WO2019130687A1 - Connection structure of exhaust pipe - Google Patents

Connection structure of exhaust pipe Download PDF

Info

Publication number
WO2019130687A1
WO2019130687A1 PCT/JP2018/035047 JP2018035047W WO2019130687A1 WO 2019130687 A1 WO2019130687 A1 WO 2019130687A1 JP 2018035047 W JP2018035047 W JP 2018035047W WO 2019130687 A1 WO2019130687 A1 WO 2019130687A1
Authority
WO
WIPO (PCT)
Prior art keywords
exhaust pipe
pipe
exhaust
exhaust gas
catalyst
Prior art date
Application number
PCT/JP2018/035047
Other languages
French (fr)
Japanese (ja)
Inventor
輝行 伊藤
亮輔 佐藤
陽 今野
英晃 樋口
サクロン リムパナチャイポーングーン
友和 野村
耕一朗 松下
Original Assignee
本田技研工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 本田技研工業株式会社 filed Critical 本田技研工業株式会社
Publication of WO2019130687A1 publication Critical patent/WO2019130687A1/en

Links

Images

Classifications

    • 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
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus

Definitions

  • the present invention relates to an exhaust pipe connection structure.
  • Priority is claimed on Japanese Patent Application No. 2017-253191, filed Dec. 28, 2017, the content of which is incorporated herein by reference.
  • an object of the present invention is to suppress the deterioration of the catalyst in the connection structure of the exhaust pipe.
  • An exhaust pipe connection structure includes an exhaust pipe body (21) for passing exhaust gas discharged from an internal combustion engine (4), and the exhaust pipe in the flow direction (V1) of the exhaust gas.
  • a connecting pipe (23) for connecting to the pipe (22), and the connecting pipe (23) includes a curved inner surface (30) which is curved radially outward as it goes downstream.
  • the exhaust pipe main body (21) is located at the radial center (C2) of the catalyst storage pipe (22).
  • the curvature (Rc1) of the curved inner surface (30) opposite to the offset direction (V2) of the exhaust pipe main body (21) is disposed offset to the direction orthogonal to the flow direction (V1) of the exhaust gas. ) May be larger than the curvature (Rc2) of the other part.
  • the curvature of the curved inner surface is made larger toward the upstream side of the connecting pipe because the curvature of the curved inner surface is larger toward the downstream side. Peeling can be suppressed.
  • the curvature of the curved inner surface can be made steep to shorten the length of the connecting pipe. Therefore, while suppressing the deterioration of the catalyst, it is possible to suppress the pressure loss in the connection pipe and to suppress the decrease in the output.
  • the exhaust pipe main body includes a bent portion that is concaved inward in the radial direction on the upstream side of the connection portion with the connection pipe, the exhaust gas is connected via the bent portion. It has been found that when the gas flows into the pipe, the flow of the exhaust gas is likely to be separated at a portion on the same side as the bend in the radial direction in the connecting pipe. According to the exhaust pipe connection structure described in (3) of the present invention, the curvature of the curved inner surface on the same side as the bent portion in the radial direction is larger than the curvature of the other portion, so separation of the exhaust gas flow Can be reduced. Therefore, even when the exhaust pipe main body includes the bent portion, the deterioration of the catalyst can be suppressed.
  • the exhaust pipe main body includes a bent portion that is concaved inward in the radial direction on the upstream side with respect to the connection portion with the connecting pipe. It has been found that the flowing exhaust gas is likely to spread on the same side as the bent portion by inertial force when entering the connecting pipe.
  • the exhaust pipe connection structure described in (5) of the present invention the exhaust pipe main body is opposite to the bent portion in the direction orthogonal to the flow direction of the exhaust gas with respect to the radial center of the catalyst storage pipe. By being disposed at an offset, it is possible to equalize the contact of the exhaust gas to the catalyst. Therefore, even when the exhaust pipe main body includes the bent portion, the deterioration of the catalyst can be suppressed.
  • FIG. 1 shows a right side view of an essential part of a motorcycle 1 equipped with an exhaust pipe of a straddle-type vehicle according to the embodiment.
  • the motorcycle 1 is provided with an internal combustion engine 4 (engine) at the lower center of the vehicle between the front wheel 2 and the rear wheel 3.
  • the motorcycle 1 may be simply referred to as a "vehicle”.
  • the internal combustion engine 4 includes a crankcase 5 and a cylinder portion 6 erected upward from the upper front side of the crankcase 5.
  • the front portion of the crankcase 5 is supported by the lower end portion of the down frame 10.
  • the rear of the crankcase 5 is supported by the pivot plate 11.
  • the pivot plate 11 supports a swing arm 12 extending rearward.
  • the front end portion of the swing arm 12 is supported by the pivot plate 11 so as to be vertically swingable. Thereby, the rear wheel 3 at the rear of the swing arm 12 can swing up and down.
  • An intake system member 13 is connected to the rear of the cylinder portion 6.
  • An exhaust pipe 14 is connected to a front portion of the cylinder portion 6.
  • the cylinder portion 6 includes a cylinder block coupled to the crankcase 5, a cylinder head coupled to the cylinder block and having a combustion chamber and the like formed therein, and a head cover covering the cylinder head.
  • the intake system member 13 and the exhaust pipe 14 are coupled to the cylinder head of the cylinder unit 6 and can communicate with the combustion chamber.
  • the upstream end of the connection pipe 23 is connected to the downstream end of the exhaust pipe main body 21.
  • the downstream end of the connection pipe 23 is connected to the upstream end of the catalyst storage pipe 22.
  • Exhaust gas travels from the side of the internal combustion engine 4 to the silencer 15 through the exhaust pipe body 21, the connection pipe 23, the catalyst housing pipe 22, and the connection pipe 24 (see FIG. 1).
  • the exhaust pipe body 21, the connection pipe 23, the catalyst housing pipe 22 and the connection pipe 24 each have an annular shape.
  • the exhaust pipe main body 21 and the catalyst housing pipe 22 are formed of a pipe material having a circular cross section.
  • connection pipe 23 has a so-called trumpet-shaped outer shape which is curved so as to be positioned radially outward as it goes downstream.
  • the connection pipe 23 includes a curved inner surface 30 which is curved while expanding radially outward toward the downstream side.
  • the upstream end of the curved inner surface 30 is continuous with the downstream end of the inner surface of the exhaust pipe main body 21.
  • the downstream end of the curved inner surface 30 is continuous with the upstream end of the inner surface of the catalyst storage tube 22.
  • an angle A1 formed by the tangent L1 of the curved inner surface 30 with respect to the radial direction central axis C1 of the connection pipe 23 (hereinafter, also referred to as “connection pipe axis C1”) is referred to as “inclination angle A1”.
  • an angle A1 formed by a tangent L1 of the curved inner surface 30 with respect to an imaginary line Lf parallel to the connecting pipe axis C1 is an inclination angle A1.
  • the inclination angle A1 is set to an angle of 7 ° or more and 8 ° or less.
  • the curvature Rc1 (hereinafter also referred to as “first curvature Rc1”) on the same side as the inner recess 31 in the radial direction in the curved inner surface 30 is larger than the curvature of the other portion.
  • the first curvature Rc1 is larger than the curvature Rc2 (the curvature on the same side as the inner convex portion 32, hereinafter also referred to as the “second curvature Rc2”) in the curved inner surface 30 in the radial direction opposite to the inner concave portion 31.
  • the exhaust pipe main body 21 is offset from the radial center of the catalyst housing pipe 22 in the direction orthogonal to the flow direction V1 of the exhaust gas. That is, in the direction orthogonal to the flow direction V1 of the exhaust gas, the exhaust pipe main body 21 and the catalyst housing pipe 22 are offset from each other.
  • the exhaust pipe main body 21 is offset from the radial center of the catalyst housing pipe 22 in the direction opposite to the bent portion 31 in a direction orthogonal to the flow direction V1 of the exhaust gas.
  • a symbol C2 indicates a radial central axis of the catalyst housing pipe 22 (hereinafter also referred to as “catalyst housing pipe axis”).
  • the direction in which the exhaust pipe main body 21 is offset with respect to the catalyst housing pipe axis C2 (the direction of the arrow V2 in FIG. 3) is referred to as “offset direction V2”.
  • the exhaust pipe 14X according to the comparative example does not include the curved inner surface 30 (see FIG. 9) according to the embodiment (see FIG. 7).
  • the flow of the exhaust gas is along the extending direction of the exhaust pipe main body 21X. That is, in the comparative example, the flow of exhaust gas is separated from the inner surface of the tapered portion 23X.
  • the flow of the exhaust gas is biased to the radial center in the tapered portion 23X.
  • the contact of the exhaust gas with the catalyst tends to be biased toward the radial center.
  • the flow velocity of the exhaust gas is large at the radial center of the tapered portion 23X.
  • the connecting pipe 23 includes the curved inner surface 30 that is curved while expanding radially outward toward the downstream side, whereby the flow of exhaust gas is less likely to be separated from the curved inner surface 30, and the flow of exhaust gas is curved
  • the contact of the exhaust gas to the catalyst 18 becomes uniform. Therefore, the deterioration of the catalyst 18 can be suppressed.
  • the catalyst 18 (the catalyst housing pipe 22) can be miniaturized.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Silencers (AREA)

Abstract

This connection structure of an exhaust pipe includes an exhaust pipe body (21) for passing exhaust gas discharged from an internal combustion engine (4), a catalyst (18) that is disposed downstream of the exhaust pipe body (21) in the flow direction (V1) of the exhaust gas and purifies the exhaust gas, a catalyst storage pipe (22) for storing the catalyst (18), and a connecting pipe (23) connecting the exhaust pipe body (21) and the catalyst storage pipe (22), wherein the connecting pipe (23) has a curved inner surface (30) that is curved while expanding radially outward toward the downstream side.

