Induction Motor Stator Dual-Layer Encapsulation

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Solution Overview

Problem

Conventional induction motor stator encapsulation methods fail to prevent cracking and falling off of the insulation layer during operation, leading to premature motor breakdown due to fragments contacting the rotor.

Innovation Solution

A dual-layer encapsulation method using a first encapsulating material with a smaller shrink rate to directly cover the stator winding, followed by a second material with higher mechanical strength and thermal conductivity to form a robust and efficient insulation structure, where the first insulation layer is made of silicon and the second of epoxy resin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single encapsulating material is used to form an insulation layer around the stator winding, then the insulation function is provided, but the insulation layer cracks and falls off during operation

Engineering Contradiction:

Improveinsulation layer stabilityVSAvoidinsulation layer strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The encapsulation structure is divided into two distinct layers: a first insulation layer directly covering the stator winding and a second insulation layer covering the first layer. This segmentation allows each layer to be optimized for different functions - the first layer for thermal dissipation and the second for mechanical protection - thereby resolving the contradiction between stability and strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses two different encapsulating materials with complementary properties. The first material is selected for its thermal conductivity to dissipate heat from the stator winding, while the second material is selected for its mechanical strength to prevent cracking and falling off. This composite material approach simultaneously achieves both thermal management and structural integrity.

Inventive Principle:

Principle #40Composite materials

2Force

If the encapsulating material has high shrink rate, then it provides strong bonding force, but it causes thermal expansion stress leading to cracking

Engineering Contradiction:

Improvebonding forceVSAvoidcrack resistance

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The shrinkage stress is segmented and distributed across two layers with different shrink rates. The first layer experiences shrinkage stress directly at the winding interface, while the second layer experiences reduced stress. This segmentation prevents concentration of thermal expansion stress that would cause cracking, while still maintaining adequate bonding force through the combined effect of both layers.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the shrink rate parameter by selecting two encapsulating materials with different shrink characteristics. The first material has a shrink rate optimized for bonding to the stator winding, while the second material has a different shrink rate that compensates for thermal expansion stresses, thereby preventing cracking while maintaining bonding strength.

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If the insulation layer is thin, then the motor size is reduced, but the thermal dissipation effect is insufficient

Engineering Contradiction:

Improvemotor sizeVSAvoidthermal dissipation

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The patent applies local quality by making the first insulation layer (in direct contact with the stator winding) have higher thermal conductivity than the second layer. This localized optimization of material properties ensures that heat is efficiently conducted away from the winding at the critical interface, while the overall encapsulation thickness remains controlled to maintain compact motor size.

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 method enhances the mechanical strength and thermal dissipation of the encapsulation, preventing damage to the stator winding and extending the motor's lifespan by reducing strain and improving thermal conductivity.

Implementation Method 1

a shrink rate of the first encapsulating material is smaller than a shrink rate of the second encapsulating material

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 2

the second of epoxy resin... improving thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10483820B2Method of encapsulating induction motor stator

Publication Date: 2019.11.19 XPT NANJING E POWERTRAIN TECH CO LTD

AI summary

An induction motor stator encapsulate method, including arranging a stator of an induction motor in a case of the induction motor, wherein the stator comprises a stator core and a stator winding surrounding the stator core; filling a first encapsulating material into the case for forming a first insulation layer, wherein the first insulation layer directly covers the stator winding; and filling a second encapsulating material into the case for forming a second insulation layer, wherein the second insulation layer covers the first insulation layer; wherein a shrink rate of the first encapsulating material is smaller than a shrink rate of the second encapsulating material.