JPH0565811A - Structure of combustion chamber for two-cycle internal combustion engine - Google Patents
Structure of combustion chamber for two-cycle internal combustion engineInfo
- Publication number
- JPH0565811A JPH0565811A JP22715091A JP22715091A JPH0565811A JP H0565811 A JPH0565811 A JP H0565811A JP 22715091 A JP22715091 A JP 22715091A JP 22715091 A JP22715091 A JP 22715091A JP H0565811 A JPH0565811 A JP H0565811A
- Authority
- JP
- Japan
- Prior art keywords
- valve
- exhaust valve
- exhaust
- valves
- opening
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
- F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
- F02F1/4214—Shape or arrangement of intake or exhaust channels in cylinder heads specially adapted for four or more valves per cylinder
-
- 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
- F02B75/00—Other engines
- F02B75/02—Engines characterised by their cycles, e.g. six-stroke
- F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
- F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は２サイクル内燃機関の燃
焼室構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber structure for a two-cycle internal combustion engine.
【０００２】[0002]
【従来の技術】シリンダヘッド内壁面の一側に一対の給
気弁を隣接配置すると共にシリンダヘッド内壁面の他側
に一対の排気弁を隣接配置し、排気弁の弁径を大きくし
て給気弁の弁径とほぼ等しく形成した２サイクル内燃機
関の燃焼室構造が公知である（特開平２-64221号公報参
照）。この２サイクル内燃機関では互いに隣接配置され
た一対の排気弁の周縁部間の距離が最も近い近接領域に
おいて排気弁周縁部とその弁座間に形成される排気弁の
開口が互いに対面している。更に、一対の排気弁の弁軸
が互いに平行に配置されており、従って上述の近接領域
に形成される各排気弁開口が互いに重なるように投影し
た各排気弁開口の投影面において各排気弁開口が完全に
重なるように各排気弁が配置されている。2. Description of the Related Art A pair of air supply valves are arranged adjacently on one side of an inner wall surface of a cylinder head, and a pair of exhaust valves are arranged adjacently on the other side of the inner wall surface of the cylinder head to increase the valve diameter of the exhaust valve. A combustion chamber structure of a two-cycle internal combustion engine, which is formed to have a diameter substantially equal to that of the air valve, is known (see Japanese Patent Laid-Open No. 2-64221). In this two-cycle internal combustion engine, the exhaust valve openings formed between the exhaust valve peripheral edge portion and its valve seat face each other in the proximity region where the distance between the peripheral edge portions of the pair of exhaust valves arranged adjacent to each other is the shortest. Further, the valve axes of the pair of exhaust valves are arranged in parallel with each other, and therefore, the exhaust valve openings are formed on the projection plane of the exhaust valve openings projected so that the exhaust valve openings formed in the above-mentioned adjacent region overlap each other. The exhaust valves are arranged so that they completely overlap each other.
【０００３】２サイクル内燃機関では排気弁の開弁開始
直後、即ち排気弁のリフト量が小さいときに、燃焼室内
の高圧既燃ガスが排気弁の開口を介して急激に排出さ
れ、所謂ブローダウンを生ずる。このブローダウン作用
が強力なほど燃焼室内の既燃ガスが速やかに排出されて
燃焼室内の圧力が速やかに低下され、その結果燃焼室内
への新気の流入が促進される。上述の２サイクル内燃機
関では排気弁の弁径を大きくして給気弁の弁径とほぼ等
しく形成しているので、排気弁の開弁開始直後における
排気弁の開口面積が大きくなり、その結果強力なブロー
ダウン作用が得られ、斯くして良好な掃気効率が確保さ
れるようにしている。In a two-cycle internal combustion engine, immediately after the opening of the exhaust valve is started, that is, when the lift amount of the exhaust valve is small, the high-pressure burned gas in the combustion chamber is rapidly discharged through the opening of the exhaust valve, so-called blowdown. Cause The stronger the blowdown action is, the more quickly the burnt gas in the combustion chamber is discharged and the pressure in the combustion chamber is promptly lowered, and as a result, the inflow of fresh air into the combustion chamber is promoted. In the above-mentioned two-cycle internal combustion engine, the valve diameter of the exhaust valve is made large so as to be almost equal to the valve diameter of the intake valve, so the opening area of the exhaust valve becomes large immediately after the opening of the exhaust valve starts, and as a result, A strong blowdown action is obtained, thus ensuring good scavenging efficiency.
【０００４】[0004]
【発明が解決しようとする課題】ところで、排気弁のリ
フト量が小さいブローダウン期間には燃焼室内の既燃ガ
スが、排気弁の開口周りに位置する円板状の燃焼室領
域、即ちカーテン領域を介して排気弁開口からカーテン
状に流出される。このカーテン領域の直径は排気弁開口
の直径よりもやや大きく、また排気弁のリフト量が小さ
いのでカーテン領域の厚みは薄い。By the way, during the blowdown period in which the lift amount of the exhaust valve is small, the burnt gas in the combustion chamber is a disc-shaped combustion chamber region located around the opening of the exhaust valve, that is, a curtain region. Through the exhaust valve opening in a curtain shape. The diameter of this curtain region is slightly larger than the diameter of the exhaust valve opening, and the lift amount of the exhaust valve is small, so the curtain region is thin.
【０００５】しかしながら、上述の２サイクル内燃機関
の燃焼室構造では、互いに隣接配置された排気弁間の距
離が最も近い近接領域において互いに対面している各排
気弁の開口部分が、上述の投影面上において完全に重な
っている。このように互いに対面している各排気弁の開
口部分が投影面上において完全に重なるように各排気弁
が配置されると共にカーテン領域の直径が排気弁開口の
直径よりもやや大きいので、ブローダウン期間において
近接領域内に位置する各排気弁のカーテン領域の多くの
部分が互いに重なり合ってしまうことになる。この各排
気弁のカーテン領域の重なり部分内を通過する既燃ガス
の一部は一方の排気弁の開口から排出され、残りの部分
は他方の排気弁の開口から排出される。しかしながら、
このカーテン領域の重なり部分内を通過する既燃ガスは
本来どちらか一方の排気弁の開口から全量排出されうる
ものである。従って、排気弁の弁径を大きく形成して排
気弁の開口面積を大きくしていても、このようにカーテ
ン領域が重なる分だけ排気弁の開口面積が無駄になって
しまう。斯くしてブローダウン期間における既燃ガスの
排出量が減少してブローダウン作用が弱まり、その結果
掃気効率が低下してしまうという問題が生ずる。However, in the above-mentioned combustion chamber structure of the two-cycle internal combustion engine, the opening portions of the exhaust valves facing each other in the proximity region where the distance between the exhaust valves arranged adjacent to each other is the shortest, the above-mentioned projection surface. It completely overlaps above. In this way, the exhaust valves are arranged so that the opening portions of the exhaust valves facing each other are completely overlapped on the projection surface, and the diameter of the curtain region is slightly larger than the diameter of the exhaust valve opening, so blowdown Many parts of the curtain region of each exhaust valve located in the proximity region will overlap each other for a period of time. A part of the burnt gas passing through the overlapping portion of the curtain regions of the exhaust valves is discharged from the opening of one exhaust valve, and the remaining portion is discharged from the opening of the other exhaust valve. However,
The burned gas passing through the overlapping portion of the curtain region can be completely discharged from the opening of either one of the exhaust valves. Therefore, even when the valve diameter of the exhaust valve is increased to increase the opening area of the exhaust valve, the opening area of the exhaust valve is wasted by the overlap of the curtain regions. Thus, the amount of burned gas discharged during the blowdown period is reduced, the blowdown action is weakened, and as a result, the scavenging efficiency is reduced.
