JPH0249923A - Two-cycle internal combustion engine - Google Patents
Two-cycle internal combustion engineInfo
- Publication number
- JPH0249923A JPH0249923A JP20003588A JP20003588A JPH0249923A JP H0249923 A JPH0249923 A JP H0249923A JP 20003588 A JP20003588 A JP 20003588A JP 20003588 A JP20003588 A JP 20003588A JP H0249923 A JPH0249923 A JP H0249923A
- Authority
- JP
- Japan
- Prior art keywords
- valve
- air supply
- exhaust
- wall
- combustion chamber
- 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.)
- Granted
Links
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 55
- 230000002093 peripheral effect Effects 0.000 claims description 13
- 230000002000 scavenging effect Effects 0.000 abstract description 15
- 239000000446 fuel Substances 0.000 description 20
- 239000007789 gas Substances 0.000 description 9
- 239000000203 mixture Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000013517 stratification Methods 0.000 description 3
- 244000062793 Sorghum vulgare Species 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000012447 hatching Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 235000019713 millet Nutrition 0.000 description 1
Classifications
-
- 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
- Combustion Methods Of Internal-Combustion Engines (AREA)
Abstract
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は２サイクル内燃機関に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to a two-stroke internal combustion engine.
一対の給気弁と一対の排気弁を具備し、シリンダヘッド
内壁面から燃焼室に向けて延びるマスク壁を各排気弁と
吸気弁との間に形成して各マスク壁により給気弁側に位
置する各排気弁周縁部と弁座間の開口を排気弁のリフ＋
−１が小さいときに閉鎖し、一対の給気ポートから夫々
流入する新気の流量が等しくなるように各給気ポートを
形成した２サイクル内燃機関が本出願人により既に提案
されている（特願昭６２−３１５５９号参照）。この２
サイクル内燃機関では排気弁開弁時においてブローダウ
ンが生じた後に排気ポートから燃焼室内に逆流する排気
ガスをマスク壁により案内し、この逆流排気ガスにより
燃焼室内にシリンダ軸線回りのスワール流を発生せしめ
るようにしている。機関低負荷運転時には給気ポートか
ら流入する新気の流速が遅いために新気が逆流排気ガス
のスワール流と共に旋回し、その結果新気が燃焼室の下
方領域に拡散せず、燃焼室の上部領域に集まるために燃
焼室内は成層化される。一方、機関高負荷運転時には給
気ポートから流入する新気の流速が速いために新気はピ
ストン頂面に向かって下降し、次いでピストン頂面にお
いて流れ方向を変え、斯くしてループ掃気が行なわれる
。このとき再給気ポートから流入する新気の流量が異な
ると、即ち再給気ポートから流入する新気の強さに差が
あると弱い方の新気流は強い方の新気流により横方向に
押されるためにきれいなループ状を描いて流れず、斯く
して全体として良好なループ掃気が得られない。しかし
ながらこの２サイクル内燃機関では再給気ポートから流
入する新気の強さが等しいために両断気流が共にループ
状に流れ、斯くして良好なループ掃気が行なわれる。It is equipped with a pair of intake valves and a pair of exhaust valves, and a mask wall extending from the inner wall surface of the cylinder head toward the combustion chamber is formed between each exhaust valve and the intake valve. The opening between the peripheral edge of each exhaust valve and the valve seat is
The applicant has already proposed a two-stroke internal combustion engine in which the air intake ports are closed when -1 is small, and each air intake port is formed so that the flow rate of fresh air flowing in from the pair of air intake ports is equal. (See Application No. 62-31559). This 2
In a cycle internal combustion engine, after blowdown occurs when the exhaust valve is opened, the exhaust gas that flows back into the combustion chamber from the exhaust port is guided by a mask wall, and this backflow exhaust gas generates a swirl flow around the cylinder axis in the combustion chamber. That's what I do. When the engine is running at low load, the flow rate of fresh air flowing in from the intake port is slow, so the fresh air swirls together with the swirl flow of backflow exhaust gas, and as a result, the fresh air does not diffuse into the lower region of the combustion chamber and The inside of the combustion chamber is stratified because it collects in the upper region. On the other hand, during high-load engine operation, the flow rate of fresh air flowing in from the air supply port is high, so the fresh air descends toward the top of the piston, then changes its flow direction at the top of the piston, thus performing loop scavenging. It will be done. At this time, if the flow rate of the fresh air flowing in from the resupply air port is different, that is, if there is a difference in the strength of the fresh air flowing in from the resupply air port, the weaker fresh airflow will be influenced laterally by the stronger fresh airflow. Because of the pressure, the air does not flow in a neat loop shape, and thus good loop scavenging cannot be obtained as a whole. However, in this two-stroke internal combustion engine, since the strength of the fresh air flowing in from the refeeding port is equal, the two interrupted air flows flow together in a loop, thus achieving good loop scavenging.
