JPS627920A - Two-cycle engine - Google Patents

Two-cycle engine

Info

Publication number
JPS627920A
JPS627920A JP14464585A JP14464585A JPS627920A JP S627920 A JPS627920 A JP S627920A JP 14464585 A JP14464585 A JP 14464585A JP 14464585 A JP14464585 A JP 14464585A JP S627920 A JPS627920 A JP S627920A
Authority
JP
Japan
Prior art keywords
scavenging
piston
exhaust
port
flow
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
Application number
JP14464585A
Other languages
Japanese (ja)
Inventor
Yoshikuni Yamauchi
山内　良訓
Yoshinobu Yashiro
矢代　善伸
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yamaha Motor Co Ltd
Original Assignee
Yamaha Motor Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Yamaha Motor Co Ltd filed Critical Yamaha Motor Co Ltd
Priority to JP14464585A priority Critical patent/JPS627920A/en
Publication of JPS627920A publication Critical patent/JPS627920A/en
Pending legal-status Critical Current

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 
    • F02F1/18—Other cylinders
    • F02F1/22—Other cylinders characterised by having ports in cylinder wall for scavenging or charging
    • 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)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)

Abstract

PURPOSE:To prevent the blow-by in the captioned engine, by providing the projection inclined to an exhaust port, on the top part of a piston and thereby introducing scavenging flow in the side edge of the projection part while regulating exhaust in the projection part. CONSTITUTION:A projection part 13 is provided on the top part of a piston 5 of the captioned engine, being inclined to an exhaust port 10 provided around a cylinder. This projection 13 is made to lower as approaching center of the piston while the side edge of the projection part 13 is made to be risen so as to introduce scavenging flow. When exhaust is performed from an exhaust port 10 by lowering the piston 5, exhaust flow is upward introduced while, at the time of the following scavenging stroke where a scavenging port 11 is opened, the scavenging flow is made to introducibly flow in the side edge 13a so that the scavenging flow is not mixed with the exhaust flow and thereby it is possible to prevent blow-by.

Description

【発明の詳細な説明】 〔発明の技術分野〕 本発明は２サイクルエンジンに関するものである。[Detailed description of the invention] [Technical field of invention] The present invention relates to a two-stroke engine.

〔従来技術〕[Prior art]

２サイクルエンジンでは、アイドリング時に排気する排
ガス中に未燃ガス（ＨＣ）を含んでいる。これは、アイ
ドリング時に掃気ポートからシリンダ内に押し込まれる
掃気流が、排気ポートへ吹き抜けてしまう吹き抜は現象
が起こるためである。In a two-stroke engine, the exhaust gas exhausted during idling contains unburned gas (HC). This is because a phenomenon occurs in which the scavenging air flow pushed into the cylinder from the scavenging port during idling blows through to the exhaust port.

このようなアイドリング時の掃気流の吹き抜は防止対策
としては、排気ポート上端と掃気ポート上端との離間距
離（排気リード）を短くすればよいことが知られている
。このため、従来の２サイクルエンジンでは、シリンダ
内壁面の掃気ポートの排気リードを短くするように設定
して掃気タイミングを調整するようにしていたが、これ
だけでは吹き抜は防止効果は必ずしも十分とはいえなか
った。It is known that a measure to prevent such blow-out of the scavenging air flow during idling is to shorten the distance (exhaust lead) between the upper end of the exhaust port and the upper end of the scavenging port. For this reason, in conventional two-stroke engines, the scavenging timing was adjusted by shortening the exhaust lead of the scavenging port on the inner wall of the cylinder, but this alone was not necessarily sufficient to prevent blow-by air. I couldn't say it.

（発明の目的〕 本発明の目的は、アイドリング時の掃気流の吹抜けを防
止し、排ガス中の未燃ガス量を低減し、燃費を向上する
ようにした２サイクルエンジンを提供することにある。(Object of the Invention) An object of the present invention is to provide a two-stroke engine that prevents scavenging airflow from blowing through during idling, reduces the amount of unburned gas in exhaust gas, and improves fuel efficiency.

