JPH02259206A - Multiple valve type four cycle engine - Google Patents

Abstract

PURPOSE:To improve degree of freedom, in a device in the caption in which four intake valves and a plurality of exhaust valves are arranged so that they surround an ignition plug at the center of a combustion chamber, by opening and closing the two inner side intake valves and the two outer side intake valves which adjoin each other through two cam shafts for intake. CONSTITUTION:In a multiple valve type four cycle engine in which four intake valves 24 (24a to 24d) and two exhaust valves 26 (26a, 26b) are arranged at almost equal intervals so that they surround an ignition plug 20 installed in the neighborhood of the center of a combustion chamber 18, cam shaft chambers 28a and 28b are formed between a cam case 12 and each of cam covers 14a and 14d. Of the cam shaft chambers 28a and 28b, two cam shafts 30a and 30b are rotatably supported in the cam shaft chamber 28a on the intake side and a cam shaft 30c in the cam shaft chamber 28b on the exhaust side respectively. And of the cam shafts 30a and 30b on the intake side, the intake valves 24a and 24d on the outer side are opened and closed by the cam shaft 30a on the side of the ignition plug 20 and the intake valves 24b and 24c on the inner side and adjoin each other are opened and closed by the cam shaft 30b.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、４個の吸気弁と複数の排気弁とを中央付近の
点火栓を囲むように配設した多弁式４サイクルエンジン
に関するものである。Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a multi-valve four-stroke engine in which four intake valves and a plurality of exhaust valves are arranged surrounding a spark plug near the center. be.

（発明の背景） ４サイクルエンジンにおいては、吸・排気弁の数を増や
すことにより体積効率の向上を図り、エンジン出力を増
大させることが可能である。そこで４個の吸気弁と２個
の排気弁とを設けることが考えられる。しかしこの場合
においても、点火栓はその着火部が燃焼室中央付近に臨
むようにするのが、良好な燃焼のために望ましい。一方
吸・排気弁の数が増えると、これらの弁を開閉するため
の動弁機構が複雑になり、点火栓を中央に配置しつつ無
理なく多眼・排気弁を配置することが非常に困難になる
。そこで４個の吸気弁を平行に配設し、これら吸気弁の
弁軸上端を１つのバルブリフタに当接させ、この１つの
バルブリフタを１本のカム軸に設けた複数のカムに摺接
させて、各吸気弁を同時に開閉する構造が同一出願人に
より提案された（例えば特開昭５６−１４１４３号）。(Background of the Invention) In a four-stroke engine, it is possible to improve volumetric efficiency and increase engine output by increasing the number of intake and exhaust valves. Therefore, it is conceivable to provide four intake valves and two exhaust valves. However, even in this case, it is desirable for the ignition part of the spark plug to face near the center of the combustion chamber for good combustion. On the other hand, as the number of intake and exhaust valves increases, the valve mechanism for opening and closing these valves becomes complex, making it extremely difficult to arrange multi-lens and exhaust valves while keeping the ignition plug in the center. become. Therefore, four intake valves are arranged in parallel, the upper ends of the valve shafts of these intake valves are brought into contact with one valve lifter, and this one valve lifter is brought into sliding contact with multiple cams provided on one camshaft. , a structure in which each intake valve is opened and closed simultaneously was proposed by the same applicant (for example, Japanese Patent Laid-Open No. 14143/1983).

しかしこの場合には各吸気弁の弁ばねが近接し弁配置の
自由度が減少するという問題があった。また各吸気弁は
平行なので、燃焼室形状の設計自由度も少ないという問
題もあった。However, in this case, there is a problem in that the valve springs of each intake valve are close to each other, reducing the degree of freedom in valve arrangement. Furthermore, since each intake valve is parallel, there is also a problem that there is little freedom in designing the shape of the combustion chamber.

