Method and control unit for operating a motor vehicle

Abstract

Method for operating a motor vehicle with a drive unit (1), a transmission (2) having several switching elements (9, 10, 11, 12, 13) and an output (14), wherein the transmission (2) is designed as an automatic or automated transmission and is connected between the drive unit (1) and the output (14), wherein in each engaged, friction-fit gear of the transmission (2) a first number of the switching elements (9, 10, 11, 12, 13) of the transmission (2) are closed or engaged and a second number of the switching elements (9, 10, 11, 12, 13) of the transmission (2) are opened or disengaged, wherein, depending on at least one operating condition of the motor vehicle, a coasting mode is entered, and subsequently, depending on at least one operating condition of the motor vehicle, the coasting mode is exited.wherein, to enter the sailing mode of the motor vehicle, starting from a friction-engaged gear, a switching element of the transmission (2) is actuated to open, such that in a non-friction-engaged sailing gear one less switching element is closed and thus one more switching element is open than in a friction-engaged gear, wherein in the sailing mode of the motor vehicle the respective closed and open switching elements of the transmission (2) are changed depending on at least one operating condition of the motor vehicle to maintain the sailing gear, characterized in that, when sailing with the drive unit (1) stationary, it is checked whether a synchronous speed of the friction-engaged gear that is engaged starting from the current actual sailing gear when exiting the sailing mode is above or below a limit value dependent on the fictitious idle speed of the drive unit (1), wherein depending on this,whether the synchronous speed is above or below the limit value dependent on the fictitious idle speed of the drive unit (1), a power transmission type adapted for exiting the sailing mode is selected when engaging the respective power-locking gear.

Images