Operation of a multi-speed vehicle transmission

Patent metadata

Field	Value
Publication number	US-11773969-B2
Application number	US-202217573021-A
Country	US
Kind code	B2
Filing date	Jan 11, 2022
Priority date	Jan 11, 2021
Publication date	Oct 3, 2023
Grant date	Oct 3, 2023

Abstract

Disclosed is a method for operating a multi-gear vehicle transmission having a plurality of shifting elements (A, B, C, D, E) for engaging the gears of the vehicle transmission, where, in a neutral gear an input (AN) and an output (AB) of the vehicle transmission are decoupled from one another, and where, in a driving gear the input (AN) and the output (AB) of the vehicle transmission are coupled to one another in order to propel the vehicle, by closing at least one shifting element (B). When the neutral gear is engaged, at least an actuation condition of a vehicle brake ( 11 ) and a transmission condition with elevated drag losses are detected, where, when the neutral gear is engaged, the shifting element (B) for the driving gear is vented if it is recognized that the vehicle brake ( 11 ) has been released and the transmission condition with elevated drag losses pertains.

First claim

The invention claimed is:

1. A method for operating a multi-gear vehicle transmission having an input, an output, and a plurality of shifting elements for engaging the gears of the vehicle transmission, the method comprising:
decoupling the input from the output to place the vehicle transmission in a neutral gear;
coupling the input to the output by closing at least one shifting element to place the vehicle transmission in a driving gear and to propel the vehicle;
detecting, when the vehicle transmission is in the neutral gear, an actuation condition of a vehicle brake and drag losses of the vehicle transmission; and
venting, when the vehicle transmission is in the neutral gear, the at least one shifting element for the driving gear if the actuation condition of the vehicle brake is a released condition and if the drag losses are elevated.

2. The method of claim 1 , wherein detecting the drag losses of the vehicle transmission comprises taking into account one or more of (i) a lubricant temperature of the vehicle transmission, (ii) an operation duration of the vehicle transmission since a motor start of a drive motor that is or can be coupled to the vehicle transmission, and (iii) a temperature model of the vehicle transmission.

3. The method of claim 1 , comprising prestressing or pre-filling with a pressure medium the shifting element for the driving gear when the vehicle transmission is in the neutral gear and the vehicle brake is actuated.

4. The method of claim 1 comprising:
closing at least two of the plurality of shifting elements of the vehicle transmission when the vehicle transmission is in the driving gear;
detecting a rolling condition of the vehicle; and
when the vehicle transmission is in the neutral gear,
venting the first of the said shifting elements if the actuation condition of the vehicle brake is the released condition and if the drag losses are elevated; and
venting the second of the said shifting elements if the actuation condition of the vehicle brake is a released condition, if the drag losses are elevated, and if the vehicle is rolling.

5. The method of claim 4 , wherein detecting the rolling condition includes taking into account one or more of (i) a drive output rotation speed (n AB ) of the vehicle transmission, (ii) a wheel rotation speed of the vehicle, and (iii) an acceleration of the vehicle.

6. The method of claim 4 , comprising, when the neutral gear is engaged and the vehicle brake has been actuated:
prestressing or pre-filling with a pressure medium the first of the shifting elements for the driving gear; and
closing the second of the shifting elements for the driving gear.

7. The method of claim 1 , comprising:
closing, when the vehicle transmission is in the driving gear, at least three or exactly three of the shifting elements of the vehicle transmission;
prestressing or pre-filling with pressure a medium the first of the shifting elements when the neutral gear is engaged, the vehicle brake is actuated, and the second of the shifting elements is closed; and
venting the third of the shifting elements.

8. The method of claim 1 , comprising closing at least three or exactly three shifting elements when placing the vehicle transmission in any of the driving gears.

9. A transmission control unit for the actuation of shifting elements of a vehicle transmission, wherein the transmission control unit is configured to carry out the method according to claim 1 .

