JP4608109B2 - Engine exhaust system - Google Patents

Engine exhaust system Download PDF

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Publication number
JP4608109B2
JP4608109B2 JP2001008728A JP2001008728A JP4608109B2 JP 4608109 B2 JP4608109 B2 JP 4608109B2 JP 2001008728 A JP2001008728 A JP 2001008728A JP 2001008728 A JP2001008728 A JP 2001008728A JP 4608109 B2 JP4608109 B2 JP 4608109B2
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Prior art keywords
exhaust
pipe
engine
cross
bent portion
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JP2001008728A
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JP2002213239A (en
Inventor
孝彦 内藤
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Sankei Giken Kogyo Co Ltd
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Sankei Giken Kogyo Co Ltd
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Priority to JP2001008728A priority Critical patent/JP4608109B2/en
Priority to GB0428079A priority patent/GB2409238B/en
Priority to GB0121362A priority patent/GB2371334B/en
Priority to DE2002100669 priority patent/DE10200669A1/en
Publication of JP2002213239A publication Critical patent/JP2002213239A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/003—Silencing apparatus characterised by method of silencing by using dead chambers communicating with gas flow passages
    • F01N1/006—Silencing apparatus characterised by method of silencing by using dead chambers communicating with gas flow passages comprising at least one perforated tube extending from inlet to outlet of the silencer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2470/00—Structure or shape of gas passages, pipes or tubes
    • F01N2470/10—Tubes having non-circular cross section
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2470/00—Structure or shape of gas passages, pipes or tubes
    • F01N2470/20—Dimensional characteristics of tubes, e.g. length, diameter

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Silencers (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば自動車等のエンジンの排気系に関する。更に詳しくは、排気系を構成する管路の途中に略Ｕ字状の屈曲部を有する排気系に関する。
【０００２】
【従来の技術】