Description

排気管の接続構造Exhaust pipe connection structure
　本発明は、排気管の接続構造に関する。
　本願は、２０１７年１２月２８日に、日本に出願された特願２０１７－２５３１９１号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to an exhaust pipe connection structure.
Priority is claimed on Japanese Patent Application No. 2017-253191, filed Dec. 28, 2017, the content of which is incorporated herein by reference.
　従来、自動二輪車の触媒配置構造において、排気管のうち触媒の上流側の部分（シリンダヘッド側の部分）に、触媒に近づくにつれて拡径するテーパ部を形成したものがある（例えば、特許文献１参照）。 Conventionally, in a catalyst arrangement structure of a motorcycle, there is a part on the upstream side of the catalyst (portion on the cylinder head side) of the exhaust pipe formed with a tapered portion which expands in diameter toward the catalyst (for example, Patent Document 1) reference).
日本国特開２００８－１９０５０５号公報Japanese Patent Laid-Open No. 2008-190505
　しかしながら、特許文献１の構造では、テーパ部の内面から排気ガスの流れが剥離しやすいため、排気ガスの流れが偏りやすい。排気ガスの流れが偏ると、触媒への排気ガスの当たりが不均一（局所的）となり、触媒が劣化しやすくなる。 However, in the structure of Patent Document 1, since the flow of the exhaust gas is easily separated from the inner surface of the tapered portion, the flow of the exhaust gas tends to be uneven. When the flow of the exhaust gas is uneven, the contact of the exhaust gas with the catalyst becomes uneven (locally), and the catalyst tends to be deteriorated.
　そこで本発明は、排気管の接続構造において、触媒の劣化を抑制することを目的とする。 Therefore, an object of the present invention is to suppress the deterioration of the catalyst in the connection structure of the exhaust pipe.
　上記課題の解決手段として、本発明の態様は以下の構成を有する。
（１）本発明の態様に係る排気管の接続構造は、内燃機関（４）から排出された排気ガスを通す排気管本体（２１）と、前記排気ガスの流れ方向（Ｖ１）における前記排気管本体（２１）の下流側に配置され、前記排気ガスを浄化する触媒（１８）と、前記触媒（１８）を収容する触媒収容管（２２）と、前記排気管本体（２１）と前記触媒収容管（２２）とを接続する接続管（２３）と、を備え、前記接続管（２３）は、下流側ほど径方向外側に拡径しつつ湾曲する湾曲内面（３０）を備える。 As means for solving the above problems, an aspect of the present invention has the following configuration.
(1) An exhaust pipe connection structure according to an aspect of the present invention includes an exhaust pipe body (21) for passing exhaust gas discharged from an internal combustion engine (4), and the exhaust pipe in the flow direction (V1) of the exhaust gas. A catalyst (18) disposed downstream of the main body (21) for purifying the exhaust gas, a catalyst storage pipe (22) for storing the catalyst (18), the exhaust pipe main body (21), and the catalyst storage A connecting pipe (23) for connecting to the pipe (22), and the connecting pipe (23) includes a curved inner surface (30) which is curved radially outward as it goes downstream.
（２）上記（１）に記載の排気管の接続構造では、前記湾曲内面（３０）の曲率（Ｒｃ）は、下流側ほど大きくてもよい。 (2) In the connection structure of the exhaust pipe according to (1), the curvature (Rc) of the curved inner surface (30) may be larger toward the downstream side.
（３）上記（１）または（２）に記載の排気管の接続構造では、前記排気管本体（２１）は、前記接続管（２３）との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部（３１）を備え、前記湾曲内面（３０）において径方向で前記曲がり部（３１）と同じ側の曲率（Ｒｃ１）は、他の部分の曲率（Ｒｃ２）よりも大きくてもよい。 (3) In the exhaust pipe connection structure according to the above (1) or (2), the exhaust pipe main body (21) is radially inward on the upstream side of the connection portion with the connection pipe (23). It has a bending portion (31) that forms a concave, and the curvature (Rc1) on the same side as the bending portion (31) in the radial direction in the curved inner surface (30) is larger than the curvature (Rc2) of other portions May be
（４）上記（１）から（３）のいずれか一項に記載の排気管の接続構造では、前記排気管本体（２１）は、前記触媒収容管（２２）の径方向中心（Ｃ２）に対して前記排気ガスの流れ方向（Ｖ１）と直交する方向にオフセットして配置され、前記湾曲内面（３０）において前記排気管本体（２１）のオフセット方向（Ｖ２）とは反対側の曲率（Ｒｃ１）は、他の部分の曲率（Ｒｃ２）よりも大きくてもよい。 (4) In the exhaust pipe connection structure according to any one of the above (1) to (3), the exhaust pipe main body (21) is located at the radial center (C2) of the catalyst storage pipe (22). The curvature (Rc1) of the curved inner surface (30) opposite to the offset direction (V2) of the exhaust pipe main body (21) is disposed offset to the direction orthogonal to the flow direction (V1) of the exhaust gas. ) May be larger than the curvature (Rc2) of the other part.
（５）上記（１）から（４）のいずれか一項に記載の排気管の接続構造では、前記排気管本体（２１）は、前記接続管（２３）との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部（３１）を備え、前記排気管本体（２１）は、前記触媒収容管（２２）の径方向中心（Ｃ２）に対して前記排気ガスの流れ方向（Ｖ１）と直交する方向で、前記曲がり部（３１）と反対方向にオフセットして配置されてもよい。 (5) In the exhaust pipe connection structure according to any one of the above (1) to (4), the exhaust pipe main body (21) is upstream of the connection portion with the connection pipe (23). Of the exhaust pipe body (21) with respect to the radial center (C2) of the catalyst storage pipe (22) and the flow direction of the exhaust gas It may be arranged to be offset in the direction opposite to the bent portion (31) in the direction orthogonal to (V1).
　本発明の上記（１）に記載の排気管の接続構造によれば、接続管が下流側ほど径方向外側に拡径しつつ湾曲する湾曲内面を備えることで、以下の効果を奏する。湾曲内面から排気ガスの流れが剥離しにくく、排気ガスの流れが湾曲内面に沿って拡散することにより、触媒への排気ガスの当たりが均一となる。したがって、触媒の劣化を抑制することができる。加えて、触媒の劣化を抑制することで、触媒の小型化を図ることができる。 According to the connection structure of the exhaust pipe according to (1) of the present invention, the following effect is exerted by providing the curved inner surface which is curved while expanding radially outward toward the downstream side. It is difficult for the flow of exhaust gas to separate from the curved inner surface, and the flow of the exhaust gas diffuses along the curved inner surface, so that the contact of the exhaust gas with the catalyst becomes uniform. Therefore, deterioration of the catalyst can be suppressed. In addition, the catalyst can be miniaturized by suppressing the deterioration of the catalyst.
　本発明の上記（２）に記載の排気管の接続構造によれば、湾曲内面の曲率が下流側ほど大きいことで、接続管の上流側では湾曲内面の曲率を緩やかにして排気ガスの流れの剥離を抑えることができる。一方、接続管の下流側では湾曲内面の曲率を急峻にして接続管の長さを短くすることができる。したがって、触媒の劣化を抑制しつつ、接続管内での圧力損失を抑えて出力の低下を抑制することができる。 According to the connection structure of the exhaust pipe according to (2) of the present invention, the curvature of the curved inner surface is made larger toward the upstream side of the connecting pipe because the curvature of the curved inner surface is larger toward the downstream side. Peeling can be suppressed. On the other hand, on the downstream side of the connecting pipe, the curvature of the curved inner surface can be made steep to shorten the length of the connecting pipe. Therefore, while suppressing the deterioration of the catalyst, it is possible to suppress the pressure loss in the connection pipe and to suppress the decrease in the output.
　本発明者は鋭意検討の結果、排気管本体が接続管との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部を備える場合、排気ガスが曲がり部を経由して接続管に流入すると、接続管内において径方向で曲がり部と同じ側の部分で排気ガスの流れが剥離しやすいことを見出した。本発明の上記（３）に記載の排気管の接続構造によれば、湾曲内面において径方向で曲がり部と同じ側の曲率が他の部分の曲率よりも大きいことで、排気ガスの流れの剥離を抑えることができる。したがって、排気管本体が曲がり部を備える場合であっても、触媒の劣化を抑制することができる。 As a result of intensive investigations by the inventor of the present invention, in the case where the exhaust pipe main body includes a bent portion that is concaved inward in the radial direction on the upstream side of the connection portion with the connection pipe, the exhaust gas is connected via the bent portion. It has been found that when the gas flows into the pipe, the flow of the exhaust gas is likely to be separated at a portion on the same side as the bend in the radial direction in the connecting pipe. According to the exhaust pipe connection structure described in (3) of the present invention, the curvature of the curved inner surface on the same side as the bent portion in the radial direction is larger than the curvature of the other portion, so separation of the exhaust gas flow Can be reduced. Therefore, even when the exhaust pipe main body includes the bent portion, the deterioration of the catalyst can be suppressed.