しかしながらこの２サイクル内燃機関では排気弁のリフ
トが大きくなると排気弁と弁座間の開口が排気弁の全周
に亘って燃焼室内に開口し、その結果給気ポートから流
入した新気の一部がシリンダヘッド内壁面に沿って流れ
、次いでマスク壁を越えて排気ポート内に流出するため
に新気の吹き抜けが生じる。ところがこのように新気の
一部が排気ポート内に吹き抜けるとこの新気はループ掃
気に寄与しないことになるので強力なループ掃気を行な
うことができないという問題がある。However, in this two-stroke internal combustion engine, when the lift of the exhaust valve becomes large, the opening between the exhaust valve and the valve seat opens into the combustion chamber around the entire circumference of the exhaust valve, and as a result, a portion of the fresh air flowing in from the intake port is Fresh air flows along the inner wall surface of the cylinder head and then flows out over the mask wall into the exhaust port, resulting in a blow-by of fresh air. However, if part of the fresh air blows into the exhaust port in this way, this fresh air does not contribute to loop scavenging, so there is a problem in that strong loop scavenging cannot be performed.
上記問題点を解決するために本発明によれば一対の給気
弁および一対の給気ポートをシリンダ軸線を含む平面に
関して夫々対称に配置すると共に各給気弁の形状および
各給気ポートの形状を夫々実質的に同一の形状に形成し
、シリンダヘッド内壁面から燃焼室に向けて延びるマス
ク壁を各給気弁と排気弁との間に形成して各マスク壁に
より排気弁側に位置する各給気弁周縁部と弁座間の開口
を給気弁の全開弁期間に亘って閉鎖し、各マスク壁を上
述のシリンダ軸線を含む平面に関して対称に配置すると
共に各マスク壁の形状を実質的に同一の形状に形成して
いる。In order to solve the above problems, according to the present invention, a pair of intake valves and a pair of intake ports are arranged symmetrically with respect to a plane including the cylinder axis, and the shape of each intake valve and the shape of each intake port are arranged symmetrically with respect to a plane including the cylinder axis. are formed in substantially the same shape, and a mask wall extending from the inner wall surface of the cylinder head toward the combustion chamber is formed between each intake valve and the exhaust valve, so that each mask wall is located on the exhaust valve side. The opening between the peripheral edge of each intake valve and the valve seat is closed during the entire opening period of the intake valve, and each mask wall is arranged symmetrically with respect to the plane containing the cylinder axis mentioned above, and the shape of each mask wall is substantially changed. are formed into the same shape.
排気弁側に位置する各給気弁周縁部と弁座間の開口を給
気弁の全開弁期間に亘ってマスク壁により閉鎖すること
によって給気ポートから流入する新気は排気ポート内に
吹き抜けることなくピストン頂面に向かい、しかも再給
気ポートから流入する新気が共にきれいなループ状をな
して流れる。By closing the opening between the peripheral edge of each air supply valve and the valve seat located on the exhaust valve side with a mask wall during the period when the air supply valve is fully open, fresh air flowing from the air supply port can blow through into the exhaust port. The fresh air flows toward the top of the piston, forming a clean loop along with the fresh air flowing in from the resupply air port.
第１図から第３図を参照すると、ｌはシリンダブロック
、２はシリンダブロック１内で往復動するピストン、３
はシリンダブロックｌ上に固定されたシリンダヘッド、
４はシリンダヘッド３の内壁面３ａとピストン２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３の
内壁面３ａ上には燃焼室４に向けて突出しかつシリンダ
ヘッド３の内壁面３ａの直径に沿いその直径の全体に亙
って延びる***部５が形成される。第１図に示すように
この***部５はその下端部に尾根５ａを有する三角形状
断面を有しており、この***部５の根元部が第１図から
第３図において５ｂで示される。***部５の一側には一
対の給気弁６が配置され、***部５の他側には一対の排
気弁７が配置される。Referring to FIGS. 1 to 3, 1 is a cylinder block, 2 is a piston that reciprocates within the cylinder block 1, and 3 is a cylinder block.
is the cylinder head fixed on the cylinder block l,
4 indicates a combustion chamber formed between the inner wall surface 3a of the cylinder head 3 and the top surface of the piston 2, respectively. A protrusion 5 is formed on the inner wall surface 3a of the cylinder head 3, which projects toward the combustion chamber 4 and extends along the entire diameter of the inner wall surface 3a of the cylinder head 3. As shown in FIG. 1, this raised portion 5 has a triangular cross-section with a ridge 5a at its lower end, and the root portion of this raised portion 5 is indicated by 5b in FIGS. 1 to 3. A pair of air supply valves 6 are arranged on one side of the raised part 5, and a pair of exhaust valves 7 are arranged on the other side of the raised part 5.