（発明の目的） 本発明はこのような事情に鑑みなされたものであり、点
火栓を囲むように４個の吸気弁と複数の排気弁とを配設
する場合に、各吸気弁の配置自由度を増やし、また燃焼
室形状の設計自由度を増やして望ましい燃焼室形状とす
ることを可能にする多弁式４サイクルエンジンを提供す
ることを目的とする。(Object of the Invention) The present invention has been made in view of the above circumstances, and it is possible to freely arrange each intake valve when four intake valves and a plurality of exhaust valves are arranged surrounding a spark plug. It is an object of the present invention to provide a multi-valve type four-stroke engine that can increase the combustion chamber shape and increase the degree of freedom in designing the combustion chamber shape, thereby making it possible to obtain a desired combustion chamber shape.

（発明の構成） 本発明によればこの目的は、燃焼室の中央付近に点火栓
の着火部が臨み、この点火栓を囲むように４個の吸気弁
と複数の排気弁とを配設した多弁式４サイクルエンジン
において、点火栓の一側に排気用カム軸を、また点火栓
の他側に２本の吸気用カム軸を互いに平行に配設し、前
記各吸気用カム軸により隣接する２個の内側の吸気弁お
よび外側の２個の吸気弁をそれぞれ開閉することを特徴
とする多弁式４サイクルエンジンにより達成される。(Structure of the Invention) According to the present invention, this object is achieved by arranging the ignition part of the ignition plug near the center of the combustion chamber, and arranging four intake valves and a plurality of exhaust valves to surround the ignition plug. In a multi-valve four-stroke engine, an exhaust camshaft is disposed on one side of the ignition plug, and two intake camshafts are disposed parallel to each other on the other side of the ignition plug, and the intake camshafts are adjacent to each other. This is achieved by a multi-valve four-stroke engine characterized by opening and closing two inner intake valves and two outer intake valves, respectively.

（実施例） 第１図は本発明の一実施例である直列４気筒エンジンの
側断面図、第２図はカム軸配置を示す平面図、第３図は
弁配置を示す平面図である。なお第１図は第３図におけ
るＩ−Ｉ線断面に対応する。(Embodiment) FIG. 1 is a side sectional view of an in-line four-cylinder engine according to an embodiment of the present invention, FIG. 2 is a plan view showing the camshaft arrangement, and FIG. 3 is a plan view showing the valve arrangement. Note that FIG. 1 corresponds to the cross section taken along line II in FIG. 3.

第１図において符号１０はシリンダヘッド、１２はカム
ケース、１４　（１４ａ、１４ｂ）はカムカバーである
。シリンダヘッド１０の下にはシリンダボデーがあるが
図にはシリンダ内壁面１６のみが示されている。シリン
ダヘッド１０には第１．２図に示すように燃焼室１８の
中央付近にほぼ垂直に臨む１本の点火栓２０が取付けら
れ、この点火柱２０はカムケース１２に設けた点火栓着
脱孔２２（第３図）から上方へ着脱可能となっている。In FIG. 1, reference numeral 10 is a cylinder head, 12 is a cam case, and 14 (14a, 14b) is a cam cover. Although there is a cylinder body under the cylinder head 10, only the cylinder inner wall surface 16 is shown in the figure. As shown in FIG. 1.2, one spark plug 20 is attached to the cylinder head 10 and faces almost vertically near the center of the combustion chamber 18. It can be attached and detached from above (Fig. 3).

