Dental Turbine Rotor Reverse-Flow Brake Design
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Solution Overview
Problem
Existing dental preparation instruments with turbine drives face challenges in achieving a noise-reduced, long-lasting design with uncomplicated configuration, robustness, and low production costs, while maintaining maximum torque and power.
Innovation Solution
The rotor design features a turbine wheel with drive blades housed in a turbine housing that includes a gas inlet and outlet channel system with a return flow channel, and a cross-sectional extension between the drive blades and the cover surfaces, which generates an eddy to deflect propellant back onto the drive blades, thereby reducing rotational speed and increasing braking effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the idling rotational speed is increased to increase the maximum power, then the maximum power is improved, but the lifespan of the mounting and noise behavior deteriorate
Solution Approach 1:
The return flow channel creates a preliminary counteracting force by redirecting propellant flow to oppose the rotation direction, reducing the net driving force on the turbine wheel and thereby lowering the idling rotational speed before it can cause excessive wear or noise
Solution Approach 2:
The return flow channel acts as an intermediary element that mediates between the propellant supply and the turbine wheel, redirecting a portion of the propellant flow to create a braking effect that controls the rotational speed
2Power
If the idling rotational speed is increased to increase the maximum power, then the maximum power is improved, but the noise behavior deteriorates
Solution Approach 1:
The return flow channel creates a preliminary counteracting force by redirecting propellant flow to oppose the rotation direction, reducing the idling rotational speed and thereby preventing excessive noise generation from the outset
3Ease of operation
If additional components such as an adjuster are added to regulate turbine rotational speed, then the rotational speed control is improved, but the device complexity and production cost increase
Solution Approach 1:
The return flow channel is integrated into the existing turbine housing structure, merging the speed control function with the structural components rather than adding separate adjuster mechanisms
Solution Approach 2:
The return flow channel serves multiple functions: it redirects propellant flow, creates a braking effect for speed control, and is integrated into the housing structure, eliminating the need for dedicated speed regulation components
4Ease of operation
If additional components such as an adjuster are added to regulate turbine rotational speed, then the rotational speed control is improved, but the robustness deteriorates
Solution Approach 1:
The return flow channel is integrated into the existing turbine housing structure, merging the speed control function with the structural components rather than adding separate adjuster mechanisms, thereby maintaining robustness
5Ease of operation
If additional components such as an adjuster are added to regulate turbine rotational speed, then the rotational speed control is improved, but the compact design is impeded
Solution Approach 1:
The return flow channel is integrated into the existing turbine housing structure, utilizing available space within the housing rather than adding external components, thereby maintaining compact design
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
This design reduces idling rotational speed without compromising maximum torque or power, leading to low-maintenance and low-wear mountings, improved noise behavior, and a more compact, cost-effective dental preparation instrument.
Implementation Method 1
The kinetic energy of the air causes a force impact on the blades of the rotor by momentum exchange
Implementation Method 2
the turbine housing has at least one cross-sectional extension between drive blades and the cover surfaces, which is formed by a recess in one of the cover surfaces... and having at least one second distance in axial direction between drive blades and the cover surface in the other region, wherein the second distance is shorter than the first distance
Data Source
AI summary
The invention relates to a rotor (1) having a turbine wheel (3) driven by propellant (TG) in a turbine housing (2), a dental preparation instrument (20) having such a rotor (1) and a method (100) for operating such a preparation instrument (20), wherein at least one part of the propellant (TG) flows back to the gas outlet opening (51) in an inner wall (21) radially orbiting the turbine wheel (3) through a return flow channel (6) after impinging on at least one of the drive blades (31) of the turbine wheel (3) counter to the direction of rotation (DR) of the turbine wheel (3), the inner wall (21) in the segment of a circle (KS) comprises at least one return flow channel (6) extending at least from the gas inlet opening (41) as far as the gas outlet opening (51), which allows at least one part of the propellant (TG) to flow back to the gas outlet opening (51) through the return flow channel (6) after impinging on at least one of the drive blades (31) counter to the direction of rotation (DR) of the turbine wheel (3), wherein, in axial direction (AR), the turbine housing (2) has at least one cross-sectional extension (8) of a surface between drive blades (31) and inner wall (21) as far as the return flow channel (6).