METHOD FOR OPERATING A HYBRID DRIVE ASSEMBLY FOR A MOTOR VEHICLE AND CORRESPONDING HYBRID DRIVE ASSEMBLY

Abstract

A method for operating a hybrid drive assembly for a motor vehicle, which has an internal combustion engine and an electric engine. A separating clutch arranged in drive terms between the internal combustion engine and the electric engine is set to a target clutch torque by at least partially engaging during an attempt to start the internal combustion engine. An actual clutch torque actually transmitted via the separating clutch and a speed of the internal combustion engine are determined during the attempt to start, and if a characteristic value dependent on the actual clutch torque exceeds a threshold value and if an integral of the speed over time continuously falls below a limit value during the attempt to start, the attempt to start is aborted.

Claims

1-10. (canceled)

11. A method for operating a hybrid drive assembly for a motor vehicle, comprising: an internal combustion engine and an electric engine, wherein a separating clutch arranged between the internal combustion engine and the electric engine is set to a target clutch torque by at least partially engaging it during an attempt to start the internal combustion engine, wherein an actual clutch torque actually transmitted via the separating clutch and a speed of the internal combustion engine are determined during the attempt to start, and if a characteristic value dependent on the actual clutch torque exceeds a threshold value and if an integral of the speed over time continuously falls below a limit value during the attempt to start, the attempt to start is aborted.

12. The method according to claim 11, wherein the attempt to start is only aborted if a temperature threshold value is additionally exceeded by a temperature of the separating clutch.

13. The method according to claim 11, wherein to abort the attempt to start the separating clutch is disengaged and an error entry is entered in the error memory, wherein subsequently an engagement of the separating clutch is prevented, as long as the error entry is entered in the error memory.

14. The method according to claim 11, wherein the error entry is deleted from the error memory after a specific period of time has elapsed after the attempt to start was aborted.

15. The method according to claim 11, wherein the error entry is deleted from the error memory only if the temperature of the separating clutch falls below the threshold value over the specific period of time.

16. The method according to claim 11, wherein a maximum value of the actual clutch torque occurring after the at least partial engagement of the separating clutch is used as the characteristic value.

17. The method according to claim 11, wherein a difference between the maximum value and a minimum value of the actual clutch torque occurring before the partial engagement of the separating clutch is used as the characteristic value.

18. The method according to claim 11, wherein the target clutch torque is set to a first value when engaging and increased in the direction of a second value during the attempt to start until the speed of the internal combustion engine has reached a minimum speed.

19. The method according to claim 11, wherein the target clutch torque is increased in specific target clutch torque increments, with the attempt to start being aborted if the second value is reached or exceeded by the target clutch torque.

20. A hybrid drive assembly for a motor vehicle, in particular for carrying out the method according claim 11, wherein the hybrid drive assembly has an internal combustion engine and an electric engine and is designed to set a separating clutch arranged in drive terms between the internal combustion engine and the electric engine, to a target clutch torque by at least partially engaging during an attempt to start the internal combustion engine, wherein the hybrid drive assembly is further designed to determine an actual clutch torque actually transmitted via the separating clutch and a speed of the internal combustion engine during the attempt to start the internal combustion engine, wherein, if a characteristic value dependent on the actual clutch torque exceeds a threshold value and if an integral of the speed over time continuously falls below a limit value during the attempt to start, the attempt to start is aborted.

21. The method according to claim 12, wherein to abort the attempt to start the separating clutch is disengaged and an error entry is entered in the error memory, wherein subsequently an engagement of the separating clutch is prevented, as long as the error entry is entered in the error memory.

22. The method according to claim 12, wherein the error entry is deleted from the error memory after a specific period of time has elapsed after the attempt to start was aborted.

23. The method according to claim 13, wherein the error entry is deleted from the error memory after a specific period of time has elapsed after the attempt to start was aborted.

24. The method according to claim 12, wherein the error entry is deleted from the error memory only if the temperature of the separating clutch falls below the threshold value over the specific period of time.

25. The method according to claim 13, wherein the error entry is deleted from the error memory only if the temperature of the separating clutch falls below the threshold value over the specific period of time.

26. The method according to claim 14, wherein the error entry is deleted from the error memory only if the temperature of the separating clutch falls below the threshold value over the specific period of time.

27. The method according to claim 12, wherein a maximum value of the actual clutch torque occurring after the at least partial engagement of the separating clutch is used as the characteristic value.

28. The method according to claim 13, wherein a maximum value of the actual clutch torque occurring after the at least partial engagement of the separating clutch is used as the characteristic value.

29. The method according to claim 14, wherein a maximum value of the actual clutch torque occurring after the at least partial engagement of the separating clutch is used as the characteristic value.

30. The method according to claim 15, wherein a maximum value of the actual clutch torque occurring after the at least partial engagement of the separating clutch is used as the characteristic value.

Description

BRIEF DESCRIPTION OF THE FIGURE(S)

[0041] The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the drawing, without limiting the invention.

