重载越野车辆高原起步响应性研究

针对重载越野车辆在高原环境下起步响应性差的问题,借助汽车仿真分析GT-SUITE软件建立整车模型,仿真研究了海拔因素对重载越野车辆起步过程的影响以及换挡时刻、前传动比对高原环境下起步过程的影响。结果表明:平原环境下整车起步用时14.7 s,而海拔高度4 500 m环境下用时27.2 s;相比于1 000 r/min转速换挡而言,2 000 r/min转速换挡所对应的整车起步响应时间缩短了3.9 s,因此可以通过提高起步换挡时刻对应发动机转速的方法来改善车辆的起步响应性;随着前传动比的增大,整车起步过程中的加速度增大,但是达到稳定状态时的车速减小,因此可以通过合理选择前传动比的方式来改善车辆的起步响应性。受到空燃比限制的影响,使得起步过程发动机与液力变矩器的共同输入特性与4 500 m海拔下外特性所对应的共同输入特性差别较大。

Research on the Starting Response of Heavy-duty Off-road Vehicle on Plateau

To study the starting response of heavy-duty off-road vehicle on plateau, a full vehicle model is established using GT-SUITE. The effects of altitude, gear shifting moment of and front gear ratio on the starting-up process of heavy-duty off-road vehicle are studied through simulation. The research results show that the starting process of vehicle takes 14.7 s on plain, while it takes 27.2 s at the altitude of 4 500 m; in comparison with the gear shifting at 1 000 r/min, the response time of starting is decreased by 3.9 s at 2 000 r/min. Therefore, the vehicle starting response can be improved by shifting gear at high engine speed. With the increase in front gear ratio, acceleration increases during starting, but the vehicle speed decreases at steady state. Therefore, the starting response of vehicle can be improved by choosing an apposite front gear ratio. Due to the influence of air-fuel ratio limit, the common input characteristics of hydraulic torque converter and engine during starting are different from the common input characteristics of hydraulic torque converter corresponding to engine full load characteristics at the altitude of 4 500 m.