Battery Pack Pressure Equalization Venting With Flow Restriction
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Solution Overview
Problem
High-voltage traction battery packs in electrified vehicles face challenges in pressure equalization during normal operations and controlled release of battery vent byproducts during thermal events, which can disrupt the integrity of the pressure equalization device.
Innovation Solution
A pressure equalization device within the enclosure assembly, featuring a housing assembly with a flow restrictor and a water-impermeable membrane, restricts flow from 78 to 88 percent, preventing excessive vent byproducts from exiting through the membrane during thermal events, while allowing pressure equalization during normal operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure equalization device allows free flow during thermal events, then pressure equalization is effective, but excessive vent byproducts disrupt the device integrity
Solution Approach 1:
A flow restrictor is introduced as an intermediary component between the pressure equalization device and the external environment. This flow restrictor limits the amount of vent byproducts that can reach the membrane during thermal events, protecting the membrane from disruption while still allowing pressure equalization to occur. The flow restrictor acts as a mediator that balances pressure management needs with membrane protection requirements.
2Reliability
If the flow restrictor is positioned inside the enclosure assembly, then it effectively controls flow, but it occupies internal space and complicates assembly
Solution Approach 1:
The flow restrictor is extracted from the internal components of the pressure equalization device and repositioned on the external surface of the enclosure assembly. This extraction simplifies the internal assembly by removing a complex component from the battery pack interior, while still maintaining effective flow control functionality on the exterior where it can manage vent byproducts without interfering with internal battery components.
3Object-affected harmful factors
If the opening diameter is reduced to restrict flow, then vent byproduct release is controlled, but pressure equalization efficiency decreases
Solution Approach 1:
The pressure equalization device incorporates multiple openings of different sizes and configurations to create local quality variations. Some openings are larger to maintain pressure equalization efficiency, while others are smaller or positioned strategically to control vent byproduct release. This localized differentiation allows the device to simultaneously achieve both pressure management and vent byproduct control without sacrificing overall productivity.
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 manages pressure within the battery pack during normal operations and throttles the release of vent byproducts during thermal events, maintaining the integrity of the pressure equalization device and ensuring controlled venting.
Implementation Method 1
a flow restrictor configured to restrict flow through the housing assembly during a battery thermal event of the traction battery pack
Implementation Method 2
a water-impermeable membrane held within the housing assembly and covering the outlet
Data Source
AI summary
A traction battery pack includes an enclosure assembly; and a pressure equalization device received within a wall of the enclosure assembly. The pressure equalization device includes a housing assembly and a flow restrictor configured to restrict flow through the housing assembly during a battery thermal event of the traction battery pack.