Battery Pack Tab Terminal Piercing for Load-Triggered Disconnect
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Solution Overview
Problem
Existing traction battery packs in electrified vehicles lack an effective mechanism to electrically disconnect battery cells when external loads are applied, potentially leading to exposure to high voltages and structural integrity issues.
Innovation Solution
The battery pack system incorporates a cross-member with apertures and a pointed or serrated edge that pierces tab terminals to sever the electrical circuit when a load is applied, using polymer-based materials and welds to connect tab terminals, allowing for relative movement between the cell stack and cross-member to open the circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tab terminals are rigidly fixed to maintain electrical connection, then electrical connectivity is improved, but vulnerability to external loads and structural integrity deteriorates
Solution Approach 1:
The tab terminal connection system transitions from a static rigid connection to a dynamic system that can adapt its state. The tab terminal is positioned within a distance of 3mm from the pointed edge, allowing it to move or deform under external loads, thereby opening the circuit when needed while maintaining connection during normal operation.
Solution Approach 2:
The system is pre-configured with the tab terminal positioned close to the pointed edge (3mm or less) before any external load is applied. This preliminary positioning ensures that when an external load occurs, the tab terminal will contact and be pierced by the pointed edge, automatically opening the circuit to prevent high voltage exposure.
2Reliability
If tab terminals are positioned close to pointed edges to enable circuit opening, then safety under external load is improved, but manufacturing precision and assembly difficulty worsen
Solution Approach 1:
The cross-member acts as an intermediary structure that provides a predetermined position for the pointed edge. By fixing the pointed edge to the cross-member and positioning the tab terminal relative to it, the system creates a controlled geometric relationship that simplifies manufacturing and assembly while ensuring the 3mm or less distance requirement is met.
3Weight of moving object
If polymer-based materials are used for cross-member to reduce weight, then weight is reduced, but structural strength and piercing capability worsen
Solution Approach 1:
The cross-member is constructed from polymer-based composite materials that combine the low weight advantage of polymers with the structural strength and piercing capability needed for the pointed edge. This composite material approach allows the cross-member to be lightweight while still enabling the pointed edge to effectively pierce the tab terminal when an external load is applied.
Data Source
AI summary
A battery pack system includes a first tab terminal, a second tab terminal joined to the first tab terminal, and at least one point spaced a distance from the first and second tab terminals. The at least one point is configured to pierce at least the first tab terminal when the first tab terminal and the at least one point are shifted relative to each other such that the at least one point contacts the first tab terminal.