EP3247892A1

EP3247892A1 - Method for operating an internal combustion engine having at least one turbocharger, control device, equipped for implementing a method of this type, internal combustion engine having a control device of this type and motor vehicle having an internal combustion engine of this type

Info

Publication number: EP3247892A1
Application number: EP16700797.0A
Authority: EP
Inventors: Alexander Bernhard; Wolfgang Fimml
Original assignee: MTU Friedrichshafen GmbH
Current assignee: Rolls Royce Solutions GmbH
Priority date: 2015-01-23
Filing date: 2016-01-15
Publication date: 2017-11-29
Also published as: US10508605B2; WO2016116265A1; DE102015201191A1; DE102015201191B4; HK1248787A1; CN107532532A; US20180016996A1

Abstract

A method for operating an internal combustion engine (3) having at least one turbocharger (9) is proposed, wherein - a fuel quantity is supplied to the combustion chamber of the internal combustion engine (3) in a stationary state, which fuel quantity is determined in accordance with a first predetermined relationship (31) between a load requirement to the internal combustion engine (3) and a rating determining a fuel quantity to be supplied to the combustion chamber (7), wherein - a second predetermined relationship (39) between the rating and the load requirement is used, wherein - according to the second relationship (39), a given load requirement is assigned a larger quantity of fuel than according to the first relationship (31), wherein - in a transient state of the internal combustion engine (3), the fuel quantity supplied to the combustion chamber (7) is determined on the basis of an interpolated value (BG_int) of the rating, which is determined for the rating by means of an interpolation (41) between a value (BG₁) resulting from the first relationship (31) and a value (BG₂) resulting from the second relationship (39) .

Description

DESCRIPTION Method for operating an internal combustion engine with at least one turbocharger, control device configured to carry out such a method,

Internal combustion engine with such a control device, and motor vehicle with such an internal combustion engine. The invention relates to a method for operating an internal combustion engine

Control device configured to carry out such a method, a

Internal combustion engine with such a control device, and a motor vehicle with such an internal combustion engine. In particular, in internal combustion engines, which are operated with fuel gas as fuel, a lean operation is often provided to reduce emissions, the

Internal combustion engine with a high excess of air and correspondingly lower

Fuel mass is operated. This is counterproductive in particular in supercharged internal combustion engines with regard to a load shifting capability, since in lean operation only one

comparatively low exhaust gas mass flow is formed, which can accelerate the turbocharger insufficiently. Its dynamic response is thereby delayed, which ultimately also delays the dynamic response of the entire engine.

The invention is based on the object, a method for operating a

Internal combustion engine with a turbocharger, a control device, set up for

Carrying out such a method, an internal combustion engine with such

Control device, and to provide a motor vehicle with such an internal combustion engine, said disadvantages do not occur. The object is achieved by providing the subject matters of the independent claims. Advantageous embodiments emerge from the subclaims.

The object is achieved in particular by a method for operating a

Internal combustion engine is provided with at least one turbocharger, in which at least a combustion chamber of the internal combustion engine in a steady state, a fuel amount according to a first predetermined relationship between a load request to the internal combustion engine and the fuel quantity to be supplied to the combustion chamber

is supplied to determining design variable, wherein a second predetermined

Relationship between the design size and the load request is used, wherein according to the second context of a given load request, a larger amount of fuel is assigned than according to the first context, the

Combustion chamber supplied amount of fuel in a transient state of the internal combustion engine is determined based on an interpolated by an interpolation between one of the first context and a resulting from the second context value of the design variable value of the design variable. The fact that a given load request according to the second context is associated with a larger amount of fuel than according to the first context means that the combustion chamber is intended to be a larger one

Fuel quantity is supplied when the design value is determined according to the second relationship, so that the internal combustion engine is operated according to the second context with a richer mixture, wherein the combustion chamber, a smaller amount of fuel is supplied when the design variable is determined according to the first context, wherein the internal combustion engine in this case - with the load demanded - operated with a leaner mixture than according to the second context. The

Internal combustion engine can therefore be operated in a steady state in lean operation, in particular to reduce emissions. In the transient state, enrichment of the mixture in the at least one combustion chamber can be effected by interpolating between values resulting from the first and the second context, thereby increasing the exhaust gas mass and thus improving the overall dynamic response of the turbocharger and thus also of the internal combustion engine as a whole becomes.

In this case, a "transient state" in the sense of the method is in particular a state in which a load request to the internal combustion engine and / or a rotational speed of the internal combustion engine is / are increased According to the method, the internal combustion engine increases faster, the mixture in the combustion chamber is enriched, so that the exhaust gas mass is increased, thereby improving the dynamic response of the turbocharger. The load request to the internal combustion engine is preferably represented as torque, which is demanded of the internal combustion engine or which applies the internal combustion engine. In particular, a torque of the internal combustion engine is preferably used in the context of the method as a load request.

The first relationship preferably exists between a load request to the

Internal combustion engine, a speed of the internal combustion engine, and the rated size.

In particular, the first relationship preferably sets the design variable

Depending on the load request and the speed. This is the first

The context is preferably identical for the second context.

