DE19960618A1 - Method to operate internal combustion engine; involves adjusting recycled exhaust flow and exhaust flow through turbine of turbo charger separately - Google Patents

Abstract

The method involves adjusting the recycled exhaust flow and the exhaust flow through the turbine (3) of the turbo charger (2) separately. The actual air flow of intake air or a corresponding parameter is measured and compared with a target value by manipulating the exhaust flow through the turbo charger. The recycled exhaust is manipulated, to obtain the actual pressure ratio of exhaust gas counter pressure (P3,P3') to charge pressure (P2,P2S,P2S') or a correlating parameter and compared with the target value. The actual air flow or a correlating parameter is compared to a target value, and if it is not sufficiently close to the target value, the method is repeated. An Independent claim is included for an internal combustion engine for operation according to the method.

Description

The invention relates to a method for operating a burner Engine and an internal combustion engine for this purpose according to the O The preamble of claim 1 and 9 respectively.

From the publication DE 197 34 494 C1 is an internal combustion engine machine with an exhaust gas turbocharger with variable turbine geometry known. By adjusting one of the variable turbine geo The active door can be assigned to the turbine guide vane leg entry cross-section can be changed, causing the exhaust gas back pressure and thus the power consumption of the turbine how the compressor capacity of the compressor can be adjusted. The internal combustion engine also has a device for exhaust gas recirculation, consisting of a return line between the exhaust line and the intake tract between exhaust gas bolader and internal combustion engine, being in the return line one via a controller unit depending on operating points adjustable exhaust gas recirculation valve of the internal combustion engine is arranged. Depending on speed, operating load etc. the exhaust gas recirculation valve is actuated in the control unit striking control signals generated in such a way that the return exhaust gas mass flow led to an improvement in exhaust gas behavior the internal combustion engine results. For a precise determination of the recirculated actual exhaust gas mass flow is additional the oxygen content directly at the cylinder inlet and at the Zy Linder output of the internal combustion engine taken into account.  

Another internal combustion engine with a device for Ab Gas recirculation is known from DE 44 29 232 C1. The before Direction for exhaust gas recirculation includes an ejector nozzle, which in the charge air line is integrated downstream of the compressor and into which the exhaust gas recirculation line opens. The ejector nozzle is variably designed, by means of a movable nozzle part Both the cross section of the charge air can lead in the nozzle changed nozzle channel and the exhaust gas inlet channel become. The adjustable nozzle part is in a control unit actuating signals depending on the operating condition the internal combustion engine and the operating characteristic of the Exhaust gas turbocharger generated. The nozzle channel through which the drawer air can be fed to the internal combustion engine, has an in Flow direction tapering cross-section, which through the adjustment of the movable nozzle part can be varied can. Depending on the position of the adjustable nozzle part is a different size increase in the flow ge speed of the charge air flowing through. So that one a decrease in the static pressure downstream of the narrowest nozzle cross-section reached, causing the backflow of the exhaust gas mass flow through the device towards Exhaust gas recirculation is supported.

The invention is based on the problem of pollutant emissions in supercharged internal combustion engines with exhaust gas recirculation reduce. Especially when using exhaust gas turbochargers variable turbine geometry should show one possibility the functions of exhaust gas, as in the fired drive bolader and exhaust gas recirculation optimally match each other are to be agreed.

This problem is solved with the features of the independent claims che solved. The dependent claims give preferred further education.  

According to the new method of operating a charged Internal combustion engine with exhaust gas recirculation are both the Rückge led exhaust gas mass flow as well as that through the turbine of the Ab gas turbocharger-guided exhaust gas mass flow set separately. In two successive steps, the air is first mass flow measured and by varying the exhaust gas turbocharger-guided exhaust gas mass flow to a setpoint like. After the actual air mass flow with a predetermined Tolerance has been approximated to the target air mass flow, the returned Ab gas mass flow set in such a way that the pressure ratio nis from exhaust gas back pressure to boost pressure at a setpoint will. After completing the second step, in a third step checks again whether the actual Air mass flow still with sufficient accuracy assigned setpoint. If not the whole process, starting with the first step, run through again.

