JP2020153238A - Combustion chamber - Google Patents

Combustion chamber Download PDF

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JP2020153238A
JP2020153238A JP2019049439A JP2019049439A JP2020153238A JP 2020153238 A JP2020153238 A JP 2020153238A JP 2019049439 A JP2019049439 A JP 2019049439A JP 2019049439 A JP2019049439 A JP 2019049439A JP 2020153238 A JP2020153238 A JP 2020153238A
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combustion chamber
shape
wall surface
fuel
annular portion
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景太 荒戸
Keita Arato
景太 荒戸
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Isuzu Motors Ltd
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Isuzu Motors Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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Abstract

To provide a combustion chamber capable of suppressing generation of smoke.SOLUTION: In a combustion chamber 10 recessedly formed on a center portion of a top surface 12 of a piston 11 which reciprocates inside a cylinder, a plurality of wall surfaces 20 facing a C2 direction opposite from a C1 direction which is a flow direction of a swirl flow are arranged in an annular portion 19 at an outer edge of a bottom 16 of the recession at intervals in the C1 direction.SELECTED DRAWING: Figure 1

Description

本開示は、燃焼室に関し、より詳細には、スモークの発生を抑制する燃焼室に関する。 The present disclosure relates to a combustion chamber, and more particularly to a combustion chamber that suppresses the generation of smoke.

エンジンの燃焼室において、中央部に配置されて上方に向かって突出する突起部の表面に上下方向に延びる複数の溝を形成し、燃焼室の壁面に沿って流れる燃料の通過経路が互いに隣り合う溝どうしの間に位置されるものが提案されている（例えば、特許文献１を参照）。この装置において、噴霧された燃料は壁面に衝突後に溝どうしの間を流れることで、溝の中で流入することなく、滞留することもない。それ故、燃料と空気との混合気の撹拌、混合が促進されることで排気エミッションが向上していた。 In the combustion chamber of an engine, a plurality of grooves extending in the vertical direction are formed on the surface of a protrusion arranged in the center and projecting upward, and the passage paths of fuel flowing along the wall surface of the combustion chamber are adjacent to each other. Those located between the grooves have been proposed (see, for example, Patent Document 1). In this device, the sprayed fuel flows between the grooves after colliding with the wall surface, so that it does not flow into the grooves and does not stay there. Therefore, the exhaust emission is improved by promoting the agitation and mixing of the air-fuel mixture.

特開平１１−０１３４７２号公報Japanese Unexamined Patent Publication No. 11-013472

ところで、多量の燃料を噴霧する運転領域では、燃費の悪化を回避するために負荷に応じた必要な燃料量を一定期間内に噴霧する必要がある。従って、噴孔面積の小さな燃料噴霧装置を用いる場合、高負荷時に必要な燃料量を一定期間内に噴霧することが可能な総噴孔面積を確保する必要があった。それ故、燃料噴霧装置の多噴孔化が必須となっていた。 By the way, in the operating region where a large amount of fuel is sprayed, it is necessary to spray a required amount of fuel according to the load within a certain period in order to avoid deterioration of fuel efficiency. Therefore, when a fuel spraying device having a small injection hole area is used, it is necessary to secure a total injection hole area capable of spraying the required amount of fuel within a certain period when the load is high. Therefore, it has been essential to increase the number of injection holes in the fuel spraying device.

しかしながら、燃料噴霧装置を多噴孔化すると、上記の特許文献１に記載の装置では、隣り合う噴孔どうしの間隔が狭くなる。それ故、溝を設けたとしても、燃料噴霧装置の各噴孔から噴霧された燃料が燃焼室の壁面に衝突した後、スワール流によってスワール流の流方向に流されて隣り合う噴霧どうしが干渉するという問題があった。この噴霧どうしの干渉によって燃焼室内に燃料の過濃領域が形成されることは、スモークの生成量が増大する要因となっている。 However, when the number of injection holes in the fuel spraying device is increased, the distance between adjacent injection holes becomes narrower in the device described in Patent Document 1 described above. Therefore, even if a groove is provided, after the fuel sprayed from each injection hole of the fuel spray device collides with the wall surface of the combustion chamber, the fuel is flowed in the flow direction of the swirl flow by the swirl flow and the adjacent sprays interfere with each other. There was a problem of doing. The formation of a fuel-rich region in the combustion chamber due to the interference between the sprays is a factor in increasing the amount of smoke produced.

本開示の目的は、スモークの生成を抑制する燃焼室を提供することである。 An object of the present disclosure is to provide a combustion chamber that suppresses the formation of smoke.

上記の目的を達成する本発明の一態様の燃焼室は、シリンダの内部を往復するピストンの頂面の中央部が窪んで構成される燃焼室において、スワール流の流方向の反対側の方向に面する壁面が、その流方向に間隔を空けて窪みの底部の外縁の環状部位に複数配置されることを特徴とする。 The combustion chamber of one aspect of the present invention that achieves the above object is a combustion chamber formed by recessing the central portion of the top surface of a piston that reciprocates inside the cylinder, in a direction opposite to the flow direction of the swirl flow. A plurality of facing wall surfaces are arranged at an annular portion on the outer edge of the bottom of the depression at intervals in the flow direction.

