JP4183378B2 - Direct acting valve gear for internal combustion engine - Google Patents

Direct acting valve gear for internal combustion engine Download PDF

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Publication number
JP4183378B2
JP4183378B2 JP2000335160A JP2000335160A JP4183378B2 JP 4183378 B2 JP4183378 B2 JP 4183378B2 JP 2000335160 A JP2000335160 A JP 2000335160A JP 2000335160 A JP2000335160 A JP 2000335160A JP 4183378 B2 JP4183378 B2 JP 4183378B2
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cam
valve
intake
exhaust
valve lifter
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JP2002138808A (en
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徳明 藤井
弘 中村
純一 岩本
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2307/00—Preventing the rotation of tappets

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  • Valve-Gear Or Valve Arrangements (AREA)
  • Valve Device For Special Equipments (AREA)

Description

【０００１】
【発明の属する技術分野】
本願発明は、内燃機関に設けられた吸気または排気を司る機関弁である吸気弁または排気弁の弁作動特性を選択的に切り換える切換手段を備えた内燃機関の直動式動弁装置に関する。
【０００２】
【従来の技術】
従来、内燃機関の吸気弁または排気弁の弁作動特性を選択的に切り換える切換手段を備えた動弁装置として、本出願人による出願である特願２０００−１８９４８９号に開示されたものがある。この先願の動弁装置は、吸気カム軸に設けられ、カムプロフィールが異なる複数のカムである低速カムと高速カムとが隣接して設けられた吸気可変カム部を有する吸気カム駒と、排気カム軸に設けられ、カムプロフィールが異なる複数のカムである低速カムと高速カムとが隣接して設けられた排気可変カム部を有する排気カム駒と、吸気可変カム部および排気可変カム部の低速カムまたは高速カムに当接する吸気ロッカアームおよび排気ロッカアームと、カム軸に対して移動自在な吸気カム駒および排気カム駒を、カム軸の回転軸線方向に移動させる駆動機構とを備える。そして、吸気カム駒および排気カム駒が前記回転軸線方向に移動することで、吸気カム駒および排気カム駒の低速カムまたは高速カムに選択的に当接して揺動される吸気ロッカアームおよび排気ロッカアームにより、吸気弁および排気弁が、それぞれ低速カムまたは高速カムのカムプロフィールに応じて作動される。
【０００３】
【発明が解決しようとする課題】
ところで、前記先願には、動弁装置は直動式のものであってもよい旨の開示があり、それによって、高速回転時の吸気弁および排気弁の作動応答性が向上し、また動弁室の高さを低くできて内燃機関がコンパクトとなる等の利点が得られる。しかしながら、直動式動弁装置において、カムプロフィールの異なる複数のカムが隣接して設けられた吸気カム駒および排気カム駒により、それぞれ吸気弁および排気弁を作動させるに当たっては、吸気弁（または排気弁）のバルブリフタ、と吸気可変カム部（または排気可変カム部）の、該バルブリフタと当接していないカム、特に低速カムに比べて大きな突出量で突出した高速カムとの干渉や、該バルブリフタと、各カム駒をカム軸の回転軸線方向に移動させる駆動機構との干渉を、動弁装置を大型化することなく、いかにして回避するかが問題となる。
【０００４】
本願発明は、このような事情に鑑みてなされたものであり、請求項１ないし請求項５記載の発明は、カムプロフィールの異なる複数のカムがカム軸の回転軸線方向に設けられたカム駒および切換手段を合わせたときの該回転軸線方向での寸法を小さくすることが可能となって、コンパクトでかつ軽量な直動式動弁装置を提供することを共通の目的とする。さらに、請求項１〜５記載の発明は、バルブリフタを軽量化すると共に機関弁の潤滑を容易にする直動式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および発明の効果】
本願の請求項１記載の発明は、カム軸と共に回転するカム駒であって、カムプロフィールの異なる複数のカムが前記カム軸の回転軸線方向に隣接して設けられたカム部を有するカム駒と、前記カム部と内燃機関の吸気または排気を司る機関弁との間に配置されたバルブリフタと、前記カム部の、前記バルブリフタに摺接するカムを選択的に切り換える切換手段とを備え、前記機関弁が摺接する前記カムのカムプロフィールに応じて作動される内燃機関の直動式動弁装置において、前記バルブリフタには、前記カム部の、前記バルブリフタに対して非接触状態にあるカムに対する逃げ用の切欠部が設けられ、前記切欠部は、前記バルブリフタを貫通して内側と外側とを連通させる孔により形成される内燃機関の直動式動弁装置である。
【０００６】
この請求項１記載の発明によれば、カム駒の、バルブリフタに摺接するカムに隣接する非接触状態にあるカムは、バルブリフタと干渉することなく、バルブリフタの切欠部を通過して回転する。その結果、次の効果が奏される。すなわち、カムプロフィールの異なる複数のカムが隣接して設けられたカム駒の一つのカムがバルブリフタと摺接して機関弁を作動させるとき、該摺接するカムに隣接するカムはバルブリフタの切欠部を通過するので、該摺接するカムに隣接するカムの少なくとも一部を、バルブリフタのカム軸の回転軸線方向での幅の範囲内に位置させることが可能となって、カム駒の前記回転軸線方向での幅を小さくすることができて、動弁装置がコンパクトでかつ軽量になり、ひいては内燃機関がコンパクトでかつ軽量になる。さらに、カム駒の前記回転軸線方向での寸法が小さいことで、同一シリンダに対して、吸気または排気を司る複数の機関弁が設けられる場合にも、限られたシリンダのボア径の範囲内で、それら複数の機関弁に対するカム駒の適用が容易であり、そのうえ、カム駒に３以上のカムを設けることも容易になる。
さらに、バルブリフタに設けられた孔からなる切欠部を通じて、バルブリフタの外側の潤滑油がバルブリフタの内側に侵入して、バルブリフタの内側に配置される弁ばね、リテーナおよび機関弁の摺動部に潤滑油が容易に供給される。また、孔が形成されることで、バルブリフタの一部が切除されるため、バルブリフタが軽量となる。その結果、切欠部を通じてバルブリフタの内側の摺動部に潤滑油を容易に供給できるので、該摺動部の耐久性が向上する。さらに、切欠部の形成によりバルブリフタの一部が切除されるため、バルブリフタが軽量化され、ひいては内燃機関の軽量化ができる。
【０００７】
請求項２記載の発明は、請求項１記載の内燃機関の直動式動弁装置において、前記カム駒は前記カム軸に対して前記回転軸線方向に移動自在であり、前記切換手段は、前記カム部の前記回転軸線方向での側面に当接する操作部材と、該操作部材を介して前記カム駒を前記回転軸線方向に移動させて、前記バルブリフタに摺接する前記カムを切り換える駆動部材とを備え、前記バルブリフタには、前記操作部材に対する逃げ用の切欠部が設けられた内燃機関の直動式動弁装置である。
【０００８】
この請求項２記載の発明によれば、操作部材は、カム部の前記回転軸線方向での側面において、カムのベース円部よりも径方向外方に突出する位置で当接したとしても、切欠部内に位置するので、バルブリフタと接触することはない。その結果、引用された請求項記載の発明の効果に加えて、次の効果が奏される。すなわち、カム部の側面に当接する操作部材は、バルブリフタと接触することなく、しかもカム部の側面において、カムのベース円部よりも径方向内側のみで当接させる必要がないうえ、カムのベース円部よりも径方向外方に突出する位置で該側面に当接したとしても、操作部材をバルブリフタのカム軸の回転軸線方向での幅の範囲内に位置させることが可能となって、カム駒と操作部材を有する切換手段と合わせた前記回転軸線方向での幅を小さくすることができて、動弁装置がコンパクトでかつ軽量になり、ひいては内燃機関がコンパクトでかつ軽量になる。さらに、カム部の側面をバルブリフタの前記回転軸線方向での幅の範囲内に位置させることができるため、カム部の側面に当接する操作部材を有する切換手段が、カム駒の回転軸線方向での幅の短縮化による動弁装置のコンパクト化を妨げることがない。また、カム部の側面での操作部材の当接部分を設定するに当たり、操作部材とバルブリフタとの位置関係からの制約が少なくなり、操作部材の配置の自由度、ひいては切換手段の配置の自由度が大きくなる。
【０００９】
請求項３記載の発明は、請求項２記載の内燃機関の直動式動弁装置において、前記操作部材に対する逃げ用の前記切欠部は、前記バルブリフタを貫通して内側と外側とを連通させる孔により形成されるものである。
【００１０】
この請求項３記載の発明によれば、バルブリフタに設けられた孔からなるカムに対する逃げ用切欠部および操作部材に対する逃げ用の切欠部を通じて、バルブリフタの外側の潤滑油がバルブリフタの内側に侵入して、バルブリフタの内側に配置される弁ばね、リテーナおよび機関弁の摺動部に潤滑油が容易に供給される。また、孔が形成されることで、バルブリフタの一部が切除されるため、バルブリフタが軽量となる。その結果、引用された請求項記載の発明の効果に加えて、次の効果が奏される。すなわち、切欠部を通じてバルブリフタの内側の摺動部に潤滑油を容易に供給できるので、該摺動部の耐久性が向上する。さらに、切欠部の形成によりバルブリフタの一部が切除されるため、バルブリフタが軽量化され、ひいては内燃機関の軽量化ができる。
【００１１】
請求項４記載の発明は、請求項１または請求項３記載の内燃機関の直動式動弁装置において、前記切欠部は、前記バルブリフタの頂壁から前記回転軸線方向での両側でバルブリフタの側壁に渡って、前記頂壁の一部および前記側壁の一部が切除されて形成された１対の切欠部であるものである。
【００１２】
請求項５記載の発明は、請求項４記載の内燃機関の直動式動弁装置において、前記バルブリフタの前記頂壁は、前記１対の切欠部の間を前記頂壁の直径方向に延びるブリッジ状のスリッパ部を形成し、前記カムが摺接する前記スリッパ部の摺接面は、前記回転軸線方向から見たとき、前記カム部に向かって凸となる円弧になっているものである。
この請求項５記載の発明によれば、引用された請求項記載の効果に加えて、次の効果が奏される。すなわち、スリッパ部の摺接面が、カム部に向かって凸となる円弧になっていることから、それら摺接面が平面である場合に比べてバルブリフタの径を小さくすることができ、シリンダヘッドを小型化できる。また、スリッパ部の側方に貫通孔からなる１対の切欠部が設けられるにも拘わらず、スリッパ部の必要な剛性を、スリッパ部を厚肉にするなどの重量増を招くことなく、軽量化を達成しつつ確保できる。
【００１３】
【発明の実施の形態】
以下、本願発明の実施例を図１ないし図８を参照して説明する。
本願発明の直動式動弁装置が適用される内燃機関Ｅは、車両に搭載されるＤＯＨＣ型の直列４気筒４サイクル内燃機関であり、図１に図示されるように、該内燃機関Ｅは、４つのシリンダ１（図１ではその１つが示されている）が一体化されたシリンダブロック２の上面にシリンダヘッド３が、さらにシリンダヘッド３の上面にヘッドカバー４がそれぞれ組み付けられる。各シリンダ１のボア1a内に往復動自在に嵌合されたピストン５は、コンロッド（図示されず）を介してクランク軸（図示されず）に連結され、該クランク軸に同期して１／２の減速比で回転駆動される吸気カム軸６および排気カム軸７が、シリンダ配列方向に互いに平行に配置され、シリンダヘッド３にボルトにより固定される５つのカムホルダ８（図１ではその１つが示されている）に回転自在に支持される。それらのカムホルダ８は、前記シリンダ配列方向の両端部および隣り合うシリンダ１の間に配置され、各カムホルダ８は、吸気カム軸６の回転軸線L1および排気カム軸７の回転軸線L2を含む平面で上下に分割された１対の上カムホルダ8Uおよび下カムホルダ8Lからなる。
【００１４】
シリンダヘッド３には、シリンダ１毎に、ピストン５との間に燃焼室９が形成されると共に、燃焼室９に開口する１対の吸気口を有する吸気ポート10および１対の排気口を有する排気ポート11が設けられ、さらに前記１対の吸気口をそれぞれ開閉して、内燃機関Ｅの吸気を司る１対の機関弁である第１吸気弁12aおよび第２吸気弁12b（図２参照）と、前記１対の排気口をそれぞれ開閉して、内燃機関Ｅの排気を司る１対の機関弁である第１排気弁13aと第２排気弁（図示されず）とが弁ガイド14a，15aに摺動自在に設けられる。そして、第１，第２吸気弁12a，12bおよび第１排気弁13a，第２排気弁は、それぞれ、その弁ステム16a，17aの上端部に設けられたリテーナ18a，18b，19aとシリンダヘッド３との間に圧縮状態で装着された弁ばね20a，20b，21aによって、閉弁方向に付勢される。また、シリンダヘッド３には、燃焼室９内の略中央に臨む点火栓22が螺着される。
【００１５】
シリンダヘッド３とヘッドカバー４との間に形成された動弁室23には、吸気弁12a，12bおよび排気弁13aを開閉作動させるための直動式動弁装置Ｖが収納される。この動弁装置Ｖは、吸気カム軸６、吸気カム駒30、吸気バルブリフタ32a，32b、および吸気カム駒30を吸気カム軸６の回転軸線L1方向に移動させる吸気側切換手段としての油圧式の吸気側駆動機構ＭINを備える吸気側動弁装置ＶINと、排気カム軸７、排気カム駒31、排気バルブリフタ33a、および排気カム駒31を排気カム軸７の回転軸方向に移動させる排気側切換手段としての油圧式の排気側駆動機構ＭEXを備える排気側動弁装置ＶEXとからなる。そして、吸気側動弁装置ＶINおよび排気側動弁装置ＶEXは、基本的に同一の構成を有するものであるので、以下の説明では、吸気側動弁装置ＶINを中心に説明する。
