DE102015226216A1 - Method and device for operating a motor vehicle with a hybrid drive - Google Patents

Abstract

The invention relates to a method and a device for operating a motor vehicle (2) with a hybrid drive, comprising an internal combustion engine (3) and an electric machine (4), both of which act on a common hybrid drive train (1) and the internal combustion engine (3 ) is operated for operating components of an exhaust aftertreatment system (20) at least temporarily in a phase with a rich air / fuel mixture or operated to reduce the exhaust gas temperature with an exhaust gas recirculation. When an increased load request for the internal combustion engine (3) occurs during the phase of operation with a rich air / fuel mixture or in the phase of operation with exhaust gas recirculation, the torque (MD_VKM) of the internal combustion engine (3) is kept constant due to the increased load requirement required additional torque applied exclusively by the electric machine (4).

Description

The invention relates to a method and a device for operating a motor vehicle with a hybrid drive, consisting of an internal combustion engine and an electric machine, both of which act on a common drive train.

During operation of an internal combustion engine, operating modes can occur in which, in addition to the implementation of the driver's wish, further criteria, in particular with regard to compliance with the exhaust gas quality and the exhaust gas temperature, are to be taken into account. This can lead to unsteady operating states of the internal combustion engine, in particular to fluctuations in the output of the internal combustion engine torque, which is to be avoided in terms of ride comfort.

Exhaust aftertreatment systems modern, at least partially operated with excess air combustion engines have u.a. a NOx storage catalyst (NOx adsorber, NOx trap, NOx trap), which adsorbs the nitrogen oxides in operating phases of the lean-burn gasoline engine. Since the absorption capacity of such a NOx storage catalyst is limited, it is in a phase in which the internal combustion engine is operated with rich air / fuel mixture, regenerated. Here, the internal combustion engine is often operated close to its operating limit. Changes in the operating state of the internal combustion engine, such as load jumps, due to the driver's request, can lead to demolition and thus incomplete regeneration cycles, as well as by changing the torque to affect the driving behavior, especially the ride comfort.

Such problems can also occur in the initiation and execution of the desulfurization of components of the exhaust aftertreatment system or in the setting of an increased exhaust gas recirculation rate for lowering the temperature in the combustion chamber of the internal combustion engine.

Demands on the exhaust gas quality and exhaust gas temperature, which are required to display the aforementioned operating modes of the internal combustion engine, are adjusted by targeted adjustment of the internal combustion engine parameters as a function of the requested engine load.

Future emissions legislation, whose driving cycles have more stringent dynamics and predictability requirements, such as WLTC (Worldwide Harmonized Light Vehicle Test Cycle), Real Driving Emmision (RDE), etc., will further increase the complexity of a robust representation of operating modes with specific exhaust requirements.

Furthermore, hybrid powertrains for motor vehicles are known and are increasingly used to increase the performance of motor vehicles and ride comfort and their efficiency by reducing fuel consumption. In this case, in a hybrid drive, an internal combustion engine and at least one electric machine are combined in such a way that both the type-specific properties of an internal combustion engine and that of an electric machine for driving the vehicle can be utilized. For this purpose, the electric machine can be arranged in various ways in the motor vehicle depending on the configuration of the hybrid drive train. The term electric machine in the context of the invention means both an electric motor and a, in particular integrated combination of an electric motor with an electric generator, e.g. in the form of a belt starter generator.

It is known to use such a hybrid powertrain also for influencing exhaust aftertreatment strategies.

The DE 10 2004 058 231 A1 FIG. 12 shows a control of an internal combustion engine in a hybrid vehicle that reduces a torque difference that occurs in association with a change of a combustion air-fuel ratio to the rich state in a rich control. The method comprises the steps of: estimating the generated torque and the consumable torque of the motor-generator, and estimating the increased torque of the internal combustion engine due to the air-fuel ratio being set to the rich state judging based on estimated torques, whether the increased torque can not be fully absorbed by the motor-generator, and performing a control in this case to reduce the torque generated by the internal combustion engine according to the excess when performing the rich control.

The object of the present invention is to provide a method and a device for operating a motor vehicle with a hybrid output, in which or in which, even when unsteady operating states of the internal combustion engine, the influences on driveability and comfort are minimized.

This object is achieved by the subject matter of the independent claims. Advantageous developments are the subject of the dependent claims.

