Plastic Diaphragm Valve Sealing Without Elastomer Backing
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Solution Overview
Problem
Conventional diaphragm valves with plastic diaphragms rely on elastomer backing cushions for sealing, which can lead to issues such as crushing during thermal expansion and contraction, loose seals, and reduced pressure capacity due to elastomer creep deformation.
Innovation Solution
The implementation of diaphragm valves with reduced or no elastomer backing cushions, where peripheral or all sealing forces are applied directly to the plastic diaphragm, utilizing a pressure ring and internal springs to provide enhanced sealing forces, allowing pressures up to 4400 psi (30.74 MPa) even on poor surface finishes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomer backing cushion is used for sealing, then sealing capability is improved, but pressure capacity is reduced due to elastomer creep deformation
Solution Approach 1:
The patent removes the elastomer backing cushion from the diaphragm valve assembly, extracting the component that causes creep deformation under pressure. This elimination allows the valve to achieve higher pressure capacity (up to 4400 psi) while maintaining sealing through alternative means such as precision-machined surfaces and direct diaphragm contact, without the degradation associated with elastomer creep.
2Reliability
If elastomer backing cushion is used for sealing, then sealing capability is improved, but device complexity is increased due to additional elastomer components
Solution Approach 1:
The patent eliminates the elastomer backing cushion and associated elastomer components, simplifying the overall assembly. This reduction in component count and complexity is achieved by relying on the diaphragm's inherent properties and precision-machined sealing surfaces, thereby reducing assembly steps and potential failure points while maintaining effective sealing.
Solution Approach 2:
The patent integrates the sealing function directly into the diaphragm and valve body structure, merging what were previously separate functions (elastomer cushion for sealing + rigid structure for support) into a unified design where the diaphragm itself provides both structural support and sealing capability through direct contact with precision-machined surfaces.
3Reliability
If elastomer backing cushion is used for sealing, then sealing capability is improved, but thermal expansion and contraction causes crushing and loose seals
Solution Approach 1:
The patent removes the elastomer backing cushion that is susceptible to thermal degradation, eliminating the component that expands and contracts with temperature changes. This extraction prevents the cyclic crushing and loosening that occurs with elastomer materials under thermal cycling, thereby improving seal stability across extreme temperature ranges.
Solution Approach 2:
The patent changes the material parameter from elastomer (which has high thermal expansion and contraction) to rigid materials with stable dimensional properties under thermal conditions. This parameter change in the sealing mechanism's material composition eliminates the thermal cycling issues associated with elastomer expansion and contraction, maintaining consistent sealing pressure across temperature extremes.
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 enhances sealing capabilities, increases pressure capacity, and simplifies assembly by eliminating complex elastomer components, reducing actuator size and cost while maintaining reliable seals under extreme thermal and mechanical cycles.
Implementation Method 1
a spring positioned above the diaphragm and in communication with the pressure ring to apply an elastic force to the pressure ring
Implementation Method 2
adjust for thermal expansion and contraction of the valve assembly
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Technologies are described for diaphragm valves with plastic diaphragm and reduced or no elastomer backing cushion, where peripheral or all sealing forces may be applied directly to the diaphragm of the valve assembly. In various examples, the valve assemblies may include a pressure ring to apply sealing force to a surface of the diaphragm with a reduced size or no backing cushion allowing a two-fold or more increase in pressure capacity of the valve assembly. In other examples, an elastomer or metallic spring placed above a center diaphragm boss may provide center-to-edge compliance for passage seal.