【００１６】
図２も併せて参照すると、吸気カム軸６には、シリンダ１毎に、吸気カム軸６が貫通する軸孔34を有する吸気カム駒30が、吸気カム軸６に対して回転軸線L1方向に摺動して移動自在に、かつ回転方向に吸気カム軸６と共に一体に回転するようにスプライン結合される。そのため、この実施例では、吸気カム駒30の内周面には、回転軸線L1方向の全長に渡って、３条の凹溝35が周方向に等間隔で、かつ回転軸線L1と平行に設けられ、吸気カム軸６の外周面には、回転軸線L1方向に吸気カム駒30の移動範囲に等しい長さに渡って、３条の凹溝35にそれぞれ係合する３条の突条36が設けられる。
【００１７】
吸気カム駒30には、回転軸線L1方向に直列にかつ離隔して第１吸気カム部37aおよび第２吸気カム部37bとが設けられ、第１，第２吸気カム部37a，37bには、それぞれカムプロフィールの異なる低速カム38a，38bと高速カム39a，39bとが回転軸線L1方向に隣接して一体に設けられる。すなわち、各低速カム38a，38bは、吸気カム軸６の径方向（以下、単に「径方向」という）に比較的小さい突出量で、その周方向に所定の作動角を有するノーズ部と、ベース円部とから構成されるカムプロフィールを有し、各高速カム39a，39bは、径方向の突出量が低速カム38a，38bのノーズ部の突出量より大きく、かつ低速カム38a，38bの作動角よりも大きい作動角を有するノーズ部と、低速カム38a，38bのベース円部と等しい径方向の突出量を有するベース円部とから構成されるカムプロフィールを有する。
【００１８】
さらに、吸気カム駒30には、低速カム38a，38bおよび高速カム39a，39bのベース円部よりも薄い径方向の厚さを有し、吸気カム駒30の、回転軸線L1方向での一側面を構成する第１吸気カム部37aの低速カム38a側の第１側面40a、および回転軸線L1方向での他側面を構成する第２吸気カム部37bの高速カム39b側の第２側面40bの両側面からそれぞれ回転軸線L1方向に延びる第１円筒部41aおよび第２円筒部41bが設けられる。
【００１９】
また、吸気カム駒30よりも下方において、シリンダ１毎に、第１吸気カム部37aと第１吸気弁12aとの間には第１吸気バルブリフタ32aが配置され、第２吸気カム部37bと第２吸気弁12bとの間には第２吸気バルブリフタ32bが配置される。そして、第１，第２吸気バルブリフタ32a，32bは、シリンダヘッド３に設けられたリフタ孔に、それぞれ弁ステム16a，16bの軸線方向に摺動自在に嵌合される。
【００２０】
各吸気バルブリフタ32a，32bは、下端が開放し、上端に頂壁を有する円筒を、該円筒の軸線を含み、かつ吸気カム軸６の回転軸線L1と直交する直交平面に関して面対称となるように、頂壁から回転軸線L1方向での両側で、該円筒の長さの略中央までの側壁を切除した形状を有する。したがって、各吸気バルブリフタ 32a ， 32b の頂壁から回転軸線 L1 方向での両側で各吸気バルブリフタ 32a ， 32b の側壁に渡って、頂壁の一部および側壁の一部が切除されたことにより形成される１対の切欠部42a1，42a2，42b1，42b2は、各吸気バルブリフタ32a，32bの外側と内側を連通する貫通孔となっており、この貫通孔を通じて動弁室23に供給された潤滑油が、各吸気バルブリフタ32a，32bの内側に侵入して、弁ばね20a，20b、リテーナ18a，18bおよび弁ステム16a，16bの摺動部を潤滑する。
【００２１】
そして、頂壁の残された部分は、低速カム38a，38bおよび高速カム39a，39bが摺接するブリッジ形状のスリッパ部43a，43bを形成し、前記直交平面と平行に延びる両側端面を有して１対の切欠部 42a1 ， 42a2 ， 42b1 ， 42b2 の間を頂壁の直径方向に延びている。このスリッパ部43a，43bは、低速カム38a，38bおよび高速カム39a，39bの回転軸線L1方向での幅よりもやや小さい回転軸線L1方向での幅を有し、その外表面である摺接面43a1，43b1は、頂壁の外表面が、吸気カム軸６の回転軸線L1と平行で、かつ前記円筒の軸線を含む平面上に軸線を有すると共に、各吸気カム部37a，37bに向かって凸となる円筒面からなる曲面をなすことから、回転軸線L1方向から見たとき、各吸気カム部37a，37bに向かって凸となる円弧になっている。
【００２２】
また、切欠部42a2，42b2は、図３に図示されるように、第１，第２吸気カム部37a，37bの低速カム38a，38bがスリッパ部43a，43bに摺接しているとき、低速カム38a，38bのノーズ部よりも大きく径方向に突出する高速カム39a，39bのノーズ部が、第１，第２吸気バルブリフタ32a，32bとそれぞれ接触することなく通過する大きさに設定されて、高速カム39a，39bに対する逃げのための切欠部となっている。そして、両吸気カム部37a，37bの回転軸線L1方向での幅、すなわち低速カム38a，38bおよび高速カム39a，39bの回転軸線L1方向での幅の合計は、各吸気バルブリフタ32a，32bの回転軸線L1方向での幅よりも小さくされる。さらに、切欠部42a1，42a2，42b1，42b2内には、切欠部42a2，42b2を通過する高速カム39a，39bのノーズ部の最大突出部に近接した位置にリテーナ18a，18bが位置するようにされて、弁ステム16a，16bの端部とスリッパ部43a，43bの摺接面43a1，43b1との間の間隔を極力小さくして、動弁装置Ｖのコンパクト化を図っている。
【００２３】
さらに、図１および図２を参照すると、第１，第２吸気バルブリフタ32a，32bの側壁には、前記リフト孔の周壁面に弁ステム16a，16bの軸線に平行に延びて形成された第１案内溝24aおよび第２案内溝にそれぞれ係合する第１ピン44aおよび第２ピン44bが設けられる。第１案内溝24aおよび第２案内溝は、第１ピン44aおよび第２ピン44bとの係合により各吸気バルブリフタ32a，32bの回り止めを行う一方で、吸気バルブリフタ32a，32bの弁ステム16a，16bの軸線方向への往復動を許容する。また、排気バルブリフタにも、シリンダヘッド３に形成された案内溝に係合するピンが設けられ、図１には、第１案内溝25aおよび第１ピン45aが示されている。
【００２４】
それゆえ、吸気側駆動機構ＭINにより回転軸線L1方向に移動される吸気カム駒30により、第１，第２吸気カム部37a，37bの低速カム38a，38bおよび高速カム39a，39bがスリッパ部43a，43bに選択的に摺接し、第１，第２吸気弁12a，12bは、低速カム38a，38bまたは高速カム39a，39bにより押圧される第１，第２吸気バルブリフタ32a，32bを介して、摺接するカムのカムプロフィールに応じて作動して、それぞれのカムのノーズ部で設定されるリフト量および開閉時期で、前記吸気口を開閉する。
【００２５】
次に、図２、図５および図６を参照して、シリンダ１毎に設けられる吸気側駆動機構ＭINについて説明すると、該吸気側駆動機構ＭINは、吸気カム駒30の両側方にそれぞれ位置して隣り合う上カムホルダ8Uの互いに対向する向きに突出したボス部において、吸気カム軸６よりもシリンダ１の中心軸線寄りに互いに対向して設けられた円柱状の凹部を有する第１シリンダ部51aおよび第２シリンダ部51bと、該両シリンダ部51a，51bに両端部がそれぞれ摺動自在に嵌合して支持される円柱状の第１ピストン部52aおよび第２ピストン部52bを有する可動部材としての複動型の駆動ピストン50と、駆動ピストン50の中心軸線方向の延びて両ピストン部52a，52bを連結する連結部53において、該連結部53と共に両ピストン部52a，52bと一体成形されて連結部53から吸気カム軸６に向かって延びる操作部材である１対のアーム54a，54bとを備える。ここで、駆動ピストン50の中心軸線は、吸気カム軸６の回転軸線L1と平行であり、しかも第１，第２シリンダ部51a，51bのそれぞれの中心軸線と一致している。
【００２６】
そして、第１ピストン部52aと第１シリンダ部51aとの間には第１油圧室55aが、また第２ピストン部52bと第２シリンダ部51bとの間には第２油圧室55bが、それぞれ形成され、駆動ピストン50は、両油圧室55a，55bに供給される作動油の油圧に応じた駆動力を受けて、駆動ピストン50の中心軸線に沿って往復動する。
【００２７】
駆動ピストン50の中心軸線方向に、吸気カム駒30における第１側面 40a と第２側面 40 との、回転軸線L1方向での間隔よりも僅かに大きな間隔をおいて設けられた１対のアーム54a，54bは、第１側面40aの側方に位置する第１アーム54aと、第２側面40bの側方に位置する第２アーム54bからなる。そして、第１，第２アーム54a，54bは、第１，第２円筒部41a，41bをそれぞれ円弧状に囲む二股となったフォーク状の１対の操作部56a1，56a2および１対の操作部56b1，56b2をそれぞれ備える。
【００２８】
第１アーム54aの両操作部56a1，56a2の先端部は、第１吸気カム部37aの低速カム38aの第１側面40aに当接すると共に第１円筒部41aの外周面に当接する１対の第１当接部57a1，57a2をそれぞれ有し、両第１当接部57a1，57a2は、回転軸線L1からの距離が等しい位置で、かつ吸気カム軸６の直径方向に対向する位置で第１側面40aおよび第１円筒部41aの外周面に当接する。同様に、第２アーム54bの両操作部56b1，56b2の先端部は、第２吸気カム部37bの高速カム39bの第２側面40bに当接すると共に第２円筒部41bの外周面に当接する１対の第２当接部57b1，57b2をそれぞれ有し、両第２当接部57b1，57b2は、回転軸線L1からの距離が等しい位置で、かつ吸気カム軸６の直径方向に対向する位置で第２側面40bおよび第２円筒部41bの外周面に当接する。
【００２９】
また、駆動ピストン50において、第１アーム54aと第２アーム54bとの間の部分には、回転する両低速カム38a，38bおよび両高速カム39a，39bが連結部53に食い込んだ状態で、それら低速カム38a，38bおよび高速カム39a，39bの通過を許容する湾曲した凹部57（図１も参照）が設けられる。
【００３０】
次に、吸気側駆動機構ＭINの油圧系統について説明すると、内燃機関Ｅに設けられてクランク軸の動力により駆動されるオイルポンプの吐出路に、シリンダブロック２、シリンダヘッド３およびカムホルダ８に設けられて第１油圧室55aに開口部58aを有する作動油路（図示されず）が連通され、該作動油路に設けられた第１制御弁（図示されず）により、第１油圧室55aの作動油圧が高油圧または低油圧に制御される。同様に、第２油圧室55bに開口部58bを有する第２作動油路（図示されず）に設けられた第２制御弁（図示されず）により、第２油圧室55bの作動油圧が高油圧または低油圧に制御される。
【００３１】
第１，第２制御弁は、図示されない機関運転状態センサである回転速度センサにより検出された信号が入力される制御装置（図示されず）によりその作動が制御される。すなわち、内燃機関Ｅの所定回転速度以下の低速回転域において、第１制御弁は、第１油圧室55a内の作動油が高油圧となるように作動油の油圧を制御し、第２制御弁は、第２油圧室55b内の作動油が低油圧となるように作動油の油圧を制御する。このため、第１油圧室55a内の油圧と第２油圧室55b内の油圧との油圧差により、駆動ピストン50は吸気カム駒30を軸方向に移動させて、該吸気カム駒30は、両低速カム38a，38bが第１，第２吸気バルブリフタ32a，32bのスリッパ部43a，43bに摺接する、図５に図示される低速位置を占める。このとき、図３に図示されるように、第１吸気カム部37aの低速カム38aの第１側面40aに当接して、第１円筒部41aを囲む１対の操作部56a1，56a2のうち、第１吸気バルブリフタ32a寄りの操作部56a2および当接部57a2は、低速カム38aのベース円部よりも径方向に突出しているにも拘わらず、切欠部42a1に位置するため、第１吸気バルブリフタ32aと接触することがない。それゆえ、切欠部42a1は、操作部56a2および当接部57a2、ひいては第１アーム54aに対する逃げのための切欠部ともなっている。
【００３２】
そして、内燃機関Ｅの回転速度が前記所定回転速度を越えて高速回転域になると、第１制御弁は、第１油圧室55aが低油圧となるように作動油の油圧を制御し、第２制御弁は、第２油圧室55bが高油圧となるように作動油の油圧を制御する。このため、第１油圧室55a内の油圧と第２油圧室55b内の油圧との油圧差により、駆動ピストン50INは吸気カム駒30を軸方向に移動させて、該吸気カム駒30は、両高速カム39a，39bが第１，第２吸気バルブリフタ32a，32bのスリッパ部43a，43bに摺接する、図６に図示される高速位置を占める。そして、このとき、図４に図示されるように、第２吸気カム部37bの高速カム39bの第２側面40bに当接して、第２円筒部41bを囲む１対の操作部56b1，56b2のうち、第２吸気バルブリフタ32b寄りの操作部56b2および当接部57b2は、高速カム39bのベース円部よりも径方向に突出しているにも拘わらず、切欠部42b2に位置するため、第２吸気バルブリフタ32bと接触することがない。それゆえ、切欠部42b2は、操作部56b2および当接部57b2、ひいては第２アーム54bに対する逃げのための切欠部ともなっている。
【００３３】
ここで、第１，第２吸気バルブリフタ32a，32bの、低速カム38a，38bの摺接よる押圧から高速カム39a，39bの摺接による押圧への移行、および高速カム39a，39bの摺接よる押圧から低速カム38a，38bの摺接による押圧への移行は、スリッパ部43a，43bの接触部が、低速カム38a，38bのベース円部または高速カム39a，39bのベース円部に摺接している時期に行われるように、駆動ピストン50が受ける駆動力が設定される。
【００３４】
また、図５および図６に図示されるように、隣り合うシリンダ１の間に位置するカムホルダ８には、該カムホルダ８の回転軸線L1方向での中央点を通り、かつ該回転軸線L1に直交する平面に関して、同図の右側にあるシリンダ１に属する第１油圧室55aと、上カムホルダ8Uを挟んでその左側にあるシリンダ１に属する第１油圧室55aとが、面対称となるように配置され、両油圧室55a，55aで作動油路が共用されている。このことは、隣り合うシリンダ１間に位置する他のカムホルダ８およびシリンダ１に属する動弁装置Ｖの構成要素についても同様である。
