Polygonal Spindle Coupling for Compact Door Handle Privacy Locks

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Solution Overview

Problem

Existing polygonal pin arrangements for door and window handles require a large installation space and complex manufacturing, compromising functional reliability and ease of use.

Innovation Solution

A compact polygonal pin arrangement with radially projecting coupling structures and a driver mechanism that allows for a small axial installation space, featuring a spring and magnet system for bistable functionality and precise alignment, ensuring high reliability and ease of use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a locking bar is used to secure the inner pin in the decoupling position, then the inner pin can be axially secured to the outer pin, but the device complexity increases and the installation space requirement increases

Engineering Contradiction:
Improvesecuring of inner pin in decoupling positionVSAvoidnumber of individual parts
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking bar is extracted and replaced by a simplified geometry-based solution. The inner pin's cylindrical section in the first outer pin's inner polygon and the annular groove in the second outer pin create a geometry-based locking mechanism that eliminates the need for a separate locking bar component, reducing device complexity while maintaining securing functionality

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The securing function is merged into the geometric design of the pins themselves. The cylindrical longitudinal section of the inner pin and the annular groove of the second outer pin are integrated into the pin geometries, combining the securing function with the existing structural elements rather than adding a separate locking mechanism

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If a locking bar is used to secure the inner pin, then the inner pin can be axially secured, but the installation space in the axial direction increases

Engineering Contradiction:
Improvesecuring of inner pinVSAvoidaxial installation space
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The securing function is merged into the geometric design of the pins themselves. The cylindrical longitudinal section of the inner pin and the annular groove of the second outer pin are integrated into the pin geometries, combining the securing function with the existing structural elements rather than adding a separate locking mechanism that would require additional axial space

Inventive Principle:
Principle #5Merging (Combining)

3Length of moving object

If additional machining of the door is performed to provide installation space, then the required space can be accommodated, but the manufacturing complexity and time increase

Engineering Contradiction:
Improveinstallation spaceVSAvoiddoor machining requirements
Core Design Contradiction:
Length of moving objectVSEase of manufacture

Solution Approach 1:

The securing function is merged into the geometric design of the pins themselves, eliminating the need for additional door machining. The compact design of the inner pin with its cylindrical section and the second outer pin with its annular groove allows the entire mechanism to be self-contained without requiring modifications to the door structure

Inventive Principle:
Principle #5Merging (Combining)

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 solution provides a compact, reliable, and easy-to-use mechanism for door and window handles with a privacy or safety function, requiring minimal additional space and ensuring precise operation.

Implementation Method 1

a spring device (32) which generates a spring force (FK) acting on the inner pin (15) to move the inner pin (15) into the coupled position (KS)

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

a holding device (33) which generates a holding force (HK) opposing the spring force (FK), wherein the holding force (HK), at least in the initial rotational position, is greater than the spring force (FK)

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP4717858A1Multi-cornered pin assembly, door handle fitting, and window handle fitting
Publication Date: 2026.04.01 KARCHER
  • EP4717858A1 patent drawingFigure 1~2
  • EP4717858A1 patent drawingFigure 3~4
  • EP4717858A1 patent drawingFigure 5~6

AI summary

The invention relates to a polygonal spindle arrangement (8) for a handle set for opening and closing a door or window, comprising a first outer spindle (14.1), a second outer spindle (14.2), and an inner spindle (15) which extends coaxially through one of the two outer spindles (14) and is rotatable therein about a pivot axis (12) and axially adjustable between a coupling position (KS), in which the two outer spindles (14) are rotationally fixed to each other, and a decoupling position (ES), in which the two outer spindles (14) are rotatable relative to each other. A compact design is achieved by the fact that the first outer spindle (14.1) has a radially outwardly projecting first coupling structure (18), and that the second outer spindle (14.2) has a radially outwardly projecting second coupling structure (19), and that the inner pin (15) has a radially outwardly projecting driver (20) which, in the coupling position (KS), engages axially with the first coupling structure (18) and with the second coupling structure (19), such that the driver (20) couples the first coupling structure (18) with the second coupling structure (19) in a rotationally fixed manner, and which, in the decoupling position (ES), does not engage axially with the first coupling structure (18), such that the first coupling structure (18) and the second coupling structure (19) are rotatable relative to each other about the axis of rotation (12).