Frequency Domain Mass Flow Rate Determination in Engine Intake
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Solution Overview
Problem
Existing methods for determining the instantaneous mass flow rate of gas in internal combustion engine intake channels are inaccurate due to reliance on time domain analysis, assumptions of steady flow and constant air density, and are intrusive, fragile, and require calibration, failing to account for pulsating flows and density fluctuations.
Innovation Solution
A frequency-based method using a transfer matrix model that links pressure and mass flow measurements in the frequency domain, accounting for air density and temperature fluctuations, and derived experimentally to provide real-time, accurate mass flow rate measurements without intrusive devices or calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time domain analysis with differential equations is used to determine mass flow rate, then the measurement can be performed, but the accuracy deteriorates due to simplifying assumptions of steady flow and constant air density
Solution Approach 1:
The patent transforms the measurement approach from time domain to frequency domain, changing the mathematical parameters used in the analysis. This allows the system to handle unsteady, pulsating flows without requiring simplifying assumptions about steady flow conditions or constant air density, thereby improving measurement accuracy while maintaining computational tractability
Solution Approach 2:
The patent replaces the traditional mechanical/intrusive measurement devices (like hot-wire anemometers or flow filters) with a non-intrusive pressure measurement system combined with frequency domain analysis. This substitution eliminates the need for physical flow disruption while achieving accurate mass flow rate determination
2Measurement precision
If intrusive measurement devices like hot-wire anemometers or flow filters are used, then mass flow rate can be measured, but the device fragility and reliability worsen due to exposure to pulsating flows
Solution Approach 1:
The patent extracts the measurement function from intrusive physical devices and implements it through non-intrusive pressure sensors combined with frequency domain analysis. This removes the vulnerable hot-wire or flow-filter elements from the pulsating flow environment while preserving the mass flow rate measurement capability
Solution Approach 2:
The patent introduces pressure measurements as an intermediary parameter to indirectly determine mass flow rate without directly measuring it with intrusive devices. The pressure data, when analyzed in the frequency domain, serves as a mediator to calculate mass flow rate while avoiding direct exposure to harsh pulsating flow conditions
3Measurement precision
If calibration is performed for each measurement device, then measurement accuracy can be optimized, but the ease of operation worsens due to repeated calibration requirements
Solution Approach 1:
The patent implements a self-calibrating system where the frequency domain analysis automatically adapts to varying operating conditions without requiring manual calibration. The method inherently accounts for changes in air density, temperature, and flow characteristics through spectral analysis, eliminating the need for repeated calibration operations
4Device complexity
If non-intrusive pressure measurements are used, then device complexity is reduced, but measurement precision deteriorates without frequency domain analysis
Solution Approach 1:
The patent transitions the analysis from the time dimension to the frequency dimension, adding a new analytical dimension to the pressure measurements. This frequency domain transformation enables accurate mass flow rate determination from simple pressure data by exploiting the spectral characteristics of the pulsating flow, thereby maintaining device simplicity while achieving high measurement precision
Data Source
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AI summary
The invention relates to a method and device for determining the instantaneous mass flow of a gas, such as air in a conduit (12), like an air intake channel of an internal combustion engine of a motor vehicle. The method comprises the steps of: - measuring (81) a time-domain signal of gas pressure at a first measurement point (A) of said conduit (12); - measuring (82) a time-domain signal of gas pressure at a second measurement point (B) of said conduit (12). According to the invention, said method further comprises the steps of: - obtaining (83) for each of the measured time-domain signals of gas pressure the corresponding frequency spectrum ; - obtaining (84) the frequency spectrum of the mass flow at each of said measurement points (A, B) using a model in the frequency domain linking the frequency spectrum of the measured gas pressure at said measurement points (A, B) to the frequency spectrum of the mass flow at said measurement points (A, B) ; - obtaining (85) the time-domain signal of the mass flow rate at any measurement point (A, B) from the frequency spectrum of the mass flow at said corresponding measurement point (A, B).