Shape Memory Seal Assembly for Dynamic Gap Sealing
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Solution Overview
Problem
Seals in applications like thrust reversers face issues such as fatigue due to repeated compression and decompression cycles, and initial installation challenges due to unpredictable geometry and tolerance stack-ups, leading to potential leakage and increased installation time.
Innovation Solution
A seal assembly utilizing shape memory material actuation members that transition from a low energy state to a high energy state, causing the body member to elastically expand and exert sealing pressure, and revert back to the original state when temperature changes, thereby actively managing the sealing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional seals are continuously compressed to ensure sealing, then sealing reliability is improved, but seal fatigue and compression set increase due to repeated cycling
Solution Approach 1:
The seal assembly transitions from a static compressed state to a dynamic system that alternates between compressed and relaxed states. The shape memory alloy actuator dynamically adjusts the seal body's compression level based on operational requirements, allowing the seal to be compressed during operation for reliable sealing and relaxed during non-operation to prevent fatigue and compression set.
Solution Approach 2:
The invention changes the compression parameter of the seal dynamically rather than maintaining constant compression. By using shape memory alloy actuators that respond to temperature changes, the seal's compression state is adjusted between high compression (during operation for sealing) and low compression (during non-operation to reduce stress), thereby extending seal life while maintaining reliability.
2Reliability
If seals are pre-compressed during installation to ensure engagement, then sealing contact is improved, but unpredictable geometry and tolerance stack-ups cause over-compression or inadequate engagement
Solution Approach 1:
The seal assembly incorporates an active control system that automatically adjusts compression based on actual engagement conditions. The shape memory alloy actuator monitors and responds to the seal's position and compression state, self-correcting for geometric variations and tolerance stack-ups without requiring precise pre-compression during installation.
Solution Approach 2:
The invention replaces passive mechanical pre-compression with an active thermally-driven actuation system. Instead of relying on mechanical shims and precise installation forces, the shape memory alloy actuator uses temperature-induced phase changes to actively control seal compression, compensating for geometric variations and ensuring proper engagement.
3Reliability
If linear seals are rigged with customized shims to adjust compression, then sealing performance is improved, but installation time and labor requirements increase significantly
Solution Approach 1:
The invention extracts and eliminates the need for complex shim-based adjustment mechanisms from the installation process. By integrating a shape memory alloy actuator directly into the seal assembly, the system achieves active compression control without requiring external shims, reducing installation complexity and time while maintaining sealing performance.
Solution Approach 2:
The shape memory alloy actuator serves multiple functions: it provides active compression control, compensates for geometric variations, and eliminates the need for separate adjustment mechanisms like shims. This multi-functional component simplifies the overall assembly and reduces installation time while ensuring reliable sealing performance.
4Reliability
If seal assemblies are over-compressed to ensure sealing, then leakage prevention is improved, but excessive force increases and may damage the sealing surface or seal
Solution Approach 1:
The seal assembly incorporates feedback through the shape memory alloy actuator's thermal response characteristics. The actuator monitors compression conditions and automatically adjusts the applied force based on temperature and engagement state, preventing over-compression while ensuring sufficient sealing force is applied during operation.
Solution Approach 2:
The system transitions from static over-compression to dynamic force control. The shape memory alloy actuator adjusts compression force in real-time based on operational status, applying high force during operation for leakage prevention and reducing force during non-operation to prevent surface damage and seal degradation.
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 solution reduces seal cycling, minimizes compression set, and ensures consistent sealing performance by actively expanding to fill gaps during operation, while reverting to the original state during non-operation, thus reducing installation complexity and maintaining effective sealing without excessive compression.
Implementation Method 1
one or more actuation members constructed from a shape memory material having a high energy state and a low energy state. The one or more actuation members are configured to urge the body member of the seal assembly from the original state into the expanded state when the shape memory material transitions from the low energy state to the high energy state
Implementation Method 2
a body member configured to elastically expand from an original state into an expanded state. The body member exerts a sealing pressure against the surface of the seal depressor when in the expanded state
Data Source
AI summary
A seal assembly configured to seal against a surface of a seal depressor is disclosed. The seal assembly includes a body member configured to elastically expand from an original state into an expanded state. The body member exerts a sealing pressure against the surface of the seal depressor when in the expanded state. The seal assembly also includes one or more actuation members constructed from a shape memory material having a high energy state and a low energy state. The one or more actuation members are configured to urge the body member of the seal assembly from the original state into the expanded state when the shape memory material transitions from the low energy state to the high energy state.