Resin Safety Valve Sealing for Controlled Battery Venting
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Solution Overview
Problem
Existing sealed battery designs face limitations in forming safety valves integrated with metal lid members, particularly in terms of thickness and material, making it difficult to address a wide variety of batteries, and there is a need for a resin safety valve member that can open when internal pressure reaches a predetermined valve opening pressure.
Innovation Solution
A sealed battery design featuring a metal wall portion with a gas vent hole sealed by a resin safety valve member, where the resin safety valve includes an annular joined portion that breaks to open and release pressure, enhancing hermeticity through an annular roughened surface and potentially integrated via insert molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a safety valve is integrated with the lid member by press-molding from an aluminum plate, then the safety valve can be formed simultaneously with the lid member, but this method has limitations on the thickness and material of the metal plate, making it difficult to address a wide variety of sealed batteries
Solution Approach 1:
The safety valve is separated from the lid member into an independent component. The lid member has a gas vent hole formed therein, and the safety valve member is a separate resin component that closes the gas vent hole by covering an annular hole-surrounding surface. This segmentation allows the lid member to be made from various materials and thicknesses without being constrained by press-molding requirements, while the safety valve member can be independently manufactured from resin materials.
2Adaptability or versatility
If the safety valve is made from a separate resin member instead of being integrated with the metal lid, then the battery case can accommodate various materials and thicknesses, but ensuring hermetic sealing between the resin safety valve member and metal wall portion becomes challenging
Solution Approach 1:
An annular protrusion is formed on the hole-surrounding surface of the metal wall portion before the safety valve member is attached. This protrusion serves as a pre-prepared sealing structure that the resin safety valve member can fit onto. The protrusion creates a mechanical interlock and sealing interface that ensures hermetic sealing between the resin member and metal portion, addressing the sealing challenge before assembly occurs.
Solution Approach 2:
The solution combines different materials (metal lid member and resin safety valve member) in a composite structure. The metal lid member provides structural strength and gas vent hole formation, while the resin safety valve member provides the closing function. The annular protrusion on the metal surface creates a bonding interface that enables hermetic sealing between the dissimilar materials.
3Measurement precision
If the annular joined portion is designed to break at a specific pressure, then the valve opening pressure can be accurately controlled, but the joined portion must be sufficiently strong to maintain hermeticity below that pressure
Solution Approach 1:
The annular joined portion has non-uniform thickness distribution, with a thinner portion specifically located at the position where breaking should occur. This local variation in quality allows the joined portion to maintain sufficient overall strength for hermetic sealing while having a specific weak point that will break at the predetermined pressure, enabling accurate valve opening pressure control.
Solution Approach 2:
The annular protrusion is formed on the metal wall portion before the safety valve member is attached, creating a pre-determined breaking structure. The protrusion's geometry is designed in advance to create a controlled weak point in the joined portion, ensuring that when internal pressure reaches the valve opening pressure, the joined portion breaks at the predetermined location rather than randomly.
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 resin safety valve member effectively opens to release pressure when internal pressure reaches the valve opening pressure, maintaining hermeticity and preventing excessive pressure rise, while allowing for easy production and accurate setting of the valve opening pressure.
Implementation Method 1
when the internal pressure of the battery case reaches a valve opening pressure, the annular joined portion breaks, or ruptures, thus opening the resin safety valve member
Implementation Method 2
the annular joined portion hermetically joined to the annular seal surface, and the annular seal surface is an annular roughened surface
Data Source
AI summary
In a sealed battery, a battery case includes a metal wall portion formed with a gas vent hole. Of an outer surface of the metal wall portion, a hole-surrounding annular surface surrounding an opening edge of the gas vent hole includes an annular seal surface surrounding the opening edge of the gas vent hole. A resin safety valve member covering and closing the the gas vent hole includes an annular joined portion hermetically joined to the annular seal surface. The annular joined portion of the resin safety valve breaks when the internal pressure of the battery case reaches a valve opening pressure, thereby opening the resin safety valve member.