Additional-Sash Window Locking for Secure Main-Sash Attachment

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Solution Overview

Problem

Existing windows and French windows with additional sashes face challenges in securely and easily attaching the additional sash to the main sash, with difficulties in monitoring and controlling the secure locking mechanism.

Innovation Solution

A window design featuring a locking unit with a movable locking element that engages behind a locking edge in the locked position, allowing for a simple and secure attachment of the additional sash to the main sash, and includes a locking unit that can be mounted facing either locking edge, suitable for right- or left-hinged sashes without additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the additional sash is mounted on the outside of the main sash, then the main sash can be opened like a normal window, but the attached sash is exposed to wind forces and it becomes difficult to monitor its connection to the main sash

Engineering Contradiction:
Improveopening of main sashVSAvoidconnection monitoring
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements a monitoring mechanism that provides feedback on the locking state of the additional sash. The system detects whether the locking element is properly engaged and communicates this status, allowing users to monitor the connection reliability without needing to physically inspect the external mounting.

Inventive Principle:
Principle #23Feedback

2Device complexity

If simple fastening elements with pivoting bolts are used, then the structure is simple, but the secure locking of the sash to the casement frame is difficult to control or monitor

Engineering Contradiction:
Improvefastening structureVSAvoidlocking control
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent incorporates a monitoring device that detects the position and engagement state of the pivoting bolts. This feedback mechanism allows the system to determine whether the locking elements are properly secured, providing controllability and monitorability without significantly increasing the complexity of the fastening structure itself.

Inventive Principle:
Principle #23Feedback

3Strength

If locking elements penetrate holes in the additional pane, then the additional pane and sash are connected, but the secure attachment is difficult to control or monitor

Engineering Contradiction:
Improveattachment securityVSAvoidattachment monitoring
Core Design Contradiction:
StrengthVSDifficulty of detecting and measuring

Solution Approach 1:

The patent includes a detection device that monitors the engagement state of locking elements penetrating the additional pane. The system can detect whether these elements are properly positioned and secured through the pane material, providing feedback on attachment security without requiring direct visual inspection of the penetration points.

Inventive Principle:
Principle #23Feedback

4Adaptability or versatility

If a two-part composite lock and hinge are used, then the dome fitting for composite sashes is achieved, but a locking unit for locking the locking hook in the locked position is not known

Engineering Contradiction:
Improvecomposite sash fittingVSAvoidlocking position security
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent combines the locking hook mechanism with an additional locking unit that secures the hook in its locked position. This merging of the original two-part composite lock with a supplementary locking mechanism ensures that the locking hook cannot accidentally disengage, providing enhanced reliability while maintaining compatibility with composite sash constructions.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4446533B1Window or french window with an additional sash mounted on a main sash
Publication Date: 2025.09.10 AUG WINKHAUS SE
  • EP4446533B1 patent drawingFigure 1~2
  • EP4446533B1 patent drawingFigure 3~5
  • EP4446533B1 patent drawingFigure 6~9

AI summary

A window or French door has a fastening unit (4) for the detachable connection of a secondary sash (3) to a main sash (2). A locking unit (8) for securing the secondary sash (3) can be locked in a locking position by a locking unit (9). This ensures a permanent and secure attachment of the secondary sash (3) to the main sash (2).