DE102006003724A1 - Method for controlling a vehicle drive string comprises synchronizing the revolution difference using an electric machine whilst producing a torque acting positively in the rotary direction of the camshaft of the engine - Google Patents

Abstract

Method for controlling a vehicle drive string comprises synchronizing the revolution difference using an electric machine whilst producing a torque acting positively in the rotary direction of the camshaft of the engine and the input shaft of a gearing system. Preferred Features: The torque of the engine is controlled as a function of vehicle- and operation-dependent parameters. The revolution of the engine is controlled by the selection of a theoretical revolution depending on the revolution difference. The theoretical revolution is adjusted via the torque of the electric machine.

Description

The The invention relates to a method for controlling a motor vehicle drive train, an internal combustion engine, an electric machine and a transmission that covers over a summation gear with two input elements and one output element as well as over a trained as a friction clutch lock-up clutch with each other are coupled by the first input element with the crankshaft of the internal combustion engine, the second input element with the rotor the electric machine, and the output element with the input shaft the transmission is rotatably connected, and wherein the lock-up clutch is arranged between two elements of the summation, wherein an occurred with open lock-up clutch Speed difference between the input shaft of the transmission and the Internal combustion engine is synchronized and then the lock-up clutch is closed.

A drive train of a motor vehicle of the aforementioned type is from the DE 199 34 696 A1 and the DE 101 52 471 A1 known in itself. In this drive train, the summation gear is in each case designed as a simple planetary gear with a sun gear, a planet carrier with several planetary gears and a ring gear. The ring gear forms the first input element and is non-rotatably connected to the crankshaft of the internal combustion engine. The sun gear forms the second input element and is non-rotatably coupled to the rotor of the electric machine. The planet carrier forms the output element and is non-rotatably connected to the input shaft of the gearbox. The lockup clutch is arranged in terms of drive technology between the sun gear and the planet carrier of the planetary gear.

In the drive train according to the DE 199 34 696 A1 the lock-up clutch is formed in contrast to the presently assumed training as a dog clutch, so that the lock-up clutch can be closed only during synchronous operation of the engine and the input shaft of the gearbox, and thus can only be used to a limited extent. In order to enable a drive of the motor vehicle alone with the electric machine, a directional freewheel between the crankshaft and a housing part is arranged, whereby the crankshaft secured against reverse rotation and thus the drive torque of the electric machine is supported against the housing. In order to enable starting of the internal combustion engine with the electric motor when the vehicle is stationary, a further directional freewheel between the input shaft of the gearbox and a housing part is arranged, whereby the input shaft secured against reverse rotation and thus the drive torque of the electric machine is supported against the housing.

In the drive train according to the DE 101 52 471 A1 the lock-up clutch, as assumed for the present invention, designed as a friction clutch, so that the lock-up clutch can be used even with a speed difference between the input shaft of the gearbox and the engine for transmitting a torque in the slip mode. In order to enable a pulse start of the internal combustion engine by means of the electric motor when the motor vehicle and neutral gearbox, a further friction clutch between the input shaft of the gearbox and a housing part is arranged, whereby the input shaft can be braked after reaching a starting speed of the electric machine for starting the engine.

following is in the description of the invention without limitation of Scope of protection by way of example of a largely identical structure the drive train is assumed, wherein the lock-up clutch as a friction clutch is assumed, in particular as a wet multi-plate clutch, alternatively but can also be designed as a dry clutch. Alternative to the known arrangement, the lock-up clutch also between the ring gear and the sun gear, so between the crankshaft of the Internal combustion engine and the rotor of the electric machine, be arranged.

in the normal driving is the lock-up clutch Completely closed, so that the planetary gear is blocked and rigid circulates. In In this operating state are the speeds and directions of rotation of the internal combustion engine, the electric machine and the input shaft of the gearbox identical. The electric machine is in this Condition mainly as a generator to supply the electrical But can in certain operating situations, especially in acceleration phases of the motor vehicle, temporarily also be operated as a motor.

