Double air-fuel ratio sensor system having improved response characteristics

Patent · Tue Dec 15 04:00:00 EST 1987

OSTI ID:5384208

Nagal, T; Masui, T; Satou, Y; 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. It consists of: determining whether or not the engine satisfies first predetermined air-fuel ratio feedback control conditions; comparing the output of the upstream -side air-fuel ratio sensor with a first predetermined reference voltage when the engine satisfies the first redetermined air-fuel ratio feedback control conditions; changing a first air-fuel ratio correction amount in accordance with a result of the comparison of the output of the upstread-side air-fuel ratio sensor with the first predetermined reference voltage; determining whether or not the engine satisfies second predetermined air-fuel ratio feedback control conditions; comparing the output of the downstream-side air-fuel ratio sensor with a second predetermined reference voltage when the engine satisfies the second predetermined air-fuel ratio feedback control conditions; changing a second air-fuel ratio correction amount in accordance with a result of the output of the downstream-side air-fuel ratio sensor with the second predetermined reference voltage, the changing speed of the second air-fuel ratio correction amount being larger for a predetermined time period after the engine satisfies the second predetermined air-fuel ratio feedback control conditions than after the predetermined time period has passed; and adjusting the actual-air ratio in accordance with the first and second air-fuel ratio correction amounts.

• Assignee: Toyota Jidosha Kabushiki Kaisha, Aichi
• Patent Number(s): US 4712373
• OSTI ID: 5384208
• 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
FEEDBACK
FLUIDS
FUEL INJECTION SYSTEMS
FUEL SYSTEMS
FUEL-AIR RATIO
FUNCTIONS
GASEOUS WASTES
GASES
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
METERING
OPERATION
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
RESPONSE FUNCTIONS
WASTES