JP2005054720A

JP2005054720A - Engine

Info

Publication number: JP2005054720A
Application number: JP2003287661A
Authority: JP
Inventors: Masanori Tsubouchi; 方則坪内; Giichi Sato; 義一佐藤
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2003-08-06
Filing date: 2003-08-06
Publication date: 2005-03-03
Anticipated expiration: 2023-08-06
Also published as: JP4154297B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide the valve system of an engine wherein rocking force of a rocker arm is smoothly transmitted to a bridge member crossed between a plurality of and the same type of valves which leads to reduction in the loss of power by frictional resistance and to improvement of durability. <P>SOLUTION: In the engine, bridged members 38i, 38e for simultaneously transmitting rocking of main rocker arms 23i, 23e to a plurality of valves 19i, 19i; 19e, 19e are interposed between a plurality of valves 19i, 19i; 19e, 19e which are arranged in parallel with each other on one side of a cylinder axis Y and main rocker arms 23i, 23e rockably supported on a main rocker shaft 32 arranged on one side of the cylinder axis Y. Auxiliary rocker shafts 33i, 33e are arranged in a position apart from a plurality of valves 19i, 19i; 19e, 19e in opposite direction to the cylinder axis Y. The bridged members 38i, 38e are integrally formed on the tips of auxiliary rocker arms 24i, 24e rockably supported on the auxiliary rocker shafts 33i, 33e. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は，シリンダ軸線の一側に互いに平行に配置される複数の弁と，前記シリンダ軸線の一側に配置されるロッカ軸に揺動可能に支承されてカム軸から駆動されるロッカアームとの間に，該ロッカアームの揺動を前記複数の弁に同時に伝達するブリッジ部材を介裝したエンジンの改良に関する。 The present invention includes a plurality of valves arranged parallel to each other on one side of a cylinder axis, and a rocker arm supported swingably on a rocker shaft arranged on one side of the cylinder axis and driven from a cam shaft. In the meantime, the present invention relates to an improvement of the engine through a bridge member that simultaneously transmits the rocker arm swing to the plurality of valves.

かゝるエンジンは，例えば下記特許文献１及び２に開示されているように，既に知られている。
実開昭５５−１７６４０５号公報実公昭６０−３０４０４号公報 Such an engine is already known as disclosed in, for example, Patent Documents 1 and 2 below.
Japanese Utility Model Publication No. 55-176405 Japanese Utility Model Publication No. 60-30404

上記特許文献１及び２記載のものでは，単一のロッカアームによりブリッジ部材を介して一対の弁を同時に開閉駆動することができるが，一対の弁の開閉を同期させるために，ブリッジ部材に，一対の弁の弁軸間でそれらと平行に延びる摺動軸を形成し，この摺動軸を，一対の弁を支承するシリンダヘッドに設けたガイド孔に摺動自在に嵌合している。 In the above-mentioned Patent Documents 1 and 2, a pair of valves can be simultaneously opened and closed via a bridge member by a single rocker arm, but in order to synchronize the opening and closing of the pair of valves, A sliding shaft extending in parallel with these valve shafts is formed, and this sliding shaft is slidably fitted into a guide hole provided in a cylinder head that supports a pair of valves.

しかしながら，上記のように，一対の弁の弁軸間にブリッジ部材の摺動軸を配置するようなことは，一対の弁の軸間距離の増加させ，結局，エンジンの大型化を招くことになって好ましくない。また上記のものでは，ブリッジ部材は摺動軸及びガイド孔に沿って直線運動をするのに対して，そのブリッジ部材を押圧するロッカアームの揺動端は円弧運動をするものであるから，それらの運動形態の相違により，ブリッジ部材の軸部及びガイド孔にはサイドスラスト荷重が加わり，該軸部の摺動抵抗を大きくし，動力損失を増加させるのみならず，該軸部の耐久性を低下させる虞もある。 However, as described above, disposing the sliding shaft of the bridge member between the valve shafts of the pair of valves increases the distance between the shafts of the pair of valves, resulting in an increase in the size of the engine. It is not preferable. In the above, the bridge member moves linearly along the sliding shaft and the guide hole, whereas the rocking end of the rocker arm that presses the bridge member performs an arc motion. Due to the difference in motion form, side thrust loads are applied to the shaft and guide holes of the bridge member, increasing the sliding resistance of the shaft and increasing power loss as well as reducing the durability of the shaft. There is also a risk of causing it.

本発明は，かゝる事情に鑑みてなされたもので，ブリッジ部材の支持部に影響されることなく複数の弁の軸間距離を充分に詰めることができ，しかも，そのブリッジ部材の支持部にはサイドスラスト荷重が加わらないようにして，ブリッジ部材がロッカアームの揺動力を複数の弁にスムーズに伝達することを可能し，摩擦抵抗による動力損失の低減と耐久性の向上に寄与し得る，前記エンジンを提供することを目的とする。 The present invention has been made in view of such circumstances, and can sufficiently reduce the distance between the axes of the plurality of valves without being affected by the support portion of the bridge member, and the support portion of the bridge member. The bridge member can smoothly transmit the rocking force of the rocker arm to multiple valves without applying side thrust load, which can contribute to reduction of power loss due to frictional resistance and improvement of durability. An object of the present invention is to provide the engine.

上記目的を達成するために，本発明は，シリンダ軸線の一側に互いに平行に配置される複数の弁と，前記シリンダ軸線の一側に配置される主ロッカ軸に揺動可能に支承されてカム軸から駆動されるロッカアームとの間に，該ロッカアームの揺動を前記複数の弁に同時に伝達するブリッジ部材を介裝したエンジンにおいて，前記複数の弁から前記シリンダ軸線と反対方向に離れた位置に副ロッカ軸を配置し，この副ロッカ軸に揺動可能に支承される副ロッカアームの先端に前記ブリッジ部材を一体に形成したことを第１の特徴とする。 In order to achieve the above object, the present invention is supported by a plurality of valves arranged parallel to each other on one side of a cylinder axis and a main rocker shaft arranged on one side of the cylinder axis so as to be swingable. In an engine having a bridge member that transmits the rocker arm swinging to the plurality of valves at the same time with a rocker arm driven from the camshaft, a position separated from the plurality of valves in the direction opposite to the cylinder axis. A first feature is that a secondary rocker shaft is disposed on the front end of the secondary rocker arm, and the bridge member is integrally formed at the tip of a secondary rocker arm that is swingably supported by the secondary rocker shaft.

また本発明は，第１の特徴に加えて，前記副ロッカアームの先端に前記ブリッジ部材の中央部を一体に連結し，そのブリッジ部材の中央部を前記ロッカアームから押圧される入力部としたことを第２の特徴とする。 According to the present invention, in addition to the first feature, a central portion of the bridge member is integrally connected to a tip of the auxiliary rocker arm, and the central portion of the bridge member is used as an input portion pressed from the rocker arm. The second feature.

さらに本発明は，第１又は第２の特徴に加えて，前記複数の弁を，各一対の吸気弁及び排気弁とし，これら吸気弁及び排気弁を，これらがシリンダ軸線に二分される一定の挟み角をなすように配置し，前記シリンダ軸線上に点火プラグを配置したことを第３の特徴とする。 Furthermore, in addition to the first or second feature, the present invention provides the plurality of valves as a pair of intake valves and exhaust valves, and the intake valves and exhaust valves are fixedly divided into two cylinder axes. A third feature is that the spark plugs are arranged so as to form an included angle and the spark plugs are arranged on the cylinder axis.

