Patent ID: 7806804
Filing Date: 2010-10-05
Classification: B60W,F16H,Y10T

Abstract:
1. A method for shifting gears in an automatic multi-stage gearbox of a motor vehicle, wherein the gearbox comprises a drive input shaft connectable to an engine output shaft by means of a friction clutch, which acts as a separating clutch, and a drive output shaft couplable to a drive wheel or drive wheels of the motor vehicle, wherein a shift process takes place as a function of rotational speeds of the shafts, wherein each gear is assigned a synchronizing device, which acts as a shift clutch, in order to connect the drive input shaft to the drive output shaft, comprising the following steps: setting the separating clutch into a dragging position such that a low drag torque is transmitted from the engine drive output shaft to the drive input shaft, which drag torque is sufficient to bring a rotational speed of the drive input shaft, when the shift clutch is open, to a rotational speed of the engine drive output shaft; adjusting the rotational speed of the engine drive output shaft to a predetermined value which differs sufficiently from a rotational speed of a source gear or from rotational speed of a target gear; setting the shift clutch of the source gear towards an open position in order to separate the drive input shaft and drive output shaft from one another; detecting the rotational speed of the drive input shaft for a predetermined time period which follows at least a time when the shift clutch of the source gear is in the open position; determining a change in the rotational speed of the drive input shaft 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.