For gear change within the gearbox, the torque of the engine is almost simultaneously reduced, switched off the electric machine and fully open the lock-up clutch. As a result, the input shaft of the gearbox is decoupled from the engine, so that the loaded load gear designed load-free and the target gear to be engaged can be synchronized and loaded load-free. The switching process inevitably results in a speed difference between the input shaft of the gearbox and the internal combustion engine at a downshift is positive and negative in a upshift. This speed difference is usually compensated after the switching process, that the lock-up clutch is coordinated with the torque build-up of the engine closed controlled. However, this requires a certain period of time and is disadvantageously associated with a relatively high wear on the friction elements of the lockup clutch and with an undesirable heating of the lockup clutch and adjacent components and possibly also the transmission oil.

In front In this background, the present invention has the object underlying to provide a method with which in a powertrain of the type mentioned a synchronization of the speed difference faster and less weary than before feasible is. Such a method should also be usable in drive trains be comparable components, but in other propulsion combination combination contain.

The solution this task is in accordance with the features of the preamble of claim 1 from a method of control a motor vehicle powertrain, the an internal combustion engine, a Electric machine and a transmission that includes a summation gear with two input elements and one output element as well as one formed as a friction clutch lock-up clutch with each other are coupled by the first input element with the crankshaft of the internal combustion engine, the second input element with the rotor the electric machine and the output element with the input shaft of the gearbox is rotatably connected, and by the lock-up clutch is arranged between two elements of the summation gear, one with open lock-up clutch occurred speed difference Δn between the input shaft of the transmission and the internal combustion engine synchronized and then the lock-up clutch is closed.

In In this context, it should be noted that the term "gear" all gear types to understand who have a true neutral position with a zero output speed, so not for example by an internal gear speed summation an output speed generate with the value "zero" The term "gear" therefore fall, for example Manual transmissions, automated manual transmissions, planetary automatic transmissions and stepless transmission.

Of Another is according to the invention provided according to the method, that this speed difference Δn = n_GEn_VM is synchronized by the electric machine by the electric machine with positive speed difference Δn> 0 in the direction of rotation the crankshaft of the internal combustion engine and the input shaft of the Gear effective positive torque M_EM> 0 and negative for negative speed difference Δn <0 the direction of rotation of the crankshaft of the internal combustion engine and the Input shaft of the transmission effective negative torque M_EM <0 is generated.

One in the direction of rotation of the crankshaft of the internal combustion engine and the input shaft effective torque M_EM of the electric machine acts on the gearbox, each reinforced for effective translation between the electric machine and the respective shaft, braking, So speed lowering on the crankshaft of the engine as well as driving, so speed increasing on the input shaft of the transmission. Such a positive torque M_EM> 0 of the electric machine therefore has a synchronizing effect on a negative speed difference (Δn <0), which is typically occurs at an upshift.

Vice versa acts counter to the direction of rotation of the crankshaft of the engine and the input shaft of the transmission effective torque M_EM the Electric machine, respectively reinforced for effective translation between the electric machine and the respective shaft, driving, So speed increasing on the crankshaft of the engine and braking, so drehabsabsenkend on the input shaft of the transmission. Such a negative torque M_EM <0 of the electric machine therefore has a synchronizing effect on a positive speed difference (Δn> 0), which is typically at a downshift occurs.

There the input element of the summing gear connected to the electric machine, in the preferred embodiment the sun gear of the planetary gear, depending on the size of the circuit-related Speed difference Δn temporarily also backwards, so contrary to the direction of rotation of the two shafts, can turn in In this case, a positive torque M_EM> 0 by generating a drag torque in generator mode and a negative torque M_EM <0 by the generation generates a drive torque in the engine operation of the electric machine.

