Fresh Air Mass Estimation in Engine Combustion Chambers
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Solution Overview
Problem
Existing methods for estimating the mass of fresh air admitted into the combustion chamber of an internal combustion engine are imprecise, failing to accurately determine the quantity of fresh air, which is crucial for proper engine control and fuel injection adjustments.
Innovation Solution
A method that estimates the mass of fresh air by calculating the total filling of supercharged fresh air in the combustion chamber using a system of equations, incorporating admission pressure, volume, temperature, and correction coefficients, while accounting for swept gases during valve overlap, allowing for precise estimation without direct pressure or temperature measurement inside the chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing estimation methods are used for fresh air mass, then the estimation process is simple, but the measurement precision is insufficient
Solution Approach 1:
The estimation method is segmented into distinct calculation stages: determining valve overlap duration, calculating swept gas mass, estimating fresh air mass, and computing total filling. Each stage processes specific parameters independently, improving precision while maintaining manageable complexity through systematic decomposition of the estimation problem.
Solution Approach 2:
The method performs preliminary calculations of valve overlap characteristics and swept gas mass before determining the final fresh air mass estimation. By pre-calculating these intermediate parameters based on valve timing and engine operating conditions, the system establishes accurate baseline values that enhance the precision of the final measurement without requiring complex real-time computation.
2Quantity of substance
If valve overlap is used for supercharging, then the quantity of fresh air increases, but the complexity of gas flow control increases
Solution Approach 1:
The valve timing is made dynamic by adjusting the valve overlap duration and timing based on engine operating conditions such as engine speed and load. The control system dynamically modifies intake and exhaust valve opening/closing times to optimize fresh air quantity during supercharging while managing the complexity through condition-based adjustment rather than fixed timing.
Solution Approach 2:
The method changes key parameters including valve timing angles, overlap duration, and pressure ratios to optimize fresh air intake during supercharging. By systematically varying these parameters based on operating conditions and using correction coefficients, the system increases fresh air quantity while controlling complexity through parameter optimization rather than mechanical complexity.
3Measurement precision
If swept gases are considered in the estimation, then the measurement precision improves, but the calculation complexity increases
Solution Approach 1:
The calculation system is segmented into distinct modules: one for determining valve overlap parameters, another for calculating swept gas mass, and a third for computing fresh air mass. By separating the calculation of swept gases from the final fresh air estimation, the system improves precision through comprehensive modeling while managing complexity through modular calculation structures.
Solution Approach 2:
The swept gas mass calculation serves as an intermediary step between valve timing parameters and final fresh air mass estimation. By introducing this intermediate calculation that accounts for gas displacement during valve overlap, the system achieves higher measurement precision while managing complexity through a structured intermediate computation layer rather than direct complex modeling.
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 provides a more accurate estimation of fresh air mass, enabling better engine control and fuel management by considering the mass of gases swept during valve crossing, leading to improved engine performance and efficiency.
Implementation Method 1
the estimate of the total mass Mtot is obtained from an admission pressure P WMD air, a volume of the combustion chamber at the end of the intake, a temperature T mixed the mixture of fresh air and burnt gases
Data Source
Figure 1~4
Figure 2~3
AI summary
The invention relates to a method for estimating the mass Ma of fresh air taken into the combustion chamber of an engine cylinder during an engine cycle, characterised in that said method includes estimating (128) a total mass Mtot of gases contained in the combustion chamber at the end of the fresh air intake, estimating (120, 124) a mass Mb of burnt gases contained in the combustion chamber at the end of the exhaust of the burnt gases, and estimating (128) the mass Ma of fresh air from the difference between the estimated total mass Mtot and the estimated mass Mb of burnt gases.