【００３５】
なお、排気側動弁装置ＶEXの排気側駆動機構ＭEXの油圧系統も、前述の吸気側駆動機構ＭINと同様にして、制御された作動油が供給されるようになっている。
【００３６】
次に、図３ないし図６を参照して、前述のように構成された実施例の作用について説明する。
内燃機関Ｅの運転が開始されてオイルポンプが作動している状態で、内燃機関Ｅの回転速度が前記所定回転速度以下の低速回転域にあるとき、吸気側動弁装置ＶINでは、制御装置の指令により、第１制御弁は、第１油圧室55a内の作動油が高油圧となるように作動し、同時に第２制御弁は、第２油圧室55b内の作動油が低油圧となるように作動する。そのため、吸気側駆動機構ＭINの駆動ピストン50は、内燃機関Ｅの運転開始前の状態でもある図５に図示される低速位置を占める。そのため、吸気カム駒30の第１，第２吸気カム部37a，37bの低速カム38a，38bが、第１，第２吸気バルブリフタ32a，32bのスリッパ部43a，43bにそれぞれ摺接する。そして、排気側駆動機構ＭEXの駆動ピストンも吸気側駆動機構ＭINと同様に、内燃機関Ｅの運転開始前の状態でもある低速位置を占める。それゆえ、各シリンダ１における第１，第２吸気弁12a，12b、第１排気弁13aおよび第２排気弁は、低速回転域の弁作動特性に適合した小リフト量、開閉時期および短い開弁期間で開閉される。また、このとき、図３に図示されるように、低速カム38a，38bのノーズ部よりも大きく径方向に突出する高速カム39a，39bのノーズ部は、第１，第２吸気バルブリフタ32a，32bとそれぞれ接触することなく、切欠部42a2，42b2を通過して回転する。そして、第１吸気バルブリフタ32a寄りの操作部56a2および当接部57a2は、低速カム38aのベース円部よりも径方向に突出しているにも拘わらず、切欠部42a1に位置するため、第１吸気バルブリフタ32aと接触することがない。また、このことは、排気側動弁装置ＶEXにおいても同様である。
【００３７】
そして、内燃機関Ｅの回転速度が前記所定回転速度を越えて、高速回転域に移行すると、制御装置からの指令により、第１制御弁は、第１油圧室55a内の作動油が低油圧となるように作動し、同時に第２制御弁は、第２油圧室55b内の作動油が高油圧となるように作動する。そのため、吸気側駆動機構ＭINの駆動ピストン50は、低速位置から、図６に図示される高速位置に移動する駆動力を受ける。
【００３８】
このとき、第１，第２吸気バルブリフタ32a，32bのスリッパ部43a，43bが低速カム38a，38bのベース円部に摺接していれば、駆動ピストン50が、直ちに移動し、同時に第２アーム54bの１対の当接部57b1，57b2を介して駆動力が作用する吸気カム駒30は回転軸線L1方向に移動し、吸気カム駒30は、図６に図示されるように、高速カム39a，39bが第１，第２吸気バルブリフタ32a，32bに摺接する位置を占める。
【００３９】
また、駆動ピストン50が、低速位置から高速位置に移動する駆動力を受けたとき、各スリッパ部43a，43bが低速カム38a，38bのノーズ部に摺接していれば、その後の吸気カム軸６の回転により、各スリッパ部43a，43bが低速カム38a，38bのベース円部に摺接した直後に駆動ピストン50が高速位置に向けて移動し、同時に第２アーム54a，54bの当接部57b1，57b2を介して駆動力が作用する吸気カム駒30は、高速カム39a，39bが各スリッパ部43a，43bに摺接する高速位置に向けて回転軸線L1方向に移動する。そのため、高速回転域では、吸気カム駒30の第１，第２吸気カム部37a，37bの高速カム39a，39bが、第１，第２吸気バルブリフタ32a，32bのスリッパ部43a，43bにそれぞれ摺接する。そして、排気側駆動機構ＭEXの駆動ピストンも吸気側駆動機構ＭINと同様に、高速位置を占める。それゆえ、各シリンダ１における第１，第２吸気弁12a，12b、第１排気弁13aおよび第２排気弁は、高速回転域の弁作動特性に適合した大リフト量、開閉時期および長い開弁期間で開閉される。また、このとき、図４に図示されるように、第２吸気バルブリフタ32b寄りの操作部56b2および当接部57b2は、高速カム39bのベース円部よりも径方向に突出しているにも拘わらず、切欠部42b2に位置するため、第２吸気バルブリフタ32bと接触することがない。また、このことは、排気側動弁装置ＶEXにおいても同様である。
【００４０】
さらに、高速回転域から低速回転域に移行するときは、第１，第２制御弁により、第１油圧室55a内の作動油が高油圧となり、同時に第２油圧室55b内の作動油が低油圧となる。そのため、第１油圧室55a内の油圧と第２油圧室55b内の油圧との油圧差により、吸気側駆動機構ＭINの駆動ピストン50は、高速位置から低速位置に移動する駆動力を受ける。その際、第１，第２吸気バルブリフタ32a，32bのスリッパ部43a，43bが高速カム39a，39bのベース円部に摺接していれば、直ちに、また各スリッパ部43a，43bが高速カム39a，39bのノーズ部に摺接していれば、各スリッパ部43a，43bが高速カム39a，39bのベース円部に摺接した直後に、駆動ピストン50が低速位置に向けて移動し、同時に第１アーム54aの当接部57a1，57a2を介して駆動力が作用する吸気カム駒30は、低速カム38a，38bが各スリッパ部43a，43bに摺接する低速位置に向けて回転軸線L1方向に移動する。そして、排気側動弁装置ＶEXにおいても、前述の吸気側動弁装置ＶINと同様の移行がなされる。
【００４１】
次に、前述のように構成されている実施例の効果について説明する。なお、排気側動弁装置ＶEXに関するものは括弧内に記すこととし、符号は吸気側動弁装置ＶINに関するもののみを記した。
【００４２】
吸気（排気）カム駒30の低速カム38a，38bが、第１，第２吸気（排気）バルブリフタ32a，32bに摺接するとき、低速カム38a，38bに隣接してそれら第１，第２吸気（排気）バルブリフタ32a，32bに対して非接触状態にある高速カム39a，39bは、両吸気（排気）バルブリフタ32a，32bと干渉することなく、切欠部42a2，42b2を通過して回転する。その結果、次の効果が奏される。すなわち、カムプロフィールの異なる低速カム38a，38bおよび高速カム39a，39bが隣接して設けられた第１吸気（排気）カム部37aおよび第２（排気）吸気カム部37bを有する吸気（排気）カム駒30の低速カム38a，38bが、第１，第２吸気（排気）バルブリフタ32a，32bとそれぞれ摺接して第１，第２吸気（排気）弁12a，12ｂを作動させるとき、該摺接する低速カム38a，38bに隣接する高速カム39a，39bは両吸気（排気）バルブリフタ32a，32bの切欠部42a2，42b2を通過するので、第１，第２吸気（排気）カム部37a，37b、各吸気（排気）バルブリフタ32a，32bの吸気（排気）カム軸６の回転軸線L1方向での幅の範囲内に位置させることが可能となって、吸気（排気）カム駒30の回転軸線L1方向での幅を小さくすることができて、動弁装置Ｖがコンパクトでかつ軽量になり、ひいては内燃機関Ｅがコンパクトでかつ軽量になる。さらに、吸気（排気）カム駒30の回転軸線L1方向での寸法が小さいことで、同一シリンダ１に対して、第１，第２吸気弁12a，12b、第１排気弁13aおよび第２排気弁が設けられる場合にも、限られたシリンダ１のボア1a径の範囲内で、それら複数の吸気弁および排気弁に対する吸気カム駒30および排気カム駒31の適用が容易である。
【００４３】
吸気（排気）側駆動機構ＭINの１対のアーム54a，54bの操作部56a2，56b2および当接部57a2，57b2は、吸気（排気）カム駒30の第１，第２側面40a，40bにおいて、低速カム38a，38bおよび高速カム39a，39bのベース円部よりも径方向外方に突出するにも拘わらず、切欠部42a1，42b2内に位置するので、第１，第２吸気（排気）バルブリフタ32a，32bと接触することはない。その結果、次の効果が奏される。すなわち、吸気（排気）カム駒30の第１，第２側面40a，40bに当接する１対のアーム54a，54bは、第１，第２吸気（排気）バルブリフタ32a，32bと接触することなく、しかも吸気（排気）カム駒30の第１，第２側面40a，40bにおいて、低速カム38aおよび高速カム39bのベース円部よりも径方向内側のみで当接させる必要がないうえ、低速カム38aおよび高速カム39bのベース円部よりも径方向外方に突出する位置で、第１，第２側面40a，40bに当接したとしても、１対のアーム54a，54bの操作部56a2，56b2および当接部57a2，57b2を第１，第２吸気（排気）バルブリフタ32a，32bの回転軸線L1方向での幅の範囲内に位置させることが可能となって、吸気（排気）カム駒30と操作部56a2，56b2および当接部57a2，57b2を有する吸気（排気）側駆動機構ＭINとを合わせた回転軸線L1方向での幅を小さくすることができて、動弁装置Ｖがコンパクトでかつ軽量になり、ひいては内燃機関Ｅがコンパクトでかつ軽量になる。さらに、吸気カム駒30の第１，第２側面40a，40bを第１，第２吸気（排気）バルブリフタ32a，32bの回転軸線L1方向での幅の範囲内に位置させることが可能となって、アーム54a，54bを有する吸気（排気）側駆動機構ＭINが、吸気（排気）カム駒30の回転軸線L1方向での幅の短縮化による動弁装置Ｖのコンパクト化を妨げることがない。また、該第１，第２側面40a，40bでの両アーム54a，54bの当接部分を設定するに当たり、それらアーム54a，54bと第１，第２吸気（排気）バルブリフタ32a，32bとの位置関係からの制約が少なくなり、アーム54a，54bの配置の自由度、ひいては吸気（排気）側駆動機構ＭINの配置の自由度が大きくなる。
【００４４】
第１，第２吸気（排気）バルブリフタ32a，32bに設けられた貫通孔からなる切欠部42a1，42a2，42b1，42b2を通じて、動弁室23内で第１，第２吸気（排気）バルブリフタ32a，32bの外側の潤滑油が第１，第２吸気（排気）バルブリフタ32a，32bの内側に侵入して、その内側に配置される弁ばね20a，20b、リテーナ18a，18bおよび第１，第２吸気弁12a，12bの摺動部に潤滑油が容易に供給される。また、貫通孔からなる切欠部42a1，42a2，42b1，42b2が形成されることで、両吸気（排気）バルブリフタ32a，32bの一部が切除されるため、それらバルブリフタ32a，32bが軽量となる。その結果、次の効果が奏される。すなわち、切欠部42a1，42a2，42b1，42b2を通じて第１，第２吸気（排気）バルブリフタ32a，32bの内側の摺動部に潤滑油を容易に供給できるので、該摺動部の耐久性が向上する。さらに、切欠部42a1，42a2，42b1，42b2の形成により第１，第２吸気（排気）バルブリフタ32a，32bの一部が切除されるため、それらバルブリフタ32a，32bが軽量化され、ひいては内燃機関Ｅの軽量化ができる。
【００４５】
同一のシリンダ１に設けられた第１吸気（排気）弁12aおよび第２吸気（排気）弁12bは、同一の吸気（排気）カム駒30に設けられた第１吸気（排気）カム部37aおよび第２吸気（排気）カム部37bを構成する低速カム38a，38bおよび高速カム39a，39bが、同一の吸気（排気）側駆動機構ＭINにより選択的に、しかも同時に切り換えられる。その結果、次の効果が奏される。すなわち、同一のシリンダ１に設けられた第１，第２吸気（排気）弁12a，12ｂは、同一の吸気（排気）側駆動機構ＭINにより、同一の吸気（排気）カム駒30に設けられた第１，第２吸気（排気）カム部37a，37bの低速カム38a，38bおよび高速カム39a，39bのうち、第１，第２吸気（排気）バルブリフタ32a，32bに摺接するように切り換えられたカムで作動されるので、２つの吸気（排気）弁12a，12bに対して吸気（排気）カム駒30および吸気（排気）側駆動機構ＭINを共用できて、動弁装置Ｖをコンパクトにすることができる。
【００４６】
第１，第２吸気（排気）バルブリフタ32a，32bのスリッパ部43a，43bの摺接面43a1，43b1は、第１，第２吸気（排気）カム部37a，37bに向かって凸となる円筒面からなる曲面をなすことから、それら摺接面が平面である場合に比べて各吸気（排気）バルブリフタ32a，32bの径を小さくすることができ、シリンダヘッド３を小型化できる。また、スリッパ部43a，43bの側方に貫通孔からなる切欠部42a1，42a2，42b1，42b2が設けられるにも拘わらず、スリッパ部43a，43bの必要な剛性を、スリッパ部43a，43bを厚肉にするなどの重量増を招くことなく、軽量化を達成しつつ確保できるという効果が奏される。
【００４７】
第１，第２吸気（排気）バルブリフタ32a，32bの切欠部42a1，42a2，42b1，42b2内には、切欠部42a2，42b2を通過する高速カム39a，39bのノーズ部の最大突出部に近接した位置にリテーナ18a，18bが位置するようにされて、弁ステム16a，16bの端部とスリッパ部43a，43bの摺接面43a1，43b1との間の間隔を極力小さくしているので、動弁装置Ｖをコンパクトにすることができるという効果が奏される。
【００４８】
以下、前述した実施例の一部の構成を変更した実施例について、変更した構成に関して説明する。
【００４９】
前記実施例では、低速カムおよび高速カムが、吸気および排気バルブリフタのスリッパ部の外表面に摺接するものであったが、吸気側動弁装置ＶINについては図７に図示されるように、第１，第２吸気バルブリフタ32a，32bの頂壁に第１，第２ローラ60a，60bを設けて、低速カム38a，38bおよび高速カム39a，39bが両該ローラ60a，60bにそれぞれ摺接するようにしたバルブリフタであってもよい。すなわち、第１，第２吸気バルブリフタ32a，32bにそれぞれ固定される第１，第２支軸61a，61bに支持される第１，第２ローラ60a，60bは、頂壁の外表面からその一部が突出して、低速カム38a，38bおよび高速カム39a，39bと摺接する第１，第２外輪62a，62bと、両支軸61a，61bにそれぞれ嵌合された第１，第２内輪63a，63bと、各外輪62a，62bと各内輪63a，63bとの間に設けられた多数のコロ64a，64bとからなる。さらに、排気側動弁装置ＶEXにおいても同様のローラを有する排気バルブリフタが使用される。このように構成することによって、バルブリフタとカムとの間の摩擦が低減されて、出力の損失を低減できる。