By using the electric machine to synchronize a speed difference .DELTA.n between the input shaft of the transmission and the crankshaft of the internal combustion engine, the lock-up clutch remain open during synchronization, and closed slip and wear upon reaching the synchronous operation of the input shaft and the engine. This will cause unnecessary wear on the friction elements of the lock-up clutch as well prevents heating of the lock-up clutch and adjacent components.

advantageous Embodiments and developments of the method according to the invention are the subject of the dependent claims 2 to 7.

There the internal combustion engine due to a high moment of inertia and a time - delayed influence over the Combustion process is only relatively difficult to control is during the Synchronization of the speed difference .DELTA.n the torque M_VM of the engine expedient as Function controlled by vehicle and operation dependent operating parameters and the speed n_VM of the internal combustion engine by the specification one of the speed difference Δn dependent Target speed n_VM_soll regulated, the target speed n_VM_soll essentially about that Torque M_EM of the electric machine is adjusted. The internal combustion engine thus remains in its operating state at the beginning of the switching process, until the synchronization of the rotational speed difference Δn by means of the electric machine finished and the lock-up clutch closed is.

After that is the internal combustion engine depending on the usual Operational parameters and the power demand of the driver controlled.

The Electric machine must be during the synchronization of the speed difference Δn in addition to the required for this Torque also the instantaneous torque of the internal combustion engine (drive torque or drag torque) and the voltage applied to the input shaft of the transmission Support torque (driving resistance torque) against each other. The Total required torque M_EM_erf of the electric machine can therefore optionally from the for the current driving moment and for the synchronization of the speed difference Δn required torque M_GE_soll on the input shaft of the gearbox by recalculation with the translation i_EM / GE between the electric machine and the input shaft of the transmission, or from the for the current momentum and for the synchronization of the speed difference Δn required torque M_VM_soll on the crankshaft of the internal combustion engine by recalculation with the translation i_EM / VM determined between the electric machine and the internal combustion engine become.

there can, especially at weaker dimensioned electric machine, the determined torque M_EM_soll exceed the maximum torque M_EM_max that can be generated by the electric machine, which is at least a delay sync would result. It is therefore appropriate that in principle checked whether the required torque M_EM_soll is the maximum torque M_EM_max exceeds the electric machine, in which case the required residual torque ΔM_EM_R = M_EM_soll - M_EM_max a partial closing the lockup clutch is applied as clutch torque M_K_soll.

The through the lock-up clutch can be generated torque M_K regardless of their arrangement always true to the sense, that is speed-equalizing, because each faster braked rotating component and accelerates the slower mer rotating component becomes. In this approach, although a certain amount of wear on the Friction elements of the lock-up clutch accepted. However, this wear is much lower as a complete one Synchronization of the speed difference Δn via the lock-up clutch.

Independently of, whether the torque M_EM_max of the electric machine is sufficient or not, the synchronization of the speed difference Δn by the Electric machine thereby supported and be accelerated, that the lock-up clutch during the Sync is partially closed.

As well can the synchronization of the speed difference .DELTA.n by the electric machine be assisted by the internal combustion engine by adjusting the Torque M_VM_soll and / or the predetermined target speed n_VM_soll during the Synchronization increases with positive speed difference Δn> 0 and at negative speed difference Δn <0 are lowered.

to Clarification of the invention, the description is a drawing with exemplary embodiments attached. In this shows

1 1 is a functional diagram of the method for synchronizing a speed difference between an input shaft of a transmission and an internal combustion engine in a drive train,

2 a part of the functional schema according to 1 for determining the torques of an electric machine and a lock-up clutch,

3 a first application example for synchronizing a speed difference in the form of a speed diagram over time,

4 A second application example for synchronizing a speed difference in the form of a speed diagram over time,

5 the general structure of the underlying powertrain in a simplified schematic representation, and

6 a preferred practical embodiment of the drive train according to 5 in a schematic representation.

