JPH10331645A - Cylinder injection type internal combustion engine - Google Patents
Cylinder injection type internal combustion engineInfo
- Publication number
- JPH10331645A JPH10331645A JP9144927A JP14492797A JPH10331645A JP H10331645 A JPH10331645 A JP H10331645A JP 9144927 A JP9144927 A JP 9144927A JP 14492797 A JP14492797 A JP 14492797A JP H10331645 A JPH10331645 A JP H10331645A
- Authority
- JP
- Japan
- Prior art keywords
- swirl flow
- cavity
- intake
- side wall
- internal combustion
- 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
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
- F02B75/12—Other methods of operation
- F02B2075/125—Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber
-
- 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
Landscapes
- Fuel-Injection Apparatus (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、筒内に燃料噴霧を
直接噴射して点火プラグによって火花点火を行う筒内噴
射式内燃機関において、特に、排気性状及び燃費の向上
を図る技術に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder injection type internal combustion engine in which fuel spray is directly injected into a cylinder to perform spark ignition by a spark plug, and more particularly to a technique for improving exhaust characteristics and fuel efficiency.
【０００２】[0002]
【従来の技術】従来、筒内噴射式内燃機関としては、例
えば、特開平８−３５４２９号公報に開示されるよう
に、成層燃焼運転時には、圧縮行程後期に燃料噴霧をピ
ストン頂面の凹状燃焼室（以下「キャビティ」という）
に向けて噴射し、筒内の吸気スワール流（以下「スワー
ル流」という）の作用とキャビティ側壁のガイド作用と
の相乗作用によって、燃料噴霧が点火プラグ下方に効率
良く移送されるようにして可燃混合気の成層化を図り、
成層燃焼を可能としたものが知られている。2. Description of the Related Art Conventionally, in a cylinder injection type internal combustion engine, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-35429, during a stratified charge combustion operation, fuel spray is applied to a concave combustion on the piston top surface in the latter stage of the compression stroke. Chamber (hereinafter referred to as “cavity”)
By the action of intake swirl flow (hereinafter referred to as "swirl flow") in the cylinder and the guide action of the side wall of the cavity, so that the fuel spray is efficiently transferred to below the spark plug so as to be flammable. Stratify the mixture,
What has enabled stratified combustion is known.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、従来の
筒内噴射式内燃機関では、図８に示すように、ピストン
頂面１に形成されたキャビティ２の側壁高さが、筒内の
スワール流の上流側と下流側とで略等しいため、次のよ
うな問題点があった。即ち、成層燃焼運転時には、キャ
ビティ２内に噴射された燃料噴霧Ｆは、筒内のスワール
流Ｓに流されながら、スワール流Ｓの下流側に位置する
キャビティ２側壁に沿って点火プラグ３下方まで移送さ
れるため、スワール流Ｓの上流側に位置するキャビティ
２側壁は、かかるガイド作用に何ら寄与せず、燃焼室に
おける表面積／体積比（Ｓ／Ｖ比）を増大させる原因と
なっていた。Ｓ／Ｖ比の増大は、ピストン頂面１及びキ
ャビティ２内壁面を介して放出される熱量の増大を招
き、燃焼効率の低下による燃費の低下のおそれがあっ
た。However, in the conventional in-cylinder injection type internal combustion engine, as shown in FIG. 8, the height of the side wall of the cavity 2 formed on the piston top surface 1 is limited by the swirl flow in the cylinder. Since the upstream side and the downstream side are substantially equal, there were the following problems. That is, during the stratified charge combustion operation, the fuel spray F injected into the cavity 2 is flown by the swirl flow S in the cylinder, and along the side wall of the cavity 2 located downstream of the swirl flow S to a position below the ignition plug 3. Because of the transfer, the side wall of the cavity 2 located on the upstream side of the swirl flow S does not contribute to such a guiding action at all, causing an increase in the surface area / volume ratio (S / V ratio) in the combustion chamber. An increase in the S / V ratio causes an increase in the amount of heat released through the piston top surface 1 and the inner wall surface of the cavity 2, and there is a possibility that fuel efficiency may decrease due to a decrease in combustion efficiency.
