JPS63253114A - Exhaust system for two-cycle engine - Google Patents
Exhaust system for two-cycle engineInfo
- Publication number
- JPS63253114A JPS63253114A JP8548587A JP8548587A JPS63253114A JP S63253114 A JPS63253114 A JP S63253114A JP 8548587 A JP8548587 A JP 8548587A JP 8548587 A JP8548587 A JP 8548587A JP S63253114 A JPS63253114 A JP S63253114A
- Authority
- JP
- Japan
- Prior art keywords
- exhaust
- port
- engine
- divided
- ports
- 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
- 239000000203 mixture Substances 0.000 abstract description 15
- 238000002485 combustion reaction Methods 0.000 description 17
- 239000000446 fuel Substances 0.000 description 14
- 230000002000 scavenging effect Effects 0.000 description 11
- 235000014676 Phragmites communis Nutrition 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 239000002184 metal Substances 0.000 description 4
- 238000005192 partition Methods 0.000 description 3
- 238000011144 upstream manufacturing Methods 0.000 description 3
- 238000007664 blowing Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 210000002837 heart atrium Anatomy 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 210000003437 trachea Anatomy 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
- Characterised By The Charging Evacuation (AREA)
Abstract
Description
【発明の詳細な説明】
Ａ６発明の目的
（１）産業上の利用分野
本発明は２サイクルエンジンの排気系に関するものであ
る。DETAILED DESCRIPTION OF THE INVENTION A6 Object of the Invention (1) Field of Industrial Application The present invention relates to an exhaust system for a two-stroke engine.
（２）従来の技術
従来２サイクルエンジンにおいて、シリンダブロックに
一体に形成され、内端をシリンダポアに開口した排気ポ
ートと、該排気ポートの外端に接続される排気管とより
なる排気系内は分割されないのが一般的である（自動車
工学全書、１５モータスポーツ、二輪自動車参照）。(2) Prior art In a conventional two-stroke engine, the inside of the exhaust system consists of an exhaust port that is integrally formed in the cylinder block and has an inner end open to the cylinder pore, and an exhaust pipe that is connected to the outer end of the exhaust port. Generally, it is not divided (see Automotive Engineering Complete Book, 15 Motor Sports, Two-Wheel Vehicles).
（３）発明が解決しようとする問題点
−ｉに２サイクルエンジンでは、ピストンの下降する掃
気行程時に排ガスが排気系より燃焼室へ逆流する“排ガ
ス逆流現象″やピストンの上昇する圧縮行程時に掃気ポ
ートから排気ポートへ混合気が吹抜ける“吹抜は現象″
を生じ、これらの現象は２サイクルエンジンの性能上好
ましくない。(3) Problems to be solved by the invention - In two-cycle engines, there is an "exhaust gas backflow phenomenon" in which exhaust gas flows back from the exhaust system into the combustion chamber during the scavenging stroke when the piston goes down, and when the scavenging occurs during the compression stroke when the piston goes up. “Atrium is a phenomenon” where the air-fuel mixture blows from the port to the exhaust port
These phenomena are unfavorable in terms of the performance of the two-stroke engine.
そこで本出願人はかかる現象を防止、もしくは低減すべ
く排気ポートにシリンダポアから排気通路へのみ排ガス
の流れを許容するり−ド弁を設けたものを提案した。Therefore, in order to prevent or reduce such a phenomenon, the present applicant has proposed a system in which an exhaust port is provided with a leak valve that allows exhaust gas to flow only from the cylinder pore to the exhaust passage.
ところがこのものでは排気抵抗、特にエンジンの高負荷
運転時における排気抵抗が多少とも増大傾向になるとい
う別の問題点を生じた。However, this method has caused another problem in that the exhaust resistance, especially when the engine is operated under high load, tends to increase to some extent.
そこで本発明は前記問題点をすべて解決できるよにした
構成簡単な２サイクルエンジンの排気系を提供すること
を目的とするものである。SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an exhaust system for a two-stroke engine with a simple configuration that can solve all of the above-mentioned problems.
