Profiled Drive Rod Line Contact Friction Reduction

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Solution Overview

Problem

Existing drive rod arrangements for windows and doors face challenges in allowing easy displacement with minimal effort due to high frictional forces between the drive rod and its guide elements, which complicates operation and increases the cost of manufacturing.

Innovation Solution

The drive rod is profiled to allow only line contacts between the drive rod and its guide elements, reducing friction and enabling easy displacement, with features like inclined upper sides, wedge-shaped free spaces, and angled retaining lugs, allowing for elastic deformation and simplified assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the drive rod and guide element have conventional contact surfaces, then the structural design is simple, but high frictional forces occur making displacement difficult

Engineering Contradiction:
Improveease of displacementVSAvoidcross-section profiling
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The drive rod is given a profiled cross-section specifically in the displacement area where it contacts the guide element. This local profiling creates line contacts that reduce friction only where needed, while the rest of the drive rod maintains its conventional simple structure. The profiling is applied selectively to the top surface in the displacement zone, combining simplicity elsewhere with operational ease at the critical contact point.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If line contact is implemented to reduce friction, then operational effort is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improveoperational effortVSAvoidmanufacturing process
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The cross-sectional parameters of the drive rod are changed in the displacement area by creating a profiled surface. This can be achieved through various manufacturing methods such as embossing, stamping, or molding during production. The profiling changes the geometric parameters (creating inclined surfaces and line contact zones) while maintaining compatibility with standard manufacturing processes, thus reducing operational effort without excessively complicating manufacturing.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the drive rod is rigidly fixed in the guide slot, then positioning precision is high, but tolerance variations cause assembly difficulties

Engineering Contradiction:
Improvepositioning precisionVSAvoidtolerance accommodation
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The guide slot is designed with converging guide slot walls that create a wedge-shaped free space. This dynamic design allows the drive rod to be guided precisely along its displacement path while accommodating tolerance variations through the wedge-shaped clearance. The converging walls provide gradual guidance rather than rigid constraint, allowing for elastic deformation and adjustment during assembly while maintaining accurate positioning during operation.

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

This design reduces operational effort required to move the drive rod and allows for cost-effective manufacturing by minimizing friction and accommodating tolerance variations, ensuring smooth operation and flexibility in assembly.

Implementation Method 1

there is only a small amount of friction between the connecting rod guide element and the connecting rod, so that the connecting rod can be displaced or shifted particularly easily within its displacement range

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

The wedge-shaped free space allows the retaining bar to be deformed, elastically and/or plastically, without the line contact or the line contacts being lost

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2132391B1Drive rod arrangement comprising at least one drive rod and at least one drive rod guiding element
Publication Date: 2011.06.01 ROTO FRANK AG
  • EP2132391B1 patent drawingFigure 1
  • EP2132391B1 patent drawingFigure 2
  • EP2132391B1 patent drawingFigure 3

AI summary

The invention relates to a drive rod arrangement for a window, door or similar, comprising at least one drive rod and at least one drive rod guiding element for maintaining the drive rod within a displacement area of the drive rod. The drive rod guiding element comprises a fastening element that reaches through a guiding slit of the driving rod and a maintaining element overlays the top side of the drive rod. According to the invention, the cross-section of the drive rod (2) is profiled, at least in the displacement area (10), in such a manner that when the maintaining element (7) and driving rod are touched, only one line contact is established or several line contacts are established.