液力机械自动变速器动力性换挡点算法研究

Study on the Calculation Method of the Power Shift Point of Hydro-mechanical Automatic Transmission

为得到发动机与液力变矩器共同工作点及动力性换挡点精确计算结果,对发动机净转矩外特性曲线采用三次样条插值,并构造了求解共同工作点及动力性换挡点的求值函数,分别采用改进二分法和牛顿下山法来求解构造函数零值。通过实例计算和分析表明,这2种方法运行速度快、精度高,求得的动力性换挡特性提高了液力传动车辆的匹配效率。

To obtain the common operating point of engine and torque converter and an accurate calculation result of the power shifting point, cubic spline interpolation is adopted for the exterior characteristic of engine net torque, and the evaluation function is established to solve the common operating point and power shifting point, and the modified dichotomy and Newton Downhill Method are employed respectively to solve zeros of constructed function. The example calculation and analysis indicate that the two methods operate with rapid speed and high precision, the obtained power shifting characteristic improves matching efficiency of vehicle with hydraulic transmission.