【０００６】[0006]
【課題を解決するための手段】上記問題点を解決するた
めに本発明によれば、互いに隣接配置された排気弁間の
距離が最も近い領域において排気弁とその弁座間に形成
される排気弁の開口が互いに対面している２サイクル内
燃機関の燃焼室構造において、上述の領域に形成される
各排気弁開口が互いに重なるように投影した各排気弁開
口の投影面において各排気弁開口が互いに斜めに交差し
て延びるように各排気弁を配置している。In order to solve the above problems, according to the present invention, an exhaust valve formed between an exhaust valve and its valve seat in a region where the distance between the exhaust valves arranged adjacent to each other is the shortest. In the combustion chamber structure of the two-cycle internal combustion engine in which the exhaust valve openings face each other, the exhaust valve openings are projected in such a manner that the exhaust valve openings formed in the above-mentioned region overlap each other. The exhaust valves are arranged so as to extend diagonally.
【０００７】[0007]
【作用】互いに隣接配置された排気弁間の距離が最も近
い領域に形成される各排気弁開口が互いに重なるように
投影した各排気弁開口の投影面において各排気弁開口が
互いに斜めに交差して延びているので、排気弁の開弁期
間初期において互いに隣接配置された各排気弁の開口周
りに位置する燃焼室領域、即ちカーテン領域の重なりが
減少する。斯くして排気弁の開弁期間初期に各排気弁の
カーテン領域内を通って各排気弁開口から排出される既
燃ガス量が増大する。In the projection plane of the exhaust valve openings formed so that the exhaust valve openings formed in the region where the distances between the exhaust valves arranged adjacent to each other are closest to each other overlap each other, the exhaust valve openings obliquely intersect each other. Since the exhaust valve extends, the overlap of the combustion chamber regions, that is, the curtain regions, located around the openings of the exhaust valves arranged adjacent to each other is reduced in the early stage of opening the exhaust valve. Thus, the amount of burnt gas discharged from each exhaust valve opening through the curtain region of each exhaust valve at the beginning of the opening period of the exhaust valve increases.
【０００８】[0008]
【実施例】図１から図９に本発明を２気筒２サイクル内
燃機関に適用した場合を示す。図１から図４にこの２気
筒２サイクル内燃機関の一つの気筒の燃焼室構造を示
す。図１から図４を参照すると、１はシリンダブロッ
ク、２はシリンダブロック１内に固定されたシリンダラ
イナ、４はシリンダライナ２内で往復動するピストン、
６はシリンダブロック１上に固定されたシリンダヘッ
ド、８はシリンダヘッド６の内壁面６ａとピストン４の
頂面間に形成された燃焼室を夫々示す。シリンダヘッド
内壁面６ａ上には窪み部１０が形成され、この窪み部１
０の底壁面をなすシリンダヘッド内壁面部分６ｂ上に一
対の給気弁１２が配置される。一方、窪み部１０を除く
シリンダヘッド内壁面部分６ｃは傾斜したほぼ平坦をな
し、このシリンダヘッド内壁面部分６ｃ上に一対の第１
排気弁１４ａと１個の第２排気弁１４ｂとが配置され
る。1 to 9 show a case where the present invention is applied to a two-cylinder two-cycle internal combustion engine. 1 to 4 show the structure of the combustion chamber of one cylinder of this two-cylinder two-cycle internal combustion engine. 1 to 4, 1 is a cylinder block, 2 is a cylinder liner fixed in the cylinder block 1, 4 is a piston that reciprocates in the cylinder liner 2,
Reference numeral 6 indicates a cylinder head fixed on the cylinder block 1, and 8 indicates a combustion chamber formed between the inner wall surface 6a of the cylinder head 6 and the top surface of the piston 4. A hollow portion 10 is formed on the inner wall surface 6a of the cylinder head.
A pair of air supply valves 12 are arranged on the cylinder head inner wall surface portion 6b forming the bottom wall surface of 0. On the other hand, the cylinder head inner wall surface portion 6c excluding the hollow portion 10 is inclined and substantially flat, and a pair of first wall surfaces 6c are formed on the cylinder head inner wall surface portion 6c.
An exhaust valve 14a and one second exhaust valve 14b are arranged.
