WO2017108652A1

WO2017108652A1 - Method and device for operating a motor vehicle with a hybrid drive

Info

Publication number: WO2017108652A1
Application number: PCT/EP2016/081650
Authority: WO
Inventors: Peter Weiland
Original assignee: Continental Automotive Gmbh
Priority date: 2015-12-21
Filing date: 2016-12-19
Publication date: 2017-06-29
Also published as: DE102015226216A1

Abstract

A method and a device for operating a motor vehicle (2) with a hybrid drive are described, composed of an internal combustion engine (3) and an electric machine (4) which both act on a common hybrid drivetrain (1), and the internal combustion engine (3) is, for the operation of components of an exhaust-gas aftertreatment system (20), operated at least intermittently in a phase with a rich air/fuel mixture or, for the lowering of the exhaust-gas temperature, operated with exhaust-gas recirculation. In the event of an increased load demand 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 (MD_VKM) of the internal combustion engine (3) is held constant, and the additional torque required owing to the increased load demand is imparted by the electric machine (4) alone.

Description

description

Method and device for operating a motor vehicle with a hybrid drive

The invention relates to a method and a device for operating a motor vehicle with a hybrid drive, be ^¬ standing from an internal combustion engine and a Ele- electric machine, both of which act on a common drive train.

When operating an internal combustion engine operation ^¬ species can occur in which both the implementation of the driver other criteria, in particular regarding compliance with the exhaust gas quality and the exhaust gas temperature must be considered. 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. As the recording capacity of such

NOx storage catalyst is limited, it is in a phase in which the internal combustion engine with rich

Air / fuel mixture is operated, regenerated. Here, the internal combustion engine is often operated close to their Be ^¬ 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 impair driving behavior, in ^¬ particular driving comfort. Such problems can also occur when initiating and carrying out the desulphurization of components of the exhaust aftertreatment system or when setting 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 depending on the design of the hybrid powertrain can be arranged in various ways in the motor vehicle. In the context of the invention, the term electric machine is understood to mean both an electric motor and a, in particular integrated, combination of an electric motor with an electric generator, for example in the form of a belt starter generator.

It is known to use such a hybrid powertrain also for influencing exhaust aftertreatment strategies. DE 10 2004 058 231 AI shows a control of an internal combustion engine in a hybrid vehicle, which reduces a torque ^¬ difference, which occurs in connection 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 or recorded

Torque and the absorbable torque of the motor ^¬ Mo generator and estimating the increased torque of the internal combustion engine due to the fact that the air-fuel ratio is set to the rich state judging based on the estimated torque, whether the increased torque is not complete the motor generator can be taken on ^¬ , and performing a control in this case to reduce the torque generated by the internal combustion engine according to the excess when performing the grease 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 a combustion ^¬ machine and an electric machine, both of which act on a ge ^¬ common hybrid powertrain and the internal combustion engine for operating components of an Ab - Gas aftertreatment plant operated at least temporarily in one phase with a rich air / fuel mixture or operated to reduce the exhaust gas temperature with an exhaust gas recirculation. When an increased load requirement for the combustion engine during the phase of operation with a rich air / fuel mixture or in the phase of operation with exhaust gas recirculation, the torque of the combustion ^¬ engine is kept constant and applied due to the increased load requirement additional torque exclusively applied 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 desulphurisation of a NOx storage catalytic converter do not need to be interrupted. Furthermore, the regeneration times can be shortened, resulting in a lower oil dilution and a reduction of the fuel ^¬ demand.

With the inventive method and apparatus are appropriate control of the hybrid powertrain all possible operating conditions of the engine which cause sudden changes in torque due to load ^¬ jumps, particularly reliably overcome. 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:

FIG. 1 shows a schematic view of components of a motor vehicle equipped with a hybrid drive train, and

FIGS. 2A to 2E show time profiles of various parameters when carrying out the method according to the invention. FIG. 1 shows in a highly schematic manner a typical configuration of a hybrid drive train 1 for a motor vehicle 2. The hybrid drive train 1 has an internal combustion engine 3 of conventional design (diesel engine, gasoline engine, gas-powered engine or Flexfuel engine) and an electric machine 4 on. The electric machine 4 can in particular be designed as an integrated Star ^¬ tergenerator.

