Flush-Mounted Window And Door Handle With Variable Linkage

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Solution Overview

Problem

Existing flush-mounted window and door handles are limited by their depth due to the use of large gear wheels and metal alloys with low mechanical strength, restricting their use to profiles with sufficient hollow space and compromising functionality and cost-effectiveness.

Innovation Solution

A handle design with a linkage mechanism using two pins and slots to vary the transmission arm length, reducing the depth of the case while maintaining the same stroke, and incorporating plastic components for enhanced strength and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If large gear wheels and toothed sectors are used to achieve desired stroke length, then the stroke length is improved, but the depth of the case increases

Engineering Contradiction:
Improvestroke lengthVSAvoiddepth of case
Core Design Contradiction:
Length of moving objectVSLength of stationary object

Solution Approach 1:

The patent replaces the traditional gear wheel and toothed sector mechanism with a linkage mechanism consisting of two pins and slots. This substitution allows the transmission arm length to be varied during operation, achieving the desired stroke length without requiring large gear dimensions, thereby reducing the case depth while maintaining functional performance.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention introduces a dynamic linkage mechanism where the transmission arm length changes as the operating lever rotates. The two pins and slots configuration allows the effective transmission arm to vary in length during the stroke, enabling optimized force transmission without fixed large gear dimensions, thus resolving the contradiction between stroke length and case depth.

Inventive Principle:
Principle #15Dynamics

2Length of stationary object

If the height of gear teeth is reduced to decrease case depth, then the case depth is reduced, but the mechanical strength decreases

Engineering Contradiction:
Improvedepth of caseVSAvoidmechanical strength
Core Design Contradiction:
Length of stationary objectVSStrength

Solution Approach 1:

The patent eliminates the gear tooth structure entirely by using a linkage mechanism with two pins and slots. This replacement avoids the need for high gear teeth that would increase case depth, while the linkage design ensures sufficient mechanical strength through proper pin-slot engagement and force transmission paths.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the fundamental parameters of the transmission mechanism from gear-based (with tooth height as a critical parameter) to linkage-based (with pin-slot geometry as critical parameters). This parameter change allows the case depth to be reduced without compromising mechanical strength, as the linkage design optimizes force transmission through geometric configuration rather than tooth height.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If metal alloys with low mechanical strength are used for handle components, then the manufacturing cost is reduced, but the strength and durability decrease

Engineering Contradiction:
Improvemanufacturing costVSAvoidstrength and durability
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent employs a composite construction where the case is made from zinc alloy (zamak) and the operating lever is made from plastic material. This composite approach combines the cost-effectiveness and ease of manufacturing of zinc alloy with the strength and durability benefits of plastic, creating a handle that is both economical to manufacture and sufficiently strong for its application.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the material parameters by using plastic instead of metal for the operating lever. This material substitution maintains manufacturing cost-effectiveness while providing adequate strength and durability, as the plastic material is specifically selected to meet the mechanical requirements of the linkage mechanism.

Inventive Principle:
Principle #35Parameter changes

4Length of moving object

If the operating lever rotation angle is increased to achieve longer stroke, then the stroke length is improved, but the device complexity increases

Engineering Contradiction:
Improvestroke lengthVSAvoiddevice complexity
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent uses a dynamic linkage mechanism where the transmission arm length varies during the 90° or 180° rotation of the operating lever. This dynamic configuration allows the linkage to achieve extended stroke length through geometric transformation rather than requiring more complex multi-stage mechanisms, maintaining relative simplicity while improving performance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention utilizes the rotational dimension of the operating lever (90° or 180°) and transforms it through the linkage geometry to achieve linear stroke length. The two pins and slots configuration converts rotational motion in one dimension into linear motion in another dimension, achieving extended stroke without increasing overall device complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 handle achieves a compact design, compatible with various profiles, ensuring strong and functional operation with reduced depth, smooth movement, and secure positioning of components, eliminating the need for large gears and enhancing durability.

Implementation Method 1

an operating lever (4) that is rotatably coupled to the case (2) about a fulcrum whose axis is orthogonal to the first direction (J) and parallel to the bottom of the case (2)

Methodology Applied
Scientific EffectLever: Lever

Implementation Method 2

A linkage (7, 8) connects the transmission arm (41) of the operating lever (4) to the slider (5) and is configured so that the length of the transmission arm (41) varies as the angular position of the operating lever (4) with respect to the case (2) varies

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Implementation Method 3

A linkage (7, 8) connects the transmission arm (41) of the operating lever (4) to the slider (5) and is configured so that the length of the transmission arm (41) varies as the angular position of the operating lever (4) with respect to the case (2) varies. In particular, this linkage is configured in such a way that the length of the transmission arm (41) decreases with the increase of the angle that the longitudinal development axis of the operating lever (4) forms with a plane parallel to the first direction (J)

Methodology Applied
Scientific EffectFour-Bar Linkage: Four-Bar Linkage

Data Source

PatentEP4450741B1Handle for operating mechanisms for opening and closing windows and doors, the handle being of the type that is flush-mounted into a window or door frame cavity
Publication Date: 2025.10.22 MASTER LAB SRL
  • EP4450741B1 patent drawingFigure 1~1a
  • EP4450741B1 patent drawingFigure 2~2a
  • EP4450741B1 patent drawingFigure 3~6

AI summary

Flush-mounted handle (1) for operating mechanisms for opening and closing windows and doors, comprising: - a case (2) adapted to be flush-mounted into a window or door frame cavity and extending longitudinally along a first straight direction (J), the case (2) defining a containment seat (3) open outwards for containing an operating lever (4); - a slider (5) slidably coupled to the case (2) along a sliding direction parallel or coincident to the first direction (J) and provided with connection fastenings (6) connecting to components of a mechanism for opening and closing the window or door; - an operating lever (4) for operating the sliding motion of the slider (5) and rotatably coupled to the case (2) about a fulcrum defining a gripping arm (40) and a transmission arm (41); - a linkage connecting the transmission arm (41) to the slider (5), wherein the length of the transmission arm (41) varies with the angular position of the operating lever (4) with respect to the case (2).