EP2569195A1

EP2569195A1 - Method for operating a drive train

Info

Publication number: EP2569195A1
Application number: EP11713242A
Authority: EP
Inventors: Johannes Kaltenbach
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2010-05-12
Filing date: 2011-04-04
Publication date: 2013-03-20
Also published as: US20130060411A1; US8825337B2; DE102010028936A1; CN102892656A; CN102892656B; WO2011141233A1

Abstract

A method for operating a drive train having a drive unit comprising at least one electric machine (2) and an internal combustion engine (1), wherein an automated shift transmission is connected between the internal combustion engine (1) and an output (4), wherein the electric machine (2) is coupled via a friction clutch (5) to a shaft of the shift transmission, and wherein shift operations in the shift transmission are carried out, interrupting the drive torque provided by the drive unit on the output (4) in that, firstly, the drive torque provided on the output drive (4) is dissipated, then the actual shift operation is carried out and, following that, drive torque is built up again on the output (4), wherein, in order to carry out the actual shift operation, after disengaging a current gear of the circuit and before engaging a target gear of the circuit, the shaft of the shift transmission (3) to which the electric machine (2) is coupled via the friction clutch (5) is synchronized by utilizing an inertial mass of the electric machine (5).

Description

Method for operating a drive train

The invention relates to a method for operating a drive train of a motor vehicle according to the preamble of claim 1.

The main components of a drive train of a motor vehicle are a drive unit and a transmission. The transmission converts speeds and torques and thus provides a traction power supply of the drive unit at a power take-off of the drive train ready. The present invention relates to a method for operating a drive train of a hybrid vehicle, the drive unit of which comprises at least one electric machine and one internal combustion engine. Between the combustion engine and an output, an automated manual transmission is connected. The electric machine is coupled via a friction clutch to a shaft of the automated manual transmission.

In the automated manual transmission circuits are executed with interruption of the drive unit provided at the output drive, namely such that first in a first phase, the drive torque provided at the output reduced, then executed in a second phase, the actual circuit and subsequently in a third phase on Output drive torque is rebuilt. The execution of the actual circuit or the actual gear change in the automated transmission is divided into several phases, namely in a first sub-phase in which the actual gear of the circuit to be executed is designed in a second sub-phase in which synchronizes a gear shaft of the automated transmission is, and in a third sub-phase in which is inserted after the synchronization of the respective transmission shaft of the target gear of the circuit to be executed or the gear change to be carried out. In practice, the synchronization of the gear shaft to be synchronized takes place via synchronizer rings. In this case, relatively long switching times can occur.

On this basis, the present invention based on the problem to provide a novel method for operating a drive train.

This problem is solved by a method according to claim 1. According to the invention is to execute the actual circuit after a Gangauslegen an actual gear of the circuit and before a Gangeinlegen a target gear of the circuit, the shaft of the automated transmission, to which the electric machine is coupled via the friction clutch, taking advantage of a flywheel of the electric machine synchronized.

With the present invention, it is proposed to use a flywheel torque of the electric machine for synchronizing the gear shaft to be synchronized. After laying out the actual gear and before inserting the target gear of the circuit to be executed, the shaft of the automated gearbox to be synchronized is subjected to a swing synchronization. This makes it possible to dispense with synchronizer rings. In this way, on the one hand, the structure of the automated gearbox can be simplified, on the other hand, a shortening of switching times and traction interruptions can be realized.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. An embodiment of the invention will be described, without being limited thereto, with reference to the drawing. Showing: 1 shows a block diagram of a first drive train to illustrate the method according to the invention;

2 shows a block diagram of a second drive train to illustrate the method according to the invention;

3 shows a block diagram of a third drive train to illustrate the method according to the invention;

Fig. 4 diagrams for further clarification of the method according to the invention.

The present invention relates to a method for operating a drive train of a motor vehicle, namely a hybrid vehicle.

