Additional Bolt Fitting Assembly for Mullion-Free Sash Security

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Solution Overview

Problem

Existing window and door fittings, particularly those without a central mullion, struggle to provide adequate burglary resistance due to limited cross-sections of locking elements, which fail to meet increased security requirements.

Innovation Solution

A fitting arrangement with a drive rod assembly and a bolt attachment, where a locking element can be retracted or extended longitudinally, and an additional bolt is housed in a casing, ensuring a larger effective cross-section for enhanced security, coupled with a gearbox for converting rotary movement into longitudinal movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single locking element is used in the drive rod assembly, then the device complexity is reduced, but the burglary resistance is insufficient due to limited cross-section

Engineering Contradiction:
Improveburglary resistanceVSAvoidlocking mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking function is segmented into two independent locking elements (first locking element and second locking element) that can be engaged independently. This segmentation allows each element to have adequate cross-section for security while keeping the overall mechanism manageable through modular operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drive rod assembly is designed to perform multiple functions: it can engage either the first locking element or the second locking element depending on the closing sequence. This multi-functionality allows a single drive rod to provide adequate security cross-section by selectively engaging different locking elements with sufficient dimensions

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

2Adaptability or versatility

If identical hardware arrangements are installed on both sashes, then the adaptability and security consistency are improved, but the device complexity increases due to synchronized control requirements

Engineering Contradiction:
Improvehardware configuration flexibilityVSAvoidsynchronized control complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system dynamically adapts its locking configuration based on the closing sequence of sashes. When sashes are closed in different sequences, different locking elements are engaged, allowing identical hardware arrangements on both sashes to function independently without requiring complex synchronized control mechanisms

Inventive Principle:
Principle #15Dynamics

3Reliability

If the locking element cross-section is increased to meet security requirements, then the burglary resistance is improved, but the ease of operation deteriorates due to larger moving parts

Engineering Contradiction:
Improvesecurity requirement fulfillmentVSAvoidlocking mechanism operability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The locking function is divided into multiple locking elements, each with adequate cross-section for security. By segmenting the locking function, each individual element can be operated independently with reasonable dimensions, avoiding the need to operate a single oversized locking element that would compromise ease of use

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system uses partial action by engaging only one locking element at a time depending on the closing sequence. This allows each locking element to have sufficient cross-section for security while being operated independently, rather than requiring all locking elements to be engaged simultaneously which would increase operational complexity

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4685318A1Fitting assembly with an additional bolt, in particular for double winged windows or doors without central mullion post
Publication Date: 2026.01.28 ROTO FRANK FENSTER & TURTECHNOLOGIE GMBH
  • EP4685318A1 patent drawingFigure 1
  • EP4685318A1 patent drawingFigure 2
  • EP4685318A1 patent drawingFigure 3

AI summary

The invention relates to a locking bolt attachment for reinforcing the locking of a window or door sash to a frame. A hardware assembly includes a sliding drive rod assembly. A locking element of the drive rod assembly can be retracted by operating a handle to allow the window or door to be opened, or extended to fix the sash to the frame in a closed position. The drive rod assembly has a locking bolt to which an additional bolt is coupled. The additional bolt and the locking element move in the same direction over the same distance. A common strike plate for the additional bolt and the locking element can be provided on the frame. The additional bolt secures the sash to the frame in the closed position in addition to the locking element.This is particularly useful for windows or doors with two sashes but without a central mullion on the frame. The additional bolt is preferably housed in a casing. Hardware arrangements that can also be used without the bolt attachment, depending on the application, can then be reinforced particularly efficiently by additionally attaching the bolt attachment to withstand higher loads.