chamber 13 to improve combustion efficiency.
[0039]
 In addition, a plurality of exhaust-side and intake-side rocker arms 40, 41, etc. whose one end is pivotally supported by the cylinder head 11 so as to be able to swing in a plane orthogonal to the axis of the first and second camshafts 31, 32. The ends of the first and second bearing portions 33A, 33 ...; 34A, 34 ... are connected to and connected to the exhaust valve 26 ... and the intake valve 20, respectively, and the exhaust side and intake side rocker arms 40 ..., 41 ... The lower cam holder 35 is fastened to the cylinder head 11 and has a protrusion 46 that prevents the rocker arms 40... 41 from falling over, and a plurality of exhaust sides fastened to the lower cam holder 35. The exhaust-side rocker arm 40 adjacent to the first end side first bearing portion 33A and the one end side first bearing portion. Spacing between 3A is set smaller than the interval between the intake-side rocker arm 41 and the one end side second bearing section 34A adjacent to one side second bearing portion 34A. For this reason, by bringing the one end side first bearing portion 33A close to the exhaust side rocker arm 40, the protrusion amount of the protrusion 46 provided on the lower cam holder 35 is reduced at the portion corresponding to the one end side first bearing portion 33A. Thus, the weight of the entire engine can be reduced.
[0040]
 Further, the side surface on the first drive gear 51 side of the one end side first bearing portion 33A is one end side first bearing among the plurality of bolts 38 for fastening the lower cam holder 35 and the exhaust side upper cam holder 36 to the cylinder head 11. The first camshaft 31 is disposed on the inner side in the axial direction than the pair of bosses 65 provided on the first bearing portion 33A to insert the bolts 38 corresponding to the portion 33A. The offset amount of the side first bearing portion 33A with respect to the one end side second bearing portion 34A can be made relatively large, and the engine can be made more compact.
[0041]
 Further, the second driven gear 69 meshing with the second drive gear 68 provided at the other end of the first camshaft 31 is an auxiliary machine drive shaft connected to the high pressure fuel pump 70 attached to the cylinder head 11 of the engine body 10. The axis of the accessory drive shaft 71 is disposed between the camshafts 31 and 32 on the cylinder head 11 side of the straight line L that is provided at 71 and connects the axes of the first and second camshafts 31 and 32.
[0042]
 Therefore, without increasing the distance between the first and second camshafts 31 and 32, the accessory drive shaft 70 can be brought close to the first camshaft 31 and the engine can be made compact in the direction along the cylinder axis. .
[0043]
 A bearing portion 76 that supports the accessory drive shaft 71 is provided in the cylinder head 11 at a position that partially overlaps the second drive gear 68 when viewed from the direction along the cylinder axis, and interferes with the second drive gear 68. Since the notch 75a to be avoided is formed in the bearing portion 76, the bearing portion 76 that supports the accessory drive shaft 71 avoids an increase in the position of the camshafts 31 and 32 in the direction along the cylinder axis. The second drive gear 68 can be disposed close to the first camshaft 31 in the direction along the axis of the first camshaft 31, and this can also contribute to the downsizing of the engine.
[0044]
 Incidentally, the bearing portion 76 is configured by fastening a bearing member 75 that rotatably supports the accessory drive shaft 71 to the cylinder head 11 with three bolts 77, 78, 79. Two bolts 77 and 78 out of 77 to 79 are arranged on both sides of the auxiliary drive shaft 71 at positions that do not overlap with the second drive gear 68 when viewed from the direction along the cylinder axis, whereas the remaining bolts 77 and 78 The bolt 79 fastens the bearing member 65 to the cylinder head 11 at a position partially overlapping the second drive gear 68 when viewed from the direction along the cylinder axis in order to increase the fastening rigidity of the bearing member 75 to the cylinder head 11. To be arranged.
[0045]
 In addition, the first virtual plane P1 parallel to the axes of the first and second camshafts 31 and 32 through the top surfaces of the two bolts 77 and 78 which are a part of the bolts 77 to 79, and A portion of the outer peripheral surface of the second drive gear 68 facing the remaining bolt 79 is disposed between the second virtual plane P2 parallel to the first virtual plane P1 through the top surface of the remaining bolt 79. ing.
[0046]
 Therefore, the auxiliary machine drive shaft 71 can be brought close to the first camshaft 31 that is one of the camshafts 31 and 32 without increasing the distance between the first and second camshafts 31 and 32, and the bearing member. 75 can be disposed close to the second drive gear 68 in the direction along the axis of the camshafts 31 and 32 while avoiding an increase in the position of the camshaft in the direction along the cylinder axis. This can contribute to downsizing.
[0047]
 Further, a first drive gear 51 and a first driven gear 52 which are provided at one end portions of the first and second camshafts 31 and 32 and mesh with each other are helical gears, and the first drive gear 51 and the first driven gear 52 Since the thrust force generated in the first camshaft 31 by the meshing and the thrust force generated in the first camshaft 31 by the meshing of the second drive gear 68 and the second driven gear 69, which are helical gears, are set in opposite directions. The first drive gear 51 and the first driven gear 52 provided at one end of the first and second camshafts 31 and 32, and the second drive gear 68 and the second driven gear 69 for driving the high-pressure fuel pump 70. It is possible to improve the durability.
[0048]
 Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0049]
 For example, in the above embodiment, the high-pressure fuel pump 70 that is an auxiliary machine is attached to the cylinder head 11, but the auxiliary machine may be attached to a part other than the cylinder head 11 of the engine body 10, for example, the cylinder block 12, In that case, the axis line of the auxiliary machine drive shaft 71 may be disposed between the cam shafts 31 and 32 on the cylinder head 11 side with respect to the straight line L connecting the axis lines of the cam shafts 31 and 32.
[0050]
 Further, the present invention can also be applied to a marine vessel propulsion engine such as an outboard motor whose crankshaft axis is vertical.
[0051]
【The invention's effect】
 As aboveBookAccording to the present invention, it is possible to make the engine compact in the direction along the cylinder axis by bringing the accessory drive shaft close to one of the two camshafts without increasing the distance between the pair of camshafts. In addition, by providing the cylinder head with a recess that accommodates part of the driven gear, the camshaft height in the direction along the cylinder axis can be reduced as much as possible, contributing to the downsizing of the engine. When the driven gear lifts up the accumulated oil, the meshing portion of the drive gear and the driven gear can be lubricated.In addition, the bearing member that supports the accessory drive shaft can be disposed close to the drive gear in the direction along the camshaft axis while avoiding an increase in the position of the camshaft along the cylinder axis. Can contribute to the downsizing of the engine.
[Brief description of the drawings]
FIG. 1 is a partial longitudinal sectional view of an engine and a sectional view taken along line 1-1 of FIG.
FIG. 2 is a view taken along line 2-2 in FIG. 1 with the head cover removed.
3 is an enlarged view of a portion indicated by an arrow 3 in FIG.
4 is a cross-sectional view taken along line 4-4 in FIG.
FIG. 5 is an enlarged view of a part indicated by an arrow 5 in FIG.
6 is an enlarged sectional view taken along line 6-6 in FIG.
7 is a sectional view taken along line 7-7 in FIG.
8 is a cross-sectional view taken along line 8-8 in FIG.
[Explanation of symbols]
10 ... Engine body
11 ... Cylinder head
31 ... 1st camshaft
32 ... Second camshaft
53 ... Sprocket as a power input unit
68 ... Drive gear
69 ... driven gear
70 ... High-pressure fuel pump as auxiliary equipment
71 ... Auxiliary machine drive shaft
75. Bearing member
75a ...
76 ... Bearing part
77, 78, 79, bolts
L ... Straight line
P1 ... 1st virtual plane
P2 ... Second virtual plane

