Snap-Fit Locking Arrangement for Electric Module Cards

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Solution Overview

Problem

The existing methods for replacing electric module cards in a housing for distribution grid automation systems are inefficient, as they often result in the generation of metal chips that can cause short-circuits, and require time-consuming screw removal and reattachment, making the process difficult and prone to errors.

Innovation Solution

A locking arrangement using snap-fit transverse members that secure electric module cards between side walls of a housing, allowing for toolless and rapid removal and insertion without screws, reducing the risk of metal chip dispersion and simplifying the exchange process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If screws are used to fasten electric module cards to the housing, then the module cards are securely fixed, but the replacement process becomes time-consuming and generates metal chips that can cause short-circuits

Engineering Contradiction:

Improvesecure fixation of module cardsVSAvoidreplacement time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The housing is divided into a stationary base and a movable cover that can be independently removed. The cover contains the module cards and can be detached as a single unit, allowing rapid replacement without manipulating individual screws for each card. This segmentation resolves the contradiction by enabling secure fixation during operation while allowing fast replacement when needed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cover containing the module cards is extracted as a separate removable component from the housing. This allows the entire set of module cards to be removed and replaced as one unit without dealing with individual fastening elements, dramatically reducing replacement time while maintaining secure fixation when the cover is in place.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If screws are used to fasten electric module cards, then the cards are securely held, but metal chips are generated that can spread inside the housing and cause short-circuits

Engineering Contradiction:

Improvesecure fixation of module cardsVSAvoidmetal chip dispersion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The screw-based mechanical fastening system is replaced with a snap-fit or friction-fit mechanism integrated into the removable cover. This substitution eliminates the need for screws and nut assemblies, preventing metal chip generation while maintaining secure fixation of module cards during normal operation. The cover itself acts as the retaining structure rather than individual fasteners.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a metal plate with openings for electric contacts is used over the module cards, then the cards are protected, but the difficulty of replacement increases and all contacts must be disconnected

Engineering Contradiction:

Improveprotection of electric contactsVSAvoidreplacement difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The housing is segmented into a base and a removable cover, with the cover containing all module cards. This segmentation allows the entire cover to be removed as one unit, providing contact protection when closed while enabling simple replacement by removing the whole cover without disconnecting individual contacts. The segmentation separates the protection function (cover enclosing contacts) from the replacement operation (remove entire cover).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The removable cover serves multiple functions simultaneously: it protects electric contacts from damage, secures module cards in position, and acts as a removable carrier for rapid replacement. This multi-functionality resolves the contradiction by integrating protection and securement features into a single component that simplifies rather than complicates the replacement process.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This solution enables fast, reliable, and chip-free module card exchanges, enhancing the operational reliability of the electric device by eliminating the need for screwing and unscrewing, while maintaining connected cables for unaffected cards.

Implementation Method 1

at least one locking mechanism configured to detachably connect at least one of the transverse members to at least one of the side members by means of a snap-fit

Methodology Applied

Scientific EffectSnap-fit: Mechanical Fastener

Data Source

PatentEP4098087B1Locking arrangement for electric module cards, housing and electric device

Publication Date: 2024.06.05 HITACHI ENERGY LTD

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AI summary

A locking arrangement (16) for securing electric module cards (14) between two side walls (18) of a housing (12), the locking arrangement (16) comprising two side members (26) for fixed arrangement with the respective side walls (18); an opening (32) for accommodating electric contacts (24) of the electric module cards (14) defined between the side members (26); a first and a second transverse member (28) configured to form a frame with the side members (26) in order to lock the electric module cards (14) within the housing (12); and at least one locking mechanism (34) configured to detachably connect at least one of the transverse members (28) to at least one of the side members (26) by means of a snap-fit. A housing (12) for accommodating electric module cards (14) and an electric device (10) comprising a housing (12) are also provided.