The invention is characterized by a method and a corresponding device for operating a motor vehicle with a hybrid drive, consisting of an internal combustion engine and an electric machine, both acting on a common hybrid powertrain and the internal combustion engine for operating components of an exhaust aftertreatment system at least temporarily in one Phase operated with a rich air / fuel mixture or operated to reduce the exhaust gas temperature with an exhaust gas recirculation. When an increased load request for the internal combustion engine occurs during the phase of the operation with a rich air / fuel mixture or in the phase of operation with exhaust gas recirculation, the torque of the internal combustion engine is kept constant and the additional torque required due to the increased load requirement applied exclusively by the electric machine.

This results in more stable operating states in the aforementioned operating modes of the internal combustion engine and an increase in the degrees of freedom for achieving exhaust gas setpoints such as setting a desired lambda value or the exhaust gas temperature.

Since the electric machine supplies the required torque when additional load requirements occur, the internal combustion engine does not reach its load limit and measures for operating components of the exhaust gas aftertreatment, such as the regeneration or desulfurization of a NOx storage catalytic converter need not be canceled. Furthermore, the regeneration times can be shortened, resulting in a lower oil dilution and a reduction in fuel consumption.

With the method and the device according to the invention, all possible operating situations of the internal combustion engine, which cause sudden torque changes due to load jumps, are handled particularly reliably by corresponding activation of the hybrid drive train.

The invention will now be explained in more detail with reference to the attached figures, wherein further advantages of the invention will become apparent from the following description of embodiments with reference to the attached figures.

Show it:

1 a schematic view of components of a equipped with a hybrid powertrain motor vehicle and

2A to 2E temporal courses of various parameters in carrying out the method according to the invention

The 1 shows a highly schematic of a typical configuration of a hybrid powertrain 1 for a motor vehicle 2 , The hybrid powertrain 1 has an internal combustion engine 3 conventional design (diesel engine, gasoline engine, gas-powered engine or flex-fuel engine) and an electric machine 4 on. The electric machine 4 can be designed in particular as an integrated starter generator.

The hybrid powertrain 1 also has a first clutch 5 on, which is designed as a positive coupling, for example as a dog clutch. The first clutch 5 is on the one hand with a crankshaft 6 the internal combustion engine 3 and on the other hand with a shaft of the electric machine 4 connected so that this connection can be closed or disconnected depending on demand. In addition, the hybrid powertrain features 1 a second clutch 7 on, which is also designed as a positive coupling, for example as a dog clutch. The second clutch 7 is on the one hand with a transmission input shaft 8th a gearbox 9 and on the other hand with the shaft of the electric machine 4 connected so that this connection can be closed or disconnected depending on demand. The gear 9 is designed for example as an automatic transmission or manual transmission. A transmission output shaft 10 of the transmission 9 is mechanical with a differential gear 11 a drive axle 12 of the motor vehicle 2 connected.

Such an arrangement is a hybrid drive for the motor vehicle 2 with an "inline" arranged electric machine 4 created, ie the internal combustion engine 3 and the electric machine 4 are arranged linearly one behind the other, so that the motor vehicle 2 both by means of the internal combustion engine 3 or the electric machine 4 or can be driven by both drive sources.

For controlling or regulating the electric machine 4 is a vehicle electrical system 14 and a hybrid battery 15 intended. Preferably, the hybrid battery is a 48 volt hybrid battery, but the aspects of the invention are not limited in principle to a nominal voltage of 48 volts. For example, it is also conceivable that the nominal voltage is only 42 volts, or even more than 48 volts. Furthermore, in the motor vehicle 2 preferably still a conventional 12-volt electrical system with a 12-volt vehicle battery arranged, supplied with the various electrical consumers.

With the 48-volt vehicle electrical system voltage in comparison to the conventional 12-volt vehicle electrical system voltage higher performance and a relatively high torque of the electric machine 4 be achieved. Furthermore, the increased vehicle electrical system voltage results in lower electrical losses and higher efficiency, with no additional load on the conventional 12-volt vehicle electrical system, in particular during the starting process. Furthermore, the hybrid drive system is adapted to automatically perform a recuperation of energy, or a change from a normal driving situation to a recuperation mode or vice versa.