従来、上記のようなエンジンの排気系において、該排気系を構成する管路の途中に略Ｕ字状の屈曲部を設けたものは知られている。例えば横置式エンジンの前側気筒からの排気管と、後側気筒からの排気管とをエンジンの下側で合流させる場合には、上記後側気筒からの排気管をエンジンの下側で前向きに湾曲させたのちＵ字状に屈曲させて前側気筒からの排気管と合流させている。また例えばマフラ内に配設される排気流通管等において、所定の消音機能を発揮させるのに必要な管路長を確保するために、上記流通管等をマフラ内でＵ字状に屈曲させる場合がある。
【０００３】
上記のようなＵ字状屈曲部の内空横断面積は通常その近傍の管路をも含めて略一定に形成されており、また上記のような管路は最大排気流量および消音特性等を勘案して必要最小限の大きさに形成されている。そのため、上記屈曲部では排気の流れが悪く、それが抵抗となってエンジンに背圧が掛かり、エンジン性能やエンジン出力が低下する等の不具合がある。
【０００４】
そこで、上記屈曲部での抵抗を軽減させるために、上記管路全体の内空横断面積を大きくすることが考えられるが、そのようにすると往々にして排気流に乱れや渦流が生じるため必ずしも流通抵抗を少なくすることができないだけでなく、消音性能の低下および材料コストや重量が増大する等の不具合がある。
【０００５】
【発明が解決しようとする課題】
本発明は上記の問題点に鑑みて提案したもので、上記のような排気系を構成する管路の途中にＵ字状の屈曲部を有するものにあっても排気流の流通抵抗を極力小さくすることのできるエンジンの排気系を提供することを目的とする。
【０００６】
【課題を解決するための手段】
上記の目的を達成するために本発明によるエンジンの排気系は、以下の構成としたものである。
【０００７】
即ち、本発明のエンジンの排気系は、排気系を構成する管路の途中に管材を設け、前記管材を、一つの部材で形成され断面視形状が一連で連続し、その途中に略Ｕ字状の屈曲部が形成されるものとし、前記屈曲部の頂部付近の内空横断面積を前記管材の最小内空横断面積の１．３倍以上となるようにして、前記屈曲部を漸次なだらかな曲面に形成することを特徴とする。また、本発明のエンジンの排気系は、前記管材を、自動車の横置式エンジンの後側気筒からの排気管とし、前記後側気筒からの排気管の下流側の直管状部分を断面略半円形に形成し、前記横置式エンジンの前側気筒からの排気管の下流側部分を、前記後側気筒からの排気管と対称形状の断面略半円形に形成し、前記後側気筒からの排気管の断面略半円形の部分と前記前側気筒からの排気管の断面略半円形の部分とを集合部で合流することを特徴とする。また、本発明のエンジンの排気系は、前記管材を、自動車のマフラ内に配置される排気流通管とし、前記排気流通管を複数設け、前記マフラの本体内を区画する仕切板に前記複数の排気流通管の直管状部分を貫通して配置し、前記複数の排気流通管の直管状部分を前記仕切板の貫通部において互いに嵌合接続することを特徴とする。
【０００８】
【発明の実施の形態】
以下、本発明を図に示す実施形態に基づいて具体的に説明する。図１は本発明によるエンジンの排気系の一実施形態を示す斜視図、図２はその一部の平面図および要部の断面図である。
【０００９】
本実施形態は横置式エンジンの前側気筒からの排気管１と、後側気筒からの排気管２とをエンジンの下側で合流させるために後側気筒からの排気管２に形成したＵ字状の屈曲部に適用したものである。上記各排気管１，２は、その各一端部１ａ，２ａに設けたフランジ継手３，４を介して図に省略したエンジンの前側気筒および後側気筒の排気マニホールドにそれぞれ接続されている。
【００１０】
後側気筒からの排気管２は、図に省略したエンジンの下側で前向きに湾曲したのちＵ字状に屈曲して前側気筒からの排気管１の後端部１ｂと集合部５で合流するように構成され、その集合部５で合流した排気は、引き続き触媒コンバータを経て車体後部のマフラに導かれる構成であるが図には省略した。
【００１１】
上記排気管２のＵ字状屈曲部２ｃおよびその両側の直管状部分２ｂ，２ｄは、図２（ｂ）〜（ｄ）に示すようにそれぞれ断面略円形に形成され、上記Ｕ字状の屈曲部２ｃは、その頂部（図の場合は図２（ａ）のｃ−ｃ切断部）付近の内空横断面積が、そのＵ字状屈曲部を有する管路の最小内空横断面積の１．３倍以上になるように漸次なだらかな曲面に形成されている。特に、本実施形態においては上記排気管２のＵ字状屈曲部２ｃよりも上流側の直管状部分２ｂの内空横断面積が最も小さく形成されており、屈曲部２ｃの頂部はその最小内空横断面積の１．３倍以上に形成されている。
【００１２】
上記のように形成すると、排気流に乱れや渦流等が殆ど生じることなく、排気の流通抵抗を極力小さくすることが可能となり、エンジンに背圧が掛かってエンジン出力が低下するのを防止することができる。
【００１３】
なお上記実施形態においては、排気管２のＵ字状屈曲部２ｃおよびその両側の直管状部分２ｂ，２ｄの断面形状を略円形に形成したが、必ずしも円形である必要はなく、例えば上記排気管２の近傍に配設される他部品との干渉をさけるために図３（ｃ）のように異形断面に形成してもよく、また排気管２の下流側の直管状部分２ｄの断面形状を図３（ｄ）に示すように略半円形に形成し、それと合流する排気管１の下流側部分を上記と対称の略半円形状に形成すると前記の集合部を簡素化することができる。
