CVT Compression Control via Torque Ratio Estimation
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Solution Overview
Problem
The power transmission efficiency of belt type continuously variable transmissions is difficult to control effectively, particularly in maintaining a desired torque ratio with good responsiveness, leading to inefficiencies and potential slipping issues.
Innovation Solution
A compression control device that estimates the torque ratio using slip identifiers and phase lags, and adjusts axial thrust based on friction coefficients to optimize power transmission, minimizing sensor requirements and improving control responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If torque ratio is indirectly controlled using slip identifier or phase lag, then the control system can operate with simpler parameters, but the responsiveness and precision of torque ratio control deteriorates
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual torque ratio and comparing it with the target torque ratio. The compression control means adjusts the axial thrust based on the deviation between actual and target values, creating a closed-loop control system that improves precision while maintaining manageable complexity.
Solution Approach 2:
The patent changes the control parameter from indirect parameters (slip identifier, phase lag) to direct parameter (actual torque ratio). By directly controlling the torque ratio through axial thrust adjustment based on friction coefficient, the system achieves better precision without excessive complexity.
2Loss of energy
If compression control is applied to improve power transmission efficiency, then transmission efficiency increases, but the risk of power transmission element slipping increases if not properly controlled
Solution Approach 1:
The patent dynamically adjusts the axial thrust parameter based on the friction coefficient and target torque ratio. By changing the compression force according to actual friction conditions and desired torque ratio, the system maximizes power transmission efficiency while preventing slipping through adaptive control.
Solution Approach 2:
The compression control means uses feedback from the friction coefficient estimation and actual torque ratio measurement to adjust axial thrust. This closed-loop control ensures that compression is optimized for efficiency while maintaining sufficient friction to prevent slipping.
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 approach enhances power transmission efficiency by precise control of torque ratios, reduces computation load, and prevents slipping, while learning friction coefficients for improved performance during cruising and varying conditions.
Implementation Method 1
a power transmission element that is in contact with each of the input and output shaft elements and transmits the driving force from the input shaft to the output shaft by virtue of friction in contacting portions
Implementation Method 2
coefficient of friction estimation means that estimates a coefficient of friction between the either one shaft element and the power transmission element
Data Source
AI summary
A compression control device for a continuously variable transmission is provided in which when estimating the torque ratio, which is the ratio of the actually transmitted torque relative to the maximum transmittable torque of the continuously variable transmission, based on the transmission characteristics for transmitting the given variable component of the input shaft to the output shaft via an endless belt, a slip identifier, which is an indicator for the ratio of the amplitude of the variable component between the input shaft and the output shaft, or a phase lag, which is an indicator for difference in phase of the variable component, is used. It is possible to improve the control responsiveness and reduce the computation load of the control device and to improve the power transmission efficiency of the continuously variable transmission while preventing the endless belt thereof from slipping.