Pull-Out Guide with Independent Rolling Cage for Slippage Compensation

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Solution Overview

Problem

Existing pull-out guides experience slippage issues when moving the running rail relative to the middle and guide rails, leading to incomplete closure due to sliding friction, requiring manual intervention to achieve the closed position.

Innovation Solution

A pull-out guide design featuring three synchronized rolling element cages with a flexible deflection element, where the third cage can move independently to compensate for slippage, allowing the second cage to rest against a stop while the third cage continues to roll, reducing the force required to close the pull-out element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cable control with rolling element cages is used to synchronize movement, then stable running behavior is achieved, but slippage occurs between the running rail and rolling elements leading to incomplete closure

Engineering Contradiction:
Improvestable running behaviorVSAvoidcomplete closure
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system is divided into multiple rolling element cages (first cage between guide rail and middle rail, second cage between middle rail and running rail, and third rolling body cage between running rail and middle rail). Each cage can move independently to compensate for slippage, allowing the pull-out element to be fully closed even when one cage encounters friction or stops.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The third rolling body cage is designed to be movable relative to the second rolling element cage parallel to the extension direction, rather than being rigidly connected. This dynamic configuration allows the third cage to continue rolling and compensate for slippage when the second cage is braked by a stop, ensuring complete closure.

Inventive Principle:
Principle #15Dynamics

2Extent of automation

If a self-closing mechanism with energy accumulator is used, then automatic closure is enabled, but the mechanism cannot overcome sliding friction when rolling element cages are stopped

Engineering Contradiction:
Improveautomatic closureVSAvoidovercoming sliding friction
Core Design Contradiction:
Extent of automationVSForce

Solution Approach 1:

The closure function is distributed across multiple rolling element cages rather than relying on a single cage. When one cage is stopped, the energy accumulator can still overcome sliding friction in other cages that are in rolling state, enabling automatic closure to complete.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The energy accumulator is designed to overcome sliding friction in at least one rolling element cage when others are stopped. This partial action is sufficient to enable automatic closure, as the rolling elements in other cages continue to facilitate movement with lower friction.

Inventive Principle:
Principle #16Partial or excessive action

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 effectively compensates for slippage, enabling the pull-out element to be fully closed with lower tensile forces, as only sliding friction on the second cage needs to be overcome, with the third cage's rolling elements facilitating smooth closure.

Implementation Method 1

rolling elements held in a first rolling body cage being provided between the guide rail and the middle rail, and rolling bodies held in a second rolling body cage are provided between the middle rail and the running rail

Methodology Applied
Scientific EffectRolling friction: Friction

Implementation Method 2

the first rolling body cage is synchronized with the second rolling body cage via a flexible deflection element guided on the middle rail

Methodology Applied
Scientific EffectFlexibility: Elasticity

Data Source

PatentEP4195976B1Pull-out guide
Publication Date: 2023.11.29 PAUL HETTICH GMBH & CO KG
  • EP4195976B1 patent drawingFigure 1
  • EP4195976B1 patent drawingFigure 2
  • EP4195976B1 patent drawingFigure 3~4

AI summary

A pull-out guide (1) comprises a guide rail (2), which can be secured on a basic furniture structure, a central rail (3) and a running rail (4), which can be coupled to a pull-out element and can be moved between a pulled-out position and a retracted position, wherein rolling bodies (12) retained in a first rolling-body cage (5) are provided between the guide rail (2) and the central rail (3), and rolling bodies (12) retained in a second rolling-body cage (6) are provided between the central rail (3) and the running rail (4), and the first rolling-body cage (5) is synchronized with the second rolling-body cage (6) via a flexible deflecting element (9), which is guided on the central rail (3), wherein a third rolling-body cage (7) containing rolling bodies (12) is provided between the running rail (4) and the central rail (3), wherein the third rolling-body cage (7) is arranged such that it can be moved relative to the second rolling-body cage (6) parallel to the pulling-out direction. This makes it possible to compensate for slippage on the rolling bodies.