JP2017145817A

JP2017145817A - Internal combustion engine including ignition structure

Info

Publication number: JP2017145817A
Application number: JP2016069505A
Authority: JP
Inventors: 北村　修一; Shuichi Kitamura; 修一北村
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-02-20
Filing date: 2016-02-20
Publication date: 2017-08-24

Abstract

PROBLEM TO BE SOLVED: To achieve rapid combustion by disposing an ignition part of an ignition structure such an ignition plug in a center of a combustion chamber or near the center as much as possible to improve heat efficiency and reduce CO.SOLUTION: The internal combustion engine includes the ignition structure 2 having a projection member 3 projecting by 10 mm or more from a wall surface of a combustion chamber and having an ignition part at the tip part thereof and is configured so as to cool the projection member 3 of the ignition structure by jetting a cooling jet flow to it.SELECTED DRAWING: Figure 1

Description

本発明は点火プラグの様な点火構造体を備えた内燃機関に係わり、点火構造体の１０ｍｍ以上と長く突出した電極などの突出部材に水を微粒化した噴流又は低温気体の噴流を噴き付けて冷却する様にしたものに関する。前記低温気体の噴流は空気、気体燃料などエンジンの燃焼に関与する気体（常温で気体）を圧縮した後に冷却し、これを膨張機で断熱膨張させる事によって得られるものである。The present invention relates to an internal combustion engine equipped with an ignition structure such as an ignition plug, and sprays a jet of water atomized or a jet of low-temperature gas onto a protruding member such as an electrode that protrudes longer than 10 mm of the ignition structure. It relates to things that are designed to cool. The jet of low-temperature gas is obtained by compressing a gas (air-temperature gas) involved in engine combustion, such as air or gaseous fuel, and then cooling it and adiabatic expansion with an expander.

内燃機関はＣＯ_２削減、熱効率向上が強く求められているが、これに最も効果的なものは希薄燃焼、急速燃焼の技術である。一般に燃焼室内混合気に点火する点火構造体、例えば点火プラグは図６に示す様に突出部材、即ち電極の突出量ｌは６〜８ｍｍ以下であり、従ってその点火部（火花ギャップ）は燃焼室壁面に近く、燃焼室中心に配置する事はできない。もしこの点火部を燃焼室中心に配置する事ができれば（図１参照）火炎伝播距離が半減するから、燃焼完了までの期間が半減して急速燃焼が可能となり、しかも火炎が全ての混合気が燃焼完了するまで冷たい燃焼室壁面に接触しないから冷却損失が減少し、特に希薄混合気は火炎伝播速度が遅くなりがちであるからこの希薄燃焼に有利であり、かくして熱効率の大幅向上、ＣＯ_２の大幅削減が期待できる。しかしながらこの様な構成は長い突出部材、例えば長い電極は受熱量が増して伝熱冷却が困難となるから、異状高温となり、激しい過早点火を引き起す。Internal combustion engines are strongly required to reduce CO ₂ and improve thermal efficiency, but the most effective ones are lean combustion and rapid combustion technologies. In general, an ignition structure for igniting an air-fuel mixture in a combustion chamber, for example, an ignition plug, has a protruding member, that is, an electrode protruding amount l of 6 to 8 mm or less, as shown in FIG. It cannot be placed near the wall and in the center of the combustion chamber. If this ignition part can be placed in the center of the combustion chamber (see Fig. 1), the flame propagation distance will be halved, so the period until the completion of combustion will be halved and rapid combustion will be possible. cooling loss do not contact the cold combustion chamber walls to complete the combustion is reduced, particularly lean mixtures is advantageous in this lean burn because it is likely slower flame propagation velocity, thus greatly improving the thermal efficiency, the CO ₂ Significant reduction can be expected. However, in such a configuration, a long projecting member, for example, a long electrode, increases the amount of heat received and makes it difficult to cool the heat transfer, resulting in an abnormally high temperature and causing severe pre-ignition.

本発明の目的は点火プラグの様な点火構造体の突出部材の先端部にある点火部を燃焼室の中心又はできる限り中心に配置する事によって燃焼期間を短縮化して急速燃焼を達成し、ＣＯ_２の削減、熱効率の向上を図ったものである。更に希薄燃焼は熱効率を改善するから、希薄燃焼・急速燃焼とする事によって熱効率の大幅改善を図ったものである。
かつ、本発明はそれによって長く突出した点火構造体の突出部材に水を微粒化した噴流又は低温気体の噴流を噴き付けて冷却し、過早点火を未然に防ぐ事も目的としている。前記低温気体の噴流は空気、気体状燃料などのエンジン燃焼に関与する気体を圧縮機で圧縮した後に冷却し、これを膨張機で断熱膨張させる事によって得るものである。It is an object of the present invention to achieve rapid combustion by shortening the combustion period by disposing the ignition part at the tip of the projecting member of the ignition structure such as a spark plug at the center of the combustion chamber or as much as possible. _This is intended to reduce ₂ and improve thermal efficiency. Furthermore, since lean combustion improves thermal efficiency, lean combustion and rapid combustion are used to significantly improve thermal efficiency.
Another object of the present invention is to prevent premature ignition by spraying a jet of finely atomized water or a jet of low-temperature gas on the projecting member of the ignition structure that projects long thereby. The jet of low-temperature gas is obtained by compressing a gas involved in engine combustion such as air or gaseous fuel after being compressed by a compressor and adiabatically expanding it by an expander.

Means to solve the problem

本発明は上記目的を達成する為、燃焼室壁面から１０ｍｍ以上突出した突出部材を有し、その先端部に燃焼室内混合気に点火する点火部を有する点火構造体を備える。第１の発明は前記点火構造体の突出部材に水を微粒化した噴流を噴き付けて冷却する様にする構造である。
第２の発明は前記突出部材にエンジンの燃焼に関与する気体を圧縮機により圧縮した後に冷却し、これを膨張機によって膨張させた低温の気体を噴き付けて冷却する構造である。In order to achieve the above object, the present invention includes an ignition structure having a projecting member projecting 10 mm or more from the combustion chamber wall surface, and having an ignition unit for igniting the air-fuel mixture in the combustion chamber at the tip thereof. The first aspect of the invention is a structure in which a jet of water atomized is sprayed onto the projecting member of the ignition structure to cool it.
According to a second aspect of the present invention, a gas involved in engine combustion is compressed on the projecting member after being cooled by a compressor, and then cooled by injecting a low-temperature gas expanded by the expander.

