JP3923314B2

JP3923314B2 - SOHC type valve gear for internal combustion engine

Info

Publication number: JP3923314B2
Application number: JP2002000906A
Authority: JP
Inventors: 真美福澤; 幸一福尾; 美広藤吉
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2002-01-07
Filing date: 2002-01-07
Publication date: 2007-05-30
Anticipated expiration: 2022-05-30
Also published as: JP2002227624A

Description

【０００１】
【発明の属する技術分野】
本発明は、内燃機関、特に吸気弁および排気弁に対して共通の単一のカムシャフトが、シリンダヘッドと該ヘッド上に結合される複数のホルダとの間で回転自在に支承され、該カムシャフトと吸気弁との間には、連動および連動解除を切換可能な連動切換機構を有する複数の吸気弁駆動部材が、カムシャフトよりも上方でホルダに支持した吸気側揺動支軸を介して揺動可能に配設され、前記カムシャフトと排気弁との間には、各排気弁に個別に対応する排気弁駆動部材が、カムシャフトよりも上方でホルダに支持した排気側揺動支軸を介して揺動可能に配設され、前記複数の吸気弁駆動部材のうち、連動切換機構が連動解除状態にあるときに吸気弁に対して自由となる特定の吸気弁駆動部材をカム側に弾発付勢するロストモーション機構が、ホルダに固定されて吸気弁駆動部材及び排気弁駆動部材よりも上側に位置する支持板に支持されてなる内燃機関のＳＯＨＣ型動弁装置に関する。
【０００２】
【従来の技術】
従来、かかる動弁装置は、例えば特開平４−１４０５号公報等で既に知られている。
【０００３】
【発明が解決しようとする課題】
ところで、上記従来のものでは、一対の吸気弁に一端がそれぞれ連動、連結される２つのロッカアームを含む３つの吸気弁側ロッカアームの他端がローラーを介してカムにそれぞれ摺接され、それにより摩擦損失の低減が図られているが、連動切換機構は各吸気弁側ロッカアームの一端および揺動軸線間に設けられていたので、各吸気弁側ロッカアームの一端寄りの中間部（連動切換機構が配設される部分）が厚肉となる上、吸気弁上端部の弁ばね支持用リテーナと干渉し易くなって、相隣なるロッカアーム相互間のリフト量の設定自由度が狭くなる等の問題があった。
【０００４】
本発明は、かかる事情に鑑みてなされたものであり、摩擦損失の低減を図った上で上記問題を解決できるようにし、しかも高さ方向にコンパクトな内燃機関のＳＯＨＣ型動弁装置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記載の発明によれば、吸気弁および排気弁に対して共通の単一のカムシャフトが、シリンダヘッドと該ヘッド上に結合される複数のホルダとの間で回転自在に支承され、該カムシャフトと吸気弁との間には、連動および連動解除を切換可能な連動切換機構を有する複数の吸気弁駆動部材が、カムシャフトよりも上方でホルダに支持した吸気側揺動支軸を介して揺動可能に配設され、前記カムシャフトと排気弁との間には、各排気弁に個別に対応する排気弁駆動部材が、カムシャフトよりも上方でホルダに支持した排気側揺動支軸を介して揺動可能に配設され、前記複数の吸気弁駆動部材のうち、連動切換機構が連動解除状態にあるときに吸気弁に対して自由となる特定の吸気弁駆動部材をカム側に弾発付勢するロストモーション機構が、ホルダに固定されて吸気弁駆動部材及び排気弁駆動部材よりも上側に位置する支持板に支持されてなる、内燃機関のＳＯＨＣ型動弁装置において、前記連動切換機構は、隣接する吸気弁駆動部材を連動させる位置ならびにその連動を解除する位置間で移動可能な切換ピンと、切換ピンの移動を案内すべく複数の吸気弁駆動部材に各々固設される吸気弁用円筒状軸部材とを備えていて、吸気側揺動支軸から見て吸気弁とは反対側に配置されると共に、各々の円筒状軸部材には、前記カムシャフトにおける吸気弁用カムに摺接する円筒状の回転体が回転自在に支承され、前記特定の吸気弁駆動部材の、吸気弁用円筒状軸部材と吸気側揺動支軸との中間部上面に前記ロストモーション機構が当接することを特徴とする。
【０００６】
【発明の実施の形態】
本発明の実施の形態を、添付図面に例示した本発明の実施例に基づいて以下に具体的に説明する。
【０００７】
添付図面において、図１ないし図５は本発明の一実施例を示すものであり、図１はＶ型内燃機関の側面図、図２は図１の２−２線矢視拡大断面図、図３は図２の３−３線断面図、図４は図２の４−４線断面図、図５は図３の５−５線断面図である。
【０００８】
先ず図１において、このＶ型内燃機関は、クランク軸６の軸線方向に並ぶ１あるいは複数のシリンダ７と、該シリンダ７に対して上方に開いた略Ｖ字形に配置されてクランク軸６の軸線方向に並ぶ１あるいは複数のシリンダ７とがシリンダブロック８に設けられ、該シリンダブロック８に結合されるシリンダヘッド９，９に、上記Ｖ字形の内方側で各シリンダ７…の吸気ポート１０…が設けられるとともに上記Ｖ字形の外方側で各シリンダ７…の排気ポート１１…が設けられ、シリンダヘッド９，９間に各吸気ポート１０…に接続される吸気マニホールドＭが配置されて成るものである。図１に示されるように各シリンダヘッド９の頂部には、これを覆うヘッドカバーＣが結合される。
【０００９】
図２ないし図４を併せて参照して、シリンダ７にはピストン１２が摺動可能に嵌合され、該ピストン１２の上面およびシリンダヘッド９間に燃焼室１３が形成される。シリンダヘッド９には、燃焼室１３の天井面に開口するようにして一対の吸気弁口１４…ならびに一対の排気弁口１５…が設けられており、両吸気弁口１４…は吸気ポート１０に連通され、両排気弁口１５…は排気ポート１１に連通される。
【００１０】
両吸気弁口１４…を個別に開閉可能な一対の吸気弁１６，１６は、シリンダヘッド９にそれぞれ設けられたガイド筒１７…に摺動可能に嵌合され、各ガイド筒１７…から上方に突出した吸気弁１６，１６の上端部に設けられるリテーナ１８，１８とシリンダヘッド９との間には各吸気弁１６，１６を囲繞する弁ばね１９，１９が縮設され、それらの弁ばね１９，１９により吸気弁１６，１６は吸気弁口１４…を閉じる方向に付勢される。また両排気弁口１５…を個別に開閉可能な一対の排気弁２０，２０は、シリンダヘッド９にそれぞれ設けられたガイド筒２１…に摺動可能に嵌合され、各ガイド筒２１…から上方に突出した排気弁２０，２０の上端部に設けられるリテーナ２２，２２とシリンダヘッド９との間には各排気弁２０，２０を囲繞する弁ばね２３，２３が縮設され、それらの弁ばね２３，２３により排気弁２０，２０は排気弁口１５…を閉じる方向に付勢される。
【００１１】
上記両吸気弁１６，１６と、クランク軸６に１／２の減速比で連動、連結されるカムシャフト２６との間には、カムシャフト２６の回転運動を吸気弁１６，１６の開閉運動に変換する吸気弁駆動手段２７₁が設けられ、両排気弁２０，２０と前記カムシャフト２６との間には、カムシャフト２６の回転運動を排気弁２０，２０の開閉運動に変換する排気弁駆動手段２７₂が設けられる。