２４（２４ａ−ｄ）は４本の吸気弁、また２６（２６ａ
＝ｂ）は２本の排気弁である。これら吸・排気弁２４．
２６は点火栓２０を囲むようにほぼ等間隔に配置されて
いる。吸気弁２４ａ−ｄは第１図に示すように点火栓２
０に対して左側に位置しかつ左側に傾き、また両排気弁
２６は点火栓２０に対して右側に位置しかつ右側に傾い
ている。第１．２図に示すように、側面から見て点火栓
２０から遠くなるように左側へ傾いた互いに隣接する内
側の２つの吸気弁２４ｂ、ｃは、これらの吸気弁２４ｂ
、ｃを挟む外側の２つの吸気弁２４ａ、ｄよりも左側へ
強く傾いている。24 (24a-d) are four intake valves, and 26 (26a-d) are four intake valves.
=b) are two exhaust valves. These intake/exhaust valves 24.
26 are arranged at approximately equal intervals so as to surround the spark plug 20. The intake valves 24a-d are connected to the spark plug 2 as shown in FIG.
0 and is tilted to the left, and both exhaust valves 26 are located to the right of the spark plug 20 and tilted to the right. As shown in FIG. 1.2, two adjacent inner intake valves 24b and 24c tilted to the left so as to be far from the ignition plug 20 when viewed from the side.
, c are more strongly tilted to the left than the two outer intake valves 24a and 24d.

カムケース１２と両カムカバー１４との間にはカム軸室
２８　（２８ａ、２８ｂ）が形成され、これらカムケー
ス１２とカムカバー１４の台面間には３本のカム軸３０
　（３０ａ、３０ｂ、３０ｃ）が平行に配設されている
。すなわち、吸気側のカム軸３０ａ、３０ｂは、カムケ
ース１２と、吸気側カム軸重り８ａ内の所定位置に取付
けられたカムキャップ３２　（３２ａ、３２ｂのみ図示
、第３図）との間に保持されている。排気側のカム軸３
０ｃは、カムケース１２と、排気側カム軸重２８ｂ内の
所定位置に取付けられたカムキャップ３４　（３４ａ、
３４ｂのみ図示）との間に保持されている。吸気側の２
本のカム軸３０ａ、３０ｂのうち点火柱２０側のカム軸
３０ａは、外側の吸気弁２４ａ、２４ｄをバルブリフタ
３６ａ、３６ｄを介して開閉する。点火栓２０から遠い
側のカム軸３０ｂは、内側の互いに隣接する２つの吸気
弁２４ｂ、２４ｃをバルブリフタ３６ｂ、３６ｃを介し
て開閉する。また排気側のカム軸３０ｃは、２つの排気
弁２６をバルブリフタ３８ａ、３８ｂを介して開閉する
。A camshaft chamber 28 (28a, 28b) is formed between the cam case 12 and both cam covers 14, and three camshafts 30 are formed between the cam case 12 and the base of the cam cover 14.
(30a, 30b, 30c) are arranged in parallel. That is, the intake-side camshafts 30a and 30b are held between the cam case 12 and a cam cap 32 (only 32a and 32b are shown in FIG. 3) attached to a predetermined position within the intake-side camshaft weight 8a. ing. Exhaust side camshaft 3
0c is a cam cap 34 (34a,
(only 34b is shown). 2 on the intake side
Of the main camshafts 30a and 30b, the camshaft 30a on the ignition column 20 side opens and closes the outer intake valves 24a and 24d via valve lifters 36a and 36d. The camshaft 30b on the side far from the spark plug 20 opens and closes two mutually adjacent inner intake valves 24b and 24c via valve lifters 36b and 36c. Further, the exhaust side camshaft 30c opens and closes the two exhaust valves 26 via valve lifters 38a and 38b.

