Flow Control Valve Segmented Seat for Precise Small Gas Flow
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Solution Overview
Problem
Conventional flow control valves in mass flow controllers face challenges in achieving smooth, flat, and parallel contact surfaces, which are essential for precise control of small flow rate ranges, due to structural limitations that hinder effective polishing and processing of these surfaces.
Innovation Solution
A flow control valve design where the valve seat and valve body are configured as separate cylindrical members, allowing for precise manipulation and polishing of the contact surface without obstruction, enabling smoothness, flatness, and parallelism, and ensuring accurate control of gas flow rates in small flow ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the valve seat is designed as an integrated structure with the outer cylindrical part, then the structural simplicity is improved, but the manufacturing precision of the contact surface deteriorates due to obstruction in polishing access
Solution Approach 1:
The valve seat is divided into two separate parts: the outer cylindrical part and the inner cylindrical part. This segmentation allows the contact surface on the inner cylindrical part to be accessed and polished from the top without obstruction, while the outer cylindrical part provides the discharge passage structure. The separation resolves the conflict between structural simplicity and manufacturing precision by allowing independent optimization of each part.
2Manufacturing precision
If the contact surface requires high smoothness for small flow rate control, then the flow control precision is improved, but the ease of manufacture deteriorates due to difficult polishing access
Solution Approach 1:
By separating the valve seat into outer and inner cylindrical parts, the contact surface on the inner cylindrical part becomes accessible from the top for polishing operations. This segmentation eliminates the obstruction problem and allows standard polishing tools to reach the contact surface, significantly improving ease of manufacture while maintaining high flow control precision.
Solution Approach 2:
The design changes the accessibility dimension by allowing polishing access from the top direction rather than requiring lateral or bottom access. The inner cylindrical part is positioned such that its contact surface can be reached from the top, transforming the polishing operation from a difficult lateral access problem to a simple top-down operation.
3Reliability
If the valve body and actuator are airtightly isolated by a diaphragm, then the reliability is improved by preventing gas leakage, but the device complexity increases due to additional isolation components
Solution Approach 1:
A metal diaphragm is used to airtightly isolate the valve body and actuator. The diaphragm serves as a flexible barrier that prevents gas leakage while accommodating relative movements between the valve body and actuator. This thin film solution provides reliable gas isolation without requiring complex rigid isolation structures, thus improving reliability while minimizing the increase in device complexity.
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 design achieves a smooth contact surface with improved accuracy and precision in controlling gas flow rates in small flow ranges, preventing fluid leakage and enhancing the durability and reliability of the flow control valve.
Implementation Method 1
an elastic means which gives the valve body elastic force in a direction away from the contact surface of the valve seat or a direction approaching to the contact surface
Implementation Method 2
a piezo actuator which drives the valve body to be pushed back toward the contact surface of the valve seat against the elastic force by the spring
Data Source
AI summary
In a flow control valve which comprises a valve seat comprising an inner cylindrical part with a contact surface formed in its upper end part and an outer cylindrical part higher than the inner cylindrical member and a valve body that carries out an opening and closing action in a direction perpendicular to the contact surface of the valve seat, an inner cylindrical member and an outer cylindrical member, which are separate members, are airtightly fitted with each other to constitute the inner cylindrical part and the outer cylindrical part. As a result, by processing the contact surface of the inner cylindrical part to be smooth, the flow control valve can control flow rate of gas in a small flow rate range more accurately than before.