DE102014214543A1 - Method for controlling and / or regulating the drive system or driving a motor vehicle - Google Patents

Abstract

The invention relates to methods for controlling and / or regulating the drive system (1, 1a) or the driving of a motor vehicle, in particular a hybrid drive system (1a), a parallel hybrid drive system or a plug-in hybrid drive system of a motor vehicle an electrical operation of the motor vehicle is controlled and / or regulated, wherein a torque (MEmot) from an electric machine (2) to an automatic transmission (3) of the motor vehicle by means of a clutch (4) is transmitted, and wherein for starting the motor vehicle in the electric Operation an electrical creeping operation and / or for starting an electric driving operation by means of the electric machine (2) is realized. Loss of efficiency is avoided by the clutch (4) being controlled and / or regulated in such a way that a reduced - first - clutch slip value, in particular of substantially approximately zero, is set for the electrical creeping operation.

Description

The invention relates to a method for controlling and / or regulating the drive system or driving a motor vehicle, in particular a hybrid drive system, a parallel hybrid drive system or a plug-in hybrid drive system, according to the preamble of claim 1.

In the prior art motor vehicles corresponding hybrid drive systems are known, where in addition to the internal combustion engine additionally an electric drive, in particular an electrical energy storage device is used. In particular, as a function of the energy content of the electrical energy storage and its performance route components, purely electric, so be driven in pure electric driving from the motor vehicle.

In general, the starting of the motor vehicle in the aforementioned hybrid drive system always takes place in electrical operation. This includes in particular starting from standstill or accelerating from low speeds (eg <10 km / h).

In parallel hybrid drive concepts, a clutch, in particular a double clutch, is inserted between the electric motor (electric machine) and the following transmission. At the same time a clutch, in particular a separating clutch is used between the electric motor and the internal combustion engine.

To increase comfort, a so-called "creep function" is often used in drive systems, in particular in hybrid drive systems. This means that even with the unloading of the brake pedal, a low drive torque is built up, so that the motor vehicle is accelerated to a lower speed (eg 7 km / h). This preferred "creep-end speed" is achieved without driving requirement, ie without the driver pressing the accelerator pedal (gas pedal). In the known hybrid drive systems in this case a clutch slip for the arranged between the transmission and the electric motor clutch is set from the outset to the drive in the vibration sensitive starting situations with high gear ratio of the e-machine to the wheel (eg., I = 10 to 20 , in particular i = 15) also decouple. In this case, the tendency of the drive train to oscillate (transmission, differential, propeller shafts) is highly dependent on the torque excitation or the driver's desired torque and the momentum dynamics in the starting situation. Furthermore, a clutch slip is basically also required to maintain a defined coupling capacity (for example, for circuits) and possibly also from an acoustic point of view. The clutch slip is therefore adjusted so that even in critical starting situations with high dynamics a good decoupling effect is given to the wheel to allow a comfortable start. This means that no matter at what speeds, including when starting in the low speed range, where, for example. An electrical creep operation is realized in the known hybrid drive systems, a clutch slip is realized, which also at higher speeds, ie in the normal electric driving accordingly is set. Overall, the clutch slip but causes corresponding loss of efficiency.

If the motor vehicle leaves the "creeping mode" because the driver, for example, actuates the accelerator pedal, then, if the electric driving operation is to be realized, in particular with driving speeds of greater than 7 km / h, then the clutch is also operated accordingly that then the electric driving operation, which in particular connects to the creep, is realized with the clutch including the corresponding clutch slip.

Therefore exist in the prior art corresponding hybrid drive systems in which in electric creep, as well as in particular subsequent electric driving clutch slippage is present, when starting in electrical creep at lower speeds and at higher speeds in electric driving from the outset a certain specific clutch slip is set.

So is, for example, from the DE 10 2007 055 785 A1 a method for controlling a creep system of a vehicle is known, where a clutch is operated with clutch slip to produce a creep mode.

Furthermore, from the DE 10 2008 001 278 A1 a method for operating a drive train of a motor vehicle, in which, when the brake pedal is actuated, the electric motor is operated at a specific speed, so that on the one hand via a hydraulic pump for the transmission required to hold a defined gear pressure and on the other hand for the clutch the drive train, a grinding torque or a creeping torque is provided.

