DE102018209075A1 - Method for controlling a drive train of a motor vehicle - Google Patents

Abstract

Method for controlling a drive train (1) of a motor vehicle (2); wherein the motor vehicle (2) has at least one drive train (1) with at least one first drive unit (3) for driving the motor vehicle (2); wherein, when the motor vehicle (2) is accelerated until a maximum speed (4) of the motor vehicle (2) is reached, the method comprises at least the following steps:
a) determining an acceleration request and
b) accelerating the motor vehicle (2) by a drive power (5), which can be provided by the at least one first drive unit (3), with a first acceleration profile (6) for implementing the acceleration request;
c) regulating an acceleration (7) of the motor vehicle (2) and reducing the drive power (5), so that a second acceleration curve (8) immediately before reaching the maximum speed (4) has lower acceleration values than the first acceleration curve (6).

Description

The invention relates to a method for controlling a drive train of a motor vehicle. The drive train comprises at least a first drive unit for driving the motor vehicle.

It is known a drive train comprising at least one electric machine and an internal combustion engine. The at least one electric machine can be used as an electric motor (conversion of electrical energy into mechanical energy) and as an electrical generator (conversion of mechanical energy into electrical energy). The powertrain can be operated in different modes. In a serial operation, a torque for driving at least one wheel is provided by the at least one electric machine. The internal combustion engine is then coupled to a generator (and decoupled from the at least one wheel) to generate electrical energy. In a parallel operation, torques are generated by the internal combustion engine and the electric machine and transmitted to the at least one wheel (electric machine and internal combustion engine are coupled to the at least one wheel). Internal combustion engine and electric machine are each connected via rigid (ie unchangeable) translations with the at least one wheel.

In the case of motor vehicles, the maximum speeds that can be reached by the motor vehicle can be limited so that further acceleration of the motor vehicle beyond the maximum speed is not possible. Especially with the drive train described, however, there is regularly a powerful design of the drive units, which would allow an acceleration of the motor vehicle to higher speeds than the maximum speed.

The object of the present invention is to improve the control of a drive train. In particular, a method is to be proposed by which a sense of comfort of a user of the motor vehicle can be increased.

To solve these problems, a method with the features according to claim 1 contributes. Advantageous developments are the subject of the dependent claims. The features listed individually in the claims can be combined in a technologically meaningful manner and can be supplemented by explanatory facts from the description and / or details of the figures, with further embodiments of the invention are shown.

1. a) Feststellen einer Beschleunigungsanforderung (z. B. des Nutzers),
2. b) Beschleunigen des Kraftfahrzeuges durch eine von der zumindest einen ersten Antriebseinheit (maximal) bereitstellbaren Antriebsleistung mit einem ersten Beschleunigungsverlauf zur Umsetzung der Beschleunigungsanforderung;
3. c) Regeln der Beschleunigung des Kraftfahrzeuges und Reduzieren der Antriebsleistung (der zumindest einen ersten Antriebseinheit), so dass ein zweiter Beschleunigungsverlauf unmittelbar vor dem Erreichen der Höchstgeschwindigkeit geringere Werte der Beschleunigung aufweist als der erste Beschleunigungsverlauf.

It is proposed a method for controlling a drive train of a motor vehicle. The motor vehicle has at least one drive train with at least one first drive unit for driving the motor vehicle. The method is used when the motor vehicle is accelerated to a maximum speed of the motor vehicle (the maximum speed does not have to be reached). The method comprises at least the following steps:

1. a) determining an acceleration request (eg of the user),
2. b) accelerating the motor vehicle by one of the at least one first drive unit (maximum) providable drive power with a first acceleration curve to implement the acceleration request;
3. c) regulating the acceleration of the motor vehicle and reducing the drive power (the at least one first drive unit), so that a second acceleration course immediately before reaching the maximum speed has lower acceleration values than the first acceleration course.

So far, motor vehicles were operated so that a maximum deliverable drive power for the fastest possible reaching the maximum speed was requested by the drive train. However, a strong withdrawal of the acceleration when reaching the maximum speed by a user of the motor vehicle can be perceived as unpleasant. The present method is particularly aimed at reducing the acceleration already before reaching the maximum speed, so that no abrupt end of the acceleration occurs.

In particular, it is therefore proposed that the (maximum possible) acceleration which can be generated with the at least one drive unit (or only with one drive unit, alternatively with several drive units or with all available drive units) be significantly reduced before reaching the maximum speed. Preferably, the acceleration is to be reduced until reaching the maximum speed in the context of a continuous function (ie without jump).

