METHOD FOR CONTROLLING A POWERTRAIN

Abstract

A system and method for controlling a powertrain, comprising an internal combustion engine connected to a double clutch transmission having a first and a second partial transmission with at least one shiftable transmission stage. A first friction clutch is arranged between the internal combustion engine and the first partial transmission, and a second friction clutch is arranged between the internal combustion engine and the second partial transmission. An engine torque of the internal combustion engine is transmitted by the first and second friction clutches to the first or second partial transmissions to provide a drivetrain torque at the output of the double clutch transmission. The powertrain is monitored for an occurrence of juddering oscillations, wherein in response to juddering oscillations being detected a regeneration process of one of the first and second friction clutches is triggered, and a friction lining is removed in the regeneration process.

Claims

1. A method for controlling a powertrain, comprising an internal combustion engine connected to a double clutch transmission having a first and a second partial transmission with at least one shiftable transmission stage, wherein a first friction clutch is arranged between the internal combustion engine and the first partial transmission, and a second friction clutch is arranged between the internal combustion engine and the second partial transmission, the method comprising: transmitting an engine torque of the internal combustion engine by the first and second friction clutches to the first or second partial transmissions to provide a drivetrain torque at an output of the double clutch transmission; and, monitoring the powertrain for an occurrence of juddering oscillations, wherein in response to juddering oscillations being detected a regeneration process of one of the first and second friction clutches is triggered, wherein a friction lining is removed in the regeneration process.

2. The method of claim 1, wherein monitoring the powertrain for the occurrence of the juddering oscillations is carried out by a judder observer, the judder observer activating or deactivating the regeneration process.

3. The method of claim 1, wherein the juddering oscillations are compensated by a traction control system, wherein in response to a judder threshold value being exceeded by an amplitude of the juddering oscillations, the regeneration process of the first or second friction clutch is triggered.

4. The method of claim 1, wherein during the regeneration process a load profile of the powertrain is varied by the first or second friction clutch.

5. The method of claim 4, wherein the regeneration process is carried out on the first friction clutch, the first friction clutch being in an active state to transmit the engine torque, while the engine torque of the internal combustion engine is applied to the second friction clutch, the second friction clutch being in an inactive state and being in a slipping state, wherein the second friction clutch is moved in a direction of a closed state, and a slip control system monitors a slipping rotational speed applied to the second friction clutch.

6. The method of claim 5, wherein the first friction clutch remains closed during the regeneration process.

7. The method of claim 5, wherein the first friction clutch is opened during the regeneration process, and the slip control system reduces a clutch torque transmitted by the first friction clutch by the clutch torque that is transmitted by the second friction clutch.

8. The method of claim 1, wherein in response to a low ambient temperature of the powertrain, an increased slipping rotational speed is generated at the second friction clutch.

9. The method of claim 1, wherein in response to low load judder being detected, wear is generated at the second friction clutch.

10. The method of claim 1, wherein an engine torque of approximately 10 to 25 Nm is applied to the second friction clutch.

11. A powertrain, comprising: an internal combustion engine connected to a double clutch transmission having a first and a second partial transmission with at least one shiftable transmission stage; a first friction clutch arranged between the internal combustion engine and the first partial transmission; and, a second friction clutch arranged between the internal combustion engine and the second partial transmission, wherein: the first or second friction clutch is configured to transmit an engine torque of the internal combustion engine to the first or second partial transmissions to provide a drivetrain torque at an output of the double clutch transmission; and, in response to an occurrence of juddering oscillations in the powertrain, a regeneration process of the first or second friction clutches is triggered and a friction lining is removed in the regeneration process.

12. The powertrain of claim 11, wherein the juddering oscillations are detected by a judder observer, the judder observer activating or deactivating the regeneration process.

13. The powertrain of claim 11, further comprising a traction control system configured to compensate for the juddering oscillations, wherein the regeneration process of the first or second friction clutch is triggered in response to a judder threshold value being exceeded by an amplitude of the juddering oscillations.

14. The powertrain of claim 11, wherein the first or second friction clutch is configured to vary a load profile of the powertrain during the regeneration process.

15. The powertrain of claim 14, wherein the regeneration process is carried out on the first friction clutch, the first friction clutch being in an active state to transmit the engine torque, while the engine torque of the internal combustion engine is applied to the second friction clutch, the second friction clutch being in an inactive state and being in a slipping state, wherein the second friction clutch is moved in a direction of a closed state, and wherein a slipping rotational speed applied to the second friction clutch is monitored by a slip control system.

16. The powertrain of claim 15, wherein the first friction clutch is configured to remain closed during the regeneration process.

17. The powertrain of claim 15, wherein the first friction clutch is opened during the regeneration process, and the slip control system reduces a clutch torque transmitted by the first friction clutch by the clutch torque that is transmitted by the second friction clutch.

18. The powertrain of claim 11, wherein the second friction clutch is configured to generate an increased slipping rotational speed in response to an ambient temperature of the powertrain being below a corresponding threshold.