本発明の一態様によれば、壁面によりスワール流の影響によって噴霧された燃料がスワール流の流方向への流れることを防ぐことで、隣り合う噴霧どうしの干渉を抑制することができる。これにより、スモークの生成を抑制することができる。 According to one aspect of the present invention, it is possible to suppress the interference between adjacent sprays by preventing the fuel sprayed by the influence of the swirl flow from flowing in the flow direction of the swirl flow by the wall surface. As a result, the generation of smoke can be suppressed.

燃焼室の第一実施形態を例示する斜視図である。It is a perspective view which illustrates the 1st Embodiment of a combustion chamber. 図１の一部を拡大した平面図である。It is an enlarged plan view of a part of FIG. 図２の矢印ＩＩＩで示す断面を例示する断面図である。It is sectional drawing which illustrates the cross section shown by the arrow III of FIG. 図２の矢印ＩＶで示す断面を例示する断面図である。It is sectional drawing which illustrates the cross section shown by the arrow IV of FIG. 燃焼室の第二実施形態を例示する平面図である。It is a top view which illustrates the 2nd Embodiment of a combustion chamber. 図５の矢印ＶＩで示す断面を例示する断面図である。It is sectional drawing which illustrates the cross section shown by the arrow VI of FIG. 燃焼室の第三実施形態を例示する平面図である。It is a top view which illustrates the 3rd Embodiment of a combustion chamber. 図７の矢印ＶＩＩＩで示す断面を例示する断面図である。It is sectional drawing which illustrates the cross section shown by the arrow VIII of FIG.

以下に、本開示における燃焼室の実施形態について説明する。なお、本開示でピストン１１が往復運動するシリンダ（図示しない）は、図１において中心軸の軸方向が上下方向に向いているものとする。従って、図中では、Ｃ方向をシリンダの中心軸まわりの周方向とし、Ｃ１方向をＣ方向のうちのスワール流の流方向（左回りの方向）とし、Ｃ２方向をＣ１方向の反対側の方向（右回りの方向）とし、Ｄ方向をシリンダの径方向とする。また、Ｘ方向をＤ方向のうちの一方向とし、Ｚ方向をシリンダの中心軸の軸方向とし、Ｙ方向をＸ方向及びＺ方向のそれぞれに直交する方向とし、Ｚ方向は鉛直方向に限定されないものとする。また、本開示では、「角」は相交わる二平面や二直線が作る形状を示すものとし、場所を示す意味では用いないものとする。また、図中では、「角」がある形状を実線で示し、「角」の無い形状については点線で示すものとする。 Hereinafter, embodiments of the combustion chamber in the present disclosure will be described. In the present disclosure, it is assumed that the cylinder (not shown) in which the piston 11 reciprocates has its central axis oriented in the vertical direction in FIG. Therefore, in the figure, the C direction is the circumferential direction around the central axis of the cylinder, the C1 direction is the swirl flow direction (counterclockwise direction) of the C direction, and the C2 direction is the direction opposite to the C1 direction. (Rightward direction), and the D direction is the radial direction of the cylinder. Further, the X direction is one of the D directions, the Z direction is the axial direction of the central axis of the cylinder, the Y direction is a direction orthogonal to each of the X direction and the Z direction, and the Z direction is not limited to the vertical direction. Shall be. Further, in the present disclosure, "corner" shall indicate a shape formed by two intersecting planes or two straight lines, and shall not be used in the sense of indicating a place. Further, in the figure, the shape having "corners" is shown by a solid line, and the shape without "corners" is shown by a dotted line.

図１に例示するように、燃焼室１０は、図示しないシリンダの内部をＺ方向に往復運動するピストン１１の頂面１２の中央部が下方に向かって凹状に窪んで構成される。燃焼室１０は頂面１２に形成されたこの窪みと図示しないシリンダの内壁面と燃料噴霧装置１３および吸排気弁が設置されたシリンダヘッドとに囲まれた空間のことを示すが、本開示で燃焼室１０はこの窪みを示すものとする。 As illustrated in FIG. 1, the combustion chamber 10 is configured such that the central portion of the top surface 12 of the piston 11 that reciprocates in the Z direction inside a cylinder (not shown) is recessed downward. The combustion chamber 10 indicates a space surrounded by this recess formed on the top surface 12, an inner wall surface of a cylinder (not shown), a fuel spray device 13, and a cylinder head in which an intake / exhaust valve is installed. The combustion chamber 10 shall indicate this depression.

