JP3966619B2 - Combustion chamber structure of internal combustion engine - Google Patents

Combustion chamber structure of internal combustion engine Download PDF

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JP3966619B2
JP3966619B2 JP17154998A JP17154998A JP3966619B2 JP 3966619 B2 JP3966619 B2 JP 3966619B2 JP 17154998 A JP17154998 A JP 17154998A JP 17154998 A JP17154998 A JP 17154998A JP 3966619 B2 JP3966619 B2 JP 3966619B2
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combustion chamber
electrode
piston
squish
area
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JP2000008860A (en
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一紀 菊池
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Honda Motor Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Combined Controls Of Internal Combustion Engines (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は，シリンダヘッドの内面とピストンの頂面とで燃焼室を画成し，シリンダヘッドに装着される点火栓の電極を燃焼室の周縁部に近接して臨ませた内燃機関の燃焼室構造に関する。
【０００２】
【従来の技術】
かゝる内燃機関の燃焼室構造は，例えば特公昭５８−４３５６５号公報に開示されているように，既に知られている。
【０００３】
【発明が解決しようとする課題】
内燃機関において，ノッキングの発生を防止するためには，点火栓の電極を燃焼室の中心部に配置して，火炎の伝播距離を極力短くすることが一般に有効とされている。しかしながら，内燃機関の構造や形式によっては，吸，排気弁の配置等の関係から，点火栓のそのような配置を採用することが困難な場合があり，即ち点火栓の電極を燃焼室の周縁部に近接して配置することを余儀なくされることがある。このような場合には，火炎の伝播距離が必然的に長くなるため，エンドガスの自然発火によるノッキングが発生し易くなる。
【０００４】
本発明は，かゝる事情に鑑みてなされたもので，点火栓の電極を燃焼室の周縁部に近接して配置しても，エンドガスが自然発火に至る前に，正常な火炎伝播が完了するようにして，耐ノッキング性を向上させ得る，内燃機関の燃焼室構造を提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するために，本発明は，シリンダヘッドの内面とピストンの頂面とで燃焼室を画成し，シリンダヘッドに装着される点火栓の電極を燃焼室の周縁部に近接して臨ませた内燃機関において，前記燃焼室の天井面周縁部と前記ピストンの頂面周縁部との間に燃焼室の中心に向かって上り勾配の環状のスキッシュ領域を設け，このスキッシュ領域の，前記点火栓の電極に最も遠い区域から噴出する混合気のスキッシュ流が該電極を指向し，該電極に最も近い区域から噴出する混合気のスキッシュ流が該電極の下方を指向するようにしたことを第１の特徴とする。
【０００６】
この第１の特徴によれば，圧縮行程時，ピストンが上死点に近づくと，燃焼室周縁部の，電極に遠い区域からは，電極に向かう混合気のスキッシュ流が噴出するので，これが点火栓の点火により発生した火炎の外面に対して垂直に衝突することにより，火炎によるエンドガスの加圧に遅れを生じさせる。そしてエンドガスが自然発火する前に火炎は燃焼室の最遠の周縁まで正常に伝播し，ノッキングの無い正常な燃焼を生起させることになる。
【０００７】
また，燃焼室の，電極に最も近い部分から噴出するスキッシュ流は電極へは向かわず，その下方へ逸れるため，電極の点火直後に出来た火種を吹き消すことを回避しながら，混合気に乱流を生じせしめて，火炎の伝播を促進し，ノッキングの発生をより防ぐことができる。
【０００８】
さらに，点火栓の電極は，燃焼室の周縁部に近接して配置されることから，燃焼室の比較的低い位置を占めることになり，該電極に最も遠い区域から噴出する混合気のスキッシュ流が該電極を指向し，該電極に最も近い区域から噴出する混合気のスキッシュ流が該電極の下方を指向するように，燃焼室の天井面周縁部とピストンの頂面周縁部との間にスキッシュ領域を設けると，ピストンの頂面周縁部に形成される斜面は必然的に緩勾配のものとなるから，その斜面形成に伴うピストン頂面の受熱面積の増加が極めて少ないこと，及び全部のスキッシュ流がピストン頂面に近接して流れてピストンを効果的に冷却することにより，ピストンの耐久性を確保しつゝ，耐ノッキング性の向上に寄与する。