The hybrid powertrain 1 also has a first clutch 5, which is designed as a positive coupling, for example as a dog clutch. The first clutch 5 is egg ^¬ nerseits with a crankshaft 6 of the internal combustion engine

3 and on the other hand connected to a shaft of the electric machine 4, so that this connection can be closed or disconnected depending on demand. In addition, the hybrid drive train 1 has a second clutch 7, which is likewise designed as a form-locking coupling, for example as a dog clutch. The second clutch 7 is connected on the one hand to a transmission input shaft 8 of a transmission 9 and on the other hand to the shaft of the electric machine 4, so that this connection can be closed or disconnected depending on demand. The transmission 9 is designed for example as an automatic transmission or manual transmission. A transmission output shaft 10 of the transmission 9 is mechanically connected to a differential gear 11 of a drive axle 12 of the motor vehicle 2.

By such an arrangement is a hybrid drive for the motor vehicle 2 with an "in-line" 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 can be driven both by means of the internal combustion engine 3 or the electric machine 4 or by both drive sources.

To control or regulate the electric machine 4, a vehicle electrical system 14 and a hybrid battery 15 is provided. Preferably, the hybrid battery is designed as a 48-volt hybrid battery, but the aspects of the invention are not limited in principle to a nominal voltage of 48 volts ^¬ limits. For example, it is also conceivable that the Nomi ^¬ nalspannung is only 42 volts, or even more than 48 volts. Still further, a forth ^¬ kömmliches 12-volt electrical system is arranged with a 12-volt car battery, are supplied with the various electrical loads in the motor vehicle 2 is preferred.

With the 48-volt vehicle electrical system voltage in comparison with the conventional 12-volt vehicle electrical system voltage a higher performance capability as well as a relatively high torque of the engine 4 elekt ^¬ step can be achieved. Furthermore, due to the increased vehicle electrical system voltage lower electrical losses and higher efficiency, in particular during the start ^¬ process no additional burden of the conventional

12-volt electrical system takes place. 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. About the intake duct 16, the necessary for the combustion of the fuel air is supplied. To a ^¬ position of the air mass flow, a throttle body 18 is provided in the intake duct 16, preferably as an electronic motor controllable throttle valve (E-GAS) is formed and its opening cross-section in addition to the operation of the driver (driver demand) depends on the operating range of the internal combustion engine 3 via signals one that burns 3 engine controlling and regulating electronic

Control device 21 is adjustable. Upstream of the throttle body 18, a load sensor 19 in the form of an air mass meter or a Saugrohrdrucksensors is provided in the intake manifold 16 and each provide a corresponding load signal L. For the aftertreatment of the exhaust gases resulting from the combustion in the cylinders of the internal combustion engine 3, an exhaust aftertreatment system 20 is installed in the exhaust gas tract 17. The exhaust aftertreatment system 20 may in particular contain a NO _x storage catalytic converter and / or a soot particle filter.

Seen in the flow direction of the exhaust gas upstream of the exhaust aftertreatment system 20 treadmill is intended 22 a lambda sensor, which detects a residual oxygen content of the exhaust gas and the measurement signal λ (lambda) is characteristic of the air / fuel ratio in the cylinders of the combustion ^¬ 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 depending on at least one of the operating variables, the actuators, which are associated with the internal combustion engine 3, and each of which corresponding actuators are assigned, by generating actuating signals for the actuators.

The sensors are for example the load sensor 19, the

Lambda probe 22 and a pedal position sensor 23, which detects the position of an accelerator pedal 24. Signals from other sensors that are necessary for controlling and / or regulating the internal combustion engine 3 and its ancillary components, such as temperature sensors for the intake air and for the coolant, a crank angle sensor, etc. are not explicitly shown in FIG. 1, but generally with the reference numeral ES marked. The actuators, which controls the control device 21 by means of actuating signals, are, for example, the throttle element 18, gas inlet and gas outlet valves, fuel injection valves, spark plugs, etc. Such control signals for further actuators of the internal combustion engine 3 and their

Auxiliary units are generally indicated by the reference ES in the figure.

