Pressure Sensor Dielectric Pathway for Reliable Glass-to-Metal Sealing
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Solution Overview
Problem
Existing pressure sensors face challenges in providing a reliable glass-to-metal seal that ensures electrical insulation and thermal compatibility, particularly in lead-free configurations, which can lead to thermal mismatch issues and cracking.
Innovation Solution
A method is introduced to form an open pathway through a glass-to-metal seal by using an elongate rod, such as a graphite rod, to create a dielectric passageway within the sensor, which is then filled with a dielectric material and sealed with a deflectable diaphragm, ensuring electrical insulation and thermal compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass to metal seal is used in pressure sensors, then electrical insulation and thermal compatibility are achieved, but thermal mismatch issues and cracking occur
Solution Approach 1:
A dielectric material is introduced as an intermediary substance between the metal tube and glass seal. This dielectric material serves as a thermal and electrical intermediary, allowing the metal tube to be positioned within the glass seal while preventing direct thermal contact that causes mismatch and cracking. The dielectric material compensates for thermal expansion differences between metal and glass.
Solution Approach 2:
The dielectric material is pre-positioned in the sensor cavity before the metal tube is inserted and sealed with glass. This preliminary placement ensures that the thermal mismatch issue is addressed from the beginning, preventing cracking during subsequent heating and sealing operations. The dielectric material is already in place to accommodate the metal tube without direct contact.
2Reliability
If a seal is provided between the metal tube and dielectric material, then electrical insulation is ensured, but manufacturing complexity increases
Solution Approach 1:
The sealing function and electrical insulation function are merged into a single dielectric material component. The dielectric material simultaneously provides the seal between the metal tube and glass, and ensures electrical insulation between the metal tube and sensor cavity. This eliminates the need for separate sealing and insulation components, simplifying manufacturing.
Solution Approach 2:
The dielectric material is used as a homogeneous substance that fills the sensor cavity and provides uniform electrical insulation and sealing properties throughout. This homogeneous approach simplifies manufacturing compared to using multiple different materials with specialized functions, as the dielectric material performs all required functions simultaneously.
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 robust and reliable glass-to-metal seal that maintains electrical insulation and thermal stability, preventing cracking and ensuring accurate capacitance measurements in pressure sensors.
Implementation Method 1
A seal must be provided between the metal tube and the dielectric material
Implementation Method 2
The sensor cavity is sealed with a deflectable diaphragm which is configured to deflect in response to applied pressure from the process fluid
Implementation Method 3
Existing pressure sensors face challenges in providing a reliable glass-to-metal seal that ensures electrical insulation and thermal compatibility
Data Source
AI summary
A method of manufacturing a pressure sensor for sensing a pressure of a process fluid includes obtaining a sensor body having a sensor cavity formed therein. A metal tube is placed through an opening in the sensor body into the sensor cavity. A rod is placed through the metal tube and into the sensor cavity. The sensor cavity is at least partially filled with a dielectric material and the dielectric material completely covers the metal tube carried in the sensor cavity and a portion of the rod. The rod is removed and thereby forming a dielectric passageway which is fluidically coupled to the metal tube. The sensor cavity is sealed with a deflectable diaphragm which is configured to deflect in response to applied pressure from the process fluid. A differential pressure sensor for sensing a differential pressure of a process fluid includes a sensor body having a sensor cavity formed therein is also provided.