Gas Flow Control Restriction Diagnosis Without Supply Interruption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pressure type flow rate control devices in gas supply systems, such as those in semiconductor manufacturing facilities, face challenges in detecting abnormalities in the restriction part, like clogging or corrosion, without disrupting the manufacturing process or reducing diagnosis accuracy, due to the lack of direct flow rate measurement capabilities and the need for offline self-diagnosis.
Innovation Solution
A method involving an upstream on/off valve, a flow control pressure sensor, and a control circuit that allows for continuous gas flow during abnormality detection by measuring the drop in supply pressure after closing the upstream on/off valve, enabling diagnosis of clogging or aperture expansion in the restriction part while maintaining controlled flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If self-diagnosis is performed by closing the control valve to measure pressure drop, then abnormality detection capability is improved, but gas supply is interrupted and productivity deteriorates
Solution Approach 1:
The system segments the valve system into two independent parts: the control valve (for flow control) and the upstream on/off valve (for diagnosis). This segmentation allows the control valve to remain open for continuous gas supply while the upstream on/off valve closes to enable pressure drop measurement for abnormality detection, eliminating the need to interrupt gas supply for diagnosis
Solution Approach 2:
The upstream on/off valve acts as an intermediary component that enables diagnosis functionality without affecting the control valve's flow control function. By placing this intermediary valve upstream of the inflow pressure sensor, the system can perform self-diagnosis through pressure drop measurement while maintaining continuous gas flow through the control valve and restriction part
2Reliability
If self-diagnosis is performed offline to ensure diagnosis accuracy, then measurement reliability is improved, but system downtime increases and productivity deteriorates
Solution Approach 1:
The system enables continuous useful action by allowing gas supply to proceed uninterrupted while diagnosis is performed. The control valve remains open maintaining gas flow, and the upstream on/off valve closes only in the measurement section to enable pressure drop measurement. This continuous operation eliminates downtime while maintaining diagnosis accuracy through proper measurement conditions
3Measurement precision
If pressure drop measurement is performed with control valve closed, then abnormality detection accuracy is improved, but flow rate control function is interrupted
Solution Approach 1:
The system segments the valve functions into control (control valve) and measurement (upstream on/off valve), allowing the control valve to maintain flow rate control by remaining open while the upstream on/off valve closes to enable accurate pressure drop measurement for abnormality detection
Solution Approach 2:
The upstream on/ off valve serves as an intermediary that enables measurement functionality without disrupting control functionality. It closes to create the pressure drop condition needed for accurate abnormality detection while the control valve remains open to maintain continuous flow rate control
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
Enables accurate detection of abnormalities in the restriction part during ongoing processes, reducing downtime and improving diagnosis accuracy by utilizing pressure drop measurements without interrupting gas supply, thus ensuring reliable flow rate monitoring and control.
Implementation Method 1
a flow control pressure sensor for measuring an upstream pressure between the restriction part and the control valve
Implementation Method 2
an inflow pressure sensor for measuring a supply pressure upstream of the control valve
Implementation Method 3
a piezoelectric element driven valve configured to open and close the diaphragm valve element by a piezo actuator
Implementation Method 4
the fluid pressure upstream of the restriction part (hereinafter, sometimes referred to as an upstream pressure P1) is controlled to adjust the flow rate
Data Source
AI summary
An abnormality detection method is performed in a gas supply system including a flow rate control device having a restriction part, a control valve, a flow rate control pressure sensor for measuring upstream pressure, and a control circuit. The inflow pressure sensor measures the supply pressure. An upstream on/off valve is provided upstream of the inflow pressure sensor. The method includes closing the upstream on/off valve when the gas flows at a controlled flow rate at the downstream of the restriction part by controlling an opening degree of the control valve based on the output of the flow rate control pressure sensor; measuring a drop in supply pressure on the upstream side of the control valve after closing the upstream on/off valve while keeping the control valve open; and detecting the presence or absence of abnormality in the flow rate control device based on the measured supply pressure drop.