Effect of the invention

本発明においては燃焼室壁面から長く突出した点火構造体の突出部材は（中）・高負荷域では水を微粒化した噴流、又はエンジンの燃焼に関与する気体（空気、気体燃料）を圧縮した後に冷却し、これを膨張機で膨張させて得られる低温の気体が噴き付けられて冷却させるから、過度に高温になる事は回避され、過早点火は起らない。
本発明によれば燃焼室内混合気に点火する点火部は燃焼室の中心に配置する事ができるから、火炎伝播距離は半減・燃焼期間も半減し（実際は後述する如く１／２．５位にはなる）、急速燃焼が可能となる。この為、希薄燃焼が可能となり、希薄燃焼はポンプ損失が少なく、燃焼温度が低い為に冷却損失が少なく比熱比が大で、熱効率を大幅に改善する事ができる。一般に希薄燃焼は燃焼速度が遅くなる為、これらの効果は限定的であるが、急速燃焼との相乗効果により大きな熱効率改善が得られる。かつ、燃焼室内混合気に点火する点火部は燃焼室中心に配置され、燃焼が完了するまで冷たい燃焼室壁面に火炎が接触しないから、冷却損失は更に少ない（この為、始動性も向上する）。更に本発明によれば急速燃焼が可能であるから、最適点火時期を遅らせる事ができ、最高燃焼温度・圧力の減少により冷却損失、摩擦損失の低減も見込まれ、熱効率の改善効果は著るしいものになる。加えて低負荷域、特にアイドルを含む極低負荷域においては希薄混合気では着火性が悪化するが、本発明によれば上記点火部までの突出部材が長くその先端部は高温となっているから（この領域では突出部材の冷却は停止される）、火炎核が冷却作用（消炎作用）を受ける事がなく着火性は大幅に向上し、より一層の希薄燃焼により熱効率の大幅向上が期待できる。In the present invention, the projecting member of the ignition structure projecting long from the wall surface of the combustion chamber is (medium). In the high load region, a jet of water atomized or a gas (air, gaseous fuel) involved in engine combustion is compressed. Since it cools later and the low temperature gas obtained by expanding this with an expander is injected and cooled, it is avoided that it becomes too high temperature, and pre-ignition does not occur.
According to the present invention, the ignition part for igniting the air-fuel mixture in the combustion chamber can be arranged at the center of the combustion chamber, so that the flame propagation distance is halved and the combustion period is halved (actually, it is reduced to 1 / 2.5 as described later). Rapid combustion is possible. For this reason, lean combustion becomes possible, and lean combustion has low pump loss, and since the combustion temperature is low, cooling loss is low, specific heat ratio is large, and thermal efficiency can be greatly improved. In general, lean combustion has a slow combustion speed, so these effects are limited. However, a great improvement in thermal efficiency can be obtained by a synergistic effect with rapid combustion. In addition, since the ignition part for igniting the air-fuel mixture in the combustion chamber is arranged at the center of the combustion chamber and the flame does not contact the cold combustion chamber wall surface until combustion is completed, the cooling loss is further reduced (therefore, the startability is also improved). . Furthermore, since rapid combustion is possible according to the present invention, the optimal ignition timing can be delayed, and the cooling efficiency and friction loss can be reduced by reducing the maximum combustion temperature and pressure, and the effect of improving thermal efficiency is remarkable. Become a thing. In addition, in a low load range, particularly in an extremely low load range including idle, the ignitability deteriorates with a lean air-fuel mixture, but according to the present invention, the protruding member to the ignition portion is long and the tip thereof is hot. (Cooling of the projecting member is stopped in this region), the flame core does not receive cooling action (extinguishing action), the ignitability is greatly improved, and further improvement in thermal efficiency can be expected by further lean combustion .