【０００９】
また本発明は，上記第１の特徴に加えて，前記燃焼室の天井面周縁部には燃焼室の中心に向かって上り勾配の上部斜面を設けると共に，前記ピストンの頂面周縁部には前記上部斜面と同角度で傾斜する下部斜面を設け，これら上部斜面と下部斜面との間に環状の前記スキッシュ領域が形成されるようにしたことを第２の特徴とする。
【００１０】
さらに本発明は，上記第１又は第２の特徴に加えて，前記燃焼室の天井面に各１個の吸気弁及び排気弁の傘部を互いに近接して配置し，これら吸気弁及び排気弁の両軸線を含む平面の一側方において前記点火栓の電極を燃焼室の周縁部に近接配置したことを第３の特徴とする。
【００１１】
この第３の特徴によれば，点火栓に干渉されることなく，吸気ポート及び排気ポートの大径化を可能にし，充填効率を高めると共に排気抵抗を下げ，耐ノッキング性の向上と相まって，機関出力の向上を図ることができる。
【００１２】
【発明の実施の形態】
本発明の実施の形態を，添付図面に示す本発明の実施例に基づいて以下に説明する。
【００１３】
図１は本発明の燃焼室構造を備えた内燃機関の縦断側面図，図２は図１の２−２線断面図，図３は図１の３−３線断面図，図４は図１の４−４線断面図，図５は燃焼室における混合気の燃焼状態を示す作用説明図，図６は比較例の燃焼室構造を示す，図１に対応した断面図，図７は本発明と比較例との耐ノッキング性能比較テスト線図である。
【００１４】
先ず，図１及び図２において，内燃機関１は，シリンダブロック２と，このシリンダブロック２の上端面にガスケット３を挟んで接合されるシリンダヘッド４と，シリンダブロック２の中心部に形成されたシリンダボア２ａに昇降自在に嵌装されたピストン５とを備えており，シリンダヘッド４の内面とピストン５の頂面との間に燃焼室６が画成される。
【００１５】
この燃焼室６の半球状に形成された天井面に，シリンダヘッド４に形成された吸気ポート７及び排気ポート８が開口し，これらを開閉するポペット型の吸気弁１０及び排気弁１１がシリンダヘッド４に装着される。その際，各ポート７，８を極力大径とすべく各弁１０，１１の傘部１０ａ，１１ａは互いに近接して配置される。
【００１６】
またシリンダヘッド４に螺着される点火栓１２の電極１２ａは，吸気及び排気弁１０，１１の両傘部１０ａ，１１ａを避けて燃焼室６に臨むように，燃焼室６周縁部に近接して配置される。即ち電極１２ａは，吸気及び排気弁１０，１１の軸線Ｏ１，Ｏ２を含む平面Ａの一側方において燃焼室６周縁部に近接配置される。
【００１７】
吸気及び排気弁１０，１１は，図示しないクランク軸より駆動される公知の動弁装置１３によって開閉される。
【００１８】
図１ないし図４に示すように，燃焼室６の天井面周縁部には，燃焼室６の中心に向かって上り勾配となる截頭円錐状の上部斜面１５が，またピストン５の頂面周縁部には，上記上部斜面１５と同角度で傾斜する截頭円錐状の下部斜面１６がそれぞれ形成される。これら上部及び下部斜面１５，１６は，ピストン５が上死点に到達するとき，両斜面１５，１６から混合気のスキッシュ流を噴出する環状のスキッシュ領域１７を形成するものであって，両斜面１５，１６の勾配は，スキッシュ領域１７の，電極１２ａに最も遠い区域１７ｆから噴出するスキッシュ流Ｆが電極１２ａに向かう方向を指向し，電極１２ａに最も近い区域１７ｎから噴出するスキッシュ流Ｎが該電極１２ａを下方へ逸れる方向を指向するように設定される。
【００１９】
次に，この実施例の作用について説明する。
【００２０】
ピストン５の吸気行程で，吸気弁１０の開弁により吸気ポート７から燃焼室６に混合気が吸入され，この混合気はピストン５の次の圧縮行程で圧縮されるが，ピストン５が上死点に近づくと，燃焼室６の天井面周縁部の截頭円錐状の上部斜面１５と，ピストン５の頂面周縁部の截頭円錐状の下部斜面１６とが近接して環状のスキッシュ領域１７を形成するので，このスキッシュ領域１７から混合気の噴出が始まり，この噴出は，ピストン５が上死点を僅かに過ぎるまで続く。
【００２１】
そのとき，スキッシュ領域１７の，点火栓１２の電極１２ａに最も遠い区域１７ｆから噴出するスキッシュ流Ｆは電極１２ａに向かって直進するが，電極１２ａに最も近い区域１７ｎから噴出するスキッシュ流Ｎは電極１２ａを逸れるように，その下方に向かう。
【００２２】
一方，点火栓１２は，ピストン５が上死点手前の所定位置に来たとき電極１２ａに点火され，混合気の着火により発生した火炎１８は，図５に示すように電極１２ａを中心にして球状に広がって進行する。
【００２３】
この場合，一般的には，上記火炎１８は，燃焼室６の周縁の，電極１２ａに近い区域には短時間で到達するので，該区域ではエンドガスの自然発火は生じ難いが，電極１２ａから遠く離れた区域への火炎１８の到達には相応の時間を要するため，その間にエンドガスは火炎面により加圧され，前炎反応が進行して自然発火に至り，これによる異常燃焼がノッキングの原因とされている。
【００２４】
