Battery Cell Contact Surface Structuring for Ultrasonic Welding
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Solution Overview
Problem
Existing cell connecting systems for vehicle battery modules face challenges in achieving reliable mechanical and electrical connections, particularly under stress conditions like vibrations and shocks, which affect the monitoring capabilities of battery cells in electric and hybrid vehicles.
Innovation Solution
The cell connecting system incorporates surface area enhancing features on the contact element and sensing cable, such as bumps or pyramidal patterns, to increase the contact surface area, allowing for improved mechanical and electrical connections through ultrasonic welding, and a method to create these features using stamping, scratching, or laser structuring to enhance the peeling force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a smooth surface is used for the contact element and wire, then the manufacturing process is simple, but the mechanical contact force and welding stability are insufficient
Solution Approach 1:
The patent applies local quality by introducing surface area enhancing features (bumps, pyramidal structures) only in the specific contact region between the wire and contact element, while keeping other areas smooth. This localized modification increases the contact surface area and mechanical contact force exactly where needed, without complicating the overall structure or manufacturing process of the entire component.
Solution Approach 2:
The patent employs curved surface features such as bumps and pyramidal structures with rounded edges in the contact area. These curved geometries increase the surface area compared to flat surfaces, providing better contact force distribution and welding stability. The curvature also helps in stress distribution and prevents stress concentration points that would occur with sharp edges.
2Reliability
If surface area enhancing features are added to increase contact surface area, then the welding force and connection reliability improve, but the manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the surface area enhancing features (bumps, pyramidal structures) on the contact element or wire before the welding process. This pre-structuring ensures that when welding occurs, the enhanced surface area is already in place to provide optimal contact and welding conditions, eliminating the need for complex real-time adjustments during manufacturing and improving both reliability and ease of manufacture.
Solution Approach 2:
The patent utilizes parameter changes by modifying the surface geometry parameters (introducing bumps with specific heights, pyramidal structures with defined angles) to optimize the contact surface area. By carefully selecting and controlling these geometric parameters within specific ranges, the patent achieves improved welding force and connection reliability while keeping the manufacturing process manageable through standardized dimensional specifications.
3Stability of the object's composition
If the connection must withstand vibrations and shocks, then the mechanical stress resistance improves, but the connection structure becomes more complex
Solution Approach 1:
The patent applies local quality by concentrating the stress-resistant features (surface area enhancing structures) specifically in the contact region where mechanical stress from vibrations and shocks is most intense. This localized reinforcement provides the necessary mechanical stress resistance without requiring complex structural modifications throughout the entire connection assembly, maintaining simplicity while improving durability.
Solution Approach 2:
The patent employs curved surface features with rounded geometries that distribute mechanical stress more evenly across the contact area. The curved bump and pyramidal structures prevent stress concentration at sharp edges, thereby improving resistance to vibrations and shocks. This curvature-based approach enhances mechanical stability without adding complex structural elements, as the stress-distributing geometry is achieved through surface modification rather than structural complexity.
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 enhanced surface area features lead to higher and more stable welding forces, improving the reliability of connections and extending the lifetime of the battery module by ensuring connections withstand mechanical stress, with peel-off forces exceeding the required 7N in tests.
Implementation Method 1
The connection between the cable and the cell connecting system is realized using ultrasonic welding
Data Source
Figure 1
Figure 2a~2b
Figure 2c~3
AI summary
The invention relates to a cell connecting system for a vehicle battery module, in particular for an electric or hybrid vehicle. It comprises a contact element for receiving an electrical pole of at least one battery cell, a sensing cable comprising a wire electrically and mechanically connecting a cell monitoring unit and the contact element. The cell connecting system is characterized in that the surface of the wire and/or the contact element comprises surface area enhancing features in the area of contact with each other. The surface area enhancing features improve the welding process as higher welding forces with more material transfer between the welding parts can be achieved. The invention also relates to a method to manufacture the cell connecting system.