Cycloid Roller Transmission With Variable Diameter for Low Torque Ripple
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Solution Overview
Problem
Current transmission systems face challenges in achieving high efficiency, power/torque rating, and extended lifetime while maintaining a compact form factor, particularly in applications requiring torque and rotational speed conversion with reduced vibration and torque ripple.
Innovation Solution
The proposed transmission system incorporates a sun gear, planet gears, cams, eccentric members, and rollers with variable-width cutouts, allowing for precessional rotation and rolling motion to achieve efficient torque conversion, with additional transmissions phased to reduce vibration and torque ripple, and mid-plane constraining elements to maintain optimal roller alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional transmission systems are used to achieve torque and rotational speed conversion, then basic transmission function is provided, but efficiency is reduced, power capacity is limited, and lifetime is shortened due to vibration and torque ripple
Solution Approach 1:
The transmission system is divided into multiple independent roller elements (at least three rollers) that separately engage with the eccentric member and ground member. Each roller independently transmits force, distributing the load and reducing vibration and torque ripple while maintaining high transmission efficiency
Solution Approach 2:
The rollers are designed with variable effective diameter through variable-width cutouts in the eccentric member and ground member. The effective diameter of each roller changes during its rotation cycle, optimizing the transmission ratio dynamically and reducing harmful vibrations while improving overall transmission efficiency
2Weight of moving object
If transmission size and weight are reduced for compact form factor, then space requirements are minimized, but power capacity and load bearing capability are reduced
Solution Approach 1:
The rollers are designed with non-uniform cross-sections featuring variable-width cutouts that create locally optimized effective diameters. This allows different regions of each roller to have different load-bearing characteristics, enabling compact roller dimensions while maintaining high power capacity through optimized local stress distribution
Solution Approach 2:
The variable effective diameter of the rollers during rotation creates dynamic load distribution. As each roller rotates, its effective diameter changes, allowing the compact roller structure to adaptively handle varying loads and maximize power capacity within limited space
3Reliability
If service lifetime is extended through improved durability, then reliability is enhanced, but transmission complexity increases
Solution Approach 1:
The variable-width cutouts in the rollers and mating members automatically adjust the effective diameter during operation based on the rotational position. This self-adjusting mechanism optimizes load distribution and reduces wear without requiring external control systems or complex adjustment mechanisms
Solution Approach 2:
The variable effective diameter function and the transmission elements are merged into a unified structure where the cutouts are integral to the rollers and mating members. This integration eliminates separate adjustment mechanisms and reduces overall system complexity while extending service lifetime
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 configuration enhances transmission efficiency, power capacity, and service lifetime while reducing size and weight, and effectively mitigates torque ripple and vibration, making it suitable for various industrial and robotic applications.
Implementation Method 1
rotation of the input member results in rotation of the eccentric member, whereby the rotation of the input member causes rotation of the output member
Implementation Method 2
two or more cams, each one of the two or more cams being coupled to a respective one of the two or more planet gears such that rotation of the sun gear results in rotation of each of the two or more cams
Implementation Method 3
two or more planet gears that are in geared contact with the sun gear
Data Source
AI summary
A variety of transmissions, and improvements thereof, are provided having improved efficiency and other benefits. The transmissions include one or more inner members that are driven by one or more cams or other means to engage in precessional rotation about an axis of rotation that, itself, orbits about a primary axis of rotation. A plurality of shaped rollers are in contact with shaped cutouts on the inner member(s) and on a ground member such that an input rotation/torque applied via the cam is realized as an output rotation/torque at an output member that is coupled to the inner member(s). Tire rollers and contact surfaces are shaped such that the rollers engage in rolling motion relative to the contact surfaces, providing improved efficiency. Multiple inner members, and corresponding sets of shaped rollers, can be provided to increase power capacity, reduce torque ripple, reduce wobble, or provide other benefits.