さらにまた本発明は，第３の特徴に加えて，前記各一対の吸気弁及び排気弁に対応する副吸気ロッカアーム及び副排気ロッカアームを支承する副吸気ロッカ軸及び副排気ロッカ軸をそれぞれ吸気弁及び排気弁からシリンダ軸線と反対方向に離して配置し，副吸気ロッカアーム及び副排気ロッカアームに対応する主吸気ロッカアーム及び主排気ロッカアームを支承する共通一本の主ロッカ軸をシリンダ軸線の一側に前記副吸気ロッカ軸及び副排気ロッカ軸と直角に配置したことを第４の特徴とする。 In addition to the third feature of the present invention, the auxiliary intake rocker shaft and the auxiliary exhaust rocker shaft that support the auxiliary intake rocker arm and the auxiliary exhaust rocker arm corresponding to each of the pair of intake valves and exhaust valves are respectively connected to the intake valve and the auxiliary exhaust rocker shaft. A common main rocker shaft that supports the main intake rocker arm and the main exhaust rocker arm corresponding to the sub intake rocker arm and the sub exhaust rocker arm is arranged on the side of the cylinder axis, and is separated from the exhaust valve in the direction opposite to the cylinder axis. A fourth feature is that the intake rocker shaft and the auxiliary exhaust rocker shaft are arranged at right angles.

さらにまた本発明は，第３又は４の特徴に加えて，前記吸気弁及び排気弁を支持するシリンダヘッドに，前記吸気弁及び排気弁の弁軸間を通る主通風路と，この主通風路に連通して前記一対の排気弁間を抜ける副通風路とを形成したことを第５の特徴とする。 Furthermore, in addition to the third or fourth feature, the present invention provides a cylinder head that supports the intake valve and the exhaust valve, a main ventilation path that passes between the valve shafts of the intake valve and the exhaust valve, and the main ventilation path. A sub-ventilating passage that communicates with the exhaust passage through the pair of exhaust valves is formed as a fifth feature.

本発明の第１の特徴によれば，ロッカアームの揺動力により副ロッカアームを揺動させることにより，副ロッカアームと一体のブリッジ部材が複数の弁を同時に開閉することになる。その副ロッカアームの揺動時，副ロッカアームとそれを支持する副ロッカ軸との間に発生する回転摩擦抵抗は極めて小さいので，潤滑も容易となり，摩擦抵抗による動力損失の低減と耐久性の向上を図ることができる。 According to the first feature of the present invention, the bridge member integral with the secondary rocker arm opens and closes the plurality of valves simultaneously by swinging the secondary rocker arm by the rocking force of the rocker arm. When the secondary rocker arm swings, the rotational frictional resistance generated between the secondary rocker arm and the secondary rocker shaft that supports it is extremely small, making lubrication easy, reducing power loss and improving durability due to frictional resistance. Can be planned.

しかもブリッジ部材付きの副ロッカアームを支承する副ロッカ軸は，複数の弁からシリンダ軸線と反対方向に離れた位置に配置されるので，この副ロッカ軸に干渉されることなく複数の弁の軸間距離を充分に詰めてエンジンのコンパクト化を図ることができる。 In addition, the auxiliary rocker shaft that supports the auxiliary rocker arm with the bridge member is arranged at a position away from the plurality of valves in the direction opposite to the cylinder axis, so that there is no interference between the auxiliary rocker shafts. The engine can be made compact by narrowing the distance sufficiently.

本発明の第２の特徴によれば，ロッカアームの押圧力をブリッジ部材に効率よく作用させて複数の弁を確実に同時に開閉させることができると共に，副ロッカアームには，無用な曲げや捩じり荷重を与えることがなく，その耐久性を更に向上させることができる。 According to the second feature of the present invention, the pressing force of the rocker arm can be efficiently applied to the bridge member so that a plurality of valves can be reliably opened and closed simultaneously, and the auxiliary rocker arm has no unnecessary bending or twisting. The durability can be further improved without applying a load.

本発明の第３の特徴によれば，燃料効率の高いペントルーフ型の燃焼室を持つ４弁式エンジンへの適用が可能であり，また点火プラグが燃焼室の中心部に電極を臨ませることになるから，燃焼効率の一層の向上を図ることができ，しかも吸気弁及び排気弁のための各ロッカアーム及び副ロッカアームは，この点火プラグを避けて，その周囲に配置されることになるから，点火プラグの脱着が容易であり，メンテナンス性が良好である。 According to the third aspect of the present invention, the present invention can be applied to a four-valve engine having a pent roof type combustion chamber with high fuel efficiency, and the spark plug faces the electrode at the center of the combustion chamber. Therefore, the combustion efficiency can be further improved, and the rocker arm and the auxiliary rocker arm for the intake valve and the exhaust valve are arranged around the spark plug so as to avoid the spark plug. Plugs can be easily attached and removed, and maintainability is good.

本発明の第４の特徴によれば，各副ロッカアームの有効アーム長を充分長く確保して，各ブリッジ部材の揺動を吸気及び排気弁の直線運動に極力近づけて，その間の摩擦の低減を図ることができ，しかもシリンダ軸線上への点火プラグの配置を可能にしつゝ動弁装置のコンパクト化を図ることができる。 According to the fourth feature of the present invention, the effective arm length of each sub-rocker arm is ensured sufficiently long so that the swing of each bridge member is as close as possible to the linear motion of the intake and exhaust valves, and the friction between them is reduced. In addition, it is possible to reduce the size of the peristaltic valve device by allowing the ignition plug to be arranged on the cylinder axis.

本発明の第５の特徴によれば，主通風路を通過する冷却風の一部が副通風路を通ることにより，高温になり勝ちの，一対の排気弁に挟まれる部分を効果的に冷却することができる。 According to the fifth feature of the present invention, a part of the cooling air passing through the main ventilation passage passes through the sub ventilation passage, so that the portion sandwiched between the pair of exhaust valves, which tends to become high temperature, is effectively cooled. can do.

本発明の実施の形態を，添付図面に示す本発明の好適な実施例に基づいて以下に説明する。 Embodiments of the present invention will be described below on the basis of preferred embodiments of the present invention shown in the accompanying drawings.

図１は本発明の実施例に係る４サイクル式エンジンの側面図，図２は同エンジンの縦断側面図，図３は図１の３−３線断面図，図４は図３の４−４線断面図，図５は図３の５−５線断面図，図６は図３の６−６線断面図，図７は図６の７−７線断面図，図８は図５の８−８線断面図である。 1 is a side view of a four-cycle engine according to an embodiment of the present invention, FIG. 2 is a longitudinal side view of the engine, FIG. 3 is a sectional view taken along line 3-3 in FIG. 1, and FIG. 5 is a sectional view taken along line 5-5 of FIG. 3, FIG. 6 is a sectional view taken along line 6-6 of FIG. 3, FIG. 7 is a sectional view taken along line 7-7 of FIG. FIG.

