Engine Temperature Estimation Module for Dither Control
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Solution Overview
Problem
Existing temperature estimation methods for internal combustion engines during dither control are inadequate, as they rely solely on actual temperatures, leading to inappropriate execution or stopping of processes and potential hunting issues due to inaccurate temperature determination.
Innovation Solution
A temperature estimation module that calculates both actual and virtual temperatures of the exhaust purifying device, allowing for more accurate determination of whether to execute or stop dither control by considering the engine's operation point and air-fuel ratios, thereby reducing hunting and improving control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only actual temperature is used for control determination during dither control, then the control decision is simple, but the temperature determination becomes inaccurate leading to inappropriate process execution or stopping
Solution Approach 1:
The temperature estimation is segmented into two distinct components: virtual temperature estimation (based on operation point without dither control) and actual temperature estimation (incorporating dither control effects). This segmentation allows the system to separately handle the baseline temperature prediction and the dither-induced temperature changes, improving overall accuracy while maintaining manageable complexity through modular estimation processes.
Solution Approach 2:
The patent introduces an intermediary approach by using operation point-based virtual temperature as a reference framework. This virtual temperature serves as a mediator between the complex actual dither control scenario and the simpler non-dither baseline, enabling accurate temperature determination without directly measuring actual temperature during dither control execution.
2Temperature
If dither control is executed to increase exhaust purifying device temperature, then the temperature increase effect is achieved, but the temperature estimation becomes unreliable for monitoring the temperature increase
Solution Approach 1:
The system performs preliminary action by estimating the virtual temperature based on the operation point before dither control is applied. This pre-established baseline serves as a reference framework that remains valid during dither control execution, allowing the system to monitor temperature changes without being confounded by the transient effects of dither control on direct temperature measurements.
Solution Approach 2:
The patent creates a virtual copy of the temperature estimation process that operates independently of the actual dither control effects. This virtual temperature estimation copies the essential relationship between operation point and temperature without being influenced by dither control, providing a reliable reference for monitoring actual temperature increases during dither control execution.
3Reliability
If the control system relies solely on actual temperature estimates during dither control, then the control logic is simple, but hunting occurs due to inaccurate temperature determination
Solution Approach 1:
The system implements feedback by continuously comparing the virtual temperature estimation with the actual temperature estimation during dither control. This feedback mechanism allows the control system to detect discrepancies caused by dither control and adjust decisions accordingly, eliminating hunting behavior while maintaining control stability through the dual-estimation approach.
Solution Approach 2:
The temperature estimation system dynamically adapts by switching between virtual temperature estimation (when dither control is not executed) and actual temperature estimation (when dither control is executed). This dynamic approach allows the system to maintain reliability across different operating conditions without requiring a permanently complex estimation system, as the complexity is activated only when needed.
Data Source
AI summary
A temperature estimation module applied to a control apparatus for an internal combustion engine is configured to execute a virtual temperature estimation process that estimates a virtual temperature, which is a temperature of an exhaust purifying device under an assumption that a dither control process is not executed, based on an operation point of the internal combustion engine during execution of the dither control process. The temperature estimation module is further configured to execute an actual temperature estimation process that estimates an actual temperature of the exhaust purifying device based on a difference between the air-fuel ratio of a rich combustion cylinder and the air-fuel ratio of a lean combustion cylinder and based on the operation point of the internal combustion engine during execution of the dither control process.