1 shows a first driveline scheme of a hybrid vehicle in which the method according to the invention can be used. Thus, the drive train of Fig. 1 has an internal combustion engine 1, an electric machine 2, an automated transmission 3 and an output 4, wherein the automated transmission 3 is connected between the engine 1 and the output 4. Likewise, the automated transmission 3 is connected between the electric machine 2 and the output 4.

In FIG. 1, both the internal combustion engine 1 and the electric machine 2 of the drive unit engage with a transmission input shaft of the automated transmission 3. According to FIG. 1, the electric machine 2 engages the transmission input shaft of the automated transmission 3 via a friction clutch 5. The internal combustion engine 1 engages the transmission input shaft of the automated transmission 3 via a clutch 6.

Then, when the friction clutch 5 is opened, the electric machine 2 is decoupled from the output 4. Then, when the clutch 6 is opened, the engine 1 is decoupled from the output 4. When the drive train, which is to be operated in the context of the present invention, therefore, the electric machine 2 by opening the friction clutch 5 from the output 4 can be decoupled, even if the internal combustion engine 1 is coupled with the clutch 6 to the output 4. Likewise, with the clutch 6 open, the internal combustion engine 1 can be decoupled from the output 4 and the electric machine 2 can be coupled to the output 4 when the friction clutch 5 is closed.

As already stated, the transmission 3 is an automated manual transmission. In the automated manual transmission 3, shifts or gear changes are performed while interrupting the drive torque provided by the drive unit at the output 4. For this purpose, the procedure in Fig. 4 in three phases so that initially during a first phase between times t1 and t4 applied to the output 4 and provided by the output unit drive torque MAB is reduced, subsequently in a second phase between the times t4 and Ü actual gear change is performed, and then in a third phase between the times t7 and t8 at the output 4 drive torque M _A B is rebuilt.

In the second phase, an actual gear of the circuit to be executed is first designed to execute the actual gear change or the actual circuit, namely in FIG. 4 between the times t4 and t5, wherein subsequently between the times t5 and t6 the shaft of the automated gearbox 3, to which the electric machine 2 is coupled or couplable via the clutch 5, is synchronized by taking advantage of the flywheel of the electric machine 2, then to the momentum synchronization of this shaft of the automated transmission 3 between the times t6 and t7 the target -Gang the circuit to be executed or the gear change to be performed insert. Details relating to this will be described in greater detail below with reference to FIG. 4, wherein FIG. 4 shows a plurality of time curves over time t, namely a time curve of a torque M _V M provided by the internal combustion engine 1, a time curve of one of FIG electrical machine 2 provided torque MEM as well as temporal curves of a speed ΠΕΜ-HS and ΠΕΜ-RS of elec ^¬ cal machine 2 and a speed n _G E-Hs and n _G E-Rs the shaft of the automated transmission 3, to which the electric machine 2 coupled or coupled via the friction clutch 5, both for an upshift HS and for a downshift RS.

In Fig. 4, a case is considered, in which before the time t1 of the drive train is operated in a hybrid drive, according to Fig. 4 in this hybrid drive the engine 1 at the output 4 provides a positive drive torque MVM, whereas the electric machine 2 a negative Drive torque M _E M at the output 4 provides.

At time t1, the execution of the method according to the invention is started, wherein the time t1 is present, for example, when a driver triggers either a circuit or when a switching strategy of the automated transmission 3 detects an impending circuit. An imminent circuit can be recognized by a transmission control device on the control side, for example, by evaluating a driver request, a time gradient of a transmission output rotational speed, and a time gradient of a transmission input rotational speed.

Beginning with the time t1, the drive torque M _E M provided by the electric machine 2 at the output 4 is first of all reduced, specifically as shown in FIG. 2 with appropriate adaptation of the drive torque M _V M- provided by the internal combustion engine 1 at the output 4. Thus, Fig. 4 can be seen that in the embodiment shown between the times t1 and t2, the regenerative torque M _E M of the electric machine 2 is reduced to zero, wherein the provided by the engine 1 drive torque M _V M by the amount of previously effective generator torque M _E M of the electric machine 2 is reduced.

