JPH03222815A - Piston for internal combustion engine - Google Patents
Piston for internal combustion engineInfo
- Publication number
- JPH03222815A JPH03222815A JP2013569A JP1356990A JPH03222815A JP H03222815 A JPH03222815 A JP H03222815A JP 2013569 A JP2013569 A JP 2013569A JP 1356990 A JP1356990 A JP 1356990A JP H03222815 A JPH03222815 A JP H03222815A
- Authority
- JP
- Japan
- Prior art keywords
- recess
- piston
- recessed part
- swirl
- fuel
- 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 29
- 239000000446 fuel Substances 0.000 claims abstract description 32
- 238000002347 injection Methods 0.000 claims abstract description 31
- 239000007924 injection Substances 0.000 claims abstract description 31
- 239000000463 material Substances 0.000 claims 1
- 239000000919 ceramic Substances 0.000 abstract description 7
- 238000001816 cooling Methods 0.000 abstract description 7
- 238000000034 method Methods 0.000 abstract 1
- 239000000567 combustion gas Substances 0.000 description 7
- 230000007423 decrease Effects 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000009413 insulation Methods 0.000 description 2
- 239000000470 constituent Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000002269 spontaneous effect Effects 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
- F02B23/0645—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
- 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
- F02B23/0696—W-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 wall
-
- 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
- F02B23/0603—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 at least part of the interior volume or the wall of the combustion space being made of material different from the surrounding piston part, e.g. combustion space formed within a ceramic part fixed to a metal piston head
- F02B2023/0612—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 at least part of the interior volume or the wall of the combustion space being made of material different from the surrounding piston part, e.g. combustion space formed within a ceramic part fixed to a metal piston head the material having a high temperature and pressure resistance, e.g. ceramic
-
- 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
- F02B23/0624—Swirl 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)
Abstract
Description
【発明の詳細な説明】
［発明の目的］
（産業上の利用分野）
二の年明は、ピストン頂部に形成された燃焼室に、燃料
か直接噴射される内燃機関のピストンに関する。Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The second decade of the present invention relates to a piston for an internal combustion engine in which fuel is directly injected into a combustion chamber formed at the top of the piston.
（従来の技術〉
ピストン頂部に形成された燃焼室に向けて燃料が直接噴
射される内燃機関としては、直噴式ディーゼル機関かあ
る。直噴式ディーゼル機関は燃焼室内の圧縮空気中に燃
料を直接噴射して自然着火させるものであることから、
圧縮される空気は高温高圧とする必要がある。(Prior art) There is a direct injection diesel engine as an internal combustion engine in which fuel is directly injected into the combustion chamber formed at the top of the piston.Direct injection diesel engines inject fuel directly into the compressed air inside the combustion chamber. Because it causes spontaneous ignition,
The air to be compressed needs to be at high temperature and pressure.
このため従来では、例えば特開昭５９−１５８３１７号
公報から引用した第６図及び第７図のように、断熱効果
の高いセラミックからなる成形体１をピストン３の頂部
５に鋳込み、このセラミック成形体１に凹部を形成して
燃焼室７とし、これにより高温高圧の圧縮空気を確保す
るようにしたものがある。この燃焼室７に燃料噴射ノズ
ルの噴射孔が望み燃焼室７に直接燃料を噴射するように
なっている。この場合、燃料噴射ノズルの噴射孔は周方
向等間隔に４つ設けられており、各噴射孔の指向方向に
は、燃焼室７の底部中心から頂部５に至る帯状の突起９
が形成されている。For this reason, conventionally, as shown in FIGS. 6 and 7 cited from JP-A-59-158317, for example, a molded body 1 made of ceramic with high heat insulation effect is cast into the top part 5 of the piston 3, and this ceramic molded body 1 is cast into the top part 5 of the piston 3. There is one in which a recess is formed in the body 1 to serve as a combustion chamber 7, thereby securing high-temperature, high-pressure compressed air. A fuel injection nozzle has an injection hole in the combustion chamber 7 so that fuel can be directly injected into the combustion chamber 7. In this case, four injection holes of the fuel injection nozzle are provided at equal intervals in the circumferential direction, and a band-shaped projection 9 extending from the center of the bottom of the combustion chamber 7 to the top 5 extends in the direction of direction of each injection hole.
is formed.
