Segmented Membrane Vent for Reclosable Low-Pressure Battery Degassing
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Solution Overview
Problem
Existing degassing units for electronics cases, particularly battery cases, have high opening pressures due to material limitations, making them non-reclosable and inefficient for emergency venting, especially in high-voltage storage devices like traction batteries.
Innovation Solution
A degassing unit with a segmented membrane and support ribs that allows for a low opening pressure of up to 50 mbar, enabling rapid gas release while maintaining a sealed state, using a single impermeable membrane with segmentation lines and convex shape for enhanced sealing and elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional PTFE membrane is used for emergency venting, then the membrane can provide pressure compensation and gas release, but the opening pressure is high (150-300 mbar) and the membrane cannot be closed again after bursting
Solution Approach 1:
The membrane is divided into multiple segments by radial segmentation lines extending from the center to the outer rim. These segments can move independently relative to each other, allowing the membrane to open at low pressure by segment separation while maintaining structural integrity. The segmentation enables the membrane to flex and open without requiring high bursting pressure.
Solution Approach 2:
The membrane transitions from a static, rigid structure to a dynamic, flexible system where segments can move relative to each other. The segmentation lines create flexible joints that allow the membrane to deform and open under low pressure differential, then return to its closed position when pressure equalizes, enabling reclosable emergency venting.
2Stress or pressure
If the membrane is made more flexible to reduce opening pressure, then low pressure venting is achieved, but the membrane may deform excessively or fail to seal properly
Solution Approach 1:
The segmented structure allows controlled flexibility at the segmentation lines while maintaining rigidity in the membrane segments themselves. This enables the membrane to open at low pressure through segment separation while the segments retain enough structural integrity to seal properly when closed.
Solution Approach 2:
The membrane combines materials with different properties: the membrane segments provide structural integrity and sealing capability, while the segmentation lines provide flexibility and low-pressure opening. This composite structure achieves both low opening pressure and reliable sealing function.
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 allows for efficient and cost-effective emergency venting with a low opening pressure, ensuring the case remains sealed during normal conditions and prevents external contamination, while being easily manufacturable and robust.
Implementation Method 1
If the internal pressure of the case exceeds the external pressure, the segments of the membrane move away from each other. Thus, the degassing unit opens. Gas from inside the case may escape to the environment.
Implementation Method 2
In an unloaded state of the degassing membrane, i.e. if an outside pressure of the case equals its internal pressure, the segments of the membrane contact each other along the segmentation line, i.e. the segmentation line has vanishing width. Thereby, the degassing unit is closed. Basically, gas flow in either direction through the degassing opening is prevented by the closed membrane.
Implementation Method 3
If the external pressure exceeds the internal pressure of the membrane, the membrane is pressed towards the support rib. If the external pressure is sufficiently high, the membrane will contact the support rib. This inward deformation of the membrane causes the segments of the membrane to be pressed against each other. This increases the sealing effect between adjacent segments.
Data Source
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AI summary
The invention refers to a degassing unit (30) for an electronics case, in particular for a battery case, comprising a base body (32), which is attachable to the case so as to seal against a perimeter of an aperture in the case, the base body (32) comprising a degassing opening (38), and a single membrane (44), which covers the degassing opening (38) of the base body (32), wherein at least one segmentation line (46) penetrates through the membrane (44), and wherein at least one support rib (40) is provided for abutment of adjacent segments (48a-48d) of the membrane (44) along the segmentation line (46).