JP3767351B2

JP3767351B2 - Variable valve mechanism for internal combustion engine

Info

Publication number: JP3767351B2
Application number: JP2000271957A
Authority: JP
Inventors: 学立野
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 1999-12-17
Filing date: 2000-09-07
Publication date: 2006-04-19
Anticipated expiration: 2020-09-07
Also published as: JP2001234722A

Description

【０００１】
【発明の属する技術分野】
本発明は、内燃機関の可変動弁機構に関する。
【０００２】
【従来の技術】
カムシャフトに配置された第一カム及び第二カムと、第一カム及び第二カムと吸気弁との間に介在するスイングアームのような動作伝達部材とを具備し、選択された一方のカム動作によって吸気弁又は排気弁を開弁する可変動弁機構が公知である。例えば、第一カムは吸気弁の低リフトを実現するための低リフトカムであり、第二カムは吸気弁の高リフトを実現するための高リフトカムであり、動作伝達部材は、回動軸線に沿って互いに隣接し、第一カムにより回動させられて吸気弁に当接する主部分と、第二カムにより回動させられて主部分へ連結可能な副部分とを有している。
【０００３】
副部分を主部分へ連結すれば、高リフトカムが副部分を介して主部分を作動させ、吸気弁は、高リフトで開弁させられる。この時、低リフトカムの山部は主部分とは非当接となる。一方、副部分を主部分から切り離せば、高リフトカムは副部分を作動させるが、副部分の動作は吸気弁へ伝達されず、吸気弁は、低リフトカムによる主部分の作動によって、低リフトで開弁させられる。こうして、機関高速時に適した吸気弁の高リフトと、機関低速時に適した吸気弁の低リフトとを実現可能となる。
【０００４】
このような可変動弁機構において、一般的に、動作伝達部材の主部分と副部分とは、互いに回動軸線に垂直な摺動面を有し、一方の摺動面に形成された穴内へ他方の摺動面からピンを突出させることにより互いに連結され、ピンを引っ込めることにより結合解除される。このような連結構造においては、連結時において、ピンに剪断力又は曲げ力が作用し、ピンに高い強度が必要とされ、ピンの大型化等の問題が発生する。
【０００５】
特開平１０−２２０２１０号公報に開示されている可変動弁機構は、動作伝達部材の主部分と副部分とが、それぞれ、互いに向けて回動軸線方向に突出する突出部を有し、各突出部には回動軸線に平行で互いに対向する対向面が設けられ、各対向面は、副部分が第二カムによって回動させられる時に互いに接近するようになっている。主部分及び副部分の一方から各対向面の間にピンを押し出せば、高リフトカムによる副部分の回動動作が主部分へ伝達されて吸気弁を高リフトで開弁し、各対向面の間からピンを引っ込めれば、高リフトカムによる副部分の回動動作は、各対向面を接近させるが、主部分へは伝達されず、低リフトカムによる主部分の回動動作によって吸気弁は低リフトで開弁する。それにより、ピンには、剪断力及び曲げ力ではなく、圧縮力だけが作用し、一般的な材料は圧縮力に対しては非常に強いために、ピンの大型化の問題を解決することができる。
【０００６】
【発明が解決しようとする課題】
前述の従来技術において、ピンを押し出して高リフトカムにより吸気弁を作動し続ける際に、バルブスプリングのサージング等によって、動作伝達部材の主部分は、突出部対向面がピンから離れるように、異常に回動し、それにより、吸気弁が異常に押し下げられて閉弁時に破損したり、反動によって主部分の突出部対向面がピンに激しく衝突し、主部分及びピンが破損する可能性がある。
【０００７】
従って、本発明の目的は、主部分と副部分とを有する動作伝達部材を具備し、主部分の突出部端面と副部分の突出部端面との間に介在部材を押し出すことにより、カムによる副部分の回動動作を主部分を介して吸気弁又は排気弁へ伝達可能な可変動弁機構において、バルブスプリングのサージング等による主部分の異常回動を防止することである。
【０００８】
【課題を解決するための手段】
本発明による請求項１に記載の内燃機関の可変動弁機構は、第一カム及び第二カムと、動作伝達部材とを具備し、前記動作伝達部材は、前記第一カムにより回動させられて吸気弁又は排気弁に当接する主部分と、前記第二カムにより回動させられる副部分とを有し、前記主部分と前記副部分とは少なくとも互いに平行なそれぞれの回動軸線方向に互いに隣接し、前記主部分は、前記副部分へ向けて前記回動軸線方向に突出する第一突出部を有し、前記副部分は、前記主部分へ向けて前記回動軸線方向に突出する第二突出部を有し、前記第一突出部は、前記主部分の前記吸気弁又は排気弁の開弁への回動方向における第一前側端面と第一後側端面とを有し、前記第二突出部は、前記副部分の前記吸気弁又は排気弁の開弁への回動方向における第二前側端面と第二後側端面とを有し、前記第一前側端面と前記第二後側端面とは互いに対向し、前記第一後側端面と前記第二前側端面とは互いに対向し、前記第一後側端面と前記第二前側端面との間へ押し出し可能な介在部材が設けられ、前記介在部材が押し出されていない時には、前記副部分は前記主部分に対して自由に回動し、前記介在部材が押し出された時には、前記第二カムによる前記副部分の回動動作は、前記吸気弁又は排気弁を開弁するために、前記介在部材を介して前記主部分へ伝達されると共に、前記第一前側端面は前記第二後側端面にほぼ当接していることを特徴とする。
【０００９】
また、本発明による請求項２に記載の内燃機関の可変動弁機構は、第一カム、第二カム及び第三カムと、動作伝達部材とを具備し、前記動作伝達部材は、前記第一カムにより回動させられて吸気弁又は排気弁に当接する主部分と、前記第二カムにより回動させられる第一副部分とを有し、前記主部分と前記第一副部分とは少なくとも互いに平行なそれぞれの回動軸線方向に互いに隣接し、前記主部分は、前記第一副部分へ向けて前記回動軸線方向に突出する第一突出部を有し、前記第一副部分は、前記主部分へ向けて前記回動軸線方向に突出する第二突出部を有し、前記第一突出部は、前記主部分の前記吸気弁又は排気弁の開弁への回動方向における第一前側端面と第一後側端面とを有し、前記第二突出部は、前記第一副部分の前記吸気弁又は排気弁の開弁への回動方向における第二前側端面と第二後側端面とを有し、前記第一後側端面と前記第二前側端面とは互いに対向し、前記第一後側端面と前記第二前側端面との間へ押し出し可能な第一介在部材が設けられ、前記第一介在部材が押し出されていない時には、前記第一副部分は前記主部分に対して自由に回動し、前記第一介在部材が押し出された時には、前記第二カムによる前記第一副部分の回動動作は、前記吸気弁又は排気弁を開弁するために、前記第一介在部材を介して前記主部分へ伝達され、前記第三カムは前記第二カムの形状より外側に突出しない形状を有し、前記動作伝達部材は、前記第三カムにより回動させられる第二副部分を有し、前記主部分と前記第二副部分とは少なくとも互いに平行なそれぞれの回動軸線方向に互いに隣接し、前記主部分は、前記第二副部分へ向けて前記回動軸線方向に突出する第三突出部を有し、前記副部分は、前記主部分へ向けて前記回動軸線方向に突出する第四突出部を有し、前記第三突出部は、前記主部分の前記吸気弁又は排気弁の開弁への回動方向における第三前側端面と第三後側端面とを有し、前記第四突出部は、前記第二副部分の前記吸気弁又は排気弁の開弁への回動方向における第四前側端面と第四後側端面とを有し、前記第三後側端面と前記第四前側端面とは互いに対向し、前記第三後側端面と前記第四前側端面との間へ押し出し可能な第二介在部材が設けられ、前記第二介在部材が押し出されていない時には、前記第二副部分は前記主部分に対して自由に回動し、前記第二介在部材が押し出された時には、前記第三カムによる前記第二副部分の回動動作は、前記吸気弁又は排気弁を開弁するために、前記第二介在部材を介して前記主部分へ伝達されると共に、前記第三前側端面は前記第四後側端面から離間し、前記第一介在部材及び前記第二介在部材がいずれも押し出されている時に、前記第二カムによる前記第一副部材の回動動作が前記第二副部材へ伝達されないようになっていることを特徴とする。
【００１０】
【発明の実施の形態】