【００１４】
次に、図４および図５は本発明による他の実施形態を示すもので、マフラ内にＵ字状に屈曲させて配置した排気流通管に適用したものである。上記のマフラは外筒１１の両端部を端板１２，１３で閉塞してなるマフラ本体１０内を仕切板１４，１５によって２つの膨張室１６，１７と１つの共鳴室１８とに区画した構成であり、その仕切板１４，１５を貫通し且つ上記３つの室１６〜１８内を往復するようにして２つのＵ字状の屈曲部２１ｂ，２２ｂとを有する排気流通管２０が設けられている。
【００１５】
その排気流通管２０は、本実施形態においては２つの管材２１，２２で構成され、その各管材２１，２２には、それぞれ上記のＵ字状の屈曲部２１ｂ，２２ｂを設けると共に、その各Ｕ字状屈曲部２１ｂ，２２ｂに連通する直管状部分２１ａ，２１ｃ、２２ａ、２２ｃが設けられ、管材２１の直管状部分２１ｃと管材２２の直管状部分２２ａとは前記仕切板１４の貫通部において互いに嵌合接続されている。
【００１６】
上記の各Ｕ字状屈曲部２１ｂ，２２ｂは、その各頂部の内空横断面積が、その管路すなわち排気流通管２０の最小内空横断面積の１．３倍以上になるように漸次なだらかな曲面に形成されている。特に図の場合は上記各直管状部分２１ａ、２１ｃ、２２ａ、２２ｃの内空横断面積は略同じ大きさに形成されており、上記屈曲部２１ｂ，２２ｂの各頂部の内空横断面積は上記各直管状部分２１ａ、２１ｃ、２２ａ、２２ｃの内空横断面積の１．３倍以上に形成されている。なお図５（ｂ）〜（ｄ）は上記管材２１の直管状部分２１ａ，２１ｃおよびＵ字状屈曲部２１ｂのみを示したが、管材２２の直管状部分２２ａ、２２ｃおよび屈曲部２２ｂも同様に構成されている。
【００１７】
図中、３０は排気導入管で、その下流側端部は端板３１で閉塞され、その端板３１の近傍に形成した貫通孔３２によって排気導入管３０内と共鳴室１８内とが連通して上記貫通孔３２の開口面積と共鳴室１８の容積等によって決定される所定周波数の排気騒音が共鳴作用によって消音される。
【００１８】
また排気導入管３０の長手方向中央部には、該導入管３０によってマフラ本体１０内に導かれた排気を膨張室１７内に導入する排気導入孔３３が設けられ、その導入孔３３から膨張室１７内に導入された排気は、連通管４０を介して膨張室１６に導入されて膨張収縮を繰り返したのち前記排気流通管２０に導かれる。
【００１９】
その排気流通管２０は、上記のように直管状部分２１ａ，２１ｃ、２２ａ、２２ｃとＵ字状屈曲部２１ｂ，２２ｂとで構成され、その屈曲部２１ｂ，２２ｂを、その頂部の内空横断面積が、その管路すなわち排気流通管２０の最小内空横断面積の１．３倍以上になるように漸次なだらかな曲面に形成したことによって、排気をスムーズに流通させることが可能となり、エンジンに背圧が掛かって出力が低下するのを良好に防止することができるものである。
【００２０】
なお、上記実施形態は、２つのＵ字状の屈曲部２１ｂ，２２ｂを有する排気流通管２０に適用したが、上記屈曲部の数は適宜であり、また上記屈曲部および直管状部分の断面形状も適宜変更可能である。また上記実施形態は排気流通管２０を２つの管材２１，２２で構成したが、１つ若しくは２つ以上の管材で構成したものにも適用できる。
【００２１】
【実施例】
前記図１および図２に示すような排気系において、Ｕ字状屈曲部２ｃの頂部の内空横断面積が、その排気系の最小内空横断面積の約１．３倍となるように上記屈曲部２ｃをなだらかな曲面に形成して排気の流通性能を調べたところ、以下のような結果が得られた。
【００２２】
即ち、図６は上記の排気系に空気を供給したときの供給圧力と流量との関係を示すもので、図中Ａは本発明による上記実施例の場合、Ｂは上記実施例と同径でＵ字状屈曲部を有しない直管を用いた場合、ＣはＵ字状の屈曲部を直管部分と同径にした場合である。
【００２３】
上記の図からも明らかなように、本発明によるＵ字状屈曲部の頂部付近の内空横断面積を、その管路の最小内空横断面積の１．３倍になるように漸次なだらかな曲面に形成した上記Ａの排気系は、Ｕ字状の屈曲部を直管部分と同径にした上記Ｃの排気系に比べ、排気の流通抵抗が小さく、エンジンに背圧が掛かってエンジン出力が低下するようなおそれがないことが分かった。また１．３倍以上にすれば更に流通抵抗を少なくできることは、上記の結果からも明らかであるが、あまり大きくすると屈曲部の体積が増大して嵩張るので適宜の大きさに設定すればよい。
【００２４】
【発明の効果】
以上のように本発明によるエンジンの排気系は、上記のように排気系を構成する管路の途中に設けられた略Ｕ字状屈曲部の頂部付近の内空横断面積が、そのＵ字状屈曲部を有する管路の最小内空横断面積の１．３倍以上になるように漸次なだらかな曲面に形成するだけの極めて簡単な構成により、上記屈曲部で排気流に乱れや渦流等が殆ど生じることなく、流通抵抗を極力小さくすることが可能となり、エンジンに背圧が掛かって出力が低下するのを良好に防止できる。又その際、上記屈曲部の両側の略直管状部分の内空横断面積は必要最小限の大きさでよいから、前記従来のように直管状部分を含めて屈曲部全体を大径に形成した場合に比べ、材料コストや重量を低減できると共に、車体底部やマフラ内の狭い配置スペースでも良好に配置できる等の効果がある。
