WO2007128260A1

WO2007128260A1 - Process for operating a drive train

Info

Publication number: WO2007128260A1
Application number: PCT/DE2007/000686
Authority: WO
Inventors: Dierk Reitz; Martin Dilzer
Original assignee: Luk Lamellen Und Kupplungsbau Beteiligungs Kg
Priority date: 2006-05-04
Filing date: 2007-04-19
Publication date: 2007-11-15
Also published as: DE112007000968A5; JP2009535256A

Abstract

In a process for operating a motor vehicle drive train that is the drive for a combustion engine (12), the drive shaft can be coupled to a drive shaft (15) with a coupling (21, 22), wherein the motor vehicle drive shaft has an electric machine (13) with a drive connection to the drive shaft that can be operated at least as a generator, and the drive shaft is driven with the help of the combustion engine. The coupling is opened, and the combustion engine is switched off. The electric machine is driven by the still moving drive shaft while the combustion engine is slowing down, and braking torque is applied to the drive shaft by the electrical energy generated by the electric machine. A speed signal for the combustion engine is recorded and detects any oscillations in the speed signal. When oscillations occur, the coupling is actuated in such a controlled manner that an opposing torque is transmitted to the drive shaft of the combustion engine over the coupling. The braking torque of the electric machine is reduced in accordance with the torque transmitted over the coupling on the drive shaft.

Description

A method of operating a motor vehicle drive train

The invention relates to a method for operating a motor vehicle drive train having an internal combustion engine as a drive, the drive shaft via at least one clutch with an output shaft can be coupled, wherein the motor vehicle drive train having a standing in drive connection with the output shaft electric machine having, at least as a generator is operable, wherein the output shaft is driven by means of the internal combustion engine, wherein the clutch is opened and the internal combustion engine is switched off, and wherein the electric machine driven during the running of the internal combustion engine by the still moving output shaft and by generating electrical energy by means of the electric Machine a braking torque is exerted on the output shaft.

Such a method is from the book 7. LuK Colloquium 11./12. April 2002, pages 254 and 255, publisher: LuK GmbH & Co., Bühl / Baden known. In this case, the internal combustion engine designed as a reciprocating internal combustion engine is decoupled in overrun by opening a arranged between the drive shaft and the output shaft clutch from the output shafts and thus standing in driving connection drive wheels of the motor vehicle for recovering braking energy. The deceleration of the motor vehicle takes over the electric machine, which exerts a regenerative braking torque on the output shaft depending on the speed, brake pedal position and translation of arranged between the internal combustion engine and the output shaft change gear while converting the kinetic energy of the motor vehicle into electrical energy. After disconnecting the internal combustion engine from the output shaft, the internal combustion engine is switched off to save fuel. When the internal combustion engine runs out, vibrations which are transmitted to the vehicle body via the engine bearings occur due to the gas forces acting in the combustion chamber of the internal combustion engine. These vibrations can be perceived as disturbing by the vehicle passengers.

From DE 40 15 701 C2, a method is also already known in which a speed signal for the drive shaft of the internal combustion engine is detected on an internal combustion engine designed as a reciprocating internal combustion engine, which has during its operation to a mean drive torque periodically changing drive torque , The speed signal is forwarded to a control device, by which the operating conditions of the Combustion engine can be influenced. With the internal combustion engine, a connectable to a vehicle battery electric machine can be connected. For the purpose of partial relief of the internal combustion engine, this energy can only be removed by the electric machine if, during the periodically changing drive torque, the instantaneous drive torque is not smaller than the average drive torque. In a corresponding manner, this energy can be supplied from the electric machine to a partial relief of the internal combustion engine, if at the periodically changing drive torque, the instantaneous drive torque is smaller than the average drive torque. However, the method is not readily applicable to a powertrain that includes a clutch that decouples the internal combustion engine from the output shaft in coasting mode.

There is therefore the object to provide a method of the type mentioned, which makes it possible to reduce the oscillations occurring when the internal combustion engine expires in a simple manner.