図１は本発明による内燃機関の可変動弁機構における実施形態を示す側面図であり、図２は同平面図であり、図３は同分解斜視図である。これらの図において、１は吸気弁又は排気弁（以下、バルブと称する）であり、１ａはバルブ１を閉弁方向に付勢するバルブスプリングである（図２及び図３においては省略されている）。２はカムシャフトであり、３１はカムシャフト２に配置された第一カムである。カムシャフト２には、第一カム３１の両側において、第二カム３２及び第三カム３３が配置されている。
【００１１】
４は各カム３１〜３３の動作をバルブへ伝達するロッカアーム及びスイングアーム等の動作伝達部材である。動作伝達部材４は、いずれも共通の回動軸５回りに回動する主部分４１、第一副部分４２、及び第二副部分４３を有している。第一副部分４２及び第二副部分４３は、主部分４１に対して回動軸５の回動軸線方向に沿って両側に隣接している。主部分４１、第一副部分４２、及び第二副部分４３は、それぞれ、第一カム３１、第二カム３２、及び第三カム３３に当接するためのローラＲを有している。主部分４２には、二つのバルブ１に同時に当接する押圧アーム４１ａが設けられている。
【００１２】
図３に示すように、主部分４１は、第一副部分４２へ向けて回動軸線方向に突出する第一突出部４１ｂを有し、第一副部分４２は、主部分４１へ向けて回動軸線方向に突出する第二突出部４２ｂを有している。図４は、回動軸線に垂直で第一突出部４１ｂ及び第二突出部４２ｂを通る断面図である。図４に示すように、第一突出部４１ｂは、主部分４１のバルブ１の開弁への回動方向（図３及び図４に矢印で示す）における第一前側端面４１ｃと第一後側端面４１ｄとを有し、第二突出部４２ｂは、第一副部分４２のバルブ１の開弁への回動方向における第二前側端面４２ｃと第二後側端面４２ｄとを有し、第一前側端面４１ｃと第二後側端面４２ｄとは互いに対向し、第一後側端面４１ｄと第二前側端面４２ｃとは互いに対向している。
【００１３】
第一後側端面４１ｄと第二前側端面４２ｃとの間にはピンのような第一介在部材４４が設けられている。図４のＡ−Ａ断面図である図５に示すように、第一介在部材４４は、バネ４５によって第一後側端面４１ｄと第二前側端面４２ｃとの間から第一副部分４２内へ引っ込むように付勢されている。一方、第一副部分４２内の圧力室４６内に油圧が作用する時には、第一介在部材４４における押し出し側の受圧面積と引っ込め側の受圧面積との差により発生する押し出し力によって、第一介在部材４４はバネ４５に逆らって第一後側端面４１ｄと第二前側端面４２ｃとの間へ押し出されるようになっている。
【００１４】
動作伝達部材４の主部分４１は、前述したように、バルブ１に当接する押圧アーム４１ａを有しているために、バルブスプリング１ａによって、バルブ１の閉弁への回動方向に付勢されている。一方、第一副部分４２及び第二副部分４３も、それぞれ、バネ４７及び４８によって、バルブ１の閉弁への回動方向に付勢されている。
【００１５】
主部分４１の第一突出部４１ｂ及び第一副部分４２の第二突出部４２ｂは、バルブスプリング１ａ及びバネ４７による前述の付勢によって、第一カム３１及び第二カム３２が主部分４１及び第一副部分４２を作動しない時には、図４に示すように、第一突出部４１ｂの第一後側端面４１ｄと第二突出部４２ｂの第二前側端面４２ｃとの間に、第一介在部材４４の押し出しを可能とする隙間がもたらされると共に、第一突出部４１ｂの第一前側端面４１ｃと第二突出部４２ｂの第二後側端面４２ｄとは互いに当接するように形成されている。
【００１６】
図１に示すように、第一カム３１は低リフトカムであり、第二カム３２は高リフトカムであり、第一カム３１のカム形状は、第二カム３２のカム形状より外側に突出していない。第一副部分４２内の油圧室４６に油圧が作用していない時には、バネ４５によって第一介在部材４４は第一副部分４２内へ引っ込められている。それにより、バルブ１の閉弁方向において、第一副部分４２は、第一カム３１によって回動させられる主部分４１に比較して、第二カム３２によって大きく回動させられるが、第一突出部４１ｂの第一後側端面４１ｄと第二突出部４２ｂの第二前側端面４２ｃとの間の隙間によって、第一副部分４２は、主部分４１に対して自由に回動し、第一副部分４２の動作が主部分４１へ伝達されることはなく、バルブ１は、第一カム３１による主部分４１の回動動作によって低リフトで開弁させられる。
【００１７】
一方、第一副部分４２内の油圧室４６に油圧が作用している時には、第一突出部４１ｂの第一後側端面４１ｄと第二突出部４２ｂの第二前側端面４２ｃとの間の隙間には、第一介在部材４４が押し出され、第二カム３２による第一副部分の回動動作は第一介在部材４４を介して主部分４１へ伝達される。それにより、第一カム３１の山部は主部分４１に対して非接触となり、バルブ１は第二カム３２によって高リフトで開弁させられる。この時、第一介在部材４４は、第一突出部４１ｂの第一後側端面４１ｄと第二突出部４２ｂの第二前側端面４２ｃとによって圧縮されることとなるが、一般的な材料は、剪断及び曲げに比較して圧縮に対しては強く、第一介在部材４４をそれほど大きくしなくても第一介在部材４４が破損するようなことはない。
【００１８】
本実施形態において、第一突出部４１ｂの第一後側端面４１ｄ及び第二突出部４２ｂの第二前側端面４２ｃは、圧縮時の応力集中を防止するために、それぞれ、円形断面の第一介在部材４４に対して面接触するような凹部を有している。
【００１９】
こうして、第一副部分４２を介してバルブ１を高リフトで開弁している時に、一般的な可変動弁機構では、主部分４１の第一突出部４１ｂにおける第一前側端面４１ｃと第一副部分４２の第二突出部４２ｂにおける第二後側端面４２ｄとの間に比較的大きな隙間が存在するために、バルブスプリング１ａのサージング等によって、主部分４１は、第一突出部４１ｂの第一後側端面４１ｄが第一介在部材４４から離れるように、異常に回動し、それにより、バルブ１が異常に押し下げられて閉弁時に破損したり、反動によって主部分４１の第一突出部４１ｂにおける第一後側端面４１ｄが第一介在部材４４に激しく衝突し、第一突出部４１ｂ及び第一介在部材４４が破損する可能性がある。
【００２０】
しかしながら、本実施形態では、第一副部分４２を介してバルブ１を高リフトで開弁している時に、主部分４１の第一突出部４１ｂにおける第一前側端面４１ｃと第一副部分４２の第二突出部４２ｂにおける第二後側端面４２ｄとは互いに当接しており、このような主部分４１の異常回動が発生することはなく、第一突出部４１ｂ及び第一介在部材４４の破損を防止することができる。もちろん、主部分４１の第一突出部４１ｂにおける第一前側端面４１ｃと第一副部分４２の第二突出部４２ｂにおける第二後側端面４２ｄとの間の隙間が、一般的な可変動弁機構とは異なり僅かであれば、バルブ１が異常に押し下げられるような主部分４１の異常回動を防止することができる。
【００２１】
本実施形態において、第二副部分４３は、図３及び図５に示すように、第一副部分４２と同様な構成を有している。図６に示すように、主部分４１は、第二副部分４３へ向けて回動軸線方向に突出する第三突出部４１ｅを有し、第二副部分４３は、主部分４１へ向けて回動軸線方向に突出する第四突出部４３ｂを有している。図６は、回動軸線に垂直で第三突出部４１ｅ及び第四突出部４３ｂを通る断面図である。図６に示すように、第三突出部４１ｅは、主部分４１のバルブ１の開弁への回動方向（図３及び図６に矢印で示す）における第三前側端面４１ｆと第三後側端面４１ｇとを有し、第四突出部４３ｂは、第二副部分４３のバルブ１の開弁への回動方向における第四前側端面４３ｃと第四後側端面４３ｄとを有し、第三前側端面４１ｆと第四後側端面４３ｄとは互いに対向し、第三後側端面４１ｇと第四前側端面４３ｃとは互いに対向している。
【００２２】
第三後側端面４１ｇと第四前側端面４３ｃとの間には前述したと同様な第二介在部材４４’が設けられている。図５に示すように、第二介在部材４４’は、バネ４５’によって第三後側端面４１ｇと第四前側端面４３ｃとの間から第二副部分４３内へ引っ込むように付勢されている。一方、第二副部分４３内の圧力室４６’内に油圧が作用する時には、前述同様に、第二介在部材４４’はバネ４５’に逆らって第三後側端面４１ｅと第四前側端面４３ｃとの間へ押し出されるようになっている。
【００２３】
