Engine Combustion State Prediction Using Cylinder Temperature Zones
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Solution Overview
Problem
Existing techniques fail to accurately predict the combustion state of an engine, particularly during transient operation, due to difficulties in determining combustion end timing influenced by cylinder wall temperature and other factors.
Innovation Solution
A method that calculates the combustion state by setting operating conditions, determining the temperature of the highest and lowest temperature portions in the cylinder, using Livengood-Wu integration to predict start and end timings, and considering the wall surface layer's temperature changes based on burned, unburned, and wall surface regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear parameter model is used to estimate in-cylinder state quantities, then calculation load is reduced and estimation accuracy is improved, but the technique is insufficient to accurately predict combustion state during transient operation
Solution Approach 1:
The cylinder is divided into multiple regions with different temperature characteristics (highest temperature portion and lowest temperature portion). The combustion process is segmented into combustion start timing determined by highest temperature region and combustion end timing determined by lowest temperature region, allowing accurate prediction throughout the combustion cycle including transient operation.
Solution Approach 2:
Different regions of the cylinder are assigned different temperature characteristics - the highest temperature portion (central region) controls combustion start timing while the lowest temperature portion (wall surface region) controls combustion end timing. This local quality approach enables accurate prediction of combustion state under varying operating conditions.
2Device complexity
If conventional estimation techniques are used, then calculation is simplified, but combustion end timing prediction is inaccurate due to wall temperature influence
Solution Approach 1:
The invention introduces wall surface layer portion temperature as a critical parameter for predicting combustion end timing. By calculating temperature changes in the wall surface layer portion based on heat transfer from burned and unburned portions, the model accurately captures wall temperature influence on combustion end timing without excessive calculation complexity.
3Measurement precision
If the temperature of the lowest temperature portion is calculated based on wall surface layer portion, then combustion end timing prediction accuracy is improved, but calculation complexity increases due to considering burned, unburned, and wall surface layer portions
Solution Approach 1:
The temperature of the wall surface layer portion is calculated in advance by considering heat transfer from the burned and unburned portions. This preliminary calculation of wall surface layer temperature enables accurate prediction of combustion end timing while organizing the calculation sequence to manage complexity efficiently.
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
This method allows for precise prediction of combustion start and end timings in transient operation, accounting for cooling losses and accurately modeling combustion in changing engine conditions.
Implementation Method 1
calculates a temperature of a wall surface layer portion based on state changes in a burned portion in which combustion has occurred, an unburned portion in which combustion has not yet occurred, and the wall surface layer portion located near a wall surface in the cylinder
Implementation Method 2
the lowest temperature portion temperature calculation step calculates a temperature of a wall surface layer portion based on state changes in a burned portion
Implementation Method 3
properly taking, for example, the cooling loss in the wall surface layer portion in the cylinder into consideration
Implementation Method 4
the combustion end timing in transient operation can be accurately predicted by properly taking, for example, the cooling loss in the wall surface layer portion
Data Source
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AI summary
A method of predicting or calculating the combustion state calculates the temperature of a highest temperature portion in the cylinder before combustion of the engine, calculates the combustion start timing of the engine based on the temperature of the highest temperature portion, calculates the temperature of a lowest temperature portion in the cylinder, and calculates the combustion end timing of the engine based on the temperature of the lowest temperature portion. In particular, the method calculates the temperature of a wall surface layer portion based on state changes in a burned portion in which combustion has occurred, an unburned portion in which combustion has not yet occurred, and the wall surface layer portion located near the wall surface in the cylinder, and applies the temperature of the wall surface layer portion as the temperature of the lowest temperature portion.