Acoustically insulated machine
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Solution Overview
Problem
Conventional acoustical insulation methods for noise-generating machines are inadequate in reducing low-frequency sound transmission, as they often reflect a significant portion of sound energy back into the machine, leading to increased noise levels in residential environments.
Innovation Solution
The implementation of a multi-layer acoustic insulation member comprising porous sound-absorbing layers and denser facing layers, where the facing layers are oriented to allow a majority of low-frequency sound energy to pass into the sound-absorbing layers, thereby minimizing reflection and enhancing sound absorption, particularly in the 100 to 800 Hz frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional acoustical insulation methods are used, then high-frequency sound transmission is reduced, but low-frequency sound energy is reflected back into the machine, increasing noise levels
Solution Approach 1:
The acoustical insulation is divided into multiple functional layers: a sound absorption layer (fiberglass or similar porous material) and a separate sound reflection barrier (metal or plastic sheet). This segmentation allows each layer to perform its specific function - the absorption layer handles high-frequency sounds while the barrier manages low-frequency reflections, preventing noise amplification.
Solution Approach 2:
The insulation system combines two different materials with complementary acoustic properties: porous sound-absorbing material and dense sound-reflecting barrier material. This composite structure enables simultaneous management of both high-frequency transmission and low-frequency reflection, resolving the contradiction between reducing sound transmission and preventing noise level increase.
2Object-affected harmful factors
If a dense facing layer is used to block sound, then sound transmission is reduced, but low-frequency sound energy is reflected back into the machine
Solution Approach 1:
The facing layer is segmented into two distinct components: a dense barrier layer for blocking sound transmission and a separate sound absorption layer positioned to intercept reflected low-frequency energy. This segmentation prevents the single layer from both blocking and reflecting, as each component handles one function.
Solution Approach 2:
The sound absorption layer acts as an intermediary between the dense facing layer and the noise source. It intercepts low-frequency sound energy that would otherwise be reflected by the dense layer, converting it to heat and preventing the reflection back into the machine while maintaining the blocking function of the facing layer.
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 configuration significantly reduces the reflection of low-frequency sound energy, trapping most of it within the insulation member and allowing only a small portion to pass through, resulting in a substantial decrease in noise emission from machines like washing machines and dishwashers, effectively making them quieter.
Implementation Method 1
The blanket of glass fibers absorbs some of the sound energy entering the fiberglass absorber
Implementation Method 2
a plurality of porous, sound absorbing layer
Implementation Method 3
the insertion of a reflecting sound barrier within the acoustical insulation also reduces the sound transmission through the insulation product
Data Source
AI summary
Acoustically insulated machines have an internal source of noise and an insulation member. The insulation member may include a plurality of porous, sound absorbing layers and a plurality of dense or facing layers attached to faces of the sound absorbing layers. The dense or facing layers each have a density that is greater than the densities of the sound absorbing layers. The insulation member may be oriented such that one of the dense or facing layers faces toward the internal source of noise. The insulation member may be configured such that most of the low frequency sound energy generated by the internal source of noise is not reflected back into the machine. That is, the dense or facing layer may be configured to allow a majority of low frequency sound energy from the internal source of noise to pass into the insulation member.