Ceramic Electrical Feedthrough for Catalytic Converter Thermal Isolation
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Solution Overview
Problem
Existing electrically heatable catalytic converters face issues with high thermal loads causing damage to insulation and connections, and magnesium oxide insulation being hydrophilic, leading to reduced durability and inadequate flashover prevention.
Innovation Solution
A conical design for the inner conductor and outer tube with a non-metallic oxidic insulation layer, preferably ceramic, and a ceramic adhesive, along with a surface sealer to enhance friction and prevent water wetting, and multiple layers with controlled thermal expansion coefficients to manage thermal stresses and prevent flashovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an integrally bonded connection between the current-conducting pin and the components in the interior of the catalytic converter is used, then electrical contact is achieved, but high thermal load occurs in the outer region of the current feedthrough
Solution Approach 1:
A ceramic insulation piece is introduced as an intermediary component between the current-conducting pin and the heating conductor. This ceramic piece serves as a thermal barrier while maintaining electrical contact, reducing thermal load on the outer region of the feedthrough while preserving the electrical connection functionality
2Reliability
If magnesium oxide is used as insulation material, then electrical insulation is provided, but the insulation layer is washed out due to high hydrophilicity
Solution Approach 1:
The insulation material is changed from hydrophilic magnesium oxide to hydrophobic ceramic materials such as aluminum oxide or silicon oxide. This parameter change in material composition eliminates the washing out problem while maintaining electrical insulation properties, thereby improving durability
3Device complexity
If the insulation layer is contained within the outer tube, then compact structure is achieved, but flashovers cannot be adequately prevented
Solution Approach 1:
The insulation layer is extended axially beyond the outer tube to create an overhanging insulation structure. This dimensional extension in the axial direction provides additional flashover protection by creating a longer electrical path, while the insulation layer remains contained within the overall feedthrough structure
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 provides a durable and robust electrical feedthrough that prevents flashovers and maintains insulation integrity under high thermal and mechanical loads, ensuring reliable operation with improved stability and reduced risk of damage.
Implementation Method 1
an electrical insulation layer, which surrounds the electrically conductive inner conductor on its radial outer face
Implementation Method 2
A conical design for the inner conductor and outer tube with a non-metallic oxidic insulation layer, preferably ceramic, and a ceramic adhesive, along with a surface sealer to enhance friction
Implementation Method 3
a surface sealer to enhance friction and prevent water wetting
Implementation Method 4
multiple layers with controlled thermal expansion coefficients to manage thermal stresses
Data Source
AI summary
A current feedthrough for an electrically heatable catalytic converter, which has inside it at least one electrical conductor that can be electrically contacted by the current feedthrough, a central electrically conductive inner conductor, which is guided from the interior of the catalytic converter through the outer housing wall thereof, an electrical insulation layer, which surrounds the electrically conductive inner conductor on the radially outer surface thereof, and a metallic outer tube, in which the electrically conductive inner conductor and the electrical insulation layer are accommodated.