Composite Rotor Coupler for Short, Lightweight Direct Drive Motors

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

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 polymeric frame and hub, where the metallic coupler has an inner axial surface for interfacing with the shaft and an outer axial surface with multiple outer teeth that engage the hub to transmit torque, with specific dimensions optimizing strength and durability.

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 combines a polymeric frame material with a metallic coupler to create a composite structure. The polymeric frame provides lightweight construction while the metallic coupler provides the necessary strength and durability for coupling with the drive shaft, thus resolving the contradiction between strength and weight.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The rotor is divided into functionally distinct segments: a polymeric frame for lightweight support and a separate metallic coupler for strong, durable coupling. This segmentation allows each component to be optimized for its specific function, achieving both light weight and high strength where needed.

Inventive Principle:

Principle #1Segmentation

2Weight of moving object

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

Engineering Contradiction:

Improverotor weightVSAvoidcoupling strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The rotor uses a composite structure combining polymeric frame material with a metallic coupler. The polymeric material provides light weight and cost advantages, while the metallic coupler compensates for the lower strength of plastic by providing the necessary coupling durability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The rotor applies local quality enhancement by using metallic material specifically at the coupler region where strength and durability are most critical for coupling with the drive shaft, while the rest of the rotor body remains lightweight polymeric material.

Inventive Principle:

Principle #3Local quality

3Strength

If plastic rotors use adjusted coupling geometry for larger engagement area, then coupling strength is improved, but axial length increases

Engineering Contradiction:

Improvecoupling strengthVSAvoidaxial length

Core Design Contradiction:

StrengthVSLength of moving object

Solution Approach 1:

The invention changes the material parameter of the coupler from polymeric to metallic, which has higher strength density. This allows the coupler to achieve the required coupling strength with a more compact geometry, reducing the axial length while maintaining or improving coupling strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite structure with metallic coupler enables compact coupling geometry because the metallic material provides higher strength per unit volume, allowing the coupling interface to be more compact while still achieving the required engagement strength.

Inventive Principle:

Principle #40Composite materials

4Reliability

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

Engineering Contradiction:

Improvecoupling durabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The rotor uses a composite structure with a polymeric frame and metallic coupler. The polymeric frame is more cost-effective to manufacture, while the metallic coupler is strategically used only where durability is critical, thus achieving high reliability at lower overall cost compared to full steel construction.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention applies metallic material locally only at the coupler region where durability is most critical, rather than using it throughout the entire rotor. This localized application achieves the required durability while significantly reducing material costs compared to full steel rotors.

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

The design achieves a rotor with low cost, short axial length, and lightweight, strong coupling, demonstrated by withstanding torque without damage and reducing stress on the plastic hub by 85% compared to alternative designs.

Implementation Method 1

The outer teeth engage the hub such that torque is transmitted from the coupler to the frame

Methodology Applied

Scientific EffectTorque transmission: Torque

Implementation Method 2

an inner axial surface configured to interface with a shaft to be driven by the rotor

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS9391487B2Direct drive rotor with metal coupler

Publication Date: 2016.07.12 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.