Dental Motor Assembly Shortened Coupling Pin Sterilization

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Solution Overview

Problem

Dental motors face challenges in sterilization resistance due to the degradation of insulating materials under sterilization processes, and existing designs compromise on size and ergonomics for functionality.

Innovation Solution

A compact dental electric motor arrangement with a shortened coupling pin, integrated media pipes, and a one-piece motor housing, utilizing high-temperature polymers for the stator and soft-magnetic yoke, and an SMD LED light source for reduced length and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the stator is completely encased in high-temperature polymer for sterilization resistance, then sterilization resistance is improved, but the motor length increases

Engineering Contradiction:
Improvesterilization resistanceVSAvoidmotor length
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The patent embeds the media lines directly within the polymer casing structure, nesting one component inside another. The media lines are integrated into the stator assembly and surrounded by the polymer casing, eliminating the need for separate channels or external routing that would increase length.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent repositions the media lines from a longitudinal arrangement (parallel to the rotor shaft) to a radial arrangement (perpendicular to the rotor shaft). This dimensional change allows the media lines to exit the stator in a direction that reduces the overall motor length while maintaining sterilization resistance through complete polymer encasement.

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

2Ease of operation

If the coupling pin is shortened for better ergonomics, then ease of operation is improved, but the structural integrity may be compromised

Engineering Contradiction:
ImproveergonomicsVSAvoidcoupling pin integrity
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The coupling pin is constructed from composite materials or optimized alloy structures that provide high strength-to-weight ratio. This allows the pin to be shortened while maintaining sufficient mechanical integrity and torque transmission capability through enhanced material properties rather than increased dimensions.

Inventive Principle:
Principle #40Composite materials

3Power

If the distance between return and permanent magnet is reduced for motor power, then power is improved, but the space for overmolded stator is reduced resulting in thin plastic casing

Engineering Contradiction:
Improvemotor powerVSAvoidplastic casing thickness
Core Design Contradiction:
PowerVSStrength

Solution Approach 1:

The patent employs composite material structures in the stator assembly that provide both mechanical strength and magnetic properties. The polymer casing is reinforced with structural elements or filled with composite materials that maintain adequate thickness for sterilization resistance while accommodating the reduced distance between magnetic components.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies different material properties to different regions of the stator. Areas requiring high mechanical strength receive enhanced polymer composition or additional reinforcement, while areas requiring magnetic flux pathways maintain closer spacing between components. This localized optimization allows reduced motor power distance while maintaining adequate casing thickness where needed.

Inventive Principle:
Principle #3Local quality

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 enhances sterilization resistance, reduces noise, and improves ergonomics by shortening the motor length while maintaining functionality, providing a more ergonomic and efficient dental handpiece.

Implementation Method 1

an SMD LED light source for reduced length and noise

Methodology Applied
Scientific EffectLight Emitting Diode: Light Emitting Diode

Implementation Method 2

the stator is completely and tightly encased in a sterilization-resistant high-temperature polymer (e.g. PEEK, PPS, LCP, PAI, PPSU, PSU, PES)

Methodology Applied
Scientific EffectThermal resistance: Thermal Insulation

Implementation Method 3

a rotor with a rotor shaft rotatably mounted about a longitudinal axis

Methodology Applied
Scientific EffectRotation:

Data Source

PatentEP3404809B1Electric motor assembly for a medical, specifically, dental handpiece
Publication Date: 2021.06.30 KAVO DENTAL GMBH
  • EP3404809B1 patent drawingFigure 1~3
  • EP3404809B1 patent drawingFigure 4~8
  • EP3404809B1 patent drawingFigure 9~12

AI summary

A dental electric motor arrangement for a dental handpiece comprises a rotor (R) with a rotor shaft rotatably mounted about a longitudinal axis (L) and a coupling pin (310') for connection to the handpiece, wherein the coupling pin (310') has a length (l) in the direction of the longitudinal axis (L), the length (l) being less than 30 mm.