Turbo Compressor Motor Casing Geometry for High-RPM Resonance Control
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Solution Overview
Problem
Turbo compressors and refrigerators face challenges in stabilizing motor operation at high rpm due to resonance issues caused by the planar blocking cover, leading to increased noise and potential damage, limiting the motor's operational range.
Innovation Solution
The design incorporates a motor casing with a cylindrical body portion and an annular reduced diameter portion, along with a flat portion molded in a planar shape, which increases the natural frequency of vibration, allowing the motor to operate stably at higher rpms by shifting the resonance frequency beyond the original limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the blocking cover is molded in a planar shape, then the motor casing structure is simple, but the natural frequency of the flat portion is low causing resonance at low rpm
Solution Approach 1:
The patent applies curvature by replacing the planar flat portion with a dome-shaped flat portion that has an outward curvature in the radial direction. This curved geometry increases the natural frequency of vibration of the blocking cover, thereby raising the rpm at which resonance occurs, allowing the motor to operate stably at higher speeds without encountering resonance issues.
Solution Approach 2:
The patent changes the geometric parameters of the blocking cover by introducing a dome shape with a specific curvature radius (R1) that is at least 0.05 times the outer diameter of the flat portion. This parameter change modifies the vibrational characteristics of the blocking cover, increasing its natural frequency and shifting the resonance point to a higher rpm range.
2Productivity
If the motor operates at high rpm, then productivity increases, but resonance occurs causing noise and potential damage
Solution Approach 1:
The dome-shaped configuration of the flat portion with outward curvature increases the structural stiffness and natural frequency of the blocking cover. This design modification allows the motor to operate at high rpm for improved productivity while avoiding resonance-induced noise and vibration by ensuring the operating speed remains below the elevated resonance threshold.
3Speed
If the flat portion diameter is reduced, then the natural frequency increases, but the motor casing volume decreases
Solution Approach 1:
The patent employs a dome-shaped flat portion that maintains a sufficient diameter for motor casing volume while introducing outward curvature to increase the natural frequency. The curvature radius R1 is designed to be at least 0.05 times the outer diameter, creating a balanced geometry that achieves both objectives: elevated natural frequency for high-rpm operation and adequate volume for motor accommodation.
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 enables the motor to operate reliably at higher rpms without generating resonance, enhancing the stability and performance of the turbo compressor and refrigerator systems.
Implementation Method 1
the natural frequency of the flat portion increases, so that the vibration frequency when generating the resonance of the flat portion increases
Data Source
AI summary
Provided is a turbo compressor that includes: a compressor unit compressing a gas; a motor driving the compressor unit; and a motor casing accommodating the motor. In the turbo compressor, the motor casing includes: a body portion which is molded in a cylindrical shape; an annular diameter reduced portion which is connected to at least one end portion of the body portion in the rotation axis direction of the motor and of which the diameter is reduced as it moves away from the body portion; and a flat portion which is connected to the central end portion of the diameter reduced portion and is molded in a planar shape.