However, the known for hybrid drive systems in the prior art method for starting the motor vehicle in creeping electrical operation or for starting in electric driving are not quite optimally formed, in particular There is loss of efficiency or loss of comfort for the driver.

The invention is therefore the object of the method mentioned, now such and further develop that efficiency losses are reduced and a great comfort for the driver is realized.

The aforementioned object is now solved by the features of claim 1.

According to the method, an electrical operation of the motor vehicle is controlled and / or regulated, wherein a torque is transmitted from the electric machine to an automatic transmission of the motor vehicle by means of a clutch and wherein for starting the motor vehicle an electrical creeping operation and / or for starting an electric driving operation with Help the electric machine is realized.

In this case, the clutch is now controlled and / or regulated so that a (reduced) first clutch slip value is set for the electrical creeping operation, in particular a - first - clutch slip value of approximately zero is set. It is therefore approached in electrical creep now without a significant clutch slip.

But for the electric driving operation a certain - compared to the first clutch slip value - higher second clutch slip value is set, so that then a certain clutch slip is realized for starting in the electric driving.

In particular, therefore, is approached in electrical creeping without a significant clutch slip, vzw. Namely, the first clutch slip value is approximately zero, the latter can be realized in particular in a specific preferred embodiment, that is approached with an over-pressed clutch.

If now in the "creep mode", ie in electric crawl mode, in particular with a clutch slip value of almost zero is approached, the shaping of the torque / speed curve, regardless of driver influence, on the torque source, namely realized here via the electric machine (electric motor) or, in other words, via the controller of the electric motor can ideally - without a clutch slip in electrical creep - then be approached in electrical creep so that it - if at all - only the lowest possible vibration excitations of the drive train. The torque source, the electric motor is controlled accordingly.

If the motor vehicle changes from electrical creep mode to electric drive mode, or if electric driving is directly implemented during startup, because, for example, the driver actuates the accelerator pedal accordingly, then a higher second clutch slip value (as in electric creep mode) is produced for this electric drive mode Clutch set. This has the advantage that, as already explained above, the lowest possible vibration excitation of the drive train can be realized by the control of the electric motor for the electric driving operation, in particular even at higher speeds.

Thus, in electrical creeping operation and / or in electric driving operation with the aid of the control unit, respective specific torque values for the individual phases, ie for the electrical starting in electrical creeping operation and for starting in electric driving operation, can be preset, these values being predetermined and adjusted can be realized that the respectively transmitted by the electric motor to the wheel torque through the set via the control unit clutch force, ie in the end on the (reduced) first clutch slip value of particular approximately zero or a higher second clutch slip value.

In particular, with the aid of a control unit, a specific torque gradient can be selected and, with the aid of this torque gradient, the torque of the electric machine during startup of the motor vehicle can be correspondingly controlled, in particular to reduce or prevent the excitation of jolting sole frequencies of the motor vehicle.

In electric creep operation, therefore, a particular gear-dependent torque gradient can be selected, wherein in particular this torque gradient is optimized accordingly, in particular the dynamic progression of the vehicle longitudinal acceleration can thereby be "smoothed", which may be explained in more detail below.

The electric creeping operation is realized, in particular, when the brake pressure is reduced when the motor vehicle is at a standstill, in particular the brake pedal position is reduced or the brake pedal is released. When the driver presses the accelerator pedal (accelerator pedal), the electric driving operation is realized, with vzw when the accelerator pedal increases. the second clutch slip value continues to increase or increase, namely, depending on the respective operation of the accelerator pedal.

With the method according to the invention, therefore, the electrical operation, in particular the startup of a motor vehicle can be optimized, as usual in such drive concepts, with appropriate operation of the accelerator pedal and an internal combustion engine switched on at the appropriate time and the electric machine can be turned off. Vzw. In this case, an at least partially compensated start of the internal combustion engine is possible.

There are now a variety of ways to design the inventive method in an advantageous manner and further. For this, reference may first be made to the subordinate claims of claim 1 and to the following description and the accompanying drawings. In the drawing shows:

1 a schematic representation of a drive system of a motor vehicle, namely a hybrid drive system,

2 a schematic diagram of a diagram illustrating the electrical operation of a motor vehicle according to the inventive method, and

3 a specific further embodiment of the method according to the invention similar to 2 in a schematic representation, but only with the clarification of the effect of a specific torque gradient for the electric Kriechbetrieb.