This object is achieved by a method for operating a motor vehicle drive train having as a drive an internal combustion engine whose drive shaft is coupled via at least one clutch to an output shaft, wherein the motor vehicle drive train having a standing in drive connection with the output shaft electrical machine which, at least is operated as a generator, wherein the output shaft is driven by means of the internal combustion engine, wherein the clutch is opened and the internal combustion engine is switched off, wherein the electric machine driven during the running out of the internal combustion engine by the still moving output shaft and by generating electrical energy by means of electric machine, a braking torque is applied to the output shaft, wherein a speed signal for the internal combustion engine is detected, wherein it is detected whether in the speed signal Auspendelschwingungen present sin d, wherein the occurrence of Auspendelschwingungen the clutch is operated regulated such that via the coupling a Ausstoßelschwingungen the counteracting vibrations is transmitted to the drive shaft of the internal combustion engine, and wherein the braking torque of the electric machine is reduced in accordance with the transmitted via the clutch to the drive shaft torque ,

Advantageously, therefore, the clutch is controlled in response to the speed variations of the internal combustion engine caused by the Auspendelschwingungen closed to decelerate the drive shaft of the internal combustion engine, if the instantaneous speed of the internal combustion engine is greater than their average or smoothed rotary number. If the instantaneous speed of the internal combustion engine is less than its average or smoothed speed, the clutch is opened controlled to relieve the loaded by gas forces drive shaft and thus to dampen the vibrations. So that the torque transmitted via the clutch is not forwarded via the output shaft to the drive wheels of the motor vehicle, the braking torque of the electric machine is reduced in accordance with the torque transmitted via the clutch to the output shaft. Thus, the Auspendelschwingungen can be easily damped.

In an advantageous embodiment of the invention, a torque is transmitted to the drive shaft of the internal combustion engine by means of the clutch, which is greater in magnitude than it was the braking torque of the electric machine immediately prior to applying this torque, wherein for compensating over the clutch on the Drive shaft transmitted torque, the braking torque of the electric machine is reduced so that the electric machine operates as an electric motor and drives the drive shaft. The electric machine can thus be switched briefly to the engine operation to suppress strong Auspendelschwingungen even more effective.

In a preferred embodiment of the invention it is provided that the speed signal is compared with a speed limit, and that the controlled closing of the clutch is disabled when the speed signal is greater than the speed limit. Vibrations in the speed signal are thus compensated only at low speeds at which Auspendelschwingungen can occur at the internal combustion engine, which are perceived by the vehicle users as disturbing. At higher speeds, vibration compensation is disabled to reduce clutch wear.

Conveniently, the motor vehicle drive train in addition to the first clutch, a second clutch, wherein means of the first clutch, the internal combustion engine is separated from the output shaft and the electric motor is connected to the drive shaft by means of the second clutch, and wherein for compensating the Auspendelschwingungen the first clutch is operated regulated. The method can thus also be used in a hybrid drive train with a dual-clutch transmission.

An exemplary embodiment of the invention is explained in more detail below with reference to the drawing. Show it:

1 is a schematic representation of a motor vehicle drive train, 2 is a graphical representation of the torque curve of a reciprocating internal combustion engine during coasting, wherein the abscissa is the time and the ordinate the torque is plotted,

Fig. 3 is a graphical representation of a clutch on the crankshaft of

Hubkolben-Brennkraftmaschine transferred braking torque, where the abscissa is the time and the ordinate the torque is plotted, and

Fig. 4 is a graph of the resulting torque from the torque in Fig. 2 and 3, wherein the abscissa is the time and the ordinate the torque is plotted.

A schematically illustrated in FIG. 1, designated as a whole by 11 motor vehicle drive train has a designed as a reciprocating engine internal combustion engine 12 and an electric machine 13 as a drive, which can be brought via a dual-clutch transmission 14 with an output shaft 15 in drive connection. The internal combustion engine 12 has a drive shaft 16 and a device, not shown in the drawing for detecting a rotational speed signal of the drive shaft 16. The latter may for example have an inductive speed sensor.

The electric machine 13 is connected via an electrical control device 17 at a

Vehicle battery connected. With the aid of the control device 17, the electric machine 1 can be operated both as a drive motor and as a generator for charging the vehicle battery and / or food to electrical consumers.

