Cylinder Air Charge Correction for Unfired Engine Operation
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Solution Overview
Problem
Current methods for determining cylinder air charge in internal combustion engines fail to accurately model unfired operation, leading to significant deviations from actual values, which affects downstream systems and contributes to inefficiencies and inaccuracies in exhaust gas temperature modeling.
Innovation Solution
A method that adjusts the cylinder air charge determined in fired operation using a correction factor dependent on engine speed and load to account for unfired operation, integrating with existing engine control systems to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard cylinder air charge determination method is used, then the method is simple and can be implemented with existing models, but the accuracy of cylinder air charge determination deteriorates significantly during unfired operation
Solution Approach 1:
The patent applies parameter changes by introducing a correction factor that modifies the cylinder air charge calculation based on the firing state of cylinders. The correction factor is determined by comparing the number of firing cylinders to the total number of cylinders, and it adjusts the air charge value to account for the different gas dynamics in unfired versus fired operation. This allows the existing air charge model to be adapted for unfired operation without requiring a completely new model.
2Ease of manufacture
If existing air charge models are used for unfired operation, then implementation is straightforward, but the model accuracy deteriorates with deviations up to 30%
Solution Approach 1:
The patent introduces a correction factor as an intermediary element that bridges the gap between existing air charge models and unfired operation conditions. This correction factor acts as a mediator that adjusts the output of the existing model to better reflect actual air charge in unfired cylinders, without requiring a complete redesign of the underlying air charge calculation model.
3Device complexity
If no correction is applied for unfired operation, then the control system remains simple, but downstream systems receive inaccurate data leading to inefficiencies
Solution Approach 1:
The patent applies preliminary action by correcting the cylinder air charge value before it is used by downstream control systems. The correction factor is calculated and applied in advance, ensuring that accurate air charge data is provided to downstream systems such as exhaust gas temperature modeling and aftertreatment control, thereby improving their reliability without requiring complex modifications to those systems.
Data Source
Figure 1
AI summary
The invention relates to a method for determining the cylinder air charge of an internal combustion engine during unfired operation, wherein a method for determining the cylinder air charge during fired operation is carried out. According to the invention, the method for determining the cylinder air charge during fired operation includes a correction factor that depends on engine speed and engine load. This correction factor adjusts the cylinder air charge value determined by the method during fired operation accordingly for unfired operation. The invention further relates to an engine control unit and a computer program for executing the method. The method according to the invention allows for improvements and increased efficiency compared to previously known methods, particularly with regard to the deviations of up to 30% in the cylinder air charge values during unfired operation compared to modeled values for fired operation.