また、***部５の中央部５ｃは排気弁７側に湾曲せしめ
られており、この湾曲中央部５Ｃの給気弁６側に点火栓
８が配置される。従って点火栓８はほぼシリンダ軸線上
に位置し、しかも***部５に対して給気弁６側に配置さ
れている。***部５上には排気弁７側に位置する給気弁
６周縁部と弁座９間の開口を覆うために各給気弁６に対
して夫々マスク壁１０が形成されている。これらのマス
ク壁１０は対応する給気弁６の周縁部に極めて近接配置
されかつ給気弁６の周縁部に沿って延びる断面円弧状を
なしており、更にこれらのマスク壁１０は第１図におい
て鎖線で示す最大リフト位置にある給気弁６よりも下方
まで燃焼室４に向けて延びている。従って排気弁７側に
位置する給気弁６周縁部と弁座９間の開口は給気弁６の
開弁期間全体に亙ってマスク壁１０により閉鎖されるこ
とになる、一方、排気弁７の周縁部と***部５の根元部
５ｂとの間には一定の間隔が設けられており従って給気
弁６側に位置する排気弁７周縁部と弁座１１間の開口は
***部５によって閉鎖されることがない。従って排気弁
７が開弁すると排気弁７と弁座１１間に形成される開口
はその全体が燃焼室４内に開口することになる。Further, the central portion 5c of the raised portion 5 is curved toward the exhaust valve 7 side, and the ignition plug 8 is disposed on the air supply valve 6 side of this curved central portion 5C. Therefore, the ignition plug 8 is located approximately on the cylinder axis, and is located on the intake valve 6 side with respect to the raised portion 5. A mask wall 10 is formed on the raised portion 5 for each air intake valve 6 to cover the opening between the peripheral edge of the air intake valve 6 and the valve seat 9 located on the exhaust valve 7 side. These mask walls 10 are disposed very close to the periphery of the corresponding air supply valve 6 and have an arcuate cross section extending along the periphery of the air supply valve 6. It extends toward the combustion chamber 4 below the intake valve 6 which is at the maximum lift position shown by the chain line. Therefore, the opening between the peripheral edge of the air supply valve 6 and the valve seat 9 located on the exhaust valve 7 side is closed by the mask wall 10 throughout the opening period of the air supply valve 6. A certain distance is provided between the peripheral edge of the exhaust valve 7 and the root part 5b of the raised part 5. Therefore, the opening between the peripheral edge of the exhaust valve 7 located on the air supply valve 6 side and the valve seat 11 is located at the raised part 5. will not be closed by. Therefore, when the exhaust valve 7 opens, the entire opening formed between the exhaust valve 7 and the valve seat 11 opens into the combustion chamber 4.
シリンダヘッド３内には給気弁６に対して給気ポート１
２が形成され、排気弁７に対して排気ポート１３が形成
される。各給気ポート１２は例えば機関によって駆動さ
れる機械式過給機１４および給気ダクト１５を介して図
示しないエアクリーナに接続されており、給気ダクト１
５内にはスロットル弁１６が配置される。各給気ボー１
−１２の上壁面には燃料噴射弁１７が配置され、各燃料
噴射弁１７からは広がり角の小さい剛体状の燃料が給気
弁６の第３図においてハツチングで示す領域１８に向け
て噴射される。この領域１８は給気ポート１２軸線に関
して点火栓８側に位置し、かつ両給気弁６の弁ステムを
結ぶ線に対して点火栓８と反対側に位置する。In the cylinder head 3, there is an air intake port 1 for the air intake valve 6.
2 is formed, and an exhaust port 13 is formed for the exhaust valve 7. Each air supply port 12 is connected to an air cleaner (not shown) via a mechanical supercharger 14 driven by an engine and an air supply duct 15, for example.
A throttle valve 16 is disposed within the throttle valve 5 . Each air supply bow 1
Fuel injection valves 17 are arranged on the upper wall surface of -12, and from each fuel injection valve 17, rigid fuel with a small spread angle is injected toward a region 18 of the intake valve 6 shown by hatching in FIG. Ru. This region 18 is located on the ignition plug 8 side with respect to the axis of the air supply port 12, and on the opposite side of the ignition plug 8 with respect to a line connecting the valve stems of both the air supply valves 6.
第２図かられかるように一対の給気弁６はシリンダ軸線
を含む平面ａ−ａに関して対称に配置されており、一対
の給気ポート１２も平面ａ−ａに関して対称に配置され
ている。また、各給気弁６の形状は実質的に同一であり
、各給気ポート１２の形状も実質的に同一である。また
、各給気弁６の弁リフト曲線は実質的に同一であり、従
って給気弁６が開弁じたときに各給気ポート１２から流
入する新気の量は実質的に同一となる。また、***部５
は平面ａ−ａに関して対称的な形状を有し、各マスク壁
１０も平面ａ−ａに関して対称的に配置されている。更
に各マスク壁１０は実質的に同一の形状を有する。また
、各排気弁７も平面ａａに関して対称的に配置されてお
り、弁黍排気弁７は実質的に同一の形状を有する。As can be seen from FIG. 2, the pair of air supply valves 6 are arranged symmetrically with respect to a plane a-a including the cylinder axis, and the pair of air supply ports 12 are also arranged symmetrically with respect to a plane a-a. Moreover, the shape of each air supply valve 6 is substantially the same, and the shape of each air supply port 12 is also substantially the same. Further, the valve lift curves of each intake valve 6 are substantially the same, and therefore the amount of fresh air flowing from each intake port 12 when the intake valve 6 is opened is substantially the same. In addition, the raised portion 5
has a symmetrical shape with respect to the plane a-a, and each mask wall 10 is also arranged symmetrically with respect to the plane a-a. Furthermore, each mask wall 10 has a substantially identical shape. Moreover, each exhaust valve 7 is also arranged symmetrically with respect to the plane aa, and the valve millet exhaust valves 7 have substantially the same shape.
第４図は各給気弁６および各排気弁７の開弁期間の一例
、および燃料噴射期間の一例を示している。第４図に示
す例においては給気弁６よりも排気弁７が先に開弁じ、
給気弁６よりも排気弁７が先に閉弁する。更に燃料噴射
期間は給気弁６の開弁後、下死点ＢＤＣ前までの間に設
定されている。FIG. 4 shows an example of the opening period of each intake valve 6 and each exhaust valve 7, and an example of a fuel injection period. In the example shown in FIG. 4, the exhaust valve 7 opens earlier than the intake valve 6.