主部分４１の第三突出部４１ｅ及び第二副部分４３の第四突出部４３ｂは、バルブスプリング１ａ及びバネ４８による前述の付勢によって、第一カム３１及び第三カム３３が主部分４１及び第二副部分４３を作動しない時には、図６に示すように、第三突出部４１ｅの第三後側端面４１ｇと第四突出部４３ｂの第四前側端面４３ｃとの間に、第二介在部材４４’の押し出しを可能とする隙間がもたらされると共に、第三突出部４１ｅの第三前側端面４１ｆと第四突出部４３ｂの第四後側端面４３ｄとは互いに離間するように形成されている。
【００２４】
第二副部分４３に当接する第三カム３３は、図１に示すように、中リフトカムであり、第一カム３１のカム形状は、第三カム３３のカム形状より外側に突出していない。また、第三カム３３のカム形状は、第二カム３２のカム形状より外側に突出していない。第二副部分４３内の油圧室４６’に油圧が作用していない時には、バネ４５’によって第二介在部材４４’は第二副部分４３内へ引っ込められている。それにより、第三突出部４１ｅの第三後側端面４１ｇと第四突出部４３ｂの第四前側端面４３ｃとの間の隙間によって、第二副部分４３は、主部分４１に対して自由に回動し、第二副部分４２の動作が主部分４１へ伝達されることはない。一方、第二副部分４３内の油圧室４６’に油圧が作用している時には、第三突出部４１ｅの第三後側端面４１ｇと第四突出部４３ｂの第四前側端面４３ｃとの間の隙間には、第二介在部材４４’が押し出され、第三カム３３による第一副部分の回動動作は第二介在部材４４’を介して主部分４１へ伝達される。それにより、第一カム３１の山部は主部分４１に対して非接触となり、バルブ１は第三カム３３によって中リフトで開弁させられる。
【００２５】
こうして、第一介在部材４４を押し出せば、第二カム３２によって第一副部分４２を介してバルブ１を高リフトで開弁させることができ、第一介在部材４４を引っ込めて第二介在部材４４’を押し出せば、第三カム３３によって第二副部分４３を介してバルブ１を中リフトで開弁させることができる。本実施形態では、第三カム３３のカム形状は、第二カム３２のカム形状より外側に突出しないようにされているために、二つの介在部材４４，４４’を押し出していても、第二カム３２によってバルブ１を高リフトで開弁させることが可能である。
【００２６】
このような場合において、第二カム３２によって第一副部分４２及び主部分４１が作動させられる時に、主部分４１の第三突出部４１ｅにおける第三前側端面４１ｆと第二副部分４３の第四突出部４３ｂにおける第四後側端面４３ｄとの間に比較的大きな隙間が存在するために、第一副部分４２の動作が主部分４１を介して第二副部分４３へ伝達されず、第二副部分４３は第三カム３３によってだけ作動させられる。
【００２７】
もし、第一副部分４２の動作が第二副部分４３へ伝達されるならば、第二カム３２は、第一副部分４２及び主部分４１に加えて第二副部分４３を回動させることとなり、可動部重量が大きくなるために、カムシャフト２の必要トルクを増大させる。
【００２８】
また、第二副部分４３が高リフトカムである第二カム３２によって回動させられるならば、第二副部分４３を戻すためのバネ４８を、第一副部分４２を戻すためのバネ４７と同様に強いものとしなければならず、これは、第三カム３３によってバルブ１を中リフトで開弁させる際に、第二副部分４３の回動抵抗を増大させ、カムシャフト２の必要トルクを増大させる。
【００２９】
もちろん、第二介在部材４４’を引っ込めた後に第一介在部材４４を押し出すことにより、主部分４１の第三突出部４１ｅにおける第三前側端面４１ｆと第二副部分４３の第四突出部４３ｂにおける第二後側端面４３ｄとを当接させていても、第二副部分４３が第一副部分４２と共に回動することは防止されるが、このような制御では、バルブリフトが、中リフトから低リフトを介して高リフトへ移行することとなり、実際の機関運転には適さない。従って、バルブリフトを低リフトを介さずに中リフトから高リフトへ移行させるためには、どうしても第一介在部材４４と第二介在部材４４’とが同時に押し出されている期間が存在して前述の問題を発生させるために、本実施形態のように、第二カム３２によって第一副部分４３及び主部分４１が作動させられる時に、主部分４１の第三突出部４１ｅにおける第三前側端面４１ｆと第二副部分４３の第四突出部４３ｂにおける第四後側端面４３ｄとの間に比較的大きな隙間を設けることは、前述したカムシャフト２の必要トルク増大の問題解決に有効である。
【００３０】
この一方で、バルブ１の高リフト運転時で説明したと同様に、第三カム３３による中リフト運転時には、第三突出部４１ｅの第三後側端面４１ｇが第二介在部材４４’から離れるように回動することができるようになってしまう。しかしながら、これを引き起こすバルブスプリング１ａのサージングは、主に機関高回転時において発生し、バルブ１を中リフトで開弁する機関中回転時には殆ど発生しないために特に問題とはならない。
【００３１】
このように、主部分４１の両側に第一副部分４２及び第二副部分４３が設けられ、第二副部分４３を作動させる第三カム３３の形状が、第一副部分４２を作動させる第二カム３２の形状の内側に納まっている場合には、第一介在部材４４及び第二介在部材４４’のいずれも押し出す場合を想定して、主部分４１の第三突出部４１ｅにおける第三前側端面４１ｆと第二副部分４３の第四突出部４３ｂにおける第四後側端面４３ｄとを当接させるよりも、両方の間に比較的大きな隙間を設ける方が有利である。また、この場合において、図４に相当する図７に示すように、第一副部分４１の第二突出部４２ｂの第二後側端面４２ｄと、主部分４１の第一突出部４１ｂの第一前側端面４１ｃとを当接させることなく離間させていても、前述したカムシャフト２の必要トルク増大の問題は解決することができる。
【００３２】
動作伝達部材４の回動軸５内に形成された二つの通路５ａ，５ｂは、第一副部分４２の油圧室４６及び第二副部分４３の油圧室（図示せず）のそれぞれへ油圧を供給するための通路である。
【００３３】
本実施形態において、動作伝達部材４の主部分４１に当接する第一カム３１を低リフトカムとして、第一副部分４２に当接する第二カム３２を高リフトカムとしたが、これは本発明を限定するものではなく、例えば、バルブ１が吸気弁の場合において、第二カム３２は、吸気弁を排気行程で開弁させるためのカムとしても良い。この場合において、第一介在部材４４を第一副部分４２から押し出せば、吸気弁は、主部分４１によって吸気行程で開弁させられることに加えて、第一副部分４２によって排気行程で開弁させられ、排気ガスの一部を機関吸気系に逆流させて内部的に排気ガス再循環を実施することが可能となる。本実施形態によれば、主部分４１の第一突出部４１ｂと第一副部分４２の第二突出部４２ｂとの前述した当接によって、この排気行程での吸気弁の開弁時において、主部分４１の異常回動を防止することが可能となる。また、第二カム３２を高リフトカムとして、第三カム３３を、排気行程で吸気弁を開弁させるためのカムとする場合には、第一介在部材４４及び第二介在部材４４’のいずれも押し出していれば、吸気弁は、吸気行程において高リフトで開弁させられると共に排気行程で開弁させられ、第二介在部材４４’を引っ込めれば、吸気弁は、吸気行程で高リフトで開弁させられるだけである。このように、第一介在部材４４及び第二介在部材４４’のこれら二つの状態によって、吸気弁に異なる動作をさせる場合、すなわち、第三カム３３が第二カム３２の形状から突出する形状である場合には、主部分４１の第三突出部４１ｅと第二副部分４３の第四突出部４２ｂとを前述のように離間させても意味はなく、第二介在部材４４’だけを押し出して、吸気弁を吸気行程において低リフトで開弁（第一カム３１によって）させると共に排気行程において開弁（第三カム３３によって）させる時の主部分４１の異常回動を防止するために、主部分４１の第三突出部４１ｅと第二副部分４３の第四突出部４２ｂとを当接させることが好ましい。本実施形態において、動作伝達部材４の主部分４１、第一副部分４２、及び第二副部分４３は、共通の回動軸線回りに回動するようにしたが、これは本発明を限定するものではなく、各部分を少なくとも互いに平行な異なる回動軸線回りに回動させるようにしても良い。
【００３４】
【発明の効果】
