JPH03149314A - Combustion chamber of direct injection type diesel engine - Google Patents
Combustion chamber of direct injection type diesel engineInfo
- Publication number
- JPH03149314A JPH03149314A JP1289744A JP28974489A JPH03149314A JP H03149314 A JPH03149314 A JP H03149314A JP 1289744 A JP1289744 A JP 1289744A JP 28974489 A JP28974489 A JP 28974489A JP H03149314 A JPH03149314 A JP H03149314A
- Authority
- JP
- Japan
- Prior art keywords
- combustion chamber
- combustion
- protrusion
- fuel
- end surface
- 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
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 56
- 238000002347 injection Methods 0.000 title claims abstract description 36
- 239000007924 injection Substances 0.000 title claims abstract description 36
- 239000000446 fuel Substances 0.000 claims abstract description 32
- 239000007921 spray Substances 0.000 claims abstract description 25
- 230000002093 peripheral effect Effects 0.000 claims abstract description 11
- 239000000779 smoke Substances 0.000 abstract description 6
- 230000007423 decrease Effects 0.000 abstract description 2
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract 6
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 239000000203 mixture Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 208000000260 Warts Diseases 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 201000010153 skin papilloma Diseases 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
- F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
- F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
- F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
- F02B23/0672—Omega-piston bowl, i.e. the combustion space having a central projection pointing towards the cylinder head and the surrounding wall being inclined towards the cylinder center axis
-
- 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
- F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
- F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
- F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
- F02B23/0645—Details related to the fuel injector or the fuel spray
- F02B23/0648—Means or methods to improve the spray dispersion, evaporation or ignition
- F02B23/0651—Means or methods to improve the spray dispersion, evaporation or ignition the fuel spray impinging on reflecting surfaces or being specially guided throughout the combustion space
-
- 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
- F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
- F02B2275/14—Direct injection into combustion chamber
-
- 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
- F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
- F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
- F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
- F02B23/0618—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston having in-cylinder means to influence the charge motion
- F02B23/0621—Squish flow
-
- 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
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
-
- 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
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Dispersion Chemistry (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
１ 一
本発明は、シリンダ内に上方から直接燃料噴射弁を臨ま
せ、ピストン上壁に上記燃料噴射弁へ向いて開口する燃
焼室を形成した直接噴射式ディーゼル機関の燃焼室に関
する。Detailed Description of the Invention (Industrial Field of Application) 1. The present invention provides a cylinder with a fuel injection valve facing directly from above, and a combustion chamber that opens toward the fuel injection valve on the upper wall of the piston. The present invention relates to the combustion chamber of a direct injection diesel engine.
（従来技術）
この種ディーゼル機関における従来の燃焼室は、第１４
図のようなトロイダル型、第１５図のような浅皿型ある
いは第１６図のような内周テーパ一面を有するスキッシ
ュリップ型等がある。(Prior art) The conventional combustion chamber in this type of diesel engine is the 14th combustion chamber.
There are a toroidal type as shown in the figure, a shallow dish type as shown in Fig. 15, and a squish lip type with a tapered inner surface as shown in Fig. 16.
ところがこのような燃焼室では燃料の噴霧を抑制する手
段がないため、噴射初期において一連の燃焼が急激に行
なわれ、第７図の実線のグラフＸｌで示すようにクラン
ク角θ２ （燃焼初期）付近で熱発生率が急激に上昇す
る。これにより噴射初期におけ−るＮＯｘの排出量が多
くなるという不具合が生じる。However, in such a combustion chamber, there is no means to suppress fuel spray, so a series of combustions occur rapidly at the beginning of injection, and as shown by the solid line graph The heat release rate increases rapidly. This causes a problem that the amount of NOx discharged at the initial stage of injection increases.
なお特公昭３４−６７５３のように燃焼室の中央部に突
起部を形成したものもあるが、ピストン下降中、燃料噴
霧の全部が常に突起部上端面に当接するようになってお
り、したがって燃料付着量が多すぎ、燃焼しに＜＜、黒
煙発生量が多い。Note that there are some models, such as the one in Tokuko Sho 34-6753, that have a protrusion formed in the center of the combustion chamber, but all of the fuel spray always comes into contact with the upper end surface of the protrusion while the piston is descending, so that the fuel is The amount of adhesion is too large, and the amount of black smoke generated is too large to burn.