Claims

A first camshaft (31) having a power input part (53) at one end and a second camshaft (32) whose one end is linked and connected to the first camshaft (31) are parallel to each other. And a driven gear (69) that is rotatably supported by the cylinder head (11) and meshes with a drive gear (68) provided at one other end of the first and second camshafts (31, 32). ) Is provided on an auxiliary machine drive shaft (71) connected to an auxiliary machine (70) attached to one end of the engine body (10) including the cylinder head (11) in the direction along the axis.
The axis of the accessory drive shaft (71) between the cam shafts (31, 32) on the cylinder head (11) side of the straight line (L) connecting the axes of the first and second cam shafts (31, 32). The cylinder head (11) has a recess (83) for accommodating a part of the driven gear (69), and the driven gear (69) scrapes the oil accumulated in the recess (83). It is provided so that it can be lifted to lubricate the meshing part of the drive gear (68) and the driven gear (69), and is arranged adjacent to the side surface of the driven gear (69) on the auxiliary machine (70) side A portion of the bearing member (75) is disposed at a position where the bearing member (75) supporting the auxiliary machine drive shaft (71) overlaps the drive gear (68) when viewed from the direction along the cylinder axis. The bottom of the cylinder head (1 ) Is fastened to, notch to avoid interference with the drive gear (68) of (75a) said bearing member (75), said auxiliary (70) and being formed on the side surface of the opposite side To engine.

A first camshaft (31) having a power input part (53) at one end and a second camshaft (32) whose one end is linked and connected to the first camshaft (31) are parallel to each other. And a driven gear (69) that is rotatably supported by the cylinder head (11) and meshes with a drive gear (68) provided at one other end of the first and second camshafts (31, 32). ) Is provided on an auxiliary machine drive shaft (71) connected to an auxiliary machine (70) attached to one end of the engine body (10) including the cylinder head (11) in the direction along the axis.
The axis of the accessory drive shaft (71) between the cam shafts (31, 32) on the cylinder head (11) side of the straight line (L) connecting the axes of the first and second cam shafts (31, 32). The cylinder head (11) has a recess (83) for accommodating a part of the driven gear (69), and the driven gear (69) scrapes the oil accumulated in the recess (83). It is provided so that it can be lifted to lubricate the meshing part of the drive gear (68) and the driven gear (69), and is arranged adjacent to the side surface of the driven gear (69) on the auxiliary machine (70) side A portion of the bearing member (75) is disposed at a position where the bearing member (75) supporting the auxiliary machine drive shaft (71) overlaps the drive gear (68) when viewed from the direction along the cylinder axis. and to so that, a plurality of bolts (77-7 ) Wherein is fastened to the bottom surface to the cylinder head (11) in said driving gear portion of the bolt (77, 78) when viewed from the direction along the cylinder axis of the plurality of bolts (77-79) and (68) Arranged on both sides of the accessory drive shaft (71) avoiding the overlapping position, the remaining bolt (79) is disposed at a position overlapping the drive gear (68) when viewed from the direction along the cylinder axis, The first imaginary plane (P1) parallel to the axis of the two camshafts (31, 32) through the top surfaces of the bolts (77, 78) of the part, and the top surfaces of the remaining bolts (79). A portion of the outer peripheral surface of the drive gear (68) facing the remaining bolt (79) is disposed between the first virtual plane (P1) and a second virtual plane (P2) parallel to the first virtual plane (P1). d and wherein the engine.