このように、本発明による内燃機関の可変動弁機構は、第一カム及び第二カムと、動作伝達部材とを具備し、動作伝達部材は、第一カムにより回動させられて吸気弁又は排気弁に当接する主部分と、第二カムにより回動させられる副部分とを有し、主部分と副部分とは少なくとも互いに平行なそれぞれの回動軸線方向に互いに隣接し、主部分は、副部分へ向けて回動軸線方向に突出する第一突出部を有し、副部分は、主部分へ向けて回動軸線方向に突出する第二突出部を有し、第一突出部は、主部分の吸気弁又は排気弁の開弁への回動方向における第一前側端面と第一後側端面とを有し、第二突出部は、副部分の吸気弁又は排気弁の開弁への回動方向における第二前側端面と第二後側端面とを有し、第一前側端面と第二後側端面とは互いに対向し、第一後側端面と第二前側端面とは互いに対向し、第一後側端面と第二前側端面との間へ押し出し可能な介在部材が設けられ、介在部材が押し出されていない時には、副部分は主部分に対して自由に回動し、介在部材が押し出された時には、第二カムによる副部分の回動動作は、吸気弁又は排気弁を開弁するために、介在部材を介して主部分へ伝達されると共に、第一前側端面は第二後側端面にほぼ当接している。それにより、副部分の回動動作が介在部材を介して主部分へ伝達される時に、バルブスプリングのサージング等によって、第一突出部の第一後側端面が介在部材から離れるように、主部分が異常に回動しようとしても、この回動は、第一突出部の第一前側端面が第二突出部の第二後側端面にほぼ当接しているために防止される。こうして、吸気弁が異常に押し下げられて閉弁時に破損したり、反動によって主部分の第一突出部が介在部材に激しく衝突し、主部分及び介在部材が破損することが防止可能となる。
【００３５】
また、本発明によるもう一つの内燃機関の可変動弁機構は、第一カム、第二カム及び第三カムと、動作伝達部材とを具備し、動作伝達部材は、第一カムにより回動させられて吸気弁又は排気弁に当接する主部分と、第二カムにより回動させられる第一副部分とを有し、主部分と第一副部分とは少なくとも互いに平行なそれぞれの回動軸線方向に互いに隣接し、主部分は、第一副部分へ向けて回動軸線方向に突出する第一突出部を有し、第一副部分は、主部分へ向けて回動軸線方向に突出する第二突出部を有し、第一突出部は、主部分の吸気弁又は排気弁の開弁への回動方向における第一前側端面と第一後側端面とを有し、第二突出部は、第一副部分の吸気弁又は排気弁の開弁への回動方向における第二前側端面と第二後側端面とを有し、第一後側端面と第二前側端面とは互いに対向し、第一後側端面と第二前側端面との間へ押し出し可能な第一介在部材が設けられ、第一介在部材が押し出されていない時には、第一副部分は主部分に対して自由に回動し、第一介在部材が押し出された時には、第二カムによる第一副部分の回動動作は、吸気弁又は排気弁を開弁するために、第一介在部材を介して主部分へ伝達され、第三カムは第二カムの形状より外側に突出しない形状を有し、動作伝達部材は、第三カムにより回動させられる第二副部分を有し、主部分と第二副部分とは少なくとも互いに平行なそれぞれの回動軸線方向に互いに隣接し、主部分は、第二副部分へ向けて回動軸線方向に突出する第三突出部を有し、副部分は、主部分へ向けて回動軸線方向に突出する第四突出部を有し、第三突出部は、主部分の吸気弁又は排気弁の開弁への回動方向における第三前側端面と第三後側端面とを有し、第四突出部は、第二副部分の吸気弁又は排気弁の開弁への回動方向における第四前側端面と第四後側端面とを有し、第三後側端面と第四前側端面とは互いに対向し、第三後側端面と第四前側端面との間へ押し出し可能な第二介在部材が設けられ、第二介在部材が押し出されていない時には、第二副部分は主部分に対して自由に回動し、第二介在部材が押し出された時には、第三カムによる第二副部分の回動動作は、吸気弁又は排気弁を開弁するために、第二介在部材を介して主部分へ伝達されると共に、第三前側端面は第四後側端面から離間し、第一介在部材及び第二介在部材がいずれも押し出されている時に、第二カムによる第一副部材の回動動作が第二副部材へ伝達されないようになっている。それにより、第一介在部材及び第二介在部材のいずれも押し出されている時に、第二カムが第一副部材と主部材とに加えて第二副部材を回動させることはなく、可動部重量の増大によってカムシャフトの必要トルクが増大することを防止することができる。
【図面の簡単な説明】
【図１】本発明による内燃機関の可変動弁機構における実施形態を示す側面図である。
【図２】図１の可変動弁機構の平面図である。
【図３】図１の可変動弁機構の分解斜視図である。
【図４】動作伝達部材の主部分の第一突出部と第一副部分の第二突出部とを回動軸線に垂直に通る断面図である。
【図５】図４のＡ−Ａ断面図である。
【図６】動作伝達部材の主部分の第三突出部と第二副部分の第四突出部とを回動軸線に垂直に通る断面図である。
【図７】図４とは異なる形状の第一突出部と第二突出部とを回動軸線に垂直に通る断面図である。
【符号の説明】
１…バルブ
４…動作伝達部材
３１…第一カム
３２…第二カム
３３…第三カム
４１…主部分
４１ｂ…第一突出部
４１ｃ…第一前側端面
４１ｄ…第一後側端面
４１ｅ…第三突出部
４１ｆ…第三前側端面
４１ｇ…第三後側端面
４２…第一副部分
４２ｂ…第二突出部
４２ｃ…第二前側端面
４２ｄ…第二後側端面
４３…第二副部分
４３ｂ…第四突出部
４３ｃ…第四前側端面
４３ｄ…第四後側端面
４４…第一介在部材
４４’…第二介在部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable valve mechanism for an internal combustion engine.
[0002]
[Prior art]
One selected cam comprising a first cam and a second cam disposed on the camshaft, and a motion transmission member such as a swing arm interposed between the first cam and the second cam and the intake valve A variable valve mechanism that opens an intake valve or an exhaust valve by operation is known. For example, the first cam is a low lift cam for realizing a low lift of the intake valve, the second cam is a high lift cam for realizing a high lift of the intake valve, and the motion transmission member is along the rotation axis. And a main portion that is rotated by the first cam and contacts the intake valve, and a sub-portion that is rotated by the second cam and can be connected to the main portion.
[0003]
If the sub part is connected to the main part, the high lift cam operates the main part via the sub part, and the intake valve is opened with high lift. At this time, the peak portion of the low lift cam is not in contact with the main portion. On the other hand, if the sub-portion is separated from the main portion, the high lift cam operates the sub-portion, but the operation of the sub-portion is not transmitted to the intake valve, and the intake valve opens with low lift by the operation of the main portion by the low lift cam. Be made to speak. In this way, it is possible to realize a high lift of the intake valve suitable at high engine speed and a low lift of the intake valve suitable at low engine speed.