The third step is a recursion of the method achieved, which ensures that changes in the air mass flow due to a change in exhaust gas back pressure or of the boost pressure are due to the repeated Going through the process sequence are compensated so that the actual air mass flow is set to the setpoint becomes. The change in the exhaust gas mass flow that occurs through the turbine and the changes that may result from it ratio of exhaust gas back pressure to boost pressure can in subsequent second run of the second process step be compensated.

With the recursive method, the mass flows for the Combustion air and the exhaust gas iteratively to the given Setpoints set. Both the setting options th of an actuator in the area of exhaust gas recirculation as  also an actuator in the area of the exhaust gas turbine uses.

The novel internal combustion engine, which is special Suitable way to carry out the novel method is with an exhaust gas turbocharger and a device for exhaust gas return provided with the recirculated exhaust gas mass flow with With the help of a variably adjustable ejector nozzle in the intake tract is to be set. The variable ejector nozzle has a nozzle ka nal for the supply of combustion air, one of the engs th cross section of the nozzle in the bypass bypass, and an exhaust gas inlet duct for the introduction of the recirculated Exhaust gas on. An actuator of the ejector nozzle, which by Sig nals a regulating and control unit is applied, provides the cross sections of the exhaust gas inlet duct, the nozzle duct, see above like the bypass depending on the operating state of the internal combustion engine to a desired size. In particular, all Cross sections in the ejector nozzle with just a single position element set, the common actuator before is designed in such a way that when the Adjusting element in different, especially in opposite set the cross-sections of the exhaust gas inlet duct and nozzle channel can be set.

This design of the ejector nozzle enables that in particular ders simple and quick to perform by an ent speaking positioning of the actuator both the Dü mass airflow flowing through the vertical channel and also via the Exhaust gas recirculation guided exhaust gas mass flow can be set can what a change in both the exhaust back pressure as well the boost pressure and therefore the ratio of exhaust gas back pressure to boost pressure. The internal combustion engine in which the The ejector nozzle described above can be used advantageous according to the method for regulating the air mass flow  and to regulate the recirculated exhaust gas mass flow operate.

In addition, it may also be useful to use the ejector nozzle regardless of the process or Ver use in internal combustion engines, which are with regard to their structure from the above-described internal combustion differentiate machine.

In an expedient development, the adjusting element of the E ejector nozzle or the receptacle for the actuator in the way formed that in at least one position of the actuating element both the exhaust gas inlet duct and the bypass to the nozzle box nal are closed, it may be advantageous to this Extend position to an adjustment tolerance range. With egg ner simultaneous closing of the exhaust gas inlet duct and bypass only the nozzle channel is released. In this version is due to the narrowing of the cross-section in the nozzle channel increased flow velocity with simultaneous pressure drops kung reached.

When the bypass is opened, the total for the flow available cross-section eats, with the result that no over the course of the ejector nozzle ne or only a slight pressure drop in the charge air takes place.

Further advantages and practical designs are the others Claims, the description of the figures and the drawings remove. Show it:

Fig. 1 is a schematic representation of an internal combustion engine with an exhaust gas turbocharger with variable Tur binengeometrie and a device for exhaust gas recirculation,

Fig. 2 shows a process diagram with the basic rate from running short of the regulation of a load placed NEN internal combustion engine with exhaust gas recirculation,

FIGS. 3a-3c respectively functions a section through an ejector nozzle to the nozzle actuator manipulated in various posi,

Fig. 4 shows an ejector nozzle in a further embodiment,

Fig. 5 is a diagram showing the cross-sectional profiles of the nozzle channel, the bypass and the exhaust gas inlet channel in dependence of the position of the nozzle actuating member.