A powertrain 1 according to 5 includes an internal combustion engine 2 , an electric machine 3 and a gearbox 4 that have a summation gearbox 5 with two input elements 6 . 7 and an output element 8th coupled together. The first input element 6 is with the crankshaft 9 of the internal combustion engine 2 , the second input element 7 with the rotor 10 the electric machine 3 , and the starting element 8th with the input shaft 11 of the transmission 4 each rotatably connected. A trained as a friction clutch lock-up clutch 12 is between two elements of the summation gear 5 , present between the two input elements 6 . 7 arranged. The internal combustion engine 2 , the electric machine 2 and the lock-up clutch 12 stand over sensor and control cables 13 with a control unit 14 in conjunction, about which the components of the powertrain 1 coordinated are controllable.

A preferred practical embodiment of the powertrain 1 is in 6 displayed. In this drive train 1 is the summation gearbox 5 as a simple planetary gear 15 with a sun wheel 16 , a planet carrier 17 with several planet wheels 18 and a ring gear 19 educated. The ring gear 19 forms the first input element 6 and stands over a flywheel 20 and a torsional vibration damper 21 with the crankshaft 9 of the internal combustion engine 2 in connection. The sun wheel 16 forms the second input element 7 and is directly with the rotor 10 the electric machine 3 rotationally coupled. The planet carrier 17 forms the starting element 8th and is directly connected to the input shaft 11 the here designed as an automated manual transmission 4 in connection.

One between the input shaft 11 and a housing part 22 arranged directional freewheel 23 serves to support the input shaft 11 at a start of the internal combustion engine 2 through the electric machine 3 , The manual transmission 4 is executed in Vorgelegebau way and has a total of six forward gears and one reverse gear, which are selectively switchable via a respective claw clutch. The lockup clutch 12 is between the rotor 10 the electric machine 3 and a connection shaft 24 arranged by which the internal combustion engine 2 with the ring gear 19 communicates.

In such a drive train 1 occurs when the lock-up clutch is open 12 by a switching operation within the gearbox 4 and at a starting process, a speed difference between the input shaft 11 of the gearbox 4 and the internal combustion engine 2 or the crankshaft 9 on, according to the invention by means of the electric machine 3 is balanced before the lock-up clutch 12 is completely closed.

For this purpose, according to the functional scheme of 1 provided that the torque M_VM or M_VM_soll of the internal combustion engine 2 essentially as a function of vehicle and operating-dependent operating parameters, such as the driving speed v, the engaged gear G, and the accelerator pedal position x_Fp, from a setpoint generator 14.1 is controlled or predetermined, whereas the speed n_VM of the internal combustion engine 2 by specifying one of the speed difference Δn = n_GEn_VM between the input shaft 11 of the gearbox 4 and the crankshaft 9 of the internal combustion engine 2 dependent setpoint speed n_VM_soll via a controller 14.2 is regulated. In this case, the setpoint speed n_VM_soll is substantially higher than that of the electric machine 3 generated torque M_EM set and thus the speed difference Δn synchronized.

As in 2 is shown in more detail, this is done by the controller 14.2 of the control unit 14 one on the input shaft 11 of the transmission 4 Required torque M_GE_soll determined and specified by the electric machine 3 should be applied to allow the current driving maneuver and in addition the synchronization of the speed difference .DELTA.n. The required torque M_EM_soll of the electric machine results from the required torque M_GE_soll on the input shaft 11 by recalculation with the translation i_EM / GE between the electric machine 3 and the input shaft 11 ,

In the preferred embodiment of the powertrain 1 according to 6 M_EM_soll = M_GE_soll / (1 - i ₀ ), with stand translation i ₀ . With a typical stand translation of i ₀ = -3, this means that M_EM_soll is a quarter of M_GE_soll.

The required torque M_EM_soll is determined by means of an associated inverter 25 at the electric machine 3 set, if this is not the maximum possible torque M_EM_max the electric machine 3 exceeds. By recalculation of the actual torque M_EM_ist on the input shaft 11 and subtraction with the predetermined target torque M_GE_soll is a possible residual torque .DELTA.M_GE_R determined by a partial closing of the lock-up clutch 12 should be applied as clutch torque M_K_soll.