[0042] The FIGURE shows a schematic representation of a hybrid drive assembly for carrying out the method according to this description.

DETAILED DESCRIPTION

[0043] The FIGURE shows a hybrid drive assembly 1 for a motor vehicle, which has an internal combustion engine 2 and an electric engine 3. A separating clutch 4 is arranged in drive terms between the internal combustion engine 2 and the electric engine 3 and is present, for example, as a multi-plate clutch. The hybrid drive assembly 1 at least temporarily provides a drive torque for driving the motor vehicle. The drive torque is provided by the internal combustion engine 2 and the electric engine 3 alone or at least temporarily together in a hybrid operation.

[0044] Internal combustion engine 2 is switched off or stopped at least temporarily during hybrid operation of hybrid drive assembly 1. In particular, provision is made for the internal combustion engine 2 to be started when a corresponding request variable is present and for at least part of the drive torque to be generated by means of the internal combustion engine 2.

[0045] In order to start the internal combustion engine 2, an attempt to start is carried out. The attempt to start begins when the request variable is present or when the separating clutch 4 is at least partially engaged to start the internal combustion engine 2 and ends either with a successful start of the internal combustion engine 2 or with the attempt to start being aborted. In the event of a successful start, the internal combustion engine 2 is then able to provide the drive torque at least partially independently.

[0046] When the internal combustion engine 2 starts successfully, it reaches a minimum speed, an idle speed or a synchronous speed. The synchronous speed is understood to mean a speed of the internal combustion engine that corresponds to a speed of the electric engine 3 that is present at the moment. When the synchronous speed is present, there is no slip at the separating clutch 4, so that the separating clutch 4 is completely engaged and a rigid connection can be established between the internal combustion engine 2 and the electric engine 3.

[0047] During the attempt to start, the speed of the internal combustion engine 2 is increased from standstill towards the minimum speed. At the beginning of the attempt to start, the internal combustion engine 2 is preferably at a standstill or has a speed that is less than the minimum speed.

[0048] During the attempt to start, the separating clutch 4 is at least partially engaged. Here, the separating clutch 4 is set to a target clutch torque. The target clutch torque is used to increase the speed of the internal combustion engine 2 towards the minimum speed and preferably corresponds to a predetermined drag torque, when the speed of the internal combustion engine 2 can reach the minimum speed.

[0049] The target clutch torque is increased by further engaging the separating clutch 4, starting from a first value towards a second value. The target clutch torque is increased until the speed of internal combustion engine 2 has reached a minimum speed or the attempt to start is aborted. In particular, it can be provided that the target clutch torque is stepwise increased in specific target clutch torque increments. In particular, said increasing takes place periodically, for example at fixed time intervals.

[0050] During the attempt to start, the actual clutch torque actually transmitted via the separating clutch 4 is determined. The actual clutch torque is determined, for example, from a characteristic map of the separating clutch 4 or alternatively calculated from a speed gradient and/or a mass moment of inertia. A time course of the actual clutch torque can be formed on the basis of the determined actual clutch torque. From the course of the actual clutch torque over time, a characteristic value is determined which corresponds to a maximum value of the actual clutch torque occurring after the at least partial engagement of the separating clutch 4.

[0051] A maximum value of the actual clutch torque occurring within a specific time window after the engagement of the separating clutch 4 is preferably used as the characteristic value and not a maximum value occurring over the entire attempt to start. Alternatively, a difference between the maximum value, in particular the maximum value occurring within the time window, and a minimum value of the actual clutch torque occurring before the at least partial engagement of the separating clutch 4 is used as a characteristic value.

[0052] In addition, a course of the speed of the internal combustion engine 2 over time is determined. An integral over time is determined from the course of the speed of the internal combustion engine 2 over time. In particular, measured values of the speed over time are summed up for this purpose.

[0053] Provision is made to abort the attempt to start if the characteristic value exceeds a threshold value and the integral of the speed continuously falls below a limit value during the attempt to start. In addition, provision can be made that the attempt to start is only aborted if also a temperature of the separating clutch 4 exceeds a temperature threshold value. For example, the threshold is set to correspond to a torque or a characteristic value at which the engine 2 can normally be started.

[0054] To abort the attempt to start, the separating clutch 4 is disengaged and an error entry is made in an error memory. Engagement of the separating clutch 4 is then prevented as long as the error entry is entered in the error memory. The error entry is deleted from the error memory after a specific period of time has elapsed after the attempt to start was aborted, and/or when the temperature of the separating clutch 4 falls below the temperature threshold value over the specific period of time.

[0055] The method according to the invention avoids damage or destruction of the separating clutch 4 if the internal combustion engine 2 is sluggish or jammed.

LIST OF REFERENCE NUMERALS

[0056] 1 hybrid drive assembly [0057] 2 internal combustion engine [0058] 3 electric engine [0059] 4 disconnect clutch