Ｂ９発明の構成
＋１１ 問題点を解決するための手段本発明によれば
、前記目的達成のためシリンダブロックに一体に形成さ
れ、内端をピストンの摺合されるシリンダポアに開口し
た排気ポートと、この排気ポートの外端に接続される非
気管とを含む２サイクルエンジンの排気系において、前
記排気系の排気ポート内を複数の分割ポートに分割し、
それらの分割ポートのうちの少なくとも一つに前記シリ
ンダポアから前記排気管への排気の流れのみを許容する
逆止弁を設け、残余の分割ポートにエンジンの低負荷運
転時に閉弁制御され、その高負荷運転時に開弁制御され
る制御弁を設ける。B9 Configuration of the Invention +11 Means for Solving Problems According to the present invention, in order to achieve the above-mentioned object, an exhaust port is formed integrally with the cylinder block and has an inner end opening into a cylinder pore into which a piston is slidably connected, and an exhaust port is provided. In a two-stroke engine exhaust system including a non-trachea connected to an outer end of the port, the exhaust port of the exhaust system is divided into a plurality of split ports,
At least one of the divided ports is provided with a check valve that allows only the flow of exhaust gas from the cylinder pore to the exhaust pipe, and the remaining divided ports are controlled to close during low-load operation of the engine. A control valve is provided that is controlled to open during load operation.
（２）作 用
２サイクルエンジンの低負荷運転時には、排気ポートの
複数の分割ポートの少なくとも一つは逆止弁によって排
ガスの逆流が阻止されるとともに残余の分割ポートは制
御弁によって閉じられ、その結果排ガスの逆流が防止さ
れ、また混合気の吹き抜けも低減される。(2) Function During low-load operation of a two-stroke engine, at least one of the plurality of divided ports of the exhaust port is blocked by a check valve from backflowing exhaust gas, and the remaining divided ports are closed by a control valve. As a result, backflow of exhaust gas is prevented and blow-by of the air-fuel mixture is also reduced.
また２サイクルエンジンの高負荷運転時には、制御弁を
開弁じて排気抵抗を低減して排気効率を高め、エンジン
の高負荷運転域の高出力性能を維持することができる。Furthermore, during high-load operation of the two-cycle engine, the control valve is opened to reduce exhaust resistance and improve exhaust efficiency, thereby maintaining high output performance in the high-load operation range of the engine.
（３）実施例
以下、第１図により本発明の第１実施例について説明す
る。(3) Example Hereinafter, a first example of the present invention will be described with reference to FIG.
この実施例は本発明排気系が自動二輪車用パワーユニッ
トＰｕの２サイクルエンジン已に実施される。In this embodiment, the exhaust system of the present invention is implemented in a two-stroke engine of a power unit Pu for a motorcycle.
パワーユニットＰｕは、エンジン本体１が斜めに１頃斜
される２サイクルエンジンＥと、諜亥エンジンＥの下部
に一体的に組付けられたミッションＭとより構成される
。エンジン本体１はシリンダブロック２と、そのデツキ
面上に結着されるシリンダへンド３と、前記シリンダブ
ロック２の下部に一体に組付けられるクランクケース４
とより構成される。シリンダブロック２に形成したシリ
ンダポア５にはピストン６が摺動自在に嵌合される。The power unit Pu is composed of a two-cycle engine E in which the engine body 1 is tilted at an angle of about 1, and a transmission M integrally assembled to the lower part of the spy engine E. The engine body 1 includes a cylinder block 2, a cylinder head 3 fixed to the deck surface of the cylinder block 2, and a crankcase 4 integrally assembled to the lower part of the cylinder block 2.
It consists of A piston 6 is slidably fitted into a cylinder pore 5 formed in the cylinder block 2.