In 3 such a synchronization is shown for a push downshift. Currently Point t0 is the target gear engaged, creating a positive speed difference Δn = n_GE - n_VM> 0 between the input shaft 11 of the transmission 4 and the internal combustion engine 2 is present. By the subsequent generation of a counter to the direction of rotation of the input shaft 11 and the crankshaft 9 of the internal combustion engine 2 effective torque M_EM becomes the input shaft 11 delayed and decelerated the relevant motor vehicle so while the internal combustion engine 2 Relieves and thus the crankshaft 9 accelerates until at time t1 synchronism between the two waves 9 . 11 and thus also at the lock-up clutch 12 is reached. Therefore, the lock-up clutch 12 be closed slip-free and wear-free at time t1. Subsequently, the further overrun with completely closed lock-up clutch 12 about the control of the internal combustion engine 2 ,

In 4 Similarly, a synchronization for a pull up circuit is shown. At time t0, the target gear is engaged, whereby a negative speed difference Δn = n_GE - n_VM <0 between the input shaft 11 of the transmission 4 and the internal combustion engine 2 was caused. By the subsequent generation of one in the direction of rotation of the input shaft 11 and the crankshaft 9 of the internal combustion engine 2 effective torque M_EM becomes the input shaft 11 and thus also accelerates the relevant motor vehicle, and at the same time the internal combustion engine 2 loaded and thus the crankshaft 9 braked.

Due to the simultaneously increasing torque M_VM of the internal combustion engine 2 the speed n_VM of the internal combustion engine increases 2 nevertheless slightly, but becomes at the time t1 of the higher rising speed n_GE of the input shaft 9 of the transmission 4 caught up, so that due to the achieved synchronism between the two waves 9 . 11 the lock-up clutch 12 can be closed slip-free and wear-free. Subsequently, the further acceleration of the motor vehicle with completely closed lock-up clutch 12 about the control of the internal combustion engine 2 ,

Regardless of those in the 5 and 6 In the embodiments shown, the invention also covers drive trains with all other possible and different drive couplings between the internal combustion engine 2 , the electric machine 3 , the summation gearbox 5 , the clutch 12 and the transmission 4 , which is not shown here separately.

1

powertrain

2

internal combustion engine

3

electric machine

4

Transmission, Manual transmission, automated manual transmission

5

summing

6

(First) input element

7

(Second) input element

8th

output element

9

crankshaft

10

rotor

11

input shaft

12

lock-up clutch

13

Sensor- and control line

14

control unit

14.1

Setpoint generator

14.2

regulator

15

planetary gear

16

sun

17

planet carrier

18

planet

19

ring gear

20

flywheel

21

torsional vibration dampers

22

housing part

23

Direction freewheel

24

connecting shaft

25

inverter

G

corridor

i

translation

i ₀

stand translation of the planetary gear

i_EM / GE

Translation between 3 and 11

i_EM / VM

Translation between 3 and 2

M

torque

M_EM

Torque of 3

M_EM_ist

Actual moment of 3

M_EM_max

Maximum moment of 3

M_EM_soll

Nominal torque of 3

M_GE

Torque of 11

M_GE_soll

Nominal torque of 11

M_K

Torque of 12

M_K_soll

Nominal torque of 12

M_VM

Torque of 2

M_VM_soll

Nominal torque of 2

n

rotation speed

n_GE

Speed of 11

n_VM

Speed of 2

n_VM_ist

Actual speed of 2

n_VM_soll

Nominal speed of 2

t

Time

t0

time

t1

time

v

driving speed

x_Fp

Accelerator pedal position

ΔM_EM_R

Residual moment of 3

ΔM_GE_R

Residual moment of 11

.DELTA.n

Speed difference between 11 and 2

Claims (7)

