Multistage Friction Drive for Zero-Backlash Speed Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high-performance speed adapters, such as toothed gears, suffer from noise, vibrations, and reduced control performance due to tooth bending and backlash, which limit speed and positioning accuracy, and are costly to manufacture.
Innovation Solution
The use of friction or traction drives with smooth, toothless surfaces in rolling contact, employing guided rollers and a sun element with planet elements to achieve a fixed gear ratio, providing high stiffness, low backlash, and efficient speed reduction with optional position sensors for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If toothed spur or helical gears are used for speed adaptation, then torque and speed can be adapted between motor and load, but noise and vibrations occur due to discontinuous meshing and rigidity fluctuation, limiting allowable speed
Solution Approach 1:
The invention extracts and eliminates the teeth from the gear system, replacing traditional toothed meshing with smooth surface friction contact. This removes the source of discontinuous engagement and rigidity fluctuation that causes noise and vibrations, allowing for higher operating speeds without these harmful effects
Solution Approach 2:
The invention substitutes the mechanical toothed meshing system with a friction-based contact system. Instead of relying on interlocking teeth that engage and disengage, the system uses continuous friction contact between smooth surfaces to transmit power, eliminating the mechanical discontinuities that generate noise and vibration
2Ease of operation
If toothed gears with backlash are used to allow proper function, then gear operation is enabled, but control performance and positioning accuracy are reduced
Solution Approach 1:
The invention removes the backlash inherent in toothed gear systems by eliminating the teeth themselves. The smooth surface friction contact maintains continuous engagement without the gaps and play that characterize toothed gears, thereby preserving positioning accuracy while still enabling proper gear operation
Solution Approach 2:
Instead of accepting backlash as a necessary compromise for gear operation, the invention inverts the approach by using friction contact that naturally maintains continuous pressure and engagement. The system works in reverse logic to traditional gears: rather than tolerating gaps, it uses sustained surface contact to eliminate them entirely
3Measurement precision
If strain wave gearing is used to achieve compact drive with no backlash, then compactness and zero backlash are achieved, but flexibility is introduced reducing control performance
Solution Approach 1:
The invention extracts the flexibility issue from the zero-backlash solution by removing the elastic deformation mechanism entirely. Instead of using a flexible cup that deforms elastically to engage with the annulus gear, the system uses rigid smooth surfaces in friction contact, achieving zero backlash through continuous pressure contact rather than elastic compliance
Solution Approach 2:
The invention substitutes the elastic deformation mechanism of strain wave gearing with a friction-based contact mechanism. Rather than relying on material elasticity to maintain engagement, the system uses friction between rigid smooth surfaces to transmit power, eliminating the flexibility that degrades control performance while maintaining zero backlash
4Measurement precision
If cycloidal gear with preloads is used to achieve close to zero backlash, then positioning accuracy is improved, but manufacturing requires precision techniques that are challenging and costly
Solution Approach 1:
The invention extracts the complex tooth geometry from the system, replacing it with simple smooth cylindrical surfaces. This eliminates the need for precision tooth profiling and complex manufacturing techniques, allowing standard machining methods to be used while maintaining positioning accuracy through friction-based continuous contact
Solution Approach 2:
The invention changes the fundamental geometric parameters from complex toothed profiles to simple smooth cylindrical surfaces. This parameter change simplifies manufacturing significantly, as smooth surfaces can be produced with standard turning and grinding operations, while the friction contact mechanism preserves the positioning accuracy benefits
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
These drives offer high-speed regulating accuracy, smooth torque transfer, and low or zero backlash, enabling high-performance servo mechanisms with reduced noise and vibrations, while maintaining efficient contact forces to minimize material fatigue and energy losses.
Implementation Method 1
A friction drive relies on friction between elements in rolling contact
Implementation Method 2
A traction drive, on the other hand, transmits the efforts through the shearing of a lubricant—typically a traction lubricant which, under high contact pressures, forms solid films that protect surfaces and provide traction
Data Source
AI summary
A multistage friction/traction speed adapter having a first drive which can include a plurality of free rollers orbiting around a sun element within a frame, transmitting their orbiting movement to guided rollers which do not contact the sun element or the frame. The guided rollers are driven in the orbiting movement and transmit the rotary movement to a carrier via corresponding pins which engage with the carrier. A second drive can include rollers having radial position variation which is prevented from being transmitted to the carrier by providing accommodation at the pin level, either by providing a bushing around the pins with a bore that is eccentric relative to its outer surface, either by engaging the pins into the carriers in portions thereof which are made more flexible. A friction/traction gear at an angle is also disclosed.