しかしながら，本発明の場合，燃焼室６の周縁部に形成された環状のスキッシュ領域１７において，電極１２ａに遠い区域１７ｆからは，前述のように電極１２ａに向かって直進する混合気のスキッシュ流Ｆが噴出するので，これが火炎１８の外面に対して垂直に衝突することにより，火炎１８によるエンドガスの加圧に遅れを生じさせる。そしてエンドガスが自然発火する前に火炎１８は燃焼室６の最遠の周縁まで正常に伝播し，ノッキングの無い正常な燃焼を生起させることになる。
【００２５】
また，スキッシュ領域１７において，電極１２ａに最も近い区域１７ｎから噴出するスキッシュ流Ｎは電極１２ａへは向かわず，その下方へ逸れるため，電極１２ａの点火直後に出来た火種を吹き消すことを回避しながら，混合気に乱流を生じせしめて，火炎１８の伝播を速め，これもノッキングの発生防止に寄与する。
【００２６】
さらに，点火栓１２の電極１２ａは，燃焼室６の周縁部に近接して配置されることから，燃焼室６の比較的低い位置を占めることになり，該電極１２ａに最も遠い区域１７ｆから噴出する混合気のスキッシュ流Ｆが該電極１２ａを指向し，該電極１２ａに最も近い区域１７ｎから噴出する混合気のスキッシュ流Ｎが該電極１２ａの下方を指向するように，燃焼室６の天井面周縁部とピストン５の頂面周縁部との間にスキッシュ領域１７を設けると，ピストン５の頂面周縁部に形成される斜面は傾斜角度θ（図５参照）が必然的に小さいものとなるから，その斜面形成に伴うピストン５頂面の受熱面積の増加が極めて少ないこと，及び全部のスキッシュ流Ｆ，Ｎがピストン５頂面に近接して流れてピストン５頂面を効果的に冷却することにより，ピストン５の耐久性の確保と耐ノッキング性の向上とに貢献する。
【００２７】
図６に示す比較例の燃焼室構造では，スキッシュ領域１７′は，燃焼室６の天井面周縁部の環状水平面１５′と，ピストン５の頂面周縁部の環状水平面１６′との間に形成される。その他の構成は，上記本発明の実施例と同様であり，図中，本発明の実施例と対応する部分には，それと同一の符号を付す。
【００２８】
この比較例では，スキッシュ領域１７′から噴出する混合気のスキッシュ流は，燃焼室６の，電極１２ａより下方の部分で混合気に攪拌を与える。
【００２９】
本発明の燃焼室構造と上記比較例の燃焼室構造とのそれぞれのノッキング状況をテストして比較してみると，図７の結果を得た。
【００３０】
テスト条件として，両燃焼室構造のスキッシュ間隙ｇを０．８ｍｍ，圧縮比を９．２，潤滑油温度を１２５〜１４５°Ｃ，点火栓温度を２０４〜２８２°Ｃ，スロットル開度を全開とした。
【００３１】
テストの方法は，キスラーの指圧センサにより，シリンダボア２ａの内圧を検出し，オシロスコープでモニタしながら点火時期を進角していくもので，ノッキングに起因する高周波が出始めた点をノッキング開始点火時期とした。
【００３２】
図７から明らかなように，本発明の場合のノッキング開始点火時期は，比較例の場合のノッキング開始点火時期に対してクランク角度で５〜１０°も遅れることが判明し，本発明燃焼室構造の耐ノッキング性の向上を確認することができた。
【００３３】
また本発明の燃焼室構造では，燃焼室６の天井面に各１個の吸気弁１０及び排気弁１１の傘部１０ａ，１１ａが互いに近接して配置され，これら吸気弁１０及び排気弁１１の両軸線を含む平面Ａの一側方に点火栓１２の電極１２ａが配置されたので，点火栓１２に何等干渉されることなく，吸気ポート７及び排気ポートの大径化を可能にし，充填効率を高めると共に排気抵抗を下げ，耐ノッキング性の向上と相まって，機関出力の向上をもたらすことができる。
【００３４】
本発明は，上記実施例に限定されるものではなく，その要旨の範囲を逸脱することなく種々の設計変更が可能である。例えば，スキッシュ領域１７は，吸気及び排気弁１０，１１の傘部１０ａ，１１ａを更に大径にして，それら傘部１０ａ，１１ａとの干渉を避けるべく，スキッシュ領域１７の一部を削除することもできる。またピストン５の頂面のスキッシュ領域１７に囲繞される部分は，図示例のような窪ませた形状に代えて，反対に緩やかに膨らませた形状とすることもできる。
【００３５】
【発明の効果】
以上のように本発明の第１及び第２の特徴によれば，シリンダヘッドの内面とピストンの頂面とで燃焼室を画成し，シリンダヘッドに装着される点火栓の電極を燃焼室の周縁部に近接して臨ませた内燃機関において，前記燃焼室の天井面周縁部とピストンの頂面周縁部との間に燃焼室の中心に向かって上り勾配の環状のスキッシュ領域を設け，このスキッシュ領域の，前記点火栓の電極に最も遠い区域から噴出する混合気のスキッシュ流が該電極を指向し，該電極に最も近い区域から噴出する混合気のスキッシュ流が該電極の下方を指向するようにしたので，燃焼室周縁の，電極に遠い区域から噴出するスキッシュ流が電極から発生した火炎の外面を圧迫して，火炎によるエンドガスの加圧に遅れを生じさせること，燃焼室周縁の，電極に近い区域から噴出するスキッシュ流は電極を避けることにより，電極の点火直後に出来た火種を吹き消すことなく混合気に乱流を生じせしめて火炎の伝播を促進すること等によって，耐ノッキング性を大幅に向上させることができる。また点火栓の電極は，燃焼室の周縁部に近接して配置されることから，燃焼室の比較的低い位置を占めることになり，該電極に最も遠い区域から噴出する混合気のスキッシュ流が該電極を指向し，該電極に最も近い区域から噴出する混合気のスキッシュ流が該電極の下方を指向するように，燃焼室の天井面周縁部とピストンの頂面周縁部との間にスキッシュ領域を設けると，ピストンの頂面周縁部に形成される斜面は必然的に緩勾配のものとなるから，その斜面形成に伴うピストン頂面の受熱面積の増加が極めて少ないこと，及び全部のスキッシュ流がピストン頂面に近接して流れてピストンを効果的に冷却することにより，ピストンの耐久性を確保しつゝ，耐ノッキング性の向上に寄与することができる。