BEST MODE FOR CARRYING OUT THE INVENTION

図１（イ）は本発明による内燃機関を示し、ガソリンなどを燃料とし、点火プラグの様な点火構造体により燃焼室内混合気に点火するものである。
ＥＣＵ（電子制御ユニット）１３はＲＯＭ、ＲＡＭ、ＣＰＵ、入出力ポート等から成るマイクロコンピューターを中心として構成され、これらは双方性バスによって相互に接続されている。ＥＣＵ１３にはエンジン運転状態の把握に必要なパラメーター用の各種センサー、例えば所定のクランク角毎にクランク角信号を出力するクランク角センサー、所定のカム角毎にカム角信号を出力するカム角センサー、アクセル開度を検出するアクセルセンサー、エンジン回転速度センサー、エンジンに吸入される空気流量センサー、ノックセンサー、Ｏ_２センサー、エンジン冷却水温を検出する水温センサー、大気圧センサー、等からの各信号が対応するＡ／Ｄコンバーターを介して入力ポートに送信される。又、出力ポートは点火プラグ２、燃料噴射弁１１、絞り弁９を駆動するアクチュエーター１０、水噴射弁１２等と各々対応する駆動回路を介して接続され、各々の制御信号を送信する。ＲＯＭには燃料噴射弁の噴射量や噴射時期を決定する為の制御ルーチン、点火プラグへの通電を制御する為の制御ルーチン、絞り弁９の開度を制御する為の制御ルーチン、水噴射弁の噴射量や噴射時期を決定する為の制御ルーチン等のエンジンを制御する為の制御ルーチンやそれらに用いられる制御値を含む制御マップが記憶されている。ＲＡＭに記憶されている各種データーはエンジン回転速度センサーが信号を出力する度に最新のデーターに置き換えられる。
ＣＰＵはＲＯＭに記憶されたアプリケーションプログラムに従って動作し、燃料や水の噴射制御、点火時期制御、絞り弁の開度制御等を実行する。
本内燃機関は電気火花などの点火源により混合気に点火するものであり、図１は吸気弁５、排気弁７を有する４サイクル内燃機関を示している。
本発明では燃焼室１内の混合気は点火構造体２によって点火されるが、図では点火プラグが使用され、点火構造体の突出部材３（電極）を燃焼室壁面からｌ＝１０ｍｍ以上突出させ（従来は６〜８ｍｍ以下）、突出部材３の先端部に点火部（火花ギャップ）を有している。こうすると前記点火部を燃焼室中心に配置する事ができ（完全に中心でなくても従来よりは遙かに中心に近く配置できる）、例えば突出部材３の突出量ｌ＝２０ｍｍとすると燃焼室１の容積は半径ｌの球形燃焼室とほぼ同じ容積の４／３・π・（２）^３≒３３．５ｃｍ^３となり、圧縮ε＝１６とするとシリンダー排気量は３３．５×（１６−１）≒５００ｃｍ^３が可能となる（ｌ＝２．５ｃｍでは９８０ｃｍ^３が可能）。以上の構造によれば前記点火部は燃焼室中心に配置する事ができるから、火炎伝播距離は半減し、従って燃焼期間も半減する一方、火炎は燃焼が完了するまで冷たい燃焼室壁面に接触せず、従って冷却されないので、燃焼による温度・圧力上昇が著るしく、この結果この温度・圧力の上昇により燃焼速度が更に増すので、この相乗効果により最終的には燃焼期間は１／２．５位まで短縮化され、急速燃焼が達成される。即ち、従来では燃焼期間がクランク角で４０°〜６０°であったが、これを２０°位に短縮できる。スキッシュ部の混合気は火炎伝播に依存すると燃焼が遅くなるから、燃焼室１の急速燃焼によりその上昇した燃焼温度・圧力により自着火させる事ができるから、かくして全体として急速燃焼が可能であり、この場合、スキッシュ部の混合気は少量なので衝撃的燃焼は避けられる（点火時期を制御することによりスキッシュ部の自着火を上死点を少し過ぎた時点で引き起す事もできる）。従って最適点火時期を遅らせる事ができ、この結果最高燃焼温度・圧力が減少し、冷却損失・摩擦損失の低減により熱効率は大幅に向上する。本発明では更なる熱効率向上の為、希薄燃焼と合わせて実施するのが良い。即ち、希薄燃焼は一般には燃焼速度が遅くなり限界があるが、本発明では急速燃焼が可能なので、両者の相乗

