Method for operating a drive train of a motor vehicle, and drive train module of a motor vehicle of this type

Patent metadata

Field	Value
Publication number	US-10793154-B2
Application number	US-201716095200-A
Country	US
Kind code	B2
Filing date	Mar 22, 2017
Priority date	Apr 21, 2016
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A method for operating a drive train of a motor vehicle, the drive train having at least one transmission ( 2 ) for carrying out different transmission gear ratios between an input shaft ( 21 ) and an output shaft ( 22 ) of the transmission ( 2 ) by selectively engaging hydraulically actuatable shift elements of the transmission (G), the drive train further having an electric machine as a drive source ( 1 ), and a hydraulically actuatable or bridgeable starting component ( 3 ) in the power path between the drive source ( 1 ) and the output shaft ( 22 ). The method includes performing a starting process of the motor vehicle driven solely by the drive source ( 1 ) with an engaged or bridged starting component ( 3 ). The method further includes limiting a drive source torque ( 1 t ) during the starting process to a maximum value dependent on a current system pressure ( 2 p ) of a hydraulic system of the transmission ( 2 ).

First claim

The invention claimed is:

1. A method for operating a drive train of a motor vehicle, the drive train having at least one transmission ( 2 ), the transmission ( 2 ) configured such that different gear ratios between an input shaft ( 21 ) and an output shaft ( 22 ) of the transmission ( 2 ) are made available by selectively engaging hydraulically actuatable shift elements of the transmission (G), the drive train further having an electric machine as a drive source ( 1 ) and a hydraulically actuatable or bridgeable starting component ( 3 ) in a power path between the drive source ( 1 ) and the output shaft ( 22 ) of the transmission (G), the method comprising:
performing a starting process of the motor vehicle, the starting process driven solely by the drive source ( 1 ) with the starting component ( 3 ) locked-up; and
limiting a drive source torque ( 1 t ) of the drive source ( 1 ) during the starting process to a maximum value of the drive source torque ( 1 t ), the maximum value of the drive source torque ( 1 t ) being dependent on a current system pressure ( 2 p ) of a hydraulic system of the transmission ( 2 ).

2. The method of claim 1 , wherein the maximum value of the drive source torque ( 1 t ) is additionally dependent on a gear ratio engaged in the transmission ( 2 ).

3. The method of claim 1 , wherein the maximum value of the drive source torque ( 1 t ) is additionally dependent on a temperature of a hydraulic fluid of the transmission ( 2 ).

4. The method of claim 1 , wherein the maximum value of the drive source torque ( 1 t ) is additionally dependent on a temperature of a shift element ( 3 x ) of the transmission ( 2 ).

5. The method of claim 1 , wherein the transmission ( 2 ) includes a first pump ( 26 ) drivable by the drive source ( 1 ) and a second pump ( 24 ) drivable independently of the drive source ( 1 ), the first and the second pumps ( 26 , 24 ) are configured for supplying pressure to the shift elements and the starting component ( 3 ) or to the shift elements and a lock-up clutch of the starting component ( 3 ), the method further comprising:
determining an output pressure of the first pump ( 26 ) with a first pressure model, and an output pressure of the second pump ( 24 ) with a second pressure model; and
utilizing the greater of the output pressure of the first pump ( 26 ) and the output pressure of the second pump ( 24 ) as the current system pressure for limiting the drive source torque ( 1 t ).

6. The method of claim 1 , wherein the starting component ( 3 ) is transferred into a slip state when the drive source torque ( 1 t ) of the motor vehicle reaches or exceeds the current maximum value of the drive source torque ( 1 t ).

7. The method of claim 6 , wherein a rotational speed of the drive source ( 1 ) is increased in parallel with the transfer of the starting component ( 3 ) into the slip state.

8. A drive train module of a motor vehicle, comprising:
at least one drive source ( 1 ), the at least one drive source ( 1 ) being an electric machine;
an interface to an internal combustion engine ( 9 ) of the motor vehicle;
a control unit;
a transmission (G) configured for providing different gear ratios between an input shaft ( 21 ) and an output shaft ( 22 ) of the transmission ( 2 ) by the selective engagement of hydraulically actuatable shift elements of the transmission (G); and
a hydraulically actuatable or bridgeable starting component ( 3 ) in a power path between the drive source ( 1 ) and the output shaft ( 22 ) of the transmission (G),
wherein the control unit is configured for, by an open-loop control system,
performing a starting process of the motor vehicle, the starting process driven solely by the drive source ( 1 ) with the starting component ( 3 ) locked-up, and

limiting a drive source torque ( 1 t ) of the drive source ( 1 ) during the starting process to a maximum value of the drive source torque ( 1 t ), the maximum value of the drive source torque ( 1 t ) being dependent on a current system pressure ( 2 p ) of a hydraulic system of the transmission ( 2 ).

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Bühle Felix
• Platzer Falko
• Lemp Thomas

Classifications

• B60W2510/0291

  Clutch temperature · CPC title

• F16H59/68

  Inputs being a function of gearing status · CPC title

• B60W2710/0666

  Engine torque · CPC title

• B60W2510/107

  Temperature · CPC title

• B60W2510/1075

  fluid pressure, e.g. oil pressure · CPC title