Roller Friction Drive for High-Ratio Torque Without Backlash
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Solution Overview
Problem
Existing power transmission systems fail to efficiently achieve high speed ratios and torque multiplication while maintaining lightweight, low noise, and zero backlash, which are essential for applications like robotic actuators and precision positioning.
Innovation Solution
A friction drive power transmission system utilizing rollers with different diameters, a sun roller, and fixed and outer rings, which allows for adjustable preload and symmetrical contact to achieve high rotational speed ratios and torque multiplication, with options for speed reduction or increase, and includes features like tapered rollers and gear teeth for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power transmission systems are used to achieve high speed ratios, then torque multiplication is obtained, but the system becomes heavy and complex
Solution Approach 1:
The system segments the transmission function into multiple rollers (planet rollers and sun roller) that work in parallel, each contributing to torque multiplication. This segmentation allows achieving high speed ratios without requiring a single heavy transmission component, thereby reducing overall system weight while maintaining torque multiplication capability.
Solution Approach 2:
The planet rollers are nested within the annular race, with the sun roller positioned at the center. This nested arrangement allows compact packaging of multiple transmission elements within a small volume, achieving high torque multiplication without increasing system weight or complexity.
2Power
If conventional power transmission systems are used to achieve high speed ratios, then torque multiplication is obtained, but the device complexity increases
Solution Approach 1:
The rollers serve multiple functions simultaneously: they transmit torque, provide speed ratio multiplication, and act as structural elements within the compact nested arrangement. This multi-functionality reduces the number of separate components needed, thereby simplifying the overall device structure while achieving high torque multiplication.
Solution Approach 2:
The system merges the functions of multiple transmission elements into a unified nested structure where planet rollers and sun roller work together within a single annular race. This merging reduces the number of separate housings and support structures needed, simplifying the device complexity while maintaining high speed ratio capability.
3Power
If conventional power transmission systems are used, then power transmission is achieved, but backlash and noise increase
Solution Approach 1:
The system uses curved rolling contact surfaces between the rollers and the annular race, replacing traditional gear teeth with curved friction surfaces. This curvature enables smooth rolling motion without the discrete engagement and disengagement of gear teeth, eliminating backlash and significantly reducing noise during power transmission.
Solution Approach 2:
The system replaces the traditional gear meshing mechanism with a friction-based rolling contact system. Instead of relying on interlocking gear teeth that produce backlash and noise, the curved surfaces roll against each other, providing smooth power transmission without the harmful effects of gear engagement.
4Measurement precision
If precision positioning is required, then positioning accuracy must be maintained, but the system cannot handle over-torque scenarios
Solution Approach 1:
The system converts the potential harm of over-torque scenarios into a beneficial feature by allowing the friction contact to slip when torque exceeds the friction limit. This controlled slip prevents damage to precision components while maintaining positioning accuracy during normal operation, as the friction interface naturally protects against overload without compromising precision positioning capability.
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 system provides high rotational speed ratios, torque multiplication, low noise, and zero backlash, making it suitable for robotic and medical applications, with the ability to handle over-torque scenarios and maintain precision positioning.
Implementation Method 1
rollers, each roller having a first portion of a first diameter and a second portion of a second diameter, a fixed outer ring arranged in rolling contact with the respective first portion of each roller, and an outer drive or driven ring arranged in rolling contact with the respective second portion of each roller
Implementation Method 2
A friction drive power transmission system utilizing rollers with different diameters, a sun roller, and fixed and outer rings
Data Source
AI summary
A high speed ratio drive system is formed of planet rollers, each having varying diameter, an outer fixed ring in contact with one diameter of the planet rollers, and an outer drive ring in contact with another diameter of the planet rollers. An inner drive element is provided by a sun drive roller in contact with the planet rollers or by a planet carrier. Preferably the system has an axial reflective symmetry minimizing twisting forces on the planet rollers.