〔発明の構成〕[Structure of the invention]

上記目的を達成する本発明は、シリンダ内周面に掃気ポ
ートと排気ポートを開口させた２サイクルエンジンにお
いて、ピストン上面の前記排気ポートに対応する周縁位
置に突起部を設け、この突起部の側面を前記掃気ポート
からの掃気流をピストン上面の内側へ案内するガイド面
に形成したことを特徴とするものである。To achieve the above object, the present invention provides a two-stroke engine in which a scavenging port and an exhaust port are opened on the inner circumferential surface of the cylinder, a protrusion is provided on the upper surface of the piston at a circumferential position corresponding to the exhaust port, and a protrusion is provided on the side surface of the protrusion. is formed on a guide surface that guides the scavenging air flow from the scavenging air port to the inside of the upper surface of the piston.

〔実施例〕〔Example〕

以下、本発明を図に示す実施例により説明する。 The present invention will be explained below with reference to embodiments shown in the drawings.

■はシリンダヘッド、２はシリンダ、３はクランクケー
スである。シリンダヘッド１のシリンダ２上方に対応す
る位置には点火栓４が取付けられている。シリンダ２に
はピストン５が挿入され、このピストン５の往復運動に
より、クランクケース３内のクランク軸６が回転駆動さ
れるようになっている。2 is the cylinder head, 2 is the cylinder, and 3 is the crankcase. An ignition plug 4 is attached to the cylinder head 1 at a position corresponding to the upper part of the cylinder 2. A piston 5 is inserted into the cylinder 2, and the reciprocating motion of the piston 5 rotates a crankshaft 6 within the crankcase 3.

シリンダ２の一方の側部には吸気通路７が設けられ、ま
た反対側に排気通路８が設けられている。シリンダ２の
内周面には、吸気通路７に連通ずる３個の吸気ボー）９
．９．９が、下部と中間部にそれぞれ開口し、また排気
通路８に連通ずる排気ポート１０が中間部に開口してい
る。また、上記吸気ポート９と排気ポート１０との間の
中間域には、クランクケース３に連通する主掃気ボー）
１１．１１と補助掃気ポート１２．１２とが開口してい
る。これら主掃気ポート１１と補助掃気ポート１２とは
、吸気ポート９と排気ポート１０との対角線を挟んで左
右対称に配置され、かつ主掃気ポート１１は排気ポート
１０に近い側に、補助掃気ポート１２は遠い側にそれぞ
れ配置されている。An intake passage 7 is provided on one side of the cylinder 2, and an exhaust passage 8 is provided on the opposite side. On the inner peripheral surface of the cylinder 2, there are three intake bows) 9 that communicate with the intake passage 7.
．． 9.9 are opened at the lower part and the middle part, respectively, and an exhaust port 10 communicating with the exhaust passage 8 is opened at the middle part. In addition, in the intermediate region between the intake port 9 and the exhaust port 10, there is a main scavenging air bow communicating with the crankcase 3.
11.11 and an auxiliary scavenging port 12.12 are open. The main scavenging port 11 and the auxiliary scavenging port 12 are arranged symmetrically across the diagonal line between the intake port 9 and the exhaust port 10, and the main scavenging port 11 is located on the side closer to the exhaust port 10, and the auxiliary scavenging port 12 is located on the side closer to the exhaust port 10. are placed on the far side.

また、ピストン５の上面には、排気ポート１０に対応す
る周縁位置に突起部１３が形成されている。この突起部
１３の上面は周縁位置において最も高く、ピストン５中
夫に向かうほど低くなる傾斜面になっている。さらに、
その両側面１３ａ、１３ａは、主掃気ポート１１から噴
き出した掃気流を、ピストン５の内側へ向けて案内する
ようなガイド面を形成している。Furthermore, a protrusion 13 is formed on the upper surface of the piston 5 at a peripheral edge position corresponding to the exhaust port 10. The upper surface of this projection 13 is an inclined surface that is highest at the peripheral edge position and becomes lower toward the center of the piston 5. moreover,
Both side surfaces 13a, 13a form guide surfaces that guide the scavenging air flow blown out from the main scavenging port 11 toward the inside of the piston 5.

