DE102018124922A1 - Diesel hybrid drive technology with urea-free NOx conversion - Google Patents

Abstract

The invention relates to a drive technology for vehicles with a diesel hybrid drive. The drive technology comprises a drive device and an operating method. An exhaust gas aftertreatment device (13) for the diesel engine (11) comprises a controllable fuel addition device (17) to add fuel to the exhaust gas (34) in an exhaust gas passage (14) and a catalyst (20) for removing nitrogen oxides (NOx ) from the exhaust gas (34) by reaction with the added fuel. In a high-load operating mode (MODE 1), the power (Pd) of the diesel engine is limited to a continuous operation nominal value (Pr) and fuel is added to the exhaust gas (34) downstream of the diesel engine (1). Furthermore, additional fuel is added to the diesel engine (11) according to a determined required amount (in-engine addition amount). The fuel is added in order to achieve an air-fuel ratio close to the stoichiometric equilibrium (lambda ≈ 1) in the exhaust passage. An excess power (Pex) generated by the in-motor addition quantity is absorbed by the electric motor (12).

Description

The present invention relates to a drive technology for hybrid diesel vehicles, in particular for passenger cars or trucks, which have a diesel engine and an electric motor as drive drives which can be operated in combination.

In practice it is known to equip diesel engines with an exhaust gas aftertreatment device to reduce the nitrogen oxides by adding a separate reducing agent in a catalytic converter for selective catalysis. The reducing agent is usually ammonia, which is formed when injected urea decomposes in the exhaust passage. But it is also possible to add ammonia directly as a reducing agent. The catalyst is usually an SCR catalyst.

On the other hand, it is known to additionally combine a diesel engine with an electric motor to save fuel and combustion emissions in order to create a hybrid drive. With a hybrid drive, a load distribution between the diesel engine and the electric motor is made possible. The electric motor can generate a propulsive power both when electrical energy is drawn from an electrical driving energy storage device and can also take up mechanical power when the driving energy storage device is recuperated (charged), which power can come from the diesel engine and / or from the dynamics of the vehicle.

Diesel engines have significantly higher production costs than other internal combustion engines such as gasoline engines, but offer significantly lower CO2 emissions and have lower fuel consumption. It has been shown that a drive device which combines a diesel engine, an electric motor and a SCR catalytic converter operated with urea or ammonia has such high manufacturing costs that this form of drive is not accepted by the customer.

It is an object of the present invention to show an improved drive technology for a vehicle with a diesel engine and an electric motor, which has, in particular, lower production costs and can comply with the strict emission guidelines for CO2 and nitrogen oxide emissions. The drive technology comprises a drive device and an operating method for the drive device. The invention solves the problem by the characteristics of the independent claims.

The drive device according to the present disclosure can be with a diesel hybrid drive, i.e. with a combination of a diesel engine and an electric motor of the above Kind of be combined. Alternatively, the drive device itself can include the diesel engine and / or the electric motor and any associated control components.

A first aspect of the disclosure is explained below, which alone or in combination with other aspects which are explained below, contributes to the solution of the task.

The drive device according to the present disclosure includes an exhaust gas aftertreatment device for treating the exhaust gas of the diesel engine. The exhaust gas aftertreatment device has an exhaust gas passage, on or in which a controllable fuel addition device and a catalytic converter are arranged along the flow direction of the exhaust gas. The fuel addition device is provided and designed to add fuel to the exhaust gas in the exhaust passage. In particular, this can be the (diesel) fuel that is also used for the operation of the diesel engine. In other words, the exhaust gas aftertreatment device is designed to carry out an after-engine injection.

The catalytic converter of the exhaust gas aftertreatment device according to the present disclosure is provided and designed to remove nitrogen oxides (NOx) from the exhaust gas by converting the nitrogen oxides using the added fuel. In addition, the catalytic converter can be designed to store or adsorb nitrogen oxides.

The exhaust gas aftertreatment device further comprises a control device for controlling the fuel addition.

The fuel is preferably added not only as an after-engine injection but also by an in-engine injection.

Fuel is added to the exhaust gas in such a way that the air-fuel ratio of the exhaust gas and in particular in the region of the catalytic converter is approximated to a target value that is close to the stoichiometric equilibrium. The air-fuel ratio is therefore changed in a region downstream of the combustion chamber in such a way that an excess of oxygen in the exhaust gas is reduced or reduced to zero. A different and significantly higher air-fuel ratio can be present within the combustion chamber, particularly before and during combustion.

The air-fuel ratio is also called the lambda value. For the combustion process in a diesel engine - especially in the high-load operation with a conventional diesel fuel explained below - a lambda value must be provided in the combustion chamber before or during the ignition of the air-fuel mixture, which is clearly above 1, which is, for example, the Has a value of 1.3 or higher. If the lambda value before or during the combustion of conventional diesel fuel is in the range of the stoichiometric equilibrium, i.e. Lambda is equal to 1 or lambda in the range from 1.05 to, for example, 1.1 or 1.15, an unacceptable amount of soot is produced during combustion.