先ず，図１〜図３において，符号Ｅは，４サイクル式の汎用エンジンである。このエンジンＥのエンジン本体１は，クランクケース２，シリンダブロック３及びシリンダヘッド４から構成され，シリンダブロック３及びシリンダヘッド４は多数の冷却フィンを外周に備えている。クランクケース２は，据え付けフランジ５を有して一側面を開放したケース本体２ａと，その開放面を閉じるようにケース本体２ａに複数のボルト８で結合されるケース蓋体２ｂとからなっており，ケース本体２ａの一側壁とケース蓋体２ｂとに水平配置のクランク軸６の両端部がボールベアリング７，７′を介して回転自在に支承される。シリンダブロック３は一本のシリンダボア３ａを有して上記ケース本体２ａと一体に鋳造されたもので，そのシリンダボア３ａの中心線，即ちシリンダ軸線Ｙは水平線に対してクランク軸６から離れる方向へ上向きに傾斜している。シリンダボア３ａに嵌装されるピストン９は，従来普通のようにコンロッド１０を介してクランク軸６と連接される。 First, in FIGS. 1 to 3, a symbol E is a four-cycle general-purpose engine. The engine body 1 of the engine E is composed of a crankcase 2, a cylinder block 3, and a cylinder head 4. The cylinder block 3 and the cylinder head 4 are provided with a number of cooling fins on the outer periphery. The crankcase 2 includes a case body 2a having a mounting flange 5 and having one side opened, and a case lid 2b coupled to the case body 2a by a plurality of bolts 8 so as to close the open surface. The both ends of the crankshaft 6 disposed horizontally are supported on one side wall of the case body 2a and the case lid 2b via ball bearings 7 and 7 '. The cylinder block 3 has a single cylinder bore 3a and is integrally cast with the case body 2a. The center line of the cylinder bore 3a, that is, the cylinder axis Y is directed upward in a direction away from the crankshaft 6 with respect to the horizontal line. It is inclined to. The piston 9 fitted in the cylinder bore 3a is connected to the crankshaft 6 via the connecting rod 10 as usual.

シリンダブロック３の上端面にボルト１１（図４参照）で接合されるシリンダヘッド４には，シリンダボア３ａに連なるペントルーフ型の燃焼室１２が形成される。 The cylinder head 4 joined to the upper end surface of the cylinder block 3 with a bolt 11 (see FIG. 4) is formed with a pent roof type combustion chamber 12 connected to the cylinder bore 3a.

図３及び図４に示すように，上記燃焼室１２の天井面は，クランク軸６の軸線と直交する方向に延びる稜線Ｘを共有する二つの斜面１２ｉ，１２ｅからなっており，それら斜面１２ｉ，１２ｅに各一対の吸気弁座１３ｉ，１３ｉ及び排気弁座１３ｅ，１３ｅが埋設され，両吸気弁座１３ｉ，１３ｉに連なる二股状の吸気ポート１４ｉと，両排気弁座１３ｅ，１３ｅに連なる二股状の排気ポート１４ｅとが互いに反対方向に指向するようにシリンダヘッド４に形成される。即ち吸気１４ｉ及び排気ポート１４ｅは所謂クロスフロー式に配置される。 As shown in FIGS. 3 and 4, the ceiling surface of the combustion chamber 12 is composed of two inclined surfaces 12 i and 12 e sharing a ridge line X extending in a direction orthogonal to the axis of the crankshaft 6. A pair of intake valve seats 13i, 13i and exhaust valve seats 13e, 13e are embedded in 12e, a bifurcated intake port 14i connected to both intake valve seats 13i, 13i, and a bifurcated shape connected to both exhaust valve seats 13e, 13e. The exhaust port 14e is formed in the cylinder head 4 so as to be directed in opposite directions. That is, the intake air 14i and the exhaust port 14e are arranged in a so-called cross flow type.

またシリンダヘッド４には，両吸気弁座１３ｉ，１３ｉと協働して吸気ポート１４ｉを開閉する一対の吸気弁１９ｉ，１９ｉと，両排気弁座１３ｅ，１３ｅと協働して排気ポート１４ｅを開閉する一対の排気弁１９ｅ，１９ｅとが，シリンダヘッド４に固設された弁ガイド１５ｉ，１５ｅに摺動自在に支承される。 The cylinder head 4 has a pair of intake valves 19i and 19i that open and close the intake port 14i in cooperation with both intake valve seats 13i and 13i, and an exhaust port 14e in cooperation with both exhaust valve seats 13e and 13e. A pair of exhaust valves 19e, 19e that open and close are slidably supported by valve guides 15i, 15e fixed to the cylinder head 4.

以上において，吸気効率を極力高めるために，吸気弁座１３ｉ，１３ｉ及び吸気弁１９ｉ，１９ｉの傘部の有効径は，排気弁座１３ｅ，１３ｅ及び排気弁１９ｅ，１９ｅの傘部のそれより大きく設定される。 In the above, in order to increase the intake efficiency as much as possible, the effective diameters of the umbrella portions of the intake valve seats 13i and 13i and the intake valves 19i and 19i are larger than those of the exhaust valve seats 13e and 13e and the umbrella portions of the exhaust valves 19e and 19e. Is set.

また吸気弁１９ｉ，１９ｉ同士，排気弁１９ｅ，１９ｅ同士はそれぞれ互いに弁軸を平行にし，且つ吸気弁１９ｉ，１９ｉ同士の軸間距離及び排気弁１９ｅ，１９ｅ同士の軸間距離を互いに等しくして配置されるが，吸気弁１９ｉ，１９ｉと排気弁１９ｅ，１９ｅとは，燃焼室１２の天井面の前記形状に対応して，それらの弁軸間距離が燃焼室１２から離れるにつれて増加するように配置される。したがって，吸気弁１９ｉ，１９ｉ及び排気弁１９ｅ，１９ｅの弁軸は，シリンダ軸線Ｙにより二分される一定の挟み角θをなして配置されることになる。 Further, the intake valves 19i, 19i and the exhaust valves 19e, 19e are made parallel to each other, and the distance between the intake valves 19i, 19i and the distance between the exhaust valves 19e, 19e are made equal to each other. Although arranged, the intake valves 19i and 19i and the exhaust valves 19e and 19e correspond to the shape of the ceiling surface of the combustion chamber 12 so that the distance between the valve shafts increases as the distance from the combustion chamber 12 increases. Be placed. Therefore, the valve shafts of the intake valves 19i and 19i and the exhaust valves 19e and 19e are arranged with a fixed pinching angle θ divided by the cylinder axis Y.

点火プラグ１６は，シリンダ軸線Ｙ上でシリンダヘッド４に螺着されて，その電極を燃焼室１２の天井面の中心部に臨ませている。 The spark plug 16 is screwed onto the cylinder head 4 on the cylinder axis Y so that the electrode faces the center of the ceiling surface of the combustion chamber 12.

上記吸気弁１９ｉ，１９ｉ及び排気弁１９ｅ，１９ｅには，これらを開閉駆動する動弁装置２０が連結される。 The intake valves 19i and 19i and the exhaust valves 19e and 19e are connected to a valve gear 20 that opens and closes the valves.

その動弁装置２０ついて次に説明する。 The valve gear 20 will be described next.