In step a) an acceleration request z. B. a user (eg., Based on an accelerator pedal position) detected in particular by a control unit of the motor vehicle. The control unit is designed to carry out the method suitable.

In step b) the motor vehicle is accelerated. In this case, the motor vehicle according to a first (predetermined or stored) Accelerated acceleration. The first acceleration curve takes into account (in particular exclusively) the (maximum available) drive power of the at least one drive unit and uses it to implement the acceleration request (in particular completely).

The first acceleration course would accelerate the motor vehicle up to the maximum speed, whereby an "abrupt" change of the acceleration to zero takes place only when the maximum speed is reached.

In particular, in order to avoid such an "abrupt change" of the acceleration, a regulation of the acceleration is proposed according to step c). In this case, a second acceleration curve is set, which has lower acceleration values at least immediately before reaching the maximum speed than the first acceleration curve. The second acceleration curve utilizes (only) a part of the maximum available drive power of the at least one drive unit to implement the acceleration request.

In particular, the second acceleration course takes place in a time window (eg between 1 and 15 seconds, preferably between 1 and 10 seconds) and / or above a minimum speed (between 20 and 1 km / h [km / hour] differential speed to maximum speed) the maximum speed (according to the first acceleration course) is reached.

In particular, the second acceleration curve in the time window and / or from the minimum speed before reaching the maximum speed (according to the first acceleration curve) has lower acceleration values than the first acceleration curve (the accelerations being determined at the same time points in each case). In particular, the acceleration in the second acceleration course is reduced to zero according to a continuous function until the maximum speed is reached.

In particular, a rate of change of the acceleration in the second acceleration course immediately before reaching the maximum speed is at most 0.1 m / s ³ [meters / second ³ ], preferably at most 0.05 m / s ³ . In particular, this rate of change is maintained in the time window and / or from the minimum speed.

In particular, within the time window and / or from a minimum speed in any time interval which is one second, a change of the acceleration of more than 0.1 m / s ³ , preferably of more than 0.05 m / s ^{3 takes place} .

In particular, the regulation of the first acceleration curve according to step b) takes place such that the at least one first drive unit in a first operating condition (eg travel on a track without incline or gradient) to achieve the first acceleration curve, a drive power of at most 98%, preferably of at most 95%, particularly preferably of at most 90%, of a rated power of the at least one first drive unit, so that in a second operating condition (eg driving on a track with gradient) with a drive power of 100% of the nominal power also the first acceleration course is reachable.

In particular, the user of the motor vehicle is therefore to be used under different operating conditions (gradient or gradient of the traveled route, climatic conditions, head wind, air resistance, weight of the motor vehicle, set speed of a cruise control, energy storage state of charge, vehicle mode, eg, eco, sport, comfort, etc.). etc.) a reproducible acceleration behavior can be offered.

In the present case, it is proposed that the drive train should be operated in the region of the maximum speed according to the second acceleration course. It is deliberately avoided to use the maximum retrievable drive power of at least a first drive unit. The power reserve then available can be used to generate the reproducible acceleration behavior.

In particular, it is therefore proposed that a referenced acceleration profile be defined for the motor vehicle. This can z. B. for idealized environmental conditions or operating conditions (no headwind, defined minimum air resistance, fixed weight, straight route without incline / gradient, etc.) are defined and stored in the control unit.

In particular, the (second) acceleration curve of the motor vehicle should be reproducible within predefined limits of the specified operating conditions.

In particular, it should be made possible so that an acceleration course of the motor vehicle and thus a control of the drive train always (or compliance with predefined limits of the specified operating conditions) in particular in a full load request according to the referenced acceleration curve.

In particular, in the case of a lower power requirement (for example because of driving on a route with a gradient), the power curve of the at least a first drive unit can be reduced even more. In the case of a route with a gradient, the power curve is refilled, possibly by connecting additional drive units (or generation of torques by a plurality of drive units, eg parallel operation).

In particular, a power reserve of the drive train can be resolved at any time in order to possibly achieve maximum possible acceleration (eg in the event of an emergency when overtaking, sport mode, etc.).