In Fig. 1 illustrated internal combustion engine 1, a plurality of assemblies are associated, in particular a Abgastur turbochargers 2, a device 8 for exhaust gas recirculation, a 9 senstromes flow regulating means for adjusting the internal combustion engine to be supplied to the charge air and the recirculated Abgasmas and a control and control unit 11 , via which the various units of the internal combustion engine are to be controlled or regulated. The exhaust gas turbocharger 2 comprises an exhaust gas turbine 3 , which is equipped with a variable turbine geometry 7 for variable adjustment of the effective turbine cross section, and a compressor 4 for compressing intake combustion air. The arranged in the exhaust line 5 exhaust gas turbine 3 is driven by the exhaust gases standing under the exhaust gas back pressure p ₃ , where at the rotational energy of the charger in the compressor 4 , which is arranged in the intake tract 6 , to compress the combustion air sucked in with ambient pressure p ₁ to an increased boost pressure p _{2 is} used. Downstream of the compressor 4 , a charge air cooler 12 is provided in the intake tract 6 for cooling the compressed air. The cooled in the charge air cooler 12 combustion air occurs with the boost pressure P _2S in the ejector nozzle 10 formed as a flow regulating device 9 , which communicates with the device 8 for exhaust gas recirculation. Via the exhaust gas recirculation device 8 , which comprises a recirculation line 13 with an exhaust gas cooler 14 arranged therein, exhaust gas from the exhaust line 5 with the exhaust gas back pressure p _{3 ′} downstream of the exhaust gas cooler 14 is fed to the flow regulating device 9 , the flow regulating device 9 is designed in such a way that the recirculated exhaust gas mass flow can be set variably. Downstream of the flow regulating device 9 , the charge air, optionally with admixture of exhaust gas, is fed to the internal combustion engine with the boost pressure p _{2S '} .

On the exhaust gas side of the internal combustion engine, the exhaust gas after the exhaust gas turbine 3 has flowed through it is discharged with the residual pressure p ₄ from the exhaust gas line 5 .

The variable turbine geometry 7 of the exhaust gas turbine 3 expediently comprises a turbine guide vane which can either be displaced axially displaceably in the turbine inlet cross section or comprises rotatable guide vanes, the effective turbine inlet cross section being able to be varied by rotating the guide vanes. In addition, there are also other vario turbine types in question, for example flap turbines which have a flood facing the turbine wheel, which can be shut off via a flap, or double-flow, asymmetrically constructed vario turbines, the two flows of which can be controlled via a flap.

If necessary, in addition or alternatively to the variable turbine geometry, a blow-off device 15 with a blow-off valve 17 is provided in a bypass line 16 bridging the turbine 3 .

All adjustable units of the internal combustion engine - the variable turbine geometry 7 of the exhaust gas turbine 3 , the blow-off valve 17 and the flow regulating device 9 - are set as a function of state variables of the internal combustion engine via the regulating and control unit 11 .

The variable turbine geometry and also the blow-off device 15 can be used both in the fired drive operating mode and in the engine braking mode. In order to generate engine braking power, the variable turbine geometry is transferred to the stowed position with a reduced cross section or the exhaust device is closed, whereupon an increased exhaust gas counter pressure p ₃ builds up. By opening brake valves or exhaust valves from the internal combustion engine, the air compressed in the cylinders is pushed out against the high exhaust gas counterpressure p ₃ in the exhaust gas line 5 during engine braking operation. The engine braking power can be varied by setting the variable turbine geometry or the blow-off device.

In FIG. 2, a flow diagram is shown according to which the internal combustion engine is preferably operated. In discrete time steps, engine operating points are determined in accordance with method block 101 , in which state variables the internal combustion engine and possibly also the units to be assigned to the internal combustion engine are supplied to the regulating and control unit. In the regulating and control unit, target values are determined from the state variables, possibly also from stored parameters, which are compared in the control with measured or calculated actual variables.

