Sliding Locking Hook Fitting for Tool-Free Sash Mounting

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Solution Overview

Problem

Existing fittings for windows and doors are structurally complex, often not intuitively mountable, and not easily removable without tools, leading to potential damage during installation.

Innovation Solution

A fitting with a first arm and a locking element featuring a spring bar with a hook, which can be easily mounted by displacing a displacement body to secure the hook into a profile groove, allowing tool-free installation and removal, and a locking device to prevent unintentional disengagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional locking mechanisms with multiple components are used, then reliable engagement is achieved, but device complexity increases and ease of operation deteriorates

Engineering Contradiction:
Improvereliable engagementVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the locking element and displacement body into a single integrated component with interlocking geometry. The locking element features a hook-shaped end that engages with the profile groove, while the displacement body includes an inclined plane that works with a cam surface on the locking element to enable tool-free actuation. This merging of functions into one component reduces the number of parts while maintaining reliable engagement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The locking element serves multiple functions: it provides the locking hook for engagement, incorporates a cam surface for actuation, and includes integration features with the displacement body. This multi-functionality eliminates the need for separate locking mechanisms, screws, or tools, achieving both reliability and simplicity.

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

2Reliability

If traditional fixed mounting methods are used, then secure attachment is achieved, but ease of operation deteriorates due to requirement of tools

Engineering Contradiction:
Improvesecure attachmentVSAvoidtool-free mounting
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The locking element is designed to be movable relative to the displacement body during installation. The inclined plane of the displacement body interacts with the cam surface to dynamically transition the locking element from a retracted position (for easy insertion) to an engaged position (for secure attachment). This dynamic mechanism enables tool-free mounting while maintaining secure attachment.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The fitting is designed to be self-installing without external tools. The user simply pushes the fitting into the profile groove, and the inclined plane automatically actuates the locking element into its engaged position through the cam mechanism. The system serves itself by converting the simple pushing motion into the complex locking action.

Inventive Principle:
Principle #25Self-service

3Reliability

If locking element is always engaged, then reliability is improved, but ease of operation deteriorates due to inability to remove

Engineering Contradiction:
Improvesecure engagementVSAvoidreversible mounting
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The locking mechanism is designed to be dynamically reversible. The displacement body can be pushed in the opposite direction along its axis, which reverses the cam action and releases the locking element from engagement. This allows the fitting to be easily removed by applying force in the reverse direction, maintaining both secure engagement during use and ease of removal when needed.

Inventive Principle:
Principle #15Dynamics

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 fitting is securely attached to the window or door without tools, enabling quick and reversible installation without damage, with a locking mechanism ensuring stability and ease of use.

Implementation Method 1

a spring bar with a hook that can be displaced relative to a displacement body

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a bevel for easy transition between loose and mounted positions

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentEP4074931B2Fitting with a locking hook which can be locked by longitudinal sliding
Publication Date: 2026.05.06 ROTO FRANK FENSTER & TURTECHNOLOGIE GMBH
  • EP4074931B2 patent drawingFigure 1a~1b
  • EP4074931B2 patent drawingFigure 2
  • EP4074931B2 patent drawingFigure 3

AI summary

The invention relates to a fitting (14) mountable on a sash (12), a window (10), and a door with such a fitting (14), as well as a method for mounting a fitting (14). The fitting (14) has at least one first arm (20) with a locking element (24) and a displacement body. The displacement body is displaceable relative to the locking element (24) in the direction of the longitudinal axis of the first arm (20) in order to support a first locking hook in a mounted position, so that the first locking hook cannot move inwards in the mounted position. A ramp is provided between the locking element (24) and the displacement body, via which the locking element (24) can be moved from the mounted position to a disengaged position. In the disengaged position, the first locking hook is no longer supported by the displacement body, so that it can move inwards. The fitting (14) can thus be easily mounted and dismounted on the sash (12).