ピストン６のピストンピン６１にはコンロッド７の小端
部が連結され、該コンロッド７の大端部はクランクケー
ス４に回転自在に支承されるクランク軸８のクランクビ
ン８．に連結される。シリンダへラド３の、ピストン６
と対面する下面には燃焼室９が形成され、シリンダへラ
ド３の頂部にはスパークプラグ１０が螺着され、該プラ
グ１０の電極１０．は燃焼室９内に口ｎんでいる。A small end of a connecting rod 7 is connected to a piston pin 61 of the piston 6, and a large end of the connecting rod 7 is connected to a crank pin 8 of a crankshaft 8 rotatably supported by the crankcase 4. connected to. cylinder rad 3, piston 6
A combustion chamber 9 is formed on the lower surface facing the cylinder head 3. A spark plug 10 is screwed onto the top of the cylinder head 3, and an electrode 10 of the plug 10. is located inside the combustion chamber 9.
前記シリンダボア５には、該ボア５内に混合気を導入す
るための吸気系Ｉｎｓおよびシリンダボア５内の排ガス
を排出するための排気系Ｅｘが接続される。吸気系Ｉｎ
は、シリンダブロック２に一体に形成され、内端をシリ
ンダボア５に連通させた吸気ポート１１と、この吸気ボ
ー）１１の開口外端に接続される吸気管１２と、この吸
気管１２の開口外端に連設されるキャブレタ１３とより
構成され、前記吸気ポートｌｌ内には、従来公知のリー
ド弁１４が設けられ、このリード弁１４シよ、キャプレ
ク１３からの混合気が、シリンダブロック２側へのみ流
れるのを許容する。The cylinder bore 5 is connected to an intake system Ins for introducing an air-fuel mixture into the bore 5 and an exhaust system Ex for discharging exhaust gas from the cylinder bore 5. Intake system In
is an intake port 11 integrally formed in the cylinder block 2 and whose inner end communicates with the cylinder bore 5; an intake pipe 12 connected to the open outer end of the intake port 11; A conventionally known reed valve 14 is provided in the intake port 11, and the air-fuel mixture from the carburetor 13 is transferred to the cylinder block 2 side through the reed valve 14. Allow flow only to.
また前記排気系Ｅｘは、シリンダブロック２に一体に形
成され、内端をシリンダボア５にＪ！！通させた排気ポ
ート１５と、この排気ポート１５の開口外端に金属製シ
ート部材１６を介して接続される排気管１７とより構成
されている。前記排気ポート１５内は、その略全長にわ
たりその縦軸線に沿って仕切壁２４が設けられ、この仕
切壁２４によって上部分割ポート１５．と下部分割ポー
ト１５□とに分割される。そして上部分割ポート１５、
および下部分割ポート１５□の下流端は、それぞれ前記
シート部材１６に形成した上部通孔１６１、および下部
通孔１６□を介して排気管１７内に連通される。前記上
部分割ボー）１５．の下流端に連通ずる、シート部材１
６の上部通孔１６゜にはリード弁よりなる逆止弁１８が
複数のビス１９により取付けられる。この逆止弁１８は
燃焼室９からの排ガスの排気管１７への流れのみを許容
する。また前記下部分割ポート１５！の途中にはバタフ
ライ弁よりなる制御弁２０が、該下部分割ポート１５．
に回転自在に横架された弁軸２１にビス２２を以て開閉
自在に取付けられ、この制御弁２０はエンジンＥの低負
荷運転時に閉弁され、またその高負荷運転時に開弁され
るように制御され、例えばキャブレタ１３のスロットレ
バー、エンジンＥの吸気負圧等に応動して開閉作動され
るように構成される。Further, the exhaust system Ex is formed integrally with the cylinder block 2, and its inner end is connected to the cylinder bore 5. ! It consists of an exhaust port 15 that is passed through, and an exhaust pipe 17 that is connected to the open outer end of the exhaust port 15 via a metal sheet member 16. A partition wall 24 is provided along the longitudinal axis of the exhaust port 15 over substantially its entire length, and the partition wall 24 separates the upper divided port 15. and a lower divided port 15□. and upper split port 15,
The downstream end of the lower divided port 15□ is communicated with the exhaust pipe 17 through an upper passage hole 161 and a lower passage hole 16□ formed in the sheet member 16, respectively. 15. Sheet member 1 communicating with the downstream end of
A check valve 18, which is a reed valve, is attached to the upper through hole 16° of 6 with a plurality of screws 19. This check valve 18 only allows exhaust gas from the combustion chamber 9 to flow into the exhaust pipe 17. Also, the lower divided port 15! A control valve 20 consisting of a butterfly valve is located in the middle of the lower divided port 15.