燃焼室１０は、上方から下方に向かって筒部１４とリップ部１５と底部１６とが順に配置された分配型の燃焼室で構成される。本開示において、分配型の燃焼室とは燃料噴霧装置１３から噴霧された燃料がリップ部１５に衝突して上下二方向に分配される機能を有するものを示す。燃焼室１０は、そのような分配型の燃焼室に限定されずに、燃料噴霧装置１３から噴霧された燃料がリップ部１５に衝突して少なくとも下方に導かれるものでもよい。燃焼室１０としては、リップ部１５の上方に筒部１４を有さないものも例示される。
燃焼室１０の窪みの形状としては椀状、半球形状、多球形状が例示され、その横断面形状（Ｘ−Ｙ平面の断面形状）としては円形状や多円形状が例示される。 The combustion chamber 10 is composed of a distribution type combustion chamber in which a tubular portion 14, a lip portion 15, and a bottom portion 16 are arranged in order from above to below. In the present disclosure, the distribution type combustion chamber means a combustion chamber having a function of colliding the fuel sprayed from the fuel spraying device 13 with the lip portion 15 and distributing the fuel in two directions up and down. The combustion chamber 10 is not limited to such a distribution type combustion chamber, and the fuel sprayed from the fuel spraying device 13 may collide with the lip portion 15 and be guided at least downward. As the combustion chamber 10, a combustion chamber 10 having no tubular portion 14 above the lip portion 15 is also exemplified.
Examples of the shape of the depression of the combustion chamber 10 include a bowl shape, a hemispherical shape, and a multispherical shape, and examples thereof include a circular shape and a multicircular shape as the cross-sectional shape (cross-sectional shape of the XY plane).

筒部１４は、Ｚ方向の両端が開口した筒の内筒面で構成される。筒部１４は内筒面で構成されればよく、その内筒面が上方から下方に向かって拡径してもよく、上方から下方に向かって縮径してもよい。また、筒部１４は、その内筒面が上方から下方に向かって段々に変化する段状の筒面でもよい。 The cylinder portion 14 is composed of an inner cylinder surface of a cylinder having both ends open in the Z direction. The cylinder portion 14 may be formed of an inner cylinder surface, and the diameter of the inner cylinder surface may be increased from the upper side to the lower side or may be reduced from the upper side to the lower side. Further, the tubular portion 14 may be a stepped tubular surface whose inner tubular surface gradually changes from the upper side to the lower side.

リップ部１５は、筒部１４および底部１６の間に位置し、Ｚ方向に見て筒部１４の内側の面よりも中央側に突出した環状の部位である。リップ部１５は、Ｚ方向に見て中央側に突出した角に丸みを付けてもよい。リップ部１５は、燃料噴霧装置１３から噴霧された燃料が衝突する衝突部位１７を有し、衝突部位１７に衝突したその燃料のうちの一部の燃料をＺ方向上方に、その他の燃料をＺ方向下方にそれぞれ分割させるように機能する。なお、一つの燃焼室１０に複数のリップ部１５が設けられてもよく、複数のリップ部１５がＺ方向に多段状に設けられてもよい。 The lip portion 15 is an annular portion located between the tubular portion 14 and the bottom portion 16 and projecting toward the center of the inner surface of the tubular portion 14 when viewed in the Z direction. The lip portion 15 may have rounded corners protruding toward the center when viewed in the Z direction. The lip portion 15 has a collision portion 17 in which the fuel sprayed from the fuel spraying device 13 collides, and a part of the fuel colliding with the collision portion 17 is upward in the Z direction, and the other fuel is Z. It functions to divide each downward in the direction. A plurality of lip portions 15 may be provided in one combustion chamber 10, and a plurality of lip portions 15 may be provided in a multi-stage shape in the Z direction.

衝突部位１７は、燃料噴霧装置１３から噴霧された燃料が衝突する部位であり、リップ部１５のＣ方向に間隔を空けて複数配置される。リップ部１５における衝突部位１７の配置位置と専有領域とは、燃料噴霧装置１３ごとに適宜設定される。衝突部位１７は、燃料が衝突する領域であり、図中では点線で囲われた領域とする。 The collision portion 17 is a portion where the fuel sprayed from the fuel spraying device 13 collides, and a plurality of collision portions 17 are arranged at intervals in the C direction of the lip portion 15. The arrangement position and the exclusive area of the collision portion 17 in the lip portion 15 are appropriately set for each fuel spraying device 13. The collision site 17 is a region where the fuel collides, and is a region surrounded by a dotted line in the figure.

底部１６は、窪みである燃焼室１０の底に位置し、Ｚ方向の上端が開口する一方で下端が閉口した有底筒状を成し、上方から下方に向かって開口径が徐々に狭まる椀状を成す。底部１６は、中央部に上方に向かって膨らんで成る膨らみ１８と、膨らみ１８よりも縁側でＺ方向に見て環状を成す環状部位１９と、を有する。 The bottom portion 16 is located at the bottom of the combustion chamber 10 which is a depression, and has a bottomed tubular shape in which the upper end in the Z direction opens while the lower end closes, and the opening diameter gradually narrows from the upper side to the lower side. Form a shape. The bottom portion 16 has a bulge 18 that bulges upward toward the center, and an annular portion 19 that forms an annular shape when viewed in the Z direction on the veranda side of the bulge 18.

