Gas Sensor Element Fixation via Preliminary Compression
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Solution Overview
Problem
Conventional gas sensor manufacturing methods can cause breakage of the sensor element due to misalignment and non-uniform stress from the compression of talc rings, leading to potential shearing stress and element failure.
Innovation Solution
A method involving a tubular holder and compacted filling member within a metallic shell, where a metallic pin is used for pre-compression to form a filling member intermediate, allowing uniform distribution and preventing breakage by maintaining the shape and ensuring even stress distribution during the main compression step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If talc rings are compressed using conventional methods, then the sensor element can be held within the metallic shell, but misalignment and non-uniform stress occur causing sensor element breakage
Solution Approach 1:
A preliminary compression step is performed before the main compression step. In this preliminary step, the talc ring is compressed to a predetermined density that is lower than the final density, creating a preliminary compressed state. This preliminary action allows the filling member to be pre-positioned in a controlled manner, reducing misalignment and non-uniform stress during subsequent main compression, thereby preventing sensor element breakage while ensuring proper alignment.
2Ease of manufacture
If talc powder is compressed to hold the sensor element, then the sensor element is fixed within the metallic shell, but non-uniform stress distribution causes shearing stress and element failure
Solution Approach 1:
The preliminary compression step creates a uniform preliminary compressed state throughout the filling member before the main compression step. This preliminary action ensures that stress is distributed more uniformly during the subsequent main compression, preventing concentration of stress at specific points that would create shearing stress on the sensor element, thereby maintaining element strength while achieving proper fixation.
Solution Approach 2:
The compression process is divided into two stages with different density targets. The preliminary compression step compresses the talc ring to a first predetermined density, and the main compression step compresses it to a second predetermined density that is higher than the first. This parameter change approach allows controlled stress distribution, preventing non-uniform stress concentration that would cause shearing stress and element failure.
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
Prevents breakage of the sensor element by ensuring uniform stress distribution and maintaining the shape of the filling member, facilitating easy insertion and secure fixation of the sensor element within the metallic shell.
Implementation Method 1
a main compression step of compressing the filling member intermediate to thereby form the filling member which fixes the sensor element inside of the metallic shell
Data Source
AI summary
A method for manufacturing a gas sensor includes: disposing a tubular holder and a tubular compact in a tubular metallic shell defining a through hole, the tubular holder defining a first insertion hole, and the tubular compact defining a second insertion hole; preparing a preliminary assembly in which a pin is inserted into the first insertion hole and the second insertion hole; pulling out the pin from the first insertion hole and the second insertion hole and inserting a sensor element into the first insertion hole and the second insertion hole such that a forward end of the pin will come into contact with an end of the sensor element; compressing the compact to thereby fix the sensor element inside of the metallic shell; welding a protection sleeve to the metallic shell to thereby form a semi-assembly; and combining the semi-assembly with another semi-assembly to thereby form the gas sensor.