上述した２サイクルエンジンは、ピストン５が上昇する
とき、ピストン５上部の混合気を圧縮すると共に、ピス
トン５の下部側を負正にするため、下部側では吸気通路
７の混合気が吸気ポート９を介してクランクケース３内
へ吸入される。次いで、点火栓４の点火により、ピスト
ン５上部側の圧縮された混合気が燃焼爆発してピストン
５が下降させ、そのピストン５の上面が排気ボー）１０
を通過するとき、その排気ポート１０から内部の既燃ガ
スを排出する。それと同時に、ピストン５の下降によっ
て圧縮されたクランクケース３内の混合気が、掃気ポー
ト１１．１２からシリンダ２内へ噴き出されて掃気作用
を行う。In the above-mentioned two-stroke engine, when the piston 5 rises, it compresses the air-fuel mixture in the upper part of the piston 5 and makes the lower side of the piston 5 negative and positive. It is sucked into the crankcase 3 through. Next, by igniting the spark plug 4, the compressed air-fuel mixture on the upper side of the piston 5 burns and explodes, causing the piston 5 to descend, and the upper surface of the piston 5 becomes an exhaust bow.
When passing through, the burnt gas inside is discharged from the exhaust port 10. At the same time, the air-fuel mixture in the crankcase 3 compressed by the downward movement of the piston 5 is blown out from the scavenging ports 11, 12 into the cylinder 2 to perform a scavenging action.

このような掃気作用を行うとき、掃気流は突起部１３の
側面１３ａによってピストン５の奥側へ案内されるため
、排気ポート１０から矢印Ｂのように簡単に吹き抜ける
ことはない。また、掃気流が吹き込まれる初期において
、排気ポート１０の開口度が突起部１３によって狭めら
れた状態になるため、さらに吹き抜は防止効果を層高め
ることになる。When such a scavenging action is performed, the scavenging air flow is guided toward the inner side of the piston 5 by the side surface 13a of the protrusion 13, so that it does not easily blow through from the exhaust port 10 as shown by arrow B. Further, at the initial stage when the scavenging air flow is blown in, the opening degree of the exhaust port 10 is narrowed by the protrusion 13, which further enhances the effect of preventing the blow-out.

したがって、上述した２サイクルエンジンでは、アイド
リング時の掃気流の吹き抜けが防止され、排気中に含有
される未燃ガス（ＨＣ）の量を低減することができる。Therefore, in the two-stroke engine described above, blow-by of the scavenging air flow during idling is prevented, and the amount of unburned gas (HC) contained in the exhaust gas can be reduced.

また、それによって燃費を向上することができる。Moreover, fuel efficiency can be improved thereby.

なお、本発明において、上記突起部１３は側面１３ａの
部分を突起状に残し、上面中央を凹状に形成したもので
もよい。ただし、この場合は、側面１３ａを形成する突
起状が熱を溜めやすくなるため、好ましくない。In the present invention, the protrusion 13 may be formed such that the side surface 13a remains protruding and the center of the upper surface is concave. However, in this case, the protrusion forming the side surface 13a tends to accumulate heat, which is not preferable.

