Air-Fuel Ratio Sensor Heating Control for Fuel Cut Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control devices for internal combustion engines face challenges in accurately performing abnormality diagnosis of air-fuel ratio sensors during fuel cut-off control, especially at low temperatures, due to increased electric power consumption for heating and incomplete temperature rise before fuel cut-off completion.
Innovation Solution
A control device and method that adjust the heating element temperature of the air-fuel ratio sensor to a target temperature higher than normal operation only during abnormality diagnosis, maintaining low electric power consumption and ensuring accurate diagnosis by optimizing temperature control during fuel cut-off and post-diagnosis phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the element temperature of the air-fuel ratio sensor is maintained comparatively high all the time by a heater, then the detection accuracy of lean air-fuel ratio is improved, but electric power consumed by heating increases
Solution Approach 1:
The heater is operated periodically rather than continuously. Specifically, the heater is activated only during the abnormality diagnosis period when accurate detection of lean air-fuel ratio is required, and is turned off during normal operation periods. This periodic heating action reduces overall electric power consumption while maintaining detection accuracy when needed.
Solution Approach 2:
The heater is activated in advance before the abnormality diagnosis is performed. By pre-heating the air-fuel ratio sensor element to the required temperature before diagnosis begins, the system ensures that the sensor is ready for accurate detection without maintaining high temperature continuously, thus reducing power consumption.
2Temperature
If heating of the air-fuel ratio sensor is performed by the heater from the beginning of the fuel cut-off control, then the element temperature rises, but the fuel cut-off control is completed before sufficient temperature rise
Solution Approach 1:
The heater is activated in advance before the abnormality diagnosis is performed. By pre-heating the air-fuel ratio sensor element to the required temperature before diagnosis begins, the system ensures that the sensor is ready for accurate detection without maintaining high temperature continuously, thus reducing power consumption.
Solution Approach 2:
The heater control is made dynamic by adjusting the target element temperature based on the diagnostic phase. During abnormality diagnosis, a higher target temperature (e.g., 700°C) is set to ensure accurate lean air-fuel ratio detection, while during normal operation, a lower target temperature (e.g., 600°C) is sufficient. This dynamic temperature adjustment optimizes both detection accuracy and power consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable abnormality diagnosis of air-fuel ratio sensors with reduced electric power consumption and improved detection accuracy of lean air-fuel ratios during fuel cut-off control, while minimizing heating time and power usage.
Implementation Method 1
the air-fuel ratio sensor having a heating device for heating an element thereof
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A control device of an internal combustion engine is configured to perform a fuel cut-off control and an abnormality diagnosis control. A heating device for heating an element of an air-fuel ratio sensor is controlled by making an element temperature of the air-fuel ratio sensor become a target element temperature. The target element temperature of the air-fuel ratio sensor during a high temperature control period from a time when a prescribed high temperature control begins after a start of the internal combustion engine to a time when the prescribed high temperature control is completed after completion of the abnormality diagnosis control of the air-fuel ratio sensor is set to be higher than the target element temperature outside the high temperature control period.