Device for purifying the exhaust gas of an internal combustion engine

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.

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.

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.

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.