図１〜図３及び図５において，動弁装置２０は，一本のカム軸２１，一対の吸気及び排気プッシュロッド２２ｉ，２２ｅ，一対の主吸気及び排気ロッカアーム２３ｉ，２３ｅ，一対の副吸気及び排気ロッカアーム２４ｉ，２４ｅ，一対の吸気弁ばね２５ｉ，２５ｉ及び一対の排気弁ばね２５ｅ，２５ｅを主たる構成要素とするもので，それらについて順次説明する。 1 to 3 and 5, the valve gear 20 includes a single camshaft 21, a pair of intake and exhaust push rods 22 i and 22 e, a pair of main intake and exhaust rocker arms 23 i and 23 e, a pair of auxiliary intake and The exhaust rocker arms 24i and 24e, the pair of intake valve springs 25i and 25i, and the pair of exhaust valve springs 25e and 25e are the main constituent elements, which will be sequentially described.

先ず，一対の吸気弁ばね２５ｉ，２５ｉは，従来普通のように，一対の吸気弁１９ｉ，１９ｉの弁軸先端部に取り付けられるリテーナ２６ｉ，２６ｉとシリンダヘッド４との間にそれぞれ縮設され，また一対の排気弁ばね２５ｅ，２５ｅも，一対の排気弁１９ｅ，１９ｅの弁軸先端部に取り付けられるリテーナ２６ｅ，２６ｅとシリンダヘッド４との間にそれぞれ縮設される。 First, the pair of intake valve springs 25i and 25i are respectively compressed between the retainers 26i and 26i attached to the valve shaft tip portions of the pair of intake valves 19i and 19i and the cylinder head 4 as usual. Also, the pair of exhaust valve springs 25e, 25e are respectively contracted between the cylinder head 4 and the retainers 26e, 26e attached to the valve shaft tips of the pair of exhaust valves 19e, 19e.

次にカム軸２１は，シリンダボア３ａの軸方投影面の下方でクランク軸６と平行になるように，クランクケース２の両側壁に回転自在に支承され，そしてケース蓋体２ｂの外側において，クランク軸６に調時伝動装置２７を介して連結され，クランク軸６から２分の１の減速比をもって駆動されるようになっている。調時伝動装置２７は，ケース蓋体２ｂに接合されるサイドカバー１７によって覆われる。 Next, the camshaft 21 is rotatably supported on both side walls of the crankcase 2 so as to be parallel to the crankshaft 6 below the axial projection surface of the cylinder bore 3a, and on the outside of the case lid 2b, The shaft 6 is connected via a timing transmission device 27 and is driven from the crankshaft 6 with a half reduction ratio. The timing transmission device 27 is covered with a side cover 17 joined to the case lid 2b.

カム軸２１は吸気カム２１ｉ及び排気カム２１ｅを備えており，それらカム２１ｉ，２１ｅの周面に接して昇降する一対のタペット３０ｉ，３０ｅが，シリンダボア３ａに下方でそれと平行に延びる一対のガイド孔２８，２８に摺動自在に嵌合される。シリンダブロック３及びシリンダヘッド４には，上記ガイド孔２８，２８にそれぞれ連なる一連の戻し油路２９，２９が形成されており，これら戻し油路２９，２９に，下端が吸気及び排気タペット３０ｉ，３０ｅにそれぞれ当接する吸気及び排気プッシュロッド２２ｉ，２２ｅが配設される。 The cam shaft 21 includes an intake cam 21i and an exhaust cam 21e, and a pair of tappets 30i and 30e that move up and down in contact with the peripheral surfaces of the cams 21i and 21e extend to the cylinder bore 3a downward and parallel to the guide holes. 28 and 28 are slidably fitted. The cylinder block 3 and the cylinder head 4 are formed with a series of return oil passages 29, 29 respectively connected to the guide holes 28, 28. The lower ends of the return oil passages 29, 29 have intake and exhaust tappets 30i, Intake and exhaust push rods 22i and 22e that are in contact with 30e are disposed.

尚，上記各ガイド孔２８の内面には，潤滑オイルの流通のための油溝３１が形成されている。 An oil groove 31 is formed on the inner surface of each guide hole 28 for lubricating oil flow.

一方，シリンダヘッド４の上面にはヘッドカバー３５がボルト３６（図２参照）により結合され，これらシリンダヘッド４及びヘッドカバー３５間に，前記戻し油路２９，２９が開口する動弁室３７が画成される。動弁装置２０を潤滑して動弁室３７に溜まった潤滑オイルは，前記戻し油路２９，２９を経てクランクケース２内に戻るようになっている。 On the other hand, a head cover 35 is coupled to the upper surface of the cylinder head 4 by bolts 36 (see FIG. 2), and a valve operating chamber 37 in which the return oil passages 29, 29 are opened is defined between the cylinder head 4 and the head cover 35. Is done. Lubricating oil that has lubricated the valve operating device 20 and accumulated in the valve operating chamber 37 returns to the crankcase 2 through the return oil passages 29 and 29.

図３，図５，図７及び図８に示すように，動弁室３７において，シリンダヘッド４には一本の主ロッカ軸３２と一対の副吸気及び排気ロッカ軸３３ｉ，３３ｅとが取り付けられる。主ロッカ軸３２は，シリンダ軸線Ｙとオイル戻し孔２９，２９との間でカム軸２１と平行に配置され，副吸気ロッカ軸３３ｉは，一対の吸気弁１９ｉ，１９ｉからシリンダ軸線Ｙと反対側へ，また副排気ロッカ軸３３ｅは排気弁１９ｅ，１９ｅからシリンダ軸線Ｙと反対側へそれぞれ極力離れた位置に主ロッカ軸３２と直角に配置される。 As shown in FIGS. 3, 5, 7 and 8, in the valve operating chamber 37, one main rocker shaft 32 and a pair of auxiliary intake and exhaust rocker shafts 33 i and 33 e are attached to the cylinder head 4. . The main rocker shaft 32 is disposed parallel to the cam shaft 21 between the cylinder axis Y and the oil return holes 29, 29, and the auxiliary intake rocker shaft 33i is opposite to the cylinder axis Y from the pair of intake valves 19i, 19i. The auxiliary exhaust rocker shaft 33e is disposed at right angles to the main rocker shaft 32 at positions as far away from the exhaust valves 19e, 19e as possible to the opposite side of the cylinder axis Y.

そして，先ず副吸気ロッカ軸３３ｉに副吸気ロッカアーム２４ｉが，また副排気ロッカ軸３３ｅに副排気ロッカアーム２４ｅがそれぞれ対応する吸気及び排気弁１９ｉ，１９ｉ；１９ｅ，１９ｅの開閉方向に揺動可能に支承される。 First, the auxiliary intake rocker arm 24i is supported by the auxiliary intake rocker shaft 33i, and the auxiliary exhaust rocker arm 24e is supported by the auxiliary exhaust rocker shaft 33e so as to be swingable in the opening and closing directions of the intake and exhaust valves 19i, 19i; 19e, 19e. Is done.

