Power-Split CVT with Integrated Variator and Planetary Gears
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Solution Overview
Problem
Existing continuously variable transmission (CVT) systems face limitations in configuration complexity and design compactness, with high component loads and variator loads, which hinder efficient power-splitting and starting processes.
Innovation Solution
A power-split continuously variable transmission device featuring two planetary gear sets and three shift elements, where the variator unit is integrated to provide a simple and compact design with low transmission losses, allowing power to be implemented via the variator in all modes, and utilizing a mechanical variator like NuVinci for efficient power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a power-split transmission structure with planetary gear sets is used, then the gear ratio spread is expanded and starting process is enabled, but the device complexity increases
Solution Approach 1:
The patent combines a variator unit with two planetary gear sets (first and second planetary gear sets) into an integrated power-split transmission system. The variator unit merges with the planetary gear sets through shared power paths, where power can flow through the variator, planetary gear sets, and back to the variator, creating a unified structure that achieves both continuous variable transmission and expanded gear ratio spread without proportionally increasing complexity
Solution Approach 2:
The variator unit serves multiple functions simultaneously: it provides continuous variable transmission ratio control, guides power along multiple paths, and enables power return to itself through the planetary gear sets. The planetary gear sets also serve dual purposes by enabling both gear ratio expansion and starting process capability while maintaining structural integration
2Volume of moving object
If multiple planetary gear sets and shift elements are integrated, then the transmission becomes more compact, but the manufacturing complexity increases
Solution Approach 1:
The patent arranges the first and second planetary gear sets in a nested configuration where they share common components and power paths. The variator unit is integrated with the planetary gear sets such that power flows through interconnected paths, allowing compact packaging of multiple transmission functions within a reduced volume while maintaining manufacturability through standardized component interfaces
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 achieves a compact, efficient transmission with low component loads and variator load, enabling flexible mode selection and reduced transmission losses, suitable for motor vehicle drive trains with improved starting capabilities and reduced complexity.
Implementation Method 1
The power transmission takes place, without conversion of the form of energy, in a force-locking manner, by way of the friction-locking contact of two or more contact bodies which are moving relative to each other and which are usually referred to as a primary and a secondary disk
Data Source
AI summary
A variator unit of a power-split continuously variable transmission is fixed to a rotationally fixed component and has a primary side rotationally fixed to an input shaft and a secondary side rotationally fixed to a first element of a second planetary gear set via a third shaft. A third element of a first planetary gear set is rotationally fixed via a fourth shaft to a second element of the second planetary gear set, which is fixable to the rotationally fixed component via a first shift element and connectable to the input shaft via a second shift element. A third element of the second planetary gear set is rotationally fixed via a fifth shaft to a first element of the first planetary gear set fixable to the rotationally fixed component via a third shift element. The second element of the first planetary gear set is rotationally fixed to an output shaft.