Screw Compressor Gearbox Resonance Suppression
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Solution Overview
Problem
Screw compressors experience resonance issues due to a decrease in the natural frequency of the gearbox, leading to increased vibrations and reduced durability, when the compressor main body is attached to a substantially rectangular gearbox, especially with changes in mass and rigidity.
Innovation Solution
The configuration includes a compressor main body with a first flange extending outside the attachment surface of the gearbox, maintaining the rigidity of the connection portion and increasing the natural frequency of the gearbox, while reducing the mass of the tip end, and optimizing the attachment angle and structure with stiffening ribs and embedded oil pipes to enhance rigidity and reduce vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mass of the gearbox is increased, then the natural frequency of the gearbox decreases, but this causes resonance between the compressor main body and the gearbox
Solution Approach 1:
The tip end part of the gearbox is removed (extracted) to decrease the mass of the gearbox. This extraction of the non-essential tip end portion reduces the overall mass while maintaining the functional integrity of the gearbox, thereby increasing the natural frequency to avoid resonance without compromising structural reliability
Solution Approach 2:
The first flange is extended to the outside of the attachment surface, creating a local structural modification. This extension is positioned specifically at the attachment region to maintain connection rigidity while the tip end removal decreases overall mass. The local quality change allows differential optimization of different regions for different functions
2Reliability
If the extension amount of the first flange is increased to decrease the mass of the tip end part, then the natural frequency increases, but the rigidity of the connection portion is reduced
Solution Approach 1:
The first flange is extended locally to the outside of the attachment surface, creating a specific structural configuration where the extension amount is controlled. This local extension maintains the projection region of the rotor casing within the attachment surface, ensuring connection rigidity is preserved while the tip end removal decreases overall mass to increase natural frequency
Solution Approach 2:
The extension amount of the first flange is optimized as a critical parameter. By controlling this dimensional parameter, the design achieves a balance where the flange extends sufficiently to decrease tip end mass and increase natural frequency, but not so much that connection portion rigidity is compromised
Data Source
AI summary
A screw compressor 2 includes a compressor main body 4, a motor 8, and a gearbox 10. The compressor main body 4 includes screw rotors 5c, 5d, 6c, and 6d, rotor casings 5e and 6e accommodating therein the screw rotors 5c, 5d, 6c, and 6d, and main body casings 5a and 6a accommodating therein the rotor casings 5e and 6e, the main body casings being provided with first flanges 5b and 6b on respective ends thereof. The motor 8 drives the screw rotors 5c, 5d, 6c, and 6d via gears 10f and 10g. The gearbox 10 has an attachment surface Son which the first flange 6b to the main body casings 5a and 6a is attached, accommodates therein the gears 10f and 10g, and has a substantially rectangular shape. In a state where the compressor main body 4 is attached to the gearbox 10, a part of the first flange 6b extends to an outside of the attachment surface S, and projection regions of the rotor casings 5e and 6e onto the attachment surface S exist within the attachment surface S. In this way, vibrations of the screw compressor 2 can be reduced.