The control valve 20 is attached to a valve shaft 21 rotatably horizontally mounted on the engine E with screws 22 so as to be openable and closable. It is configured to be opened and closed in response to, for example, the slot lever of the carburetor 13, the intake negative pressure of the engine E, etc.
また前記シリンダブロック２には、そのシリンダ部の周
方向で前記排気ポート１５の両側に複数の掃気ポート２
３が形成され、これらの掃気ポート２３の上端の出口２
３．は燃焼室９に開口し、またそれらの下端の入口２３
□はクランクケース４内に連通ずる。Further, the cylinder block 2 has a plurality of scavenging ports 2 on both sides of the exhaust port 15 in the circumferential direction of the cylinder portion.
3 are formed, and the outlet 2 at the upper end of these scavenging ports 23
3. open into the combustion chamber 9 and also have an inlet 23 at their lower end.
□ communicates with the inside of the crankcase 4.
ピストン６の上昇行程では前記複数の掃気ポート２３下
端の入口２３．が開口され、この開口によればキャブレ
タ１３で生成された混合気が、開弁されたリート弁１４
を通過してクランクケース４内に導入される。またピス
トン６の下降行程の後半では、排気ボー１−１５および
掃気ポート２３が順次に開口し、これらの順次開口によ
れば排ガスが燃焼室９から排気ポート１５へ排出された
のち、クランクケース４内からの圧縮混合気が掃気ポー
ト２３を通して燃焼室９に噴入される。During the upward stroke of the piston 6, the inlets 23. is opened, and according to this opening, the air-fuel mixture generated in the carburetor 13 is transferred to the opened Riet valve 14.
It passes through and is introduced into the crankcase 4. In addition, in the latter half of the downward stroke of the piston 6, the exhaust bows 1-15 and the scavenging port 23 open sequentially. According to these sequential openings, the exhaust gas is discharged from the combustion chamber 9 to the exhaust port 15, and then the exhaust gas is discharged from the combustion chamber 9 to the exhaust port 15. The compressed air-fuel mixture from within is injected into the combustion chamber 9 through the scavenging port 23.
ところでエンジンＥの低負荷運転域では、バタフライ弁
よりなる制御弁２０は前述のように閉弁制御されるので
、排気ポート１５の下部分割ポート１５□は閉路されて
おり、燃焼室９がら排出される排ガスは専ら上部分割ポ
ート１５１および逆止弁１８を通って排気管１７へと排
出される。By the way, in the low-load operating range of the engine E, the control valve 20, which is a butterfly valve, is controlled to close as described above, so the lower divided port 15□ of the exhaust port 15 is closed, and the air is discharged from the combustion chamber 9. The exhaust gas is discharged exclusively through the upper split port 151 and the check valve 18 to the exhaust pipe 17.
またエンジンＥの高負荷運転域では、制御弁２０は開弁
制御されるので、排気ポート１５の下部分割ポート１５
２は開路され、燃焼室９から排出される排ガスは上部分
割ポート１５．より逆止弁１８、および下部分割ポート
１５□より制御弁２０を通って排気管１７へと排出され
る。In addition, in the high-load operating range of the engine E, the control valve 20 is controlled to open, so the lower divided port 15 of the exhaust port 15
2 is opened, and the exhaust gas discharged from the combustion chamber 9 is passed through the upper divided port 15. It is discharged from the check valve 18 and the lower divided port 15□ to the exhaust pipe 17 through the control valve 20.
