JP4030172B2

JP4030172B2 - Exhaust system with catalyst in internal combustion engine

Info

Publication number: JP4030172B2
Application number: JP02245898A
Authority: JP
Inventors: 敏浩大高
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1998-02-04
Filing date: 1998-02-04
Publication date: 2008-01-09
Anticipated expiration: 2018-02-04
Also published as: BR9900524A; KR100287442B1; CN1143950C; JPH11223121A; CN1225413A; KR19990072425A

Description

【０００１】
【発明の属する技術分野】
本発明は、内燃機関、特に自動二・三輪車の駆動用として好適な内燃機関における触媒付き排気装置に関するものである。
【０００２】
【従来の技術】
従来自動二輪車用内燃機関の排気系内に、筒状の触媒を配置し、前記機関からの排ガスを反応浄化するようにした、触媒付き排気装置は公知である（特開平９−５３４４１号公報参照）
【０００３】
【発明が解決しようとする課題】
ところが従来の触媒付き排気系装置では、排気管内に配置される筒状の触媒は、排気管の内面に沿うように設けられるグラスウール等よりなる緩衝体により密着状態で支持されているので、排気管と筒状の触媒との間を流れる排ガスの流れが、前記緩衝体により妨げられ、これが排ガスの流れ抵抗を多少とも増大させ、その上排ガスと、触媒との接触面積が減じて排ガスの反応浄化効率を低下させる原因になるという問題がある。
【０００４】
本発明はかかる事情に鑑みてなされたもので、筒状の触媒を排気管に緩衝体を介して緩衝的に支持しながら、触媒を流れる排ガスの流動抵抗を可及的に低減できるようにした、新規な内燃機関における触媒付き排気系装置を提供することを目的とするものである。
【０００５】
【課題を解決するための手段】
上記目的を達成するため、請求項１の発明は、内燃機関の排気ポートに接続される排気管内に筒状の触媒を設け、この触媒を排気管に設けた緩衝体により支持するようにした、内燃機関における触媒付き排気系装置において、排気管に環状の緩衝体を備えた触媒ホルダを設け、その緩衝体の内周面に、横断面長円形状の中空筒体よりなるステーの長径部の外周面を軸方向摺動可能に支持すると共に、同ステーの短径部の内周面に触媒の外周面を固着して、前記長径部の内周面と、該長径部に対応した触媒の外周面との間に排ガスの流通路を形成したことを特徴としており、かかる特徴によれば、筒状の触媒は排気管に緩衝的に摺動可能に支持されながら排気管内を流れる排ガスはその緩衝体に邪魔されずに、その触媒の外周を抵抗少なく、円滑に流れて内燃機関の出力の向上および触媒による排ガスの反応浄化能率の向上に図ることができる。
【０００６】
また請求項２の発明は、請求項１の発明の前記特徴に加えて、前記排気管は保温筒により被覆されることを特徴とし、この特徴によれば、保温筒は、触媒を保温してその反応浄化性能を高めると共に排気管からの熱の外部への放散を抑制することが可能である。
【０００７】
また請求項３の発明は、請求項２の発明の前記特徴に加えて、前記保温筒内において、前記排気管の一部が変色防止筒により覆われると共に、その変色防止筒の内周面と排気管の外周面との間、並びに同変色防止筒の外周面と保温筒の内周面との間にはそれぞれ空隙が形成され、排気管の、変色防止筒で覆われる部分には、排ガス迂回孔が設けられることを特徴とし、この特徴によれば、排気管を流れる排ガスの一部は、排ガス迂回孔を通って排気管と保温筒との間を後方へと迂回して流れるようになっており、これにより排ガスの排気抵抗を低減することが可能である。
【０００８】
【発明の実施の形態】
以下、本発明の実施形態を、添付図面に示した本発明の実施例に基づいて説明する。
【０００９】
なお、以下の説明において、前後、左右および上下は、自動二輪車の進行方向に対していう。
【００１０】
先ず図１〜１０を参照して本発明装置を自動二輪車に実施した場合の第１実施例について説明するに、図１は、本発明装置を備えた自動二輪車の側面図、図２は、排気系の触媒装着部分の縦断面図、図３は、図２の３−３線に沿う拡大断面図、図４は、図２の４−４線に沿う拡大断面図、図５は、図２の５−５線に沿う拡大断面図、図６は、図５の６−６線に沿う断面図、図７は、排気系の消音器の縦断面図、図８は、図７の８−８線に沿う断面図、図９は、図７の９−９線に沿う断面図、図１０は、図７の１０−１０線に沿う断面図である。
【００１１】
図１において、自動二輪車の車体フレームＦには、その走行用内燃機関Ｅが搭載されている。この内燃機関Ｅの頭部前面には排気ポートＰｅが開口され、この排気ポートＰｅに、排気系ＥＸが連通接続される。