Accordingly, it is particularly preferable according to the second context of a given load request and a given speed associated with a larger amount of fuel than according to the first context.

In the context of the method, the internal combustion engine is preferably operated with a fuel gas as fuel. In particular, a gas engine is preferably operated, particularly preferably a lean-burn gas engine, which is driven in stationary states in lean operation. This realizes in a special way, the advantages of the process. At least one combustion chamber of the internal combustion engine, the fuel gas via a Saugrohreindüsung, especially as cylinder individual Saugrohreindüsung, as Einzelpunkteindüsung (single point injection) in a charge air line of the engine, in particular upstream of a charge air compressor, or as Direktindüsung be fed directly into the combustion chamber. In this case, the amount of fuel gas supplied to the combustion chamber is preferably determined by a combustion gas valve arranged in a fuel gas line, which is controlled as a function of the design variable. It is particularly possible that as

Rated variable is a lambda setpoint, so a setpoint for the combustion air ratio is used, which is also referred to as air ratio or air ratio. This dimensionless measure gives the mass ratio of air and fuel in a combustion process. In this case, the value 1 corresponds to a stoichiometric combustion air ratio, thus a complete combustion, with values smaller than 1 indicating a rich mixture and values greater than 1 indicating a lean mixture. An embodiment of the method is preferred which is characterized in that the first relationship between the load requirement and preferably the rotational speed and the design variable is optimized with regard to reduced, in particular the lowest, possible emissions of the internal combustion engine. The first relationship is thus established in order to realize a lean operation of the internal combustion engine and to operate the internal combustion engine with the lowest possible emissions.

Alternatively or additionally, it is preferably provided that the second relationship between the load requirement and preferably the speed and the design variable a

Knock limit of the engine maps. This means that the values of the

Rated variable, which according to the second context depends on the

Load request and preferably are deposited depending on the speed, are selected so that the internal combustion engine at a design of the combustion chamber supplied

Brennstoffrnenge after the second context just does not knock. The

Internal combustion engine would therefore start knocking when held load demand and preferably held speed when the combustion chamber a larger

Fuel quantity would be supplied, as it is determined by the determined according to the second relationship dimension. This refinement of the second context is advantageous because the internal combustion engine can thus be operated to be maximally rich without the risk of damaging by knocking, so that a maximum exhaust gas mass flow can be made available to the turbocharger for a given load requirement and preferably given rotational speed. The dynamic response of the internal combustion engine is then optimally improved. An embodiment of the method is also preferred, which is characterized in that a characteristic diagram is used as the first context in which values for the

Rated variable as a function of the speed and the torque of the

Internal combustion engine are deposited. This represents a particularly simple implementation of the first context.

Alternatively or additionally, a map is preferably used as the second context, in which values for the rated size in dependence on a speed and a

Torque of the internal combustion engine are stored. Thus, also for the second context, a particularly simple to implement implementation. An embodiment of the method is also preferred, which is characterized in that the interpolation between the first and the second context is carried out as a function of a differential rotational speed. The differential speed is calculated as the difference between a target speed and a current actual speed of the internal combustion engine. A transient state in the sense of the method is in this case in particular

characterized in that the instantaneous actual speed of the internal combustion engine of a

Specification for the speed deviates, in particular, the target speed is greater than the current actual speed, so that the engine must be accelerated to the target speed. Such speed specifications can be found, for example, in internal combustion engines, which are provided for driving a watercraft, in particular a ship, wherein a target speed for the internal combustion engine is set directly by means of a driving lever by a ship's guide. Is interpolated depending on the differential speed, this allows a flexible enrichment of the mixture depending on the actual distance of the current actual speed of the target speed. In this case, it is particularly possible to grease the mixture with smaller deviation to a lesser extent than with greater deviation. The dynamic response of the internal combustion engine is thus controlled demand, which

saves fuel in particular and keeps emissions as low as possible, despite enrichment. The interpolation preferably takes place according to the following equation:

BG _int = BG ₁ + g (BG ₂ - BG. (1)

Where BGj _{nt is} the interpolated value of the design variable, BG | is determined according to the first related value for the measurement parameter, BG ₂ is determined according to the second related value for the design size, and g is an interpolation factor having a value range of at least 0 to at most 1, wherein the value of

Interpolation factor is determined as a function of the differential speed.

According to equation (1), it is obvious that the interpolated value BGi "t of the design quantity is equal to the value Gi determined by the first relationship, if the

Interpolation factor g has the value 0. If the interpolation factor g has the value 1, the interpolated value BGj _{nt of} the rated value is equal to that according to the second one

Related value BG _{2 of} the rated value. The interpolation factor is preferably read from a first characteristic curve, the first characteristic curve having values of the interpolation factor g as a function of the differential rotational speed. In a preferred embodiment of the method it is provided that the course of the characteristic is steep, the characteristic being particularly preferably within one

Differential speed range, which is from at least 5 U / min to at most 20 U / min, preferably from at least 10 U / min to at most 15 U / min, wide, from the value 0 to the value 1 increases.

