Heat Release Rate Estimation Using Tangential Line Initial Values
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Solution Overview
Problem
Existing methods for estimating the heat release rate in internal combustion engines with multiple-stage fuel injection face challenges in accurately identifying model parameters due to high freedom degrees and oscillation components in the heat release waveform, leading to imprecise start timing of after-burning and pre-burning.
Innovation Solution
An estimation device that determines a point of higher peak burning within a predetermined range, calculates tangential lines, and sets a point on these lines as an initial value for identifying model parameters, reducing the difference between calculated and actual heat release rates, thereby improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional parameter identification methods are used for heat release rate modeling in multiple-stage fuel injection engines, then the model can be established, but the identification accuracy is low due to high freedom degrees and oscillation components in the heat release waveform
Solution Approach 1:
The patent applies preliminary action by determining a predetermined point on the tangential line before the parameter identification process. This initial point determination serves as a preparatory step that guides the subsequent identification algorithm, providing a head start in the parameter estimation process and improving convergence accuracy while managing the complexity of high freedom degree models
Solution Approach 2:
The patent utilizes parameter changes by transforming the heat release rate waveform into a tangential line representation and identifying model parameters based on geometric characteristics of this transformed domain. This parameter transformation approach converts the difficult parameter identification problem in the time domain into a more tractable problem in the transformed domain, reducing identification errors despite the high freedom degrees in multiple-stage injection models
2Reliability
If detailed model parameters are identified to capture oscillation components in the heat release waveform, then the model fidelity improves, but the start timing of after-burning and pre-burning becomes less precise
Solution Approach 1:
The patent applies segmentation by separating the heat release rate waveform into distinct burning phases (pre-burning, main burning, after-burning) and analyzing each phase independently through tangential line transformations. This segmentation allows the model to capture oscillation components within each phase while precisely determining start timing points at the boundaries between phases, resolving the contradiction between model fidelity and timing precision
Solution Approach 2:
The patent introduces the tangential line transformation as an intermediary representation between the raw heat release rate waveform and the model parameters. This intermediary domain serves as a bridge that preserves the fidelity information needed for accurate modeling while providing clear geometric features for precise start timing determination, effectively mediating between the two competing requirements
Data Source
AI summary
An estimation device includes: a memory and a processor, wherein the processor is configured to execute a process including: determining a point of a burning having a higher peak in a predetermined range of a heat release rate based on a peak of a burning having a smaller peak, in a heat release rate waveform in an internal combustion engine that performs a multiple-stage fuel injection; calculating a tangential line of the heat release rate waveform at the point; setting a predetermined point on the tangential line as an initial value for identifying a model parameter of a heat release rate model; identifying the model parameter so that a difference between a calculation value of the heat release rate model and the heat release rate waveform is reduced with use of the initial value; and estimating a heat release rate with a result of an identification of the identifying.