【０００１】
【発明の属する技術分野】本発明は、自動二輪車に搭載したエンジンから排出される排気ガスを触媒によって浄化する排気ガス浄化触媒付マフラ構造に関し、安価で振動に強く、騒音対策上又排気ガス対策上有利な耐久性ある触媒付マフラ構造に関する。
【０００２】
【従来の技術】従来の自動二輪車用の触媒付マフラ構造としては例えば特開２００１−１１５８３１号公報で知られているように、筒状マフラ内の最上流の消音室内に消音室内を横断するように円盤状の触媒を装着するとともに、同触媒を支持する支持部材にバイパス通路を設け、エンジン高出力、高回転時には排気ガスは触媒を迂回させていた。
又、従来一般に知られたセラミックハニカム触媒はメタルケースとその間に圧縮状態で配置されたワイヤーメッシュマット又はセラミック繊維マットを介在させていた。
【０００３】
【発明が解決しようとする課題】上記従来例の前者のように最上流の消音室内に触媒を設置するとすると、触媒の大きさ形状、バイパス通路の構造を最適なものとするためには従来の最上流消音室の構造を大幅に変更しなければならず、更に下流の複数のバッフルパイプ、バッフルプレート、消音室等全体構造にも影響し、結局マフラ全体の新規設計となる構造であった。
【０００４】又、上記従来例の後者のようにセラミックハニカム触媒を使用したものではセラミックハニカムが機関運転中に振動等によりマット間で踊り、セラミックハニカムの外面は摩耗し、破損するおそれもあった。更に又セラミックハニカム触媒は振動の少ない自動車用エンジンには使用できるが比較的振動の多い自動２輪用エンジンでは摩耗、破損が起こりやすい。その為、一般にはメタルハニカムを採用している。
【０００５】本発明は以上のような課題を解決するためのもので、浄化装置を備えていない筒状マフラ構造を他の構成を大幅に変更することなく触媒付マフラとする事ができると共に触媒そのものを安価で反応温度の早い触媒で生成し且つ振動に耐える触媒マウント構造を得たもので製作工程の省略化、安価製造、触媒体保持管理の安易化を目的とする。
【０００６】
【課題を解決するための手段】本発明の請求項１記載の触媒付マフラ構造は、エンジンの排気口から排出された排気ガスを、筒状マフラ内をバッフルプレートによって前後方向に複数の室に仕切った消音室と、各消音室にそれぞれ順次開口させた複数のバッフルパイプとによって消音する自動二輪車用のマフラ構造において、該マフラ内の最上流の消音室を区画構成するバッフルプレートを、セラミック多孔質３次元構造体にプラチナ、ロジウム、バナジウム等の貴金属若しくはサイロン、又はサイアロンとコバルト酸化物の触媒を担持させて生成したセラミック多孔質３次元触媒構造体で形成するとともにこのセラミック多孔質３次元触媒構造体から成るバッフルプレートに、一端が該最上流の消音室に開口し他端が下流の他の消音室に開口する最前部バッフルパイプを挿通配置せしめたもの。
【０００７】本発明の請求項２記載の触媒付マフラ構造は、セラミック多孔質３次元構造体は、外周のセラミックス充填体部とこのセラミックス充填体部の内周の多孔質セラミックス構造体部とを一体に成形して構成したもの。
【０００８】本発明の請求項３記載の触媒付マフラ構造は、セラミック多孔質３次元触媒構造体外周のセラミック充填体部周囲に薄いステンレス板をステンレスマット又はファイバーマット等の緩衝材を介在させ且つ同板に引っ張り張力を与えながら締付け固着し、この外周にステンレス板を装着したセラミック多孔質３次元触媒構造体をマフラ内筒に保持したもの。
【０００９】本発明の請求項４記載の触媒付マフラ構造は、セラミック多孔質３次元触媒構造体に排気ガスの流れ方向に沿って貫通した複数の小孔を穿設したものである。
【００１０】本発明の請求項５記載の触媒付マフラ構造は、最前部バッフルパイプの排気ガス流入側に近い位置に、排気ガス圧力によって同バッフルパイプの排気通路面積を可変とする排圧応動の開閉弁を装着したもの。
【００１１】
【発明の実施の形態】本発明を以下図について説明する。図は何れも本発明を示すもので、図１は自動二輪車用マフラの全体構造を示す縦断面図、図２は同要部拡大縦断面である。
【００１２】図１において、１は筒状マフラを示し、内部に適宜間隙を隔てて内筒２を装着している。筒状マフラ１の前部上流端にエンジン排気口に連結した排気管３を挿入装着し、後部下流端に排気ガスを大気に開放する尾管４を装着している。又この筒状マフラ１の内部を上流から下流の前後方向に複数の室に仕切るバッフルプレート５、６を固定し、これら各バッフルプレート５、６で仕切られた各室を順次連通させた複数のバッフルパイプ７を装着している。具体的には最上流の消音室Ａと最下流の消音室Ｂを連通するバッフルパイプ７１と、最上流の消音室Ａと最下流の消音室Ｂとの間の中央の消音室Ｃと、最下流の消音室Ｂとを連通するバッフルパイプ７２（想像線で表示）と、中央の消音室Ｃと大気開放のバッフルパイプ７３とから成る。なおバッフルパイプ７３は前記尾管４を兼ねている。
