Rail Battery Container Safety Fitting for Thermal Runaway Venting
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Solution Overview
Problem
Existing battery containers for rail vehicles fail to meet safety standards during thermal runaway of lithium-ion batteries, as they burst due to sudden pressure increases, and known rupture discs do not provide adequate fire protection or prevent re-ignition.
Innovation Solution
A battery container with a safety fitting that diverts fluids and gas from the inner space upon exceeding a presettable response pressure, while automatically sealing again when pressure falls below a presettable closing pressure, thus preventing pressure buildup and re-ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a rupture disc made of thin metal foils is used to enable pressure balance, then the inner pressure can be released, but the fire protection properties required in the rail sector are not met and fresh air penetration intensifies battery fire
Solution Approach 1:
The patent employs an inerting system that introduces inert gas (such as nitrogen or carbon dioxide) into the battery container to displace oxygen and create a non-combustible atmosphere. This prevents fire propagation even when the safety fitting opens, as the inert gas environment cannot support combustion of battery materials or released substances.
Solution Approach 2:
The safety fitting acts as an intermediary component that mediates between pressure relief needs and fire protection requirements. It is designed with integrated fire-resistant materials and coordinated with the inerting system to ensure that pressure relief occurs without compromising fire safety, unlike simple rupture discs that directly expose the interior to external air.
2Stress or pressure
If a liquid impermeable but gas permeable membrane is used for continuous pressure balance, then gas can be discharged, but the sudden inner pressure in case of thermal runaway cannot be evacuated and the membrane is destroyed
Solution Approach 1:
The safety fitting is designed as a dynamic pressure relief system that transitions from a closed state to an open state based on pressure conditions. It features a resilient closure element that can deform and open under high pressure loads (such as thermal runaway conditions) while maintaining sealing under normal operating pressures, adapting its properties to the operational demands.
Solution Approach 2:
The system changes the pressure parameter threshold for opening the safety fitting. Unlike membranes with fixed permeability, the safety fitting remains closed under normal gas pressure but opens automatically when pressure exceeds a predetermined threshold (such as during thermal runaway), allowing sudden pressure equalization without membrane destruction.
3Stress or pressure
If the safety fitting opens to discharge gas, then pressure balance is achieved, but the casing must remain open to maintain pressure balance, preventing fluid-tight sealing
Solution Approach 1:
The safety fitting operates periodically rather than continuously - it opens briefly when pressure exceeds the threshold to relieve overpressure, then closes automatically to restore fluid-tight sealing. This periodic opening-closing action maintains pressure balance when needed while preserving sealing integrity during normal operation, unlike systems that must remain permanently open.
Solution Approach 2:
The safety fitting is designed with self-actuating mechanisms including resilient closure elements and pressure-activated opening features that automatically respond to pressure conditions without external control. The fitting opens itself when pressure exceeds the threshold and closes itself when pressure normalizes, providing autonomous pressure management while maintaining sealing.
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 safety fitting effectively manages pressure and prevents fires by automatically discharging gas and re-sealing the container, reducing the risk of damage and health hazards.
Implementation Method 1
the safety fitting is designed to divert at least one fluid from the inner space of the casing in case of exceeding a presettable response pressure
Implementation Method 2
the safety fitting is designed to divert at least one fluid from the inner space of the casing in case of exceeding a presettable response pressure and to fluid-tightly seal the casing on falling below a presettable closing pressure
Data Source
AI summary
A battery container for rail vehicles, in particular railways and tramways, comprises a casing that provides an inner space for housing lithium-ion batteries. The casing includes a safety fitting that is designed to divert at least one fluid from the inner space of the casing in case of exceeding a presettable actuation pressure and to fluid-tightly seal the casing on falling below a presettable closing pressure.