The dual-clutch transmission 14 has a first partial transmission with a first input shaft

18 and a second partial transmission with a second input shaft 19. The input shafts 18,

19 are connected by means of a switching device 20 each via a gear to the output shaft 15. As can be seen in Fig. 1, a first, third and fifth gear and a reverse gear of the first input shaft 18 and a second, fourth and sixth gear of the second input shaft 19 are assigned. With the aid of the switching device 20, the gears associated with individual gears can be brought into engagement with gears arranged on the corresponding input shafts 18, 19.

The first input shaft 18 is connected via a first clutch 21 and the second input shaft 19 via a second clutch 22 to the drive shaft 16 of the internal combustion engine 12. Pelbar. The switching device 20 and the clutches 21, 22 can be actuated by means of electromotive actuators not shown in detail in the drawing. These can be controlled via a control unit.

In a first shift strategy is an odd for internal combustion engine driving

Gear 1, 3 or 5 is engaged and the second gear is in neutral position. The first clutch 21 is closed, so that the drive shaft 16 of the internal combustion engine 12 is coupled to the output shaft 15 via the first clutch 21, the first input shaft 18 and the engaged gear. The second clutch 22 is closed, so that the drive shaft 16 of the internal combustion engine 12 is coupled to the electric machine 13 via the second clutch 22 and the second input shaft 19. Depending on the operating mode of the motor vehicle, the electric machine 13 can be operated in this case as a generator or as a motor.

For the recovery of stored in the motor vehicle kinetic energy in

Push operation, both clutches 21, 22 are opened and the internal combustion engine 12 is turned off. At the second partial transmission, a straight gear is engaged in idle electric machine 13, so that the electric machine 13 is then connected via the straight gear to the output shaft 15. While the electric machine 13 is driven by the output shaft 15 still in motion, a braking torque is applied to the output shaft 15 by generating electrical energy by means of the electric machine 13.

It detects a speed signal for the internal combustion engine 12, for example by means of an inductive sensor, which cooperates in a conventional manner with a arranged on the drive shaft 16 of the internal combustion engine 12 gear or ring gear magnetically. If the speed signal falls below a predetermined speed limit, it is checked whether Ausstoßelschwingungen are present in the speed signal. 2, the torque curve for the drive shaft 16 of the unloaded combustion engine 12 is shown graphically. It can clearly be seen that the torque is subject to periodic fluctuations due to gas forces occurring in the combustion chamber, which cause oscillations. When pendulum oscillations occur, the first clutch 21 is operated in a regulated manner in such a way that a torque counter to the oscillating oscillations is transmitted to the drive shaft 16 of the internal combustion engine 12 via the first clutch 21. In this case, the first clutch 21 is closed closed when the current speed of the drive shaft 16 is smaller than the average speed. simultaneously the braking torque of the electric machine 13 is reduced in accordance with the transmitted via the first clutch 21 to the output shaft 15 torque.

The transmitted via the first clutch 21 to the drive shaft 16 torque is in

Fig. 3 illustrated by way of example graphically. It can clearly be seen that the maxima of this torque coincide in time with the minima of the torque curve in FIG. 2. The torque resulting from the torque of the drive shaft 16 shown in FIG. 2 and the torque transmitted via the first clutch 21 is shown in FIG. 4. By comparing FIG. 4 with FIG. 2, it becomes clear that the torque fluctuations occurring on the drive shaft 16 are smoothed by the controlled actuation of the first clutch 21 and thus the oscillatory oscillations are attenuated.

In a second shift strategy, an odd gear 1, 3 or 5 is inserted for internal combustion engine driving and on the second partial transmission, a straight gear is preselected. The first clutch 21 is closed, so that the drive shaft 16 of the internal combustion engine 12 is coupled to the output shaft 15 via the first clutch 21, the first input shaft 18 and the engaged gear. The second clutch 22 is opened and the electric machine 13 is coupled to the output shaft 15 via the preselected gear. The electric machine 13 is operated as a generator.

