Integrated Fuse Disconnect Switch with Insulator

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Solution Overview

Problem

Existing circuit protection systems face challenges with high current fuses requiring additional holders, wires, and connections, leading to increased size, cost, and complexity, and are prone to short circuits due to direct electrical contact between the ring terminal and post, which complicates installation and reliability.

Innovation Solution

A mechanical disconnect switch integrated with a fuse assembly featuring a post arrangement and a glass mat washer insulator to prevent short circuits and allow secure torque application, eliminating unnecessary components and ensuring correct electrical paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high current fuses are positioned close to relays and battery disconnect switches, then circuit protection is improved, but size, cost and complexity increase due to additional holders, wires and connections

Engineering Contradiction:
Improvecircuit protectionVSAvoidholders, wires and connections
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the fuse and disconnect switch into a single integrated assembly, eliminating the need for separate holders, wires and connections. The fuse is positioned directly within the disconnect switch housing, creating a unified component that provides both circuit protection and disconnect functionality without requiring additional mounting hardware or wiring.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated assembly performs multiple functions simultaneously: the fuse provides overcurrent protection while the disconnect switch provides circuit isolation capability. This multi-functional design consolidates what would traditionally require separate components into a single unit, reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of operation

If direct electrical contact is made between ring terminal and post, then electrical connection is simplified, but short circuits occur compromising reliability

Engineering Contradiction:
Improveelectrical connectionVSAvoidshort circuit prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces an insulator as an intermediary component between the ring terminal and the post. This insulator provides the necessary electrical isolation to prevent short circuits while still allowing mechanical mounting and secure connection. The insulator mediates between the need for electrical connection and the need for short circuit prevention.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If fuse is integrated directly into disconnect switch, then installation is simplified and cost is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improveinstallation and costVSAvoidpost arrangement and insulator positioning
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent incorporates the insulator and fuse positioning features into the disconnect switch housing during the molding process. By pre-forming the insulator integration and post positioning features in the initial manufacturing step, the design eliminates the need for separate assembly operations, thereby reducing overall manufacturing complexity despite the integrated nature of the components.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2993681B1Mechanical disconnect switch with integrated fuse protection
Publication Date: 2023.02.15 LITTELFUSE INC
  • EP2993681B1 patent drawingFigure 1A~1B
  • EP2993681B1 patent drawingFigure 2A
  • EP2993681B1 patent drawingFigure 2B

AI summary

A circuit protection assembly (CPA) is disposed between a source of power and a circuit to be protected. The CPA comprises a mounting block having a bore extending therethrough and a recess cavity on a first surface of the mounting block. A post having a first end is disposed within the recess cavity and a body portion extends through the bore. The body portion configured to receive a terminal and the second end configured to receive a securing mechanism. A fuse having a centrally disposed aperture is configured to receive the body portion of the post and to receive the terminal for connection to a circuit to be protected. An insulator disposed on the terminal and disposed beneath the securing mechanism. The insulator configured to isolate the post from the terminal and the fuse while allowing the securing mechanism to apply an amount of torque.