【図面の簡単な説明】
【図１】本発明によるエンジンの排気系の一実施形態を示す斜視図。
【図２】（ａ）はその一部の平面図。
（ｂ）〜（ｄ）は（ａ）におけるｂ−ｂ、ｃ−ｃ、ｄ−ｄ線断面図。
【図３】（ａ）は断面形状を変更した一部の平面図。
（ｂ）〜（ｄ）は（ａ）におけるｂ−ｂ、ｃ−ｃ、ｄ−ｄ線断面図。
【図４】本発明によるエンジンの排気系の他の実施形態を示す横断平面図。
【図５】上記排気系の一部の拡大平面図。
【図６】本発明による排気系を用いて排気の流通抵抗を調べた結果を示すグラフ。
【符号の説明】
１、２ 排気管
２ｂ，２ｄ 直管状部分
２ｃ 屈曲部
３、４ フランジ継手
１０ マフラ本体
１１ 外筒
１２、１３ 端板
１４、１５ 仕切板
１６、１７ 膨張室
１８ 共鳴室
２０ 排気流通管
２１、２２ 管材
２１ａ、２１ｃ、２２ａ、２２ｃ 直管状部分
２１ｂ、２２ｂ 屈曲部
３０ 排気導入管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust system of an engine such as an automobile. More specifically, the present invention relates to an exhaust system having a substantially U-shaped bent portion in the middle of a pipeline constituting the exhaust system.
[0002]
[Prior art]
Conventionally, in the engine exhaust system as described above, a substantially U-shaped bent portion is provided in the middle of a pipe line constituting the exhaust system. For example, when the exhaust pipe from the front cylinder of the horizontal engine and the exhaust pipe from the rear cylinder are joined at the lower side of the engine, the exhaust pipe from the rear cylinder is bent forward at the lower side of the engine. Then, it is bent into a U shape and joined with the exhaust pipe from the front cylinder. In addition, for example, in an exhaust flow pipe disposed in a muffler, in order to secure a pipe length necessary for exhibiting a predetermined silencing function, the flow pipe is bent in a U shape in the muffler. There is.
[0003]
The inner space crossing area of the U-shaped bent part as described above is generally formed to be substantially constant including the pipe line in the vicinity of the U-shaped bent part, and the above pipe line takes into consideration the maximum exhaust flow rate and the silencing characteristics. And it is formed in the minimum necessary size. For this reason, the flow of exhaust gas is poor at the bent portion, which causes resistance, which causes a back pressure on the engine, resulting in a decrease in engine performance and engine output.