【００５０】
さらに、図８に図示されるように、吸気側駆動機構ＭINにおいて、吸気カム駒30に、高速カム39aおよび低速カム38bの間で回転軸線L1方向に延びて第１，第２吸気カム部37a，37bを連結する１条または周方向に間隔をおいて複数条の補強リブ70が設けられてもよく、また、吸気側駆動機構ＭINの動弁室23内での位置は、図１に図示される位置よりもシリンダ１寄りとされて、１対のアーム54a，54bの操作部56a2，56b2および当接部57a2，57b2が、前記実施例のものよりも、第１，第２吸気バルブリフタ32a，32bに近い位置を占め、低速カム38a，38bおよび高速カム39a，39bのノーズ部の最大突出部よりも、吸気カム軸６の径方向外方に突出していてもよい。
【００５１】
そして、この吸気側駆動機構ＭINにおいても、図８に図示されるように、低速回転域で両低速カム38a，38bが第１，第２吸気バルブリフタ32a，32bの第１，第２ローラ60a，60bにそれぞれ摺接するときは、第１吸気バルブリフタ32a寄りの操作部56a2および当接部57a2は、低速カム38aおよび高速カム39aのノーズ部の最大突出部よりも径方向に突出しているにも拘わらず、切欠部42a1に位置するため、第１吸気バルブリフタ32aと接触することがない。同様に、高速回転域で両高速カム39a，39bが第１，第２吸気バルブリフタ32a，32bの第１，第２ローラ60a，60bにそれぞれ摺接するときは、第２吸気バルブリフタ32b寄りの操作部56b2および当接部57b2は、低速カム38bおよび高速カム39bのノーズ部の最大突出部よりも径方向に突出しているにも拘わらず、切欠部42b2に位置するため、第２吸気バルブリフタ32bと接触することがない。
さらに、排気側動弁装置ＶEXにおいても、この吸気側駆動機構ＭINと同様の構成の排気側駆動機構ＭEXが使用される。
【００５２】
それゆえ、この実施例によれば、前記実施例と同様の効果が奏されるほか、補強リブ70が設けられるので、吸気（排気）カム駒30の剛性が向上すると共に、吸気（排気）側駆動機構ＭINがシリンダ１寄りに配置されるので、動弁室23の高さを低くすることができて、内燃機関Ｅを高さ方向にコンパクトにすることができるという効果が奏される。
【００５３】
前記実施例では、吸気カム駒30および排気カム駒31の第１カム部および第２カム部はいずれも低速カムおよび高速カムから構成されるものであったが、両カム部のいずれか一方のカム部が、一方の吸気弁または一方の排気弁を実質的に閉弁状態に保つ休止カムと高速カムとから構成されて、低速回転域では該一方の吸気弁または該一方の排気弁が閉弁され、他方の吸気弁および他方の排気弁が低速カムで作動され、高速回転域では、両吸気弁および両排気弁が高速カムで作動されるようしてもよい。同様にして、多気筒内燃機関において、一部のシリンダの両カム部が、吸気弁および排気弁を実質的に閉弁状態に保つ休止カムと高速カムとから構成されて、低速回転域では、該一部のシリンダの両吸気弁および両排気弁が閉弁されて、該シリンダが休止され、高速回転域では、すべてのシリンダの両吸気弁および両排気弁が高速カムで作動されるようしてもよい。
【００５４】
また、前記実施例では、シリンダ１毎の１対の吸気弁および１対の排気弁は、別々のバルブリフタを介して別々のカム部により作動されたが、両吸気弁または両排気弁が、単一のバルブリフタを介して単一のカム部により作動されるようにしてもよい。
【００５５】
前記実施例では、吸気側および排気側駆動機構の駆動ピストンは、二つの位置を占めるものであったが、吸気および排気カム駒のカム部を、カムプロフィールの異なる３つのカムから構成して、駆動ピストンが３つの位置を占めることができるように、例えば第１油圧室55aが高油圧、第２油圧室55bが低油圧となる第１状態、第１油圧室55aが高油圧、第２油圧室55bが高油圧となる第２状態、および第１油圧室55aが低油圧、第２油圧室55bが高油圧となる第３状態となるように、作動油を制御することもできる。この場合にも、バルブリフタに対して非接触状態にあるカムが、バルブリフタの切欠部を通過するようにできるので、カム部に３つのカムを設けるにも拘わらず、動弁装置をコンパクトにすることができる。
【００５６】
前記実施例では、内燃機関Ｅは、吸気カム軸６および排気カム軸７を有するものであったが、単一のカム軸を有するＳＯＨＣ型の内燃機関であってもよい。また、シリンダ当たり、１個または３個以上の吸気弁、または１個または３個以上の排気弁が設けられるものであってもよい。さらに、内燃機関は単気筒の内燃機関であってもよい。
【００５７】
前記実施例では、１対のアーム54a，54bが設けられたが、吸気カム駒30および排気カム駒31において、第１カム部および第２カム部の間の円筒部に摺接する１つのアームにより、両カム駒30，31を軸方向に移動させることもできる。
【図面の簡単な説明】
【図１】本願発明の実施例を示し、直動式動弁装置が適用される内燃機関の部分縦断面図である。
【図２】吸気側動弁装置の一部分解図である。
【図３】低速位置にある吸気カム駒と吸気バルブリフタとの、吸気カム軸の回転軸線および弁ステムの軸線を含む平面での部分断面図である。
【図４】高速位置にある吸気カム駒と吸気バルブリフタとの、図３と同様の部分断面図である。
【図５】図１のＶ矢視図であり、低速位置にある吸気カム駒および吸気側駆動機構状態を示す図である。
【図６】図５と同様の矢視図であり、高速位置にある吸気カム駒および吸気側駆動機構状態を示す図である。
【図７】ローラを有するバルブリフタを備えた直動式動弁装置の本願発明の別の実施例である。
【図８】駆動機構の配置およびカム駒が異なる本願発明の別の実施例である。
【符号の説明】
１…シリンダ、２…シリンダブロック、３…シリンダヘッド、４…ヘッドカバー、５…ピストン、６…吸気カム軸、７…排気カム軸、８…カムホルダ、９…燃焼室、10…吸気ポート、11…排気ポート、12a，12b…吸気弁、13a…排気弁、14a，15a…弁ガイド、16a，16b，17a…弁ステム、18a，18b，19a…リテーナ、20a，20b，21a…弁ばね、22…点火栓、23…動弁室、24a，25a…案内溝、
30…吸気カム駒、31…排気カム駒、32a，32b…吸気バルブリフタ、33a…排気バルブリフタ、34…軸孔、35…凹溝、36…突条、37a，37b…吸気カム部、38a，38b…低速カム、39a，39b…高速カム、40a，40b…側面、41a，41b…円筒部、42a1，42a2，42b1，42b2…切欠部、43a，43b…スリッパ部、44a，44b，45a…ピン、
50…駆動ピストン、51a，51b…シリンダ部、52a，52b…両ピストン部、53…連結部、54a，54b…アーム、55a，55b…油圧室、56a1，56a2，56b1，56b2…操作部、57a1，57a2，57b1，57b2…当接部、58a，58b…開口部、
60a，60b…ローラ、61a，61b…支軸、62a，62b…外輪、63a，63b…内輪、64a，64b…コロ、
70…補強リブ、
Ｅ…内燃機関、L1，L2…回転軸線、Ｖ…動弁装置、ＶIN…吸気側動弁装置、ＶEX…排気側動弁装置、ＭIN…吸気側駆動機構、ＭEX…排気側駆動機構。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct acting valve operating apparatus for an internal combustion engine provided with switching means for selectively switching the valve operating characteristics of an intake valve or an exhaust valve that is an engine valve for controlling intake or exhaust provided in the internal combustion engine.
[0002]
[Prior art]
  2. Description of the Related Art Conventionally, there has been disclosed a Japanese Patent Application No. 2000-189489 filed by the present applicant as a valve operating device provided with switching means for selectively switching the valve operating characteristics of an intake valve or an exhaust valve of an internal combustion engine. The valve gear of this prior application includes an intake cam piece having an intake variable cam portion provided on an intake camshaft, and a plurality of cams having different cam profiles, each having a low-speed cam and a high-speed cam, and an exhaust cam. A low-speed cam and a high-speed cam that are provided on the shaft and have different cam profiles are provided adjacent to each other.ThisAn exhaust cam piece having a variable exhaust cam portion, an intake rocker arm and an exhaust rocker arm that contact the low-speed cam or the high-speed cam of the intake variable cam portion and the exhaust variable cam portion, and an intake cam piece and an exhaust that are movable with respect to the cam shaft And a drive mechanism for moving the cam piece in the rotation axis direction of the cam shaft. And, by the intake cam piece and the exhaust cam piece moving in the direction of the rotation axis, the intake rocker arm and the exhaust rocker arm that are selectively swung to the low speed cam or the high speed cam of the intake cam piece and the exhaust cam piece, The intake and exhaust valves are actuated according to the cam profile of the low speed cam or the high speed cam, respectively.
[0003]
[Problems to be solved by the invention]
By the way, the prior application has disclosed that the valve operating device may be a direct acting type, thereby improving the operation responsiveness of the intake valve and the exhaust valve during high speed rotation, The advantage that the height of the valve chamber can be reduced and the internal combustion engine becomes compact is obtained. However, in a direct-acting valve operating apparatus, when operating an intake valve and an exhaust valve by an intake cam piece and an exhaust cam piece provided adjacent to each other with a plurality of cams having different cam profiles, the intake valve (or the exhaust valve) is used. The valve lifter of the valve) and the intake variable cam portion (or the exhaust variable cam portion) of the cam that is not in contact with the valve lifter, in particular, the high-speed cam that protrudes with a larger protruding amount than the low-speed cam, The problem is how to avoid interference with the drive mechanism that moves each cam piece in the direction of the rotational axis of the cam shaft without increasing the size of the valve gear.