ところで一般に２サイクルエンジンの運転において、ピ
ストンの下降行程で開口した排気ポートが、ピストンの
上昇行程で再び閉じるまでの間で、燃焼室から排気管へ
と流れる排ガス流は膨張室を有する排気管内で反射され
、正圧、および負圧を交互に繰り返す圧力波となって、
排気ポートへと波及し、この圧力波により、排気管へ排
出された排ガスの一部は排気ポートから燃焼室へと押し
戻され、掃気ポートから燃焼室へ噴出された混合気を希
釈化する所謂“排ガス逆流現象１を発生させ、さらにピ
ストンの上昇行程において排気ポートを閉じる以前に掃
気ポートから燃焼室へ噴入した混合気がそのまま排気ポ
ートに流出する、所謂“吹き抜は現象“を発生する。By the way, in general, when operating a two-stroke engine, the exhaust gas flow from the combustion chamber to the exhaust pipe flows through the exhaust pipe, which has an expansion chamber, until the exhaust port opens during the downward stroke of the piston and closes again during the upward stroke of the piston. It is reflected and becomes a pressure wave that alternately repeats positive and negative pressure,
This pressure wave spreads to the exhaust port, and due to this pressure wave, a part of the exhaust gas discharged to the exhaust pipe is pushed back from the exhaust port to the combustion chamber, diluting the air-fuel mixture injected into the combustion chamber from the scavenging port. This causes the exhaust gas backflow phenomenon 1, and also causes the so-called "air blow phenomenon" in which the air-fuel mixture injected from the scavenging port into the combustion chamber directly flows out to the exhaust port before the exhaust port is closed during the upward stroke of the piston.
而してエンジンの低負荷運転域では燃焼室内への混合気
の流入流量が少なく、その流入速度も遅いので、排ガス
の圧力波による前記“排ガス逆流現象”が一層顕著とな
る傾向となるが、この実施例ではエンジンＥの低負荷運
転域では排気ポート１５の、上記分割ポート１５．は逆
止弁１８が設けられ、また下部分割ポート１５□は制御
弁２０によって閉じられるので、排ガスの逆流が阻止さ
れ前記“排ガス逆流現象”の発生が未然に防止される。In the low-load operating range of the engine, the flow rate of the air-fuel mixture into the combustion chamber is small and its inflow speed is slow, so the above-mentioned "exhaust gas backflow phenomenon" caused by exhaust gas pressure waves tends to become more pronounced. In this embodiment, in the low load operating range of the engine E, the exhaust port 15 is connected to the split port 15. Since a check valve 18 is provided and the lower divided port 15□ is closed by a control valve 20, backflow of exhaust gas is prevented and the occurrence of the above-mentioned "exhaust gas backflow phenomenon" is prevented.
しかもピストン６の上昇行程では前記逆止弁１８および
制御弁２０よりも上流の排気ポート１５内の圧力は、正
圧に維持されるため、前記混合気の“吹き抜は現象”の
発生も可及的に低減される。Moreover, during the upward stroke of the piston 6, the pressure in the exhaust port 15 upstream of the check valve 18 and the control valve 20 is maintained at a positive pressure, so the "blowing phenomenon" of the air-fuel mixture may occur. is effectively reduced.
またエンジンＥの高負荷運転域では、燃焼室９内への混
合気の流入流量が多く、しかもその流速も早いので前記
低負荷運転域よりも“排ガス逆流現象″の発生割合が少
なくなり、本実施例では制御弁２０を開弁制御して下部
分割ポート１５ｔを開放状態とし、制御弁２０の存在に
よるも排気抵抗を可及的に低減して排気効率を高めエン
ジンの高負荷運転時の高出力性能を維持することができ
る。In addition, in the high-load operating range of the engine E, the flow rate of the air-fuel mixture into the combustion chamber 9 is large, and the flow velocity is also fast, so the occurrence rate of the "exhaust gas backflow phenomenon" is lower than in the low-load operating range, and this is true. In the embodiment, the control valve 20 is controlled to open so that the lower divided port 15t is in an open state, and the presence of the control valve 20 reduces exhaust resistance as much as possible to improve exhaust efficiency and reduce high pressure during high-load operation of the engine. Output performance can be maintained.
第２図には本発明の第２実施例が示される。この第２実
施例において、第１実施例と同一部材には同一符号が付
される。FIG. 2 shows a second embodiment of the invention. In this second embodiment, the same members as in the first embodiment are given the same reference numerals.