【００１３】図１において、下流のバッフルプレート６は従来公知の薄板製バッフルプレートで構成するが、最上流の消音室Ａを区画構成するバッフルプレート５は本発明の特徴ある構成部品となっている。即ち、バッフルプレート５はセラミック多孔質３次元触媒構造体５Ａから構成されている。
【００１４】更に、本発明は、最前部バッフルパイプ７１の排気ガス流入側に近い位置に、排気ガス圧力によって同バッフルパイプ７１内の排気通路面積を可変とする排圧応動の開閉弁１１を装着したことを特徴とするものである。以下その構成を詳記する。
【００１５】図２において、上記セラミック多孔質３次元触媒構造体５Ａは、セラミック多孔質３次元構造体Ｘに触媒を担持させて得たもので、セラミック多孔質３次元触媒構造体Ｘは例えば、排気通路に設置する触媒体の形状に合わせて形成した多孔質ウレタンフォームを型内の定位置にセットした後、アルミナと水とバインダーとから成る混合物で作ったスラリーを注入し、これを大気中で加熱、焼成させてセラミック発泡多孔質３次元構造体Ｘを得る。そしてこのセラミック発泡多孔質３次元構造体Ｘにプラチナ（Ｐｔ）、ロジウム（Ｒｈ）、パラジウム（Ｐｄ）などの貴金属若しくはサイアロン、又はサイアロンとコバルト酸化物の触媒を担持させて成形したセラミック多孔質３次元触媒構造体５Ａを得る。
【００１６】尚、セラミック多孔質３次元構造体Ｘは上記発泡ウレタンを利用して成形する方法以外に適宜多孔質構造体を得る方法でもよい。たとえば針金状３次元構造体あるいは麺状３次元構造体のごとく適宜迷路的隙間を設けたセラミック３次元構造体に触媒を担持させたものでもよい。
【００１７】上記セラミック多孔質３次元触媒構造体５Ａから成るバッフルプレート５に、一端が該最上流の消音室Ａに開口し他端が下流の消音室Ｂに開口する最前部バッフルパイプ７１を貫通して挿通配置せしめたものである。
【００１８】上記セラミック多孔質３次元構造体Ｘは、外周のセラミック充填体部Ｘ２とこのセラミック充填体部Ｘ２の内周の多孔質セラミック構造体部Ｘ１とを一体に成形して構成したもので、同じく、バッフルパイプ７１が貫通する位置のセラミック多孔質３次元構造体の穴部外周のセラミック充填部Ｘ３とこのセラミック充填体Ｘ３の内周の多孔質セラミック構造体Ｘ１とを一体に成型したものである。
【００１９】そして上記して得たセラミック多孔質３次元触媒構造体５Ａ外周のセラミック充填部Ｘ２周囲にステンレスマット又はファイバーマット等の緩衝材９を介在させて、且つ同ステンレス板８をステンレスマット又はファイバーマットを圧縮した状態で固着させる。そして外周にステンレス板８を固着したセラミック多孔質３次元触媒構造体５Ａをマフラー内筒２に装着保持したものである。尚、セラミックス充填体部Ｘ１の周囲に直接薄いステンレス板を同板に引っ張り張力を与えながら締付け固着した後、上記の如くステンレスマット又はファイバーマット等の緩衝材９を介在させて更にその外周にステンレス板８を固着させてマフラー内筒２に装着保持する方法でもよい。
【００２０】１０は前記セラミック多孔質３次元触媒構造体５Ａの排気ガスの流れ方向に沿って貫通して穿設した複数の小孔である。この小孔１０は、排気ガスを浄化している時、急激な加速時とか低開度高負荷運転時のように一時的に排圧が急上昇したりした時にセラミック多孔質３次元触媒構造体５Ａが損傷することを防いだり、セラミック多孔質３次元触媒構造体５Ａの排気ガス通過量を微調整するために設けたものである。
【００２１】又、最前部バッフルパイプ７１の排気ガス流入側に近い位置に、排気ガス圧力によって同バッフルパイプの排気通路面積を可変とする排圧応動の開閉弁１１を装着したもので、具体的にはバッフルパイプ７１内部形状と略相似形の円板１２の上方をピン１３によって回動自在に支持し下方に錘１４設け、若しくは必要に応じ円板１２を通路を閉じる方向に付勢したバネを備えると円板の妄動を防ぐ事ができる。
【００２２】上記構成の作用を説明すると、エンジンから排出された排気ガスは、基本的には排気管３、最上流の消音室Ａ、最前部のバッフルパイプ７１、最下流の消音室Ｂ、バッフルパイプ７２、中央の消音室Ｃ、尾管４を経由して拡散膨張干渉作用をし消音し大気に放出される。そして本願発明は、最上流の消音室Ａを区画構成するバッフルプレート５をセラミック多孔質３次元触媒構造体５Ａで構成し且つ、最前部バッフルパイプ７１の排気ガス流入側に近い位置に、排気ガス圧力によって同バッフルパイプ７１内の排気通路面積を可変とする排圧応動の開閉弁１１を装着した構成としたので、アイドリング時や低速回転時の如く排気ガス圧力が低い時はバッフルパイプ７１内の開閉弁１１を大きく開けることができず、結局多くの排気ガスは、セラミック多孔質３次元触媒構造体５Ａを通過することとなりここで浄化される。また開閉弁１１の開閉具合と排気ガス流量、圧力などの微妙な変化はセラミック多孔質３次元触媒構造体５Ａ流れ方向に沿って貫通して穿設した複数の小孔１０の太さや配置位置若しくは数によって調整する。