減少が得られ、著るしい熱効率の向上が見込まれる。本発明では突出部材３（電極）が長い為、アイドルを含む極低負荷域でもその先端部、即ち点火部が高温に保たれ（受熱面積が増すのがその理由である）。この結果、点火によって生じる火炎核が突出部材先端部による冷却作用（消炎作用）を受け難く、火炎核が大きく成長し易いから着火性が向上し、より一層の希薄燃焼を可能とする。これを一段と強化する為、突出部材３の先端部を融点の高い白金、イリジウム、更にはタングステンなどの各合金を用いて極細にする事が考えられる。更には本発明では点火部は燃焼室中心にあり、この部分はスワールによる混合気流速が遅く火炎核が吹き飛ばされる事がなく、冷たい燃焼室壁面から離れている為、点火前の混合気は高温に保たれ、これらの効果も着火性を更に向上させるのである。この様に従来よりは遙かに希薄燃焼が可能となるから、熱効率の向上は著しいものとなる。
次に上記の様に本発明では突出部材３が長く受熱面積が大きいから高温となり、（中）・高負荷域では限界を越えて過早点火の原因となる為、水噴射弁１２から噴射される微粒化された水の噴流を突出部材３に噴き付けて冷却する様にしている。即ち、図１（イ）の如く水タンクａに貯蔵された水をフィードポンプｂ（例えば多数のローラーを溝内に収めたローターを有するポンプ）によって加圧してコモンレールｄに導びき、ここから各気筒に配置された水噴射弁１２から微粒化した水の噴流を突出部材３に噴き付ける構成とするのである。水噴射弁１２は吸気通路６内に臨む如く配置され、吸気弁５が開いている間に（ピストン４も十分に下っている）その間隙を介して点火構造体２の突出部材３に向けて破線の如く噴き付けられる（水噴射弁１２は図１（ロ）の様に燃焼室に直接臨む如くシリンダーヘッド面に備えても良い）。この時、微粒化された水の噴流は点火構造体２の突出部材３、即ち中心電極にも接地電極にも均等に噴き付けられる様にする事が大切である――図では微粒化された水の噴流は主として接地電極に噴き付けられる様に見えるが、これは突出部材３の構造を判り易い様に描いた図の為であり、実際はこれを９０°回転させた位置に配置するのである。そして突出部材３の先端部は火花ギャップがあり、水滴となって付着すると火花が飛ばなくなるから、ここは避ける様に微粒化された水の噴流を噴き付ける事が望ましい。
即ち、この部分の冷却は微粒化された水の噴流が噴き付けられて温度が下った部分への伝熱によって冷却される。又、微粒化された水の噴流が噴き付けられるから、突出部材３は錆に強いステンレス鋼が望ましく、その先端部は極細の白金チップとする事が望ましい。噴射される水の微粒化を良好にする為、フィードポンプｂの発生圧力はできる限り高くする事が望ましく（例えば１０気圧）、水噴射弁１２もスワールを伴なって噴射される様にして微粒化を助ける構造とする。ｃはコモンレールｄ内の圧力を一定に保つ為の調圧装置である（規定の圧力を越えたら圧力を吸入側へ逃す作用を行なう）。水噴射弁１２による水の噴射は低負荷域では行なわないが（フィードポンプｂも停止させる）。高負荷域では必らず行ない、中負荷域では点火プラグの特性によって行なわない場合もあるし、水噴射量を制限して行なう場合もある。
以上の水噴射弁１２の噴射量や噴射時期は燃料噴射弁１１の制御技術によって容易に実行する事ができる。低負荷域で水噴射を行なわない理由は突出部材３を高温に維持して点火部における火炎核の消炎作用を防止する為である。以上により、突出部材３は長く突出しているにも拘らず過早点火を誘発するほどの高温にはならない（低負荷域では従来よりは遙かに高温であり、着火性は向上する。）FIG. 1 (a) shows an internal combustion engine according to the present invention, which uses gasoline or the like as fuel and ignites a mixture in a combustion chamber by an ignition structure such as a spark plug.
The ECU (electronic control unit) 13 is mainly composed of a microcomputer comprising a ROM, a RAM, a CPU, an input / output port, etc., and these are connected to each other by a bidirectional bus. The ECU 13 includes various sensors for parameters necessary for grasping the engine operating state, such as a crank angle sensor that outputs a crank angle signal for each predetermined crank angle, a cam angle sensor that outputs a cam angle signal for each predetermined cam angle, Each signal from the accelerator sensor that detects the accelerator opening, the engine rotation speed sensor, the air flow sensor that is sucked into the engine, the knock sensor, the O ₂ sensor, the water temperature sensor that detects the engine cooling water temperature, the atmospheric pressure sensor, etc. To the input port via the A / D converter. The output port is connected to the ignition plug 2, the fuel injection valve 11, the actuator 10 that drives the throttle valve 9, the water injection valve 12, and the like via corresponding drive circuits, and transmits respective control signals. The ROM has a control routine for determining the injection amount and injection timing of the fuel injection valve, a control routine for controlling energization to the spark plug, a control routine for controlling the opening of the throttle valve 9, a water injection valve A control map including a control routine for controlling the engine, such as a control routine for determining the injection amount and injection timing, and a control value used for the control routine are stored. Various data stored in the RAM are replaced with the latest data every time the engine speed sensor outputs a signal.
The CPU operates in accordance with an application program stored in the ROM, and executes fuel and water injection control, ignition timing control, throttle valve opening control, and the like.
This internal combustion engine ignites an air-fuel mixture by an ignition source such as an electric spark. FIG. 1 shows a four-cycle internal combustion engine having an intake valve 5 and an exhaust valve 7.
In the present invention, the air-fuel mixture in the combustion chamber 1 is ignited by the ignition structure 2. However, in the drawing, a spark plug is used, and the projecting member 3 (electrode) of the ignition structure is projected from the combustion chamber wall surface by l = 10 mm or more. (Conventionally 6 to 8 mm or less), the projecting member 3 has an ignition part (spark gap) at the tip. In this way, the ignition part can be arranged in the center of the combustion chamber (even if it is not completely centered, it can be arranged much closer to the center than in the prior art). For example, when the protruding amount 1 of the protruding member 3 is 20 mm, the combustion chamber The volume of 1 is 4/3 · π · (2) ³ ≈33.5 cm ^{3 which} is almost the same volume as the spherical combustion chamber of radius l, and if the compression ε = 16, the cylinder displacement is 33.5 × (16-1 ) ≈500 cm ³ is possible (when 1 = 2.5 cm, 980 cm ³ is possible). According to the above structure, since the ignition part can be arranged at the center of the combustion chamber, the flame propagation distance is halved and therefore the combustion period is also halved, while the flame is kept in contact with the cold combustion chamber wall until combustion is completed. Therefore, since it is not cooled, the temperature and pressure increase due to combustion is remarkable. As a result, the combustion speed is further increased by the increase in temperature and pressure. Is shortened to a high level, and rapid combustion is achieved. That is, conventionally, the combustion period was 40 ° to 60 ° in crank angle, but this can be shortened to about 20 °. Since the air-fuel mixture in the squish portion depends on flame propagation, the combustion slows down, so that it can be ignited by the increased combustion temperature and pressure by the rapid combustion in the combustion chamber 1, and thus rapid combustion as a whole is possible. In this case, since the air-fuel mixture in the squish portion is small, shock combustion is avoided (the ignition timing can be controlled to cause self-ignition of the squish portion at a point just past the top dead center). Therefore, the optimum ignition timing can be delayed, and as a result, the maximum combustion temperature and pressure are reduced, and the thermal efficiency is greatly improved by reducing the cooling loss and friction loss. In the present invention, in order to further improve the thermal efficiency, it is preferable to carry out in combination with lean combustion. In other words, lean combustion generally has a limit because the combustion speed becomes slow, but in the present invention, rapid combustion is possible, so the synergy of both.