吸気側のカム軸３０ａ、３０ｂの軸端には互いに噛合す
る歯車４０ａ、４０ｂが固定され（第３図）、これらカ
ム軸３０ａ、３０ｂは同期して互いに逆方向に周速で回
転する。なお吸気側のカム軸３０ｂは左右に分割される
一方、他方のカム軸３０ａの中央と排気側カム軸３０ｃ
の中央とにはスプロケット４２ａ、４２ｃが設けられ、
これらスプロケット４２ａ、４２ｃと、クランク軸（図
示せず）とにはタイミングチェーン４４（第２図）が巻
き掛けられ、各カム軸３０はクランク軸の半分の速度で
回転される。また第１．２図で４２は吸気通路、４４は
排気通路である。Gears 40a and 40b that mesh with each other are fixed to the shaft ends of the intake side camshafts 30a and 30b (FIG. 3), and these camshafts 30a and 30b rotate in synchronization with each other at circumferential speeds in opposite directions. Note that the intake side camshaft 30b is divided into left and right parts, while the center of the other camshaft 30a and the exhaust side camshaft 30c
Sprockets 42a and 42c are provided at the center of the
A timing chain 44 (FIG. 2) is wound around these sprockets 42a, 42c and a crankshaft (not shown), and each camshaft 30 is rotated at half the speed of the crankshaft. Further, in Fig. 1.2, 42 is an intake passage, and 44 is an exhaust passage.

この実施例では多眼・排気弁２４．２６は各カム軸３０
に直交する平面上に位置するが、一部または全部の吸気
弁２４または排気弁２６をこの平面に対し傾けて配置し
てもよい。例えば外側の吸気弁２４ａ、２４ｄや内側の
吸気弁２４ｂ、２４Ｃをその弁軸上端が互いに離れるよ
うに傾けてもよい。In this embodiment, the multi-lens exhaust valve 24,26 is connected to each camshaft 30.
However, some or all of the intake valves 24 or exhaust valves 26 may be arranged at an angle with respect to this plane. For example, the outer intake valves 24a, 24d and the inner intake valves 24b, 24C may be tilted so that the upper ends of their valve shafts are separated from each other.

この実施例によれば外側の吸気弁２４ａ、２４ｄを内側
の吸気弁２４ｂ、２４ｃよりも垂直に近付けたので第３
図に斜線で示すようにスキッシュ領域８を大きく確保で
きる効果がある。According to this embodiment, the outer intake valves 24a, 24d are closer to the vertical position than the inner intake valves 24b, 24c.
As shown by diagonal lines in the figure, there is an effect that a large squish area 8 can be ensured.

第４図は他の実施例の側面図、第５図はそのカム軸配置
を示す平面図、第６図は弁配置を示す平面図である。FIG. 4 is a side view of another embodiment, FIG. 5 is a plan view showing its camshaft arrangement, and FIG. 6 is a plan view showing its valve arrangement.

この実施例では内側の吸気弁１２４ｂ、１２４Ｃを外側
の吸気弁１２４ａ、１２４ｄよりも垂直に近く配置し、
第４図に示すように側面から見て両者を交差させたもの
である。従って点火栓１２０に近い内側のカム軸１３０
ａは、内側の吸気弁１２４ａ、１２４ｄを開閉し、外側
のカム軸１３０ｂは外側の吸気弁１２４ｂ、１２４ｃを
開閉する。なお点火栓１２０は２本並設され、その着脱
孔１２２も２つ設けられている（第５図）。In this embodiment, the inner intake valves 124b, 124C are arranged closer vertically than the outer intake valves 124a, 124d,
As shown in FIG. 4, the two are crossed when viewed from the side. Therefore, the inner camshaft 130 near the spark plug 120
a opens and closes the inner intake valves 124a and 124d, and the outer camshaft 130b opens and closes the outer intake valves 124b and 124c. Note that two spark plugs 120 are arranged in parallel, and two attachment/detachment holes 122 are also provided (FIG. 5).

１３２ａ、ｂ、ｃはカムキャップ、１３６ａ−ｄはパル
プリフタ、１４０ａ、ｂは歯車である。132a, b, c are cam caps, 136a-d are pulp lifters, and 140a, b are gears.

また排気系は前記第１〜３図の実施例と変わらないので
その説明は繰り返さない。Further, since the exhaust system is the same as the embodiment shown in FIGS. 1 to 3, its description will not be repeated.

