Rotor Imbalance Compensation via Pre-Assembly Positioning

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Solution Overview

Problem

High-speed electrical machines often experience imbalance due to production deviations, leading to unwanted vibrations, noise, and premature failure, which existing balancing methods struggle to address effectively, especially in high-performance machines where negative-balancing can damage the rotor and increase mass and length.

Innovation Solution

A method that involves measuring and calculating the precise mounting positions for sheet metal packages and magnets on the rotor shaft to minimize imbalance before assembly, allowing for potential positive-balancing compensation post-installation without sacrificial masses, thereby reducing weight and length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If negative balancing is used to compensate for rotor imbalance, then the imbalance is reduced, but the rotor mass and axial length increase due to sacrificial balancing discs

Engineering Contradiction:
Improverotor imbalanceVSAvoidrotor mass
Core Design Contradiction:
Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The invention measures and records the individual imbalances of shafts, laminated cores, and magnets before assembly. Based on these pre-measured values, the mounting positions of components are calculated in advance to achieve optimal balance compensation, eliminating the need for sacrificial balancing discs and subsequent material removal.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If negative balancing is used to compensate for rotor imbalance, then the imbalance is reduced, but the rotor axial length increases due to sacrificial balancing discs

Engineering Contradiction:
Improverotor imbalanceVSAvoidrotor axial length
Core Design Contradiction:
Manufacturing precisionVSLength of moving object

Solution Approach 1:

The invention measures and records the individual imbalances of shafts, laminated cores, and magnets before assembly. Based on these pre-measured values, the mounting positions of components are calculated in advance to achieve optimal balance compensation, eliminating the need for sacrificial balancing discs and subsequent material removal.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If positive balancing is used to compensate for rotor imbalance, then the rotor mass increases, but the method is insufficient for high imbalance compensation in high-speed machines

Engineering Contradiction:
Improverotor imbalanceVSAvoidrotor mass
Core Design Contradiction:
Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The invention measures and records the individual imbalances of shafts, laminated cores, and magnets before assembly. Based on these pre-measured values, the mounting positions of components are calculated in advance to achieve optimal balance compensation, eliminating the need for sacrificial balancing discs and subsequent material removal.

Inventive Principle:
Principle #10Preliminary action

4Manufacturing precision

If individual components are measured and optimized before assembly, then the rotor imbalance is minimized, but the manufacturing process complexity increases

Engineering Contradiction:
Improverotor imbalanceVSAvoidmanufacturing process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention measures and records the individual imbalances of shafts, laminated cores, and magnets before assembly. Based on these pre-measured values, the mounting positions of components are calculated in advance to achieve optimal balance compensation, eliminating the need for sacrificial balancing discs and subsequent material removal.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3471244B1Method for assembling of electrical machine rotors
Publication Date: 2021.09.08 DR ING H C F PORSCHE AG
  • EP3471244B1 patent drawingFigure 1

AI summary

Assembly method for rotors (18) of electrical machines, wherein each rotor (18) comprises a shaft (12), one or more laminated cores with magnet pockets arranged on the shaft, and magnets (15) arranged in the magnet pockets, comprising at least the following steps: providing shafts (12) and measuring the imbalance of at least one shaft (12); providing laminated core segments (13) and measuring the imbalance of at least one laminated core segment (13); providing several magnets (15) and measuring the weight of the magnets (15); for each rotor to be manufactured: selecting one or more laminated core segments (13), selecting a shaft (12), selecting magnets (15), determining mounting positions for the selected magnets (15) in the magnet pockets or of the selected laminated core segments, and calculating a mounting position for the selected laminated core segments (13).Mount the magnets (15) in the calculated mounting positions in the magnet pockets of the laminated core segments (13). Mount the laminated core segments (13) on the shaft (12) in the mounting position.