液压机械无级变速器换段冲击影响因素研究

为解决液压机械无级变速器HMT换段冲击问题,对某型HMT的换段过程进行了理论分析和试验研究.得出结论:汇流行星排三构件的转速换段时刻有突变是造成换段冲击的根本原因.存在同步换段点传动比,它仅由HMT的机械结构决定.分析了欠同步换段和过同步换段时马达转速和输出转速的波动情况,并进行试验验证.液压系统容积效率的变化会造成马达转速和输出转速的突变,从而在汇流行星排上产生冲击载荷.制动器充放油特性的不一致和共用油源时操纵油压的相互影响均有可能导致动力传递中断,从而造成换段冲击. 

Research on the Influencing Factors of the Range-Shifting Impact on HMT

To decrease the range-shifting impact on hydro-mechanical transmission (HMT),theoretical analysis and test-bed experiments of the range-shifting process on one kind of HMT had been done. It can be concluded that the mismatch of the rotating speeds of the three basic elements of the planetary-gear system is the essential factor leading to the range-shifting impact. The existence of the synchronized range-shifting gear ratio was proven and it is only determined by the mechanical structure of the HMT. The variation of the motor speed and output speed during the under-synchronized and over-synchronized range-shifting were analyzed and investigated with test bench experiments. The results show that, the volumetric efficiency of the hydraulic system will cause a sudden shift of the motor speed and further the impact on the planetary-gear system, the distinctness of the engagement and disengagement characteristics of the brakes is one of the reasons resulting in the interrupt of the power transfer. While the two brakes use a common oil source, the mutual influence of the manipulating hydraulic pressure may cause the power transfer interrupt and torque impact.