【００１２】
図５を併せて参照して、カムシャフト２６は、シリンダヘッド９と該シリンダヘッド９に結合されるホルダ２８とで、クランク軸６の回転軸線と平行な軸線を有して回転自在に支承される。このカムシャフト２６には、吸気弁用高速カム２９と、一方の吸気弁１６に対応して吸気弁用高速カム２９の一側に配置される吸気弁用低速カム３０と、吸気弁用高速カム２９に関して吸気弁用低速カム３０とは反対側で他方の吸気弁１６に対応して配置される吸気弁用休止カム３１と、吸気弁用低速カム３０および吸気弁用休止カム３１の両側で両排気弁２０，２０に個別に対応して配置される排気弁用カム３２，３２とがそれぞれ固設される。
【００１３】
吸気弁用高速カム２９は、機関の高速運転域で両吸気弁１６，１６を開閉作動せしめるための形状を有するものであり、カムシャフト２６の軸線を中心とする円弧状のベース円部２９ａと、該ベース円部２９ａから半径方向外方に張出す高位部２９ｂとを有する。吸気弁用低速カム３０は、機関の低速運転域で一方の吸気弁１６を開閉作動せしめるための形状を有するものであり、カムシャフト２６の軸線を中心とする円弧状のベース円部３０ａと、カムシャフト２６の半径方向外方へのベース円部３０ａからの張出量を吸気弁用高速カム２９の高位部２９ｂよりも小とするとともに該高位部２９ｂよりも狭い中心角範囲にわたってベース円部３０ａから張出した高位部３０ｂとを有する。また吸気弁用休止カム３１は、機関の低速運転域で他方の吸気弁１６を実質的に休止させるための形状を有するものであり、基本的には前記両カム２９，３０のベース円部２９ａ，３０ａに対応した真円状に形成されるが、前記両カム２９，３０の高位部２９ｂ，３０ｂに対応する部分には、吸気弁１６を実質的には休止状態に保つものの該吸気弁１６の吸気弁口１４への固着を回避すべくわずかに開弁させるための突部３１ａが設けられる。しかも吸気弁用低速カム３０の軸方向に沿う幅Ｗ₂は吸気弁用高速カム２９の幅Ｗ₁よりも小さく、また吸気弁用休止カム３１の軸方向に沿う幅Ｗ₃は吸気弁用低速カム３０の幅Ｗ₂よりも小さい。さらに排気弁用カム３２，３２は、機関の運転状態にかかわらず両排気弁２０，２０を開閉作動せしめるための形状を有する。
【００１４】
一方、吸気弁駆動手段２７₁は、相互に隣接配置される吸気弁駆動部材としての第１、第２および第３吸気弁側ロッカアーム３３，３４，３５と、それらのロッカアーム３３〜３５の連動および連動解除を切換可能な連動切換機構３６とを有するものであり、第１吸気弁側ロッカアーム３３は一方の吸気弁１６に連動、連結され、第３吸気弁側ロッカアーム３５は他方の吸気弁１６に連動、連結され、第２吸気弁側ロッカアーム３４は第１および第３吸気弁側ロッカアーム３３，３５間に配置される。第１〜第３吸気弁側ロッカアーム３３〜３５は、カムシャフト２６の斜め上方位置でホルダ２８に固定的に支持された吸気弁側ロッカアームシャフト３７で揺動自在に支承される。また排気弁駆動手段２７₂は、各排気弁２０，２０に個別に連動、連結される排気弁駆動部材としての一対の排気弁側ロッカアーム３８，３８を有し、それらの排気弁側ロッカアーム３８，３８は、カムシャフト２６の斜め上方位置でホルダ２８に固定的に支持された排気弁側ロッカアームシャフト３９で揺動自在に支承される。第１〜第３吸気弁側ロッカアーム３３〜３５はクランク軸６の軸線に沿うシリンダ７の両側に配置されるホルダ２８，２８間に隣接配置され、両排気弁側ロッカアーム３８，３８は、排気弁側ロッカアームシャフト３９を囲繞するコイルばね４２を相互間に介設するようにして両ホルダ２８，２８間に配置される。
【００１５】
吸気弁駆動手段２７₁において第１および第３吸気弁側ロッカアーム３３，３５には、吸気弁１６，１６側に延びる腕部３３ａ，３５ａが一体に設けられており、それらの腕部３３ａ，３５ａの先端には、両吸気弁１６，１６の上端に当接するタペットねじ４０，４０が進退自在に螺合される。また排気弁駆動手段２７₂における両排気弁側ロッカアーム３８，３８には、両排気弁２０，２０側に延びる腕部３８ａ，３８ａが一体に設けられており、それらの腕部３８ａ，３８ａの先端には、両排気弁２０，２０の上端に当接するタペットねじ４１，４１が進退自在に螺合される。
【００１６】
第１吸気弁側ロッカアーム３３において、その揺動軸線すなわち吸気弁側ロッカアームシャフト３７の軸線に関して吸気弁１６とは反対側の端部には、吸気弁用低速カム３０に摺接する円筒状の回転体４５が回転自在に支承され、第２吸気弁側ロッカアーム３４において、その揺動軸線に関して両吸気弁１６，１６とは反対側の端部には吸気弁用高速カム２９に摺接する円筒状の回転体４６が回転自在に支承され、第３吸気弁側ロッカアーム３５において、その揺動軸線に関して吸気弁１６とは反対側の端部には吸気弁用休止カム３１に摺接する円筒状の回転体４７が回転自在に支承され、両排気弁側ロッカアーム３８，３８において、その揺動軸線すなわち排気弁側ロッカアームシャフト３９の軸線に関して両排気弁２０，２０とは反対側の端部には排気弁用カム３２，３２に摺接する円筒状の回転体４８，４８が回転自在に支承される。
【００１７】
第１吸気弁側ロッカアーム３３には、第２吸気弁側ロッカアーム３４側に開放した有底の嵌合穴４９が吸気弁側ロッカアームシャフト３７と平行に穿設され、第２吸気弁側ロッカアーム３４には、嵌合穴４９に対応して両側面に開口する嵌合孔５０が穿設され、第３吸気弁側ロッカアーム３５には、嵌合孔５０に対応して第２吸気弁側ロッカアーム３４側に開放した有底の嵌合穴５１が吸気弁側ロッカアームシャフト３７と平行に穿設される。而して前記嵌合穴４９、嵌合孔５０および嵌合穴５１には、同径である円筒状軸部材５２，５３，５４がそれぞれ嵌合、固定され、円筒状軸部材５２〜５４と、それらの円筒状軸部材５２〜５４を同軸に囲繞する回転体４５〜４７との間には複数のころ５５…，５６…，５７…がそれぞれ介装される。また排気弁側ロッカアーム３８，３８には、両側面に開口する嵌合孔５８，５８が排気弁側ロッカアームシャフト３９と平行に穿設され、各嵌合孔５８，５８に嵌合、固定される円筒状軸部材５９，５９と、それらの円筒状軸部材５９，５９を同軸に囲繞する回転体４８，４８との間には複数のころ６０…，６０…がそれぞれ介装される。したがって第１〜第３吸気弁側ロッカアーム３３〜３５は回転体４５〜４７を介して対応するカム３０，２９，３１にそれぞれ摺接される。しかも吸気弁用高速カム２９の幅Ｗ₁＞吸気弁用低速カム３０の幅Ｗ₂＞吸気弁用休止カム３１の幅Ｗ₃であるので、回転体４６の軸方向長さ＞回転体４５の軸方向長さ＞回転体４７の軸方向長さ、に設定されている。さらに排気弁側ロッカアーム２０，２０は回転体４８，４８を介して排気弁用カム３２，３２にそれぞれ摺接される。
【００１８】
