Asymmetric Toroidal CVT Geometry for Wider Ratio Range
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Solution Overview
Problem
Conventional toroidal traction Continuously Variable Transmissions (CVTs) have limited velocity and torque ratio ranges, typically between 2:1 to 2.65:1, which restricts their application and efficiency, especially in requiring wider ratio ranges.
Innovation Solution
The development of asymmetric toroidal traction CVTs with uniquely shaped input and output wheels and variator wheels that pivot within a toroidal cavity, allowing for a broader range of velocity and torque ratios up to 0.8:1 to 5:1 by varying the angle of the variator wheels and controlling the traction fluid film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional symmetrical toroidal CVTs are used, then the structure is simple and easy to manufacture, but the velocity and torque ratio range is limited to 2:1 to 2.65:1
Solution Approach 1:
The patent applies asymmetry by designing the input wheel and output wheel with different geometries. The input wheel has a first geometry while the output wheel has a second geometry that is different from the first. This asymmetric configuration enables the transmission system to achieve a broader velocity and torque ratio range (up to 0.8:1 to 5:1) compared to conventional symmetrical designs, while maintaining structural feasibility through deliberate geometric differentiation rather than complex additional components
2Adaptability or versatility
If the variator wheel pivot position is fixed at the center, then the structure is stable, but the ratio range is limited
Solution Approach 1:
The patent implements dynamics by allowing the variator wheel pivot position to vary within the toroidal cavity rather than being fixed at the center. The pivot position can move between a first position and a second position, enabling continuous adjustment of the velocity and torque ratio. This dynamic configuration allows the system to achieve a superior ratio range (0.8:1 to 5:1) while maintaining operational stability through controlled pivot movement within defined boundaries
3Adaptability or versatility
If multiple stages of CVTs are connected to achieve wider ratio ranges, then the ratio range is improved, but the device complexity and loss of energy increase
Solution Approach 1:
The patent combines multiple functional elements into a single integrated toroidal transmission system. The asymmetric input wheel, asymmetric output wheel, and variator wheel with movable pivot are merged into one cohesive mechanism that achieves a broad ratio range (0.8:1 to 5:1) in a single stage. This eliminates the need for multiple sequential CVT stages or supplementary gear arrangements, thereby reducing cumulative energy losses and improving overall power transmission efficiency
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 design enables a superior ratio range compared to traditional systems, allowing for more efficient power transmission and reducing the risk of physical contact between wheels, thereby enhancing the transmission's operational flexibility and reliability.
Implementation Method 1
Traction Toroidal Transmissions transmit power between the wheels by shearing action of traction fluid trapped between the wheels without actual physical contact
Implementation Method 2
allowing for a broader range of velocity and torque ratios up to 0.8:1 to 5:1 by varying the angle of the variator wheels and controlling the traction fluid film thickness
Data Source
AI summary
An input shaft being configured into spline engagement with an input wheel wherein the input wheel slides axially along the input shaft; an output shaft into engagement with the input shaft, and wherein an output wheel is configured to slide axially along said output shaft; a variator wheel being configured to drive the input wheel or output wheel without direct contact; a traction fluid to enable the variator wheel to drive at least one of the input wheel and output wheel without direct contact; a toroidal cavity for containing the traction fluid and form an enveloping toroidal cavity when the input wheel and output wheel are aligned together; and an actuator tier controlling the axial sliding of the input and output wheel on their respective splined shafts.