In contrast, in gasoline engines it is possible to provide an air-fuel mixture close to the stoichiometric equilibrium without excessive soot generation, i.e. Lambda is equal to or less than 1.0. That is why it is possible with gasoline engines to carry out an efficient nitrogen oxide reduction with a particularly simple and inexpensive three-way catalytic converter.

In conventional diesel engines, the excess oxygen in the exhaust gas prevents the three-way catalytic converter from being used, because it only works in a narrow lambda value range around lambda equal to 1.0.

In the context of the present invention, a new operating mode is provided for a diesel hybrid drive or for the drive device according to the disclosure, which is referred to as high-load operation.

In high-load operation, the above-mentioned after-engine injection, in which a certain after-engine addition amount of fuel is added to the exhaust gas, changes the air-fuel ratio for the exhaust gas (at least) behind the engine outlet and that approximated stoichiometric balance. This makes it possible to dispense with expensive selective catalysis and the associated urea or ammonia injection.

In addition, it is provided that in high-load operation, a required amount for adding fuel to the diesel engine is determined as an in-engine added amount. In addition to the post-engine addition amount, the in-engine addition amount may at least temporarily be necessary in order to allow the lambda value to approximate the stoichiometric equilibrium. In particular, the precisely controllable fuel injectors, which are generally provided on the diesel engine anyway, allow additional fuel to be added particularly precisely with regard to the injection quantity and with regard to the injection timing. Thus, the in-engine addition quantity, for example, allows the air-fuel ratio in the exhaust gas to be approximated to the target value, while the post-engine addition quantity provides a rough approximation.

The after-engine fuel addition can preferably be controlled by a pilot control, while the in-engine fuel addition can be carried out by a regulation.

The in-motor addition amount can be determined in any manner and by any device or method, preferably by the control device of the drive device and further preferably by a target / actual comparison, i.e. a comparison of the actual air-fuel ratio of the exhaust gas (actual value) with a target value. The actual air-fuel ratio of the exhaust gas is preferably determined in a region downstream of the after-engine fuel addition, in particular by means of a lambda sensor.

The control device of the exhaust gas aftertreatment device preferably also generates an addition control instruction for the diesel engine, so that the in-engine addition amount of fuel is added to or in the diesel engine in high-load operation.

To determine the amount of in-engine added, in particular an actual lambda value or an actual air-fuel ratio in the exhaust gas downstream of the after-engine fuel addition can be measured by a lambda sensor, which is preferably arranged in the vicinity of the catalytic converter is, in particular in the entrance area of the catalytic converter or in the flow direction of the exhaust gas between the fuel addition device and the catalytic converter.

The in-engine addition quantity can be calculated on the basis of a determined (residual) deviation between the target value and the actual air-fuel ratio of the exhaust gas.

The post-engine addition amount is preferably larger and in particular significantly larger than the in-engine addition amount.

The additional fuel that is injected by the in-engine fuel addition can generate excess power that goes beyond the regular power requirement that has been determined, for example, according to the accelerator pedal position of the vehicle or according to another load request. Such excess power from the diesel engine could lead to unexpected driving behavior.

It is known to the person skilled in the art that excessive operation of an engine can be characterized by various parameters, which can be used in particular individually or in combination. It is also known to the person skilled in the art that parameters with different time references can be used to characterize the operation of an engine, i.e. For example, instantaneous parameters, short-term parameters and duration parameters. In the context of the present disclosure, the term “performance” is intended to be the generic term for these various parameters. It therefore encompasses both "mechanical performance" and "mechanical work" or "torque". The term performance is used to represent the various possible parameters. The term "torque" is also used. The person skilled in the art knows the physical phenomena which can occur when a diesel engine and an electric motor are operated in a hybrid system. He knows that the torque of an internal combustion engine depends significantly on the amount of fuel burned, which is why the torque is a particularly frequently used parameter. He is also aware that the same performance can be achieved through different combinations of speed and torque, and that the various possible parameters, which are summarized here under the term "performance", can be used to convert.

In the context of the present disclosure, it is provided that a compensation control instruction for the electric motor is generated so that the excess power resulting from the in-engine addition quantity or the corresponding excess torque of the diesel engine is absorbed by the electric motor. The excess power can be used in particular to charge the driving energy store and / or to operate electrical consumers on the vehicle.

The combination of the fuel additives after the engine and in the engine thus enables a particularly precise adaptation of the air-fuel ratio in the exhaust gas in the region of the catalytic converter, in particular by combining a somewhat coarser pilot control with a fine control.

This means that a catalytic converter that does not need to have selective catalytic properties can also be used for the diesel hybrid drive. In particular, a so-called nitrogen oxide storage catalytic converter (LNT) or (exclusively) a three-way catalytic converter can be used. As an alternative or in addition, it is possible to use a combination of a nitrogen oxide storage catalytic converter (LNT) and a three-way catalytic converter. Again, alternatively or additionally, a catalyst for selective catalysis of nitrogen oxides (SCR) can be used, but this is operated without a urea or ammonia injection. In other words, it is sufficient that the drive device has only one or more catalytic converters which (exclusively) remove nitrogen oxides from the exhaust gas by a reaction with the added fuel. It is therefore not necessary to add a separate reducing agent that is not a fuel.