[0004]
  The present invention has been made in view of such circumstances, and claims 1 to5The described invention makes it possible to reduce the size in the direction of the rotation axis when a plurality of cams having different cam profiles are combined with the cam piece and the switching means provided in the direction of the rotation axis of the cam shaft. A common object is to provide a compact and lightweight direct acting valve gear.further, Claims1-5SUMMARY OF THE INVENTION An object of the present invention is to provide a direct-acting valve operating device that reduces the weight of a valve lifter and facilitates lubrication of an engine valve.TossThe
[0005]
[Means for Solving the Problems and Effects of the Invention]
  The invention according to claim 1 of the present application is a cam piece that rotates together with a camshaft, and a cam piece having a cam portion in which a plurality of cams having different cam profiles are provided adjacent to each other in the rotation axis direction of the camshaft. A valve lifter disposed between the cam portion and an engine valve that controls intake or exhaust of the internal combustion engine; and a switching means for selectively switching a cam of the cam portion that is in sliding contact with the valve lifter. In the direct acting valve operating apparatus for an internal combustion engine that is operated according to the cam profile of the cam that is in sliding contact with the valve lifter, the valve lifter is configured to allow the cam portion to escape from a cam that is not in contact with the valve lifter. Notch is providedThe notch is formed by a hole that penetrates the valve lifter to communicate the inside and the outside.It is a direct acting valve gear for an internal combustion engine.
[0006]
  According to the first aspect of the present invention, the cam in the non-contact state adjacent to the cam slidingly contacting the valve lifter of the cam piece rotates through the notch of the valve lifter without interfering with the valve lifter. As a result, the following effects are exhibited. That is, when one cam of a cam piece provided with a plurality of cams having different cam profiles is in sliding contact with the valve lifter to operate the engine valve, the cam adjacent to the sliding contact cam passes through the notch portion of the valve lifter. Therefore, at least a part of the cam adjacent to the sliding cam can be positioned within the range of the width of the cam shaft of the valve lifter in the rotational axis direction, and the width of the cam piece in the rotational axis direction can be increased. The valve operating device can be made compact and light, and the internal combustion engine can be made compact and light. Furthermore, even when a plurality of engine valves for controlling intake or exhaust are provided for the same cylinder due to the small size of the cam piece in the rotational axis direction, within the limited bore diameter range of the cylinder, The cam piece can be easily applied to the plurality of engine valves, and more than two cams can be easily provided on the cam piece.
  Furthermore, the lubricating oil outside the valve lifter enters the inside of the valve lifter through the notch formed in the valve lifter, and the lubricating oil is applied to the sliding portions of the valve spring, retainer and engine valve arranged inside the valve lifter. Is easily supplied. Moreover, since a part of the valve lifter is cut off by forming the hole, the valve lifter becomes light. As a result, the lubricating oil can be easily supplied to the sliding portion inside the valve lifter through the notch, so that the durability of the sliding portion is improved. Furthermore, since a part of the valve lifter is cut off by forming the notch, the valve lifter can be reduced in weight, and thus the internal combustion engine can be reduced in weight.
[0007]
  The invention according to claim 2Claim 1In the direct acting valve operating apparatus for an internal combustion engine, the cam piece is movable in the rotational axis direction with respect to the cam shaft, and the switching means abuts on a side surface of the cam portion in the rotational axis direction. An operation member; and a drive member that moves the cam piece in the direction of the rotation axis via the operation member to switch the cam that is slidably contacted with the valve lifter. It is a direct acting valve gear for an internal combustion engine provided with a notch.
[0008]
  According to the second aspect of the present invention, even if the operating member abuts on the side surface of the cam portion in the rotational axis direction at a position protruding radially outward from the base circle portion of the cam, Since it is located in the part, it does not come into contact with the valve lifter. as a result,In addition to the effects of the claimed invention,The following effects are produced. In other words, the operating member that contacts the side surface of the cam portion does not need to contact the valve lifter, and does not need to contact the side surface of the cam portion only on the radially inner side of the base circle portion of the cam. Even if it comes into contact with the side surface at a position that protrudes radially outward from the circular portion, the operation member can be positioned within the range of the width of the cam shaft of the valve lifter in the direction of the rotation axis. The width in the direction of the rotation axis combined with the switching means having the piece and the operating member can be reduced, so that the valve operating device is compact and lightweight, and the internal combustion engine is compact and lightweight. Further, since the side surface of the cam portion can be positioned within the range of the width of the valve lifter in the rotational axis direction, the switching means having an operation member that abuts on the side surface of the cam portion has a width in the rotational axis direction of the cam piece. Therefore, it is possible to prevent the valve operating device from being made compact by shortening the length. Further, in setting the contact portion of the operation member on the side surface of the cam portion, there are less restrictions from the positional relationship between the operation member and the valve lifter, and the degree of freedom of arrangement of the operation member, and thus the degree of freedom of arrangement of the switching means. Becomes larger.
[0009]
  The invention according to claim 3, ContractIn the direct acting valve gear for an internal combustion engine according to claim 2,For escape to the operation memberThe notch is formed by a hole that penetrates the valve lifter and communicates the inside and the outside.
[0010]
  According to this invention of Claim 3, it consists of a hole provided in the valve lifter.Escape to camNotchAnd a notch for escaping to the operation memberThrough this, the lubricating oil outside the valve lifter enters the inside of the valve lifter, and the lubricating oil is easily supplied to the sliding portions of the valve spring, the retainer and the engine valve arranged inside the valve lifter. Moreover, since a part of the valve lifter is cut off by forming the hole, the valve lifter becomes light. as a result,QuotedClaimEntryIn addition to the effects of the present invention, the following effects are achieved. That is, since the lubricating oil can be easily supplied to the sliding portion inside the valve lifter through the notch, the durability of the sliding portion is improved. Furthermore, since a part of the valve lifter is cut off by forming the notch, the valve lifter can be reduced in weight, and thus the internal combustion engine can be reduced in weight.
[0011]
  The invention according to claim 4 is the invention according to claim 1.OrClaim3In the direct acting valve operating device of the internal combustion engine,The notch is a pair of notches formed by cutting a part of the top wall and a part of the side wall from the top wall of the valve lifter to the side wall of the valve lifter on both sides in the rotational axis direction. IsIs.
[0012]
  According to a fifth aspect of the present invention, in the direct acting valve operating apparatus for an internal combustion engine according to the fourth aspect, the top wall of the valve lifter extends between the pair of notches in the diametrical direction of the top wall. The slippering surface of the slipper part, which forms a slipper part in a shape and the cam is slidably contacted, is an arc that is convex toward the cam part when viewed from the direction of the rotation axis.
  According to the invention described in claim 5, in addition to the effects described in the cited claims, the following effects can be obtained. That is, since the sliding surface of the slipper portion is an arc that is convex toward the cam portion, the diameter of the valve lifter can be reduced compared to the case where the sliding surface is a flat surface. Can be miniaturized. In addition, despite the fact that a pair of notches formed of through-holes are provided on the sides of the slipper part, the required rigidity of the slipper part can be reduced without incurring an increase in weight such as thickening the slipper part. Can be secured while achieving
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS.
The internal combustion engine E to which the direct acting valve gear of the present invention is applied is a DOHC type in-line four-cylinder four-cycle internal combustion engine mounted on a vehicle, and as shown in FIG. A cylinder head 3 is assembled on the upper surface of a cylinder block 2 in which four cylinders 1 (one of which is shown in FIG. 1) are integrated, and a head cover 4 is assembled on the upper surface of the cylinder head 3. The piston 5 fitted in the bore 1a of each cylinder 1 so as to be reciprocally movable is connected to a crankshaft (not shown) via a connecting rod (not shown), and ½ in synchronism with the crankshaft. An intake cam shaft 6 and an exhaust cam shaft 7 that are rotationally driven at a reduction ratio of 5 are arranged in parallel to each other in the cylinder arrangement direction, and are fixed to the cylinder head 3 by bolts, one of which is shown in FIG. It is supported rotatably. These cam holders 8 are disposed between both ends in the cylinder arrangement direction and between adjacent cylinders 1, and each cam holder 8 is a plane including the rotation axis L 1 of the intake cam shaft 6 and the rotation axis L 2 of the exhaust cam shaft 7. It consists of a pair of upper cam holder 8U and lower cam holder 8L divided vertically.
[0014]
In each cylinder head 3, a combustion chamber 9 is formed between each cylinder 1 and the piston 5, and an intake port 10 having a pair of intake ports that open to the combustion chamber 9 and a pair of exhaust ports are provided. An exhaust port 11 is provided, and the pair of intake ports are further opened and closed, and a first intake valve 12a and a second intake valve 12b, which are a pair of engine valves that control intake of the internal combustion engine E (see FIG. 2). The first exhaust valve 13a and the second exhaust valve (not shown), which are a pair of engine valves for controlling the exhaust of the internal combustion engine E by opening and closing the pair of exhaust ports, respectively, are valve guides 14a and 15a. Is slidably provided. The first and second intake valves 12a and 12b, the first exhaust valve 13a and the second exhaust valve are respectively provided with retainers 18a, 18b and 19a provided at the upper ends of the valve stems 16a and 17a and the cylinder head 3. Are urged in the valve closing direction by the valve springs 20a, 20b, 21a mounted in a compressed state. Further, a spark plug 22 facing the substantially center in the combustion chamber 9 is screwed to the cylinder head 3.
[0015]
A valve operating chamber 23 formed between the cylinder head 3 and the head cover 4 accommodates a direct acting valve operating device V for opening and closing the intake valves 12a and 12b and the exhaust valve 13a. This valve operating device V is a hydraulic type as an intake side switching means for moving the intake cam shaft 6, the intake cam piece 30, the intake valve lifters 32a, 32b, and the intake cam piece 30 in the direction of the rotation axis L1 of the intake cam shaft 6. Intake side drive mechanism MINIntake side valve operating device VINAnd a hydraulic exhaust side drive mechanism M as exhaust side switching means for moving the exhaust cam shaft 7, the exhaust cam piece 31, the exhaust valve lifter 33a, and the exhaust cam piece 31 in the direction of the rotation axis of the exhaust cam shaft 7.EXExhaust valve operating device VEXIt consists of. And the intake side valve operating device VINAnd exhaust side valve gear VEXHave basically the same configuration, so in the following description, the intake side valve operating device VINThe explanation will be focused on.
[0016]
Referring also to FIG. 2, an intake camshaft 30 having a shaft hole 34 through which the intake camshaft 6 passes is provided in the intake camshaft 6 in the direction of the rotational axis L1 with respect to the intake camshaft 6. They are slidably moved and splined so as to rotate together with the intake camshaft 6 in the rotational direction. Therefore, in this embodiment, on the inner peripheral surface of the intake cam piece 30, three concave grooves 35 are provided at equal intervals in the circumferential direction and parallel to the rotational axis L1 over the entire length in the rotational axis L1 direction. On the outer peripheral surface of the intake camshaft 6, three ridges 36 are respectively engaged with the three concave grooves 35 over a length equal to the moving range of the intake cam piece 30 in the direction of the rotation axis L1. Provided.
[0017]
The intake cam piece 30 is provided with a first intake cam portion 37a and a second intake cam portion 37b in series and apart from each other in the direction of the rotation axis L1, and the first and second intake cam portions 37a, 37b include Low-speed cams 38a and 38b and high-speed cams 39a and 39b having different cam profiles are provided integrally adjacent to each other in the direction of the rotation axis L1. That is, each of the low-speed cams 38a and 38b includes a nose portion having a relatively small protrusion amount in the radial direction of the intake cam shaft 6 (hereinafter simply referred to as “radial direction”) and a predetermined operating angle in the circumferential direction, and a base Each of the high-speed cams 39a and 39b has a larger amount of protrusion in the radial direction than the protrusion amount of the nose portion of the low-speed cams 38a and 38b, and the operating angle of the low-speed cams 38a and 38b. The cam profile includes a nose portion having a larger operating angle and a base circle portion having a radial protrusion amount equal to the base circle portions of the low-speed cams 38a and 38b.
[0018]
Further, the intake cam piece 30 has a radial thickness thinner than the base circles of the low speed cams 38a and 38b and the high speed cams 39a and 39b, and one side surface of the intake cam piece 30 in the direction of the rotation axis L1. Both sides of the first side surface 40a on the low-speed cam 38a side of the first intake cam portion 37a constituting the first side surface 40b and the second side surface 40b on the high-speed cam 39b side of the second intake cam portion 37b constituting the other side surface in the direction of the rotation axis L1. A first cylindrical portion 41a and a second cylindrical portion 41b extending in the direction of the rotation axis L1 from the surface are provided.
[0019]
Further, below the intake cam piece 30, for each cylinder 1, a first intake valve lifter 32a is disposed between the first intake cam portion 37a and the first intake valve 12a, and the second intake cam portion 37b and the second intake cam portion 37b are connected to the second intake cam portion 37b. A second intake valve lifter 32b is disposed between the two intake valves 12b. The first and second intake valve lifters 32a and 32b are slidably fitted in lifter holes provided in the cylinder head 3 in the axial direction of the valve stems 16a and 16b, respectively.
[0020]
  Each intake valve lifter 32a, 32b has a lower end opened and a cylinder having a top wall at the upper end is plane-symmetrical with respect to an orthogonal plane that includes the axis of the cylinder and is orthogonal to the rotation axis L1 of the intake camshaft 6. The side wall from the top wall to the approximate center of the length of the cylinder is cut off on both sides in the direction of the rotation axis L1.Therefore, each intake valve lifter 32a , 32b Axis of rotation from top wall L1 Each intake valve lifter on both sides in the direction 32a , 32b Part of the top wall and part of the side wallA pair of notches 42a1, 42a2, 42b1, and 42b2 formed by the excision form through holes that communicate between the outside and the inside of each intake valve lifter 32a, 32b, and the valve operating chamber 23 passes through the through holes. The lubricating oil supplied to the inside penetrates into the intake valve lifters 32a and 32b and lubricates the sliding portions of the valve springs 20a and 20b, the retainers 18a and 18b, and the valve stems 16a and 16b.