各吸気弁側ロッカアーム３３〜３５ならびに排気弁側ロッカアーム３８，３８の上方でホルダ２８…上には支持板６１が固定されており、この支持板６１には、第２吸気弁側ロッカアーム３４をその回転体４６が吸気弁用高速カム２９に摺接する方向に弾発付勢するロストモーション機構６２が設けられ、該ロストモーション機構６２は、下方に開放した有底円筒状に形成されて支持板６１に固定されるガイド部材６３と、第２吸気弁側ロッカアーム３４に先端を当接させてガイド部材６３に摺動可能に嵌合されるリフタ６４と、リフタ６４およびガイド部材６３間に縮設されるリフタばね６５とを備える。この場合、リフタ６４の先端は、第２吸気弁側ロッカアーム３４の、吸気弁側ロッカアームシャフト３７と円筒状軸部材５３との中間部上面に当接しているため、リフタ６４（ロストモーション機構６２）に対する受け座を該第２吸気弁側ロッカアーム３４の一端から特別に延設（例えば特開昭63-100211 号公報の第３図参照）させる必要はなくなり、それだけ第２吸気弁側ロッカアーム３４の構造簡素化と小型化が図られる。
【００１９】
連動切換機構３６は、第３および第２吸気弁側ロッカアーム３５，３４の連動および連動解除を切換可能な第１切換ピン６８と、第２および第１吸気弁側ロッカアーム３４，３３の連動および連動解除を切換可能な第２切換ピン６９と、第１切換ピン６８とは反対側で第２切換ピン６９に摺接する規制部材７０と、規制部材７０を第２切換ピン６９側に付勢する戻しばね７１とを備える。
【００２０】
第１切換ピン６８は、第３吸気弁側ロッカアーム３５の円筒状軸部材５４に摺動可能に嵌合されるものであり、第３吸気弁側ロッカアーム３５における嵌合穴５１の閉塞端と第１切換ピン６８との間には液圧室７２が画成される。また第３吸気弁側ロッカアーム３５には液圧室７２に通じる連通路７３が穿設され、吸気弁側ロッカアームシャフト３７内には、前記連通路７３に常時通じる液圧路７４が設けられる。而して該液圧路７４は図示しない制御弁を介して液圧源に接続される。
【００２１】
第２切換ピン６９は、第２吸気弁側ロッカアーム３４の円筒状軸部材５３に摺動可能に嵌合され、第２切換ピン６９の一端は第１切換ピン６８に摺接されている。
【００２２】
規制部材７０は、有底円筒状に形成されて第１吸気弁側ロッカアーム３３の円筒状軸部材５２に摺動可能に嵌合されるものであり、この規制部材７０の閉塞端が第２切換ピン６９の他端に摺接される。また円筒状軸部材５２の内面には、規制部材７０に当接して該規制部材７０が円筒状軸部材５２から脱落するのを阻止するための止め輪７５が嵌着される。戻しばね７１は、第１吸気弁側ロッカアーム３３における嵌合穴４９の閉塞端と規制部材７０との間に縮設され、前記嵌合穴４９の閉塞端には開放孔７６が穿設される。
【００２３】
ところで、燃焼室１３の天井面中央部には点火プラグ７８が配設されるものであり、該点火プラグ７８を挿入するためのプラグパイプ７９がシリンダヘッド９に配設される。而して吸気弁駆動手段２７₁において、各吸気弁側ロッカアーム３３〜３５は吸気弁側ロッカアームシャフト３７に関して両吸気弁１６，１６とは反対側で回転体４５〜４７を介してカムシャフト２６の各カム３０，２９，３１に摺接されるものであって連動切換機構３６もそれらの回転体４５〜４７と同軸に配置されるので、第１および第３吸気弁側ロッカアーム３３，３５の腕部３３ａ，３５ａ間には空きスペースがあり、その空きスペースに上記プラグパイプ７９を配設することができる。したがって、吸気側を内方側に配置した車載用Ｖ型内燃機関において、点火プラグ７８の脱着のためのプラグパイプ７９を、Ｖ型内燃機関の内方側に配設することが可能となる。
【００２４】
次にこの実施例の作用について説明すると、機関の低速運転域では、連動切換機構３６の液圧室７２に液圧は作用しておらず、第１および第２切換ピン６８，６９の摺接面は第３および第２吸気弁側ロッカアーム３４，３５間に対応する位置に在り、第２切換ピン６９および規制部材７０の摺接面は第２および第１吸気弁側ロッカアーム３４，３３間に対応する位置に在る。したがって各吸気弁側ロッカアーム３３〜３５は相対揺動可能な状態にあり、一方の吸気弁１６が吸気弁用低速カム３０に応じたタイミングおよびリフト量で開閉駆動されるのに対し、他方の吸気弁１６は実質的に休止されている。
【００２５】
機関の高速運転域では、連動切換機構３６の液圧室７２に高圧の液圧が作用せしめられ、第１切換ピン６８は第２切換ピン６９を押圧しながら第２吸気弁側ロッカアーム３４の円筒状軸部材５３に嵌合し、第２切換ピン６９は規制部材７０を押圧しながら第１吸気弁側ロッカアーム３３の円筒状軸部材５２に嵌合する。したがって第１〜第３吸気弁側ロッカアーム３３〜３５は一体的に連結された状態となり、両吸気弁１６，１６は吸気弁用高速カム２９に応じたタイミングおよびリフト量で開閉駆動されることになる。
【００２６】
このようにして機関の低速運転域および高速運転域で両吸気弁１６，１６の開閉作動特性を変化させることにより、機関の運転状態に適合した動弁特性として機関出力の向上を図ることができる。
【００２７】
一方、両排気弁２０，２０は、機関の低速運転域および高速運転域とも、排気弁用カム３２，３２に応じたタイミングおよびリフト量で開閉駆動されることになる。
【００２８】
このような動弁装置において、吸気弁駆動手段２７₁および排気弁駆動手段２７₂とも、各ロッカアーム３３〜３５，３８，３８は回転体４５〜４７，４８，４８を介して対応するカム３０，２９，３１，３２，３２に摺接するので、摩擦損失を低減して開弁動力の低減を図ることができる。また第１〜第３吸気弁側ロッカアーム３３〜３５に設けられる連動切換機構３６は、前記回転体４５〜４７と同軸に配置されるものであり、連動切換機構３６を構成する切換ピン６８，６９、規制部材７０および戻しばね７１は、回転体４５〜４７を支承すべく各ロッカアーム３３〜３５に設けられた円筒状軸部材５２〜５４内に挿入されるので、連動切換機構３６を構成するための穿孔加工を各ロッカアーム３３〜３５に施すことが不要となり、加工工数の低減に寄与することができる。
【００２９】
しかも点火プラグ７８を吸気弁１６，１６側に配置することができるので、点火プラグ７８まわりの熱引き性を向上することができ、最大トルクを発生させる点火時期近傍に点火プラグ７８の点火時期を設定してもノッキングの発生を抑えることができ、したがって充分な出力トルクを得ることができる。
【００３０】
また吸気側を内方側に配置した車載用Ｖ型内燃機関において、点火プラグ７８が吸気弁１６，１６側に配置されることにより、点火プラグ７８の脱着のためのスペースをＶ型内燃機関の上方に確保すればよく、点火プラグ７８の脱着のためのスペースを確保することが容易となる。
【００３１】
ところで、連動切換機構３６において、液圧室７２に高圧の液圧を作用させたにもかかわらず、第１および第２切換ピン６８，６９の連結作動が何らかの原因により阻害され、連動切換機構３６が連動解除状態のままとなる場合が考えられる。その場合、相互に独立して作動する両吸気弁１６，１６のうち相対的に高リフトとなる吸気弁１６を駆動する第１吸気弁側ロッカアーム３３に、所定の高回転域まで動弁系挙動を保証するために、弁ばね１９のばね荷重を第１吸気弁側ロッカアーム３３の重量に対応して比較的高く設定しておく必要がある。したがって第１吸気弁側ロッカアーム３３が比較的大重量であれば、上記弁ばね１９のばね荷重もそれに対応して大きく設定せねばならず、連動解除状態ならびに連動状態での開弁動力が大きくなる。しかるに、相互に独立して作動する両吸気弁１６，１６のうち相対的に低リフトとなる吸気弁１６を駆動する第３吸気弁側ロッカアーム３５に液圧室７２および連通路７３が設けられることにより、第１吸気弁側ロッカアーム３３は、液圧室７２および連通路７３がない分だけ軽量化可能であり、したがって第１吸気弁側ロッカアーム３３を付勢するばね荷重を比較的低く設定して開弁動力の低減に寄与することができる。