このような燃焼室７を備えたピストン３ては。The piston 3 is equipped with such a combustion chamber 7.
燃料と空気との混合を促進するために、吸入行程時にシ
リンダ内に流入する吸気が、燃焼室７にて吸気ポートの
形状によって第７図に示すような旋回空気流（スワール
）Ｓとなる。一方、燃料噴射ノズルの４つの噴射孔から
噴射される燃料は突起９に沿って矢印Ｆのような流れと
なる。このなめ噴射された燃料はスワールＳと交錯して
空気と燃料との混合がより一層促進されることになる。In order to promote the mixing of fuel and air, the intake air flowing into the cylinder during the intake stroke forms a swirl S as shown in FIG. 7 in the combustion chamber 7 due to the shape of the intake port. On the other hand, the fuel injected from the four injection holes of the fuel injection nozzle flows along the protrusion 9 as shown by arrow F. This lick-injected fuel intersects with the swirl S, further promoting the mixing of air and fuel.
（発明が解決しようとする課題）
ところで、セラミックのような断熱材を燃焼室の構成部
材とした場合には、圧縮空気を高温高圧に維持できるも
のの、燃焼室壁面が高温となるため、スワールによって
壁面を沿って回転する空気の動粘性係数が増大し、スワ
ール速度が減少する傾向にある。断熱材を用いない従来
型のピストンと同等のスワール速度を確保するためには
、実用化困難な数倍のスワール比（吸気回転速度と機関
回転速度との比）か必要であり、仮にそのような高スワ
ールを実現できたとしても、吸気抵抗が増大し、体積効
率が極めて悪化することとなる。(Problem to be Solved by the Invention) By the way, if a heat insulating material such as ceramic is used as a constituent member of the combustion chamber, compressed air can be maintained at high temperature and pressure, but the wall surface of the combustion chamber becomes high temperature, so swirl The kinematic viscosity coefficient of air rotating along the wall surface increases, and the swirl speed tends to decrease. In order to secure a swirl speed equivalent to that of a conventional piston that does not use insulation, it is necessary to have a swirl ratio (ratio of intake rotation speed to engine rotation speed) several times higher, which is difficult to put into practical use. Even if a high swirl can be achieved, the intake resistance will increase and the volumetric efficiency will deteriorate significantly.
スワール速度か減少すると、燃焼ガスと燃焼室壁面との
間の境界層が充分に確保できなくなり。When the swirl speed decreases, a sufficient boundary layer between the combustion gas and the combustion chamber wall cannot be secured.
火炎が壁面に直接接触し、冷却損失が増大して燃費の悪
化を招くこととなる。特に前述した公報記載のものは、
突起９の部分で熱伝達率が急激に増大するとともに、空
気及び燃焼ガスが突起９に沿って上昇するため、回転し
ている空気の動粘性係数の増大及びこれに付随するスワ
ールの回転速度の低下がより一層顕著となり、冷却損失
は益り大きなものとなる。The flame comes into direct contact with the wall surface, increasing cooling loss and causing deterioration of fuel efficiency. In particular, those described in the above-mentioned publications,
The heat transfer coefficient rapidly increases at the protrusion 9, and air and combustion gas rise along the protrusion 9, resulting in an increase in the kinematic viscosity coefficient of the rotating air and an accompanying decrease in the rotational speed of the swirl. The decrease becomes even more noticeable, and the cooling loss becomes even larger.
そこでこの発明は、燃焼室内に生成されるスワール速度
を充分に高め、燃焼ガスと壁面との境界層を充分確保し
て冷却損失の増大を防止することを目的としている。Therefore, an object of the present invention is to sufficiently increase the swirl velocity generated within the combustion chamber to ensure a sufficient boundary layer between the combustion gas and the wall surface, thereby preventing an increase in cooling loss.