The following method blocks 102 to 106 represent a first control step in which the actual air mass flow of the intake air is adapted to a given or determined target value. According to method block 102 , the air mass flow at point 1 of the intake air in the intake tract is first measured, in particular the air mass flow after the compression in the compressor of the exhaust gas turbocharger. In the following method block 103 , a query is carried out as to whether the actual air mass flow at point 1 exceeds the target value _l, assigned to the current engine operating point. If this is the case, the yes branch is continued in accordance with method block 104 , according to which the variable turbine geometry VTG is opened further to expand the effective turbine inlet cross section, with the result that the exhaust gas counterpressure drops, so that a lower supercharger output is produced. The lower supercharger output manifests itself in the fact that a lower boost pressure is generated in the intake tract, and accordingly a smaller air mass flow is also supplied to the internal combustion engine.

If query 103 shows that the actual, measured air mass flow _{l is} not greater than the assigned target value _l, the no branching continues to method block 105 and the variable turbine geometry VTG of the exhaust gas turbine is adjusted in the direction of its closed position. The effective turbine inlet cross-section is then reduced, the exhaust gas back pressure increases and consequently the supercharger output, with the result that a higher boost pressure is generated. The higher boost pressure results in a higher air mass flow into the cylinder inlet of the internal combustion engine.

After the opening or closing process of the variable turbine geometry in the process blocks 104 and 105 , the query continues according to process block 106 , in which it is checked whether the actual air mass flow _I manipulated via the variable turbine geometry is accurate enough to the corresponding target value _{l, is supposed to be} approximated. If the amount of the difference between the actual value and the target value falls below a tolerance limit Tol, the air mass flow has been adjusted to the target value with sufficient accuracy and the yes branch is continued in accordance with the following method block 107 . Otherwise, the No branch is returned to method block 102 accordingly, and the entire first control step is run through again.

The process blocks 107 to 111 represent the second control step in which the exhaust gas mass flow recirculated from the exhaust system into the intake tract is set via the exhaust gas recirculation device. According to method block 107 , the required measured quantities are first determined, in the exemplary embodiment the charge pressure p _{2S '} downstream of the flow regulating device and the exhaust gas back pressure p _3' in the exhaust gas recirculation device downstream of the exhaust gas cooler. In the next method block 108 , the query is made as to whether the pressure ratio p _{3 '} / p _2S' from exhaust gas back pressure p _{3 '} to boost pressure p _2S' should exceed an assigned setpoint (p _{3 '} / p _2S' ). If this is the case, the yes branch will proceed according to method block 109 , according to which the exhaust gas recirculation cross section is reduced in the flow regulating device, which is advantageously designed as an ejector nozzle, so that a lower exhaust gas flow is returned to the intake tract. This also reduces the pressure ratio p _{3 '} / p _2S from exhaust gas counterpressure to boost pressure, which is a yardstick for the recirculated exhaust gas mass flow.

If the query in method block 108 shows that the actual pressure ratio is not greater than the corresponding desired value, the no-branch is continued in accordance with method block 110 and the exhaust gas recirculation cross section is increased in the flow regulating device. The increase in cross-section means that a larger proportion of the exhaust gas mass flow is directed into the intake tract, whereupon the actual pressure ratio drops.

After the cross-sectional reduction or cross-sectional enlargement according to the process blocks 109 and 110 , in the next step the process block 111 is queried whether the actual pressure ratio has been approximated with sufficient accuracy to the predetermined target value. If the amount of the difference between the actual pressure ratio and the assigned target value falls below a tolerance limit Tol, the second control step according to the process blocks 107 to 111 is ended; it continues to the process block 112 in accordance with the yes branch. If the required tolerance limit is not undershot, the No branch is returned to method block 107 accordingly, and the entire second control step is run through again.

In the second control step, the pressure ver Ratio of exhaust gas back pressure to boost pressure of both the exhaust gas gene pressure upstream and downstream of the exhaust gas cooler in the Ab gas recirculation device can be used. It is the same possible, the boost pressure in the intake tract upstream of the charge air cooler lers, downstream of the intercooler, but upstream of the through flow regulating device or downstream of the flow To use the regulating device. In addition, it is possible instead of directly determining the pressure ratio ses from exhaust gas back pressure to boost pressure one with the pressure ratio to determine the corresponding size, for example the Cross-sectional geometry in the area of the exhaust gas supply or the air flow in the flow- designed as ejector nozzle Regulator. The cross-sectional geometries are here used as a benchmark for the assigned pressures; demented speaking, the pressure ratio of exhaust gas back pressure to charging print also through a correlating relationship of the cross section geometries are expressed. Beyond that it is also possible to position the actuator in the flow Regulating device as a benchmark for the open cross-sectional geometries  and thus also as a yardstick for the assigned pressures to consider.