膨らみ１８は、底部１６の底から上方に向かって凸の椀状に膨らんで成る。膨らみ１８の最高位置は、リップ部１５の上端の位置よりも低くすることが望ましい。環状部位１９は、底部１６の外縁部に位置する部位であり、より具体的に膨らみ１８の裾野とリップ部１５との間の部位である。環状部位１９は、その表面が環状体状に窪んで成る。ここでいう環状体としては、トーラス体（円環体）が例示される。環状部位１９は、底部１６において外縁部に位置する環状の部位であればよく、その表面が環状体状に窪んだものに限定されない。 The bulge 18 is formed by bulging like a bowl upward from the bottom of the bottom portion 16. It is desirable that the highest position of the bulge 18 is lower than the position of the upper end of the lip portion 15. The annular portion 19 is a portion located at the outer edge portion of the bottom portion 16, and more specifically, a portion between the skirt of the bulge 18 and the lip portion 15. The surface of the annular portion 19 is recessed in an annular shape. As the annular body referred to here, a torus body (annular body) is exemplified. The annular portion 19 may be an annular portion located at the outer edge portion of the bottom portion 16, and the surface thereof is not limited to a concave portion in an annular shape.

燃焼室１０の種類としては、燃料噴霧装置１３から噴霧された燃料が上下に分配される分配型の燃焼室であればよく、上記の構成に限定されない。例えば、燃焼室１０の種類としては、シリンダヘッドの形状に応じてペントルーフ型やウエッジ型が例示される。また、燃焼室１０の種類としては、窪みの形状に応じて深皿型（トロイダル型、リエントラント型、バスタブ型）や浅皿型が例示される。
燃焼室１０は、複数の壁面２０を備えて構成される。また、燃焼室１０は、壁面２０のそれぞれがＣ方向に隣り合う凹み２１どうしの間の凸部位で構成される。 The type of the combustion chamber 10 may be a distribution type combustion chamber in which the fuel sprayed from the fuel spraying device 13 is vertically distributed, and is not limited to the above configuration. For example, as the type of the combustion chamber 10, a pent roof type or a wedge type is exemplified according to the shape of the cylinder head. Further, as the type of the combustion chamber 10, a deep dish type (toroidal type, reentrant type, bathtub type) and a shallow dish type are exemplified according to the shape of the recess.
The combustion chamber 10 includes a plurality of wall surfaces 20. Further, the combustion chamber 10 is composed of convex portions between the recesses 21 having the wall surfaces 20 adjacent to each other in the C direction.

図２および図３に例示するように、壁面２０はＣ２方向に面し、Ｃ１方向に見て三日月型を成す。本開示で、Ｃ２方向に面するとは、Ｃ１方向の燃料の流れに対して抵抗となるように面することを意味し、壁面２０はＣ２方向に向かう面であればよい。このような面としては、例えば、Ｃ２方向に対して直交するＸ−Ｚ平面の他に、Ｃ２方向に対して交差する斜面も例示される。また、Ｃ１方向に見た壁面２０の形状は、Ｃ１方向の燃料の流れに対して抵抗となれば特に限定されず、例えば、矩形状も例示される。 As illustrated in FIGS. 2 and 3, the wall surface 20 faces the C2 direction and forms a crescent shape when viewed in the C1 direction. In the present disclosure, facing in the C2 direction means facing so as to resist the flow of fuel in the C1 direction, and the wall surface 20 may be a surface facing in the C2 direction. As such a plane, for example, in addition to the XZ plane orthogonal to the C2 direction, a slope intersecting the C2 direction is also exemplified. Further, the shape of the wall surface 20 seen in the C1 direction is not particularly limited as long as it becomes a resistance to the flow of fuel in the C1 direction, and for example, a rectangular shape is also exemplified.

複数の壁面２０は、底部１６の環状部位１９にＣ１方向に互いに間隔を空けて配置される。複数の壁面２０は、リップ部１５における衝突部位１７の配置数に対応させた数が配置される。複数の壁面２０の配置間隔は、リップ部１５における衝突部位１７の配置間隔に対応させる。例えば、複数の壁面２０の配置間隔は、衝突部位１７の配置間隔が等間隔の場合にＣ１方向に等間隔に配置される。また、複数の壁面２０の配置間隔は、衝突部位１７の配置間隔が所定の位置からＣ１方向に向かって徐々に広くなる場合に同様にＣ１方向に向かって徐々に広くなるように配置される。 The plurality of wall surfaces 20 are arranged on the annular portion 19 of the bottom portion 16 at intervals in the C1 direction. The plurality of wall surfaces 20 are arranged in a number corresponding to the number of collision portions 17 arranged in the lip portion 15. The arrangement interval of the plurality of wall surfaces 20 corresponds to the arrangement interval of the collision portion 17 in the lip portion 15. For example, the arrangement intervals of the plurality of wall surfaces 20 are arranged at equal intervals in the C1 direction when the arrangement intervals of the collision portions 17 are equal. Further, the arrangement interval of the plurality of wall surfaces 20 is arranged so that the arrangement interval of the collision portion 17 gradually increases in the C1 direction when the arrangement interval of the collision portion 17 gradually increases in the C1 direction.