The exhaust valve 7 closes before the intake valve 6. Further, the fuel injection period is set from the time when the intake valve 6 opens until before the bottom dead center BDC.
第５図は給気弁６および排気弁７の弁リフトおよび排気
ポート１３内の圧力変化Ｐ１＋Ｐｚ＋Ｑ＋ 、Ｑｚを示
している。これらの圧力変化Ｐ＋。FIG. 5 shows the valve lifts of the intake valve 6 and the exhaust valve 7 and the pressure changes P1+Pz+Q+, Qz in the exhaust port 13. These pressure changes P+.
Ｐｔ 、Ｑｌ、 Ｑｚについては後述する。Pt, Ql, and Qz will be described later.
次に第６図および第７図を参照して掃気作用および成層
化作用について説明する。第６図は低負荷運転時を示し
ており、第７図は高負荷運転時を示している。また、第
６図（＾）および第７図（＾）は給気弁６が開弁じた直
後を示しており、第６図（Ｂ）および第７図（Ｂ）はピ
ストン２がほぼ下死点にあるときを示している。Next, the scavenging action and stratification action will be explained with reference to FIGS. 6 and 7. FIG. 6 shows the state of low load operation, and FIG. 7 shows the state of high load operation. In addition, Fig. 6 (^) and Fig. 7 (^) show the state immediately after the air supply valve 6 is opened, and Fig. 6 (B) and Fig. 7 (B) show that the piston 2 is almost dead. It shows when it is at a point.
まず初めに第６図を参照して機関低負荷運転時について
説明する。First, with reference to FIG. 6, the operation during low engine load operation will be described.
ピストン２が下降して排気弁７が開弁すると燃焼室４内
の高圧燃焼ガスが排気ポート１３内に流出し、その結果
第５図においてＰ、で示すように排気ボー）１３内の圧
力は一時的に正圧となる。When the piston 2 descends and the exhaust valve 7 opens, the high-pressure combustion gas in the combustion chamber 4 flows out into the exhaust port 13, and as a result, the pressure in the exhaust port 13 as indicated by P in FIG. Temporarily becomes positive pressure.
この正圧Ｐ、は排気通路内を下流に向けて伝播し、各気
筒の排気通路の集合部において反射し、今度は負圧とな
って再び排気ボー１−１３内に伝播してくる。従って給
気弁６が開弁すると第５図においてＰ２で示されるよう
に排気ポート１３内には負圧が発生する。この負圧の発
生する時期は排気通路の長さに依存している。機関低負
荷運転時は燃焼圧が低く、従って排気ポート１３内に発
生する正圧Ｐ１、負圧Ｐ２は比較的小さい。This positive pressure P propagates downstream in the exhaust passage, is reflected at the gathering part of the exhaust passages of each cylinder, and then becomes negative pressure and propagates into the exhaust bow 1-13 again. Therefore, when the air supply valve 6 opens, a negative pressure is generated in the exhaust port 13, as indicated by P2 in FIG. The timing at which this negative pressure occurs depends on the length of the exhaust passage. When the engine is operating at low load, the combustion pressure is low, and therefore the positive pressure P1 and negative pressure P2 generated within the exhaust port 13 are relatively small.
給気弁６が開弁すると給気ポート１２から燃焼室４内に
燃料を含んだ新気が流入するが給気弁６の開口に対して
マスク壁１０が設けられているために新気および燃料は
主にマスク壁１０と反対側の給気弁６の開口部から燃焼
室４内に流入する。When the intake valve 6 opens, fresh air containing fuel flows into the combustion chamber 4 from the intake port 12, but because the mask wall 10 is provided in front of the opening of the intake valve 6, fresh air and Fuel mainly flows into the combustion chamber 4 through the opening of the intake valve 6 on the side opposite to the mask wall 10.
一方、給気弁６が開弁すると第５図においてＰ２で示さ
れるように排気ポート１３内には負圧が発生するので燃
焼室４の上方部の既燃ガスがこの負圧によって排気ポー
ト１３内に吸い出される。この既燃ガスの移動によって
新気および燃料は第６図（＾）において矢印Ｒ，で示す
ように排気弁７に向けて引っばられ、斯くして燃料が点
火栓８ （第ユ図）の周りに導びかれる。次いで第６図
＋８１に示すようにピストン２が下降すると燃料を含ん
だ新気はＲ２で示されるように給気弁６下方のシリンダ
内壁面に沿って下方に向かう。しかしながら機関低負荷
運転時は燃焼室４内に流入する新気量が少なくしかも流
入速度が遅いために新気はピストン２の頂面まで達せず
、燃焼室４の上方部に滞留している。従ってピストン２
が上昇すると燃焼室４の上方部には混合気が集まり、燃
焼室４の下方部には残留既燃ガスが集まるために燃焼室
４内は成層化されることになる。斯くして混合気が点火
栓８によって確実に着火せしめられるごとになる。On the other hand, when the intake valve 6 opens, negative pressure is generated in the exhaust port 13 as shown by P2 in FIG. being sucked out inside. Due to the movement of the burnt gas, fresh air and fuel are drawn toward the exhaust valve 7 as shown by the arrow R in Figure 6 (^), and the fuel is thus drawn into the spark plug 8 (Figure 6). be guided by those around you. Next, as shown in FIG. 6+81, when the piston 2 descends, the fresh air containing fuel moves downward along the inner wall surface of the cylinder below the intake valve 6, as shown by R2. However, when the engine is operating at low load, the amount of fresh air flowing into the combustion chamber 4 is small and the speed of the fresh air flowing into the combustion chamber 4 is slow, so that the fresh air does not reach the top surface of the piston 2 and remains in the upper part of the combustion chamber 4. Therefore piston 2
When the combustion chamber 4 rises, air-fuel mixture gathers in the upper part of the combustion chamber 4, and residual burnt gas gathers in the lower part of the combustion chamber 4, so that the inside of the combustion chamber 4 becomes stratified. In this way, the air-fuel mixture is reliably ignited by the ignition plug 8.
