Continuously Variable Transmission Axial Force Control
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Solution Overview
Problem
Traditional continuously variable transmissions face challenges in generating and controlling axial force effectively, leading to inefficiency and reduced lifespan due to excessive force requirements, especially at varying speed ratios, and existing electric motors struggle to provide constant power at low speeds without increasing size and cost.
Innovation Solution
A variable speed transmission system utilizing a plurality of tiltable balls with a rotatable idler and axial force generator, along with an integrated electric motor or generator, to manage axial force and maintain efficient power transmission across varying speed ratios, incorporating a cage and idler shaft to support and align the balls, and using magnetic materials for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional iris plates are used to tilt the axis of rotation of traction rollers, then the transmission ratio can be adjusted, but the device complexity increases significantly due to the large number of parts required
Solution Approach 1:
The patent combines the functions of multiple separate components into a single integrated structure. The guide ring is merged with the support structure for the traction rollers, eliminating the need for separate iris plates and reducing the number of parts while maintaining the ability to adjust transmission ratio.
Solution Approach 2:
The guide ring serves multiple functions simultaneously: it guides the traction rollers, supports the support structure, and enables transmission ratio adjustment. This multi-functional design replaces what would traditionally require multiple separate components.
2Device complexity
If a stationary guide ring is used to support traction rollers, then the structure is simplified, but shifting the axis of rotation of traction rollers becomes difficult
Solution Approach 1:
The patent introduces dynamic capability to the previously stationary guide ring. The guide ring is designed to move axially, allowing the support structure and traction rollers to shift positions. This axial movement enables the axis of rotation of the traction rollers to be shifted while maintaining structural simplicity.
3Reliability
If excessive axial force is applied to prevent slippage at low speeds, then frictional contact is maintained, but efficiency decreases and transmission lifespan is reduced
Solution Approach 1:
The axial force generation is made dynamic rather than constant. The axial force varies with the transmission ratio, providing sufficient force to prevent slippage at low speeds while reducing the force at high speeds and 1:1 ratio, thereby maintaining reliability while improving efficiency.
Solution Approach 2:
The patent changes the parameter of axial force from a constant value to a variable value that depends on the transmission ratio. This parameter change allows the system to optimize the balance between preventing slippage and maintaining efficiency across different operating conditions.
4Force
If a bigger electric motor is used to provide sufficient low speed torque, then torque requirement is met, but cost, size, weight, and packaging difficulty increase
Solution Approach 1:
The patent introduces a continuously variable transmission as an intermediary mechanism between the electric motor and the load. This transmission multiplies the torque at low speeds, allowing a smaller motor to provide sufficient low speed torque by mechanically amplifying the force through the variable ratio transmission system.
Solution Approach 2:
Instead of increasing the motor size to provide low speed torque, the patent replaces this approach with a mechanical transmission system that provides torque multiplication. This substitution allows the motor to remain small while still meeting the low speed torque requirements through mechanical advantage.
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 system achieves improved efficiency and extended lifespan by dynamically adjusting axial force based on transmission ratio and provides constant power across a wide range of speeds without the need for excessive force or motor size increases, integrating seamlessly with electric motors for enhanced performance.
Implementation Method 1
rolling traction continuously variable transmissions require more axial force at low speed to prevent the driving and driven rotating members from slipping on the speed changing friction balls
Implementation Method 2
an electrical stator configured to rotate about said axis, wherein the electrical stator is directly coupled to one of the first disc, second disc, or idler
Implementation Method 3
using magnetic materials for enhanced performance
Data Source
AI summary
A transmission having a plurality of tilting balls and opposing input and output discs provides an infinite number of speed combinations over its transmission ratio range. The transmission provides multiple powerpaths and can be combined with electrical components to provide motor/generator functionality, which reduces the overall size and complexity of the motor and transmission compared to when they are constructed separately. In one embodiment, rotatable components of a continuously variable transmission are coupled separately to an electrical rotor and to an electrical stator so that the rotor and stator rotate simultaneously in opposite directions relative to one another. In other embodiments, an electrical rotor is configured to transfer torque to or from a disc that is in contact with a plurality of speed adjusters, while an electrical stator is configured to transfer torque to a shaft that is operationally coupled to the speed adjusters via an idler.