【００３２】
また液圧室７２および連通路７３が設けられる第３吸気弁側ロッカアーム３５では、回転体４６の軸方向長さ＞回転体４５の軸方向長さ＞回転体４７の軸方向長さとなっているために、液圧室７２および連通路７３を配設しても吸気弁側ロッカアームシャフト３７の軸線に沿う幅を比較的小さく設定することが可能であり、それにより第３吸気弁側ロッカアーム３５の重量増大を抑えて開弁動力低減に寄与することができるとともに、カムシャフト２６の軸線に沿って動弁装置を比較的コンパクトに構成することが可能となる。
【００３３】
以上、本発明の実施例を詳述したが、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なうことが可能である。
【００３４】
【発明の効果】
以上のように本発明によれば、連動切換機構は、隣接する吸気弁駆動部材を連動させる位置ならびにその連動を解除する位置間で移動可能な切換ピンと、切換ピンの移動を案内すべく複数の吸気弁駆動部材に各々固設される吸気弁用円筒状軸部材とを備えていて、吸気側揺動支軸から見て吸気弁とは反対側に配置され、各々の円筒状軸部材には、カムシャフトにおける吸気弁用カムに摺接する円筒状の回転体が回転自在に支承されるので、各吸気弁駆動部材の吸気弁側の端部ないしはその近くに連動切換機構を配設する必要はなくなり、従って、吸気弁上端部の周辺において弁ばね支持用リテーナ等の部品を配置するスペースを連動切換機構に影響されずに十分に確保可能となるから、相隣なる吸気弁駆動部材相互間のリフト量の設定自由度を高めることができ、しかも吸気側揺動支軸よりも下方に配設されるカムシャフトの上方スペースを有効に利用して連動切換機構を無理なく配設できることから動弁機構の高さ方向の小型化に寄与することができ、さらに吸気弁駆動部材の、連動切換機構を保持する部分の肉厚（特に上下方向）も十分に確保できるから該部材の変形防止に効果的であって、該連動切換機構の切換作動の信頼性向上にも寄与することができる。
【００３５】
また連動切換機構が連動解除状態にあるときに吸気弁に対して自由となる特定の吸気弁駆動部材をカム側に弾発付勢するロストモーション機構が、シリンダヘッド上に結合されたカムシャフト用ホルダに固定されて吸、排気弁駆動部材よりも上側に位置する支持板に支持され、前記特定の吸気弁駆動部材の、吸気弁用円筒状軸部材と吸気側揺動支軸との中間部外面に前記ロストモーション機構が当接しているので、カムシャフトと支持板間で特定の吸気弁駆動部材及びロストモーション機構を上下方向に極力詰めてコンパクトに配置しつつ、該吸気弁駆動部材の前記中間部でロストモーション機構からの付勢力を直接受けることができて、その付勢力を吸気弁駆動部材に効率よく伝達し得るばかりか、ロストモーション受け座を該吸気弁駆動部材の一端から特別に延設させる必要はなくなり、それらの結果、全体として動弁装置の高さ方向小型化を図りながら、該吸気弁駆動部材自体の構造簡素化と小型化とが達成できて、その慣性質量の低減、延いては機関の高出力化に寄与することができる。
【図面の簡単な説明】
【図１】Ｖ型内燃機関の側面図
【図２】図１の２−２線矢視拡大断面図
【図３】図２の３−３線断面図
【図４】図２の４−４線断面図
【図５】図３の５−５線断面図
【符号の説明】
１６・・・・・・吸気弁
２０・・・・・・排気弁
２６・・・・・・カムシャフト
２８・・・・・・ホルダ
２９，３０，３１・・吸気弁用カム
３２・・・・・・排気弁用カム
３３，３４，３５・・・・・・吸気弁駆動部材としての吸気弁側ロッカアーム
３６・・・・・・連動切換機構
３７・・・・・・吸気側揺動支軸としての吸気弁側ロッカアームシャフト
３８・・・・・・排気弁駆動部材としての排気弁側ロッカアーム
３９・・・・・・排気側揺動支軸としての排気弁側ロッカアームシャフト
４５，４６，４７・・回転体
５２，５３，５４・・吸気弁用円筒状軸部材
５９・・・・・・排気弁用円筒状軸部材
６１・・・・・・支持板
６２・・・・・・ロストモーション機構
６８，６９・・・切換ピン[0001]
BACKGROUND OF THE INVENTION
  According to the present invention, a single camshaft common to an internal combustion engine, in particular an intake valve and an exhaust valve, is rotatably supported between a cylinder head and a plurality of holders coupled on the head. Between the shaft and the intake valve, a plurality of intake valve drive members having an interlocking switching mechanism capable of switching between interlocking and interlocking release are provided via an intake side swing support shaft supported by a holder above the camshaft. An exhaust-side swing support shaft is disposed between the camshaft and the exhaust valve so that the exhaust valve drive member individually corresponding to each exhaust valve is supported by the holder above the camshaft. A specific intake valve drive member that is free to the intake valve when the interlock switching mechanism is in the interlock release state among the plurality of intake valve drive members is arranged on the cam side. The lost motion mechanism that urges the bullet, It relates SOHC Katadoben device fixed to the intake valve driving member and supported by a supporting plate which is located above the exhaust valve driving member formed of an internal combustion engine folder.
