JP4017488B2 - Camshaft bearing structure of overhead camshaft internal combustion engine - Google Patents

Camshaft bearing structure of overhead camshaft internal combustion engine Download PDF

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Publication number
JP4017488B2
JP4017488B2 JP2002287251A JP2002287251A JP4017488B2 JP 4017488 B2 JP4017488 B2 JP 4017488B2 JP 2002287251 A JP2002287251 A JP 2002287251A JP 2002287251 A JP2002287251 A JP 2002287251A JP 4017488 B2 JP4017488 B2 JP 4017488B2
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Prior art keywords
camshaft
cam chain
intake
exhaust
combustion engine
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JP2002287251A
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JP2004124746A (en
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幸司 寺田
浩隆 枦
英子 塩崎
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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Priority to JP2002287251A priority Critical patent/JP4017488B2/en
Priority to DE2003617150 priority patent/DE60317150T2/en
Priority to EP03020860A priority patent/EP1403497B1/en
Publication of JP2004124746A publication Critical patent/JP2004124746A/en
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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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/022—Chain drive
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • F01L1/0532—Camshafts overhead type the cams being directly in contact with the driven valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M9/00—Lubrication means having pertinent characteristics not provided for in, or of interest apart from, groups F01M1/00 - F01M7/00
    • F01M9/10—Lubrication of valve gear or auxiliaries
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M9/00—Lubrication means having pertinent characteristics not provided for in, or of interest apart from, groups F01M1/00 - F01M7/00
    • F01M9/10—Lubrication of valve gear or auxiliaries
    • F01M9/102—Lubrication of valve gear or auxiliaries of camshaft bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F1/26—Cylinder heads having cooling means
    • F02F1/36—Cylinder heads having cooling means for liquid cooling
    • F02F1/38—Cylinder heads having cooling means for liquid cooling the cylinder heads being of overhead valve type
    • 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