【００３６】
また本発明の第３の特徴によれば，燃焼室の天井面に各１個の吸気弁及び排気弁の傘部を互いに近接して配置し，これら吸気弁及び排気弁の両軸線を含む平面の一側方において点火栓の電極を燃焼室の周縁部に近接配置したので，点火栓に干渉されることなく，吸気ポート及び排気ポートの大径化を可能にし，充填効率を高めると共に排気抵抗を下げ，耐ノッキング性の向上と相まって，機関出力の向上を図ることができる。
【図面の簡単な説明】
【図１】 本発明の燃焼室構造を備えた内燃機関の縦断側面図。
【図２】 図１の２−２線断面図。
【図３】 図１の３−３線断面図。
【図４】 図１の４−４線断面図。
【図５】 燃焼室における混合気の燃焼状態を示す作用説明図。
【図６】 比較例の燃焼室構造を示す，図１に対応した断面図。
【図７】 本発明と比較例との耐ノッキング性能比較テスト線図。
【符号の説明】
１・・・・・内燃機関
４・・・・・シリンダヘッド
５・・・・・ピストン
６・・・・・燃焼室
１０・・・・吸気弁
１０ａ・・・吸気弁の傘部
１１・・・・排気弁
１１ａ・・・排気弁の傘部
１２・・・・点火栓
１２ａ・・・点火栓の電極
１５・・・・上部斜面
１６・・・・下部斜面
１７・・・・スキッシュ領域
１７ｆ・・・スキッシュ領域の電極に遠い区域
１７ｎ・・・スキッシュ領域の電極に近い区域
Ａ・・・・・平面
Ｏ１・・・・吸気弁の軸線
Ｏ２・・・・排気弁の軸線
Ｆ・・・・・電極に遠い区域から噴出したスキッシュ流
Ｎ・・・・・電極に近い区域から噴出したスキッシュ流[0001]
BACKGROUND OF THE INVENTION
The present invention provides a combustion chamber of an internal combustion engine in which a combustion chamber is defined by an inner surface of a cylinder head and a top surface of a piston, and an electrode of a spark plug attached to the cylinder head faces a peripheral portion of the combustion chamber. Concerning structure.
[0002]
[Prior art]
A combustion chamber structure of such an internal combustion engine, for example as disclosed in Japanese Patent Publication 58-43565, JP-known already.
[0003]
[Problems to be solved by the invention]
In an internal combustion engine, in order to prevent the occurrence of knocking, it is generally effective to reduce the flame propagation distance as much as possible by arranging the electrode of the spark plug at the center of the combustion chamber. However, depending on the structure and type of the internal combustion engine, it may be difficult to adopt such an arrangement of the spark plug due to the arrangement of the intake and exhaust valves, that is, the electrode of the spark plug is connected to the periphery of the combustion chamber. May be forced to be placed close to the part. In such a case, since the propagation distance of the flame is inevitably long, knocking due to spontaneous ignition of the end gas is likely to occur.