Particularly preferably, an increase in the characteristic is already provided at small differential speeds. In particular, it is possible that the value of the interpolation factor g in a differential speed range from 0 rpm to a starting differential speed which is from at least 5 rpm to at most 10 rpm is equal to 0, the value being 1 for the

Interpolation factor g is achieved at a differential speed of preferably 20 U / min.

A steep first characteristic allows a particularly dynamic response of the

Turbocharger and also the internal combustion engine in total. An embodiment of the method is also preferred, which is characterized in that a lambda setpoint value for the internal combustion engine is used as the design variable. This is particularly favorable for the operation of an internal combustion engine designed as a gas engine, because in such an internal combustion engine, the fuel quantity to be supplied to the combustion chamber is typically controlled anyway via a desired lambda value. In this case, the lambda desired value is preferably used to control a fuel valve, in particular a fuel gas valve, which defines the fuel quantity to be supplied to the combustion chamber.

Preferably, however, the fuel valve is not controlled directly with the lambda desired value, but this is previously converted into another, suitable for driving the fuel gas valve size, for example in a fuel gas mass flow or in a fuel gas mass to be supplied per stroke of the combustion chamber associated piston.

An embodiment of the method is also preferred in which, in a transient state, an ignition timing of the internal combustion engine is determined by interpolation between a first predetermined ignition timing, which is between an ignition point of time Internal combustion engine and a load request - and preferably a speed - the internal combustion engine is set, and a second predetermined ignition timing, which is also adjusted between an ignition timing of the internal combustion engine and a load request - and preferably a speed - the internal combustion engine, is retarded. It is thus provided in particular that the ignition point in the transient state of the internal combustion engine is determined by an interpolation between an ignition point determined according to the first ignition point relationship and an ignition point determined according to the second ignition point relationship. By adjusting the ignition timing to late the knock limit of the engine is shifted so that the combustion chamber, a larger amount of fuel can be supplied without knock risk. The internal combustion engine can therefore be operated in the transient state with even richer mixture when the ignition is retarded. Thus, the exhaust gas mass flow, with which the turbocharger is applied, be further increased, whereby the dynamic response of the turbocharger and also the

Internal combustion engine itself can be further improved.

In this case, an ignition point determined for a given load request and preferably given rotational speed according to the first ignition timing context is earlier than an ignition timing determined according to the second ignition timing context. Therefore, a retardation is always effected by the interpolation and allows an additional enrichment of the mixture in the combustion chamber.

The first ignition timing relationship is preferably in terms of reduced,

optimized in particular the lowest possible emissions of the internal combustion engine. Alternatively or additionally, the second ignition-time relationship is preferably based on a technical

Limitation for the retardation of the ignition timing tuned out and forms in particular a technically possible limit for the retardation of the ignition timing from. In particular, it is possible that the second ignition timing relationship is a knock limit of

Internal combustion engine maps with respect to the ignition, wherein the internal combustion engine would knock if the ignition would be chosen later than is the case for a given load request and preferably given speed according to the second ignition timing. The first ignition-time relationship is preferably a characteristic map in which values for the ignition time are stored as a function of a rotational speed and a torque of the internal combustion engine. Alternatively or additionally, for the second

Zündzeitpunkt context preferably uses a map, are deposited in the values for the ignition timing in dependence on the speed and the torque of the internal combustion engine.

The interpolation is also preferably with respect to the ignition depending on the differential speed, which is calculated as the difference between a desired speed and a current actual speed of the internal combustion engine.

In particular, the interpolation of the ignition timing preferably takes place according to the following equation:

ZZP _int = ZZP _i + h (ZZP ₂ - ZZP. (2)

Here, ZZPj _{nt is} the interpolated value for the ignition timing, ZZP _\ is a value for the ignition timing determined according to the first ignition timing, ZZP ₂ denotes a value for the ignition timing determined according to the second ignition timing, and h is an ignition timing interpolation factor which has a value range of at least 0 to at most 1, wherein it is preferably given as a function of the differential rotational speed. In particular, the ignition timing interpolation factor h is preferably determined on the basis of a second characteristic which has values for the ignition timing interpolation factor h as a function of the differential rotational speed. In this case, it is apparent from equation (2) that the interpolated ignition timing ZZP _ln t is equal to the ignition timing ZZP _\ determined according to the first ignition timing, when the ignition timing interpolation factor h is 0, being equal to that of the second

Ignition timing ZZP ₂ is when the ignition timing interpolation factor h has the value 1.

It is possible that the same characteristic is used as the first characteristic curve and as the second characteristic curve. However, an embodiment of the method is preferred in which the second characteristic curve is selected differently from the first characteristic curve, wherein in particular a starting value for the differential rotational speed, from which values for the ignition-time interpolation factor h deviate from 0, in comparison to the first characteristic higher differential speeds is shifted. In particular, it is possible for an increase in the second characteristic to begin only at a differential speed of 20 rpm. An embodiment of the method is preferred in which a gradient of the second characteristic curve is identical to a gradient of the first characteristic curve, such that the difference between the characteristic curves is purely linear

Shifting the second characteristic to higher differential speeds limited. Alternatively, however, it is also possible for the second characteristic curve to also have a gradient which is different from the gradient of the first characteristic curve, wherein it increases in particular less steeply than the first characteristic curve. Both a shift of the second characteristic to higher

Differential speeds as well as a reduction of the slope of the second characteristic in

Compared to the first characteristic curve causes the Zündzeitpunkt- shift only at larger deviations of the actual speed of the target speed is effective. This ultimately leads to an increased dynamics of the internal combustion engine is only made available when it is actually required to compensate for comparatively large speed differences as quickly as possible. At lower speed differences can be saved in this way fuel, at the same time, the emissions of the internal combustion engine are lower than if the first characteristic and the second characteristic would be equal.

