Temperature Sensor Glass Sealing Sagging Part Design
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Solution Overview
Problem
Conventional temperature sensors used in hydrogen tanks face issues with thermal shock and pressure due to a weak thin glass layer formed between the sealing glass and lead wires, which can lead to damage and breakage, especially under increased filling pressures and thermal changes.
Innovation Solution
A temperature sensor design featuring a glass sealing body with a sagging part in the insertion holes, where the length of the sagging part is limited to 1.5 mm or less, and a convex curved surface to distribute pressure effectively, combined with a lead-free borosilicate glass and platinum alloy electrodes, to enhance strength and resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing glass is provided to cover the thermo-sensitive element, then the temperature sensor is protected from high pressure, but a thin glass layer is formed in the gap between the insertion hole and lead wire which is weaker and more prone to breakage from thermal shock and pressure
Solution Approach 1:
The invention extracts and removes the harmful thin glass layer formed in the gap between the insertion hole and lead wire during the sealing process. By eliminating this weak layer, the overall strength and reliability of the sealing structure is improved without compromising the protective function of the main sealing glass body.
Solution Approach 2:
The invention applies different quality requirements to different regions of the sealing glass. The main sealing body maintains sufficient thickness for protection, while the problematic thin glass layer in the insertion hole gap is specifically targeted for removal. This localized quality control ensures strength where needed while eliminating weaknesses.
2Productivity
If the filling time of hydrogen tank is shortened, then productivity is improved, but thermal shock and pressure during filling increase causing higher risk of glass breakage
Solution Approach 1:
The invention prepares the sealing structure in advance by removing the weak thin glass layer before the hydrogen filling process occurs. This preliminary action ensures that when rapid filling and associated thermal shock occur, the sealing structure is already optimized to withstand these conditions without breaking.
3Ease of manufacture
If the thin glass layer is present to fill the gap, then manufacturing is simplified, but the sealing glass may break due to breakage of the thin glass layer under thermal shock and pressure
Solution Approach 1:
The invention converts the harmful effect of the thin glass layer formation into a beneficial manufacturing indicator. The presence of the thin glass layer during sealing identifies the gap location, and subsequent removal of this layer (through controlled breaking and cleaning) ensures complete gap elimination. This transforms a manufacturing byproduct into a quality assurance mechanism.
Data Source
AI summary
A temperature sensor includes a thermo-sensitive element, a pair of element electrode wires electrically connected to the thermo-sensitive element, a glass sealing body that covers the thermo-sensitive element and part of the pair of the element electrode wires, and a tablet formed with a pair of insertion holes extending in an axial direction thereof, through which the pair of the element electrode wires pass respectively. The glass sealing body includes a sealing part formed so as to extend from an element side end surface thereof located on a side of the thermo-sensitive element toward the thermo-sensitive element, and a sagging part formed in each of the pair of the insertion holes so as to extend integrally from the sealing part. The length of the sagging part in the axial direction being smaller than or equal to 1.5 mm.