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • F01L2001/0537—Double overhead camshafts [DOHC]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/06—Lubricating systems characterised by the provision therein of crankshafts or connecting rods with lubricant passageways, e.g. bores
    • F01M2001/064—Camshaft with passageways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
    • F02B2275/18—DOHC [Double overhead camshaft]

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、頭上カム軸（ＯＨＣ：OverHead Camshaft）式内燃機関のカム軸の軸受構造に関する。
【０００２】
【従来の技術】
シリンダヘッドの被カバー面に吸気用カム軸と排気用カム軸とが互いに平行に並べられ各ジャーナル部を軸支されて配設されヘッドカバーで覆われた多気筒の頭上カム軸式内燃機関であって、吸気用カム軸と排気用カム軸にカムチェーンスプロケットを備えたカムチェーンタイプの内燃機関が一般に採用されている（例えば、特許文献１参照）。
【０００３】
【特許文献１】
特許２７４４７８１号公報
【０００４】
【発明が解決しようとする課題】
特許文献１に開示された動弁系のカム軸の軸受構造は、詳細には明らかでないが、カム軸の軸受部からカムチェーンスプロケットまである程度距離が存在すると、カムチェーンスプロケットに巻き掛けられるカムチェーンによる張力がカム軸に曲げ力として作用するとカム軸の剛性を確保することが難しく、打音が発生する要因ともなる。
【０００５】
本発明は、斯かる点に鑑みなされたもので、その目的とする処は、カム軸の剛性を容易に確保することができ打音の発生を防止することができる頭上カム軸式内燃機関のカム軸軸受構造を供する点にある。
【０００８】
【課題を解決するための手段及び作用効果】
上記目的を達成するために、本請求項１記載の発明は、シリンダヘッドの被カバー面に吸気用カム軸と排気用カム軸とが互いに平行に並べられ各ジャーナル部を軸支されて配設されヘッドカバーで覆われる多気筒の頭上カム軸式内燃機関において、前記吸気用カム軸と排気用カム軸のそれぞれ略中央にカムチェーンスプロケットが設けられ、前記カムチェーンスプロケットに隣接して前記シリンダヘッドの被カバー面に軸受部がそれぞれカムチェーン室に膨出するように形成され、前記各軸受部と各ブラケットにより前記吸気用カム軸と排気用カム軸の対応する各ジャーナル部が挟まれるようにして軸支され、前記各カムチェーンスプロケットに隣接して前記シリンダヘッドの被カバー面に形成される各軸受部は、前記各カムチェーンスプロケットの片側にのみ形成され、前記吸気用カム軸および排気用カム軸には内部に油通路が形成され、前記シリンダヘッドの前記カムチェーンスプロケットに隣接した軸受部に形成された導入油路から前記油通路にオイルが導入され、各カムロブおよびジャーナル部に形成された導出油路からオイルが導出され、前記ブラケットの前記カムチェーン室側に油路が形成される頭上カム軸式内燃機関のカム軸軸受構造とした。
【０００９】
吸気用カム軸と排気用カム軸をそれぞれ軸支する軸受部が各カムチェーンスプロケットに隣接して形成されるので、各カムチェーンスプロケットに巻き掛けられるカムチェーンによる張力が吸気用カム軸と排気用カム軸に曲げ力として作用しても吸気用カム軸と排気用カム軸の剛性を容易に確保することができる。
【００１１】
軸受部が、カムチェーンスプロケットの片側にのみ形成されても、軸受部とカムチェーンスプロケットとは隣接しているので、カム軸の剛性を十分に確保することができる。
各カムがそれぞれ吸気バルブおよび排気バルブを直動する構造を利用してカム軸内に油通路を形成し、カムチェーンスプロケットに隣接した軸受部からオイルを導入し、各カムロブおよびジャーナル部から導出することで、潤滑油経路を簡略化することができる。
【００１２】
請求項２記載の発明は、請求項１記載の頭上カム軸式内燃機関カム軸の軸受構造において、前記吸気用カム軸および排気用カム軸は、その各カムがそれぞれ吸気バルブおよび排気バルブを直動することを特徴とする。
【００１３】
各カムがそれぞれ吸気バルブおよび排気バルブを直動するので、ロッカアームを必要とせず、部品を削減し構造を簡素化することができる。
【００１６】
【発明の実施の形態】
以下本発明に係る一実施の形態について図１ないし図４に基づき説明する。
本実施の形態に係る内燃機関１は、並列４気筒４ストロークサイクルのＤＯＨＣ（頭上２カム軸）式内燃機関であり、自動二輪車に横置きに搭載される。
【００１７】
図１は該内燃機関１の一部縦断面図であって図２のＩ−Ｉ線に沿う断面図であり、図２はシリンダヘッドカバーを外した状態の上面図である。
シリンダブロック２には４つのシリンダボア３が並列に形成されており、各シリンダボア３にピストン４が摺動自在に嵌合される。
【００１８】