The internal combustion engine 3 has an intake tract 16 and an exhaust tract 17 on. About the intake tract 16 is supplied to the combustion of the fuel necessary air. To set the air mass flow is in the intake 16 a throttle body 18 provided, which is preferably designed as an electromotive controllable throttle (E-GAS) and its opening cross-section in addition to the operation of the driver (driver's request) depending on the operating range of the internal combustion engine 3 about signals one, the internal combustion engine 3 controlling and regulating electronic control device 21 is adjustable. Upstream of the throttle body 18 is in the intake tract 16 a load sensor 19 provided in the form of an air mass meter or a Saugrohrdrucksensors and each provide a corresponding load signal L. For aftertreatment due to combustion in the cylinders of the internal combustion engine 3 resulting exhaust gases is in the exhaust system 17 an exhaust aftertreatment system 20 installed. The exhaust aftertreatment system 20 may in particular contain a NO _x storage catalytic converter and / or a soot particle filter.

Viewed in the flow direction of the exhaust gas upstream of the exhaust aftertreatment system 20 is a lambda sensor 22 provided, which detects a residual oxygen content of the exhaust gas and whose measurement signal λ (lambda) is characteristic of the air / fuel ratio in the cylinders of the internal combustion engine 3 ,

The electronic control device 21 Various sensors are assigned to record the measured quantities and determine the measured values of the measured variable. The control device 21 controls the actuators, that of the internal combustion engine depending on at least one of the operating variables 3 are assigned, and each associated with corresponding actuators, by generating actuating signals for the actuators.

The sensors are for example the load sensor 19 , the lambda sensor 22 and a pedal positioner 23 , which indicates the position of an accelerator pedal 24 detected. Signals from other sensors used to control and / or regulating the internal combustion engine 3 and their ancillaries are necessary, such as temperature sensors for the intake air and for the coolant, a crank angle sensor, etc. are in the 1 not explicitly guaranteed, but generally denoted by the reference ES.

The actuators, which the control device 21 by means of actuating signals, for example, the throttle body 18 , Gaseinlass- and gas outlet valves, fuel injection valves, spark plugs, etc. Such control signals for other actuators of the internal combustion engine 3 and their ancillary components are generally indicated by the reference ES in the figure.

The control device 21 is for the exchange of data with the electrical system 14 the electric machine 4 coupled, for example via a CAN bus.

The electronic control device 21 can also be referred to as engine control unit. Such control devices 21 , which usually include one or more microprocessors, are known per se, so that in the following only the relevant in connection with the invention structure and its operation will be discussed.

The control device 21 preferably comprises a computing unit 25 (Processor) using a program memory 26 and a value memory 27 (Data memory) is coupled. In the program memory and the value memory programs or values are stored, which are for the operation of the internal combustion engine 3 are necessary. Among other things, in the program memory software is a function for controlling the hybrid powertrain 1 implements, as follows from the description of the 2A to 2E is explained.

At time t0, a request is made for a specific operation of the internal combustion engine 3 , These are in particular measures to the exhaust gas of the internal combustion engine 3 to influence in any way. Such a measure represents, for example, the regeneration phase of a NOx storage catalytic converter, the burnout of a soot particle filter or the opening of an exhaust gas recirculation valve, so that exhaust gas can enter the intake tract and mix there with the intake fresh air.

In 2A Such a request is represented in the form of a trigger signal TRIGG, which jumps from a logical value 0 to a logical value 1 at the time t0.

To implement the measures mentioned, the air ratio λ is adjusted at time t0 by an actual lambda value λ_IST present up to time t0 in the direction of a predetermined lambda setpoint value λ_SOLL. This is done by means of a conventional, known lambda control device. In the case of a requested regeneration of the NOx storage catalytic converter, the nominal value λ_SOLL <1, the air / fuel mixture is thus enriched. The desired setpoint λ_SOLL is achieved somewhat delayed in time after the request has been reached at the time t0 ( 2 B ).

At the time t1, a load request (increase in the load L) takes place, which is equivalent to a torque request to the drive train of the internal combustion engine 3 because, for example, the driver of the motor vehicle 2 on the accelerator pedal 24 presses ( 2C ).

Will the internal combustion engine 3 already operated in the vicinity of their load limit, they can not apply the additionally requested torque without in this case the regeneration phase initiated at the time t0 for the NOx storage catalytic converter or the burn-off of the soot particle filter again. In order to avoid this, the torque MD_VKM of the internal combustion engine does not become 3 increases, but at time t1 the torque MD_EM the electric machine 4 increases until the desired setpoint for the requested torque is reached at time t2 ( 2D ).