　本発明者は鋭意検討の結果、排気管本体が触媒の径方向中心に対して排気ガスの流れ方向と直交する方向にオフセットして配置されている場合、排気ガスがオフセットした排気管本体を経由して接続管に流入すると、接続管内において排気管本体のオフセット方向とは反対側の部分で排気ガスの流れが剥離しやすいことを見出した。本発明の上記（４）に記載の排気管の接続構造によれば、湾曲内面において排気管本体のオフセット方向とは反対側の曲率が他の部分の曲率よりも大きいことで、排気ガスの流れの剥離を抑えることができる。したがって、排気管本体が触媒収容管の径方向中心に対してオフセットして配置されている場合であっても、触媒の劣化を抑制することができる。 As a result of intensive investigations, the inventor of the present invention has found that, when the exhaust pipe main body is disposed offset with respect to the radial direction center of the catalyst in the direction orthogonal to the flow direction of the exhaust gas, the exhaust gas is offset. It has been found that when the gas flows into the connecting pipe, the flow of the exhaust gas is likely to be separated at a portion of the connecting pipe opposite to the offset direction of the exhaust pipe body. According to the exhaust pipe connection structure according to (4) of the present invention, the curvature of the curved inner surface on the opposite side to the offset direction of the exhaust pipe main body is larger than the curvature of the other portion. Peeling can be suppressed. Therefore, even when the exhaust pipe main body is disposed offset with respect to the radial center of the catalyst housing pipe, deterioration of the catalyst can be suppressed.
　本発明者は鋭意検討の結果、排気管本体が接続管との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部を備える場合、排気管本体で曲げられつつ下流側へ流れる排気ガスは、接続管へ入ると慣性力で曲がり部と同じ側に広がりやすいことを見出した。本発明の上記（５）に記載の排気管の接続構造によれば、排気管本体は、触媒収容管の径方向中心に対して排気ガスの流れ方向と直交する方向で、曲がり部と反対方向にオフセットして配置されていることで、触媒への排気ガスの当たりを均一化することができる。したがって、排気管本体が曲がり部を備える場合であっても、触媒の劣化を抑制することができる。 As a result of intensive investigations by the inventor of the present invention, in the case where the exhaust pipe main body includes a bent portion that is concaved inward in the radial direction on the upstream side with respect to the connection portion with the connecting pipe, It has been found that the flowing exhaust gas is likely to spread on the same side as the bent portion by inertial force when entering the connecting pipe. According to the exhaust pipe connection structure described in (5) of the present invention, the exhaust pipe main body is opposite to the bent portion in the direction orthogonal to the flow direction of the exhaust gas with respect to the radial center of the catalyst storage pipe. By being disposed at an offset, it is possible to equalize the contact of the exhaust gas to the catalyst. Therefore, even when the exhaust pipe main body includes the bent portion, the deterioration of the catalyst can be suppressed.
実施形態に係る自動二輪車の右側面図である。1 is a right side view of a motorcycle according to an embodiment. 実施形態に係る排気管の接続構造の上面図である。It is a top view of the connection structure of the exhaust pipe which concerns on embodiment. 実施形態に係る排気管の接続構造の右側面図である。It is a right side view of connection structure of an exhaust pipe concerning an embodiment. 実施形態に係る排気管の接続構造を右上方から見た斜視図である。It is the perspective view which looked at the connection structure of the exhaust pipe concerning an embodiment from the upper right. 実施形態に係る接続管の湾曲内面の上面図である。It is a top view of the curved inner surface of the connection pipe concerning an embodiment. 実施形態に係る接続管の湾曲内面の右側面図である。It is a right side view of a curved inner surface of a connecting pipe concerning an embodiment. 比較例に係る排気ガスの流れを示す上面図である。It is a top view which shows the flow of the exhaust gas which concerns on a comparative example. 図７のＶＩＩＩ－ＶＩＩＩ断面を含む図である。FIG. 8 is a view including a VIII-VIII cross section of FIG. 7; 実施形態に係る排気ガスの流れを示す上面図である。It is a top view which shows the flow of the exhaust gas which concerns on embodiment. 図９のＸ－Ｘ断面を含む図である。FIG. 10 is a view including an XX cross section of FIG. 9; 実施形態に係る排気ガスの流れを示す左側面図である。It is a left side view showing the flow of exhaust gas concerning an embodiment. 実施形態の第一変形例に係る排気管の接続構造を右上方から見た斜視図である。It is the perspective view which looked at the connection structure of the exhaust pipe concerning the 1st modification of an embodiment from the upper right. 実施形態の第二変形例に係る排気管の接続構造を右上方から見た斜視図である。It is the perspective view which looked at the connection structure of the exhaust pipe concerning the 2nd modification of an embodiment from the upper right.
　以下、本発明の実施形態について図面を参照して説明する。なお、以下の説明における前後左右等の向きは、特に記載が無ければ以下に説明する車両における向きと同一とする。また以下の説明に用いる図中適所には、車両前方を示す矢印ＦＲ、車両左方を示す矢印ＬＨ、及び車両上方を示す矢印ＵＰが示されている。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, directions such as front, rear, left, and right are the same as the directions in the vehicle described below unless otherwise specified. Further, an arrow FR indicating the front of the vehicle, an arrow LH indicating the left of the vehicle, and an arrow UP indicating the upper of the vehicle are shown at appropriate positions in the drawings used for the following description.
＜車両全体＞
　図１は、実施形態に係る鞍乗型車両の排気管を搭載した自動二輪車１の要部の右側面図を示す。図１を参照し、自動二輪車１は、前輪２と後輪３との間の車両中央下部に内燃機関４（エンジン）を備えている。以下、自動二輪車１を単に「車両」ということがある。 <Whole vehicle>
FIG. 1 shows a right side view of an essential part of a motorcycle 1 equipped with an exhaust pipe of a straddle-type vehicle according to the embodiment. Referring to FIG. 1, the motorcycle 1 is provided with an internal combustion engine 4 (engine) at the lower center of the vehicle between the front wheel 2 and the rear wheel 3. Hereinafter, the motorcycle 1 may be simply referred to as a "vehicle".
　内燃機関４は、クランクケース５と、クランクケース５の上部前側から上方に向けて立設されたシリンダ部６と、を備える。クランクケース５の前部は、ダウンフレーム１０の下端部に支持されている。クランクケース５の後部は、ピボットプレート１１に支持されている。 The internal combustion engine 4 includes a crankcase 5 and a cylinder portion 6 erected upward from the upper front side of the crankcase 5. The front portion of the crankcase 5 is supported by the lower end portion of the down frame 10. The rear of the crankcase 5 is supported by the pivot plate 11.
　自動二輪車１は、複数の鋼材が一体に結合された車体フレーム７を備える。車体フレーム７は、前端に位置するヘッドパイプ８と、ヘッドパイプ８から後方に延びた後、下方に延びるメインフレーム９と、ヘッドパイプ８から下方に延びるダウンフレーム１０と、メインフレーム９の下端部に設けられたピボットプレート１１と、を備える。 The motorcycle 1 includes a vehicle body frame 7 in which a plurality of steel members are integrally coupled. The body frame 7 has a head pipe 8 located at the front end, a main frame 9 extending downward from the head pipe 8 and then extending downward, a down frame 10 extending downward from the head pipe 8, and a lower end of the main frame 9 And a pivot plate 11 provided on the
　ピボットプレート１１には、後方に延びるスイングアーム１２が支持されている。スイングアーム１２の前端部は、ピボットプレート１１に上下方向に揺動可能に支持されている。これにより、スイングアーム１２の後部の後輪３を上下に揺動可能としている。 The pivot plate 11 supports a swing arm 12 extending rearward. The front end portion of the swing arm 12 is supported by the pivot plate 11 so as to be vertically swingable. Thereby, the rear wheel 3 at the rear of the swing arm 12 can swing up and down.
　シリンダ部６の後部には、吸気系部材１３が接続されている。シリンダ部６の前部には排気管１４が接続されている。シリンダ部６は、クランクケース５に結合するシリンダブロックと、シリンダブロックに結合し内部に燃焼室等が形成されるシリンダヘッドと、シリンダヘッドを覆うヘッドカバーと、を備える。吸気系部材１３及び排気管１４は、シリンダ部６のうちのシリンダヘッドに結合し、燃焼室に連通可能となっている。 An intake system member 13 is connected to the rear of the cylinder portion 6. An exhaust pipe 14 is connected to a front portion of the cylinder portion 6. The cylinder portion 6 includes a cylinder block coupled to the crankcase 5, a cylinder head coupled to the cylinder block and having a combustion chamber and the like formed therein, and a head cover covering the cylinder head. The intake system member 13 and the exhaust pipe 14 are coupled to the cylinder head of the cylinder unit 6 and can communicate with the combustion chamber.
　図１の側面視で、排気管１４は、シリンダ部６の前部から前斜め下方に延びてから後斜め下方に湾曲し、クランクケース５の下方で後方に延びている。その後、排気管１４は、後輪３の前端の車幅方向外側の位置で角度を変えて、斜め後上方に湾曲している。排気管１４の後端部には、消音器１５が接続されている。排気管１４におけるクランクケース５の下方で前後方向に延びる部位（触媒収容管）の内部には、触媒１８が収容されている。 In a side view of FIG. 1, the exhaust pipe 14 extends obliquely forward and downward from the front portion of the cylinder portion 6 and then bends obliquely rearward and downward, and extends rearward and below the crankcase 5. Thereafter, the exhaust pipe 14 is curved diagonally upward and backward, changing the angle at a position outside the front end of the rear wheel 3 in the vehicle width direction. A silencer 15 is connected to the rear end of the exhaust pipe 14. A catalyst 18 is accommodated in a portion (catalyst accommodating pipe) of the exhaust pipe 14 which extends in the front-rear direction below the crankcase 5 (catalyst accommodating pipe).
　図１の側面視で、消音器１５は、排気管１４の後端部から斜め後上方に延び、後輪３の車幅方向外側に位置している。すなわち、車両搭載時に、消音器１５は、車幅方向中央に対して車幅方向の一方側にオフセットして配置される。なお、排気管１４と消音器１５とで、自動二輪車１の排気装置Ｅｘが構成される。排気装置Ｅｘは、排気管の接続構造２０を備えている。図１において符号１６，１７は、車体フレーム７により排気装置Ｅｘを支持するためのブラケットをそれぞれ示す。 In the side view of FIG. 1, the silencer 15 extends obliquely rearward and upward from the rear end portion of the exhaust pipe 14 and is located on the outer side in the vehicle width direction of the rear wheel 3. That is, when the vehicle is mounted, the silencer 15 is disposed offset to one side in the vehicle width direction with respect to the center in the vehicle width direction. The exhaust pipe 14 and the silencer 15 constitute an exhaust system Ex of the motorcycle 1. The exhaust system Ex includes an exhaust pipe connection structure 20. In FIG. 1, reference numerals 16 and 17 respectively indicate brackets for supporting the exhaust system Ex by the vehicle body frame 7.
