Experimental Research on Comprehensive Efficiency Characters of CVT Variator System Considering Slip
In order to decrease the clamping force and increase the transmission efficiency of CVT variator system， the relationship between the slip rate and comprehensive efficiency of variator system was examined by using the experimental identification method. Considering the coupling effect of slip on the transmission loss and oil pump power consumption， a model for testing the comprehensive efficiency of variator system was constructed. Based on a self-developed CVT variator system， the tests of transmission efficiency to slip rate and oil pump power consumption were designed, the variation characteristics of the comprehensive efficiency of variator system considering the slip rate under different speed ratio， input torque and input speed were analyzed， and the maximum efficiency slip line and maximum efficiency safety factor of the variator system were derived according to the test results. The results demonstrate that， with the increase of the slip rate， the peak comprehensive efficiency slip point of variator system occurs， which is located between the peak transmission efficiency slip point and friction coefficient saturation slip point，and mainly affected by the speed ratio. The influence of input torque and input speed can be neglected. In the whole speed ratio range， the maximum efficiency slip line of variator system is located between 0.98%~3.16%, the corresponding comprehensive efficiency is between 0.878~0.915, and the maximum efficiency safety factor is between 1.09~1.16，which is reduced by 10.8%~16.2% when compared with the traditional clamping force safety factor. The results of the study can provide a clear control target for CVT slip control and also provide a lower reference boundary for reducing the safety factor of CVT clamping force.
Keywords: continuous variable transmission, slipping, comprehensive efficiency, slip control test
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