Battery Vent Flap Assembly for eVTOL Thermal Runaway Venting
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Solution Overview
Problem
Electric vertical take-off and landing (eVTOL) aircraft face challenges in safely managing thermal runaway in battery cells, which can lead to uncontrolled heat and gas release, posing risks to the aircraft and its occupants.
Innovation Solution
A mechanical support layer with integrated vent flaps is attached to the battery assembly, allowing the vent flaps to deform and release gas safely, preventing pressure buildup and protecting adjacent cells from heat and ejecta during thermal runaway events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If battery cells are sealed to prevent gas release, then structural integrity is improved, but thermal runaway risk increases due to pressure buildup
Solution Approach 1:
Vent flaps are pre-positioned and pre-sized to open at specific pressure thresholds during thermal runaway events. The mechanical support layer is pre-configured with recesses that hold the vent flaps in place during normal operation, ready to deform and vent when pressure builds up from gas generation in battery cells.
Solution Approach 2:
The vent flap assembly acts as an intermediary between the sealed battery cell environment and the external atmosphere. The mechanical support layer with integrated vent flaps serves as a pressure-regulating interface that maintains structural integrity while allowing controlled gas release, preventing both uncontrolled rupture and dangerous pressure buildup.
2Strength
If vent flaps are made rigid to maintain structural integrity, then mechanical strength is improved, but gas flow capability deteriorates due to deformation resistance
Solution Approach 1:
The vent flaps exhibit spatially varying mechanical properties: they are anchored to the mechanical support layer at specific locations to maintain structural integrity, while having deformable portions that can flex and open under pressure to release gas. The local quality transitions from rigid (at anchors) to flexible (at deformable portions) to simultaneously satisfy both structural and venting requirements.
Solution Approach 2:
The vent flaps transition from a static, rigid state during normal operation to a dynamic, deformable state during thermal runaway events. The mechanical support layer with integrated vent flaps is designed to remain structurally sound under normal conditions but automatically deform to permit gas flow when pressure thresholds are exceeded, adapting its mechanical properties in response to operating conditions.
3Reliability
If battery cells are isolated to prevent thermal runaway propagation, then cell safety is improved, but heat dissipation capability deteriorates
Solution Approach 1:
The battery assembly is segmented into individual cell compartments with isolated venting paths. Each battery cell has its own vent flap that can open independently, allowing thermal runaway to be contained to individual cells while maintaining proper heat dissipation through controlled venting of each cell's thermal byproducts separately.
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 effectively vents gases and reduces the risk of cell damage, ensuring safe operation and minimizing the risk of propagation of thermal runaway, thereby enhancing safety and reliability in eVTOL aircraft.
Implementation Method 1
Each vent flap includes one or more portions configured to deform to permit flow of gas from the battery cell corresponding to the vent flap
Data Source
AI summary
This disclosure relates generally to high voltage power supply (HVPS) systems and battery assemblies for aircraft that use electrical propulsion systems. In one embodiment, an apparatus for safely venting battery cells in thermal runaway is provided. The apparatus includes: a mechanical support layer, the mechanical support layer configured to be attached to a battery assembly; and a vent flap layer attached to the mechanical support layer, the vent flap layer including vent flaps corresponding to battery cells in the battery assembly. Each vent flap includes one or more portions configured to deform to permit flow of gas from the battery cell corresponding to the vent flap.