CVT Compression Control via Slip State Matrix
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Solution Overview
Problem
Existing continuously variable transmission systems face challenges in accurately detecting slip states and controlling slippage, leading to degraded power transmission efficiency due to the need for special sensors and excessive pulley thrust caused by safety factors to prevent slippage.
Innovation Solution
A compression control device that calculates a slip state matrix from rotational speed amplitudes and phase lags to estimate power transmission states and control compression, allowing precise slippage detection and minimization without requiring special sensors, and adjusts compression based on eigenvalue analysis to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the target torque ratio is set to 1 to maximize power transmission efficiency, then power transmission efficiency is improved, but slippage occurs under disturbances such as oil pressure pulsations and torque variations
Solution Approach 1:
The patent applies partial action by setting the target torque ratio to a value slightly less than 1 (e.g., 0.95) rather than exactly 1. This provides a safety margin that prevents slippage under disturbances while maintaining near-maximal power transmission efficiency. The control device adjusts pulley thrust to achieve this slightly reduced torque ratio, balancing efficiency and reliability.
2Reliability
If the target torque ratio is set below 1 to prevent slippage with safety factor, then slippage prevention is improved, but pulley thrust becomes excessively large and power transmission efficiency is degraded
Solution Approach 1:
The patent uses partial action by implementing a safety factor that reduces the target torque ratio only slightly below 1 (e.g., to 0.95). This provides adequate slippage prevention while avoiding excessive pulley thrust. The control device optimizes the safety factor to achieve the right balance between reliability and efficiency.
Solution Approach 2:
The patent dynamically adjusts the target torque ratio parameter based on operating conditions. Rather than using a fixed conservative value, the control device modifies this parameter in real-time to maintain optimal balance between slippage prevention and power transmission efficiency across different operating states.
3Measurement precision
If special sensors are added to detect input torque for calculating μ gradient, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies self-service by using the continuously variable transmission system's own existing sensors and measurements to detect slip state. The control device calculates μ gradient using data from standard sensors already present in the system (output shaft rotational speed sensor and gear ratio information), eliminating the need for additional special sensors for input torque detection.
Solution Approach 2:
The patent uses an intermediary approach by introducing calculated parameters (amplitude ratio, phase lag, and derived μ gradient) that mediate between existing sensor measurements and slip state detection. This allows accurate slip detection without direct measurement of all physical quantities using special sensors.
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 enables precise control of slippage, enhancing power transmission efficiency while preventing damage by accurately determining slip states and adjusting compression, even under disturbances, without the need for special sensors.
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 contacted portions thereof
Data Source
AI summary
A compression control device for a continuously variable transmission is provided in which the compression control device that controls the compression of either one of shaft elements of the continuously variable transmission calculates a slip state matrix from an amplitude ratio between a variable component of a rotational speed of the input shaft and a variable component of a rotational speed of the output shaft, a phase lag that is an indicator of difference in phase between a variable component of the rotational speed of the input shaft and a variable component of the rotational speed of the output shaft, and a gear ratio between the input shaft and the output shaft, estimates a power transmission state among the input shaft element, the output shaft element, and the power transmission element based on an eigenvalue sequence calculated from the slip state matrix, and controls compression.