【０００４】一方、均質燃焼運転時には、吸気行程中に
燃料噴霧Ｆを筒内に噴射して、筒内に略均一な可燃混合
気を形成する。ここで、機関が高負荷で運転される場合
を考えると、所定の燃料噴射量を確保するため吸気行程
初期から燃料噴霧Ｆの噴射が開始される。このとき、噴
射される燃料噴霧Ｆは、キャビティ２側壁に付着するた
め、燃料と空気との混合不良が生じ、最大出力の低下と
すすの発生が起こるおそれがあった。また、機関が中負
荷で運転される場合には、成層燃焼運転時と同様に、Ｓ
／Ｖ比の増大による燃費の低下のおそれがあった。[0004] On the other hand, during the homogeneous combustion operation, the fuel spray F is injected into the cylinder during the intake stroke to form a substantially uniform combustible mixture in the cylinder. Here, considering the case where the engine is operated under a high load, the injection of the fuel spray F is started from the beginning of the intake stroke in order to secure a predetermined fuel injection amount. At this time, since the injected fuel spray F adheres to the side wall of the cavity 2, there is a possibility that poor mixing of the fuel and the air occurs, so that the maximum output is reduced and soot is generated. Further, when the engine is operated with a medium load, S
There is a possibility that fuel efficiency may decrease due to an increase in the / V ratio.
【０００５】そこで、本発明は以上のような従来の問題
点に鑑み、ピストン頂面に形成されたキャビティ形状を
見直すことによって、表面積／体積比の改善による燃費
の向上、及び、キャビティ側壁への燃料噴霧の付着を低
減することによる排気性状の向上を共に実現した筒内噴
射式内燃機関を提供することを目的とする。[0005] In view of the above problems, the present invention reviews the shape of the cavity formed on the top surface of the piston, thereby improving the fuel efficiency by improving the surface area / volume ratio and improving the side wall of the cavity. It is an object of the present invention to provide an in-cylinder injection type internal combustion engine that achieves both improved exhaust properties by reducing the adhesion of fuel spray.
【０００６】[0006]
【課題を解決するための手段】このため、請求項１記載
の発明は、ピストン頂面とシリンダヘッド下面との間に
形成された燃焼室の吸気側壁面に配設された燃料噴射弁
により燃焼室内に燃料噴霧を直接噴射し、燃焼室のピス
トン頂面と対向する壁面の略中央部に配設された点火プ
ラグによって火花点火を行う筒内噴射式内燃機関におい
て、前記燃焼室内に吸気のスワール流を発生させるスワ
ール流発生手段を、吸気通路に設けると共に、前記ピス
トン頂面の燃料噴射弁と点火プラグとを結ぶ線下の位置
に開口部が上面に形成された略円柱形状のキャビティを
形成し、前記キャビティの側壁高さを、前記吸気スワー
ル流の下流側より上流側が低くなるように形成した。According to the present invention, a fuel injection valve disposed on an intake side wall of a combustion chamber formed between a top surface of a piston and a lower surface of a cylinder head is used for combustion. In a direct injection internal combustion engine in which a fuel spray is directly injected into a chamber and spark ignition is performed by a spark plug arranged at a substantially central portion of a wall surface opposed to a piston top surface of the combustion chamber, a swirl of intake air enters the combustion chamber. A swirl flow generating means for generating a flow is provided in the intake passage, and a substantially cylindrical cavity having an opening formed on the upper surface at a position below a line connecting the fuel injection valve and the ignition plug on the top surface of the piston is formed. Then, the height of the side wall of the cavity is formed so as to be lower on the upstream side than on the downstream side of the intake swirl flow.
【０００７】かかる構成によれば、吸気スワール流の上
流側に位置するキャビティ側壁高さが、下流側に位置す
るキャビティ側壁高さより低くなるので、ピストン頂面
の表面積が減少すると共に、均質燃焼運転中に噴射され
る燃料噴霧のうち、キャビティ側壁に付着する燃料噴霧
量が低減する。従って、ピストン頂面の表面積の減少に
より、燃焼室における表面積／体積比が小さくなり、ピ
ストン表面を介して放出される熱量が減り、燃焼効率が
向上する。また、キャビティ壁面に付着する燃料噴霧量
が低減することにより、燃料と空気との混合不良が軽減
し、排出されるすすの量が減る。According to this configuration, the height of the cavity side wall located on the upstream side of the intake swirl flow is lower than the height of the cavity side wall located on the downstream side, so that the surface area of the piston top surface is reduced and the homogeneous combustion operation is performed. Among the fuel spray injected inside, the amount of fuel spray adhering to the side wall of the cavity is reduced. Accordingly, the surface area / volume ratio in the combustion chamber is reduced due to the decrease in the surface area of the piston top surface, the amount of heat released through the piston surface is reduced, and the combustion efficiency is improved. In addition, by reducing the amount of fuel spray adhering to the cavity wall surface, poor mixing of fuel and air is reduced, and the amount of soot discharged is reduced.
