Battery Module Weld Fatigue Testing with Segmented Flexible Tubes
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Solution Overview
Problem
Conventional welding portion fatigue failure verification devices struggle to provide an environment similar to actual swelling conditions in battery modules, especially when dealing with small battery modules, due to the difficulty in applying uniform force and the limited size of hydraulic units.
Innovation Solution
A fatigue failure verification device is designed with flexible tubes and buffer pads that simulate the swelling environment by individually controlling fluid supply to multiple flexible tubes, allowing for precise application of force in various directions to mimic the expansion of battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a small hydraulic unit is used in the conventional verification device, then the device complexity is reduced, but the force application capability is insufficient for small battery modules
Solution Approach 1:
The patent divides the single hydraulic unit into multiple independent flexible tubes (first, second, third, and fourth flexible tubes) that can be independently controlled. This segmentation allows each tube to apply force to specific regions of the battery cell, achieving uniform force distribution across the entire cell surface without requiring a large centralized hydraulic unit.
Solution Approach 2:
The patent transitions from a centralized single-point force application (conventional hydraulic unit) to a distributed multi-point force application system. By arranging flexible tubes at different positions (front/rear and left/right sides) of the battery cell, the system achieves three-dimensional force distribution, enabling uniform pressing force across the entire battery cell surface area.
2Device complexity
If a conventional hydraulic unit is used, then the device structure is simple, but uniform force application to the entire battery cell area is difficult
Solution Approach 1:
The hydraulic system is segmented into multiple independent flexible tubes, each capable of independent fluid supply control. This allows precise control of force application at different locations on the battery cell, achieving uniform force distribution across the entire cell area while maintaining relative structural simplicity through modular design.
Solution Approach 2:
Each flexible tube is equipped with independent fluid supply capability, allowing local adjustment of force application. This enables different regions of the battery cell to receive precisely controlled forces according to their specific requirements, achieving uniform overall force distribution through localized control.
3Reliability
If charging and discharging fatigue test is performed, then the verification accuracy is high, but the testing time is excessively long
Solution Approach 1:
The patent applies preliminary mechanical pressing forces using flexible tubes to simulate the cumulative effect of repeated swelling and contraction before actual fatigue testing. This preliminary action pre-stresses the welding portion, allowing accelerated fatigue testing that requires fewer charging-discharging cycles while maintaining verification accuracy.
Solution Approach 2:
The patent implements periodic pressing and releasing cycles using the flexible tubes to simulate the repetitive swelling and contraction of battery cells. This periodic mechanical stimulation accelerates fatigue accumulation in the welding portion, reducing the number of actual charging-discharging cycles needed for verification.
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 device effectively simulates the actual swelling environment of battery modules, enabling accurate design of the welding portion by replicating the expansion and contraction forces experienced by battery cells, thereby preventing damage to the housing.
Implementation Method 1
a pump 35, located outside the module housing 10, and adjusts a pressure applied by the main flexible tube 31 to the battery cell 20 by supplying a fluid to the main flexible tube 31
Implementation Method 2
the main flexible tube 31 presses the battery cell 20 located on both sides of the main flexible tube 31 toward side walls of the module housing 10
Data Source
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AI summary
A fatigue failure verification device according to an embodiment of the present disclosure includes: a module housing including a welding portion; a cell stack including a plurality of battery cells accommodated in the module housing; at least one main flexible tube located in a central portion of the cell stack in a stack direction of the cell stack; a main flexible tube frame in which the main flexible tube is accommodated, the main flexible tube frame including a pair of opening portions formed on both sides so that the main flexible tube faces the battery cell; and a pump configured to adjust a pressure applied by the main flexible tube to the battery cell by supplying a fluid to the main flexible tube.