Spring Biased Plug Valve Sealing Reliability
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Solution Overview
Problem
Existing plug valves face challenges in maintaining a secure seal over a long lifetime while being cost-effective, especially in plastic valves, due to manufacturing variations, temperature effects, and medium pressure fluctuations, which require flexible sealing elements that integrate both sealing and tolerance compensation functions.
Innovation Solution
A plug valve design featuring a rotating plug supported by spring elements that press against trunnions, which in turn engage with an annular sealing element, allowing for independent adjustment of contact force and tolerance range, with the spring elements protected from the medium and minimizing frictional losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexible sealing elements are integrated into the plug structure to compensate for manufacturing tolerances and temperature effects, then sealing reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The sealing system is segmented into separate functional components: the plug with integrated sealing lip, the separate spring element for force application, and the annular seating. This segmentation allows each component to be optimized independently - the sealing lip integrates with the plug for tolerance compensation, while the separate spring provides adjustable pressing force without complicating the sealing element design.
Solution Approach 2:
A spring element is introduced as an intermediary between the plug and the sealing system. This spring mediates the force transmission, allowing independent adjustment of the pressing force on the sealing lip without affecting the sealing element's structural design. The spring acts as a buffer that decouples the force application mechanism from the sealing function.
2Manufacturing precision
If separate spring elements are used to support the plug, then tolerance compensation and sealing force adjustment are improved, but device complexity increases due to additional components
Solution Approach 1:
The sealing lip is merged with the plug body to form an integrated sealing element. This combination eliminates the need for separate sealing rings or lips that would require additional mounting structures and seals. The integrated design compensates for manufacturing tolerances and temperature effects directly at the plug-seating interface while reducing the total component count.
Solution Approach 2:
The spring element is designed to be self-contained and self-lubricating, requiring no additional maintenance or adjustment mechanisms. The spring automatically compensates for wear and dimensional changes over time, maintaining consistent sealing force without requiring external intervention or complex control systems.
3Reliability
If spring elements are protected from the medium, then reliability is improved, but device complexity increases due to additional sealing requirements
Solution Approach 1:
The valve interior is segmented into a medium-exposed zone and a protected zone. The spring element is positioned in the protected zone, isolated from the medium by the plug body and guide groove structure. This spatial segmentation allows the spring to maintain its mechanical properties without degradation from medium exposure while using the existing plug geometry as a natural barrier.
Solution Approach 2:
The guide groove and plug body act as intermediary structures that physically separate the spring element from the medium. These intermediaries provide mechanical guidance for the spring while simultaneously serving as protective barriers, eliminating the need for additional seals or protective housings around the spring.
4Manufacturing precision
If the plug is supported in a floating manner, then tolerance compensation is improved, but positioning accuracy may be compromised
Solution Approach 1:
The plug is given different local properties: the body is designed to float freely for axial movement and tolerance compensation, while the trunnions are precisely shaped and fitted into guide grooves for accurate rotational positioning. This local differentiation allows the plug to simultaneously achieve both floating support for tolerance compensation and precise positioning for accurate operation.
Solution Approach 2:
The degree of freedom of the plug is dynamically changed through the spring force. When the spring is uncompressed, the plug can move axially to compensate for tolerances. When the spring is compressed to the operating position, the axial movement is constrained, providing precise positioning while maintaining the ability to accommodate dimensional variations through elastic deformation of the spring and sealing elements.
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
This design ensures reliable sealing with reduced leakage and displacement force fluctuations, allowing for easy rotation and assembly, while maintaining accuracy and reducing costs by separating the tasks of sealing and spring force application.
Implementation Method 1
wherein the plug is supported in a floating manner against a spring force, wherein at least one spring element bearing against the valve housing presses the plug against the annular sealing element
Implementation Method 2
wherein a pressurized, blocked-off medium generates an additional force component, which influences a floating movement of the plug
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a plug valve with a plug (11) supported around its axis of rotation in a flow passageway of the valve housing (1), the plug is supported in a floating manner against a spring force pressing the plug against an annular sealing element (23). The spring force is provided by a spring element (20, 21) bearing against the valve housing (1) and engaging with a trunnion (16, 17) of the plug. The sealing element (23) is supported in a fixed position against a flow passage opening (2).