Continuously Variable Transmission Shifter Assembly Dynamics
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Solution Overview
Problem
Ball-type rolling traction continuously variable transmissions (CVTs) face technical and economic hurdles, limiting their wider adoption across various industrial applications, including automotive sectors due to inefficiencies and adaptability issues.
Innovation Solution
The development of a drive system incorporating a continuously variable unit (CVU) with a prime mover, transmission, and hydraulic and lubrication systems, featuring a parallel branch for mechanical power transmission, traction rollers, and a shifter assembly for adjusting the axis of rotation, along with a planetary gearset and axial force generator to enhance torque transfer and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ball-type rolling traction CVT is used, then continuous variable transmission is achieved, but efficiency and adaptability are insufficient
Solution Approach 1:
The patent employs dynamic adjustment mechanisms including a shifter assembly that adjusts the axis of rotation of traction rollers, and a variable geometry impeller that changes blade angle according to operating conditions. These dynamic elements allow the transmission to adapt continuously to varying load and speed requirements, resolving the contradiction between adaptability and efficiency by enabling real-time optimization of power transmission characteristics.
Solution Approach 2:
The system utilizes parameter changes through variable displacement pumps and motors, adjustable traction roller dimensions, and variable geometry impellers. By continuously varying geometric parameters such as roller radius, blade angle, and displacement volume, the transmission achieves both high adaptability to different operating conditions and maintained efficiency through optimal parameter selection at each operating point.
2Reliability
If traditional CVT configuration is used, then power transmission is achieved, but efficiency is insufficient
Solution Approach 1:
The patent incorporates hydraulic systems including variable displacement pumps, hydraulic motors, and fluid coupling elements. These hydraulic components enable efficient power transmission by utilizing fluid dynamics to transfer energy with minimal losses, while the variable displacement capability allows optimization of hydraulic flow and pressure to maintain high efficiency across varying power transmission requirements.
Solution Approach 2:
The system employs fluid phase transitions and elastohydrodynamic lubrication in the traction contact zones. By maintaining optimal lubrication regimes and utilizing fluid properties under varying pressure and temperature conditions, the transmission achieves high efficiency in power transmission while accommodating variable load and speed conditions through controlled phase behavior of transmission fluids.
3Adaptability or versatility
If ball-type rolling traction mechanism is used, then continuous variable ratio is achieved, but device complexity increases
Solution Approach 1:
The patent designs multi-functional components where single elements perform multiple functions. For example, the traction rollers serve both as power transmission elements and as variable ratio control mechanisms. The shifter assembly simultaneously adjusts roller position and axis orientation to achieve continuous variable ratio while maintaining a relatively compact and simplified overall structure, reducing device complexity despite continuous variable capability.
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 configuration improves the efficiency and adaptability of ball-type rolling traction CVTs, enabling their use in automotive applications by providing a more robust and efficient mechanical power transmission system.
Implementation Method 1
a hydraulic system operably coupled to the shifter assembly
Implementation Method 2
a lubrication system configured to provide lubricant to at least the traction rollers
Implementation Method 3
The input element includes a load cam and a traction ring that each has bidirectional load cam ramps
Data Source
AI summary
Components, subassemblies, systems, and/or methods for continuously variable transmissions (CVT) having a variator provided with a plurality of tilting, traction planets and traction rings are described. In one embodiment, a variator is coupled to a rangebox to provide multiple operating modes. In another embodiment, a hydraulic system is configured to control the transmission ratio of the variator and the rangebox. Shift-cam-and-sun subassemblies can be used to facilitate shifting of the transmission ratio of a CVT. A transmission housing and bell housing can be adapted to house components of a CVT and, in some embodiments, to cooperate with other components of the CVT to support operation and/or functionality of the CVT. Related devices include, for example, a pivot arm, a control feedback mechanism, axial force generation and management mechanisms, a control valve integral with an input shaft, a pivot pin hub, and a rotatable carrier configured to support planet-pivot arm assemblies.