履带车辆传动系统换挡工况瞬态动力学分析

提出了一种分析履带车辆动力传动系统瞬态动力学行为的仿真模型。首先,考虑离合器非线性摩擦系数和齿轮间隙等非线性因素,分别建立发动机、离合器和齿轮副等部件模型并集成为一个动力传动系统集中参数仿真模型。其次,以履带车辆油门开度突变这一瞬态工况为例,分析了过程中发生的齿轮反冲、脱啮和离合器粘滑颤振等动力学现象的机理。最后,利用小波变换进行了时频分析,辨识出了瞬态动力学行为的发生时刻和其在输出转矩中的频率成分,结果表明对应频率为114 Hz的轮齿反冲对传动系统输出转矩有显著影响,频率范围在1 500~5 000 Hz的摩擦元件颤振对输出转矩仍有一定影响,而5 k Hz以上的高频振动则对输出转矩的影响较小。

Transient Dynamic Analysis of Tracked Vehicle Transmission during Gear Shift Process

The research objective was to propose an analytic model to investigate the transient dynamic behavior of a tracked vehicle powertrain. Firstly, by considering the engine torque harmonics, gear backlash, friction coefficient and other nonlinear factors, lumped-mass component models as diesel engine, torque converter with lockup clutch, wet clutch, spur gear pair and vehicle were developed and then incorporated to an integral model. Then, a gear shift process that induces nonlinear dynamic behaviors, including clonk, gear contact loss and clutch stick-slip judder was simulated with the initial and boundary conditions for the shift process carefully set. Transient dynamic behaviors and the mechanism of dynamic behaviors occurred during the gear shift process were discussed. Finally, time-frequency analysis of output torque was conducted by wavelet transform. The instants of the occurrences of transient dynamic behavior were identified by time-frequency analysis and the corresponding frequency components were examined. The clutch torque pulse with a steep gradient due to the transition between slip and stick was an impact source in the system, and the results also indicated that the gear contact and reverse impact (114Hz) significantly impacted the output torque, the clutch stick-slip judder (1500~5000Hz) also affected the output torque but the high-frequency vibrations (higher than 5kHz) had little influence on it. The wavelet transform based time-frequency frequency analysis can be used to diagnose NVH issues of vehicle powertrain. Also, the system parameters of the powertrain can be optimized to obtain good NVH characteristics by using the simulation method proposed in the article.