Electroactive Polymer Seal Actuator for Creep Compensation
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Solution Overview
Problem
Conventional seals made of rubber materials face issues such as creep, leading to loss of sealing force over time, and are difficult to monitor for failure, especially in isolated locations, with limited resealing capabilities and durability in dynamic systems.
Innovation Solution
The use of a multilayer actuator structure with electrically-conductive polymer electrodes and a dielectric electroactive polymer layer that expands when an electric potential is applied, providing a resealing capability by increasing the sealing effect at the interface, and incorporating a polymer sensing element to monitor distortion and apply electrical stimulation for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional rubber seals are used, then flexibility and ease of manufacture are improved, but sealing force is lost over time due to creep
Solution Approach 1:
The patent uses composite materials by combining electroactive polymer layers with conventional rubber seal materials. The EAP layer is integrated into the seal structure to provide active compensation for creep, while the rubber provides baseline sealing properties. This composite approach allows the seal to maintain both ease of manufacture and reliable sealing force over time.
Solution Approach 2:
The patent introduces dynamic behavior to the seal by incorporating electroactive polymer layers that can actively change their mechanical properties in response to electrical stimulation. This dynamic compensation mechanism allows the seal to counteract creep and maintain sealing force, transforming the seal from a passive static component to an active dynamic system.
2Adaptability or versatility
If seals are installed in isolated locations, then system coverage is improved, but monitoring capability deteriorates
Solution Approach 1:
The patent makes the seal multi-functional by integrating sensing capabilities directly into the sealing element. The seal not only performs its primary sealing function but also monitors its own condition and the surrounding environment. This universal approach allows isolated seals to both seal and monitor, eliminating the need for separate monitoring systems.
Solution Approach 2:
The patent enables the seal to monitor itself by incorporating embedded sensors and electroactive layers that can detect changes in the seal's own state (such as distortion, temperature, or pressure) and respond autonomously. This self-service capability allows the seal to detect and report its condition without external monitoring equipment.
3Reliability
If seal compression is increased to improve sealing, then sealing effect is improved, but seal durability deteriorates
Solution Approach 1:
The patent uses dynamic electroactive polymer layers that can actively adjust their compression force on demand. Instead of maintaining constant high compression, the EAP layers provide supplemental sealing force only when needed (such as when creep occurs or leakage is detected), allowing the seal to maintain effective sealing while reducing overall compression and extending seal life.
Solution Approach 2:
The patent implements periodic or on-demand actuation of the electroactive polymer layers rather than continuous high compression. The EAP layers are activated periodically to compensate for seal degradation or leakage events, allowing the seal to maintain effectiveness through intermittent reinforcement rather than constant high stress, thereby extending durability.
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 enables the actuator to maintain or restore sealing effectiveness by expanding in response to electrical stimulation, extending the life of sealing elements and reducing leakage, while allowing for timely replacement and monitoring of seal conditions.
Implementation Method 1
When a sufficient electrical potential is applied to the electrodes, Coulomb forces cause electrostatic stresses to occur that cause the viscoelastic EAP material to reallocate its volume, forcing it to constrict in thickness and expand (strain) in the in-plane (length and width) directions.
Implementation Method 2
Dielectric EAP materials are a subclass of electric EAPs that are viscoelastic and exhibit properties similar to dielectric materials of capacitors when positioned between two conductive electrodes that apply a large voltage
Data Source
AI summary
Actuators and methods utilizing electrical properties of polymer materials. The actuators have a multilayer structure that includes an electroactive polymer layer between and bonded to first and second electrodes so that the polymer layer has a thickness dimension therebetween. The multilayer structure is adapted so that application of an electric potential to the electrodes causes the electroactive polymer layer to expand in at least one dimension thereof transverse to the thickness dimension of the electroactive polymer layer. The actuators can be used in sealing elements to provide a resealing capability once a condition has occurred of a type that may precede a seal failure.