For the recovery of stored in the motor vehicle kinetic energy in

Pushing operation, the first clutch 21 is opened and the internal combustion engine 12 is turned off. While the electric machine 13 is still driven by the output shaft 15 still in motion, a braking torque is applied to the output shaft 15 by generating electrical energy by means of the electric machine 13. The speed signal for the internal combustion engine 12 is detected and the occurrence of Auspendelschwingungen in the speed signal, the first clutch 21 is operated regulated such that via the first clutch 21, a Ausstoßelschwingungen counteracting torque is transmitted to the drive shaft 16 of the internal combustion engine 12. At the same time, the braking torque of the electric machine 13 is reduced in accordance with the torque transmitted to the output shaft 15 via the first clutch 21.

If a straight gear 2, 4 or 6 is inserted for internal combustion engine driving, the second clutch 22 is closed, so that the drive shaft 16 of the internal combustion engine 12 via the second clutch 22, the second input shaft 19 and the gear engaged with the output shaft 15 and electric machine 13 is coupled. The electrical 13 is operated as a generator. The first clutch 21 is open, so that an odd gear can be preselected on the first partial transmission.

For recovering stored in the motor vehicle kinetic energy in the

Pushing operation, the second clutch 22 is opened and the internal combustion engine 12 is turned off. While the electric machine 13 is still driven by the output shaft 15 still in motion, a braking torque is applied to the output shaft 15 by generating electrical energy by means of the electric machine 13. The speed signal for the internal combustion engine 12 is detected and the second clutch 22 is controlled such that upon the occurrence of Auspendelschwingungen in the speed signal that via the second clutch 22, a Ausstoßelschwingungen counteracting torque is transmitted to the drive shaft 16 of the internal combustion engine 12. At the same time, the braking torque of the electric machine 13 is reduced in accordance with the transmitted via the second clutch 22 to the output shaft 15 torque.

LIST OF REFERENCE NUMERALS

Automotive powertrain internal combustion engine electric machine dual clutch transmission output shaft drive shaft electric drive device first input shaft second input shaft switching device first clutch second clutch

Claims

claims

1. A method for operating a motor vehicle drive train (11) having as a drive an internal combustion engine (12) whose drive shaft via at least one clutch (21, 22) with an output shaft (15) can be coupled, wherein the motor vehicle drive train (11) with the The output shaft (15) in drive connection standing e- lectric machine (13) which is operable at least as a generator, wherein the output shaft (15) by means of the internal combustion engine (12) is driven, wherein the clutch (21, 22) is opened and the Combustion engine (12) is switched off, wherein the electric machine (13) during the running out of the internal combustion engine (11) by the still moving output shaft (15) driven and by generating electrical energy by means of the electric machine (13) a braking torque on the Output shaft (15) is applied, wherein a speed signal for the internal combustion engine (11) is detected, wherein it is detected whether in The speed signal Auspendelschwingungen are present, wherein the occurrence of Auspendelschwingungen the clutch (21, 22) is controlled such that via the clutch (21, 22) a Ausstoßelschwingungen counteracting torque to the drive shaft (16) of the internal combustion engine (11) is transmitted , and wherein the braking torque of the electric machine (13) is reduced in accordance with the transmitted via the coupling (21, 22) to the drive shaft (16) torque.

2. The method according to claim 1, characterized in that by means of the coupling (21, 22) a torque to the drive shaft (16) of the internal combustion engine (11) is transmitted, which is greater in magnitude than the braking torque of the electric machine (13) directly before applying this torque, and that for compensating the torque transmitted via the clutch (21, 22) to the drive shaft (16), the braking torque of the electric machine (13) is reduced so that the electric machine (13) operates as an electric motor and drives the drive shaft (16).

3. The method of claim 1 or 2, characterized in that the speed signal is compared with a speed limit, and that the controlled closing of the clutch (21, 22) is disabled when the speed signal is greater than the speed limit.

4. The method according to any one of claims 1 to 3, characterized in that the motor vehicle drive train (11) in addition to the first clutch (21) has a second coupling ment (22) that by means of the first clutch (21), the internal combustion engine (11) separated from the output shaft (15) and by means of the second clutch (22), the e- lectric machine (13) with the drive shaft (16) is connected , and that for compensating the Auspendelschwingungen the first clutch (21) is operated regulated.