Toroidal Variator Roller Mounting for Balanced Contact Loads
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Solution Overview
Problem
Conventional dual toroidal variators with independent roller control mechanisms are costly, complex, and face packaging challenges due to large size and undesirable exterior shapes, leading to issues with drive transfer and durability, especially in high-power density applications like vehicle main-drive transmissions.
Innovation Solution
The variator design features rollers mounted such that disc-roller contact points lie in a plane perpendicular to the radial force from the take-off drive, ensuring balanced normal contact loads and reducing the complexity and weight of the variator, with a dual cavity configuration that allows for more compact and economical manufacturing and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If independent roller control mechanisms are used in conventional dual toroidal variators, then the variator can handle high-power density applications, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines the control of multiple rollers into a single integrated control mechanism. The control assembly includes a pivotable lever that simultaneously controls the tilt of multiple rollers through mechanical linkages, eliminating the need for independent control mechanisms for each roller. This merging approach maintains high-power density capability while significantly reducing device complexity and manufacturing cost.
2Power
If conventional dual toroidal variator design is used, then high-power transmission is achieved, but the exterior shape becomes undesirable and packaging challenges arise
Solution Approach 1:
The patent employs asymmetric arrangement of the toroidal cavities and rollers within the housing. The control assembly is positioned to optimize space utilization, and the rollers are arranged at specific angles and positions that allow for a more compact and aesthetically pleasing exterior shape while maintaining the dual-cavity high-power transmission capability.
3Device complexity
If rollers are mounted with contact points not in a plane perpendicular to radial force, then the variator structure is simpler, but the normal contact loads become unbalanced reducing durability
Solution Approach 1:
The patent applies the principle of local quality by specifically positioning the roller contact points to lie in a plane perpendicular to the radial force from the take-off drive. This localized geometric arrangement ensures that normal contact loads are balanced across all rollers, optimizing durability and performance. The rest of the variator structure can remain relatively simple, achieving reliability without excessive complexity.
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 enhances the efficiency and durability of the variator by balancing reaction torques and reducing manufacturing costs, while providing a more compact and cost-effective solution for high-power density applications without compromising performance.
Implementation Method 1
This has the property of having a viscosity that increases rapidly when its pressure exceeds a threshold. As the races rotate, traction fluid is drawn into the nips formed between the rolling elements and the working surfaces to create a thin layer of traction fluid between the rolling surfaces and the working surfaces
Data Source
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AI summary
A toroidal variator having an input surface and an output surface coaxially mounted for rotation on a shaft defining a variator axis and two rollers in driving engagement with the input and output surfaces, a take-off drive operatively engaged with the output surface and disposed radially of the variator axis whereby a radial contact force perpendicular to and intersecting the variator axis is generated and wherein the rollers are located such that the points of contact of the rollers with the input and output surfaces at one particular ratio within the operating range of the variator lie generally in a plane which is substantially perpendicular to the direction of the radial contact force. This plane lies on or close to the neutral axis of bending of the variator structure whereby both normal contact loads between the discs and the two rollers will be generally the same.