Internal EGR Calculation Using Overlap Center Position Correction
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Solution Overview
Problem
Existing internal EGR amount calculation devices for internal combustion engines fail to accurately calculate the internal EGR amount due to the lack of consideration for the timing position relationship between the valve overlap period and the exhaust top dead center, leading to increased calculation errors.
Innovation Solution
An internal EGR amount calculation device that adjusts valve timing for the intake and exhaust valves to change the valve overlap period, incorporating blow back gas amount calculation, overlap center position calculation, and correction of the blow back gas amount based on the overlap center position to improve accuracy, even when the timing position relationship changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the blow back gas amount is calculated using only the valve overlap period length and engine speed, then the calculation process is simple, but the calculation accuracy decreases when the timing position relationship between the valve overlap period and exhaust top dead center changes
Solution Approach 1:
The patent introduces a new parameter (overlap center position) to the calculation formula and changes the functional parameters to account for timing position relationships. This resolves the contradiction by enhancing calculation accuracy through parameter expansion while maintaining reasonable computational complexity.
Solution Approach 2:
The patent makes the calculation dynamic by introducing the overlap center position relative to exhaust top dead center, allowing the calculation to adapt to changing timing positions. This enables accurate calculation across different operating conditions without excessive complexity.
2Adaptability or versatility
If the valve timing is changed to adjust the valve overlap period, then the internal EGR amount can be controlled, but the calculation accuracy decreases when the timing position relationship changes
Solution Approach 1:
The patent introduces feedback by calculating the overlap center position relative to exhaust top dead center and using this information to correct the blow back gas amount calculation. This feedback mechanism maintains calculation accuracy across different valve timing configurations.
Solution Approach 2:
The calculation system becomes dynamic by adapting to different overlap center positions, allowing accurate internal EGR calculation regardless of valve timing adjustments. This resolves the contradiction between adaptability and precision.
3Measurement precision
If the overlap center position is used to correct the blow back gas amount, then the calculation accuracy improves, but the calculation process becomes more complex
Solution Approach 1:
The patent adds the overlap center position parameter to the calculation, improving accuracy through enhanced parameterization. The added complexity is minimal and justified by the significant improvement in calculation accuracy across different operating conditions.
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 approach allows for precise calculation of the internal EGR amount by reflecting changes in the timing position relationship, thereby enhancing the calculation accuracy of the internal EGR amount.
Implementation Method 1
the blow back gas amount represents an amount of burned gas which has once flowed into an intake passage from an exhaust passage and then has been blown back into the cylinder, due to the pressure difference between the intake passage and the exhaust passage
Implementation Method 2
the blow back gas amount represents an amount of burned gas which has once flowed into an intake passage from an exhaust passage and then has been blown back into the cylinder, due to the pressure difference between the intake passage and the exhaust passage
Implementation Method 3
an amount of gas which once flowed out of the cylinder into at least one of an intake system and an exhaust system
Data Source
AI summary
An internal EGR amount calculation device for an internal combustion engine, which, even when a timing position relationship between a valve overlap period and an exhaust top dead center has changed, can properly calculate an internal EGR amount according to the change and can improve a calculation accuracy of the internal EGR amount. The internal EGR amount calculation device for an internal combustion engine includes an ECU. The ECU calculates a basic blow back gas amount, calculates a crank angle position in the center between the starting point and the ending point of the valve overlap period as an overlap center position, calculates a blow back gas amount by correcting the basic blow back gas amount according to the overlap center position, and calculates the internal EGR amount, using the calculated blow back gas amount.