Telescopic drawer slide

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Solution Overview

Problem

Existing pull-out guides for furniture parts, such as drawers, face challenges in achieving high load-bearing capacity and smooth running under varying load conditions, with previous designs limiting the load absorption to less than 50% and experiencing issues with differential running and roller placement.

Innovation Solution

The design incorporates a pull-out guide with a first and second rotatably mounted differential roller, where the second differential roller has a recess or elevation on the body rail's track, allowing it to contribute to differential running over a larger extension path, and an auxiliary roller for additional support, ensuring high load-bearing capacity and smooth operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a single differential roller is used on the middle rail, then the structure is simple, but the load-bearing capacity is limited to less than 50%

Engineering Contradiction:
Improveload-bearing capacityVSAvoidroller arrangement complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The single differential roller is segmented into two separate differential rollers (first and second differential rollers) positioned at different locations on the middle rail. This segmentation allows each roller to independently bear load and contribute to differential running, thereby increasing the overall load-bearing capacity beyond the limitation of a single roller system while maintaining a relatively simple structural concept.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The body rail acts as an intermediary element that receives load from both differential rollers. The body rail's upwardly directed track provides a load transfer path that accommodates the distributed loading from the two differential rollers, enabling the system to handle higher loads by distributing them through the intermediary body rail structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the differential roller is positioned far from the body rail track, then it can accommodate tolerances and geometry changes, but it cannot contribute to differential running over a large extension path

Engineering Contradiction:
Improveaccommodation of tolerances and geometry changesVSAvoiddifferential running contribution path
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The single roller position is segmented into two distinct positions along the middle rail. The first differential roller is positioned to engage with the body rail track over the initial extension path, while the second differential roller is positioned to engage over the subsequent extension path. This segmentation ensures continuous differential running contribution throughout the entire extension range while each roller maintains optimal engagement with the body rail track.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution transitions from a single-point roller arrangement to a distributed multi-point arrangement along the longitudinal dimension of the middle rail. By spacing the two differential rollers at different positions, the system extends the differential running contribution across the full extension path while each roller individually maintains proper engagement geometry with the body rail track.

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

3Strength

If multiple rollers are arranged on the middle rail, then load-bearing capacity increases, but the smooth running and differential running are compromised

Engineering Contradiction:
Improveload-bearing capacityVSAvoidsmooth running
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

Each differential roller is given the specific local quality of having vertical play relative to the middle rail, while maintaining fixed positioning along the longitudinal axis. This localized play allows each roller to independently accommodate load variations and maintain smooth operation, preventing the cumulative roughness that would result from multiple rigidly positioned rollers. The local quality of vertical play is applied specifically to the roller mounting mechanism.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The differential rollers are designed with dynamic vertical play that allows them to adjust their position relative to the middle rail in response to varying load conditions. This dynamic adjustment capability enables the rollers to maintain optimal contact with both the body rail track and pull-out rail track throughout the extension range, ensuring smooth running while accommodating the increased load-bearing capacity provided by having two rollers.

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 configuration enhances the load-bearing capacity and smooth running of the pull-out guide, enabling it to handle loads exceeding 50% of the test load with improved differential running and reduced shock during operation.

Implementation Method 1

each of which has bearing play in the vertical direction relative to the center rail

Methodology Applied
Scientific EffectBearing play: Backlash

Implementation Method 2

Load-transferring rollers are rotatably mounted on all rails

Methodology Applied
Scientific EffectRolling friction: Roller

Data Source

PatentEP3624642B1Telescopic drawer slide
Publication Date: 2021.02.24 FULTERER AG & CO KG
  • EP3624642B1 patent drawingFigure 1~2
  • EP3624642B1 patent drawingFigure 3~4
  • EP3624642B1 patent drawingFigure 5~7

AI summary

A telescopic drawer slide comprises a body rail (3), a pull-out rail (5) and a central rail (4) arranged between the body rail (3) and the pull-out rail (5), which central rail has a first and a second rotatably mounted differential roller (8, 9) each of which has a bearing play in the vertical direction with respect to the central rail (4) and of which, the second differential roller (9) is arranged behind the first differential roller (8) with respect to the pull-out direction (50). The first and the second differential rollers (8, 9) interact with an upwardly directed running track (13) of the body rail (3) and a downwardly directed running track (14) of the pull-out rail (5). In an intermediate position of the rails in which the rear end of the downwardly directed running track (14) of the pull-out rail (5) lies at the second differential roller (9), the second differential roller (9) is located in the region (52) of a depression (25) and/or the first differential roller (8) is located in the region (53) of an elevation (26) of the upwardly directed running track (13) of the body rail (3).