Door Bottom Security Strip with Deflecting Element

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Solution Overview

Problem

Existing burglary protection devices for doors, particularly the underside, are inadequate as they can be easily bypassed using tools like a goat's foot or wire, and lack sufficient security features to prevent unauthorized access or tool penetration.

Innovation Solution

A burglary protection device featuring a security strip with a defensive element that prevents tools from being pushed under, including a sloping extension or horizontal base, which can deflect or block tools, combined with a mechanical lowering mechanism for automatic activation when the door is closed, providing enhanced sealing and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional drop seal is used to seal the gap between the door leaf and the floor, then sealing effectiveness against drafts, noise, and light is improved, but burglary protection is worsened as the seal can be easily lifted with a crowbar or bypassed with a wire

Engineering Contradiction:
Improvesealing effectivenessVSAvoidburglary vulnerability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protective device is divided into multiple functional segments: a sealing strip for draft/noise/light sealing, a deflecting element for preventing tool insertion, and a lowering mechanism for automatic deployment. Each segment performs a specific function, collectively providing both sealing and burglary protection without compromising either aspect.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protective device combines different material properties in a single integrated structure: a flexible sealing profile (rubber/silicone) for sealing, a rigid deflecting element (metal or hard plastic) for burglary protection, and a mechanical lowering mechanism. This composite structure simultaneously achieves sealing effectiveness and burglary resistance.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If the underside of the door is left without additional protection to maintain ease of operation, then accessibility for disabled people and smooth door operation are improved, but security against tool insertion and prying is worsened

Engineering Contradiction:
Improvedoor accessibilityVSAvoidtool insertion vulnerability
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The protective device features a dynamic lowering mechanism that automatically deploys the security strip and deflecting element when the door closes. This dynamic action provides burglary protection only when needed (door closed), while maintaining ease of operation (no manual intervention required) and accessibility (no permanent obstacle when door is open).

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The lowering mechanism is automatically actuated by the door closing action itself, using the door's movement to trigger the deployment of the protective elements. This self-service mechanism eliminates the need for separate actuators, sensors, or power sources, maintaining ease of operation while providing effective security.

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If a mechanical lowering mechanism is added to provide automatic sealing and security, then burglary protection and sealing are improved, but device complexity is worsened

Engineering Contradiction:
Improveburglary resistanceVSAvoidmechanical mechanism complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The lowering mechanism serves multiple functions simultaneously: it deploys the sealing strip for draft/noise/light sealing, positions the deflecting element for burglary protection, and can provide mechanical support for the security strip. This multi-functionality reduces the need for separate mechanisms, thereby limiting the increase in device complexity while maximizing protective benefits.

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

4Object-affected harmful factors

If the deflecting element is designed with a downwardly oblique extension to prevent tool insertion, then burglary protection is improved, but manufacturing precision requirements are worsened to ensure proper seating and force distribution

Engineering Contradiction:
Improvetool deflection effectivenessVSAvoidinstallation precision
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The deflecting element is pre-formed with the optimal downwardly oblique extension angle and geometry during manufacturing. This preliminary action ensures that the element is pre-positioned and pre-shaped to effectively deflect tools, reducing the precision requirements during installation. The element arrives ready-to-install with its protective geometry already optimized.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3792441A1Burglar protection device for a door
Publication Date: 2021.03.17 ASSA ABLOY (SCHWEIZ) AG
  • EP3792441A1 patent drawingFigure 1~2
  • EP3792441A1 patent drawingFigure 3~4
  • EP3792441A1 patent drawingFigure 5a

AI summary

An anti-burglary device for a door comprises a locking bar (3) for mounting on or in a door leaf (F) and for closing a gap between the door leaf (F) and the bottom of the door (6). The locking bar (3) can be moved from a raised position to a locked position, in which it closes the gap when the door is closed. The locking bar (3) has a locking element (32, 31, 33) whose shape prevents the locking bar (3) from being reached under and penetration between the locking bar (3) and the bottom of the door (6). This anti-burglary device provides optimal protection against break-ins, even when a crowbar or wire loop is used as a burglary tool.