1. i. Bereitstellung des Drehmoments entweder durch die erste Antriebseinheit oder durch die zweite Antriebseinheit;
2. ii. Bereitstellung des Drehmoments durch die erste Antriebseinheit und durch die zweite Antriebseinheit;
3. iii. Betrieb einer der Antriebseinheiten zur Bereitstellung einer elektrischen Energie für die andere Antriebseinheit und Bereitstellung des Drehmoments durch die andere Antriebseinheit.

In particular, the drive train additionally comprises at least one second drive unit, wherein at least the following operating modes for providing a torque by the drive units and forwarding this torque to at least one wheel of the motor vehicle are possible:

1. i. Providing the torque either by the first drive unit or by the second drive unit;
2. ii. Providing the torque by the first drive unit and by the second drive unit;
3. iii. Operating one of the drive units for providing electrical energy for the other drive unit and providing the torque by the other drive unit.

The operating modes according to i. and iii. include, for. B. a serial operation in which z. For example, an electric machine generates the torque and an internal combustion engine (eg, with a second electrical machine that operates as a generator) is operated only to provide electrical energy. The operating mode according to i. also includes an exclusive operation of an electric machine or an internal combustion engine. In particular, the respective non-operated drive unit is decoupled from the drive train or relative to the wheel (eg via a clutch).

The operating mode according to ii. includes z. B. a parallel operation in which z. B. the torque generated by the internal combustion engine and the electric machine and is transmitted to the at least one wheel.

In particular, one of the drive units is an electric machine (preferably the first drive unit) and the other (preferably the second) drive unit is an internal combustion engine.

In particular, the torque is provided exclusively by an electric machine until a minimum speed of the motor vehicle is reached. In particular, the motor vehicle is optionally operated additionally or exclusively in a serial mode until the minimum speed is reached.

In particular, in step c), the torque is provided exclusively by an electric machine (exclusive operation of the electric machine or serial operation).

In particular, in step c) the torque is provided by an electric machine and an internal combustion engine (parallel operation).

Preferably, the internal combustion engine is operated with a constant drive power and the control of the acceleration is performed by the electric machine (operation of the electric machine as an electric motor or as an electric generator or providing a zero torque).

Alternatively, the internal combustion engine can be operated with a varying drive power and the regulation of the acceleration can be performed at least by the internal combustion engine. In particular, an additional torque may be provided by an electric machine (or a plurality of electric machines).

In particular, the regulation of the acceleration is additionally performed by the electric machine.

In particular, the motor vehicle has a drive train in which a stronger acceleration is possible in serial operation than in a parallel operation. In particular, the serial operation is not more efficient (in terms of energy consumption) than the parallel operation. In the present case, it is therefore proposed, in particular, to switch from serial operation to parallel operation before reaching the maximum speed. This switching improves efficiency in particular. The acceleration capacity then reduced in parallel operation is not decisive in the transition region from the acceleration process to the maximum speed, since no greater power requirement is placed on the drive train or on the drive units in this transition region.

It is further proposed a motor vehicle, at least comprising a drive train with at least a first drive unit for driving the motor vehicle and a control unit, which is designed to control the drive train according to a method according to one of the preceding claims suitable.

Furthermore, the method can also be executed by a computer or with a processor of a control unit.

Accordingly, there is also proposed a data processing system comprising a processor adapted / configured to perform the method or part of the steps of the proposed method.

A computer-readable storage medium may be provided that includes instructions that, when executed by a computer / processor, cause it to perform the method or at least part of the steps of the proposed method.

The statements relating to the method are in particular applicable to the motor vehicle, the system, the storage medium or the computer-implemented method, and vice versa.

By way of precaution, it should be noted that the numerical terms used here ("first", "second",...) Primarily (only) serve to distinguish a plurality of similar objects, variables or processes, ie in particular no dependence and / or order of these objects, quantities or mandate processes to one another. If a dependency and / or order are required, this is explicitly stated here or it obviously results for the person skilled in the art when studying the concretely described embodiment.

• 1: ein Kraftfahrzeug; und
• 2: ein Diagramm.

The invention and the technical environment will be explained in more detail with reference to the accompanying figures. It should be noted that the invention should not be limited by the stated embodiments. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. Show it:

• 1 : a motor vehicle; and
• 2 : a diagram.

1 shows a motor vehicle 2 with a powertrain 1 , a control unit 13 and a plurality of wheels 11 , A first drive unit 3 is an electrical machine. A second drive unit 9 is an internal combustion engine. The internal combustion engine is via a generator 15 and a fixed translation 16 with the wheel 11 coupled (where also a (fixed) translation between the internal combustion engine and generator 15 can be provided). The first drive unit 3 is about another fixed translation 16 with the wheel 11 coupled. The first drive unit 3 and the generator 15 are with a battery 17 connected. It would also be possible to disassemble at least one drive unit (or all drive units) via at least one clutch.

