Mechanical Plug Locking with Polarity Indication

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Solution Overview

Problem

Existing AC plug connections lack effective mechanical security to prevent unintentional disconnection due to tensile loads, which can lead to accidents, and do not provide clear visual indication of a secure connection.

Innovation Solution

A mechanical fuse design with visible markings or edge lines on a pushbutton that protrudes from the connector housing, allowing for easy visual verification of correct insertion and polarity, utilizing an asymmetrical locking mechanism and spring block for secure and space-efficient connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical locking mechanism is added to the plug connection, then the security against unintentional disconnection is improved, but the device complexity increases

Engineering Contradiction:
Improvesecurity against unintentional disconnectionVSAvoidcomplexity of plug connection
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism is segmented into separate functional components: locking claws on the plug, corresponding locking notches on the socket, and a push-button release mechanism. This segmentation allows each component to perform its specific function independently while maintaining overall system simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The locking mechanism automatically engages when the plug is inserted into the socket without requiring user intervention. The locking claws automatically snap into the locking notches, providing self-securing functionality that improves reliability without adding operational complexity.

Inventive Principle:
Principle #25Self-service

2Difficulty of detecting and measuring

If visual markings are added to the pushbutton, then the ease of detecting correct connection is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvevisibility of correct insertionVSAvoidmanufacturing of pushbutton
Core Design Contradiction:
Difficulty of detecting and measuringVSEase of manufacture

Solution Approach 1:

The pushbutton incorporates colored markings or edge lines that are visible from the side when the button protrudes too far beyond the housing. These color indicators provide immediate visual feedback about the connection status without requiring complex display mechanisms.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

Instead of hiding the connection status inside the plug, the indicator is placed on the exterior pushbutton surface where it is easily visible from the side. This inverted approach to indicator placement makes detection trivial while keeping the manufacturing process simple.

Inventive Principle:
Principle #13The other way round (Inversion)

3Adaptability or versatility

If the locking mechanism is designed to be asymmetric for polarity indication, then the ability to indicate correct polarity is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvepolarity indication capabilityVSAvoidprecision of asymmetric locking mechanism
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The locking mechanism incorporates asymmetric features where the position and orientation of locking claws and notches correspond to specific polarities. The pushbutton markings are also asymmetrically positioned to indicate the correct insertion orientation, enabling polarity identification through the locking mechanism itself.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The asymmetric locking mechanism serves multiple functions simultaneously: it provides mechanical locking security, indicates correct polarity through its asymmetric geometry, and guides proper insertion orientation. This multi-functionality reduces the need for separate polarity indication components.

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

The solution provides enhanced mechanical security against unintentional disconnection, ensures correct polarity, and offers a simple, self-explanatory, and visually confirmable secure connection, suitable for standard SCHUKO® plugs, reducing the risk of accidents and improving user safety.

Implementation Method 1

a spring block (18) for the spring (17)

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP3391476B1Mechanically securing an electric plug connection for grid voltages
Publication Date: 2020.02.05 A STEFFEN AG ELEKTROHANDEL
  • EP3391476B1 patent drawingFigure 1
  • EP3391476B1 patent drawingFigure 2
  • EP3391476B1 patent drawingFigure 3~5

AI summary

Plug connections in alternating current grids are often disconnected accidentally due to tension acting on a cable. Plugs (1) can be mechanically secured in the protective collar (2) of couplings and sockets by means of easily actuatable keys (6) with connected claws (7). One embodiment of a secured plug connection in SCHUKO® systems solves an old problem, namely correctly pairing outer conductors and neutral conductors. If four recesses (16,16') are provided, the connection can be mechanically secured and the polarity of the connection can be reversed like before. The plug (1) can likewise be used in conventional couplings and sockets.