In particular, an embodiment of the method is preferred in which in addition to the retardation of the ignition timing, a design size Zusatzterm with the

interpolated value of the design variable, the design variable additional term being calculated by scaling a design difference value between a value for the design variable resulting from a predetermined third relationship and the value resulting from the second context, the third relationship being established again is between a load request - and preferably a speed - of the internal combustion engine and the rated size. By means of the design variable Zusatzterms it is possible to additionally greasy the mixture in the combustion chamber by supplying additional fuel and thus exploit the shift of the knock limit due to the shift of the ignition timing to late. The design variable additional term can be offset either additively or multiplicatively with the interpolated value of the design variable.

It is provided in particular that according to the third context of a given load request - and preferably a given speed - a larger amount of fuel is assigned than according to the second context. In this case, the third relationship preferably forms a knock limit of the internal combustion engine at the retarded ignition timing according to the second ignition timing relationship. In a corresponding manner, the second relationship preferably forms the knock limit of the internal combustion engine at the ignition time determined in accordance with the first ignition-time relationship, the first ignition-time relationship preferably being present in all

States of the internal combustion engine is used for determining the ignition timing, in which no interpolation between the first ignition timing and the second ignition timing relationship occurs, ie in particular in stationary states, and preferably also in transient states, which in connection with a load shedding or a reduction go along with the target speed. The design variable is therefore preferably chosen according to the third context that the internal combustion engine just does not knock at a given load request and preferably given speed when the

Combustion chamber which is supplied by the design quantity of fuel. On the other hand, the internal combustion engine starts to knock when it is supplied with a larger amount of fuel at a given load request and preferably given rotational speed, than it is the design variable according to the third context in the retarded

Ignition timing corresponds. The design size additional term is preferably determined according to the following equation:

ABG = k {BG ₃ - BG ₂ ). (3)

In this case, ABG is the design variable additional term, BG ₂ is again the value of the design variable determined according to the second context, BG ₃ is one according to the third

Context specific value of the rated value, (BG ₃ -BG ₂ ) is the rated size difference value, and k is a scaling factor having a value range of at least 0 to at most 1, the scaling factor k being determined depending on the differential speed. The scaling factor k is preferably determined on the basis of a third characteristic curve, wherein the third characteristic curve has values for the scaling factor k as a function of the differential rotational speed. It is possible that the third characteristic is different from the first characteristic and the second characteristic. Particularly preferred, however, is an embodiment in which the third characteristic curve is selected to be identical to the second characteristic curve, or in which the second characteristic curve is used as the third characteristic curve for determining the scaling factor k is used. This has the advantage that the scaling of the design variable additional term ABG is matched to the interpolation of the ignition timing, so that - assuming a linear relationship between the Zündzeitpunkt- shift and the shift of the knock limit - always at the interpolated ignition optimally matching

Rated size additional term is selected. This makes it possible overall, the

Internal combustion engine at each selected ignition optimal fat, especially with maximally enriched mixture, but at the same time without knock risk to operate.

In a preferred embodiment of the method, the total amount of fuel to be supplied to the combustion chamber is determined by a design value setpoint, which is calculated according to the equation reproduced below as the sum of the interpolated value BGj _nt for the design variable and the design variable additional term ABG:

BG _should = BG _int + ABG. (4)

In this case, BG _is n the rated value setpoint.

In the context of a preferred embodiment of the method, the value of

Rated size, which ultimately determines the amount of fuel to be supplied, thus in particular the interpolated value of the rated size BGjnt or the design parameters set value BG _as u, limited by a limiter to a maximum value of Figure 1. This ensures advantageously that the internal combustion engine is not operated in a transient state according to the method with a lean mixture, wherein the amount of fuel supplied corresponds at least to the stoichiometric amount of fuel.

It is preferably provided that the value of the rated quantity provided for determining the amount of brake fluid to be supplied is converted by a conversion function into a fuel quantity to be supplied, in particular a fuel gas quantity to be supplied, and / or into a suitable size for driving a fuel valve, in particular a fuel mass flow or a per Hub of the combustion chamber associated piston supplied Brer pulp.