Method for controlling a motor vehicle drive train, comprising an internal combustion engine ( 2 ), an electric machine ( 3 ) and a transmission ( 4 ), which via a summation gear ( 5 ) with two input elements ( 6 . 7 ) and an output element ( 8th ) and via a lock-up clutch designed as a friction clutch ( 12 ) are coupled together, in which the first input element with the crankshaft ( 9 ) of the internal combustion engine ( 2 ), the second input element with the rotor ( 10 ) of the electric machine ( 3 ) and the starting element ( 8th ) with the input shaft ( 11 ) of the transmission ( 4 ) is rotationally connected, and in which the lock-up clutch ( 12 ) between two elements of the summation gear ( 5 ) is arranged, with an open at lock-up clutch ( 12 ) occurred speed difference (Δn) between the input shaft ( 11 ) of the transmission ( 4 ) and the internal combustion engine ( 2 ) and then the lock-up clutch ( 12 ) is closed, characterized in that this speed difference Δn = n_GE - n_VM means of the electric machine ( 3 ) is synchronized by the electric machine ( 3 ) at negative rotational speed difference (Δn <0) in the direction of rotation of the crankshaft ( 9 ) of the internal combustion engine ( 2 ) and the input shaft ( 11 ) of the transmission ( 4 ) positive positive torque M_EM> 0 or at positive rotational speed difference (Δn> 0) a against the direction of rotation of the crankshaft ( 9 ) of the internal combustion engine ( 2 ) and the input shaft ( 11 ) of the transmission ( 4 ) effective negative torque M_EM <0 is generated. A method according to claim 1, characterized in that the torque (M_VM) of the internal combustion engine ( 2 ) is controlled essentially as a function of vehicle and operating-dependent operating parameters, and that the rotational speed (n_VM) of the internal combustion engine ( 2 ) is controlled by the specification of a speed difference (Δn) dependent setpoint speed (n_VM_soll), wherein the setpoint speed (n_VM_soll) substantially via the torque (M_EM) of the electric machine ( 3 ) is set. Method according to claim 1 or 2, characterized in that the required torque (M_EM_soll) of the electric machine ( 3 ) from the torque (M_GE_setpoint) required for the current drive torque and for the synchronization of the speed difference (Δn) on the input shaft ( 11 ) of the transmission ( 4 ) by recalculation with the translation (i_EM / GE) between the electric machine ( 3 ) and the input shaft ( 11 ) of the transmission ( 4 ) is determined. Method according to claim 1 or 2, characterized in that the required torque (M_EM_soll) of the electric machine ( 3 ) from the torque (M_VM_soll) on the crankshaft (M_VM_soll) required for the current drive torque and for the synchronization of the speed difference (Δn) ( 9 ) of the internal combustion engine ( 2 ) by recalculation with the translation (i_EM / VM) between the electric machine ( 3 ) and the internal combustion engine ( 2 ) is determined. A method according to claim 3 or 4, characterized in that it is checked whether the required torque (M_EM_soll) the maximum torque (M_EM_max) of the electric machine ( 3 ) and, if the result is positive, the required residual torque (ΔM_EM_R = M_EM_setpoint - M_EM_max) is achieved by partially closing the lockup clutch ( 12 ) is generated as a clutch torque (M_K_soll). Method according to at least one of claims 1 to 5, characterized in that the synchronization of the rotational speed difference (Δn) with the electric machine ( 3 ) by means of the lock-up clutch ( 12 ) is supported by the lock-up clutch ( 12 ) is partially closed during synchronization. Method according to at least one of claims 1 to 6, characterized in that the synchronization of the speed difference (Δn) with the electric machine ( 3 ) by means of the internal combustion engine ( 2 ) is supported by the torque to be set (M_VM_soll) and / or the predetermined target speed (n_VM_soll) increased during synchronization at positive speed difference (Δn> 0) and at negative speed difference (Δn <0) are lowered.