【００１２】
なお、内燃機関Ｅが多気筒の場合には、排気ポートに排気マニホールドを介して排気系ＥＸが連通接続される。
【００１３】
前記排気系ＥＸは内燃機関Ｅの前方より、その内燃機関Ｅの一側を通って車体フレームＦの後方へと延長されており、その後端部は、自動二輪車の後車輪Ｗｒの側方を通って、その出口は後方に向かって大気に開放されている。また排気系ＥＸの後部を構成する、後述の消音器Ｍには、ハンガＨａが溶接されており、このハンガＨａを介して、消音器Ｍすなわち排気系ＥＸの後部が、車体フレームＦにボルト・ナット等の固着具により着脱可能に懸吊支持される。
【００１４】
次に排気系ＥＸの構造を、主に図２〜１０を参照して詳細に説明するに、この排気装置ＥＸは、内燃機関Ｅの排気ポートＰｅに一体に連通接続される排気管Ｐの後部に消音器Ｍを一体に接続して構成されている。
【００１５】
前記排気管Ｐ内には、後に詳述する筒状の金属触媒Ｃが装着されており、内燃機関Ｅより排出される排ガスは、排気管Ｐを通る間にその金属触媒ＣによりＨＣ、ＣＯ、ＮＯｘ等の有害成分を反応浄化したのち、消音器Ｍを通って大気に放出される。
【００１６】
前記排気管Ｐは、上流側排気管１と、その下流端に接続される下流側排気管２とより構成されている。上流側排気管１は、下向きに凹状に湾曲形成されており、その上流端には接続フランジが固着されており、この接続フランジ１₁が、前記内燃機関Ｅの前面に開口する排気ポートＰｅの取付座に、ボルト等の固着具３をもって固着される。上流側排気管１の下流端は、下流側排気管２の上流端に挿入され、溶接等により一体に接続される。前記下流側排気管２は、短い上流側部分２ｕの後端にそれよりも長い下流側部分２ｄを溶接等により一体に接続し構成されている。
【００１７】
前記下流側排気管２の下流側部分２ｄは直状に形成されていて、その内部に同じく直状に形成される筒状の金属触媒Ｃが装着される。前記金属触媒Ｃは、ＳＵＳ板等の耐熱性金属板に多数の小孔９₁を穿設したパンチングプレートにより両端開放の筒状に形成された触媒本体９の内外面に触媒エレメントを担持して構成されている。
【００１８】
図２，３に示すように、前記筒状の金属触媒Ｃの前部は、前部ステー４を介して下流側排気管２に固定状態に支持されている。前記前部ステー４は横断面長円形状の中空筒体により構成され、その短径部４₁の内周面が、前記金属触媒Ｃの前部外周面に溶接等により固着され、またその長径部４₂の外周面が、下流側排気管２の前部内周面に溶接等により固着される。したがって筒状の金属触媒Ｃの前部は、前記ステー４を介して下流側排気管２の前部に固定支持され、その下流側排気管２と、金属触媒Ｃとの間には環状の排ガス通路が形成される。
【００１９】
また図２，５，６に示すように前記金属触媒Ｃの後部は、触媒ホルダＨｃを介して下流側排気管２にその長手方向に摺動可能に支持されている。前記触媒ホルダＨｃは、下流側排気管２の下流側部分２ｄの途中に介在されており、その下流側部分２ｄよりも大径に形成される短円筒状のホルダケース５の環状空隙部内に緩衝体６を装填し、さらにその緩衝体６の内周面に沿って下流側排気管２の下流側部分２ｄと略同径の環状の支持筒７を設けて構成されている。前記ホルダケース５は、下流側排気管２の下流側部分２ｄの、前後に分割された前部分と後部分との間に溶接等により一体に固着され、前記支持筒７は、その周壁に複数の通気孔８が穿設されていて、この通気孔８を通して緩衝体６内に排ガスを流通させその排ガス音を吸収減音できるようになっている。前記緩衝体６は、ＳＵＳウールによりメッシュ状に形成されている。
【００２０】
図５，６に明瞭に示すように、金属触媒Ｃの後端の、前記触媒ホルダＨｃと対応する部分の外周面には、前記前部ステー４と同じく横断面長円形状の中空筒体よりなる後部ステー１０の短径部１０₁の内周面が溶接等により固着され、この後部ステー１０の長径部１０₂の外周面は、前記触媒ホルダＨｃの支持筒７の内周面に軸方向に摺動可能に支持されている。したがって筒状の金属触媒Ｃの後部は、下流側排気管２に対して前記触媒ホルダＨｃにより長手方向に摺動可能であり、下流側排気管２に対して金属触媒Ｃの熱等による膨縮が許容され、またその金属触媒Ｃは下流側排気管２に緩衝体６を介して緩衝的に支持され、金属触媒Ｃの後部外周面と、触媒ホルダＨｃの緩衝体６との間は離間されて排ガスの流通路１１が形成される。これにより金属触媒Ｃを流れる排ガスは、緩衝体６に邪魔されることなく、その流通路１１を通って抵抗少なく流れる。
【００２１】
図２，４に明瞭に示すように、下流側排気管２の大部分は、保温筒１２により被覆されている。この保温筒１２は、前部保温筒１２₁の後端に後部保温筒１２₂を溶接等により一体に接続して構成されており、その前端は下流側排気管２の上流端に溶接等により固着され、また保温筒１２の後端には、略１８０°の位相差を存して対をなす横断面Ｕ字状の潰し部１３が形成され、これらの潰し部１３の内面が下流側排気管２の後部外周面に密着され、保温筒１２の後端は下流側排気管２に支持されている。
【００２２】