The method blocks 112 and 113 represent a third control step in which it is checked again whether the actual air mass flow _{I has} been approximated with sufficient accuracy to the assigned target value. This query is carried out in order to ensure that the conditions in the internal combustion engine after the adaptation of the recirculated exhaust gas mass flow in the second control step in accordance with process blocks 107 to 111 have not changed to such an extent that the actual air mass flow of the intake air changes in an impermissible manner from the has removed the first control step in accordance with method blocks 102 to 106 determined target value. The variation of the recirculated exhaust gas mass flow in the second control step has an influence on the pressure conditions, in particular on the exhaust gas back pressure and the charging pressure, which can lead to a changed actual air mass flow of the intake air.

After the measurement of the air mass flow in method block 112, the accuracy query in method block 113 with regard to the air mass flow _I leads to the result that the actual air mass flow has moved in an impermissible manner from the predetermined setpoint value, in accordance with the no-branching to the first control step, in particular returned to query according to method block 103 . In this case, the entire procedure is repeated. If, on the other hand, the query in method block 113 leads to the result that the air mass flow is still approximated with sufficient accuracy to the given target value, the regulation for this cycle has ended, and the yes branch is returned to the first method block 101 and run through the entire procedure again in a new cycle, taking into account changed engine operating points.

Within the iteration phases is usually common change the operating point. This is about the changes in the Setpoints for the air flow and the exhaust gas to be mixed must be taken into account at all times in the iteration process.

As an alternative to measuring the air mass flow of the intake air in the first control step, which by means of an air mass meter is carried out, a kor with the air mass flow Relative size measured and the regulation in the first regulation step as a basis. For example, it can also the boost pressure or charge air temperature is measured and the on position of the variable turbine geometry the.

Alternatively or in addition to the cross-section setting via the variable turbine geometry can also be another facility to manipulate the exhaust gas mass flow in the exhaust line are pulled, in particular a blow-off device, over the the exhaust gas can be discharged directly into the atmosphere.

FIGS. 3a to 3c show an ejector nozzle designed as a flow regulator, the control element to SET development of the cross sections of the exhaust gas inlet duct of the nozzle passage and the bypass in three different positions shown is.

The ejector nozzle 10 has an approximately ring-shaped housing 18 , which includes a central nozzle channel 19 , through which combustion air flows in the direction of the arrow 25 . In the nozzle channel 19 , a guide body 20 is introduced, which has an aerodynamically contoured shape and reduces the flow cross section in the nozzle channel 19 to a minimum. In the further course, the flow cross section of the nozzle channel 19 expands to a diffuser, whereby a venturi-like effect is achieved in the nozzle channel 19 , in which a higher flow speed is achieved in the area of the narrowest flow cross section and at the same time downstream of the guide body 20 the stationary pressure is lowered.

An annular bypass 22 is introduced into the housing 18 and surrounds the nozzle channel 19 in an annular manner. The bypass bridges the area of the narrowest flow cross section in the nozzle channel 19 ; the bypass branches off from the nozzle channel 19 immediately upstream of the narrowest flow cross section.

The ejector nozzle 10 also has a connecting piece 23 for connecting an exhaust gas recirculation line of an exhaust gas recirculation device. The connecting piece 23 extends radially to the longitudinal axis 26 of the ejector nozzle 10 . At the connecting piece 23 opens into an exhaust gas inlet channel 24 , which communicates with the nozzle channel 19 in an open position of the actuating element 21 of the ejector nozzle 10 . The exhaust gas inlet channel 24 opens into the narrowest cross section of the nozzle channel 19 .