The drive technology disclosed includes, as a further aspect, which can be used alone or in combination with the aforementioned aspect, an operating method in which the high-load operation is provided as one of different operating modes.

There are particular advantages for efficient and / or low-emission use of the drive technology if the high-load operating mode is selected as a function of a nitrogen oxide conversion efficiency and in particular as a function of an exhaust gas temperature and also as a function of a state of the hybrid system, ie the current availability a drive support by the electric motor or the current possibility of charging the driving energy storage. Other Operating modes can be adjusted so that on the one hand a particularly efficient nitrogen oxide conversion takes place and on the other hand the special advantages of the diesel engine, namely the low CO2 emissions, are used.

The adaptation of the other operating modes has the particular advantage that the high-load operating mode is used only in a very small proportion of the time during driving, for example in less than 3% or less than 1% of the driving time. In this way, the additional consumption of fuel that is generated during the high-load operation by adding fuel to the exhaust gas is reduced to a minimum overall and offset by the advantages of the hybrid drive.

Further advantageous embodiments of the invention are specified in the subclaims.

• 1: eine schematische Darstellung der Antriebsvorrichtung gemäß der vorliegenden Offenbarung;
• 2: ein Schemadiagramm zur Erläuterung der Entstehung von Stickoxidmengen an einem Dieselmotor bei unterschiedlichen Betriebsbedingungen;
• 3: ein Ablaufdiagramm zur Erläuterung verschiedener Aspekte eines Betriebsverfahrens gemäß der vorliegenden Offenbarung.

The invention is illustrated by way of example and schematically in the drawings. These show:

• 1 : A schematic representation of the drive device according to the present disclosure;
• 2nd : a schematic diagram to explain the formation of nitrogen oxide amounts on a diesel engine under different operating conditions;
• 3rd : A flowchart illustrating various aspects of an operating method according to the present disclosure.

1 shows a drive device ( 10th ) in a schematic representation. The drive device ( 10th ) is intended and designed for use on a vehicle (not shown). The vehicle can be powered by a diesel engine ( 11 ) and an electric motor ( 12th ) feature. The diesel engine ( 11 ) is for simplified representation by a combustion chamber ( 27 ) represents. Intake air is drawn from an intake passage ( 24th ) via an inlet valve into the combustion chamber ( 27 ) and burned there with a fuel that is injected through a fuel injector ( 28 ) is injected. The fuel injector ( 28 ) is preferably on or in the combustion chamber ( 27 ) arranged.

The intake air can be controlled by at least one compressor ( 19th ) to be charged. The compressor is in the intake passage upstream of the engine inlet ( 25th ) and downstream to a fresh air inlet ( 26 ) arranged. It is preferably driven directly by a turbine ( 18th ) driven in the exhaust passage ( 14 ) is arranged.

For energy supply to the electric motor ( 12th ) an electrical driving energy storage ( 29 ) be provided.

The diesel engine ( 11 ) and / or the electric motor ( 12th ) and the aforementioned additional components can each be part of the drive device (individually or in any combination) 10th ) according to the present disclosure.

The drive device ( 10th ) includes an exhaust gas aftertreatment device ( 13 ). This has an exhaust passage ( 14 ), which extends from an engine outlet ( 15 ) towards an exhaust ( 16 ) extends and one of the diesel engine ( 11 ) leading exhaust gas. The flow direction of the exhaust gas ( 34 is accordingly from the engine outlet ( 15 ) to the exhaust ( 16 ) directed towards it.

In the direction of flow of the exhaust gas ( 34 ) are on or in the exhaust passage ( 14 ) at least one controllable fuel addition device ( 17th ) and a catalyst ( 20th ) arranged, which have the above training.

An operating method according to the present disclosure provides for operating the aforementioned drive device, wherein the operating method can comprise a plurality of operating modes, including at least one high-load operating mode (MODE 1 ) by following the steps below.

Fuel is in the exhaust ( 34 ) downstream of the diesel engine ( 1 ) and upstream to the catalyst ( 20th ) injected as an after-engine fuel additive to determine the air-fuel ratio of the exhaust gas ( 34 ) in the area of the catalyst ( 20th ) to approach a target value that is close to or equal to the stoichiometric equilibrium, ie lambda is equal to 1. There is a required quantity for an (additional) fuel addition in the diesel engine ( 11 ) determined, which is referred to below as the in-motor addition quantity. The in-motor addition amount may be required to be in addition to the above-mentioned after-motor Additional fuel already added to the diesel engine ( 11 ) and thereby the air-fuel ratio of the exhaust gas ( 34 ) in the area of the catalyst ( 20th ) to approach the aforementioned target value.