[0002]
[Prior art]
  Conventionally, such a valve gear is already known, for example, in Japanese Patent Laid-Open No. 4-1405.
[0003]
[Problems to be solved by the invention]
  By the way, in the above-mentioned conventional one, the other end of the three intake valve side rocker arms including the two rocker arms that are linked and connected to the pair of intake valves are respectively slidably contacted with the cams via the rollers, thereby causing friction. Although the loss is reduced, the interlocking switching mechanism is provided between one end of each intake valve side rocker arm and the swing axis, so an intermediate portion near one end of each intake valve side rocker arm (the interlocking switching mechanism is arranged). The part to be installed) becomes thicker and more easily interferes with the retainer for supporting the valve spring at the upper end of the intake valve, so that the degree of freedom in setting the lift amount between adjacent rocker arms is reduced. It was.
[0004]
  The present invention has been made in view of such circumstances, and provides an SOHC type valve operating apparatus for an internal combustion engine that is capable of solving the above-mentioned problems while reducing friction loss and that is compact in the height direction. For the purpose.
[0005]
[Means for Solving the Problems]
  To achieve the above object, according to the first aspect of the present invention, a single camshaft common to the intake valve and the exhaust valve is formed of a cylinder head and a plurality of holders coupled on the head. A plurality of intake valve drive members having an interlocking switching mechanism capable of switching between interlocking and interlocking release are supported by the holder above the camshaft between the camshaft and the intake valve. An exhaust valve drive member individually corresponding to each exhaust valve is disposed above the camshaft between the camshaft and the exhaust valve. It is disposed so as to be swingable via an exhaust-side swing support shaft supported by a holder, and becomes free with respect to the intake valve when the interlock switching mechanism is in the interlock release state among the plurality of intake valve drive members. A specific intake valve drive member is impacted on the cam side. In the SOHC type valve operating system for an internal combustion engine, the lost switching mechanism is fixed to a holder and supported by a support plate positioned above the intake valve driving member and the exhaust valve driving member. A switching pin that can be moved between a position where the adjacent intake valve driving member is interlocked and a position where the interlock is released, and a cylindrical shape for the intake valve fixed to each of the plurality of intake valve driving members to guide the movement of the switching pin A cylindrical member that is disposed on the opposite side of the intake valve as viewed from the intake side swing support shaft, and that each cylindrical shaft member is in sliding contact with the intake valve cam on the camshaft. Shaped rotating body is rotatably supported,in frontThe lost motion mechanism is in contact with the upper surface of the intermediate portion of the intake valve driving shaft and the intake shaft swinging support shaft of the specific intake valve drive member.It is characterized by that.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be specifically described below based on the embodiments of the present invention illustrated in the accompanying drawings.
[0007]
  1 to 5 show an embodiment of the present invention, FIG. 1 is a side view of a V-type internal combustion engine, and FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a sectional view taken along line 4-4 in FIG. 2, and FIG. 5 is a sectional view taken along line 5-5 in FIG.
[0008]
  First, in FIG. 1, this V-type internal combustion engine includes one or a plurality of cylinders 7 arranged in the axial direction of the crankshaft 6, and a substantially V-shape that opens upward with respect to the cylinders 7. One or a plurality of cylinders 7 arranged in the direction are provided in the cylinder block 8, and the cylinder heads 9, 9 coupled to the cylinder block 8 are connected to the intake ports 10 of the cylinders 7 on the inner side of the V shape. And the exhaust port 11 of each cylinder 7 is provided on the outer side of the V-shape, and an intake manifold M connected to each intake port 10 is disposed between the cylinder heads 9 and 9. It is. As shown in FIG. 1, a head cover C covering the top of each cylinder head 9 is coupled.
[0009]
  2 to 4 together, a piston 12 is slidably fitted into the cylinder 7, and a combustion chamber 13 is formed between the upper surface of the piston 12 and the cylinder head 9. The cylinder head 9 is provided with a pair of intake valve ports 14 and a pair of exhaust valve ports 15 so as to open to the ceiling surface of the combustion chamber 13, and both intake valve ports 14 are connected to the intake port 10. The two exhaust valve ports 15... Are communicated with the exhaust port 11.
[0010]
  A pair of intake valves 16, 16 capable of individually opening and closing both intake valve ports 14 are slidably fitted into guide cylinders 17 provided respectively on the cylinder head 9, and upward from the respective guide cylinders 17. Between the retainers 18 and 18 provided at the upper end portions of the protruding intake valves 16 and 16 and the cylinder head 9, valve springs 19 and 19 surrounding the intake valves 16 and 16 are contracted, and these valve springs 19 are provided. , 19 urge the intake valves 16, 16 in a direction to close the intake valve ports 14. Further, a pair of exhaust valves 20 and 20 capable of individually opening and closing both exhaust valve ports 15 are slidably fitted to guide cylinders 21 provided on the cylinder head 9 respectively, and upward from the respective guide cylinders 21. Between the retainers 22 and 22 provided at the upper ends of the exhaust valves 20 and 20 projecting to the cylinder head 9, valve springs 23 and 23 surrounding the exhaust valves 20 and 20 are contracted, and these valve springs are provided. 23 and 23 urge the exhaust valves 20 and 20 in a direction to close the exhaust valve ports 15.
[0011]
  Between the intake valves 16 and 16 and the camshaft 26 that is linked and connected to the crankshaft 6 at a reduction ratio of 1/2, the rotational movement of the camshaft 26 is changed to the opening and closing movement of the intake valves 16 and 16. Intake valve drive means 27 for conversion₁Exhaust valve drive means 27 for converting the rotational motion of the camshaft 26 into the open / close motion of the exhaust valves 20, 20 is provided between the exhaust valves 20, 20 and the camshaft 26.₂Is provided.
[0012]
  Referring also to FIG. 5, the camshaft 26 is rotatably supported by the cylinder head 9 and a holder 28 coupled to the cylinder head 9, having an axis parallel to the rotation axis of the crankshaft 6. The The camshaft 26 includes an intake valve high-speed cam 29, an intake valve low-speed cam 30 disposed on one side of the intake valve high-speed cam 29 corresponding to one intake valve 16, and an intake valve high-speed cam. 29, the intake valve rest cam 31 disposed on the opposite side of the intake valve low-speed cam 30 and corresponding to the other intake valve 16, and both the intake valve low-speed cam 30 and the intake valve stop cam 31 on both sides. Exhaust valve cams 32, 32 arranged individually corresponding to the exhaust valves 20, 20 are respectively fixed.
