Double air-fuel ratio sensor system in internal combustion engine
A method for controlling an air-fuel ratio in an internal combustion engine having catalyst means for removing pollutants in an exhaust gas, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of the catalyst means for detecting a concentration of a specific component in the exhaust gas, is described comprising the steps of: comparing an output of the upstream-side air-fuel ratio sensor with a first predetermined reference voltage; calculating an air-fuel ratio feedback correction amount in accordance with the comparison result of the output of the upstream-side air-fuel ratio sensor with the first predetermined reference voltage; comparing an output of the downstream-side air-fuel ratio sensor with a second predetermined reference voltage; calculating, in accordance with the comparison result of the output of the downstream-side air-fuel ratio sensor; adjusting the actual air-fuel ratio in accordance with the air-fuel ratio feedback correction amount and the air-fuel ratio feedback control parameter; determining whether the downstream-side air-fuel ratio sensor is in a normal state or in an abnormal state; and prohibiting the calculation of the air-fuel ratio feedback control parameter when the downstream-side air-fuel ratio sensor is in an abnormal state while continuing the calculation of the air-fuel ratio correction amount.
- Assignee:
- Toyota Jidosha Kabushiki Kaisha, Aichi
- Patent Number(s):
- US 4739614
- OSTI ID:
- 7007242
- Resource Relation:
- Patent File Date: Filed date 21 Feb 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
FUEL SYSTEMS
METERING
INTERNAL COMBUSTION ENGINES
EMISSION
POLLUTION CONTROL EQUIPMENT
METERS
AIR POLLUTION CONTROL
CATALYSTS
CONTROL SYSTEMS
CORRECTIONS
EXHAUST GASES
EXHAUST SYSTEMS
FEEDBACK
FUEL-AIR RATIO
OPERATION
POLLUTANTS
REMOVAL
CONTROL
ENGINES
EQUIPMENT
FLUIDS
GASEOUS WASTES
GASES
HEAT ENGINES
MEASURING INSTRUMENTS
POLLUTION CONTROL
WASTES
330100* - Internal Combustion Engines
330700 - Advanced Propulsion Systems- Emission Control
500200 - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)