[0004]
The present invention has been made in view of such circumstances, and even if the electrode of the spark plug is arranged close to the peripheral portion of the combustion chamber, normal flame propagation is completed before the end gas reaches spontaneous ignition. Thus, an object of the present invention is to provide a combustion chamber structure of an internal combustion engine that can improve knocking resistance.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention defines a combustion chamber by the inner surface of the cylinder head and the top surface of the piston, and an electrode of a spark plug attached to the cylinder head is placed close to the peripheral edge of the combustion chamber. in face was the internal combustion engine, said an annular squish area of upward gradient toward the center of the combustion chamber between the top surface peripheral edge of the ceiling surface peripheral portion of the combustion chamber piston of the squish area, the The squish flow of the air-fuel mixture ejected from the area farthest from the spark plug electrode is directed to the electrode, and the squish flow of the air-fuel mixture ejected from the area closest to the electrode is directed to the lower side of the electrode. First feature.
[0006]
According to this first feature, during the compression stroke, when the piston approaches top dead center, the squish flow of the air-fuel mixture toward the electrode is ejected from the peripheral area of the combustion chamber and far from the electrode. By colliding perpendicularly to the outer surface of the flame generated by the ignition of the plug, the end gas pressurization by the flame is delayed. Before the end gas spontaneously ignites, the flame propagates normally to the farthest periphery of the combustion chamber, causing normal combustion without knocking.
[0007]
In addition, the squish flow ejected from the portion of the combustion chamber closest to the electrode does not go to the electrode, but deviates downward. Therefore, the air-fuel mixture is disturbed while avoiding blowing off the fire produced immediately after the ignition of the electrode. By creating a flow, it is possible to promote the propagation of flame and prevent the occurrence of knocking.
[0008]
Furthermore, since the electrode of the spark plug is arranged close to the peripheral edge of the combustion chamber, it occupies a relatively low position of the combustion chamber, and the squish flow of the air-fuel mixture ejected from the area farthest from the electrode Is directed to the electrode and the squish flow of the air-fuel mixture ejected from the area closest to the electrode is directed to the lower side of the electrode between the ceiling peripheral edge of the combustion chamber and the top peripheral edge of the piston. When the squish area is provided, the slope formed on the periphery of the top surface of the piston inevitably has a gentle slope. Therefore, the increase in the heat receiving area of the piston top surface due to the formation of the slope is extremely small. The squish flow flows close to the top surface of the piston and effectively cools the piston, ensuring the durability of the piston and contributing to the improvement of knocking resistance.
[0009]
According to the present invention, in addition to the first feature described above, an upper slope of an upward slope toward the center of the combustion chamber is provided at the peripheral edge of the ceiling surface of the combustion chamber, and the top peripheral edge of the piston is provided at the peripheral edge of the piston. A second feature is that a lower slope inclined at the same angle as the upper slope is provided, and the annular squish area is formed between the upper slope and the lower slope.
[0010]
The present invention, in addition to the first or second feature, the ceiling surface of the combustion chamber adjacent the valve head of each one of the intake and exhaust valves each other are arranged, the intake and exhaust valves a third feature in that the electrodes of the spark plug disposed close to the periphery of the combustion chamber in one side of a plane containing both the axis of the.
[0011]
According to the third feature, without that will be interference to the ignition plug, enabling larger diameter of the intake port and the exhaust port lowers the exhaust resistance to increase the charging efficiency, coupled with improvement in antiknock properties, engine The output can be improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.
[0013]
1 is a longitudinal side view of an internal combustion engine having a combustion chamber structure according to the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, FIG. 3 is a sectional view taken along line 3-3 of FIG. Fig. 5 is a sectional view corresponding to Fig. 1, Fig. 5 is a sectional view corresponding to Fig. 1, and Fig. 7 is a sectional view corresponding to Fig. 1. It is a knocking-proof performance comparison test diagram with a comparative example.
[0014]
First, in FIG. 1 and FIG. 2, the internal combustion engine 1 is formed at the center of the cylinder block 2, a cylinder head 4 joined to the upper end surface of the cylinder block 2 with a gasket 3 interposed therebetween, and the cylinder block 2. A piston 5 is mounted on the cylinder bore 2 a so as to be movable up and down. A combustion chamber 6 is defined between the inner surface of the cylinder head 4 and the top surface of the piston 5.
[0015]
Hemispherical ceiling surface formed in the combustion chamber 6, an intake port 7 and an exhaust port 8 formed in the cylinder head 4 is opened, the intake valve 10 and exhaust valve 11 of the poppet to open and close them is the cylinder head 4 is attached. At that time, the umbrella portions 10a and 11a of the valves 10 and 11 are arranged close to each other in order to make the ports 7 and 8 as large as possible.
[0016]
Further, the electrode 12a of the spark plug 12 screwed to the cylinder head 4 is close to the peripheral portion of the combustion chamber 6 so as to face the combustion chamber 6 while avoiding the umbrella portions 10a, 11a of the intake and exhaust valves 10, 11. Arranged. That is, the electrode 12a is disposed close to the periphery of the combustion chamber 6 on one side of the plane A including the axes O 1 and O 2 of the intake and exhaust valves 10 and 11.