［発明の構成コ
（課題を解決するための手段）
前述した課題を解決するためにこの発明は、少くとも頂
部が低熱伝導性かつ耐熱性のある部材からなり、この頂
部に、複数の噴射孔を＠えた燃料噴射ノスルにより燃料
か噴射される凹部からなる燃焼室か形成された内燃機関
のピストンにおいて、頂部中央に比較的浅い第１の凹部
を設けるとともに、第１の凹部より深い断面円弧状で円
形の第２の凹部を第１の凹部の周縁に沿って前記燃料噴
射ノズルの噴射孔と同数設け、前記噴射孔の第２の凹部
に対する指向方向は、第２の凹部の周縁のほぼ接線方向
で、かつ吸入行程にて生成される第２の凹部内のスワー
ルと同方向となるよう鰻重する構成としである。[Configuration of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention comprises at least a top part made of a member having low thermal conductivity and heat resistance, and a plurality of injection holes in the top part. In the piston of an internal combustion engine, which has a combustion chamber formed of a recess into which fuel is injected by a fuel injection nostle with a The same number of circular second recesses as the injection holes of the fuel injection nozzle are provided along the periphery of the first recess, and the orientation direction of the injection holes with respect to the second recess is substantially tangent to the periphery of the second recess. The structure is such that the eel is piled up in the same direction as the swirl in the second recess generated in the suction stroke.
（作用）
吸入行程にてシリンダ内に供給される空気は旋回しなが
ら第２の凹部に流入し、それぞれの第２の凹部では同方
向のスワールとなる。第２の凹部は複数段けであること
から比較的小径であり、このためスワールの流速は高ま
る。燃料噴射ノズルの４つの噴射孔から噴射される燃料
は、それぞれの第２の凹部の周縁のほぼ接線方向で、か
つ吸入行程にて第２の凹部内で生成されるスワールと同
方向に流入してスワールの流速登さらに高める。(Operation) Air supplied into the cylinder during the suction stroke flows into the second recess while swirling, and swirls in the same direction in each second recess. The second recess has a relatively small diameter because it has multiple stages, and therefore the flow velocity of the swirl increases. The fuel injected from the four injection holes of the fuel injection nozzle flows in substantially tangential direction of the periphery of each second recess and in the same direction as the swirl generated within the second recess during the suction stroke. This further increases the velocity of the swirl.
第２の凹部内に生成されるスワールは、ピストン外周側
が吸入行程時でのシリンダ内の旋回流と同方向であるの
でこの部位での速度成分が増大し、一方向周側は、第１
の凹部か形成されていることから、ここでの壁面高さが
外周側より低くなっており、したがってピストン内周側
での第２の凹部内のスワールの方向が吸入行程時での前
記旋回流の方向と逆になっていてもスワールが減速され
るようなことはない。The swirl generated in the second recess has the same direction as the swirling flow inside the cylinder during the suction stroke on the outer peripheral side of the piston, so the velocity component at this part increases, and the swirl on the peripheral side in one direction increases
Since a concave portion is formed, the wall surface height here is lower than that on the outer circumferential side, and therefore the direction of the swirl in the second concave portion on the inner circumferential side of the piston is the same as that of the swirling flow during the suction stroke. The swirl will not be slowed down even if the direction is reversed.
（実施例）
以下、この発明の実施例を第１図ないし第５図に基づき
説明する。(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5.
