CVT Driven Pulley Axial Thrust Control via Friction Coefficient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing CVT control systems struggle to accurately determine the target axial thrust of the driven pulley, leading to potential belt slippage due to insufficient thrust margin, as the peak thrust ratio cannot be determined until belt slippage occurs, necessitating excessive axial thrust settings to prevent slippage.
Innovation Solution
A control apparatus and method for a continuously variable transmission that includes detection blocks for transmission state, axial thrust, and inter-shaft force, a friction coefficient calculation block to determine the radial component of friction coefficients, and an axial thrust control block to set the target axial thrust based on calculated friction coefficients, ensuring appropriate axial thrust levels to prevent belt slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driven pulley axial thrust is set to an excessive value to prevent belt slippage, then belt slippage is prevented, but transmission efficiency deteriorates due to excessive axial thrust
Solution Approach 1:
The invention changes the control parameter from fixed axial thrust values to dynamically calculated friction coefficients. By calculating the friction coefficient between the belt and pulley based on actual operating conditions (axial thrusts, rotational speeds, torques), the system determines the minimum necessary axial thrust to prevent slippage, thereby optimizing transmission efficiency while ensuring reliability.
Solution Approach 2:
The invention implements a feedback control mechanism where the friction coefficient is continuously calculated from measured operating parameters (axial thrusts Q1 and Q2, rotational speeds, torques) and used to adjust the axial thrust control. This closed-loop feedback ensures that axial thrust is maintained at the optimal level needed to prevent slippage without being excessively high, thus improving transmission efficiency.
2Loss of energy
If the margin of axial thrust variation relative to slip safety rate is set to be small, then transmission efficiency is improved, but belt slippage may occur depending on control convergence
Solution Approach 1:
The invention performs preliminary calculation of the friction coefficient based on current operating conditions before adjusting axial thrust. By calculating the friction coefficient from the relationship between axial thrusts, rotational speeds, and torques, the system determines the appropriate axial thrust setting in advance, ensuring both efficiency and slippage prevention without relying on excessive safety margins.
3Reliability
If the peak thrust ratio is used as the control target, then belt slippage can be prevented, but the peak cannot be determined until belt slippage occurs
Solution Approach 1:
The invention inverts the traditional control approach by not directly controlling axial thrust based on detected peak thrust ratio. Instead, it calculates the friction coefficient from measured operating parameters and uses this calculated value to determine target axial thrust. This inversion allows determination of optimal control parameters before slippage occurs, improving both measurement precision and reliability.
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 accurately calculates friction coefficients and sets target axial thrusts, preventing belt slippage while reducing excessive axial thrust, thereby enhancing transmission efficiency and fuel consumption by maintaining optimal axial thrust levels.
Implementation Method 1
a power transmissible member wound around the drive and driven pulleys to be clamped therebetween in response to axial thrust acting along axes of the input and output shafts
Data Source
AI summary
In an apparatus for controlling a continuously variable transmission, a transmission ratio, an input shaft rotational speed and an input torque, etc., are detected, an axial thrusts of the drive and driven pulleys are detected therefrom, an inter-shaft force is detected, a friction coefficient of the driven pulley including at least a radial component of the friction coefficient μRDN is calculated in accordance with predetermined relational equations, a target axial thrust of the driven pulley is calculated based on at least the friction coefficient and the axial thrust of the driven pulley is controlled based on the calculated target axial thrust.