Rotating Electric Machine Resin Encapsulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rotating electric machines face reliability issues due to thermal stress-induced cracking and peeling at joints and interfaces caused by differences in the coefficient of linear expansion between electrical conductors, insulating coats, and encapsulating resin bodies.
Innovation Solution
The solution involves creating a dual-part encapsulating resin body with a lower coefficient of linear expansion for the first part encapsulating exposed conductor portions and joints, and a second part with a higher filler content for encapsulating covered conductor portions, minimizing thermal stress and peeling by unevenly distributing the filler within the resin body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform encapsulating resin body is used, then the manufacturing process is simple, but thermal stress-induced cracking and peeling occur at joints and interfaces
Solution Approach 1:
The encapsulating resin body is divided into a first region and a second region with different filler contents. The first region has a higher filler content to match the coefficient of linear expansion of electrical conductors, suppressing cracking at joints. The second region has a lower filler content to match the coefficient of linear expansion of insulating coats, preventing peeling at interfaces. This local differentiation of material properties resolves the contradiction between manufacturing simplicity and reliability.
2Reliability
If the filler content is increased to reduce the coefficient of linear expansion, then cracking at joints is suppressed, but peeling at insulating coat interfaces occurs
Solution Approach 1:
Different regions of the encapsulating resin body are assigned different filler contents to match different expansion characteristics. The first region with higher filler content suppresses cracking at conductor joints, while the second region with lower filler content prevents peeling at insulating coat interfaces, thereby resolving the harmful effects of both cracking and peeling simultaneously.
Solution Approach 2:
The filler content parameter is varied spatially within the encapsulating resin body. By changing the filler concentration from the first region to the second region, the coefficient of linear expansion is adjusted to match different adjacent materials, eliminating thermal stress-induced damage.
3Reliability
If different resin materials are used for the first and second parts, then thermal stress is minimized, but manufacturing complexity and cost increase
Solution Approach 1:
The same resin material is used throughout the encapsulating resin body, but the filler content is locally adjusted to create regions with different coefficients of linear expansion. This approach achieves thermal stress minimization while maintaining manufacturing simplicity and avoiding the complexity of using multiple resin materials.
Solution Approach 2:
A composite material approach is employed where filler particles are distributed within the resin matrix at varying concentrations. This creates a functionally graded material structure that optimizes thermal expansion matching with adjacent components while maintaining a unified material system for simplified manufacturing.
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
This configuration effectively suppresses cracking and peeling, ensuring high reliability and simplifying the manufacturing process by using the same resin material for both parts, thereby reducing manufacturing costs.
Implementation Method 1
A coefficient of linear expansion of the first part of the encapsulating resin body is lower than a coefficient of linear expansion of the second part of the encapsulating resin body
Implementation Method 2
curing the liquid resin, at a time point after a predetermined duration has elapsed from the immersing step, to form an encapsulating resin body
Data Source
AI summary
A rotating electric machine includes a stator core, a stator coil formed of electrical conductors and insulating coats respectively covering the electrical conductors, and an encapsulating resin body. The stator coil has a coil end part protruding from the stator core. The coil end part includes exposed portions of the electrical conductors, which are exposed from the insulating coats, joints formed at the exposed portions, and covered portions of the electrical conductors which are covered with the respective insulating coats and respectively adjoin the exposed portions. The encapsulating resin body has a first part in which the exposed portions of the electrical conductors and the joints are encapsulated, and a second part in which at least part of each of the covered portions of the electrical conductors is encapsulated. A coefficient of linear expansion of the first part is lower than a coefficient of linear expansion of the second part.