Dental Instrument Torque Limiting Gear Mechanism

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Solution Overview

Problem

Dental instruments face challenges in torque limitation, leading to potential tool breakage and stress on gear components due to excessive torque, which can result in early failure and difficulties in removing stuck tools during procedures.

Innovation Solution

A dental instrument with a gear housing containing a torque-limiting device featuring a preloaded spring element that contacts the ring gear to limit torque, allowing for simple and robust adjustment of torque levels, even at high speeds, using multiple ring gears and adjustable spring elements for precise control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a torque-limiting device with a preloaded spring element is used to limit torque in the transmission, then the risk of tool breakage and gear failure is reduced, but the device complexity increases

Engineering Contradiction:
Improvetorque limitationVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The torque-limiting device merges the spring element, ring gear, and transmission housing into a single integrated assembly. The spring element is positioned between the ring gear and housing, combining multiple components into one compact unit that limits torque through the interaction of these merged elements, thereby reducing overall device complexity while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The torque-limiting device employs a nested structure where the spring element is positioned within the transmission housing and interacts with the ring gear. The spring element is effectively nested between the ring gear and the housing, creating a compact arrangement that limits torque without adding significant external complexity to the transmission system.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Manufacturing precision

If multiple spring elements are used for precise torque adjustment, then the manufacturing precision and torque control improve, but the ease of manufacture decreases

Engineering Contradiction:
Improvetorque adjustment precisionVSAvoidease of manufacture
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The torque-limiting device uses multiple spring elements (first and second spring elements) that can be independently adjusted. Each spring element can be selectively positioned and preloaded to different degrees, allowing precise torque adjustment through segmented control. This segmentation enables fine-tuning of torque limits while maintaining relatively simple manufacturing processes for each individual spring element.

Inventive Principle:
Principle #1Segmentation

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 limits torque, reducing the risk of tool breakage and gear failure, enabling precise adjustment and extended instrument lifespan while maintaining operational efficiency.

Implementation Method 1

a preloaded spring element (18) which is at least partially in contact with the ring gear (7) and brings it into contact with the transmission housing (4) in order to change or at least limit the torque

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the ring gear (7) relative to the transmission housing (4) for torque limitation is designed to slip against the bias

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3232979B1Dental instrument comprising a gearing for driving a tool
Publication Date: 2018.09.12 SIRONA DENTAL SYSTEMS GMBH CORP LEGAL
  • EP3232979B1 patent drawingFigure 1
  • EP3232979B1 patent drawingFigure 2~3
  • EP3232979B1 patent drawingFigure 4~5

AI summary

The invention relates to a dental instrument, comprising a gearing for driving a tool, wherein at least one torque limiting device is provided, which can be brought into contact with the gearing, as a result of which the maximum acting torque in the gearing can be limited.