シリンダブロック２に一体に重ね合わされるシリンダヘッド５には各ピストン４に対向してそれぞれ燃焼室６が形成され、各燃焼室６の天井面には一対の吸気ポート７と一対の排気ポート８が互いに並んで開口する。
【００１９】
吸気ポート７の開口を開閉する吸気バルブ９と排気ポート８の開口を開閉する排気バルブ10は、そのバルブステム９ａ，10ａがそれぞれバルブガイド11，12により摺動自在に支持され、バルブステム９ａ，10ａの上端に設けられるリテーナ13，14とシリンダヘッド５との間にバルブスプリング15，16が介装され、吸気バルブ９と排気バルブ10を閉弁方向に付勢している。
【００２０】
バルブステム９ａ，10ａの上部は有底円筒状のバルブリフタ17，18が被せられ、このバルブリフタ17，18の端面を吸気カム軸21と排気カム軸22のカムロブ23，24が直接押圧する。
すなわちカムがバルブを直接駆動する直動式である。
【００２１】
本内燃機関１はＤＯＨＣ式内燃機関であり、吸気カム軸21と排気カム軸22はシリンダヘッド５の被カバー面に互いに平行に並べられ各ジャーナル部25，26を軸支されて配設され、その上方はシリンダヘッドカバー19で覆われる。
吸気カム軸21と排気カム軸22は、略中央部にカムチェーンスプロケット27，28が嵌着されたセンタカムチェーンタイプである。
【００２２】
図４に示すように上面視長方形状をしたシリンダヘッド５は、中央部にカムチェーン室30が幅方向に長尺の矩形孔として形成されている。
このカムチェーン室30の両側に各気筒の燃焼室６が２つずつ配設され、各燃焼室６の中心に点火プラグを装着するためのプラグ孔31がそれぞれ形成されている。
【００２３】
プラグ孔31の周囲に各々一対のバルブリフタ17，18が摺動する一対のリフタ穴32，33が４つ形成されている。
そして各気筒について吸気側リフタ穴32と排気側リフタ穴33との間に半円弧面をなす軸受部34，35が設けられ、各軸受部34，35の前後にブラケットとの合せ面36，37が形成され、合せ面36，37にはそれぞれボルト穴36ａ，37ａが設けられている。
【００２４】
なお各気筒の一対の吸気側リフタ穴32，32の両側および一対の排気側リフタ穴33，33の両側には、ヘッドボルト用のボス部38，39が形成されている。
【００２５】
そして本シリンダヘッド５には、前記軸受部34，35のほかにボス部38，39よりもさらにカムチェーン室30に幾らか膨出するようにして半円弧面をなす軸受部41，42がそれぞれ前記軸受部34，35と同軸に形成されている。
【００２６】
各軸受部41，42の前後にブラケットとの合せ面43，44が形成され、合せ面43，44にはそれぞれボルト穴43ａ，44ａが設けられる。
なお合せ面43，44には導入油路43ｂ，44ｂの開口が形成されている。
【００２７】
以上のようなシリンダヘッド５の被カバー面において、吸気カム軸21と排気カム軸22がカムチェーンスプロケット27，28をカムチェーン室30に嵌挿して各軸受部34，35および軸受部41，42にジャーナル部25，26を支持させ、各軸受部に対応する半円弧面を備えるブラケット45，46およびブラケット51，52がジャーナル部25，26を挟んで吸気カム軸21と排気カム軸22を回動自在に軸支する（図２および図３参照）。
【００２８】
なおブラケット45，46およびブラケット51，52はボルト53により固着される。吸気カム軸21と排気カム軸22のカムロブ23，24はリフタ穴32，33に摺動自在に嵌合したバルブリフタ17，18の端面に当接する。
【００２９】
カムチェーン室30に嵌挿されたカムチェーンスプロケット27，28にはクランク軸に嵌着された駆動スプロケットとの間に無端状のカムチェーン55が巻き掛けられて架設される。
【００３０】
内燃機関１の運転によりクランク軸の回転がカムチェーン55を介して２分の１回転の割合で吸気カム軸21と排気カム軸22に伝達され、この吸気カム軸21と排気カム軸22の回転によりカムロブ23，24がバルブリフタ17，18を介して吸気バルブ９、排気バルブ10を開閉弁駆動することができる。
【００３１】
本シリンダヘッド５の場合、カムチェーン室30に幾らか膨出するようにして軸受部41，42が形成されているので、カムチェーン室30に嵌挿されるカムチェーンスプロケット27，28に軸受部41，42が極めて接近して隣接した状態にある。
【００３２】
したがって各カムチェーンスプロケット27，28に巻き掛けられるカムチェーン55による張力が吸気用カム軸21と排気用カム軸22に曲げ力として作用しても吸気用カム軸21と排気用カム軸22の剛性を容易に確保することができる。
よってカム軸の歪みによる打音の発生を防止することができる。
【００３３】
軸受部41，42が、カムチェーンスプロケット27，28の片側にのみあるが、軸受部41，42とカムチェーンスプロケット27，28とは隣接しているので、吸気用カム軸21と排気用カム軸22の剛性を十分に確保することができる。
【００３４】
バルブリフタ17，18の端面を吸気カム軸21と排気カム軸22のカムロブ23，24が直接押圧する直動式なので、図３に示すように吸気カム軸21（および排気カム軸22）内に両端を閉塞した油通路21ａ(22ａ)を形成した簡単な潤滑油経路を構成することができる。
【００３５】