1 shows a drive system 1 a motor vehicle not shown in detail here, namely a hybrid drive system 1a , The drive system 1 or hybrid drive system 1a has an electric machine 2 , an automatic transmission 3 , one between the electric machine 2 and the automatic transmission 3 arranged clutch 4 and an internal combustion engine 5 on. Between the combustion engine 5 and the electric machine 2 is a disconnect clutch 6 intended.

Other components of the hybrid drive system 1a are also in 1 represented, namely an energy storage 7 and at least one control unit 8th , here an engine control unit 8a and a transmission control unit 8b ,

The control unit 8th can both units, so the engine control unit 8a and the transmission control unit 8b in one unit. But it is also conceivable two separate control devices, namely an engine control unit 8a and a transmission control unit 8b to provide, as here in 1 shown.

Furthermore, by the dot-dash lines, the transmission channels (CAN-BUS or the like.) For the electrical and / or electronic signal transmission from the control unit 8th or from the engine control unit 8a and from the gearbox control unit 8b be shown to the individual components, as well as a battery management system 9 and a charger 10 out 1 is recognizable. In addition, an electrical / electronic unit 11 for signal transmission and an electrical / electronic unit 12 , here for signal transmission or control of the electric machine 2 intended.

1 therefore shows here a hybrid drive system 1a a motor vehicle not shown with the corresponding components explained above.

With the help of the control unit 8th or the engine control unit 8a and the transmission control unit 8b can now the hybrid drive system 1a or the drive train of the motor vehicle not shown to be controlled and / or regulated.

In this case, the purely electrical operation of the motor vehicle is controlled and / or regulated in the corresponding method according to the invention. A torque in the electric machine 2 gets on the automatic transmission 3 with the help of the coupling 4 transfer. To start the motor vehicle, an electrical creeping operation and / or an electric driving operation with the aid of the electric machine is used in electric operation 2 realized.

The aforementioned disadvantages are now initially avoided by the fact that the clutch 4 is controlled and / or regulated so that a reduced first clutch slip value, in particular of essentially approximately zero, is set for the electrical creeping operation. But for the start in electric driving now a certain - compared to the first clutch slip value - higher second clutch slip value is set.

Here, by the terms (reduced) "first clutch slip value" and "higher second clutch slip value" is meant that the first clutch slip value is reduced compared to the second clutch slip value, ie lower or (conversely) the second clutch slip value is increased compared to the first clutch slip value, ie especially much larger than zero.

As a result, the disadvantages mentioned above can be avoided, in particular the efficiencies of the hybrid drive system 1a are improved or the ride comfort is appropriate elevated. In particular, the electrical creep operation includes vehicle speeds of 0 to 7 km / h.

To clarify the process steps serve the 2 and 3 :

2 shows in the right column, the start of the motor vehicle on the creep KR, so the electrical creeping, and in the left column, the start of the motor vehicle upon actuation of the accelerator pedal, ie the electric driving, so the usual electrical driving mode EF.

In the first line of each 2 and 3 is the speed _curve N _Emot the electric machine 2 and the rotational speed N _Gin the transmission _input shaft of the automatic transmission 3 shown over the time t.

In the second line of each 2 and 3 is the respective torque M _Emot the electric machine 2 shown over the time t.

In the third line of the 2 is the accelerator pedal control FP and in the fourth line of the 2 the brake pedal operation BP shown.

On the other hand, in the third line of the 3 the vehicle longitudinal acceleration v 'and in the fourth line of the 3 brake pedal actuation BP is shown over time t.