The powertrain 1 is operable in different operating modes. For example, in a serial operation where the electric machine drives the torque 10 generated and an internal combustion engine is operated only to provide electrical energy. Further, an exclusive operation of the electric machine or the internal combustion engine may be provided.

In a parallel operation, the torque 10 generated by the internal combustion engine and the electric machine and on the at least one wheel 11 be transmitted.

2 shows a diagram. On the vertical axis is a speed 18 of the motor vehicle 2 applied. On the horizontal axis is the time 14 applied.

The method is applied when the motor vehicle 2 until reaching a maximum speed 4 of the motor vehicle 2 is accelerated (being the maximum speed 4 does not have to be reached). According to step a), an acceleration request (eg of the user) is detected. According to step b), the motor vehicle 2 through one of the first drive unit 3 maximum deliverable drive power 5 with a first acceleration course 6 accelerated to implement the acceleration request. According to step c), the acceleration 7 (here the slope of the respective course 19 . 20 . 21 . 22 . 23 . 24 . 25 ) of the motor vehicle 2 regulated and the drive power 5 the first drive unit 3 reduced, leaving a second acceleration course 8th just before reaching the top speed 4 lower values of acceleration 7 has as the first acceleration curve 6 ,

The present method is directed to accelerating 7 already before reaching the maximum speed 4 reduce, so no abrupt end to the acceleration 7 occurs.

The first acceleration course 6 would the motor vehicle 2 up to the maximum speed 4 accelerate (if the acceleration request persists), taking effect only when reaching the top speed 4 an "abrupt" change in acceleration 7 to zero. To avoid this usual "abrupt change" of the acceleration 7 becomes in step c) a Regulation of acceleration 7 proposed. This will be a second acceleration curve 8th set, at least immediately before reaching the maximum speed 4 lower values of acceleration 7 has as the first acceleration curve 6 ,

The second acceleration course 8th is in a time window of about 10 seconds or from a minimum speed 12 (here from a differential speed to the maximum speed 4 of about 30 km / h) before reaching the maximum speed 4 (according to the first acceleration curve 6 ).

In the present case, the second acceleration course 8th in the time window and from the minimum speed 12 before reaching the maximum speed 4 (according to the first acceleration curve 6 ) lower values of the acceleration 7 as the first acceleration curve 6 on (with the accelerations 7 be determined at the same time points in each case). The acceleration 7 becomes at the second acceleration course 8th according to a continuous function until reaching the maximum speed 4 reduced to zero.

In the diagram are different gradients 19 . 20 . 21 . 22 . 23 . 24 . 25 the speed 18 shown. The slope of the gradients 19 . 20 . 21 . 22 . 23 . 24 . 25 corresponds to the respective acceleration 7 so that the acceleration curves 6 . 8th can be derived.

Present is until reaching the minimum speed 12 of the motor vehicle 2 the torque 10 provided exclusively by an electric machine.

The first course 19 the speed is determined by the first acceleration curve 6 generated. This is the torque 10 up to the maximum speed 4 provided exclusively by the electric machine.

The courses 20 . 21 . 22 . 23 . 24 the speed 18 be through the respective second acceleration curve 8th generated.

The second course 20 will start at the minimum speed 12 generated by a regulation of the electric machine. In this case, the torque generated by the electric machine 10 increasingly reduced. The regulation of the second acceleration curve 8th via the electric machine.

The third course 21 will start at the minimum speed 12 generated by a parallel operation of the electric machine and an internal combustion engine. Both drive units 3 . 9 can be a torque 10 generate, so that the torques 10 overlap. The regulation of the second acceleration curve 8th via the electric machine.

The fourth course 22 will start at the minimum speed 12 generated by a parallel operation of the electric machine and an internal combustion engine. Both drive units 3 . 9 can be a torque 10 produce. In this case, by the electric machine, the torque 10 the internal combustion engine, if necessary, only reduced.

The regulation of the second acceleration curve 8th via the electric machine.

