Button Cell Without Flanging Using Double-Walled Cover Notch

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Solution Overview

Problem

Existing button cells face challenges in achieving optimized capacity and ease of assembly while maintaining a liquid-tight seal, often requiring complex flanging tools and being prone to damage during assembly.

Innovation Solution

A button cell design featuring a cell cup and cell cover connected via a foil seal with a single-walled section and a circumferential double-walled opening edge, utilizing a radially bent cut edge and a circumferential notch for positive fit without beading, and a seal that encloses the opening edge and covers the cell cover casing for enhanced stability and visibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If classic flanging with beaded cup edge is used, then liquid-tight seal is achieved, but assembly complexity increases and damage risk occurs

Engineering Contradiction:
Improveliquid-tight sealVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the flanging process and beaded cup edge from the button cell construction. Instead of deforming the cup edge to overlap the cover, the patent uses a simple force-fit connection where the cup edge directly engages with the cover opening, removing the complex flanging tools and steps while maintaining sealing through an elastomeric seal ring.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces an elastomeric seal ring as an intermediary element between the cup and cover. This seal ring provides the liquid-tight barrier function that previously required complex flanging, while the force-fit mechanical connection handles the structural joining, separating the sealing function from the complex deformation process.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Quantity of substance

If foil seals are used, then capacity is optimized, but seal visibility and color coding are reduced

Engineering Contradiction:
Improvecell capacityVSAvoidseal visibility
Core Design Contradiction:
Quantity of substanceVSLoss of information

Solution Approach 1:

The invention uses a composite sealing system combining a thin elastomeric seal ring for sealing function with an optional outer seal cover or visible seal element. The elastomeric ring provides the actual liquid-tight barrier optimized for capacity, while the outer visible element provides color coding and visual indication, combining both requirements in a composite structure.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP2729975B1Button cell without flanging
Publication Date: 2018.01.10 VARTA MICROBATTERY GMBH
  • EP2729975B1 patent drawingFigure 1~2

AI summary

The invention relates to a button cell comprising a liquid-proof closed housing consisting of a cell beaker, which comprises a bottom, a peripheral jacket, a transition area connecting the bottom and the jacket, and a terminal cutting edge, a cell cap which comprises a bottom, a peripheral jacket, a transition area connecting the bottom and the jacket, and a terminal cutting edge, and of a sealing element, wherein the cell cap, with the cutting edge forward, is inserted into the cell beaker, and the sealing element is arranged between the cell beaker and the cell cap in such a manner that it insulates the latter two from each other. The button cell is characterized in particular in that the jacket of the cell cap is subdivided into a single wall section and an adjacent peripheral double-walled opening margin having a U-shaped cross section, which is formed by radial bending of the cutting edge of the cell cap outward, and the jacket of the cell cap comprises immediately beneath the double-walled opening margin a peripheral notch in which the outer diameter thereof has a minimum and the jacket of the cell beaker has a peripheral nose which is formed by radial pulling in, and which engages in said notch. The invention further relates to a method for producing such a button cell.