Polymer Seal Assembly for Low-Temperature Hydraulic Strut Sealing
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Solution Overview
Problem
Conventional dynamic seals used in hydraulic systems, such as those in aircraft landing gear, face issues with wear, brittleness, and leakage due to elastomer materials, which become ineffective at low temperatures and require frequent replacement.
Innovation Solution
A seal assembly comprising a plastic polymer-based seal body and spring, designed with specific dimensions and materials, including a fluoroplastic and polyimide, that provides improved durability and sealing capacity, along with a unique installation method using specialized tooling to avoid damage during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If elastomer materials are used for dynamic seals, then deformability and resilience are improved, but wear resistance and durability deteriorate
Solution Approach 1:
The seal assembly uses a composite structure combining a polymer seal body with an elastomeric backup ring. The polymer material (such as PTFE or other fluoroplastics) provides wear resistance and chemical inertness, while the elastomeric backup ring provides deformability and resilience. This composite approach resolves the contradiction by allowing each material to contribute its superior properties to the overall seal performance.
2Adaptability or versatility
If elastomer materials are used for dynamic seals, then resilience is improved, but service life deteriorates due to quick wear and tearing
Solution Approach 1:
The combination of polymer and elastomeric materials creates a seal assembly where the polymer face provides durable wear resistance for extended service life, while the elastomeric backup ring maintains resilience for proper sealing function throughout the extended service period.
3Reliability
If elastomer materials are used for dynamic seals, then sealing capacity is improved, but performance at low temperatures deteriorates due to hardening and brittleness
Solution Approach 1:
The seal assembly divides functional requirements into different materials: the polymer seal body provides temperature stability and structural integrity at low temperatures, while the elastomeric backup ring provides localized sealing compliance. This local specialization allows the assembly to maintain sealing capacity across a wide temperature range.
4Ease of manufacture
If conventional elastomer seals are used, then installation is simple, but frequent replacement is required due to wear and deterioration
Solution Approach 1:
The polymer-elastomer composite seal assembly maintains the simplicity of elastomer installation while dramatically extending service life through the wear-resistant polymer face, thereby improving operational availability by reducing replacement frequency.
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 seal assembly demonstrates significantly reduced leakage rates and extended operational cycles, maintaining effectiveness even at low temperatures, with a leakage rate of no greater than 0.05 mL per simulated flight cycle for over 2000 cycles, and avoids damage during installation.
Implementation Method 1
a spring disposed adjacent to the seal body
Data Source
AI summary
A seal assembly includes a seal body, a spring disposed adjacent to the seal body, and a seal ring disposed adjacent to the seal body. The seal body and the seal ring can include a plastic polymer material. The seal assembly can be a subcomponent of hydraulic strut in the landing gear of an aircraft.