〔発明の効果〕〔Effect of the invention〕

上述したように本発明は、シリンダ内周面に掃気ポート
と排気ポートを開口させた２サイクルエンジンにおいて
、ピストン上面の前記排気ポートに対応する周縁位置に
突起部を設け、この突起部の側面を前記掃気ポートから
の掃気流をピストン上面の内側へ案内するガイド面に形
成したので、上記突起部によって掃気作用時の排気ポー
トの開口度が狭められ、掃気流が簡単に吹き抜けること
がなくなる。しかも、掃気ポートから噴き出す掃気流は
、突起部側面のガイド面によってピストン上面の内側へ
案内されるため、上記吹き抜は防止効果を一層効果的に
することができる。したがって、アイドリング時に排気
中に含有される未燃ガスの量を低減し、燃費を向上する
ことができる。As described above, the present invention provides a two-stroke engine in which a scavenging port and an exhaust port are opened on the inner circumferential surface of the cylinder, in which a protrusion is provided at a peripheral edge position corresponding to the exhaust port on the upper surface of the piston, and the side surface of the protrusion is Since the guide surface is formed to guide the scavenging air flow from the scavenging air port to the inside of the upper surface of the piston, the opening degree of the exhaust port during the scavenging operation is narrowed by the protrusion, and the scavenging air flow does not easily blow through. Furthermore, since the scavenging air flow blown out from the scavenging port is guided to the inside of the upper surface of the piston by the guide surface on the side surface of the protrusion, the above-mentioned blowout can further enhance the prevention effect. Therefore, the amount of unburned gas contained in the exhaust gas during idling can be reduced and fuel efficiency can be improved.

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

図は本発明の実施例による２サイクルエンジンを示し、
第１図は第３図に示す２ザイクルエンジンの要部を概略
的に示す斜視図、第２図は同エンジンのシリンダの展開
図、第３図は同エンジンの縦断面図、第４図は第３図の
ＴＬ−ＴＶ矢視図である。 ２−　シリンダ、　　５−　ピストン、　　９・−吸気
ポート、　１〇−排気ポート、　　１１−主掃気ポート
、　１２＝−補助掃気ポート、　１３−突起部、　１３
ａ−突起部側面（ガイド面）。The figure shows a two-stroke engine according to an embodiment of the invention,
Fig. 1 is a perspective view schematically showing the main parts of the two cycle engine shown in Fig. 3, Fig. 2 is an exploded view of the cylinder of the engine, Fig. 3 is a longitudinal sectional view of the engine, and Fig. 4 is It is a TL-TV arrow directional view of FIG. 2- cylinder, 5- piston, 9--intake port, 10-exhaust port, 11-main scavenging port, 12=-auxiliary scavenging port, 13-protrusion, 13
a - Projection side surface (guide surface).

Claims (1)

【特許請求の範囲】[Claims] シリンダ内周面に掃気ポートと排気ポートを開口させた
２サイクルエンジンにおいて、ピストン上面の前記排気
ポートに対応する周縁位置に突起部を設け、この突起部
の側面を前記掃気ポートからの掃気流をピストン上面の
内側へ案内するガイド面に形成したことを特徴とする２
サイクルエンジン。In a two-stroke engine in which a scavenging port and an exhaust port are opened on the inner peripheral surface of the cylinder, a protrusion is provided on the upper surface of the piston at a peripheral edge position corresponding to the exhaust port, and the side surface of this protrusion is used to direct the scavenging air flow from the scavenging port. 2, characterized in that it is formed on a guide surface that guides inside the upper surface of the piston.
cycle engine.
JP14464585A 1985-07-03 1985-07-03 Two-cycle engine Pending JPS627920A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP14464585A JPS627920A (en) 1985-07-03 1985-07-03 Two-cycle engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP14464585A JPS627920A (en) 1985-07-03 1985-07-03 Two-cycle engine

Publications (1)

Publication Number Publication Date
JPS627920A true JPS627920A (en) 1987-01-14

Family

ID=15366886

Family Applications (1)

Application Number Title Priority Date Filing Date
JP14464585A Pending JPS627920A (en) 1985-07-03 1985-07-03 Two-cycle engine

Country Status (1)

Country Link
JP (1) JPS627920A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013164010A (en) * 2012-02-10 2013-08-22 Makita Corp Two-stroke engine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013164010A (en) * 2012-02-10 2013-08-22 Makita Corp Two-stroke engine

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