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

The electronic control device 21 may also be referred to as an engine control unit. Such control devices 21, which as a rule include one or more microprocessors, are known per se, so that in the following only the construction relevant in connection with the invention and its mode of operation will be discussed. The control device 21 preferably comprises a computer unit 25 (processor), which is coupled to a program memory 26 and a value memory 27 (data memory). In the program memory and the value memory programs or values are stored, which are necessary for the operation of the internal combustion engine 3. Among other things, a function of controlling the hybrid drive is implemented in software strand 1 in the program memory, as will be explained below with reference to Be ^¬ scription of Figures 2A to 2E. At the time tO a request is made to a specific operation of the internal combustion engine 3. It is in particular measures to influence the exhaust gas of the combustion engine 3 ^¬ in any way. Such a measure, for example, the regeneration phase of a NOx storage catalyst, the burning of a

Soot particulate filter or the opening of an exhaust gas recirculation valve, so that exhaust gas can get into the intake and there can mix with the intake fresh air. In Fig. 2A, such a request is in the form of a

Trigger signal TRIGG that jumps from a logical value of 0 to a logical value of 1 at the time tO. To implement the measures mentioned, the air ratio λ at the time t0 is from a lambda actual value X_IST present at the time t0 in the direction of a predetermined value

Lambda setpoint X_SOLL adjusted. 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 setpoint value X_SOLL <1, the air / fuel mixture is thus enriched. The desired setpoint value X_SOLL is achieved somewhat delayed in time after request at time tO (FIG. 2B).

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

If the internal combustion engine 3 is already operated in the vicinity of its load limit, it can not apply the additionally requested torque, without the regeneration phase initiated at the time t 0 in this case

NOx storage catalyst or the burning of the

Soot particle filter break off again. In order to avoid this, the torque MD_VKM of the internal combustion engine 3 is not increased, but at the time t1 the torque MD_EM of the electric machine 4 is increased until the desired setpoint value for the requested torque is reached at the time t2 (FIG. 2D).

At the time t3, there is no longer any need to influence the exhaust gas of the internal combustion engine 3 by means of additional, special measures, be it because the NOx storage catalytic converter is regenerated or the soot particle filter has burnt free. The trigger signal TRIG therefore jumps from logic 1 to logic 0 at time t3. Since at time t3, no additional torque for embedding ^¬ flussung of the exhaust gas more has to be applied, the electric machine 4 is controlled such that its output to the Hyb- rid-drivetrain 1 torque MD_EM is again reduced to the initial value, which prevailed prior to the load requirement (Time t4 in Fig. 2D).

However, the higher load request due to the driver's request at the time t 1 exists beyond the time t 3 (FIG. 2C). By eliminating the additionally applied torque for influencing the exhaust gas, this increased load can now be applied by the internal combustion engine 3. 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 period t4-t3, FIG. 2D and FIG. 2E).

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

Reference sign list

1 hybrid powertrain

2 motor vehicle

3 internal combustion engine

4 electric machine

5 first clutch

6 crankshaft

7 second clutch

8 transmission input shaft

9 gears

10 transmission output shaft

11 differential gear

12 drive axle

14 onboard electronics

15 hybrid battery

16 intake tract

17 exhaust tract

18 throttle body

19 load sensor

20 exhaust aftertreatment system

21 electronic control device

22 lambda probe

23 Pedal positioner

24 accelerator pedal

AS output signals

ES input signals

L load signal

λ lambda

X_SOLL lambda setpoint

X_IST Lambda actual value

MD_EM torque of the electric machine

MD_VKM torque of the internal combustion engine t time

t0-t6 times TRIG trigger signal

Claims

claims

1. A method for operating a motor vehicle (2) with a hybrid drive, consisting of an internal combustion engine (3) and an electric machine (4), both acting on a ge ^¬ common hybrid powertrain (1) and the internal combustion engine (3) for operating is operated by 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, characterized in that

when an increased load request 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 is applied exclusively by the electric machine (4).

2. The 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 occurrence of load increase and the torque (MD_VKM) of the internal combustion engine (3) is increased, so that the required increase in load can be implemented ,

3. The method according to claim 1 or 2, characterized in that the increased load request by the driver of the motor vehicle (2) is triggered.

4. A device for operating a motor vehicle (2) with a hybrid drive, which is adapted to carry out a method according to one of claims 1 to 3.

5. The device 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.

6. Apparatus according to claim 4, characterized in that the electric machine (4) is designed as a belt starter generator.

7. Device according to one of claims 4 to 6, characterized in that the phase of operation with a rich air / fuel mixture includes a regeneration operation or desulfurization of a NOx storage catalytic converter of Abgasnach ^¬ treatment plant (20).

8. Device according to one of claims 4 to 6, characterized in that the phase of operation with a rich air / fuel mixture includes the burnout of a particulate filter of the exhaust aftertreatment system (20).