（発明の目的）
本発明の目的は、噴射初期に生成されるＮＯｘを低減し
、燃焼中期以降ではバックスキッシュの渦流により混合
気形成を良くして、黒煙の発生を減少させることである
。(Objective of the Invention) The object of the present invention is to reduce NOx generated in the initial stage of injection, improve mixture formation by back squish vortex flow after the middle stage of combustion, and reduce the generation of black smoke.
（目的を達成するための技術的手段）
上記目的を達成するために本発明は、燃焼室の内周面を
上端部が狭くなるような環状テーパ面に形成し、燃焼室
の中央部に上方へ突出する中央突起部を形成して、該突
起部の上端面を概ね緩やかな円錐状に形成し、突起部の
上方に位置する燃料噴射弁の燃料噴射角度と突起部上端
面との関係を、噴射初期においては噴霧域の一部が突起
部上端面に当接して初期燃焼を抑制し、燃焼中期以降に
おいてはピストンの下降により噴霧域全域が突起部から
離れてテーパ内周面に向かって噴射されるように設定し
ている。(Technical Means for Achieving the Object) In order to achieve the above object, the present invention forms the inner circumferential surface of the combustion chamber into an annular tapered surface that is narrower at the upper end. A central protrusion is formed that protrudes into the protrusion, and the upper end surface of the protrusion is formed into a generally gentle conical shape, and the relationship between the fuel injection angle of the fuel injection valve located above the protrusion and the upper end surface of the protrusion is determined. At the beginning of injection, part of the spray area comes into contact with the upper end surface of the protrusion to suppress initial combustion, and after the middle stage of combustion, the entire spray area moves away from the protrusion and toward the tapered inner peripheral surface due to the downward movement of the piston. It is set to be sprayed.
（作用）
噴射初期においては燃料噴射弁から噴射される噴霧の一
部が中央突起部にびっかかり、初期燃焼が抑制され、そ
れによりＮＯＸが減少する。(Function) At the initial stage of injection, a portion of the spray injected from the fuel injection valve catches on the central protrusion, suppressing initial combustion and thereby reducing NOx.
ピストンの下降に従って噴霧域か中央突起部から外れて
いき、かつ燃料噴射弁から燃焼室内周向までの距離か長
くなり、燃料中期以降は高圧噴霧が略すべてテーパー内
周面に当るようになり、それにより勢いのよいバックス
キッシュの渦流か形成される。従って混合気形成かよく
なって、黒煙の発生が抑制される。As the piston descends, the spray area moves away from the central protrusion, and the distance from the fuel injector to the circumferential direction of the combustion chamber increases, and from the middle of the fuel stage onward, almost all of the high-pressure spray hits the tapered inner circumferential surface. As a result, a powerful back squish vortex is formed. Therefore, the air-fuel mixture is formed better and the generation of black smoke is suppressed.
また前述の燃焼初期で突起部上端面に溜っていた燃料は
徐々に蒸発し、燃焼する。Further, the fuel accumulated on the upper end surface of the protrusion at the early stage of combustion is gradually evaporated and burned.
（実施例）
第１図は本発明を適用しｔ：直接噴射式ディーゼル機関
のスキッシュリップ型燃焼室の断面図を示しており、こ
の第１図において、シリンダヘッド２には燃料噴射弁３
が少し傾斜した状態で固定されており、燃料噴射弁３の
下端ノズル部はシリンダ４の中心線０１から少しずれた
位置に位置すると共に、シリンダ４内に上方から臨んで
いる。(Embodiment) Fig. 1 shows a sectional view of a squish lip type combustion chamber of a direct injection diesel engine to which the present invention is applied.
is fixed in a slightly inclined state, and the lower end nozzle portion of the fuel injection valve 3 is located at a position slightly shifted from the center line 01 of the cylinder 4 and faces into the cylinder 4 from above.