副吸気ロッカアーム２４ｉの揺動端には，副吸気ロッカ軸３３ｉと平行に延びる吸気ブリッジ部材３８ｉの中央部が一体に連結され，この吸気ブリッジ部材３８ｉは一対の吸気弁１９ｉ，１９ｉの弁頭間に橋渡しされるように配置される。 A central portion of an intake bridge member 38i extending in parallel with the auxiliary intake rocker shaft 33i is integrally connected to the swing end of the auxiliary intake rocker arm 24i. The intake bridge member 38i is connected between the valve heads of the pair of intake valves 19i and 19i. It is arranged to be bridged to.

また副排気ロッカアーム２４ｅの揺動端には，副排気ロッカ軸３３ｅと平行に延びる排気ブリッジ部材３８ｅの中央部が一体に連結され，この排気ブリッジ部材３８ｅは一対の排気弁１９ｅ，１９ｅの弁頭間に橋渡しされるように配置される。 A central portion of an exhaust bridge member 38e extending in parallel with the auxiliary exhaust rocker shaft 33e is integrally connected to the swing end of the auxiliary exhaust rocker arm 24e. The exhaust bridge member 38e is connected to the valve heads of the pair of exhaust valves 19e and 19e. Arranged to be bridged between them.

上記吸気ブリッジ部材３８ｉ付きの副吸気ロッカアーム２４ｉ及び排気ブリッジ部材３８ｅ付きの副排気ロッカアーム２４ｅは，吸気弁１９ｉ，１９ｉ同士の軸間距離及び排気弁１９ｅ，１９ｅ同士の軸間距離を互いに等しくしたことから，相互に互換性のある同一部品で構成され，これによってコストの低減が図られる。 In the auxiliary intake rocker arm 24i with the intake bridge member 38i and the auxiliary exhaust rocker arm 24e with the exhaust bridge member 38e, the distance between the intake valves 19i and 19i and the distance between the exhaust valves 19e and 19e are equal to each other. Therefore, it is composed of the same parts that are compatible with each other, thereby reducing the cost.

主ロッカ軸３２には，主吸気ロッカアーム２３ｉ及び主排気ロッカアーム２３ｅがそれぞれ揺動可能に支承される。主吸気ロッカアーム２３ｉは，互いに反対方向に張り出した２本のアーム部２３ｉａ，２３ｉｂを備えていて，一方のアーム部２３ｉａを前記吸気プッシュロッド２２ｉの上端に連接し，他方のアーム部２３ｉｂを前記副吸気ロッカアーム２４ｉの吸気ブリッジ部材３８ｉの中央部上面に当接させるように対向させる。 A main intake rocker arm 23i and a main exhaust rocker arm 23e are supported on the main rocker shaft 32 so as to be swingable. The main intake rocker arm 23i is provided with two arm portions 23ia and 23ib projecting in opposite directions, one arm portion 23ia is connected to the upper end of the intake push rod 22i, and the other arm portion 23ib is connected to the auxiliary arm 23ib. The intake rocker arm 24i is opposed to the upper surface of the central portion of the intake bridge member 38i.

また主排気ロッカアーム２３ｅも，互いに反対方向に張り出した２本のアーム部２３ｅａ，２３ｅｂを備えていて，一方のアーム部２３ｅａを前記排気プッシュロッド２２ｅの上端に連接し，他方のアーム部２３ｅｂを前記副排気ロッカアーム２４ｅの排気ブリッジ部材３８ｅの中央部に当接させるように対向させる。 The main exhaust rocker arm 23e also includes two arm portions 23ea and 23eb projecting in opposite directions. One arm portion 23ea is connected to the upper end of the exhaust push rod 22e, and the other arm portion 23eb is connected to the above-described arm portion 23eb. The auxiliary exhaust rocker arm 24e is opposed to the central portion of the exhaust bridge member 38e.

その際，図８に明示するように，吸気及び排気弁１９ｉ，１９ｉ；１９ｅ，19ｅの各弁頭間隙を調整するために，主吸気及び排気ロッカアーム２３ｉ，２３ｅのアーム部２３ｉｂ，２３ｅｂには，調節ボルト３９が対応する吸気及び排気ブリッジ部材３８ｉ，３８ｅの上面に対して進退調節可能に螺着され，また各ブリッジ部材３８ｉ，３８ｅと対応する弁１９ｉ，１９ｉ；１９ｅ，19ｅの弁頭間にはシム４０が介裝され，このシム４０は対応するリテーナ２６ｉ，２６ｅに保持される。 At that time, as clearly shown in FIG. 8, in order to adjust the valve head gaps of the intake and exhaust valves 19i, 19i; 19e, 19e, the arm portions 23ib, 23eb of the main intake and exhaust rocker arms 23i, 23e are Adjustment bolts 39 are screwed to the upper surfaces of the corresponding intake and exhaust bridge members 38i, 38e so as to be able to advance and retract, and between the corresponding valve members 19i, 19i; 19e, 19e valve heads. The shim 40 is interposed between the retainers 26i and 26e.

図１〜図３及び図５〜図７において，シリンダヘッド４には，燃焼室１２に近接して各一対の吸気弁１９ｉ，１９ｉと排気弁１９ｅ，１９ｅとの間を横断しつゝ点火プラグ１６の周りを通る主通風路４１と，この主通風路４１の，吸気弁１９ｉ，１９ｉと排気弁１９ｅ，１９ｅを過ぎた下流側で横方向に分岐する一対の第１副通風路４２，４２と，主通風路４１から両排気弁１９ｅ，１９ｅ間を，それらの傘部に近接して通過する第２副通風路４３とが設けられる。またシリンダヘッド４及びヘッドカバー３５に亙り，動弁室３７の中心部を貫通して点火プラグ１６の直上で主通風路４１に連通するプラグガイド孔４４が設けられ，このプラグガイド孔４４を通して点火プラグ１６がシリンダヘッド４の所定位置に螺着されると共に，それに接続されるハイテンションコード（図示せず）がそのプラグガイド孔４４に配線される。主通風路４１には，このエンジンＥが車両用に使用される場合は走行風が冷却風として供給され，また定置作業機用に使用される場合には冷却ファンによって発生される冷却風が供給される。 1 to 3 and 5 to 7, the cylinder head 4 includes a spark plug that crosses between the pair of intake valves 19 i and 19 i and the exhaust valves 19 e and 19 e in the vicinity of the combustion chamber 12. 16 and a pair of first auxiliary ventilation passages 42, 42 that branch laterally on the downstream side of the main ventilation passage 41 past the intake valves 19i, 19i and the exhaust valves 19e, 19e. And a second auxiliary ventilation passage 43 that passes between the main ventilation passage 41 and the exhaust valves 19e, 19e close to the umbrella portion. A plug guide hole 44 is provided over the cylinder head 4 and the head cover 35, passing through the central portion of the valve operating chamber 37 and communicating with the main ventilation path 41 directly above the ignition plug 16. 16 is screwed into a predetermined position of the cylinder head 4 and a high tension cord (not shown) connected thereto is wired in the plug guide hole 44. When the engine E is used for a vehicle, traveling air is supplied as cooling air to the main ventilation path 41, and cooling air generated by a cooling fan is supplied when used for a stationary work machine. Is done.

次に，この実施例の作用について説明する。 Next, the operation of this embodiment will be described.

