Flow Rate Signal Correction for Pressure-Type Flow Control
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Solution Overview
Problem
Pressure-type flow rate control devices experience signal drift due to quantization errors, leading to unstable output signals despite stable gas flow rates, which can compromise responsiveness if noise removal methods are applied.
Innovation Solution
A flow rate signal correction method that generates a secondary signal using current and past values of the primary signal through a predetermined relational expression, with correction applied only during stable flow rate periods to minimize signal swings without affecting responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a pressure-type flow rate control device is used to control flow rate by controlling upstream pressure, then responsiveness is improved and the system is hardly influenced by disturbances, but signal drift occurs due to quantization errors causing the output signal to fluctuate even when actual flow rate is stable
Solution Approach 1:
The system performs preliminary classification of flow rate periods into stable and transient change periods. During stable periods, correction processing is applied in advance to smooth quantization errors, while during transient periods, the primary signal is output without correction to maintain responsiveness. This preliminary classification resolves the contradiction by preparing different processing paths before signal output.
Solution Approach 2:
The system dynamically switches between two operating modes: correction mode during stable flow rate periods and direct output mode during transient change periods. The correction processing is applied dynamically based on the detected flow rate period, allowing the system to adapt its signal processing behavior to current operating conditions, thus maintaining both responsiveness and signal stability.
2Stability of the object's composition
If noise removal processing is applied to remove signal drift, then output signal stability is improved, but responsiveness may be sacrificed
Solution Approach 1:
The system applies different quality processing to different time periods of the signal. During stable flow rate periods, correction processing is applied to smooth quantization errors and improve signal stability. During transient change periods, the primary signal is output without correction to preserve responsiveness. This local differentiation of processing quality resolves the contradiction by applying stability enhancement only where it does not compromise responsiveness.
Solution Approach 2:
The system applies correction processing partially, only during stable flow rate periods when it is beneficial, rather than continuously. This partial application of correction avoids the responsiveness degradation that would occur with continuous noise removal processing, while still achieving signal stability improvement during the periods when it matters most.
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 method stabilizes the flow rate output signal during stable conditions, reducing signal fluctuations while maintaining responsiveness by selectively applying correction processing during stable periods and outputting the primary signal during transient changes.
Implementation Method 1
a pressure sensor provided upstream of the restriction part
Implementation Method 2
a piezo actuator-driven pressure control valve
Data Source
AI summary
A flow rate signal correction method applicable to a pressure-type flow rate control device that controls a flow rate by controlling pressure existing upstream of a restriction part includes a step of generating a primary signal indicating the flow rate in accordance with an output of a pressure sensor provided upstream of the restriction part and a step of generating a secondary signal as a corrected signal of the primary signal such that the current value of the primary signal and a value including information regarding one or a plurality of past values of the primary signal are used to derive a current value corrected according to a predetermined relational expression. The secondary signal is output as a flow rate signal during a stable flow rate period, and the secondary signal is not output as a flow rate signal during a transient change period.