Battery Vent Assembly With Expanded Metal Flame Arrestor
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Solution Overview
Problem
Existing vent assemblies for rechargeable battery packs do not effectively mitigate thermal runaway events, as they fail to manage heat, flames, and explosive particles generated during catastrophic failures, potentially leading to uncontrolled fires and explosions.
Innovation Solution
A novel vent assembly incorporating a Directional Flow Expanded Metal (DFEM) and Variable Expanded Metal (VEM) filter element acts as a heat sink, particulate filter, and flame arrestor, utilizing a multilayer cylindrical or flat design to create a tortuous path for gases and particles, effectively cooling and trapping flames and debris within milliseconds, while allowing cooled air to escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing vent assemblies are used to provide pressure equalization and gas venting, then pressure relief is achieved, but protection from heat, flame, and projectiles is not provided
Solution Approach 1:
The vent assembly is divided into multiple functional layers: a first expanded metal layer with larger openings for pressure relief and heat dissipation, and a second expanded metal layer with smaller openings for particle filtration and flame arrestment. This segmentation allows each layer to specialize in specific protective functions, achieving comprehensive thermal runaway mitigation while maintaining pressure equalization capabilities.
2Speed
If vent openings are made larger to improve pressure relief, then gas escape is enhanced, but flame and particle propagation risk increases
Solution Approach 1:
The solution transitions from a single-layer vent design to a multi-layer expanded metal structure. The first layer with larger openings handles gas escape in one dimension, while the second layer with smaller openings provides flame arrestment in another dimension. This dimensional approach allows simultaneous optimization of both gas escape speed and flame propagation prevention.
3Device complexity
If a single-layer filter design is used, then device complexity is reduced, but effectiveness in cooling and trapping flames is insufficient
Solution Approach 1:
The vent assembly employs a nested dual-layer structure where the second expanded metal layer is positioned within or adjacent to the first layer. This nesting arrangement maximizes the cooling surface area and flame path length within a compact structure, enhancing temperature reduction effectiveness while maintaining relatively simple overall device 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 solution significantly reduces the temperature of escaping air by up to 90% in less than a second, effectively preventing the propagation of flames and particles outside the battery, thereby mitigating thermal runaway events and ensuring safety.
Implementation Method 1
the filter element is formed as a multilayer cylindrical collar... the filter element acts as a heat sink to cool and overheating battery
Implementation Method 2
The fins and holes are offset from layer to layer within the wrap of the collar filter and are designed to immediately spin the flames and burning particles into a 90 degree pathway
Implementation Method 3
the vent assembly acts as a particulate filter and flame arrestor which prevents and/or reduces flames and particulate slag projectiles from being expelled outside an individual cell or bank of cells in a battery
Data Source
AI summary
A battery exhaust vent includes an expanded metal filter which acts as a heat sink to cool an overheating battery. The exhaust vent acts as a particulate filter and flame arrestor which reduces flames and particulate slag projectiles from being expelled outside a battery housing. Directional Flow Expanded Metal (DFEM) and Variable Expanded Metal (VEM) are utilized for their directional fins and associated plethora of openings offset in overlapping layers to create a cyclone effect for gases or particles passing through the filter. The fins and holes are offset from layer to layer within a multi-layer filter construction and are designed to immediately change the direction of the flames and burning particles relative to the input flame flow direction. The vent may include an elastomeric umbrella valve which seals the vent from external airflow but allows quick venting for internal gas pressure during a runaway event or excessive heating.