ピストン１の上壁には、上記燃料噴射弁３のノズル部と
同じ位置の中心線０２を中心とする円盤形の燃焼室５が
上端開口状に形成されている。燃焼室５の環状の内周面
７は上端部側が狭くなるようにテーパー状に形成されて
おり、該テーパー内周面７の下端部分は円弧形部分７ａ
を介して燃焼室底壁５ａにつながっている。A disk-shaped combustion chamber 5 is formed in the upper wall of the piston 1 and has an open upper end, the combustion chamber 5 being centered on a center line 02 at the same position as the nozzle portion of the fuel injection valve 3 . The annular inner circumferential surface 7 of the combustion chamber 5 is tapered so that the upper end side becomes narrower, and the lower end portion of the tapered inner circumferential surface 7 is an arcuate portion 7a.
It is connected to the combustion chamber bottom wall 5a via.
燃焼室５の中央部には底壁５ａ部分から上方に突出する
円筒状の中央突起部１０が形成されており、該突起部１
０の上端面１０ａは燃焼室中心線ｏ２を中心とする緩や
かな円錐状に形成されている。中央突起部１０の上端面
１０ａはピストン１の上端面よりも少し低い位置に形成
されている。A cylindrical central projection 10 is formed in the center of the combustion chamber 5 and projects upward from the bottom wall 5a.
The upper end surface 10a of the combustion chamber 0 is formed into a gentle conical shape centered on the combustion chamber centerline o2. The upper end surface 10a of the central protrusion 10 is formed at a position slightly lower than the upper end surface of the piston 1.
中央突起部１０の上端部周囲は円弧形部分１０ｃを介し
て燃焼室底壁５ａにつながっている。The periphery of the upper end of the central protrusion 10 is connected to the combustion chamber bottom wall 5a via an arcuate portion 10c.
燃料噴射弁３の先端ノズル部には複数の噴口が形成され
、各噴口から噴射される噴霧Ｐの仮想中心線Ａと燃焼室
中心線０２とのなず噴射角度αは、中央突起部１０との
関係上次のように設定されている。A plurality of nozzles are formed in the tip nozzle portion of the fuel injection valve 3, and the injection angle α between the virtual centerline A of the spray P injected from each nozzle and the combustion chamber centerline 02 is the same as that of the central protrusion 10. The settings are as follows.
第１図の噴射開始時において、その噴霧Ｐの概ね５０％
が中央突起部１０の上端面１０ａに当接し、噴射中期に
おいて第３図のように噴霧Ｐが中央突起部１０の上端面
１０ａから略完全にはずれ、噴霧Ｐかテーパー内周面７
に当接するように設定されている。ちなみに第１図では
上記仮想中心線Ａが中央突起部１０の上端面１０ａの路
外周端縁を通過するようになっている。At the start of injection in Figure 1, approximately 50% of the spray P
touches the upper end surface 10a of the central projection 10, and in the middle of injection, the spray P is almost completely separated from the upper end surface 10a of the central projection 10 as shown in FIG.
It is set so that it comes into contact with. Incidentally, in FIG. 1, the virtual center line A passes through the outer peripheral edge of the upper end surface 10a of the central protrusion 10.
第６図において、中央突起部１０の上端面１０ａには、
燃料の付着量を制御するために直径が異なる複数の同心
の環状溝１２か形成されている。In FIG. 6, on the upper end surface 10a of the central protrusion 10,
A plurality of concentric annular grooves 12 of different diameters are formed to control the amount of fuel deposited.
環状溝１２の断面形状は中心線０２から半径方向外方に
ゆくに従い徐々に深くなってゆくようなくさび形状に形
成されている。The cross-sectional shape of the annular groove 12 is formed into a wedge shape that gradually becomes deeper as it goes radially outward from the center line 02.
作動を説明する。噴射開始時においては第１図のように
噴霧Ｐの略５０％が燃焼室５内に直接入り、残りの５０
％は突起部１０の上端面１０ａに当接し、その一部は燃
焼室５内へと滑っていくが、残りは上端面１０ａの環状
溝１２内に溜る。これにより燃焼初期における急激な燃
焼は抑えられ、ＮＯＸの排出量は減少する。Explain the operation. At the start of injection, approximately 50% of the spray P enters directly into the combustion chamber 5, as shown in Figure 1, and the remaining 50%
% comes into contact with the upper end surface 10a of the protrusion 10, and part of it slides into the combustion chamber 5, but the rest remains in the annular groove 12 of the upper end surface 10a. This suppresses rapid combustion in the initial stage of combustion, and reduces the amount of NOx emissions.
