Engine Airflow Measurement Correction for Pulsation
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Solution Overview
Problem
Thermal air flow rate measuring apparatuses in internal combustion engines face measurement errors due to pulsation, especially when air flow rates are higher than the minimum flow rate, leading to inaccurate air-fuel ratio calculations.
Innovation Solution
An internal combustion engine control apparatus that uses a thermal air flow rate measuring apparatus with storage means for multiple conversion tables and selection means to choose the appropriate table based on air flow pulsation state, allowing for accurate air flow rate measurement by correcting measurement errors caused by pulsation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermal air flow rate measuring apparatus is used to detect air flow rate, then the air flow rate can be measured, but measurement errors occur due to pulsation and response delay
Solution Approach 1:
The patent applies parameter changes by storing multiple air flow rate conversion tables corresponding to different pulsation amplitudes and selecting the appropriate table based on the current pulsation state. This allows the conversion from heating resistor signal to air flow rate to account for pulsation effects, thereby improving measurement accuracy without changing the physical structure of the thermal air flow rate measuring apparatus.
2Measurement precision
If multiple conversion tables are stored for different pulsation states, then measurement accuracy under pulsation improves, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing multiple air flow rate conversion tables corresponding to different pulsation amplitudes before actual operation. During operation, the control apparatus only needs to select the appropriate pre-prepared table based on the current pulsation state, rather than performing complex real-time calculations, thus improving accuracy while limiting complexity growth.
3Loss of information
If the thermal air flow rate measuring apparatus response time is increased to capture pulsation, then measurement completeness improves, but response delay increases
Solution Approach 1:
The patent introduces an intermediary approach by using multiple pre-calculated conversion tables as intermediaries between the heating resistor signal and the final air flow rate value. Instead of increasing the physical response time of the thermal measuring apparatus, the system compensates for pulsation effects through table selection based on detected pulsation amplitude, thus maintaining fast response while improving information completeness.
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
The solution enables precise air flow rate measurement even during pulsation, improving the accuracy of air-fuel ratio calculations, especially in high load regions.
Implementation Method 1
a thermal air flow rate measuring apparatus which detects the flow rate of air flowing through an intake passage on the basis of, for example, a signal from a heating resistor
Data Source
AI summary
An internal combustion engine control apparatus according to the present invention includes storage for storing a plurality of air flow rate conversion tables T1 and T2 used to convert a signal of a heating resistor 2 to an air flow rate, a selector for selecting a conversion table to be referred to from the plurality of conversion tables T1 and T2 stored, and a converter for converting a signal of the heating resistor into an air flow rate by referring to the conversion table selected by the selector. The selector performs selection of the conversion table according to a state value, which directly or indirectly indicates the state of air flow pulsation generated in a passage.