Magnetic Strap Locking Assembly for 50 kg Interchangeable Bag Straps

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Solution Overview

Problem

Existing handbag and backpack straps lack robust locking and fastening devices capable of supporting loads over 10 kg and are not interchangeable, leading to damage and difficulty in replacement when one strap breaks.

Innovation Solution

A locking and fastening device comprising two steel blocks with a neodymium-based magnet and a mortise-tenon mechanism, allowing for a mass support of up to 50 kg, with interchangeable straps and enhanced mechanical and magnetic bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional hooks or screws are used to attach straps to bags, then the strap can be attached to the bag, but the locking device quickly damages the bag or breaks under weights of at least 10 kg

Engineering Contradiction:
Improvemechanical resistanceVSAvoiddurability under load
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent replaces traditional mechanical fastening systems (hooks, screws) with a magnetic locking mechanism. The magnet embedded in the steel block creates a magnetic field that provides both mechanical attachment and locking functions, eliminating the need for separate fasteners that damage the bag or break under load.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses composite construction combining steel blocks with embedded magnets. This composite structure integrates the strength of steel with the magnetic locking capability, creating a unified component that provides both structural integrity and secure attachment without the need for separate fastening elements.

Inventive Principle:
Principle #40Composite materials

2Adaptability or versatility

If traditional strap attachment devices are used, then straps can be attached to bags, but they are not interchangeable and difficult to replace when broken

Engineering Contradiction:
ImproveinterchangeabilityVSAvoiddifficulty of replacement
Core Design Contradiction:
Adaptability or versatilityVSEase of repair

Solution Approach 1:

The patent divides the strap attachment system into separate interchangeable components: a magnetic block unit and a strap. The magnetic block can be detached from the strap and replaced independently, allowing users to swap straps without replacing the entire attachment system, thereby enabling interchangeability and ease of repair.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The magnetic block serves multiple functions: it provides the magnetic locking mechanism, acts as the attachment point for the strap, and serves as the structural core. This universal design allows the same magnetic block to work with different strap configurations and bag types, enhancing versatility and ease of replacement.

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

3Reliability

If magnetic fastening is used to attach straps, then the strap can be securely attached, but the device complexity increases with additional magnetic components

Engineering Contradiction:
Improvesecure attachmentVSAvoidnumber of magnetic components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the magnetic component with the steel block structure, embedding the magnet directly into the steel block rather than using separate magnetic parts. This integration reduces the number of discrete components while maintaining secure magnetic attachment, thereby reducing device complexity while preserving reliability.

Inventive Principle:
Principle #5Merging (Combining)

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 device provides secure, durable, and interchangeable straps capable of supporting heavy loads while preventing damage to the bag, with easy replacement and improved mechanical resistance.

Implementation Method 1

two parts fixed together by means of a permanent magnet

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Implementation Method 2

at least one magnet including a neodymium-based tenon with a magnetic locking and/or magnetic fastening function

Methodology Applied
Scientific EffectMagnetic locking: Magnetism

Data Source

PatentEP4444133B1Device for locking and/or attaching a strap of a handbag or of a backpack
Publication Date: 2026.01.28 BURKHALTER STEEVE
  • EP4444133B1 patent drawingFigure 1~2
  • EP4444133B1 patent drawingFigure 3A~4

AI summary

Disclosed is a device for locking and/or attaching a strap of a handbag or of a backpack, the device being capable of withstanding a mass of up to 50 kg and comprising: - two portions that are attached to one another by means of a permanent magnet: - the lower portion of the two portions comprising a first steel block, this steel block comprising at least one bore or mortise that is at least 3 mm deep; and - the upper portion of the two portions being attached to the lower portion by means of a permanent magnet, and comprising a second steel block whose shape is the inverse of that of the first steel block such that the two steel blocks fit together perfectly; - and a strap made of a material that is capable of supporting a weight of up to 50 kg, this strap being attached to one of the portions, one of the portions being intended to be attached to a bag by means of the attachments, characterized in that the steel block comprises at least one magnet comprising a neodymium-based tenon with a magnetic locking and/or magnetic attaching function, the lead-free brass concentration of which is lower than 100 ppm, and the shape, width and thickness of which corresponds to the inverse dimension of the bore or mortise of the steel block such that: - the tenon of the magnet is inserted into the bore or mortise to form a mechanical and magnetic stop; and - the two steel blocks fit together perfectly to form a mechanically securely connected assembly.