19. The powertrain of claim 11, wherein wear is generated at the second friction clutch in response to low load judder being detected.

20. The powertrain of claim 11, wherein an engine torque of approximately 10 to 25 Nm is applied to the second friction clutch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] This disclosure contemplates numerous embodiments. One of these embodiments will be explained in more detail with reference to the figures illustrated in the drawing, in which:

[0019] FIG. 1 shows a basic illustration of a powertrain with a double clutch transmission.

DETAILED DESCRIPTION

[0020] Embodiments according to this disclosure will be explained using the example of a powertrain 1 with a double clutch transmission. FIG. 1 shows a basic illustration of the powertrain 1 as is used in motor vehicles. This powertrain 1 comprises an internal combustion engine 2 and two partial transmission 3, 4. The connection of a partial transmission 3, 4 to the internal combustion engine 2 is carried out by means of one partial clutch 5, 6 in each case, which partial clutches 5, 6 are actuated by a control unit 15. The first partial transmission 3 has the uneven-numbered gear speeds 7, while the second partial transmission 4 comprises the even-numbered gear speeds 8. The gear speeds 7 and 8 are connected where necessary to a transmission input shaft 9, 10 of a transmission 11 which drives the drive wheels 14 via an output shaft 12 and a differential 13.

[0021] In such a powertrain 1 with a double clutch transmission, a gear speed 7 of the partial transmission 3 is connected to the transmission input shaft 9, while the gear speed 8 of the other partial transmission 4 is engaged. For this purpose, the behavior of the two partial clutches 5, 6 has to be set precisely in order to avoid disruption. A slipping rotational speed of the partial clutch 5 is determined by the control unit 15 by means of a rotational speed sensor 16, which detects the rotational speed of the internal combustion engine 2, and a rotational speed sensor 17, which monitors the rotational speed at the transmission input shaft 9. A further rotational speed sensor 18 is also connected to the control unit 15 and detects the rotational speed at the transmission input shaft 10 in order to determine the slipping rotational speed of the partial clutch 6. This slipping rotational speed is detected as a function of whether the partial clutches 5, 6 are closed or opened.

[0022] Owing to the friction properties of the partial clutches 5, 6, juddering oscillations occur in the rotational speed of the transmission input shaft which are monitored by the rotational speed sensors 17 and 18, the excitation frequency of which juddering oscillations may depend on the slip of the respective partial clutch 5, 6, the rotational speed of the transmission input shaft or the engine rotational speed. The juddering oscillations are detected by a judder observer 19 which is present in the control unit 15. The amplitudes of the juddering oscillations are evaluated by means of a juddering oscillation control system and compared with a juddering oscillation threshold value. If the judder observer detects that the juddering oscillations which occur can no longer be compensated by the juddering oscillation control system, the control unit 15 starts a regeneration process for the inactive partial clutch 6 of the double clutch transmission during the operation of the vehicle. During this regeneration process, approximately the entire engine torque of the internal combustion engine 2 is applied to the first active partial clutch 5. A drivetrain torque for driving the drive wheels 14 is therefore taken off at the transmission output shaft 12, which corresponds to the engine torque of the internal combustion engine 2. During this state of the first partial clutch 5 the second partial clutch 6 is in the slipping state and is therefore inactive. In order to generate abrasion of the friction lining at the inactive partial clutch 6, an engine torque of approximately 20 Nm is applied to this partial clutch 6, and the partial clutch 6 is moved in the direction of closing, with the result that the slipping rotational speed is set at this partial clutch 6. Depending on the magnitude of the slip, abrasion of the friction lining of the inactive partial clutch 6 takes place as a result of wear. A relatively long setting of the slip can, however, also give rise to an increase in temperature of the inactive partial clutch 6, which entails increased abrasion of the friction lining of the partial clutch 6. In order to maintain the stability of the double clutch transmission and to keep constant the drivetrain torque which is taken off at the transmission output shaft 12, a slip control system 20 which is present in the control unit 15 subtracts the engine torque of 20 Nm, which is present at the inactive partial clutch 6, from the engine torque which is transmitted to the active partial clutch 5 by the internal combustion engine 2.

[0023] By virtue of the proposed solution, the load profile of the powertrain is changed selectively by setting the active and inactive partial clutches 5, 6 in order to therefore move through critical situations such as juddering oscillations more quickly or even to avoid them entirely.

LIST OF REFERENCE NUMBERS

[0024] 1 Powertrain [0025] 2 Internal combustion engine [0026] 3 First partial transmission [0027] 4 Second partial transmission [0028] 5 First partial clutch [0029] 6 Second partial clutch [0030] 7 Uneven-numbered gear speed [0031] 8 Even-numbered gear speed [0032] 9 Transmission input shaft [0033] 10 Transmission input shaft [0034] 11 Transmission [0035] 12 Transmission output shaft [0036] 13 Differential [0037] 14 Drive wheels [0038] 15 Control unit [0039] 16 Rotational speed sensor [0040] 17 Rotational speed sensor [0041] 18 Rotational speed sensor [0042] 19 Judder observer [0043] 20 Slip control system