【００２３】そしてエンジン回転が中速から高速回転に移行すると、前記バッフルパイプ７１内の開閉弁１１は排気圧で大きく開き多くの排気ガスはこのバッフルパイプ７１内を通って他の消音室Ｂに向かい通常の消音作用を行い排出される。このように開閉弁１１が開放した時は、最上流の消音室Ａを区画構成するバッフルプレート５即ちセラミック多孔質３次元触媒構造体５Ａでの浄化効率は低下するが、現状の自動二輪車の排気ガス浄化規制には対応可能である。
【００２４】
【発明の効果】本発明の請求項１記載の触媒付マフラ構造によれば、最前部のバッフルプレートを、セラミック多孔質３次元構造体に触媒を担持させて生成したセラミック多孔質３次元触媒構造体で形成したので、従来の如く消音室内に円盤状触媒を装着したのに比べ、他の消音機能を果たす構成例えば後部のバッフルパイプ、バッフルプレートおよび内筒、外筒等のマフラ構造全体を大幅に変更しなくても容易に触媒を装着する事ができる。
又、触媒そのものも安価で反応温度の早い触媒で生成したので、価格の廉価な自動二輪車に好適であり且つ製作工程の省略化、安価製造、触媒体保持管理の安易となる。
【００２５】本発明の請求項２記載の触媒付マフラ構造によれば、セラミック多孔質３次元構造体は、外周のセラミックス充填体部とこのセラミックス充填体部の内周の多孔質セラミックス構造体部とを一体に成形して構成したものでマフラ内筒にマウント支持させる時支持部が多孔質部分ではなくセラミックスが充填された支持部となるので多孔質部が破損したり損傷するおそれがすくない。比較的振動の多い自動２輪用エンジンの触媒マウント構造に適用して効果大である。
【００２６】本発明の請求項３記載の触媒付マフラ構造は、セラミックス充填体部周囲に薄いステンレス板をステンレスマット又はファイバーマット等の緩衝材を介在させて締付け固着し、このステンレス板外周上にてマフラ筒に保持したので前記請求項２記載の構成と相乗しハニカムセラミック触媒のように厳密に接触面圧を管理する必要が無くクッション性能を長期にわたって維持できる。
【００２７】本発明の請求項４記載の触媒付マフラ構造は、セラミック多孔質３次元触媒構造体に貫通した複数の小孔を穿設したので、急激な加速時とか低開度高負荷運転時のように一時的に排圧が急上昇したりした時にセラミック多孔質３次元触媒構造体が損傷することを防いだり、排気ガス通過量を微調整することができる。
【００２８】更に本発明の請求項５記載の触媒付マフラ構造は、最前部バッフルパイプの排気ガス流入側に近い位置に、排気ガス圧力によって同バッフルパイプの排気通路面積を可変とする排圧応動の開閉弁を装着したので、エンジン作動状態に応じて前記セラミック多孔質３次元触媒構造体にかかる排気抵抗を効果的に変化させることができる。
【図面の簡単な説明】
【図１】本発明の触媒付マフラ構造の全体縦断面図。
【図２】同要部拡大縦断面図。
【符号の説明】
１．マフラ外筒
５．バッフルプレート
５Ａ．セラミック多孔質３次元触媒構造体
７．バッフルパイプ
７１．最前部バッフルパイプ
８．ステンレス板
９．緩衝材
１０．小孔
１１．開閉弁
Ａ．最上流消音室
Ｂ．最下流消音室
Ｘ．セラミック多孔質３次元構造体
Ｘ２．セラミックス充填部
Ｘ１．多孔質セラミックス構造体部
Ｘ３．セラミックス充填部[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler structure with an exhaust gas purifying catalyst for purifying exhaust gas discharged from an engine mounted on a motorcycle by a catalyst, and is inexpensive and resistant to vibration, noise and exhaust gas. The present invention relates to an advantageous and durable muffler structure with a catalyst.
[0002]
