Method for operating a drive train of a vehicle

A method for operating a drive train of a vehicle during a gearshift from an actual transmission ratio (i_ist) to a target transmission ratio (i_ziel), the drive train having a hydrodynamic torque converter (3), a transmission device (4) and a prime mover (2), the method comprising the steps of:

• transmitting a shifting signal to the transmission device (4);
• initiating a transmission ratio change by reducing a transmitting capacity of a shifting element engaged in a power flow of the automatic transmission (actual ratio (i_ist)) and simultaneously preparing a shifting element to be engaged in the power flow of the transmission device (target ratio (i_ziel));
• adjusting a nominal standard of a control pressure (p_kab) of the shifting element to be disengaged, with respect to a nominal standard of the control pressure (p_kzu) of the shifting element to be engaged, such that an actual rotational speed (n_t_ist) of a turbine of the torque converter is altered, during the gearshift, from a synchronous rotational speed (n_t(“i_ist”)) of the turbine of the ratio (i_ist) to a synchronous rotational speed (n_t(“i_ziel”)) of the turbine of the target ratio (i_ziel);
• and
• adjusting the nominal standard of the control pressure (p_kab) of the shifting element to be disengaged, until a divergence of the actual rotational speed (n_t_ist) from a predefined nominal standard (n_t) of the rotational speed of the turbine is less than a threshold value, when the divergence of the actual rotational speed (n_t_ist) from a predefined nominal standard (n_t) of the rotational speed of the turbine is higher than the threshold value.