この第２実施例では排気ポート１５の上部分割ポート１
５．にバタフライ弁よりなる制御弁２０を、またその下
部分割ポート１５！にリード弁よりなる逆止弁１８を設
けた点で前記第１実施例と相違しており、他の構成にお
いて前記第１実施例と同じである。すなわち排気ポート
１５の上部分割ポート１５１の途中には弁軸２１が回転
自在に横架されこの弁軸２１にビス２２を以て制御弁２
０が取付けられる。また下部分割ポート１５□の下流端
に連通される金属製シート部材１６の下部通孔１６□に
は、前記逆止弁１８がビス１９を以て取付けられる。In this second embodiment, the upper divided port 1 of the exhaust port 15
5. Control valve 20 consisting of a butterfly valve, and its lower divided port 15! The second embodiment differs from the first embodiment in that a check valve 18 made of a reed valve is provided at the top, and the other configurations are the same as the first embodiment. That is, a valve shaft 21 is rotatably installed horizontally in the middle of the upper divided port 151 of the exhaust port 15, and the control valve 2 is connected to this valve shaft 21 with a screw 22.
0 is attached. Further, the check valve 18 is attached with a screw 19 to the lower through hole 16□ of the metal sheet member 16, which communicates with the downstream end of the lower divided port 15□.
而してこの第２実施例も前記第１実施例と同等の効果を
達成するが、加えてエンジンＥの高負荷運転時には、逆
止弁１８の存する下部分割ポート１５□が、制御弁２０
の開弁された上部分割ポート１５１に比べて高い正圧に
保持されること、および掃気ポート２３は排気ポート１
５よりも下位にあることとの理由により掃気ポート２３
からの吹き抜はガスの多くは下部分割ポート１５□に流
れる傾向にあるが、該下部分割ポート１５□内が逆止弁
１８の抵抗で上部分割ポート１５．よりも高い正圧に維
持されることからエンジンＥの高負荷運転域での混合気
の吹き抜は抑制効果が高められる。This second embodiment also achieves the same effect as the first embodiment, but in addition, during high-load operation of the engine E, the lower divided port 15□ where the check valve 18 is located is connected to the control valve 20.
The scavenging port 23 is maintained at a higher positive pressure than the open upper divided port 151, and the scavenging port 23 is
Scavenging port 23 because it is lower than 5.
Most of the gas tends to flow into the lower divided port 15□, but due to the resistance of the check valve 18, the inside of the lower divided port 15□ flows into the upper divided port 15. Since the pressure is maintained at a higher positive pressure than the engine E, the effect of suppressing air-fuel mixture blow-out in the high-load operating range of the engine E is enhanced.
第３．４図には本発明の第３実施例が示される。A third embodiment of the invention is shown in Figure 3.4.
この第３実施例においても第１実施例と同一部材は同一
符号が付される。In this third embodiment as well, the same members as in the first embodiment are given the same reference numerals.
この第３実施例は排気ポート１５の構成において前記第
１．第２実施例と相違している。This third embodiment has the configuration of the exhaust port 15 as described above. This is different from the second embodiment.
排気ポート１５内は、その上流端から下流端にわたって
その縦方向に略平方に延設される左、右２枚の仕切壁２
４．．２４□によって、通路断面積の大きい中央分割ポ
ート１５３と、それよりも通路断面積の小さい左、右分
割ボー）１５．．１５、とに分割される。そしてそれら
のポート１５ｓ、１５−および１５．は金属製シート部
材１６の、中央通孔１６．および左、右通孔１６．，１
６、を通して排気ポート１５に連通される。Inside the exhaust port 15, there are two partition walls 2 on the left and right extending vertically in a substantially square shape from its upstream end to its downstream end.
4. ．． 24□, the central divided port 153 has a large passage cross-sectional area, and the left and right divided ports have a smaller passage cross-sectional area)15. ．． It is divided into 15. and those ports 15s, 15- and 15. is the central through hole 16. of the metal sheet member 16. and left and right through holes 16. ,1
6, and communicates with the exhaust port 15 through the exhaust port 15.