Between the times t1 and t2, between which a load reduction takes place on the electric machine 2 under load transfer by the internal combustion engine 1, simultaneously the friction clutch 5, via which the electric machine 2 to be synchronized to the shaft of the automated transmission 3, namely in the embodiment 1 is coupled to the transmission input shaft, opened, so that at the time t2, this friction clutch 5 is fully open.

Then, when this friction clutch 5 is fully opened, the speed n _E M of the electric machine 2 is subsequently brought to a preparation speed n _V oR starting from the time t2 between the times t2 and t3, wherein only when the speed n _E M was brought to the preparation speed n _V oR, also provided by the engine 1 drive torque M _V M is degraded.

In the exemplary embodiment shown in FIG. 4, the rotational speed n _{EM of} the electric machine 2 reaches the preparation rotational speed n _V oR-Hs or n _V oR-Rs both during execution of the upshift HS and during execution of the downshift RS at the time t3, so that in FIG 4, starting at the time t3, the drive torque n _V M provided by the internal combustion engine 1 at the output 4 is reduced, namely between the times t3 and t4, so that the torque reduction is completely completed at time t4 and no drive torque is applied to the output 4. With the removal of the drive torque M _V M provided by the internal combustion engine 1 at the output 4 is therefore only started at time t3 when the rotational speed Π ΕΜ-HS or ΠΕΜ-RS of the electric machine 2 to the respective preparation speed n _V oR-Hs or n _V oR-Rs, namely lowered at an upshift HS and raised at a downshift RS was. This can be speed-controlled or time-controlled.

Then, when the rotational speed n _{E of} the electric machine 2 is speed-controlled to the preparation rotational speed n _V oR between the times t2 and t3, the rotational speed of the electric machine 2 is determined and compared with a corresponding limit value. Then, when the speed n _E M of the electric machine 2 reaches this limit, which corresponds to the preparation speed, or HS falls below an upshift or overshoot RS in a downshift, can subsequently with the reduction of the provided by the engine 1 at the output 4 drive torque M _V M be started.

Alternatively, it is also possible to bring the speed n _E M of the electric machine 2 between the times t2 and t3 timed to the preparation speed n _V oR. In such a timed raising or lowering of the speed n _E M to the preparation speed n _V oR is proceeded so that a remaining time is continuously calculated or determined until the speed n _{EM of} the electric machine 2 at a downshift RS above the preparation speed n _V oR-Rs lying flywheel speed n _S cHwuNG-Rs reached at an upshift HS below the preparation speed n _V oR-Hs swing speed n _S cHwuNG-Hs reached. In FIG. 4, the rotational speed n _EM reaches the corresponding rotational speed nscHwuNG at time t5, both in the execution of an upshift HS and in the execution of a downshift RS. Subsequent to the time t5, thus subsequent to the achievement of the flywheel speed n _Sc , the moment synchronization of the shaft of the automated manual transmission 3 to be synchronized takes place between the times t5 and t6.

The determined residual time is compared with a limit value, this limit value corresponding to the time duration between the times t3 and t5.

The limit value with which the determined residual time is compared thus corresponds to the time required for load reduction at the internal combustion engine 1 between the times t3 and t4 and for gear shifting the actual gear of the circuit to be executed between the times t4 and t5.

The remaining time, which is determined during the time-controlled raising or lowering of the speed Π _Ε Μ to the preparation speed n _V oR and compared with the limit value, results from the temporal gradient of the speed n _E M of the electric machine 2 and the expected torque curve of the electric machine 2, namely from the maximum of the electric machine 2 can be provided moment. This maximum torque, which can be provided by the electric machine 2 for accelerating the same, depends on the rotational speed Π ΕΜ of the electric machine 2 and on the capacity or state of charge of the electrical energy store interacting with the electric machine 2.