＜排気管の接続構造＞
　図２に示すように、排気管の接続構造２０は、内燃機関４（図１参照）から排出された排気ガスを通す排気管本体２１と、排気ガスの流れ方向Ｖ１における排気管本体２１の下流側に配置され、排気ガスを浄化する触媒１８と、触媒１８を収容する触媒収容管２２と、排気管本体２１と触媒収容管２２とを接続する接続管２３と、触媒収容管２２と消音器１５（図１参照）とを連結する連結管２４と、を備える。 <Connection structure of exhaust pipe>
As shown in FIG. 2, the exhaust pipe connection structure 20 includes an exhaust pipe main body 21 through which exhaust gas discharged from the internal combustion engine 4 (see FIG. 1) passes and a downstream of the exhaust pipe main body 21 in the exhaust gas flow direction V1. The catalyst 18 disposed on the side for purifying exhaust gas, the catalyst storage pipe 22 for storing the catalyst 18, the connection pipe 23 for connecting the exhaust pipe main body 21 and the catalyst storage pipe 22, the catalyst storage pipe 22 and the silencer And (15) (see FIG. 1).
　ここで、排気ガスの流れ方向Ｖ１は、内燃機関４の側から消音器１５の側に向かう方向である（図１参照）。図１に示すように、排気ガスは、シリンダ部６から排気管１４を通って消音器１５に流れ、消音器１５から排出される。以下、排気ガスの流れ方向Ｖ１において、内燃機関４（シリンダ部６との連結部）の側を「上流側」といい、消音器１５の側を「下流側」ということがある。 Here, the flow direction V1 of the exhaust gas is a direction from the side of the internal combustion engine 4 toward the side of the silencer 15 (see FIG. 1). As shown in FIG. 1, the exhaust gas flows from the cylinder portion 6 through the exhaust pipe 14 to the silencer 15 and is discharged from the silencer 15. Hereinafter, in the flow direction V1 of the exhaust gas, the side of the internal combustion engine 4 (the connection portion with the cylinder portion 6) may be referred to as "upstream side" and the side of the silencer 15 may be referred to as "downstream side".
　図２に示すように、接続管２３の上流端は、排気管本体２１の下流端に接続されている。接続管２３の下流端は、触媒収容管２２の上流端に接続されている。排気ガスは、内燃機関４の側から排気管本体２１、接続管２３、触媒収容管２２、連結管２４を通って消音器１５に向かう（図１参照）。排気ガスの流れ方向Ｖ１と直交する断面視で、排気管本体２１、接続管２３、触媒収容管２２および連結管２４は、それぞれ円環状をなしている。例えば、排気管本体２１および触媒収容管２２は、断面円形状のパイプ材により形成されている。 As shown in FIG. 2, the upstream end of the connection pipe 23 is connected to the downstream end of the exhaust pipe main body 21. The downstream end of the connection pipe 23 is connected to the upstream end of the catalyst storage pipe 22. Exhaust gas travels from the side of the internal combustion engine 4 to the silencer 15 through the exhaust pipe body 21, the connection pipe 23, the catalyst housing pipe 22, and the connection pipe 24 (see FIG. 1). In a cross-sectional view orthogonal to the flow direction V1 of the exhaust gas, the exhaust pipe body 21, the connection pipe 23, the catalyst housing pipe 22 and the connection pipe 24 each have an annular shape. For example, the exhaust pipe main body 21 and the catalyst housing pipe 22 are formed of a pipe material having a circular cross section.
　接続管２３は、下流側ほど径方向外側に位置するように湾曲する所謂ラッパ形状の外形を有している。接続管２３は、下流側ほど径方向外側に拡径しつつ湾曲する湾曲内面３０を備える。湾曲内面３０の上流端は、排気管本体２１の内面の下流端に連なっている。湾曲内面３０の下流端は、触媒収容管２２の内面の上流端に連なっている。 The connection pipe 23 has a so-called trumpet-shaped outer shape which is curved so as to be positioned radially outward as it goes downstream. The connection pipe 23 includes a curved inner surface 30 which is curved while expanding radially outward toward the downstream side. The upstream end of the curved inner surface 30 is continuous with the downstream end of the inner surface of the exhaust pipe main body 21. The downstream end of the curved inner surface 30 is continuous with the upstream end of the inner surface of the catalyst storage tube 22.
　図５に示すように、湾曲内面３０の曲率Ｒｃは、下流側ほど大きい。言い換えると、湾曲内面３０は、上流側において緩やかな傾斜を有し、下流側において急峻な傾斜を有している。 As shown in FIG. 5, the curvature Rc of the curved inner surface 30 is larger toward the downstream side. In other words, the curved inner surface 30 has a gentle slope on the upstream side and a steep slope on the downstream side.
　ここで、接続管２３の径方向中心軸線Ｃ１（以下「接続管軸線Ｃ１」ともいう。）に対して湾曲内面３０の接線Ｌ１がなす角度Ａ１を「傾斜角度Ａ１」という。図５においては、接続管軸線Ｃ１と平行な仮想線Ｌｆに対して湾曲内面３０の接線Ｌ１がなす角度Ａ１を傾斜角度Ａ１としている。例えば、傾斜角度Ａ１は、７°以上８°以下の角度に設定されている。これにより、接続管２３内における排気ガスの流れの剥離を抑えつつ、接続管２３内での圧力損失を抑えることができる。 Here, an angle A1 formed by the tangent L1 of the curved inner surface 30 with respect to the radial direction central axis C1 of the connection pipe 23 (hereinafter, also referred to as “connection pipe axis C1”) is referred to as “inclination angle A1”. In FIG. 5, an angle A1 formed by a tangent L1 of the curved inner surface 30 with respect to an imaginary line Lf parallel to the connecting pipe axis C1 is an inclination angle A1. For example, the inclination angle A1 is set to an angle of 7 ° or more and 8 ° or less. Thereby, the pressure loss in the connection pipe 23 can be suppressed while the separation of the flow of the exhaust gas in the connection pipe 23 is suppressed.
　図３に示すように、排気管本体２１は、接続管２３との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部３１（以下「内側凹部３１」ともいう。）と、径方向で内側凹部３１とは反対側にて径方向内側に凸をなして曲がる第二曲がり部３２（以下「内側凸部３２」ともいう。）と、を備える。 As shown in FIG. 3, the exhaust pipe main body 21 has a bent portion 31 (hereinafter, also referred to as “inner concave portion 31”) which is concaved inward in the radial direction on the upstream side of the connection portion with the connection pipe 23. And a second bent portion 32 (hereinafter, also referred to as “inner convex portion 32”) that is bent inward in the radial direction on the opposite side to the inner concave portion 31 in the radial direction.
　湾曲内面３０において径方向で内側凹部３１と同じ側の曲率Ｒｃ１（以下「第一曲率Ｒｃ１」ともいう。）は、他の部分の曲率よりも大きい。第一曲率Ｒｃ１は、湾曲内面３０において径方向で内側凹部３１とは反対側の曲率Ｒｃ２（内側凸部３２と同じ側の曲率、以下「第二曲率Ｒｃ２」ともいう。）よりも大きい。 The curvature Rc1 (hereinafter also referred to as "first curvature Rc1") on the same side as the inner recess 31 in the radial direction in the curved inner surface 30 is larger than the curvature of the other portion. The first curvature Rc1 is larger than the curvature Rc2 (the curvature on the same side as the inner convex portion 32, hereinafter also referred to as the “second curvature Rc2”) in the curved inner surface 30 in the radial direction opposite to the inner concave portion 31.
　排気管本体２１は、触媒収容管２２の径方向中心に対して排気ガスの流れ方向Ｖ１と直交する方向にオフセットして配置されている。すなわち、排気ガスの流れ方向Ｖ１と直交する方向において、排気管本体２１と触媒収容管２２とは互いにずれている。排気管本体２１は、触媒収容管２２の径方向中心に対して排気ガスの流れ方向Ｖ１と直交する方向で、曲がり部３１と反対方向にオフセットして配置されている。図３において符号Ｃ２は、触媒収容管２２の径方向中心軸線（以下「触媒収容管軸線」ともいう。）を示す。以下、触媒収容管軸線Ｃ２に対して排気管本体２１がオフセットする方向（図３中矢印Ｖ２の方向）を「オフセット方向Ｖ２」という。 The exhaust pipe main body 21 is offset from the radial center of the catalyst housing pipe 22 in the direction orthogonal to the flow direction V1 of the exhaust gas. That is, in the direction orthogonal to the flow direction V1 of the exhaust gas, the exhaust pipe main body 21 and the catalyst housing pipe 22 are offset from each other. The exhaust pipe main body 21 is offset from the radial center of the catalyst housing pipe 22 in the direction opposite to the bent portion 31 in a direction orthogonal to the flow direction V1 of the exhaust gas. In FIG. 3, a symbol C2 indicates a radial central axis of the catalyst housing pipe 22 (hereinafter also referred to as “catalyst housing pipe axis”). Hereinafter, the direction in which the exhaust pipe main body 21 is offset with respect to the catalyst housing pipe axis C2 (the direction of the arrow V2 in FIG. 3) is referred to as “offset direction V2”.
　湾曲内面３０において排気管本体２１のオフセット方向Ｖ２とは反対側の曲率（第一曲率Ｒｃ１）は、他の部分の曲率よりも大きい。実施形態では、湾曲内面３０において径方向で内側凹部３１と同じ側と、湾曲内面３０において排気管本体２１のオフセット方向Ｖ２とは反対側と、は径方向で互いに同じ側にある。第一曲率Ｒｃ１は、湾曲内面３０において排気管本体２１のオフセット方向Ｖ２と同じ側の曲率（第二曲率Ｒｃ２）よりも大きい。 The curvature (first curvature Rc1) of the curved inner surface 30 opposite to the offset direction V2 of the exhaust pipe main body 21 is larger than the curvature of the other portion. In the embodiment, the same side as the inner recess 31 in the radial direction in the curved inner surface 30 and the side opposite to the offset direction V2 of the exhaust pipe main body 21 in the curved inner surface 30 are on the same side in the radial direction. The first curvature Rc1 is larger than the curvature (second curvature Rc2) of the curved inner surface 30 on the same side as the offset direction V2 of the exhaust pipe main body 21.