一方、機関高負荷運転時には燃焼圧が高くなるために第
５図においてＱ、で示されるように排気ポート１３内に
発生ずる正圧が高くなり、またこの正圧Ｑ１の反射波で
ある負圧Ｑｔも大きくなる。On the other hand, during high-load engine operation, the combustion pressure increases, so the positive pressure generated in the exhaust port 13 increases as shown by Q in FIG. 5, and the negative pressure that is the reflected wave of this positive pressure Q1 increases. Qt also increases.
また、負圧Ｑ２のピークは負圧Ｐ２のピークよりも若干
遅れて発生する。Further, the peak of the negative pressure Q2 occurs slightly later than the peak of the negative pressure P2.
機関高負荷運転時には燃焼室４内に流入する新気の量が
多く、しかも流入速度が速くなる。従って給気弁６が開
弁すると多量の新気が高速度で燃焼室４内に流入する。When the engine is operated under high load, the amount of fresh air flowing into the combustion chamber 4 is large, and the speed of the air flowing into the combustion chamber 4 is high. Therefore, when the intake valve 6 opens, a large amount of fresh air flows into the combustion chamber 4 at a high speed.
次いで排気ポート１３内に発生する負圧ＱＸによって燃
焼室４の上方部の既燃ガスが排気ポート１３内に吸い出
されると第７図（＾）において矢印Ｓ、、Ｓ、で示され
るように新気は燃焼室４の中心部の方に向きを変える。Next, the burnt gas in the upper part of the combustion chamber 4 is sucked out into the exhaust port 13 by the negative pressure QX generated in the exhaust port 13, as shown by the arrows S, , S, in FIG. 7(^). The fresh air is directed towards the center of the combustion chamber 4.
次いで更にピストン２が下降すると第７図（８１におい
てＳｓで示されるように新気は給気弁６下方のシリンダ
内壁面に沿って下方に向かい、ピストン２の頂面に達す
る。従って燃焼室４内の既燃ガスは第７図（ｅｌにおい
て矢印Ｔで示すように新気により徐々に追いやられて排
気ポート１３内に排出され、斯くして燃焼室４内ではル
ープ掃気が行なわれることになる。Next, as the piston 2 further descends, as shown by Ss in FIG. The burnt gas in the combustion chamber 4 is gradually driven away by fresh air and discharged into the exhaust port 13 as shown by the arrow T in FIG. .
ところで前述したように第１図から第３図に示す実施例
では各給気弁６、各マスク壁１０および各給気ポート１
２は夫々平面ａ−ａに関して対称に配置されており、夫
々実質的に同一の形状を有する。従って各給気ポート１
２から流入する新気の強さは実質的に等しく、しかも燃
焼室４内の形状が平面ａ−ａに関して対称的な形状とな
っているので各給気ポート１２から燃焼室４内に流入し
た新気は平面ａ−ａに関して対称的なループ状の流れを
生ずる。その結果、新気はきれいなループ状をなして燃
焼室４内を流れることになり、斯くして機関高負荷運転
時には強力なループ掃気が得られることになる。By the way, as mentioned above, in the embodiment shown in FIGS. 1 to 3, each air supply valve 6, each mask wall 10, and each air supply port 1
2 are each arranged symmetrically with respect to the plane a-a, and each have substantially the same shape. Therefore each air supply port 1
The strength of the fresh air flowing in from the intake ports 12 is substantially equal, and since the shape inside the combustion chamber 4 is symmetrical with respect to the plane a-a, the fresh air flows into the combustion chamber 4 from each intake port 12. The fresh air creates a loop-like flow that is symmetrical about the plane a-a. As a result, the fresh air flows in the combustion chamber 4 in a clean loop shape, and thus strong loop scavenging air can be obtained during high-load engine operation.
給気弁６および排気弁７を具えた２サイクル内燃機関で
はこのようなループ掃気が最も掃気効率がよい。また２
サイクル内燃機関では残留既燃ガス量が多く、このよう
に残留既燃ガスが多い場合においても良好な着火燃焼を
確保するためには点火栓８の周りに混合気を集めてお（
こと、即ち良好な成層化を行なうことが必要となる。第
１図から第３図に示す実施例ではマスク壁ｌＯを設ける
ことによって新気および混合気がシリンダ内壁面３の内
壁面３ａに沿って排気ポート１３内に流出することがな
く、それによって良好なループ掃気を確保できるばかり
でな（、良好な成層化も確保することができる。In a two-stroke internal combustion engine equipped with an intake valve 6 and an exhaust valve 7, such loop scavenging has the highest scavenging efficiency. Also 2
In a cycle internal combustion engine, there is a large amount of residual burnt gas, and in order to ensure good ignition combustion even when there is a large amount of residual burnt gas, the air-fuel mixture is collected around the ignition plug 8 (
In other words, it is necessary to perform good stratification. In the embodiment shown in FIGS. 1 to 3, the provision of the mask wall 10 prevents fresh air and air-fuel mixture from flowing into the exhaust port 13 along the inner wall surface 3a of the cylinder inner wall surface 3, thereby improving the Not only can it ensure good loop scavenging (but also good stratification).
