Honda Giken Kogyo Kabushiki Kaisha

Yuichiro Tanabe

Kotaro Miyashita

Hirofumi Mutoh

Kenji Nakano

Akira Hashimoto

Hiroshi Yatani

Toshikatsu Takanohashi

Daisuke Shimizu

Hiroaki Hasumi

Mitsuo Hashizume

Akira Murakami

Mistuo Hashizume

Norio Moteki

An exhaust emission control system for an internal combustion engine is disclosed. The system includes a NOx removing device provided in an exhaust system of the engine for removing NOx contained in exhaust gases, and an oxygen concentration sensor provided in the exhaust system. The air-fuel ratio of the air-fuel mixture to be supplied to the engine is changed from a value which is leaner than the stoichiometric ratio to a value which is richer than the stoichiometric ratio. It is determined whether or not a sulfur oxide concentration in the exhaust gases is high according to a transient characteristic of an oxygen concentration detected by the oxygen concentration sensor after the air-fuel ratio is changed.

Exhaust emission control system for internal combustion engine

An exhaust emission control system for an internal combustion engine, having a nitrogen oxide removing device provided in an exhaust system of the internal combustion engine for absorbing nitrogen oxides contained in exhaust gases in an exhaust lean condition. The exhaust emission control system includes first and second oxygen concentration sensors respectively provided upstream and downstream of the nitrogen oxide removing device for detecting an oxygen concentration in the exhaust gases. The air-fuel ratio of an air-fuel mixture to be supplied to the engine is changed from a lean region to a rich region with respect to a stoichiometric ratio. An amount of reducing components flowing into the nitrogen oxide removing device from the time when an output value from the first oxygen concentration sensor has changed to a value indicative of a rich air-fuel ratio after enrichment of the air-fuel ratio is calculated. Deterioration of the nitrogen oxide removing device is determined according to the calculated amount of reducing components and an output value from the second oxygen concentration sensor.

An air-fuel ratio control system for an internal combustion engine includes an air-fuel ratio sensor arranged in an exhaust system thereof for generating an output substantially proportional in value to an air-fuel ratio of exhaust gases emitted from the engine. An amount of variation in combustion of the engine is detected. A desired air-fuel ratio of a mixture supplied to the engine is set to a value leaner than a stoichiometric air-fuel ratio based on the amount of variation in combustion of the engine, when the engine is in a predetermined operating condition. Feedback control of an air-fuel ratio of the mixture to the desired air-fuel ratio is carried out in response to the output from the air-fuel ratio sensor. The desired air-fuel ratio is set to a richer value than an immediately preceding value thereof when the amount of variation in combustion of the engine detected is large and to a leaner value than the immediately preceding value thereof when the amount of variation in combustion of the engine is small. A value of the desired air-fuel ratio set is learned as an actual lean limit of the air-fuel ratio for stable combustion of the engine. A rate of change of the desired air-fuel ratio is adjusted based on the learned value of the desired air-fuel ratio.

Air-fuel ratio control system for internal combustion engines

An air-fuel ratio control system for an internal combustion engine includes an air-fuel ratio sensor arranged in the exhaust system of the engine, for generating an output indicative of the air-fuel ratio of exhaust gases emitted from the engine. An ECU carries out feedback control of controlling the air-fuel ratio of a mixture supplied to the engine to a predetermined desired air-fuel ratio in response to the output from the air-fuel ratio sensor, by using at least one feedback control gain. A purge control valve purges evaporative fuel generated in the fuel tank to the engine. The at least one feedback control gain is set to a smaller value when the degree of influence of evaporative fuel purged by the purge control valve upon the air-fuel ratio of the mixture is larger, and set to a larger value when the degree of influence of the purged evaporative fuel upon the air-fuel ratio of the mixture is smaller.

There is provided a control system for an internal combustion engine. An amount of variation in the rotational speed of the engine is detected. A rotational speed variation reference value is calculated based on an averaged value of the detected amount of variation in the rotational speed of the engine. The detected amount of variation in the rotational speed of the engine is compared with the rotational speed variation reference value. The amount of fuel to be supplied to the engine is corrected based on results of the comparison.

Growing community of inventors

Wako, Japan

Yuichiro Tanabe