Sealing Device for Polymer Filtration with Pressure-Responsive Bias
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Solution Overview
Problem
Existing screen changers in polymer extrusion face issues with excessive wear and polymer leakage due to high sealing forces and trapped polymer degradation, which leads to contamination.
Innovation Solution
A sealing device with a light preload bias and an axial gap regulating member made of a material with a higher coefficient of expansion, allowing for increased polymer pressure to enhance sealing without trapping excessive polymer, minimizing wear and degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring with a large spring constant is used to produce substantial biasing sealing force, then polymer leakage is prevented, but excessive wear or damage occurs to the seal and slide plate surfaces
Solution Approach 1:
The patent transitions from a static high-force spring system to a dynamic pressure-responsive system where the sealing force varies with polymer pressure. The seal is biased against the slide plate with a light preload by a spring, but during extrusion, polymer pressure entering the seal cavity provides additional axial force against the thrust surface, dynamically increasing the sealing force to match operating conditions without causing excessive wear during idle periods
Solution Approach 2:
The patent changes the parameter of sealing force from a constant high value to a variable value that responds to polymer pressure. The spring provides a light preload bias, and the polymer pressure in the seal cavity modulates the total sealing force, allowing the system to adapt sealing strength to actual operating needs, preventing both leakage and excessive wear
2Reliability
If a spring with a large spring constant is used to produce substantial biasing sealing force, then polymer leakage is prevented, but a large amount of force is required to move the slide plate
Solution Approach 1:
The system uses a light spring preload that requires minimal force to overcome during slide plate movement. The substantial sealing force is generated dynamically during extrusion when polymer pressure acts on the thrust surface, rather than being present as a constant mechanical bias that would resist slide plate translation
Solution Approach 2:
The seal system uses the polymer pressure itself to generate the sealing force rather than relying on an external high-force spring. The polymer pressure that drives extrusion also provides the axial force against the thrust surface, making the sealing mechanism self-powered and eliminating the need for a large biasing spring that would hinder slide plate operation
3Reliability
If seal design regions or cavities trap excessive quantities of polymer, then sealing is maintained, but the trapped polymer overheats and degrades forming undesirable contaminants
Solution Approach 1:
The patent applies different qualities to different regions: the seal cavity provides sealing function, while the polymer pressure gap is designed with specific dimensions to allow thin film flow and minimize polymer trapping. The axial gap regulating member creates a controlled local region that prevents excessive polymer accumulation while maintaining sealing integrity
Solution Approach 2:
The axial gap regulating member is formed of a material with a higher coefficient of thermal expansion than the seal and housing. As temperature increases, this member expands to minimize the size of the polymer pressure gap, preventing excessive polymer from being trapped and thermally degraded in the gap region
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 seals both low and high-pressure polymers, reducing wear and contamination by allowing a thin polymer film to exert axial force, while the expanding gap minimizes trapped polymer and heat degradation.
Implementation Method 1
A spring device can be positioned around the outer periphery surfaces of the seal for axially biasing the sealing surface of the seal against the slide plate with a preload bias
Implementation Method 2
The axial gap regulating member can be formed of a material having a higher coefficient of expansion than the seal and the housing, for expanding and minimizing the size of the polymer pressure gap as heat increases
Implementation Method 3
Increasing pressure of polymer in the extrusion bore can enter a region in the seal cavity upstream of the thrust surface and can provide polymer pressure in the axial direction for exerting axial force against the thrust surface of the seal
Data Source
AI summary
A sealing device for sealing a slide plate in a polymer filtration apparatus where the slide plate is translatable across an extrusion bore extending through a housing of the polymer filtration apparatus. A spring device can be positioned around the outer periphery surfaces of the seal for axially biasing the sealing surface of the seal against the slide plate with a preload bias. Increasing pressure of polymer in the extrusion bore can enter a region in the seal cavity upstream of the thrust surface of the seal and can provide polymer pressure in the axial direction for exerting axial force against the thrust surface of the seal for causing the sealing surface to be further biased against the slide plate.