Research on Safety Margin Optimization of CVT Transmission Based on Principle of Least Action under Lubrication Mechanism

doi:10.3901/JME.2022.10.222

Abstract

Abstract: Aiming at the problem that the lubrication mechanism of the existing metal belt type continuously variable transmission (continuously variable transmission, CVT) sliding friction transmission process affects the safety and efficiency of metal belt transmission. Taking a domestically-developed CVT as the research object, the distribution trend of force and stress between CVT driven pulley and metal belt friction plate was analyzed, and the thermal elastohydrodynamic lubrication model of metal belt pulley was established. Due to the critical extreme value of oil film state in the process of CVT operation, the assumption that the lubrication characteristics conform to the principle of least action is put forward. The Lagrange function and principle of least action model of CVT lubrication characteristics are constructed, and the values of actual action and theoretical minimum action in CVT lubrication process are deduced, and the film under variable temperature environment is clarified The change trend of thick action amount verifies the rationality of the hypothesis. The function expressions of macro friction coefficient and micro oil film shear force between metal belt pulley and metal friction plate are obtained. Combined with CVT transmission comprehensive test, the working relations of friction coefficient, temperature, transmission efficiency and torque ratio are tested respectively, and the optimal transmission torque value of metal belt is calculated. The safety margin of CVT sliding friction transmission is determined by interpolating the results obtained from specific operating conditions. The variation characteristics of transmission efficiency under different speed ratios, input torque and speed of the transmission mechanism are analyzed. The results show that the transmission efficiency of CVT can be effectively increased by 2.62%-3.76% based on the principle of least action. It provides a new optimization idea to solve the problem of CVT transmission safety and efficiency.

Key words: continuously variable transmission, principle of least action, oil film characteristics, safety margin, transmission efficiency

CLC Number:

TG156

HAN Ling, ZHAO Wei, CAO Yue, WANG Jinwu. Research on Safety Margin Optimization of CVT Transmission Based on Principle of Least Action under Lubrication Mechanism[J]. Journal of Mechanical Engineering, 2022, 58(10): 222-234.

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