[0004]
In such a variable valve mechanism, generally, the main portion and the sub portion of the motion transmitting member have sliding surfaces perpendicular to the rotation axis, and into a hole formed in one sliding surface. The pins are connected to each other by projecting the pins from the other sliding surface, and the coupling is released by retracting the pins. In such a connection structure, at the time of connection, a shearing force or a bending force acts on the pin, and a high strength is required for the pin, causing problems such as an increase in the size of the pin.
[0005]
In the variable valve mechanism disclosed in Japanese Patent Laid-Open No. 10-220210, the main part and the sub part of the operation transmitting member have protrusions that protrude in the rotation axis direction toward each other. The part is provided with opposing surfaces parallel to the rotation axis and facing each other, and the opposing surfaces approach each other when the sub-portion is rotated by the second cam. If a pin is pushed out from one of the main part and the sub part between the opposing surfaces, the rotation of the sub part by the high lift cam is transmitted to the main part, and the intake valve is opened with a high lift. If the pin is retracted from between, the rotation of the sub part by the high lift cam brings the opposing surfaces closer to each other, but it is not transmitted to the main part, and the intake valve is lowered by the rotation of the main part by the low lift cam. To open the valve. As a result, only the compression force acts on the pin, not the shearing force and the bending force, and the general material is very strong against the compression force. it can.
[0006]
[Problems to be solved by the invention]
In the above prior art, when the pin is pushed out and the intake valve is continuously operated by the high lift cam, the main portion of the motion transmission member is abnormally separated from the pin by the surging of the valve spring or the like. Accordingly, there is a possibility that the intake valve is abnormally pushed down and damaged when the valve is closed, or the protrusion-facing surface of the main part collides with the pin violently due to the reaction, and the main part and the pin are damaged.
[0007]
Accordingly, an object of the present invention is to provide a motion transmitting member having a main portion and a sub portion, and by pushing an intervening member between the protruding portion end surface of the main portion and the protruding portion end surface of the sub portion, In a variable valve mechanism that can transmit the rotation of the part to the intake valve or the exhaust valve through the main part, it is to prevent the main part from rotating abnormally due to surging of the valve spring or the like.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, the variable valve mechanism for an internal combustion engine includes a first cam, a second cam, and a motion transmission member, and the motion transmission member is rotated by the first cam. A main portion that contacts the intake valve or the exhaust valve and a sub-portion rotated by the second cam, and the main portion and the sub-portion are at least parallel to each other in their respective rotation axis directions. The main part has a first protrusion that protrudes in the direction of the rotation axis toward the sub part, and the sub part protrudes in the direction of the rotation axis toward the main part. The first protrusion has a first front end face and a first rear end face in the direction of rotation of the main portion toward the opening of the intake valve or the exhaust valve. The two protrusions are the first in the direction of rotation of the sub-portion to open the intake valve or exhaust valve. A front end face and a second rear end face, the first front end face and the second rear end face oppose each other, the first rear end face and the second front end face oppose each other, An interposition member that can be pushed out between the first rear end face and the second front end face is provided, and when the interposition member is not pushed out, Deputy The portion freely rotates with respect to the main portion, and when the interposition member is pushed out, the rotation operation of the sub-portion by the second cam is to open the intake valve or the exhaust valve. The first front end face is substantially in contact with the second rear end face while being transmitted to the main portion via the interposition member.
[0009]
According to a second aspect of the present invention, there is provided a variable valve mechanism for an internal combustion engine comprising a first cam, a second cam, a third cam, and a motion transmission member, wherein the motion transmission member is the first cam. A main portion that is rotated by a cam and abuts against an intake valve or an exhaust valve; and a first subportion that is rotated by the second cam, wherein the main portion and the first subportion are at least mutually Adjacent to each other in the respective rotation axis directions parallel to each other, the main portion has a first protrusion that protrudes in the rotation axis direction toward the first sub-portion, and the first sub-portion is A second projecting portion projecting in the direction of the rotational axis toward the main portion, wherein the first projecting portion is a first front side in the rotational direction of the main portion toward the valve opening of the intake valve or exhaust valve; An end face and a first rear end face, and the second projecting portion is the intake valve or the first sub-portion. A second front side end surface and a second rear side end surface in the direction of rotation of the exhaust valve to open, the first rear side end surface and the second front side end surface facing each other, the first rear side end surface Is provided between the first front end face and the second front end face, and when the first intermediate member is not pushed out, the first sub part freely rotates with respect to the main part. When the first interposed member is pushed out, the rotation of the first sub-portion by the second cam is performed via the first interposed member to open the intake valve or the exhaust valve. Transmitted to the main portion, the third cam has a shape that does not protrude outward from the shape of the second cam, the motion transmission member has a second sub-portion rotated by the third cam, The main part and the second sub part are at least parallel to each other. Adjacent to each other in the direction, the main portion has a third protruding portion that protrudes in the direction of the rotation axis toward the second sub-portion, and the sub-portion has the rotation axis toward the main portion. A third projecting portion projecting in a direction, and the third projecting portion includes a third front end surface and a third rear end surface in the direction of rotation of the main portion to open the intake valve or the exhaust valve. The fourth projecting portion has a fourth front end surface and a fourth rear end surface in the direction of rotation of the second sub-portion to the intake valve or exhaust valve opening, and the third rear portion A side end surface and the fourth front side end surface are opposed to each other, and a second interposed member that can be pushed out between the third rear side end surface and the fourth front side end surface is provided, and the second intermediate member is extruded. When there is not, the second sub-portion rotates freely with respect to the main portion, and when the second interposition member is pushed out, The rotating operation of the second sub-portion by the third cam is transmitted to the main portion via the second interposition member to open the intake valve or the exhaust valve, and the third front side The end surface is separated from the fourth rear side end surface, and when the first interposed member and the second interposed member are both pushed out, the rotating operation of the first sub member by the second cam is the second It is characterized by not being transmitted to the sub member.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a side view showing an embodiment of a variable valve mechanism for an internal combustion engine according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is an exploded perspective view thereof. In these drawings, 1 is an intake valve or an exhaust valve (hereinafter referred to as a valve), and 1a is a valve spring that urges the valve 1 in the valve closing direction (omitted in FIGS. 2 and 3). ). 2 is a camshaft, and 31 is a first cam disposed on the camshaft 2. A second cam 32 and a third cam 33 are disposed on the camshaft 2 on both sides of the first cam 31.
[0011]
Reference numeral 4 denotes an operation transmitting member such as a rocker arm and a swing arm that transmits the operation of each of the cams 31 to 33 to the valve. The motion transmitting member 4 has a main part 41, a first sub part 42, and a second sub part 43 that rotate about a common rotation axis 5. The first sub-portion 42 and the second sub-portion 43 are adjacent to the main portion 41 on both sides along the rotation axis direction of the rotation shaft 5. The main portion 41, the first sub portion 42, and the second sub portion 43 have rollers R for contacting the first cam 31, the second cam 32, and the third cam 33, respectively. The main portion 42 is provided with a pressing arm 41 a that simultaneously contacts the two valves 1.
[0012]
As shown in FIG. 3, the main portion 41 has a first protruding portion 41 b that protrudes in the rotation axis direction toward the first sub portion 42, and the first sub portion 42 rotates toward the main portion 41. It has the 2nd protrusion part 42b which protrudes in a dynamic-axis line direction. FIG. 4 is a cross-sectional view perpendicular to the rotation axis and passing through the first protrusion 41b and the second protrusion 42b. As shown in FIG. 4, the first projecting portion 41 b includes the first front end face 41 c and the first rear side in the rotation direction (indicated by arrows in FIGS. 3 and 4) of the main portion 41 to the valve 1 opening. The second protrusion 42b has a second front end face 42c and a second rear end face 42d in the direction of rotation of the first sub-part 42 toward the valve opening of the valve 1, The front end face 41c and the second rear end face 42d face each other, and the first rear end face 41d and the second front end face 42c face each other.
