Air-fuel ratio control system for internal combustion engines

摘要

There is provided an air-fuel ratio control system for an internal combustion. An air-fuel ratio sensor arranged in the exhaust system detects an air-fuel ratio of exhaust gases emitted from the engine. An amount of fuel to be supplied to the engine is controlled in response to the output from the air-fuel ratio sensor by using a controller of a recurrence formula type, such that an air-fuel ratio of a mixture supplied to the engine is converged to a desired air-fuel ratio, to thereby effect feedback control of the air-fuel ratio of the mixture. The desired air-fuel ratio is determined based on operating conditions of the engine. The desired air-fuel ratio is smoothed when the engine is in a predetermined operating condition. The feedback control of the air-fuel ratio is carried out by the use of the smoothed desired air-fuel ratio.