Switchgear Housing Snap Hook Prevents Terminal Gaps

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Solution Overview

Problem

Generic service switching devices experience gaps between housing parts in the area of connection terminals due to riveted connections, which can lead to moisture and dirt ingress, compromising device functionality, especially under pressure surges during short-circuit switching.

Innovation Solution

A second connecting means, such as a snap hook with a resilient web and latching surface, is introduced in the terminal receiving space to securely lock the housing parts together, preventing them from gaping apart, even under pressure surges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If riveted connections are used to join housing parts, then the housing parts are held together firmly at several points, but gaps occur in the area of connection terminals where rivets cannot be positioned

Engineering Contradiction:
Improveholding force of housing connectionVSAvoidgap-free connection at terminal area
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The connection system is divided into two segments: riveted connections for the broad sides of the housing and a separate snap hook mechanism for the narrow side in the terminal area. This segmentation allows each connection type to be optimized for its specific location, with the snap hook filling the gap where rivets cannot be positioned.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The snap hook acts as an intermediary connection element that bridges the gap between housing parts in the terminal area where rivets cannot reach. It provides a dedicated locking mechanism specifically for the narrow side, ensuring continuous connection throughout the entire housing perimeter.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If connection terminals are tightened more than necessary, then secure electrical connection is achieved, but the housing parts gape apart in the area of connection terminals

Engineering Contradiction:
Improveelectrical connection securityVSAvoidhousing part alignment
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The snap hook mechanism provides preliminary anti-action by preemptively counteracting the gapping force generated during terminal tightening. The resilient web and latching surface are designed to resist the outward pressure surge that occurs when terminals are tightened, preventing gap formation before it can compromise housing integrity.

Inventive Principle:
Principle #9Preliminary anti-action

3Ease of manufacture

If housing parts are made of thermoplastic material for ease of manufacture, then manufacturing is simplified and cost reduced, but the material is softer and more flexible leading to potential gapping under pressure

Engineering Contradiction:
Improvehousing material processingVSAvoidresistance to pressure surge
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The snap hook mechanism compensates for the lower mechanical strength of thermoplastic material by introducing a mechanical interlocking system. The resilient web is designed with specific elasticity parameters that allow it to withstand pressure surges and maintain the closed position of housing parts, effectively offsetting the material's flexibility.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If the housing is designed with receiving spaces for connection terminals, then electrical connections are enabled, but gaps occur in these areas where no riveted connection can be made

Engineering Contradiction:
Improveterminal connection capabilityVSAvoidhousing seal integrity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The housing connection system employs local quality by providing different connection mechanisms for different locations: riveted connections for the broad sides and a snap hook mechanism specifically for the narrow side in the terminal area. This localized solution addresses the specific needs of the terminal region while maintaining overall housing integrity.

Inventive Principle:
Principle #3Local quality

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

The snap hook mechanism effectively prevents gaps between the housing parts at connection terminals, ensuring the device's integrity and functionality by providing a reliable locking mechanism that resists outward forces and maintains closure even during pressure surges.

Implementation Method 1

a first resilient web protruding perpendicular to the broad side in the area of the joining line, which carries a locking lug with a second locking surface at its free end

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2015333B1Installation switching device with isolating material housing
Publication Date: 2013.08.07 ABB AG(DE)
  • EP2015333B1 patent drawingFigure 1
  • EP2015333B1 patent drawingFigure 2
  • EP2015333B1 patent drawingFigure 3

AI summary

The invention relates to an installation switching device with an insulating housing, which has a front and an opposite mounting side, as well as narrow and wide sides connecting the front and the mounting side, comprising at least one first housing shell and at least one cover part, which are joined by first connecting means that engage the wide sides of the housing shell and the cover part and hold them together forming a circumferential joining line, wherein the insulating housing includes receiving spaces for connection terminals in the area of ​​the narrow sides. In the area of ​​a terminal receiving space and in the area of ​​the narrow side associated therewith, a second connecting means is provided, which holds the housing shell and the cover part together there at the joining line.