Pull-Out Slide Assembly with Preloaded Ball to Eliminate Radial Play

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Solution Overview

Problem

Pull-out guides in devices like ovens experience radial play due to ball track misalignment, leading to wobbly and imprecise movement, and existing solutions like narrowing profiles or using larger balls result in ball cage immobilization or shifting, causing operational issues.

Innovation Solution

A ball with a larger diameter is preloaded in each row, allowing slight play for other balls to roll freely, preventing rail tilting while enabling smooth ball cage movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If all balls are made larger in diameter to eliminate radial play, then radial play is reduced, but the ball cage becomes difficult to move or may be damaged during installation

Engineering Contradiction:
Improveradial play eliminationVSAvoidball cage displacement
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies local quality by making only one ball in each row have a larger diameter while keeping other balls at the standard size. This localized approach concentrates the preload effect on a single ball to eliminate radial play, while the remaining smaller balls maintain sufficient clearance to allow easy ball cage displacement and installation without damage.

Inventive Principle:
Principle #3Local quality

2Reliability

If the ball cage is preloaded with all balls to eliminate radial play, then radial play is eliminated, but the ball cage cannot be moved or installed easily

Engineering Contradiction:
Improveradial play eliminationVSAvoidball cage installation
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent implements local quality by applying preload only to one ball per row rather than all balls. This selective preload eliminates radial play through the preloaded ball while the other balls with normal dimensions provide necessary clearance, enabling straightforward ball cage installation and movement without requiring excessive force or special tools.

Inventive Principle:
Principle #3Local quality

3Reliability

If larger balls are used to eliminate radial play, then radial play is reduced, but the ball cage may shift over time and fail to reach end positions

Engineering Contradiction:
Improveradial play reductionVSAvoidend position accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by using one larger preloaded ball per row to eliminate radial play and prevent rail tilting, while the combination of preloaded and standard-sized balls maintains proper clearance and positioning. This prevents the ball cage from shifting over time while ensuring it can still reach its designated end positions accurately, as the preloaded ball stabilizes the configuration without creating excessive friction.

Inventive Principle:
Principle #3Local quality

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 solution eliminates radial play, ensuring smooth operation and preventing rail tilting, while allowing the ball cage to be moved without hindrance, maintaining full extension and retraction functionality.

Implementation Method 1

A ball in a row of balls on the ball track has a larger diameter than the other balls on the ball track. The increased diameter is chosen so that this ball is preloaded, in particular slightly preloaded

Methodology Applied
Scientific EffectPreload:

Implementation Method 2

The pull-out guide comprises a guide rail, a running rail and a ball track between the guide rail and the running rail, the ball track having a ball cage and one or more rows of balls

Methodology Applied
Scientific EffectRolling:

Data Source

PatentEP2992782B1Slide assembly
Publication Date: 2019.05.08 APPARATEBAU GRONBACH SRL
  • EP2992782B1 patent drawingFigure 1~2
  • EP2992782B1 patent drawingFigure 3~4
  • EP2992782B1 patent drawingFigure 5~6

AI summary

A pull-out slide comprises rails (1, 2) lying one next to the other in succession, and rolling elements (4,5) of round cross-section, each arranged between the two rails and suitable for rolling on them, thereby making a Allow displacement of one (2) of the two adjacent rails along the other rail (1). In order to reduce or eliminate the radial play, at least one (4) of the rolling elements has a diameter of its cross section that is larger than the diameter of the cross section of the other rolling elements (5) such that this rolling element (4) with the larger diameter is between the two adjacent rails (1, 2) is biased and the remaining rolling elements (5) are instead installed with play (Fig. 2).