Hearing Protection Cap Vibration Damping Weight Elements
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Solution Overview
Problem
Existing hearing protection caps face challenges in effectively attenuating noise at higher frequencies above 1 kHz, as increasing weight to improve low-frequency sound attenuation leads to increased size and potential sound attenuation impairment, and current methods fail to address resonance issues effectively across the entire audible frequency range.
Innovation Solution
Incorporating vibration-damping weight elements with higher density than the cap shell, strategically positioned to block specific resonance peaks and modes of vibration, thereby enhancing sound attenuation without increasing the cap's size or material thickness, and allowing for precise placement and fixation through molding or other attachment methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the cap shell is increased to increase weight for better low-frequency sound attenuation, then sound attenuation in low frequency range is improved, but the cap becomes larger and more unwieldy
Solution Approach 1:
The patent applies local quality by adding weight elements only at specific locations within the cap shell rather than uniformly increasing thickness throughout. This localized approach increases weight for sound attenuation while maintaining a compact overall cap size, resolving the contradiction between sound attenuation performance and cap dimensions.
2Reliability
If the thickness of the cap shell is increased inwards to increase weight, then weight is increased for better sound attenuation, but the inner volume decreases and sound attenuation is impaired
Solution Approach 1:
The patent resolves this contradiction by locally adding weight elements at specific positions within the cap shell rather than uniformly increasing thickness. This allows weight to be increased for sound attenuation while preserving the inner volume necessary for acoustic performance, as the weight elements are strategically placed without compromising the internal space.
3Reliability
If metal filler is added to the plastic cap shell to increase weight, then low frequency sound attenuation is improved, but tool wear increases and strength properties are compromised
Solution Approach 1:
The patent applies segmentation by separating the weight addition function from the cap shell material itself. Instead of mixing metal filler throughout the plastic (which compromises strength and causes tool wear), discrete weight elements are added as separate components. This resolves the contradiction by achieving weight increase for sound attenuation without compromising the structural integrity or manufacturing quality of the cap shell.
4Reliability
If extra weights are added inside the closed cavity to increase cap shell weight and separate resonance frequencies, then low frequency sound attenuation is improved, but no solution is provided for high frequency resonance damping
Solution Approach 1:
The patent resolves this limitation by strategically positioning weight elements at specific locations within the cap shell that correspond to high-frequency resonance modes. This localized placement allows the same weight elements to address both low-frequency sound attenuation and high-frequency resonance damping, thereby expanding the frequency range coverage without adding separate solutions for each frequency band.
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
Significantly improves sound attenuation at high frequencies, avoids tool wear and strength reduction issues associated with adding metal to plastic, and reduces production costs and cooling times in injection molding, while maintaining or reducing the cap's size and weight.
Implementation Method 1
the cap comprises a cap shell which supports at least one vibration-damping weight element, said weight element being arranged so as to at least partly block an audio mode of vibration that would have existed in the cap in the absence of said weight element
Implementation Method 2
noise at certain frequencies or in certain frequency ranges may create resonance phenomena in the caps of the hearing protection
Data Source
AI summary
The present invention relates to a cap (11) intended for use as hearing protection and adapted to enclosed the external ear of a user, characterized by at least one vibration-damping weight element (18, 38a-b) of the cap (11), which weight element is arranged so as to at least partly block an audio mode of vibration that would have existed in the cap in the absence of said weight element (18, 38a-b). The invention also relates to a method of producing such a cap, and use of the same.