Catalyst-attached muffler for internal combustion engine

Abstract

A catalyst-attached muffler includes an expansion chamber ( 25 ) defined by a cup-shaped fore-side outer wall panel ( 21 ) and a cup-shaped rear-side outer wall panel ( 22 ), both panels being removably attached to each other; a partition panel ( 23 ) interposed between the fore-side outer wall panel and the rear-side outer wall panel to partition the expansion chamber into a first expansion chamber ( 25 A) and a second expansion chamber ( 25 B). A closed-end cylindrical diffuser ( 40 ) is positioned in the first expansion chamber; and a gas-permeable exhaust gas-purifying catalyst ( 30 ) is inserted into and fixed to the diffuser, wherein exhaust gas from the exhaust port ( 10 ) of a cylinder of internal combustion engine is permitted to enter, via the catalyst, into the first expansion chamber, then to flow out of the first expansion chamber and to enter, via an opening ( 23 e ) formed in the partition panel, into the second expansion chamber, and to flow out of the second expansion chamber through an outlet ( 29 ) formed in the fore-side outer wall panel, thereby discharging the exhaust gas into external atmosphere.

1 . A muffler capable of cooperating with an exhaust port of a cylinder of an internal combustion engine, the muffler comprising: 
 an expansion chamber, the expansion chamber including a cup-shaped fore-side outer wall panel and a rear-side outer wall panel, both panels being removably secured to each other;    a partition panel interposed between the fore-side outer wall panel and the rear-side outer wall panel to partition the expansion chamber into a first expansion chamber and a second expansion chamber;    a diffuser positioned in the first expansion chamber; and    a catalyst inserted into and secured to the diffuser;    wherein exhaust gas from the exhaust port flows through the catalyst and is introduced into the first expansion chamber, then flows out of the first expansion chamber and is introduced into the second expansion chamber via an opening formed in the partition panel, and flows out of the second expansion chamber through an outlet formed in the fore-side outer wall panel.    
   
   
       2 . The muffler of  claim 1 , wherein a fore-end portion of the fore-side outer wall panel, a fore-end portion of the partition panel, and a flange portion formed at the fore-end of the diffuser are collectively secured to a portion of the exhaust port of the cylinder by bolts.  
   
   
       3 . The muffler of  claim 2 , wherein the head of at least one of the bolts is proximate to the portion of the exhaust port.  
   
   
       4 . The muffler of  claim 1 , wherein the catalyst is at least one of a cylindrical configuration and a prismatic configuration.  
   
   
       5 . The muffler of  claim 4 , wherein the catalyst is secured to the diffuser by spot welding.  
   
   
       6 . The muffler of  claim 1 , wherein the catalyst is secured to the diffuser by spot welding.  
   
   
       7 . The muffler of  claim 1 , wherein the catalyst is an oxidation catalyst formed of metallic carrier.  
   
   
       8 . The muffler of  claim 1 , further comprising a spark arrester screen secured to the opening formed in the partition panel.  
   
   
       9 . The muffler of  claim 1 , wherein a rear-end portion of the fore-side outer wall panel, a rear-end portion of the partition panel, and a fore-end portion of the rear-side outer wall panel are respectively formed into a first, second, and third collar-shaped portion and the first, second, and third collar-shaped portions are successively superimposed and collectively fastened together by bolts.  
   
   
       10 . A muffler capable of cooperating with an exhaust port of a cylinder of an internal combustion engine, the muffler comprising: 
 an expansion chamber, the expansion chamber including a cup-shaped fore-side outer wall panel and a cup-shaped rear-side outer wall panel, both panels being removably secured to each other;    a partition panel interposed between the fore-side outer wall panel and the rear-side outer wall panel to partition the expansion chamber into a first expansion chamber and a second expansion chamber;    a closed-end cylindrical diffuser positioned in the first expansion chamber; and    a gas-permeable exhaust gas-purifying catalyst inserted into and secured to the diffuser;    wherein exhaust gas from the exhaust port flows through the catalyst and is introduced into the first expansion chamber, then flows out of the first expansion chamber and is introduced into the second expansion chamber via an opening formed in the partition panel, and flows out of the second expansion chamber through an outlet formed in the fore-side outer wall panel.    
   
   
       11 . The muffler of  claim 10 , wherein a fore-end portion of the fore-side outer wall panel, a fore-end portion of the partition panel, and a flange portion formed at the fore-end of the diffuser are collectively secured to a brim portion of the exhaust port of the cylinder by bolts.  
   
   
       12 . The muffler of  claim 11 , wherein the head of at least one of the bolts is proximate to the brim portion of the exhaust port.  
   
   
       13 . The muffler of  claim 10 , wherein the catalyst has a cylindrical configuration and a prismatic configuration.  
   
   
       14 . The muffler of  claim 13 , wherein the catalyst is secured to the diffuser by spot welding.  
   
   
       15 . The muffler of  claim 10 , wherein the catalyst has a prismatic configuration.  
   
   
       16 . The muffler of  claim 15 , wherein the catalyst is secured to the diffuser by spot welding.  
   
   
       17 . The muffler of  claim 10 , wherein the catalyst is secured to the diffuser by spot welding.  
   
   
       18 . The muffler of  claim 10 , wherein the catalyst is an oxidation catalyst formed of metallic carrier.  
   
   
       19 . The muffler of  claim 10 , further comprising a spark arrester screen secured to the opening formed in the partition panel.  
   
   
       20 . The muffler of  claim 10 , wherein a rear-end portion of the fore-side outer wall panel, a rear-end portion of the partition panel, and a fore-end portion of the rear-side outer wall panel are respectively formed into a first, second, and third collar-shaped portion and the first, second, and third collar-shaped portions are successively superimposed and collectively fastened together by bolts.