Earplug Stem Biaxial Stiffness and Tip Cavity Bonding
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Solution Overview
Problem
Existing earplugs often face conflicts between sound attenuation, comfort, and ease of insertion, with dense tips providing effective sound blocking but being uncomfortable, and less dense tips offering poor sound attenuation but easier insertion, while stiff stems can be difficult to insert safely.
Innovation Solution
An earplug design featuring a tip with a rearward recessed cavity and a stem with biaxial stiffness, where the stem's elongate portion is stiffer laterally than normally, and a member with a surface for adhesive bonding to the tip, allowing for adaptive insertion and improved structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tip is made very dense to attenuate a large amount of sound, then sound attenuation is improved, but comfort and ease of insertion deteriorate
Solution Approach 1:
The earplug employs different foam densities in different regions: a denser forward portion for effective sound attenuation and a less dense rearward portion for comfort and ease of insertion. This local variation in material density allows each region to optimize its function without compromising the other.
Solution Approach 2:
The tip is segmented into distinct density zones - a forward portion with higher density for sound blocking and a rearward portion with lower density for comfort. This segmentation enables the earplug to simultaneously achieve effective sound attenuation and user comfort.
2Ease of operation
If the stem is made relatively stiff to facilitate easy insertion, then ease of operation is improved, but safety deteriorates due to risk of deep insertion upon impact
Solution Approach 1:
The stem incorporates a dynamic stiffness characteristic - it is relatively stiff during normal insertion to guide proper placement, but can deform or collapse under excessive force or impact. This dynamic response allows the stem to be easy to insert while preventing deep insertion injury when subjected to accidental impacts.
Solution Approach 2:
The stem's stiffness parameter is designed to change under different loading conditions. During normal insertion, the stem maintains sufficient stiffness for easy handling and placement. However, under excessive force or impact, the stem's structural integrity changes, allowing it to deform or collapse, thereby preventing transmission of harmful forces to the ear canal.
3Ease of operation
If the tip is made less dense to improve comfort and ease of insertion, then ease of operation is improved, but sound attenuation deteriorates
Solution Approach 1:
The earplug employs different foam densities in different regions: a denser forward portion for effective sound attenuation and a less dense rearward portion for comfort and ease of insertion. This local variation in material density allows each region to optimize its function without compromising the other.
4Object-affected harmful factors
If the stem is made more flexible to improve safety, then safety is improved, but ease of insertion deteriorates
Solution Approach 1:
The stem incorporates a dynamic stiffness characteristic - it is relatively stiff during normal insertion to guide proper placement, but can deform or collapse under excessive force or impact. This dynamic response allows the stem to be easy to insert while preventing deep insertion injury when subjected to accidental impacts.
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 design enhances user safety and comfort by facilitating easy and safe insertion while maintaining effective sound attenuation, with the biaxial stiffness of the stem and adaptive polymer foam tip ensuring proper fit and reduced risk of deep insertion or injury.
Implementation Method 1
a member (50)... which includes a surface (51) to be adhered to an interior facing surface of the cavity (26)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An earplug is provided and includes a tip for use in forward and lateral sealing, which is formed to define a rearward recessed cavity, and a stem. The stem includes a user graspable elongate portion configured with a stiffness in a first direction that is greater than a stiffness in a second direction, which is transverse to the first direction, and a member, disposed at a forward end of the elongate portion and configured to be insertable into the cavity, the member including a surface to be adhered to an interior facing surface of the cavity and on which a channel is defined to allow for outflow from the cavity, and the member being formed with a shape to complement that of the cavity to axially and circumferentially align the tip and the stem.