Pouch Battery Seal Inspection via Eddy Current Thickness Monitoring
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Solution Overview
Problem
Existing methods for inspecting the seal of pouch battery cells are inadequate due to the challenges posed by aluminum foil interference with optical methods and the impracticality of computed tomography, necessitating a more reliable and efficient method for verifying the seal integrity.
Innovation Solution
A method using eddy current distance sensors to measure the thickness of the seal seam, determining a reference value, and monitoring for deviations indicative of anomalies, which can be implemented inline during production, ensuring airtightness by detecting thickness changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If optical methods are used to inspect the seal, then the inspection can be performed with simple equipment, but the aluminum foil prevents optical access to the plastic layers
Solution Approach 1:
The patent replaces optical measurement methods with capacitive sensing technology. The capacitive sensor measures changes in capacitance caused by variations in seal thickness, enabling detection of seal quality without requiring optical access through the aluminum foil barrier.
Solution Approach 2:
The patent introduces a capacitive field as an intermediary measurement mechanism that can penetrate the aluminum foil and interact with the seal structure underneath, allowing indirect measurement of seal thickness without direct optical contact.
2Reliability
If computed tomography is used to inspect the seal, then the seal integrity can be verified, but the process is time-consuming and unsuitable for inline processing
Solution Approach 1:
The patent replaces computed tomography with capacitive sensing, substituting a complex, time-consuming imaging system with a rapid electrical measurement system that provides real-time feedback suitable for inline production environments.
Solution Approach 2:
The patent skips the lengthy data acquisition and reconstruction process of computed tomography by using direct capacitive measurements that provide immediate results, enabling fast inspection cycles compatible with high-speed manufacturing.
3Difficulty of detecting and measuring
If eddy current analysis is used to examine the foil bag, then the inner workings can be detected, but the method is complex and may not specifically identify seal thickness issues
Solution Approach 1:
The patent applies capacitive sensing specifically to the seal region with localized sensors positioned to detect only seal thickness variations, rather than using comprehensive eddy current analysis of the entire foil bag. This targeted approach simplifies the system while focusing detection on the critical seal area.
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
Enables rapid and reliable detection of seal defects, preventing electrolyte leakage by ensuring the integrity of the seal, suitable for 100% process monitoring and automation in manufacturing.
Implementation Method 1
A method using eddy current distance sensors to measure the thickness of the seal seam
Data Source
Figure 1~2
AI summary
The invention relates to a method for inspecting a sealing seam (14) of a pouch battery cell (2). In this method, a reference value (Sg) characteristic of the thickness of the sealing seam (14) is determined along the sealing seam (14) by means of a first and optionally also a second distance sensor (22, 24). The reference value (Sg) is monitored for deviations characteristic of thickness anomalies, and a warning message is issued in the event of such a deviation.