Double air-fuel ratio sensor system in internal combustion engine

Patent · Tue Apr 26 04:00:00 EDT 1988

OSTI ID:7007242

Katsuno, T; Kayanuma, N; Sato, Y; Tanahashi, T; Chujo, Y; Nagai, T; Hasegawa, K; Bessho, H; Masui, T

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
• 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
CATALYSTS
CONTROL
CONTROL SYSTEMS
CORRECTIONS
EMISSION
ENGINES
EQUIPMENT
EXHAUST GASES
EXHAUST SYSTEMS
FEEDBACK
FLUIDS
FUEL SYSTEMS
FUEL-AIR RATIO
GASEOUS WASTES
GASES
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
MEASURING INSTRUMENTS
METERING
METERS
OPERATION
POLLUTANTS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
REMOVAL
WASTES