Expandable Shield for Bellows Corrosion Protection
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Solution Overview
Problem
Valves in chemical vapor deposition systems face corrosion and deposition issues due to the use of corrosive gases, which can shorten their service life and require frequent shut-downs, especially when thin stainless steel bellows are exposed to corrosive gases even when the valve is closed, as existing protective measures do not effectively isolate the bellows in such scenarios.
Innovation Solution
A valve apparatus with an expandable and contractible shield that surrounds the bellows, providing a vacuum-tight hermetic seal and protecting them from corrosive gases and deposition, regardless of the valve's open or closed position, by using a stationary and movable shield section that creates a pressurized space with inert gas to prevent gas and particle ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective cup is used around the bellows to isolate the bellows from the valve chamber when the valve is open, then the bellows is protected from corrosive gases during open valve operation, but the bellows remains exposed to corrosive gases when the valve is closed
Solution Approach 1:
The shield is designed to be movable rather than fixed, allowing it to dynamically adjust its position based on valve operation. The shield moves between a retracted position (when valve is open) and an extended position (when valve is closed), ensuring continuous protection of the bellows regardless of valve state. This dynamic adaptation resolves the contradiction by making protection effective in both open and closed valve conditions.
2Reliability
If the shield is extended to fully protect the bellows, then the bellows is completely isolated from corrosive gases, but the shield may interfere with the reciprocating motion of the valve actuator
Solution Approach 1:
The shield is divided into multiple sections or segments that can move independently. This segmentation allows the shield to extend sufficiently to protect the bellows while accommodating the reciprocating motion of the valve actuator through coordinated movement of different segments. The segmented design resolves the contradiction by providing complete protection without obstructing actuator operation.
3Adaptability or versatility
If thin stainless steel bellows are used to accommodate reciprocating motion, then the bellows has sufficient flexibility for valve operation, but the thin material is vulnerable to chemical attack and corrosion
Solution Approach 1:
The movable shield acts as an intermediary protective barrier between the thin stainless steel bellows and the corrosive gases in the valve chamber. This intermediate shield provides the necessary protection against chemical attack while allowing the bellows to maintain its thin, flexible design for reciprocating motion. The shield resolves the contradiction by decoupling the requirements for flexibility and corrosion resistance.
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 solution effectively prolongs the lifespan of the bellows by preventing corrosion and deposition, maintaining a vacuum-tight seal and ensuring continuous operation without the need for frequent repairs or shut-downs, even in manifold valve assemblies where multiple valves share a common chamber.
Implementation Method 1
a bellows positioned to isolate the valve chamber and is impervious to air or gas to provide a vacuum-tight hermetic seal from the piston cylinder, piston, and other components that may not operate at the same pressure as the valve chamber
Implementation Method 2
by using a stationary and movable shield section that creates a pressurized space with inert gas to prevent gas and particle ingress
Data Source
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AI summary
An expandable and contractible shield around a bellows in a valve protects the bellows from corrosive gases and solid particles in the valve chamber. In a manifold valve assembly with multiple outlet ports and multiple valves in a common valve chamber, a respective expandable and contractible shield around each respective bellows of each respective valve in the assembly separates each bellows from corrosive gases and solid particles in the common valve chamber regardless of whether one or all of the valves in the assembly is opened or closed.