The basic procedure may now be based on the 2 be explained in more detail:
In electrical creep operation (cf. 2 right), so if the accelerator pedal and the brake pedal is not actuated (or alternatively, the brake pedal pressure is already reduced, so the brake pedal position is reduced), the electrical Kriechbetrieb is realized. For this purpose, the electric machine delivers over time t 2 a torque M _Emot with a corresponding speed N _Emot , so that the torque M _Emot the electric machine 2 and the speed N _Emot increases accordingly, as in lines 1 and 2 of the 2 shown on the right. Because the clutch 4 is now controlled and / or regulated so that for the electric creep then a reduced first clutch slip value is set, in particular, namely, a first clutch slip value is set by approximately zero, transmits the electric machine 2 the corresponding torque M _Emot essentially completely on the automatic transmission 3 , so that the unspecified output shaft of the electric machine 2 has substantially the same speed N _Emot as the speed N _Gein the input shaft of the automatic transmission 3 , After a certain start-up time in electric creeping _mode, essentially a constant speed N _Emot or N _Gein and a constant torque M _{Emot of} the electric machine then _arise 2 a, as in 2 shown on the right.

If now, for example, because the driver actuates the accelerator pedal, a start of the motor vehicle in electric driving realized, then according to the inventive method now a certain - compared to the first clutch slip value - higher second clutch slip value at the clutch 4 set. This startup should be in 2 be shown in the left column. It can be clearly seen that for this case first the speed N _Emot and the torque M _{Emot of} the electric machine 2 increases accordingly strong, especially because the driver has pressed the accelerator pedal, but now the speed N _Gein the input shaft of the automatic transmission 3 from the speed N _{Emot of} the electric machine 2 deviates, namely due to the higher second clutch slip value of the clutch 4 , After a certain _starting time, on the one hand, the torque M _{Emot reaches} the electric machine 2 a certain constant value and the rotational speeds N _Gin the transmission _input shaft of the automatic transmission 3 and the speed N _{Emot of} the electric machine 2 they are similar to each other, as in the 2 shown in the left column.

2 shows the electrical creep operation without a substantial clutch slip, namely with a first clutch slip value of approximately zero. It is also conceivable that in particular here with an over-pressed coupling 4 is approached.

As the 2 (and also the 3 ) substantially clarify, first, especially at standstill of the vehicle, the driver's request is determined, namely it is determined in particular whether the brake pedal or the accelerator pedal (accelerator pedal) is operated by the driver and / or operated. This will be in the 2 and 3 each in the bottom line for the brake pedal and in the 2 correspondingly represented in the third line for the accelerator pedal ("0" for not actuated, "1" or ">0" for correspondingly actuated).

As the 2 Further shows the electrical creep operation is then realized when at standstill of the motor vehicle, the brake pressure is reduced, in particular the brake pedal is released, that is not actuated. It is also conceivable that in a decreasing brake pedal position, the electrical creeping operation is already initiated and not only when the brake pedal is completely released.

But how the 2 Further, when an accelerator pedal operation is detected, as shown in the third line in FIG 2 on the left, in particular within a defined period of time, the height of the second clutch slip value on the clutch 4 set. Thus, in particular, the electrical creeping operation is ended, if this had previously been realized, and now realized the electric driving, as in 2 shown in the left column.

It is therefore in the electrical operation of the motor vehicle in principle between a start on the specification of a driver's desired torque or a pedal value, in particular for the realization of the electric driving operation upon actuation of the accelerator pedal, or a Ankriechen in electric Kriechbetrieb, especially if the accelerator pedal is not operated, distinguished.

The torque / speed specification of the electric machine 2 sets in electrical Ankriechen, so in electric creep only low torque _values M _Emot and / or low torque _gradients (the latter will be explained below) and the clutch slip or slip speed, so the first clutch slip value is reduced compared to starting operations on the accelerator pedal, that is, set to a first clutch slip value that is, in particular, approximately zero and / or less than the second clutch slip value. Values for slip speeds at the clutch for electric creeping operation are here in particular 150 rpm, 100 rpm, preferably only 50 rpm (or even less, in particular approximately zero).

As the 2 is further clarified, is preferably approached without a clutch slip, so with a first clutch slip value of substantially approximately "zero" in electrical creep operation, especially approached with überpres- sere clutch, in order to achieve the best possible efficiency. When starting in electric creep operation, the torque-determining member is the electric machine 2 , whereas when starting via the accelerator pedal, the torque-determining member, the clutch 4 is.