ピストン１の下降に従い第２図のように燃料噴射弁３か
ら突起部１０が遠ざかると共に噴霧Ｐは突起部１０の上
端面１０ａに当接する割合が減少してゆき、第３図のよ
うに噴射中期に入る頃において、噴霧Ｐは略その全部が
突起部１０の上端面１０ａから外れる。そして噴霧長さ
が長くなると共に圧力が増加し、燃焼室５のテーパー内
周面７に当接し、第４図のようにバックスキッシュ流Ｓ
が形成されて火炎は拡散し、燃焼が促進される。As the piston 1 descends, the projection 10 moves away from the fuel injector 3 as shown in FIG. 2, and the proportion of the spray P that comes into contact with the upper end surface 10a of the projection 10 decreases, and as shown in FIG. At the time when the spray P enters, almost all of the spray P is removed from the upper end surface 10a of the protrusion 10. As the length of the spray increases, the pressure increases, and the spray comes into contact with the tapered inner circumferential surface 7 of the combustion chamber 5, resulting in a back squish flow S as shown in FIG.
is formed, the flame spreads, and combustion is promoted.
一方突起部１０の溝１２に溜っていた燃料は蒸発し、バ
ックスキッシュ流Ｓの火炎と共に燃焼する。On the other hand, the fuel accumulated in the groove 12 of the protrusion 10 evaporates and burns together with the flame of the back squish flow S.
燃焼中期から後期にかけては、第５図のように噴霧Ｐは
一部が直接ピストン１とシリンダヘッド２の間に供給さ
れる。From the middle to late stages of combustion, a portion of the spray P is directly supplied between the piston 1 and the cylinder head 2, as shown in FIG.
第７図に破線で示すグラフＸ２は本発明の燃焼室を使用
した場合の熱発生率の変化であり、クランク角θｌ〜θ
５はそれぞれ第１図〜第５図に対応している。Ｘｉで示
す従来例に比べ、燃焼初期（θｌ〜θ３）における熱発
生率が大幅に減少しており、そして略滑らかに初期から
中期へと熱発生率が増加している。Graph X2 shown with a broken line in FIG.
5 correspond to FIGS. 1 to 5, respectively. Compared to the conventional example indicated by Xi, the heat release rate at the early stage of combustion (θl to θ3) is significantly reduced, and the heat release rate increases almost smoothly from the early stage to the middle stage.
従って第８図の下部のＮＯｘのグラフに示すように、従
来例Ｘｉに比べＮＯｘ排出量は大幅に減少している。Therefore, as shown in the NOx graph at the bottom of FIG. 8, the amount of NOx discharged is significantly reduced compared to the conventional example Xi.
またピストン１の下降と共に燃料噴射弁３から燃焼室内
周面７までの距離が長くなってバックスキッシュ流によ
り混合気形成がよくなるので、第８図の上部のグラフに
示すように従来例Ｘ１に比べて排気色も減少する。Furthermore, as the piston 1 descends, the distance from the fuel injection valve 3 to the combustion chamber peripheral surface 7 becomes longer, and the back squish flow improves the mixture formation. This also reduces exhaust color.
（別の実施例） −
（１）第９図は突起部１０の上端面１０ａの付近に滞留
している蒸発噴霧Ｑをバックスキッシュ流Ｓに乗せ易く
するために、中央突起部１０の周壁に環状のくびれ部１
５を形成した構造である。中央突起部１０の周壁の上部
付近が最小外径になるように湾曲状にくびれでいる。(Another embodiment) - (1) In Fig. 9, in order to make it easier for the evaporative spray Q staying in the vicinity of the upper end surface 10a of the protrusion 10 to be transferred to the back squish flow S, the peripheral wall of the central protrusion 10 is Annular constriction 1
This is the structure in which 5 was formed. The peripheral wall of the central protrusion 10 is constricted in a curved manner so that the outer diameter is the minimum near the upper part.
この構造によるとバックスキッシュ流Ｓの火炎により突
起部１０の上端面１０ａを効率良く加熱することにより
、滞留燃料の蒸発を促進し、カーボンの堆積を防ぎ、か
つその蒸発噴ＷＱをバックスキッシュ流にうまく載せて
燃焼させることができるるので、燃焼が促進される。According to this structure, by efficiently heating the upper end surface 10a of the protrusion 10 by the flame of the back squish flow S, the evaporation of the accumulated fuel is promoted, carbon deposition is prevented, and the evaporation jet WQ is converted into the back squish flow. Since it can be placed well and combusted, combustion is promoted.
