考虑滑移的CVT变速系统综合效率特性试验研究

Experimental Research on Comprehensive Efficiency Characters of CVT Variator System Considering Slip

为改善CVT变速系统夹紧力过高、效率偏低的问题,采用试验辨识方法揭示金属带滑移率与变速系统综合效率间的关联规律.考虑金属带滑移对传动损失及油泵功耗的耦合影响,构建变速系统综合效率试验模型,以某自主开发的CVT变速系统为研究对象,设计变速机构传动效率滑移率试验及油泵功耗试验,分析出不同速比、不同输入转矩及不同输入转速下变速系统综合效率随滑移率的变化特性,最后根据试验结果导出变速系统最优效率滑移线及最优效率安全系数.结果表明:在滑移率增加的过程中存在变速系统综合效率峰值滑移点,该滑移点位于传动效率峰值滑移点与摩擦系数饱和滑移点之间,其主要受速比的影响,输入转矩和输入转速对其位置的影响可以忽略;在整个速比区间,变速系统最优效率滑移线位于0.98%～3.16%之间,对应的综合效率为0.878～0.915,最优效率安全系数位于1.09～1.16范围内,其较CVT传统夹紧力安全系数降低了10.8%～16.2%.研究结果可为CVT滑移控制提供明确的控制目标,同时可为降低CVT夹紧力安全系数提供下限参考边界.

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.