Gas Sensor Assembly Defect Detection via Heater Resistance Comparison
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Solution Overview
Problem
In the manufacturing of gas sensors, existing methods fail to reliably detect assembly defects and ensure that the heater resistance value meets standards, leading to potential defects in the final product and reduced productivity due to inspections being performed only after assembly.
Innovation Solution
A two-stage inspection method is implemented, where the heater resistance value of the sensor element is measured before incorporation into the gas sensor and again after assembly, with a comparison of the difference in resistance values to determine assembly defects, such as contact abnormalities between the electrode terminal and contact point member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If inspection is performed only after assembly, then device complexity is reduced, but manufacturing precision and reliability deteriorate because assembly defects cannot be detected
Solution Approach 1:
The patent implements preliminary inspection of the sensor element's heater resistance value before assembly into the gas sensor. This preliminary action allows detection of defective sensor elements prior to incorporation into the final product, preventing assembly defects from occurring while maintaining a relatively simple inspection process.
Solution Approach 2:
The patent establishes a feedback mechanism by comparing the heater resistance value measured after assembly with the predetermined standard value. When the measured value falls outside the predetermined range, the system provides feedback indicating an assembly defect, enabling corrective action to be taken.
2Manufacturing precision
If inspection is performed before assembly, then manufacturing precision improves, but productivity deteriorates due to additional inspection steps
Solution Approach 1:
The patent performs preliminary measurement of the heater resistance value on the sensor element before assembly. This allows early identification of defective elements, preventing waste of assembly time on components that will fail inspection, thereby actually improving overall productivity despite the additional measurement step.
Solution Approach 2:
By establishing feedback loops at multiple stages (before and after assembly), the system efficiently identifies and eliminates defective products early in the process, reducing rework and scrap rates, which ultimately improves productivity.
3Reliability
If two-stage inspection is implemented, then reliability improves by detecting both sensor element defects and assembly defects, but device complexity increases
Solution Approach 1:
The patent segments the inspection process into two distinct stages: first inspecting the sensor element's heater resistance value before assembly, and second inspecting the assembled gas sensor's heater resistance value. This segmentation allows each inspection stage to focus on specific defect types, improving overall reliability while keeping each individual inspection step relatively simple.
Solution Approach 2:
The dual-feedback mechanism (pre-assembly and post-assembly inspection) creates a comprehensive quality control system that reliably detects both manufacturing defects in sensor elements and assembly defects in the final product, significantly improving overall system reliability.
4Ease of manufacture
If only post-assembly inspection is performed, then ease of manufacture improves, but loss of time increases due to rework of defective assembled products
Solution Approach 1:
The patent measures the heater resistance value preliminarily before assembly, identifying and eliminating defective sensor elements prior to incorporation. This prevents the need for rework of assembled products, reducing time loss while maintaining simple assembly processes.
Solution Approach 2:
By providing feedback at the pre-assembly stage through heater resistance value measurement, the system prevents defective components from entering the assembly process, eliminating rework time and improving manufacturing efficiency.
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 approach allows for the reliable exclusion of defective gas sensors from the shipping process, ensuring that only sensors with normal heater resistance values and proper assembly are used, thereby enhancing product quality and productivity.
Implementation Method 1
a heater (a resistance heating heater)
Data Source
AI summary
Provided is a method of inspecting an assembly defect of a gas sensor in a mass-production process. The sensor element included in a second constituting member includes a heater therein and an electrode terminal for a heater in its surface, and the first constituting member includes a contact point member contacting the terminal in a state where the sensor element is inserted into its opening. A first heater resistance value before incorporated is measured to associate the resistance value with an identification information of the sensor element, a second heater resistance value is measured via a contact point member, in a state where the first and second constituting members are integrated with each other, to associate the resistance value with the identification information of the sensor element, and when a difference value between these resistance values associated with the identical identification information exceeds a threshold value, it is determined that an assembly defect occurs.