Overall, it is preferably provided in the context of the method that, as a function of a difference between the instantaneous actual rotational speed of the internal combustion engine and the nominal Speed an additional amount of fuel is introduced into the combustion chamber. This additional amount is preferably specified as the desired lambda value. In principle, it is possible to enrich a mixture in the combustion chamber until the internal combustion engine starts to knock. Therefore, if there is a load request, the engine may operate at its knock limit to accelerate the turbocharger. If the actual speed approaches the target speed, the additional enrichment is removed, and the

Internal combustion engine is stationary again adjusted to reduced emissions. By shifting the ignition timing to late, an even greater amount of fuel can be introduced into the combustion chamber, as the knock limit is shifted by the retardation of the ignition timing. This therefore offers the possibility of being able to inject more fuel into the combustion chamber. Thus, a much better result

Lastschaltvermögen the internal combustion engine and improved engine dynamics.

The object is in particular also achieved by providing a control device which is set up for carrying out a method for operating a

Internal combustion engine with at least one turbocharger, wherein the control device is arranged to a combustion chamber of the internal combustion engine in a stationary state a

Fuel quantity according to a first predetermined relationship between a

Load request to the internal combustion engine and a supply to the combustion chamber to be supplied amount of fuel determining design variable, wherein in the control device, a second predetermined relationship between the design variable and the

Load request is deposited, wherein according to the second context of a given load request, a larger amount of fuel is assigned than according to the first

And wherein the control device is set up to determine the fuel quantity supplied to the combustion chamber in a transient state of the internal combustion engine based on an interpolated value for the design variable, wherein the interpolated value is determined by an interpolation between one of the first context and one of the second relationship resulting value of the design variable is determined. The control device is in particular configured to carry out a method according to one of the above

described embodiments. In connection with the control device, the advantages that have already been explained in connection with the method result.

The control device is preferably designed as an engine control unit for an internal combustion engine, in particular as a central engine control unit (ECU). It is possible that the method is firmly implemented in an electronic structure, in particular in a hardware, the control device. Alternatively, it is possible for a computer program to be loaded into the controller having instructions for performing a method according to any of the embodiments described above when the computer program product is running on the controller. In that regard, a computer program product is preferred which has machine-readable instructions, due to which a method is performed according to one of the embodiments described above, when the computer program product on a

Computing device, in particular on a control unit of an internal combustion engine, runs. Also preferred is a data carrier having such a compute rogrammprodukt.

The object is also achieved by providing a - preferably speed-controlled - internal combustion engine, which has a control device according to one of the embodiments described above. The control device is in particular configured to carry out a method according to one of the previously described

Embodiments. Thus, in connection with the internal combustion engine, the advantages that have already been explained in connection with the method.

An exemplary embodiment of the internal combustion engine is preferred in which it is designed as a gas engine. Particularly preferably, the internal combustion engine is designed for operation with lean gas, in particular thus as a lean-burn gas engine. For such

Embodiment of the internal combustion engine realize in a special way the advantages that have already been explained in connection with the method.

The internal combustion engine is preferably designed as a reciprocating engine. At a

preferred embodiment, the internal combustion engine is used to drive in particular heavy land or water vehicles, such as mining vehicles, trains, the internal combustion engine is used in a locomotive or a railcar, or ships. It is also possible to use the internal combustion engine to drive a defense vehicle, for example a tank. An embodiment of the Internal combustion engine is preferably also stationary, for example, for stationary

Energy supply used in emergency power, continuous load operation or peak load operation, the internal combustion engine in this case preferably drives a generator. A stationary application of the internal combustion engine for driving auxiliary equipment, such as fire pumps on oil rigs, is possible. Furthermore, an application of the

Internal combustion engine in the field of promotion of fossil raw materials and in particular fuels, for example oil and / or gas possible. It is also possible to use the internal combustion engine in the industrial sector or in the field of construction, for example in a construction or construction machine, for example in a crane or an excavator. The

Internal combustion engine may be designed as a diesel engine, as a gasoline engine, but more preferably as a gas engine for operation with natural gas, biogas, special gas or other suitable gas. In particular, when the internal combustion engine is designed as a gas engine, it is suitable for use in a cogeneration plant for stationary power generation. Finally, the object is also achieved by providing a motor vehicle which has an internal combustion engine according to one of the exemplary embodiments described above. In this case, realized in connection with the motor vehicle, the advantages that have already been explained in connection with the method, the control device and the internal combustion engine.

The motor vehicle is preferably designed as a passenger car, as a truck, as a commercial vehicle, as a construction machine, as a rail vehicle, in particular as a locomotive, shunting locomotive, railcar, power car or train. It is also possible that the motor vehicle is designed as a defense vehicle, for example as a tank.

Particularly preferred is a motor vehicle, which is designed as a watercraft, in particular as a ship or as a submarine. In this case, in particular in the case of a watercraft, typically a desired rotational speed is determined by an operator of the watercraft for the vessel

Internal combustion engine specified.

It is also possible for the motor vehicle to be designed as an aircraft, for example as an aircraft, in particular as a propeller aircraft, it being possible for the vehicle to be used

Internal combustion engine, for example, a drive of a propeller is used. Also in this case preferably a specification of a desired speed is provided. It is also preferred a stationary system with an internal combustion engine according to one of the embodiments described above. The internal combustion engine is preferably provided in the stationary system for a variable-speed operation. The stationary plant can be a device for generating electricity, a stationary pump, which is intended for example for the extraction of raw materials, a fire pump on a drilling rig, or another suitable stationary plant.

