Metal-Coupler Rotor Structure for Short, Durable Direct Drive Coupling

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Solution Overview

Problem

Direct drive clothes washing machine motors require a rotor that balances low cost, short axial length, and strong/durable coupling with the drive shaft, as existing steel rotors are heavy and costly, while plastic rotors are less durable and require longer axial lengths.

Innovation Solution

A rotor design featuring a metallic coupler with a splined inner surface and a polymeric frame with reinforcement ribs and magnet spacers, which includes a metallic coupler with a multiplicity of teeth and an annular retention surface, and a polymeric frame with a hub and side wall, providing secure engagement and reduced axial length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If steel rotors are used, then strength and durability are improved, but weight and cost increase

Engineering Contradiction:

Improvecoupling strengthVSAvoidrotor weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The rotor uses a composite structure combining a metal coupler (providing strength) with a plastic frame (reducing weight). The metal coupler is press-fit into the plastic frame hub, creating a hybrid component that leverages the advantages of both materials: the metal provides the necessary coupling strength with the drive shaft, while the plastic provides overall structural support with reduced weight compared to a fully metal rotor.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If plastic rotors are used, then weight and cost are reduced, but strength and durability worsen

Engineering Contradiction:

Improverotor weightVSAvoidcoupling strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The rotor is segmented into distinct functional components: a metal coupler for shaft engagement, a plastic frame for structural support, and a press-fit connection mechanism. This segmentation allows each component to be optimized for its specific function - the metal coupler handles the high-stress coupling function while the plastic frame provides lightweight structural support.

Inventive Principle:

Principle #1Segmentation

3Weight of moving object

If plastic rotors are used, then weight is reduced, but axial length increases

Engineering Contradiction:

Improverotor weightVSAvoidaxial length

Core Design Contradiction:

Weight of moving objectVSLength of moving object

Solution Approach 1:

The design changes the geometric parameters of the coupler and hub interface, specifically using a press-fit connection with optimized dimensional relationships. The coupler outer diameter, hub inner diameter, and press-fit interference fit parameters are carefully selected to achieve strong coupling in a compact axial space, avoiding the need for longer engagement lengths.

Inventive Principle:

Principle #35Parameter changes

4Strength

If steel rotors are used, then strength is improved, but cost increases

Engineering Contradiction:

Improvecoupling strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

5Ease of manufacture

If plastic rotors are used, then cost is reduced, but durability worsens

Engineering Contradiction:

Improvemanufacturing costVSAvoidcoupling durability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10003236B2Direct drive rotor with metal coupler

Publication Date: 2018.06.19 NIDEC MOTOR CORP

AI summary

A rotor for an outer rotor-type motor is provided. The rotor includes a metallic coupler and a polymeric frame molded over at least part of the metallic coupler.