Gas Sensor Separator Fixation via Compressed Rubber Cap
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Solution Overview
Problem
The existing gas sensor design is prone to vibration relative to the outer casing in the axial line crossing direction, leading to stress between the front and rear connection portions of the metal terminal, which can result in breakage due to the separator not being fixed within the outer casing.
Innovation Solution
The separator is elastically compressed and fixed between the rubber cap and the front side member, utilizing a rubber cap with a compression set of 32.3% or less after 25% compression in a 250°C environment for 67 hours to reduce vibration and maintain fixation over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the separator is not fixed inside the outer casing, then the assembly is simple and easy to manufacture, but the separator vibrates relative to the outer casing causing stress and potential breakage of the metal terminal
Solution Approach 1:
The rubber cap is pre-compressed in the axial direction during assembly to immediately secure the separator in position, preventing vibration before it can cause damage to the metal terminal
Solution Approach 2:
The rubber cap serves as an intermediary component between the separator and the outer casing, using its elastic properties to provide damping and vibration reduction while maintaining the separator's fixed position
2Reliability
If a rubber cap with high elasticity is used to reduce vibration, then the separator is well-fixed, but the rubber cap deforms excessively in high-temperature environments over time
Solution Approach 1:
The compression set of the rubber cap is controlled within a specific range (5% to 30%) to optimize the balance between vibration reduction capability and dimensional stability in high-temperature environments
Solution Approach 2:
The rubber cap is made from elastomeric materials with specific physical properties that provide both elasticity for vibration damping and thermal stability for maintaining shape in high-temperature conditions
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 solution effectively reduces the likelihood of separator vibration relative to the outer casing, minimizing stress and potential breakage of the metal terminal, while maintaining the separator's fixation state over a long period, even in high-temperature environments.
Implementation Method 1
the separator is interposed and fixed between a rubber cap located on a rear side with respect to the separator and elastically compressed in the axial direction and a front side member located on a front side with respect to the separator
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
In a gas sensor (1) including a sensor element (5), a metal shell (3), an outer casing (11), metal terminals (41 to 44), a separator (13), lead wires (31 to 34), and a rubber cap (15), the separator (13) is interposed and fixed between the rubber cap (15) located on a rear side with respect to the separator (13) and elastically compressed in an axial direction DX and a front side member (67) located on a front side with respect to the separator (13). A compression set of the rubber cap (15) after the rubber cap (15) is compressed by 25% in the axial direction DX in a temperature environment of 250°C for 67 hours is 32.3% or less.