| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine having two cylinders, capable of preventing overheat of an exhaust emission control catalyst, or capable of controlling the temperature of the exhaust emission control catalyst in a proper temperature range, or capable of raising the temperature of the exhaust emission control catalyst, or capable of lowering the temperature of the exhaust emission control catalyst. <P>SOLUTION: This exhaust emission control device has a first cylinder 1A, #1 to #3 and second cylinders 2A and #4 to #6 cylinders. A first exhaust pipe 9A is connected to the first cylinder, and a second exhaust pipe 9B is connected to the second cylinder. An intermediate part of the first exhaust pipe and an intermediate part of the second exhaust pipe are mutually connected by a communicating tube 17. The exhaust emission control catalyst 14B is arranged in the second exhaust pipe on the downstream side of a part connected with the communicating tube. This device has exhaust gas quantity reducing means 16A and 16B for reducing quantity of exhaust gas flowing in the second exhaust pipe by passing through the communicating tube from the first exhaust pipe, when performing rich-lean combustion control for performing combustion by the air-fuel ratio richer than the stoichiometric air-fuel ratio in the air-fuel ratio of an air-fuel mixture in one cylinder, and performing the combustion by the air-fuel ratio leaner than the stoichiometric air-fuel ratio in the air-fuel ratio of the air-fuel mixture in the other cylinder. <P>COPYRIGHT: (C)2008,JPO&INPIT |
