Tapered Roller Bearing Raceway Eliminating Undercut

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Solution Overview

Problem

Tapered roller bearings experience significant power losses due to friction, which is a concern for sustainable management of raw materials and energy, especially in vehicles.

Innovation Solution

The design of a tapered roller bearing with a raceway element that eliminates the undercut in the transition region from the rim to the rolling surface, allowing for a thinner rim and reduced friction by optimizing the contact area between the rolling elements and the rim, resulting in lower sliding and power losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an undercut is provided in the transition region from the flange inner surface to the rolling surface, then the raceway element can be manufactured with adequate flange strength, but the raceway element requires greater axial length and material usage

Engineering Contradiction:
Improveflange strengthVSAvoidraceway element axial length
Core Design Contradiction:
StrengthVSLength of moving object

Solution Approach 1:

The invention replaces the conventional undercut (sharp angular transition) with a curved transition surface having a specific radius of curvature. This curved geometry eliminates the need for an extended flange thickness while maintaining adequate strength by distributing stresses more effectively through the curved surface, thereby reducing the axial length of the raceway element.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Device complexity

If the contact area between rolling element faces and flange inner surface is positioned far from the rolling surface, then the flange structure is simpler, but friction losses and power consumption increase

Engineering Contradiction:
Improveflange structure complexityVSAvoidfriction losses
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The invention optimizes the local position of the contact area on the rolling element faces, specifying that the contact occurs within a defined radial distance from the main axis (within 85-98% of the rolling element face radius). This localized optimization of contact position reduces sliding friction while maintaining simple flange structure, thereby reducing energy losses without increasing complexity.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If consistent surface quality is achieved on both the rolling surface and flange inner surface, then manufacturing precision is improved, but the transition region requires additional material to avoid undercuts

Engineering Contradiction:
Improvesurface quality consistencyVSAvoidraceway element material
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

By implementing a curved transition surface with specific radius requirements, the invention enables consistent surface quality to be achieved across both the rolling surface and flange inner surface without requiring additional material. The curved geometry allows for uniform material distribution and eliminates the need for excessive flange thickness that would otherwise be required to accommodate an undercut while maintaining surface integrity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 material and weight usage while minimizing friction losses, leading to lower power consumption and improved efficiency in tapered roller bearings.

Implementation Method 1

This allows, among other things, the flange to be advantageously designed with a reduced thickness in the axial direction while maintaining consistent flange strength. This, in turn, allows for a shorter raceway element, thus advantageously saving material and weight. Furthermore, by eliminating the undercut, it is possible to shift the intended contact area between the rolling element faces and the inside of the flange closer to the rolling surface through appropriate design of the rolling element faces and the inside of the flange. This results in a rolling action with minimal sliding on this contact area, thus reducing friction losses and consequently lowering power losses.

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2840266B1Track element and tapered roller bearing with the track element
Publication Date: 2019.07.03 AB SKF SKF PATENT DEPARTMENT
  • EP2840266B1 patent drawingFigure 1~2
  • EP2840266B1 patent drawingFigure 3~4

AI summary

In a raceway element for frustoconical rolling elements with a rolling surface for the rolling elements and with an inner surface on one of the end faces of the rolling elements, in which an area of ​​the inner surface is provided for contact by areas of the rolling element contact faces, when viewed from a central area of ​​the inner surface between its outer and inner edges and directed radially along a rolling element end face to the rolling surface, the raceway element is free of an undercut in a transition area from the inner surface to the rolling surface with respect to the viewing direction.