Mass Flow Controller Acceleration Means for Pressure Fluctuation
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Solution Overview
Problem
Mass flow controllers with pressure-type flow meters experience time deviation between measured and actual flow rates, leading to unstable control actions and longer response times due to pressure fluctuations and potential fluid leakage, which worsens the control stability and accuracy.
Innovation Solution
Incorporating an acceleration means in the flow meter to accelerate the time variation of pressure values measured, allowing for the calculation of a flow rate based on these accelerated pressure values, which is then used to control the flow rate, thereby reducing time deviation and stabilizing the control action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pressure-type flow meter is used to measure flow rate, then the structure is simple and cost-effective, but time deviation occurs between measured and actual flow rates leading to unstable control
Solution Approach 1:
The patent applies preliminary action by predicting the actual flow rate based on the measured flow rate and predetermined characteristics before the time deviation fully manifests. The controller proactively adjusts the flow control valve based on this prediction, preventing control instability before it occurs rather than reacting after the deviation is detected.
2Ease of operation
If feedback control is used based on measured flow rate, then the flow rate can be regulated, but control action becomes unstable due to time deviation
Solution Approach 1:
The patent enhances feedback control by introducing a prediction mechanism that compensates for time delays. The controller continuously receives measured flow rate data, predicts the actual flow rate using predetermined characteristics, and adjusts the flow control valve based on this corrected feedback, thereby maintaining control stability despite inherent measurement delays.
Solution Approach 2:
The prediction of actual flow rate based on measured flow rate and predetermined characteristics represents preliminary action. This allows the controller to anticipate the true flow state before time deviation causes instability, enabling proactive adjustments that maintain control stability.
3Measurement precision
If mechanical pressure regulator is added to maintain constant pressure, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical pressure regulator with a computational approach. Instead of using additional mechanical components to maintain constant pressure, the system uses the controller to calculate and compensate for pressure variations based on measured flow rate and predetermined characteristics, thereby maintaining measurement accuracy while reducing mechanical complexity.
Solution Approach 2:
The patent introduces an intermediary computational layer between the flow meter and the control valve. Rather than directly controlling based on raw measured flow rate, the controller acts as an intermediary that processes the measurement through prediction algorithms, compensating for time deviation and pressure variations without requiring additional physical components.
4Reliability
If fluid leakage occurs in mechanical pressure regulator, then time deviation increases and control stability worsens
Solution Approach 1:
The patent uses feedback control with prediction to detect and compensate for the effects of fluid leakage. By continuously monitoring measured flow rate and comparing it with predicted actual flow rate based on predetermined characteristics, the system can identify anomalies caused by leakage and adjust the control valve accordingly, maintaining control stability despite the leakage-induced time deviation.
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 enables faster and more stable flow rate control, reducing the time it takes to reach a set flow rate and minimizing overshooting or hunching, even in the presence of leakage or pressure fluctuations, by ensuring the flow rate calculated is closer to the actual flow rate.
Implementation Method 1
a pressure difference generate means (2a) and a pressure value measurement means configured to measure one or two or more pressure values derived from pressure P1 of fluid on an upstream side of the pressure difference generate means (2a) and pressure P2 of the fluid on a downstream side of the pressure difference generate means
Data Source
AI summary
Mass flow controllers and methods for controlling mass flow rates are disclosed. A mass flow controller includes a pressure value measurement means that measures one or two or more pressure values derived from pressure P1 of fluid on an upstream side of a pressure difference generate means and pressure P2 of the fluid on a downstream side of the pressure difference generate means, an acceleration means accelerates time variation of the obtained pressure values, a flow meter calculates a flow rate of the fluid based on a pressure value obtained according to the accelerated time variation (accelerated pressure value), and a flow control valve controls the flow rate of the fluid based on the calculated flow rate.