Battery Pack Cover Interference Fitting for ESD Protection
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Solution Overview
Problem
Existing battery packs face challenges in maintaining stable electrical connections and protecting against electrostatic discharge (ESD) for extended operation, particularly in multi-cell configurations where external factors can damage components.
Innovation Solution
A battery pack design incorporating a protective circuit module with a substrate, a lower frame and cover featuring a protrusion and groove structure with specific height ratios, and an electrical insulator, which secures the cover to the frame via interference fitting, elongating ESD penetration paths and enhancing coupling force, thereby protecting internal components from damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cover and lower frame are coupled using conventional methods, then assembly is simple, but the coupling force is insufficient and ESD penetration paths are short
Solution Approach 1:
The protrusion incorporates an uneven surface with curved contours rather than flat surfaces, creating interference fit geometry that increases coupling force through friction and mechanical interlocking, while the grooves provide curved ESD penetration paths
Solution Approach 2:
The design adds vertical dimension to ESD protection by creating multi-level grooves that extend through different depths, forcing ESD to traverse three-dimensional paths rather than straight lines, thereby elongating the penetration path without significantly increasing overall device dimensions
2Object-affected harmful factors
If the ESD penetration path is elongated, then protection against ESD is improved, but the device dimensions increase
Solution Approach 1:
Multiple grooves are nested within each other at different levels and positions, creating a multi-layered ESD barrier system where ESD must pass through successive grooves, effectively increasing protection without proportionally increasing external dimensions
Solution Approach 2:
The uneven surface features and grooves are concentrated specifically at the interface between cover and lower frame where ESD entry is most likely, providing localized ESD protection exactly where needed rather than uniformly throughout the entire device structure
3Strength
If interference fitting is used to secure the protrusion in the groove, then coupling force is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The uneven surface of the protrusion creates variable contact points and friction characteristics along the interface, allowing the interference fit to accommodate normal manufacturing variations while maintaining sufficient coupling force through the cumulative effect of multiple contact zones
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 design effectively prevents ESD damage to the protective devices, ensuring stable operation and extended battery life by elongating ESD penetration paths and increasing the coupling force between the cover and frame, as demonstrated by successful ESD tests at ±6 kV and ±8 kV.
Implementation Method 1
The protrusion is placed in the groove and secured therein by interference fitting
Implementation Method 2
elongating ESD penetration paths and enhancing coupling force, thereby protecting internal components from damage
Data Source
AI summary
A battery pack is disclosed. In one aspect, the battery pack includes a battery cell and a protective circuit module electrically connected to the battery cell. The protective circuit module includes a substrate and a protective device mounted on the substrate. The battery pack also includes a lower frame including an accommodation space for the battery cell and the protective circuit module and a cover coupled to the lower frame and covering at least a portion of the protective circuit module. The cover includes a protrusion protruding the lower frame and having an uneven surface and the lower frame includes a groove. The protrusion is placed in the groove and secured therein by interference fitting.