【０００８】請求項２記載の発明は、前記スワール流発
生手段は、吸気通路に介装されたスワールコントロール
バルブから構成され、該スワールコントロールバルブ
は、バルブ本体と、該バルブ本体を吸気通路に回動自由
に支承する回動支軸とから構成され、前記バルブ本体に
は、その一部を切除して開口部が形成された構成とし
た。According to a second aspect of the present invention, the swirl flow generating means comprises a swirl control valve interposed in an intake passage. The swirl control valve is provided with a valve body and a valve for turning the valve body to the intake passage. The valve body is configured to have an opening formed by partially cutting off the valve body.
【０００９】かかる構成によれば、バルブ本体の開閉制
御を行うだけで、吸気スワール流の生成が行われる。請
求項３記載の発明は、前記キャビティの少なくとも前記
吸気スワール流の上流側の側壁高さを、該吸気スワール
流の下流方向に徐々に高くなるように形成した。According to this structure, the intake swirl flow is generated only by controlling the opening and closing of the valve body. According to a third aspect of the present invention, the height of at least the side wall of the cavity on the upstream side of the intake swirl flow is gradually increased in the downstream direction of the intake swirl flow.
【００１０】かかる構成によれば、請求項１又は２に記
載の発明に比べて、ピストン頂面の表面積がより減少
し、燃焼効率がより向上する。請求項４記載の発明は、
前記キャビティの少なくとも前記吸気スワール流の上流
側のの内底面を、該吸気スワール流の下流方向に徐々に
低位となる傾斜面に形成した。According to this configuration, the surface area of the piston top surface is further reduced and the combustion efficiency is further improved as compared with the first or second aspect of the invention. The invention according to claim 4 is
At least the inner bottom surface of the cavity on the upstream side of the intake swirl flow is formed as an inclined surface that gradually becomes lower in the downstream direction of the intake swirl flow.
【００１１】かかる構成によれば、請求項３記載の発明
に比べて、ピストン頂面の表面積がさらに減少し、燃焼
効率がさらに向上する。請求項５記載の発明は、前記点
火プラグは、前記吸気スワール流の下流方向にオフセッ
トされて配設される構成とした。かかる構成によれば、
燃焼室内における火炎伝播が均一化され、燃焼効率が向
上する。According to this configuration, the surface area of the piston top surface is further reduced, and the combustion efficiency is further improved, as compared with the third aspect of the invention. The invention according to claim 5 is configured such that the spark plug is arranged so as to be offset in a downstream direction of the intake swirl flow. According to such a configuration,
The flame propagation in the combustion chamber is made uniform, and the combustion efficiency is improved.
【００１２】請求項６記載の発明は、ピストン頂面に形
成したキャビティの側壁高さを、吸気スワール流の下流
側より上流側が低くなるように形成することにより、ピ
ストン頂面の表面積を小さくすると共に、均質燃焼運転
時に、噴射された燃料噴霧がキャビティ側壁に付着し難
くした。かかる構成によれば、ピストン頂面に形成した
キャビティの側壁高さは、吸気スワール流の下流側より
上流側が低くなるように形成されているので、ピストン
頂面の表面積が減少すると共に、均質燃焼運転中に、噴
射される燃料噴霧のうち、キャビティ側壁に付着する燃
料噴霧量が低減する。According to the present invention, the height of the side wall of the cavity formed on the top surface of the piston is made lower on the upstream side than on the downstream side of the intake swirl flow, thereby reducing the surface area of the piston top surface. In addition, during the homogeneous combustion operation, the injected fuel spray hardly adhered to the side wall of the cavity. According to this configuration, the height of the side wall of the cavity formed on the piston top surface is formed so as to be lower on the upstream side than on the downstream side of the intake swirl flow. During operation, the amount of fuel spray adhering to the side wall of the cavity among the injected fuel sprays is reduced.
【００１３】従って、ピストン頂面の表面積の減少によ
り、燃焼室における表面積／体積比が小さくなり、ピス
トン表面を介して放出される熱量が減り、燃焼効率が向
上する。また、キャビティ壁面に付着する燃料噴霧量が
低減することにより、燃料と空気との混合不良が軽減
し、排出されるすすの量が減る。Accordingly, the surface area / volume ratio in the combustion chamber is reduced due to the decrease in the surface area of the piston top surface, the amount of heat released through the piston surface is reduced, and the combustion efficiency is improved. In addition, by reducing the amount of fuel spray adhering to the cavity wall surface, poor mixing of fuel and air is reduced, and the amount of soot discharged is reduced.
【００１４】[0014]
【発明の効果】以上説明したように、請求項１又は６記
載の発明によれば、燃焼効率が向上するので、燃費を向
上することができる。また、排出されるすすの量が減少
するので、排気性状を向上することができる。請求項２
記載の発明によれば、吸気スワール流を簡単な構成で生
成することができる。As described above, according to the first or sixth aspect of the present invention, the combustion efficiency is improved, so that the fuel efficiency can be improved. Further, since the amount of soot to be discharged is reduced, the exhaust properties can be improved. Claim 2
According to the described invention, the intake swirl flow can be generated with a simple configuration.