[0017]
The intake and exhaust valves 10 and 11 are opened and closed by a known valve gear 13 driven by a crankshaft (not shown).
[0018]
As shown in FIGS. 1 to 4, a frustoconical upper slope 15 that is inclined upward toward the center of the combustion chamber 6 is formed at the periphery of the ceiling surface of the combustion chamber 6. Each part has a frustoconical lower slope 16 inclined at the same angle as the upper slope 15. These upper and lower slopes 15 and 16 form an annular squish region 17 that ejects a squish flow of air-fuel mixture from both slopes 15 and 16 when the piston 5 reaches top dead center. The slopes 15 and 16 are directed so that the squish flow F ejected from the region 17f farthest from the electrode 12a in the squish region 17 is directed toward the electrode 12a, and the squish flow N ejected from the region 17n closest to the electrode 12a The electrode 12a is set so as to be directed in a direction deviating downward.
[0019]
Next, the operation of this embodiment will be described.
[0020]
In the intake stroke of the piston 5, the air-fuel mixture is sucked into the combustion chamber 6 from the intake port 7 by opening the intake valve 10, and this air-fuel mixture is compressed in the next compression stroke of the piston 5, but the piston 5 is dead dead. When approaching the point, the frustoconical upper slope 15 at the periphery of the ceiling surface of the combustion chamber 6 and the frustoconical lower slope 16 at the periphery of the top surface of the piston 5 come close to each other, and an annular squish region 17. Therefore, the air-fuel mixture starts to be ejected from the squish area 17, and this ejection continues until the piston 5 slightly passes the top dead center.
[0021]
Then, the squish area 17, squish flow F injected from the furthest zone 17f to the electrode 12a of the spark plug 12 is straight I toward either the electrode 12a, squish flow ejected from the nearest area 17n to the electrode 12a N Heads downward to escape the electrode 12a.
[0022]
On the other hand, the spark plug 12 ignites the electrode 12a when the piston 5 reaches a predetermined position before the top dead center, and the flame 18 generated by the ignition of the air-fuel mixture is centered on the electrode 12a as shown in FIG. Progress in a spherical shape.
[0023]
In this case, in general, the flame 18 reaches the area near the electrode 12a at the periphery of the combustion chamber 6 in a short time, so that spontaneous combustion of the end gas hardly occurs in the area but is far from the electrode 12a. Since it takes a certain amount of time for the flame 18 to reach a distant area, the end gas is pressurized by the flame surface during that time, the pre-flame reaction proceeds and spontaneous ignition occurs, and abnormal combustion caused by this causes knocking. Has been.
[0024]
However, in the present invention, the annular squish area 17 formed on the peripheral portion of the combustion chamber 6 from the distant area 17f to the electrodes 12a, the air-fuel mixture to be straight I or toward the electrode 12a, as described above squish Since the flow F is ejected, it collides perpendicularly with the outer surface of the flame 18, thereby causing a delay in pressurization of the end gas by the flame 18. Before the end gas spontaneously ignites, the flame 18 propagates normally to the farthest periphery of the combustion chamber 6 and causes normal combustion without knocking.
[0025]
In addition, in the squish region 17, the squish flow N ejected from the area 17n closest to the electrode 12a does not go to the electrode 12a, but deviates downward. Therefore, it is possible to avoid blowing off the fire type generated immediately after the ignition of the electrode 12a. However, the turbulent flow is generated in the air-fuel mixture and the propagation of the flame 18 is accelerated, which also contributes to the prevention of knocking.
[0026]
Further, since the electrode 12a of the spark plug 12 is disposed in the vicinity of the peripheral edge of the combustion chamber 6, it occupies a relatively low position of the combustion chamber 6 and is ejected from a region 17f farthest from the electrode 12a. The squish flow F of the air-fuel mixture is directed toward the electrode 12a, and the squish flow N of the air-fuel mixture ejected from the area 17n closest to the electrode 12a is directed downward of the electrode 12a. When the squish region 17 is provided between the peripheral edge and the top peripheral edge of the piston 5, the slope formed on the top peripheral edge of the piston 5 necessarily has a small inclination angle θ (see FIG. 5). Therefore, the increase in the heat receiving area of the top surface of the piston 5 due to the formation of the inclined surface is extremely small, and all the squish flows F and N flow close to the top surface of the piston 5 to effectively cool the top surface of the piston 5. By Contribute to ensuring the durability of the piston 5 and the improvement of antiknock properties.
[0027]
In the combustion chamber structure of the comparative example shown in FIG. 6, the squish region 17 ′ is formed between the annular horizontal surface 15 ′ at the peripheral edge of the ceiling surface of the combustion chamber 6 and the annular horizontal surface 16 ′ at the peripheral edge of the top surface of the piston 5. Is done. Other configurations are the same as those of the above-described embodiment of the present invention, and portions corresponding to those of the embodiment of the present invention are denoted by the same reference numerals.
