Flow Rate Control Valve Self-Diagnosis via Pressure Drop Signatures
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Solution Overview
Problem
The increased opening and closing speed, displacement, and frequency of piezoelectric element driven valves in flow rate control devices lead to degradation of flow rate control accuracy and operation failures, particularly in high-speed applications like ALD, resulting in reduced accuracy and potential early-stage operation failures.
Innovation Solution
A self-diagnosis method for flow rate control devices that includes a pressure control valve, a flow rate control valve, a restriction part, and pressure sensors to measure pressure drop characteristics, compare them with references, and determine abnormalities, specifically focusing on the distance between the valve seat and element using a strain sensor to correct output and maintain accuracy over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the piezoelectric element driven valve operates with high opening and closing speed, displacement, and frequency, then the flow rate control response is improved, but the accuracy of flow rate control degrades and operation failures occur earlier
Solution Approach 1:
The patent applies preliminary action by performing self-diagnosis measurements before abnormality occurs. The system periodically measures pressure drop characteristics and compares them with reference values to detect changes in valve opening degree, allowing early detection of degradation trends before they lead to control failures.
Solution Approach 2:
The patent implements feedback by continuously monitoring pressure drop characteristics and comparing them with reference values. When deviations exceed predetermined thresholds, the system generates abnormality notifications, enabling real-time feedback on valve performance degradation and allowing corrective action before complete failure occurs.
2Productivity
If the piezoelectric element driven valve operates with high opening and closing frequency, then the productivity is improved, but the operation failures increase
Solution Approach 1:
The system performs preliminary diagnostics by measuring pressure drop characteristics at regular intervals during high-frequency operation. This allows detection of cumulative degradation effects from repeated cycling before they result in operational failures, enabling maintenance scheduling that prevents downtime.
Solution Approach 2:
The valve system performs self-diagnosis by autonomously measuring its own pressure drop characteristics and comparing them against reference values. This self-monitoring capability allows the system to track its own degradation without external intervention, enabling proactive maintenance while maintaining high productivity.
3Reliability
If the valve element is pressed against the valve seat with sufficient pressing force, then the valve closes properly, but the strain sensor output span degrades over time
Solution Approach 1:
The patent applies parameter changes by using pressure drop characteristics as an alternative measurement parameter that remains stable over time. Instead of relying on the degrading strain sensor output span, the system measures pressure differential across the valve to determine opening degree, providing a stable reference that does not degrade with repeated pressing cycles.
Solution Approach 2:
The patent introduces pressure drop measurement as an intermediary parameter that indirectly indicates valve opening degree without being affected by strain sensor degradation. This intermediary measurement method provides a stable reference that mediates between the mechanical pressing force and the control system, eliminating the degradation issue.
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 provides a self-diagnostic solution that maintains flow rate control accuracy over long periods by detecting changes in strain sensor output span and correcting it, thereby preventing early-stage accuracy degradation and operation failures in high-speed applications.
Implementation Method 1
a piezoelectric element for moving the valve element to seat on/off the valve seat
Implementation Method 2
measuring a pressure drop characteristic of the fluid pressure
Data Source
AI summary
A self-diagnosis method of a flow rate control device includes: a step (a) for measuring a pressure drop characteristic after a pressure control valve (6) has been changed to a closed state from a state where a fluid flows from the upstream side of the pressure control valve with the opening of a flow rate control valve (8) is larger than a restriction part; a step (b) for measuring the pressure drop characteristic after the pressure control valve has been changed to the closed state from a state where the fluid flows from the upstream side of the flow rate control valve to the downstream side with the opening of the flow rate control valve is smaller than the restriction part; a step (c) for determining whether there is an abnormality by comparing the pressure drop characteristic measured in step (a) with a corresponding reference pressure drop characteristic; a step (d) for determining whether there is an abnormality by comparing the pressure drop characteristic measured in step (b) with a corresponding reference pressure drop characteristic; and a step (e) for determining that there is an abnormality in the flow rate control valve when it is determined that there is an abnormality only in the step (d).