A reduction is obtained, and a significant improvement in thermal efficiency is expected. In the present invention, since the protruding member 3 (electrode) is long, the tip portion, that is, the ignition portion is kept at a high temperature even in an extremely low load region including idle (the reason is that the heat receiving area is increased). As a result, flame nuclei generated by ignition are less susceptible to the cooling action (extinguishing action) by the tip of the protruding member, and the flame nuclei are easy to grow large, so that ignitability is improved and further lean combustion is possible. In order to reinforce this further, it is conceivable that the tip of the protruding member 3 is made finer by using alloys such as platinum, iridium, and tungsten having a high melting point. Furthermore, in the present invention, the ignition part is located at the center of the combustion chamber, and this part has a slow mixture flow rate due to swirl and flame nuclei are not blown away, and is separated from the cold combustion chamber wall surface. These effects also improve the ignitability. In this way, since lean combustion can be performed much more than before, the improvement in thermal efficiency is significant.
Next, as described above, in the present invention, since the protruding member 3 is long and the heat receiving area is large, the temperature is high, and in the (medium) / high load range, the limit is exceeded, causing premature ignition. A jet of atomized water is sprayed on the projecting member 3 to be cooled. That is, as shown in FIG. 1 (a), water stored in the water tank a is pressurized by a feed pump b (for example, a pump having a rotor in which a large number of rollers are housed in grooves) and led to the common rail d. The jet of atomized water is sprayed onto the protruding member 3 from the water injection valve 12 arranged in the cylinder. The water injection valve 12 is disposed so as to face the intake passage 6 and is directed toward the projecting member 3 of the ignition structure 2 through the gap while the intake valve 5 is open (the piston 4 is also sufficiently lowered). The water injection valve 12 may be provided on the cylinder head surface so as to directly face the combustion chamber as shown in FIG. At this time, it is important that the atomized water jet is sprayed evenly on the projecting member 3 of the ignition structure 2, that is, the center electrode and the ground electrode. The water jet appears to be sprayed mainly on the ground electrode, but this is for the purpose of drawing the structure of the protruding member 3 so that it can be easily understood. In practice, this is arranged at a position rotated by 90 °. . The tip of the projecting member 3 has a spark gap, and if it adheres as a water droplet, the spark will not fly. Therefore, it is desirable to spray a jet of atomized water so as to avoid this.
That is, this portion is cooled by heat transfer to the portion where the temperature is lowered by the jet of atomized water. Further, since a jet of atomized water is sprayed, the protruding member 3 is preferably made of stainless steel that is resistant to rust, and its tip is preferably made of an extremely fine platinum chip. In order to improve atomization of the water to be injected, it is desirable that the pressure generated by the feed pump b is as high as possible (for example, 10 atm), and the water injection valve 12 is also injected with a swirl to make fine particles. A structure that helps make it easier. c is a pressure adjusting device for keeping the pressure in the common rail d constant (when the pressure exceeds a specified pressure, the pressure is released to the suction side). Water injection by the water injection valve 12 is not performed in the low load range (the feed pump b is also stopped). This is necessarily performed in the high load range, and may not be performed in the middle load range depending on the characteristics of the spark plug, or may be performed with the water injection amount limited.
The above-described injection amount and injection timing of the water injection valve 12 can be easily executed by the control technique of the fuel injection valve 11. The reason why water injection is not performed in the low load region is to prevent the extinguishing action of the flame kernel in the ignition part by maintaining the protruding member 3 at a high temperature. As described above, although the protruding member 3 protrudes long, the temperature does not become high enough to induce pre-ignition (in the low load region, the temperature is much higher than before and the ignitability is improved).

図１（イ）では吸・排気弁がシリンダーヘッド面に直立した配置であったが、一定の傾斜角を与えて弁面積を増加させ、吸排気効率を向上させたのが図２（イ）である。
もちろん、点火構造体２の点火部は燃焼室の中心又はできる限り中心に近く配置してある。図２（ロ）は点火構造体を複数（図では２個）備えて各々の突出部材３、３′先端部の点火部によって燃焼室１内の混合気を点火・燃焼させようとしたもので、より急速燃焼が可能となり、大排気量エンジンにも適用可能となるものである。水噴射弁１２から噴射される噴流は２方向に分岐して各々の突出部材３、３′に噴き付けられ、冷却する。図１では点火構造体として点火プラグを使用していたが、図３（ハ）の様に副燃焼室１４′から突出してくる突出部材１５の先端部に点火部を有する構成の点火構造体１４も考えられる。
この突出部材１５は燃焼室壁面から１０ｍｍ以上突出しており、その先端部は副燃焼室１４′内で燃焼した燃焼ガスの噴口（１〜数個）になっており、これが燃焼室１内の混合気に点火する点火部である。副燃焼室１４′には点火プラグ１６と燃料噴射弁１７（燃焼室１内の混合気よりは若干濃混合気とする役割を持つ）が臨んでおり、燃焼室１内の希薄混合気より若干濃い混合気（しかし希薄混合気である）が点火プラグ１６により点火・燃焼をされると燃焼ガスが突出部材１５の先端部からエネルギーの非常に高い火炎噴流となって噴出し、この点火部によって燃焼室内の希薄混合気が点火される。これにより非常に希薄な混合気でも燃焼が可能であり、突出部材１５の点火部は燃焼室中心（又はできる限り中心に近く）に配置されるから、急速燃焼が可能となり、熱効率の著るしい向上が期待できる。突出部材１５はそのままでは異状高温となるが、図１と同様に水噴射弁１２から噴射される微粒化された水の噴流により冷却されるから、過早点火は起らない。
図２（ニ）に示す点火構造体は、図２（ハ）において副燃焼室１４′を縮小化し燃料噴射弁１７を除去したものに相当し、突出部材１５の先端部（点火部）から噴出する火炎噴流は図２（ハ）よりエネルギーが弱いが、図１の点火プラグよりは強力である。突出部材１５の上部にある噴口１５′はここからも火炎噴流が噴出されるので、より燃焼期間の短縮化が可能である。In Fig. 1 (a), the intake / exhaust valves were placed upright on the cylinder head surface. However, the valve area was increased by giving a constant angle of inclination to improve intake / exhaust efficiency. It is.
Of course, the ignition part of the ignition structure 2 is arranged as close to the center of the combustion chamber as possible. FIG. 2 (b) is provided with a plurality (two in the figure) of ignition structures, and the mixture in the combustion chamber 1 is ignited and burned by the igniting portions of the projecting members 3, 3 ′. Thus, more rapid combustion is possible, and it can be applied to a large displacement engine. The jet flow injected from the water injection valve 12 branches in two directions and is sprayed on the projecting members 3 and 3 'to be cooled. In FIG. 1, the ignition plug is used as the ignition structure. However, as shown in FIG. 3 (c), the ignition structure 14 having an ignition part at the tip of the protruding member 15 protruding from the auxiliary combustion chamber 14 '. Is also possible.
This protruding member 15 protrudes 10 mm or more from the wall surface of the combustion chamber, and its tip is a nozzle (1 to several) of combustion gas burned in the sub-combustion chamber 14 ′, which is mixed in the combustion chamber 1. It is an igniter that ignites fire A spark plug 16 and a fuel injection valve 17 (having a role of a slightly richer mixture than the air-fuel mixture in the combustion chamber 1) face the sub-combustion chamber 14 ′, and slightly more than the lean air-fuel mixture in the combustion chamber 1. When a rich mixture (but a lean mixture) is ignited and burned by the spark plug 16, the combustion gas is ejected from the tip of the projecting member 15 as a very high energy flame jet, The lean mixture in the combustion chamber is ignited. Thus, even a very lean air-fuel mixture can be combusted, and the ignition part of the projecting member 15 is arranged at the center of the combustion chamber (or as close to the center as possible), so that rapid combustion is possible and the thermal efficiency is extremely high. Improvement can be expected. Although the protruding member 15 has an abnormally high temperature as it is, since it is cooled by the jet of atomized water injected from the water injection valve 12 as in FIG. 1, pre-ignition does not occur.
The ignition structure shown in FIG. 2 (d) corresponds to the structure in which the auxiliary combustion chamber 14 'is reduced in FIG. 2 (c) and the fuel injection valve 17 is removed, and is ejected from the tip (ignition part) of the protruding member 15. The flame jet to be performed is weaker than that of FIG. 2C, but is stronger than the spark plug of FIG. Since a flame jet is ejected from the nozzle hole 15 ′ at the upper part of the protruding member 15, the combustion period can be further shortened.

