Dental Handpiece Chuck With Integrated Plunger Ball for Low-Friction Release

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Solution Overview

Problem

Existing dental handpieces face issues with excessive mechanical abrasion and heating at the clamping mechanism, require a compact design to access spatially limited oral cavity areas, and need reliable and easy operation.

Innovation Solution

A dental handpiece design featuring a ceramic ball that rotates with the hollow shaft, reducing friction and heat dissipation by point-like contact with the resilient arms, allowing a compact configuration and easy operation through a plunger-like mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional clamping mechanism with direct contact between push button and wedge-shaped element is used, then the clamping mechanism is simple in structure, but excessive mechanical abrasion and heating occur at the contact area

Engineering Contradiction:
Improvereliable operationVSAvoidmechanical abrasion and heating
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A ceramic ball is introduced as an intermediary element between the push button and the wedge-shaped clamping element. The ball acts as a mediator that transfers the releasing force while rotating, preventing direct sliding contact between the push button and the clamping mechanism. This intermediary ball reduces mechanical abrasion and heat generation by converting sliding friction into rolling friction.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Volume of moving object

If the head size is reduced to access spatially limited oral cavity areas, then ease of access is improved, but the clamping mechanism becomes more compact and complex

Engineering Contradiction:
Improvehead sizeVSAvoidclamping mechanism complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The ball is integrated directly into the hollow shaft structure, merging the ball's housing with the shaft itself. This integration eliminates the need for separate ball housing components, reducing the overall head volume while maintaining the functional complexity of the clamping mechanism. The merged structure allows the ball to rotate within the shaft without requiring additional external containment structures.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If the push button is always in contact with the clamping mechanism, then operational reliability is improved, but excessive heating occurs at the contact area

Engineering Contradiction:
Improveoperational reliabilityVSAvoidcontact area temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The ball rotates periodically as it moves between the push button and the wedge-shaped element during operation. This periodic rotation ensures that different portions of the ball's surface contact the push button at different times, distributing the thermal load across the ball's surface area. The periodic motion prevents continuous heating at a single contact point, allowing heat dissipation between contact cycles.

Inventive Principle:
Principle #19Periodic action

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

Prevents excessive mechanical abrasion and heating, enables a compact head size for easier oral cavity access, and facilitates easy and reliable clamping/releasing of dental drills with reduced user force.

Implementation Method 1

a chuck having resilient arms for releasably clamping a dental drill... move the ball downwardly in between the resilient arms so as flex the resilient arms radially outwards and release the dental drill

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a biasing means to move the push button away from the ball, wherein the push button is not in contact with the wedge-shaped element when it is released

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 3

the ball partly protrudes through an opening on the upper end of the hollow shaft... the lower side of the ball generally gives only rise to point-like contacts with the resilient arms of the chuck due to its spherical shape which further reduces any heat transfer from the lower side of the ball to the chuck

Methodology Applied
Scientific EffectFriction reduction through point contact: Friction

Data Source

PatentEP4311516B1Dental handpiece having a chuck with an integrated plunger ball
Publication Date: 2025.09.10 DENTSPLY SIRONA INC
  • EP4311516B1 patent drawingFigure 1
  • EP4311516B1 patent drawingFigure 2a
  • EP4311516B1 patent drawingFigure 2b

AI summary

The present invention relates to a dental handpiece (1) comprising: a dental handpiece (1) comprising: a head (4); a rotatable hollow shaft (15) which is rotatably arranged inside the head (4); a driving means for rotating the hollow shaft (15); a chuck (26) having resilient arms (27) for releasably clamping a dental drill (2), wherein the chuck (26) is fixed into the hollow shaft (15) so as to rotate with same; a ball (14) which is axially movably arranged inside the rotatable hollow shaft (15) and in direct contact with the resilient arms (27) of the chuck (26), wherein the ball (14) partly protrudes through an opening (17) on the upper end of the hollow shaft (15), and wherein the opening (17) is smaller than the size of the ball (14); a push button (7) which is arranged in the head (4) and configured to contact, when pressed by a user, the partly protruding ball (14) and move the ball (14) downwardly in between the resilient arms (27) so as flex the resilient arms (27) radially outwards and release the dental drill (2), wherein the resilient arms (27) bias the ball (14) inside the rotatable hollow shaft (15) towards the opening (17); and a biasing means to move the push button (7) away from the ball (14), wherein the push button (7) is not in contact with the ball (15) when it is released.