Cryogenic Shut-Off Valve With Pivot Ball Flow Control
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Solution Overview
Problem
Existing cryogenic fluid shut-off valves struggle to reliably control the flow of extremely cold fluids like liquid helium and liquid hydrogen due to the extreme operating conditions, leading to inefficiencies and potential contamination.
Innovation Solution
A shut-off valve design featuring a valve body, bonnet, plug, stem, spindle, and pivot ball mechanism that allows for precise control of cryogenic fluid flow, using materials capable of withstanding extreme temperatures and incorporating a buffer to minimize contamination and debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shut-off valve designs are used for cryogenic fluids, then the valve structure is simple and easy to manufacture, but the valve fails to reliably control flow under extreme cold temperatures
Solution Approach 1:
The valve is divided into multiple functional segments: a valve body for fluid flow, a bonnet assembly for actuation, a plug for sealing, a stem for motion transmission, and a spindle with pivot ball for mechanical advantage. Each segment is optimized for its specific function while working together to achieve reliable cryogenic flow control.
Solution Approach 2:
The stem is housed within the bonnet chamber, and the pivot ball is positioned between the stem and spindle, creating a nested arrangement where smaller components are contained within larger ones. This reduces overall valve size while maintaining functional integrity under cryogenic conditions.
2Ease of manufacture
If standard sealing mechanisms are used, then the valve is easier to manufacture, but particle ingress and contamination occur at cryogenic temperatures
Solution Approach 1:
The plug features a sealing edge specifically designed for fluid-tight engagement with the valve seat, and the bonnet includes a buffer zone that creates an additional barrier. These localized quality enhancements at critical sealing points prevent particle ingress without requiring complete redesign of the entire valve structure.
3Manufacturing precision
If a direct-actuation mechanism is used, then the valve has fewer moving parts and is simpler, but it cannot provide precise control under extreme operating conditions
Solution Approach 1:
The actuation mechanism transforms rotational motion of the spindle into linear motion of the plug through the pivot ball and stem assembly. This dynamic motion conversion allows precise control of the sealing edge position against the valve seat, enabling accurate flow control while the plug slides along the longitudinal axis of the bonnet.
Solution Approach 2:
The stem acts as an intermediary component that transmits motion from the spindle-pivot ball assembly to the plug. The stem converts the mechanical advantage provided by the pivot ball into precise linear displacement of the sealing edge, enabling fine flow control without direct coupling between the actuator and plug.
4Temperature
If materials not designed for cryogenic temperatures are used, then the valve is cheaper and easier to manufacture, but the valve cannot withstand extreme cold fluids like liquid helium and hydrogen
Solution Approach 1:
The valve employs materials specifically selected for cryogenic service, including austenitic stainless steel or other low-temperature resistant materials for the valve body, bonnet, plug, and stem. These materials maintain ductility and strength at extreme temperatures, preventing brittle failure while withstanding the mechanical stresses of cryogenic fluid operation.
Data Source
AI summary
Shut-off valves for cryogenic fluids are disclosed herein. An example valve includes a valve body defining a flow path and a valve seat, a bonnet coupled to the valve body and defining a bonnet chamber, a plug, and a stem coupled to the plug. The stem is configured to slide to cause the plug to slide. The valve includes a spindle that includes external threads. The spindle is configured to move along a longitudinal axis of the bonnet as the spindle is rotated about the longitudinal axis via the external threads to cause the stem to slide linearly along the longitudinal axis. The valve includes a pivot ball positioned between and operatively coupled to the stem and the spindle. The pivot ball is configured to translate linear and rotational movement of the spindle into linear movement of the stem and the plug.