また、点火栓８を***部５に対して給気弁６側に配置す
ることによって点火栓８の周りに混合気が集まりやすく
なり、従って点火栓８による混合気の良好な着火を確保
することができる。特に***部５の湾曲中央部５ｃによ
り包囲された領域には混合気が滞留しやすく、この領域
内に点火栓８が配置されているので着火性が向上せしめ
られる。Further, by arranging the spark plug 8 on the side of the air supply valve 6 with respect to the raised portion 5, the air-fuel mixture tends to gather around the spark plug 8, thus ensuring good ignition of the air-fuel mixture by the spark plug 8. Can be done. In particular, the air-fuel mixture tends to stay in the region surrounded by the curved central portion 5c of the raised portion 5, and since the spark plug 8 is disposed within this region, ignition performance is improved.
また、燃料噴射弁１７から噴射された燃料は給気弁６の
かさ部背面に衝突して霧化した後にただちに燃焼室４内
に供給されるので燃料が給気ポート１２の内壁面上に付
着することがない。In addition, the fuel injected from the fuel injection valve 17 collides with the back surface of the air intake valve 6 to atomize and is immediately supplied into the combustion chamber 4, so that the fuel adheres to the inner wall surface of the air intake port 12. There's nothing to do.
第８図および第９図は更に良好なループ掃気を確保でき
るようにした２サイクル内燃機関の別の実施例を示す。FIGS. 8 and 9 show another embodiment of a two-stroke internal combustion engine in which even better loop scavenging can be ensured.
この実施例ではシリンダヘッド内壁面３ａ上に凹溝２０
が形成され、この凹溝２０の底壁面をなすシリンダヘッ
ド内壁面部分３ｂ上に給気弁６が配置される。一方、凹
溝２０を除くシリンダヘッド内壁面部分３ｃはほぼ平坦
をなし、このシリンダヘッド内壁面部分３ｃ上に排気弁
７が配置される。シリンダヘッド内壁面部分３ｂとシリ
ンダヘッド内壁面部分３ｃは凹溝２０の周壁２１を介し
て互いに接続されている。この凹溝周壁２１は給気弁６
の周縁部に極めて近接配置されかつ給気弁６の周縁部に
沿って円弧状に延びるマスク壁２１ａと、給気弁６間に
位置する新気ガイド璧２１ｂと、シリンダヘッド内壁面
３ａの周壁と給気弁６間に位置する新気ガイド壁２ＩＣ
とにより構成される。各マスク壁２１ａは最大リフト位
置にある給気弁６よりも下方まで燃焼室４に向けて延び
ており、従って排気弁７側に位置する給気弁６周縁部と
弁座９間の開口は給気弁６の開弁期間全体に互ってマス
ク壁２１ａにより閉鎖されることになる。また、各新気
ガイド壁２１ｂ、２１Ｃ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２１ｂ、２１Ｃは再給気
弁６の中心を結ぶ線に対してほぼ平行に延びている。点
火栓８はシリンダヘッド内壁面３ａの中心に位置するよ
うにシリンダヘッド内壁面部分３ｃ上に配置されている
。In this embodiment, a groove 20 is formed on the inner wall surface 3a of the cylinder head.
is formed, and the air supply valve 6 is disposed on the cylinder head inner wall surface portion 3b forming the bottom wall surface of the groove 20. On the other hand, the cylinder head inner wall surface portion 3c excluding the groove 20 is substantially flat, and the exhaust valve 7 is disposed on this cylinder head inner wall surface portion 3c. The cylinder head inner wall surface portion 3b and the cylinder head inner wall surface portion 3c are connected to each other via the peripheral wall 21 of the groove 20. This concave groove surrounding wall 21 is connected to the air supply valve 6
a mask wall 21a which is arranged very close to the peripheral edge of the air supply valve 6 and extends in an arc shape along the peripheral edge of the air supply valve 6; a fresh air guide wall 21b located between the air supply valves 6; and a peripheral wall of the cylinder head inner wall surface 3a. and the fresh air guide wall 2IC located between the air supply valve 6
It is composed of Each mask wall 21a extends toward the combustion chamber 4 below the intake valve 6 at the maximum lift position, so that the opening between the peripheral edge of the intake valve 6 and the valve seat 9 located on the exhaust valve 7 side is During the entire opening period of the air supply valve 6, it is closed by the mask wall 21a. Further, the fresh air guide walls 21b and 21C are located in substantially the same plane, and furthermore, these fresh air guide walls 21b and 21C extend substantially parallel to the line connecting the centers of the resupply valve 6. There is. The ignition plug 8 is arranged on the cylinder head inner wall surface portion 3c so as to be located at the center of the cylinder head inner wall surface 3a.
