Spark-Ignition Engine Combustion Estimation via Intake Valve Phase Correction
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Solution Overview
Problem
Existing methods for estimating the first combustion period length in internal combustion engines require extensive experimentation and recalibration when the valve opening characteristic of the intake valve changes, leading to inefficiencies and increased time and effort.
Innovation Solution
A combustion state estimation method that utilizes mathematical expressions to estimate the first combustion period length by translating the relationship between maximum heat release rate timing and first combustion period length based on changes in intake valve phase angle and operating angle, allowing for efficient estimation even when the valve opening characteristic changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first combustion period length is estimated by utilizing the Wiebe function or model expression, then the estimation can be performed with existing methods, but when the valve opening characteristic of the intake valve changes, it is required to determine the variables of the Wiebe function or identify various parameters again, leading to extensive experimentation and recalibration
Solution Approach 1:
The patent pre-calculates and stores the relationship between intake valve phase angles and correction values for the first combustion period length in a lookup table during the design phase. When the engine operates with different valve timing configurations, the system simply retrieves the appropriate correction value from the pre-computed table based on the current intake valve phase angle, eliminating the need for real-time experimentation or parameter identification.
Solution Approach 2:
The patent creates a simplified computational model that copies the essential relationship between valve timing and combustion period characteristics. Instead of performing complex Wiebe function calculations or model parameter identification for each valve timing change, the system uses a streamlined approach that replicates the key behavioral patterns from pre-conducted experiments, allowing rapid estimation without repeating the full analysis.
2Measurement precision
If extensive experimentation is conducted to acquire first combustion period length for various valve opening characteristics, then accurate estimation data can be obtained, but an enormous amount of experiments need to be carried out for various engine operating states each time the valve opening characteristic changes
Solution Approach 1:
The patent performs comprehensive experiments and calculations in advance to build a lookup table that captures the relationship between intake valve phase angles and first combustion period length corrections. This pre-computation covers various engine operating states beforehand, so when the engine actually operates, the system can immediately retrieve the appropriate correction value without conducting new experiments, thus maintaining high accuracy while dramatically improving productivity.
3Adaptability or versatility
If the valve opening characteristic of the intake valve is changed, then the combustion speed changes due to disturbance of air stream, but it requires determining variables again and expending extremely large amounts of time and effort
Solution Approach 1:
The patent uses the intake valve phase angle as a key parameter to index into a pre-computed lookup table. When the valve opening characteristic changes, the system simply changes the parameter (phase angle) used to query the table, and retrieves the corresponding correction value. This approach allows the system to adapt to various valve timing configurations instantly without re-determining the underlying combustion model variables, thus maintaining versatility while minimizing time loss.
Data Source
AI summary
Where a relationship between maximum heat release rate timing and a first combustion period length (that is, a reference relationship) in the case where an engine rotation speed of a spark-ignition internal combustion engine is a selected speed and a valve opening characteristic of an intake valve is a reference characteristic is expressed by the function are f=f(θdQpeak) where θdQpeak denotes the maximum heat release rate timing and aref denotes the first combustion period length, when the valve opening characteristic of the intake valve changes to a specific characteristic from this state, a first combustion period length for selected maximum heat release rate timing is estimated on the basis of the mathematical expression a=f(θ2)+Δa1 where θ2 denotes the selected maximum heat release rate timing and a denotes the first combustion period length.