Multi-Stage Interlock with Reduction Gear for Luggage

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Solution Overview

Problem

Conventional single-stage locks require significant force to lock suitcases, making them inconvenient to use during packing.

Innovation Solution

A novel multi-stage interlock system with a main lock and side locks, utilizing a control mechanism with reduction gears and springs to reduce the force required for locking, providing audible feedback and modular design for adjustable security based on luggage size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional single-stage locks are used, then the locking mechanism is simple, but quite force is required to lock the suitcase making it inconvenient to use

Engineering Contradiction:
Improveease of lockingVSAvoidforce required for locking
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The locking mechanism is divided into multiple stages with multiple lock hooks (first lock hook, second lock hook, third lock hook) that engage sequentially. Each stage locks at a different position, distributing the locking force across multiple engagement points rather than requiring single-point force concentration, thereby reducing the effort needed for each individual locking action.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lock body includes a pushing component that automatically pushes the lock hooks into their locked positions with the lock holes after the user initiates locking. This preliminary automated action reduces the manual force the user must apply, as the system performs part of the locking work automatically through spring-driven or mechanism-driven hook engagement.

Inventive Principle:
Principle #10Preliminary action

2Force

If multi-stage interlock system is implemented, then the force required for locking is reduced, but the device complexity increases

Engineering Contradiction:
Improveforce required for lockingVSAvoidcomplexity of locking mechanism
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The control mechanism serves multiple functions: it controls the engagement of multiple lock hooks, manages the interaction between lock body and lock holes, and coordinates the pushing component's action. This multi-functional design consolidates what could be separate complex mechanisms into a single integrated control system, reducing overall device complexity while maintaining multi-stage locking capability.

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

Solution Approach 2:

The lock hooks are nested within the lock body structure, with the first, second, and third lock hooks arranged in sequence within the same housing. The control mechanism is also nested within the lock body, managing all hook engagements from a centralized position. This nested arrangement reduces spatial complexity and simplifies the overall structure compared to distributed locking mechanisms.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 multi-stage interlock system reduces the force needed for locking, provides clear audible feedback, and allows for modular adjustment of security levels, enhancing user experience and manufacturing efficiency.

Implementation Method 1

The first plate is provided with two spring-loaded catches that engage, during closing, with the two saw-toothed gears fixed to the second plate

Methodology Applied
Scientific EffectSpring-loaded mechanism: Spring

Implementation Method 2

A pair of main lock assemblies are located on both sides of the control mechanism. The control mechanism can control the locking and unlocking of all the main lock assemblies synchronously

Methodology Applied
Scientific EffectMechanical advantage: Mechanical Advantage

Data Source

PatentEP4056791B1Novel multi-stage interlock, and case applying same
Publication Date: 2025.01.08 MERIT TECH (FU JIAN) CO LTD
  • EP4056791B1 patent drawingFigure 1~2
  • EP4056791B1 patent drawingFigure 3
  • EP4056791B1 patent drawingFigure 4

AI summary

Provided is a novel multi-stage interlock, including a main lock and a pair of main lock hooks adapted for the main lock. The main lock includes a main lock housing, a control mechanism, and a pair of main lock cylinder assemblies. The main lock cylinder assemblies and the control mechanism both are arranged within the main lock housing. The pair of main lock assemblies are located at both sides of the control mechanism, respectively. The control mechanism is capable of controlling the locking and unlocking of all of the main lock cylinder assemblies. The main lock hooks are provided with a plurality of first protruding teeth adapted for the main lock cylinder assemblies. The present invention provides a multi-stage interlock which uses multiple-stage interlocking to realize easy closing for the case. The use of reduction gear further reduces the force to push the buttons. The feedback of sound during opening the case generated by the spring makes it clear to the users whether the lock is in place.