第９図かられかるようにこの実施８例においても一対の
給気弁６はシリンダ軸線を含む平面ａ−ａに関して対称
に配置されており、一対の給気ポート１２も平面ａ−ａ
に関して対称に配置されている。また、各給気弁６の形
状は実質的に同一であり、各給気ポート１２の形状も実
質的に同一である。また、各給気弁６の弁リフト曲線は
実質的に同一であり、従って給気弁６が開弁じたときに
各給気ボー）１２から流入する新気の量は実質的に同一
となる。また、各マスク壁２１ａは平面ａ−ａに関して
対称的な形状を有し、新気ガイド壁２１ｂおよび各新気
ガイド壁２１ｃも夫々平面ａ−ａに関して対称的に配置
されている。更に各マスク壁２１ａおよび各新気ガイド
壁２１ｃは夫々実質的に同一の形状を有する。また、各
排気弁７および各排気ボー）１３も夫々平面ａ−ａに関
して対称的に配置されており、各排気弁７および各排気
ポート１３は夫々実質的に同一の形状を有する。As can be seen from FIG. 9, also in this eighth embodiment, the pair of air supply valves 6 are arranged symmetrically with respect to the plane a-a including the cylinder axis, and the pair of air supply ports 12 are also arranged symmetrically on the plane a-a.
are arranged symmetrically with respect to Moreover, the shape of each air supply valve 6 is substantially the same, and the shape of each air supply port 12 is also substantially the same. Further, the valve lift curves of each air intake valve 6 are substantially the same, and therefore the amount of fresh air flowing from each air intake valve 12 when the air intake valve 6 is opened is substantially the same. . Further, each mask wall 21a has a symmetrical shape with respect to the plane a-a, and the fresh air guide wall 21b and each fresh air guide wall 21c are also arranged symmetrically with respect to the plane a-a. Further, each mask wall 21a and each fresh air guide wall 21c have substantially the same shape. Further, each exhaust valve 7 and each exhaust port 13 are also arranged symmetrically with respect to the plane a-a, and each exhaust valve 7 and each exhaust port 13 have substantially the same shape.
この実施例では第１図から第３図に示す実施例に比べて
円弧状に延びるマスク壁２１ａの長さが長く、給気弁６
とその弁座９間に形成される開口のうちで排気弁７側に
位置するほぼ１／３の開口がマスク壁２１ａにより閉鎖
され、排気弁７と反対側に位置するほぼ２／３の開口か
ら新気が供給される。更にこの実施例では給気弁６から
流入した新気は新気ガイド壁２１ｂ、２１Ｃによりシリ
ンダ内壁面に沿って下方に向かうように案内される。従
ってこの実施例では給気弁６が開弁じたときには第１０
図において矢印Ｕで示すように大部分の新気がシリンダ
内壁面に沿ってピストン２の頂面に向かい、斯くして良
好なループ掃気が行なわれることになる。In this embodiment, the mask wall 21a extending in an arc shape is longer than the embodiments shown in FIGS. 1 to 3, and the air supply valve 6 is longer.
Of the openings formed between the valve seat 9 and the valve seat 9, approximately 1/3 of the openings located on the exhaust valve 7 side are closed by the mask wall 21a, and approximately 2/3 of the openings located on the opposite side of the exhaust valve 7. Fresh air is supplied from Furthermore, in this embodiment, the fresh air flowing in from the air supply valve 6 is guided downward along the inner wall surface of the cylinder by the fresh air guide walls 21b and 21C. Therefore, in this embodiment, when the air supply valve 6 is opened, the 10th
As shown by arrow U in the figure, most of the fresh air flows toward the top surface of the piston 2 along the inner wall surface of the cylinder, thus achieving good loop scavenging.
ところで第９図および第１０図に示す実施例においても
各給気弁６、各給気ポート１２、各マスク壁２１ａおよ
び各新気ガイド壁２１Ｃは夫々平面ａ−ａに関して対称
に配置されており、夫々実質的に同一の形状を有する。Incidentally, also in the embodiment shown in FIGS. 9 and 10, each air supply valve 6, each air supply port 12, each mask wall 21a, and each fresh air guide wall 21C are arranged symmetrically with respect to the plane a-a. , each having substantially the same shape.
従って各給気ボー）１２から流入する新気の強さは実質
的に等しく、しかも燃焼室４内の形状が平面ａ−ａに関
して対称的な形状となっているので各給気ポート１２か
ら燃焼室４内に流入した新気は平面ａ−ａに関して対称
的なループ状の流れを生ずる。その結果、この実施例に
おいても新気はきれいなループ状をなして燃焼室４内を
流れることになり、斯くして機関高負荷運転時には強力
なループ掃気が得られることになる。Therefore, the strength of the fresh air flowing in from each intake air port 12 is substantially equal, and since the shape inside the combustion chamber 4 is symmetrical with respect to the plane a-a, combustion occurs from each intake air port 12. The fresh air flowing into the chamber 4 forms a loop-shaped flow that is symmetrical with respect to the plane a-a. As a result, in this embodiment as well, the fresh air flows in the combustion chamber 4 in a clean loop shape, and thus strong loop scavenging air can be obtained during high load engine operation.