すなわち図３を参照してカムチェーンスプロケット27に隣接した軸受部41の合せ面43に開口した導入油路43ｂからブラケット51に形成された油路51ａ（図２参照）を通り対応するジャーナル部の導入油路21ｂを介してオイルを吸気カム軸21の油通路21ａに導入し、各カムロブ23に形成された導出油路23ａおよびジャーナル部25に形成された導出油路25ａからオイルを導出してカム外周面および軸受にオイルを供給して潤滑する。
【００３６】
吸気カム軸21の略中央に位置する軸受部41の導入油路43ｂから吸気カム軸21の油通路21ａにオイルが導入されるので、左右両側に均等にオイルが供給される。
なお排気側の動弁系の潤滑も同様の構造のものである。
【００３７】
以上の実施の形態では、ＤＯＨＣ式内燃機関に適用したがＳＯＨＣ（頭上１カム軸）式内燃機関にも適用でき、また多気筒に限らず単気筒内燃機関にも適用できる。
【００３８】
また多気筒内燃機関で、カムチェーンスプロケットがカム軸の中央に位置するセンタカムチェーンタイプに限らず、カム軸の端部にカムチェーンスプロケットがあるサイドカムチェーンタイプにも適用できる。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る内燃機関の一部縦断面図である。
【図２】同内燃機関のシリンダヘッドカバーを外した状態の上面図である。
【図３】図２のIII−III線に沿った断面図である。
【図４】シリンダヘッドの上面図である。
【符号の説明】
１…内燃機関、２…シリンダブロック、３…シリンダボア、４…ピストン、５…シリンダヘッド、６…燃焼室、７…吸気ポート、８…排気ポート、９…吸気バルブ、10…排気バルブ、11，12…バルブガイド、13，14…リテーナ、15，16…バルブスプリング、17，18…バルブリフタ、19…シリンダヘッドカバー、
21…吸気カム軸、21ａ…油通路、22…排気カム軸、23，24…カムロブ、23ａ…導出油路、25，26…ジャーナル部、25ａ…導出油路、27，28…カムチェーンスプロケット、30…カムチェーン室、31…プラグ孔、32，33…リフタ穴、34，35…軸受部、36，37…合せ面、38，39…ボス部、41，42…軸受部、43，44…合せ面、43ｂ，44ｂ…導入油路、45，46,51，52…ブラケット、53…ボルト、55…カムチェーン。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bearing structure of a cam shaft of an overhead camshaft (OHC) type internal combustion engine.
[0002]
[Prior art]
This is a multi-cylinder overhead camshaft type internal combustion engine in which an intake camshaft and an exhaust camshaft are arranged in parallel to each other on a covered surface of a cylinder head and supported by journal heads and covered with a head cover. In general, a cam chain type internal combustion engine in which a cam chain sprocket is provided on an intake cam shaft and an exhaust cam shaft is employed (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent No. 2744781 [0004]
[Problems to be solved by the invention]
Although the bearing structure of the camshaft of the valve train disclosed in Patent Document 1 is not clear in detail, the cam chain wound around the cam chain sprocket when there is a certain distance from the bearing portion of the cam shaft to the cam chain sprocket When the tension due to acts as a bending force on the camshaft, it is difficult to ensure the rigidity of the camshaft, which causes a hitting sound.
[0005]
The present invention has been made in view of such a point, and the object of the present invention is an overhead camshaft internal combustion engine that can easily ensure the rigidity of the camshaft and prevent the occurrence of a hitting sound. The camshaft bearing structure is provided.