前記中央分割ポート１５．の途中にはバタフライ弁より
なる制御弁２０が開閉自在に設けられる。Said center split port 15. A control valve 20, which is a butterfly valve, is provided in the middle so that it can be opened and closed.
すなわち中央分割ポート１５．に回転自在に横架される
弁軸２１には制御弁２０がビス２２によって取付けられ
る。制御弁２０はエンジンＥの低負荷運転域で閉じられ
、またその高負荷運転域で開（ように制御され、スロッ
トル弁、吸気負圧等の負荷制御ファクタに応動して作動
される。That is, the central split port 15. A control valve 20 is attached by screws 22 to a valve shaft 21 which is rotatably suspended horizontally. The control valve 20 is controlled to be closed in a low-load operating range of the engine E and opened in a high-load operating range, and is operated in response to load control factors such as the throttle valve and intake negative pressure.
また前記左、右分割ポート１５４．１５ｓの下流端には
、燃焼室９より排気管１７への排ガスの流れを許容する
リード弁よりなる左、右逆止弁１８＋、１８□が設けら
れる。すなわち排気ポート１５の下流側端面と排気管１
７の上流側端面間に介在される金属製シート部材１６の
左側にはビス１９、を以て左逆止弁１８．が、またその
右側にはビス１９ｇを以て右逆止弁１８□がそれぞれ取
付けられる。Furthermore, left and right check valves 18+ and 18□, which are reed valves that allow exhaust gas to flow from the combustion chamber 9 to the exhaust pipe 17, are provided at the downstream ends of the left and right split ports 154.15s. That is, the downstream end face of the exhaust port 15 and the exhaust pipe 1
A screw 19 is attached to the left side of the metal sheet member 16 interposed between the upstream end surfaces of the left check valve 18.7. However, right check valves 18□ are each attached to the right side using screws 19g.
第３，４図に示す第３実施例も前記第１．第２実施例と
同じ作用効果を奏するが、加えて左、右分割ポー）１５
４．１５ｓにそれぞれ左、右逆止弁１Ｂ、、１８□を設
けたことにより、排気ポート１５の左、右両側端に多く
流れる混合気の吹き抜けを抑制する効果がある。The third embodiment shown in FIGS. 3 and 4 is also similar to the first embodiment. It has the same effect as the second embodiment, but in addition, left and right split ports) 15
By providing the left and right check valves 1B, 18□ at 4.15s, respectively, there is an effect of suppressing blow-by of the air-fuel mixture that flows to both left and right ends of the exhaust port 15.
Ｃ１発明の効果
以上のように本発明によれば、２サイクルエンジンにお
いて、その排気系の排気ポート内を複数の分割ポートに
分割し、それらの分割ポートのうちの少なくとも一つに
シリンダボアから排気管への排気の流れのみを許容する
逆止弁を設け、残余の分割ポートにエンジンの低負荷運
転時に閉弁制御され、その高負荷運転時に開弁制御され
る制御弁を設けたので、２サイクルエンジンの性能上、
マイナス要因となる“排ガス逆流現象”および混合気の
“吹き抜は現象”の発生を何れも可及的に低減し、しか
も高負荷運転域での高い排気効率を維持することができ
全体として２サイクルエンジンの出力性能を大幅に向上
させることができる。C1 Effects of the invention As described above, according to the present invention, in a two-stroke engine, the exhaust port of the exhaust system is divided into a plurality of divided ports, and at least one of the divided ports is connected to the exhaust pipe from the cylinder bore. A check valve that only allows the flow of exhaust gas to Due to engine performance,
It is possible to reduce as much as possible the occurrence of negative factors such as "exhaust gas backflow phenomenon" and "blowing phenomenon" of the air-fuel mixture, while maintaining high exhaust efficiency in high-load operating ranges, resulting in an overall improvement of 2. The output performance of cycle engines can be significantly improved.