なお、これまで本発明を２サイクルガソリン機関に適用
した場合について説明してきたが本発明を２サイクルデ
イ一ゼル機関に適用しうろことは云うまでもない。Although the present invention has been described so far in the case where it is applied to a two-stroke gasoline engine, it goes without saying that the present invention can also be applied to a two-stroke diesel engine.
排気弁側に位置する給気弁周縁部と弁座間の開口を給気
弁の全開弁期間に亙ってマスク壁により閉鎖しかつ各給
気ポートから実質的に同じ強さで新気を燃焼室内に流入
させ、流入した新気をシリンダ軸線を含む平面に関し対
称的にループ状に流すことによって強力なループ掃気を
確保することができる。The opening between the air intake valve periphery and the valve seat located on the exhaust valve side is closed by a mask wall during the full opening period of the air intake valve, and fresh air is combusted from each air intake port with substantially the same intensity. Strong loop scavenging can be ensured by causing fresh air to flow into the room and flowing in a loop shape symmetrically with respect to a plane including the cylinder axis.
第１図と２サイクル内燃機関の側面断面図、第２図はシ
リンダヘッド内壁面を示す図、第３図はシリンダヘッド
の平面断面図、第４図は給排気弁の開弁期間を示す線図
、第５図は給排気弁の弁リフトおよび排気ポート内の圧
力変化を示す図、第６図は低負荷運転時の作動を説明す
るための図、第７図は高負荷運転時の作動を説明するた
めの図、第８図は別の実施例を示す２サイクル内燃機関
の側面断面図、第９図は第８図のシリンダヘッド内壁面
を示す図、第１０図は作動を説明するための図である。
３・・・シリンダヘッド、 ４・・・燃焼室、５・・
・***部、 ６・・・給気弁、７・・・排気
弁、 ８・・・点火栓、１０、２１ａ・・
・マスク壁、 １２・・・給気ポート。
第
図
排気弁
（Ａ）
隼
図
第
図
第
図
（Ａ）
（Ｂ）
第
図
第
図Figure 1 is a side sectional view of a two-stroke internal combustion engine, Figure 2 is a diagram showing the inner wall surface of the cylinder head, Figure 3 is a plan sectional view of the cylinder head, and Figure 4 is a line showing the opening period of the intake and exhaust valves. Figure 5 is a diagram showing the valve lift of the supply/exhaust valve and pressure changes in the exhaust port, Figure 6 is a diagram to explain the operation during low load operation, and Figure 7 is a diagram showing the operation during high load operation. 8 is a side sectional view of a two-stroke internal combustion engine showing another embodiment, FIG. 9 is a view showing the inner wall surface of the cylinder head of FIG. 8, and FIG. 10 is for explaining the operation. This is a diagram for 3... Cylinder head, 4... Combustion chamber, 5...
・Protuberance, 6... Air supply valve, 7... Exhaust valve, 8... Spark plug, 10, 21a...
・Mask wall, 12...Air supply port. Fig. Exhaust valve (A) Hayabusa Fig. Fig. (A) (B) Fig. Fig.
Claims (1)
を含む平面に関して夫々対称に配置すると共に各給気弁
の形状および各給気ポートの形状を夫々実質的に同一の
形状に形成し、シリンダヘッド内壁面から燃焼室に向け
て延びるマスク壁を各給気弁と排気弁との間に形成して
各マスク壁により排気弁側に位置する各給気弁周縁部と
弁座間の開口を給気弁の全開弁期間に亘って閉鎖し、各
マスク壁を上記シリンダ軸線を含む平面に関して対称に
配置すると共に各マスク壁の形状を実質的に同一の形状
に形成した２サイクル内燃機関。A pair of air supply valves and a pair of air supply ports are arranged symmetrically with respect to a plane including the cylinder axis, and the shape of each air supply valve and the shape of each air supply port are respectively formed to be substantially the same, and the cylinder A mask wall extending from the inner wall surface of the head toward the combustion chamber is formed between each intake valve and the exhaust valve, and each mask wall supplies the opening between the peripheral edge of each intake valve located on the exhaust valve side and the valve seat. A two-stroke internal combustion engine in which a gas valve is closed during a full opening period, each mask wall is arranged symmetrically with respect to a plane including the cylinder axis, and each mask wall is formed into substantially the same shape.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20003588A JPH0733771B2 (en) | 1988-08-12 | 1988-08-12 | 2-cycle internal combustion engine |
| US07/391,786 US4945867A (en) | 1988-08-12 | 1989-08-09 | Two-stroke engine |
| DE3926631A DE3926631C2 (en) | 1988-08-12 | 1989-08-11 | Two-stroke engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20003588A JPH0733771B2 (en) | 1988-08-12 | 1988-08-12 | 2-cycle internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0249923A true JPH0249923A (en) | 1990-02-20 |
| JPH0733771B2 JPH0733771B2 (en) | 1995-04-12 |
Family
ID=16417739
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20003588A Expired - Fee Related JPH0733771B2 (en) | 1988-08-12 | 1988-08-12 | 2-cycle internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0733771B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5140958A (en) * | 1990-06-27 | 1992-08-25 | Toyota Jidosha Kabushiki Kaisha | Two-stroke engine |
-
1988
- 1988-08-12 JP JP20003588A patent/JPH0733771B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5140958A (en) * | 1990-06-27 | 1992-08-25 | Toyota Jidosha Kabushiki Kaisha | Two-stroke engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0733771B2 (en) | 1995-04-12 |
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