図３（イ）は本発明を２サイクル機関に適用したもので、掃・排気通路を有し、クランク軸１回転毎に１回の膨張行程が得られる。点火構造体２の突出部材３は燃焼室壁面より１０ｍｍ以上突出しており、（中）・高負荷域では水噴射弁１２からの微粒化された水の噴流により冷却されるから過早点火は起らない。低負荷域ではこの冷却は停止され、突出部材３は高温に保たれるから、着火性は良好である。突出部材３の先端部を白金、イリジウム、タングステンなどの各合金により極細とすれば着火性は一般と向上し、更には短時間に数回スパークさせる多重点火とすれば極低負荷域でも点火・燃焼させる事ができ、２サイクル機関の欠点である不整燃焼が解消される。図３（ロ）は超ロングストローク化により冷却損失を大幅に低減できる対向ピストン機関に本発明を適用したもので（Ａ−Ａ′断面を示した図３（ハ）も参照）、一対のピストンは互いに反対方向へ移動し、ピストン頂面間に挟まれた燃焼室１８が形成され、掃気は一方のピストン側に形成された掃気通路から他方のピストン側に形成された排気通路へ流されるユニフロー型である。図は掃気ポンプとしてクランク圧縮式を採用しているが、ルーツブロワを使う事もできる。
燃焼室１８には２個の点火構造体の突出部材３が各々配置され、各々に（中）・高負荷域では水噴射弁１２から噴射される微粒化された水の噴流が噴き付けられ、冷却される。尚、本発明においては燃料を水素とする水素エンジンの場合は排気は無害の水蒸気であるから、これを図３（ニ）の如く熱交換器１９で水、空気などにより冷却して凝縮させ、これを水タンクａ（図１）に導入する様にすれば水の補給は不要である。
尚、図２（ハ）、（ニ）における点火構造体では突出部材１５の先端部（点火部があり、噴口がある）から火炎を噴出させる手段として点火プラグ１６の代りに圧縮比を十分に高めておいて軽油などを噴射する燃料噴射弁を使用する事もできる。尚、図３（ニ）の場合は燃料が水素以外にも適用できる。
又、図２（ハ）、（ニ）では点火プラグに水の付着の心配がない。FIG. 3 (a) shows an application of the present invention to a two-cycle engine, which has a scavenging / exhaust passage and can obtain one expansion stroke for every one rotation of the crankshaft. The protruding member 3 of the ignition structure 2 protrudes 10 mm or more from the wall surface of the combustion chamber, and is cooled by the atomized water jet from the water injection valve 12 in the middle (high) load region, so that pre-ignition occurs. Not. In the low load range, this cooling is stopped and the protruding member 3 is kept at a high temperature, so the ignitability is good. If the tip part of the projecting member 3 is made extremely fine by an alloy such as platinum, iridium, tungsten, etc., the ignitability is generally improved. Further, if multiple ignition is performed with several sparks in a short time, ignition is performed even in an extremely low load range.・ Can be burned, eliminating irregular combustion, which is a disadvantage of 2-cycle engines. FIG. 3 (b) shows the application of the present invention to an opposed piston engine that can significantly reduce the cooling loss due to the ultra-long stroke (see also FIG. 3 (c) showing the AA 'cross section). Move in opposite directions to form a combustion chamber 18 sandwiched between piston top surfaces, and scavenging flows from a scavenging passage formed on one piston side to an exhaust passage formed on the other piston side. It is a type. The figure uses a crank compression type scavenging pump, but a Roots blower can also be used.
In the combustion chamber 18, two projecting members 3 of an ignition structure are disposed, and in each (medium) / high load region, a jet of atomized water injected from the water injection valve 12 is sprayed. To be cooled. In the present invention, in the case of a hydrogen engine using hydrogen as a fuel, the exhaust gas is harmless water vapor, so that it is cooled and condensed by water, air, etc. in the heat exchanger 19 as shown in FIG. If this is introduced into the water tank a (FIG. 1), replenishment of water is unnecessary.
In the ignition structure in FIGS. 2 (c) and 2 (d), a sufficient compression ratio is used in place of the spark plug 16 as means for injecting flame from the tip of the projecting member 15 (there is an ignition part and there is a nozzle). It is also possible to use a fuel injection valve that injects light oil or the like by raising it. In the case of FIG. 3D, the fuel can be applied to other than hydrogen.
Further, in FIGS. 2C and 2D, there is no fear of water adhering to the spark plug.