而して前記保温筒１２は、金属触媒Ｃを保温してその反応浄化性能を高めると共に排気管Ｐからの熱の外部への放散を抑制して後述する消音器Ｍの外筒１８への熱害を低減するのに役立つ。
【００２３】
図２に示すように、下流側排気管２の上流側部分２ｕには、短い中空円筒状の変色防止筒１５が溶接等により固着される。この変色防止筒１５は下流側排気管２と前記保温筒１２との間に介在され、それらの間にはそれぞれ空隙が形成される。下流側排気管２の前記変色防止筒１５により覆われる部分には、周方向に間隔をあけて複数の小孔よりなる排ガス迂回孔１６が穿設されている。内燃機関Ｅから上流側排気管１を経て下流側排気管２を流れる排ガスの一部は、前記排ガス迂回孔１６を通って下流側排気管２と保温筒１２との間を後方へと迂回して流れるようになっており、これにより排ガスの排気抵抗を低減して内燃機関Ｅの出力アップ、特にその中、低速運転域での出力アップに寄与できるようになっている。
【００２４】
前記下流側排気管２および保温筒１２は、排気系ＥＸの後半部を構成する消音器Ｍ内に、その入口側より挿着され、その消音器Ｍの入口端は、前部保温筒１２₁の前端外周に溶接等により固着され、下流側排気管２の下流側部分２ｄは、消音器Ｍの途中まで延びている。
【００２５】
図７，８に示すように、消音器Ｍの外筒１８は、後方に向かって末広状に拡がる截頭円錐状の前部外筒１８ｆと、その後端に溶接等により固着される円筒状の後部外筒１８ｒとより構成されている。後部外筒１８ｒ内には環状の空隙を存して内筒１９が設けられる。この内筒１９内は、第１隔壁２０、第２隔壁２１および内筒１９の後壁１９₁とにより第１室２３、第２室２４および第３室２５に区画されており、前記第１室２３と第３室２５は、第１隔壁２０と第２隔壁２１間に、橋架連結される第１連通管２６により相互に連通され、また第３室２５と第２室２４は第２隔壁２１に片持支持される第２連通管２７により相互に連通され、さらに第２室２４と大気とが第２隔壁２１および外筒１８の後壁１８₁間に橋架支持される第３連通管２８により連通されている。
【００２６】
下流側排気管２より金属触媒Ｃを通って反応浄化された排ガスは、消音器Ｍ内に流入し、ここで第１室２３から第１連通管２６を通って第３室２５に入り、この第３室２５から第２連通管２７を通って第２室２４に入り、さらに第２室２４から第３連通管２８を通って大気に放出される。そしてこの間に排ガスは消音器Ｍ内を膨張と収縮を繰り返しつつ消音器Ｍ内の第１、３および２室２３，２５および２４を迂回して流れて効果的に減音されたのち、大気に放出される。
【００２７】
次にこの第１実施例の作用について説明すると、いま内燃機関Ｅの運転により発生した排ガスは、その排気ポートＰｅより上流側排気管１を経て下流側排気管２へと流れ、その下流側排気管２に設けた筒状の金属触媒Ｃにより、その中に含まれる有害成分が反応除去されたのち、消音器Ｍへと流れ、ここで減音されて大気へと放出される。
【００２８】
ところで金属触媒Ｃと、これを緩衝的に支持する触媒ホルダＨｃの緩衝体６間は離間されてそれら間に排ガスの流通路１１が形成されるので、金属触媒Ｃの外側を流れる排ガスは、その緩衝体６により邪魔されずに、その流れに乱れを生じることがなく円滑に流れ、これにより排気抵抗を低減して内燃機関Ｅの出力向上に寄与するばかりでなく排ガスと金属触媒Ｃとの接触面積を増大してその触媒Ｃによる排ガス浄化能率を高めることができる。
【００２９】
次に本発明の第２実施例について図１１，１２を参照して説明する。
【００３０】
図１１は、排気系の触媒装着部の横断面図、図１２は、図１１の１２−１２線に沿う断面図であり、前記第１実施例のものと同じ部材には同じ符号が付される。
【００３１】
この第２実施例では、触媒ホルダＨｃの構造において前記第１実施例と相違しており、この触媒ホルダＨｃは、ホルダケース５とこのホルダケース５内に装填される緩衝体６とより構成されており、この緩衝体６の内面は、下流側排気管２内の、金属触媒Ｃに固着される断面楕円形状の後部ステー１０の外周面に直接接触して、その軸方向に摺動自在に支持されている。そしてこの第２実施例のものは、前記第１実施例の支持筒が省略される。
【００３２】
ところでこの第２実施例のものも筒状の金属触媒Ｃの後部が、触媒ホルダＨｃの緩衝体６により軸方向に摺動可能に支持され、金属触媒Ｃは緩衝体６に対して離間しており、それらの間に排ガスの流通路１１を形成することができ、前記第１実施例のものと同等の効果を奏し、さらに前記支持筒（第１実施例）の省略により部品点数を低減して排気系装置のコストダウンを図ることができる。
【００３３】
以上、本発明の実施例について説明したが、本発明はその実施例に限定されることなく、本発明の範囲内で種々の実施例が可能である。たとえば前記実施例では、本発明装置を自動二輪車用内燃機関の排気系に実施した場合について説明したが、これを他の車両、他の機器用内燃機関の排気系に実施してもよく、また前記実施例では、筒状の触媒として金属触媒Ｃを用いた場合について説明したが、その金属触媒Ｃに変えて非金属性の他の触媒を用いてもよい。さらに前記実施例では、緩衝体としてＳＵＳウールを用いているが、これに変えて従来公知の他の緩衝体を用いてもよい。
