Engine air/fuel ratio control method and system selectively providing feedback control or open loop control according to oxygen sensor heating condition
This patent describes an exhaust system and an oxygen sensor fitted to the exhaust system consisting of a sensor element and an electrically powered heater for heating the sensor element whose application is in an internal combustion engine. A methodology for controlling the air/fuel ratio of the air-fuel mixture supplied to the engine is characterized in detail by this patent. This method is described as consisting of two separate mechanisms of control. The first method pertains to the operating condition where the voltage of the power supply to the heater has dropped below a first predetermined value and thereafter has remained below a second predetermined value which is higher than the first value for longer than a specified time period, the air/fuel ratio is controlled according to engine operating parameters by an open loop form of control with no account taken of the output signal of the oxygen sensor. The second method, which encompasses all other power supply voltage conditions, controls the air/fuel ratio according to engine operational parameters by a closed loop form of feedback control taking into account the output signal of the oxygen sensor in order to obtain an optimum air/fuel ratio for the engine.
- Assignee:
- Toyota Jidosha Kabushiki Kaisha, Toyota
- Patent Number(s):
- US 4563991
- OSTI ID:
- 6023937
- Resource Relation:
- Patent File Date: Filed date 30 Oct 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EXHAUST SYSTEMS
CONTROL SYSTEMS
FUEL SYSTEMS
INTERNAL COMBUSTION ENGINES
FUEL-AIR RATIO
ELECTRIC HEATING
ELECTRIC POTENTIAL
FEEDBACK
HEATERS
OPERATION
OPTIMIZATION
OXYGEN METERS
SIGNALS
SPECIFICATIONS
TIME MEASUREMENT
ENGINES
HEAT ENGINES
HEATING
MEASURING INSTRUMENTS
METERS
330100* - Internal Combustion Engines