壁面２０は、衝突部位１７におけるＣ１方向に関して下流側の端部２２から底部１６の中心部に向かう線分Ｌ１に沿って設けられる。ここでいう線分Ｌ１としては、底部１６の中心から径方向Ｄに延在する線分のうちの端部２２に接する線分が例示される。また、壁面２０がその線分Ｌ１に沿って設けられるとは、壁面２０が線分Ｌ１上の底部１６、あるいは、線分Ｌ１のＣ１方向の側方にずれた底部１６から上方に立設して線分Ｌ１に沿ってＤ方向に延在することを示すものとする。壁面２０は、線分Ｌ１のＣ２方向の側方を除き、線分Ｌ１上または線分Ｌ１のＣ１方向の側方に立設することで、衝突部位１７に衝突して下方に分配された燃料の流れを妨げることを回避するには有利になる。 The wall surface 20 is provided along the line segment L1 from the downstream end 22 toward the center of the bottom 16 in the C1 direction at the collision site 17. As the line segment L1 referred to here, a line segment tangent to the end portion 22 of the line segments extending in the radial direction D from the center of the bottom portion 16 is exemplified. Further, the fact that the wall surface 20 is provided along the line segment L1 means that the wall surface 20 is erected above the bottom portion 16 on the line segment L1 or the bottom portion 16 of the line segment L1 displaced laterally in the C1 direction. It shall be shown that it extends in the D direction along the line segment L1. The wall surface 20 is erected on the line segment L1 or on the side of the line segment L1 in the C1 direction except for the side of the line segment L1 in the C2 direction, so that the fuel collides with the collision portion 17 and is distributed downward. It is advantageous to avoid obstructing the flow of.

壁面２０は、底部１６を上方に凸ませて形成してもよいが、底部１６を下方に凹ませて形成することが望ましく、Ｃ方向に隣り合う凹み２１どうしの間の凸部位で構成されることがより望ましい。 The wall surface 20 may be formed by projecting the bottom portion 16 upward, but it is desirable that the wall surface 20 is formed by recessing the bottom portion 16 downward, and is composed of convex portions between the recesses 21 adjacent to each other in the C direction. Is more desirable.

凹み２１は、底部１６の環状部位１９のＣ方向に間隔を空けて配置されて、底部１６から下方に凹状に凹んで成る。また、凹み２１は、一つの壁面２０に対して一つ設けられ、壁面２０に対してＣ２方向に存在する部分である。 The recesses 21 are arranged at intervals in the C direction of the annular portion 19 of the bottom portion 16 and are formed to be recessed downward from the bottom portion 16. Further, one recess 21 is provided for one wall surface 20, and is a portion existing in the C2 direction with respect to the wall surface 20.

凹み２１の形状は、壁面２０を形成することが可能な形状であれば特に限定されない。この実施形態で、Ｚ方向に見た凹み２１の開口形状は矩形状を成す。また、凹み２１の深さは、Ｄ方向に関して凹み２１の中央部から外縁に向かって深さが浅くなるように構成され、Ｃ方向に関して一定の深さとなるように構成される。 The shape of the recess 21 is not particularly limited as long as it can form the wall surface 20. In this embodiment, the opening shape of the recess 21 seen in the Z direction is rectangular. Further, the depth of the recess 21 is configured so that the depth becomes shallower from the central portion of the recess 21 toward the outer edge in the D direction, and is configured to be a constant depth in the C direction.

底部１６を凹み２１により凹ませて壁面２０を形成することで、燃焼室１０の総容積を凹ませた分だけ増やすことができる。このように、燃焼室１０により多くの空間を設けることで、空気との混合を良化するには有利になり、燃焼期間を短縮することができる。 By denting the bottom portion 16 by the dent 21 to form the wall surface 20, the total volume of the combustion chamber 10 can be increased by the dented amount. As described above, providing more space in the combustion chamber 10 is advantageous for improving the mixing with air, and the combustion period can be shortened.

但し、凹み２１のＺ方向の深さを深くする、あるいは開口面積を広くすると、燃焼室１０の総表面積が増えることになり、総表面積の増加による熱損失が増加する。従って、凹み２１の深さや開口面積は、凹み２１を設けることで増加する熱損失よりも、総容積の増加によって得られる燃焼期間の短縮により低減する熱損失が大きくなるように設定することが好ましい。 However, if the depth of the recess 21 in the Z direction is increased or the opening area is increased, the total surface area of the combustion chamber 10 increases, and the heat loss due to the increase in the total surface area increases. Therefore, it is preferable that the depth and opening area of the recess 21 are set so that the heat loss reduced by shortening the combustion period obtained by increasing the total volume is larger than the heat loss increased by providing the recess 21. ..

凹み２１は、Ｃ１方向に存在する内面として壁面２０を、Ｃ２方向に存在する内面として壁面２０に対してＣ方向に対向する対向面２３を、それぞれ有する。対向面２３の形状は特に限定されず、壁面２０に対して面対称となる形状に形成されてもよく、壁面２０と異なる形状に形成されてもよい。対向面２３を壁面２０に対向して設ける場合は、衝突部位１７に衝突して分割された燃料の噴霧の進行を妨げないように衝突部位１７におけるＣ２方向に関して下流側の端部（Ｃ１方向に関して上流側の端部）２４から底部１６の中心部に向かう線分Ｌ２に沿って設けられることが好ましい。 The recess 21 has a wall surface 20 as an inner surface existing in the C1 direction, and a facing surface 23 facing the wall surface 20 in the C direction as an inner surface existing in the C2 direction. The shape of the facing surface 23 is not particularly limited, and may be formed in a shape symmetrical with respect to the wall surface 20 or may be formed in a shape different from that of the wall surface 20. When the facing surface 23 is provided facing the wall surface 20, the end portion on the downstream side with respect to the C2 direction at the collision portion 17 (with respect to the C1 direction) so as not to interfere with the progress of the spray of the fuel divided by colliding with the collision portion 17. It is preferably provided along the line segment L2 from the upstream end) 24 toward the center of the bottom 16.