第１図及び第２図はこの発明の第１の実施例を示してい
る。このピストン１１は、直噴式ディーゼル機関に使用
されるもので、その頂部１３には低熱伝導性かつ耐熱性
のあるセラミックからなる成形体１５が鋳込まれている
。このセラミック成形体１５の中央には、比較的浅く断
面円弧状で円形の第１の凹部１７が形成されている。第
１の凹部１７の周縁トには、断面円弧状て円形の燃焼室
となる４つの第２の凹部１つか９０度間隔で設けられて
いる。第２の凹部１つは、第１の凹部１７より深く形成
されて内面か滑らかで、かつ円形間１１部の直径かピス
トン１１の直径の１ 、’ ５程度としである。1 and 2 show a first embodiment of the invention. This piston 11 is used in a direct-injection diesel engine, and has a molded body 15 made of ceramic having low thermal conductivity and heat resistance cast into its top 13. In the center of this ceramic molded body 15, a first recess 17 is formed which is relatively shallow and has a circular arcuate cross section. On the periphery of the first recess 17, four second recesses are provided at intervals of 90 degrees, each forming a combustion chamber having an arcuate cross section. One of the second recesses is formed deeper than the first recess 17, has a smooth inner surface, and has a diameter of about 1.5 times the diameter of the circular gap 11 or the diameter of the piston 11.
一方、第２の凹部１９に燃料を噴射する燃ト１噴射ノス
ル２１は、４つの第２の凹部１つに対応して噴射孔か４
つあり、これら各噴射孔の第２の凹部１９に対する指向
方向は、第１図の破線Ｆで示すように、第２の凹部１つ
の円形開口部周縁のほぼ接線方向で、かつ吸入行程にて
生成される旋回流Ｓｍに起因して発生する第２の凹部１
９内のスワールＳと同方向となるよう設定しである。On the other hand, the fuel 1 injection nostle 21 that injects fuel into the second recess 19 has four injection holes corresponding to one of the four second recesses.
The orientation direction of each of these injection holes with respect to the second recess 19 is approximately tangential to the periphery of the circular opening of one of the second recesses, and in the suction stroke, as shown by the broken line F in FIG. Second recess 1 generated due to the generated swirling flow Sm
It is set to be in the same direction as the swirl S in 9.
このような燃焼室構造を備えたピストンでは、機関の吸
入行程にてシリンダ内に供給される空気は、矢印Ｓｍ方
向に旋回しながら第２の凹部１つに流入しスワールとＳ
となる。第２の凹部１つは複数設けてその直径をピスト
ン１１の直径の１２，１５程度とし、かつ内面を滑らか
にすることで、直径を小さくすることによる抵抗が最小
限に抑えられて旋回速度か高速に確保される。一方、燃
料噴射ノスル２１の４つの噴射孔から噴射される燃ト１
は、それぞれの第２の凹部１つの周縁のほぼ接線方向で
、かつ上記スワールとＳと同方向に流入してスワールの
流速をさらに高める。In a piston with such a combustion chamber structure, air supplied into the cylinder during the intake stroke of the engine flows into one second recess while swirling in the direction of arrow Sm, causing a swirl and S
becomes. By providing a plurality of second recesses and making the diameter approximately 12.15 times the diameter of the piston 11, and by making the inner surface smooth, the resistance caused by reducing the diameter is minimized and the rotation speed is increased. Secured quickly. On the other hand, the fuel 1 injected from the four injection holes of the fuel injection nostle 21
S flows in substantially tangential direction of the periphery of one of the respective second recesses and in the same direction as the swirl and S to further increase the flow velocity of the swirl.
第２の凹部１つ内のスワールの流速が高まることから、
燃焼ガスと第２の凹部１つの壁面との間の境界層を充分
確保でき、この結果冷却損失が低下し、またスワール速
度か高速となることから、燃焼ガスの層を薄くでき、噴
射された燃料が空気に対し拡散し混合しやすくなって拡
散燃焼が良好となり燃費が向上する。Since the flow velocity of the swirl within one second recess increases,
A sufficient boundary layer can be secured between the combustion gas and the wall surface of one of the second recesses, and as a result, the cooling loss is reduced and the swirl speed is high, so the layer of combustion gas can be thinned and the injected The fuel diffuses into the air and mixes more easily, resulting in better diffusion combustion and improved fuel efficiency.