In the 2 illustrated process steps, electrical Kriechbetrieb (KR) or electric driving or here the usual normal electric driving mode EF can be controlled separately next to each other during the starting process of the motor vehicle or take place, depending on whether the accelerator pedal and / or brake pedal is pressed or not, these respective Anfahrgänge are in the 2 shown. The electrical creeping operation and the electric driving operation can, however, also take place one after the other, that is to say the electric driving operation with corresponding accelerator pedal actuation can be correspondingly connected to the electrical creeping operation. This means that when the accelerator pedal is actuated, the method then sets the higher second clutch slip value (for example, slip speeds of between 50 rpm and 300 rpm at the clutch), so that in particular a decoupling effect is again present and the electric driving mode can be realized and thus at the same time the condition is met that, for example, the connection of the engine in the then slipping operation is conveniently possible.

The preferred further embodiment of the basic in 2 is now shown in 3 represented or should 3 again clarify this process according to the invention. This may now be discussed in more detail:
For creeping electrical operation, can now with the help of the control unit 8th now a certain torque _gradient a _{opt be} selected, with this torque _gradient a _opt the torque M _Emot the electric machine 2 When starting the motor vehicle can be controlled accordingly, in other words, the increase in line 2 of 3 shown graph is controlled accordingly. This serves to reduce or prevent the excitation of Jolteleigenfrequenzen the motor vehicle.

3 Therefore, now shows essentially the same or a similar representation as the right side of the 2 , with the difference, as from line 2 of the 3 It can be seen that a particular gear-dependent torque gradient a or a _{opt are} selected for starting in electrical creep mode, which, like the 3 shows are different, namely a ≠ a _opt . This will, like the 3 in comparison to 2 should clarify, the dynamic course DV of the respective vehicle longitudinal acceleration v '(see row 3 of the 3 ) is influenced, in particular by the application of an optimized torque gradient a _opt the dynamic profile DV is harmonized or smoothed accordingly. For electrical creep operation, the excitation of gear-dependent jerk signal frequencies of the motor vehicle is reduced or prevented when starting with an optimized torque gradient a _{opt is} realized (compare the illustrated difference with respect to the vehicle longitudinal acceleration v 'on the left and right side, in line 3 of the 3 ).

The particular, in particular gear-dependent torque gradient "a _opt " is selected accordingly, in particular taking into account the vehicle type and / or the load / payload and is via the control unit 8th or via the engine control unit 8a or transmission control unit 8b specified accordingly. In particular, under the aforementioned conditions, the optimized gear-dependent torque gradient a _{opt is} selected and with the aid of this torque gradient a _opt Start in electrical creep realized, so that there is a dynamic course DV, which is harmonious or smoothed, as in line 3, right side of 3 shown. As a result, the vibrations of the drive train can be reduced accordingly and thus the starting comfort can be significantly improved.

Well visible in 3 are also the different slopes of the respective straight line or the sizes of the angles which are to represent the torque gradient a and a _opt .

The of the controller or the control unit 8th Maximum set torque _gradient a _opt when starting for creeping electrical operation is, for example, at an unladen mass of the motor vehicle of 1500 kg at values of 100 Nm / s, 50 Nm / s, preferably 20 Nm / s. The starting torque M _{Emot of} the electric machine 2 For the aforementioned vehicle with a multi-speed transmission is generally in a range of 20 to 100 Nm, preferably at about 50 Nm.

As 3 clearly shows, namely in line 3, in the electrical creep operation after a certain time, namely after a start acceleration, the vehicle longitudinal acceleration v 'tends to substantially "0", because the vehicle then reaches the maximum creep speed, whereas it only at the beginning of electric creep operation is accelerated accordingly, as in 3 right. In order to reduce jolt sound frequencies of the vehicle, a specific, in particular optimized, torque gradient a _{opt is} selected for this, which smooths out or harmonizes the resulting dynamic curve DV (compare line 3 of FIGS 3 , left and right side).

Ideally, in the method according to the invention for the electrical creeping operation, a setpoint torque and / or a desired speed profile of the electric machine 2 predetermined, which results in coordination with the natural frequencies of the drive train, a minimum vibration excitation.

