EV Battery Terminal Laser Welding Assembly
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Solution Overview
Problem
The existing methods for electrically connecting bus bars to electric vehicle battery terminals are time-consuming and prone to damage due to assembly tolerance stack-ups and risks of over-torquing and cross-threading, especially with the large number of connections required.
Innovation Solution
The method involves laser welding a landing of the terminal to a bus bar, with the landing and base positioned on different planes, and using a terminal holder with a step to support the landing, while communicating air through an open area to manage thermal energy generated during welding, forming a lap joint connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded connections (bolts and nuts) are used to secure bus bars to battery terminals, then the connection can be mechanically secured, but the assembly process becomes time-consuming and prone to damage from over-torquing and cross-threading
Solution Approach 1:
The patent replaces the mechanical threaded connection system (bolts and nuts) with a laser welding process that creates metallurgical bonds between the bus bar and battery terminal. This substitution eliminates the need for threading operations, torque control, and nut installation, thereby dramatically reducing assembly time while maintaining or improving connection reliability through direct metal fusion.
Solution Approach 2:
The patent changes the connection method from mechanical (threaded) to thermal (laser welding). By altering the fundamental parameter of connection methodology from mechanical fastening to thermal fusion, the process achieves both faster assembly and reliable connections without the drawbacks of threaded assemblies.
2Ease of operation
If threaded connections are used, then mechanical securing is achieved, but assembly tolerance stack-ups cause difficulty in automation
Solution Approach 1:
By replacing the mechanical threaded connection system with laser welding, the patent eliminates the sensitivity to assembly tolerances that plagues threaded fastening. Laser welding can accommodate greater tolerance variations while maintaining connection quality, and the automated laser welding process is inherently more tolerant of positional variations than automated threaded fastening, which requires precise hole alignment and thread engagement.
3Productivity
If laser welding is used to connect bus bars to terminals, then assembly time is reduced and productivity increases, but thermal energy generation requires management to prevent damage
Solution Approach 1:
The patent converts the harmful thermal energy generated during laser welding into a beneficial process by using the heat to create the metallurgical bond itself. The laser energy that could be considered harmful excess heat is instead utilized to melt and fuse the bus bar and terminal materials, creating a strong weld joint. Any excess thermal energy is managed through controlled dissipation to prevent damage to surrounding components.
4Ease of manufacture
If the landing and base are positioned on different planes, then the terminal structure provides better welding access and lap joint formation, but the terminal design becomes more complex
Solution Approach 1:
The patent resolves the conflict between welding accessibility and structural simplicity by transitioning from a two-dimensional planar terminal design to a three-dimensional stepped structure. By positioning the landing and base on different planes (different z-heights), the design creates optimal geometric relationships for laser welding access and lap joint formation, while the stepped configuration remains a straightforward extension of typical terminal geometry rather than a complex multi-component assembly.
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 significantly reduces assembly time, minimizes the risk of damage to connections, and ensures robust weld formation, enhancing the efficiency and reliability of electric vehicle battery assembly.
Implementation Method 1
welding a landing of a terminal to a bus bar... the welding comprises laser welding... the laser welded lap joint securing the bus bar to the terminal
Implementation Method 2
communicating air through an open area under the landing to remove thermal energy generated during the welding
Data Source
AI summary
An example method of connecting an electric vehicle battery includes welding a landing of a terminal to a bus bar, and pressing a landing of the terminal and the bus bar against one another during the welding. The landing is along a first plane and a base of the terminal is along a second plane that is spaced from the first plane.