Cylindrical Battery Case Reduced-Diameter Step Design
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Solution Overview
Problem
Conventional battery case bodies deform during the diameter reducing process due to uneven rigidity, where the closed end is more rigid and less likely to be reduced in diameter, causing external forces to be transmitted to the side wall portion and leading to deformation.
Innovation Solution
A cylindrical case with a reduced-diameter portion formed at the closed end, where the dimension of this portion is equal to or greater than the thickness of the closed end, and a step formed between the outer surface and the reduced-diameter portion to distribute pressing forces, thereby suppressing deformation and maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the closed portion of the case body has higher rigidity than the side wall portion, then the closed portion is less likely to be reduced in diameter, but the external force is transmitted to the side wall portion causing deformation
Solution Approach 1:
The patent applies local quality by creating a reduced-diameter portion with a specific outer diameter smaller than the main body of the case. This localized structural modification concentrates the diameter reduction effect at a specific location (the closed end) rather than uniformly across the entire case, allowing the side wall portion to maintain its original dimensions while the closed end achieves the required reduced diameter.
Solution Approach 2:
The case body is segmented into distinct portions: a main body portion with a first outer diameter and a reduced-diameter portion at the closed end with a second outer diameter smaller than the first. This segmentation allows different portions of the case to have different functional characteristics, with the reduced-diameter portion specifically designed to receive pressing forces during manufacturing while the main body maintains structural integrity.
2Stability of the object's composition
If the closed portion has higher rigidity, then it maintains structural integrity, but it resists diameter reduction and transmits force to weaker areas
Solution Approach 1:
The reduced-diameter portion creates a localized zone at the closed end that is specifically designed to be more compliant. This local structural variation allows the closed end to absorb pressing forces during manufacturing processes without transmitting excessive stress to the side wall portion, while the rest of the case maintains its structural integrity.
Solution Approach 2:
The reduced-diameter portion acts as a pre-designed stress-absorbing feature that cushions the closed end against pressing forces applied during manufacturing. By anticipating the force application during diameter reduction processes, the design incorporates this compliant zone in advance to prevent force transmission to the side wall portion.
Data Source
AI summary
An energy storage device including: a cylindrical case having at least one end closed; and an electrode assembly housed in the case. A reduced-diameter portion, at which an outer diameter of the case is reduced, is formed at the closed end of the case.