2. Description of the Related Art As a conventional muffler structure with a catalyst for a motorcycle, for example, as disclosed in Japanese Patent Application Laid-Open No. 2001-115831, a muffler with a most upstream muffler inside a cylindrical muffler crosses the muffler. In addition, a disk-shaped catalyst is mounted on the support member, and a bypass passage is provided in a support member for supporting the catalyst, so that the exhaust gas bypasses the catalyst at high engine output and high rotation.
Further, conventionally known ceramic honeycomb catalysts have interposed a metal mesh and a wire mesh mat or a ceramic fiber mat disposed in a compressed state therebetween.
[0003]
Assuming that the catalyst is installed in the silence chamber at the uppermost stream as in the former case of the above-mentioned conventional example, the conventional size and shape of the catalyst and the structure of the bypass passage are required in order to optimize the size of the catalyst. The structure of the most upstream muffler had to be drastically changed, and the overall structure of a plurality of baffle pipes, baffle plates, mufflers and the like further downstream was affected, resulting in a new design of the entire muffler.
Further, in the case of using the ceramic honeycomb catalyst as in the latter case of the above-mentioned conventional example, the ceramic honeycomb dances between the mats due to vibration or the like during the operation of the engine, and the outer surface of the ceramic honeycomb may be worn out and damaged. . Further, the ceramic honeycomb catalyst can be used for an automobile engine having less vibration, but is likely to be worn and damaged in a motorcycle engine having relatively large vibration. For this reason, metal honeycombs are generally used.
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a cylindrical muffler structure without a purifying device can be made into a muffler with a catalyst without significantly changing other structures. It has a catalyst mount structure which is produced by using a catalyst which is inexpensive and has a high reaction temperature and which withstands vibration. The object of the present invention is to omit a manufacturing process, manufacture at low cost, and facilitate the maintenance and management of a catalyst body.
