Shape-Memory Battery Ejection Latch for Thermal Runaway
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Solution Overview
Problem
Lithium ion batteries in electric vehicles are prone to thermal runaway, which can spread to other cells and cause damage to the battery pack and vehicle, necessitating a safe and automatic ejection mechanism.
Innovation Solution
A housing with a latch and biasing member made of shape memory material that transitions states at a threshold temperature, automatically opening to eject the battery, utilizing Nitinol's shape memory properties to ensure safe removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery is retained in the housing during normal operation, then the battery is securely held and protected, but the battery cannot be automatically removed in case of thermal runaway
Solution Approach 1:
The latch mechanism utilizes temperature-dependent parameter changes in shape memory material. At normal temperatures, the material maintains a first shape that secures the latch in the closed position for reliable battery retention. When thermal runaway occurs and temperature exceeds the threshold, the material transitions to a second shape that automatically releases the latch, enabling easy battery ejection without manual intervention.
Solution Approach 2:
The system implements self-service through the temperature-responsive latch that automatically detects thermal runaway conditions and triggers ejection without external control. The shape memory material self-activates based on temperature changes, and the biasing member self-propels the battery outward once the latch releases, making the entire ejection process autonomous.
2Strength
If a latch mechanism is used to secure the battery, then the battery is held firmly in place, but the latch must be released to allow ejection
Solution Approach 1:
The patent replaces complex mechanical release mechanisms with a temperature-responsive shape memory material system. Instead of using motors, solenoids, or manual release levers, the latch utilizes the inherent phase transition properties of shape memory material to automatically change its locking characteristics based on temperature, significantly simplifying the device architecture.
Solution Approach 2:
The latch incorporates shape memory material, which is a composite material exhibiting unique thermomechanical properties. This material combines elastic deformation capabilities with temperature-triggered shape recovery, allowing the latch to maintain strong holding force at low temperatures while automatically releasing at high temperatures without requiring additional mechanical components.
3Speed
If a biasing member is used to urge the battery out, then rapid ejection is achieved, but the biasing member must be contained until ejection is needed
Solution Approach 1:
The biasing member is merged with the latch assembly rather than being a separate contained component. The biasing member is positioned to act directly on the battery through the latch mechanism, eliminating the need for separate containment structures. This integration maintains compact design while enabling rapid ejection when the latch releases.
Solution Approach 2:
The biasing member is pre-loaded in a compressed or tensioned state during normal operation, storing potential energy ready for immediate release. When thermal runaway occurs and the latch releases, the pre-loaded biasing member instantly propels the battery outward at high speed, achieving rapid ejection without requiring active actuation during the ejection event.
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 system effectively prevents damage by automatically ejecting batteries at high temperatures, enhancing safety and ease of handling for professionals.
Implementation Method 1
At least one of the latch and the biasing member comprises a shape memory material that is in a first state when a temperature of the battery is below a threshold temperature. The shape memory material transitions to a second state when the temperature of the battery exceeds the threshold temperature.
Implementation Method 2
A biasing member is configured to apply a force onto a battery in the housing to urge the battery out of the housing.
Data Source
AI summary
A vehicle battery retention and ejection system includes a housing having a portion that closes an opening of the housing. A latch secures the portion of the housing in a closed position when the latch is in a first condition and allows the portion of the housing to open when the latch is in a second, different condition. A biasing member, such as a spring, applies a force onto a battery in the housing to urge the battery out of the housing. The latch, the biasing member, or both comprises a shape memory material. The shape memory material transitions to a different state when the temperature of the battery exceeds a threshold temperature. As a result, the latch transitions from the first condition to the second condition so the portion of the housing moves into the open position and the biasing member forces the battery out of the housing.