METHOD FOR OPERATING A DRIVE DEVICE FOR A MOTOR VEHICLE AND CORRESPONDING DRIVE DEVICE

Abstract

A method for operating a drive unit for a motor vehicle. The drive unit has at least one internal combustion engine, an electric machine which is or may be drivingly coupled to the internal combustion engine, and a start-up clutch, via which the internal combustion engine and the electric machine are drivingly connected to an output shaft of the drive unit. In a start-up operation mode of the drive unit, the internal combustion engine is operated without ignition when the start-up clutch is open, and is cranked by the electric machine to a start-up speed, which is greater than an idle speed of the internal combustion engine. The internal combustion engine is ignition-operated and the start-up clutch is closed upon reaching the start-up speed. The invention further relates to a drive unit for a motor vehicle.

Claims

1-10. (canceled)

11. A method for operating a drive unit for a motor vehicle, wherein the drive unit has at least one internal combustion engine, one electric machine, which is or may be drivingly coupled to the internal combustion engine, and a start-up clutch, via which the internal combustion engine and the electric machine are drivingly connected to an output shaft of the drive unit, wherein, in a start-up operating mode of the drive unit, the internal combustion engine is operated without fuel ignition, when the start-up clutch is fully open and is cranked by the electric machine to a start-up speed, which is greater than an idle speed of the internal combustion engine, wherein the internal combustion engine is fuel-ignition operated and the start-up clutch closed, once the start-up speed has been reached.

12. The method according to claim 11, wherein fuel-ignition operation of the internal combustion engine is initiated immediately after reaching the start-up speed.

13. The method according to claim 11, wherein upon initiation of the fuel-ignition operation of the internal combustion engine by means of the electric machine, a torque is generated, which corresponds in magnitude to a torque provided by the internal combustion engine and is directed opposite thereto.

14. The method according to claim 3, wherein the torque is provided by the electric machine due to regenerative operation of the electric machine, and the electrical energy provided by the electric machine is temporarily stored or converted into heat during the regenerative operation.

15. The method according to claim 11, wherein the start-up clutch is closed after initiation of fuel-ignition operation of the internal combustion engine.

16. The method according to claim 11, wherein, when the start-up clutch is closed, the electric machine is deactivated or, after closing the start-up clutch, a torque supporting the torque of the internal combustion engine is generated by the electric machine.

17. The method according to claim 11, wherein the start-up speed is selected to be equal to the speed at which the internal combustion engine provides maximum torque.

18. The method according to claim 11, wherein the start-up speed is selected to be equal to a speed, at which a maximum torque of the internal combustion engine corresponds to a maximum torque, which can be provided by the electric machine.

19. The method according to claim 11, wherein a disconnecting clutch is drivingly provided between the internal combustion engine and the electric machine and is closed in order to crank the internal combustion engine by means of the electric machine.

20. A drive device for a motor vehicle, for carrying out the method according to claim 11.

21. The method according to claim 12, wherein upon initiation of the fuel-ignition operation of the internal combustion engine by means of the electric machine, a torque is generated, which corresponds in magnitude to a torque provided by the internal combustion engine and is directed opposite thereto.

22. The method according to claim 12, wherein the start-up clutch is closed after initiation of fuel-ignition operation of the internal combustion engine.

23. The method according to claim 13, wherein the start-up clutch is closed after initiation of fuel-ignition operation of the internal combustion engine.

24. The method according to claim 14, wherein the start-up clutch is closed after initiation of fuel-ignition operation of the internal combustion engine.

25. The method according to claim 12, wherein, when the start-up clutch is closed, the electric machine is deactivated or, after closing the start-up clutch, a torque supporting the torque of the internal combustion engine is generated by the electric machine.

26. The method according to claim 13, wherein, when the start-up clutch is closed, the electric machine is deactivated or, after closing the start-up clutch, a torque supporting the torque of the internal combustion engine is generated by the electric machine.

27. The method according to claim 14, wherein, when the start-up clutch is closed, the electric machine is deactivated or, after closing the start-up clutch, a torque supporting the torque of the internal combustion engine is generated by the electric machine.