【０００９】図２に示されるように第２排気弁１４ｂは
一対の第１排気弁１４ａの間であって給気弁１２と反対
側のシリンダヘッド内壁面６ａの周辺部に設けられてお
り、従って第２排気弁１４ｂは第１排気弁１４ａに比べ
て給気弁１２から離れた位置に配置されている。また、
互いに隣接配置された第２排気弁１４ｂと各第１排気弁
１４ａとは、第２排気弁１４ｂの周縁部と第１排気弁１
４ａの周縁部との間の距離が最も近い近接領域において
排気弁１４ｂ，１４ａとその弁座１６間に形成される開
口が互いに対面している。図１から図３に示されるよう
に第２排気弁１４ｂの弁軸はシリンダボア軸線と第２排
気弁１４ｂのかさ部中心とを含む平面Ｋ−Ｋ上に配置さ
れている。一方、一対の第１排気弁１４ａの弁軸は、図
１および図４に示されるように夫々平面Ｋ−Ｋに対して
平行な平面上に配置されている。図１、図３および図４
からわかるように、シリンダボア軸線方向に対する一対
の第１排気弁１４ａの弁軸の傾斜角は等しく形成されて
おり、一方第２排気弁１４ｂの弁軸の傾斜角は第１排気
弁１４ａの弁軸の傾斜角よりも小さくなっている。従っ
て、第１排気弁１４ａと第２排気弁１４ｂ間の距離が最
も近い近接領域に形成される各排気弁１４ａ，１４ｂの
開口が互いに重なるように投影した投影面において、即
ち図２において矢印Ｖまたは矢印Ａの方向に投影した投
影面において、各排気弁１４ａ，１４ｂの開口は互いに
斜めに交差して延びている（図５参照）。また図３、図
４および図９に示されるように一対の第１排気弁１４ａ
は一対の第１排気弁駆動カム１８ａによって開閉制御さ
れ、一方第２排気弁１４ｂは第２排気弁駆動カム１８ｂ
によって開閉制御される。図９に示されるようにこれら
の排気弁駆動カム１８ａ，１８ｂは１本の排気弁用カム
シャフト２０上に形成されている。As shown in FIG. 2, the second exhaust valve 14b is provided between the pair of first exhaust valves 14a and on the periphery of the cylinder head inner wall surface 6a opposite to the air supply valve 12, Therefore, the second exhaust valve 14b is located farther from the air supply valve 12 than the first exhaust valve 14a. Also,
The second exhaust valve 14b and each first exhaust valve 14a that are arranged adjacent to each other include a peripheral portion of the second exhaust valve 14b and the first exhaust valve 1
The openings formed between the exhaust valves 14b and 14a and their valve seats 16 face each other in the proximity region where the distance from the peripheral edge of 4a is the shortest. As shown in FIGS. 1 to 3, the valve shaft of the second exhaust valve 14b is arranged on a plane KK including the cylinder bore axis and the center of the bulkhead of the second exhaust valve 14b. On the other hand, the valve shafts of the pair of first exhaust valves 14a are arranged on planes parallel to the plane KK, respectively, as shown in FIGS. 1 and 4. 1, 3 and 4
As can be seen from the above, the inclination angles of the valve shafts of the pair of first exhaust valves 14a with respect to the cylinder bore axis direction are formed to be equal, while the inclination angle of the valve shaft of the second exhaust valve 14b is equal to the valve shaft of the first exhaust valve 14a. It is smaller than the inclination angle of. Therefore, on the projection plane projected so that the openings of the exhaust valves 14a and 14b formed in the adjacent region where the distance between the first exhaust valve 14a and the second exhaust valve 14b is the shortest, that is, the arrow V in FIG. Alternatively, on the projection plane projected in the direction of arrow A, the openings of the exhaust valves 14a and 14b extend obliquely to each other (see FIG. 5). Further, as shown in FIGS. 3, 4 and 9, a pair of first exhaust valves 14a
Is controlled by a pair of first exhaust valve drive cams 18a, while the second exhaust valve 14b is controlled by the second exhaust valve drive cams 18b.
The opening and closing is controlled by. As shown in FIG. 9, these exhaust valve drive cams 18a and 18b are formed on one exhaust valve camshaft 20.
【００１０】一方、図１および図４に示されるように一
対の給気弁１２の弁軸は夫々上述の平面Ｋ−Ｋに対して
平行な平面上に配置される。図１からわかるようにシリ
ンダボア軸線方向に対する一対の給気弁１２の弁軸の傾
斜角は等しくなっている。また図４および図９に示され
るように一対の給気弁１２は一対の給気弁駆動カム２２
によって開閉制御され、これらの給気弁駆動カム２２は
１本の給気弁用カムシャフト２４上に形成されている。On the other hand, as shown in FIGS. 1 and 4, the valve shafts of the pair of air supply valves 12 are arranged on planes parallel to the plane K-K. As can be seen from FIG. 1, the inclination angles of the valve shafts of the pair of air supply valves 12 with respect to the cylinder bore axis direction are equal. Further, as shown in FIG. 4 and FIG. 9, the pair of air supply valves 12 is a pair of air supply valve drive cams 22.
The air supply valve drive cam 22 is formed on a single air supply valve cam shaft 24 by being controlled to be opened and closed by.
【００１１】図２に示されるようにシリンダヘッド内壁
面部分６ｂとシリンダヘッド内壁面部分６ｃは窪み部１
０の周壁２６を介して互いに接続されており、この窪み
部周壁２６は一対の給気弁１２と第１排気弁１４ａ、第
２排気弁１４ｂとの間においてシリンダヘッド内壁面６
ａの一方の周縁部から他方の周縁部まで延びている。こ
の窪み部周壁２６は給気弁１２の周縁部に極めて近接配
置されかつ給気弁１２の周縁部に沿って円弧状に延びる
一対のマスク壁２６ａと、給気弁１２間に位置する新気
ガイド壁２６ｂと、シリンダヘッド内壁面６ａの周壁と
給気弁１２間に位置する一対の新気ガイド壁２６ｃとに
より構成される。各マスク壁２６ａは最大リフト位置に
ある給気弁１２よりも下方まで燃焼室８に向けて延びて
おり、従って排気弁１４ａ，１４ｂ側に位置する給気弁
１２周縁部と弁座２８間の開口は給気弁１２の開弁期間
全体に亙ってマスク壁２６ａにより閉鎖されることにな
る。また、各新気ガイド壁２６ｂ，２６ｃはほぼ同一平
面内に位置しており、更にこれらの新気ガイド壁２６
ｂ，２６ｃは両給気弁１２の中心を結ぶ線に対してほぼ
平行に延びている。点火栓３０はシリンダヘッド内壁面
６ａの中心に位置するようにシリンダヘッド内壁面部分
６ｃ上に位置されている。一方、第１排気弁１４ａおよ
び第２排気弁１４ｂに対しては排気弁１４ａ，１４ｂと
弁座１６間の開口を覆うマスク壁が設けられておらず、
従って排気弁１４ａ，１４ｂが開弁すると排気弁１４
ａ，１４ｂと弁座１６間に形成される開口はその全体が
燃焼室８内に開口することになる。As shown in FIG. 2, the cylinder head inner wall surface portion 6b and the cylinder head inner wall surface portion 6c have a recessed portion 1.
No. 0 peripheral wall 26 is connected to each other, and the recess peripheral wall 26 is provided between the pair of intake valves 12 and the first exhaust valve 14a and the second exhaust valve 14b.
