一种新型大扭矩传输CVT的机构设计与性能分析

Mechanism Design and Performance Analysis of a Novel CVT with High-Torque Transmission

针对现有无级变速器不能传递较大扭矩的情况,提出了一种分矩汇速的大扭矩传输设计方案;分析了2K-H型差动轮系、双排差动轮系与定轴轮系、输入轴的连接方式;以输入功率分流比为评价指标,得出了双排差动轮系输入功率分流比区间涵盖2K-H型差动轮系输入功率分流比区间且结构紧凑的结论,从而构建了由双腔半环面型无级变速单元、定轴轮系、双排差动轮系组成闭环系统的新型CVT机构;求解了表征该机构扭矩传输的输入扭矩分矩比和输出输入扭矩比等性能指标,并分析了有利于新型CVT大扭矩输出的双排差动轮系转换机构传动比、定轴轮系传动比的变化趋势.最后,通过算例验证了这两项传动比变化趋势的正确性.

As the existing continuously variable transmissions（CVTs） cannot transmit high torque,first,a design scheme with input coupled type for transmitting high torque is put forward.Then,the connection modes of the 2K-H type differential gear train and the double-row differential gear train with the fixed-axis gear train and with the in-put axis are analyzed.By using the input power-distributing ratio as an evaluation index,it is found that,as compared with the 2K-H type differential gear train,the double-row differential gear train is of larger interval of input power-distributing ratio and more compact structure.According to these findings,a novel CVT mechanism is designed,which is composed of a dual-cavity half-toroidal continuously variable unit,a fixed-axis gear train and a double-row differential gear train in a closed loop.Moreover,the performance indexes describing the torque transmission of the novel CVT,namely the split ratio of input torque and the ratio of output torque to input torque,are derived,and the variation trends of the transmission ratios of the fixed-axis gear train and the shifting mechanism of the double-row differential gear train,which benefit the high torque output of the novel CVT,are discussed.Finally,the correctness of the variation trends of the two transmission ratios is confirmed by numerical examples.