According to a preferred embodiment, the post-engine fuel addition amount is significantly larger than the in-engine addition amount. In particular, the substantial or predominant part of an excess of oxygen in the exhaust gas ( 34 ), which during regular operation after combustion in a combustion chamber ( 27 ) of the diesel engine ( 11 ) would exist, thereby compensating for the air-fuel ratio of the exhaust gas ( 34 ) are approximated to the target value. To carry out an after-engine fuel addition, the fuel addition device ( 17th , 17 ' ) operated between the engine outlet ( 15 ) and the catalyst ( 20th ) in at least a simple version, possibly in a multiple version on or in the exhaust passage ( 14 ) is provided. The amount of fuel added to the engine can be selected, for example, by at least 50% and preferably more than 80% of the aforementioned excess of oxygen in the exhaust gas ( 34 ) after regular combustion.

At or in the fuel passage ( 14 ) at least one lambda sensor ( 35 ) be provided. In particular, at least one lambda sensor ( 35 ) between the at least one fuel addition device ( 17th , 17 ' ) and the catalyst ( 20th ) arranged. Via the at least one lambda sensor ( 35 ) the air-fuel ratio of the exhaust gas ( 34 ) in front of or on the catalyst ( 20th ) are recorded. Alternatively or additionally, a current air-fuel ratio of the exhaust gas ( 34 ) in front of or on the catalyst ( 20th ) are determined or obtained in another way, for example by calculation in a combustion model and / or by querying an external control unit, for example a diesel engine control unit (not shown), which may be provided separately.

Based on the determined or related value for the actual air-fuel ratio of the exhaust gas ( 34 ) it can be determined whether there is still a deviation from the target value. If this is the case, a required quantity for an additional fuel addition in the diesel engine ( 11 ) as an in-motor addition quantity.

The in-engine addition quantity is in the diesel engine ( 11 ) added. For this, the control unit ( 23 ) the drive device ( 10th ) generates an additional control instruction. The control unit ( 23 ) can use a fuel injector ( 28 ) of the diesel engine directly or indirectly to carry out an in-engine fuel addition. For this purpose, if necessary, a specification for the type of injection can also be made, which is to be provided on the diesel engine for carrying out the in-engine addition quantity. The specification for the type of injection can, in particular, be part of the additional control instruction issued by the control device ( 23 ) is produced.

A specification for the type of injection can determine that the in-motor addition quantity is either to be added completely as part of a main injection, or on the one hand as part of a main injection and on the other hand as part of a post-injection.

Again, as an alternative, a specification for the type of injection can include that the in-motor addition quantity is to be added entirely as part of a post-injection.

If the amount of in-engine added is at least partially carried out as part of a main injection, more fuel is possibly in the combustion chamber ( 27 ) burned than is necessary for a power request or torque request, so that an excess power output or torque output on the diesel engine ( 11 ) he follows. The excess power or torque ( Pex ) of the diesel engine ( 11 ) according to the present disclosure by the electric motor ( 12th ) recorded by instructing it accordingly by means of a compensation control instruction. For the driver of the vehicle, the total output torque or the total output power thus remains in agreement with the torque request or the output request.

In the following, the term excess engine power ( Pex ) used in such a way that its meaning also includes an excess torque.

The selection of the high-load operating mode (Mode 1 ) can according to the in 3rd shown selection process take place, which can be part of the disclosed operating method.

In a first step ( S10 ) becomes a target performance ( P * ) determined. The target performance ( P * ) is in particular based on an accelerator pedal position of the vehicle and / or on the basis of a specification from one Assistance system determined, the assistance system can be, for example, a cruise control or a distance sequence control or a partially or fully automatic vehicle guidance method. The term target performance ( P * ) also includes a target torque.

In a subsequent step ( S11 ) it is determined whether a temperature ( T_Ex ) of the exhaust gas ( 34 ) an upper threshold ( T2 ) exceeds. If so (step S11 : YES), the output or the output torque ( Pd ) of the diesel engine ( 11 ) to a fixed continuous operation nominal value ( Pr ) limited.

The continuous operation nominal power ( Pr ) depending on a structure and any test values on the diesel engine ( 11 ) be set in such a way that if the diesel engine is operated continuously with this output power ( Pr ) the temperature ( T_Ex ) of the exhaust gas maintains a predetermined temperature level at which there is no damage to the exhaust gas aftertreatment system ( 13 ) are to be expected.

The exhaust gas aftertreatment device ( 13 ) can in particular at least one turbine ( 18th ), in particular have a high-pressure turbine, which further preferably upstream of the catalyst ( 20th ) and downstream to at least one fuel addition device ( 17th ) is arranged.

Thermal damage often occurs first on the turbine blades of such a high-pressure turbine ( 18th ) so that the temperature resistance of the high pressure turbine ( 18th ) as a measure of the permissible temperature level of the exhaust gas ( 34 ) can be used in continuous operation.

2nd explains various operating conditions of a diesel engine ( 11 ) and the nitrogen oxide mass flows and exhaust gas temperatures generated, for example.