【００３４】
【発明の効果】
以上のように、本発明によれば、触媒付き排気系装置において、排気管に環状の緩衝体を備えた触媒ホルダを設け、その緩衝体の内周面に、横断面長円形状の中空筒体よりなるステーの長径部の外周面を軸方向摺動可能に支持すると共に、同ステーの短径部の内周面に触媒の外周面を固着して、前記長径部の内周面と、該長径部に対応した触媒の外周面との間に排ガスの流通路を形成したので、排気管内を流れる排ガスは、触媒を支持する緩衝体に邪魔されずに、その触媒の外周を抵抗少なく、円滑に流れて排気抵抗を低減し、内燃機関の出力向上および触媒による排ガスの反応浄化能率の向上を図ることができる。
【００３５】
また特に請求項２の発明によれば、排気管は保温筒により被覆されるので、この保温筒により触媒を保温してその反応浄化性能を高めると共に排気管からの熱の外部への放散を抑制することが可能である。
【００３６】
また特に請求項３の発明によれば、保温筒内において、前記排気管の一部が変色防止筒により覆われると共に、その変色防止筒の内周面と排気管の外周面との間、並びに同変色防止筒の外周面と保温筒の内周面との間にはそれぞれ空隙が形成され、排気管の、変色防止筒で覆われる部分には、排ガス迂回孔が設けられるので、排気管を流れる排ガスの一部は、排ガス迂回孔を通って排気管と保温筒との間を後方へと迂回して流れるようになっており、これにより排ガスの排気抵抗を低減することが可能である。
【図面の簡単な説明】
【図１】本発明装置を備えた自動二輪車の側面図
【図２】排気系の触媒装着部分の縦断面図
【図３】図２の３−３線に沿う拡大断面図
【図４】図２の４−４線に沿う拡大断面図
【図５】図２の５−５線に沿う拡大断面図
【図６】図５の６−６線に沿う断面図
【図７】排気系の消音器の縦断面図
【図８】図７の８−８線に沿う断面図
【図９】図７の９−９線に沿う断面図
【図１０】図７の１０−１０線に沿う断面図
【図１１】排気系の触媒装着部の横断面図
【図１２】図１１の１２−１２線に沿う断面図
【符号の説明】
６・・・・緩衝体
１０・・・ステー（後部ステー）
１０ ₁ ・・短径部
１０ ₂ ・・長径部
１１・・・流通路
１２・・・保温筒
１５・・・変色防止筒
１６・・・排ガス迂回孔
Ｃ・・・・触媒（金属触媒）
Ｅ・・・・内燃機関
Ｈｃ・・・触媒ホルダ
Ｐ・・・・排気管
Ｐｅ・・・排気ポート[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust apparatus with a catalyst in an internal combustion engine, particularly an internal combustion engine suitable for driving a motorcycle or a tricycle.
[0002]
[Prior art]
Conventionally, a catalyst-equipped exhaust system in which a cylindrical catalyst is disposed in an exhaust system of an internal combustion engine for a motorcycle and exhaust gas from the engine is reacted and purified is known (see Japanese Patent Laid-Open No. 9-53441). )
[0003]
[Problems to be solved by the invention]
However, in the conventional exhaust system apparatus with a catalyst, the cylindrical catalyst disposed in the exhaust pipe is supported in close contact with a buffer made of glass wool or the like provided along the inner surface of the exhaust pipe. The flow of exhaust gas flowing between the catalyst and the cylindrical catalyst is hindered by the buffer, which slightly increases the flow resistance of the exhaust gas, and further reduces the contact area between the exhaust gas and the catalyst, thereby reducing the reaction of the exhaust gas. There is a problem of causing a decrease in efficiency.
