Power plants – Internal combustion engine with treatment or handling of... – Having sensor or indicator of malfunction – unsafeness – or...
Patent
1992-11-25
1994-03-01
Kamen, Noah P.
Power plants
Internal combustion engine with treatment or handling of...
Having sensor or indicator of malfunction, unsafeness, or...
60274, 60276, 60285, F01N 300
Patent
active
052896781
ABSTRACT:
Apparatus and method are disclosed for monitoring catalytic converter efficiency in treating exhaust gas, for example from an internal combustion engine of a motor vehicle. In a dual closed loop fuel control system having switch-type exhaust gas oxygen (EGO) sensors located upstream and downstream of the catalytic converter, the number of times the downstream EGO sensor switches from rich to lean and/or visa versa is compared to the number of times the upstream EGO sensor switches during normal system operation over the course of a test period. A catalytic converter efficiency value is determined by calculating the ratio of the switching frequencies. The impact of the speed and load dependence of the downstream EGO sensor switching frequency can be reduced by a normalizing effect of the frequency ratio calculation. The efficiency value is compared to a stored value predetermined to correspond to a minimum acceptable efficiency of the catalytic converter. A failure signal can be generated when the efficiency value indicates catalytic converter efficiency below the minimum acceptable level.
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Clemens et al.--SAE Technical Paper 900062, Detection of Catalyst Performance Loss Using On-Board Diagnostics, Feb. 26--Mar. 2, 1990.
Ford Motor Company
Kamen Noah P.
May Roger L.
Melotik Lorraine S.
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