Basically, the diesel engine ( 11 ) an exhaust gas ( 34 ) with a higher temperature ( T_Ex ) if the in the combustion chamber ( 27 ) amount of fuel burned ( Qi ) is high and / or if there are many combustion cycles, i.e. if the engine speed ( NE ) is high. However, the temperature of the exhaust gas changes ( T_Ex ) often only with a time delay to a change in the operating condition of the diesel engine ( 11 ). Too much an increase in the exhaust gas temperature can initially lead to a reduction in the conversion efficiency or to a deterioration in the performance of a chemical reduction reaction. A further increase in the exhaust gas temperature can ultimately lead to damage or permanent impairment of the conversion efficiency.

With an increase in the combustion chamber ( 27 ) The amount of fuel burned usually results in a disproportionate increase in nitrogen oxide production, ie a disproportionate increase in the NOx mass flow.

Within the scope of the present disclosure, it is provided that particularly high target outputs ( P * ) are initially covered by the fact that the electric motor ( 12th ) there is electrical drive support (see step S31 in 3rd ). If such electrical drive support is not or no longer possible, for example because the electrical driving energy storage ( 29 ) is exhausted, the target output ( P * ) only by the diesel engine ( 11 ) are generated (step S31 : NO).

If this occurs, which can happen, for example, when the vehicle is going uphill for a longer time, the high-load operating mode (mode 1 ) (Step S42 ) executed. In this case, the diesel engine is operated in such a way that it generates (according to the regular injection control) a maximum of the output power and / or the output torque that corresponds to the specified continuous operation nominal value ( Pr ) corresponds. In addition, the after-engine fuel addition and, if necessary, the in-engine fuel addition are carried out to determine the air-fuel ratio in the exhaust gas ( 34 ) to approach the target value.

The additional addition of fuel to the exhaust gas ( 34 ) upstream to the turbine ( 18th ) exhaust gas cooling is achieved, which can compensate for the temperature rise that is possibly generated by the in-engine fuel addition. On the other hand, the catalyst ( 20th ) convert the nitrogen oxides (NOx) very efficiently by reaction with the added fuel due to the achieved air-fuel ratio close to the stoichiometric equilibrium.

As a result of the limitation of the output power of the diesel engine, an overload of the exhaust gas aftertreatment device ( 13 ) and especially the turbine ( 18th ) avoided, even if the high-load operation (mode 1 ) should last for several seconds or minutes.

Since the excess output power ( Pex ) of the diesel engine ( 1 ) via the electric motor ( 12th ) can be charged, if necessary, charging the electrical driving energy storage ( 29 ) respectively.

If in step ( S31 ) it is determined that electrical drive support is still possible or possible again (step S31 : YES), the diesel engine ( 11 ) (provided the exhaust gas temperature ( T_Ex ) still above the threshold ( T2 ) is operated in such a way that it has a power or a torque ( Pd ) equal to or below the continuous operation nominal value ( Pr ) issues. The electric motor ( 12th ) is operated in such a way that a possible power gap between that of the diesel engine ( 11 ) delivered power ( Pd ) and the target performance ( P * ) by the output power of the electric motor ( 12th ) is covered. This operating mode is in 3rd as a step ( S33 ) within a hybrid operating mode (Mode 2nd ) intended.

The operating method according to the present disclosure thus ensures that an efficient nitrogen oxide reduction is made possible in operating phases in which a high power output from the diesel engine (even without an expensive addition of urea or ammonia) ( 11 ) is required so that larger amounts of nitrogen oxides are generated, and in which, on the other hand, electrical drive support is not or no longer possible. This enables inexpensive diesel hybrid drive technology that complies with the strict emissions regulations. Possibly. can determine the continuous operation nominal value ( Pr ) on the one hand and the determination of the amount of after-engine fuel added on the other hand, ie the measures to prevent the exhaust gas temperature from T_Ex ) limit or exclude, depending on the specific system parameters are optimized against each other. It is also possible to use a separate control system to regulate the continuous operation nominal value ( Pr ) and / or the amount of after-engine fuel added depending on the exhaust gas temperature ( T_Ex ) to change, if necessary to allow maximum power output of the entire drive system.

The operating method according to the present disclosure further includes instructions and measures to prevent insufficient nitrogen oxide conversion due to an exhaust gas temperature that is too low ( T_Ex ) limit or exclude. For this purpose, the operating method can in particular provide that according to step S10 First a target power or a target torque ( P * ) is determined. If in step S12 it is determined that the exhaust gas temperature ( T_Ex ) a lower threshold ( T1 ) falls below (step S12 : YES) can be done according to step S20 Countermeasures are taken to increase the output of the diesel engine ( Pd ) and thus the exhaust gas temperature ( T_Ex ) tend to increase. In this way, the low temperature range can be avoided by, for example, also reducing emissions by using a nitrogen oxide storage catalytic converter ( LNT ) is ineffective or has insufficient efficiency.

