Toroidal CVT Thrust Bearing Gap for Shaft Misalignment
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Solution Overview
Problem
In toroidal continuously variable transmissions, misalignment between the axis of the fitting hole and the variator shaft during assembly can lead to bending stress and eccentric loads on support parts, such as the thrust bearings and driving shaft, due to the positional accuracy dependencies of the variator shaft and thrust bearing.
Innovation Solution
A predetermined gap is introduced between the thrust bearing and the fitting hole or output side disc, allowing for alignment and absorption of misalignment, thereby preventing bending stress and eccentric loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thrust bearing is fitted tightly into the fitting hole to ensure positional accuracy, then the support stability is improved, but misalignment between the variator shaft axis and thrust bearing axis causes bending stress and eccentric loads
Solution Approach 1:
The patent changes the fit parameter from tight fit to loose fit by providing a predetermined gap between the thrust bearing outer peripheral surface and the fitting hole inner peripheral surface. This parameter change allows the thrust bearing to be positioned centrally in the fitting hole without requiring tight tolerance, thereby preventing bending stress and eccentric loads while maintaining adequate positional accuracy for normal operation.
2Reliability
If the variator shaft and thrust bearing are supported with high positional accuracy to prevent misalignment, then the reliability is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the fitting hole into two functional zones: a lower portion that provides lateral support to the thrust bearing, and an upper portion that forms a clearance space. This segmentation allows the thrust bearing to be supported adequately for reliability while avoiding the need for complex high-precision fitting structures, thereby reducing device complexity and manufacturing difficulty.
3Stability of the object's composition
If a tight fit is used between the thrust bearing and fitting hole to prevent misalignment, then the positional stability is improved, but the ease of assembly deteriorates due to difficulty in centralizing the thrust bearing
Solution Approach 1:
The patent introduces a predetermined gap as an intermediary space between the thrust bearing and the fitting hole. This gap acts as a mediator that allows the thrust bearing to be easily inserted and centered in the fitting hole during assembly, while still providing adequate lateral support through the lower portion of the fitting hole to maintain positional stability during operation.
Data Source
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AI summary
Provided is a toroidal continuously variable transmission capable of preventing the application of bending stress to a variator shaft during rotation and the application of an eccentric load to each of support parts even when misalignment between the axis of a fitting hole formed in a post and the axis on which the variator shaft is supported occurs. A thrust bearing 12 which determines the position of an output side disc 10 in an axial direction and rotatably supports the output side disc 10 is fitted into a fitting hole 62b provided in a post 61, and a predetermined gap S is provided between the thrust bearing 12 and the fitting hole 62b in a direction perpendicular to the variator shaft 3. Therefore, even when misalignment between the axis of the fitting hole and the axis on which the variator shaft is supported occurs, the axes of the thrust bearing 12 and the variator shaft 3 can be aligned with each other in the predetermined gap S, thereby preventing the application of bending stress to the variator shaft 3 during rotation and the application of an eccentric load to each of support parts.