[0021]
  The remaining portions of the top wall form bridge-shaped slipper portions 43a and 43b that are in sliding contact with the low-speed cams 38a and 38b and the high-speed cams 39a and 39b, and have both end surfaces extending in parallel with the orthogonal plane.A pair of notches 42a1 , 42a2 , 42b1 , 42b2 BetweenIt extends in the diameter direction of the top wall. The slipper portions 43a and 43b have a width in the rotation axis L1 direction slightly smaller than the width in the rotation axis L1 direction of the low-speed cams 38a and 38b and the high-speed cams 39a and 39b, and are sliding surfaces that are outer surfaces thereof The outer surfaces of the top walls 43a1 and 43b1 are parallel to the rotation axis L1 of the intake camshaft 6 and have an axis on a plane including the axis of the cylinder, and protrude toward the intake cam portions 37a and 37b. Since the curved surface is a cylindrical surface, the circular arcs are convex toward the intake cam portions 37a and 37b when viewed from the direction of the rotation axis L1.
[0022]
Further, as shown in FIG. 3, the notches 42a2 and 42b2 are formed when the low-speed cams 38a and 38b of the first and second intake cam portions 37a and 37b are in sliding contact with the slipper portions 43a and 43b. The nose portions of the high-speed cams 39a and 39b projecting in the radial direction larger than the nose portions of the 38a and 38b are set so as to pass through without contacting the first and second intake valve lifters 32a and 32b, respectively. It is a notch for escaping from the cams 39a and 39b. The total width of the intake cam portions 37a and 37b in the direction of the rotation axis L1, that is, the total width of the low speed cams 38a and 38b and the high speed cams 39a and 39b in the direction of the rotation axis L1 is the rotation of each intake valve lifter 32a and 32b. It is made smaller than the width in the direction of the axis L1. Further, in the notches 42a1, 42a2, 42b1, 42b2, the retainers 18a, 18b are positioned close to the maximum protrusions of the nose portions of the high speed cams 39a, 39b that pass through the notches 42a2, 42b2. Thus, the distance between the end portions of the valve stems 16a and 16b and the sliding contact surfaces 43a1 and 43b1 of the slipper portions 43a and 43b is made as small as possible, so that the valve operating device V is made compact.
[0023]
Referring to FIGS. 1 and 2, the first and second intake valve lifters 32a and 32b have first sidewalls formed on the peripheral wall surfaces of the lift holes so as to extend parallel to the axis of the valve stems 16a and 16b. A first pin 44a and a second pin 44b that engage with the guide groove 24a and the second guide groove, respectively, are provided. The first guide groove 24a and the second guide groove prevent the intake valve lifters 32a and 32b from rotating by engaging with the first pin 44a and the second pin 44b, while the valve stems 16a and 32b of the intake valve lifters 32a and 32b. Allow reciprocation in the axial direction of 16b. The exhaust valve lifter is also provided with a pin that engages with a guide groove formed in the cylinder head 3, and FIG. 1 shows a first guide groove 25a and a first pin 45a.
[0024]
Therefore, intake side drive mechanism MINThe low-speed cams 38a and 38b and the high-speed cams 39a and 39b of the first and second intake cam portions 37a and 37b are selectively slidably brought into sliding contact with the slipper portions 43a and 43b by the intake cam piece 30 moved in the direction of the rotation axis L1. The first and second intake valves 12a and 12b correspond to the cam profile of the cam that comes into sliding contact with the low-speed cams 38a and 38b or the first and second intake valve lifters 32a and 32b pressed by the high-speed cams 39a and 39b. The intake port is opened and closed at a lift amount and opening / closing timing set in the nose portion of each cam.
[0025]
Next, referring to FIGS. 2, 5, and 6, an intake side drive mechanism M provided for each cylinder 1.INThe intake side drive mechanism M will be described.INAre provided opposite to each other closer to the center axis of the cylinder 1 than the intake camshaft 6 at the bosses protruding in opposite directions of the adjacent upper cam holders 8U located respectively on both sides of the intake cam piece 30. A first cylinder portion 51a and a second cylinder portion 51b having a cylindrical recess, and a cylindrical first piston portion supported by both ends of the cylinder portions 51a and 51b being slidably fitted to each other. In the double-acting type drive piston 50 as a movable member having a 52a and a second piston portion 52b, and a connecting portion 53 extending in the central axis direction of the driving piston 50 and connecting the piston portions 52a and 52b, the connecting portion 53 In addition, a pair of arms 54a and 54b, which are operation members that are integrally formed with the piston portions 52a and 52b and extend from the connecting portion 53 toward the intake camshaft 6, are provided. Here, the central axis of the drive piston 50 is parallel to the rotational axis L1 of the intake camshaft 6, and coincides with the central axes of the first and second cylinder portions 51a and 51b.
[0026]
A first hydraulic chamber 55a is provided between the first piston part 52a and the first cylinder part 51a.,A second hydraulic chamber 55b is formed between the second piston portion 52b and the second cylinder portion 51b, and the drive piston 50 corresponds to the hydraulic pressure of the hydraulic oil supplied to both hydraulic chambers 55a and 55b. Receiving the driving force, it reciprocates along the central axis of the driving piston 50.
[0027]
  Intake cam piece 30 in the direction of the central axis of drive piston 50The first aspect of 40a And the second side 40 With, In the direction of the rotation axis L1intervalThe pair of arms 54a and 54b provided with a slightly larger interval than the first arm 54a located on the side of the first side face 40a and the second arm located on the side of the second side face 40b. It consists of 54b. The first and second arms 54a and 54b are a pair of fork-shaped operating portions 56a1 and 56a2 and a pair of operating portions that are bifurcated to surround the first and second cylindrical portions 41a and 41b, respectively. 56b1 and 56b2 are provided.
[0028]
The distal ends of both operation portions 56a1 and 56a2 of the first arm 54a are in contact with the first side surface 40a of the low speed cam 38a of the first intake cam portion 37a and a pair of first contacts that are in contact with the outer peripheral surface of the first cylindrical portion 41a. The first abutting portions 57a1 and 57a2 are respectively provided, and the first abutting portions 57a1 and 57a2 are located at the same distance from the rotation axis L1 and at the positions facing the intake cam shaft 6 in the diametrical direction. 40a and the outer peripheral surface of the first cylindrical portion 41a. Similarly, the front ends of both operation portions 56b1 and 56b2 of the second arm 54b are in contact with the second side surface 40b of the high-speed cam 39b of the second intake cam portion 37b and are in contact with the outer peripheral surface of the second cylindrical portion 41b. Each of the second contact portions 57b1 and 57b2 has a pair of second contact portions 57b1 and 57b2, and is located at a position where the distance from the rotation axis L1 is equal and opposite to the diameter direction of the intake camshaft 6. It contacts the outer peripheral surfaces of the second side surface 40b and the second cylindrical portion 41b.
[0029]
Further, in the drive piston 50, the rotating low-speed cams 38a, 38b and the high-speed cams 39a, 39b are inserted into the connecting portion 53 between the first arm 54a and the second arm 54b. Curved recesses 57 (see also FIG. 1) that allow passage of the low-speed cams 38a, 38b and the high-speed cams 39a, 39b are provided.
[0030]
Next, the intake side drive mechanism MINThe hydraulic system will be described. In the discharge path of an oil pump provided in the internal combustion engine E and driven by the power of the crankshaft, the cylinder block 2, the cylinder head 3 and the cam holder 8 are provided in the first hydraulic chamber 55a. A hydraulic fluid passage (not shown) having a portion 58a is communicated, and the hydraulic pressure in the first hydraulic chamber 55a is made high or low by a first control valve (not shown) provided in the hydraulic fluid passage. Be controlled. Similarly, the hydraulic pressure in the second hydraulic chamber 55b is increased by a second control valve (not shown) provided in a second hydraulic oil passage (not shown) having an opening 58b in the second hydraulic chamber 55b. Or it is controlled to low hydraulic pressure.
[0031]
The operations of the first and second control valves are controlled by a control device (not shown) to which a signal detected by a rotation speed sensor that is an engine operation state sensor (not shown) is input. That is, in the low-speed rotation range below the predetermined rotation speed of the internal combustion engine E, the first control valve controls the hydraulic pressure of the hydraulic oil so that the hydraulic oil in the first hydraulic chamber 55a becomes a high hydraulic pressure, and the second control valve Controls the hydraulic pressure of the hydraulic oil so that the hydraulic oil in the second hydraulic chamber 55b has a low hydraulic pressure. Therefore, due to the hydraulic pressure difference between the hydraulic pressure in the first hydraulic chamber 55a and the hydraulic pressure in the second hydraulic chamber 55b, the drive piston 50 moves the intake cam piece 30 in the axial direction. The low-speed cams 38a and 38b occupy the low-speed position shown in FIG. 5 where the low-speed cams 38a and 38b are in sliding contact with the slipper portions 43a and 43b of the first and second intake valve lifters 32a and 32b. At this time, as shown in FIG. 3, of the pair of operation portions 56 a 1 and 56 a 2 that contact the first side surface 40 a of the low speed cam 38 a of the first intake cam portion 37 a and surround the first cylindrical portion 41 a, The operation portion 56a2 and the contact portion 57a2 near the first intake valve lifter 32a are positioned in the cutout portion 42a1 even though they protrude in the radial direction from the base circle portion of the low speed cam 38a. There is no contact with. Therefore, the notch 42a1 also serves as a notch for escaping from the operation portion 56a2, the contact portion 57a2, and the first arm 54a.
[0032]
When the rotational speed of the internal combustion engine E exceeds the predetermined rotational speed and enters a high speed rotational range, the first control valve controls the hydraulic pressure of the hydraulic oil so that the first hydraulic chamber 55a has a low hydraulic pressure, and the second The control valve controls the hydraulic pressure of the hydraulic oil so that the second hydraulic chamber 55b has a high hydraulic pressure. Therefore, the drive piston 50 is caused by the hydraulic pressure difference between the hydraulic pressure in the first hydraulic chamber 55a and the hydraulic pressure in the second hydraulic chamber 55b.IN6 moves the intake cam piece 30 in the axial direction. In the intake cam piece 30, both high speed cams 39a and 39b are in sliding contact with the slipper portions 43a and 43b of the first and second intake valve lifters 32a and 32b. Occupies the high speed position shown. At this time, as shown in FIG. 4, the pair of operation portions 56b1 and 56b2 that contact the second side surface 40b of the high-speed cam 39b of the second intake cam portion 37b and surround the second cylindrical portion 41b. Among them, the operation portion 56b2 and the contact portion 57b2 near the second intake valve lifter 32b are positioned in the notch portion 42b2 even though they protrude in the radial direction from the base circle portion of the high-speed cam 39b. There is no contact with the valve lifter 32b. Therefore, the cutout portion 42b2 also serves as a cutout portion for escaping from the operation portion 56b2, the contact portion 57b2, and the second arm 54b.
[0033]
Here, the first and second intake valve lifters 32a and 32b are changed from being pressed by the sliding contact of the low speed cams 38a and 38b to the pressing by the sliding contact of the high speed cams 39a and 39b, and by the sliding contact of the high speed cams 39a and 39b. The transition from pressing to pressing by sliding contact of the low speed cams 38a, 38b is such that the contact portions of the slipper portions 43a, 43b are in sliding contact with the base circle portions of the low speed cams 38a, 38b or the base circle portions of the high speed cams 39a, 39b. The driving force received by the driving piston 50 is set so as to be performed at a certain time.
[0034]
As shown in FIGS. 5 and 6, the cam holder 8 located between the adjacent cylinders 1 passes through the center point in the direction of the rotation axis L1 of the cam holder 8 and is orthogonal to the rotation axis L1. The first hydraulic chamber 55a belonging to the cylinder 1 on the right side of the figure and the first hydraulic chamber 55a belonging to the cylinder 1 on the left side of the upper cam holder 8U with respect to the plane to be arranged are symmetrical. The hydraulic oil passages are shared by both hydraulic chambers 55a and 55a. The same applies to other cam holders 8 positioned between adjacent cylinders 1 and components of the valve gear V belonging to the cylinders 1.
[0035]
Exhaust valve operating device VEXExhaust side drive mechanism MEXThe hydraulic system of the intake side drive mechanism M is also described above.INIn the same manner as described above, controlled hydraulic oil is supplied.
[0036]
Next, with reference to FIGS. 3 to 6, the operation of the embodiment configured as described above will be described.