So long as per step S21 an electrical charge of the driving energy storage ( 29 ) or any other utilization of excess power of the diesel engine ( Pd ) above the target power ( P * ) is possible (step S21 : YES), the electric motor ( 12th ) operated in such a way that it absorbs the excess power or the excess torque (step S23 in 3rd ).

However, if according to step S21 an electric charge or other utilization of the excess power by the electric motor ( 12th ) is no longer possible (step S21 : NO), the diesel engine ( 11 ) deactivated so that the electric motor ( 12th ) the full target power or the complete target torque ( P * ) he brings.

• - Gemäß Schritt S23 unter gleichzeitiger Ladung des Fahrenergiespeichers (29) erfolgen soll, in dem die Abgabeleistung (Pd) des Dieselmotors oberhalb der Soll-Leistung (P*) gewählt wird, und der Überschussbetrag der Leistung von dem Elektromotor aufgenommen wird; oder ob
• - die Soll-Leistung gemäß Schritt S14 vollständig durch die Abgabeleistung (Pd) des Dieselmotors erbracht werden soll; oder ob
• - eine elektrische Antriebsunterstützung gemäß Schritt S33 erfolgen soll, bei der die Soll-Leistung (P*) nur zum Teil durch die Abgabeleistung (Pd) des Dieselmotors und ergänzend durch die Abgabeleistung (Pel) des Elektromotors gedeckt wird.

In the operating method according to the present disclosure, it is further provided that in operating states in which the exhaust gas temperature ( T_Ex ) between the lower threshold ( T1 ) and the upper threshold ( T2 ) lies (step S11 : NO and step S12 : NO) a hybrid load distribution known in principle S13 is performed. The hybrid load distribution can essentially determine whether the target power (independent of the nitrogen oxide conversion according to optimization criteria known in practice) P * ):

• - According to step S23 with simultaneous charging of the driving energy storage ( 29 ) in which the power output ( Pd ) of the diesel engine above the target power ( P * ) is selected, and the excess amount of power is absorbed by the electric motor; or if
• - The target output according to step S14 completely through the power output ( Pd ) the diesel engine is to be provided; or if
• - An electrical drive support according to step S33 at which the target power ( P * ) only partly due to the power output ( Pd ) of the diesel engine and in addition by the power output ( Pel ) of the electric motor is covered.

It should be noted that when executing according to step S33 within the general hybrid operating mode (MODE 2nd ) only a limitation of the output power ( Pd ) of the diesel engine ( 11 ) is required if the exhaust gas temperature ( T_Ex ) the second threshold ( T2 ) has exceeded. So if a particularly high target output (only for a short time range ( P * ) is determined, but no excessive rise in the exhaust gas temperature ( T_Ex ) is to be determined (step S11 : NO), the diesel engine can step S33 also with an output ( Pd ) operated above the specified continuous operation nominal value ( Pr ) lies.

Alternatively or in addition to the aforementioned features, further measures can favor the cost efficiency and the nitrogen oxide conversion efficiency of the disclosed drive technology.

Upstream to the catalyst ( 20th ) can preferably be a plasma generator ( 22 ) be arranged. A plasma generator ( 22 , 22 ' ) can be arranged one or more times. A plasma generator is particularly preferred ( 22 , 22 ' ) in the flow direction of the exhaust gas directly before, on or immediately after a fuel addition device ( 17th , 17 ' ) arranged. By the plasma generator ( 22 ) the nitrogen oxide conversion in the catalyst ( 20th ) are significantly favored in cooperation with the added fuel, so that it takes place faster and / or with greater efficiency. The use of a plasma generator ( 22 ) can take place both in high-load operation and in a regeneration operation for the catalyst ( 20th ), which can, for example, provide a fuel addition outside of high-load operation.

In order to optimize the generation of nitrogen oxides in the combustion process, the drive device ( 10th ) preferably an exhaust gas recirculation device ( 30th ) which have exhaust gas ( 34 ) from the exhaust passage ( 14 ) to an intake passage ( 24th ) of the diesel engine ( 11 ) leads back. The exhaust gas recirculation device ( 30th ) can in particular be designed exclusively as a low-pressure exhaust gas recirculation, ie it can in particular exclusively be an exhaust gas ( 34 ) that the exhaust passage ( 14 ) at a location downstream of the catalyst ( 20th ) is removed. If necessary, at the exhaust gas passage ( 14 ) further components can be arranged which cause fuel oxidation, for example a so-called diesel oxidation catalyst (Doc). In 1 is an example of an additional fuel oxidation device ( 21 shown downstream of the catalyst ( 20th ) and upstream to the connection point with the exhaust gas recirculation device ( 30th ) is located. Only exhaust gas ( 34 ) from one point of the exhaust gas passage ( 14 ) at which the content of free hydrocarbons in the exhaust gas ( 34 ), which result from the in-engine addition amount and / or the post-engine addition amount, is reduced or eliminated. Accordingly, the exhaust gas recirculation ( 30th ) no or a negligible amount of flammable substances for the intake passage ( 24th ) and therefore there is no compensation for the injection quantity ( Qi ) on the diesel engine ( 11 ) required for compensation.

