Gas Sensor Air Permeability Filter Thermal Protection
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Solution Overview
Problem
Conventional gas sensors in exhaust systems face heat-induced deterioration of air permeability filters, leading to potential water infiltration due to compromised waterproof properties.
Innovation Solution
The design incorporates an air permeability filter crimped between an elastic insulating member and a tubular member, with strategically positioned air vents and passage portions to maintain waterproof integrity, utilizing a porous polytetrafluoroethylene filter for enhanced heat and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the air permeability filter is retained between the air cover and outer cover, then air can be introduced into the gas sensor, but the filter easily receives heat via the air cover or outer cover causing heat deterioration and compromising waterproof property
Solution Approach 1:
The patent introduces a heat-resistant tubular member as an intermediary component between the air cover and the air permeability filter. This tubular member acts as a thermal barrier that protects the filter from direct heat exposure while still allowing air to pass through to the sensor element, thus resolving the contradiction between maintaining air introduction functionality and preserving waterproof integrity.
Solution Approach 2:
The air permeability filter is extracted from its original position between the air cover and outer cover, and relocated to be crimped around the tubular member. This repositioning removes the filter from the direct heat exposure zone, preventing heat deterioration while maintaining its air permeability function.
2Ease of manufacture
If the air permeability filter is crimped to be retained by calking portions, then the filter is secured in place, but the waterproof property at the calking portions may fail due to heat deterioration
Solution Approach 1:
The tubular member serves as a protective intermediary that shields the calking portions from direct heat exposure. By positioning the filter around this heat-resistant structure rather than directly against the heat-prone air cover, the calking portions maintain their waterproof integrity while still achieving secure filter retention.
3Duration of action of moving object
If the gas sensor is used in exhaust of the internal combustion engine any number of times, then the sensor continues to operate, but the permeability filter is subject to heat deterioration
Solution Approach 1:
The patent converts the harmful heat exposure into a beneficial design feature by using the heat-resistant properties of the tubular member to create a protected zone for the filter. The exhaust system's heat, which would normally deteriorate the filter, is instead utilized to demonstrate the thermal stability of the tubular member's material, allowing the filter to withstand the harsh environment.
Solution Approach 2:
The patent employs composite material construction by combining the heat-resistant tubular member with the air permeability filter. This composite structure leverages the thermal stability of the tubular member material to protect the filter, creating a multi-material system that maintains filter performance under repeated heat exposure in the exhaust system.
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
This configuration prevents water infiltration and maintains the waterproof property of the gas sensor even under heat exposure, ensuring reliable air introduction and reducing clogging risks.
Implementation Method 1
an air permeability filter wound around an outer circumference of said tubular member and crimped between said elastic insulating member and said tubular member
Implementation Method 2
an elastic insulating member having a lead wire insertion hole for receiving said lead wire and sealing the base portion of said air cover
Implementation Method 3
a tubular member forming an internal space that is open at an end thereof and having a through-hole penetrating between said internal space and an outer side of said tubular member is disposed in said longitudinal hole
Data Source
AI summary
A gas sensor having an elastic insulating member including a longitudinal hole for receiving an air permeability filter assembly and a passage portion communications between the longitudinal hole and an outer side thereof.