[0004]
Therefore, in order to reduce the resistance at the bent portion, it is conceivable to increase the cross-sectional area of the entire inside of the pipe line. However, since this often causes turbulence and vortex flow in the exhaust flow, it is not always necessary to circulate. Not only can the resistance not be reduced, but there are problems such as a decrease in the silencing performance and an increase in material cost and weight.
[0005]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above problems, and the flow resistance of the exhaust flow is made as small as possible even in the case where a U-shaped bent portion is provided in the middle of the pipeline constituting the exhaust system as described above. It is an object of the present invention to provide an exhaust system for an engine that can be used.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an engine exhaust system according to the present invention has the following configuration.
[0007]
That is, the exhaust system of the engine of the present invention is provided with a pipe material in the middle of a pipe line constituting the exhaust system , the pipe material is formed of one member, and the cross-sectional shape is continuous in series. A bent portion is formed , and the bent portion is gradually and gently formed so that the inner space cross-sectional area near the top of the bent portion is 1.3 times or more the minimum inner air cross-sectional area of the tube material. It is formed in a curved surface. In the exhaust system of the engine of the present invention, the pipe material is an exhaust pipe from a rear cylinder of a horizontal engine of an automobile, and a straight tubular portion downstream of the exhaust pipe from the rear cylinder is substantially semicircular in cross section. The downstream portion of the exhaust pipe from the front cylinder of the horizontal engine is formed into a substantially semicircular cross section symmetrical to the exhaust pipe from the rear cylinder, and the exhaust pipe from the rear cylinder A portion having a substantially semicircular cross section and a portion having a substantially semicircular cross section of the exhaust pipe from the front cylinder are joined together at a collecting portion. In the exhaust system of the engine of the present invention, the pipe material is an exhaust flow pipe disposed in a muffler of an automobile, and a plurality of the exhaust flow pipes are provided. A straight tubular portion of the exhaust gas flow pipe is disposed so as to penetrate, and the straight tubular portions of the plurality of exhaust flow pipes are fitted and connected to each other at a through portion of the partition plate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described based on embodiments shown in the drawings. FIG. 1 is a perspective view showing an embodiment of an exhaust system of an engine according to the present invention, and FIG. 2 is a plan view of a part thereof and a cross-sectional view of a main part thereof.
[0009]
In the present embodiment, a U-shape formed in the exhaust pipe 2 from the rear cylinder to join the exhaust pipe 1 from the front cylinder of the horizontal engine and the exhaust pipe 2 from the rear cylinder below the engine. This is applied to the bent portion. The exhaust pipes 1 and 2 are connected to the exhaust manifolds of the front cylinder and the rear cylinder of the engine, which are not shown in the drawing, via flange joints 3 and 4 provided at the respective end portions 1a and 2a.
[0010]
The exhaust pipe 2 from the rear cylinder is bent forward at the lower side of the engine (not shown) and then bent into a U shape so as to join the rear end portion 1b of the exhaust pipe 1 from the front cylinder and the collecting portion 5. The exhaust gas that has been configured as described above and that has joined at the collecting portion 5 continues to be guided to the muffler at the rear of the vehicle body through the catalytic converter, but is not shown in the drawing.
[0011]
The U-shaped bent portion 2c of the exhaust pipe 2 and the straight tubular portions 2b and 2d on both sides thereof are formed in a substantially circular cross section as shown in FIGS. 2 (b) to 2 (d), and the U-shaped bent portion is formed. In the portion 2c, the inner space cross-sectional area near the top (in the figure, the cc cutting portion in FIG. 2 (a)) is the minimum inner space cross-section of the pipe having the U-shaped bent portion. It is formed into a gently-sloping curved surface so as to be three times or more. In particular, in the present embodiment, the inner space crossing area of the straight tubular portion 2b upstream of the U-shaped bent portion 2c of the exhaust pipe 2 is formed to be the smallest, and the top of the bent portion 2c is the smallest inner space. It is formed more than 1.3 times the cross-sectional area.
[0012]
When formed as described above, it is possible to minimize the flow resistance of the exhaust as much as possible without causing turbulence or vortex in the exhaust flow, and to prevent the engine output from being reduced due to back pressure applied to the engine. Can do.