第１図は本発明の第１実施例の要部縦断側面図、第２図
は本発明の第２実施例の要部縦断側面図、第３，４図は
本発明の第３実施例を示すもので、第３図はその要部縦
断側面図、第４図は第３図■−■線に沿う部分断面図で
ある。
Ｅｘ・・・排気系
２・・・シリンダブロック、５・・・シリンダボア、６
・・・ピストン、１５・・・排気ポート、１５．．１５
□、１５３，１５４，１５５・・・分割ポートとしての
上部、下部、中央、左、右分割ポート、１７・・・排気
管、１８・・・逆止弁FIG. 1 is a longitudinal sectional side view of the main part of the first embodiment of the present invention, FIG. 2 is a longitudinal sectional side view of the main part of the second embodiment of the invention, and FIGS. FIG. 3 is a longitudinal sectional side view of the main part thereof, and FIG. 4 is a partial sectional view taken along line 1--2 in FIG. 3. Ex...Exhaust system 2...Cylinder block, 5...Cylinder bore, 6
...Piston, 15...Exhaust port, 15. ．． 15
□, 153, 154, 155... Upper, lower, center, left, right split ports as split ports, 17... Exhaust pipe, 18... Check valve
Claims (1)
トン（６）の摺合されるシリンダボア（５）に開口した
排気ポート（１５）と、この排気ポート（１５）の外端
に接続される排気管（１７）とを含む２サイクルエンジ
ン（Ｅ）の排気系（Ｅｘ）において、前記排気系（Ｅｘ
）の排気ポート（１５）内を複数の分割ポートに分割し
、それらの分割ポートのうちの少なくとも一つに前記シ
リンダボア（５）から前記排気管（１７）への排気の流
れのみを許容する逆止弁（１８）を設け、残余の分割ポ
ートにエンジン（Ｅ）の低負荷運転時に閉弁制御され、
その高負荷運転時に開弁制御２サイクルエンジンの排気
系。An exhaust port (15) that is integrally formed in the cylinder block (2) and has an inner end open to the cylinder bore (5) into which the piston (6) is slid, and an exhaust that is connected to the outer end of the exhaust port (15). In an exhaust system (Ex) of a two-stroke engine (E) including a pipe (17), the exhaust system (Ex)
) is divided into a plurality of divided ports, and at least one of the divided ports allows only the flow of exhaust from the cylinder bore (5) to the exhaust pipe (17). A stop valve (18) is provided, and the remaining divided ports are controlled to close during low-load operation of the engine (E).
The exhaust system of a 2-cycle engine that controls valve opening during high-load operation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8548587A JPS63253114A (en) | 1987-04-07 | 1987-04-07 | Exhaust system for two-cycle engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8548587A JPS63253114A (en) | 1987-04-07 | 1987-04-07 | Exhaust system for two-cycle engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63253114A true JPS63253114A (en) | 1988-10-20 |
Family
ID=13860219
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8548587A Pending JPS63253114A (en) | 1987-04-07 | 1987-04-07 | Exhaust system for two-cycle engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63253114A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4969329A (en) * | 1989-05-05 | 1990-11-13 | General Motors Corporation | Two cycle engine with exhaust emission control |
| US4969330A (en) * | 1989-06-21 | 1990-11-13 | General Motors Corporation | Two cycle engine catalytic emission control |
| US4998512A (en) * | 1989-02-01 | 1991-03-12 | Yamaha Hatsudoki Kabushiki Kaisha | Exhaust port control system for two stroke engine |
| US5361732A (en) * | 1991-11-21 | 1994-11-08 | Kioritz Corporation | Two cycle internal combustion engine |
-
1987
- 1987-04-07 JP JP8548587A patent/JPS63253114A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4998512A (en) * | 1989-02-01 | 1991-03-12 | Yamaha Hatsudoki Kabushiki Kaisha | Exhaust port control system for two stroke engine |
| US4969329A (en) * | 1989-05-05 | 1990-11-13 | General Motors Corporation | Two cycle engine with exhaust emission control |
| US4969330A (en) * | 1989-06-21 | 1990-11-13 | General Motors Corporation | Two cycle engine catalytic emission control |
| US5361732A (en) * | 1991-11-21 | 1994-11-08 | Kioritz Corporation | Two cycle internal combustion engine |
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