エンジンＥの運転中，カム軸２１の回転に伴ない吸気カム２１ｉ及び排気カム２１ｅがタペット３０ｉ，３０ｅをそれぞれ介して吸気プッシュロッド２２ｉ及び排気プッシュロッド２２ｅを交互に押し上げると，主吸気ロッカアーム２３ｉ及び主排気ロッカアーム２３ｅが主ロッカ軸３２周りに交互に揺動して，副吸気ブリッジ部材３８ｉ及び副排気ブリッジ部材３８ｅを交互に押圧する。すると，副吸気ブリッジ部材３８ｉ及び副排気ブリッジ部材３８ｅは，それらを一体に支持する副吸気ロッカアーム２４ｉ及び副排気ロッカアーム２４ｅと共に，副吸気ロッカ軸３３ｉ及び副排気ロッカ軸３３ｅ周りに交互に揺動しながら，各一対の吸気弁１９ｉ，１９ｉ及び排気弁１９ｅ，１９ｅを，吸気弁ばね２５ｉ，２５ｉ及び排気弁ばね２５ｅ，２５ｅの反発力に抗して交互に同時開弁する。 During the operation of the engine E, when the intake cam 21i and the exhaust cam 21e alternately push up the intake push rod 22i and the exhaust push rod 22e through the tappets 30i and 30e as the cam shaft 21 rotates, the main intake rocker arm 23i and The main exhaust rocker arm 23e is alternately swung around the main rocker shaft 32, and alternately presses the auxiliary intake bridge member 38i and the auxiliary exhaust bridge member 38e. Then, the auxiliary intake bridge member 38i and the auxiliary exhaust bridge member 38e swing around the auxiliary intake rocker shaft 33i and the auxiliary exhaust rocker shaft 33e together with the auxiliary intake rocker arm 24i and the auxiliary exhaust rocker arm 24e that support them integrally. However, the pair of intake valves 19i and 19i and the exhaust valves 19e and 19e are alternately opened simultaneously against the repulsive force of the intake valve springs 25i and 25i and the exhaust valve springs 25e and 25e.

吸気カム２１ｉ及び排気カム２１ｅが吸気プッシュロッド２２ｉ及び排気プッシュロッド２２ｅに対する押し上げ力をそれぞれ解放すると，吸気弁１９ｉ，１９ｉ及び排気弁１９ｅ，１９ｅは，吸気弁ばね２５ｉ，２５ｉ及び排気弁ばね２５ｅ，２５ｅの反発力をもって閉弁し，それに伴ない副吸気ブリッジ部材３８ｉ及び副排気ブリッジ部材３８ｅから吸気プッシュロッド２２ｉ及び排気プッシュロッド２２ｅまでの動弁装置２０の各部材は原位置に復帰し，以上の作用が繰り返えされる。 When the intake cam 21i and the exhaust cam 21e release the push-up force with respect to the intake push rod 22i and the exhaust push rod 22e, respectively, the intake valves 19i and 19i and the exhaust valves 19e and 19e become intake valve springs 25i and 25i and exhaust valve springs 25e, Each valve member 20 from the auxiliary intake bridge member 38i and the auxiliary exhaust bridge member 38e to the intake push rod 22i and the exhaust push rod 22e is returned to the original position. Is repeated.

ところで，上記のように，主吸気ロッカアーム２３ｉ及び主排気ロッカアーム２３ｅが吸気ブリッジ部材３８ｉ及び排気ブリッジ部材３８ｅを押圧するとき，吸気ブリッジ部材３８ｉ及び排気ブリッジ部材３８ｅは，副吸気ロッカアーム２４ｉ及び副排気ロッカアーム２４ｅと共に，副吸気ロッカ軸３３ｉ及び副排気ロッカ軸３３ｅ周りに揺動するので，各副ロッカアーム２４ｉ，２４ｅと各副ロッカ軸３３ｉ，３３ｅとの間に発生する回転摩擦抵抗は極めて小さく，したがってその間の潤滑も容易となり，摩擦抵抗による動力損失の低減と耐久性の向上を図ることができる。 By the way, as described above, when the main intake rocker arm 23i and the main exhaust rocker arm 23e press the intake bridge member 38i and the exhaust bridge member 38e, the intake bridge member 38i and the exhaust bridge member 38e become the auxiliary intake rocker arm 24i and the auxiliary exhaust rocker arm. 24e and the auxiliary intake rocker shaft 33i and the auxiliary exhaust rocker shaft 33e, so that the rotational friction resistance generated between the auxiliary rocker arms 24i and 24e and the auxiliary rocker shafts 33i and 33e is extremely small. Lubrication is easy, reducing power loss due to frictional resistance and improving durability.

しかも主吸気ロッカアーム２３ｉ及び主排気ロッカアーム２３ｅは，それぞれの押圧力を吸気ブリッジ部材３８ｉ及び排気ブリッジ部材３８ｅの中央部に集中させるので，各主ロッカアーム２３ｉ，２３ｅの押圧力を各ブリッジ部材３８ｉ，３８ｅに効率よく作用させて各一対の吸気及び排気弁１９ｉ，１９ｉ；１９ｅ，19ｅを確実に同時に開閉させることができ，しかも各副ロッカアーム２４ｉ，２４ｅには，単純なモーメントが作用するのみで，無用な曲げや捩じり荷重を与えることがなく，その耐久性を更に向上させることができると共に，各副ロッカ軸３３ｉ，３３ｅの小径化を図ることができる。 In addition, the main intake rocker arm 23i and the main exhaust rocker arm 23e concentrate their pressing forces on the central portions of the intake bridge member 38i and the exhaust bridge member 38e, so that the pressing forces of the main rocker arms 23i, 23e are applied to the bridge members 38i, 38e. Each pair of intake and exhaust valves 19i, 19i; 19e, 19e can be reliably opened and closed at the same time, and each sub-rocker arm 24i, 24e is merely used with a simple moment. Therefore, the durability of the auxiliary rocker shafts 33i and 33e can be reduced and the durability can be further improved.

さらに副吸気及び排気ロッカアーム２４ｉ，２４ｅをそれぞれ支承する副吸気及び排気ロッカ軸３３ｉ，３３ｅは，各一対の吸気及び排気弁１９ｉ，１９ｅからそれぞれシリンダ軸線Ｙと反対方向に離れた位置に配置されるので，これら副吸気及び排気ロッカ軸３３ｉ，３３ｅに全く干渉されることなく各一対の吸気及び排気弁１９ｉ，１９ｅの軸間距離を充分に詰めてエンジンＥのコンパクト化を図ることができる。 Further, the auxiliary intake and exhaust rocker shafts 33i and 33e for supporting the auxiliary intake and exhaust rocker arms 24i and 24e, respectively, are disposed at positions away from the pair of intake and exhaust valves 19i and 19e in the direction opposite to the cylinder axis Y, respectively. Therefore, the distance between the shafts of the pair of intake and exhaust valves 19i and 19e can be sufficiently reduced without any interference with the auxiliary intake and exhaust rocker shafts 33i and 33e, and the engine E can be made compact.