[0013]
In the above embodiment, the cross-sectional shape of the U-shaped bent portion 2c of the exhaust pipe 2 and the straight tubular portions 2b, 2d on both sides thereof is formed in a substantially circular shape, but is not necessarily circular, for example, the exhaust pipe In order to avoid interference with other parts arranged in the vicinity of 2, the cross-sectional shape of the straight tubular portion 2 d on the downstream side of the exhaust pipe 2 may be formed as shown in FIG. As shown in FIG. 3 (d), if the downstream portion of the exhaust pipe 1 that joins it is formed in a substantially semicircular shape symmetrical to the above, the above-mentioned collecting portion can be simplified.
[0014]
Next, FIGS. 4 and 5 show another embodiment according to the present invention, which is applied to an exhaust gas flow pipe arranged in a U-shape in a muffler. The muffler has a configuration in which the inside of the muffler main body 10 formed by closing both ends of the outer cylinder 11 with end plates 12 and 13 is divided into two expansion chambers 16 and 17 and one resonance chamber 18 by partition plates 14 and 15. An exhaust gas distribution pipe 20 having two U-shaped bent portions 21b and 22b is provided so as to penetrate the partition plates 14 and 15 and reciprocate in the three chambers 16 to 18. .
[0015]
In the present embodiment, the exhaust flow pipe 20 is composed of two pipe materials 21 and 22, and the pipe materials 21 and 22 are provided with the U-shaped bent portions 21 b and 22 b, respectively. Straight tubular portions 21 a, 21 c, 22 a, 22 c communicating with the character-shaped bent portions 21 b, 22 b are provided, and the straight tubular portion 21 c of the tubular material 21 and the straight tubular portion 22 a of the tubular material 22 are mutually connected in the penetrating portion of the partition plate 14. Mated and connected.
[0016]
Each of the U-shaped bent portions 21b and 22b is gradually gentle so that the inner air cross-sectional area of each top portion is 1.3 times or more the minimum inner air cross-sectional area of the pipe line, that is, the exhaust flow pipe 20. It is formed on a curved surface. Particularly, in the case of the figure, the inner space cross-sectional areas of the straight tubular portions 21a, 21c, 22a, and 22c are formed to have substantially the same size, and the inner air cross-sectional areas of the top portions of the bent portions 21b and 22b are The straight tubular portions 21a, 21c, 22a, and 22c are formed to be 1.3 times or more the inner space cross-sectional area. 5B to 5D show only the straight tubular portions 21a and 21c and the U-shaped bent portion 21b of the tube material 21, the straight tubular portions 22a and 22c and the bent portion 22b of the tube material 22 are similarly formed. It is configured.
[0017]
In the drawing, reference numeral 30 denotes an exhaust introduction pipe, and its downstream end is closed by an end plate 31, and the inside of the exhaust introduction pipe 30 communicates with the inside of the resonance chamber 18 through a through hole 32 formed in the vicinity of the end plate 31. Thus, exhaust noise of a predetermined frequency determined by the opening area of the through hole 32 and the volume of the resonance chamber 18 is silenced by the resonance action.
[0018]
Further, an exhaust introduction hole 33 for introducing the exhaust gas introduced into the muffler main body 10 by the introduction pipe 30 into the expansion chamber 17 is provided at the central portion in the longitudinal direction of the exhaust introduction pipe 30. The exhaust gas introduced into 17 is introduced into the expansion chamber 16 through the communication pipe 40 and is repeatedly expanded and contracted, and then guided to the exhaust flow pipe 20.
[0019]
The exhaust flow pipe 20 is composed of the straight tubular portions 21a, 21c, 22a, 22c and the U-shaped bent portions 21b, 22b as described above, and the bent portions 21b, 22b are arranged in the inner space crossing area of the top portion. However, by forming the curved surface gradually and gently so as to be 1.3 times or more of the minimum inner-air cross-sectional area of the pipe, that is, the exhaust gas distribution pipe 20, it becomes possible to smoothly distribute the exhaust gas and It is possible to satisfactorily prevent the output from being lowered due to the pressure.
