Variable Guide Cage for High Speed Bearings

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Solution Overview

Problem

Existing rolling bearing cages face issues with excessive friction at high speeds and noise/vibrations at low speeds, and current designs are either costly or unsuitable for mass production and high-precision applications.

Innovation Solution

A thermoplastic cage with a specific geometry and material properties that utilizes differential thermal expansion and centrifugal expansion to transition the guide from rolling bodies to the outer ring at high speeds, reducing friction and maintaining accurate positioning, while allowing easy assembly and robust introduction of rolling bodies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the cage is made of thermoplastic material with specific geometry, then friction at high speeds is reduced and noise/vibrations at low speeds are eliminated, but manufacturing complexity increases due to specific geometric requirements

Engineering Contradiction:
ImprovefrictionVSAvoidcage geometry
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The cage geometry parameters (seat width, guide surface angle, radial thickness) are specifically designed to change the interaction between cage and rolling bodies based on operating conditions. The guide surface angle α and seat width b are optimized to provide optimal guidance at low speeds while reducing friction at high speeds.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cage design allows dynamic adaptation of its functional characteristics based on operating speed and thermal conditions. At low speeds, the cage geometry provides active guidance on rolling bodies; at high speeds, thermal expansion and centrifugal forces cause the cage to expand, naturally reducing the guidance interaction and friction.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If the cage geometry is optimized for low speed performance, then noise and vibrations are eliminated, but friction increases at high speeds

Engineering Contradiction:
Improvenoise and vibrationsVSAvoidfriction
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The thermoplastic cage material is selected and dimensioned so that thermal expansion during operation naturally adjusts the cage-rolling body interaction. As temperature increases with speed, the cage expands radially, reducing the guidance pressure on rolling bodies and thereby reducing friction at high speeds while maintaining noise-free operation at low speeds.

Inventive Principle:
Principle #37Thermal expansion

Solution Approach 2:

The cage design enables dynamic transition in its functional mode based on operating conditions. The guide surface geometry and radial dimensions are designed to provide firm guidance at low speeds for noise elimination, while allowing natural clearance development at high speeds through thermal and centrifugal expansion to reduce friction.

Inventive Principle:
Principle #15Dynamics

3Loss of energy

If a cage made of pressed metal or plastics with U-shaped cross section is used, then friction at high speeds is reduced, but the cage can only be used effectively with rollers and not spherical rolling bodies

Engineering Contradiction:
ImprovefrictionVSAvoidrolling body compatibility
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The cage design with optimized seat geometry and guide surfaces universally accommodates both spherical rolling bodies and rollers. The seat width, radial thickness, and guide surface angle are dimensioned to provide appropriate guidance and friction reduction for different rolling body types, making the cage applicable to various bearing configurations.

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

4Manufacturing precision

If the cage is designed with complex geometry for high-precision applications, then positioning accuracy is improved, but manufacturing cost increases

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The cage parameters (guide surface angle, seat width, radial thickness) are optimized within practical manufacturing ranges to achieve high positioning accuracy without requiring complex or expensive manufacturing processes. The geometry is designed to be manufacturable using standard techniques while maintaining precision.

Inventive Principle:
Principle #35Parameter changes

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

The solution effectively reduces friction at high speeds and eliminates noise and vibrations at low speeds, ensuring accurate positioning and cost-effective, high-precision operation for high-speed rolling bearings.

Implementation Method 1

By exploiting the phenomenon of differential thermal expansion between the special thermoplastic material of which the cage is made and the material of the outer ring of the bearing and of the rolling bodies

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

as well as centrifugal expansion, which is a function of the rotation speed of the cage

Methodology Applied
Scientific EffectCentrifugal expansion: Centrifugal Force

Implementation Method 3

By exploiting the phenomenon of differential thermal expansion between the special thermoplastic material of which the cage is made and the material of the outer ring of the bearing and of the rolling bodies

Methodology Applied
Scientific EffectDifferential thermal expansion: Thermal Expansion

Data Source

PatentEP2610510B1Variable guide cage for rolling bearings and high speed bearing equipped with such a cage
Publication Date: 2015.03.04 AB SKF SKF PATENT DEPARTMENT
  • EP2610510B1 patent drawingFigure 1
  • EP2610510B1 patent drawingFigure 2~3
  • EP2610510B1 patent drawingFigure 4~5

AI summary

A cage (1) made of synthetic thermoplastic material, preferably a poly-aryl-ether-ketone, for withholding at least one crown of rolling bodies (2) of a high-performance rolling bearing (3), wherein the cage (1) is made so that, below a value of the bearing speed factor between 1.2 and 1.5 millions, the cage (1) is guided onto the rolling bodies (2), while above such a value the cage (1) is guided onto an outer ring (4) of the bearing. A bearing (3) includes such a cage.