It extends from one peripheral edge of a to the other peripheral edge. The recessed peripheral wall 26 is disposed very close to the peripheral edge of the air supply valve 12, and a pair of mask walls 26 a extending in an arc shape along the peripheral edge of the air supply valve 12 and fresh air located between the air supply valves 12. The guide wall 26b and a pair of fresh air guide walls 26c located between the peripheral wall of the cylinder head inner wall surface 6a and the air supply valve 12 are provided. Each mask wall 26a extends toward the combustion chamber 8 below the intake valve 12 at the maximum lift position, and therefore, between the peripheral portion of the intake valve 12 located on the exhaust valve 14a, 14b side and the valve seat 28. The opening is closed by the mask wall 26a during the entire opening period of the air supply valve 12. The fresh air guide walls 26b and 26c are located substantially in the same plane.
b and 26c extend substantially parallel to a line connecting the centers of both air supply valves 12. The spark plug 30 is located on the cylinder head inner wall surface portion 6c so as to be located at the center of the cylinder head inner wall surface 6a. On the other hand, for the first exhaust valve 14a and the second exhaust valve 14b, a mask wall that covers the opening between the exhaust valves 14a and 14b and the valve seat 16 is not provided,
Therefore, when the exhaust valves 14a and 14b are opened, the exhaust valve 14
The entire opening formed between the a and 14b and the valve seat 16 opens into the combustion chamber 8.
【００１２】シリンダヘッド６内には各給気弁１２に対
して夫々給気ポート３２が形成され、各排気弁１４ａ，
１４ｂに対して夫々排気ポート３３が形成される。ま
た、各給気弁１２の近傍のシリンダヘッド内壁面６ａの
周縁部には一対の燃料噴射弁、即ち第１燃料噴射弁３５
ａと第２燃料噴射弁３５ｂとが配置され、これらの燃料
噴射弁３５ａ，３５ｂから燃料が燃焼室８内に向けて噴
射される。一方、図１、図３および図４に示されるよう
にピストン４の頂面上には点火栓３０の下方から燃料噴
射弁３５ａ，３５ｂの先端部の下方まで延びる凹部３７
が形成されている。In the cylinder head 6, an air supply port 32 is formed for each air supply valve 12, and each exhaust valve 14a,
An exhaust port 33 is formed for each of 14b. In addition, a pair of fuel injection valves, that is, the first fuel injection valve 35, is provided at the peripheral edge of the cylinder head inner wall surface 6a near each air supply valve 12.
a and the second fuel injection valve 35b are arranged, and the fuel is injected into the combustion chamber 8 from these fuel injection valves 35a and 35b. On the other hand, as shown in FIGS. 1, 3 and 4, on the top surface of the piston 4, a recess 37 extending from below the spark plug 30 to below the tips of the fuel injection valves 35a and 35b.
Are formed.
【００１３】図６に示されるように本実施例では排気弁
１４ａ，１４ｂが給気弁１２よりも先に開弁し、排気弁
１４ａ，１４ｂが給気弁１２よりも先に閉弁する。ま
た、図６においてＩｒは機関低負荷運転時における燃料
噴射時期を示しており、Ｉｍ1 おおびＩｍ2 は機関中負
荷運転時における燃料噴射時期を示しており、Ｉｈ1 お
よびＩｈ2 は機関高負荷運転時における燃料噴射時期を
示している。なお、機関低負荷運転時における燃料噴射
Ｉｒおよび機関中負荷運転時における第２回目の燃料噴
射Ｉｍ2 は第１燃料噴射弁３５ａにより行われ、機関中
負荷運転時における第１回目の燃料噴射Ｉｍ1 は第２燃
料噴射弁３５ｂにより行われ、機関高負荷運転時におけ
る燃料噴射Ｉｈ1 およびＩｈ2 は第１燃料噴射弁３５ａ
および第２燃料噴射弁３５ｂの双方により行われる。As shown in FIG. 6, in this embodiment, the exhaust valves 14a and 14b are opened before the air supply valve 12, and the exhaust valves 14a and 14b are closed before the air supply valve 12. Further, in FIG. 6, Ir indicates the fuel injection timing during engine low load operation, Im 1 and Im 2 indicate fuel injection timing during engine medium load operation, and Ih 1 and Ih 2 indicate engine height. The fuel injection timing at the time of load operation is shown. It should be noted that the fuel injection Ir during the engine low load operation and the second fuel injection Im 2 during the engine medium load operation are performed by the first fuel injection valve 35a, and the first fuel injection Im during the engine medium load operation. 1 is performed by the second fuel injection valve 35b, and the fuel injections Ih 1 and Ih 2 during engine high load operation are performed by the first fuel injection valve 35a.
And the second fuel injection valve 35b.
【００１４】次に、排気弁１４ａ，１４ｂが開弁したと
きのブローダウン作用、および給気弁１２が開弁したと
きの掃気作用について説明する。排気弁１４ａ，１４ｂ
が開弁すると燃焼室８内の既燃ガスが急激に排気ポート
３３内に流出し、所謂ブローダウンを生ずる。その結
果、燃焼室８内の圧力が急激に低下する。本実施例では
３個の排気弁１４ａ，１４ｂが設けられているので２個
あるいは１個の排気弁が設けられている場合に比べて排
気弁の開口面積が増大し、その結果燃焼室８内の既燃ガ
スの排出が促進され、斯くして燃焼室８内の圧力がより
急激に低下する。Next, the blowdown action when the exhaust valves 14a and 14b are opened and the scavenging action when the air supply valve 12 is opened will be described. Exhaust valves 14a, 14b
When the valve is opened, the burnt gas in the combustion chamber 8 suddenly flows into the exhaust port 33, causing so-called blowdown. As a result, the pressure in the combustion chamber 8 drops sharply. In this embodiment, since three exhaust valves 14a and 14b are provided, the opening area of the exhaust valve is increased as compared with the case where two or one exhaust valve is provided, and as a result, the inside of the combustion chamber 8 is increased. The discharge of the burned gas is promoted, and thus the pressure in the combustion chamber 8 drops more rapidly.
【００１５】このようにブローダウンが生ずる期間、即
ち排気弁１４ａ，１４ｂの開弁期間初期において、燃焼
室８内の既燃ガスは各排気弁１４ａ，１４ｂの開口周り
に位置する円板状の燃焼室領域４０ａ，４０ｂ、即ちカ
ーテン領域４０ａ，４０ｂを通って各排気弁１４ａ，１
４ｂの開口からカーテン状に流出する。図２に示される
ようにこのカーテン領域４０ａ，４０ｂの直径は排気弁
１４ａ，１４ｂの開口の直径よりもやや大きく、またブ
ローダウン期間には排気弁１４ａ，１４ｂのリフト量が
小さいのでカーテン領域４０ａ，４０ｂの厚みは薄い。In the period in which the blowdown occurs in this way, that is, in the early stage of the opening period of the exhaust valves 14a, 14b, the burnt gas in the combustion chamber 8 is in the form of a disc located around the openings of the exhaust valves 14a, 14b. Each exhaust valve 14a, 1 passes through the combustion chamber area 40a, 40b, i.e. the curtain area 40a, 40b.