図１から図３まででは点火構造体の突出部材３を冷却する手段として微粒した水の噴流を噴き付けていたが、空気や気体燃料の様なエンジンの燃焼に関与する気体を圧縮して冷却し、これを膨張機により断熱膨張させて低温の気体とし、これを噴き付けて冷却する事も可能で、この低温の気体が空気の場合を図４に、燃料の場合を図５に示す。
先ず図４（イ）においてエンジンのクランク軸に連結する膨張機２０と圧縮機２１（図４（ロ）参照）とが備えられている（エンジンのクランク軸とベルト、プーリー等を介して膨張機２０のクランク軸２２とを連結させ、クランク軸２２上に圧縮機２１のクランク軸を一体配置する――圧縮機２１は図では膨張機２０の奥手側に配置されている）。圧縮機２１ではエアクリーナーを通った空気がリード弁２９を介して吸入され、圧縮された後にリード弁３０を介して排出され、この圧縮されて昇温した空気は冷却器２８（水冷式又は空冷式）により冷却され、水分を除去した後に膨張機２０に導入される。膨張機２０では吸入弁２４が開いてシリンダー内にピストンストロークの途中まで吸入され、かつこの時点で吸入が遮断されてピストン下死点まで断熱膨張し、低温となった空気はピストン下死点付近から開く図示しない排出弁（吸入弁２４の奥手側にある）を介してサージタンク２５に導入され、更に空気噴射弁２６、ノズル２７を介して吸気弁５が開いている間にその間隙を介して点火構造体の突出部材３に噴き付けられる（吸入弁２４及び図示しない排出弁はクランク軸２２と回転比１／１で歯車を介して駆動されるカム軸２３上に備えられたカムにより、更にプッシュロッド、ロッカーアームを介して駆動される。吸入弁２４がピストンストロークの１／２．５の時点で閉じる様にすると膨張比は２．５であり、空気冷却器２８により３２０ｋまで冷却されると仮定すると、膨張機２０から排出される空気の温度は−５１℃である（理論値）。
かくしてこの低温の空気が空気噴射弁２６、ノズル２７から吸気弁５が開いている間にその間隙を介して点火構造体の突出部材３に噴き付けられ（冷却され）、過早点火を未然に防止する。低負荷域では突出部材３は過早点火を誘発するほどの高温には到らず、着火性向上の為にできる限り高温に保ちたいから、膨張機２０、圧縮機２１の回転を止め（駆動プーリーに内蔵した電磁クラッチを切るなど）、空気噴射弁２６からの低温の空気の噴射を停止する様にする。尚、空気噴射弁２６は燃焼室１に直接臨む如くシリンダーヘッドに備えても良い。圧縮機２１は駆動々力そのものは小さくないが、膨張機２０が動力を発生するので、全体としての駆動損失は小さい。次に図５においてエンジンと膨張機２０、圧縮機２１は互いに図４と同様に連結され、圧縮機２１（図５（ロ）参照）へ導入された気体燃料（気化したＬＰＧ燃料、都市ガスなど）は図４と同様に圧縮された後に冷却器２８によって冷却され、続いて膨張機２０に導入されて断熱膨張し、低温の気体燃料となってサージタンク２５へ送られ燃料噴射弁２６′、ノズル２７′から吸気弁５が開いている間にその間隙を介して点火構造体の突出部材３に噴き付けられ、冷却する。サージタンク２５内の圧力は常時規定の圧力に維持する必要があり、この為、電磁式遮断弁３２、３３が備えられている。即ち、サージタンク２５内の圧力が規定圧を越えたら電磁式遮断弁３２、３３は閉鎖され、これによりサージタンク２５内への燃料流入が遮断され、サージタンク２５内の圧力が規定値より下ったら電磁式遮断弁３２、３３を開いてサージタンク２５内への燃料流入を開始し、かくしてサージタンク２５内の圧力を規定値に維持する。これはサージタンク２５内の圧力を検出する圧力センサー３１からの出力信号によりＥＣＵ１３（図１）が対応する出力信号を電磁式遮断弁３２、３３へ送信する事によって為される。サージタンク２５は圧縮機２１、膨張機２０による圧力変動を緩和する為に十分な容積とする。
低負荷域では点火構造体の突出部材３の温度を十分に高めて着火性を向上させたいから、燃料噴射弁２６′、ノズル２７′から噴射される燃料の噴流を突出部材３に直接噴き付けない様にする必要があり、その為には燃料噴射弁２６′の噴射時期を制御し、吸気弁５が閉じている間に燃料を吸気通路６内に噴射する様にすれば良い。尚、以上までの本発明においては低負荷域では突出部材３（１５）の冷却を停止したが、この領域でも噴流を噴き付けて冷却する様にしても点火部が燃焼室中心に位置する為、急速燃焼が可能である大きな利点を有している。1 to 3, a jet of fine water is sprayed as means for cooling the projecting member 3 of the ignition structure. However, the gas involved in combustion of the engine such as air or gaseous fuel is compressed and cooled. It is also possible to adiabatic expansion by an expander to form a low-temperature gas, which can be sprayed and cooled. FIG. 4 shows the case where the low-temperature gas is air, and FIG. 5 shows the case of fuel.
First, in FIG. 4 (a), an expander 20 and a compressor 21 (see FIG. 4 (b)) connected to the crankshaft of the engine are provided (the expander via the engine crankshaft, belt, pulley, etc.). 20 crankshafts 22 are connected, and the crankshaft of the compressor 21 is integrally disposed on the crankshaft 22—the compressor 21 is disposed on the far side of the expander 20 in the figure). In the compressor 21, air that has passed through an air cleaner is sucked in through a reed valve 29, compressed and then discharged through a reed valve 30, and this compressed and heated air is cooled by a cooler 28 (water-cooled or air-cooled). After being cooled by the formula (2) and removing the moisture, it is introduced into the expander 20. In the expander 20, the suction valve 24 is opened and sucked into the cylinder halfway through the piston stroke, and at this point, the suction is shut off and adiabatically expanded to the bottom dead center of the piston. Is introduced into the surge tank 25 through a discharge valve (not shown) that opens from the back (on the far side of the intake valve 24), and further, through the gap while the intake valve 5 is open through the air injection valve 26 and the nozzle 27. The suction valve 24 and the discharge valve (not shown) are sprayed onto the projecting member 3 of the ignition structure by a cam provided on the crankshaft 22 and a camshaft 23 driven via a gear at a rotation ratio 1/1. Further, it is driven via a push rod and a rocker arm If the intake valve 24 is closed at a time of 1 / 2.5 of the piston stroke, the expansion ratio is 2.5, and the air cooler 28 Assuming cooled to 320k, the temperature of the air discharged from the expander 20 is -51 ° C. (theoretical value).
Thus, this low-temperature air is sprayed (cooled) to the projecting member 3 of the ignition structure through the gap between the air injection valve 26 and the nozzle 27 while the intake valve 5 is open, and pre-ignition is performed in advance. To prevent. In the low load region, the protruding member 3 does not reach a high temperature that induces pre-ignition, and it is desired to keep the temperature as high as possible to improve the ignitability. Therefore, the rotation of the expander 20 and the compressor 21 is stopped (driven). The injection of low-temperature air from the air injection valve 26 is stopped, such as by disengaging the electromagnetic clutch built in the pulley. The air injection valve 26 may be provided in the cylinder head so as to directly face the combustion chamber 1. Although the compressor 21 does not have a small driving force itself, since the expander 20 generates power, the driving loss as a whole is small. Next, in FIG. 5, the engine, the expander 20, and the compressor 21 are connected to each other in the same manner as in FIG. 4, and gaseous fuel introduced into the compressor 21 (see FIG. 5B) (vaporized LPG fuel, city gas, etc.) 4) is compressed by the cooler 28 after being compressed in the same manner as in FIG. 4, and is then introduced into the expander 20 for adiabatic expansion, and is sent to the surge tank 25 as a low-temperature gaseous fuel and sent to the fuel injection valve 26 ', While the intake valve 5 is opened from the nozzle 27 ′, it is sprayed onto the projecting member 3 of the ignition structure through the gap to cool. The pressure in the surge tank 25 must be maintained at a specified pressure at all times, and therefore electromagnetic shut-off valves 32 and 33 are provided. That is, when the pressure in the surge tank 25 exceeds the specified pressure, the electromagnetic shut-off valves 32 and 33 are closed, whereby the fuel inflow into the surge tank 25 is blocked, and the pressure in the surge tank 25 falls below the specified value. Then, the electromagnetic shut-off valves 32 and 33 are opened to start fuel inflow into the surge tank 25, thus maintaining the pressure in the surge tank 25 at a specified value. This is done by sending an output signal corresponding to the ECU 13 (FIG. 1) to the electromagnetic shut-off valves 32 and 33 by an output signal from the pressure sensor 31 that detects the pressure in the surge tank 25. The surge tank 25 has a sufficient volume to relieve pressure fluctuations caused by the compressor 21 and the expander 20.
In the low load range, the temperature of the projecting member 3 of the ignition structure is sufficiently increased to improve the ignitability, so that the fuel jet injected from the fuel injection valve 26 ′ and nozzle 27 ′ is directly sprayed onto the projecting member 3. Therefore, it is necessary to control the injection timing of the fuel injection valve 26 'so that fuel is injected into the intake passage 6 while the intake valve 5 is closed. In the present invention described above, the cooling of the protruding member 3 (15) is stopped in the low load region. However, even in this region, the ignition part is located at the center of the combustion chamber even if the jet is sprayed and cooled. It has the great advantage that rapid combustion is possible.