10. A computer-readable storage medium, containing commands which, when carried out by a computer, enable the method according to claim 1 to be carried out.

11. A multi-gear vehicle transmission comprising:
a plurality of shifting elements for engaging gears of the vehicle transmission;
an input and an output of the vehicle transmission, wherein, in a neutral gear the input and the output of the vehicle transmission are decoupled from one another, and wherein, in a driving gear the input and the output of the vehicle transmission are coupled to one another by closing at least one shifting element in order to propel the vehicle;
a control unit configured to detect, when the neutral gear is engaged, at least an actuation condition of a vehicle brake and a transmission condition of elevated drag losses,
wherein, when the neutral gear is engaged, the control unit is configured to vent the at least one shifting element for the driving gear if release of the vehicle brake is recognized and the transmission condition of elevated drag losses pertains.

12. The multi-gear vehicle transmission of claim 11 , wherein detecting the drag losses of the vehicle transmission the control unit is configured to take into account one or more of (i) a lubricant temperature of the vehicle transmission, (ii) an operation duration of the vehicle transmission since a motor start of a drive motor that is or can be coupled to the vehicle transmission, and (iii) a temperature model of the vehicle transmission.

13. The multi-gear vehicle transmission of claim 11 , wherein the control unit is configured to prestress or pre-fill with a pressure medium the at least one shifting element for the driving gear when the vehicle transmission is in the neutral gear and the vehicle brake is actuated.

14. The multi-gear vehicle transmission of claim 11 , wherein the control unit is configured to:
close at least two of the plurality of shifting elements of the vehicle transmission when the vehicle transmission is in the driving gear;
detect a rolling condition of the vehicle; and
when the vehicle transmission is in the neutral gear,
vent the first of the said shifting elements if the actuation condition of the vehicle brake is the released condition and if the drag losses are elevated; and
vent the second of the said shifting elements if the actuation condition of the vehicle brake is a released condition, if the drag losses are elevated, and if the vehicle is rolling.

15. The multi-gear vehicle transmission of claim 14 , wherein, when detecting the rolling condition, the control unit takes into account one or more of (i) a drive output rotation speed (n AB ) of the vehicle transmission, (ii) a wheel rotation speed of the vehicle, and (iii) an acceleration of the vehicle.

16. The multi-gear vehicle transmission of claim 14 , wherein, when the neutral gear is engaged and the vehicle brake has been actuated, the control unit is configured to
prestress or pre-fill with a pressure medium the first of the shifting elements for the driving gear; and
close the second of the shifting elements for the driving gear.

17. The multi-gear vehicle transmission of claim 11 , wherein the control unit is configured to:
close at least three or exactly three of the shifting elements of the vehicle transmission when the vehicle transmission is in the driving gear;
prestress or pre-fill with pressure a medium the first of the shifting elements when the neutral gear is engaged, the vehicle brake is actuated, and the second of the shifting elements is closed; and
vent the third of the shifting elements.

18. The multi-gear vehicle transmission of 11 , wherein the control unit is configured to close at least three or exactly three shifting elements when placing the vehicle transmission in any of the driving gears.

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Blaser Jürgen
• Ley Fabian
• Winter Jens

Classifications

• F16H61/30 Primary

  Hydraulic {or pneumatic} motors {or related fluid control means} therefor · CPC title

• F16H61/06 Primary

  by controlling rate of change of fluid pressure · CPC title

• F16H61/2807

  using electric control signals for shift actuators, e.g. electro-hydraulic control therefor  (F16H61/30, F16H61/32 take precedence) · CPC title

• F16H2061/0455

  during shifts involving three or more shift members, e.g. release of 3-4 clutch, 2-4 brake and apply of forward clutch C1 · CPC title

• F16H2061/2823

  Controlling actuator force way characteristic, i.e. controlling force or movement depending on the actuator position, e.g. for adapting force to synchronisation and engagement of gear clutch · CPC title