[0013]
A first interposition member 44 such as a pin is provided between the first rear end face 41d and the second front end face 42c. As shown in FIG. 5, which is a cross-sectional view taken along the line AA of FIG. 4, the first interposition member 44 is moved by the spring 45 from between the first rear end face 41 d and the second front end face 42 c into the first sub part 42. It is energized to retract. On the other hand, when hydraulic pressure acts in the pressure chamber 46 in the first sub-portion 42, the first intervention member 44 causes the first intervention by the pushing force generated by the difference between the pressure receiving area on the pushing side and the pressure receiving area on the retracting side. The member 44 is pushed against the spring 45 between the first rear end face 41d and the second front end face 42c.
[0014]
As described above, the main portion 41 of the motion transmitting member 4 has the pressing arm 41a that comes into contact with the valve 1. Therefore, the main portion 41 is urged by the valve spring 1a in the rotation direction of the valve 1 toward the valve closing. ing. On the other hand, the first sub-portion 42 and the second sub-portion 43 are also urged by the springs 47 and 48, respectively, in the direction of rotation of the valve 1 toward the valve closing.
[0015]
The first protrusion 41 b of the main portion 41 and the second protrusion 42 b of the first sub-portion 42 are formed by the first cam 31 and the second cam 32 by the above-described biasing by the valve spring 1 a and the spring 47. When the first sub-portion 42 is not actuated, as shown in FIG. 4, the first interposed member is interposed between the first rear end face 41d of the first protrusion 41b and the second front end face 42c of the second protrusion 42b. The first front end face 41c of the first protrusion 41b and the second rear end face 42d of the second protrusion 42b are formed so as to contact each other.
[0016]
As shown in FIG. 1, the first cam 31 is a low lift cam, the second cam 32 is a high lift cam, and the cam shape of the first cam 31 does not protrude outward from the cam shape of the second cam 32. When no hydraulic pressure is applied to the hydraulic chamber 46 in the first sub-part 42, the first interposition member 44 is retracted into the first sub-part 42 by the spring 45. Thereby, in the valve closing direction of the valve 1, the first sub-part 42 is largely rotated by the second cam 32 compared to the main part 41 rotated by the first cam 31, but the first protrusion Due to the gap between the first rear end face 41d of the portion 41b and the second front end face 42c of the second projecting portion 42b, the first sub-part 42 freely rotates with respect to the main part 41, and the first sub-end 42b The operation of the portion 42 is not transmitted to the main portion 41, and the valve 1 is opened with a low lift by the rotation of the main portion 41 by the first cam 31.
[0017]
On the other hand, when hydraulic pressure is acting on the hydraulic chamber 46 in the first sub-portion 42, the gap between the first rear end face 41d of the first protrusion 41b and the second front end face 42c of the second protrusion 42b. The first interposing member 44 is pushed out, and the rotation of the first sub-portion by the second cam 32 is transmitted to the main portion 41 via the first interposing member 44. Accordingly, the peak portion of the first cam 31 is not in contact with the main portion 41, and the valve 1 is opened by the second cam 32 with a high lift. At this time, the first interposed member 44 is compressed by the first rear end face 41d of the first protrusion 41b and the second front end face 42c of the second protrusion 42b. Compared to shearing and bending, it is more resistant to compression, and even if the first intervening member 44 is not made too large, the first intervening member 44 will not be damaged.
[0018]
In the present embodiment, the first rear end face 41d of the first protrusion 41b and the second front end face 42c of the second protrusion 42b are each provided with a first circular cross section in order to prevent stress concentration during compression. A recess is provided so as to make surface contact with the member 44.
[0019]
Thus, when the valve 1 is opened with a high lift via the first sub-portion 42, the general variable valve mechanism has the first front end face 41 c and the first front end surface 41 c of the first protrusion 41 b of the main portion 41. Since there is a relatively large gap between the second projecting portion 42b of the sub-part 42 and the second rear end face 42d, the main part 41 can be connected to the first projecting part 41b by the surging of the valve spring 1a. The first rear end surface 41d rotates abnormally so as to be separated from the first interposition member 44, whereby the valve 1 is abnormally pushed down and is damaged when the valve is closed, or the first protruding portion of the main portion 41 is caused by reaction. There is a possibility that the first rear side end face 41d of 41b collides violently with the first interposition member 44, and the first protrusion 41b and the first interposition member 44 are damaged.
[0020]
However, in this embodiment, when the valve 1 is opened with a high lift via the first sub-portion 42, the first front end face 41c and the first sub-portion 42 of the first protrusion 41b of the main portion 41 are opened. The second rear end face 42d of the second protrusion 42b is in contact with each other, and such an abnormal rotation of the main portion 41 does not occur, and the first protrusion 41b and the first interposed member 44 are damaged. Can be prevented. Of course, the gap between the first front end face 41c of the first protrusion 41b of the main portion 41 and the second rear end face 42d of the second protrusion 42b of the first sub-part 42 is a general variable valve mechanism. In contrast, if the amount is small, abnormal rotation of the main portion 41 such that the valve 1 is abnormally pushed down can be prevented.
[0021]
In the present embodiment, the second sub portion 43 has the same configuration as the first sub portion 42 as shown in FIGS. 3 and 5. As shown in FIG. 6, the main portion 41 has a third protrusion 41 e that protrudes in the rotational axis direction toward the second sub portion 43, and the second sub portion 43 rotates toward the main portion 41. It has the 4th protrusion part 43b which protrudes in a dynamic-axis line direction. FIG. 6 is a cross-sectional view perpendicular to the rotation axis and passing through the third protrusion 41e and the fourth protrusion 43b. As shown in FIG. 6, the third projecting portion 41 e includes the third front end face 41 f and the third rear side in the rotation direction (indicated by arrows in FIGS. 3 and 6) of the main portion 41 to the valve 1 opening. The fourth protrusion 43b has a fourth front end face 43c and a fourth rear end face 43d in the direction of rotation of the second sub-part 43 to the valve 1 opening, The front end face 41f and the fourth rear end face 43d face each other, and the third rear end face 41g and the fourth front end face 43c face each other.
[0022]
Between the third rear side end face 41g and the fourth front side end face 43c, a second interposed member 44 'similar to that described above is provided. As shown in FIG. 5, the second interposed member 44 ′ is biased by the spring 45 ′ so as to be retracted into the second sub-portion 43 from between the third rear side end surface 41 g and the fourth front side end surface 43 c. . On the other hand, when the hydraulic pressure is applied to the pressure chamber 46 ′ in the second sub-portion 43, the second interposition member 44 ′ is opposed to the spring 45 ′ and the third rear end face 41e and the fourth front end face 43c as described above. It is pushed out between.
[0023]
The third protrusion 41e of the main portion 41 and the fourth protrusion 43b of the second sub-part 43 have the first cam 31 and the third cam 33 formed by the main portion 41 and the biasing by the valve spring 1a and the spring 48, respectively. When the second sub-portion 43 is not actuated, as shown in FIG. 6, the second interposition member is provided between the third rear end face 41g of the third protrusion 41e and the fourth front end face 43c of the fourth protrusion 43b. A gap that allows the extrusion of 44 'is provided, and the third front end face 41f of the third protrusion 41e and the fourth rear end face 43d of the fourth protrusion 43b are formed to be separated from each other.
[0024]
As shown in FIG. 1, the third cam 33 that contacts the second sub-portion 43 is an intermediate lift cam, and the cam shape of the first cam 31 does not protrude outward from the cam shape of the third cam 33. Further, the cam shape of the third cam 33 does not protrude outward from the cam shape of the second cam 32. When no hydraulic pressure is acting on the hydraulic chamber 46 ′ in the second sub part 43, the second interposition member 44 ′ is retracted into the second sub part 43 by the spring 45 ′. As a result, the second sub-part 43 rotates freely with respect to the main part 41 by the gap between the third rear end face 41g of the third protrusion 41e and the fourth front end face 43c of the fourth protrusion 43b. The movement of the second sub-portion 42 is not transmitted to the main portion 41. On the other hand, when hydraulic pressure is acting on the hydraulic chamber 46 ′ in the second sub-portion 43, it is between the third rear end face 41 g of the third protrusion 41 e and the fourth front end face 43 c of the fourth protrusion 43 b. The second interposed member 44 ′ is pushed out into the gap, and the rotation of the first sub part by the third cam 33 is transmitted to the main part 41 via the second interposed member 44 ′. Thereby, the peak portion of the first cam 31 is not in contact with the main portion 41, and the valve 1 is opened by the third cam 33 with a middle lift.
