Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1994-07-21
1996-10-29
Hart, Douglas
Power plants
Internal combustion engine with treatment or handling of...
Methods
60276, 60277, 60285, 123688, F01N 320
Patent
active
055687253
ABSTRACT:
In an internal combustion engine with oxygen sensors provided respectively upstream and downstream of an exhaust purification catalytic converter, the air-fuel ratio is feedback controlled based on an output of the second oxygen sensor only. When in this control situation, an output period of the first oxygen sensor becomes longer than that of the second oxygen sensor, response deterioration of the first oxygen sensor is judged to have occurred. Once the occurrence of response deterioration is determined, a proportional operating amount used in a proportional control of an air-fuel ratio feedback correction coefficient LMD for air-fuel ratio feedback control using the first oxygen sensor, is corrected in proportion to the response deterioration to thereby correct a deviation of the air-fuel ratio control point.
As a result, response deterioration of the first oxygen sensor can be diagnosed, and deviation of the air-fuel ratio control point due to the response deterioration can be avoided, so that control accuracy to the target air-fuel ratio can be ensured.
REFERENCES:
patent: 4980834 (1990-12-01), Ikeda
patent: 5168700 (1992-12-01), Furuya
patent: 5331808 (1994-07-01), Koike
patent: 5337558 (1994-08-01), Komatsu
patent: 5414995 (1995-05-01), Tokuda
Hart Douglas
Unisia Jecs Corporation
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