Frustoconical Ball Bearing Axial to Radial Preload Conversion

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Solution Overview

Problem

Conventional ball bearings in mechanical assemblies experience increased wear and reduced durability due to residual radial clearance between the stator and rotating elements, which allows eccentric rotation and excessive radial forces, leading to potential irreparable damage under impact.

Innovation Solution

An axially preloaded ball bearing assembly with a preload mechanism that applies an axial force to a frustoconical outer race, transferring it into a radial force to eliminate or reduce clearance between the ball bearing and stator, using press fits for the inner diameter surfaces of the ball bearings on the rotor shaft.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If radial clearance is allowed to remain to reduce stiffness, then impact resistance is maintained, but eccentric rotation increases generating larger radial forces

Engineering Contradiction:

Improveimpact resistanceVSAvoidradial force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The frustoconical outer surface geometry parameter enables conversion of axial preload to radial preload, eliminating radial clearance and preventing eccentric rotation. This geometric parameter change addresses both the impact resistance requirement and the radial force reduction requirement simultaneously.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a frustoconical outer race is used to convert axial preload to radial preload, then radial clearance is eliminated, but the bearing structure becomes more complex

Engineering Contradiction:

Improveclearance eliminationVSAvoidbearing structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The frustoconical outer race structure performs multiple functions: it maintains radial load capacity, converts axial preload to radial preload to eliminate clearance, and maintains impact resistance. This multi-functional design achieves clearance elimination without proportionally increasing structural complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 reduces relative movement and wear, increases durability, and decreases radial forces, thereby minimizing the likelihood of component damage and improving the assembly's stability under impact.

Implementation Method 1

the stator being configured with a frustoconical surface which firmly abuts the frustoconical exterior surface of the second ball bearing to transfer a portion of the axial preload force to a radial preload force

Methodology Applied

Scientific EffectForce transformation through frustoconical geometry: Wedge

Implementation Method 2

the inner race is press fit to the rotating element. This press fit secures the assembled ball bearing to the rotating element

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP2093439B1Frustoconical ball bearing and preloaded ball bearing assemblies

Publication Date: 2013.04.24 HAMILTON SUNDSTRAND CORP

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AI summary

A ball bearing for interconnecting a rotor to a stator has a plurality of balls (44) and an inner (42) and outer race (48). The inner race and the outer race have an interior surface (56,66) configured to movably engage a portion of the balls, and at least one of the inner race and outer race includes a frustoconical exterior surface (62;68). The bearing may be used in an assembly in which an axial preload is transferred to a radial preload via the frustoconical surface.