Gas Sensor Reference Electrode Tapered Lead Section
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Solution Overview
Problem
Existing gas sensors face challenges in maintaining a uniform temperature distribution along the axial direction of the sensor element, which affects the accuracy of air-fuel ratio detection, particularly in the slightly rich region, due to heat transfer issues from the detection electrode to the housing.
Innovation Solution
The gas sensor employs a reference electrode with an inner lead section that is tapered in shape, reducing its formation region stepwise from the detection section to the connecting section, minimizing heat transfer and maintaining a uniform temperature distribution by adjusting the shape and width in the circumferential direction of the inner lead section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the reference electrode is formed with a uniform cross-section along its length, then the manufacturing process is simple, but heat transfer from the detection electrode to the housing increases, causing temperature non-uniformity
Solution Approach 1:
The reference electrode is designed with varying cross-sectional areas along its length, where the cross-sectional area is smaller near the detection electrode and larger near the housing. This local variation in geometry optimizes heat transfer characteristics at different positions, maintaining uniform temperature distribution along the axial direction while preventing excessive heat transfer to the housing.
2Measurement precision
If the inner lead section has a larger formation region, then the electrical connection is more robust, but heat transfer to the housing increases and detection accuracy decreases
Solution Approach 1:
The formation region of the inner lead section is optimized by varying its cross-sectional area along the axial direction. The cross-sectional area is controlled to be within 0.1mm² to 1mm², with a preference for 0.3mm² to 0.7mm². This parameter optimization reduces heat transfer to the housing while maintaining sufficient electrical connection, thereby improving detection accuracy in the slightly rich region.
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 configuration enhances the detection accuracy of the air-fuel ratio in the slightly rich region by maintaining a high and uniform temperature suitable for the solid electrolyte and electrodes, improving the sensitivity and stability of the gas sensor.
Implementation Method 1
a heater that has a tip portion including a heating section for heating the solid electrolyte
Data Source
AI summary
A gas sensor includes: a sensor element including a bottomed tubular solid electrolyte, a detection electrode, and a reference electrode; and a heater for heating the solid electrolyte. The reference electrode includes an inner detection section on an entire periphery in a circumferential direction at an endmost position on a tip side on the reference electrode, an inner connecting section on an entire periphery in the circumferential direction at an endmost position on a base end side on the reference electrode, and an inner lead section on a part in the circumferential direction at a position where the inner detection section is connected to the inner connecting section. A formation region in the circumferential direction of the inner lead section is reduced stepwise from the inner detection section toward the inner connecting section.