[0025]
Thus, if the first interposition member 44 is pushed out, the valve 1 can be opened with a high lift by the second cam 32 via the first subportion 42, and the first interposition member 44 is retracted and the second interposition member is retracted. If 44 'is pushed out, the valve 1 can be opened by the third cam 33 through the second sub-portion 43 with a medium lift. In the present embodiment, since the cam shape of the third cam 33 does not protrude outwardly from the cam shape of the second cam 32, the second cam 33, even if the two interposing members 44, 44 ′ are pushed out, The cam 32 can open the valve 1 with a high lift.
[0026]
In such a case, when the first sub-portion 42 and the main portion 41 are operated by the second cam 32, the third front end face 41f of the third protrusion 41e of the main portion 41 and the fourth of the second sub-portion 43 are used. Since a relatively large gap exists between the projecting portion 43b and the fourth rear end face 43d, the operation of the first sub-portion 42 is not transmitted to the second sub-portion 43 via the main portion 41, and the second sub-end portion 43 is not transmitted. The sub-part 43 is actuated only by the third cam 33.
[0027]
If the operation of the first sub-portion 42 is transmitted to the second sub-portion 43, the second cam 32 rotates the second sub-portion 43 in addition to the first sub-portion 42 and the main portion 41. Thus, the required torque of the camshaft 2 is increased because the weight of the movable part is increased.
[0028]
Further, if the second sub-portion 43 is rotated by the second cam 32 which is a high lift cam, the spring 48 for returning the second sub-portion 43 is the same as the spring 47 for returning the first sub-portion 42. This is because when the valve 1 is opened with a middle lift by the third cam 33, the rotational resistance of the second sub-part 43 is increased and the required torque of the camshaft 2 is increased. Let
[0029]
Of course, by retracting the second interposition member 44 ′ and pushing out the first interposition member 44, the third front end face 41 f of the third protrusion 41 e of the main portion 41 and the fourth protrusion 43 b of the second sub portion 43 Even if the second rear end face 43d is in contact, the second sub-portion 43 is prevented from rotating together with the first sub-portion 42, but in such control, the valve lift is changed from the middle lift. It will shift to a high lift via a low lift and is not suitable for actual engine operation. Therefore, in order to shift the valve lift from the middle lift to the high lift without going through the low lift, there is always a period in which the first interposed member 44 and the second interposed member 44 ′ are pushed out at the same time. To cause a problem, when the first sub-portion 43 and the main portion 41 are actuated by the second cam 32, as in the present embodiment, the third front end face 41f in the third protrusion 41e of the main portion 41 and Providing a relatively large gap between the fourth protrusion 43b of the second sub-part 43 and the fourth rear end face 43d is effective for solving the problem of the increase in the required torque of the camshaft 2 described above.
[0030]
On the other hand, as described in the high lift operation of the valve 1, during the middle lift operation by the third cam 33, the third rear end face 41g of the third protrusion 41e is separated from the second interposed member 44 ′. It will be possible to turn. However, the surging of the valve spring 1a that causes this occurs mainly at the time of high engine rotation, and hardly occurs at the time of medium rotation of the engine in which the valve 1 is opened with a medium lift.
[0031]
As described above, the first sub-portion 42 and the second sub-portion 43 are provided on both sides of the main portion 41, and the shape of the third cam 33 that operates the second sub-portion 43 is the first one that operates the first sub-portion 42. In the case where it is housed inside the shape of the two cams 32, the third front side of the third protruding portion 41e of the main portion 41 is assumed assuming that both the first interposed member 44 and the second interposed member 44 ′ are pushed out. Rather than bringing the end face 41f into contact with the fourth rear end face 43d of the fourth protrusion 43b of the second sub-part 43, it is advantageous to provide a relatively large gap therebetween. In this case, as shown in FIG. 7 corresponding to FIG. 4, the second rear end face 42 d of the second protrusion 42 b of the first sub-portion 41 and the first protrusion 41 b of the main portion 41 are first. Even if the front end surface 41c is separated without being brought into contact therewith, the above-described problem of an increase in required torque of the camshaft 2 can be solved.
[0032]
The two passages 5a and 5b formed in the rotation shaft 5 of the motion transmitting member 4 supply hydraulic pressure to the hydraulic chamber 46 of the first sub part 42 and the hydraulic chamber (not shown) of the second sub part 43, respectively. It is a passage for supplying.
[0033]
In the present embodiment, the first cam 31 that contacts the main portion 41 of the motion transmitting member 4 is a low lift cam, and the second cam 32 that contacts the first sub portion 42 is a high lift cam, but this limits the present invention. For example, when the valve 1 is an intake valve, the second cam 32 may be a cam for opening the intake valve in the exhaust stroke. In this case, if the first interposition member 44 is pushed out from the first sub-portion 42, the intake valve is opened by the first sub-portion 42 in the exhaust stroke in addition to being opened by the main portion 41 in the intake stroke. It is possible to perform exhaust gas recirculation internally by causing a part of the exhaust gas to flow back to the engine intake system. According to the present embodiment, when the intake valve is opened during this exhaust stroke, the main contact 41 is in contact with the first protrusion 41b of the main portion 41 and the second protrusion 42b of the first sub-portion 42. It is possible to prevent the portion 41 from rotating abnormally. When the second cam 32 is a high lift cam and the third cam 33 is a cam for opening the intake valve in the exhaust stroke, both the first interposed member 44 and the second interposed member 44 ′ are used. If pushed out, the intake valve is opened at a high lift in the intake stroke and opened at the exhaust stroke, and if the second interposed member 44 'is retracted, the intake valve is opened at a high lift in the intake stroke. It can only be spoken. As described above, when the intake valve performs different operations depending on the two states of the first interposed member 44 and the second interposed member 44 ′, that is, the third cam 33 protrudes from the shape of the second cam 32. In some cases, there is no point in separating the third projecting portion 41e of the main portion 41 and the fourth projecting portion 42b of the second sub-part 43 as described above, and only the second interposing member 44 'is pushed out. In order to prevent the main portion 41 from rotating abnormally when the intake valve is opened with a low lift in the intake stroke (by the first cam 31) and opened in the exhaust stroke (by the third cam 33), It is preferable that the third protrusion 41e of the part 41 and the fourth protrusion 42b of the second sub part 43 are brought into contact with each other. In the present embodiment, the main portion 41, the first sub portion 42, and the second sub portion 43 of the motion transmitting member 4 rotate around a common rotation axis, but this limits the present invention. Instead, each part may be rotated at least about different rotation axes parallel to each other.
[0034]
【The invention's effect】
As described above, the variable valve mechanism for an internal combustion engine according to the present invention includes the first cam and the second cam, and the operation transmission member, and the operation transmission member is rotated by the first cam to be an intake valve or A main portion that contacts the exhaust valve, and a sub-portion rotated by the second cam, wherein the main portion and the sub-portion are adjacent to each other at least in the respective rotation axis directions, and the main portion is The first projecting portion projecting in the rotation axis direction toward the sub-portion, the sub-portion having the second projecting portion projecting in the rotation axis direction toward the main portion, The main part has a first front end face and a first rear end face in the direction of rotation to open the intake valve or exhaust valve, and the second projecting part opens the sub part intake valve or exhaust valve. Having a second front end face and a second rear end face, and the first front end face and the second rear end face are opposed to each other. The first rear side end surface and the second front side end surface are opposed to each other, and an interposition member that can be pushed out between the first rear side end surface and the second front side end surface is provided, and when the interposition member is not extruded, The sub-portion rotates freely with respect to the main portion, and when the interposition member is pushed out, the sub-portion operation by the second cam is performed via the interposition member to open the intake valve or the exhaust valve. The first front side end surface is substantially in contact with the second rear side end surface. Thereby, when the rotation of the sub-portion is transmitted to the main portion via the interposition member, the main portion so that the first rear end face of the first protrusion is separated from the interposition member by surging of the valve spring or the like. Even if an attempt is made to rotate abnormally, this rotation is prevented because the first front end face of the first protrusion is substantially in contact with the second rear end face of the second protrusion. In this way, it is possible to prevent the intake valve from being abnormally pushed down and damaged when the valve is closed, or the first projecting portion of the main portion violently collides with the interposition member due to the reaction, and the main portion and the interposition member are prevented from being damaged.