The description of the method on the one hand and the control device, the internal combustion engine and the motor vehicle on the other hand are to be understood as complementary to one another. Features of the control device, of the internal combustion engine and of the motor vehicle, which have been explained explicitly or implicitly in connection with the method, are preferably individually or combined with one another Features of a preferred embodiment of the control device, the internal combustion engine or the motor vehicle. Method steps which have been explained explicitly or implicitly in connection with the control device, the internal combustion engine and / or the motor vehicle are preferably individually or combined with one another Steps of a preferred embodiment of the method. This is preferably characterized by at least one method step, which is characterized by at least one feature of the control device, the

Internal combustion engine or the motor vehicle is conditional. The control device, the

Internal combustion engine and / or the motor vehicle preferably draws / distinguishes itself by at least one feature, which is due to at least one method step of a preferred embodiment of the method.

The invention will be explained in more detail below with reference to the drawing. Showing:

Fig. 1 is a schematic representation of an embodiment of a motor vehicle with an internal combustion engine;

Fig. 2 is a schematic detail of an embodiment of the method, and

3 shows a further schematic detail representation of the embodiment of the method according to FIG. 2.

1 shows a schematic representation of an exemplary embodiment of a motor vehicle 1, which has an internal combustion engine 3. The motor vehicle 1 is for example as

Watercraft, in particular as a ship trained. The internal combustion engine 3 has a here Engine block 5 with at least one combustion chamber 7. Preferably, the internal combustion engine 3 is designed as a reciprocating piston engine. It is possible that they have a plurality of

Has combustion chambers, in particular four, six, eight, ten, twelve, sixteen, eighteen, twenty cylinders, or more cylinders or other number of cylinders. It is possible for the internal combustion engine 3 to be designed as a series engine, as a V engine, as a W engine or in another suitable configuration.

The internal combustion engine 3 has a turbocharger 9, which has a turbine 13 arranged in an exhaust gas line 11, which flows through a gas flowing in the exhaust gas line 11

Exhaust gas mass flow is driven, wherein the turbine 13 is operatively connected via a shaft 15 with a arranged in a charge air line 17 compressor 19, so that the compressor 19 is driven by the turbine 13 via the shaft 15. In the charge air line 17 is - here downstream of the compressor 19 - a Eindüseinrichtung 21 for one as a fuel gas

formed fuel for operating the internal combustion engine 3 is arranged. Of the

Eindüseinrichtung 21, the fuel gas is supplied via a fuel gas line 23. Alternatively, it is possible for the injection device 21 to be arranged upstream of the compressor 19, that is, upstream of the compressor 19. There are different ways of injection of the

Fuel gas into the charge air possible, namely in particular as Einzelpunkteindüsung, preferably in front of the compressor 19, as Saugrohreindüsung downstream of the compressor 19, in particular as a cylinder Mehrfachindüsung individual combustion chambers 7 individually associated Saugrohrabschnitte, or in the form of a direct injection into the individual combustion chambers. 7

In any case, the combustion air by means of the Eindüseinrichtung 21 an adjustable, variable amount of fuel gas can be supplied, the Eindüseinrichtung 21 for setting the combustion chamber 7 supplied amount of fuel can be controlled.

The internal combustion engine 3 has a control device 25, preferably as

Engine control unit (ECU) is formed. The control device 25 is operatively connected to the Eindüseinrichtung 21 to specify a fuel quantity to be supplied to the combustion chamber 7. It is also preferably operatively connected to a speed sensor 27 for detecting a current actual speed of the internal combustion engine 3. Furthermore, the

Control device 25 with a speed-setting device 29, here a drive lever, operatively connected to the specification of a desired speed for the internal combustion engine 3. The Control device 25 is in particular configured to calculate a differential rotational speed between the setpoint speed determined by means of the speed setting device 29 and the actual speed detected by means of the speed sensor 27. Known control devices are typically set up for one as possible

low-emission operation of such trained as gas engines internal combustion engines. The disadvantage here is that in the case of a load application no sufficient exhaust gas mass flow to

Is available to ensure a sufficiently dynamic response of the turbocharger 9. Such internal combustion engines are therefore generally quite inert and have an improved transient ability.

In order to remedy this disadvantage, the control device 25 shown in FIG. 1 is designed to carry out a method according to one of the embodiments described above, in particular an embodiment of the method as described below in connection with FIGS. 2 and 3. In this case, the control device 25 is in particular designed to control the injection device 21 as a function of the determined differential rotational speed.

Fig. 2 shows a schematic representation of a detail of an embodiment of a

A first predetermined relationship 31 is provided in the form of a characteristic diagram, which values BGi for a design variable, which determines a fuel quantity to be supplied to the combustion chamber 7, as a function of a rotational speed 35 and a torque 37 of the internal combustion engine 3. In this case, the first relationship 31 is optimized with regard to the lowest possible emissions of the internal combustion engine 3. In particular, in stationary states of the internal combustion engine 3, the amount of fuel to be supplied to the combustion chamber 7 is preferably determined by the values BGi of the design variable determined according to the first relationship 31. In particular, the design variable is a lambda setpoint.

