Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1994-02-10
1995-03-28
Lazarus, Ira S.
Power plants
Internal combustion engine with treatment or handling of...
Methods
60276, 60277, 60285, 123674, 123703, F01N 320
Patent
active
054005922
ABSTRACT:
A catalytic diagnostic apparatus for determining whether a catalyst of an internal combustion engine has deteriorated as disclosed. Air-fuel ratio sensors are placed at the upstream and downstream sides of the catalytic converter, and the output signal from the upstream air-fuel sensor is used to control the air-fuel mixture provided to the engine via the fuel injectors, in a conventional closed loop operation. Diagnosis of the condition of the catalytic converter is performed only when selected engine operating parameters fall within a predetermined diagnostic range. When the engine is operated in the diagnostic range, the condition of the catalytic converter is analyzed by calculating a deterioration index based on a comparison of the variation of the output signals from the upstream and downstream air-fuel ratio sensors. In a preferred embodiment, a look-up table is provided to correct the deterioration index, based on the intake air flow rate to the engine, and on the cyclic frequency of the variation of the downstream air-fuel ratio sensor.
REFERENCES:
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patent: 5074113 (1991-12-01), Matsuoka
patent: 5090199 (1992-02-01), Ikuta
patent: 5097700 (1992-03-01), Nakane
patent: 5271223 (1993-12-01), Hoshi
patent: 5335493 (1994-08-01), Uchida
patent: 5337556 (1994-08-01), Aihara
patent: 5337557 (1994-08-01), Toyoda
Ishii Toshio
Mukaihira Takashi
Numata Akihito
Takaku Yutaka
Hitachi , Ltd.
Lazarus Ira S.
O'Connor Daniel J.
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