[0008]
[Means for solving the problems and effects]
To achieve the above object, according to the first aspect of the present invention, an intake camshaft and an exhaust camshaft are arranged in parallel to each other on a covered surface of a cylinder head, and each journal portion is pivotally supported. In a multi-cylinder overhead camshaft internal combustion engine covered with a head cover, a cam chain sprocket is provided at substantially the center of each of the intake cam shaft and the exhaust cam shaft, and the cylinder head is adjacent to the cam chain sprocket. A bearing portion is formed on the covered surface so as to bulge into the cam chain chamber, and the corresponding journal portions of the intake cam shaft and the exhaust cam shaft are sandwiched between the bearing portions and the brackets. Each bearing portion, which is pivotally supported and formed on the covered surface of the cylinder head adjacent to each cam chain sprocket, is connected to each cam chain sprocket. The intake camshaft and the exhaust camshaft are formed with oil passages in the intake camshaft and the exhaust camshaft. The oil passage is formed in a bearing portion adjacent to the cam chain sprocket of the cylinder head. A cam of an overhead camshaft internal combustion engine in which oil is introduced into the oil passage, oil is led out from a lead-out oil passage formed in each cam lobe and journal portion, and an oil passage is formed on the cam chain chamber side of the bracket A shaft bearing structure was adopted.
[0009]
Since the bearings that support the intake camshaft and the exhaust camshaft are formed adjacent to each cam chain sprocket, the tension of the cam chain wound around each cam chain sprocket causes the intake camshaft and the exhaust camshaft to Even if the camshaft acts as a bending force, the rigidity of the intake camshaft and the exhaust camshaft can be easily secured.
[0011]
Even if the bearing portion is formed only on one side of the cam chain sprocket, the bearing portion and the cam chain sprocket are adjacent to each other, so that the rigidity of the cam shaft can be sufficiently secured.
An oil passage is formed in the camshaft using a structure in which each cam directly moves an intake valve and an exhaust valve, oil is introduced from a bearing portion adjacent to the cam chain sprocket, and is led out from each cam lobe and journal portion. As a result, the lubricating oil path can be simplified.
[0012]
According to a second aspect of the invention, straight in the bearing structure of the overhead camshaft type internal combustion engine camshaft according to claim 1, wherein the cam shaft and an exhaust cam shaft for intake, the respective cam an intake valve and an exhaust valve It is characterized by moving.
[0013]
Since each cam directly moves the intake valve and the exhaust valve, a rocker arm is not required, parts can be reduced, and the structure can be simplified.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
The internal combustion engine 1 according to the present embodiment is a parallel 4-cylinder 4-stroke cycle DOHC (overhead 2 camshaft) internal combustion engine, and is mounted horizontally on a motorcycle.
[0017]
FIG. 1 is a partial longitudinal sectional view of the internal combustion engine 1 and is a sectional view taken along the line II of FIG. 2, and FIG. 2 is a top view of a state in which a cylinder head cover is removed.
Four cylinder bores 3 are formed in the cylinder block 2 in parallel, and a piston 4 is slidably fitted to each cylinder bore 3.
[0018]
Combustion chambers 6 are formed in the cylinder head 5 that is integrally overlapped with the cylinder block 2 so as to face the pistons 4. A pair of intake ports 7 and a pair of exhaust ports 8 are formed on the ceiling surface of each combustion chamber 6. Open side by side.
[0019]
An intake valve 9 that opens and closes the opening of the intake port 7 and an exhaust valve 10 that opens and closes the opening of the exhaust port 8 have valve stems 9a and 10a slidably supported by valve guides 11 and 12, respectively. Valve springs 15 and 16 are interposed between retainers 13 and 14 provided at the upper end of 10a and the cylinder head 5 to urge the intake valve 9 and the exhaust valve 10 in the valve closing direction.
