C-Shaped Weld Patterns for Battery Terminal Joints
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Solution Overview
Problem
High stress areas occur at the start and end points of weld beads in battery cell terminal/bus bar joints, which can lead to reduced strength and lifespan of these connections in electrified vehicle battery packs.
Innovation Solution
The use of unique weld patterns, such as Double-C and Single-C configurations, where weld beads extend along non-linear paths to position their start and end points at lower stress zones, improving stress distribution and securing bus bars to terminals using laser welding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional linear weld beads are used to connect bus bars to battery cell terminals, then the welding process is simple and quick, but high stress areas occur at the start and end points of the weld beads, reducing the strength and lifespan of the connections
Solution Approach 1:
The patent applies curvature by transitioning from linear weld beads to C-shaped or Double-C-shaped weld patterns. The curved geometry redistributes stress along the weld path, eliminating concentrated stress at linear endpoints and thereby improving joint strength and fatigue life.
Solution Approach 2:
The weld pattern is segmented into multiple distinct weld beads (e.g., first weld bead and second weld bead in Double-C configuration) rather than using a single continuous linear weld. This segmentation allows stress to be distributed across multiple zones, preventing stress concentration at any single point.
2Reliability
If weld beads are extended to cover larger areas of the bus bar, then the connection strength is improved, but the stress concentration at the start and end points increases, reducing the overall joint lifespan
Solution Approach 1:
The C-shaped and Double-C-shaped weld patterns use curved geometries that naturally distribute stress more evenly throughout the weld zone. The curved paths eliminate sharp corners and endpoints where stress would concentrate, thereby improving reliability while maintaining acceptable stress levels.
Solution Approach 2:
The weld pattern transitions from a one-dimensional linear path to a two-dimensional curved path that wraps around portions of the bus bar. This dimensional change allows the weld to engage more surface area and distribute stress across a broader zone, improving reliability without creating stress concentration points.
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
These weld patterns enhance the static strength and fatigue life of battery cell terminal/bus bar joints, optimizing stress distribution and rendering more robust connections.
Implementation Method 1
securing the bus bar to the first terminal with a first weld bead... using laser welding techniques
Data Source
AI summary
A battery assembly includes a first battery cell including a first terminal, a bus bar connected to the first terminal, and a first weld bead for securing the bus bar to the first terminal. The first weld bead includes a first end portion extending continuously to a second end portion and configured such that the first end portion faces in a direction toward the second end portion.