Gas Sensor U-Spring Curved Ends and Tube Roughness
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Solution Overview
Problem
Conventional gas sensors face issues with vibration resistance due to pressure springs getting caught inside the metal tube, leading to defective contact and wear or cracking of the sensor element over time.
Innovation Solution
A gas sensor design featuring ceramic housings, U-shaped elastic members with curved contact portions, and a metal tube with an arithmetical mean roughness of 1 µm or less, which allows for improved sliding and absorption of vibrations, preventing the elastic members from getting caught and ensuring reliable contact between the sensor element and contact fittings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure springs are used to press contact fittings and electrodes, then reliable electrical contact is achieved, but the pressure springs may get caught inside the metal tube during vibration and fail to perform elastic function
Solution Approach 1:
The pressure springs are designed with U-shaped curved structures instead of straight configurations. This curvature allows the ends of the pressure springs to slide along the inner periphery of the metal tube during vibration, preventing them from getting caught and stuck, thereby maintaining their elastic function and vibration absorption capability while ensuring reliable electrical contact
Solution Approach 2:
The inner periphery of the metal tube is designed with specific roughness parameters (Ra value between 0.1-1.0 μm) to optimize the sliding interaction with the curved ends of the pressure springs. This parameter control ensures smooth movement during vibration while maintaining sufficient friction for reliable contact pressure
2Stability of the object's composition
If the metal tube is crimped to secure pressure springs, then the pressure springs are held in position, but the rough inner periphery causes the pressure springs to get stuck during vibration
Solution Approach 1:
The inner periphery roughness of the metal tube is precisely controlled within the range of Ra 0.1-1.0 μm through surface treatment processes. This optimized roughness parameter allows the crimped metal tube to securely hold the pressure springs in position while enabling smooth sliding of the curved spring ends during vibration, preventing them from getting stuck
3Reliability
If pressure springs apply continuous pressing force, then contact reliability is maintained, but vibration causes defective contact and wear or cracking of the sensor element
Solution Approach 1:
The U-shaped curved ends of the pressure springs enable them to absorb vibration energy through elastic deformation and sliding motion along the metal tube inner periphery. This curvature design allows the pressure springs to maintain continuous contact pressure on the electrodes while isolating the sensor element from vibration-induced stress, preventing wear and cracking over time
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 enhances vibration resistance, reducing the likelihood of defective contact and wear, thereby extending the lifespan of the gas sensor.
Implementation Method 1
a first elastic member substantially U-shaped in cross section, in contact with an inner periphery of the metal tube at both ends of the U-shape, and configured to press the first housing with an elastic force generated by pressure from the metal tube
Implementation Method 2
at least one of both the ends of the first elastic member is formed as a curved contact portion having a curved surface that is in contact with the inner periphery of the metal tube and has a curvature radius smaller than or equal to a curvature radius of the contact portion of the inner periphery of the metal tube
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In a gas sensor, when an arithmetical mean roughness Ra of an inner periphery of a metal tube 95 is 1 µm or less and end portions 93 and 94 of U-springs 92 are formed as curved contact portions, the end portions 93 and 94 of the U-springs 92 can slide smoothly along the inner periphery of the metal tube 95. Therefore, when vibration is applied to the gas sensor, the U-springs 92 can be prevented from being caught in the inner periphery of the metal tube 95, and the vibration can be absorbed by an elastic function of the U-springs 92. Even if the gas sensor vibrates, defective contact between a sensor element 20 and contact fittings 71 and wear and cracks in the sensor element 20 are less likely to occur. That is, the gas sensor resistant to vibration can be obtained.