[0006]
According to a first aspect of the present invention, there is provided a muffler structure with a catalyst, wherein exhaust gas discharged from an exhaust port of an engine is divided into a plurality of chambers in a front-rear direction by a baffle plate in a cylindrical muffler. In a muffler structure for a motorcycle in which mufflers are muffled by a partitioned muffler chamber and a plurality of baffle pipes sequentially opened in the muffler chambers, a baffle plate defining a muffler muffler chamber in the muffler has a ceramic porous plate. And a noble metal such as platinum, rhodium, vanadium or the like, or a ceramic porous three-dimensional catalyst structure formed by supporting a catalyst of sialon and cobalt oxide on the porous three-dimensional structure. One end of the baffle plate is open to the uppermost muffler chamber and the other end is opened to another muffler chamber downstream. That the foremost baffle pipe was allowed inserted and arranged for.
In the muffler structure with a catalyst according to a second aspect of the present invention, the ceramic porous three-dimensional structure comprises a ceramic filler portion on the outer periphery and a porous ceramic structure portion on the inner periphery of the ceramic filler portion. One that is formed by integral molding.
In the muffler structure with a catalyst according to a third aspect of the present invention, a thin stainless plate is interposed with a cushioning material such as a stainless mat or a fiber mat around the ceramic filler around the ceramic porous three-dimensional catalyst structure. A ceramic porous three-dimensional catalyst structure having a stainless steel plate mounted on the outer periphery of the plate and holding the muffler inner cylinder by tightening and fixing the plate while applying a tensile force to the plate.
According to a fourth aspect of the present invention, there is provided a muffler structure with a catalyst, wherein a plurality of small holes are formed in a porous ceramic three-dimensional catalyst structure along a flow direction of exhaust gas.
According to a fifth aspect of the present invention, there is provided a muffler structure with a catalyst, which is located at a position close to an exhaust gas inflow side of a foremost baffle pipe and which has an exhaust pressure responsive to change an exhaust passage area of the baffle pipe by exhaust gas pressure. With an on-off valve.
[0011]
BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIGS. 1 and 2 show the present invention. FIG. 1 is a longitudinal sectional view showing the entire structure of a muffler for a motorcycle, and FIG.
In FIG. 1, reference numeral 1 denotes a cylindrical muffler, in which an inner cylinder 2 is mounted with an appropriate gap therebetween. An exhaust pipe 3 connected to an engine exhaust port is inserted and mounted at a front upstream end of the cylindrical muffler 1, and a tail pipe 4 for releasing exhaust gas to the atmosphere is mounted at a rear downstream end. Also, a plurality of baffle plates 5, 6 that partition the inside of the cylindrical muffler 1 into a plurality of chambers in the front-rear direction from upstream to downstream are fixed, and a plurality of chambers partitioned by the baffle plates 5, 6 are sequentially communicated. The baffle pipe 7 is attached. More specifically, a baffle pipe 71 that connects the most upstream muffling chamber A and the most downstream muffling chamber B, a central muffling chamber C between the most upstream muffling chamber A and the most downstream muffling chamber B, A baffle pipe 72 (indicated by an imaginary line) communicating with the downstream silencing chamber B, a central silencing chamber C and a baffle pipe 73 open to the atmosphere. The baffle pipe 73 also serves as the tail pipe 4.
In FIG. 1, the downstream baffle plate 6 is constituted by a conventionally known thin plate baffle plate, and the baffle plate 5 defining the uppermost-stream silencing chamber A is a characteristic component of the present invention. . That is, the baffle plate 5 is composed of the ceramic porous three-dimensional catalyst structure 5A.
Further, according to the present invention, an exhaust-pressure-responsive opening / closing valve 11 for varying the exhaust passage area in the baffle pipe 71 by the exhaust gas pressure is mounted at a position near the exhaust gas inflow side of the foremost baffle pipe 71. It is characterized by having done. Hereinafter, the configuration will be described in detail.