[0020]
The upper portions of the valve stems 9a and 10a are covered with bottomed cylindrical valve lifters 17 and 18, and the end faces of the valve lifters 17 and 18 are directly pressed by the intake camshaft 21 and the cam lobes 23 and 24 of the exhaust camshaft 22.
That is, it is a direct acting type in which the cam directly drives the valve.
[0021]
The internal combustion engine 1 is a DOHC internal combustion engine, and an intake cam shaft 21 and an exhaust cam shaft 22 are arranged in parallel to each other on the covered surface of the cylinder head 5 and are supported by journal portions 25 and 26, respectively. The upper part is covered with a cylinder head cover 19.
The intake camshaft 21 and the exhaust camshaft 22 are a center cam chain type in which cam chain sprockets 27 and 28 are fitted at substantially the center.
[0022]
As shown in FIG. 4, the cylinder head 5 having a rectangular shape in a top view has a cam chain chamber 30 formed at the center as a rectangular hole that is long in the width direction.
Two combustion chambers 6 for each cylinder are disposed on both sides of the cam chain chamber 30, and plug holes 31 for attaching spark plugs are formed at the centers of the respective combustion chambers 6.
[0023]
Four pair of lifter holes 32 and 33 are formed around the plug hole 31 so that the pair of valve lifters 17 and 18 slide.
Bearing portions 34 and 35 having a semicircular arc surface are provided between the intake-side lifter hole 32 and the exhaust-side lifter hole 33 for each cylinder, and mating surfaces 36 and 37 with the bracket are provided before and after each bearing portion 34 and 35. Are formed, and the mating surfaces 36 and 37 are provided with bolt holes 36a and 37a, respectively.
[0024]
Boss portions 38 and 39 for head bolts are formed on both sides of the pair of intake side lifter holes 32 and 32 and on both sides of the pair of exhaust side lifter holes 33 and 33 of each cylinder.
[0025]
In addition to the bearing portions 34 and 35, the cylinder head 5 has bearing portions 41 and 42 that form semicircular arc surfaces so as to bulge somewhat further into the cam chain chamber 30 than the boss portions 38 and 39, respectively. It is formed coaxially with the bearing portions 34 and 35.
[0026]
The mating surfaces 43 and 44 are formed on the front and rear sides of the bearing portions 41 and 42, and the mating surfaces 43 and 44 are provided with bolt holes 43a and 44a, respectively.
The mating surfaces 43 and 44 are formed with openings for introducing oil passages 43b and 44b.
[0027]
On the covered surface of the cylinder head 5 as described above, the intake camshaft 21 and the exhaust camshaft 22 are inserted into the cam chain chamber 30 by inserting the cam chain sprockets 27 and 28 into the respective bearing portions 34 and 35 and the bearing portions 41 and 42. The brackets 45 and 46 and the brackets 51 and 52 having semicircular arc surfaces corresponding to the bearings rotate the intake cam shaft 21 and the exhaust cam shaft 22 with the journal portions 25 and 26 interposed therebetween. It is pivotally supported (see FIGS. 2 and 3).
[0028]
The brackets 45 and 46 and the brackets 51 and 52 are fixed by bolts 53. The cam lobes 23 and 24 of the intake camshaft 21 and the exhaust camshaft 22 are in contact with the end surfaces of the valve lifters 17 and 18 slidably fitted in the lifter holes 32 and 33.
[0029]
An endless cam chain 55 is wound around the cam chain sprockets 27 and 28 fitted in the cam chain chamber 30 between the drive sprocket fitted on the crankshaft.
[0030]
When the internal combustion engine 1 is operated, the rotation of the crankshaft is transmitted to the intake camshaft 21 and the exhaust camshaft 22 through the cam chain 55 at a rate of a half rotation, and the rotation of the intake camshaft 21 and the exhaust camshaft 22 is transmitted. Thus, the cam lobes 23 and 24 can drive the intake valve 9 and the exhaust valve 10 via the valve lifters 17 and 18, respectively.