[0028]
In this comparative example, the squish flow of the air-fuel mixture ejected from the squish region 17 ′ gives stirring to the air-fuel mixture in the portion of the combustion chamber 6 below the electrode 12 a.
[0029]
As each Comparing Test knocking condition of the combustion chamber structure and the combustion chamber structure of the comparative example of the present invention to obtain the results of Figure 7.
[0030]
As test conditions, the squish gap g of both combustion chamber structures is 0.8 mm, the compression ratio is 9.2, the lubricating oil temperature is 125 to 145 ° C, the spark plug temperature is 204 to 282 ° C, and the throttle opening is fully open. did.
[0031]
The test method is to detect the internal pressure of the cylinder bore 2a with a Kistler finger pressure sensor and advance the ignition timing while monitoring with an oscilloscope. It was.
[0032]
As apparent from FIG. 7, the knocking starts the ignition timing in the case of the present invention, was found to be delayed even 5 to 10 ° in crank angle with respect to the knocking starts the ignition timing in the case of the comparative example, the present invention a combustion chamber structure It was confirmed that the knocking resistance was improved.
[0033]
Further, in the combustion chamber structure of the present invention, one intake valve 10 and one umbrella portion 10a of the exhaust valve 11 are arranged close to each other on the ceiling surface of the combustion chamber 6, and the intake valve 10 and the exhaust valve 11 Since the electrode 12a of the spark plug 12 is arranged on one side of the plane A including both axes, the diameter of the intake port 7 and the exhaust port can be increased without any interference with the spark plug 12, and the charging efficiency As well as lowering the exhaust resistance and improving the knocking resistance, the engine output can be improved.
[0034]
The present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the scope of the gist thereof. For example, in the squish area 17, the umbrella portions 10 a and 11 a of the intake and exhaust valves 10 and 11 are made larger in diameter, and a part of the squish area 17 is deleted to avoid interference with the umbrella portions 10 a and 11 a. You can also. Further, the portion surrounded by the squish region 17 on the top surface of the piston 5 can be formed into a gently bulging shape on the contrary, instead of the recessed shape as shown in the illustrated example.
[0035]
【The invention's effect】
As described above, according to the first and second features of the present invention, the combustion chamber is defined by the inner surface of the cylinder head and the top surface of the piston, and the electrode of the spark plug mounted on the cylinder head is connected to the combustion chamber . in an internal combustion engine which is faced in close proximity to the periphery, an annular squish area of upward gradient toward the center of the combustion chamber between the top surface peripheral portion of the ceiling surface periphery and the piston of the combustion chamber is provided, this squish area squish flow of the mixture jetted from the farthest zone to the electrodes of the spark plug oriented to the electrode, the squish flow of the mixture jetted from the closest zone to the electrode is directed downward of the electrode As a result, the squish flow ejected from the area far from the electrode at the periphery of the combustion chamber compresses the outer surface of the flame generated from the electrode, causing a delay in pressurization of the end gas by the flame, Close to electrode The squish flow erupted from the area avoids the electrode, greatly increasing the resistance to knocking by, for example, creating a turbulent flow in the air-fuel mixture without blowing off the fire produced immediately after the electrode is ignited, thereby promoting flame propagation. Can be improved. In addition, since the electrode of the spark plug is disposed close to the peripheral edge of the combustion chamber, it occupies a relatively low position of the combustion chamber, and the squish flow of the air-fuel mixture ejected from the area farthest from the electrode is generated. A squish between the ceiling peripheral edge of the combustion chamber and the top peripheral edge of the piston so that the squish flow of the air-fuel mixture ejected from the area closest to the electrode is directed downward of the electrode. If the area is provided, the slope formed on the periphery of the top surface of the piston inevitably has a gentle slope, and therefore the increase in the heat receiving area of the piston top surface due to the formation of the slope is extremely small, and the entire squish The flow flows close to the top surface of the piston and effectively cools the piston, so that the durability of the piston can be secured and the knocking resistance can be improved.
[0036]
According to the third aspect of the present invention, the umbrella portion of each intake valve and exhaust valve is disposed close to each other on the ceiling surface of the combustion chamber, and includes a plane including both axes of the intake valve and the exhaust valve. Because the spark plug electrode is located close to the periphery of the combustion chamber on one side of the cylinder, the intake and exhaust ports can be enlarged without interference by the spark plug, increasing the charging efficiency and exhaust resistance. The engine output can be improved in combination with the improved knock resistance.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of an internal combustion engine having a combustion chamber structure according to the present invention.
FIG. 2 is a cross-sectional view taken along line 2-2 of FIG.
3 is a cross-sectional view taken along line 3-3 in FIG.
4 is a cross-sectional view taken along line 4-4 of FIG.
FIG. 5 is an operation explanatory diagram showing a combustion state of an air-fuel mixture in a combustion chamber.
6 is a cross-sectional view corresponding to FIG. 1, showing a combustion chamber structure of a comparative example.