The control element 21 of the ejector 10 is designed as an axially displaceable in the direction of the longitudinal axis 26 adjusting sleeve which is introduced into the nozzle channel 19 and is aerodynamically shaped on its ra dial inner side, in particular in the longitudinal direction has a tapered profile. The actuator 21 takes in Fig. 3a, an axial center position, from which a shift in both axial directions is possible. In the central position according to FIG. 3a, the control element 21 closes both the branching of the by pass 22 from the nozzle channel 19 and the outlet opening of the exhaust gas inlet channel 24 into the nozzle channel 19 further downstream, so that in the central position of the control element 21 no exhaust gas flows through the Connection piece 23 and the exhaust gas inlet channel 24 can flow into the nozzle channel 19 and, moreover, no combustion air from the nozzle channel 19 into the bypass 22 can be sent. In the middle position of FIG. 3a shows the E has jektordüse 10, the action of a venturi. The adjustment element 21 is adjusted in accordance with the control signals generated in a regulating and control unit as a function of current state variables and parameters of the internal combustion engine.

In Fig. 3b, the actuating member 21 is displaced axially in flow direction according to arrow direction 25, is enabled thereby the diversion to the bypass 22nd Accordingly, a partial flow of the combustion air flowing through the nozzle channel 19 is guided into the ring-encompassing bypass 22 and is guided in the arrow direction 27 parallel to the nozzle channel 19 through the ejector nozzle 10 . In the first open position according to FIG. 3b, only the branch to the bypass 22 is opened, at the same time the mouth of the exhaust gas inlet duct 24 in the nozzle duct 19 is closed by the actuating element 21 . The displacement of the actuating element 21 has a cross-sectional expansion in the nozzle channel 19 , because on the one hand an additional cross-section is released in the region of the branching of the bypass 22 and on the other hand the tapering section of the actuating element 21 is inserted into a receptacle of the gas inlet channel 24 is and now a portion of the actuating element 21 with a larger inner diameter surrounds the Leitkör by 20 radially. This first open position of the actuating element 21 , in which the supply of exhaust gas is prevented, is particularly suitable for transient conditions of the internal combustion engine, in which a high proportion of oxygen is required for increased power generation in the engine. The large flow cross-sections ensure the desired low flow losses.

In Fig. 3c, the control element 21 is shown in its second open position, in which the branch of the bypass 22 closed ver, but at the same time the mouth of the exhaust gas inlet channel 24 is open in the nozzle channel 19 , so that exhaust gas, which via the exhaust gas recirculation Device is passed into the connecting piece 23 and further into the exhaust gas inlet duct 24 , can flow into the nozzle duct 19 in the region of the narrowest flow cross section according to arrow direction 28 . Since there is a reduced pressure downstream of the narrowest cross section in the nozzle channel 19 due to the Venturi effect, the inflow of exhaust gas is supported via the exhaust gas recirculation. The range of applications for exhaust gas recirculation is being expanded, as a pressure drop between the exhaust system and the intake tract can now be used to recirculate exhaust gas over larger operating areas of the internal combustion engine.

The exhaust gas recirculation quantity becomes the air flow under a swirl led, which ensures a favorable mixing of air and exhaust gas arises. Secondly, swirl flow expands to the following Diffuser flow with regard to a reduced tendency to detach the Flow out. In general, the swirl design of the Abga ses the overall length of the diffuser are reduced, which is among the Space can bring a big advantage.

In a preferred embodiment, the cross-sectional ratio of exhaust gas inlet duct 24 to nozzle duct 19 is a maximum of ten, while the cross-sectional ratio of bypass 22 to nozzle duct 19 is advantageously a maximum of five.

