Method for a synchronous range shift on an electronically controlled two-speed transfer case with an electronically controlled engine and transmission

A method for shifting between a low speed range and a high speed range for a two-speed transfer case in a four-wheel drive vehicle includes determining a target transmission gear ratio and a desired transfer case range based on the current vehicle speed and the initial transfer case range. The transmission is shifted to the target transmission gear ratio when it is determined that the vehicle speed is in an appropriate range. The transfer case input torque is reduced to a minimum value, and the transfer case is shifted to neutral. The method further includes adjusting the engine speed and transmission gear setting to control the transmission output shaft speed to a desired range. The transfer case is shifted from neutral to the desired transfer case range when the transmission output shaftspeed is within the desired range of transmission output shaft speed. 种用于在四轮驱动车辆中使双速分动箱在低速挡与高速挡之间换挡的方法，该方法包括：基于当前车辆速度和初始分动箱挡位来确定目标变速器齿轮比和期望分动箱挡位。当确定了车辆速度在恰当范围内时，将变速器切换至目标变速器齿轮比。将分动箱输入转矩减小至最小值，并且将分动箱切换至空挡。方法进步包括：调节发动机速度和变速器齿轮