　図４に示すように、接続管２３は、上下方向と左右方向とで外形が異なる異形ファンネル形状をなしている。接続管２３は、上下方向と左右方向とで曲率が異なる湾曲内面３０（図５、図６参照）を備える。 As shown in FIG. 4, the connection pipe 23 has a different funnel shape in which the outer shape is different in the vertical direction and the horizontal direction. The connection pipe 23 is provided with a curved inner surface 30 (see FIGS. 5 and 6) having different curvatures in the vertical direction and the horizontal direction.
　図５に示すように、湾曲内面３０の曲率Ｒｃは、左右方向で異なっている。図６に示すように、湾曲内面３０の曲率は、上下方向で異なっている。図５、図６において、符号Ｓｆは下流側ほど径方向外側に拡径する仮想内面を示す。仮想内面Ｓｆは、ストレートに延在している。 As shown in FIG. 5, the curvature Rc of the curved inner surface 30 is different in the left-right direction. As shown in FIG. 6, the curvature of the curved inner surface 30 differs in the vertical direction. In FIG. 5 and FIG. 6, the code | symbol Sf shows the virtual inner surface diameter-expanded radially outward toward the downstream side. The virtual inner surface Sf extends straight.
　図５の上面視で、湾曲内面３０の曲率Ｒｃは、左側のほうが右側よりも僅かに大きい。
　図６の側面視で、湾曲内面３０の曲率Ｒｃは、上側のほうが下側よりも大きい。湾曲内面３０の上側の曲率Ｒｃ１は、上述の第一曲率Ｒｃ１に相当する。湾曲内面３０の下側の曲率Ｒｃ２は、上述の第二曲率Ｒｃ２に相当する。湾曲内面３０の下側は、ストレートに近い湾曲形状とされている。 In the top view of FIG. 5, the curvature Rc of the curved inner surface 30 is slightly larger on the left side than on the right side.
In the side view of FIG. 6, the curvature Rc of the curved inner surface 30 is larger on the upper side than on the lower side. The upper curvature Rc1 of the curved inner surface 30 corresponds to the above-described first curvature Rc1. The lower curvature Rc2 of the curved inner surface 30 corresponds to the above-described second curvature Rc2. The lower side of the curved inner surface 30 has a nearly straight curved shape.
＜排気ガスの流れ＞
　ここで、実施形態に係る湾曲内面３０の作用について比較例と共に説明する。
　図７は、比較例に係る排気ガスの流れを示す上面図である。図８は、図７のＶＩＩＩ－ＶＩＩＩ断面を含む図である。図９は、実施形態に係る排気ガスの流れを示す上面図である。図１０は、図９のＸ－Ｘ断面を含む図である。図１１は、実施形態に係る排気ガスの流れを示す左側面図である。図７～図１１において、ドットが相対的に密な部分（ハッチングが濃い部分）は、ドットが相対的に疎な部分（ハッチングが薄い部分）に比べて排気ガスの流速が大きい部分を示している。 <Flow of exhaust gas>
Here, the operation of the curved inner surface 30 according to the embodiment will be described together with a comparative example.
FIG. 7 is a top view showing the flow of exhaust gas according to a comparative example. FIG. 8 is a view including a VIII-VIII cross section of FIG. FIG. 9 is a top view showing the flow of exhaust gas according to the embodiment. FIG. 10 is a view including the XX cross section of FIG. FIG. 11 is a left side view showing the flow of exhaust gas according to the embodiment. In FIG. 7 to FIG. 11, the relatively dense dot portion (the dark hatched portion) indicates a portion where the flow velocity of the exhaust gas is higher than the relatively sparse dot portion (the thin hatched portion). There is.
　比較例に係る排気管１４Ｘは、実施形態に係る湾曲内面３０（図９参照）を備えていない（図７参照）。図７に示すように、比較例においては、排気ガスの流れが排気管本体２１Ｘの延在方向に沿っている。すなわち、比較例においては、排気ガスの流れがテーパ部２３Ｘの内面から剥離している。図８に示すように、比較例においては、排気ガスの流れがテーパ部２３Ｘ内の径方向中央に偏っている。比較例においては、触媒への排気ガスの当たりが径方向中心部に偏る傾向にある。比較例においては、排気ガスの流速がテーパ部２３Ｘの径方向中心部において大きくなっている。 The exhaust pipe 14X according to the comparative example does not include the curved inner surface 30 (see FIG. 9) according to the embodiment (see FIG. 7). As shown in FIG. 7, in the comparative example, the flow of the exhaust gas is along the extending direction of the exhaust pipe main body 21X. That is, in the comparative example, the flow of exhaust gas is separated from the inner surface of the tapered portion 23X. As shown in FIG. 8, in the comparative example, the flow of the exhaust gas is biased to the radial center in the tapered portion 23X. In the comparative example, the contact of the exhaust gas with the catalyst tends to be biased toward the radial center. In the comparative example, the flow velocity of the exhaust gas is large at the radial center of the tapered portion 23X.
　これに対し、実施形態に係る排気管１４は、接続管２３内に湾曲内面３０を備えている（図９参照）。図９に示すように、実施形態においては、比較例（図７参照）に対し、排気ガスの流れが湾曲内面３０に沿って拡散している。図１０に示すように、実施形態においては、排気ガスの流れが接続管２３内に全体的に拡散している。実施形態においては、排気ガスの流速が接続管２３内で略均等となっている。図１１に示すように、実施形態においては、排気管本体２１が触媒収容管軸線Ｃ２に対してオフセットして配置されている場合であっても、排気ガスの流れが湾曲内面３０に沿って拡散している。これにより、触媒への排気ガスの当たりを均一にし、触媒の劣化を抑えることができる。 On the other hand, the exhaust pipe 14 which concerns on embodiment is equipped with the curved inner surface 30 in the connection pipe 23 (refer FIG. 9). As shown in FIG. 9, in the embodiment, the flow of the exhaust gas is diffused along the curved inner surface 30 with respect to the comparative example (see FIG. 7). As shown in FIG. 10, in the embodiment, the flow of exhaust gas is diffused throughout the connecting pipe 23. In the embodiment, the flow velocity of the exhaust gas is substantially equal in the connection pipe 23. As shown in FIG. 11, in the embodiment, even if the exhaust pipe main body 21 is disposed offset to the catalyst housing pipe axis C2, the flow of exhaust gas diffuses along the curved inner surface 30 doing. This makes it possible to make the exhaust gas hit the catalyst uniformly and to suppress the deterioration of the catalyst.
　以上説明したように、上記実施形態に係る排気管の接続構造２０は、内燃機関４から排出された排気ガスを通す排気管本体２１と、排気ガスの流れ方向Ｖ１における排気管本体２１の下流側に配置され、排気ガスを浄化する触媒１８と、触媒１８を収容する触媒収容管２２と、排気管本体２１と触媒収容管２２とを接続する接続管２３と、を備え、接続管２３は、下流側ほど径方向外側に拡径しつつ湾曲する湾曲内面３０を備える。
　この構成によれば、接続管２３が下流側ほど径方向外側に拡径しつつ湾曲する湾曲内面３０を備えることで、湾曲内面３０から排気ガスの流れが剥離しにくく、排気ガスの流れが湾曲内面３０に沿って拡散することにより、触媒１８への排気ガスの当たりが均一となる。したがって、触媒１８の劣化を抑制することができる。加えて、触媒１８の劣化を抑制することで、触媒１８（触媒収容管２２）の小型化を図ることができる。 As described above, the exhaust pipe connection structure 20 according to the embodiment includes the exhaust pipe main body 21 through which the exhaust gas discharged from the internal combustion engine 4 passes and the downstream side of the exhaust pipe main body 21 in the flow direction V1 of the exhaust gas. , And a connecting pipe 23 for connecting the exhaust pipe main body 21 and the catalyst containing pipe 22. The connecting pipe 23 comprises: It has a curved inner surface 30 which is curved while expanding radially outward toward the downstream side.
According to this configuration, the connecting pipe 23 includes the curved inner surface 30 that is curved while expanding radially outward toward the downstream side, whereby the flow of exhaust gas is less likely to be separated from the curved inner surface 30, and the flow of exhaust gas is curved By diffusing along the inner surface 30, the contact of the exhaust gas to the catalyst 18 becomes uniform. Therefore, the deterioration of the catalyst 18 can be suppressed. In addition, by suppressing the deterioration of the catalyst 18, the catalyst 18 (the catalyst housing pipe 22) can be miniaturized.
　また、上記実施形態では、湾曲内面３０の曲率Ｒｃが下流側ほど大きいことで、接続管２３の上流側では湾曲内面３０の曲率Ｒｃを緩やかにして排気ガスの流れの剥離を抑えることができる。一方、接続管２３の下流側では湾曲内面３０の曲率Ｒｃを急峻にして接続管２３の長さを短くすることができる。したがって、触媒１８の劣化を抑制しつつ、接続管２３内での圧力損失を抑えて出力の低下を抑制することができる。 Further, in the above embodiment, the curvature Rc of the curved inner surface 30 can be made gentle on the upstream side of the connection pipe 23 and the separation of the flow of exhaust gas can be suppressed because the curvature Rc of the curved inner surface 30 increases toward the downstream side. On the other hand, on the downstream side of the connection pipe 23, the curvature Rc of the curved inner surface 30 can be made steep to shorten the length of the connection pipe 23. Therefore, while suppressing the deterioration of the catalyst 18, it is possible to suppress the pressure loss in the connection pipe 23 and to suppress the decrease in the output.
　本発明者は鋭意検討の結果、排気管本体２１が接続管２３との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部３１を備える場合、排気ガスが曲がり部３１を経由して接続管２３に流入すると、接続管２３内において径方向で曲がり部３１と同じ側の部分で排気ガスの流れが剥離しやすいことを見出した。上記実施形態では、湾曲内面３０において径方向で曲がり部３１と同じ側の曲率（第一曲率Ｒｃ１）が他の部分の曲率（第二曲率Ｒｃ２）よりも大きいことで、排気ガスの流れの剥離を抑えることができる。したがって、排気管本体２１が曲がり部３１を備える場合であっても、触媒１８の劣化を抑制することができる。 As a result of intensive investigations, the inventor of the present invention has a case where the exhaust gas has a bent portion 31 when the exhaust pipe main body 21 includes a bent portion 31 concaved radially inward at the upstream side of the connection portion with the connection pipe 23. It has been found that when flowing into the connection pipe 23 via the passage, the flow of exhaust gas is likely to be separated at a portion on the same side as the bent portion 31 in the radial direction in the connection pipe 23. In the above embodiment, the curvature (first curvature Rc1) on the same side as the bent portion 31 in the radial direction in the curved inner surface 30 is larger than the curvature (second curvature Rc2) of the other portion, so separation of the exhaust gas flow Can be reduced. Therefore, even in the case where the exhaust pipe main body 21 includes the bent portion 31, the deterioration of the catalyst 18 can be suppressed.