【００１５】請求項３〜５に記載の発明によれば、燃焼
効率がより向上するので、燃費をより向上することがで
きる。According to the third to fifth aspects of the present invention, the combustion efficiency is further improved, so that the fuel efficiency can be further improved.
【００１６】[0016]
【発明の実施の形態】以下、添付された図面を参照して
本発明を詳述する。図１及び図２は、本発明に係る筒内
噴射式内燃機関の第１実施形態を示す。ピストン１０の
頂面（以下「ピストン頂面」という）１０ａとシリンダ
ヘッド１１の下面との間には、所定容積を有する燃焼室
１２が形成される。燃焼室１２の上部に位置するシリン
ダヘッド１１の壁面、即ち、シリンダヘッド１１の下部
に形成されたシリンダヘッド燃焼室１２ａの壁面には、
吸気弁１３によって開閉される吸気ポート１４、及び、
排気弁１５によって開閉される吸気ポート１６が、夫々
並列して２つ形成される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. 1 and 2 show a first embodiment of a direct injection internal combustion engine according to the present invention. A combustion chamber 12 having a predetermined volume is formed between a top surface of the piston 10 (hereinafter, referred to as a “piston top surface”) 10 a and a lower surface of the cylinder head 11. On the wall surface of the cylinder head 11 located above the combustion chamber 12, that is, on the wall surface of the cylinder head combustion chamber 12a formed below the cylinder head 11,
An intake port 14 opened and closed by an intake valve 13, and
Two intake ports 16 opened and closed by the exhaust valve 15 are respectively formed in parallel.
【００１７】シリンダヘッド１１の両吸気ポート１４間
には、燃料噴霧を噴射する燃料噴射弁１７がピストン頂
面１０ａに対して所定角度を有するように配設される。
また、シリンダヘッド燃焼室１２ａの壁面の略中央部に
は、燃料と空気との可燃混合気を火花点火する点火プラ
グ１８が配設される。ここで、２つの吸気ポート１４に
接続される吸気通路１９には、燃焼室１２内に吸気のス
ワール流を生成させるスワールコントロールバルブ２０
（スワール流発生手段）が配設される。スワールコント
ロールバルブ２０は、バルブ本体２０ａと、バルブ本体
２０ａを吸気通路１９壁に回動自由に支承する回動支軸
２０ｂとから構成され、バルブ本体２０ａには、その一
部を切除して形成した開口部（図示せず）が形成され
る。A fuel injection valve 17 for injecting fuel spray is disposed between the intake ports 14 of the cylinder head 11 so as to have a predetermined angle with respect to the piston top surface 10a.
An ignition plug 18 for spark-igniting a combustible air-fuel mixture of fuel and air is disposed substantially at the center of the wall surface of the cylinder head combustion chamber 12a. Here, a swirl control valve 20 for generating a swirl flow of intake air in the combustion chamber 12 is provided in an intake passage 19 connected to the two intake ports 14.
(Swirl flow generating means) is provided. The swirl control valve 20 includes a valve body 20a and a pivot 20b that rotatably supports the valve body 20a on the wall of the intake passage 19, and is formed by cutting a part of the valve body 20a. An opening (not shown) is formed.
【００１８】また、ピストン１０には、ピストン頂面１
０ａの燃料噴射弁１７と点火プラグ１８とを結ぶ線下の
位置に、略円形の開口部２１ａが上面に形成された略円
柱形状のキャビティ２１が形成される。さらに、キャビ
ティ２１の側壁高さを、成層燃焼運転時において燃焼室
１２内に生成されるスワール流の下流側より上流側が低
くなるように形成する。具体的には、図２において、燃
焼室１２内に反時計回りのスワール流Ｓが生成されると
すると、燃料噴射弁１７の先端部におけるスワール流Ｓ
の上流側、即ち、図でピストン頂面１０ａの上半分を切
除加工してフラットピストン形状に形成する。The piston 10 has a piston top surface 1.
A substantially cylindrical cavity 21 having a substantially circular opening 21a formed on the upper surface is formed at a position below a line connecting the fuel injection valve 17 and the ignition plug 18 at 0a. Further, the height of the side wall of the cavity 21 is formed so that the swirl flow generated in the combustion chamber 12 during the stratified combustion operation is lower on the upstream side than on the downstream side. Specifically, in FIG. 2, assuming that a swirl flow S is generated in the combustion chamber 12 in a counterclockwise direction, the swirl flow S at the tip of the fuel injection valve 17 is assumed.
