Manual Selective Attenuator for Compressor Noise
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Solution Overview
Problem
Existing sound attenuation systems for positive displacement compressors, such as mufflers, are ineffective in adjusting to changing frequency ranges of noise produced by compressors due to variable operational speeds and loads, as they are designed to target fixed frequencies and require physical modification or replacement to adapt.
Innovation Solution
A manual selective attenuator that acts as an adjustable resonator, allowing HVAC technicians to modify the volume of the discharge cavity to resonate and cancel undesirable noise frequencies, enabling tuning across a range of frequencies without system shutdown or part replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mufflers are designed to target fixed frequencies, then sound attenuation at specific frequencies is achieved, but the attenuator becomes ineffective when compressor operating speed and noise frequency change
Solution Approach 1:
The patent applies the dynamics principle by making the resonator volume adjustable rather than fixed. The resonator includes a movable partition that can be repositioned to change the volume of the resonating chamber, allowing the attenuator to adapt to different operating frequencies. This dynamic adjustment capability resolves the contradiction between maintaining effective attenuation and adapting to frequency changes.
Solution Approach 2:
The patent implements parameter changes by modifying the physical volume parameter of the resonator. By changing the resonator volume through movable partition adjustment, the resonant frequency of the attenuator is tuned to match the current operating frequency of the compressor, thereby maintaining attenuation effectiveness across variable operating conditions.
2Adaptability or versatility
If mufflers are physically modified or replaced to change target frequency, then the frequency response is adjusted, but system shutdown and physical modification are required
Solution Approach 1:
The movable partition design enables dynamic adjustment of resonator volume without requiring system shutdown. The partition can be repositioned while the compressor is operating, allowing frequency tuning to be performed in-situ and eliminating the need for physical modification or replacement of the entire muffler assembly.
Solution Approach 2:
The attenuator is designed to be self-adjusting through the movable partition mechanism. The partition can be manually or automatically repositioned to change resonator volume, enabling the system to self-tune to different operating frequencies without external intervention for physical modification or replacement.
3Ease of manufacture
If resonator volume is fixed, then manufacturing and installation are simplified, but the attenuator cannot be adjusted to different operating conditions
Solution Approach 1:
The resonator is segmented into adjustable sections by the movable partition. This segmentation allows the resonator volume to be divided and reconfigured, providing adjustment capability while maintaining a relatively simple overall structure that does not require complex manufacturing processes.
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 manual selective attenuator effectively reduces undesirable noise by allowing real-time adjustments to the discharge cavity volume, maintaining sound attenuation across changing frequency ranges without the need for system deactivation or part replacement, ensuring continuous operation and adaptability.
Implementation Method 1
the resonance characteristics of the sound of the pulsations of the compressed gas discharged into the discharge chamber are modified. When the plug is adjusted within the bore to a preselected position wherein the tuning chamber achieves a volume that resonates the most undesirable sound
Implementation Method 2
pulsations produced by the compressor occur at a resonant wavelength of the most undesirable noise frequencies, producing a cancellation effect
Data Source
AI summary
An attenuating apparatus for use with a positive displacement compressor. The device includes a bore formed in a housing of the compressor, the bore being positioned at an angle to a discharge chamber of the compressor and in fluid communication with the compressor discharge chamber. A plug is positioned within the bore, the plug movable within the bore to a preselected position. The plug has a first end in contact with a gas from the compressor discharge chamber and a second, opposite end being accessible from an exterior of the housing. A seal is positioned between the plug and the bore to seal an interface between the plug and the bore to prevent leakage of a gas from the compressor discharge chamber along the interface. The plug is lockable within the bore at the preselected position. The preselected position of the plug within the bore determines a bore length in fluid communication with the compressor discharge chamber, which attenuates sound from gas pulsations resulting from discharge of compressed gas from the operation of the compressor. The bore and plug are threaded to facilitate the adjustment of the plug within the bore.