Another aspect of the method according to the invention is also that with increasing actuation of the accelerator pedal (accelerator pedal), the second clutch slip value also increases or increases. An increasing slip structure in the clutch 4 with increasing accelerator pedal value is very beneficial. The built with a higher accelerator pedal value higher slip of the clutch 4 allows, in particular at high accelerator pedal values, the implementation of a partially compensated start of the internal combustion engine 5 ie the use of a part of the kinetic / rotational energy of the electric machine 2 to the acceleration of the internal combustion engine 5 to assist without affecting the vehicle longitudinal acceleration v '. The rest of for the acceleration of the internal combustion engine 5 required energy is provided by the electric motor.

In an endsprechendes operation of the accelerator pedal, an internal combustion engine 5 therefore switched on and the electric machine 2 turned off.

LIST OF REFERENCE NUMBERS

1

drive system

1a

Hybrid drive system

2

electric machine

3

automatic transmission

4

clutch

5

internal combustion engine

6

separating clutch

7

energy storage

8th

control unit

8a

Engine control unit

8b

Transmission Control Module

9

Battery Management System

10

charger

11

electrical / electronic unit

12

electrical / electronic unit

a

Drehmomentengradient

a _opt

optimized torque gradient

DV

dynamic course

FP

Accelerator confirmation

BP

Brake pedal operation

KR

Electric creep operation / creep regulator

EF

electric driving / electric driving mode

N _Emot

Speed of the electric machine

N _Gein

Speed of the transmission input shaft

M _Emot

Torque of the electric machine

v '

Vehicle longitudinal acceleration

S

clutch slip

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007055785 A1 [0008]
• DE 102008001278 A1 [0009]

Claims (10)

Method for controlling and / or regulating the drive system ( 1 . 1a ) or the driving of a motor vehicle, in particular a hybrid drive system ( 1a ), a parallel hybrid drive system or a plug-in hybrid drive system of a motor vehicle, wherein an electrical operation of the motor vehicle is controlled and / or regulated, wherein a torque (M _Emot) from an electric machine ( 2 ) on an automatic transmission ( 3 ) of the motor vehicle by means of a coupling ( 4 ) is transmitted, and wherein for starting the motor vehicle in electrical operation, an electrical creeping operation and / or for starting an electric driving operation by means of the electric machine ( 2 ), characterized in that the coupling ( 4 ) is controlled and / or regulated so that a reduced - first - clutch slip value, in particular of substantially approximately zero, is set for the electrical creeping operation. A method according to claim 1, characterized in that but for the electric driving a certain - compared to the first clutch slip value - higher second clutch slip value is set, in particular for the electric driving a certain clutch slip value of substantially greater than zero is realized. A method according to claim 1 or 2, characterized in that is approached in electric Kriechbetrieb without a substantial clutch slip, in particular the first clutch slip value is zero and / or with a überangepresster clutch ( 4 ) is approached. Method according to one of claims 1 to 3, characterized in that first the driver's request is determined at standstill of the motor vehicle, in particular whether the brake pedal or the accelerator pedal is operated by the driver and / or operated. Method according to one of claims 1 to 4, characterized in that the electrical creeping operation is realized when at standstill of the motor vehicle, the brake pressure is reduced, in particular a brake pedal position is reduced or a brake pedal is released or not operated. Method according to one of claims 1 to 5, characterized in that, when an accelerator pedal operation (FP) is determined, then the higher second clutch slip value is set, in particular if necessary, the creeping operation is terminated, and the electric driving operation is realized. Method according to one of Claims 1 to 6, characterized in that a specific torque gradient (a _opt ) is selected in electric creep operation with the aid of a control _device , with this torque _gradient (a _opt ) the torque (M _Emot ) of the electric machine ( 2 ) is appropriately controlled when starting the motor vehicle, in particular to reduce or prevent the excitation of Jückeleigenfrequenzen the motor vehicle. A method according to claim 7, characterized in that in electrical creep operation, a gear-dependent torque gradient (a _opt ) is selected, in particular to reduce the excitation of gear-dependent Jerkeleigenfrequenzen the motor vehicle or prevent. Method according to one of claims 1 to 8, characterized in that with increasing operation of the accelerator pedal and the second clutch slip value continues to increase or increase. Method according to one of claims 1 to 9, characterized in that with appropriate actuation of the accelerator pedal, an internal combustion engine is switched on and the electric machine ( 2 ) is controlled so that in particular an at least partially compensated start of the internal combustion engine is performed.

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