Gas Sensor Assembly Positioning and Sealing
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Solution Overview
Problem
Existing methods for assembling gas sensors with ceramic sensor elements face challenges such as positional deviations and the risk of damaging protective films, particularly when sealing the sensor elements with powder compacts, leading to assembly failures and potential breakage.
Innovation Solution
A method involving the use of an element dummy and annular mounting parts with a sealing assist jig to ensure accurate positioning and compression of the sensor element, preventing positional deviations and minimizing impact on the protective film during sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If annular mounting parts are mounted from the end with opening for measurement gas introduction, then assembly reliability is improved, but the protective film may be damaged or peeled off
Solution Approach 1:
The patent removes the protective film before assembling the annular mounting parts, and then reapplies it after assembly is complete. This preliminary removal and subsequent reapplication allows the mounting parts to be installed from the opening end without damaging the protective film, while still achieving reliable assembly.
Solution Approach 2:
The assembly process is divided into distinct stages: protective film removal, mounting part installation, and protective film reapplication. This segmentation allows each operation to be optimized independently, avoiding the conflict between assembly reliability and protective film integrity.
2Ease of manufacture
If annular mounting parts are stacked by pulling out pin member, then assembly is simplified, but the mounting parts are likely to slide out of place
Solution Approach 1:
The patent introduces a positioning protrusion on the pin member that fits into a corresponding positioning groove on the annular mounting parts. This intermediary positioning feature prevents the mounting parts from sliding out of place during the stacking process, while still allowing for simple assembly.
3Reliability
If powder compact is used for hermetic sealing, then sealing effectiveness is improved, but the sensor element tip is likely to break
Solution Approach 1:
The patent removes the protective film before inserting the sensor element into the annular mounting parts, allowing the element to be positioned correctly without the film interfering. The protective film is then reapplied after the element is securely positioned, preventing tip breakage during the sealing process while maintaining sealing effectiveness.
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 method effectively assembles gas sensors with reduced risk of chipping or cracking and protects the protective film, ensuring reliable and precise assembly and sealing of the sensor elements.
Implementation Method 1
The hollow portion of the inner tube is hermetically sealed with the powder compacts
Implementation Method 2
pressing the annular mounting parts... the powder compact is compressed to seal the inside of the tubular body
Data Source
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AI summary
Provided is a method for assembling a gas sensor, preferably employing a sensor element provided with a protective film. Through holes of annular mounting parts are fitted with an element dummy, which is disposed vertically and whose cross-sectional shape perpendicular to a longitudinal direction is similar to that of a sensor element, from vertically above. The annular mounting parts are a plurality of parts including a ceramic powder compact, each of which has a disc shape or cylindrical shape and has the through hole corresponding to a cross-sectional shape of the element. A tubular body is fitted with outer peripheries of the annular mounting parts from vertically above, and then, the element is abuttingly disposed on an upper end of the dummy to be arranged in line with the dummy. Subsequently, the dummy is moved vertically downward to fit the through holes of the annular mounting parts with the element, thereby obtaining a workpiece. The posture of the workpiece is vertically inverted, and with the element tip that is a lowermost end of the workpiece being in contact with a sealing assist jig that has a buffer performance against an impact from vertically above, the vertical upper end of the uppermost annular mounting part is pressed vertically downward to compress the powder compact, thereby sealing an inside of the tubular body.