Double air-fuel ratio sensor system having improved response characteristics

Patent · Tue Nov 24 04:00:00 EST 1987

OSTI ID:5803964

Katsuno, T; Nagai, T; Masui, T; Satou, Y

A method for controlling the air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream, respectively, of the catalyst converter for detecting the concentration of a specific component in the exhaust gas is described comprising the steps of: adjusting an actual air-fuel ratio in accordance with the outputs of the upstream-side and downstream-side air-fuel ratio sensors; detecting a coolant temperature of the engine prohibiting the adjustment of the actual air-fuel ratio by the output of the downstream-side air-fuel ratio sensor in accordance with the detected coolant temperature. The adjustment prohibiting step comprises the steps of: determining whether or not the engine is started; calculating a reference duration in accordance with the coolant temperature detected immediately after the engine is started or after a predetermined time period has passed after the engine is started; calculating a duration after the engine is started; and determining whether or not the duration is smaller than the reference duration, detecting a deterioration degree of the downstream-side air-fuel ratio sensor; and correcting the reference duration in accordance with the deterioration degree.

• Assignee: Jidosha Kabushiki Kaisha, Aichi
• Patent Number(s): US 4707984
• OSTI ID: 5803964
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330100* -- Internal Combustion Engines
330700 -- Advanced Propulsion Systems-- Emission Control
500200 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION CONTROL
CATALYTIC CONVERTERS
CONTROL
CONTROL SYSTEMS
ENGINES
EQUIPMENT
EXHAUST GASES
FLUIDS
FUEL INJECTION SYSTEMS
FUEL SYSTEMS
FUEL-AIR RATIO
GASEOUS WASTES
GASES
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
MONITORING
OPERATION
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
TEMPERATURE MONITORING
WASTES