, Ie, the upper half of the piston top surface 10a in the figure is cut out to form a flat piston shape.
【００１９】次にかかる構成からなる筒内噴射式内燃機
関の作用について説明する。図３及び図４は、成層燃焼
運転時における可燃混合気の形成過程を示す。機関の圧
縮行程後期に、燃料噴射弁１７から燃料噴霧Ｆをピスト
ン１０のキャビティ２１内に向けて噴射する（図３参
照）。キャビティ２１内に噴射された燃料噴霧Ｆは、燃
焼室１２内の空気或いはピストン１０壁面との熱交換に
よって気化し、その大部分が可燃混合気Ｇとなる。そし
て、可燃混合気Ｇは、キャビティ２１外への拡散が最小
限に抑えられつつ、燃焼室１２内に生成されたスワール
流Ｓに流されながら、スワール流Ｓの下流側に位置する
キャビティ２１側壁に沿って点火プラグ１８の下方まで
移送され、点火プラグ１８の下方にのみ可燃混合気Ｇが
形成される（図４参照）。Next, the operation of the in-cylinder injection type internal combustion engine having the above configuration will be described. 3 and 4 show the process of forming a combustible air-fuel mixture during stratified charge combustion operation. In the latter half of the compression stroke of the engine, the fuel spray F is injected from the fuel injection valve 17 into the cavity 21 of the piston 10 (see FIG. 3). The fuel spray F injected into the cavity 21 is vaporized by heat exchange with the air in the combustion chamber 12 or the wall surface of the piston 10, and most of the fuel spray F becomes a combustible mixture G. The combustible air-fuel mixture G flows to the swirl flow S generated in the combustion chamber 12 while minimizing diffusion to the outside of the cavity 21, and the side wall of the cavity 21 located downstream of the swirl flow S Is transported to below the spark plug 18, and a combustible mixture G is formed only below the spark plug 18 (see FIG. 4).
【００２０】その後、機関運転条件に応じた点火時期
に、点火プラグ１８によって可燃混合気Ｇが火花点火さ
れ、成層燃焼が行われる。このような成層燃焼運転時に
おいては、可燃混合気Ｇの移送に何ら寄与しないスワー
ル流Ｓの上流側のキャビティ２１の側壁高さが、下流側
のキャビティ２１の側壁高さより低くなるように形成さ
れているので、燃焼室１２を形成するピストン頂面１０
ａの表面積が減少し、Ｓ／Ｖ比が小さくなる。従って、
ピストン頂面１０ａを介して放出される熱量が減少して
燃焼効率が向上し、燃費の向上を図ることができる。After that, the combustible mixture G is spark-ignited by the ignition plug 18 at the ignition timing according to the engine operating conditions, and stratified combustion is performed. In such a stratified combustion operation, the swirl flow S that does not contribute to the transfer of the combustible air-fuel mixture G is formed such that the side wall height of the upstream cavity 21 is lower than the side wall height of the downstream cavity 21. The piston top surface 10 forming the combustion chamber 12
The surface area of a decreases, and the S / V ratio decreases. Therefore,
The amount of heat released through the piston top surface 10a is reduced, the combustion efficiency is improved, and the fuel efficiency can be improved.
【００２１】図５は、均質燃焼運転時における可燃混合
気の形成過程を示す。機関の吸気行程中に、燃料噴射弁
１７から燃料噴霧Ｆを燃焼室１２内に噴射するが、特
に、機関が高負荷で運転されているときには、所定の燃
料噴射量を確保するため吸気行程初期から燃料噴霧Ｆの
噴射が開始される。燃焼室１２内に噴射された燃料噴霧
Ｆは、燃焼室１２内の空気或いはピストン１０壁面との
熱交換によって気化し、その大部分が可燃混合気Ｇとな
り、キャビティ２１内に入り込む。キャビティ２１内に
入り込んだ燃料噴霧Ｆは、キャビティ２１内に流入した
順タンブル流によって気化が促進され、可燃混合気Ｇの
形成が促進される。これと同時に、キャビティ２１内の
可燃混合気Ｇは、順タンブル流によってキャビティ２１
から追い出され、燃焼室１２全体に略均一な可燃混合気
Ｇが形成される。FIG. 5 shows a process of forming a combustible mixture during a homogeneous combustion operation. During the intake stroke of the engine, the fuel spray F is injected from the fuel injection valve 17 into the combustion chamber 12. Particularly, when the engine is operated under a high load, the initial stage of the intake stroke is performed to secure a predetermined fuel injection amount. Starts the injection of the fuel spray F. The fuel spray F injected into the combustion chamber 12 is vaporized by heat exchange with the air in the combustion chamber 12 or the wall of the piston 10, and most of the fuel spray F becomes a combustible mixture G and enters the cavity 21. The fuel spray F that has entered the cavity 21 is vaporized by the forward tumble flow that has flowed into the cavity 21, and the formation of the combustible mixture G is promoted. At the same time, the combustible air-fuel mixture G in the cavity 21
And a substantially uniform combustible gas mixture G is formed in the entire combustion chamber 12.