　本発明者は鋭意検討の結果、排気管本体２１が触媒収容管軸線Ｃ２に対して排気ガスの流れ方向Ｖ１と直交する方向にオフセットして配置されている場合、排気ガスがオフセットした排気管本体２１を経由して接続管２３に流入すると、接続管２３内において排気管本体２１のオフセット方向Ｖ２とは反対側の部分で排気ガスの流れが剥離しやすいことを見出した。上記実施形態では、湾曲内面３０において排気管本体２１のオフセット方向Ｖ２とは反対側の曲率（第一曲率Ｒｃ１）が他の部分の曲率（第二曲率Ｒｃ２）よりも大きいことで、排気ガスの流れの剥離を抑えることができる。したがって、排気管本体２１が触媒収容管軸線Ｃ２に対してオフセットして配置されている場合であっても、触媒１８の劣化を抑制することができる。 When the exhaust pipe main body 21 is arranged offset with respect to the catalyst housing pipe axial line C2 in a direction orthogonal to the flow direction V1 of the exhaust gas as a result of intensive studies, the exhaust pipe main body is offset. It has been found that when the gas flows into the connection pipe 23 via 21, the flow of exhaust gas is likely to be separated at a portion of the connection pipe 23 on the opposite side to the offset direction V 2 of the exhaust pipe body 21. In the above embodiment, the curvature (first curvature Rc1) of the curved inner surface 30 opposite to the offset direction V2 of the exhaust pipe main body 21 is larger than the curvature (second curvature Rc2) of the other portion. It is possible to suppress flow separation. Therefore, even in the case where the exhaust pipe main body 21 is disposed offset to the catalyst housing pipe axis C2, the deterioration of the catalyst 18 can be suppressed.
　本発明者は鋭意検討の結果、排気管本体２１が接続管２３との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部３１を備える場合、排気管本体２１で曲げられつつ下流側へ流れる排気ガスは、接続管２３へ入ると慣性力で曲がり部３１と同じ側に広がりやすいことを見出した。上記実施形態では、排気管本体２１は、触媒収容管軸線Ｃ２に対して排気ガスの流れ方向Ｖ１と直交する方向で、曲がり部３１と反対方向にオフセットして配置されていることで、触媒１８への排気ガスの当たりを均一化することができる。したがって、排気管本体２１が曲がり部３１を備える場合であっても、触媒１８の劣化を抑制することができる。 As a result of intensive studies, the inventor of the present invention has a case where the exhaust pipe main body 21 includes a bent portion 31 which is concaved radially inward at the upstream side with respect to the connection portion with the connection pipe 23. Meanwhile, it was found that the exhaust gas flowing to the downstream side is likely to spread to the same side as the bent portion 31 by inertia force when entering the connection pipe 23. In the above embodiment, the exhaust pipe main body 21 is arranged to be offset in the direction opposite to the bent portion 31 in a direction perpendicular to the flow direction V1 of the exhaust gas with respect to the catalyst housing pipe axis C2. It is possible to equalize the impact of the exhaust gas on. Therefore, even in the case where the exhaust pipe main body 21 includes the bent portion 31, the deterioration of the catalyst 18 can be suppressed.
　なお、上記実施形態では、湾曲内面３０において径方向で内側凹部３１と同じ側と、湾曲内面３０において排気管本体２１のオフセット方向Ｖ２とは反対側と、は径方向で互いに同じ側にある例を挙げて説明したが、これに限らない。例えば、湾曲内面３０において径方向で内側凹部３１と同じ側と、湾曲内面３０において排気管本体２１のオフセット方向Ｖ２とは反対側と、は径方向で互いに反対側にあってもよい。この場合、湾曲内面３０の曲率は、曲がり部３１の勾配および排気管本体２１のオフセット量などを考慮して設定されてもよい。 In the above embodiment, the same side as the inner recess 31 in the radial direction in the curved inner surface 30 and the opposite side of the curved inner surface 30 to the offset direction V2 of the exhaust pipe main body 21 are in the same radial direction. Although it mentioned and mentioned, it does not restrict to this. For example, the same side as the inner recess 31 in the radial direction in the curved inner surface 30 and the opposite side of the curved inner surface 30 to the offset direction V2 of the exhaust pipe main body 21 may be in mutually opposite radial directions. In this case, the curvature of the curved inner surface 30 may be set in consideration of the slope of the bent portion 31, the offset amount of the exhaust pipe main body 21, and the like.
　また、上記実施形態では、接続管２３は、上下方向と左右方向とで外形が異なる異形ファンネル形状をなしている例を挙げて説明したが、これに限らない。例えば、接続管２３は、上下方向と左右方向とで同じ外形をなしていてもよい。例えば、接続管２３は、上下方向と左右方向とで曲率が同じ湾曲内面を備えていてもよい。 Moreover, although the connection pipe 23 mentioned and demonstrated the example which made the different-shaped funnel shape which differs in an external shape by the up-down direction and the left-right direction in the said embodiment, it does not restrict to this. For example, the connection pipe 23 may have the same outer shape in the vertical direction and the horizontal direction. For example, the connection pipe 23 may be provided with a curved inner surface having the same curvature in the vertical direction and the horizontal direction.
　また、上記実施形態では、接続管２３がラッパ形状の外形を有する例を挙げて説明したが、これに限らない。
　例えば、図１２に示すように、接続管１２３がテーパ形状の外形を有していてもよい。接続管１２３（以下「テーパ部」ともいう。）の内面には、排気ガスの流れを遮る邪魔板３５が設けられていてもよい。邪魔板３５は、テーパ部１２３の内面から径方向内側に向けて起立している。これにより、排気管本体２１の延在方向に沿って流れる排気ガスを邪魔板３５で拡散することができる。 Moreover, in the said embodiment, although the connection pipe 23 mentioned and demonstrated the example which has the external shape of a trumpet shape, it does not restrict to this.
For example, as shown in FIG. 12, the connection pipe 123 may have a tapered outer shape. A baffle plate 35 that blocks the flow of exhaust gas may be provided on the inner surface of the connection pipe 123 (hereinafter, also referred to as “taper portion”). The baffle plate 35 stands radially inward from the inner surface of the tapered portion 123. Thus, the exhaust gas flowing along the extending direction of the exhaust pipe main body 21 can be diffused by the baffle plate 35.
　また、図１３に示すように、テーパ部１２３の内面には、径方向内側に凸をなす凸部３６が設けられていてもよい。これにより、排気管本体２１の延在方向に沿って流れる排気ガスを凸部３６で拡散することができる。 Further, as shown in FIG. 13, the inner surface of the tapered portion 123 may be provided with a convex portion 36 that is convex inward in the radial direction. Thus, the exhaust gas flowing along the extending direction of the exhaust pipe main body 21 can be diffused by the convex portion 36.
　また、テーパ部１２３の内面には、邪魔板３５および凸部３６の双方が設けられていてもよい。すなわち、テーパ部１２３の内面には、邪魔板３５および凸部３６の少なくとも一方が設けられていてもよい。また、邪魔板３５および凸部の少なくとも一方は、テーパ部１２３の内面に設けられることに限らず、実施形態に係る湾曲内面３０に設けられていてもよい。 Further, on the inner surface of the tapered portion 123, both the baffle plate 35 and the convex portion 36 may be provided. That is, on the inner surface of the tapered portion 123, at least one of the baffle plate 35 and the convex portion 36 may be provided. Further, at least one of the baffle plate 35 and the convex portion is not limited to being provided on the inner surface of the tapered portion 123, and may be provided on the curved inner surface 30 according to the embodiment.
　なお、本発明は上記実施形態に限られるものではなく、例えば、前記鞍乗型車両には、運転者が車体を跨いで乗車する車両全般が含まれ、自動二輪車（原動機付自転車及びスクータ型車両を含む）のみならず、三輪（前一輪かつ後二輪の他に、前二輪かつ後一輪の車両も含む）又は四輪の車両も含まれる。
　そして、上記実施形態における構成は本発明の一例であり、実施形態の構成要素を周知の構成要素に置き換える等、本発明の要旨を逸脱しない範囲で種々の変更が可能である。 The present invention is not limited to the above embodiment. For example, the straddle-type vehicle includes all vehicles on which the driver straddles the vehicle body, and includes a motorcycle (motorized bicycle and scooter type vehicle Not only three wheels (including one front wheel and two rear wheels but also front two rear wheels and one rear wheel) or four-wheeled vehicles are included.
The configuration in the above embodiment is an example of the present invention, and various modifications can be made without departing from the scope of the present invention, such as replacing the components of the embodiment with known components.
　４　内燃機関
　１８　触媒
　２０　排気管の接続構造
　２１　排気管本体
　２２　触媒収容管
　２３　接続管
　３０　湾曲内面
　３１　内側凹部（曲がり部）
　Ｃ２　触媒収容管軸線（触媒収容管の径方向中心）
　Ｒｃ　湾曲内面の曲率
　Ｒｃ１　第一曲率（湾曲内面の曲率）
　Ｒｃ２　第二曲率（湾曲内面の曲率）
　Ｖ１　排気ガスの流れ方向
　Ｖ２　オフセット方向 REFERENCE SIGNS LIST 4 internal combustion engine 18 catalyst 20 exhaust pipe connection structure 21 exhaust pipe main body 22 catalyst housing pipe 23 connection pipe 30 curved inner surface 31 inner concave portion (curved portion)
C2 Catalyst containing tube axis (radial center of catalyst containing tube)
Rc Curved inner surface curvature Rc1 First curvature (curvature inner surface curvature)
Rc2 Second curvature (curvature of curved inner surface)
V1 exhaust gas flow direction V2 offset direction

