Battery Gas Discharge Valve Notch Geometry for Stable Pressure Venting
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Solution Overview
Problem
Existing battery gas discharge valves are prone to instability due to stress from vibrations or impacts during manufacturing, leading to unreliable activation when internal pressure increases.
Innovation Solution
A battery gas discharge valve design featuring a thin valve body with a track-shaped main notch and an auxiliary notch, where the curvature and thickness ratios are optimized to concentrate stress on the inner corner of the main notch, enhancing resistance to shear stress and ensuring stable activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a track-shaped rupturable groove is provided at the outer peripheral portion of the valve body, then the valve body can be opened to release gas, but cracks are caused at the rupturable groove due to stress from vibration or impact during manufacturing
Solution Approach 1:
The patent applies local quality by creating an asymmetric notch geometry where the inner corner has a small radius of curvature (≤0.05mm) to concentrate stress for reliable activation, while the outer corner has a large radius of curvature (≥0.05mm) to resist stress from vibration and impact during manufacturing. This differential local geometry optimizes each corner for its specific functional requirement.
Solution Approach 2:
The patent changes the geometric parameters of the notch, specifically controlling the radius of curvature at the inner corner (≤0.05mm) and outer corner (≥0.05mm), along with the thickness ratio t2/t1≥0.16. These parameter changes enable the notch to simultaneously achieve stress concentration for activation and resistance to manufacturing-induced stress.
2Reliability
If the curvature of the inner corner is increased to concentrate stress for activation, then the valve activates more reliably, but the resistance to shear stress from vibration or impact is reduced
Solution Approach 1:
The patent employs asymmetry by designing the notch with different radius of curvature values at the inner corner (≤0.05mm) and outer corner (≥0.05mm). This asymmetric geometry allows the inner corner to concentrate stress for reliable activation while the outer corner resists shear stress from vibration and impact, resolving the contradiction between activation reliability and resistance to harmful external factors.
Data Source
AI summary
A valve body of a gas discharge valve includes a substantially annular main notch for opening the valve body and an auxillary notch provided in a region inside the main notch. The main notch and the auxillary notch are coupled to each other at least at one location. At a coupling portion between the main notch and the auxillary notch, the curvature of an inner corner of a bottom portion of the main notch is equal to or less than 0.05, and the curvature of an outer corner of the bottom portion is equal or greater than 0.05. Assuming that the thickness of the valve body at a portion thereof located in the opposite direction of the auxillary notch when viewed from the coupling portion is t1 and the thickness the valve body at a portion thereof located below the bottom portion of the main notch is t2, t2/t1≥0.16 is satisfied.