In the state where the operation of the internal combustion engine E is started and the oil pump is operating, when the rotation speed of the internal combustion engine E is in a low speed rotation range equal to or lower than the predetermined rotation speed, the intake side valve operating device VINThen, according to a command from the control device, the first control valve operates so that the hydraulic oil in the first hydraulic chamber 55a becomes a high hydraulic pressure, and at the same time, the second control valve receives the hydraulic oil in the second hydraulic chamber 55b. Operates to low hydraulic pressure. Therefore, the intake side drive mechanism MINThe drive piston 50 occupies a low speed position shown in FIG. 5 which is also in a state before the operation of the internal combustion engine E is started. Therefore, the low-speed cams 38a and 38b of the first and second intake cam portions 37a and 37b of the intake cam piece 30 are in sliding contact with the slipper portions 43a and 43b of the first and second intake valve lifters 32a and 32b, respectively. And the exhaust side drive mechanism MEXThe drive piston of the intake side drive mechanism MINIn the same manner as above, the low speed position is also occupied before the internal combustion engine E starts operating. Therefore, the first and second intake valves 12a and 12b, the first exhaust valve 13a, and the second exhaust valve in each cylinder 1 have a small lift amount, an opening / closing timing and a short valve opening suitable for the valve operating characteristics in the low speed rotation region. It is opened and closed with a period. At this time, as shown in FIG. 3, the nose portions of the high-speed cams 39a and 39b projecting in the radial direction larger than the nose portions of the low-speed cams 38a and 38b are the first and second intake valve lifters 32a and 32b. Without contact with each other and rotate through the notches 42a2 and 42b2. Since the operation portion 56a2 and the contact portion 57a2 near the first intake valve lifter 32a are positioned in the notch portion 42a1 even though they protrude in the radial direction from the base circle portion of the low-speed cam 38a, the first intake valve There is no contact with the valve lifter 32a. This also means that the exhaust side valve operating device VEXThe same applies to.
[0037]
Then, when the rotational speed of the internal combustion engine E exceeds the predetermined rotational speed and shifts to the high speed rotational range, the first control valve causes the hydraulic oil in the first hydraulic chamber 55a to become low hydraulic pressure in accordance with a command from the control device. At the same time, the second control valve operates so that the hydraulic oil in the second hydraulic chamber 55b becomes a high hydraulic pressure. Therefore, the intake side drive mechanism MINThe driving piston 50 receives a driving force that moves from the low speed position to the high speed position shown in FIG.
[0038]
At this time, if the slipper portions 43a and 43b of the first and second intake valve lifters 32a and 32b are in sliding contact with the base circle portions of the low-speed cams 38a and 38b, the drive piston 50 moves immediately and simultaneously the second arm 54b. The intake cam piece 30 to which the driving force is applied moves through the pair of contact portions 57b1 and 57b2 in the direction of the rotation axis L1, and the intake cam piece 30 has a high-speed cam 39a, 39b occupies a position in sliding contact with the first and second intake valve lifters 32a and 32b.
[0039]
Further, when the driving piston 50 receives a driving force that moves from the low speed position to the high speed position, if the slipper portions 43a and 43b are in sliding contact with the nose portions of the low speed cams 38a and 38b, the subsequent intake camshaft 6 As a result of the rotation, the drive piston 50 moves toward the high speed position immediately after the slipper portions 43a, 43b are brought into sliding contact with the base circles of the low speed cams 38a, 38b, and at the same time, the contact portions 57b1 of the second arms 54a, 54b. , 57b2, the intake cam piece 30 on which the driving force is applied moves in the direction of the rotation axis L1 toward the high speed position where the high speed cams 39a, 39b are in sliding contact with the slipper portions 43a, 43b. Therefore, in the high-speed rotation region, the high-speed cams 39a and 39b of the first and second intake cam portions 37a and 37b of the intake cam piece 30 slide on the slipper portions 43a and 43b of the first and second intake valve lifters 32a and 32b, respectively. Touch. And the exhaust side drive mechanism MEXThe drive piston of the intake side drive mechanism MINAs well as occupying a high-speed position. Therefore, the first and second intake valves 12a and 12b, the first exhaust valve 13a, and the second exhaust valve in each cylinder 1 have a large lift amount, an open / close timing, and a long valve opening suitable for the valve operating characteristics in the high-speed rotation range. It is opened and closed with a period. Further, at this time, as shown in FIG. 4, the operating portion 56b2 and the contact portion 57b2 near the second intake valve lifter 32b are projected in the radial direction from the base circle portion of the high speed cam 39b. Since it is located in the notch 42b2, it does not come into contact with the second intake valve lifter 32b. This also means that the exhaust side valve operating device VEXThe same applies to.
[0040]
Further, when shifting from the high-speed rotation region to the low-speed rotation region, the hydraulic oil in the first hydraulic chamber 55a becomes high hydraulic pressure and the hydraulic oil in the second hydraulic chamber 55b is low at the same time by the first and second control valves. It becomes hydraulic. Therefore, the intake side drive mechanism M is caused by the hydraulic pressure difference between the hydraulic pressure in the first hydraulic chamber 55a and the hydraulic pressure in the second hydraulic chamber 55b.INThe driving piston 50 receives a driving force that moves from the high speed position to the low speed position. At this time, if the slipper portions 43a and 43b of the first and second intake valve lifters 32a and 32b are in sliding contact with the base circle portions of the high-speed cams 39a and 39b, the slipper portions 43a and 43b are immediately connected to the high-speed cams 39a, If it is in sliding contact with the nose portion of 39b, immediately after each of the slipper portions 43a, 43b is in sliding contact with the base circle portion of the high speed cams 39a, 39b, the drive piston 50 moves toward the low speed position and simultaneously the first arm The intake cam piece 30 to which the driving force is applied via the contact portions 57a1 and 57a2 of 54a moves in the direction of the rotation axis L1 toward the low speed position where the low speed cams 38a and 38b are in sliding contact with the slipper portions 43a and 43b. And the exhaust side valve operating device VEXIn the above-mentioned intake side valve operating device VINThe same transition is made.
[0041]
Next, effects of the embodiment configured as described above will be described. Exhaust valve operating device VEXRelated to the intake side valve operating device VINOnly the thing about was described.
[0042]
When the low-speed cams 38a and 38b of the intake (exhaust) cam piece 30 are in sliding contact with the first and second intake (exhaust) valve lifters 32a and 32b, the first and second intakes (adjacent to the low-speed cams 38a and 38b) The high-speed cams 39a, 39b that are in non-contact with the exhaust (lift) valve lifters 32a, 32b rotate through the notches 42a2, 42b2 without interfering with the intake (exhaust) valve lifters 32a, 32b. As a result, the following effects are exhibited. That is, the intake (exhaust) cam having the first intake (exhaust) cam portion 37a and the second (exhaust) intake cam portion 37b provided with the low-speed cams 38a and 38b and the high-speed cams 39a and 39b having different cam profiles. When the low-speed cams 38a and 38b of the piece 30 are in sliding contact with the first and second intake (exhaust) valve lifters 32a and 32b, respectively, to operate the first and second intake (exhaust) valves 12a and 12b, the sliding low speed Since the high-speed cams 39a and 39b adjacent to the cams 38a and 38b pass through the cutout portions 42a2 and 42b2 of the both intake (exhaust) valve lifters 32a and 32b, the first and second intake (exhaust) cam portions 37a and 37b, The (exhaust) valve lifters 32a and 32b can be positioned within the range of the width of the intake (exhaust) cam shaft 6 in the direction of the rotational axis L1, and the intake (exhaust) cam piece 30 can be positioned in the direction of the rotational axis L1. The width can be reduced, making the valve gear V compact and lightweight. And thus the internal combustion engine E can be made compact and lightweight. Further, since the size of the intake (exhaust) cam piece 30 in the direction of the rotation axis L1 is small, the first and second intake valves 12a and 12b, the first exhaust valve 13a and the second exhaust valve are provided for the same cylinder 1. Also, the intake cam piece 30 and the exhaust cam piece 31 can be easily applied to the plurality of intake valves and exhaust valves within the limited bore 1a diameter range of the cylinder 1.
[0043]
Intake (exhaust) side drive mechanism MINThe operation portions 56a2 and 56b2 and the contact portions 57a2 and 57b2 of the pair of arms 54a and 54b of the pair of arms 54a and 54b are the low-speed cams 38a and 38b and the high-speed cams on the first and second side surfaces 40a and 40b of the intake (exhaust) cam piece 30, respectively. Although it is located in the notches 42a1 and 42b2 even though it protrudes radially outward from the base circles 39a and 39b, it does not contact the first and second intake (exhaust) valve lifters 32a and 32b. Absent. As a result, the following effects are exhibited. That is, the pair of arms 54a and 54b that contact the first and second side surfaces 40a and 40b of the intake (exhaust) cam piece 30 do not contact the first and second intake (exhaust) valve lifters 32a and 32b. In addition, the first and second side surfaces 40a and 40b of the intake (exhaust) cam piece 30 do not need to be contacted only radially inward of the base circles of the low speed cam 38a and the high speed cam 39b, and the low speed cam 38a and Even if it contacts the first and second side surfaces 40a, 40b at a position protruding radially outward from the base circle of the high-speed cam 39b, the operation portions 56a2, 56b2 of the pair of arms 54a, 54b and the The contact portions 57a2 and 57b2 can be positioned within the width of the first and second intake (exhaust) valve lifters 32a and 32b in the direction of the rotation axis L1, and the intake (exhaust) cam piece 30 and the operation unit Intake (exhaust) side drive mechanism M having 56a2, 56b2 and contact portions 57a2, 57b2INAnd the width in the direction of the rotation axis L1 can be reduced, and the valve operating device V is compact and lightweight, and the internal combustion engine E is compact and lightweight. Further, the first and second side surfaces 40a and 40b of the intake cam piece 30 can be positioned within the range of the width in the direction of the rotation axis L1 of the first and second intake (exhaust) valve lifters 32a and 32b. Intake (exhaust) side drive mechanism M having arms 54a and 54bINHowever, it does not hinder downsizing of the valve gear V by shortening the width of the intake (exhaust) cam piece 30 in the direction of the rotation axis L1. In setting the contact portions of the arms 54a and 54b on the first and second side surfaces 40a and 40b, the positions of the arms 54a and 54b and the first and second intake (exhaust) valve lifters 32a and 32b are set. The restriction from the relationship is reduced, the degree of freedom of arrangement of the arms 54a, 54b, and the intake (exhaust) side drive mechanism MINThe degree of freedom of arrangement becomes large.
[0044]
The first and second intake (exhaust) valve lifters 32a, 32a, 32b are formed in the valve operating chamber 23 through notches 42a1, 42a2, 42b1, and 42b2 formed through holes provided in the first and second intake (exhaust) valve lifters 32a and 32b. Lubricating oil on the outside of 32b enters the insides of the first and second intake (exhaust) valve lifters 32a and 32b, and the valve springs 20a and 20b, retainers 18a and 18b, and the first and second intakes disposed inside thereof. Lubricating oil is easily supplied to the sliding parts of the valves 12a and 12b. Further, by forming the notches 42a1, 42a2, 42b1, and 42b2 formed of through holes, part of both intake (exhaust) valve lifters 32a and 32b is cut off, so that the valve lifters 32a and 32b become lighter. As a result, the following effects are exhibited. That is, since the lubricating oil can be easily supplied to the sliding portions inside the first and second intake (exhaust) valve lifters 32a and 32b through the notches 42a1, 42a2, 42b1, and 42b2, the durability of the sliding portions is improved. To do. Further, since the cutout portions 42a1, 42a2, 42b1, and 42b2 are formed, a part of the first and second intake (exhaust) valve lifters 32a and 32b is cut off, so that the valve lifters 32a and 32b are reduced in weight, and as a result, the internal combustion engine E Can be reduced in weight.
[0045]
The first intake (exhaust) valve 12a and the second intake (exhaust) valve 12b provided in the same cylinder 1 are a first intake (exhaust) cam portion 37a provided in the same intake (exhaust) cam piece 30, and The low-speed cams 38a and 38b and the high-speed cams 39a and 39b constituting the second intake (exhaust) cam portion 37b are the same intake (exhaust) side drive mechanism M.INCan be switched selectively and simultaneously. As a result, the following effects are exhibited. That is, the first and second intake (exhaust) valves 12a and 12b provided in the same cylinder 1 are connected to the same intake (exhaust) side drive mechanism M.INAccordingly, the first and second intake air among the low-speed cams 38a and 38b and the high-speed cams 39a and 39b of the first and second intake (exhaust) cam portions 37a and 37b provided in the same intake (exhaust) cam piece 30. (Exhaust) Actuated by cams switched so as to be in sliding contact with the valve lifters 32a and 32b, the intake (exhaust) cam piece 30 and the intake (exhaust) side drive mechanism for the two intake (exhaust) valves 12a and 12b MINAnd the valve operating device V can be made compact.
[0046]
Sliding contact surfaces 43a1 and 43b1 of the slipper portions 43a and 43b of the first and second intake (exhaust) valve lifters 32a and 32b are cylindrical surfaces that protrude toward the first and second intake (exhaust) cam portions 37a and 37b. Therefore, the diameter of each of the intake (exhaust) valve lifters 32a and 32b can be reduced as compared with the case where the sliding contact surfaces are flat, and the cylinder head 3 can be downsized. In addition, the slipper portions 43a and 43b are provided with the necessary rigidity despite the notches 42a1, 42a2, 42b1 and 42b2 formed through holes on the sides of the slipper portions 43a and 43b. The effect that it can ensure, achieving weight reduction, without causing the weight increase, such as making meat, is show | played.
[0047]
In the notches 42a1, 42a2, 42b1, 42b2 of the first and second intake (exhaust) valve lifters 32a, 32b, close to the maximum protruding portion of the nose portion of the high speed cams 39a, 39b passing through the notches 42a2, 42b2. Since the retainers 18a and 18b are positioned at the positions, the distance between the end portions of the valve stems 16a and 16b and the sliding contact surfaces 43a1 and 43b1 of the slipper portions 43a and 43b is made as small as possible. The effect that the apparatus V can be made compact is produced.