There is also a second predetermined relationship 39 between the design variable, in this case the desired air ratio, and the rotational speed 35 and the torque 37 in the form of a second characteristic map. From this second context 39 results in

Depending on the speed 35 and the torque 37 is a value BG ₂ for the Rated size. In this case, the second relationship 39 forms a knock limit of

Internal combustion engine 3 from. Thus, the values BG _{2 of} the rated value according to the second relationship 39 are lambda nominal values at the knock limit. In order to improve the transient behavior of the internal combustion engine 3, in a transient state in which there is a load connection and in particular the speed of the

Internal combustion engine 3 is to be increased, carried out an interpolation 41 between the determined according to the first context 31 value BGi the design variable and the determined according to the second context 39 value BG _{2 of} the design variable. In this case, the interpolation takes place as a function of a speed difference 43, wherein an interpolation factor g is read out in accordance with a first characteristic 45 as a function of the differential speed 43. The interpolation 41 is preferably carried out according to equation (1) given above.

This results in an interpolated value BGjn _t for the rated value.

It is possible for this interpolated value BGj _{nt of} the rated value to be used per se for determining the fuel quantity to be supplied to the combustion chamber 7.

In the embodiment of the method illustrated here, however, it is additionally provided that in a calculation element 47, a design variable additional term ABG is offset against the interpolated value BGint of the design variable.

In this case, it is possible in principle for the design variable additional term ABG to be a multiplicative term that is multiplied by the interpolated value BGim. In the embodiment shown here, however, it is preferably provided that the charging element 47 is designed as an addition element, wherein the rated quantities Zusatzterm ABG is formed as an additive term and in particular as a summand, according to the above equation (4) to the interpolated design variable BGi _{nt is} added. The interpolated value BGi _nt is preferably a lambda desired value.

Accordingly, the design variable additional term ABG is preferably a lambda addition value. Offsetting in the clearing element 47 results in a rated value setpoint BGsoii- This is also a lambda setpoint.

Since the internal combustion engine 3 is not to be operated lean in the transient state, preferably a restriction member 49 is provided which - in particular by forming a maximum between the design parameters set value BG _as n and 1 - the value of the

Rated size setpoint BG _so n and thus in particular the desired air ratio limited to 1. Furthermore, a conversion function 51 is preferably provided by which the limited rated value setpoint is converted into a value suitable for driving the injection device 21, for example, into a stock mass flow or a fuel mass to be injected per stroke of a piston assigned to the combustion chamber 7. From the

Conversion function 51, in which preferably enter in particular a pressure and a temperature of the fuel, finally results in a control value 53, with which the Eindüseinrichtung 21 is controlled by the control device 25.

3 shows a second detailed representation of the embodiment of the method according to FIG. 2. Identical and functionally identical elements are provided with the same reference symbols, so that reference is made to the preceding description. FIG. 3 shows the calculation of the design variable additional term ÄBG. In addition, the calculation of an interpolated ignition timing ZZPi _{nt is} shown.

There is a first predetermined ignition-time relationship 55 which is embodied here in the form of a characteristic diagram which has values ZZP _t for the ignition time as a function of the rotational speed 35 and the torque 37. Here, the first Zündzeitpunkt- connection 55 is optimized for the lowest possible emissions of the internal combustion engine 3. This first ignition timing relationship 55 is used in particular in stationary states of the internal combustion engine 3. The knocking limit represented by the second relationship 39 preferably relates to the first ignition timing relationship 55 or the ignition timing ZZP provided according to this first ignition timing relationship 55 _! , It is a second predetermined ignition timing relationship 57 is provided, namely again in the form of a map, which values ZZP ₂ for the ignition in

Dependent on the speed 35 and the torque 37 has. In this case, the second ignition-time relationship 57 is in particular a technical limit of

Internal combustion engine 3 tuned towards, preferably to a knock limit of the same, where it has no risk to the internal combustion engine 3 maximum realizable ignition ZZP ₂ . The map for the second ignition timing relationship 57 is preferably determined on a test bench. In any case, the second ignition timing relationship 57 at fixed speed 35 and retained torque 37 comprises ignition points later than the first ignition timing 55.

In the context of the method is in a transient state of the internal combustion engine 3 - in particular at Lastaufschaltung- and speed increase - interpolated in an ignition timing mterpolationsschritt 59 between the ignition ZZPt according to the first Zündzeitpunkt- connection 55 and the ignition ZZP ₂ according to the second Zündzeitpunkt- connection 57. This is done by means of an ignition timing interpolation factor h, which is read out from a second characteristic 61 as a function of the differential rotational speed 43. In this case, the interpolation takes place in particular according to equation (2) given above. From the ignition timing interpolation step 59 results an interpolated value ZZPj _nt for the ignition timing at which the engine 3 is driven in the transient state. This causes in any case an adjustment of the ignition timing to late, causing the