It flows out like a curtain from the opening of 4b. As shown in FIG. 2, the diameters of the curtain regions 40a and 40b are slightly larger than the diameters of the openings of the exhaust valves 14a and 14b, and the lift amount of the exhaust valves 14a and 14b is small during the blowdown period. , 40b is thin.
【００１６】本実施例では排気弁１４ａ，１４ｂの開口
面積ができるだけ大きくなるように排気弁１４ａ，１４
ｂの弁径が大きく形成されているので、図２に示すよう
に互いに隣接配置された第１排気弁１４ａの開口と第２
排気弁１４ｂの開口とが対面している領域において各排
気弁のカーテン領域４０ａ，４０ｂの一部が互いに重な
り合う。In the present embodiment, the exhaust valves 14a, 14b are arranged so that the opening areas of the exhaust valves 14a, 14b are as large as possible.
Since the valve diameter of b is large, the opening of the first exhaust valve 14a and the second exhaust valve 14a which are arranged adjacent to each other as shown in FIG.
In the region where the opening of the exhaust valve 14b faces, the curtain regions 40a and 40b of the exhaust valves partially overlap each other.
【００１７】しかしながら本実施例では上述のように第
１排気弁１４ａの弁軸の傾斜角が第２排気弁１４ｂの弁
軸の傾斜角よりも大きくなっている。従って、互いに対
面する各排気弁１４ａ，１４ｂの開口が互いに重なるよ
うに投影した各排気弁開口の投影面において、即ち図２
において矢印Ｖまたは矢印Ａの方向に投影した投影面に
おいて、各排気弁１４ａ，１４ｂの開口が図５に示され
るように互いに斜めに交差して延びている。従って第１
排気弁１４ａのカーテン領域４０ａと第２排気弁１４ｂ
のカーテン領域４０ｂもこの投影面上において互いに斜
めに交差して延びている。図５において第１排気弁１４
ａのカーテン領域部分４１ａおよび第２排気弁１４ｂの
カーテン領域部分４１ｂは、図２において互いに重なっ
て見えるカーテン領域４０ａ部分およびカーテン領域４
０ｂ部分に対応している。なお、図５ではカーテン領域
部分４１ａ，４１ｂを実際の位置よりも下方にずらして
図示している。このようにカーテン領域部分４１ａ，４
１ｂが互いに斜めに交差して延びているので、カーテン
領域部分４１ａ，４１ｂが互いに平行に延びている場
合、即ちカーテン領域部分４１ａ，４１ｂが互いに完全
に重なっている場合に比べてカーテン領域部分４１ａ，
４１ｂの重なり部分４２（図５においてハッチングが施
されている部分）が大幅に減少する。However, in this embodiment, as described above, the inclination angle of the valve shaft of the first exhaust valve 14a is larger than the inclination angle of the valve shaft of the second exhaust valve 14b. Therefore, on the projection surface of the exhaust valve openings projected so that the openings of the exhaust valves 14a and 14b facing each other overlap each other, that is, in FIG.
On the projection plane projected in the direction of arrow V or arrow A in FIG. 5, the openings of the exhaust valves 14a and 14b extend obliquely to each other as shown in FIG. Therefore the first
The curtain region 40a of the exhaust valve 14a and the second exhaust valve 14b
The curtain areas 40b also extend obliquely to each other on this projection plane. In FIG. 5, the first exhaust valve 14
The curtain region portion 41a of a and the curtain region portion 41b of the second exhaust valve 14b are seen to overlap each other in FIG.
It corresponds to part 0b. Note that, in FIG. 5, the curtain region portions 41a and 41b are shown by being shifted downward from the actual position. Thus, the curtain area portions 41a, 4a
Since 1b extends obliquely to each other, the curtain region portion 41a can be compared to when the curtain region portions 41a and 41b extend parallel to each other, that is, when the curtain region portions 41a and 41b completely overlap each other. ，
The overlapping portion 42 of 41b (hatched portion in FIG. 5) is significantly reduced.
【００１８】このカーテン領域の重なり部分４２内を通
過する既燃ガスの一部は第１排気弁１４ａの開口から排
出され、残りの部分は第２排気弁１４ｂの開口から排出
されることになる。しかしながらこのカーテン領域の重
なり部分４２内を通過する既燃ガスは本来どちらか一方
の排気弁１４ａまたは１４ｂの開口から全量排出されう
るものである。従ってカーテン領域の重なり部分４２が
大きいとその分だけ排気弁１４ａ，１４ｂの開口面積が
無駄になってしまい、その結果ブローダウン期間におけ
る既燃ガスの排出量が減少してしまう。本実施例では上
述のように第１排気弁１４ａの弁軸の傾斜角と第２排気
弁１４ｂの弁軸の傾斜角とを変えることによりカーテン
領域の重なり部分４２を低減させているので、ブローダ
ウン期間において既燃ガスが速やかかつ大量に排出され
る。Part of the burnt gas passing through the overlapping portion 42 of the curtain region is discharged from the opening of the first exhaust valve 14a, and the remaining portion is discharged from the opening of the second exhaust valve 14b. .. However, the burned gas passing through the overlapping portion 42 of the curtain region can be completely discharged from the opening of either exhaust valve 14a or 14b. Therefore, if the overlapping portion 42 of the curtain region is large, the opening area of the exhaust valves 14a and 14b is wasted by that amount, and as a result, the amount of burned gas discharged during the blowdown period is reduced. In this embodiment, as described above, the overlapping portion 42 of the curtain region is reduced by changing the inclination angle of the valve shaft of the first exhaust valve 14a and the inclination angle of the valve shaft of the second exhaust valve 14b. Burned gas is discharged promptly and in large quantities during the down period.
【００１９】このように本実施例では３個の排気弁１４
ａ，１４ｂを設けることにより排気弁の開口面積を増大
させると共に、第１排気弁１４ａおよび第２排気弁１４
ｂの弁軸の傾斜角を変えることによりカーテン領域の重
なり部分４２を低減させているので、排気弁１４ａ，１
４ｂが開弁すると燃焼室８内の既燃ガスが極めて急激に
排気ポート３３内に流出し、その結果燃焼室８内の圧力
が極めて急激に低下する。即ち強力なブローダウン作用
が得られる。なお、このブローダウンが生ずるブローダ
ウン期間は排気弁１４ａ，１４ｂの開弁開始時期から給
気弁１２の開弁開始時期までの期間にほぼ対応する。As described above, in this embodiment, the three exhaust valves 14 are provided.