Claims (5)

  1. 　内燃機関（４）から排出された排気ガスを通す排気管本体（２１）と、
    　前記排気ガスの流れ方向（Ｖ１）における前記排気管本体（２１）の下流側に配置され、前記排気ガスを浄化する触媒（１８）と、
    　前記触媒（１８）を収容する触媒収容管（２２）と、
    　前記排気管本体（２１）と前記触媒収容管（２２）とを接続する接続管（２３）と、を備え、
    　前記接続管（２３）は、下流側ほど径方向外側に拡径しつつ湾曲する湾曲内面（３０）を備えることを特徴とする排気管の接続構造。     An exhaust pipe body (21) for passing exhaust gas discharged from the internal combustion engine (4);
    A catalyst (18) disposed downstream of the exhaust pipe body (21) in the flow direction (V1) of the exhaust gas and purifying the exhaust gas;
    A catalyst storage pipe (22) for storing the catalyst (18);
    A connecting pipe (23) for connecting the exhaust pipe body (21) and the catalyst storage pipe (22);
    The connection structure of an exhaust pipe characterized in that the connection pipe (23) includes a curved inner surface (30) which is curved while expanding radially outward toward the downstream side.
  2. 　前記湾曲内面（３０）の曲率（Ｒｃ）は、下流側ほど大きいことを特徴とする請求項１に記載の排気管の接続構造。 The exhaust pipe connection structure according to claim 1, wherein the curvature (Rc) of the curved inner surface (30) is larger toward the downstream side.
  3. 　前記排気管本体（２１）は、前記接続管（２３）との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部（３１）を備え、
    　前記湾曲内面（３０）において径方向で前記曲がり部（３１）と同じ側の曲率（Ｒｃ１）は、他の部分の曲率（Ｒｃ２）よりも大きいことを特徴とする請求項１または２に記載の排気管の接続構造。     The exhaust pipe body (21) includes a bent portion (31) which is concaved radially inward at the upstream side of the connection portion with the connection pipe (23), and bent.
    The curvature (Rc1) on the same side as the bent portion (31) in the radial direction in the curved inner surface (30) is larger than the curvature (Rc2) of the other portion, according to claim 1 or 2, Exhaust pipe connection structure.
  4. 　前記排気管本体（２１）は、前記触媒収容管（２２）の径方向中心（Ｃ２）に対して前記排気ガスの流れ方向（Ｖ１）と直交する方向にオフセットして配置され、
    　前記湾曲内面（３０）において前記排気管本体（２１）のオフセット方向（Ｖ２）とは反対側の曲率（Ｒｃ１）は、他の部分の曲率（Ｒｃ２）よりも大きいことを特徴とする請求項１から３のいずれか一項に記載の排気管の接続構造。     The exhaust pipe body (21) is disposed offset in a direction perpendicular to the flow direction (V1) of the exhaust gas with respect to the radial center (C2) of the catalyst storage pipe (22).
    The curvature (Rc1) opposite to the offset direction (V2) of the exhaust pipe body (21) at the curved inner surface (30) is characterized by being larger than the curvature (Rc2) of the other part. Connection structure of the exhaust pipe as described in any one of to 3.
  5. 　前記排気管本体（２１）は、前記接続管（２３）との接続部よりも上流側にて径方向内側に凹をなして曲がる曲がり部（３１）を備え、
    　前記排気管本体（２１）は、前記触媒収容管（２２）の径方向中心（Ｃ２）に対して前記排気ガスの流れ方向（Ｖ１）と直交する方向で、前記曲がり部（３１）と反対方向にオフセットして配置されていることを特徴とする請求項１から４のいずれか一項に記載の排気管の接続構造。     The exhaust pipe body (21) includes a bent portion (31) which is concaved radially inward at the upstream side of the connection portion with the connection pipe (23), and bent.
    The exhaust pipe body (21) is opposite to the bent portion (31) in a direction perpendicular to the flow direction (V1) of the exhaust gas with respect to the radial center (C2) of the catalyst storage pipe (22) The exhaust pipe connection structure according to any one of claims 1 to 4, which is disposed offset to each other.
PCT/JP2018/035047 2017-12-28 2018-09-21 Connection structure of exhaust pipe WO2019130687A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017253191 2017-12-28
JP2017-253191 2017-12-28