[0013]
  The intake valve high-speed cam 29 has a shape for opening and closing both intake valves 16 and 16 in the high-speed operation region of the engine, and includes an arc-shaped base circle portion 29 a centering on the axis of the camshaft 26. And a high-order part 29b projecting outward from the base circle part 29a in the radial direction. The intake valve low-speed cam 30 has a shape for opening and closing one intake valve 16 in the low-speed operation region of the engine, and includes an arc-shaped base circle portion 30a centering on the axis of the camshaft 26; The amount of protrusion of the camshaft 26 radially outward from the base circle portion 30a is smaller than the high position portion 29b of the intake valve high-speed cam 29, and the base circle portion extends over a central angle range narrower than the high position portion 29b. And a high position portion 30b protruding from 30a. The intake valve stop cam 31 has a shape for substantially stopping the other intake valve 16 in the low speed operation region of the engine. Basically, the base circular portion 29a of both the cams 29, 30 is used. , 30a, and the cams 29, 30 corresponding to the high positions 29b, 30b of the cams 29, 30, the intake valve 16 is substantially kept in a resting state. In order to avoid sticking to the intake valve port 14, a protrusion 31 a for slightly opening the valve is provided. Moreover, the width W along the axial direction of the low-speed cam 30 for the intake valve₂Is the width W of the high-speed cam 29 for the intake valve₁And the width W along the axial direction of the intake valve rest cam 31_ThreeIs the width W of the low-speed cam 30 for the intake valve₂Smaller than. Further, the exhaust valve cams 32, 32 have a shape for opening and closing both the exhaust valves 20, 20 regardless of the operating state of the engine.
[0014]
  On the other hand, the intake valve drive means 27₁The first, second and third intake valve side rocker arms 33, 34, 35 as the intake valve drive members arranged adjacent to each other, and the interlock switching that can switch the interlock and the interlock release of these rocker arms 33-35. The first intake valve side rocker arm 33 is linked and connected to one intake valve 16, and the third intake valve side rocker arm 35 is linked and connected to the other intake valve 16, and the second intake valve 16 is provided. The valve rocker arm 34 is disposed between the first and third intake valve rocker arms 33 and 35. The first to third intake valve side rocker arms 33 to 35 are swingably supported by an intake valve side rocker arm shaft 37 fixedly supported by the holder 28 at a position obliquely above the camshaft 26. Also, the exhaust valve driving means 27₂Has a pair of exhaust valve side rocker arms 38 and 38 as exhaust valve drive members that are individually linked and connected to the exhaust valves 20 and 20, and these exhaust valve side rocker arms 38 and 38 are connected to the camshaft 26. The exhaust valve side rocker arm shaft 39 is fixedly supported by the holder 28 at an obliquely upper position and is supported so as to be swingable. The first to third intake valve side rocker arms 33 to 35 are arranged adjacent to each other between the holders 28 and 28 arranged on both sides of the cylinder 7 along the axis of the crankshaft 6. A coil spring 42 surrounding the side rocker arm shaft 39 is disposed between the holders 28 and 28 so as to be interposed therebetween.
[0015]
  Intake valve driving means 27₁The first and third intake valve side rocker arms 33 and 35 are integrally provided with arm portions 33a and 35a extending toward the intake valves 16 and 16, respectively. Tappet screws 40, 40 that are in contact with the upper ends of the intake valves 16, 16 are screwed together so as to freely advance and retract. Also, the exhaust valve driving means 27₂Both exhaust valve side rocker arms 38, 38 are integrally provided with arm portions 38a, 38a extending to both exhaust valve 20, 20 sides, and both exhaust valve 20 are provided at the tips of these arm portions 38a, 38a. , 20 tappet screws 41, 41 which are in contact with the upper ends of 20 are screwed together so as to freely advance and retract.
[0016]
  In the first intake valve side rocker arm 33, a cylindrical rotating body that is in sliding contact with the intake valve low-speed cam 30 is located at the end opposite to the intake valve 16 with respect to the swing axis thereof, that is, the axis of the intake valve side rocker arm shaft 37. 45 is rotatably supported, and the second intake valve side rocker arm 34 has a cylindrical rotation that is in sliding contact with the intake valve high-speed cam 29 at the end opposite to the intake valves 16 and 16 with respect to the swing axis. A body 46 is rotatably supported. In the third intake valve side rocker arm 35, a cylindrical rotary body 47 slidably in contact with the intake valve rest cam 31 is provided at the end of the third intake valve side rocker arm 35 opposite to the intake valve 16. Are rotatably supported, and both exhaust valve side rocker arms 38, 38 are opposite to both exhaust valves 20, 20 with respect to the swing axis thereof, that is, the axis line of the exhaust valve side rocker arm shaft 39. The end cylindrical rotary member 48, 48 in sliding contact is rotatably supported on the exhaust valve cam 32, 32.
[0017]
  The first intake valve side rocker arm 33 is provided with a bottomed fitting hole 49 opened to the second intake valve side rocker arm 34 side in parallel with the intake valve side rocker arm shaft 37, so that the second intake valve side rocker arm 34 has Are provided with fitting holes 50 opened on both side surfaces corresponding to the fitting holes 49, and the third intake valve side rocker arm 35 is provided on the second intake valve side rocker arm 34 side corresponding to the fitting hole 50. A bottomed fitting hole 51 that is open at the bottom is formed in parallel with the intake valve side rocker arm shaft 37. Thus, cylindrical shaft members 52, 53, and 54 having the same diameter are fitted and fixed in the fitting hole 49, the fitting hole 50, and the fitting hole 51, respectively. A plurality of rollers 55, 56,... 57 are interposed between the rotating bodies 45 to 47 that coaxially surround the cylindrical shaft members 52 to 54, respectively. The exhaust valve side rocker arms 38, 38 are provided with fitting holes 58, 58 opened on both side surfaces in parallel with the exhaust valve side rocker arm shaft 39, and are fitted and fixed to the fitting holes 58, 58, respectively. A plurality of rollers 60... 60 are respectively interposed between the cylindrical shaft members 59 and 59 and the rotating bodies 48 and 48 that coaxially surround the cylindrical shaft members 59 and 59. Accordingly, the first to third intake valve side rocker arms 33 to 35 are slidably contacted with the corresponding cams 30, 29, and 31 via the rotating bodies 45 to 47. Moreover, the width W of the high-speed cam 29 for the intake valve₁> Width W of low-speed cam 30 for intake valve₂> Width W of intake cam idle cam 31_ThreeTherefore, the axial length of the rotating body 46> the axial length of the rotating body 45> the axial length of the rotating body 47 is set. Further, the exhaust valve side rocker arms 20 and 20 are slidably contacted with the exhaust valve cams 32 and 32 via the rotating bodies 48 and 48, respectively..
