Double air-fuel ratio sensor system having double-skip function

Patent · Tue Jan 26 00:00:00 EST 1988

OSTI ID:5401141

Katsuno, T

A method for controlling the air-fuel ratio in an internal combustion engine is described having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of the catalyst converter for detecting a concentration of a specific component in an exhaust gas, comprising the steps of: comparing the output of the upstream-side air-fuel ratio sensor with a first predetermined value; gradually changing a first air-fuel ratio correction amount in accordance with a result of the comparison of the output of the upstream-side air-fuel ratio sensor with the predetermined value; shifting the first air-fuel ratio correction amount by a first skip amount during a predetermined time period after the result of the comparison of the upstream-side air-fuel ratio sensor is changed; shifting the first air-fuel ratio correction amount by a second skip amount smaller than the first skip amount after the predetermined time period has passed; comparing the output of the downstream-side air-fuel ratio with a second predetermined value, calculating a second air-fuel ratio correction amount in accordance with the comparison result of the output of the downstream-side air-fuel ratio sensor with the second predetermined value; and adjusting the actual air-fuel ratio in accordance with the first and second air-fuel ratio correction amounts; wherein the gradually-changing step comprises the steps of: gradually decreasing the first air-fuel ratio correction amount when the output of the upstream-side air-fuel sensor is on the rich side with respect to the first predetermined value; and gradually increasing the first air-fuel ratio correction amount when the output of the upstream-side air-fuel sensor is on the lean side with respect to the first predetermined value.

• Assignee: Toyota Jidosha Kabushiki Kaisha, Aichi
• Patent Number(s): US 4720973
• OSTI ID: 5401141
• Resource Relation: Patent File Date: Filed date 19 Feb 1986
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
54 ENVIRONMENTAL SCIENCES
FUEL INJECTION SYSTEMS
METERS
FUEL-AIR RATIO
METERING
INTERNAL COMBUSTION ENGINES
CATALYTIC CONVERTERS
DESIGN
AIR POLLUTION CONTROL
CONTROL SYSTEMS
EXHAUST GASES
OPERATION
CONTROL
ENGINES
EQUIPMENT
FLUIDS
FUEL SYSTEMS
GASEOUS WASTES
GASES
HEAT ENGINES
MEASURING INSTRUMENTS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
WASTES
330100* - Internal Combustion Engines
500200 - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)