図４に例示するように、環状部位１９のＣ方向の全周に渡って延在して環状部位１９に配置された全ての壁面２０と凹み２１とを横断する線分で環状部位１９を切断した場合の切断面に現れる環状部位１９の表面形状は波形状を成すことが好ましい。 As illustrated in FIG. 4, the annular portion 19 is cut by a line segment extending over the entire circumference of the annular portion 19 in the C direction and crossing all the wall surfaces 20 and the recess 21 arranged in the annular portion 19. It is preferable that the surface shape of the annular portion 19 appearing on the cut surface is wavy.

本開示で、波形状としては、矩形波、正弦波、三角波、および、のこぎり波が例示される。この実施形態における切断面に現れる環状部位１９の表面形状は矩形波を成す。その矩形波の周期はリップ部１５における衝突部位１７の配置間隔に基づき、その振幅は凹み２１のＹ方向の深さに基づく。 In the present disclosure, examples of the wave shape include a square wave, a sine wave, a triangular wave, and a sawtooth wave. The surface shape of the annular portion 19 appearing on the cut surface in this embodiment forms a square wave. The period of the square wave is based on the arrangement interval of the collision sites 17 in the lip portion 15, and the amplitude is based on the depth of the recess 21 in the Y direction.

燃料噴霧装置１３から燃料が噴霧されると、噴霧された燃料はリップ部１５の衝突部位１７に衝突して上下方向に分割される。下方に分割された燃料はスワール流の影響によりＣ１方向へ流れようとするが、壁面２０がその流れに対する抵抗となる。この結果、下方に分割された燃料のスワール流の流速が低減し、その流れが抑制される。 When the fuel is sprayed from the fuel spraying device 13, the sprayed fuel collides with the collision portion 17 of the lip portion 15 and is divided in the vertical direction. The fuel divided downward tries to flow in the C1 direction due to the influence of the swirl flow, but the wall surface 20 becomes a resistance to the flow. As a result, the flow velocity of the swirl flow of the fuel divided downward is reduced, and the flow is suppressed.

このように、本開示の燃焼室１０によれば、燃焼室１０の底部１６に壁面２０を設けることで、壁面２０が抵抗となり下方に進行する燃料のＣ１方向への流れを抑制することができる。これにより、Ｃ方向に隣り合う燃料どうしの干渉を抑制するには有利になり、燃料の過濃領域により生じるスモークの生成量を抑制することができる。 As described above, according to the combustion chamber 10 of the present disclosure, by providing the wall surface 20 on the bottom 16 of the combustion chamber 10, the wall surface 20 acts as a resistance and the downward flow of fuel in the C1 direction can be suppressed. .. This is advantageous for suppressing interference between fuels adjacent to each other in the C direction, and it is possible to suppress the amount of smoke generated due to the fuel enrichment region.

また、本開示の燃焼室１０によれば、下方に分割された燃料は凹み２１により広がった空間により、凹み２１を設けないものに比して空気との混合を良化（促進）させることができる。これにより、燃焼状態を良化して燃焼期間を短縮するには有利になり、燃焼期間が短縮することで熱損失を低下してスモークの生成量を抑制することができる。 Further, according to the combustion chamber 10 of the present disclosure, the fuel divided downward can improve (promote) mixing with air due to the space expanded by the recess 21 as compared with the fuel without the recess 21. it can. This is advantageous for improving the combustion state and shortening the combustion period, and by shortening the combustion period, heat loss can be reduced and the amount of smoke produced can be suppressed.

図５および図６に例示するように、第二実施形態の燃焼室１０は、第一実施形態に対して、凹み２１が角の無い形状を成す点が異なる。本開示で、角の無い形状とは、凹み２１を構成する要素の全てに角が存在しない形状である。具体的に、Ｚ方向に見た凹み２１の開口形状を含む凹み２１の横断面形状としては、円形状や楕円形状、オーバル形状が例示される。 As illustrated in FIGS. 5 and 6, the combustion chamber 10 of the second embodiment is different from the first embodiment in that the recess 21 has a shape without corners. In the present disclosure, the shape without corners is a shape in which all the elements constituting the recess 21 do not have corners. Specifically, as the cross-sectional shape of the dent 21 including the opening shape of the dent 21 seen in the Z direction, a circular shape, an elliptical shape, and an oval shape are exemplified.

凹み２１の深さは凹み２１の中心部から外縁に向かって徐々に浅くなるように構成される。具体的に、凹み２１の任意の縦断面形状としては、一つのスプライン曲線あるいは一つのベジエ曲線で描かれる形状が例示される。 The depth of the recess 21 is configured to gradually become shallower from the central portion of the recess 21 toward the outer edge. Specifically, as an arbitrary vertical cross-sectional shape of the recess 21, a shape drawn by one spline curve or one Bezier curve is exemplified.