By providing a and 14b, the opening area of the exhaust valve is increased and the first exhaust valve 14a and the second exhaust valve 14 are provided.
Since the overlapping portion 42 of the curtain region is reduced by changing the inclination angle of the valve shaft of b, the exhaust valves 14a, 1
When the valve 4b is opened, the burnt gas in the combustion chamber 8 flows into the exhaust port 33 very rapidly, and as a result, the pressure in the combustion chamber 8 drops extremely rapidly. That is, a strong blowdown action is obtained. The blowdown period in which this blowdown occurs substantially corresponds to the period from the opening start timing of the exhaust valves 14a and 14b to the opening start timing of the air supply valve 12.
【００２０】このように強力なブローダウン作用によっ
て燃焼室８内の圧力が急激に低下するので、次いで給気
弁１２が開弁するとただちに新気が燃焼室８内に流入を
開始する。従って多量の新気を燃焼室８内に送り込むこ
とができる。このように給気弁１２が開弁すると新気が
燃焼室８内に流入を開始するが排気弁１４ａ，１４ｂ側
の給気弁１２の開口はマスク壁２６ａによって覆われて
いるので新気はマスク壁２６ａと反対側の給気弁１２の
開口から燃焼室８内に流入する。この新気は給気弁１２
下方のシリンダボア内壁面に沿い下降し、次いでピスト
ン４の頂面に沿い進んで排気弁１４ａ，１４ｂ下方のシ
リンダボア内壁面に沿い上昇し、斯くして新気は燃焼室
８内をループ状に流れることになる。このループ状に流
れる新気によって燃焼室８内の既燃ガスが排気弁１４
ａ，１４ｂを介して良好に排出される。斯くして良好な
掃気効率を確保することができる。Since the pressure in the combustion chamber 8 is drastically reduced by such a strong blowdown action, fresh air starts flowing into the combustion chamber 8 immediately when the air supply valve 12 is subsequently opened. Therefore, a large amount of fresh air can be sent into the combustion chamber 8. When the air supply valve 12 is opened in this manner, fresh air begins to flow into the combustion chamber 8, but the opening of the air supply valve 12 on the side of the exhaust valves 14a and 14b is covered by the mask wall 26a, so The gas flows into the combustion chamber 8 from the opening of the air supply valve 12 on the side opposite to the mask wall 26a. This fresh air is the intake valve 12
It descends along the inner wall surface of the lower cylinder bore, then advances along the top surface of the piston 4 and rises along the inner wall surface of the cylinder bore below the exhaust valves 14a and 14b, and thus fresh air flows in a loop in the combustion chamber 8. It will be. The burned gas in the combustion chamber 8 is exhausted by the exhaust valve 14 by the fresh air flowing in a loop.
It is satisfactorily discharged via a and 14b. Thus, good scavenging efficiency can be secured.
【００２１】次いでピストン４が下死点ＢＤＣを過ぎて
上昇を開始するとその後燃料噴射弁３５ａ，３５ｂから
の燃料噴射が開始される。図６に示される燃料噴射Ｉｒ
およびＩｍ2 では第１燃料噴射弁３５ａからピストン４
頂面上に形成された凹部３７内に燃料が噴射され、点火
栓３０周りに最適な濃度の混合気が形成されるようにし
ている。一方、燃料噴射Ｉｍ1 ，Ｉｈ1およびＩｈ2 で
は噴射燃料がピストン４頂面の広い領域に亘って衝突せ
しめられ、燃焼室８内に均一混合気が形成されるように
している。Then, when the piston 4 passes the bottom dead center BDC and starts to rise, fuel injection from the fuel injection valves 35a and 35b is then started. Fuel injection Ir shown in FIG.
And Im 2 from the first fuel injection valve 35a to the piston 4
The fuel is injected into the concave portion 37 formed on the top surface so that the air-fuel mixture having the optimum concentration is formed around the spark plug 30. On the other hand, in the fuel injection Im 1 , Ih 1 and Ih 2 , the injected fuel is made to collide over a wide area of the top surface of the piston 4, and a uniform air-fuel mixture is formed in the combustion chamber 8.
【００２２】また図１、図３および図４に示されるよう
に第１排気弁１４ａの弁軸の傾斜角と第２排気弁１４ｂ
の弁軸の傾斜角とが異なっているので、互いに隣接する
各排気弁１４ａ，１４ｂのバルブリフタ４５の傾斜角も
互いに異なっている。その結果、互いに隣接するバルブ
リフタ４５が平行に配置されている場合に比べて隣接す
るバルブリフタ４５間に位置するリフタガイド部４７
（図８参照）の肉厚が全体的に厚くなり、従って排気動
弁系の強度を向上させることができる。また、このよう
にリフタガイド部４７の肉厚が全体的に厚くなるので、
バルブリフタ４５の円筒状部分の肉厚を増してバルブリ
フタ４５の強度を向上させることもできる。Further, as shown in FIGS. 1, 3 and 4, the inclination angle of the valve shaft of the first exhaust valve 14a and the second exhaust valve 14b.
Since the inclination angle of the valve shaft is different, the inclination angles of the valve lifters 45 of the exhaust valves 14a and 14b adjacent to each other are also different. As a result, the lifter guide portion 47 located between the adjacent valve lifters 45 is different from the case where the adjacent valve lifters 45 are arranged in parallel.
The wall thickness (see FIG. 8) is increased as a whole, so that the strength of the exhaust valve system can be improved. Also, since the wall thickness of the lifter guide portion 47 becomes thicker in this way,
The thickness of the cylindrical portion of the valve lifter 45 can be increased to improve the strength of the valve lifter 45.
【００２３】図８および図９を参照すると、排気弁用カ
ムシャフト２０は互いに隣接する第１排気弁駆動カム１
８ａと第２排気弁駆動カム１８ｂ間に位置する排気弁用
カムシャフト２０部分において夫々、シリンダヘッド６
の上壁面上に形成された排気弁用カムジャーナル面５０
と排気弁用カムキャップ５２に形成されたジャーナル面
とにより支承されている。即ち、排気弁用カムシャフト
２０は１気筒当たり、互いに隣接する排気弁駆動カム１
８ａ，１８ｂ間に位置する２箇所において支承されてい
る。Referring to FIG. 8 and FIG. 9, the exhaust valve camshaft 20 includes the first exhaust valve drive cam 1 adjacent to each other.
8a and the second exhaust valve drive cam 18b.
Exhaust valve cam journal surface 50 formed on the upper wall surface
And a journal surface formed on the exhaust valve cam cap 52. That is, the exhaust valve camshaft 20 is provided for each exhaust valve drive cam 1 that is adjacent to each other for each cylinder.