28. The method according to claim 15, wherein, when the start-up clutch is closed, the electric machine is deactivated or, after closing the start-up clutch, a torque supporting the torque of the internal combustion engine is generated by the electric machine.

29. The method according to claim 12, wherein the start-up speed is selected to be equal to the speed at which the internal combustion engine provides maximum torque.

30. The method according to claim 13, wherein the start-up speed is selected to be equal to the speed at which the internal combustion engine provides maximum torque.

Description

[0039] The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The only FIGURE represents [0040] a schematic diagram of a drive unit for a motor vehicle.

[0041] The FIGURE shows a schematic diagram of a motor vehicle 1 having a drive unit 2 and at least one wheel 3, which can be driven by means of the drive unit 2. The drive unit 1 has an internal combustion engine 4 and an electric machine 5, which are at least temporarily drivingly coupled to an output shaft 6 of the drive unit 2. In the exemplary embodiment shown here, the output shaft 6 is drivingly connected to an intermediate shaft 8 via a start-up clutch 7, which is rigidly and permanently coupled to the electric machine 5.

[0042] For example, the electric machine 5 is connected to the intermediate shaft 8 via an intermediate gear 9. The internal combustion engine 4, on the other hand, is drivingly connected to the intermediate shaft 8 via a disconnect clutch 10. In this respect, when the disconnecting clutch 10 is open, the intermediate shaft 8 is fully decoupled from the internal combustion engine 4, and when the disconnect clutch 10 is closed, it is rigidly connected thereto. Similarly, the output shaft 6 is fully decoupled from the intermediate shaft 8, when the start-up clutch 7 is open, and rigidly coupled thereto, when the start-up clutch 7 is closed. The electric machine 5 is electrically connected to an energy storage device 11, which is used for intermediate storage of electrical energy.

[0043] In the depicted exemplary embodiment, the output shaft 6 is drivingly connected to the at least one wheel 3 of the motor vehicle 1 via a gearbox 12. Obviously, the gearbox 12 may be provided elsewhere in the drive unit 2, or may be omitted altogether. It is also possible for the start-up clutch 7 to be designed as integrated into the gearbox 12, such that the output shaft 6 is also provided in the gearbox 12, e.g., as a layshaft, or the like.

[0044] It is now provided that, in a start-up operating mode of the drive unit 2, the start-up clutch 7 is opened fully, if not already fully open. Subsequently, the internal combustion engine 4 is cranked by the electric machine 5 to a start-up speed that is greater than the idle speed of the internal combustion engine 4. In this case, the internal combustion engine 4 is operated without fuel ignition. This means that no fuel is burned therein, in particular no fuel is being supplied thereto. The electrical energy for cranking the internal combustion engine 4 by means of the electric machine 5 is preferably drawn from the energy storage device 11.

[0045] After reaching the start-up speed, the internal combustion engine 4 is switched from non-fuel-ignition operation to fuel-ignition operation. Preferably, the internal combustion engine 4 is adjusted, such that a torque greater than 0 Nm is supplied. At the same time, the electric machine 5 is actuated, such that it generates a torque, which counteracts the torque of the internal combustion engine 4 and matching it in terms of magnitude. Accordingly, despite the generated torque, the speed of the internal combustion engine 4 is kept constant, namely at the start-up speed, by means of the electric machine 5.

[0046] In order to accelerate the motor vehicle 1, the start-up clutch 7 is subsequently closed, and the electric machine 5 is either deactivated or set to assist the torque generated by the internal combustion engine 4. In the latter case, a drive torque is present at the output shaft 6 and is provided jointly by the internal combustion engine 4 and the electric machine 5. Due to the previously performed biasing of the internal combustion engine 4, a very large drive torque can be provided very rapidly at the output shaft.

REFERENCE NUMERAL LIST

[0047] 1 Motor vehicle [0048] 2 Drive unit [0049] 3 Wheel [0050] 4 Internal combustion engine [0051] 5 Electric machine [0052] 6 Output shaft [0053] 7 Start-up clutch [0054] 8 Intermediate shaft [0055] 9 Intermediate gear [0056] 10 Disconnect clutch [0057] 11 Energy storage device [0058] 12 Manual gearbox