无级变速器夹紧力控制方法的可靠性

Reliability Analysis of Continuously Variable Transmission Clamping Force Control Algorithm

从确定目标夹紧力、设计控制算法和验证传动可靠性三个方面,对无级变速器夹紧力控制中的可靠性问题进行了研究。澄清了绝对安全系数与相对安全系数在概念上的混淆,指出错误地采用相对安全系数法不能保证夹紧力的可靠性。分析了惯性力矩和计算流程对主动轮扭矩计算误差的影响,给出了主动轮扭矩的正确计算方法。提出了夹紧力控制算法的模块化和通用化,设计了夹紧力通用复合控制算法。实验分析了速比控制对夹紧力的耦合作用,指出低速重载工况下为防止金属带打滑必须限制速比变化率。分析了最容易引起金属带打滑的工况,对车辆从冰面打滑状态突然进入水泥路面的行驶过程进行了仿真,验证了夹紧力控制方法的可靠性。

From three respects including clamping force computing method, control algorithm development and clamping force reliability validation, several key points of CVT clamping force control process were studied. The obscure concepts of absolute safety factor and relative safety factor were ex- plained. Normal relative safety factor method could not ensure the safety of clamping force. Inertia torque and computing process were analyzed to determine the influence factors of primary pulley torque computing error. The right computing method and process of clamping force target value were presented. Coupling effects between clamping force control and ratio control were studied by experiments. To avoid metal-belt slipping, ratio shift rate had to be limited while the vehicle was in low speed and heavy duty. The most likely condition leading to metal-belt slipping was analyzed. To validate the reliability of control methods, vehicle running process from ice surface to cement road was simulated.