[0031]
In the case of this cylinder head 5, the bearing portions 41, 42 are formed so as to swell somewhat in the cam chain chamber 30, so that the bearing portions 41 are mounted on the cam chain sprockets 27, 28 that are inserted into the cam chain chamber 30. , 42 are in close proximity and adjacent.
[0032]
Accordingly, the rigidity of the intake camshaft 21 and the exhaust camshaft 22 is maintained even if the tension of the cam chain 55 wound around each cam chain sprocket 27, 28 acts as a bending force on the intake camshaft 21 and the exhaust camshaft 22. Can be easily secured.
Therefore, it is possible to prevent the hitting sound due to the camshaft distortion.
[0033]
The bearings 41 and 42 are only on one side of the cam chain sprockets 27 and 28. However, since the bearings 41 and 42 and the cam chain sprockets 27 and 28 are adjacent to each other, the intake camshaft 21 and the exhaust camshaft 21 A sufficient rigidity of 22 can be secured.
[0034]
Since the cam lobes 23 and 24 of the intake camshaft 21 and the exhaust camshaft 22 are directly pressed against the end surfaces of the valve lifters 17 and 18, both ends of the intake lifter camshaft 21 (and the exhaust camshaft 22) are in the intake camshaft 21 as shown in FIG. A simple lubricating oil path in which the oil passage 21a (22a) is closed can be configured.
[0035]
That is, referring to FIG. 3, the corresponding journal portion passes through an oil passage 51 a (see FIG. 2) formed in the bracket 51 from the introduction oil passage 43 b opened in the mating surface 43 of the bearing portion 41 adjacent to the cam chain sprocket 27. Oil is introduced into the oil passage 21a of the intake camshaft 21 through the introduction oil passage 21b, and the oil is led out from the lead-out oil passage 23a formed in each cam lobe 23 and the lead-out oil passage 25a formed in the journal portion 25. Lubricate by supplying oil to the cam outer surface and bearings.
[0036]
Since oil is introduced into the oil passage 21a of the intake camshaft 21 from the introduction oil passage 43b of the bearing portion 41 located substantially at the center of the intake camshaft 21, the oil is evenly supplied to both the left and right sides.
In addition, the lubrication of the valve system on the exhaust side has the same structure.
[0037]
In the above embodiment, the present invention is applied to a DOHC type internal combustion engine, but can also be applied to an SOHC (overhead one camshaft) type internal combustion engine, and can be applied not only to a multi-cylinder but also to a single cylinder internal combustion engine.
[0038]
Further, in a multi-cylinder internal combustion engine, the present invention can be applied not only to the center cam chain type in which the cam chain sprocket is located at the center of the cam shaft but also to the side cam chain type in which the cam chain sprocket is provided at the end of the cam shaft.
[Brief description of the drawings]
FIG. 1 is a partial longitudinal sectional view of an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a top view of the internal combustion engine with a cylinder head cover removed.
3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a top view of the cylinder head.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Cylinder block, 3 ... Cylinder bore, 4 ... Piston, 5 ... Cylinder head, 6 ... Combustion chamber, 7 ... Intake port, 8 ... Exhaust port, 9 ... Intake valve, 10 ... Exhaust valve, 11, 12 ... Valve guide, 13, 14 ... Retainer, 15, 16 ... Valve spring, 17, 18 ... Valve lifter, 19 ... Cylinder head cover,
21 ... Intake camshaft, 21a ... Oil passage, 22 ... Exhaust camshaft, 23, 24 ... Cam lobe, 23a ... Derived oil passage, 25, 26 ... Journal section, 25a ... Derived oil passage, 27, 28 ... Cam chain sprocket, 30 ... Cam chain chamber, 31 ... Plug hole, 32,33 ... Lifter hole, 34,35 ... Bearing part, 36,37 ... Mating surface, 38,39 ... Boss part, 41,42 ... Bearing part, 43,44 ... Matching surface, 43b, 44b ... introducing oil passage, 45, 46, 51, 52 ... bracket, 53 ... bolt, 55 ... cam chain.

