Gas Sensor Recessed Holder Reduces Axial Length
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Solution Overview
Problem
Existing gas sensors face challenges in reducing the axial length of the sensor element while maintaining detection performance and securing a required region for the porous protection layer, which is essential for cost reduction and energy conservation.
Innovation Solution
The gas sensor design incorporates a recessed portion in the holder to allow the rear end of the porous protection layer to be situated within it, reducing the protrusion length of the front end of the sensor element while maintaining exposure for detection, and utilizing a multi-layer protector to ensure effective protection and smooth gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the axial length of the sensor element is reduced to decrease noble metal material usage and power consumption, then cost and energy consumption are reduced, but the protrusion length of the front end part and the region for the porous protection layer are compromised
Solution Approach 1:
The holder includes a recessed portion that creates a stepped axial structure, allowing the sensor element to be positioned at different axial levels. The porous protection layer extends onto the recessed portion's surface, effectively utilizing the recessed space to maintain protection layer area while reducing the overall protrusion length of the sensor element from the holder's front end face.
Solution Approach 2:
The recessed portion of the holder is designed to receive and accommodate the porous protection layer, nesting it within the holder's structure. This allows the protection layer to be housed within the holder's axial space rather than requiring additional protrusion length, thereby reducing the sensor element's overall axial length while maintaining the necessary protection layer region.
2Length of moving object
If the protrusion length of the front end part of the sensor element is reduced, then the axial length is decreased, but the detection performance is compromised due to reduced exposure to the gas under measurement
Solution Approach 1:
The recessed portion creates an additional exposure surface at a different axial level. The porous protection layer extending onto this recessed surface provides an alternative pathway for gas to reach the detection portion, maintaining detection performance while reducing the front end protrusion length.
Solution Approach 2:
The porous protection layer is selectively positioned to extend onto the recessed portion's surface, creating a localized exposure region that compensates for the reduced front end protrusion. This localized quality change ensures that gas can still access the detection portion through the porous structure at the recessed level.
3Length of moving object
If the region for the porous protection layer is reduced to shorten the sensor element, then axial length is decreased, but the protection against thermal impact and foreign substance adhesion is compromised
Solution Approach 1:
The porous protection layer is nested within the recessed portion of the holder, utilizing the recessed space to house the protection layer. This nesting arrangement maintains the necessary protection layer region for thermal and contaminant protection while reducing the sensor element's overall axial length by eliminating the need for additional protrusion.
Solution Approach 2:
The protection layer is extended onto the recessed portion's surface, creating a two-level protection structure. This dimensional change allows the protection layer to be positioned at different axial levels, maintaining adequate protection region while reducing the sensor element's total axial length.
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 design effectively reduces the total length of the sensor element, minimizing the use of noble metal materials and power consumption without compromising detection performance, while ensuring the protection layer's required region is maintained, thus achieving cost reduction and energy conservation.
Implementation Method 1
a protection layer of porous material (e.g. spinel or alumina) is commonly formed on a predetermined surface region from the front end of the sensor element toward the rear in order to prevent the sensor element from deteriorating in detection performance due to the adhesion of a foreign substance contained in the exhaust gas or becoming broken due to the adhesion of water contained in the exhaust gas
Implementation Method 2
a detection portion constituted by an oxygen ion conducting solid electrolyte material and a pair of detection electrodes
Data Source
AI summary
Disclosed is a gas sensor having a metal shell, a holder placed in the metal shell and a sensor element inserted through an axial insertion hole of the holder. The holder has a recessed portion recessed toward the rear from a front end face of the holder. The sensor element has, at a front end part thereof, a detection portion covered with a porous protection layer such that a rear end of the porous protection layer is situated within the recessed portion of the holder and is located at the rear side with respect to the front end face of the holder while maintaining a space between an inner circumferential surface of the recessed portion and an outer circumferential surface of the porous protection layer.