| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio control system for an internal combustion engine capable of quickly and properly eliminating variation in air-fuel ratio between a plurality of cylinders. SOLUTION: The air-fuel ratio control system 1 controls the amount TOUTi of fuel to be supplied to the plurality of cylinders #1 to #4, on a cylinder-by-cylinder basis, thereby controlling the air-fuel ratio of a mixture supplied to each of the plurality of cylinders #1 to #4. An air-fuel ratio sensor 14 delivers to an ECU 2 a detection signal indicative of the air-fuel ratio of exhaust gases emitted from the cylinders #1 to #4 and merged. The ECU 2 of the air-fuel ratio control system 1 filters the detection signal KACT output from the air-fuel ratio sensor 14 such that components in respective bands of predetermined frequencies fr1 and fr2 are allowed to pass therethrough. A fuel injection amount TOUTi is determined, on a cylinder-by-cylinder basis, according to the output KACT_Fc or KACT_Fr such that the amplitude of the output converges to a predetermined value (steps 10 and 11). COPYRIGHT: (C)2005,JPO&NCIPI
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