Gas Sensor Elastic Body Erosion Prevention
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Solution Overview
Problem
Conventional gas sensors face issues with erosion of the elastic body when shortened, risk of lead retaining portion contacting the inner surface of the through-hole, and deterioration of airtightness and measurement accuracy due to the lead retaining portion blocking the through-hole.
Innovation Solution
A gas sensor design with a single diameter-reduced portion for fixing the elastic body, ensuring a minimum 0.1 mm distance between the lead retaining portion and the elastic body's end surface, and adjusting dimensions to satisfy the expression (Da-Db)×Sa > Fc/(μ×q) to prevent contact misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the gas sensor is shortened to reduce overall length, then the compactness is improved, but the elastic body is exposed to high temperature and suffers erosion
Solution Approach 1:
The patent positions the diameter-reduced portion at the rear end of the tubular body, changing the spatial arrangement from distributed swaging points to a concentrated rear-end swaging point. This dimensional repositioning allows the elastic body to be fixed at the rear end, creating sufficient distance between the heat source at the front end and the elastic body, thereby protecting the elastic body from high-temperature erosion while maintaining overall sensor compactness.
2Device complexity
If the lead retaining portion is accommodated in the through-hole of the elastic body, then the structural integration is improved, but the airtightness deteriorates due to contact with inner surface
Solution Approach 1:
The patent extracts the lead retaining portion from the through-hole of the elastic body and relocates it to the rear end of the tubular body. This separation eliminates the contact between the lead retaining portion and the inner surface of the through-hole, preventing deterioration of airtightness while maintaining structural integration through the concentrated rear-end configuration.
3Device complexity
If the lead retaining portion is accommodated in the through-hole, then the assembly is compact, but the measurement accuracy deteriorates due to blocking the through-hole
Solution Approach 1:
The patent extracts the lead retaining portion from the through-hole and positions it at the rear end of the tubular body. This extraction prevents the lead retaining portion from blocking the through-hole, ensuring that gas can flow freely through the elastic body without obstruction, thereby maintaining measurement accuracy while achieving assembly compactness through the rear-end concentration design.
4Reliability
If two diameter-reduced portions are used to fix the elastic body, then the fixing reliability is improved, but the elastic body length increases
Solution Approach 1:
The patent merges the functions of multiple diameter-reduced portions into a single diameter-reduced portion located at the rear end of the tubular body. This consolidation reduces the elastic body length by eliminating redundant swaging sections while maintaining fixing reliability through the strategically positioned rear-end swaging point that ensures adequate distance from the heat source.
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 design reduces the risk of elastic body erosion, prevents contact misalignment, and maintains airtightness and measurement accuracy by ensuring adequate distance and static friction to restrict lead movement, while simplifying manufacturing and reducing material costs.
Implementation Method 1
an expression (1) given below is satisfied: (Da-Db)×Sa>Fc/(μ×q) where μ is a coefficient of static friction between the elastic body and the covered section of the lead
Implementation Method 2
one diameter-reduced portion that swages a part of the elastic body from a periphery of the elastic body is provided in the tubular body
Data Source
AI summary
Provided is a gas sensor that is low in risk of erosion of an elastic body even when the gas sensor is shortened and prevents a lead retaining portion from coming into contact with an inner surface of a through-hole of the elastic body or closing the through-hole. In the gas sensor according to one aspect of the present invention, one diameter-reduced portion for fixing the elastic body to a tubular body is provided, the lead retaining portion is apart from a front end surface of the elastic body by 0.1 mm or more, and a size or the like of each member is adjusted to satisfy a predetermined relational expression, thereby preventing the occurrence of contact misalignment.