またこの動弁装置２０が適用されるエンジンＥは，燃料効率の高いペントルーフ型の燃焼室１２を持ち，しかも点火プラグ１６は，燃焼室１２の中心部に電極を臨ませるべく，しかも動弁装置２０に邪魔されることなく，シリンダ軸線Ｙ上に容易に配置することができ，燃焼効率の向上を図ることができると共に，点火プラグ１６の脱着が容易で良好なメンテナンス性を確保し得る。 The engine E to which the valve operating device 20 is applied has a pent roof type combustion chamber 12 with high fuel efficiency, and the spark plug 16 has a valve operating device so that the electrode faces the center of the combustion chamber 12. 20 can be easily disposed on the cylinder axis Y without being obstructed, and the combustion efficiency can be improved, and the ignition plug 16 can be easily attached and detached to ensure good maintainability.

さらに副吸気ロッカアーム２４ｉ及び副排気ロッカアーム２４ｅを支承する副吸気ロッカ軸３３ｉ及び副排気ロッカ軸３３ｅをそれぞれ吸気弁１９ｉ，１９ｉ及び排気弁１９ｅ，１９ｅからシリンダ軸線Ｙと反対方向に離して配置し，主吸気ロッカアーム２３ｉ及び主排気ロッカアーム２３ｅを支承する共通一本の主ロッカ軸３２をシリンダ軸線Ｙの一側に副吸気ロッカ軸３３ｉ及び副排気ロッカ軸３３ｅと直角に配置したので，各ブリッジ部材３８ｉ，３８ｅの揺動を吸気及び排気弁１９ｉ，１９ｉ；１９ｅ，19ｅの直線運動に極力近づけて，その間の摩擦の低減を図ることができ，しかもシリンダ軸線Ｙ上への点火プラグ１６の配置を可能にしつゝ動弁装置２０のコンパクト化を図ることができる。 Further, the auxiliary intake rocker shaft 33i and the auxiliary exhaust rocker shaft 33e for supporting the auxiliary intake rocker arm 24i and the auxiliary exhaust rocker arm 24e are arranged away from the intake valve 19i, 19i and the exhaust valves 19e, 19e in the direction opposite to the cylinder axis Y, respectively. Since the common main rocker shaft 32 for supporting the main intake rocker arm 23i and the main exhaust rocker arm 23e is arranged on one side of the cylinder axis Y at right angles to the sub intake rocker shaft 33i and the sub exhaust rocker shaft 33e, each bridge member 38i , 38e can be made as close as possible to the linear motion of the intake and exhaust valves 19i, 19i; 19e, 19e to reduce friction between them, and the spark plug 16 can be arranged on the cylinder axis Y The compact peristaltic valve device 20 can be made compact.

一方，主通風路４１に冷却風が供給されると，その冷却風の大部分は主通風路４１を通過し，一部は主通風路４１内で主及び第２副通風路４２，４３に分流することにより，シリンダヘッド４，特に燃焼室１２上部を効率良く冷却することができる。また第２副通風路４３を流れる冷却風は，高温になり勝ちの，一対の排気弁１９ｅ，１９ｅ間を通過することになるから，シリンダヘッド４の両排気弁１９ｅ，１９ｅに挟まれる部分を効果的に冷却することができる。 On the other hand, when the cooling air is supplied to the main ventilation passage 41, most of the cooling air passes through the main ventilation passage 41, and a part of the cooling air is supplied to the main and second auxiliary ventilation passages 42 and 43 in the main ventilation passage 41. By splitting, the cylinder head 4, particularly the upper part of the combustion chamber 12 can be efficiently cooled. In addition, the cooling air flowing through the second auxiliary ventilation passage 43 passes between the pair of exhaust valves 19e, 19e, which tends to become high temperature, and therefore the portion sandwiched between the exhaust valves 19e, 19e of the cylinder head 4 is It can be cooled effectively.

ところで，排気弁１９ｅ，１９ｅの軸間距離と吸気弁１９ｉ，１９ｉの軸間距離が互いに等しく設定されているにも拘らず，排気弁１９ｅ，１９ｅの傘部は，吸気弁１９ｉ，１９ｉの傘部より小径になっているため，その分，排気弁１９ｅ，１９ｅ傘部周りではシリンダヘッド３の肉厚が厚くなり，前記第２副通風路４３は，その部分を利用して，排気弁１９ｅ，１９ｅ間に，それらの傘部に近接させて設けられたものであり，シリンダヘッド３の剛性低下を招くことなく，排気弁１９ｅ，１９ｅの傘部周の冷却に大きく寄与することができる。 Incidentally, although the distance between the axes of the exhaust valves 19e and 19e and the distance between the axes of the intake valves 19i and 19i are set equal to each other, the umbrella portion of the exhaust valves 19e and 19e is the umbrella of the intake valves 19i and 19i. Accordingly, the cylinder head 3 becomes thicker around the exhaust valve 19e, 19e umbrella, and the second auxiliary ventilation passage 43 uses the portion to exhaust the exhaust valve 19e. , 19e are provided close to these umbrella portions, and can greatly contribute to cooling of the periphery of the umbrella portions of the exhaust valves 19e, 19e without deteriorating the rigidity of the cylinder head 3.

本発明は上記実施例に限定されるものではなく，その要旨を逸脱しない範囲で種々の設計変更が可能である。例えば，カム軸２１をシリンダヘッド４に支承させ，それに主吸気及び排気ロッカアーム２３ｉ，２３ｅのアーム部２３ｉａ，２３ｅａを係合して，主吸気及び排気ロッカアーム２３ｉ，２３ｅを直接駆動するようにすることもできる。また本発明の第１の特徴は，一対の吸気弁と１本の排気弁を持つ３弁式エンジンへの適用も可能である。 The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, the camshaft 21 is supported by the cylinder head 4, and the main intake and exhaust rocker arms 23i and 23e are engaged with the arm portions 23ia and 23ea to directly drive the main intake and exhaust rocker arms 23i and 23e. You can also. The first feature of the present invention can also be applied to a three-valve engine having a pair of intake valves and one exhaust valve.

本発明の実施例に係る４サイクル式エンジンの側面図4 is a side view of a four-cycle engine according to an embodiment of the present invention. 同エンジンの縦断側面図Longitudinal side view of the engine 図１の３−３線断面図3-3 sectional view of FIG. 図３の３−３線断面図Sectional view taken along line 3-3 in FIG. 図３の５−５線断面図Sectional view along line 5-5 in FIG. 図３の６−６線断面図6-6 sectional view of FIG. 図６の７−７線断面図Sectional view along line 7-7 in FIG. 図５の８−８線断面図8-8 sectional view of FIG.

