Exhaust Temperature Sensor Protrusion Geometry for Catalytic Converter Accuracy
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Solution Overview
Problem
Existing temperature sensors for exhaust systems face challenges in accurately measuring the central temperature of catalytic converters with large diameters, as they tend to experience resonance issues leading to damage and reduced accuracy due to increased vibration and heat transfer, especially when trying to minimize protrusion length for vibration resistance.
Innovation Solution
A temperature sensor design with a protruding length of 50mm or more, optimized protruding location, and specific geometric relationships between the sensor and the flow path, along with a durable construction using a thermister and metallic cover, to reduce heat transfer and enhance vibration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the protruding length of the temperature sensor is increased to measure the central temperature of large-diameter catalytic converters, then the measurement accuracy of central temperature is improved, but the resonance frequency decreases leading to increased vibration and sensor damage
Solution Approach 1:
The patent applies parameter changes by specifying precise geometric relationships (L1'/D1 ≥ 0.5 and L1 ≥ 50mm) to optimize the balance between measurement accuracy and vibration resistance. This quantitative parameter specification resolves the contradiction by defining the optimal protruding length range that achieves both goals simultaneously.
2Reliability
If the protruding length of the temperature sensor is decreased to increase resonance frequency and avoid vibration resonance, then the vibration resistance is improved, but the heat transfer increases leading to inaccurate temperature measurement
Solution Approach 1:
The patent uses parameter changes to establish the minimum protruding length L1 ≥ 50mm and the geometric relationship L1'/D1 ≥ 0.5, which ensures sufficient heat isolation while maintaining vibration resistance. This quantitative approach resolves the contradiction by defining the optimal parameter range.
3Adaptability or versatility
If the temperature sensor is installed in large-diameter catalytic converters, then the measurement of central portion temperature is enabled, but the protruding length must be increased which facilitates resonance and causes sensor breakage
Solution Approach 1:
The patent applies parameter changes by defining the geometric relationship L1'/D1 ≥ 0.5 and minimum protruding length L1 ≥ 50mm, which enables adaptation to large-diameter catalytic converters while preventing resonance-induced breakage through optimized dimensional parameters.
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 enables accurate measurement of the maximum temperature in the central portion of the catalytic converter while maintaining durability and reducing resonance-related damage, improving the accuracy and longevity of the temperature sensor.
Implementation Method 1
a temperature sensor including a temperature sensitive device which is disposed in a flow path through which fluid flows and whose electric characteristic changes as a function of temperature of the fluid in the flow path
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~4
AI summary
A protruding length L1 that is a distance between an inner circumference of a flow path through which fluid flows on an axis of a temperature sensor disposed in the flow path and the center of said temperature sensitive device is 50mm or more. A protruding location that is a distance between an inner circumferential surface of the flow path and the center of said temperature sensitive device on a cross section extending perpendicular to the axis of said flow path through the center of said temperature sensitive device is defined as L1'. A flow path width that is a distance between intersections of the axis of the temperature sensor with the inner circumferential surface of said flow path when the temperature sensor is projected onto said cross section is defined as D1. A relation of L1'/D1 is specified as a function of the value of D1, thereby reducing heat transfer in an exhaust temperature sensor and enabling the temperature to be measured accurately.