Epoxy-Encapsulated Coil for Thermal Expansion Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrical machine coils, particularly in synchronous machines, face issues with adhesion and reliability due to thermal expansion differences and high operating forces, leading to potential detachment and damage, while existing solutions like additional thermally conductive layers increase production costs.
Innovation Solution
A coil with a winding partially or fully encapsulated in an epoxy resin with a specific compressive-to-tensile strength ratio, high modulus of elasticity, and a glass transition temperature, ensuring excellent strength, flexibility, and thermal expansion matching that of copper or steel, reducing operational tensions and maintaining reliability at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a potting compound is used to embed coils, then the strength and stability of the assembly is improved, but the adhesion deteriorates due to thermal expansion differences and high operating temperatures
Solution Approach 1:
The patent modifies the chemical composition and physical parameters of the potting compound to achieve optimal adhesion. By adjusting the resin system, hardener type, and additive package, the compound's thermal expansion coefficient is matched to the coil materials, and its curing characteristics are optimized to ensure strong bonding under high temperature and mechanical stress conditions.
Solution Approach 2:
The invention uses a composite potting compound formulation that combines multiple materials with complementary properties. This includes resin matrices, fillers, coupling agents, and other additives that work together to provide both mechanical strength and reliable adhesion to the coil windings and supporting structures throughout the operational lifetime.
2Reliability
If a flexible thermally conductive layer is added between the cast resin body and supporting body, then the adhesion of the cast resin body is improved, but the manufacturing complexity and costs increase
Solution Approach 1:
The patent merges the functions of adhesion promotion and thermal conduction into the potting compound itself, eliminating the need for a separate intermediate layer. The compound is formulated with thermally conductive fillers and adhesion-promoting chemicals integrated into a single homogeneous material that performs both functions simultaneously.
Solution Approach 2:
The potting compound is designed as a multi-functional material that simultaneously provides structural support, thermal management, electrical insulation, vibration damping, and adhesion. This universal approach replaces multiple specialized components with a single integrated solution, simplifying the manufacturing process and reducing costs.
3Strength
If the compressive strength of the epoxy resin is increased significantly, then the strength under high forces is improved, but the flexibility deteriorates
Solution Approach 1:
The patent optimizes the epoxy resin's mechanical parameters by carefully selecting the resin-to-hardener ratio, choosing appropriate catalysts, and controlling the curing schedule. This produces a resin system with balanced properties where the compressive strength is enhanced for withstanding high forces while the elastic modulus remains within a range that provides necessary flexibility for thermal expansion and mechanical stress accommodation.
Solution Approach 2:
The invention creates a composite epoxy resin system that combines rigid and flexible components. This includes using modified resin systems, incorporating flexible additives or plasticizers in controlled amounts, and selecting hardeners that provide both strength and flexibility. The resulting composite material achieves the desired balance between compressive strength and flexibility.
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 epoxy resin encapsulation provides enhanced strength, flexibility, and thermal conductivity, ensuring reliable operation at high speeds and loads with reduced manufacturing costs by maintaining structural integrity and thermal balance.
Implementation Method 1
The adhesion of the potting compound is often problematic. Due to the different thermal expansion coefficients of the various materials, the high operating temperatures, and the high forces acting on them
Implementation Method 2
Due to the different thermal expansion coefficients of the various materials, the high operating temperatures, and the high forces acting on them
Implementation Method 3
WO 2007/036505 A1 discloses a rotating electrical machine with a stator provided with windings, wherein a winding head of the stator is surrounded by a cast resin body... which layer is intended to improve the adhesion of the cast resin body
Data Source
AI summary
Disclosed is a coil comprising a winding that is coated with an epoxy resin in at least some areas, wherein a ratio of a compressive strength of the epoxy resin to the tensile strength thereof at room temperature ranges between 2 and 5, the modulus of elasticity at room temperature is at least 5000 MPa, and at a glass transition temperature of the epoxy resin, the modulus of elasticity and the tensile strength have values amounting to at least 30% of the values at room temperature.