Mazda Motor Corporation

Takanobu Morimasa

Hirofumi Nishimura

Kiyotaka Mamiya

Tadataka Nakazumi

Michihiro Imada

Masanori Misumi

Ken Umehara

Exhaust gas temperature is raised after a cold engine start so as to rapidly activate a catalyst in an exhaust line by retarding an ignition timing at which an air-fuel mixture is fired in the engine to a point after top-dead-center during a certain time interval and promoting combustion of the air-fuel mixture, thereby accelerating the catalyst to attain its effective activation temperature after the cold engine start as quickly as possibly.

Method of and system for purifying exhaust gas for engines

During an air-fuel ratio feedback control based on an oxygen concentration in exhaust gases which converges an air-fuel ratio toward a target ratio suitable for a satisfactory purifying efficiency of a catalyst, the air-fuel ratio is coercively deflected so as to make a fuel mixture richer and leaner alternatively. An extent of deflection of the air-fuel ratio is set larger before the catalyst has not yet been activated sufficiently.

Air-fuel ratio control system for internal combustion engine

Growing community of inventors

Hiroshima, Japan

Takanobu Morimasa