It is supported at two places located between 8a and 18b.
【００２４】このように、各気筒の３個の排気弁駆動カ
ム１８ａ，１８ｂの組の両外側に位置する２箇所で排気
弁用カムシャフト２０を支承するのではなく、互いに隣
接する排気弁駆動カム１８ａ，１８ｂ間に位置する２箇
所で排気弁用カムシャフト２０を支承することにより、
中央の排気弁駆動カム、即ち第２排気弁駆動カム１８ｂ
における排気弁用カムシャフト２０の撓みを小さく抑え
ることができ、従って排気弁用カムシャフト２０の撓み
を全体的に小さくすることができる。特に本実施例では
第１排気弁１４ａの弁軸の傾斜角と第２排気弁１４ｂの
弁軸の傾斜角とが異なっているので、バルブスプリング
５４ａ（図４参照）のばね力により第１排気弁駆動カム
１８ａに加えられる力の方向とバルブスプリング５４ｂ
（図３参照）のばね力により第２排気弁駆動カム１８ｂ
に加えられる力の方向とが異なっている。図８および図
９に示されるように互いに隣接する排気弁駆動カム１８
ａ，１８ｂ間に位置する２箇所で排気弁用カムシャフト
２０を支承すれば、夫々異なる方向のばね力が加えられ
る排気弁用カムシャフト２０部分の中間で排気弁用カム
シャフト２０を支承することになり、従って排気弁用カ
ムシャフト２０の撓みを確実に小さくすることができ
る。このように排気弁用カムシャフト２０の撓みや回転
振れが低減されるので、排気弁用カムシャフト２０の回
転速度を高めることができ、従って機関の最高回転数、
即ち許容回転数を高く設定することができる。また、各
排気弁１４ａ，１４ｂが正規のバルブリフト量を正確に
とることができる。更に、排気弁用カムキャップ５２の
ジャーナル面に対するカムシャフト２０の当たりも低減
されるのでカムキャップ５２のジャーナル面の摩耗や異
音の発生が防止される。As described above, the exhaust valve camshafts 20 are not supported at the two positions located on both outer sides of the set of the three exhaust valve drive cams 18a and 18b of each cylinder, but the exhaust valve drive cams adjacent to each other are driven. By supporting the exhaust valve cam shaft 20 at two positions located between the cams 18a and 18b,
Central exhaust valve drive cam, that is, second exhaust valve drive cam 18b
The bending of the exhaust valve camshaft 20 can be suppressed to be small, and therefore the bending of the exhaust valve camshaft 20 can be made small as a whole. Particularly, in this embodiment, since the inclination angle of the valve shaft of the first exhaust valve 14a and the inclination angle of the valve shaft of the second exhaust valve 14b are different, the first exhaust gas is generated by the spring force of the valve spring 54a (see FIG. 4). Direction of force applied to valve drive cam 18a and valve spring 54b
The second exhaust valve drive cam 18b is driven by the spring force (see FIG. 3).
The direction of the force applied to is different. The exhaust valve drive cams 18 adjacent to each other as shown in FIGS. 8 and 9.
If the exhaust valve camshaft 20 is supported at two positions located between a and 18b, the exhaust valve camshaft 20 should be supported in the middle of the exhaust valve camshaft 20 parts to which spring forces in different directions are applied. Therefore, the flexure of the exhaust valve camshaft 20 can be surely reduced. As described above, since the bending and the rotational runout of the exhaust valve camshaft 20 are reduced, the rotational speed of the exhaust valve camshaft 20 can be increased, and thus the maximum engine speed,
That is, the allowable rotation speed can be set high. Further, each exhaust valve 14a, 14b can accurately take a proper valve lift amount. Further, the contact of the camshaft 20 with the journal surface of the exhaust valve cam cap 52 is also reduced, so that the journal surface of the cam cap 52 is prevented from being worn and noise is prevented.
【００２５】一方、給気弁用カムシャフト２４は各気筒
の互いに隣接する一対の給気弁駆動カム２２間に位置す
る給気弁用カムシャフト２４部分において、シリンダヘ
ッド６の上壁面上に形成された給気弁用カムジャーナル
面５６と給気弁用カムキャップ５８に形成されたジャー
ナル面５８ａとにより支承される。次に機関冷却水通路
構造について説明する。本実施例における冷却水通路構
造は概略的に言って、ラジエータ（図示しない）から流
出した冷却水がウォータポンプ（図示しない）に供給さ
れ、ウォータポンプから吐出された冷却水がシリンダブ
ロック１内に形成されたシリンダブロック冷却水通路６
０内に供給され、シリンダブロック冷却水通路６０から
流出した冷却水がシリンダヘッド６内に形成されたシリ
ンダヘッド冷却水通路６２内に供給され、シリンダヘッ
ド冷却水通路６２から流通した冷却水がラジエータに供
給される構造になっている。On the other hand, the air supply valve cam shaft 24 is formed on the upper wall surface of the cylinder head 6 at the air supply valve cam shaft 24 portion located between the pair of air supply valve drive cams 22 adjacent to each other in each cylinder. The cam journal surface 56 for the intake valve and the journal surface 58a formed on the cam cap 58 for the intake valve are supported. Next, the engine cooling water passage structure will be described. Generally speaking, the cooling water passage structure in the present embodiment is such that cooling water flowing out from a radiator (not shown) is supplied to a water pump (not shown), and cooling water discharged from the water pump enters the cylinder block 1. Formed cylinder block cooling water passage 6
The cooling water supplied to the cylinder block cooling water passage 60 is supplied to the cylinder head cooling water passage 62 formed in the cylinder head 6, and the cooling water flowing from the cylinder head cooling water passage 62 is supplied to the radiator. It is structured to be supplied to.
【００２６】図１、図３および図７に示されるように本
実施例では特に各気筒毎に、排気弁１４ａ，１４ｂの弁
座１６の近傍を通る二つの第１冷却水通路６４と、燃料
噴射弁３５ａ，３５ｂのノズル部の近傍を通る一つの第
２冷却水通路６６とがシリンダヘッド６内に形成されて
いる。これらの第１冷却水通路６４および第２冷却水通
路６６はシリンダヘッド６の下壁面からドリル穴加工に
よって形成される。As shown in FIGS. 1, 3 and 7, in this embodiment, in particular, for each cylinder, two first cooling water passages 64 passing near the valve seat 16 of the exhaust valves 14a and 14b, and a fuel are provided. A single second cooling water passage 66 is formed in the cylinder head 6 passing near the nozzles of the injection valves 35a and 35b. The first cooling water passage 64 and the second cooling water passage 66 are formed from the lower wall surface of the cylinder head 6 by drilling.