（２）第１０図は第９図と同様に中央突起部１゜の周壁
に環状のくびれ部１５を形成した構造であるが、くびれ
部１５は下端部付近が最小外径になるようにくびれでい
る。(2) Figure 10 shows a structure in which an annular constriction 15 is formed on the peripheral wall of the central protrusion 1° as in Figure 9, but the constriction 15 is constricted so that the minimum outer diameter is near the lower end. I'm here.
（３）第１１図は突起部１０の上端面１０ａに円周溝１
２及び放射状溝１３を形成した例である。(3) FIG. 11 shows a circumferential groove 1 on the upper end surface 10a of the protrusion 10.
2 and radial grooves 13 are formed.
（４）第１２図は突起部１ｏの上端面１０ａに多数のく
ぼみ１７を形成した例である。(4) FIG. 12 shows an example in which a large number of depressions 17 are formed on the upper end surface 10a of the projection 1o.
（５）第１３図は突起Ｉ（１０の上端面１０ａに多数の
いぼ状の突起１８を形成した例である。(5) FIG. 13 shows an example in which a large number of wart-like protrusions 18 are formed on the upper end surface 10a of the protrusion I (10).
（発明の効果）
以上説明したように本発明によると：
（１）噴射の初期においては燃料噴射弁３から噴射され
る噴霧Ｐの一部が中央突起部１０にひっかかるので、初
期燃焼が抑制され、それによりＮ。(Effects of the Invention) As explained above, according to the present invention: (1) At the initial stage of injection, a part of the spray P injected from the fuel injection valve 3 is caught on the central protrusion 10, so that the initial combustion is suppressed. , thereby N.
Ｘの排出量を減少させることができる。The amount of X discharged can be reduced.
（２）ピストン１の下降に従って噴霧Ｐが中央突起部１
０から外れていき、かつ燃料噴射弁３から燃焼室内周面
７までの距離が長くなり、燃焼中期以降は高圧噴霧が略
すべでテーパー内周面７に当るようになり、それにより
勢いのよいバックスキッシュの渦流が形成される。従っ
て混合気形成がよくなって、黒煙の発生が抑制される。(2) As the piston 1 descends, the spray P is transferred to the central protrusion 1.
0, and the distance from the fuel injector 3 to the combustion chamber circumferential surface 7 becomes longer, and from the middle of combustion onward, the high-pressure spray almost all hits the tapered inner circumferential surface 7, which increases the momentum. A backsquish vortex is formed. Therefore, the mixture formation is improved and the generation of black smoke is suppressed.
第１図は本発明を適用したディーゼル機関の燃焼室であ
って、燃焼開始時の状態を示す縦断面図、第２図〜第５
図は上記第１図の燃料開始時以降、燃焼後期までの噴射
状態の変化を順次示す縦断面図、第６図は第１図の中央
突起部の斜視図、第７図は熱発生率の変化を示すグラフ
、第８図はＮＯｘの変化並びに排気職の変化を示すグラ
フ、第９図及び第１０図はそれぞれ中央突起部の変形例
を示す縦断面図、第１１図〜第１３図は中央突起部の上
端面の変形例を示す斜視図、第１４図〜第１６図は従来
例の縦断面略図である。１・・−ピストン、２・・・シ
リンダヘッド、３・・・燃料噴射弁、４・・・シリンダ
、５・・・燃焼室、７・・・テーパー内周面、１０・・
・中央突起部、１０ａ・・・上端面
特許出願人 ヤンマ−ディーゼル株式会社七−
べ東−Ｉ
象４１州脩
開 園
ｆｏ Ｏｏｏｌ １００ ｏｏ １−き
喝
″″″ ）７FIG. 1 is a longitudinal sectional view of the combustion chamber of a diesel engine to which the present invention is applied, showing the state at the start of combustion, and FIGS.