[0018]
  A support plate 61 is fixed on the holder 28 over the intake valve side rocker arms 33 to 35 and the exhaust valve side rocker arms 38, 38, and the second intake valve side rocker arm 34 is attached to the support plate 61. A lost motion mechanism 62 is provided for elastically energizing the rotating body 46 in a direction in which the rotating body 46 is slidably in contact with the intake valve high-speed cam 29. A guide member 63 that is fixed to the second intake valve side, a lifter 64 that is slidably fitted to the guide member 63 with its tip abutted against the second intake valve side rocker arm 34, and is contracted between the lifter 64 and the guide member 63. The lifter spring 65 is provided. In this case, since the tip of the lifter 64 is in contact with the upper surface of the second intake valve side rocker arm 34 between the intake valve side rocker arm shaft 37 and the cylindrical shaft member 53, the lifter 64 (lost motion mechanism 62). It is no longer necessary to extend a receiving seat for the second intake valve side rocker arm 34 (see, for example, FIG. 3 of JP-A-63-100211). Simplification and miniaturization are achieved.
[0019]
  The interlocking switching mechanism 36 interlocks and interlocks the first switching pin 68 that can switch between interlocking and interlocking release of the third and second intake valve side rocker arms 35 and 34 and the second and first intake valve side rocker arms 34 and 33. A second switching pin 69 that can be released, a regulating member 70 that is in sliding contact with the second switching pin 69 on the side opposite to the first switching pin 68, and a return that biases the regulating member 70 toward the second switching pin 69. And a spring 71.
[0020]
  The first switching pin 68 is slidably fitted to the cylindrical shaft member 54 of the third intake valve side rocker arm 35, and is connected to the closed end of the fitting hole 51 in the third intake valve side rocker arm 35. A hydraulic chamber 72 is defined between the one switching pin 68. The third intake valve side rocker arm 35 is provided with a communication path 73 that communicates with the hydraulic pressure chamber 72, and the intake valve side rocker arm shaft 37 is provided with a hydraulic pressure path 74 that always communicates with the communication path 73. Thus, the fluid pressure path 74 is connected to a fluid pressure source via a control valve (not shown).
[0021]
  The second switching pin 69 is slidably fitted to the cylindrical shaft member 53 of the second intake valve side rocker arm 34, and one end of the second switching pin 69 is in sliding contact with the first switching pin 68.
[0022]
  The restricting member 70 is formed in a bottomed cylindrical shape and is slidably fitted to the cylindrical shaft member 52 of the first intake valve side rocker arm 33, and the closed end of the restricting member 70 is second switched. The other end of the pin 69 is slidably contacted. A retaining ring 75 is fitted on the inner surface of the cylindrical shaft member 52 so as to abut against the regulating member 70 and prevent the regulating member 70 from falling off the cylindrical shaft member 52. The return spring 71 is contracted between the closed end of the fitting hole 49 in the first intake valve side rocker arm 33 and the regulating member 70, and an open hole 76 is formed in the closed end of the fitting hole 49. .
[0023]
  Incidentally, a spark plug 78 is disposed at the center of the ceiling surface of the combustion chamber 13, and a plug pipe 79 for inserting the spark plug 78 is disposed in the cylinder head 9. Thus, the intake valve driving means 27₁The intake valve side rocker arms 33 to 35 slide on the cams 30, 29, and 31 of the camshaft 26 via the rotating bodies 45 to 47 on the opposite side of the intake valve side rocker arm shaft 37 from the intake valves 16 and 16. Since the interlocking switching mechanism 36 is also arranged coaxially with the rotating bodies 45 to 47, there is an empty space between the arm portions 33a and 35a of the first and third intake valve side rocker arms 33 and 35. The plug pipe 79 can be disposed in the empty space. Therefore, in the in-vehicle V-type internal combustion engine in which the intake side is arranged on the inner side, the plug pipe 79 for attaching / detaching the spark plug 78 can be arranged on the inner side of the V-type internal combustion engine.
[0024]
  Next, the operation of this embodiment will be described. In the low-speed operation region of the engine, no hydraulic pressure is applied to the hydraulic chamber 72 of the interlocking switching mechanism 36, and the first and second switching pins 68 and 69 are in sliding contact. The surface is located at a position corresponding to between the third and second intake valve side rocker arms 34, 35, and the sliding surface of the second switching pin 69 and the regulating member 70 is between the second and first intake valve side rocker arms 34, 33. In the corresponding position. Accordingly, the intake valve side rocker arms 33 to 35 are in a relatively swingable state, and one intake valve 16 is driven to open and close at a timing and lift amount corresponding to the intake valve low-speed cam 30, whereas the other intake valve 16 is driven. Valve 16 is substantially deactivated.
[0025]
  In the high-speed operation region of the engine, a high hydraulic pressure is applied to the hydraulic chamber 72 of the interlocking switching mechanism 36, and the first switching pin 68 presses the second switching pin 69 and the cylinder of the second intake valve side rocker arm 34. The second switching pin 69 is fitted to the cylindrical shaft member 52 of the first intake valve side rocker arm 33 while pressing the regulating member 70. Accordingly, the first to third intake valve side rocker arms 33 to 35 are integrally connected, and both intake valves 16 and 16 are opened and closed at a timing and lift amount corresponding to the intake valve high-speed cam 29. Become.
[0026]
  In this way, by changing the opening / closing operation characteristics of the intake valves 16, 16 in the low speed operation range and the high speed operation range of the engine, it is possible to improve the engine output as a valve operating characteristic adapted to the operating state of the engine. .
[0027]
  On the other hand, both the exhaust valves 20 and 20 are driven to open and close at a timing and a lift amount corresponding to the exhaust valve cams 32 and 32 in both the low speed operation region and the high speed operation region of the engine.
[0028]
  In such a valve operating apparatus, the intake valve driving means 27₁And exhaust valve driving means 27₂In each case, the rocker arms 33 to 35, 38, and 38 are in sliding contact with the corresponding cams 30, 29, 31, 32, and 32 through the rotating bodies 45 to 47, 48, and 48, so that the friction loss is reduced and the valve opening power is reduced. Can be reduced. The interlocking switching mechanism 36 provided in the first to third intake valve side rocker arms 33 to 35 is arranged coaxially with the rotating bodies 45 to 47, and switching pins 68 and 69 constituting the interlocking switching mechanism 36. The regulating member 70 and the return spring 71 are inserted into the cylindrical shaft members 52 to 54 provided on the rocker arms 33 to 35 so as to support the rotating bodies 45 to 47, so that the interlocking switching mechanism 36 is configured. It is not necessary to perform the drilling process on each of the rocker arms 33 to 35, which can contribute to a reduction in the number of processing steps.
[0029]
  In addition, since the spark plug 78 can be arranged on the intake valves 16 and 16 side, the heat drawability around the spark plug 78 can be improved, and the ignition timing of the spark plug 78 is set in the vicinity of the ignition timing that generates the maximum torque. Even if it is set, the occurrence of knocking can be suppressed, so that a sufficient output torque can be obtained.
[0030]
  Further, in the in-vehicle V-type internal combustion engine in which the intake side is disposed on the inner side, the spark plug 78 is disposed on the intake valves 16 and 16 side, so that a space for detaching the spark plug 78 is provided in the V-type internal combustion engine. What is necessary is just to ensure above, and it becomes easy to ensure the space for attachment / detachment of the spark plug 78. FIG.