Fig. 4 shows an ejector 10 in a modified Ausfüh tion, the same components with the same reference numerals as in Fig. 3a to 3c are provided. The axial adjustment of the actuating element 21 in the Dusseldorf channel 19 is carried out by means of a rotary ring 29 which is arranged on the outside of the housing 18 coaxially to the longitudinal axis 26 . The rotary ring 29 has on its radially inner side a helically wound groove into which a transmission pin 30 , which is fixedly connected to the actuating element 21 , projects. At least two transmission pins are expediently provided on opposite sides, which engage in corresponding grooves of the rotary ring in order to achieve a uniform force distribution. When the rotary ring 29 rotates, the transmission pins 30 move along the groove on the radially inner side of the rotary ring; due to the helical structure of the groove, this has a component pointing in the axial direction, so that the transmission pin 30 and thus also the actuating element 21 also undergo an axial displacement in addition to a rotary movement, via which the actuating element 21 between its open and closed positions is adjusted.

Fig. 5 shows a diagram with the cross-sectional areas A of the nozzle channel, the exhaust gas inlet channel and the bypass as a function of the axial position x _{D of} the actuating element. The actuating element can, as also shown in Fig. 3a, be adjusted axially in both directions, the central position of the actuating element being designated with x _D = 0 and a deflection against the flow direction of the combustion air with a positive sign, a deflection in the direction of the flow the combustion air, on the other hand, is designated with a negative sign. In the central position of the actuating element shown in FIG. 3a, the displacement x _{D of} the actuating element is zero; Both the cross-section A _AGR in the mouth of the exhaust gas inlet duct into the nozzle duct and the branch cross-section A _bypass in the region of the branch of the bypass from the nozzle duct are zero. The nozzle cross-section is at an intermediate level between the minimum and maximum possible nozzle cross-section.

With an axial displacement of the control element in the negative direction - in the direction of the flow of the combustion air - the control element assumes the first open position shown in FIG. 3b, in which the exhaust gas inlet channel is still closed but the bypass is open. The diagram according to FIG. 5 shows that when the actuating element is displaced in the negative direction, the branch cross section A _{bypass of} the bypass increases sharply, the mouth cross section of the exhaust gas inlet duct remains closed in the entire negative adjustment range of the actuating element. At the same time, with increasing adjustment of the adjusting element in the negative direction, the nozzle cross section A _{nozzle increases} to a maximum A _{nozzle, mx} , which is reached in the axial end position of the adjusting element.

With an adjustment in the positive direction, the mouth cross section A _{EGR of} the exhaust gas inlet channel increases continuously to a maximum, which is reached in the axial, positive end position - the position shown in FIG. 3c - of the actuating element. The bypass cross-section remains closed, the nozzle cross-section continuously decreases to a minimum due to the smaller free inner cross-section of the control element.

It can be expedient to provide a tolerance range Tol with which an area is designated within which the cross cuts both the exhaust gas inlet duct and the bypass in the Mouth or branch area to the nozzle channel closed stay. The tolerance range that is placed around the zero point is and advantageously a maximum of 5%, in particular a maximum of 0.5% of the Total adjustment range is to ensure that too in the event of manufacturing inaccuracies or expansion as a result of heating or wear at least a central position of the control element tes exists in which both the exhaust gas inlet duct as well the bypass is closed.

Claims (17)

1. A method of operating an internal combustion engine with a gas turbocharger and a device for exhaust gas recirculation, the recirculated exhaust gas mass flow and the exhaust gas mass flow guided through the turbine ( 3 ) of the exhaust gas turbocharger ( 2 ) being separately adjustable, wherein

• - In a first step, the actual air mass flow of the intake air or a variable correlating with the actual air mass flow is measured and adapted to an assigned setpoint by manipulating the exhaust gas mass flow guided by the exhaust gas turbocharger ( 2 ),
• in a second step, the recirculated exhaust gas mass flow is manipulated in such a way that the actual pressure ratio of exhaust gas counterpressure to boost pressure or a variable correlating with this actual pressure ratio is adjusted to an assigned target value,
• - In a third step, it is checked whether the actual air mass flow or a correcting quantity with the actual air mass flow corresponds with sufficient accuracy to the assigned target value, and in the event of an impermissible deviation, the first step is returned.

