Cyanate Ester Bonding Composition for Electrical Machine Windings
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Solution Overview
Problem
Conventional varnish compositions used for bonding windings or core laminates in electrical machines have poor thermal stability and are prone to cracking due to their low glass transition temperature and brittleness, especially under operating conditions and vibrations.
Innovation Solution
A curable composition comprising 10-25 weight percent polyfunctional cyanate ester, 35-65 weight percent first difunctional cyanate ester, and 15-40 weight percent second difunctional cyanate ester, which is applied and cured using a vacuum and heat process to provide improved thermal stability and crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional varnish compositions are used for bonding windings or core laminates, then the bonding process is simple, but the composition exhibits poor thermal stability and brittleness leading to thermal degradation and cracking
Solution Approach 1:
The patent employs a composite resin system combining cyanate ester base resin with reactive diluents and crosslinking agents. This composite approach achieves superior thermal stability (glass transition temperature above 300°C) and crack resistance while maintaining bonding functionality, directly resolving the contradiction between reliability and performance under thermal stress.
Solution Approach 2:
The invention modifies the chemical composition parameters by incorporating specific ratios of cyanate ester base resin (5-20 wt%), reactive diluents (10-30 wt%), and crosslinking agents (5-20 wt%). These parameter changes transform the material properties to achieve high thermal stability and flexibility, overcoming the limitations of conventional varnishes.
2Stability of the object's composition
If conventional varnish compositions with low glass transition temperature are used, then the composition remains flexible at room temperature, but it becomes brittle and cracks under vibration and thermal cycling
Solution Approach 1:
The patent raises the glass transition temperature to above 300°C through the use of cyanate ester base resin and crosslinking agents, while simultaneously incorporating flexible reactive diluents. This dual approach maintains crack resistance and flexibility despite the high glass transition temperature, resolving the contradiction between thermal stability and mechanical strength.
Solution Approach 2:
The composite resin system combines rigid cyanate ester structures for thermal stability with flexible reactive diluent molecules for crack resistance. This material composition achieves both high glass transition temperature and improved flexibility, directly addressing the contradiction between stability and strength.
3Reliability
If a curable composition with high crosslinking density is used to improve thermal stability, then the glass transition temperature increases, but the viscosity increases making impregnation difficult
Solution Approach 1:
The patent carefully controls the ratio of crosslinking agents (5-20 wt%) to base resin (5-20 wt%) and incorporates reactive diluents (10-30 wt%) to modulate viscosity. This parameter optimization ensures the composition remains sufficiently fluid for impregnation while achieving high crosslinking density and thermal stability after curing.
Solution Approach 2:
Reactive diluents serve as intermediaries that reduce the viscosity of the curable composition during application, facilitating easy impregnation. After curing, these diluents become part of the crosslinked network, maintaining thermal stability. This intermediary approach resolves the contradiction between processability and final performance.
4Duration of action of stationary object
If conventional varnish compositions are used, then the application process is simple, but the composition degrades thermally after short operating times
Solution Approach 1:
The patent utilizes cyanate ester base resin with inherent high thermal stability and incorporates crosslinking agents to create a thermally stable network structure. This compositional change enables the varnish to withstand prolonged thermal exposure without degradation, extending the operational lifetime of electrical machines.
Solution Approach 2:
The composite resin system combines thermally stable cyanate ester structures with crosslinking agents to form a heat-resistant network. This material composition resists thermal degradation during extended operation, directly addressing the contradiction between operating duration and thermal stability.
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 solution achieves a glass transition temperature greater than 300°C, enhanced thermal stability, and reduced crack formation during thermal cycling, ensuring reliable performance under operational conditions.
Implementation Method 1
a curable composition for bonding windings or core laminates in an electrical machine includes: (A) about 10 weight percent to about 25 weight percent of a polyfunctional cyanate ester... (B) about 35 weight percent to about 65 weight percent of a first difunctional cyanate ester... (C) about 15 weight percent to about 40 weight percent of a second difunctional cyanate ester... heating the winding or the core laminate to cure the curable composition
Implementation Method 2
The method includes impregnating the winding or the core laminate with a curable composition... applying a vacuum to the winding or the core laminate
Implementation Method 3
heating the winding or the core laminate to cure the curable composition... achieves thermal stability with a glass transition temperature greater than 300°C
Data Source
AI summary
A curable composition for bonding windings or core laminates in an electrical machine is presented. The curable composition includes: (A) about 10 weight percent to about 25 weight percent of a polyfunctional cyanate ester; (B) about 35 weight percent to about 65 weight percent of a first difunctional cyanate ester, or a prepolymer thereof; (C) about 15 weight percent to about 40 weight percent of a second difunctional cyanate ester, or a prepolymer thereof. An associated method is also presented.