凹み２１は、Ｚ方向に見て、長手方向がＣ方向に向いた楕円形状あるいはオーバル形状の外縁がＣ方向に沿って婉曲した形状を成す。切断線で切断した場合の切断面に現れる環状部位１９の表面形状はシヌソイドを成すことが好ましい。この実施形態のシヌソイドの周期はリップ部１５における衝突部位１７の配置間隔に基づき、その振幅は凹み２１のＹ方向の深さに基づく。なお、切断する位置をＸ方向で変化させた場合のシヌソイドの振幅の変化は、凹み２１のＸ方向の深さに基づく。 When viewed in the Z direction, the recess 21 has an elliptical shape or an oval-shaped outer edge whose longitudinal direction faces the C direction and has a curved shape along the C direction. The surface shape of the annular portion 19 that appears on the cut surface when cut along the cutting line preferably forms a sine soid. The period of the sine soid of this embodiment is based on the placement interval of the collision sites 17 on the lip portion 15, and its amplitude is based on the depth of the recess 21 in the Y direction. The change in the amplitude of the sine wave when the cutting position is changed in the X direction is based on the depth of the recess 21 in the X direction.

このように、シヌソイドを用いて波形の周期および振幅を変化させることで、凹み２１の形状を調節することが可能となる。これにより、複数の凹み２１がある複雑な形状であっても容易に製造することができる。 In this way, the shape of the recess 21 can be adjusted by changing the period and amplitude of the waveform using the sine wave. As a result, even a complicated shape having a plurality of recesses 21 can be easily manufactured.

以上のように、凹み２１が角の無い形状を成すことで、角のある形状に比して凹み２１の表面積を減少することができる。これにより、凹み２１を設けることで増加する表面積の増加による熱損失の増加を抑制するには有利になる。 As described above, since the recess 21 has a shape without corners, the surface area of the recess 21 can be reduced as compared with the shape with corners. This is advantageous in suppressing an increase in heat loss due to an increase in the surface area that is increased by providing the recess 21.

また、凹み２１が角のある形状では燃焼時に角に熱応力が集中するおそれがあるが、凹み２１が角の無い形状では燃焼時に特定の部位に熱応力が集中することを回避できる。これにより、角のある形状に比して、熱応力の集中による損壊を回避して、耐久性を向上するには有利になる。 Further, if the recess 21 has a corner shape, the thermal stress may be concentrated on the corner during combustion, but if the recess 21 has no corner shape, the thermal stress can be prevented from being concentrated on a specific portion during combustion. This is advantageous for improving durability by avoiding damage due to concentration of thermal stress as compared with the angular shape.

図７および図８に例示するように、第三実施形態の燃焼室１０は、第一実施形態に対して、環状部位１９の表面が、それ以外の部位（例えば、筒部１４、リップ部１５）の表面よりも粗い点が異なる。 As illustrated in FIGS. 7 and 8, in the combustion chamber 10 of the third embodiment, the surface of the annular portion 19 is a portion other than that of the first embodiment (for example, the tubular portion 14 and the lip portion 15). ) Is different from the surface.

本開示で、表面の粗さは、単位面積あたりの表面積を比較して表面積が広くなるものが粗く、小さくなるものが滑らかとなる。また、表面の粗さは、日本産業規格ＪＩＳ Ｂ ０６０１で規定される線粗さのパラメータにより求められる表面粗さや表面うねりも例示される。 In the present disclosure, the surface roughness is coarser when the surface area is larger and smoother when the surface area is smaller than the surface area per unit area. Further, as the surface roughness, the surface roughness and the surface waviness obtained by the line roughness parameter defined by the Japanese Industrial Standards JIS B 0601 are also exemplified.

燃焼室１０は、環状部位１９のうちの少なくとも壁面２０が底部１６以外の部位の表面よりも粗ければよく、壁面２０に加えて壁面２０に対してＣ２方向に存在する部分である凹み２１の表面も、底部１６以外の部位の表面よりも粗ければよい。燃焼室１０は、環状部位１９の全周に渡って複数の壁面２０が配置される場合に、全ての壁面２０および凹み２１を含む環状部位１９の全域の表面が底部１６以外の部位の表面よりも粗いことがより望ましい。また、燃焼室１０は、底部１６の全域の表面が他の部位の表面よりも粗くてもよい。 In the combustion chamber 10, at least the wall surface 20 of the annular portion 19 may be rougher than the surface of the portion other than the bottom portion 16, and the recess 21 which is a portion existing in the C2 direction with respect to the wall surface 20 in addition to the wall surface 20. The surface may also be rougher than the surface of a portion other than the bottom 16. In the combustion chamber 10, when a plurality of wall surfaces 20 are arranged over the entire circumference of the annular portion 19, the entire surface of the annular portion 19 including all the wall surfaces 20 and the recess 21 is more than the surface of the portion other than the bottom 16. It is more desirable that it is also coarse. Further, the surface of the entire bottom portion 16 of the combustion chamber 10 may be rougher than the surface of other portions.