Then, when the electric machine 2 has reached the preparation speed nvoR, which is the case in FIG. 4 at the time t3, the load reduction is subsequently carried out between the times t3 and t4 on the internal combustion engine 1, as already explained, while the clutch 6 is opened so that at time t4, the clutch 6 is fully opened and the engine 1 is decoupled from the output 4. When the clutch 5 is open and the clutch 6 is open, the rotational speed n _E M of the electric machine 2 is subsequently lowered further between the times t4 and t5 during an upshift HS and raised further in the case of a downshift RS, namely in the direction of the downshift. tion RS above the preparation speed n _V oR-Rs or at an upshift HS below the preparation speed n _V oR-Hs lying flywheel speed nsHWUNG-RS bZW. nsHWUNG-HS

Then, when the rotational speed n _{E of} the electric machine 2 has reached the rotational speed n _SH wuNG, which is the case in FIG. 4 at time t5, the friction clutch 5, via which the electric machine 2 is coupled to the automated manual transmission 3, is subsequently ., is closed, in order to perform between the times t5 and t6, the flywheel synchronization of the shaft of the transmission 3 to be synchronized. The friction clutch 5 is closed as quickly as possible.

Due to the inertial mass of the electric machine 2 as well as the inertial mass of the transmission 3 related to the shaft of the automated transmission 3 to be synchronized, between the times t5 and t6 a rotational speed is established which corresponds to the synchronous rotational speed of the target gear of the circuit to be executed.

As already stated, the friction clutch 5 is closed between the times t5 and t6 for the flywheel synchronization, whereby it is possible to apply a moment during the closing of the clutch 5 via the electric machine 2 so as to form the clutch during slip operation of the clutch 5 Synchronous speed to influence. This influencing by application of a torque via the electric machine 2 during the closing of the friction clutch 5 preferably takes place as a function of a measured speed curve of the rotational speed n _E M of the electric machine 2. Then, at time t6, when the flywheel synchronization of the shaft of the automatic transmission 3 to which the electric machine 2 is coupled via the friction clutch 5 is completed, the target gear of the circuit to be executed is engaged between times t6 and t7 Subsequently, starting with the time t7 between the times t7 and t8, a load build-up is carried out on the internal combustion engine 1, namely with simultaneous closing of the clutch 6.

Between the times t6 and t7, that is, when the target gear of the circuit to be executed is engaged, even if, due to the speed curve of a driven side speed of the automated transmission 3, a next circuit is predictable, parallel to the insertion of the new gear on the electrical machine 2 may be reduced any existing moment and the friction clutch 5 are opened again to then bring the electric machine 2 back to a speed corresponding to the required for the sequential circuit speed of rotation.

Then, when the actual gear of the circuit to be executed is designed between the times t5 and t6, the internal combustion engine 1 can be brought to the synchronous speed of the circuit simultaneously with the gear layout.

The flywheel speed n _S cHwNNG, to which the electric machine 2 is brought, is preferably determined by calculation, using the following equation:

n S. CWUNG

where JEM is the mass inertia of the electric machine, where JGE is the transmission input inertia relative to that to be synchronized Shaft of the automated transmission is, where ηβΕ-ιετ the input speed of the synchronized shaft of the automated transmission in the actual gear of the circuit, and wherein n _G E-ziEL is the input speed of the synchronized shaft of the automated transmission in the target gear of the circuit ,

The calculation of the flywheel speed n _S cHwuNG can be improved by additionally taking into account the flywheel energy which is lost in the slip operation of the friction clutch 5, via which the electric machine 2 is coupled or couplable to the shaft of the automated shift transmission 3 to be synchronized.

A further improvement in the determination of the speed of rotation nscHwuNG can be effected by taking into account frictional moments which have a braking effect. With an upshift to be performed, less flywheel energy is needed due to friction than neglected friction. On the other hand, during a downshift, more kinetic energy is needed based on friction than neglected friction.

Furthermore, when determining the rotational speed n _SC HwuNG, a torque that can be supplied electrically by the electric machine 2 can be taken into account, which can be provided by the electric machine 2 for synchronizing the shaft of the automated gearbox 3 to be synchronized, in order to operate in the slip mode of the friction clutch 5 Machine 2 intervention to intervene. In an upshift HS so the swing speed can be raised and lowered in a downshift RS.

