Engine Controller Exhaust Temperature Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine control techniques fail to accurately estimate exhaust gas temperature, particularly when the air-fuel ratio of the air-fuel mixture changes, as they do not adequately consider the impact of cooling loss on temperature estimation.
Innovation Solution
An engine controller that includes sensors and a control unit to estimate exhaust gas temperature based on combustion progress, air-fuel ratio, and engine temperature, using different relationships for stoichiometric and lean air-fuel ratios, and adjusting the correction amount for cooling loss, allowing for accurate temperature estimation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the air-fuel ratio is changed to improve engine performance, then fuel efficiency and emissions are improved, but exhaust gas temperature estimation accuracy deteriorates due to cooling loss variations
Solution Approach 1:
The patent applies dynamics by making the estimation system adaptive to changing operating conditions. The control unit dynamically switches between different estimation methods (first estimation using exhaust temperature map for stoichiometric conditions, second estimation considering cooling loss for lean conditions) based on the actual air-fuel ratio, enabling accurate temperature estimation across varying engine operating states
Solution Approach 2:
The patent changes the estimation parameters based on air-fuel ratio conditions. When the air-fuel ratio is stoichiometric, the system uses exhaust temperature map with combustion gravity center correction. When the air-fuel ratio is lean, the system switches to a different estimation approach that accounts for reduced cooling loss, thereby adapting the estimation parameters to match the actual thermal conditions
2Device complexity
If a single exhaust temperature map is used for all air-fuel ratios, then the system is simple, but temperature estimation accuracy deteriorates under lean burn conditions
Solution Approach 1:
The system dynamically selects the appropriate estimation method based on air-fuel ratio conditions. The control unit monitors the air-fuel ratio and switches between the first estimation method (exhaust temperature map) and the second estimation method (considering cooling loss characteristics) to maintain accuracy across different operating conditions without requiring a completely separate system for each condition
Solution Approach 2:
The patent segments the estimation approach into two distinct methods: one for stoichiometric air-fuel ratios and another for lean air-fuel ratios. This segmentation allows each method to be optimized for its specific operating range, with the first method using standard exhaust temperature maps and the second method incorporating cooling loss corrections appropriate for lean burn conditions
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
The engine controller accurately estimates exhaust gas temperature, improving thermal efficiency and ensuring the reliability of catalytic devices by adjusting fuel supply and coolant flow rates, thereby maintaining optimal engine performance.
Implementation Method 1
a first relationship that is at least defined between the progress of the combustion and the temperature of the exhaust gas
Implementation Method 2
a quantity of heat released to the engine (that is, cooling loss)
Implementation Method 3
combustion in a cylinder
Data Source
AI summary
A controller for an engine estimates a temperature of the exhaust gas and controls the engine according to the estimated exhaust temperature. The controller changes the air-fuel ratio to a stoichiometric air-fuel ratio or leaner. The controller calculates the progress of combustion on the basis of signals of sensors, and estimates an exhaust temperature. In the case where the air-fuel ratio is the stoichiometric air-fuel ratio, the controller estimates the exhaust temperature on the basis of the progress of the combustion, the engine temperature, and a first relationship that is at least defined between the progress of the combustion and the exhaust temperature, . In the case where the air-fuel ratio is lean, the controller estimates the exhaust temperature on the basis of the progress of the combustion, the engine temperature, and a second relationship that differs from the first relationship.