[0020]
In addition, although the said embodiment was applied to the exhaust flow pipe 20 which has two U-shaped bending parts 21b and 22b, the number of the said bending parts is appropriate, and the cross-sectional shape of the said bending part and a straight tubular part Can be changed as appropriate. Moreover, although the said embodiment comprised the exhaust flow pipe 20 by the two pipe materials 21 and 22, it is applicable also to what was comprised by one or two or more pipe materials.
[0021]
【Example】
In the exhaust system as shown in FIGS. 1 and 2, the bent portion is formed so that the inner space crossing area at the top of the U-shaped bent portion 2c is about 1.3 times the minimum inner space crossing area of the exhaust system. When the part 2c was formed into a gently curved surface and the circulation performance of the exhaust gas was examined, the following results were obtained.
[0022]
That is, FIG. 6 shows the relationship between the supply pressure and the flow rate when air is supplied to the exhaust system, where A is the above embodiment according to the present invention, and B is the same diameter as the above embodiment. When a straight pipe having no U-shaped bent portion is used, C is a case where the U-shaped bent portion has the same diameter as the straight pipe portion.
[0023]
As is clear from the above figure, the gently curved surface gradually increases so that the inner space crossing area near the top of the U-shaped bent portion according to the present invention is 1.3 times the minimum inner air crossing area of the pipe. The exhaust system of A formed in the above has a smaller exhaust flow resistance than the exhaust system of C having a U-shaped bent part having the same diameter as the straight pipe part, and the engine output is increased by applying back pressure to the engine. It turns out that there is no fear of lowering. In addition, it is clear from the above results that the flow resistance can be further reduced by setting it to 1.3 times or more. However, if the value is too large, the volume of the bent portion increases and becomes bulky.
[0024]
【The invention's effect】
As described above, the exhaust system of the engine according to the present invention has a U-shaped cross-sectional area in the vicinity of the top of the substantially U-shaped bent portion provided in the middle of the pipeline constituting the exhaust system as described above. Due to the extremely simple configuration that only forms a gradually curved surface so as to be 1.3 times or more of the minimum inner-air cross-sectional area of a pipe having a bent portion, the bent portion has almost no turbulence or vortex flow in the exhaust flow. It is possible to reduce the flow resistance as much as possible without causing it, and it is possible to satisfactorily prevent the output from being lowered due to the back pressure applied to the engine. Further, at that time, since the inner space crossing area of the substantially straight tubular portion on both sides of the bent portion may be the minimum necessary size, the entire bent portion including the straight tubular portion is formed to have a large diameter as in the conventional case. Compared with the case, the material cost and weight can be reduced, and there are effects such as good arrangement even in a narrow arrangement space in the bottom of the vehicle body or the muffler.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of an exhaust system of an engine according to the present invention.
FIG. 2A is a plan view of a part thereof.
(B)-(d) is the bb, cc, dd sectional view taken on the line in (a).
FIG. 3A is a plan view of a part in which a cross-sectional shape is changed.
(B)-(d) is the bb, cc, dd sectional view taken on the line in (a).
FIG. 4 is a cross-sectional plan view showing another embodiment of the exhaust system of the engine according to the present invention.
FIG. 5 is an enlarged plan view of a part of the exhaust system.
FIG. 6 is a graph showing the results of examining exhaust flow resistance using an exhaust system according to the present invention.
