Regulating Valve Gland Packing Thermal Expansion Control
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Solution Overview
Problem
Conventional regulating valves using yarn packings experience deterioration in seal performance due to shared deformation and increased contact surface pressure from thermal expansion, leading to fluid leakage and reduced sealing efficiency when subjected to thermal and mechanical cycles.
Innovation Solution
A regulating valve design featuring a gland portion with a single yarn packing sandwiched by adapter packings with a lower thermal expansion coefficient and higher hardness, along with carbon rings and disc springs, to manage thermal expansion and prevent deformation-induced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the thermal expansion of yarn packing is prevented by using disc springs, then contact surface pressure stability is improved, but the structure becomes more complex and space is consumed
Solution Approach 1:
The invention extracts the thermal expansion compensation function from the disc spring system and transfers it to the adapter packings. By selecting materials with low thermal expansion coefficients for the adapter packings, the compensation function is built into the packing structure itself, eliminating or reducing the need for disc springs and their associated complexity.
Solution Approach 2:
The adapter packings act as intermediary elements between the yarn packing and the valve stem. These intermediaries absorb the thermal expansion effects before they can reach the yarn packing and valve stem interface, thereby maintaining stable contact surface pressure without requiring complex spring mechanisms.
2Stability of the object's composition
If adapter packings with lower thermal expansion coefficient are introduced, then thermal expansion impact on yarn packing is reduced, but device complexity increases
Solution Approach 1:
The adapter packings serve multiple functions simultaneously: they provide a sealing interface with the valve stem, absorb thermal expansion effects, and protect the yarn packing from deformation. This multi-functionality justifies the additional structural element by consolidating several protective and functional roles into a single component layer.
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 effectively suppresses the deterioration of seal performance by reducing the thermal expansion impact on the yarn packing, maintaining leak rates within acceptable limits even after multiple mechanical cycles, thereby enhancing the overall sealing efficiency.
Implementation Method 1
adapter packings with a lower thermal expansion coefficient and higher hardness than the yarn packing
Implementation Method 2
a packing follower (7) disposed on the adapter packings opposite to the valve box, a disc spring (8) disposed on the packing follower
Data Source
AI summary
A regulating valve that includes a valve stem for driving a valve body, and a gland portion slidably holding the valve stem, the gland portion including a lid portion having a through-hole communicating with the inside of the valve box, the valve stem being inserted into the through-hole, a spacer provided between the inner wall of the through-hole and the valve stem, one yarn packing disposed above the spacer, at least two adapter packings disposed via the yarn packing in a slide direction of the valve stem, the adapter packings being made of a material having a smaller thermal expansion coefficient and a higher hardness than the yarn packing, a packing follower disposed on the adapter packings opposite to the valve box, a disc spring disposed on the packing follower, and a packing flange disposed above the disc spring and the packing follower, the packing flange being fixed to the lid portion.