Two-Piece Fuse Endbell Assembly for Clean Sealed Attachment

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Solution Overview

Problem

Existing fuse technologies face manufacturing complexity and quality deviations due to the need for secondary processes like soldering or welding to attach fuse elements between two terminals, and the assembly method does not ensure a sealed envelope between the fuse contents and the environment, leading to potential contamination and operational issues.

Innovation Solution

A two-piece endbell design with crush ribs and slots instead of cylindrical holes, allowing for secure attachment of the terminal assembly without adhesives and providing a sealed envelope, simplifying manufacturing and reducing contamination risks by eliminating the need for drilling and using pre-molded alignment slots for insertion pins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional endbells are secured to the fuse body using insertion pins requiring drilling holes, then the endbells can be attached to the fuse body, but contaminants are left inside the fuse body resulting in messy assembly and potential sealing issues

Engineering Contradiction:
Improveendbell attachment processVSAvoidcontamination inside fuse body
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The endbell is divided into two separate portions (first endbell portion and second endbell portion) that are fastened to opposite ends of the terminal assembly. This segmentation eliminates the need for drilling holes through the entire endbell structure, thereby preventing contaminant introduction while maintaining secure attachment capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first and second insertion pins are pre-positioned in the first and second insertion pin slots respectively before the two endbell portions are fastened together. This preliminary positioning ensures proper alignment and secure attachment without requiring post-assembly drilling operations that would introduce contaminants.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If adhesive materials are used to seal endbells to the fuse body, then sealing can be achieved, but the adhesive application is messy and complicates the manufacturing process

Engineering Contradiction:
Improvesealing of endbells to fuse bodyVSAvoidsealing process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The sealing function is extracted from the adhesive material and implemented through the structural design of the two-piece endbell assembly with pre-positioned insertion pins. The mechanical interlocking and sealing surfaces of the endbell portions provide the sealing action without requiring separate adhesive application, eliminating messiness and process complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If fully circular endbells are used with secondary attachment processes like soldering or welding, then the fuse element can be attached between terminals, but the manufacturing complexity increases and quality deviation risks arise

Engineering Contradiction:
Improvefuse element attachmentVSAvoidmanufacturing process complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The terminal assembly with fuse element is integrated as a single unit between the two endbell portions. The first and second terminals are disposed at opposite ends of the fuse element, and the endbell portions are fastened to secure this integrated assembly, eliminating the need for separate secondary attachment processes like soldering or welding.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4095880B1Two-piece fuse endbell with interface crush ribs
Publication Date: 2024.12.11 LITTELFUSE INC
  • EP4095880B1 patent drawingFigure 1
  • EP4095880B1 patent drawingFigure 2A
  • EP4095880B1 patent drawingFigure 2B

AI summary

A novel fuse assembly design utilizes single-piece terminal assemblies and two-piece endbells. The two-piece endbells and terminal assembly feature mating elements that enable fastening of the endbell portions to the terminal assembly without use of adhesives. The mating elements also provide positioning guidance for ease of assembly. Slots in the endbells for receipt of insertion pins enable the endbells to be pre-cast/pre-molded without costly rework of molding tools.