Permanent Magnet Rotor Bracket Design for Vibration Reduction
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Solution Overview
Problem
Conventional permanent magnet rotors have low reliability due to the thinner portions of the over mould member breaking during rotation, leading to reduced motor performance and increased noise and vibration.
Innovation Solution
A permanent magnet rotor design featuring a bracket with a base, end ring, and axially extending arms that securely hold arcuate magnets, providing an interference fit and balancing receptacles to enhance assembly and stability, reducing cogging torque and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an over mould member is used to fix permanent magnets to the rotor core, then the magnets can be securely held, but the thinner portions of the over mould member break during rotation leading to low reliability
Solution Approach 1:
The bracket is divided into multiple arms that are spaced circumferentially around the rotor core. Each arm independently holds one or more permanent magnets, creating segmented support structures that distribute mechanical stresses and prevent single-point failures that would occur in a continuous over-mould member.
Solution Approach 2:
The bracket design provides locally optimized support at each magnet position through individual arms. Each arm can be specifically designed to match the dimensions and fixation requirements of the magnets it supports, ensuring uniform thickness and strength at all critical locations without the thickness variation problems of conventional over-mould members.
2Reliability
If a bracket with multiple arms is used to hold magnets, then rotor reliability is improved, but the device complexity increases
Solution Approach 1:
Multiple functional elements are merged into a single bracket component. The bracket simultaneously provides magnet support, centrifugal force resistance, and structural connection between the rotor core and end ring, eliminating the need for separate fixation elements and reducing overall assembly complexity despite the multi-arm configuration.
Solution Approach 2:
The bracket serves multiple functions: it holds the permanent magnets, resists centrifugal forces during rotation, provides structural support for the rotor core, and enables balanced assembly through integrated weighting features. This multi-functionality reduces the need for additional components and simplifies the overall rotor design.
3Ease of manufacture
If the inner diameter of the end ring is greater than the outer diameter of the rotor core, then assembly is simplified, but the precision of magnet positioning may be affected
Solution Approach 1:
The bracket is pre-formed with precise arm positions and magnet holding features before assembly. This preliminary fabrication of the bracket ensures accurate magnet positioning is built into the structure itself, allowing for easier assembly with the rotor core and end ring without compromising positioning precision.
Solution Approach 2:
The bracket acts as an intermediary component between the rotor core and the permanent magnets. It provides a pre-positioned framework that guides magnet placement and ensures precise positioning, while also serving as the mechanical connection that simplifies the overall assembly process.
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
The design improves rotor reliability and reduces motor noise and vibration by securely fastening magnets and allowing for balanced assembly, enhancing overall motor performance.
Implementation Method 1
the bracket is an interference fit with the rotor core
Data Source
AI summary
A permanent magnet rotor includes a shaft, a rotor core fixed to the shaft, a bracket fixed to the rotor core, and a plurality of permanent magnets contacting an outer surface of the rotor core. The bracket includes a base at one axial end thereof, a plurality of arms axially extending from the base and spaced in a circumferential direction, and an end ring connecting the arms at the other axial end thereof. The base has an opening for the insertion of the shaft. The rotor core is positioned between the arms. Each magnet is sandwiched between two adjacent arms. An inner diameter of the end ring is greater than an outer diameter of the rotor core.