Single-Cylinder Simulation for Engine Residual Gas Estimation
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Solution Overview
Problem
Current methods for estimating engine internal residual burned gas fraction are complex, time-consuming, and require elaborate instrumentation, making them costly and sensitive to measurement errors, especially when dealing with multi-cylinder engines and complex intake and exhaust port pressure dynamics.
Innovation Solution
A system and method using a single-cylinder simulation that iteratively estimates residual burned gas fraction based on measured cylinder pressure and airflow inputs, eliminating the need for crank-angle-resolved intake and exhaust port pressure measurements, and utilizing a simulator and optimizer to converge on accurate residual fraction estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a highly detailed simulation model of the engine and manifold system is constructed and calibrated against engine test data, then the accuracy of residual estimation is improved, but the time investment and complexity of model creation and calibration increase substantially
Solution Approach 1:
The patent extracts the essential function of residual estimation from the complex manifold system by using a single-cylinder simulation that ignores intake and exhaust manifolds. This extraction allows accurate residual estimation without the time-consuming calibration of manifold pressure dynamics, directly resolving the contradiction between accuracy and time investment.
Solution Approach 2:
The patent creates a simplified copy of the engine system - a single-cylinder simulation without manifolds - that replicates the essential residual generation physics. This copy provides sufficient accuracy for residual estimation while eliminating the need for complex manifold calibration, thus reducing time investment while maintaining measurement precision.
2Measurement precision
If pressure transducers are installed in the intake and exhaust ports to measure crank-angle-resolved pressure data, then the accuracy of port pressure measurements is improved, but the instrumentation complexity and cost increase
Solution Approach 1:
The patent removes the requirement for port pressure transducers by extracting only the necessary pressure information from the single-cylinder simulation. The simulator calculates equivalent port pressures based on cylinder pressure and valve positions, eliminating complex instrumentation while maintaining sufficient measurement accuracy for residual estimation.
Solution Approach 2:
The single-cylinder simulation acts as an intermediary that translates easily measured cylinder pressure data into estimated port pressure conditions. This mediator eliminates the need for direct port pressure measurements, reducing instrumentation complexity while preserving the information needed for accurate residual estimation.
3Speed
If a detailed process simulation using the port-pressure method is used, then the execution speed is improved, but the sensitivity to model inputs such as valve train compliance and port flow coefficients increases
Solution Approach 1:
The patent extracts the residual estimation function from the port-pressure method by removing the sensitive parameters (valve train compliance, port flow coefficients). The simplified simulation uses only robust inputs (cylinder pressure, airflow) that are easily and accurately measured, eliminating sensitivity issues while maintaining fast execution speed.
Solution Approach 2:
The patent changes the set of input parameters from sensitive ones (valve train compliance, port flow coefficients) to robust ones (cylinder pressure, airflow measurements). This parameter substitution maintains fast simulation execution while significantly reducing sensitivity to measurement errors and model uncertainties.
4Adaptability or versatility
If conventional residual estimation methods using multiple cylinders and manifold simulations are used, then the comprehensiveness of the simulation is improved, but the computational complexity and time required increase
Solution Approach 1:
The patent segments the multi-cylinder engine simulation into a single-cylinder representation that captures the essential residual generation physics. This segmentation reduces computational complexity while maintaining comprehensiveness for residual estimation, as each cylinder's residual generation is independent and can be modeled separately.
Solution Approach 2:
The patent extracts the core residual estimation functionality from the comprehensive multi-cylinder manifold simulation by removing the manifold system. The single-cylinder simulation retains the essential physics of residual generation (valve flows, compression, combustion) while eliminating the computationally intensive manifold pressure dynamics.
Data Source
AI summary
An estimation apparatus for determining a residual burned gas mass fraction of an internal combustion engine includes a single-cylinder simulator and an optimizer. The residual estimation apparatus does not rely on accurate knowledge of, or calculation of the details of the complex pulsating pressures and flows at the intake and exhaust valves. Instead an iterative approach uses primarily measured cylinder pressure and airflow as driving inputs, to ensure that the simulation states (i.e., pressure, temperature, and composition) of the cylinder gas contents, at the time of intake valve closing, are correct. The burned gas fraction calculated by the engine simulator is then taken as an estimate of that in the actual engine.