动力保持型AMT带式制动器的动态力矩特性

Dynamic torque characteristics of the band brake of a continuous automatic transmission

带式制动器是动力保持型自动变速器(AMT)的换挡执行元件,其中制动带的动态力矩特性对于换挡品质至关重要。为探寻动态制动力矩与制动力的关系,该文建立了制动带静力学模型和有限元模型,设计了带式制动器样机实验台架,完成了制动鼓正反转实验,将实验结果与仿真计算结果进行了对比分析,结果表明:动态制动力矩是转速、正压力、动态摩擦系数共同作用的结果;制动鼓正转时,制动带有增力效应,制动带所产生的制动力矩较大,静态区持续时间长,制动稳定性好,而反转时无明显的静态区,线性度好,对控制有利。根据实验结果拟合得到制动带动态力矩经验公式的控制参数,可用于制动带的平滑控制。

A band brake is the shift actuator in a continuous automatic transmission with the band brake dynamics significantly influencing the shift quality. A static model, a finite element model and tests were used to investigate the relationship between the brake torque and the braking force. Tests of a brake drum rotated clockwise and counterclockwise were compared with simulations. The results show that the dynamic braking torque is related to the rotational speed, normal force and dynamic friction coefficient. When the brake drum is rotated forward, the self-energy effect increases the braking torque generated by the brake band with a longer static zone and better braking stability. When the drum is reversed, there is no obvious static zone, while the relationship is more linear and suitable for control. The test results are used to define the control parameters of the empirical equation for the dynamic brake band braking torque for smooth control of the brake band.