符号の説明Explanation of symbols

Ｅ・・・・・・・エンジン
Ｙ・・・・・・・シリンダ軸線
θ・・・・・・・挟み角
４・・・・・・・シリンダヘッド
１６・・・・・・点火プラグ
１９ｉ，１９ｉ・・・・一対の吸気弁
１９ｅ，１９ｅ・・・・一対の排気弁
２０・・・・・・動弁装置
２１・・・・・・カム軸
２３ｉ・・・・・主吸気ロッカアーム
２３ｅ・・・・・主排気ロッカアーム
２４ｉ・・・・・副吸気ロッカアーム
２４ｅ・・・・・副排気ロッカアーム
３２・・・・・・主ロッカ軸
３３ｉ・・・・・副吸気ロッカ軸
３３ｅ・・・・・副排気ロッカ軸
３８ｉ・・・・・吸気ブリッジ部材
３８ｅ・・・・・排気ブリッジ部材
４１・・・・・・主通風路
４３・・・・・・副通風路（第２副通風路） E ······· Engine Y ··········· Cylinder axis θ ···················································· 19i: a pair of intake valves 19e, 19e, a pair of exhaust valves 20, a valve operating device 21, a camshaft 23i, a main intake rocker arm 23e, ··· Main exhaust rocker arm 24i ··· Sub-intake rocker arm 24e ··· Sub exhaust rocker arm 32 ··· Main rocker shaft 33i ··· Sub-intake rocker shaft 33e ···・ Sub exhaust rocker shaft 38i .... Intake bridge member 38e .... Exhaust bridge member 41 .... Main ventilation path 43 .... Sub ventilation path (second auxiliary ventilation path)

Claims

シリンダ軸線（Ｙ）の一側に互いに平行に配置される複数の弁（１９ｉ，１９ｉ；１９ｅ，１９ｅ）と，前記シリンダ軸線（Ｙ）の一側に配置される主ロッカ軸（３２）に揺動可能に支承されてカム軸（２１）から駆動される主ロッカアーム（２３ｉ，２３ｅ）との間に，該主ロッカアーム（２３ｉ，２３ｅ）の揺動を前記複数の弁（１９ｉ，１９ｉ；１９ｅ，１９ｅ）に同時に伝達するブリッジ部材（３８ｉ，３８ｅ）を介裝したエンジンにおいて，
前記複数の弁（１９ｉ，１９ｉ；１９ｅ，１９ｅ）から前記シリンダ軸線（Ｙ）と反対方向に離れた位置に副ロッカ軸（３３ｉ，３３ｅ）を配置し，この副ロッカ軸（３３ｉ，３３ｅ）に揺動可能に支承される副ロッカアーム（２４ｉ，２４ｅ）の先端に前記ブリッジ部材（３８ｉ，３８ｅ）を一体に形成したことを特徴とするエンジン。 A plurality of valves (19i, 19i; 19e, 19e) arranged parallel to each other on one side of the cylinder axis (Y) and a main rocker shaft (32) arranged on one side of the cylinder axis (Y) The main rocker arms (23i, 23e) are swung between the plurality of valves (19i, 19i; 19e, 19e) between the main rocker arms (23i, 23e) that are movably supported and driven from the camshaft (21). 19e) in an engine via bridge members (38i, 38e) that transmit simultaneously,
A secondary rocker shaft (33i, 33e) is disposed at a position away from the plurality of valves (19i, 19i; 19e, 19e) in the direction opposite to the cylinder axis (Y), and the secondary rocker shaft (33i, 33e). An engine characterized in that the bridge member (38i, 38e) is integrally formed at the tip of a secondary rocker arm (24i, 24e) supported so as to be swingable.

請求項１記載のエンジンにおいて，
前記副ロッカアーム（２４ｉ，２４ｅ）の先端に前記ブリッジ部材（３８ｉ，３８ｅ）の中央部を一体に連結し，そのブリッジ部材（３８ｉ，３８ｅ）の中央部を前記主ロッカアーム（２３ｉ，２３ｅ）から押圧される入力部としたことを特徴とするエンジン。 The engine according to claim 1,
The central part of the bridge member (38i, 38e) is integrally connected to the tip of the secondary rocker arm (24i, 24e), and the central part of the bridge member (38i, 38e) is pressed from the main rocker arm (23i, 23e). An engine characterized by being an input unit.

請求項１又は２記載のエンジンにおいて，
前記複数の弁を，各一対の吸気弁（１９ｉ，１９ｉ）及び排気弁（１９ｅ，１９ｅ）とし，これら吸気弁（１９ｉ，１９ｉ）及び排気弁（１９ｅ，１９ｅ）を，これらがシリンダ軸線（Ｙ）に二分される一定の挟み角（θ）をなすように配置し，前記シリンダ軸線（Ｙ）上に点火プラグ（１６）を配置したことを特徴とするエンジン。 The engine according to claim 1 or 2,
The plurality of valves are a pair of intake valves (19i, 19i) and exhaust valves (19e, 19e), and these intake valves (19i, 19i) and exhaust valves (19e, 19e) are cylinder cylinders (Y ) And an ignition plug (16) disposed on the cylinder axis (Y).

請求項３記載のエンジンにおいて，
前記各一対の吸気弁（１９ｉ，１９ｉ）及び排気弁（１９ｅ，１９ｅ）に対応する副吸気ロッカアーム（２４ｉ）及び副排気ロッカアーム（２４ｅ）を支承する副吸気ロッカ軸（３３ｉ）及び副排気ロッカ軸（３３ｅ）をそれぞれ吸気弁（１９ｉ，１９ｉ）及び排気弁（１９ｅ，１９ｅ）からシリンダ軸線（Ｙ）と反対方向に離して配置し，副吸気ロッカアーム（２４ｉ）及び副排気ロッカアーム（２４ｅ）に対応する主吸気ロッカアーム（２３ｉ）及び主排気ロッカアーム（２３ｅ）を支承する共通一本の主ロッカ軸（３２）をシリンダ軸線（Ｙ）の一側に前記副吸気ロッカ軸（３３ｉ）及び副排気ロッカ軸（３３ｅ）と直角に配置したことを特徴とするエンジン。 The engine according to claim 3,
The auxiliary intake rocker shaft (33i) and the auxiliary exhaust rocker shaft for supporting the auxiliary intake rocker arm (24i) and the auxiliary exhaust rocker arm (24e) corresponding to the pair of intake valves (19i, 19i) and the exhaust valves (19e, 19e). (33e) is disposed away from the intake valve (19i, 19i) and the exhaust valve (19e, 19e) in the direction opposite to the cylinder axis (Y), and corresponds to the auxiliary intake rocker arm (24i) and the auxiliary exhaust rocker arm (24e). A common main rocker shaft (32) for supporting the main intake rocker arm (23i) and the main exhaust rocker arm (23e) to be connected to one side of the cylinder axis (Y) is the auxiliary intake rocker shaft (33i) and the auxiliary exhaust rocker shaft. An engine characterized by being arranged at a right angle to (33e).

請求項３又は４記載のエンジンにおいて，
前記吸気弁（１９ｉ，１９ｉ）及び排気弁（１９ｅ，１９ｅ）を支持するシリンダヘッド（４）に，前記吸気弁（１９ｉ，１９ｉ）及び排気弁（１９ｅ，１９ｅ）の弁軸間を通る主通風路（４１）と，この主通風路（４１）に連通して前記一対の排気弁（１９ｅ，１９ｅ）間を抜ける副通風路（４３）とを形成したことを特徴とするエンジン。
The engine according to claim 3 or 4,
Main ventilation passing between the valve shafts of the intake valve (19i, 19i) and the exhaust valve (19e, 19e) through the cylinder head (4) supporting the intake valve (19i, 19i) and the exhaust valve (19e, 19e). An engine comprising a passage (41) and a sub-ventilation passage (43) communicating with the main ventilation passage (41) and passing between the pair of exhaust valves (19e, 19e).