Device for purifying the exhaust gas of an internal combustion engine

Abstract

In a device for purifying the exhaust gas of an internal combustion engine, a first auxiliary catalytic apparatus is arranged in one of the two exhaust passages upstream of the exhaust gas merging portion, a second auxiliary catalytic apparatus is arranged in the other of the two exhaust passages, an amount of catalyst carried on the second auxiliary catalytic apparatus is smaller than that on the first auxiliary catalytic apparatus, and only the cylinder-group corresponding to the one of the two exhaust passages is operated at the engine start.

1 . A device for purifying the exhaust gas of an internal combustion engine in which all cylinders of the multi-cylinders engine are divided into two cylinder-groups, each cylinder-group is provided with an exhaust passage from each exhaust manifold to an exhaust gas merging portion, and a main catalytic apparatus is arranged downstream of the exhaust gas merging portion, characterized in that a first auxiliary catalytic apparatus is arranged in one of the two exhaust passages upstream of said exhaust gas merging portion, a second auxiliary catalytic apparatus is arranged in the other of said two exhaust passages, an amount of catalyst carried on said second auxiliary catalytic apparatus is smaller than that on said first auxiliary catalytic apparatus, and only the cylinder-group corresponding to said one of said two exhaust passages is operated at the engine start.  
   
   
       2 . A device for purifying the exhaust gas of an internal combustion engine in which all cylinders of the multi-cylinders engine are divided into two cylinder-groups, each cylinder-group is provided with an exhaust passage from each exhaust manifold to an exhaust gas merging portion, and a main catalytic apparatus is arranged downstream of the exhaust gas merging portion, characterized in that a first auxiliary catalytic apparatus is arranged in one of the two exhaust passages upstream of said exhaust gas merging portion, a second auxiliary catalytic apparatus is arranged in the other of said two exhaust passages, a heat capacity of said first auxiliary catalytic apparatus is lower than that of said second auxiliary catalytic apparatus, and only the cylinder-group corresponding to said one of said two exhaust passages is operated at the engine start.  
   
   
       3 . A device for purifying the exhaust gas of an internal combustion engine in which all cylinders of the multi-cylinders engine are divided into two cylinder-groups, each cylinder-group is provided with an exhaust passage from each exhaust manifold to an exhaust gas merging portion, and a main catalytic apparatus is arranged downstream of the exhaust gas merging portion, characterized in that a first auxiliary catalytic apparatus is arranged in one of the two exhaust passages upstream of said exhaust gas merging portion, a second auxiliary catalytic apparatus is arranged in the other of said two exhaust passages, a catalyst of said first auxiliary catalytic apparatus actives at a lower temperature than an activation temperature of a catalyst of said second auxiliary catalytic apparatus, and only the cylinder-group corresponding to said one of said two exhaust passages is operated at the engine start.  
   
   
       4 . A device for purifying the exhaust gas of an internal combustion engine in which all cylinders of the multi-cylinders engine are divided into two cylinder-groups, each cylinder-group is provided with an exhaust passage from each exhaust manifold to an exhaust gas merging portion, and a main catalytic apparatus is arranged downstream of the exhaust gas merging portion, characterized in that a first auxiliary catalytic apparatus is arranged in one of the two exhaust passages upstream of said exhaust gas merging portion, a second auxiliary catalytic apparatus is arranged in the other of said two exhaust passages, an exhaust gas route length from the corresponding exhaust manifold to said first auxiliary catalytic apparatus is shorter than an exhaust gas route length from the corresponding exhaust manifold to said second auxiliary catalytic apparatus, and only the cylinder-group corresponding to said one of said two exhaust passages is operated at the engine starting.  
   
   
       5 . A device for purifying the exhaust gas of an internal combustion engine according to  claim 4 , characterized in that said second auxiliary catalytic apparatus is arranged in said other of said two exhaust passages immediately upstream of said exhaust gas merging portion.  
   
   
       6 . A device for purifying the exhaust gas of an internal combustion engine in which all cylinders of the multi-cylinders engine are divided into two cylinder-groups, each cylinder-group is provided with an exhaust passage from each exhaust manifold to an exhaust gas merging portion, and a main catalytic apparatus is arranged downstream of the exhaust gas merging portion, characterized in that a first auxiliary catalytic apparatus is arranged in one of the two exhaust passages upstream of said exhaust gas merging portion, a second auxiliary catalytic apparatus is arranged immediately downstream of said exhaust gas merging portion, and only the cylinder-group corresponding to said one of said two exhaust passages is operated at the engine start.