[0035]
Further, another variable valve mechanism for an internal combustion engine according to the present invention includes a first cam, a second cam, a third cam, and a motion transmission member, and the motion transmission member is rotated by the first cam. A main portion that is in contact with the intake or exhaust valve and a first sub-portion rotated by the second cam, and the main portion and the first sub-portion are at least parallel to each other in the rotation axis direction Adjacent to each other, the main part has a first protrusion protruding in the direction of the rotation axis toward the first sub part, and the first sub part protrudes in the direction of the rotation axis toward the main part. The first protrusion has a first front end face and a first rear end face in the rotation direction to the intake valve or exhaust valve opening of the main part, and the second protrusion is , Having a second front end face and a second rear end face in the rotation direction to the opening of the intake valve or exhaust valve of the first sub part, The side end face and the second front end face are opposed to each other, and a first interposition member that can be pushed out between the first rear end face and the second front end face is provided, and when the first interposition member is not extruded, The first subportion freely rotates with respect to the main portion, and when the first interposition member is pushed out, the first subportion is rotated by the second cam to open the intake valve or the exhaust valve. The third cam has a shape that does not protrude outward from the shape of the second cam, and the motion transmitting member is a second sub-portion that is rotated by the third cam. And a main part and a second sub part are adjacent to each other at least in the respective rotation axis directions parallel to each other, and the main part protrudes in the rotation axis direction toward the second sub part. And the sub part has a fourth projecting part projecting in the direction of the rotational axis toward the main part. The third protrusion has a third front end face and a third rear end face in the direction of rotation of the main part to the intake valve or the exhaust valve, and the fourth protrusion is an intake air of the second sub part. A fourth front end face and a fourth rear end face in the direction of rotation of the valve or the exhaust valve to open, the third rear end face and the fourth front end face face each other, and the third rear end face A second interposition member that can be extruded between the fourth front end face is provided, and when the second interposition member is not extruded, the second sub-portion rotates freely with respect to the main portion, and the second interposition member When the is pushed out, the rotation of the second sub-portion by the third cam is transmitted to the main portion via the second intervening member to open the intake valve or the exhaust valve, and the third front side The end face is separated from the fourth rear end face, and when both the first interposed member and the second interposed member are pushed out, the second cam The rotation operation of the one sub member is not transmitted to the second sub member. Thereby, when both the first interposition member and the second interposition member are pushed out, the second cam does not rotate the second sub member in addition to the first sub member and the main member, and the movable portion It is possible to prevent an increase in the required torque of the camshaft due to an increase in weight.
[Brief description of the drawings]
FIG. 1 is a side view showing an embodiment of a variable valve mechanism for an internal combustion engine according to the present invention.
FIG. 2 is a plan view of the variable valve mechanism of FIG.
3 is an exploded perspective view of the variable valve mechanism in FIG. 1. FIG.
FIG. 4 is a cross-sectional view passing through a first protrusion of a main part of a motion transmitting member and a second protrusion of a first sub part perpendicular to a rotation axis.
5 is a cross-sectional view taken along the line AA in FIG.
FIG. 6 is a cross-sectional view passing through a third projecting portion of the main portion of the motion transmitting member and a fourth projecting portion of the second sub-portion perpendicular to the rotation axis.
7 is a cross-sectional view passing through a first protrusion and a second protrusion having a shape different from that of FIG. 4 perpendicular to a rotation axis. FIG.
[Explanation of symbols]
1 ... Valve
4 ... Motion transmission member
31 ... First cam
32 ... Second cam
33 ... Third cam
41 ... main part
41b ... 1st protrusion part
41c ... 1st front side end surface
41d ... first rear side end face
41e ... third protrusion
41f ... Third front side end face
41g ... Third rear end face
42. First subpart
42b ... second protrusion
42c ... second front side end face
42d ... second rear side end face
43 ... Second subpart
43b ... 4th protrusion part
43c ... Fourth front end face
43d ... fourth rear end face
44 ... first interposition member
44 '... second interposition member

Claims

A first cam and a second cam; and a motion transmission member, the motion transmission member being rotated by the first cam and contacting a suction valve or an exhaust valve; and the second cam The main portion and the sub-portion are adjacent to each other in the respective rotation axis directions parallel to each other, and the main portion moves toward the sub-portion. A first projecting portion projecting in the direction, the sub-portion has a second projecting portion projecting in the rotation axis direction toward the main portion, and the first projecting portion is formed of the main portion. A first front end face and a first rear end face in a direction of rotation of the intake valve or the exhaust valve to open the valve; and the second projecting portion opens the intake valve or the exhaust valve of the sub part. Having a second front end face and a second rear end face in the direction of rotation to the first front end face and the front The second rear side end surface is opposed to each other, the first rear side end surface and the second front side end surface are opposed to each other, and can be extruded between the first rear side end surface and the second front side end surface. is provided, wherein when the intervening member is not pushed, the front Symbol subportion is free to pivot relative to the main portion, when said intermediate member is extruded, said subportion times by the second cam The dynamic operation is transmitted to the main portion via the interposition member to open the intake valve or the exhaust valve, and the first front end face is substantially in contact with the second rear end face. A variable valve mechanism for an internal combustion engine.

A first cam, a second cam, a third cam, and a motion transmission member, wherein the motion transmission member is rotated by the first cam and contacts a suction valve or an exhaust valve; A first sub-portion rotated by a second cam, wherein the main portion and the first sub-portion are adjacent to each other at least in the respective rotation axis directions parallel to each other, and the main portion is The first sub-portion has a first protrusion that protrudes in the direction of the rotation axis toward the one subportion, and the first sub-portion has a second protrusion that protrudes in the direction of the rotation axis toward the main portion. The first protrusion has a first front end face and a first rear end face in the direction of rotation of the main portion to the intake valve or exhaust valve opening, and the second protrusion is Second front end face and second rear end face in the direction of rotation of the first sub-portion to the intake valve or exhaust valve opening The first rear side end surface and the second front side end surface are opposed to each other, and a first interposed member that can be pushed out between the first rear side end surface and the second front side end surface is provided, When the first interposition member is not pushed out, the first sub part is freely rotated with respect to the main part, and when the first interposition member is pushed out, the first sub part by the second cam Is rotated to the main part via the first intervening member to open the intake valve or the exhaust valve, and the third cam does not protrude outwardly from the shape of the second cam. The motion transmission member has a second sub-portion that is rotated by the third cam, and the main portion and the second sub-portion are at least parallel to each other in their respective rotation axis directions. Adjacent to each other, the main portion is directed toward the second sub-portion A third projecting portion projecting in the movement axis direction, the sub-portion includes a fourth projecting portion projecting in the rotation axis direction toward the main portion, and the third projecting portion A third front end face and a third rear end face in the direction of rotation of the portion toward the opening of the intake valve or exhaust valve, and the fourth protrusion is the intake valve or exhaust of the second sub portion. A fourth front end face and a fourth rear end face in the direction of rotation of the valve to open the valve; the third rear end face and the fourth front end face are opposed to each other; the third rear end face; A second interposition member that can be pushed out between the fourth front end face is provided, and when the second interposition member is not extruded, the second sub-portion rotates freely with respect to the main portion; When the second interposed member is pushed out, the rotation of the second sub-portion by the third cam is caused by the intake valve or the exhaust valve. In order to open the air valve, it is transmitted to the main part via the second interposed member, and the third front end surface is separated from the fourth rear end surface, and the first interposed member and the first intermediate member are separated from each other. The variable motion of the internal combustion engine, wherein the rotation of the first sub member by the second cam is not transmitted to the second sub member when the two intervening members are pushed out. Valve mechanism.