METHOD FOR SHIFTING A GEAR IN A MULTI-STAGE GEARBOX OF A MOTOR VEHICLE AS A FUNCTION OF THE DRIVE INPUT SHAFT ROTATIONAL SPEED

摘要

Method for shifting, in particular engaging and/or disengaging, gears in an automatic multi-stage gearbox of a motor vehicle, wherein the gearbox comprises a drive input shaft (18) connectable to an engine drive output shaft (16) by means of a friction clutch (12) which acts as a separating clutch (12), and a drive output shaft (20) couplable to a drive wheel or to drive wheels of the motor vehicle, wherein a shift process takes place, in particular only, as a function of rotational speeds (n) of the shafts, wherein each gear is assigned a synchronizing device (36), which acts as a shift clutch, in order to connect the drive input shaft (18) to the drive output shaft (20), comprising the following steps: setting the separating clutch (12) into a dragging position such that a low, preferably predefined, drag torque is transmitted from the engine drive output shaft (16) to the drive input shaft (18), which drag torque is sufficient to bring a rotational speed (n_IS) of the drive input shaft (18) when the shift clutch (36) is open to a rotational speed (n_M) of the engine drive output shaft (16); adjusting the rotational speed of the engine drive output shaft (16) to a predetermined value (I) which differs sufficiently from a rotational speed of a source gear or from rotational speed of a target gear; setting the shift clutch (36) of the source gear towards an open position in order to separate the drive input shaft (18) and drive output shaft (20) from one another; detecting the rotational speed (n_IS) of the drive input shaft for a predetermined time period which follows at least a time (t₁) when the shift clutch (36) of the source gear is in the open position; determining a change in the rotational speed (n_IS) of the drive input shaft (18) during the predetermined time period; and determining whether the change which is determined in this way lies within predefined tolerances of an expected rotational speed change.