【００２７】排気弁１４ａ，１４ｂは燃焼室８内の高温
既燃ガスが排出されるときにこの既燃ガスから熱を受
け、この熱が排気弁１４ａ，１４ｂの弁座１６を介して
シリンダヘッド６に伝達される。排気弁の弁座１６近傍
を通る第１冷却水通路６４を形成することにより、この
熱が効率良く冷却水に吸収される。斯くしてシリンダヘ
ッド６の熱歪みが発生することを防止できる。またこの
ようにシリンダヘッド６および燃焼室８が過熱されるこ
とが阻止されるので、ノッキングの発生を阻止しつつ点
火時期を進角させることが可能となり、その結果機関出
力トルクを高めることができる。The exhaust valves 14a and 14b receive heat from the burnt gas when the hot burned gas in the combustion chamber 8 is discharged, and this heat is transferred through the valve seat 16 of the exhaust valves 14a and 14b to the cylinder head. 6 is transmitted. By forming the first cooling water passage 64 passing near the valve seat 16 of the exhaust valve, this heat is efficiently absorbed by the cooling water. Thus, it is possible to prevent thermal distortion of the cylinder head 6. Further, since the cylinder head 6 and the combustion chamber 8 are prevented from being overheated in this way, it is possible to advance the ignition timing while preventing the occurrence of knocking, and as a result, the engine output torque can be increased. ..
【００２８】一方、第２冷却水通路６６内を流通する冷
却水によって燃料噴射弁３５ａ，３５ｂのノズル部が良
好に冷却される。その結果、ノズル部の熱膨張により燃
料噴射弁３５ａ，３５ｂ内の燃料通路径が変化すること
が防止されると共に、燃料噴射弁３５ａ，３５ｂ内で燃
料が気化して気泡が発生することが阻止される。斯くし
て燃料噴射量を正確に制御することができる。On the other hand, the nozzle portions of the fuel injection valves 35a and 35b are satisfactorily cooled by the cooling water flowing in the second cooling water passage 66. As a result, the diameter of the fuel passage in the fuel injection valves 35a, 35b is prevented from changing due to the thermal expansion of the nozzle portion, and the fuel is prevented from being vaporized and bubbles are generated in the fuel injection valves 35a, 35b. To be done. Thus, the fuel injection amount can be controlled accurately.
【００２９】[0029]
【発明の効果】排気弁の開弁期間初期に燃料室内から排
出される既燃ガス量を増大させることができ、その結果
燃料室内に流入する新気量を増大させることができる。
斯くして良好な掃気効率を確保することができる。The amount of burnt gas discharged from the fuel chamber can be increased at the beginning of the opening period of the exhaust valve, and as a result, the amount of fresh air flowing into the fuel chamber can be increased.
Thus, good scavenging efficiency can be secured.
【図１】２サイクル内燃機関の一つの気筒の斜視図であ
る。FIG. 1 is a perspective view of one cylinder of a two-cycle internal combustion engine.
【図２】シリンダヘッドの底面図である。FIG. 2 is a bottom view of a cylinder head.
【図３】図２の III−III 線に沿ってみた断面図であ
る。FIG. 3 is a sectional view taken along line III-III in FIG.
【図４】図２のIV−IV線に沿ってみた断面図である。4 is a sectional view taken along line IV-IV in FIG.
【図５】図２の矢印Ｖに沿ってみた排気弁の投影図であ
る。5 is a projection view of the exhaust valve taken along the arrow V in FIG. 2. FIG.
【図６】給排気弁の開弁時期と燃料噴射時期を示す線図
である。FIG. 6 is a diagram showing a valve opening timing of a supply / exhaust valve and a fuel injection timing.
【図７】２気筒２サイクル内燃機関のシリンダヘッドの
全体を示す底面図である。FIG. 7 is a bottom view showing the entire cylinder head of a 2-cylinder 2-cycle internal combustion engine.
【図８】排気弁用カムシャフトおよび給気弁用カムシャ
フトが取り付けられていない状態を示すシリンダヘッド
の上面図である。FIG. 8 is a top view of the cylinder head showing a state in which an exhaust valve camshaft and an intake valve camshaft are not attached.
【図９】排気弁用カムシャフトおよび給気弁用カムシャ
フトが取り付けられた状態を示すシリンダヘッドの上面
図である。FIG. 9 is a top view of the cylinder head showing a state in which an exhaust valve camshaft and an intake valve camshaft are attached.
４…ピストン １２…給気弁 １４ａ…第１排気弁 １４ｂ…第２排気弁 １６…弁座 ３０…点火栓 ３５ａ…第１燃料噴射弁 ３５ｂ…第２燃料噴射弁 4 ... Piston 12 ... Air supply valve 14a ... 1st exhaust valve 14b ... 2nd exhaust valve 16 ... Valve seat 30 ... Spark plug 35a ... 1st fuel injection valve 35b ... 2nd fuel injection valve
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｆ０２Ｂ 25/20 Ｚ 7114−3Ｇ ─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 5 Identification number Office reference number FI technical display location F02B 25/20 Z 7114-3G
Claims (1)
最も近い領域において排気弁とその弁座間に形成される
排気弁の開口が互いに対面している２サイクル内燃機関
の燃焼室構造において、上記領域に形成される各排気弁
開口が互いに重なるように投影した各排気弁開口の投影
面において各排気弁開口が互いに斜めに交差して延びる
ように各排気弁を配置した２サイクル内燃機関の燃焼室
構造。1. A combustion chamber structure for a two-cycle internal combustion engine, wherein the exhaust valve and the opening of the exhaust valve formed between its valve seats face each other in the region where the distance between the exhaust valves arranged adjacent to each other is the shortest. A two-cycle internal combustion engine in which the exhaust valves are arranged so that the exhaust valve openings are formed so as to overlap each other on the projection plane of the exhaust valve openings projected so as to overlap each other Combustion chamber structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22715091A JPH0565811A (en) | 1991-09-06 | 1991-09-06 | Structure of combustion chamber for two-cycle internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22715091A JPH0565811A (en) | 1991-09-06 | 1991-09-06 | Structure of combustion chamber for two-cycle internal combustion engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0565811A true JPH0565811A (en) | 1993-03-19 |
Family
ID=16856280
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22715091A Pending JPH0565811A (en) | 1991-09-06 | 1991-09-06 | Structure of combustion chamber for two-cycle internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0565811A (en) |
-
1991
- 1991-09-06 JP JP22715091A patent/JPH0565811A/en active Pending
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