[0004]
The present invention has been made in view of such circumstances, and the flow resistance of the exhaust gas flowing through the catalyst can be reduced as much as possible while supporting the cylindrical catalyst in the exhaust pipe through the buffer. An object of the present invention is to provide a catalyst-equipped exhaust system in a new internal combustion engine.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is provided with a cylindrical catalyst in an exhaust pipe connected to an exhaust port of an internal combustion engine, and the catalyst is supported by a buffer provided in the exhaust pipe. In an exhaust system device with a catalyst in an internal combustion engine, a catalyst holder having an annular buffer body is provided in an exhaust pipe, and a long diameter portion of a stay made of a hollow cylindrical body having an oblong cross section is formed on the inner peripheral surface of the buffer body . The outer peripheral surface is supported so as to be slidable in the axial direction, and the outer peripheral surface of the catalyst is fixed to the inner peripheral surface of the short diameter portion of the stay, and the inner peripheral surface of the long diameter portion and the catalyst corresponding to the long diameter portion An exhaust gas flow passage is formed between the exhaust pipe and the outer peripheral surface. According to this feature, the exhaust gas flowing through the exhaust pipe is supported while the cylindrical catalyst is slidably supported by the exhaust pipe. Without being disturbed by the buffer, the outer periphery of the catalyst has little resistance, and the circle It is possible to achieve the improvement of the reaction purification efficiency of exhaust gas by improving and catalyst of the output of the internal combustion engine flows into.
[0006]
The invention of claim 2 is characterized in that, in addition to the feature of the invention of claim 1, the exhaust pipe is covered with a heat insulation cylinder, and according to this feature, the heat insulation cylinder keeps the catalyst warm. It is possible to enhance the reaction purification performance and to suppress the diffusion of heat from the exhaust pipe to the outside.
[0007]
According to a third aspect of the invention, in addition to the feature of the second aspect of the invention, in the heat retaining cylinder, a part of the exhaust pipe is covered with a discoloration preventing cylinder, and an inner peripheral surface of the discoloration preventing cylinder is provided. Air gaps are formed between the outer peripheral surface of the exhaust pipe and between the outer peripheral surface of the same color-preventing cylinder and the inner peripheral surface of the heat retaining cylinder, and exhaust gas in the portion covered with the discoloration-preventing cylinder of the exhaust pipe. According to this feature, a part of the exhaust gas flowing through the exhaust pipe passes through the exhaust gas bypass hole and flows backward between the exhaust pipe and the heat insulation cylinder. Thus, the exhaust resistance of the exhaust gas can be reduced.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.
[0009]
In the following description, front and rear, left and right, and top and bottom refer to the traveling direction of the motorcycle.
[0010]
First, referring to FIGS. 1 to 10, a description will be given of a first embodiment in which the apparatus of the present invention is applied to a motorcycle. FIG. 1 is a side view of a motorcycle equipped with the apparatus of the present invention, and FIG. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2, FIG. 4 is an enlarged sectional view taken along line 4-4 in FIG. 2, and FIG. 6 is a sectional view taken along line 6-6 of FIG. 5, FIG. 7 is a longitudinal sectional view of a silencer of the exhaust system, and FIG. FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 7, and FIG. 10 is a cross-sectional view taken along line 10-10 in FIG.
[0011]
In FIG. 1, a traveling internal combustion engine E is mounted on a body frame F of a motorcycle. An exhaust port Pe is opened in front of the head of the internal combustion engine E, and an exhaust system EX is connected to the exhaust port Pe.
[0012]
When the internal combustion engine E is multi-cylinder, an exhaust system EX is connected to the exhaust port via an exhaust manifold.
[0013]
The exhaust system EX extends from the front of the internal combustion engine E to one side of the internal combustion engine E to the rear of the vehicle body frame F, and its rear end passes through the side of the rear wheel Wr of the motorcycle. The outlet is open to the atmosphere toward the rear. Moreover, a hanger Ha is welded to a silencer M, which will be described later, constituting the rear part of the exhaust system EX, and the silencer M, that is, the rear part of the exhaust system EX is connected to the vehicle body frame F via the hanger Ha. Suspended and supported by a fastener such as a nut.
[0014]
Next, the structure of the exhaust system EX will be described in detail mainly with reference to FIGS. 2 to 10. This exhaust system EX is a rear part of the exhaust pipe P that is integrally connected to the exhaust port Pe of the internal combustion engine E. Further, the silencer M is integrally connected.
[0015]
A cylindrical metal catalyst C, which will be described in detail later, is mounted in the exhaust pipe P. Exhaust gas discharged from the internal combustion engine E is HC, CO, After harmful components such as NOx are reacted and purified, they are released to the atmosphere through the silencer M.
[0016]
The exhaust pipe P is composed of an upstream exhaust pipe 1 and a downstream exhaust pipe 2 connected to the downstream end thereof. Upstream exhaust pipe 1 downward and is curved concavely, at its upstream end is secured is connecting flange, the connecting flange 1 _1, the exhaust port Pe which opens in front of the internal combustion engine E It is fixed to the mounting seat with a fixing tool 3 such as a bolt. The downstream end of the upstream side exhaust pipe 1 is inserted into the upstream end of the downstream side exhaust pipe 2 and is integrally connected by welding or the like. The downstream exhaust pipe 2 is configured by integrally connecting a longer downstream portion 2d to the rear end of a short upstream portion 2u by welding or the like.
