Residual Gas Mass Calculation in Engine Cylinders
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Solution Overview
Problem
Existing methods for calculating residual gas mass in internal combustion engine cylinders are complex and require high computing power and memory, especially when dealing with dynamic operations and deviations in exhaust gas temperatures, leading to inaccurate calculations.
Innovation Solution
A method that obtains a baseline residual gas mass value under steady-state conditions using a complex model, then determines additional residual gas mass values based on cylinder dead volume and valve overlap, allowing for accurate calculation of current residual gas mass in dynamic operations by outsourcing temperature influence from parameterized models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parameterized models include exhaust gas temperature to account for dynamic operation deviations, then calculation accuracy is improved, but device complexity and computing power requirements increase
Solution Approach 1:
The patent segments the residual gas mass calculation into two distinct components: a baseline value from a predefined model and a dynamic correction value accounting for temperature deviations. This segmentation allows the complex temperature-dependent calculations to be separated from the base model, reducing overall model complexity while maintaining accuracy.
Solution Approach 2:
The patent introduces a temperature correction parameter that adjusts the baseline residual gas mass calculation based on actual exhaust gas temperature deviations from the predefined model. By changing the parameter set to include temperature as a correction factor rather than a core model variable, the system achieves accuracy without increasing base model complexity.
2Measurement precision
If parameterized models include exhaust gas temperature for dynamic operations, then calculation accuracy is improved, but memory requirements increase
Solution Approach 1:
The patent extracts the temperature-dependent calculation components from the main parameterized model and handles them as separate correction calculations. This extraction removes the need to store extensive temperature-specific data tables in memory, as the temperature effect is applied through a simplified correction formula rather than pre-stored values.
Solution Approach 2:
The patent performs preliminary calculation of the baseline residual gas mass using a simplified predefined model, then applies temperature correction in a subsequent step. This preliminary action separates the memory-intensive base calculation from the temperature adjustment, allowing the system to use less memory for the core model while maintaining accuracy through the correction step.
3Measurement precision
If complex models are used to account for exhaust gas temperature deviations, then calculation accuracy is improved, but computing power requirements increase
Solution Approach 1:
The patent divides the calculation into a computationally simple baseline model and a separate temperature correction calculation. The baseline model uses predefined parameters requiring minimal computation, while the temperature correction applies a straightforward adjustment formula, avoiding the need for complex real-time simulations that would demand high computing power.
Solution Approach 2:
The patent uses a simplified predefined model for the baseline calculation that requires minimal computational resources, accepting that this is a simplified approximation. The temperature correction then provides the necessary accuracy adjustment without requiring the full computational power of a complete complex model, effectively using a 'cheap' approximate solution enhanced by a correction factor.
Data Source
Figure 1
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AI summary
A method of calculating a residual gas mass in a cylinder (1) of an internal combustion engine, wherein the cylinder has at least one inlet valve (3) and one outlet valve (4), comprises: receiving (21) a cylinder residual gas mass base value which is based on a predefined model; determining (22) a first cylinder residual gas mass value which indicates a cylinder residual gas mass remaining in the cylinder clearance volume after an expulsion of exhaust gas; determining (23) a second cylinder residual gas mass value which indicates a cylinder residual gas mass flowing into the cylinder owing to a valve overlap of the inlet valve and the outlet valve, wherein the second cylinder residual gas mass value is determined on the basis of the cylinder residual gas mass base value and the first cylinder residual gas mass value; and calculating (27) the residual gas mass in the cylinder on the basis of the first and second cylinder residual gas mass values.