High-Density Turbine Rotor for Medical Cutting Stability

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Solution Overview

Problem

Turbine rotors made of aluminum in medical cutting instruments experience rapid rotation speed increases, leading to increased bearing load and reduced cutting power due to low inertia moment, which can result in stalling during cutting operations.

Innovation Solution

Use a turbine rotor formed of a metal with a density of 4.0 g/cm³ or more, optionally with a counterweight and a quick stop mechanism, to stabilize rotation speed and maintain cutting power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a turbine rotor is made of aluminum for ease of processing, then manufacturing complexity is reduced, but the inertia moment during rotation becomes small causing rapid rotation speed increase and increased bearing load

Engineering Contradiction:
Improveease of processingVSAvoidrotation speed stability
Core Design Contradiction:
Ease of manufactureVSSpeed

Solution Approach 1:

The patent changes the material parameter (density) of the turbine rotor from aluminum to a metal with density of 4.0 g/cm³ or more. This parameter change increases the inertia moment, which stabilizes rotation speed and reduces bearing load, while still maintaining ease of manufacture through proper material selection and processing methods.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If a turbine rotor is made of aluminum, then manufacturing cost is reduced, but cutting power decreases due to rapid rotation speed increase and stalling under cutting load

Engineering Contradiction:
Improvemanufacturing costVSAvoidcutting power
Core Design Contradiction:
Ease of manufactureVSPower

Solution Approach 1:

The patent changes the density parameter of the turbine rotor material to 4.0 g/cm³ or more, which increases the inertia moment. This prevents rapid rotation speed increase and stalling under cutting load, thereby maintaining cutting power while keeping manufacturing costs reasonable through efficient material utilization and processing.

Inventive Principle:
Principle #35Parameter changes

3Weight of moving object

If a turbine rotor is made of aluminum, then weight is reduced, but rotation speed control becomes difficult leading to rapid speed increase

Engineering Contradiction:
Improveturbine rotor weightVSAvoidrotation speed control
Core Design Contradiction:
Weight of moving objectVSSpeed

Solution Approach 1:

The patent optimizes the weight parameter by selecting a metal with density of 4.0 g/cm³ or more, which provides appropriate weight for the turbine rotor. This increased weight corresponds to increased inertia moment, which improves rotation speed control by preventing rapid speed increases while maintaining reasonable overall weight through efficient design.

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 reduces rapid rotation speed increases and prevents stalling, maintaining cutting power by increasing inertia moment and incorporating a quick stop mechanism to brake the turbine rotor effectively.

Implementation Method 1

its inertia moment during rotation is small, which makes the rotation speed prone to rapid increase

Methodology Applied
Scientific EffectInertia moment: Moment of Inertia

Implementation Method 2

a quick stop mechanism for braking the turbine rotor

Methodology Applied
Scientific EffectFriction braking: Friction

Data Source

PatentEP4628046A1Turbine rotor, cartridge, and medical cutting instrument
Publication Date: 2025.10.08 NAKANISHI INC
  • EP4628046A1 patent drawingFigure 1
  • EP4628046A1 patent drawingFigure 2
  • EP4628046A1 patent drawingFigure 3

AI summary

Provided are a turbine rotor of a rotary cutting instrument and a rotary cutting instrument having a turbine rotor with which it is possible to reduce a sharp increase in the rotational speed of a turbine rotor and to suppress a reduction in cutting power due to a loss of speed when a cutting load is input during rotation of the turbine rotor. A turbine rotor (42) of an air-turbine handpiece (1) is formed of a metal having a density greater than or equal to 4.0 [g/cm3].