[0017]
The downstream portion 2d of the downstream exhaust pipe 2 is formed in a straight shape, and a cylindrical metal catalyst C that is also formed in a straight shape is mounted therein. The metal catalyst C is to support the catalyst elements on the inner and outer surfaces of the catalyst body 9 formed in a cylindrical open ends by punching plate bored a number of small holes 9 ₁ a refractory metal plate of SUS plate or the like It is configured.
[0018]
As shown in FIGS. 2 and 3, the front portion of the cylindrical metal catalyst C is supported by the downstream exhaust pipe 2 in a fixed state via a front stay 4. The front stay 4 is constituted by a transverse surface length circular hollow cylinder, the inner peripheral surface of the minor axis portion 4 ₁ is secured by welding or the like on the front outer peripheral surface of the metal catalyst C, also the major axis the outer peripheral surface of the part 4 ₂ is fixed by welding or the like to the front inner peripheral surface of the downstream side exhaust pipe 2. Therefore, the front part of the cylindrical metal catalyst C is fixedly supported on the front part of the downstream exhaust pipe 2 via the stay 4, and an annular exhaust gas is interposed between the downstream exhaust pipe 2 and the metal catalyst C. A passage is formed.
[0019]
As shown in FIGS. 2, 5, and 6, the rear portion of the metal catalyst C is supported by the downstream exhaust pipe 2 through the catalyst holder Hc so as to be slidable in the longitudinal direction. The catalyst holder Hc is interposed in the middle of the downstream side portion 2d of the downstream side exhaust pipe 2, and is buffered in the annular gap of the short cylindrical holder case 5 formed with a larger diameter than the downstream side portion 2d. The body 6 is loaded, and an annular support cylinder 7 having the same diameter as that of the downstream portion 2d of the downstream exhaust pipe 2 is provided along the inner peripheral surface of the buffer body 6. The holder case 5 is integrally fixed by welding or the like between the front part and the rear part of the downstream part 2d of the downstream exhaust pipe 2 which are divided into the front and rear, and a plurality of the support cylinders 7 are attached to the peripheral wall. The vent hole 8 is formed so that exhaust gas can be circulated through the buffer hole 6 through the vent hole 8 to absorb and reduce the exhaust gas sound. The buffer body 6 is formed in a mesh shape with SUS wool.
[0020]
As clearly shown in FIGS. 5 and 6, the outer peripheral surface of the portion corresponding to the catalyst holder Hc at the rear end of the metal catalyst C is formed of a hollow cylinder having an elliptical cross section like the front stay 4. the inner peripheral surface of the short diameter portion 10 ₁ of the rear stays 10 are fixed by welding or the like to be, the outer peripheral surface of the diameter portion 10 ₂ of the rear stay 10 is axially on the inner peripheral surface of the support tube 7 of the catalyst holder Hc It is slidably supported on. Therefore, the rear part of the cylindrical metal catalyst C can slide in the longitudinal direction with respect to the downstream exhaust pipe 2 by the catalyst holder Hc, and expansion and contraction due to the heat of the metal catalyst C with respect to the downstream exhaust pipe 2 In addition, the metal catalyst C is bufferedly supported by the downstream exhaust pipe 2 via the buffer body 6, and the rear outer peripheral surface of the metal catalyst C and the buffer body 6 of the catalyst holder Hc are separated from each other. Thus, the exhaust gas flow passage 11 is formed. Thereby, the exhaust gas flowing through the metal catalyst C flows through the flow passage 11 with less resistance without being obstructed by the buffer body 6.
[0021]
As clearly shown in FIGS. 2 and 4, most of the downstream side exhaust pipe 2 is covered with a heat insulating cylinder 12. The heat insulating tube 12, the rear end of the front heat insulating tube 12 ₁ and the rear heat insulating tube 12 ₂ is constructed by connecting together by welding or the like, the front end by welding or the like downstream the upstream end of the exhaust pipe 2 A crushed portion 13 having a U-shaped cross-section that forms a pair with a phase difference of about 180 ° is formed at the rear end of the heat insulating cylinder 12, and the inner surface of the crushed portion 13 is downstream exhaust. The pipe 2 is in close contact with the outer peripheral surface of the rear portion, and the rear end of the heat insulating cylinder 12 is supported by the downstream exhaust pipe 2.
[0022]
Thus, the heat retaining cylinder 12 retains the metal catalyst C to improve its reaction purification performance, and suppresses the heat from the exhaust pipe P from being radiated to the outside, and heat to the outer cylinder 18 of the silencer M, which will be described later. Helps reduce harm.