[Explanation of symbols]
1, 2 Exhaust pipes 2b, 2d Straight tubular portion 2c Bending part 3, 4 Flange joint 10 Muffler body 11 Outer cylinder 12, 13 End plate 14, 15 Partition plate 16, 17 Expansion chamber 18 Resonance chamber 20 Exhaust flow pipes 21, 22 Tubes 21a, 21c, 22a, 22c Straight tubular portions 21b, 22b Bent portion 30 Exhaust pipe

Claims (3)

排気系を構成する管路の途中に管材を設け、
前記管材を、一つの部材で形成され断面視形状が一連で連続し、その途中に略Ｕ字状の屈曲部が形成されるものとし、
前記屈曲部の頂部付近の内空横断面積を前記管材の最小内空横断面積の１．３倍以上となるようにして、前記屈曲部を漸次なだらかな曲面に形成することを特徴とするエンジンの排気系。A pipe material is provided in the middle of the pipe line constituting the exhaust system ,
The tube material is formed of one member, and the cross-sectional view shape is continuous in series, and a substantially U-shaped bent portion is formed in the middle thereof ,
The engine is characterized in that the bent portion is formed into a gradually curved surface so that the inner air cross-sectional area near the top of the bent portion is 1.3 times or more the minimum inner air cross-sectional area of the pipe material . Exhaust system. 前記管材を、自動車の横置式エンジンの後側気筒からの排気管とし、The pipe material is an exhaust pipe from a rear cylinder of a horizontal engine of an automobile,
前記後側気筒からの排気管の下流側の直管状部分を断面略半円形に形成し、A straight tubular portion downstream of the exhaust pipe from the rear cylinder is formed in a substantially semicircular cross section,
前記横置式エンジンの前側気筒からの排気管の下流側部分を、前記後側気筒からの排気管と対称形状の断面略半円形に形成し、The downstream portion of the exhaust pipe from the front cylinder of the horizontal engine is formed in a substantially semicircular cross section symmetrical to the exhaust pipe from the rear cylinder,
前記後側気筒からの排気管の断面略半円形の部分と前記前側気筒からの排気管の断面略半円形の部分とを集合部で合流することを特徴とする請求項１記載のエンジンの排気系。2. The engine exhaust according to claim 1, wherein a substantially semicircular section of the exhaust pipe from the rear cylinder and a substantially semicircular section of the exhaust pipe from the front cylinder merge at a collecting portion. system. 前記管材を、自動車のマフラ内に配置される排気流通管とし、The pipe material is an exhaust circulation pipe disposed in a muffler of an automobile,
前記排気流通管を複数設け、A plurality of the exhaust flow pipes are provided,
前記マフラの本体内を区画する仕切板に前記複数の排気流通管の直管状部分を貫通して配置し、Arranging through the straight tubular portions of the plurality of exhaust flow pipes in a partition plate that divides the inside of the muffler body,
前記複数の排気流通管の直管状部分を前記仕切板の貫通部において互いに嵌合接続することを特徴とする請求項１記載のエンジンの排気系。2. The engine exhaust system according to claim 1, wherein the straight tubular portions of the plurality of exhaust flow pipes are fitted and connected to each other at a through portion of the partition plate.
JP2001008728A 2001-01-17 2001-01-17 Engine exhaust system Expired - Fee Related JP4608109B2 (en)

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JP2001008728A JP4608109B2 (en) 2001-01-17 2001-01-17 Engine exhaust system
GB0428079A GB2409238B (en) 2001-01-17 2001-09-04 Engine exhaust system
GB0121362A GB2371334B (en) 2001-01-17 2001-09-04 Engine exhaust system
DE2002100669 DE10200669A1 (en) 2001-01-17 2002-01-10 Engine Exhaust System

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JP4724611B2 (en) 2006-01-06 2011-07-13 ヤマハ発動機株式会社 Muffler and vehicle with muffler
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JP2013217288A (en) * 2012-04-09 2013-10-24 Toyota Motor Corp Exhaust port structure for internal combustion engine
DE102013010005A1 (en) * 2013-06-14 2014-12-18 Volkswagen Ag Pipe bend and fresh gas train for an internal combustion engine
CN104420962B (en) 2013-09-05 2018-08-28 博萨尔排放控制***公司 Discharge duct
DE102015101980A1 (en) * 2015-02-11 2016-08-11 Tenneco Gmbh Exhaust pipe with deformed portion
CN109899191B (en) * 2019-03-29 2021-04-27 吉林大学 Automobile-used noise reduction air intake manifold subassembly that gives sound insulation based on kangaroo tail

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GB2371334A (en) 2002-07-24
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JP2002213239A (en) 2002-07-31
GB2371334B (en) 2005-08-10

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