Publications (1)

Publication Number Publication Date
WO2019130687A1 true WO2019130687A1 (en) 2019-07-04

Family

ID=67066894

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2018/035047 WO2019130687A1 (en) 2017-12-28 2018-09-21 Connection structure of exhaust pipe

Country Status (1)

Country Link
WO (1) WO2019130687A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020152748A1 (en) * 2001-04-19 2002-10-24 Honda Giken Kogyo Kabushiki Kaisha Exhaust structure in engine for automobile
JP2014058908A (en) * 2012-09-18 2014-04-03 Yutaka Giken Co Ltd Method of manufacturing exhaust emission control device, and exhaust emission control device
WO2014129014A1 (en) * 2013-02-20 2014-08-28 本田技研工業株式会社 Exhaust purification device
JP2016128651A (en) * 2015-01-09 2016-07-14 株式会社三五 Exhaust pipe structure of internal combustion engine
WO2017047319A1 (en) * 2015-09-18 2017-03-23 フタバ産業株式会社 Exhaust pipe and method for manufacturing exhaust pipe

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020152748A1 (en) * 2001-04-19 2002-10-24 Honda Giken Kogyo Kabushiki Kaisha Exhaust structure in engine for automobile
JP2014058908A (en) * 2012-09-18 2014-04-03 Yutaka Giken Co Ltd Method of manufacturing exhaust emission control device, and exhaust emission control device
WO2014129014A1 (en) * 2013-02-20 2014-08-28 本田技研工業株式会社 Exhaust purification device
JP2016128651A (en) * 2015-01-09 2016-07-14 株式会社三五 Exhaust pipe structure of internal combustion engine
WO2017047319A1 (en) * 2015-09-18 2017-03-23 フタバ産業株式会社 Exhaust pipe and method for manufacturing exhaust pipe

Similar Documents

Publication Publication Date Title
CN102953788B (en) Exhaust pipe structure of internal combustion engine
US7624842B2 (en) Exhaust system for an engine and motorcycle including the exhaust system
US9289723B2 (en) Exhaust system for saddle-ride type vehicle
JP5913083B2 (en) Vehicle intake passage structure
US9347406B2 (en) Air cleaner device for vehicle
EP2735715B1 (en) Muffler and saddle type vehicle
JP2007040166A (en) Exhaust device and saddle ride type vehicle
JP5315099B2 (en) Engine exhaust system
EP3505431B1 (en) Saddle-riding-type vehicle canister arrangement structure
US8359835B2 (en) Exhaust device and vehicle with exhaust device
WO2019130687A1 (en) Connection structure of exhaust pipe
JP6251615B2 (en) Suspension device for saddle riding type vehicle
JP2020063725A (en) Silencer structure for saddle riding type vehicle
JP6236700B2 (en) Silencer structure for saddle-ride type vehicles
JP2010255514A (en) Exhaust device for saddle ride type vehicle
EP4080023B1 (en) Straddled vehicle
WO2019187757A1 (en) Exhaust device for internal combustion engine
WO2018078955A1 (en) Exhaust pipe
JP6795633B2 (en) Funnel for intake device
JP5899017B2 (en) Motorcycle exhaust system
WO2021065787A1 (en) Saddle-ridden vehicle silencer structure
JP4260585B2 (en) Motorcycle muffler
JP5788704B2 (en) Engine for saddle-ride type vehicles
CN112922710B (en) Exhaust system
JP5919055B2 (en) Motorcycle silencer

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18893649

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18893649

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP