Exhaust Sensor Threaded Coupling With Lug-Seal for Welded Pipe Tightness
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Solution Overview
Problem
Existing threaded connectors for exhaust gas sensors in internal combustion engines face challenges in maintaining tightness over the service life due to uneven sealing surfaces resulting from welding into exhaust pipes, and lack robustness against corrosive infiltration.
Innovation Solution
A threaded connector design featuring a circumferential, radially inward-pointing lug within the through-bore, spaced from both ends, with a conical or flat annular surface configuration that introduces mechanical stresses evenly, providing flexibility and robustness by allowing the exhaust gas sensor to screw into an internal thread for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat sealing surface is used in the threaded connector, then manufacturing is simple, but the sealing surface cannot compensate for unevenness resulting from welding into the exhaust pipe
Solution Approach 1:
The sealing surface is designed with elastic deformation capability, allowing it to dynamically adapt to unevenness in the exhaust pipe welding surface. The material and geometry are selected so that under compression from the sensor, the sealing surface deforms elastically to conform to irregularities, ensuring reliable sealing while maintaining simple manufacturing of the base structure.
2Reliability
If a large sealing surface is provided to ensure robustness against corrosive infiltration, then protection improves, but the device becomes less flexible in compensating for surface unevenness
Solution Approach 1:
The sealing surface is designed with non-uniform local properties: the central region has higher flexibility to conform to surface unevenness, while the peripheral regions provide extended coverage for robust corrosion protection. This spatial variation in mechanical properties allows simultaneous achievement of adaptability and robustness.
3Device complexity
If the lug is positioned close to the ends of the through-bore, then the structure is simpler, but stress concentration occurs reducing the robustness of the threaded connector
Solution Approach 1:
The lug is positioned at an optimized distance from the ends of the through-bore, predetermined through stress analysis, to preemptively avoid stress concentration zones. This preliminary positioning decision, made during design rather than as a compromise, ensures uniform stress distribution and maximum robustness while maintaining structural simplicity.
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
A threaded coupling for welding into the exhaust gas line (50) of an internal combustion engine and for receiving an exhaust gas sensor (20), with a through bore (12) which has, in the axial direction, an end (121) which faces the exhaust gas and an end (122) which faces away from the exhaust gas, characterized in that a circumferential, radially inwardly pointing lug (14) for making contact with the exhaust gas sensor (20) is provided in the through bore (12), which lug (14) is spaced apart from the end (121) which faces the exhaust gas, and is spaced apart from the end (122) which faces away from the exhaust gas.