Annular Gap Shields for Dental Handpiece Bearing Reliability

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Solution Overview

Problem

Medical, dental, and surgical handpieces with rotary tools face challenges in bearing longevity due to contamination, degradation of lubricants during cleaning and sterilization, and the need for frequent re-lubrication, which can lead to contamination risks during patient treatment.

Innovation Solution

A bearing assembly with annular gap shields at each axial end to prevent contamination ingress and retain lubricant, featuring a stainless steel or ceramic ball design with a non-crown retainer and snap-interlocking shields made from engineering plastics, capable of withstanding high temperatures and repeated sterilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional open bearing designs are used in handpieces, then the bearing assembly allows for simple construction and easy assembly, but the bearing is susceptible to contamination ingress and lubricant expulsion during high-speed operation and sterilization

Engineering Contradiction:

Improvebearing lifeVSAvoidbearing assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The bearing assembly is segmented into distinct functional zones using shields: a first shield at the leading end separates the bearing from contaminant sources, while a second shield at the trailing end prevents lubricant expulsion. This segmentation allows each shield to address specific contamination pathways without requiring complete redesign of the bearing assembly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Shields are introduced as intermediary elements between the bearing and the external environment. These shields act as mediators that block contaminant ingress and lubricant expulsion without requiring direct modification of the bearing itself, thus maintaining bearing simplicity while improving reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If shields are added to prevent contamination and retain lubricant, then bearing reliability improves, but the bearing assembly becomes more complex and difficult to assemble

Engineering Contradiction:

Improvelubricant retentionVSAvoidbearing assembly fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The shields are designed as thin, flexible barriers that can be easily manufactured and integrated into the bearing assembly. These thin-film shields provide effective contamination protection and lubricant retention while minimizing the increase in assembly complexity and manufacturing difficulty.

Inventive Principle:

Principle #30Flexible shells and thin films

3Duration of action of moving object

If lubricant is frequently replenished to maintain bearing performance, then bearing operation continues, but the risk of contamination increases and additional time and expense are required

Engineering Contradiction:

Improvebearing operational continuityVSAvoidcontamination risk

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The shields are installed in advance to create a sealed environment that prevents lubricant depletion and contaminant ingress. This preliminary protective action eliminates the need for frequent lubricant replenishment and associated contamination risks during bearing operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The bearing assembly with shields becomes self-sufficient, maintaining its lubricant and protecting itself from contaminants without requiring external intervention for lubricant replenishment. This self-service capability reduces contamination risk and operational downtime.

Inventive Principle:

Principle #25Self-service

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 bearing assembly extends operational life by preventing lubricant expulsion and contamination, eliminating the need for frequent re-lubrication and maintaining effective performance during high-speed operations and sterilization cycles.

Implementation Method 1

The bearing assembly incorporates annular gap shields at each axial end to prevent contaminate ingress and to retain lubricating grease within the bearing assembly

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

The second shield is capable of withstanding repeated sterilization, autoclaving, and exposure to associated high temperatures without degradation of mechanical properties

Methodology Applied

Scientific EffectThermal resistance: Thermal Insulation

Data Source

PatentUS8931960B2High speed ball bearing for dental or medical handpieces

Publication Date: 2015.01.13 THE TIMKEN CO(US)

AI summary

A bearing assembly (20) for use in a medical, surgical, or dental handpiece (10) that enables spindle rotation for a supported rotary tool (36) at high speeds. The bearing assembly (28) incorporates annular gap shields (50, 54) at each axial end to prevent contaminate ingress and to retain lubricating grease within the bearing assembly (28) to avoid re-lubricated after each use or sterilization cycle.