Cylindrical Battery Vent Structure for Stable CID and Vent Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing welding methods for cylindrical batteries, such as metal diffusion welding, can cause significant warpage of the vent member in the sealing assembly, leading to unstable actuation pressure of the current interrupt device (CID) and vent pressure, which may result in functional loss of the sealing assembly.
Innovation Solution
A cylindrical battery design where the vent member includes a vent at its center that deforms upward when internal pressure increases, causing separation from the terminal plate, and an outer circumferential portion that is fixed to the outer housing can by caulking. The lower face positions of the vent and the outer circumferential portion are arranged on the same plane to reduce warpage during welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal diffusion welding is used to connect the vent member to the terminal plate, then welding strength and electrical conductivity are improved, but the vent member undergoes significant warpage causing unstable CID actuation pressure and vent pressure
Solution Approach 1:
The vent member is divided into three distinct regions: a vent portion at the center, an intermediate portion, and an outer circumferential portion. This segmentation allows each region to have different functional characteristics - the vent portion can deform under pressure while the outer circumferential portion maintains flatness for stable welding, thus resolving the contradiction between welding strength and manufacturing precision.
Solution Approach 2:
Different portions of the vent member are designed with different properties: the vent portion is designed to deform upward under internal pressure, while the outer circumferential portion is designed to remain flat and stable for welding. This local differentiation of properties allows the vent member to simultaneously achieve stable welding (through flat outer portion) and proper pressure response (through deformable vent portion).
2Reliability
If the vent member is designed to deform upward under internal pressure, then the CID actuation function is improved, but warpage occurs during welding causing unstable actuation pressure and vent pressure
Solution Approach 1:
By segmenting the vent member into functional zones (vent portion, intermediate portion, outer circumferential portion), the design allows the vent portion to deform upward for reliable CID actuation while the outer circumferential portion maintains stability for consistent welding. This segmentation prevents unwanted warpage that would otherwise cause unstable actuation pressure and vent pressure.
Solution Approach 2:
The vent member exhibits local quality differentiation where the vent portion has deformability for reliable CID actuation, while the outer circumferential portion has structural stability for precise welding. This localized property assignment ensures both reliable safety function and stable manufacturing characteristics.
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
This design effectively reduces warpage of the vent member during metal diffusion welding, thereby stabilizing the actuation pressure of the CID and vent pressure, and preventing functional loss of the sealing assembly.
Implementation Method 1
a vent member (26) including a vent (26a) at a center that is deformed upward of the battery when an internal pressure of the battery increases
Implementation Method 2
an outer circumferential portion (26b) that is fixed to an opening of the outer housing can (16) by caulking
Implementation Method 3
the welding method by metal diffusion welding using high frequency vibration like wire bonding
Data Source
AI summary
A cylindrical battery comprises: a housing canister that has a bottomed cylindrical shape and that accommodates an electrode; and a sealing body that seals an opening of the housing canister. The sealing body includes a valve body and a terminal plate. The valve body includes: a central valve-section that, when the internal pressure of the battery rises, deforms upward relative to the battery so as to separate from the terminal plate; and an outer-circumferential section that is crimped and fixed to the opening of the housing canister. The position of the bottom surface of the valve section and the position of the bottom surface of the outer-circumferential section are disposed on the same plane.