Ceramic-Filled Electrical Feedthrough for Moisture-Stable Insulation
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Solution Overview
Problem
Existing electrical feedthroughs for exhaust gas systems in internal combustion engines face issues with insufficient electrical insulation under higher voltages and exposure to moist, salt-containing environments, leading to electrolytic bridges and structural damage due to porous ceramic layers' saturation and differing thermal expansion coefficients.
Innovation Solution
A porous ceramic layer is filled with nanoparticles as a pore filler to prevent saturation and enhance thermal stability, ensuring consistent thermal expansion and improved durability by matching the coefficients of thermal expansion between the ceramic and conductor materials, and using a plasma-sprayed ceramic layer thermally stable up to 1200 degrees Celsius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous ceramic layer is used for electrical insulation, then electrical insulation is provided, but the ceramic layer becomes saturated with salty solution leading to electrolytic bridges and loss of insulation
Solution Approach 1:
The patent uses a porous ceramic layer as the insulator, which provides electrical insulation while maintaining a porous structure. The pores are subsequently filled with a pore filler material to prevent saturation with salty solution, thus maintaining the insulation properties over time.
Solution Approach 2:
The patent creates a composite structure by combining the porous ceramic layer with a pore filler material. This composite approach allows the ceramic to provide insulation while the pore filler prevents harmful saturation, resolving the contradiction between providing insulation and preventing saturation.
2Object-affected harmful factors
If organic sealants are used to reduce porosity, then porosity is reduced, but they are not durable enough under the stresses that occur
Solution Approach 1:
The patent changes the material parameter by using inorganic pore filler materials instead of organic sealants. This parameter change provides both porosity reduction and the required durability under thermal and mechanical stresses, as inorganic materials have better thermal stability and mechanical strength.
3Object-affected harmful factors
If inorganic sealants are used to reduce porosity, then porosity is reduced, but they lead to cracking under thermal stresses due to different coefficients of thermal expansion
Solution Approach 1:
The patent applies the homogeneity principle by selecting pore filler materials with thermal expansion coefficients that match or are compatible with both the ceramic layer and the metal components. This homogeneity in thermal expansion properties prevents cracking under thermal stresses while maintaining porosity reduction.
4Device complexity
If the porous ceramic layer is used without pore filler, then the structure is simple, but electrical insulation fails under higher voltages in moist environments
Solution Approach 1:
The patent applies preliminary action by pre-filling the pores of the ceramic layer with an appropriate filler material before the feedthrough is put into service. This preliminary filling prevents future saturation with salty solutions and maintains electrical insulation reliability under high voltage conditions, avoiding the need for complex sealing mechanisms.
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 reliable electrical insulation and increased durability by preventing conduction bridges and structural damage, maintaining effective insulation and structural integrity under varying thermal stresses and environments.
Implementation Method 1
The porous ceramic layer used has a tendency to become saturated with salty solution from the environment of the feedthrough. This gives rise to an electrolytic bridge through the ceramic layer
Implementation Method 2
Alternative sealants of the inorganic type regularly lead to cracking under thermal stresses because of different coefficients of thermal expansion
Data Source
AI summary
A feedthrough for an electrical conductor for electrical connection of an electrically heatable heating disk, especially in an exhaust gas system of an internal combustion engine, through a housing, where the feedthrough has an internal conductor, an outer sleeve, and at least one insulator, where the insulator is disposed between the internal conductor and the outer sleeve such that the internal conductor is electrically insulated from the outer sleeve. The insulator is formed by a porous ceramic layer, where pores in the ceramic layer are at least partly filled by a pore filler.