Orbital Roller Speed Changer for High-Torque Zero-Backlash Reduction
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Solution Overview
Problem
Gear transmission speed change devices are complex, exhibit backlash, gear noise, and require multiple stages for high reduction ratios, while traction drive systems offer less torque and complexity in achieving desired efficiency and torque output.
Innovation Solution
A speed change device comprising an inner race, an outer race, and a set of orbital rollers with specific friction coefficients and angles, allowing for rolling contact and self-energizing torque transfer, enabling high torque, zero backlash, and efficient speed change with a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If gear transmission is used, then high torque is achieved, but device complexity increases and backlash occurs
Solution Approach 1:
The device segments the torque transmission function into multiple independent roller elements distributed around the inner and outer races. Each roller independently transmits torque through rolling contact, eliminating the need for complex interconnected gear mechanisms while maintaining high torque capacity through distributed load sharing across multiple rollers.
Solution Approach 2:
The rollers serve as intermediary elements between the inner and outer races, transferring torque through pure rolling contact. This intermediary mechanism eliminates direct gear-to-gear contact, thereby preventing backlash while maintaining efficient torque transmission through the roller-mediated rolling interface.
2Force
If gear transmission is used, then high torque is achieved, but gear noise is generated
Solution Approach 1:
The invention replaces the traditional gear meshing mechanism with a rolling contact system. The rollers transmit torque through rolling motion between the inner and outer races, substituting the noisy sliding and impact interactions of gear teeth with quiet rolling contact, thereby eliminating gear noise while maintaining torque transmission capability.
3Speed
If multiple stages are used for high reduction ratio, then speed change ratio is improved, but device complexity increases
Solution Approach 1:
The device achieves multiple functions within a single stage: the same roller-based rolling contact mechanism simultaneously provides torque transmission, speed reduction, and compact structural integration. By making the rolling contact system multi-functional, the invention eliminates the need for multiple separate stages that would otherwise be required to achieve high reduction ratios, thereby reducing overall device complexity.
4Device complexity
If traction drive is used, then device complexity is reduced, but torque capacity decreases
Solution Approach 1:
The traction drive system is segmented into multiple discrete roller elements distributed around the races. This segmentation allows the simple rolling contact mechanism to be scaled up in torque capacity by increasing the number of rollers, thereby maintaining device simplicity while overcoming the torque limitation of single-element traction drives through distributed load sharing.
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 provides high torque capacity, zero backlash, and efficient speed change with a compact design, achieving high torque for size and weight, while maintaining low friction and vibration, and allowing for precise control and integration of motors.
Implementation Method 1
inner rollers in rolling contact with the outer surface of the inner race and outer rollers in rolling contact with the inner surface of the outer race
Implementation Method 2
the first inner roller contacts the inner race with a first coefficient of friction cf1 and the first outer roller contacts the outer race with a second coefficient of friction cf2, cf1>tan(ø) and cf2>tan(ø)
Implementation Method 3
the rollers of the orbital rollers have conical faces that contact conical faces of other rollers of the orbital rollers when the rollers are not axially centered
Data Source
AI summary
A speed change device comprising an inner race having an outer surface, an outer race having an inner surface, and set of orbital rollers including inner rollers in rolling contact with the outer surface of the inner race and outer rollers in rolling contact with the inner surface of the outer race.