Compressor Rotor Protrusions Reduce Drive Shaft Bending

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Solution Overview

Problem

Compressors used in air conditioners experience noise generation due to vibration caused by the bending eigenvalue of the drive shaft, which is challenging to prevent from resonating effectively.

Innovation Solution

The rotor of the compressor is designed with stacked metal plates that protrude toward the stator in the radial direction, increasing the magnetic attraction force in specific sections to alleviate the bending of the drive shaft, thereby reducing the centrifugal force's impact and minimizing vibration-induced noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a balance weight is provided on the rotor to counteract centrifugal force, then rotational balance is improved, but drive shaft bending and vibration-induced noise worsen

Engineering Contradiction:
Improverotational balanceVSAvoiddrive shaft bending and vibration noise
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The rotor employs localized quality variation through protrusions on specific metal plates that are closer to the stator, creating non-uniform magnetic attraction forces in specific regions rather than uniform distribution, thereby generating counteracting forces against drive shaft bending

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The protrusions on the metal plates function as magnetic counterweights by generating enhanced magnetic attraction forces that oppose the centrifugal force-induced bending of the drive shaft, effectively counterbalancing the harmful vibrations without adding physical mass

Inventive Principle:
Principle #8Anti-weight (Counterweight)

2Strength

If the drive shaft is made stiffer to reduce bending, then drive shaft strength is improved, but resonance at bending eigenvalue becomes more difficult to suppress

Engineering Contradiction:
Improvedrive shaft strengthVSAvoidresonance suppression
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The rotor protrusions generate preliminary counteracting magnetic forces that act against the centrifugal force before the drive shaft can bend significantly, preventing the resonance condition from developing fully even in stiffer drive shafts

Inventive Principle:
Principle #9Preliminary anti-action

3Stability of the object's composition

If metal plates are stacked to form the rotor, then rotor structure is improved, but magnetic attraction force distribution becomes non-uniform causing drive shaft bending

Engineering Contradiction:
Improverotor structureVSAvoidmagnetic attraction non-uniformity and bending
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The metal plates are designed with localized protrusions on specific plates, creating intentional non-uniform magnetic attraction in targeted regions to counteract centrifugal force effects, transforming the harmful non-uniformity into a beneficial counterbalancing mechanism

Inventive Principle:
Principle #3Local quality

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 effectively reduces the bending amount of the drive shaft, leading to a decrease in noise generated by vibration caused by the bending eigenvalue, resulting in a quieter operation.

Implementation Method 1

a magnetic attraction force generated adjacent to the stator is larger in a section from which the metal plates protrude than a magnetic attraction force in a section from which the metal plates do not protrude

Methodology Applied
Scientific EffectMagnetic attraction force: Magnetism

Implementation Method 2

a balance weight is provided as a weight, on the upper surface or the lower surface of the rotor... in order to keep balance with a centrifugal force generated by the rotation of the roller

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3217014B1compressor
Publication Date: 2019.05.22 MITSUBISHI HEAVY IND THERMAL SYST
  • EP3217014B1 patent drawingFigure 1
  • EP3217014B1 patent drawingFigure 2
  • EP3217014B1 patent drawingFigure 3

AI summary

A compressor is provided that is capable of reducing a bending amount of a drive shaft to reduce noise generated by vibration caused by a bending eigenvalue. The compressor is provided with: a compression mechanism; a motor that includes a rotor (13) formed by a plurality of steel plates stacked on top of each other, and a stator (12) provided around an outer circumferential portion of the rotor (13); and a drive shaft (14) that connects the motor and the compression mechanism. A first balance weight (35) is provided on the surface of the rotor located remote from the compression mechanism in the axial direction of the drive shaft (14), and of the stacked steel plates, a steel plate (13A) adjacent to the first balance weight (35) protrudes toward the stator (12) located remote from the first balance weight (35) in the radial direction of the rotor (13) with respect to the axis of the drive shaft (14).