2. The method according to claim 1, characterized in that an exhaust gas turbine ( 3 ) with variable turbine geometry ( 7 ) is used, the actual air mass flow being adjusted by manipulation of the variable turbine geometry ( 7 ). 3. The method according to claim 1 or 2, characterized in that the exhaust gas turbine ( 3 ) has an adjustable relief valve ( 17 ). 4. The method according to any one of claims 1 to 3, characterized in that the recirculated exhaust gas mass flow is adjusted to the setpoint by setting a variable ejector nozzle ( 10 ) in the intake tract ( 6 ), which has a supply for the recirculated exhaust gas. 5. The method according to any one of claims 1 to 4, characterized, that the actual air mass flow via an air mass meter is true. 6. The method according to any one of claims 1 to 5, characterized, that as the quantity correlating with the actual air mass flow Boost pressure is measured. 7. The method according to any one of claims 1 to 6, characterized, that as the quantity correlating with the actual air mass flow Charge air temperature is measured.   8. The method according to any one of claims 1 to 7, characterized in that the position of the actuating element ( 21 ) of the ejector nozzle ( 10 ) is determined as the quantity correlating with the actual pressure ratio of exhaust gas counterpressure to charge pressure. 9. Internal combustion engine, in particular for carrying out the method according to one of claims 1 to 8, with an exhaust gas turbocharger ( 2 ) and a device ( 8 ) for exhaust gas recirculation and with a variable ejector nozzle ( 10 ) in the intake tract ( 6 ) which an exhaust gas -Inlet channel ( 24 ) for an exhaust gas recirculation line ( 13 ) and a bypass ( 22 ) to its nozzle channel ( 19 ), the cross sections (A _EGR , A _nozzle , A _bypass ) of the exhaust gas inlet channel ( 24 ), the nozzle channel ( 19 ) and the bypass ( 22 ) are adjustable via an adjusting element ( 21 ) of the ejector nozzle ( 10 ), and with a regulating and control unit ( 11 ) for generating actuating signals depending on the operating state of the internal combustion engine ( 1 ), characterized that a common adjusting element ( 21 ) for setting the cross sections (A _EGR , A _nozzle , A _bypass ) of the exhaust gas inlet duct ( 24 ), the nozzle duct ( 19 ) and the bypass ( 22 ) of the ejector nozzle ( 10 ) is provided and that the cross sections (A _EGR , A _nozzle ) of the exhaust gas inlet duct ( 24 ) and nozzle duct ( 19 ) can be adjusted by moving the adjusting element ( 21 ) in different directions. 10. Internal combustion engine according to claim 9, characterized in that the adjusting element ( 21 ) is designed in such a way that the exhaust gas inlet channel ( 24 ) and the bypass ( 22 ) are closed in one position of the adjusting element ( 21 ). 11. Internal combustion engine according to claim 10, characterized in that both the exhaust gas inlet duct ( 24 ) and the by pass ( 22 ) are closed within an adjustment tolerance range of the adjusting element ( 21 ). 12. Internal combustion engine according to one of claims 9 to 11, characterized in that when the actuating element ( 21 ) is adjusted to open the exhaust gas inlet channel ( 24 ), the bypass ( 22 ) is simultaneously closed or remains closed. 13. Internal combustion engine according to one of claims 9 to 12, characterized in that the adjusting element ( 21 ) is a nozzle sleeve ( 19 ) encompassing, axially displaceable adjusting sleeve. 14. Internal combustion engine according to one of claims 9 to 13, characterized in that the cross-sectional ratio of the exhaust gas inlet duct ( 24 ) to the nozzle duct ( 19 ) is a maximum of ten. 15. Internal combustion engine according to one of claims 9 to 14, characterized in that the cross-sectional ratio of bypass ( 22 ) to the nozzle channel ( 19 ) is a maximum of five. 16. Internal combustion engine according to one of claims 9 to 15, characterized in that the exhaust gas mass flow guided through the exhaust gas turbine ( 3 ) of the exhaust gas turbocharger ( 2 ) is variably adjustable. 17. Internal combustion engine according to claim 16, characterized in that the exhaust gas turbine ( 3 ) has a variably adjustable turbine geometry ( 7 ) for setting the effective turbine cross section.