The figures are longitudinal cross-sectional views showing sequential changes in injection conditions from the start of fuel to the late stage of combustion in Fig. 1 above, Fig. 6 is a perspective view of the central protrusion in Fig. 1, and Fig. 7 shows changes in the heat release rate. Graphs showing changes, FIG. 8 is a graph showing changes in NOx and exhaust efficiency, FIGS. 9 and 10 are vertical sectional views showing modified examples of the central protrusion, and FIGS. A perspective view showing a modified example of the upper end surface of the central protrusion, and FIGS. 14 to 16 are schematic longitudinal cross-sectional views of the conventional example. DESCRIPTION OF SYMBOLS 1... Piston, 2... Cylinder head, 3... Fuel injection valve, 4... Cylinder, 5... Combustion chamber, 7... Tapered inner peripheral surface, 10...
・Central protrusion, 10a...upper end surface Patent applicant: Yanmar Diesel Co., Ltd.
Claims (1)
ン上壁に上方へ向いて開口する燃焼室を形成した直接噴
射式ディーゼル機関において、燃焼室の内周面を上端部
が狭くなるような環状テーパ面に形成し、燃焼室の中央
部に上方へ突出する中央突起部を形成して、該突起部の
上端面を概ね緩やかな円錐状に形成し、突起部の上方に
位置する燃料噴射弁の燃料噴射角度と突起部上端面との
関係を、噴射初期においては噴霧域の一部が突起部上端
面に当接して初期燃焼を抑制し、燃焼中期以降において
はピストンの下降により噴霧域全域が突起部から離れて
テーパ内周面に向かって噴射されるように設定したこと
を特徴とする直接噴射式ディーゼル機関の燃焼室。In a direct injection diesel engine, in which a fuel injection valve faces directly into the cylinder from above, and a combustion chamber that opens upward is formed on the upper wall of the piston, the inner peripheral surface of the combustion chamber is shaped like an annular shape that narrows at the upper end. A fuel injection valve having a tapered surface, a central protrusion projecting upward in the center of a combustion chamber, an upper end surface of the protrusion having a generally gentle conical shape, and located above the protrusion. The relationship between the fuel injection angle and the upper end surface of the protrusion is as follows: At the beginning of injection, a part of the spray area comes into contact with the upper end surface of the protrusion, suppressing initial combustion, and after the middle stage of combustion, the entire spray area is reduced due to the downward movement of the piston. A combustion chamber of a direct injection diesel engine, characterized in that the combustion chamber is set so that the fuel is injected away from the protrusion and toward a tapered inner circumferential surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1289744A JPH03149314A (en) | 1989-11-06 | 1989-11-06 | Combustion chamber of direct injection type diesel engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1289744A JPH03149314A (en) | 1989-11-06 | 1989-11-06 | Combustion chamber of direct injection type diesel engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03149314A true JPH03149314A (en) | 1991-06-25 |
Family
ID=17747199
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1289744A Pending JPH03149314A (en) | 1989-11-06 | 1989-11-06 | Combustion chamber of direct injection type diesel engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03149314A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04228821A (en) * | 1990-12-27 | 1992-08-18 | Shinnenshiyou Syst Kenkyusho:Kk | Combustion chamber of direct injection diesel engine |
| FR2895019A1 (en) * | 2005-12-16 | 2007-06-22 | Renault Sas | Combustion chamber for e.g. common rail type direct injection diesel engine, has cylinder with piston having bowl with three recesses whose depth and orientation are defined, based on distance between nozzle and elevated part of bowl`s boss |
| EP3803089A4 (en) * | 2018-05-30 | 2021-11-03 | Scania CV AB | Diesel engine, motor vehicle and method for reducing heat transfer to a piston of a cylinder of a diesel engine |
-
1989
- 1989-11-06 JP JP1289744A patent/JPH03149314A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04228821A (en) * | 1990-12-27 | 1992-08-18 | Shinnenshiyou Syst Kenkyusho:Kk | Combustion chamber of direct injection diesel engine |
| FR2895019A1 (en) * | 2005-12-16 | 2007-06-22 | Renault Sas | Combustion chamber for e.g. common rail type direct injection diesel engine, has cylinder with piston having bowl with three recesses whose depth and orientation are defined, based on distance between nozzle and elevated part of bowl`s boss |
| EP3803089A4 (en) * | 2018-05-30 | 2021-11-03 | Scania CV AB | Diesel engine, motor vehicle and method for reducing heat transfer to a piston of a cylinder of a diesel engine |
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