CVT Skew Control and Axial Force Balancing
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Solution Overview
Problem
There is a need for improved performance and operational control in continuously variable transmissions (CVTs) with existing variators and control systems, particularly in achieving precise speed ratios and managing axial forces effectively.
Innovation Solution
The implementation of a skew-based control system that utilizes tiltable axes of rotation for traction planets, with a control reference source providing desired operating conditions and a skew dynamics module to adjust planet axles, along with a neutralizer assembly to balance axial forces, allowing for precise speed ratio adjustments and efficient torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control system is added to adjust the speed ratio in a CVT, then the desired speed ratio can be achieved, but the device complexity increases
Solution Approach 1:
The CVT system uses its own operating parameters (input speed, output speed, torque) to automatically adjust the speed ratio through the variator, eliminating the need for external control systems. The system self-regulates by utilizing the relationship between torque, speed, and variator geometry to maintain optimal operating conditions
Solution Approach 2:
The patent implements a feedback mechanism where the actual speed ratio is continuously monitored and compared with the desired ratio, and the variator automatically adjusts its configuration based on this feedback to achieve precise speed ratio control without complex external control systems
2Measurement precision
If the variator structure is made more complex to achieve precise speed ratio adjustment, then the speed ratio control improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent achieves precise speed ratio control by changing the geometric parameters of the variator (such as the angle between transmission discs and power rollers, or the radii of contact points) rather than increasing structural complexity. By adjusting these parameters within a simplified structure, the system achieves accurate speed ratio control with standard manufacturing tolerances
3Loss of energy
If axial forces in the CVT are not balanced, then the structure becomes simpler, but the energy loss increases
Solution Approach 1:
The patent introduces counterbalancing elements that generate forces opposite to the axial forces produced by the variator. These counterweights or balancing mechanisms offset the axial forces, reducing energy loss from friction and misalignment without requiring complex active control systems
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 solution enhances the control and performance of CVTs by enabling precise speed ratio adjustments and balancing axial forces, leading to improved operational efficiency and reduced energy loss.
Implementation Method 1
a skew dynamics module to adjust planet axles... allowing for precise speed ratio adjustments
Implementation Method 2
a neutralizer assembly to balance axial forces... leading to improved operational efficiency and reduced energy loss
Implementation Method 3
The input disc applies input torque at an input rotational speed to the speed adjusters. As the speed adjusters rotate about their own axes, the speed adjusters transmit the torque to the output disc.
Data Source
AI summary
Inventions are directed to components, subassemblies, systems, and/or methods for continuously variable transmissions (CVT). In one aspect, a control system is adapted to facilitate a change in the ratio of a CVT. A control system includes a control reference nut coupled to a feedback cam and operably coupled to a skew cam. In some cases, the skew cam is configured to interact with carrier plates of a CVT. Various inventive feedback cams and skew cams can be used to facilitate shifting the ratio of a CVT. In some transmissions described, the planet subassemblies include legs configured to cooperate with the carrier plates. In some cases, a neutralizer assembly is operably coupled to the carrier plates. A shift cam and a traction sun are adapted to cooperate with other components of the CVT to support operation and/or functionality of the CVT. Among other things, shift control interfaces for a CVT are described.