Self-Contracting Tether for Hearing Protection Using Shape Memory Polymer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional tethers for personal protective devices, such as earplugs, often come in standard lengths that may not accommodate all users, leading to packaging inefficiencies and user discomfort, as they are not easily adjustable.
Innovation Solution
A tether made from a polymer blend, such as ethylene vinyl acetate (EVA) and thermoplastic polyurethane (TPU), that can be stretched to multiple lengths by the user and self-contracts to a shorter length when heated, allowing for customizable length adjustment and efficient storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard length tether is used for personal protective devices, then manufacturing and packaging are simplified, but user comfort and adaptability are reduced
Solution Approach 1:
The tether is designed with dynamic length adjustment capability through a reel mechanism that allows the tether to be extended or retracted as needed. The reel includes a spool and a reel arm that rotates to wind or unwind the tether, enabling the tether length to change from an initial extended state to a retracted state, thus adapting to different user needs while maintaining a compact form for manufacturing and storage.
Solution Approach 2:
The tether system changes its effective length parameter through the reel mechanism. The tether can be deployed to a full length for use and then retracted to a shorter length for storage or transport. This parameter change is achieved through the mechanical action of the reel arm rotating to wind the tether onto the spool, allowing the same tether to serve multiple length requirements without requiring multiple different tether products.
2Adaptability or versatility
If a longer tether is provided to accommodate all users, then adaptability is improved, but packaging space and device complexity increase
Solution Approach 1:
The tether is nested within the reel mechanism, with the tether winding around the spool and being contained within the housing of the reel assembly. When the tether is not in use, it is completely retracted and stored within the compact reel structure, significantly reducing the space required for packaging compared to providing a long extended tether. The reel arm and spool are nested within the housing, creating a compact overall structure that minimizes packaging volume.
Solution Approach 2:
The tether transitions from a static long length to a dynamically adjustable length that can be extended or retracted as needed. The reel mechanism allows the tether to be wound onto the spool, reducing its effective length from a full extended state to a compact retracted state, thereby minimizing packaging space while maintaining adaptability for different user requirements.
3Reliability
If a tether is permanently attached to earplugs, then loss prevention is improved, but ease of adjustment and storage are reduced
Solution Approach 1:
The tether is permanently attached to the earplugs through the reel mechanism, ensuring loss prevention, but the tether's effective length is dynamically adjustable. The reel arm can be rotated to wind or unwind the tether, allowing the user to adjust the tether length according to their needs. The tether remains securely attached to the earplugs at all times, but its operational length can be changed by simply rotating the reel arm, making adjustment easy while maintaining security.
Solution Approach 2:
The reel mechanism is designed to be manually operated by the user without requiring additional tools or complex procedures. The user can easily rotate the reel arm to adjust the tether length or to retract the tether for storage. The spring-loaded spool automatically winds the tether when the reel arm is rotated, providing self-service functionality that simplifies the adjustment and storage process while maintaining permanent attachment for loss prevention.
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
Enables users to select desired tether lengths with minimal force, maintaining the stretched state until heated to self-contract, reducing packaging needs and enhancing user comfort and convenience.
Implementation Method 1
A tether made from a polymer blend, such as ethylene vinyl acetate (EVA) and thermoplastic polyurethane (TPU), that can be stretched to multiple lengths by the user and self-contracts to a shorter length when heated
Implementation Method 2
self-contracts to a shorter length when heated, allowing for customizable length adjustment and efficient storage
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
A tether for a personal protective device. The tether provides an initial length (L1). The tether is configured to self-retain a stretched length (L2) when stretched. The tether is further configured to self-transition or self-contract from the stretched length (L2) to a recovered length (L3) when heated. With this construction, the tether can be stretched by a user to the stretched state in which the stretched length (L2) approximates the length desired by the user; following use, the tether can be contracted to the recovered length (L3) for storage. Or, if the stretched length (L2) is longer than desired by the user, the tether can be contracted to a desired length in the recovered state (i.e., the recovered length (L3)) and then worn. The tether can be formed from a polymer blend of EVA and TPU.