Compressor Muffler Outlet Nodal Positioning for Noise Reduction
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Solution Overview
Problem
Existing compressors, including rotary and scroll types, face challenges in reducing pressure pulsations and associated noise due to muffler outlets often being positioned near antinodes of resonance modes, leading to incomplete noise reduction.
Innovation Solution
A compressor design featuring a muffler with outlets along the outer periphery of the shaft and a constriction that narrows the passage towards the outlet, allowing the refrigerant to flow through the vicinity of nodes, reducing pressure pulsations and noise. The muffler's encircling part is bent to form a continuous cylindrical flow straightening part, enhancing noise reduction without requiring an asymmetric shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the muffler outlets are disposed in the vicinity of a node of a first-order resonance mode to reduce noise, then the noise reduction effect is improved, but the outlets inevitably fall within the vicinity of the antinodes of higher-order resonance modes (second-order, third-order, etc.), which limits the overall noise reduction effectiveness
Solution Approach 1:
The patent transitions from a two-dimensional planar view outlet arrangement to a three-dimensional spatial arrangement. The outlet is positioned at the end of a passage extending axially through the muffler body, allowing the outlet to be located at a position that corresponds to a node in the axial direction for multiple resonance modes simultaneously, rather than being constrained to a single planar position.
Solution Approach 2:
The muffler is divided into distinct functional sections: a passage section with the outlet, a bulged section for pressure pulsation reduction, and a connection section. This segmentation allows the outlet to be positioned in the passage section where it can exploit nodal positions for multiple resonance modes, while the bulged section handles the primary pressure pulsation reduction function.
2Object-affected harmful factors
If the muffler is given an asymmetric shape in planar view to displace outlets from antinodes of second-order resonance mode, then noise reduction for second-order mode is improved, but this approach does not address third-order and higher-order resonance modes
Solution Approach 1:
Instead of modifying the planar shape of the muffler (two-dimensional approach), the patent utilizes the axial dimension (three-dimensional approach) to position the outlet. The outlet is located at the end of a passage that extends axially through the muffler, allowing nodal positioning that is effective for multiple resonance modes without requiring asymmetric planar shaping.
Solution Approach 2:
The axial passage outlet design serves multiple functions simultaneously: it positions the outlet at a nodal position for first-order resonance mode, maintains effectiveness for second-order and higher-order modes, and provides a straightforward manufacturing approach. This universal solution replaces the need for mode-specific asymmetric shaping.
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 design effectively minimizes pressure pulsations and noise by positioning the muffler outlets near nodes of resonance modes, achieving a high noise reduction effect while maintaining design flexibility.
Implementation Method 1
pressure pulsations are linked to the intrinsic resonance property which is determined by the shape of the internal space of the muffler
Implementation Method 2
continuous with a circular cylindrical flow straightening part lying on an upper side of the main body of the muffler
Implementation Method 3
A refrigerant suctioned into the compression chamber is compressed with rotation of the piston rotor
Implementation Method 4
a piston rotor which is rotated eccentrically inside the cylinder
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
To provide a compressor which can produce a high noise reduction effect by sufficiently reducing pressure pulsations of a refrigerant discharged from a muffler outlet. A rotary compressor 1 includes: a compression mechanism 20 which compresses a refrigerant with rotation of a shaft 123; and a muffler 30 which is provided around the shaft 123 opposite to the compression mechanism 20 and receives the refrigerant discharged from the compression mechanism 20. A muffler outlet 38 for discharging the refrigerant inside the muffler 30 opens annularly along an outer periphery of the shaft 123. A constriction 36, at which a passage of the refrigerant flowing toward the muffler outlet 38 is narrowed in the length direction of the shaft 123, is formed around the shaft 123 inside the muffler 30.