【００２２】その後、機関運転条件に応じた点火時期
に、点火プラグ１８によって可燃混合気Ｇが火花点火さ
れ、均質燃焼が行われる。このような高負荷の均質燃焼
運転時においては、成層燃焼運転時に生成されるスワー
ル流Ｓの上流側のキャビティ２１の側壁高さが、下流側
のキャビティ２１の側壁高さより低くなるように形成さ
れているので、燃料噴霧Ｆを噴射する際に、燃料噴霧Ｆ
がキャビティ２１側壁に付着することが少なくなり、燃
料と空気との混合不良が大幅に軽減する。また、成層燃
焼運転時と同様に、Ｓ／Ｖ比が小さくなることにより、
燃焼効率も向上する。従って、燃焼効率の向上により最
大出力が向上すると共に、燃料と空気との混合不良が軽
減することで、排出されるすすが減少し、排気性状を向
上することができる。Thereafter, the flammable mixture G is spark-ignited by the ignition plug 18 at an ignition timing according to the engine operating conditions, and homogeneous combustion is performed. In such a high-load homogeneous combustion operation, the swirl flow S generated during the stratified combustion operation is formed such that the side wall height of the upstream cavity 21 is lower than the side wall height of the downstream cavity 21. Therefore, when injecting the fuel spray F, the fuel spray F
Adhering to the side wall of the cavity 21 is reduced, and poor mixing of fuel and air is greatly reduced. Also, as in the case of the stratified charge combustion operation, the S / V ratio is reduced,
Combustion efficiency also improves. Accordingly, the maximum output is improved by improving the combustion efficiency, and the mixing failure of the fuel and the air is reduced, so that the discharged soot is reduced, and the exhaust property can be improved.
【００２３】図６は、本発明に係る筒内噴射式内燃機関
の第２実施形態を示す。即ち、キャビティ２１の側壁高
さを、成層燃焼運転時において燃焼室１２内に生成され
るスワール流の下流側より上流側が低くなるように形成
する際に、キャビティ２１の少なくともスワール流の上
流側の側壁高さが、スワール流の上流側から下流側に向
かって徐々に高くなるように形成する。FIG. 6 shows a second embodiment of the direct injection internal combustion engine according to the present invention. That is, when forming the side wall height of the cavity 21 so that the upstream side is lower than the downstream side of the swirl flow generated in the combustion chamber 12 during the stratified combustion operation, at least the upstream side of the swirl flow of the cavity 21 is formed. The side wall height is formed so as to gradually increase from the upstream side to the downstream side of the swirl flow.
【００２４】このようにすれば、先の第１実施形態より
ピストン頂面１０ａの表面積が減少し、Ｓ／Ｖ比がより
小さくなる。従って、燃焼効率がより向上し、燃費がよ
り低減する。図７は、本発明に係る筒内噴射式内燃機関
の第３実施形態を示す。即ち、先の第１実施形態におい
て、キャビティ２１の少なくともスワール流の上流側の
内底面を、スワール流の下流方向に徐々に低位となる傾
斜面に形成する。By doing so, the surface area of the piston top surface 10a is smaller than in the first embodiment, and the S / V ratio is smaller. Therefore, the combustion efficiency is further improved, and the fuel efficiency is further reduced. FIG. 7 shows a third embodiment of the direct injection internal combustion engine according to the present invention. That is, in the first embodiment, at least the inner bottom surface of the cavity 21 on the upstream side of the swirl flow is formed as an inclined surface that gradually becomes lower in the downstream direction of the swirl flow.
【００２５】このようにすれば、先の第１実施形態に比
べて、ピストン頂面１０ａの表面積が減少すると共に、
均質燃焼運転時において、噴射された燃料噴霧のうち、
キャビティ２１側壁に付着する燃料噴霧量がさらに低減
し、燃費及び排気性状のさらなる向上を図ることができ
る。なお、第３実施形態の特徴であるキャビティ２１内
底面を徐々に低位となる傾斜面に形成する構成は、先の
第２実施形態に適用することも可能である。この場合に
は、ピストン頂面１０ａの表面積がさらに減少し、燃費
及び排気性状を効果的に向上することができる。With this arrangement, the surface area of the piston top surface 10a is reduced as compared with the first embodiment, and
During the homogeneous combustion operation, of the injected fuel spray,
The amount of fuel spray adhering to the side wall of the cavity 21 can be further reduced, and the fuel efficiency and exhaust properties can be further improved. The configuration in which the inner bottom surface of the cavity 21 which is a feature of the third embodiment is formed as a gradually lowering inclined surface can be applied to the second embodiment. In this case, the surface area of the piston top surface 10a is further reduced, and fuel efficiency and exhaust properties can be effectively improved.