On or in the exhaust gas recirculation device ( 30th ) a cooling device, in particular an exhaust gas cooler ( 31 ) be provided. The exhaust gas recirculation device ( 30th ) more preferably has a control valve ( 32 ) through which a composition of the intake air on the one hand from recirculated exhaust gas and on the other hand from fresh air ( 33 ) that have a suction area ( 25th ) is fed, is adjustable.

In an intake passage ( 24th ) of the diesel engine ( 11 ) is preferably between the connection point of the exhaust gas recirculation device ( 30th ) and an engine inlet ( 26 ) a compressor ( 19th ) intended. The compressor ( 19th ) is preferred by the turbine ( 18th ) driven directly or indirectly.

According to a further aspect of the present invention, a low-carbon or non-carbon-burning synthetic diesel fuel can be used as the fuel. Especially in high-load operation (MODE 3rd ) the diesel engine ( 11 ) are operated with an air-fuel ratio that is significantly lower than that of conventional diesel fuels, especially in a range between 1.05 and 1.15. If dimethyl ether is used as fuel, for example, an air-fuel ratio of 1.05 be achieved. If oxymethylene ether is used as fuel, even lower values for the air / fuel mixture are possible. However, the so-called GtL (gas-to-liquid) process can also be used to produce diesel fuels that enable at least smoke-free or soot-free combustion with an air-fuel ratio of around 1.25. In the context of the present disclosure, one of the aforementioned fuels, a combination of the aforementioned fuels or a conventional diesel fuel that is mixed with at least one of the aforementioned fuels can be used. Alternatively or additionally, other suitable synthetic diesel fuels can be used alone or in combination with one of the aforementioned fuels.

Modifications of the invention are possible in various ways. In particular, all of the features written, shown or otherwise disclosed for the exemplary embodiments can be combined with one another as desired or replaced with one another.

The drive device ( 10th ) preferably comprises at least one nitrogen oxide sensor (NOx sensor 36 ) in the area of the exhaust passage, especially shortly or directly in front of the exhaust ( 16 ). Alternatively or additionally, a further nitrogen oxide sensor can be located downstream of the engine outlet ( 15 ) be arranged. Based on a determined nitrogen oxide content in the exhaust gas ( 34 ) at least at one point within the exhaust passage ( 14 ), especially downstream of the engine outlet ( 15 ) and upstream to the exhaust ( 16 ) a NOx conversion efficiency can preferably be determined. In the 3rd in steps S11 and S12 specified tests can alternatively or additionally to a comparison of the exhaust gas temperature T_Ex versus the first and second temperature thresholds ( T1 , T2 ) provide a comparison of the actual conversion efficiency with a target value. A selection of the steps S30 and or S20 may additionally depend on the actual NOx conversion efficiency falling below a target efficiency.

Reference list

10th Drive device / diesel hybrid drive Propulsion device / diesel hybrid drive 11 Diesel engine Diesel engine 12th Hybrid drive / electric motor Hybrid drive / electric motor 13 Exhaust aftertreatment device Exhaust gas after treatment device 14 Exhaust passage Exhaust gas passage 15 Engine outlet Engine outlet 16 Exhaust Tail pipe 17/17 ' Fuel adding device / fuel injector Fuel addition device / fuel injector 18th turbine turbine 19th compressor Compressor 20th Catalytic converter / three-way catalytic converter / LNT Catalyst / three-way catalyst / LNT 21 Oxidation catalyst and / or filter Oxidation catalyst and / or filter 22/22 ' Plasma generator Plasma generator 23 Control device Control device 24th Intake passage Intake passage 25th Suction area Intake section 26 Engine intake Engine inlet 27 Combustion chamber Combustion chamber 28 Fuel injector Fuel inector 29 Accumulator / electrical driving energy storage Accumulator / electric propulsion energy storage 30th Exhaust gas recirculation Exhaust gas recirculation 31 Exhaust gas cooler Exhaust gas cooler 32 Control valve Control valve 33 Fresh air Fresh air 34 Exhaust gas Exhaust gas 35 Lambda sensor Lambda sensor 36 NOx sensor NOx sensor P * Target power / target torque Target power / target torque Pd Power output diesel engine Output power of diesel engine Pel Power of the electric motor (intake or delivery) Power of electric motor (intake or output power) Pr Nominal value / nominal power for continuous operation of the diesel engine Rated power for permanent operation of Diesel engine T_Ex Exhaust gas temperature Exhaust gas temperature T1 First temperature threshold First temperature threshold T2 Second temperature threshold Second temperature threshold Qi Fuel injection quantity / fuel quantity burned Fuel injection quantity / burned fuel quantity NE rotational speed Rotational speed

Claims (11)

