External Rotor Motor End Cover with Arc-Shaped Protruding Bars

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Solution Overview

Problem

Conventional motors face challenges in achieving precise fitting between the end cover and stator core due to limited die-casting precision, leading to increased production costs and aluminum scraps entering the motor coil and stator air gap, affecting product quality.

Innovation Solution

An end cover design for external rotor motors featuring a cylindrical connecting portion with arc-shaped protruding bars and a groove system that ensures precise fitting with the stator core, eliminates the need for further processing, and incorporates a slot to capture aluminum scraps, preventing them from entering the motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional die-casting method is used for end cover, then production cost increases due to further processing requirements, but manufacturing simplicity is improved

Engineering Contradiction:

Improveease of manufactureVSAvoidfitting precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The end cover incorporates pre-formed protruding bars with arc-shaped top surfaces and grooves between them during the die-casting process. These features are created in advance to match the stator core's inner wall geometry, eliminating the need for subsequent machining or processing to achieve precise fitting.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If conventional die-casting method is used for end cover, then further processing is required to achieve precise fitting, but production cost is reduced

Engineering Contradiction:

Improvefitting precisionVSAvoidproduction cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If conventional fitting process is used, then aluminum scraps are generated and enter motor coil and stator air gap, but fitting precision is limited

Engineering Contradiction:

Improvefitting precisionVSAvoidaluminum scraps contamination

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The grooves formed between adjacent protruding bars during die-casting serve a dual function: they accommodate aluminum scraps that may be generated during the fitting process, and they facilitate the fitting process itself. The grooves act as receptacles that trap aluminum scraps, preventing them from entering the motor coil and stator air gap, while also providing tolerance for fitting variations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS8049381B2End cover and external rotor motor using the same

Publication Date: 2011.11.01 ZHONGSHAN BROAD OCEAN

AI summary

An end cover for an external rotor motor. The external rotor motor has a stator core having a center hole, and the end cover including a body, a cylindrical connecting portion, and multiple protruding bars each having an arc-shaped top surface. The cylindrical connecting portion is extended from the center of the body and received in the center hole of the stator core, the protruding bars are disposed on outer surface of the cylindrical connecting portion and extended in an axial direction, and the arc-shaped top surface of the protruding bar is fit with inner wall of the center hole of the stator core. The end cover is accurately fit with a stator core, requires no further processing after die-casting and thus reducing production cost, and is capable of preventing aluminum scraps from entering a stator.