FIG. 7 is a test diagram for comparing resistance to knocking between the present invention and a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 4 ... Cylinder head 5 ... Piston 6 ... Combustion chamber 10 ... Intake valve 10a ... Intake valve umbrella part 11 ... ..Exhaust valve 11a ... Exhaust valve umbrella 12 ... Ignition plug 12a ... Ignition plug electrode
15 ... Upper slope
16 ... lower slope 17 .... squish area 17f · · · squish area electrodes far zone 17n · · · squish area electrodes in the near zone A · · · · · plane O 1 ... intake of Valve axis O 2 ... Exhaust valve axis F... Squish flow ejected from a region far from the electrode N. Squish flow ejected from a region near the electrode

Claims (3)

シリンダヘッド（４）の内面とピストン（５）の頂面とで燃焼室（６）を画成し，シリンダヘッド（４）に装着される点火栓（１２）の電極（１２ａ）を燃焼室（６）の周縁部に近接して臨ませた内燃機関において，
前記燃焼室（６）の天井面周縁部と前記ピストン（５）の頂面周縁部との間に燃焼室（６）の中心に向かって上り勾配の環状のスキッシュ領域（１７）を設け，このスキッシュ領域（１７）の，前記点火栓（１２）の電極（１２ａ）に最も遠い区域（１７ｆ）から噴出する混合気のスキッシュ流（Ｆ）が該電極（１２ａ）を指向し，該電極（１２ａ）に最も近い区域（１７ｎ）から噴出する混合気のスキッシュ流（Ｎ）が該電極（１２ａ）の下方を指向するようにしたことを特徴とする，内燃機関の燃焼室構造。A combustion chamber (6) is defined by the inner surface of the cylinder head (4) and the top surface of the piston (5), and an electrode (12a) of a spark plug (12) attached to the cylinder head (4) is connected to the combustion chamber ( 6) In the internal combustion engine facing the periphery of
The combustion chamber between the ceiling surface periphery and the top surface peripheral edge of the piston (5) an annular squish area of upslope (17) towards the center (6) provided in the combustion chamber (6), this the squish area (17), said spark plug (12) electrode (12a) to the squish flow of the mixture jetted from the farthest zone (17f) (F) is directed to the electrode (12a), said electrodes (12a A combustion chamber structure of an internal combustion engine, characterized in that a squish flow (N) of an air-fuel mixture ejected from an area (17n) closest to () is directed downward of the electrode (12a). 請求項１記載のものにおいて，In claim 1,
前記燃焼室（６）の天井面周縁部には燃焼室（６）の中心に向かって上り勾配の上部斜面（１５）を設けると共に，前記ピストン（５）の頂面周縁部には前記上部斜面（１５）と同角度で傾斜する下部斜面（１６）を設け，これら上部斜面（１５）と下部斜面（１６）との間に環状の前記スキッシュ領域（１７）が形成されるようにしたことを特徴とする，内燃機関の燃焼室構造。An upper slope (15) is provided on the peripheral edge of the ceiling surface of the combustion chamber (6) toward the center of the combustion chamber (6), and the upper slope is provided on the top peripheral edge of the piston (5). The lower slope (16) inclined at the same angle as (15) is provided, and the annular squish area (17) is formed between the upper slope (15) and the lower slope (16). Characterized by the combustion chamber structure of the internal combustion engine. 請求項１又は２記載のものにおいて，
前記燃焼室（６）の天井面に各１個の吸気弁（１０）及び排気弁（１１）の傘部（１０ａ，１１ａ）を互いに近接して配置し，これら吸気弁（１０）及び排気弁（１１）の両軸線（Ｏ１，Ｏ２）を含む平面（Ａ）の一側方において前記点火栓（１２）の電極（１２ａ）を前記燃焼室（６）の周縁部に近接配置したことを特徴とする，内燃機関の燃焼室構造。In claim 1 or 2 ,
Each one of the intake valves on the ceiling surface of the combustion chamber (6) (10) and the valve head (10a, 11a) of the exhaust valve (11) close to one another and disposed, the intake valve (10) and an exhaust valve (11) both the axis (O 1, O 2) of the electrodes (12a) of said spark plug (12) that has been arranged close to the periphery of the combustion chamber (6) at one side of the plane (a) containing Combustion chamber structure for internal combustion engines.
JP17154998A 1998-06-18 1998-06-18 Combustion chamber structure of internal combustion engine Expired - Fee Related JP3966619B2 (en)

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JPS5843565A (en) * 1981-09-09 1983-03-14 Toshiba Corp Semiconductor integrated circuit device
US4759323A (en) * 1985-12-20 1988-07-26 Glotur Trust Reg. Combustion engine with one or more "squish" spaces between the piston and the cylinder head
CN86202122U (en) * 1986-03-29 1986-12-10 湖南长沙汽车发动机研究所 Engine for light-duty vehicle

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JP2000008860A (en) 2000-01-11
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