Electrochemical Gas Sensor Pin Seal for Electrolyte Pressure Relief
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Solution Overview
Problem
Sealing the housing of electrochemical gas sensors with liquid electrolytes is challenging due to the aggressive nature of these materials and the need for gas permeability, leading to frequent sensor failures, particularly with O-ring seals which are prone to rolling and inadequate pressure management during electrode oxidation.
Innovation Solution
An annular seal with a radially outwardly open groove and a radially inwardly open groove, such as an X-ring seal, is used around the metal interface pin, providing a more reliable and longer-lasting seal that allows controlled egress of fluid when pressure builds up, while maintaining gas tightness and minimizing electrolyte loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an O-ring seal is used to seal the metal interface pin, then the housing is sealed to prevent electrolyte loss, but the seal is prone to rolling and failure leading to frequent sensor failures
Solution Approach 1:
The seal is divided into multiple independent contact points (first contact point and second contact point) instead of a continuous circular contact. This segmentation prevents the seal from rolling while maintaining effective sealing at each contact point with the housing and interface pin.
Solution Approach 2:
Instead of using a traditional continuous circular O-ring that contacts the housing all around, the invention inverts the approach by using a C-shaped seal that makes discrete point contacts. This inversion of the sealing mechanism eliminates the rolling problem while maintaining seal integrity.
2Loss of substance
If the housing is sealed tightly to prevent electrolyte egress, then electrolyte loss is minimized, but pressure build up from anode oxidation cannot be relieved
Solution Approach 1:
The seal has different properties at different locations: the first contact point provides tight sealing to prevent electrolyte loss, while the second contact point allows controlled pressure relief. This local differentiation of sealing quality enables simultaneous achievement of electrolyte retention and pressure management.
Solution Approach 2:
The seal design changes the sealing parameter from continuous circular contact to discrete point contact. This parameter change allows the seal to provide both tight sealing and pressure relief pathways, managing the trade-off between preventing electrolyte loss and relieving internal pressure build-up.
3Adaptability or versatility
If the seal allows gas permeability to enable analyte access, then the sensor can function, but liquid electrolyte can escape through the same pathway
Solution Approach 1:
The C-shaped seal acts as a flexible barrier that can accommodate gas molecules passing through while maintaining liquid-tight sealing. The flexible nature of the seal allows it to conform to the interface pin and housing while preventing liquid electrolyte escape.
Solution Approach 2:
The seal structure allows for selective permeability where gas can pass through the seal material or around the interface pin, while the liquid electrolyte is blocked by the seal's liquid-tight contact points. This selective permeability enables gas access while preventing liquid loss.
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 annular seal significantly reduces sensor failure rates and extends the operational lifetime by providing a more reliable sealing mechanism that manages pressure and prevents excessive electrolyte loss, as demonstrated in comparative tests with O-ring seals.
Implementation Method 1
the seal is compressed between a wall of the port and the metal interface pin thereby restricting egress of liquid electrolyte from the housing
Implementation Method 2
allows controlled egress of fluid when pressure builds up
Data Source
AI summary
An electrochemical gas sensor comprising a housing containing a plurality of electrodes and a liquid electrolyte, the housing having a gas inlet, the sensor defining at least one port through the housing having a metal interface pin therein, the interface pin extending through the port from the exterior of the housing, being electrically connected to at least one of the plurality of electrodes in the interior of the housing, the sensor additionally comprising a seal located around the metal interface pin within the port, and compressed between a wall of the port and the metal interface pin thereby restricting egress of liquid electrolyte from the housing, wherein the seal comprises an annular seal which in its uncompressed form either presents a cross-section which is concave in a radially extending direction of the seal, or whose width is constant over an extended axial direction of the seal.