Glass-Ceramic Feedthrough Bushing for Exhaust Heat and Vibration
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Solution Overview
Problem
Feedthroughs in exhaust gas systems of internal combustion engines face challenges due to high temperature gradients, mechanical loading, and corrosive environments, leading to potential damage and reduced operational integrity during mounting and operation.
Innovation Solution
A feedthrough design featuring an inner conductor, an outer conductor with a sleeve for mounting, and an electrically insulating component, typically glass or glass ceramic, which allows for reliable fastening and damping of vibrations, while minimizing thermal and mechanical stresses through suitable material selection and welding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If elastomer material is used to surround the conductor to increase creepage distance, then the creepage distance is improved, but the thermal stability and operational integrity deteriorate due to high temperatures up to 900°C
Solution Approach 1:
The patent changes the material parameter from elastomer to glass-ceramic, which has superior thermal stability at high temperatures up to 900°C while maintaining the required creepage distance for electrical insulation. This parameter change resolves the contradiction by selecting a material that satisfies both the electrical insulation requirement and the thermal stability requirement simultaneously.
Solution Approach 2:
The patent employs glass-ceramic as a composite material that combines the properties of glass (electrical insulation, creepage distance) with ceramic (thermal stability, mechanical strength). This composite material approach allows the feedthrough to withstand both the electrical insulation requirements and the extreme thermal conditions in exhaust gas systems.
2Strength
If the feedthrough is rigidly fastened to the housing component, then the mechanical retention is improved, but the thermal stress and mechanical damage increase due to thermal expansion differences
Solution Approach 1:
The patent applies local quality by creating a differentiated fastening system: the glass-ceramic insulator is rigidly retained to maintain electrical insulation and mechanical position, while the outer conductor is allowed controlled movement relative to the housing. This local differentiation resolves the contradiction by providing rigid retention where needed (insulator position) while accommodating thermal expansion where needed (outer conductor movement).
Solution Approach 2:
The patent introduces dynamics by allowing the outer conductor to move dynamically with thermal expansion while maintaining its electrical connection function. The system transitions from a completely rigid structure to one with controlled flexibility, enabling the outer conductor to expand and contract with temperature changes without generating excessive stress, while the insulator remains statically retained.
3Reliability
If the outer conductor is directly welded to the housing component, then the fastening reliability is improved, but the preliminary damage and operational integrity deteriorate due to high welding temperatures
Solution Approach 1:
The patent introduces the glass-ceramic insulator as an intermediary component between the outer conductor and the housing component. This intermediary serves multiple functions: it provides electrical insulation, mechanical retention, and thermal buffering during welding. The insulator protects the sensitive inner conductor assembly from direct exposure to high welding temperatures while still enabling reliable fastening of the feedthrough to the housing.
Solution Approach 2:
The patent segments the fastening function from the electrical connection function by using separate components: the glass-ceramic insulator handles the mechanical retention and thermal protection, while the outer conductor handles the electrical connection. This segmentation allows the welding process to be applied to the outer conductor and housing without directly affecting the sensitive inner conductor, reducing preliminary damage while maintaining fastening reliability.
4Power
If high current intensities are conducted through the feedthrough for catalytic converter heating, then the heating output is improved, but the thermal loading and mechanical stress on the feedthrough increase
Solution Approach 1:
The patent uses glass-ceramic as a composite material that can withstand the high thermal loading generated by high current intensities for catalytic converter heating. The ceramic component provides thermal stability and resistance to thermal shock, while the glass component provides electrical insulation. This composite structure enables the feedthrough to handle the extreme thermal conditions resulting from high power heating operations without deteriorating.
Solution Approach 2:
The patent changes the material parameters of the insulator from elastomer (low temperature tolerance) to glass-ceramic (high temperature tolerance), enabling the feedthrough to withstand the thermal loading generated by high current intensities. This parameter change allows the system to achieve high heating outputs (1-8 kW) while maintaining the structural integrity of the feedthrough under extreme thermal conditions.
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 design enhances the operational integrity and reliability of feedthroughs by reducing thermal and mechanical stresses during mounting and operation, ensuring a hermetically sealed connection and improved resistance to vibrations and thermal expansion differences.
Implementation Method 1
an electrically insulating component between the outer conductor and the inner conductor, the electrically insulating component retaining the inner conductor relative to the outer conductor in an electrically insulated fashion
Implementation Method 2
an electrically insulating component, typically glass or glass ceramic, which allows for reliable fastening and damping of vibrations
Implementation Method 3
minimizing thermal and mechanical stresses through suitable material selection and welding processes
Implementation Method 4
ensuring a hermetically sealed connection and improved resistance to vibrations and thermal expansion differences
Implementation Method 5
improved resistance to vibrations and thermal expansion differences
Data Source
AI summary
A feedthrough in a housing component that is subject to thermal loading for a functional assembly includes: an inner conductor; an outer conductor having a sleeve assigned to or formed on the outer conductor that retains or makes it possible to fasten the feedthrough to the housing component; and an electrically insulating component between the outer conductor and the inner conductor, the electrically insulating component retaining the inner conductor relative to the outer conductor in an electrically insulated fashion.