Method and controller for operating a drivetrain of a vehicle

Patent metadata

Field	Value
Publication number	US-11378142-B2
Application number	US-201917291777-A
Country	US
Kind code	B2
Filing date	Nov 7, 2019
Priority date	Nov 7, 2018
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A method of operating a vehicle drivetrain for rocking the vehicle free. The drivetrain has a transmission with an input and an output that can be coupled by a clutch. The input and output are connected to a drive aggregate and a drive output, respectively. The clutch is actuated based on driver actuation of an accelerator and a rotational speed of the drive output such that following accelerator actuation, when its actuation decreases, the clutch disengages with a first opening gradient. Then, based on a calculated point in time at which drive aggregate torque upon the clutch corresponds to torque on the clutch from the drive output, the clutch disengages with a second, smaller opening gradient. And depending on a rotational speed of the drive output relative to a limit value, the clutch either initiates or terminates engagement with a first closing gradient.

First claim

The invention claimed is:

1. A method of operating a drive-train of a vehicle in order to rock the vehicle free, the drive-train having a drive aggregate, a drive output and a transmission which is arranged in the drive-train between the drive aggregate and the drive output, the transmission having a controllable clutch which has a drive input side and a drive output side, a shaft connected to the drive input side of the clutch is connected to the drive aggregate and a shaft connected to the drive output side of the clutch is connected to the drive output, the method comprising:
when a rocking-free operating mode is active for rocking the drive-train free, and depending upon an actuation of an accelerator pedal by a driver, automatically actuating the clutch to rock the vehicle free,
automatically actuating the clutch as a function of the actuation of the accelerator pedal by the driver and as a function of a rotational speed of the drive output,
initially opening the clutch with a defined first opening gradient, when the accelerator pedal is actuated and the actuation of the accelerator pedal is then decreased,
thereafter, as a function of a calculated point in time at which a value of a torque from the drive aggregate that acts upon the clutch corresponds to a torque acting upon the clutch from the drive output, terminating 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 opening gradient,
then, when a value of a gradient of the rotational speed of the drive output becomes larger than a limit value, commencing engagement of the clutch with a defined first closing gradient,
and then, when the value of the gradient of the rotational speed of the drive output becomes smaller than a limit value, terminating engagement of the clutch with the defined first closing gradient.

2. The method according to claim 1 , further comprising when the engagement of the clutch with the defined first closing gradient is terminated, maintaining an engagement position of the clutch constant until the accelerator pedal is actuated again.

3. The method according to claim 2 , further comprising when the accelerator pedal is actuated again, engaging the clutch with a defined second closing gradient which is larger than the first closing gradient.

4. The method according to claim 3 , further comprising engaging the clutch with the second closing gradient until a torque transmitted by the clutch corresponds to a torque desired by the driver as a function of actuation of the accelerator pedal.

5. 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.

6. The control unit according to claim 5 , wherein when the control unit terminates engagement of the clutch with the defined first closing gradient, the control unit maintains an engaged position of the clutch constant until the actuation of the accelerator pedal is increased again.

7. The control unit according to claim 6 , wherein when new actuation of the accelerator pedal is increased, the control unit actuates the clutch with a defined second closing gradient which is larger than the first closing gradient.

8. The control unit according to claim 7 , wherein with the second closing gradient, the control unit engages the clutch until a torque transmitted by the clutch corresponds to a torque desired by the driver that depends on the actuation of the accelerator pedal.

9. 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.

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Leingruber Kai

Classifications

• F16D2500/507

  Relating the vehicle · CPC title

• F16D48/06 Primary

  Control by electric or electronic means, e.g. of fluid pressure · CPC title

• F16D2500/10412

  Transmission line of a vehicle · CPC title

• F16D2500/3144

  Accelerator pedal position · CPC title

• F16D2500/30426

  Speed of the output shaft · CPC title