第２の凹部１９内のスワールＳは、シリンダ内全体の旋
回流Ｓｍに対し、ピストン１１の外周側では同方向とな
っているので、この部位て゛のスワールＳの旋回速度成
分が増大する。一方向周側では、スワールＳの方向がン
リンダ内旋回流Ｓｍの方向と逆になっているが、第１の
凹部１７が形成されていることからここでの壁面高さが
低くなってＪ産凹流８ｍの影響を受けに＜＜、シたかっ
て内周側てのスワールＳか減速される心配はない。また
、ピストン１１の内周側の第２の凹部１つの壁面高さか
低くなっていることがら、各第２の凹部１９相互間での
混合ら促進される。Since the swirl S in the second recess 19 is in the same direction on the outer circumferential side of the piston 11 as the swirling flow Sm throughout the cylinder, the swirling speed component of the swirl S in this region increases. On the circumferential side in one direction, the direction of the swirl S is opposite to the direction of the swirling flow Sm in the cylinder, but since the first recess 17 is formed, the wall surface height here is lowered and the J production There is no worry that the swirl S on the inner circumference side will be decelerated due to the influence of the 8m concave flow. Furthermore, since the wall surface height of one of the second recesses on the inner peripheral side of the piston 11 is lower, mixing between the second recesses 19 is promoted.
第３図はこの発明の第２の実施例を示している。FIG. 3 shows a second embodiment of the invention.
二の実施例は、第２の凹部１９の燃料が噴射流入する部
位２３を除き全周にわたり舌片状の突起２５を説けたも
のである。その他の構成は第１の実施例と同様て′ある
。In the second embodiment, a tongue-shaped protrusion 25 is provided over the entire circumference of the second recess 19 except for a portion 23 into which the fuel is injected. The other configurations are the same as in the first embodiment.
突起２５を設けることで、突起２５が設けられていない
部位二３から流入した第２の凹部１９内の空気かその外
部へ逃げにくくなり、第２の凹部１９内に生成されるス
ワールの速度分より強く保持することかできる。また、
第１の凹部１７があることから突起２５はピストン１１
の中心側に向かって下方に傾斜することになり、その結
果スワールは突起２５に沿って下向きの流れとなり、ピ
ストン１１の中心・側に達するスワールはこの部位の小
さい曲率により、さらに増速される。このため、冷却損
失の低減効果及び拡散燃焼時の混合がより一層向上する
。Providing the protrusion 25 makes it difficult for the air in the second recess 19 that flows in from the part 23 where the protrusion 25 is not provided to escape to the outside, and the speed of the swirl generated in the second recess 19 is reduced. Can it be held stronger? Also,
Since the first recess 17 is present, the protrusion 25 is connected to the piston 11.
As a result, the swirl becomes a downward flow along the protrusion 25, and the swirl that reaches the center/side of the piston 11 is further accelerated due to the small curvature of this part. . Therefore, the effect of reducing cooling loss and the mixing during diffusion combustion are further improved.
第４図及び第５図はこの発明の第３の実施例を示してい
る。この実施例は、隣接する第２の凹部１９同志を、第
４図のように外周側付近でドリル加工で形成した連通孔
２７にて連通したもので、しかもこの連通孔２７は第５
図のように、第４図にて示すシリンダ内全体の旋回流Ｓ
ｍの旋回方向始端側の第２の凹部１９がらがら終端側の
第２の凹部１９に向けて下方に傾斜するように形成しで
ある。その他の構成は第１の実施例と同様である。4 and 5 show a third embodiment of the invention. In this embodiment, adjacent second recesses 19 are communicated with each other through a communication hole 27 formed by drilling near the outer circumferential side as shown in FIG.
As shown in the figure, the swirling flow S in the entire cylinder shown in Figure 4 is
The second recess 19 on the starting end side in the turning direction of m is formed so as to be inclined downward toward the second recess 19 on the terminal end side. The other configurations are similar to the first embodiment.
