Continuously variable transmissions (CVTs) can achieve continuous changes in speed ratio and can better improve the ride comfort of the car. However, the torque fluctuation of the engine will reduce its transmission efficiency, and the torsional damper is usually matched to improve transmission efficiency and reduce vibration noise. In this paper, the model of a complete vehicle power transmission system was established by using the bond graph method. The relationships between each state variable were obtained according to the system causality and the direction of the power flow, based on which the dynamic model of the entire vehicle power transmission system was derived. A simulation of the powertrain with dual-mass flywheel-continuously variable transmission (DMF-CVT) was carried out, and the torsional stiffness of the dual-mass flywheel (DMF) was optimized. Taking a certain sport-utility vehicle (SUV) as the test bench, the vehicle road testing of the DMF before and after improvement was carried out, and the test results before and after the improvement were compared to verify the correctness of the optimization direction, which provided a reference for the matching and optimization design of the DMF-CVT power transmission system.

无级变速器（CVT）可以实现速比的连续变化，可以更好地提高汽车的乘坐舒适性。但发动机的扭矩波动会降低其传动效率，通常搭配扭振阻尼器，以提高传动效率，降低振动噪声。本文采用键合图方法建立了整车动力传动系统的模型。根据系统的因果关系和功率流的方向，得到各状态变量之间的关系，在此基础上推导出整车动力传动系统的动力学模型。对带有双质量飞轮无级变速器 (DMF-CVT) 的动力系统进行了仿真，并对双质量飞轮（DMF）的扭转刚度进行了优化。以某运动型多功能车（SUV）为试验台，对改进前后的DMF进行整车道路测试，对比改进前后的测试结果，验证优化方向的正确性，为DMF-CVT动力传动系统的匹配优化设计提供了参考。