Electromagnetic Coil Ceramic Thermal Spray Insulation
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Solution Overview
Problem
Existing electromagnetic coils suffer from inadequate heat radiation from axial end surfaces due to insufficient contact between cooling plates and high-thermal-conduction insulating members, leading to reduced efficiency in heat transfer.
Innovation Solution
A ceramic layer is formed through thermal spraying on the axial end surfaces of the conductor winding, embedding irregularities and providing a flattened surface for improved heat transfer, while also enhancing electrical insulation and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling plates are covered with high-thermal-conduction insulating members (ceramic layers), then electrical insulation is improved, but heat transfer contact becomes insufficient due to surface irregularities
Solution Approach 1:
The ceramic layer is formed on the conductor winding surface before the cooling plate is installed. This preliminary formation of the ceramic coating allows the surface irregularities to be created in advance, which then serve to improve thermal contact when the cooling plate is pressed against the winding, while simultaneously providing electrical insulation.
Solution Approach 2:
The thermal spray process changes the physical parameters of the ceramic layer by controlling spray conditions (gas pressure, temperature, distance) to create a layer with specific surface roughness characteristics. This parameter control allows the ceramic layer to simultaneously provide electrical insulation and improve thermal contact through controlled surface irregularities.
2Reliability
If the ceramic layer is made thicker to improve electrical insulation, then insulation performance is improved, but heat transfer efficiency deteriorates
Solution Approach 1:
The ceramic layer is applied with varying local properties: the inner surface in contact with the conductor winding has a rough texture for thermal contact, while the outer surface has a smoother finish for contact with the cooling plate. The thickness is controlled to be sufficient for insulation (3-5 times the conductor diameter) while maintaining high thermal conductivity material selection to minimize thermal resistance.
Solution Approach 2:
The ceramic layer is formed as a composite structure with different surface characteristics on its inner and outer surfaces. The material composition and microstructure are optimized to provide both electrical insulation properties and thermal conduction properties, creating a functional gradient within the ceramic layer itself.
3Reliability
If thermal spray conditions are intensified to form a denser ceramic layer, then electrical insulation is improved, but surface irregularities increase reducing heat transfer
Solution Approach 1:
The ceramic layer formation process is segmented into distinct stages: initial coating deposition, intermediate consolidation, and final surface finishing. This segmentation allows different regions of the ceramic layer to have different properties - the inner portion provides thermal contact through controlled irregularities, while the outer portion provides smooth electrical insulation contact with the cooling plate.
Solution Approach 2:
The thermal spray process is applied with controlled excess material deposition, followed by selective removal or consolidation. This partial action approach ensures that enough ceramic material is deposited to provide complete electrical insulation, while the surface is then processed to remove excessive roughness that would impede thermal contact with the cooling plate.
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 ceramic layer effectively enhances heat radiation from the electromagnetic coil by improving contact with cooling members, maintaining electrical insulation, and reinforcing the coil's structural integrity.
Implementation Method 1
a ceramic layer formed through thermal spraying on an end surface, with respect to a direction of the predetermined axis, of the conductor winding
Implementation Method 2
heat can be efficiently transferred from the axial end surface to the ceramic layer. Furthermore, the surface of the ceramic layer is flattened. Thus, by means of the cooling plate, for example, being brought into contact with the flattened surface of the ceramic layer, heat can be efficiently transferred from the ceramic layer to the cooling plate
Data Source
AI summary
An electromagnetic coil includes a conductor winding 12a formed by winding a conductor 12b a plurality of times about a predetermined axis, and a ceramic layer 12c formed through thermal spraying on an axial end surface of the conductor winding 12a, and having a flattened surface. A maximal value t12 of thickness of the ceramic layer 12c is set to three times or less a maximal value t11 of depth of the recesses formed at the surface of turns of the conductor 12b at the axial end surface.