According to an advantageous development of the present invention, an adaptation for the rotational speed n _S cHwuNG can take place. Then, if, following the closing of the friction clutch 5, which between the Times t5 and t6 takes place, a synchronous speed for the target gear of the circuit to be executed is not reached, the flywheel speed n _S cHwuNG can be adaptively adjusted in this context, namely such that when the synchronous speed was exceeded, the flywheel speed with a negative Offset value is corrected. On the other hand, if the synchronous speed of the target gear has been undershot, the flywheel speed is corrected with a positive offset value. These offset values depend on the circuit to be executed, in particular depending on the target gear of the circuit to be executed.

In the friction clutch 5, by means of which the electric machine 2 can be coupled to the automated manual transmission 3, it is preferably a friction clutch, which in the normal case, i. in the non-driven case, spring-loaded is closed and can be opened against the spring force of the spring element. In this case, then a rapid closing of the friction clutch 5 is possible, it being sufficient if the friction clutch 5 between two states, namely between an open state and a closed state, can be transferred. It is not necessary that the friction clutch 5 is adjustable.

The method according to the invention can be used not only in the drive train of FIG. 1, but rather also in the drive trains of FIGS. 2 and 3.

2, the electric machine 2 as well as the drive train of FIG. 1 can be coupled to a transmission input shaft of the automated transmission 3 via a friction clutch 5, wherein in Fig. 2 between the friction clutch 5 and the electric machine 2, a constant ratio 10 is switched is. 2, the method can be carried out in an analogous manner, as described above for the drive train of FIG. 1, wherein it is the rotational speed for the drive train of FIG. 2 at the rotational speed n _E M is, which is provided depending on the rotational speed of the electric machine 2 of the constant ratio 10, which thus rests against the drive side of the friction clutch 5.

In addition, the method according to the invention can also be used in an automated manual transmission designed as a group transmission, which, as shown in FIG. 3, comprises a front-mounted group 7, a main transmission 8 and a rear-mounted group 9. In addition to the main transmission 8, a group transmission may also comprise only one upstream group 7 or only one downstream group 9.

In Fig. 3, the electric machine 2 is coupled via a friction clutch 5 to a countershaft of the trained as a group transmission, automated transmission 3, whereas the internal combustion engine 1 is coupled via the clutch 6 to the input shaft of the group transmission 3. In the embodiment of Fig. 3, the electric machine 2 is coupled via the friction clutch 5 to the ballast 7, namely a loose wheel of the ballast 7, which is engaged with a mounted on the countershaft fixed gear and forms a translation stage with the same.

3, the synchronization of the countershaft of the group transmission 3 via the electric machine 2 in an analogous manner as in the embodiment of FIG. 1, in which via the electric machine 2, the transmission input shaft of the automated transmission 3 was synchronized. In the embodiment of FIG. 3, the speed nGE is not the speed of the transmission input shaft, but rather the speed of the countershaft to be synchronized.

In contrast to the embodiment of FIG. 3, it is also possible that the electric machine 2 is coupled in each case via the friction clutch 5 in a loose wheel of the main transmission 8 or directly to the countershaft.

Taking advantage of the invention can be dispensed with group transmissions on an otherwise usually existing transmission brake. There are simultaneous circuits in the main transmission 8 and 7 in the Vorschaltgruppe possible. Even with group transmissions, a required switching time can be shortened.

reference numeral

internal combustion engine

electric machine

transmission

output

clutch

upstream group

main gearbox

downstream group

constant translation

Claims

claims

1 . Method for operating a drive train of a motor vehicle with a drive comprising at least one electric machine and an internal combustion engine, wherein between the internal combustion engine and an output, an automated transmission is connected, wherein the electric machine is coupled via a friction clutch to a shaft of the automated transmission, and wherein in the automated transmission with interruption of the drive unit provided at the output drive torque circuits are designed such that initially reduced in a first phase, the drive torque provided at the output, then executed in a second phase after removal of the drive torque, the actual circuit and subsequently in a third Phase after execution of the actual circuit at the output drive torque is rebuilt, characterized in that to execute the actual circuit after a Gangausl egen an actual gear of the circuit and before a Gangeinlegen a target gear of the circuit, the shaft of the automated transmission, to which the electric machine is coupled via the friction clutch is synchronized by utilizing a flywheel of the electric machine.