以上の各実施例はバルブリフタにより吸・排気弁を直接
開閉する直動式の動弁機構に本発明を適用したものであ
るが、本発明はロッカアームにより開閉するものにも適
用できる。In each of the embodiments described above, the present invention is applied to a direct-acting type valve operating mechanism in which intake and exhaust valves are directly opened and closed by a valve lifter, but the present invention can also be applied to a mechanism in which the intake and exhaust valves are opened and closed by a rocker arm.

また吸気側のカム軸３０ａ、ｂ、１３０ａ、ｂは各吸気
弁２４　ａ＝ｄ、　　１２４　ａ−ｄを同位相で開閉す
るように構成するものだけでなく、位相を僅かに変化さ
せるようにしてもよい。例えば、方のカム軸による弁開
閉タイミングを他方の弁開閉タイミングに対して進めま
たは遅らせたり、開弁角度範囲を変えたりすることによ
り、燃焼室でのスワール（吸入渦流）を制御することが
可能である。In addition, the camshafts 30a, b, 130a, b on the intake side are not only configured to open and close the intake valves 24a=d, 124a-d in the same phase, but also to slightly change the phase. Good too. For example, it is possible to control the swirl in the combustion chamber by advancing or retarding the opening and closing timing of one valve relative to the other, or by changing the valve opening angle range. It is.

（発明の効果） 本発明は以上のように、平行な３本のカム軸のうち、２
本のカム軸を用いて４個の吸気弁をそれぞれ２個づつ開
閉するものであるから、隣り合う吸気弁の弁ばね間隔を
離して配置することが可能であり、弁配置の自由度が増
大する。また多弁の角度設定の自由度が増えるから燃焼
室形状を理想的なものにすることが可能となる。(Effects of the Invention) As described above, the present invention provides two out of three parallel cam shafts.
Since the camshaft is used to open and close two of each of the four intake valves, it is possible to arrange the valve springs of adjacent intake valves apart, increasing the degree of freedom in valve arrangement. do. Furthermore, since the degree of freedom in setting the angle of the multiple valves increases, it becomes possible to make the combustion chamber shape ideal.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の一実施例の側断面図、第２図はカム軸
配置を示す平面図、第３図は弁配置を示す平面図である
。また第４図は他の実施例の側面図、第５図はそのカム
軸配置を示す平面図、第６図は弁配置を示す平面図であ
る。 ２０．１２０・・・点火栓、 ２４．１２４・・・吸気弁、　２６・・・排気弁、３０
．１３０・・・カム軸。 特許出願人　ヤマハ発動機株式会社FIG. 1 is a side sectional view of an embodiment of the present invention, FIG. 2 is a plan view showing the camshaft arrangement, and FIG. 3 is a plan view showing the valve arrangement. 4 is a side view of another embodiment, FIG. 5 is a plan view showing the arrangement of the camshaft, and FIG. 6 is a plan view showing the arrangement of the valves. 20.120...Spark plug, 24.124...Intake valve, 26...Exhaust valve, 30
．． 130...Camshaft. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

【特許請求の範囲】 燃焼室の中央付近に点火栓の着火部が臨み、この点火栓
を囲むように４個の吸気弁と複数の排気弁とを配設した
多弁式４サイクルエンジンにおいて、 点火栓の一側に排気用カム軸を、また点火栓の他側に２
本の吸気用カム軸を互いに平行に配設し、前記各吸気用
カム軸により隣接する２個の内側の吸気弁および外側の
２個の吸気弁をそれぞれ開閉することを特徴とする多弁
式４サイクルエンジン。[Claims] In a multi-valve four-stroke engine in which the ignition part of the ignition plug faces near the center of the combustion chamber, and four intake valves and a plurality of exhaust valves are arranged to surround the ignition plug, An exhaust camshaft is installed on one side of the spark plug, and two on the other side of the spark plug.
Multi-valve type 4, characterized in that two intake camshafts are arranged parallel to each other, and each intake camshaft opens and closes two adjacent inner intake valves and two outer intake valves, respectively. cycle engine.