【００２６】また、点火プラグ１８をスワール流の下流
方向にオフセットして配設するようにしてもよい。この
場合には、燃焼室１２内における火炎伝播が均一化さ
れ、燃焼効率が向上し、さらなる燃費の向上が期待でき
る。Further, the ignition plug 18 may be arranged offset in the downstream direction of the swirl flow. In this case, the flame propagation in the combustion chamber 12 is made uniform, the combustion efficiency is improved, and further improvement in fuel efficiency can be expected.
【図１】 本発明の第１実施形態を示す構成図FIG. 1 is a configuration diagram showing a first embodiment of the present invention.
【図２】 同上のピストン頂面の詳細を示し、(a) は正
面図、(b) は上面図、(c) は(b) 中のＡ−Ａ断面図2A and 2B show details of a piston top surface of the above, wherein (a) is a front view, (b) is a top view, and (c) is a cross-sectional view taken along line AA in (b).
【図３】 同上の成層燃焼運転時における燃料噴射直後
の状態を示し、(a)は上面図、(b) は正面図、(c) は右
側面図FIG. 3 shows a state immediately after fuel injection during the stratified charge combustion operation, in which (a) is a top view, (b) is a front view, and (c) is a right side view.
【図４】 同上の成層燃焼運転時における点火直前の状
態を示し、(a) は上面図、(b) は正面図、(c) は右側面
図FIG. 4 shows a state immediately before ignition during the stratified charge combustion operation, in which (a) is a top view, (b) is a front view, and (c) is a right side view.
【図５】 同上の均質燃焼運転時における燃料噴射直後
の状態を示し、(a)は上面図、(b) は正面図、(c) は右
側面図FIG. 5 shows a state immediately after fuel injection in the same homogeneous combustion operation, in which (a) is a top view, (b) is a front view, and (c) is a right side view.
【図６】 本発明の第２実施形態におけるピストン頂面
の詳細を示し、(a)は正面図、(b) は上面図、(c) は(b)
中のＢ−Ｂ断面図6A and 6B show details of a piston top surface according to the second embodiment of the present invention, wherein FIG. 6A is a front view, FIG. 6B is a top view, and FIG.
BB sectional view in the middle
【図７】 本発明の第３実施形態におけるピストン頂面
の詳細を示し、(a)は正面図、(b) は上面図、(c) は(b)
中のＣ−Ｃ断面図7A and 7B show details of a piston top surface according to a third embodiment of the present invention, wherein FIG. 7A is a front view, FIG. 7B is a top view, and FIG.
CC sectional view in the middle
【図８】 従来の筒内噴射式内燃機関のピストン頂面形
状の詳細を示し、(a) は正面図、(b) は上面図8A and 8B show details of a piston top surface shape of a conventional in-cylinder injection type internal combustion engine, wherein FIG. 8A is a front view, and FIG.
１０ ピストン １０ａ ピストン頂面 １１ シリンダヘッド １２ 燃焼室 １２ａ シリンダヘッド燃焼室 １７ 燃料噴射弁 １８ 点火プラグ １９ 吸気通路 ２０ スワールコントロールバルブ ２０ａ バルブ本体 ２０ｂ 回動支軸 ２１ キャビティ Reference Signs List 10 piston 10a piston top surface 11 cylinder head 12 combustion chamber 12a cylinder head combustion chamber 17 fuel injection valve 18 ignition plug 19 intake passage 20 swirl control valve 20a valve body 20b rotation support shaft 21 cavity
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｆ０２Ｆ 3/28 Ｆ０２Ｆ 3/28 Ｂ Ｆ０２Ｍ 61/14 ３１０ Ｆ０２Ｍ 61/14 ３１０Ａ 69/00 ３６０ 69/00 ３６０Ｃ ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 6 Identification code FI F02F 3/28 F02F 3/28 B F02M 61/14 310 F02M 61/14 310A 69/00 360 69/00 360C
Claims (6)
に形成された燃焼室の吸気側壁面に配設された燃料噴射
弁により燃焼室内に燃料噴霧を直接噴射し、燃焼室のピ
ストン頂面と対向する壁面の略中央部に配設された点火
プラグによって火花点火を行う筒内噴射式内燃機関にお
いて、 前記燃焼室内に吸気のスワール流を発生させるスワール
流発生手段を、吸気通路に設けると共に、前記ピストン
頂面の燃料噴射弁と点火プラグとを結ぶ線下の位置に開
口部が上面に形成された略円柱形状のキャビティを形成
し、前記キャビティの側壁高さを、前記吸気スワール流
の下流側より上流側が低くなるように形成したことを特
徴とする筒内噴射式内燃機関。1. A fuel injection valve disposed on an intake side wall surface of a combustion chamber formed between a top surface of a piston and a lower surface of a cylinder head, directly injects fuel spray into a combustion chamber by a fuel injection valve. A direct-injection internal combustion engine that performs spark ignition by a spark plug disposed at a substantially central portion of a wall surface facing the swirl flow, wherein a swirl flow generating means for generating a swirl flow of intake air in the combustion chamber is provided in an intake passage. A substantially cylindrical cavity having an opening formed on an upper surface thereof at a position below a line connecting the fuel injection valve and the ignition plug on the top surface of the piston is formed, and the height of the side wall of the cavity is determined by the flow rate of the intake swirl flow. An in-cylinder injection type internal combustion engine, wherein an upstream side is formed lower than a downstream side.