[0023]
As shown in FIG. 2, a short hollow cylindrical discoloration preventing cylinder 15 is fixed to the upstream portion 2u of the downstream exhaust pipe 2 by welding or the like. The discoloration preventing cylinder 15 is interposed between the downstream exhaust pipe 2 and the heat retaining cylinder 12, and a gap is formed between them. An exhaust gas bypass hole 16 made up of a plurality of small holes is formed in a portion of the downstream exhaust pipe 2 covered with the discoloration prevention cylinder 15 at intervals in the circumferential direction. A part of the exhaust gas flowing from the internal combustion engine E through the upstream exhaust pipe 1 and the downstream exhaust pipe 2 bypasses the downstream exhaust pipe 2 and the heat retaining cylinder 12 backward through the exhaust gas bypass hole 16. As a result, the exhaust resistance of the exhaust gas is reduced, thereby contributing to an increase in the output of the internal combustion engine E, in particular, an increase in the output in the low speed operation region.
[0024]
The downstream exhaust pipe 2 and the heat retaining cylinder 12 are inserted into the silencer M constituting the latter half of the exhaust system EX from the inlet side, and the inlet end of the silencer M is the front heat retaining cylinder 12 _1. The downstream portion 2d of the downstream side exhaust pipe 2 extends to the middle of the silencer M.
[0025]
As shown in FIGS. 7 and 8, the outer cylinder 18 of the silencer M has a truncated conical front outer cylinder 18 f that expands toward the rear and a cylindrical shape fixed to the rear end thereof by welding or the like. The rear outer cylinder 18r is configured. An inner cylinder 19 is provided in the rear outer cylinder 18r with an annular gap. The inner cylinder 19 is partitioned into a first chamber 23, a second chamber 24, and a third chamber 25 by a first partition wall 20, a second partition wall 21, and a rear wall 19 ₁ of the inner cylinder 19. The chamber 23 and the third chamber 25 are connected to each other by a first communication pipe 26 that is bridge-connected between the first partition wall 20 and the second partition wall 21, and the third chamber 25 and the second chamber 24 are connected to the second partition wall. 21 to communicate with each other by the second communicating pipe 27 that is cantilevered, further third communication pipe with the atmosphere the second chamber 24 is bridged supported between the rear wall 18 ₁ of the second partition wall 21 and the outer cylinder 18 28.
[0026]
The exhaust gas reacted and purified from the downstream exhaust pipe 2 through the metal catalyst C flows into the silencer M, where it enters the third chamber 25 from the first chamber 23 through the first communication pipe 26. The third chamber 25 enters the second chamber 24 through the second communication pipe 27 and is further released from the second chamber 24 through the third communication pipe 28 to the atmosphere. During this time, the exhaust gas flows through the first, third and second chambers 23, 25 and 24 in the silencer M while repeating expansion and contraction in the silencer M, and is effectively reduced in sound. Released.
[0027]
Next, the operation of the first embodiment will be described. Exhaust gas generated by the operation of the internal combustion engine E now flows from the exhaust port Pe to the downstream exhaust pipe 2 via the upstream exhaust pipe 1, and the downstream exhaust. The tubular metal catalyst C provided in the pipe 2 reacts and removes harmful components contained therein, and then flows to the silencer M, where the sound is reduced and released to the atmosphere.
[0028]
By the way, the metal catalyst C and the buffer body 6 of the catalyst holder Hc that supports this in a buffering manner are separated from each other and an exhaust gas flow passage 11 is formed between them, so that the exhaust gas flowing outside the metal catalyst C is It is not disturbed by the buffer body 6 and flows smoothly without disturbing the flow, thereby reducing exhaust resistance and contributing to improving the output of the internal combustion engine E, as well as contact between the exhaust gas and the metal catalyst C. The exhaust gas purification efficiency by the catalyst C can be increased by increasing the area.
[0029]
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0030]
FIG. 11 is a cross-sectional view of the catalyst mounting portion of the exhaust system, and FIG. 12 is a cross-sectional view taken along the line 12-12 in FIG. 11. The same members as those in the first embodiment are denoted by the same reference numerals. The
[0031]
In the second embodiment, the structure of the catalyst holder Hc is different from that of the first embodiment, and the catalyst holder Hc includes a holder case 5 and a buffer body 6 loaded in the holder case 5. The inner surface of the buffer body 6 is in direct contact with the outer peripheral surface of the rear stay 10 having an elliptical cross section fixed to the metal catalyst C in the downstream side exhaust pipe 2, and is slidable in the axial direction thereof. It is supported. In the second embodiment, the support cylinder of the first embodiment is omitted.
[0032]
By the way, the rear part of the cylindrical metal catalyst C is also supported by the buffer body 6 of the catalyst holder Hc so as to be slidable in the axial direction, and the metal catalyst C is separated from the buffer body 6. The exhaust gas flow passage 11 can be formed between them, and the same effect as that of the first embodiment can be obtained, and the number of parts can be reduced by omitting the support cylinder (first embodiment). As a result, the cost of the exhaust system can be reduced.
[0033]
As mentioned above, although the Example of this invention was described, this invention is not limited to the Example, A various Example is possible within the scope of the present invention. For example, in the above-described embodiment, the case where the apparatus of the present invention is implemented in the exhaust system of an internal combustion engine for a motorcycle has been described. However, this may be implemented in the exhaust system of an internal combustion engine for another vehicle or other equipment. In the above-described embodiment, the case where the metal catalyst C is used as the cylindrical catalyst has been described. However, instead of the metal catalyst C, another non-metallic catalyst may be used. Furthermore, in the said Example, although SUS wool is used as a buffer, it may change to this and may use another conventionally well-known buffer.
