AIR-FUEL RATIO CONTROLLER FOR INTERNAL COMBUSTION ENGINE

Japanese Patent JP3721878

B2

PROBLEM TO BE SOLVED: To improve the control of an air-fuel ratio at a transient time by changing a control constant relating to an air-fuel ratio feedback control in accordance with an O2 sensor at a downstream side of a catalytic converter, and determining an air-fuel ratio feedback correction amount in accordance with the control constant and the output of an O2 sensor at an upstream side of the catalytic converter.
SOLUTION: O2 sensors 75, 76 are respectively mounted at upstream and downstream sides of a catalytic converter 62 mounted on an exhaust system for purifying an exhaust gas, and their sensor signals are input to an ECU 90. When the output of the O2 sensor at downstream side indicates rich in the ECU 90, the control constant relating to the air-fuel ratio feedback control is updated to a value for adjusting the air-fuel ratio to a lean side. On the other hand, when the output voltage of the O2 sensor at downstream side indicates lean, the control constant is updated to a value for adjusting the air-fuel ratio to a rich side. An air-fuel ratio feedback correction amount is operated on the basis of the control constant and the output of the O2 sensor 75 at upstream side to adjust the air-fuel ratio.

Harufumi Muto
Noritake Mitsuya

JP24033699A

November 30, 2005

August 26, 1999

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TOYOTA JIDOSHA KABUSHIKI KAISHA

F02D45/00; F02D41/14; (IPC1-7): F02D41/14; F02D45/00

JP63195351A
JP11082114A
JP8218853A
JP8177571A
JP8021283A

Takashi Ishida
Jun Tsuruta
Shigeru Tsuchiya
Masaya Nishiyama

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