Claims (3)

シリンダヘッドの被カバー面に吸気用カム軸と排気用カム軸とが互いに平行に並べられ各ジャーナル部を軸支されて配設されヘッドカバーで覆われる多気筒の頭上カム軸式内燃機関において、
前記吸気用カム軸と排気用カム軸のそれぞれ略中央にカムチェーンスプロケットが設けられ、
前記カムチェーンスプロケットに隣接して前記シリンダヘッドの被カバー面に軸受部がそれぞれカムチェーン室に膨出するように形成され、
前記各軸受部と各ブラケットにより前記吸気用カム軸と排気用カム軸の対応する各ジャーナル部が挟まれるようにして軸支され、
前記各カムチェーンスプロケットに隣接して前記シリンダヘッドの被カバー面に形成される各軸受部は、前記各カムチェーンスプロケットの片側にのみ形成され、
前記吸気用カム軸および排気用カム軸には内部に油通路が形成され、
前記シリンダヘッドの前記カムチェーンスプロケットに隣接した軸受部に形成された導入油路から前記油通路にオイルが導入され、各カムロブおよびジャーナル部に形成された導出油路からオイルが導出され、
前記ブラケットの前記カムチェーン室側に油路が形成されることを特徴とする頭上カム軸式内燃機関のカム軸軸受構造。In a multi-cylinder overhead camshaft type internal combustion engine in which an intake camshaft and an exhaust camshaft are arranged in parallel to each other on a covered surface of a cylinder head and each journal portion is pivotally supported and covered with a head cover.
A cam chain sprocket is provided at approximately the center of each of the intake camshaft and the exhaust camshaft,
A bearing portion is formed on the covered surface of the cylinder head adjacent to the cam chain sprocket so as to bulge into the cam chain chamber,
The journal portions corresponding to the intake camshaft and the exhaust camshaft are pivotally supported by the bearing portions and the brackets, respectively,
Each bearing portion formed on the covered surface of the cylinder head adjacent to each cam chain sprocket is formed only on one side of each cam chain sprocket,
An oil passage is formed in the intake camshaft and the exhaust camshaft,
Oil is introduced into the oil passage from an introduction oil passage formed in a bearing portion adjacent to the cam chain sprocket of the cylinder head, and oil is led out from a discharge oil passage formed in each cam lobe and journal portion,
A camshaft bearing structure for an overhead camshaft internal combustion engine , wherein an oil passage is formed on the cam chain chamber side of the bracket . 前記吸気用カム軸および排気用カム軸は、その各カムがそれぞれ吸気バルブおよび排気バルブを直動することを特徴とする請求項１記載の頭上カム軸式内燃機関のカム軸軸受構造。  2. A camshaft bearing structure for an overhead camshaft internal combustion engine according to claim 1, wherein each of the intake camshaft and the exhaust camshaft directly moves the intake valve and the exhaust valve. 前記カムチェーン室の両側にはヘッドボルト用のボス部が形成され、
前記軸受部が前記ボス部よりカムチェーン室側に形成されることを特徴とする請求項１または請求項２記載の頭上カム軸式内燃機関のカム軸軸受構造。Boss portions for head bolts are formed on both sides of the cam chain chamber,
The camshaft bearing structure for an overhead camshaft internal combustion engine according to claim 1 or 2, wherein the bearing portion is formed closer to the cam chain chamber than the boss portion.
JP2002287251A 2002-09-30 2002-09-30 Camshaft bearing structure of overhead camshaft internal combustion engine Expired - Fee Related JP4017488B2 (en)

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DE2003617150 DE60317150T2 (en) 2002-09-30 2003-09-15 Camshaft bearing structure for an internal combustion engine with overhead camshafts
EP03020860A EP1403497B1 (en) 2002-09-30 2003-09-15 Camshaft bearing structure for over-head camshaft type internal combustion engine

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