Elastic Seal Member Pressing Sensor Element in Exhaust Gas Temperature Sensor
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Solution Overview
Problem
Conventional temperature sensors for measuring exhaust gas temperature experience deterioration in responsiveness and temperature sensitivity due to vibration and thermal variations, which can cause cracking of the cement fixing the sensor element, leading to separation from the tube and breakage of core wires.
Innovation Solution
A temperature sensor design featuring an elastic seal member with rubber-like elasticity, which presses the rear end of the insulation sheath forward, maintaining contact between the sensor element and the tube, eliminating the need for cement and enhancing vibration resistance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cement is used to fix the sensor element and insulation sheath to the tube, then the assembly is initially stable, but vibration and thermal variations cause cracking and deterioration of responsiveness
Solution Approach 1:
The invention removes the cement fixing mechanism entirely and replaces it with a mechanical pressing structure. The pressing member, positioned at the rear end of the tube, applies continuous mechanical force to press the sensor element and insulation sheath against the tube's inner wall, eliminating the need for cement that cracks under vibration and thermal stress.
Solution Approach 2:
The invention replaces the chemical bonding mechanism (cement) with a mechanical pressing system. The pressing member creates continuous mechanical contact force that maintains stable connection between components, providing superior vibration resistance compared to cement that deteriorates under dynamic conditions.
2Device complexity
If the insulation sheath is not actively fixed at the rear end, then the structure is simpler, but the core wires are vulnerable to breakage under vibration
Solution Approach 1:
The pressing member performs multiple functions simultaneously: it presses the sensor element against the tube for thermal contact, secures the insulation sheath in position, and protects the core wires from vibration-induced breakage. This multi-functional design simplifies the overall structure while enhancing reliability.
3Measurement precision
If the sensor element is in direct contact with the tube to enhance heat transfer, then temperature sensitivity improves, but the element becomes vulnerable to separation under vibration
Solution Approach 1:
The pressing member applies preliminary continuous force to maintain stable contact between the sensor element and tube before vibration occurs. This pre-applied mechanical force ensures that the element remains firmly pressed against the tube's inner wall at the front end, maintaining optimal thermal contact and measurement accuracy even under vibrational 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
The solution stabilizes the contact between the sensor element and the tube, preventing deterioration in responsiveness and temperature sensitivity, while reducing the risk of core wire breakage and simplifying the assembly process by eliminating the need for cement.
Implementation Method 1
an elastic seal member having rubber-like elasticity, which presses the rear end of the insulation sheath forward by means of deformation of the seal member
Data Source
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AI summary
A sensor (101) is configured such that a seal member (71) is provided in a deformed manner through crimping of a portion of a tube (11) located toward a rear end (17c) of the tube (11). The seal member (71) is deformed such that a frontward-oriented surface (75), which is a bottom surface of a recess (74) formed in a front end (73) of the seal member (72), presses a rear end (45) of an insulation sheath (41) frontward. Consequently, a front end (21a) of a sensor element is pressed against a front end (12) of the tube (11) via the insulation sheath (41). By virtue of a pressing action induced by rubber-like elasticity, high sensor responsiveness is maintained over a long period of time.