Flow Measuring Device Signal Processing for Airflow Stability
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Solution Overview
Problem
Existing flow measuring devices face accuracy issues due to unstable air flow near the device during high air flow rates, leading to fluctuations in output signals that affect rotation and torque, and short sampling periods reduce the accuracy of averaging processing in engine control units.
Innovation Solution
A flow measuring device with a flow rate detecting part, analog/digital conversion part, and signal processing part that converts flow voltage signals into digital data and performs averaging processing on consecutive data points, outputting an averaged flow rate signal, allowing for improved accuracy and reduced fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If averaging processing is performed on output signals to reduce fluctuation influence, then rotation fluctuation and torque fluctuation are reduced, but at high air flow rates unstable air flow causes output signal fluctuation that still affects rotation and torque
Solution Approach 1:
The patent applies preliminary action by performing averaging processing within the flow measuring device itself before the data is output to the ECU. This pre-processing ensures that the averaged data is provided to the ECU, allowing the device to proactively mitigate fluctuation effects before they reach the control unit, thereby improving rotation stability without compromising measurement precision.
Solution Approach 2:
The patent introduces an intermediary averaging processing unit within the flow measuring device that acts as a mediator between the flow rate detecting part and the ECU. This intermediary component processes the output signals by averaging them, thereby reducing the direct transmission of fluctuations to the ECU while maintaining accurate flow detection capabilities.
2Productivity
If the sampling period of A/D conversion is shortened to capture more data, then more data can be processed, but the ECU cannot load all the data and accuracy of averaging is reduced
Solution Approach 1:
The patent extracts the averaging processing function from the ECU and implements it directly within the flow measuring device. This extraction allows the device to perform averaging on all captured data points independently of the ECU's loading capacity, thereby maintaining high averaging accuracy even when the sampling period is shortened and more data is generated.
Solution Approach 2:
The flow measuring device performs self-service by conducting averaging processing internally within its own structure, rather than relying on the ECU to perform this function. This self-service capability enables the device to maintain accurate averaging regardless of the ECU's data loading constraints, effectively resolving the contradiction between productivity and measurement precision.
Data Source
AI summary
A flow measuring device includes a flow rate detecting part, an analog/digital conversion part, and a signal processing part. The flow rate detecting part detects a flow rate of air flowing through the passage, and outputs a flow voltage signal, which is a voltage in accordance with the flow rate. The analog/digital conversion part converts the flow voltage signal from the flow rate detecting part into digital data, which is flow digital data. The signal processing part performs calculation processing upon the flow digital data, which includes averaging of a predetermined number of consecutive pieces of the flow digital data, and outputs the averaged flow digital data as a flow rate signal. The predetermined number is equal to or larger than two.