The fifth course 23 (almost parallel to the fourth course 22 ) is from the minimum speed 12 generated by a parallel operation of the electric machine and an internal combustion engine. Both drive units 3 . 9 can be a torque 10 produce. In this case, by the electric machine, the torque 10 the internal combustion engine, if necessary, only reduced. From a certain speed 18 The electric machine is decoupled, so that on the wheels 11 transmitted torque 10 only generated by the internal combustion engine. The regulation of the second acceleration curve 8th via the electric machine.

The sixth course 24 will start at the minimum speed 12 generated by a parallel operation of the electric machine and an internal combustion engine. Both drive units 3 . 9 can be a torque 10 produce. In this case, the electric machine, the torque 10 continue to increase the internal combustion engine. From a certain speed 18 the internal combustion engine is stopped.

The seventh course 25 shows an acceleration curve in which a higher acceleration 7 as in the first acceleration curve 6 is present. This seventh course 25 will start at the minimum speed 12 generated by a parallel operation of the electric machine and an internal combustion engine. Both drive units 3 . 9 can each with a maximum drive power 5 be operated and so each maximum torque 10 produce.

LIST OF REFERENCE NUMBERS

1

powertrain

2

motor vehicle

3

first drive unit

4

top speed

5

drive power

6

first acceleration course

7

acceleration

8th

second acceleration curve

9

second drive unit

10

torque

11

wheel

12

minimum speed

13

control unit

14

Time

15

generator

16

translation

17

battery

18

speed

19

first course

20

second course

21

third course

22

fourth course

23

fifth course

24

sixth course

25

seventh course

Claims (12)

Method for controlling a drive train (1) of a motor vehicle (2); wherein the motor vehicle (2) has at least one drive train (1) with at least one first drive unit (3) for driving the motor vehicle (2); wherein, when the motor vehicle (2) is accelerated until a maximum speed (4) of the motor vehicle (2) is reached, the method comprises at least the following steps: a) determining an acceleration request, b) accelerating the motor vehicle (2) by a drive power (5), which can be provided by the at least one first drive unit (3), with a first acceleration profile (6) for implementing the acceleration request; c) regulating an acceleration (7) of the motor vehicle (2) and reducing the drive power (5), so that a second acceleration curve (8) immediately before reaching the maximum speed (4) has lower acceleration values than the first acceleration curve (6). Method according to Claim 1 wherein a rate of change of the acceleration (7) in the second acceleration course (8) immediately before reaching the maximum speed is at most 0.1 m / s ³ . Method according to one of the preceding claims, wherein the regulation of the first acceleration curve (6) according to step b) takes place such that the at least one first drive unit (3) at a first operating condition to achieve the first acceleration curve (6) has a drive power (5) of at most 98% of a rated power of the at least one first drive unit (3) provides; so that in a second operating condition with a drive power (5) of 100% of the rated power also the first acceleration curve (6) can be reached. Method according to one of the preceding claims, wherein the drive train (1) additionally comprises at least one second drive unit (9), wherein at least the following operating modes for providing a torque (10) by the drive units (3, 9) and forwarding of this torque (10) at least one wheel (11) of the motor vehicle (2) are possible: i. Providing the torque (10) either by the first drive unit (3) or by the second drive unit (9); ii. Providing the torque (10) through the first drive unit (3) and through the second drive unit (9); iii. Operating one of the drive units (3, 9) for providing an electrical energy for the other drive unit (9, 3) and providing the torque (10) by the other drive unit (9, 3). Method according to Claim 4 wherein one of the drive units (3, 9) is an electric machine and the other drive unit (9, 3) is an internal combustion engine. Method according to one of the preceding Claims 4 and 5 , wherein until reaching a minimum speed (12) of the motor vehicle (2), the torque (10) is provided exclusively by an electric machine. Method according to one of the preceding Claims 4 to 6 , wherein in step c) the torque (10) is provided exclusively by an electric machine. Method according to one of the preceding Claims 4 to 6 , wherein in step c) the torque (10) is provided by an electric machine and an internal combustion engine. Method according to Claim 8 , wherein the internal combustion engine with a constant drive power (5) operated and the control of Acceleration (7) is performed by the electric machine. Method according to Claim 8 in which the internal combustion engine is operated with a varying drive power (5) and the regulation of the acceleration (7) is performed at least by the internal combustion engine. Method according to Claim 10 , wherein the regulation of the acceleration (7) is additionally performed by the electric machine. Motor vehicle (2), at least comprising a drive train (1) with at least one first drive unit (3) for driving the motor vehicle (2) and a control unit (13) for controlling the drive train (1) according to a method according to one of the preceding claims is carried out suitably.

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