Balanced Split Sun Assemblies with Torque Balancing Differential Mechanisms
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Solution Overview
Problem
In ball planet-planetary continuously variable transmissions (CVTs), the uneven surface speeds between two sun rolling elements lead to sliding, reducing power transfer efficiency, causing heat buildup, noise, vibration, and abrasive effects, which shorten the lifespan and reduce the power capacity of the variator.
Innovation Solution
A torque balancing differential mechanism is introduced between the two sun rolling elements, allowing them to rotate at different speeds while applying equal torque, thereby preventing sliding and ensuring efficient power transfer to the ball planets, which reduces heat buildup and increases the efficiency and lifespan of the CVT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two sun rolling elements are positioned with axial separation and forced to rotate at the same speed, then the structure is simplified, but sliding occurs between contacts which reduces power transfer efficiency and causes heat buildup
Solution Approach 1:
The patent applies the dynamics principle by allowing the two sun rolling elements to rotate at different speeds through a differential mechanism, rather than forcing them to rotate at the same speed. This dynamic adjustment eliminates sliding between contacts while maintaining structural feasibility, thereby resolving the contradiction between structural simplicity and power transfer efficiency.
Solution Approach 2:
The patent introduces a differential mechanism as an intermediary between the two sun rolling elements. This intermediary device enables the rolling elements to rotate at different speeds while still being driven by the same input, preventing sliding and improving power transfer efficiency without requiring complete structural redesign.
2Force
If two sun rolling elements are positioned with axial separation, then torque distribution can be balanced, but sliding occurs when they rotate at different speeds causing heat buildup and noise
Solution Approach 1:
The differential mechanism enables dynamic speed adjustment of the two sun rolling elements, allowing them to rotate at different speeds that match their respective contact conditions with ball planets. This eliminates sliding while maintaining balanced torque distribution, thereby preventing heat buildup and noise generation.
3Object-affected harmful factors
If sliding is prevented by forcing sun rolling elements to rotate at the same speed, then sliding is reduced, but torque distribution becomes unbalanced and power capacity is limited
Solution Approach 1:
The differential mechanism serves as an intermediary that reconciles the conflicting requirements of sliding prevention and torque balance. It allows each sun rolling element to rotate at the optimal speed for its contact condition, preventing sliding while maintaining balanced torque distribution, thereby maximizing power capacity.
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 torque balancing differential mechanism effectively transfers power with minimal sliding, reducing heat and abrasive effects, thereby enhancing the efficiency and power capacity of the CVT and extending the life of the traction fluid.
Implementation Method 1
A torque balancing differential mechanism is introduced between the two sun rolling elements, allowing them to rotate at different speeds while applying equal torque
Implementation Method 2
contact between the two sun rolling elements and the ball planets may be direct contact, or there may be an intermediary fluid between the two sun rolling elements and corresponding points on the ball planets
Implementation Method 3
the sun has two rolling elements, each in contact with the ball planets
Data Source
AI summary
A balanced split sun assembly with an integrated differential mechanism allows power to be transferred from a sun assembly to a plurality of ball planets, or allows power to be transferred from a plurality of ball planets to a sun assembly, while minimizing sliding, spin, axial pull, or other unwanted effects on the sun assembly. A differential mechanism, including offset mechanisms, allows torque to be divided between multiple split sun rolling elements. Variations in design of a split sun assembly allow for ease of manufacture, ease of assembly, and ease of adjustment.