At time t3, there is no longer any need for the exhaust gas of the internal combustion engine 3 be influenced by additional, special measures, either because the NOx storage catalyst regenerated or the soot particle filter is burned. The trigger signal TRIG therefore jumps from logic 1 to logic 0 at time t3.

Since at the time t3 no additional torque for influencing the exhaust gas must be spent more, the electric machine 4 so controlled that its to the hybrid powertrain 1 delivered torque MD_EM is reduced again to the initial value which prevailed before the load request (time t4 in 2D ).

However, the higher load request due to the driver's request at the time t1 exists beyond the time t3 ( 2C ). By eliminating the additional torque to be applied to influence the exhaust gas can now this increased load from the internal combustion engine 3 be applied. The torque MD_VKM of the internal combustion engine is increased to the same extent as the torque MD_EM of the electric machine 4 is reduced (time t4-t3, 2D and 2E ).

At time t5, the increased load requirement drops away again ( 2C ), for example, because the driver takes gas off and therefore the torque MD_VKM is reduced again from this time t5, so that a value is reached which prevailed at the time t1 before the load request (t6, 2E ).

LIST OF REFERENCE NUMBERS

1

Hybrid powertrain

2

motor vehicle

3

Internal combustion engine

4

electric machine

5

first clutch

6

crankshaft

7

second clutch

8th

Transmission input shaft

9

transmission

10

Transmission output shaft

11

differential gear

12

drive axle

14

Bordnetzelekronik

15

hybrid battery

16

intake system

17

exhaust tract

18

throttle member

19

load sensor

20

aftertreatment system

21

electronic control device

22

lambda probe

23

Pedal position sensor

24

accelerator

AS

output signals

IT

input signals

L

load signal

λ

lambda

λ_SOLL

Lambda setpoint

λ_IST

Lambda actual value

MD_EM

Torque of the electric machine

MD_VKM

Torque of the internal combustion engine

t

Time

t0-t6

timings

TRIG

trigger signal

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 102004058231 A1 [0009]

Claims (8)

Method for operating a motor vehicle ( 2 ) with a hybrid drive, consisting of an internal combustion engine ( 3 ) and an electric machine ( 4 ), both on a common hybrid powertrain ( 1 ) and the internal combustion engine ( 3 ) for operating components of an exhaust aftertreatment system ( 20 ) is at least temporarily operated in a phase with a rich air / fuel mixture or operated to reduce the exhaust gas temperature with an exhaust gas recirculation, characterized in that when an increased load requirement for the internal combustion engine ( 3 during the phase of operation with a rich air / fuel mixture or in the phase of operation with exhaust gas recirculation, the torque or in the phase (MD_VKM) of the internal combustion engine ( 3 ) is kept constant and the additional torque required due to the increased load requirement exclusively from the electric machine ( 4 ) is applied. A method according to claim 1, characterized in that at the end of the phase of operation with a rich air / fuel mixture, the additional torque (MD_EM) of the electric machine ( 4 ) is reduced to a value that prevailed before the load increase occurred and the torque (MD_VKM) of the internal combustion engine ( 3 ) is increased, so that the required increase in load can be implemented. A method according to claim 1 or 2, characterized in that the increased load request from the driver of the motor vehicle ( 2 ) is triggered. Device for operating a motor vehicle ( 2 ) with a hybrid drive, which is designed to carry out a method according to one of claims 1 to 3. Apparatus according to claim 4, characterized in that the hybrid drive is designed as a parallel hybrid drive, in which the torques of the two drive sources ( 3 . 4 ) individually or simultaneously on the hybrid powertrain ( 1 ) Are available. Device according to claim 4, characterized in that the electric machine ( 4 ) is designed as a belt starter generator. Device according to one of claims 4 to 6, characterized in that the phase of operation with a rich air / fuel mixture, a regeneration operation or desulfurization of a NOx storage catalyst of the exhaust aftertreatment system ( 20 ). Device according to one of claims 4 to 6, characterized in that the phase of operation with a rich air / fuel mixture, the burnout of a particulate filter of the exhaust aftertreatment system ( 20 ).

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