Drive device for a vehicle with a diesel engine (11) and an electric motor (12), the drive device (10) comprising: - an exhaust gas aftertreatment device (13), for treating the exhaust gas (34) of the diesel engine (11), the exhaust gas - Aftertreatment device (13) has an exhaust gas passage (14), on which are arranged in the flow direction of the exhaust gas (34): ◯ A controllable fuel addition device (17) to add fuel to the exhaust gas (34) in the exhaust gas passage (14); ◯ a catalyst (20) for removing nitrogen oxides (NOx) from the exhaust gas (34) by reaction with the added fuel; - A control device (23) for controlling the fuel addition; characterized in that the control device (23) is designed to control the fuel addition device (17) in high-load operation (MODE 1) of the drive device (10) in such a way that by adding fuel to the exhaust gas (34) (After-engine addition quantity) the air-fuel ratio of the exhaust gas (34) in the region of the catalytic converter (20) is approximated to a target value which is close to the stoichiometric equilibrium; AND - to determine a required amount for a fuel addition in the diesel engine (11) (in-engine addition amount) that is required in addition to the after-engine addition amount to the air-fuel ratio of the exhaust gas (34) in the range of the catalytic converter (20) to approach the target value; AND - to generate an add-on control instruction for the diesel engine (11) so that the in-engine add-on amount of fuel is added to the drive device (10) in high-load operation (MODE 1); - To generate a compensation control instruction for the electric motor (12) so that an excess power (Pex) of the diesel engine (11), which results from the in-engine addition quantity, is absorbed by the electric motor (34). Drive device after Claim 1 , wherein the catalyst (20) is a three-way catalyst or a NOx storage catalyst. Drive device according to one of the Claims 1 or 2nd , A plasma generator (22) being arranged upstream of the catalytic converter (20). Drive device according to one of the preceding claims, wherein the control device (23) is configured to generate the addition control instruction in such a way that it includes a specification for the type of injection, so that the in-engine addition quantity - is added entirely as part of a main injection, OR - Proportionally as part of a main injection and proportionally as part of a post-injection. Drive device according to one of the preceding claims, wherein the drive device (10) has an exhaust gas recirculation device (30), the exhaust gas (34) from the exhaust gas passage (14) to a Intakes passage (24) of the diesel engine (11), and wherein the exhaust gas recirculation device (30) in particular only returns an exhaust gas (34) that the exhaust gas passage (14) at a point downstream to the catalyst (20) or further downstream after a fuel Oxidation device (21) is removed so that the content of free hydrocarbons, which result from the in-engine addition amount and / or the post-engine addition amount, is reduced or eliminated in the recirculated exhaust gas. Drive device according to one of the preceding claims, wherein the fuel is a soot-free or soot-free synthetic diesel fuel, and in particular in high-load operation (MODE 1) the diesel engine (11) is operated with an air-fuel ratio between 1.05 and 1.15. Operating method for a drive device (10) according to the preamble of Claim 1 , wherein the operating method comprises a high-load operating mode (MODE 1), in which the following steps are carried out: adding fuel to the exhaust gas (34) downstream of the diesel engine (11) and upstream to the catalytic converter (20) (after-engine) Fuel addition) in order to bring the air-fuel ratio of the exhaust gas (34) in the region of the catalytic converter (20) closer to a target value which is close to the stoichiometric equilibrium; - Determining a required amount for a fuel addition in the diesel engine (11) (in-engine addition amount), which is required in addition to the after-engine addition amount, the air-fuel ratio of the exhaust gas (34) in the region of the catalyst (20) to approach the target value; - adding the in-engine addition quantity in the diesel engine (11) with any generation of excess engine power (Pex); - Recording the excess engine power (Pex) of the diesel engine (12) on the electric motor (13). Operating method according to the preceding claim, wherein the operating method further comprises the following steps: - Determining a target power or a target torque (P *); - If the exhaust gas temperature (T_Ex) exceeds an upper threshold value (T2): limitation of the output power or the output torque (Pd) of the diesel engine (11) to a fixed continuous operation nominal value (Pr); AND - If no electrical drive support is possible, execute the high-load operating mode (MODE 1). Operating method according to one of the Claims 7 or 8th , further comprising: - If electric drive assistance is possible: operating the diesel engine (11) so that it delivers a power or a torque (Pd) equal to or below the continuous operation nominal value (Pr); AND if the output power or the output torque (Pd) is below the target output or below the target torque (P *): operating the electric motor (12) to cover the power gap or the torque gap (P * -Pd). Operating method according to one of the Claims 7 to 9 , wherein the operating method further comprises the following steps: - determining a target power or a target torque (P *); - If the exhaust gas temperature (T_Ex) falls below a lower threshold value (T1) and electrical charging is not possible: Deactivate the diesel engine (11) so that the electric motor (12) provides the full set power or the full set torque (P *) . Operating method according to one of the Claims 7 to 10th , wherein the operating method further comprises the following steps: - determining a target power or a target torque (P *); - If the exhaust gas temperature (T_Ex) falls below a lower threshold value (T1) and an electrical charge is possible: operate the diesel engine (11) so that it produces a power or a torque (Pd) above the target power or above the target torque ( P *) emits and recording the excess power or the torque on the electric motor (12).

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