燃焼室１０において、部位によって表面の粗さを異ならせる方法としては、ブラストなどの表面仕上げ加工により環状部位１９の表面仕上げを粗くする一方で、筒部１４やリップ部１５の表面仕上げを滑らかにする方法が例示される。また、ブラストを応用し、ブラストにより環状部位１９の表面を粗くする方法も例示される。また、ショットピーニングにより環状部位１９に微細なディンプルを形成する方法も例示される。 In the combustion chamber 10, as a method of making the surface roughness different depending on the portion, the surface finish of the annular portion 19 is roughened by surface finishing such as blasting, while the surface finish of the tubular portion 14 and the lip portion 15 is smoothed. The method of doing is exemplified. Further, a method of applying blasting to roughen the surface of the annular portion 19 by blasting is also exemplified. Further, a method of forming fine dimples in the annular portion 19 by shot peening is also exemplified.

以上のように、環状部位１９の一部の領域またはその全域の表面を底部１６以外の部位の表面よりも粗くすることで、燃料のスワール流の流速を低減するには有利になり、Ｃ方向に隣り合う燃料どうしの干渉を抑制する効果が増す。 As described above, by making the surface of a part of the annular portion 19 or the entire region thereof rougher than the surface of the portion other than the bottom 16, it is advantageous to reduce the flow velocity of the swirl flow of the fuel, and it is advantageous in the C direction. The effect of suppressing interference between fuels adjacent to each other increases.

１０ 燃焼室
１１ ピストン
１２ 頂面
１６ 底部
１９ 環状部位
２０ 壁面
Ｃ１ スワール流の流方向
Ｃ２ スワール流の流方向の反対側の方向 10 Combustion chamber 11 Piston 12 Top surface 16 Bottom surface 19 Circular part 20 Wall surface C1 Swirl flow direction C2 Swirl flow direction opposite to the flow direction

Claims (7)

シリンダの内部を往復するピストンの頂面の中央部が窪んで構成される燃焼室において、スワール流の流方向の反対側の方向に面する壁面が、その流方向に間隔を空けて窪みの底部の外縁の環状部位に複数配置されることを特徴とする燃焼室。 In a combustion chamber formed by a depression in the center of the top surface of a piston that reciprocates inside the cylinder, the wall surface facing in the direction opposite to the flow direction of the swirl flow is the bottom of the depression at intervals in the flow direction. A combustion chamber characterized in that a plurality of combustion chambers are arranged in an annular portion on the outer edge of the cylinder. 燃料噴霧装置から噴霧された燃料が衝突する複数の衝突部位が配置されたリップ部を前記底部よりも上方に備え、
前記壁面は、前記衝突部位の前記流方向に関して下流側となる端部と前記底部の中心部とを結ぶ線分に沿って延在する請求項１に記載の燃焼室。 A lip portion in which a plurality of collision sites where the fuel sprayed from the fuel spray device collides is arranged is provided above the bottom portion.
The combustion chamber according to claim 1, wherein the wall surface extends along a line segment connecting an end portion on the downstream side with respect to the flow direction of the collision portion and a central portion of the bottom portion. 前記壁面の表面が前記底部以外の部位の表面よりも粗い請求項１または２に記載の燃焼室。 The combustion chamber according to claim 1 or 2, wherein the surface of the wall surface is rougher than the surface of a portion other than the bottom. 前記環状部位の前記壁面に対して前記反対側の方向に存在する部分の表面が前記底部以外の部位の表面よりも粗い請求項３に記載の燃焼室。 The combustion chamber according to claim 3, wherein the surface of the portion of the annular portion existing in the direction opposite to the wall surface is rougher than the surface of the portion other than the bottom portion. 前記環状部位に複数の凹みを前記流方向に間隔を空けて配置し、前記壁面が前記流方向に隣り合う前記凹みどうしの間の凸部位で構成される請求項１〜４のいずれか１項に記載の燃焼室。 Any one of claims 1 to 4, wherein a plurality of dents are arranged in the annular portion at intervals in the flow direction, and the wall surface is composed of convex portions between the dents adjacent to each other in the flow direction. Combustion chamber described in. 前記凹みは角の無い形状を成す請求項５に記載の燃焼室。 The combustion chamber according to claim 5, wherein the recess has a shape without corners. 前記環状部位の環周方向の全周に渡って延在して前記環状部位に配置された全ての前記壁面と前記凹みとを横断する線分で前記環状部位を切断した場合の切断面に現れる前記環状部位の表面形状は波形状を成す請求項５または６に記載の燃焼室。 Appears on the cut surface when the annular portion is cut by a line segment extending over the entire circumference of the annular portion in the circumferential direction and crossing all the wall surfaces arranged in the annular portion and the recess. The combustion chamber according to claim 5 or 6, wherein the surface shape of the annular portion has a wavy shape.
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Publication number Priority date Publication date Assignee Title
CN117418931A (en) * 2023-12-18 2024-01-19 潍柴动力股份有限公司 Combustion chamber and diesel engine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117418931A (en) * 2023-12-18 2024-01-19 潍柴动力股份有限公司 Combustion chamber and diesel engine
CN117418931B (en) * 2023-12-18 2024-03-19 潍柴动力股份有限公司 Combustion chamber and diesel engine

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