装されたスワールコントロールバルブから構成され、該
スワールコントロールバルブは、バルブ本体と、該バル
ブ本体を吸気通路に回動自由に支承する回動支軸とから
構成され、前記バルブ本体には、その一部を切除して開
口部が形成された構成である請求項１記載の筒内噴射式
内燃機関。2. The swirl flow generating means comprises a swirl control valve interposed in an intake passage. The swirl control valve has a valve main body and a swivel for rotatably supporting the valve main body in the intake passage. 2. The direct injection internal combustion engine according to claim 1, wherein the valve main body is configured to have an opening formed by partially cutting off the valve body.
ール流の上流側の側壁高さは、該吸気スワール流の下流
方向に徐々に高くなるように形成された構成である請求
項１又は２記載の筒内噴射式内燃機関。3. The cylinder according to claim 1, wherein a height of at least a side wall of the cavity on the upstream side of the intake swirl flow is gradually increased in a downstream direction of the intake swirl flow. Internal injection type internal combustion engine.
ール流の上流側の内底面は、該吸気スワール流の下流方
向に徐々に低位となる傾斜面に形成された構成である請
求項１〜３のいずれか１つに記載の筒内噴射式内燃機
関。4. The structure according to claim 1, wherein at least an inner bottom surface of the cavity on the upstream side of the intake swirl flow is formed as an inclined surface that gradually becomes lower in the downstream direction of the intake swirl flow. The direct injection internal combustion engine according to any one of the preceding claims.
下流方向にオフセットされて配設された構成である請求
項１〜４のいずれか１つに記載の筒内噴射式内燃機関。5. The direct injection internal combustion engine according to claim 1, wherein the ignition plug is arranged so as to be offset in a downstream direction of the intake swirl flow.
高さを、吸気スワール流の下流側より上流側が低くなる
ように形成することにより、ピストン頂面の表面積を小
さくすると共に、均質燃焼運転時に、噴射された燃料噴
霧がキャビティ側壁に付着し難くしたことを特徴とする
筒内噴射式内燃機関。6. The surface of the piston top surface is reduced by forming the height of the side wall of the cavity formed on the piston top surface to be lower on the upstream side than on the downstream side of the intake swirl flow. An in-cylinder injection type internal combustion engine characterized in that the injected fuel spray hardly adheres to the side wall of the cavity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14492797A JP3644199B2 (en) | 1997-06-03 | 1997-06-03 | In-cylinder internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14492797A JP3644199B2 (en) | 1997-06-03 | 1997-06-03 | In-cylinder internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10331645A true JPH10331645A (en) | 1998-12-15 |
| JP3644199B2 JP3644199B2 (en) | 2005-04-27 |
Family
ID=15373457
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14492797A Expired - Lifetime JP3644199B2 (en) | 1997-06-03 | 1997-06-03 | In-cylinder internal combustion engine |
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| Country | Link |
|---|---|
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106640337A (en) * | 2016-12-16 | 2017-05-10 | 上海理工大学 | Anticlockwise-tumble-ratio combustion system for automotive engine |
-
1997
- 1997-06-03 JP JP14492797A patent/JP3644199B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106640337A (en) * | 2016-12-16 | 2017-05-10 | 上海理工大学 | Anticlockwise-tumble-ratio combustion system for automotive engine |
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| Publication number | Publication date |
|---|---|
| JP3644199B2 (en) | 2005-04-27 |
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