2. The method according to claim 1, characterized in that the first of the electric motor provided at the output drive torque is reduced by adjusting the drive torque provided by the engine at the output, that subsequently when the friction clutch, via which the electric machine to be synchronized Is coupled shaft of the automated transmission, is opened, the speed of the electric machine is brought to a preparation speed, and that subsequently also provided by the engine at the output drive torque is reduced.

3. The method according to claim 2, characterized in that the degradation of the combustion engine provided at the output drive torque is only started when the speed of the electric machine was speed controlled to the preparation speed, for which the speed of the electric machine determined and a limit is compared.

4. The method according to claim 2, characterized in that the degradation of the combustion engine provided at the output drive torque is only started when the speed of the electric machine was timed to the preparation speed, including a residual time is determined until the speed of the electric Machine reaches a lying at a downshift above the preparation speed flywheel speed or at an upshift below the preparation speed speed of rotation, the remaining time is compared to a limit.

5. The method according to any one of claims 2 to 4, characterized in that when the torque provided by the engine at the output torque is reduced, the actual gear of the circuit is designed, wherein at the same time as or immediately after the gear layout of the actual Gangs of the circuit, the electric machine is brought to a lying at a downshift above the preparation speed flywheel or at an upshift below the preparation speed speed of rotation, and wherein when the electric machine reaches or exceeds the flywheel speed, the friction clutch, via which the electric machine is coupled to the shaft of the automated gearbox to be synchronized, to synchronize the rotation of the shaft of the automated gearbox to be synchronized.

6. The method according to claim 5, characterized in that simultaneously with or immediately after the Gangauslegen the actual gear of the circuit of the internal combustion engine is brought to a synchronous speed of the target gear.

7. The method according to any one of claims 2 to 6, characterized in that the defined flywheel speed is calculated using the following formula:

n S. CWUNG

where J _E M is the inertia of the electric machine, where J _G E is the transmission input inertia relative to the shaft of the automated transmission to be synchronized, where n _G E is the input speed of the synchronized shaft of the automated transmission in the actual gear of the circuit and where n _G E-ziEL is the input speed of the shaft of the automated transmission to be synchronized in the target gear of the circuit.

8. The method according to claim 7, characterized in that for determining the defined flywheel speed further consideration is a flywheel energy, which is lost during slippage of the friction clutch, via which the electric machine is coupled to the shaft of the automated transmission to be synchronized.

9. The method according to claim 7 or 8, characterized in that further friction moments are taken into account for determining the defined flywheel speed.

1 0. A method according to any one of claims 7 to 9, characterized in that for determining the defined flywheel speed of a further electrically provided by the electric machine for synchronization of the shaft to be synchronized torque is taken into account.

1 1. Method according to one of claims 5 to 10, characterized in that, if, following the closing of the friction clutch, via which the electric machine is coupled to the shaft to be synchronized of the automated transmission, a synchronous speed is not reached, adapting the flywheel speed adaptively is such that when the synchronous speed has been exceeded, a negative offset value is used for the flywheel speed, whereas then, the synchronous speed was exceeded, a positive offset value used for the flywheel speed.

1 2. A method according to any one of claims 1 to 1 1, characterized in that synchronized to be synchronized shaft of the automated transmission, a transmission input shaft, to which also the internal combustion engine is coupled in particular via a coupling.

1 3. A method according to any one of claims 1 to 1 1, characterized in that as synchronizing shaft of the automated transmission, a countershaft of an automated group transmission is synchronized, wherein the internal combustion engine is coupled to a transmission input shaft of the automated group transmission, in particular via a coupling.