Worm Shaft Bearing Assembly With Annular Spring Preload

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Solution Overview

Problem

Existing bearing arrangements for worm gears often suffer from play due to manufacturing tolerances and wear, leading to malfunctions and increased wear, as they lack precise positioning and guidance of the roller bearing in all degrees of freedom.

Innovation Solution

An annular spring is anchored at one point on the housing circumference and engages diametrically opposite on the roller bearing's outer circumference, allowing only linear movement in the tension direction, providing precise positioning and a high preload force while minimizing space requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If an annular spring surrounds the rolling bearing to generate high preload force, then the preload force is increased, but the spring requires installation space within the housing

Engineering Contradiction:
Improvepreload forceVSAvoidinstallation space
Core Design Contradiction:
ForceVSVolume of stationary object

Solution Approach 1:

The annular spring is nested within the annular space formed by the housing's inner circumference and the rolling bearing's outer circumference. This nesting arrangement allows the spring to be accommodated within the existing radial clearance without requiring additional volume in the housing, efficiently utilizing the available space.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The spring is configured as an annular structure that utilizes the radial dimension (circumferential space) rather than requiring additional axial or radial clearance. By transforming the spring into an annular shape that fits within the existing annular gap, the solution generates high preload force without increasing the housing volume.

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

2Measurement precision

If the rolling bearing is guided to move exclusively linearly in the spring's tension direction, then the positioning is precise, but the guidance structure becomes more complex

Engineering Contradiction:
Improvepositioning precisionVSAvoidguidance structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The guide surfaces serve multiple functions simultaneously: they constrain the rolling bearing in directions perpendicular to the spring action, provide support surfaces for load transmission, and define the linear movement path. This multi-functionality reduces the need for separate guidance elements, simplifying the overall structure while maintaining precise positioning.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The guidance function is merged with the support structure by integrating guide surfaces directly into the housing and rolling bearing surfaces. Rather than adding separate guidance mechanisms, the existing structural surfaces are configured to provide both support and guidance functions, reducing device complexity.

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

This configuration ensures stable and precise positioning of the roller bearing and worm shaft, reducing play and wear, and maintaining precise guidance in all degrees of freedom, enhancing the bearing arrangement's stability and longevity.

Implementation Method 1

an annular spring is provided for preloading the rolling bearing, which surrounds the rolling bearing... the spring is an annular tension spring that pulls the outer ring of the rolling bearing toward the side of the housing where the spring is anchored

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a rolling bearing in which the worm shaft is supported

Methodology Applied
Scientific EffectRolling friction: Friction

Data Source

PatentEP3994368B1Bearing assembly for a worm shaft
Publication Date: 2023.07.12 ROLLAX GMBH & CO KG
  • EP3994368B1 patent drawingFigure 1~2
  • EP3994368B1 patent drawingFigure 3
  • EP3994368B1 patent drawingFigure 4

AI summary

The invention relates to a bearing assembly for a worm shaft (12), comprising a rolling bearing (14) in which the worm shaft (12) is mounted, and comprising a housing (10) in which the rolling bearing (14) is elastically pretensioned in a direction z transverse to the longitudinal direction x of the worm shaft (12), characterised in that the rolling bearing (14) is supported in the housing (10) on both sides in the direction y perpendicular to the pretensioning direction z and to the longitudinal direction x of the worm shaft (12), and in that an annular spring (16) is provided for pretensioning the rolling bearing (12), which surrounds the rolling bearing (14), which is anchored in the housing (10) at a point on its circumference, and which engages on the outer circumference of the rolling bearing (14) at a point (32) diametrically opposite the anchoring point (28).