Push-in Earplug With Thermoplastic Foam Outer Layer

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Solution Overview

Problem

Push-in earplugs are costly and pose manufacturing challenges due to complex insertion methods requiring compression or 'rolling down' of sound attenuating portions, which can compromise hygiene and increase manufacturing complexity.

Innovation Solution

A push-in earplug design featuring a stiff elongate core covered with a soft outer layer, including a sound attenuating portion and a stem portion, where the outer layer is formed by activating an unactivated foaming agent to expand and bond thermally with the core, allowing direct insertion without compression, thus simplifying manufacturing and promoting hygiene.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional push-in earplugs use a compressible attenuating portion that requires rolling down before insertion, then the earplug can be inserted into the ear canal, but the manufacturing process becomes complex and costly

Engineering Contradiction:

Improveinsertion processVSAvoidmanufacturing process

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The earplug is divided into two distinct segments: a stiff stem portion for handling and insertion, and a separate compressible attenuating portion for noise reduction. This segmentation allows each part to be optimized independently - the stem can be made rigid for easy manipulation while the attenuating portion remains compressible for effective ear canal filling, eliminating the need for complex rolling-down operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The compression step is extracted from the insertion process by designing the attenuating portion to be pre-compressed during manufacturing. The attenuating portion is formed in a compressed state within the mold, so that during insertion it simply needs to be pushed into the ear canal without requiring the user to perform compression manually, thereby simplifying the operation.

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If the attenuating portion is made compressible for easy insertion, then insertion becomes simpler, but hygiene is compromised due to increased contact before insertion

Engineering Contradiction:

Improveinsertion simplicityVSAvoidhygiene contamination

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

By separating the stem portion from the attenuating portion, the design allows the attenuating portion to remain in its compressed, sterile state until insertion. The stem can be handled freely while the attenuating portion stays protected within its packaging, reducing contamination risk while maintaining insertion simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The attenuating portion is pre-compressed during manufacturing and packaged in a sterile state. This preliminary compression eliminates the need for user compression, and the sterile packaging prevents contamination before insertion, thereby maintaining hygiene while keeping the insertion process simple.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If a stiff portion is added to the earplug for easy insertion, then insertion becomes easier, but manufacturing cost increases

Engineering Contradiction:

Improveinsertion easeVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The stem portion and attenuating portion are combined into a single integrated earplug structure that can be manufactured in one continuous process. The stiff stem and compressible attenuating portion are formed as one piece using extrusion or molding techniques, eliminating the need for separate manufacturing and assembly steps, thereby reducing overall manufacturing cost despite the added functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The earplug uses composite construction with a stiff material for the stem portion and a compressible foam material for the attenuating portion. These different materials are combined in a single manufactured component, allowing each material to perform its specific function while being produced through an integrated process that avoids additional assembly costs.

Inventive Principle:

Principle #40Composite materials

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 earplug provides effective hearing protection with direct insertion, reducing manufacturing costs and complexity, while ensuring hygiene by eliminating the need for pre-compression of the sound attenuating portion, and allowing for a comfortable fit with controlled density and hardness.

Implementation Method 1

The outer layer includes an unactivated foaming agent. The method includes activating the foaming agent to form gas or cells in the outer layer.

Methodology Applied

Scientific EffectFoaming: Foam

Implementation Method 2

The second material includes thermoplastic spheres.

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3517084B1Push-in earplug

Publication Date: 2024.04.17 3M INNOVATIVE PROPERTIES CO

Figure 1~3D
Figure 4~6B
Figure 7A~7B

AI summary

An earplug (100) including an elongate core (110) and outer layer (120) is disclosed. The elongate core (110) comprises a first material and has first and second ends (111, 112) and an outer major surface. The outer layer (120) comprises a second material and covers at least a portion of the outer major surface of the elongate core (110). The second material comprises thermoplastic spheres