Gas Sensor Terminal Fitting Layout for Vibration Durability
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Solution Overview
Problem
Conventional gas sensors experience a higher likelihood of terminal fitting breakage due to vibrations, particularly when used in environments with intense vibrations, such as exhaust pipes of automobiles, as the phase mismatch between outer and inner components leads to metal fatigue and failure.
Innovation Solution
The gas sensor design incorporates a configuration where the second distance (db) from the start end of the reduced diameter portion to the positioning fixture is set to a value between 0.24 and 0.39 times the first distance (Da) from the start end to the protrusion, ensuring reduced metal fatigue and breakage while maintaining a safe distance from heat sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the terminal fitting is positioned close to the heat source to reduce sensor length, then the sensor becomes more compact, but the terminal fitting is exposed to high temperature causing contact failure
Solution Approach 1:
The patent applies parameter changes by establishing a specific ratio relationship between the first distance (Da) from the start end to the protrusion and the second distance (db) from the start end to the positioning fixture. By controlling the ratio db/Da to be within 0.15 to 0.40, the patent optimizes the thermal exposure of the terminal fitting while maintaining sensor compactness. This quantitative parameter control resolves the contradiction between sensor length and thermal exposure.
2Reliability
If the terminal fitting is positioned close to the protrusion to reduce vibration angle, then vibration resistance improves, but the distance from heat source decreases causing thermal exposure
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal range for the ratio db/Da (0.15 to 0.40) that simultaneously satisfies both vibration resistance and thermal protection requirements. By controlling this geometric parameter, the patent achieves both a small vibration angle and sufficient distance from the heat source.
Solution Approach 2:
The patent introduces a dimensional relationship (ratio of distances) as a new control dimension. Instead of independently optimizing db for vibration resistance, the patent controls the ratio db/Da, which adds a proportional relationship dimension that simultaneously addresses both vibration and thermal concerns.
3Temperature
If the distance db is increased to protect terminal fitting from heat, then thermal exposure reduces, but the angle of shake increases causing more vibration load
Solution Approach 1:
The patent applies parameter changes by establishing an optimal range for the ratio db/Da (0.15 to 0.40) that balances thermal protection and vibration load. By controlling this ratio, the patent ensures that db is sufficiently large for thermal protection while preventing the vibration angle from becoming too large.
Solution Approach 2:
The patent introduces the ratio db/Da as a controlling dimension that transforms the independent optimization of db into a proportional relationship. This dimensional change allows simultaneous optimization of thermal protection and vibration resistance through a single ratio parameter.
4Length of moving object
If the distance Da is decreased to shorten sensor, then sensor length reduces, but the ratio db/Da increases causing thermal exposure and vibration issues
Solution Approach 1:
The patent applies parameter changes by establishing an optimal range for the ratio db/Da (0.15 to 0.40) that must be maintained regardless of the absolute values of Da and db. This ratio constraint ensures that shortening Da does not compromise terminal fitting durability, as long as the ratio relationship is preserved.
Solution Approach 2:
The patent introduces the ratio db/Da as a new controlling dimension that decouples the relationship between sensor length and terminal fitting durability. By controlling the ratio rather than absolute distances, the patent enables independent optimization of sensor length while maintaining durability through ratio control.
Data Source
AI summary
Provided is a gas sensor that reduces a possibility that a terminal fitting electrically connecting a sensor element and a lead wire to each other breaks due to vibrations applied to the gas sensor. In the gas sensor according to one aspect of the present invention, a value obtained by dividing a second distance db, which is a distance from a start end that is an end of a reduced diameter portion of a tubular body on a frontmost end side to a positioning fixture of the terminal fitting, by a first distance Da, which is a distance from the start end to a protrusion of the tubular body, is 0.24 or more and 0.39 or less.