Method and controller for operating a drivetrain of a vehicle

A control unit for operating a transmission of a vehicle, such that when a rocking-free operating mode of the drive-train for rocking the vehicle free is active, the control unit automatically actuates a clutch to rock the vehicle free depending on an actuation of an accelerator pedal by a driver,

• the control unit automatically actuates the clutch to rock the vehicle free, as a function of the actuation of the accelerator pedal by the driver and as a function of a rotational speed of an drive output, in such manner that
• when, after an actuation of the accelerator pedal and the actuation of the accelerator pedal is then decreased, the control unit first actuates the clutch with a defined first opening gradient,
• then, as a function of a calculated point in time at which a value of torque from a drive aggregate that acts upon the clutch corresponds to a torque acting upon the clutch from the drive output, the control unit terminates the disengagment of the clutch with the defined first opening gradient and actuates the clutch with a defined second opening gradient, which is smaller than the first opening gradient,
• and then, if a value of a gradient of the rotational speed of the drive output becomes larger than a limit value, the control unit actuates the clutch with a defined first closing gradient,
• and then, if the value of the gradient of the rotational speed of the drive output becomes smaller than a limit value, the control unit terminates the engagement of the clutch with the defined first closing gradient.

A method of operating a drive-train of a vehicle for rocking the vehicle free from a depression, the drive-train having, in a direction of toque transmission, a drive aggregate connected to an input shaft of a transmission, a controllable clutch having an input side connected to the input shaft and an output side connected to an output shaft of the transmission, the output shaft being connected to a drive output, the clutch being automatically actuatable to disengage and engage to controllably transmit drive from the input shaft to the output shaft, the method comprising:

• activating a rocking-free operating mode for rocking the vehicle free, and automatically actuating the clutch to rock the vehicle free as a function of actuation of the accelerator pedal by a driver and as a function of a rotational speed of the drive output such that:
• disengaging the clutch with a defined first opening gradient when the accelerator pedal is actuated and actuation of the accelerator pedal decreases,
• terminating the disengagement of the clutch with the defined first opening gradient and disengaging the clutch with a defined second opening gradient, which is smaller than the first defined opening gradient, as a function of a calculated point in time when a value of torque from the drive aggregate that acts upon the clutch corresponds to torque acting upon the clutch from the drive output,
• initiating engagement of the clutch with a defined first closing gradient when a value of a gradient of the rotational speed of the drive output is larger than a limit value, and
• terminating engagement of the clutch with the defined first closing gradient when the value of the gradient of the rotational speed of the drive output is smaller than the limit value.