Epicyclic Belt Drive Layout for High-Torque Wheel Transmission
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Solution Overview
Problem
Existing epicyclic gears with belt or traction mechanisms face challenges such as complex construction, reduced service life due to belt twisting and pressure, limited power transmission capacity, and high maintenance requirements, making them unsuitable for high torque applications.
Innovation Solution
The design features multiple belt drives with parallel shaft alignment, allowing for high power transmission without belt twisting, and incorporates a differential gear mechanism using toothed belts that reverse rotation direction, enabling efficient torque transmission with reduced friction and weight, suitable for motor vehicle drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a belt is used to connect sun gear and planetary gears in an epicyclic gear, then the construction becomes lightweight and maintenance-free, but the service life is reduced due to differences in peripheral speed causing disadvantageous force and tension conditions
Solution Approach 1:
A tensioning device is introduced as an intermediary component between the belt and the planetary gears. This tensioning device actively adjusts the belt tension to compensate for speed differences between the sun gear and planetary gears, maintaining optimal force and tension conditions throughout the belt's service life, thereby resolving the reliability issue while preserving the lightweight construction advantage
2Power
If the belt is pressed against the ring gear to achieve torque transmission, then power transmission is enabled, but the belt experiences increased load and friction leading to reduced service life
Solution Approach 1:
The tensioning device provides dynamic adjustment of belt tension rather than static pressing. This allows the belt tension to be optimized in real-time based on operating conditions, enabling sufficient torque transmission while preventing excessive loads that would reduce service life. The dynamic control ensures the belt is only as tight as necessary for power transmission
3Shape
If the drive belt is twisted by 90 degrees to redirect it between planet and sun gears, then the spatial arrangement is achieved, but the side areas of the belt are particularly stressed reducing service life
Solution Approach 1:
The tensioning device acts as a mediator that compensates for the stress concentration caused by the 90-degree twist. By actively adjusting belt tension in the twisted section, it prevents excessive stress on the belt's side areas while maintaining the necessary spatial arrangement between planet and sun gears
4Ease of operation
If additional pressure rollers and flanged wheels are added to guide the belts, then the belt path is controlled, but frictional forces and wear increase
Solution Approach 1:
The patent replaces the traditional mechanical guidance system (pressure rollers and flanged wheels) with a tensioning device that controls the belt path through tension adjustment rather than physical contact guidance. This substitution eliminates the frictional forces and wear associated with multiple contact points while maintaining effective belt path control
Data Source
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AI summary
An epicyclic gear transmission with at least three shafts, designed as a belt or traction gear transmission, with a planet carrier or web connected to a first shaft in a rotationally fixed manner or via a gearbox for receiving and supporting planet gears, and with two center or sun gears arranged concentrically to the planet carrier and each connected in a rotationally fixed manner to one of the further shafts, wherein: - the shafts connected to the sun gears and the axes of the planet gears are spatially aligned parallel, - at least two belt drives are provided and each of the sun gears is connected to the planet gears via one of the belt drives, - the belt drives are connected to each other via at least one common planet gear wrapped by their belts in a speed-coupled manner, and that one of the belt drives connecting a sun gear to the planet gears is designed with a belt that circulates forwards and backwards,that, with respect to the planet carrier, the associated sun gear is rotatable in the opposite direction to the rotation of the planet gears, the belt preferably running around the planet gears on the front and the center or sun gear on the back.