このような構造とすることで、第２の凹部１つ内の旋回
流は、第５図にてその上部側に開口している連通孔２７
に流入し、これに隣接する第２の凹部１９の下部側に流
出する。第２の凹部１９内での燃焼はその上部側で発生
することがら、下部側には空気が滞留することになり、
このなめ上記連通孔２７から流出する燃焼ガスにより、
下部側の空気か乱され、拡散燃焼時の混合がより一層促
進される。なお、この実施例では連通孔２７の耐熱性か
問題となるか、ピストン１１の頂部１３がセラミックで
構成しであるので、その心配はない。With such a structure, the swirling flow within one second recess can flow through the communication hole 27 that opens at the upper side of the second recess in FIG.
and flows out to the lower side of the second recess 19 adjacent thereto. Since combustion within the second recess 19 occurs on the upper side, air will remain on the lower side.
Due to the combustion gas flowing out from the communication hole 27,
The air on the lower side is disturbed and mixing during diffusive combustion is further promoted. In this embodiment, the heat resistance of the communication hole 27 may be a problem, but since the top portion 13 of the piston 11 is made of ceramic, there is no such concern.
また、この実施例の構造すなわち連通孔２７と、前記第
２の実施例による突起２５とを組み合わせる構成として
もよい。Further, the structure of this embodiment, that is, the communication hole 27, and the projection 25 of the second embodiment may be combined.
なお、前記各実施例では第２の凹部１つを４つ設ける構
成としたが、これに限るものではない。In each of the above embodiments, four second recesses are provided, but the present invention is not limited to this.
［発明の効果］
以上説明し、てきたようにこの発明の構成によれば、第
２の凹部内に生成されるスワールは、複数設けることで
第２の凹部が小径となることから旋回速度が上昇し、さ
らに噴射される燃料により増速され、この結果燃焼ガス
と第２の凹部内壁面との境界層が充分確保されて冷却損
失の増大と防止することができ、拡散燃焼が良好となる
とともに燃費が向上する。上記スワールの方向は、ピス
トン内周側でシリンダ内全体の旋回流の方向と逆になる
が、第１の凹部が形成されていることからここでの第２
の凹部の壁面高さが低くなってシリンダ内旋回流の影響
を受けにくく、したかって第２の凹部内のスワールが減
速される心配はない。[Effects of the Invention] As explained above and described above, according to the configuration of the present invention, by providing a plurality of swirls generated in the second recess, the second recess has a small diameter, so that the swirl speed can be increased. The fuel rises and is further accelerated by the injected fuel, and as a result, a sufficient boundary layer between the combustion gas and the inner wall surface of the second recess is secured, which prevents an increase in cooling loss and improves diffusion combustion. At the same time, fuel efficiency improves. The direction of the swirl is opposite to the direction of the swirling flow in the entire cylinder on the inner peripheral side of the piston, but since the first recess is formed, the second
The height of the wall surface of the second recess is lowered so that it is less susceptible to the influence of the swirling flow within the cylinder, so there is no concern that the swirl within the second recess will be decelerated.
第１図はこの発明の第１の実施例を示すピストンの上面
図、第２図は第１図のＩｆ−ｆｆ断面図、第３図はこの
発明の第２の実施例を示すピストンの要部断面図、第４
図はこの発明の第３の実施例を示すピストンの上面図、
第５図は第４図の拡大されたｖ−■断面図で、第６図は
従来例のピストンの斜視図、第７図は同上面図ある。FIG. 1 is a top view of a piston showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along the If-ff line in FIG. Partial sectional view, 4th
The figure is a top view of a piston showing a third embodiment of the invention.
FIG. 5 is an enlarged sectional view taken along the line v--2 in FIG. 4, FIG. 6 is a perspective view of a conventional piston, and FIG. 7 is a top view of the piston.