Knock limit of the internal combustion engine 3 is shifted to a richer mixture. It is therefore possible to introduce an additional amount of fuel into the combustion chamber 7. For this purpose, it is preferably provided that the design variable additional term ABG is calculated by a third interpolation step 63, where interpolated here between the determined according to the second context 39 value BG ₂ for the rated size and a determined according to a third context 65 value BG ₃ for the rated size becomes. In this case, the third relationship 65 is likewise embodied as a characteristic diagram which has values BG ₃ for the design variable as a function of the rotational speed 35 and the torque 37. In this case, the characteristic map 65 forms a knock limit of the internal combustion engine 3 at the ignition time ZZP ₂ determined in accordance with the second ignition-time connection 57. In this case, the value BG ₃ determined according to the third context 65 for the design variable is a value that is related to the knock limit in accordance with FIG second ignition timing relationship 57 after retarded ignition ZZP ₂ , preferably by a lambda setpoint.

For the interpolation in the third interpolation step 63, the ignition-timing interpolation factor h determined according to the second characteristic 61 is used here as the scaling factor k, the interpolation being carried out in accordance with the equation (3) given above. The equation of the Zündzeitpunkt- interpolation factor h with the scaling factor k causes an optimal tuning of the dimension ultimately used to control the Eindüseinrichtung 21 with the currently set ignition. Alternatively, however, it is also possible that in the third interpolation step 63 an independent, in particular according to a third characteristic determined scaling factor k.

The design variable additional term ABG resulting from the third interpolation step 63 is fed to the clearing member 47 according to FIG.

Overall, it can be seen that according to the method proposed here and by means of the proposed control device 25, the internal combustion engine 3 can be operated fatter in a transient state with load application and target increase in speed than in a stationary state to provide an increased exhaust gas mass flow for the turbocharger. In this case, in addition, the ignition can be postponed to late to allow additional enrichment of the mixture in the combustion chamber 7. The intended

Interpolation steps cause a softer control on the one hand and on the other hand

Fuel savings and emission reduction. They also cause the additional enrichment is gradually removed again when the actual speed approaches the target speed, the engine 3 is then set stationary again to reduced emissions. It also shows that the internal combustion engine 3 is operated in particular as a variable-speed internal combustion engine or is set up.

Claims

1. A method for operating an internal combustion engine (3) with at least one

Turbocharger (9), where

a combustion chamber of the internal combustion engine (3) in a stationary state a

Fuel quantity is supplied, which is determined in accordance with a first predetermined relationship (31) between a load request to the internal combustion engine (3) and a the combustion chamber (7) to be supplied amount of fuel determining design variable, wherein

a second predetermined relationship (39) between the design variable and the load request is used, wherein

according to the second context (39) a larger amount of fuel is allocated to a given load request than according to the first context (31), wherein the amount of fuel supplied to the combustion chamber (7) in a transient state of the internal combustion engine (3) is based on an interpolated value (BGj _nt ) is determined by an interpolation (41) between one of the first

Context (31) resulting value (BGi) and one from the second

Connection (39) resulting value (BG ₂ ) is determined for the design size.

2. The method according to claim 1, characterized in that the first relationship (31) with regard to reduced emissions of the internal combustion engine (3) is optimized, and / or that the second relationship (39) a knock limit of the internal combustion engine (3) maps.

3. The method according to any one of the preceding claims, characterized in that as first and / or second context (31,39) a characteristic diagram is used in the values for the design variable in dependence on a rotational speed (35) and a torque (37 ) of the internal combustion engine (3) are deposited.

4. The method according to any one of the preceding claims, characterized in that the interpolation (41) is performed depending on a differential speed (43), wherein the differential speed (43) is calculated as the difference between a desired speed and a current actual speed.

5. The method according to any one of the preceding claims, characterized in that a lambda desired value for the internal combustion engine (3) is used as a design variable.

6. The method according to any one of the preceding claims, characterized in that in a transient state of the internal combustion engine (3) an ignition timing by interpolation between a first predetermined ignition timing relationship (55) between a load request to the internal combustion engine (3) and the

Ignition timing is given, and a second predetermined Zündzeitpunkt- connection (57), which is given between the load request and the ignition timing, is retarded, preferably a design size Zusatzterm (ABG) with the interpolated value (BG; _nt ) of the design variable wherein the design variable additional term (ABG) is calculated on the basis of a scaling of a design variable difference value, the design variable difference value being the difference between a value (BG ₃ ) of the design variable resulting from a third predetermined relationship (65) between the

Rated value and the load request is given, and is calculated from the second context (39) resulting value (BG ₂ ) of the design variable, the third context (65) preferably a knock limit of

Internal combustion engine (3) depicts the retarded ignition timing.

7. Control device (25), characterized in that the control device (25)

is set up for carrying out a method according to one of claims 1 to 6.

8. Internal combustion engine (3), characterized by a control device (25) according to

Claim 7.

9. Internal combustion engine (3) according to claim 8, characterized in that the

Internal combustion engine (3) as a gas engine, in particular as a lean-burn gas engine, is formed.

10. Motor vehicle (1), characterized by an internal combustion engine (3) according to any one of claims 8 and 9.