Metal-Coupler Rotor Structure for Shorter Direct-Drive Washers
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Solution Overview
Problem
Direct drive clothes washing machine motor rotors face challenges with existing plastic and steel rotors, which are either heavy and costly or lightweight but less durable, leading to long axial lengths that are undesirable.
Innovation Solution
A rotor design featuring a metallic coupler with a polymeric frame, permanent magnets, and a magnetic backing ring, optimized for low cost, short axial length, and strong coupling with the drive shaft, using a metallic coupler with splined teeth and a polymeric frame with reinforcement ribs and magnet spacers to distribute torque effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel rotors are used, then strength and durability are improved, but weight and cost increase
Solution Approach 1:
The rotor assembly uses a composite structure combining a metallic coupler (steel) for strength with a polymeric frame (plastic) for lightweight construction. The metallic coupler provides the necessary coupling strength to the drive shaft, while the polymeric frame reduces overall weight compared to traditional all-steel rotors.
2Weight of moving object
If plastic rotors are used, then weight and cost are reduced, but strength and durability decrease
Solution Approach 1:
The invention uses a composite structure where a metallic coupler provides the necessary strength and durability for coupling to the drive shaft, while a polymeric frame provides lightweight construction. This allows the rotor to achieve both weight reduction and sufficient coupling strength.
Solution Approach 2:
The rotor is divided into functionally distinct segments: a metallic coupler for strength and coupling, and a polymeric frame for lightweight construction and magnet mounting. This segmentation allows each material to be optimized for its specific function.
3Strength
If plastic rotors use larger coupling area, then coupling strength is improved, but axial length increases
Solution Approach 1:
The invention changes the material parameter of the coupler from plastic to metal, which has higher strength density. This allows the metallic coupler to achieve the necessary coupling strength with a shorter axial length compared to plastic rotors that require larger coupling areas.
4Reliability
If steel rotors are used, then durability is improved, but cost increases
Solution Approach 1:
The rotor uses a composite structure with a metallic coupler for durability and a polymeric frame for cost reduction. The polymeric frame is less expensive to manufacture than steel, while the metallic coupler provides the necessary durability for coupling to the drive shaft.
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 rotor achieves a durable, lightweight, and cost-effective coupling with the drive shaft, reducing stress on the plastic hub by 85% compared to traditional designs, as demonstrated by finite element analysis and torque testing.
Implementation Method 1
a multiplicity of permanent magnets in contact with an inner axial surface of the backing ring and molded over by the polymeric frame
Data Source
AI summary
An overmolded-type rotor for an outer rotor-type electric motor, wherein, in addition to a backing ring and magnets, a metallic coupler that comprises an inner axial surface configured to interface with a shaft to be driven by the rotor and an outer axial surface that corresponds to a multiplicity of outer teeth is overmolded with a polymer frame.