In FIG. 2, the ceramic porous three-dimensional catalyst structure 5A is obtained by supporting a catalyst on a ceramic porous three-dimensional structure X. After setting the porous urethane foam formed in accordance with the shape of the catalyst body installed in the exhaust passage in a fixed position in the mold, a slurry made of a mixture of alumina, water, and a binder is injected, and the slurry is poured into the atmosphere. To form a ceramic foamed porous three-dimensional structure X. The ceramic porous body 3 is formed by carrying a noble metal such as platinum (Pt), rhodium (Rh), or palladium (Pd) or a catalyst of sialon and cobalt oxide on the ceramic foamed porous three-dimensional structure X. A five-dimensional catalyst structure 5A is obtained.
Incidentally, the ceramic porous three-dimensional structure X may be a method of appropriately obtaining a porous structure other than the method of molding using urethane foam. For example, the catalyst may be supported on a ceramic three-dimensional structure provided with an appropriate labyrinth gap, such as a wire-like three-dimensional structure or a noodle-like three-dimensional structure.
The baffle plate 5 composed of the ceramic porous three-dimensional catalyst structure 5A penetrates a foremost baffle pipe 71 having one end open to the most upstream muffler chamber A and the other end opening to the lower muffler chamber B. It is inserted and arranged.
The ceramic porous three-dimensional structure X is formed by integrally molding a ceramic filler portion X2 on the outer periphery and a porous ceramic structure portion X1 on the inner periphery of the ceramic filler portion X2. Similarly, a ceramic filling portion X3 around the hole of the ceramic porous three-dimensional structure at a position where the baffle pipe 71 penetrates and a porous ceramic structure X1 inside the ceramic filling body X3 are integrally molded. It is.
Then, a buffer material 9 such as a stainless mat or a fiber mat is interposed around the ceramic filled portion X2 on the outer periphery of the ceramic porous three-dimensional catalyst structure 5A obtained above, and the stainless steel plate 8 is connected to the stainless mat or the mat. The fiber mat is fixed in a compressed state. A ceramic porous three-dimensional catalyst structure 5A having a stainless steel plate 8 fixed to the outer periphery is mounted and held on the muffler inner cylinder 2. After a thin stainless steel plate is directly tightened and fixed around the ceramic filler portion X1 while applying a tensile force to the plate, a stainless steel mat or a fiber mat or the like cushioning material 9 is interposed as described above, and a stainless steel plate is further formed around the periphery. A method in which the plate 8 is fixed and mounted and held on the muffler inner cylinder 2 may be used.
Reference numeral 10 denotes a plurality of small holes penetrating through the ceramic porous three-dimensional catalyst structure 5A along the flow direction of the exhaust gas. The small holes 10 are used for purifying the exhaust gas, or when the exhaust pressure temporarily rises temporarily, such as during rapid acceleration or low load high load operation, or the like. This is provided to prevent damage to the gas and finely adjust the amount of exhaust gas passing through the ceramic porous three-dimensional catalyst structure 5A.
Further, an exhaust pressure-responsive opening / closing valve 11 for changing the exhaust passage area of the baffle pipe by the exhaust gas pressure is mounted at a position near the exhaust gas inflow side of the foremost baffle pipe 71. A spring which rotatably supports an upper part of a disk 12 having a shape substantially similar to the internal shape of the baffle pipe 71 by a pin 13 and provides a weight 14 below the disk 12, or biases the disk 12 in a direction for closing the passage as necessary. With it, delusion of the disk can be prevented.
Explaining the operation of the above construction, the exhaust gas discharged from the engine is basically supplied to the exhaust pipe 3, the most upstream silencer A, the foremost baffle pipe 71, the most downstream silencer B, the baffle Via the pipe 72, the central silencer C, and the tailpipe 4, they diffuse and interfere with each other and silence and are released to the atmosphere. According to the invention of the present application, the baffle plate 5 defining the uppermost-stream silencing chamber A is constituted by the ceramic porous three-dimensional catalyst structure 5A, and the exhaust gas is located at a position near the exhaust gas inflow side of the foremost baffle pipe 71. When the exhaust gas pressure is low, such as during idling or low speed rotation, the baffle pipe 71 has an exhaust pressure responsive on-off valve 11 that changes the exhaust passage area in the baffle pipe 71 by pressure. Since the on-off valve 11 cannot be opened greatly, a large amount of exhaust gas eventually passes through the ceramic porous three-dimensional catalyst structure 5A and is purified there. Further, subtle changes in the opening / closing state of the on-off valve 11, the exhaust gas flow rate, the pressure, and the like are determined by the thickness and the arrangement position of the plurality of small holes 10 penetrating along the flow direction of the ceramic porous three-dimensional catalyst structure 5A. Adjust by number.
