| 摘要 |
PROBLEM TO BE SOLVED: To make the air-fuel ratio of a first cylinder group and the air-fuel ratio of a second cylinder group conform to a common first target air-fuel ratio respectively, and to make the average air-fuel ratio of exhaust gas in a common exhaust passage conform to a second target air-fuel ratio while making the air-fuel ratio of the first cylinder group and the air-fuel ratio of the second cylinder group different from each other. SOLUTION: When the air-fuel ratio of the first cylinder group 1a and the air-fuel ratio of the second cylinder group 1b should be conformed to a common stoichiometric air-fuel ratio, the air-fuel ratio control device feedback controls air-fuel ratios of the first and second cylinder groups respectively based on outputs from air-fuel ratio sensors 14a, 14b arranged in first and second exhaust branch pipes 12a, 12b. When the average air-fuel ratio of exhaust gas in a common exhaust pipe 13 should be conformed to the stoichiometric air-fuel ratio while make a difference between the air-fuel ratio of the first cylinder group and the air-fuel ratio of the second cylinder group, the air-fuel ratio control device feedback controls the air-fuel ratio of the first cylinder group and the air-fuel ratio of the second cylinder group based on an output from the air-fuel ratio sensor 16 disposed in the common exhaust pipe. COPYRIGHT: (C)2008,JPO&INPIT
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