本発明による点火構造体を備えた内燃機関の図。The figure of the internal-combustion engine provided with the ignition structure by the present invention. 本発明による内燃機関の各種実施例を示す図。The figure which shows the various Example of the internal combustion engine by this invention. 本発明による内燃機関の各種実施例を示す図。The figure which shows the various Example of the internal combustion engine by this invention. 本発明による点火構造体を備えた内燃機関の図。The figure of the internal-combustion engine provided with the ignition structure by the present invention. 本発明による点火構造体を備えた内燃機関の図。The figure of the internal-combustion engine provided with the ignition structure by the present invention. 従来の点火構造体、例えば点火プラグを示す図。The figure which shows the conventional ignition structure, for example, a spark plug.

１，１８は燃焼室、２，１４・は点火構造体、３・１５は突出部材、４はピストン、５は吸気弁、６は吸気通路、７は排気弁、８は排気通路、９は絞り弁、１０はアクチュエーター、１１は燃料噴射弁、１２は水噴射弁、１３は電子制御ユニット、１４′は副燃焼室、１５′は噴口、１６は点火プラグ、１７は燃料噴射弁、１９は熱交換器、２０は膨張機、２１は圧縮機、２２はクランク軸、２３はカム軸、２４は排出弁、２５はサージタンク、２６は空気噴射弁、２７はノズル、２８は冷却器、２９はリード弁、３０はリード弁、３１は圧力センサー、３２は電磁式遮断弁、３３は電磁式遮断弁、ａは水タンク、ｂはフィードポンプ、ｃは調圧装置、ｄはコモンレール、３′は突出部材、２６′は燃料噴射弁、２７′はノズルである。1 and 18 are combustion chambers, 2 and 14 are ignition structures, 3 and 15 are projecting members, 4 is a piston, 5 is an intake valve, 6 is an intake passage, 7 is an exhaust valve, 8 is an exhaust passage, and 9 is a throttle. Valve 10, actuator 10, fuel injection valve 11, water injection valve 12, electronic control unit 13, auxiliary combustion chamber 14 ′, injection port 15 ′, spark plug 16, fuel injection valve 17, heat 19 Exchanger, 20 expander, 21 compressor, 22 crankshaft, 23 cam shaft, 24 discharge valve, 25 surge tank, 26 air injection valve, 27 nozzle, 28 cooler, 29 Reed valve, 30 is a reed valve, 31 is a pressure sensor, 32 is an electromagnetic shut-off valve, 33 is an electromagnetic shut-off valve, a is a water tank, b is a feed pump, c is a pressure regulator, d is a common rail, 3 ' The protruding member 26 'is a fuel injection valve, and 27' is a nozzle.

Claims

An internal combustion engine having a projecting member projecting 10 mm or more from the combustion chamber wall surface and having an ignition structure having an ignition part for igniting an air-fuel mixture in the combustion chamber at its tip, and water is supplied to the projecting member of the ignition structure An internal combustion engine that cools by spraying atomized jets.

An internal combustion engine having a projecting member projecting from the combustion chamber wall surface by 10 mm or more and having an ignition structure having an ignition unit for igniting the air-fuel mixture in the combustion chamber at the tip thereof, and the projecting member of the ignition structure An internal combustion engine in which a gas involved in combustion is cooled by being compressed by a compressor provided in the engine and then cooled by spraying a low-temperature gas obtained by adiabatic expansion of the gas by an expander.