Claims (1)
り、この頂部に、複数の噴射孔を備えた燃料噴射ノズル
により燃料が噴射される凹部からなる燃焼室が形成され
た内燃機関のピストンにおいて、頂部中央に比較的浅い
第１の凹部を設けるとともに、第１の凹部より深い断面
円弧状で円形の第２の凹部を第１の凹部の周縁に沿って
前記燃料噴射ノズルの噴射孔と同数設け、前記噴射孔の
第２の凹部に対する指向方向は、第２の凹部の周縁のほ
ぼ接線方向で、かつ吸入行程にて生成される第２の凹部
内のスワールと同方向となるよう設定したことを特徴と
する内燃機関のピストン。In a piston of an internal combustion engine, at least the top part is made of a material with low thermal conductivity and heat resistance, and the top part is formed with a combustion chamber consisting of a recessed part into which fuel is injected by a fuel injection nozzle equipped with a plurality of injection holes. , a relatively shallow first recess is provided in the center of the top, and second recesses having a circular arcuate cross section and deeper than the first recess are arranged along the periphery of the first recess in a number equal to the number of injection holes of the fuel injection nozzle. and the direction of orientation of the injection hole with respect to the second recess is set to be substantially tangential to the periphery of the second recess and in the same direction as the swirl within the second recess generated in the suction stroke. A piston for an internal combustion engine characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013569A JPH03222815A (en) | 1990-01-25 | 1990-01-25 | Piston for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013569A JPH03222815A (en) | 1990-01-25 | 1990-01-25 | Piston for internal combustion engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03222815A true JPH03222815A (en) | 1991-10-01 |
Family
ID=11836798
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2013569A Pending JPH03222815A (en) | 1990-01-25 | 1990-01-25 | Piston for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03222815A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5285755A (en) * | 1993-03-08 | 1994-02-15 | Chrysler Corporation | Open chamber diesel engine having a piston with recesses therein |
| WO2018096591A1 (en) * | 2016-11-22 | 2018-05-31 | マツダ株式会社 | Diesel engine |
-
1990
- 1990-01-25 JP JP2013569A patent/JPH03222815A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5285755A (en) * | 1993-03-08 | 1994-02-15 | Chrysler Corporation | Open chamber diesel engine having a piston with recesses therein |
| WO2018096591A1 (en) * | 2016-11-22 | 2018-05-31 | マツダ株式会社 | Diesel engine |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9957916B2 (en) | Internal combustion engine | |
| JP2000220520A (en) | Piston for internal combustion engine | |
| JP2001221050A (en) | Piston of direct injection diesel engine | |
| JPS6316124A (en) | Pent roof type piston | |
| JPS59158317A (en) | Piston | |
| JPH03222815A (en) | Piston for internal combustion engine | |
| JPH11190217A (en) | Direct injection type diesel engine | |
| JPS62255520A (en) | Pent roof type piston | |
| EP0828066A1 (en) | Combustion chamber of diesel engine | |
| JPH0893550A (en) | Combustion chamber of direct injection-type diesel engine | |
| JP3035990B2 (en) | Sub-chamber diesel engine | |
| JPH0893479A (en) | Combustion chamber of direct injection diesel engine | |
| JP2019007446A (en) | Combustion chamber structure for direct-injection type internal combustion engine | |
| JP3070186B2 (en) | Insulated engine with sub-chamber | |
| JP2581866Y2 (en) | Combustion chamber of direct injection diesel engine | |
| JP2002048001A (en) | Piston cooling structure for internal combustion engine | |
| JP2853209B2 (en) | Subchamber insulation engine | |
| JPH0133810Y2 (en) | ||
| KR100373248B1 (en) | Combustion chamber structure of direct injection type diesel engine | |
| KR19980043589U (en) | Piston for promoting vortex formation | |
| JPS5960026A (en) | Combustion chamber of diesel engine | |
| JPH07139355A (en) | Combustion chamber for direct injecting type diesel engine | |
| JPH04124443A (en) | Fuel collision diffusing device | |
| JPS5982520A (en) | Eddy-current chamber for diesel engine | |
| JPS62111115A (en) | Side injection combustion system for adiabatic type plural fuel valves |