[0048]
Hereinafter, an example in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
[0049]
In the above embodiment, the low speed cam and the high speed cam are in sliding contact with the outer surface of the slipper portion of the intake and exhaust valve lifters.INAs shown in FIG. 7, first and second rollers 60a and 60b are provided on the top walls of the first and second intake valve lifters 32a and 32b, and the low-speed cams 38a and 38b and the high-speed cams 39a and 39b are provided. It may be a valve lifter that is in sliding contact with both the rollers 60a and 60b. That is, the first and second rollers 60a and 60b supported by the first and second support shafts 61a and 61b fixed to the first and second intake valve lifters 32a and 32b, respectively, And the first and second outer rings 62a and 62b that are in sliding contact with the low-speed cams 38a and 38b and the high-speed cams 39a and 39b, and the first and second inner rings 63a that are respectively fitted to the support shafts 61a and 61b. 63b and a plurality of rollers 64a and 64b provided between the outer rings 62a and 62b and the inner rings 63a and 63b. Further, the exhaust side valve operating device VEXAn exhaust valve lifter having a similar roller is also used. By comprising in this way, the friction between a valve lifter and a cam is reduced, and the loss of output can be reduced.
[0050]
Further, as shown in FIG. 8, the intake side drive mechanism MIN, The intake cam piece 30 extends in the direction of the rotation axis L1 between the high speed cam 39a and the low speed cam 38b and connects the first and second intake cam portions 37a and 37b with a plurality of intervals in the circumferential direction. A stiffening rib 70 may be provided, and the intake side drive mechanism MINThe position in the valve chamber 23 is closer to the cylinder 1 than the position shown in FIG. 1, and the operation portions 56a2 and 56b2 and the contact portions 57a2 and 57b2 of the pair of arms 54a and 54b are It occupies a position closer to the first and second intake valve lifters 32a and 32b than in the embodiment, and the diameter of the intake camshaft 6 is larger than the maximum protruding portion of the nose portion of the low speed cams 38a and 38b and the high speed cams 39a and 39b. You may protrude outward in the direction.
[0051]
And this intake side drive mechanism MINAs shown in FIG. 8, when the low-speed cams 38a and 38b are in sliding contact with the first and second rollers 60a and 60b of the first and second intake valve lifters 32a and 32b, respectively, in the low-speed rotation range, The operation portion 56a2 and the contact portion 57a2 near the first intake valve lifter 32a are positioned in the notch portion 42a1 although they protrude in the radial direction from the maximum protrusion portions of the nose portions of the low speed cam 38a and the high speed cam 39a. Therefore, there is no contact with the first intake valve lifter 32a. Similarly, when both the high speed cams 39a and 39b are in sliding contact with the first and second rollers 60a and 60b of the first and second intake valve lifters 32a and 32b, respectively, in the high speed rotation range, the operating portion near the second intake valve lifter 32b. Although 56b2 and the contact portion 57b2 project in the radial direction from the maximum projecting portion of the nose portion of the low speed cam 38b and the high speed cam 39b, they are located in the notch portion 42b2, and thus contact the second intake valve lifter 32b. There is nothing to do.
Further, the exhaust side valve operating device VEXIn the intake side drive mechanism MINExhaust side drive mechanism M with similar configurationEXIs used.
[0052]
Therefore, according to this embodiment, in addition to the same effects as the above embodiment, the reinforcing rib 70 is provided, so that the rigidity of the intake (exhaust) cam piece 30 is improved and the intake (exhaust) side is improved. Drive mechanism MINIs disposed closer to the cylinder 1, the height of the valve operating chamber 23 can be reduced, and the internal combustion engine E can be made compact in the height direction.
[0053]
In the above embodiment, the first cam portion and the second cam portion of the intake cam piece 30 and the exhaust cam piece 31 are both composed of a low-speed cam and a high-speed cam. The cam portion is composed of a pause cam and a high-speed cam that keep one intake valve or one exhaust valve substantially closed, and the one intake valve or one exhaust valve is closed in the low-speed rotation range. The other intake valve and the other exhaust valve may be operated with a low-speed cam, and both the intake valve and both exhaust valves may be operated with a high-speed cam in a high-speed rotation range. Similarly, in a multi-cylinder internal combustion engine, both cam portions of some cylinders are composed of a pause cam and a high-speed cam that keep the intake valve and the exhaust valve substantially closed. The intake valves and exhaust valves of some of the cylinders are closed, the cylinders are stopped, and the intake valves and exhaust valves of all cylinders are operated by high speed cams in the high speed rotation range. May be.
[0054]
In the above embodiment, the pair of intake valves and the pair of exhaust valves for each cylinder 1 are operated by separate cam portions via separate valve lifters. You may make it act | operate by a single cam part through one valve lifter.
[0055]
In the above embodiment, the drive pistons of the intake side and exhaust side drive mechanisms occupy two positions. However, the cam portion of the intake and exhaust cam pieces is composed of three cams having different cam profiles, and is driven. For example, the first hydraulic chamber 55a has a high hydraulic pressure and the second hydraulic chamber 55b has a low hydraulic pressure, and the first hydraulic chamber 55a has a high hydraulic pressure and a second hydraulic chamber so that the piston can occupy three positions. It is also possible to control the hydraulic oil so that the second state 55b becomes a high hydraulic pressure, the first hydraulic chamber 55a becomes a low hydraulic pressure, and the second hydraulic chamber 55b becomes a third state where the high hydraulic pressure becomes high. In this case as well, the cam that is not in contact with the valve lifter can pass through the notch portion of the valve lifter, so that the valve operating device can be made compact despite the provision of three cams in the cam portion. Can do.
[0056]
In the above embodiment, the internal combustion engine E has the intake camshaft 6 and the exhaust camshaft 7, but it may be a SOHC type internal combustion engine having a single camshaft. Further, one or three or more intake valves or one or three or more exhaust valves may be provided per cylinder. Further, the internal combustion engine may be a single cylinder internal combustion engine.
[0057]
In the above embodiment, a pair of arms 54a and 54b are provided. However, in the intake cam piece 30 and the exhaust cam piece 31, one arm is slidably in contact with the cylindrical portion between the first cam portion and the second cam portion. Both cam pieces 30, 31 can also be moved in the axial direction.
[Brief description of the drawings]
FIG. 1 is a partial longitudinal sectional view of an internal combustion engine to which a direct acting valve gear is applied, showing an embodiment of the present invention.
FIG. 2 is a partially exploded view of the intake side valve operating apparatus.
FIG. 3 is a partial sectional view of the intake cam piece and the intake valve lifter at a low speed position on a plane including the rotation axis of the intake cam shaft and the axis of the valve stem.
4 is a partial sectional view similar to FIG. 3 of the intake cam piece and the intake valve lifter at a high speed position.
FIG. 5 is a view taken in the direction of the arrow V in FIG. 1 and shows a state of the intake cam piece and the intake side drive mechanism at a low speed position.
FIG. 6 is a view similar to FIG. 5, showing the intake cam piece and the intake side drive mechanism at the high speed position.
FIG. 7 is another embodiment of the present invention of a direct acting valve gear including a valve lifter having a roller.
FIG. 8 is another embodiment of the present invention in which the arrangement of the driving mechanism and the cam piece are different.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cylinder, 2 ... Cylinder block, 3 ... Cylinder head, 4 ... Head cover, 5 ... Piston, 6 ... Intake cam shaft, 7 ... Exhaust cam shaft, 8 ... Cam holder, 9 ... Combustion chamber, 10 ... Intake port, 11 ... Exhaust port, 12a, 12b ... Intake valve, 13a ... Exhaust valve, 14a, 15a ... Valve guide, 16a, 16b, 17a ... Valve stem, 18a, 18b, 19a ... Retainer, 20a, 20b, 21a ... Valve spring, 22 ... Spark plug, 23 ... Valve train, 24a, 25a ... Guide groove,
30 ... Intake cam piece, 31 ... Exhaust cam piece, 32a, 32b ... Intake valve lifter, 33a ... Exhaust valve lifter, 34 ... Shaft hole, 35 ... Concave groove, 36 ... Projection, 37a, 37b ... Intake cam part, 38a, 38b ... Low speed cam, 39a, 39b ... High speed cam, 40a, 40b ... Side, 41a, 41b ... Cylindrical part, 42a1, 42a2, 42b1, 42b2 ... Notch part, 43a, 43b ... Slipper part, 44a, 44b, 45a ... Pin,
50 ... Drive piston, 51a, 51b ... Cylinder part, 52a, 52b ... Both piston part, 53 ... Connecting part, 54a, 54b ... Arm, 55a, 55b ... Hydraulic chamber, 56a1, 56a2, 56b1, 56b2 ... Operating part, 57a1 , 57a2, 57b1, 57b2 ... contact portion, 58a, 58b ... opening,
60a, 60b ... roller, 61a, 61b ... spindle, 62a, 62b ... outer ring, 63a, 63b ... inner ring, 64a, 64b ... roller,
70… Reinforcing ribs,
E: Internal combustion engine, L1, L2: Axis of rotation, V ... Valve train, VIN... Intake side valve gear, VEX... Exhaust valve operating device, MIN... Intake side drive mechanism, MEX... exhaust side drive mechanism.

Claims (5)

カム軸と共に回転するカム駒であって、カムプロフィールの異なる複数のカムが前記カム軸の回転軸線方向に隣接して設けられたカム部を有するカム駒と、前記カム部と内燃機関の吸気または排気を司る機関弁との間に配置されたバルブリフタと、前記カム部の、前記バルブリフタに摺接するカムを選択的に切り換える切換手段とを備え、前記機関弁が摺接する前記カムのカムプロフィールに応じて作動される内燃機関の直動式動弁装置において、
前記バルブリフタには、前記カム部の、前記バルブリフタに対して非接触状態にあるカムに対する逃げ用の切欠部が設けられ、
前記切欠部は、前記バルブリフタを貫通して内側と外側とを連通させる孔により形成されることを特徴とする内燃機関の直動式動弁装置。A cam piece that rotates together with the cam shaft, the cam piece having a cam portion in which a plurality of cams having different cam profiles are provided adjacent to each other in the rotation axis direction of the cam shaft; A valve lifter disposed between the engine valve that controls exhaust and switching means for selectively switching a cam of the cam portion that is in sliding contact with the valve lifter according to a cam profile of the cam that is in sliding contact with the engine valve In a direct acting valve operating device of an internal combustion engine operated by
The valve lifter is provided with a notch portion for escaping the cam portion with respect to the cam that is not in contact with the valve lifter ,
The direct acting type valve operating system for an internal combustion engine, wherein the notch is formed by a hole that penetrates the valve lifter and communicates the inside and the outside . 前記カム駒は前記カム軸に対して前記回転軸線方向に移動自在であり、
前記切換手段は、前記カム部の前記回転軸線方向での側面に当接する操作部材と、該操作部材を介して前記カム駒を前記回転軸線方向に移動させて、前記バルブリフタに摺接する前記カムを切り換える駆動部材とを備え、
前記バルブリフタには、前記操作部材に対する逃げ用の切欠部が設けられたことを特徴とする請求項１記載の内燃機関の直動式動弁装置。 Before SL cam piece is movable in the rotation axis direction relative to the camshaft,
The switching means includes: an operating member that contacts a side surface of the cam portion in the rotation axis direction; and the cam that slides on the valve lifter by moving the cam piece in the rotation axis direction via the operation member. A drive member for switching,
2. The direct acting valve operating apparatus for an internal combustion engine according to claim 1 , wherein the valve lifter is provided with a notch for escaping from the operation member. 前記操作部材に対する逃げ用の前記切欠部は、前記バルブリフタを貫通して内側と外側とを連通させる孔により形成されることを特徴とする請求項２記載の内燃機関の直動式動弁装置。Said notch for relief against the operating member, linear Shikidoben for an internal combustion engine 請 Motomeko 2 wherein you being formed by holes for communicating the inside and the outside through said valve lifter apparatus. 前記切欠部は、前記バルブリフタの頂壁から前記回転軸線方向での両側でバルブリフタの側壁に渡って、前記頂壁の一部および前記側壁の一部が切除されて形成された１対の切欠部であることを特徴とする請求項１または請求項３記載の内燃機関の直動式動弁装置。 The notch is a pair of notches formed by cutting a part of the top wall and a part of the side wall from the top wall of the valve lifter to the side wall of the valve lifter on both sides in the rotational axis direction. direct acting type valve gear according to claim 1 or claim 3 Symbol placement of the internal combustion engine, characterized in that it. 前記バルブリフタの前記頂壁は、前記１対の切欠部の間を前記頂壁の直径方向に延びるブリッジ状のスリッパ部を形成し、The top wall of the valve lifter forms a bridge-like slipper portion extending in the diameter direction of the top wall between the pair of notches,
前記カムが摺接する前記スリッパ部の摺接面は、前記回転軸線方向から見たとき、前記カム部に向かって凸となる円弧になっていることを特徴とする請求項４記載の内燃機関の直動式動弁装置。5. The internal combustion engine according to claim 4, wherein the sliding contact surface of the slipper portion with which the cam is slidably contacted is an arc that is convex toward the cam portion when viewed from the direction of the rotation axis. Direct acting valve gear.
JP2000335160A 2000-06-23 2000-11-01 Direct acting valve gear for internal combustion engine Expired - Fee Related JP4183378B2 (en)

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