[0034]
【The invention's effect】
As described above, according to the present invention, in the exhaust system with a catalyst, the exhaust pipe is provided with the catalyst holder provided with the annular buffer body, and the hollow cylinder having an elliptical cross section is formed on the inner peripheral surface of the buffer body. And supporting the outer peripheral surface of the long diameter portion of the stay slidably in the axial direction, and fixing the outer peripheral surface of the catalyst to the inner peripheral surface of the short diameter portion of the stay, and the inner peripheral surface of the long diameter portion, Since the exhaust gas flow passage is formed between the catalyst and the outer peripheral surface corresponding to the long diameter portion , the exhaust gas flowing in the exhaust pipe is not obstructed by the buffer supporting the catalyst, and the outer periphery of the catalyst has less resistance. It can flow smoothly to reduce exhaust resistance, improve the output of the internal combustion engine, and improve the reaction purification efficiency of the exhaust gas by the catalyst.
[0035]
In particular, according to the invention of claim 2, since the exhaust pipe is covered with the heat insulation cylinder, the catalyst is kept warm by the heat insulation cylinder to improve its reaction purification performance and to suppress the diffusion of heat from the exhaust pipe to the outside. Is possible.
[0036]
In particular, according to the invention of claim 3, in the heat retaining cylinder, a part of the exhaust pipe is covered with the discoloration preventing cylinder, and between the inner peripheral surface of the discoloration preventing cylinder and the outer peripheral surface of the exhaust pipe, and Air gaps are formed between the outer peripheral surface of the same discoloration prevention cylinder and the inner peripheral surface of the heat insulation cylinder, and an exhaust gas bypass hole is provided in a portion of the exhaust pipe covered with the discoloration prevention cylinder. Part of the flowing exhaust gas flows through the exhaust gas bypass hole and bypasses the space between the exhaust pipe and the heat insulation cylinder to the rear, thereby reducing the exhaust resistance of the exhaust gas.
[Brief description of the drawings]
FIG. 1 is a side view of a motorcycle equipped with the device of the present invention. FIG. 2 is a longitudinal sectional view of a catalyst mounting portion of an exhaust system. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2 is an enlarged sectional view taken along line 4-4 [FIG. 5] An enlarged sectional view taken along line 5-5 in FIG. 2 [FIG. 6] A sectional view taken along line 6-6 in FIG. FIG. 8 is a sectional view taken along line 8-8 in FIG. 7. FIG. 9 is a sectional view taken along line 9-9 in FIG. 7. FIG. 10 is a sectional view taken along line 10-10 in FIG. 11 is a cross-sectional view of a catalyst mounting portion of an exhaust system. FIG. 12 is a cross-sectional view taken along the line 12-12 in FIG.
6 ... Buffer 10 ... Stay (rear stay)
10 ₁ ・・ Short diameter part
10 ₂ ..Long diameter part 11 ... Flow passage
12 ... Insulation tube
15 ... Discoloration prevention cylinder
16 ... exhaust gas bypass hole C ... catalyst (metal catalyst)
E ... Internal combustion engine Hc ... Catalyst holder P ... Exhaust pipe Pe ... Exhaust port

Claims

Exhaust pipe connected to an exhaust port of an internal combustion engine (E) (Pe) of the circular cylindrical catalyst in (P) (C) provided, cushion provided with the catalyst (C) in the exhaust pipe (P) ( In the exhaust system with catalyst in the internal combustion engine, which is supported by 6),
A catalyst holder (Hc) provided with an annular buffer (6) is provided in the exhaust pipe (P), and a stay (10) made of a hollow cylinder having an elliptical cross section is formed on the inner peripheral surface of the buffer (6). diameter section outer peripheral surface (10 ₂₎ with axially slidably supported in), fixed to the outer peripheral surface of the catalyst (C) on the inner peripheral surface of the short diameter portion of the stay (10) (10 ₁₎ Te, and the inner peripheral surface of the major diameter portion (10 _2), and characterized by forming flow passage of the exhaust gas (11) between the outer peripheral surface of the catalyst (C) corresponding to the major diameter portion (10 ₂₎ An exhaust system with a catalyst in an internal combustion engine.

The exhaust system with a catalyst in an internal combustion engine according to claim 1, wherein the exhaust pipe (P) is covered with a heat insulating cylinder (12).

In the heat retaining cylinder (12), a part of the exhaust pipe (P) is covered with the discoloration preventing cylinder (15), and the inner peripheral surface of the discoloration preventing cylinder (15) and the outer peripheral surface of the exhaust pipe (P). And between the outer peripheral surface of the anti-discoloration cylinder (15) and the inner peripheral surface of the heat retaining cylinder (12),
The exhaust system with a catalyst in an internal combustion engine according to claim 2, wherein an exhaust gas bypass hole (16) is provided in a portion of the exhaust pipe (P) covered with the discoloration prevention cylinder (15).