Method and apparatus for controlling air-fuel ratio in internal combustion engine

Patent · Tue Feb 24 04:00:00 EST 1987

OSTI ID:7083998

Kobayashi, N; Ito, T

A method is described for controlling the air-fuel ratio in an internal combustion engine comprising the steps of: detecting the concentration of a specific composition in the exhaust gas; calculating a target air-fuel ratio on the lean side with respect to the stoichiometric air-fuel ratio in accordance with predetermined parameters of the engine; detecting the temperature of the engine; adjusting the calculated target air-fuel ratio in accordance with the detected temperature of the engine, the adjusting step including the further steps of: calculating an allowed limit value of the target air-fuel ratio on the lean side in accordance with the detected temperature of the engine, when the detected temperature of the engine is lower than a definite temperature; determining whether or not the target air-fuel ratio is on the lean side with respect to the allowed limit value; and replacing the target air-fuel ratio with the allowed limit value only when the target air-fuel ratio is on the lean side with respect to the allowed limit value; and controlling the feedback of the air-fuel ratio of the engine in accordance with the detected concentration of the specific composition so that the air-fuel ratio of the engine is close to the adjusted target air-fuel ratio.

• Assignee: Toyota Jidosha Kabushiki Kaisha, Toyota
• Patent Number(s): US 4644921
• OSTI ID: 7083998
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330100* -- Internal Combustion Engines
COMPUTER CALCULATIONS
COMPUTERIZED CONTROL SYSTEMS
CONTROL SYSTEMS
ENGINES
EXHAUST GASES
FEEDBACK
FLUIDS
FUEL-AIR RATIO
GASEOUS WASTES
GASES
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
LIMITING VALUES
STOICHIOMETRY
TEMPERATURE MEASUREMENT
WASTES