When the engine speed shifts from a middle speed to a high speed, the on-off valve 11 in the baffle pipe 71 opens greatly due to the exhaust pressure, and a large amount of exhaust gas passes through the baffle pipe 71 to another muffler chamber B. It has a normal silencing effect opposite and is discharged. When the on-off valve 11 is opened in this manner, the purification efficiency of the baffle plate 5 that defines the uppermost-stream silencing chamber A, that is, the ceramic porous three-dimensional catalyst structure 5A is reduced. It can respond to gas purification regulations.
[0024]
According to the muffler structure with a catalyst according to the first aspect of the present invention, a ceramic porous three-dimensional catalyst structure is obtained by forming a foremost baffle plate by carrying a catalyst on a ceramic porous three-dimensional structure. Because it was formed with a body, compared to installing a disk-shaped catalyst in the silencing chamber as in the past, the structure that fulfills other silencing functions, such as the rear baffle pipe, baffle plate, and the entire muffler structure such as the inner cylinder and outer cylinder The catalyst can be easily mounted without changing to.
In addition, since the catalyst itself is produced using a catalyst that is inexpensive and has a fast reaction temperature, it is suitable for a motorcycle that is inexpensive, and simplifies the manufacturing process, reduces manufacturing costs, and facilitates the maintenance and management of the catalyst body.
According to the muffler structure with a catalyst according to claim 2 of the present invention, the ceramic porous three-dimensional structure comprises a ceramic filler portion on the outer periphery and a porous ceramic structure portion on the inner periphery of the ceramic filler portion. When the muffler inner cylinder is mounted and supported, since the supporting portion is not a porous portion but a supporting portion filled with ceramics, the porous portion is less likely to be damaged or damaged. It is highly effective when applied to the catalyst mount structure of a motorcycle engine that has relatively large vibrations.
In the muffler structure with a catalyst according to a third aspect of the present invention, a thin stainless steel plate is fastened and fixed around the ceramic filler with a buffer material such as a stainless steel mat or a fiber mat interposed therebetween. Since it is held in the muffler cylinder, it is not necessary to strictly control the contact surface pressure as in the case of the honeycomb ceramic catalyst in synergy with the structure of the second aspect, and the cushion performance can be maintained for a long time.
In the muffler structure with catalyst according to a fourth aspect of the present invention, a plurality of small holes penetrating the porous ceramic three-dimensional catalyst structure are provided, so that the muffler structure can be used during rapid acceleration or low load and high load operation. As described above, it is possible to prevent the ceramic porous three-dimensional catalyst structure from being damaged when the exhaust pressure rises temporarily, and to finely adjust the amount of exhaust gas passing.
Further, according to the muffler structure with a catalyst according to the fifth aspect of the present invention, the exhaust pressure responsive to the exhaust baffle pipe at the position near the exhaust gas inflow side of the foremost baffle pipe can vary the exhaust passage area of the baffle pipe. The exhaust resistance applied to the ceramic porous three-dimensional catalyst structure can be effectively changed according to the operating state of the engine.
[Brief description of the drawings]
FIG. 1 is an overall longitudinal sectional view of a muffler structure with a catalyst of the present invention.
FIG. 2 is an enlarged vertical sectional view of the main part.
[Explanation of symbols]
1. Muffler outer cylinder5. Baffle plate 5A. 6. Ceramic porous three-dimensional catalyst structure Baffle pipe 71. 7. Front baffle pipe Stainless steel plate 9. Cushioning material10. Small holes 11. On-off valve A. Uppermost sound deadening room B. Lowermost sound deadening chamber X. Ceramic porous three-dimensional structure X2. Ceramic filling part X1. Porous ceramic structure X3. Ceramics filling section
