Gas-Tight Electrical Feedthrough for Exhaust Sensors
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Solution Overview
Problem
Existing sensors in exhaust systems face challenges with maintaining gas-tight electrical feedthroughs under extreme temperature fluctuations and high voltages, which can lead to loss of tightness and damage, especially in environments with temperatures ranging from -30°C to over 1000°C.
Innovation Solution
A ceramic molded body with a through-hole filled with metallic paste, sintered to create a strong and long-lasting connection, combined with metal pipe attachments at the ends for enhanced durability and gas-tightness, utilizing high-temperature sintering processes and materials like tungsten or platinum paste for conductivity and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrical feedthroughs are used in exhaust sensors, then the sensor can operate in exhaust systems, but the feedthroughs lose gas-tightness and get damaged under extreme temperature fluctuations from -30°C to over 1000°C
Solution Approach 1:
The patent employs a composite structure consisting of a ceramic molded body (providing thermal stability and mechanical strength) combined with metallic paste (providing electrical conductivity). This composite approach allows the feedthrough to simultaneously withstand extreme temperature fluctuations while maintaining gas-tightness and electrical functionality, resolving the contradiction between reliability under thermal stress and operational temperature range.
Solution Approach 2:
The patent utilizes a sintering process that transforms the metallic paste into a sintered metal structure with enhanced properties. By changing the physical and chemical parameters of the material through controlled sintering at high temperatures, the feedthrough achieves permanent gas-tightness and improved thermal stability, enabling it to maintain reliability across the extreme temperature range from -30°C to over 1000°C.
2Reliability
If high voltages of around 1000 V are applied to sensors in the exhaust system, then the sensor can function properly, but the bushings experience additional demands and may fail
Solution Approach 1:
The combination of ceramic material (with high electrical insulation properties) and sintered metal (with high electrical conductivity and mechanical strength) creates a composite feedthrough that can handle high voltages of around 1000 V. The ceramic provides electrical isolation and structural integrity, while the sintered metal provides conductive pathways, together enabling the feedthrough to withstand high electrical stress without failure.
3Reliability
If a sintering process is used to connect metallic paste to ceramic body, then a permanently gas-tight connection with strong bonding is achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines multiple functions into a single integrated sintering process step. The metallic paste is applied to the ceramic molded body, and both are sintered together in one thermal cycle, creating a permanent gas-tight connection between the electrical components and the ceramic housing. This merging of application and bonding operations into a single process step achieves high reliability while managing manufacturing complexity.
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 permanently gas-tight and high-quality electrical feedthrough that withstands severe temperature changes and high voltages, ensuring reliable operation in exhaust systems with temperatures above 400°C and frequent thermal cycling.
Implementation Method 1
the ceramic molded body with the metallic paste is connected in a sintering process
Data Source
Figure 1~2
AI summary
Sensor, preferably in the form of an electrostatic particle sensor, comprising a housing, in which a sensor element is arranged, and an gas-tight electrical bushing through the housing, which bushing is designed to conduct electric currents and/or voltages from electrical components which are arranged outside the housing into the housing and/or to discharge said electric currents and/or voltages from the housing. In order to provide a sensor which permanently has at least one gas-tight electrical bushing through its housing, the electrical bushing has a shaped ceramic body which has at least one passage bore which has a first end and a second end, wherein the passage bore is filled with a metallic paste from the first end to the second end, and the shaped ceramic body is connected to the metallic paste by a sintering process, and at least one tubular metallic piece is attached to the sintered metallic paste in the region of the first end and/or of the second end of the passage bore.