Spoked Rotor With Deflectable Prongs for Adhesive-Free Magnet Clamping

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Solution Overview

Problem

Conventional rotor designs for electric motors face challenges with magnet positioning and retention, including high material costs, increased part counts, and size issues due to the use of adhesives or endcaps, which complicate the assembly and increase costs.

Innovation Solution

A rotor design featuring a core with arcuately arranged pole segments and magnets, where the pole segments have prongs that deflect to create a clamping force on the magnets, securing them in place without the need for adhesives or additional parts, allowing for secure retention and reduced size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high strength adhesive is used between rotor core and magnets, then magnet retention is improved, but material cost increases and cure time is required

Engineering Contradiction:

Improvemagnet retentionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes the adhesive substance from the system entirely, replacing it with a mechanical retention mechanism using deflectable prongs that physically clamp the magnets between pole segments, thereby eliminating material costs and cure time requirements while maintaining magnet retention

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the chemical bonding mechanism (adhesive) with a mechanical retention system consisting of deflectable prongs that apply clamping force to secure magnets, transitioning from chemical to mechanical means of attachment

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If endcaps are used to trap magnets, then magnet retention is improved, but device complexity and total parts increase

Engineering Contradiction:

Improvemagnet retentionVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the magnet retention function into the pole segments themselves by incorporating deflectable prongs directly into the pole segment structure, eliminating the need for separate endcaps and reducing total part count while maintaining retention capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The pole segments serve dual functions: they provide the magnetic pole structure and simultaneously act as retention mechanisms through their deflectable prongs, combining structural and retention functions into a single component

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If adhesives or endcaps are used for magnet retention, then magnet positioning is improved, but rotor size increases

Engineering Contradiction:

Improvemagnet positioningVSAvoidrotor size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent uses thin, deflectable prongs that can bend and conform to the magnet geometry, providing secure retention without requiring thick additional structures, thereby maintaining compact rotor dimensions while ensuring proper magnet positioning

Inventive Principle:

Principle #30Flexible shells and thin films

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 design securely retains magnets within the rotor core without additional parts or adhesives, reducing costs and maintaining minimal air gaps in the magnetic flux path, thereby enhancing motor performance.

Implementation Method 1

at least one of the first and second prongs is deflected by the magnet received in the respective magnet-receiving slot, such that the prongs cooperatively apply a clamping force on the magnet

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11791679B2Spoked rotor having deflectable magnet-retaining spokes

Publication Date: 2023.10.17 NIDEC MOTOR CORP

AI summary

A rotor includes magnets and a core including arcuately arranged pole segments. Each pole segment includes first and second prongs that extend away from the rotor axis and are at least in part arcuately spaced apart to define a cutout therebetween. Each pair of arcuately adjacent pole segments defines therebetween a respective magnet-receiving slot, with the first prong of one of the pole segments and the second prong of the other of the pole segments defining the slot. The magnets are received in slots, such that each of the magnets is at least in part interposed between one of the pairs of adjacent pole segments. The magnets and the pole segments are dimensioned and configured so that at least one of the first and second prongs is deflected by the magnet received in the respective slot, such that the prongs cooperatively apply a clamping force on the magnet.