[0031]
  By the way, in the interlocking switching mechanism 36, although the high hydraulic pressure is applied to the hydraulic chamber 72, the connection operation of the first and second switching pins 68 and 69 is hindered for some reason, and the interlocking switching mechanism 36 May remain in the interlock release state. In this case, the first intake valve side rocker arm 33 that drives the intake valve 16 that has a relatively high lift out of the two intake valves 16 and 16 that operate independently of each other has a valve operating system behavior up to a predetermined high rotation range. Therefore, it is necessary to set the spring load of the valve spring 19 to be relatively high corresponding to the weight of the first intake valve side rocker arm 33. Therefore, if the first intake valve side rocker arm 33 is relatively heavy, the spring load of the valve spring 19 must be set correspondingly, and the valve opening power in the interlock release state and the interlock state increases. . However, the hydraulic pressure chamber 72 and the communication path 73 are provided in the third intake valve side rocker arm 35 that drives the intake valve 16 that is relatively lifted out of the two intake valves 16 and 16 that operate independently of each other. Thus, the first intake valve side rocker arm 33 can be reduced in weight by the absence of the hydraulic pressure chamber 72 and the communication passage 73. Therefore, the spring load for biasing the first intake valve side rocker arm 33 is set to be relatively low. This can contribute to reduction of valve opening power.
[0032]
  Further, in the third intake valve side rocker arm 35 provided with the hydraulic chamber 72 and the communication path 73, the axial length of the rotating body 46> the axial length of the rotating body 45> the axial length of the rotating body 47. Therefore, even if the hydraulic chamber 72 and the communication passage 73 are provided, the width along the axis of the intake valve side rocker arm shaft 37 can be set to be relatively small, whereby the third intake valve side rocker arm 35 of the third intake valve side rocker arm 35 can be set. The increase in weight can be suppressed and the valve opening power can be reduced, and the valve gear can be configured relatively compactly along the axis of the camshaft 26.
[0033]
  Although the embodiments of the present invention have been described in detail 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. Is possible.
[0034]
【The invention's effect】
  As described above, according to the present invention, the interlocking switching mechanism includes a switching pin that is movable between a position where the adjacent intake valve driving member is interlocked and a position where the interlocking is released, and a plurality of switching pins to guide the movement of the switching pin. A cylindrical shaft member for an intake valve fixed to each intake valve drive member, and disposed on the opposite side of the intake valve as viewed from the intake side swing support shaft. Since the cylindrical rotating body slidingly contacting the intake valve cam on the camshaft is rotatably supported, it is necessary to provide an interlocking switching mechanism at or near the intake valve side end of each intake valve drive member. Therefore, the space for arranging the components such as the valve spring support retainer around the upper end of the intake valve can be sufficiently secured without being affected by the interlocking switching mechanism. Setting degree of lift amount The height of the valve mechanism can be reduced by using the space above the camshaft, which is located below the intake-side swing support shaft. In addition, since the thickness (particularly in the vertical direction) of the intake valve drive member holding the interlocking switching mechanism can be sufficiently secured, it is effective in preventing deformation of the member, and the interlocking This also contributes to improving the reliability of the switching operation of the switching mechanism.
[0035]
  A lost motion mechanism that elastically biases a specific intake valve drive member that is free to the intake valve to the cam side when the interlock switching mechanism is in the interlock release state is for the camshaft coupled to the cylinder head. Suction fixed to the holder, supported by a support plate located above the exhaust valve drive member,in frontSince the lost motion mechanism is in contact with the outer surface of the intermediate portion between the intake valve cylindrical shaft member and the intake side swing support shaft of the specific intake valve drive member, the specific intake valve is interposed between the camshaft and the support plate. While the valve drive member and the lost motion mechanism are arranged in a compact and compact manner as much as possible, the urging force from the lost motion mechanism can be directly received at the intermediate portion of the intake valve drive member, and the urging force is taken into the intake air. In addition to being able to efficiently transmit to the valve drive member, it is not necessary to extend the lost motion receiving seat from one end of the intake valve drive member, and as a result, the height of the valve operating device can be reduced as a whole. As a result, the intake valve drive member itself can be simplified in structure and reduced in size, and the inertial mass can be reduced, which in turn contributes to higher engine output..
[Brief description of the drawings]
FIG. 1 is a side view of a V-type internal combustion engine.
FIG. 2 is an enlarged cross-sectional view taken along line 2-2 in FIG.
3 is a cross-sectional view taken along line 3-3 in FIG.
4 is a cross-sectional view taken along line 4-4 of FIG.
5 is a cross-sectional view taken along line 5-5 in FIG.
[Explanation of symbols]
16 .... Intake valve
20. Exhaust valve
26 ・・・・・・ Camshaft
28 ・・・・・・ Holder
29, 30, 31 .. Cam for intake valve
32 ... Exhaust valve cam
33, 34, 35... Intake valve side rocker arm as intake valve drive member
36 ・・・・・・ Interlocking switching mechanism
37 .... Intake valve side rocker arm shaft as intake side swing support shaft
38... Exhaust valve side rocker arm as exhaust valve drive member
39... Exhaust valve side rocker arm shaft as exhaust side swing support shaft
45, 46, 47 .. Rotating body
52, 53, 54 .. Cylindrical shaft member for intake valve
59 ・・・・・・ Cylindrical shaft member for exhaust valve
61 ・・・・・・ Support plate
62 ... Lost motion mechanism
68, 69 ... switching pin

Claims

A single camshaft (26) common to the intake valve (16) and the exhaust valve (20) has a cylinder head (9) and a plurality of holders (28) coupled on the head (9). A plurality of intake valve driving members (33) having an interlocking switching mechanism (36) that can be switched between interlocking and interlocking release between the camshaft (26) and the intake valve (16). , 34, 35) are arranged so as to be swingable via an intake side swing support shaft (37) supported by a holder (28) above the camshaft (26), and the camshaft (26). Between the exhaust valves (20), exhaust valve driving members (38) individually corresponding to the respective exhaust valves (20) are supported on the holder (28) above the camshaft (26). The plurality of intake valves are disposed so as to be swingable via a movable support shaft (39). Among the moving members (33, 34, 35), the cam (29 The lost motion mechanism (62) that is elastically biased toward the) side is fixed to the holder (28) and is positioned above the intake valve drive member (33, 34, 35) and the exhaust valve drive member (38) In the SOHC type valve gear for an internal combustion engine, supported by the plate (61),
The interlock switching mechanism (36) includes a switching pin (68, 69) movable between a position where the adjacent intake valve driving members (34, 35; 33, 34) are interlocked and a position where the interlock is released. Intake valve cylindrical shaft members (54, 53, 52) fixed to a plurality of intake valve drive members (35, 34, 33) to guide the movement of the pins (68, 69). The camshaft (26) is disposed on the opposite side of the intake valve (16) as viewed from the intake-side swing support shaft (37), and on each cylindrical shaft member (54, 53, 52). A cylindrical rotating body (47, 46, 45) slidably contacting the intake valve cam (31, 29, 30) is rotatably supported.
Before Symbol particular intake valve driving member (34), wherein the lost motion mechanism (62) comes into contact with the intermediate part upper surface of the cylindrical shaft member for the intake valve (53) and the intake side rocking shaft (37) An SOHC type valve operating apparatus for an internal combustion engine .