Internal combustion engine and method for simultaneously regulating exhaust gas temperature and supercharging pressure of internal combustion engine

Abstract

To provide an internal combustion engine enabling quick regulation of the exhaust gas temperature while minimizing the efficiency loss of the internal combustion engine.SOLUTION: The invention provides 1. an internal combustion engine and a method for simultaneously regulating the exhaust gas temperature and the supercharging pressure of an internal combustion engine, and 2. an internal combustion engine that includes: an exhaust gas turbocharger (17) that includes a turbine (19) situated in an exhaust duct (8), and a compressor (18) situated in an intake duct (4); a bypass valve (13) via which at least a portion of an exhaust gas mass flow of the internal combustion engine may be led past the turbine (19); and an exhaust gas flap (15) situated in the exhaust duct (8), downstream from the turbine (19) and the bypass valve (13).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine and a method for simultaneously controlling exhaust temperature and boost pressure of the internal combustion engine. [Background technology]

[0002] Internal combustion engines, especially diesel engines, emit harmful exhaust gases, especially nitrogen oxides and soot particles, and in recent years the limits on the maximum permissible emissions have become stricter worldwide. Therefore, to reduce emissions from internal combustion engines, they are routinely fitted with systems for exhaust gas aftertreatment. In particular, exhaust gas aftertreatment systems can include a particle filter to remove soot particles and an SCR catalytic converter (SCR, Selective Catalytic Reduction) to remove nitrogen oxides.

[0003] Both the particulate filter and the SCR catalytic converter function at specific operating temperatures. The temperature of these components is primarily determined by the temperature of the exhaust gases delivered by the engine.

[0004] [Patent document 1] (German patent publication no. DE 10 2005 004 880 B4) describes a method for controlling the exhaust gas temperature of an internal combustion engine, in which, when a predefined maximum exhaust gas temperature in the mixture is exceeded, the combustion air ratio is reduced stepwise, either continuously or in several steps, down to a lower limit value, and, when the limit value is reached, the cylinder charge is reduced stepwise, either continuously or in several steps. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent Publication No. DE 10 2005 004 880 B4 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to provide an internal combustion engine which allows for rapid adjustment of exhaust gas temperature with minimal loss of efficiency of the engine. It is yet another object of the present invention to provide a method for simultaneously controlling exhaust gas temperature and boost pressure of an internal combustion engine, thereby allowing the engine to be regulated efficiently and quickly. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides an internal combustion engine comprising an exhaust gas turbocharger having a turbine arranged in the exhaust passage and a compressor arranged in the intake passage, a bypass valve for passing at least a part of the exhaust gases of the internal combustion engine through the turbine, and an exhaust flap arranged in the exhaust gas duct downstream of the turbine and the bypass valve.

[0008] An internal combustion engine has two actuators in the exhaust gas duct that can be used to regulate the exhaust gas temperature. The first actuator is the exhaust flap. Closing this flap creates a flow resistance of the exhaust gas flowing in the exhaust duct, which increases the exhaust gas back pressure. As a result, the performance of the exhaust gas turbocharger compressor is reduced and the exhaust gas flow rate is reduced. This reduces the boost pressure supplied to the intake port. The reduced boost pressure means that less fresh air flows through the internal combustion engine. Therefore, the energy of the fuel burned in the combustion chamber of the internal combustion engine is distributed to fewer gases, resulting in a higher exhaust gas temperature. Also, when the exhaust flap closes, the exhaust back pressure in the exhaust duct immediately after the combustion chamber of the internal combustion engine increases. Therefore, the closing of the exhaust gas valve leads to a reduction in the boost pressure together with an increase in the exhaust gas back pressure, which results in an increase in the gas exchange losses of the internal combustion engine and a decrease in the efficiency of the internal combustion engine. That is, the exhaust gas temperature can be regulated only by the exhaust gas flap, but closing the exhaust gas flap significantly reduces the efficiency.

[0009] The second actuator is the bypass valve, via which the boost pressure provided by the compressor in the intake port can be primarily regulated. Opening this bypass valve increases the proportion of exhaust gas passing through the turbine of the exhaust gas turbocharger, reducing the compressor's power output. This leads to a reduction in boost pressure, which, as mentioned above, leads to an increase in exhaust gas temperature. Closing the bypass valve has the opposite effect.

[0010] The internal combustion engine according to the invention has the advantage that the desired exhaust gas temperature can be adjusted mainly via the bypass valve up to the variable limit value of the exhaust gas temperature without the internal combustion engine suffering significant efficiency losses. Only if the desired exhaust gas temperature is then exceeded, the exhaust gas flap can also be used to adjust the exhaust gas temperature, at the expense of efficiency losses of the internal combustion engine, as well as the variable limit value of the exhaust gas temperature which can be adjusted by the bypass valve.

[0011] In one possible embodiment of the invention, the internal combustion engine can be designed as a diesel internal combustion engine.

[0012] In one possible embodiment of the internal combustion engine, the exhaust gas duct can include an exhaust gas aftertreatment system. In particular, the exhaust gas aftertreatment system can include all known exhaust gas cleaning systems. In particular, the exhaust gas cleaning system can be based on chemical processes. For example, the exhaust gas aftertreatment system can include a particulate filter and / or a catalytic converter based on selective catalytic reduction of the exhaust gases (SCR catalytic converter).

[0013] In yet another possible embodiment of the inventive internal combustion engine, the intake channel and the exhaust gas channel can be fluidly connected to one another only via a combustion chamber of the internal combustion engine, in which case there is, for example, no exhaust gas recirculation.

[0014] In order to solve the above problems, the present invention proposes a method for simultaneously controlling the exhaust gas temperature and the boost pressure of an internal combustion engine, in particular of the above-mentioned type of internal combustion engine, which method comprises the following steps: determining an actual boost pressure, determining an actual exhaust gas temperature, determining a target boost pressure, determining a target exhaust gas temperature range, simultaneously determining an operation amount of a bypass valve that allows at least a part of the exhaust gas mass flow of the internal combustion engine to pass through a turbine of an exhaust gas turbocharger and an operation amount of an exhaust flap by a nonlinear model predictive controller according to the actual boost pressure, the actual exhaust gas temperature, the target boost pressure and the target exhaust gas temperature range, and adjusting the operation amount of the bypass valve and the operation amount of the exhaust flap.

[0015] In addition to exhaust gas temperature, which is regulated primarily for the functioning of the exhaust gas aftertreatment system, another control variable that is controlled to essentially optimize the efficiency of the internal combustion engine is boost pressure.

[0016] As already mentioned, both the bypass valve and the exhaust gas flap simultaneously affect the control variables exhaust gas temperature and boost pressure, and are therefore multivariable systems that are mutually coupled, so it is not possible to adjust one of the two control variables without simultaneously changing the other one, and the two control variables largely have conflicting purposes.

[0017] The method of the present invention has the advantage that it overcomes the above-mentioned conflicting objectives by determining a target exhaust gas temperature range rather than a specific target exhaust gas temperature, and by making appropriate adjustments depending on the target exhaust gas temperature range, thereby allowing simultaneous control of exhaust temperature and boost pressure.

[0018] In one possible embodiment of the method of the invention, a non-linear model predictive controller is able to predict the boost pressure at one or more subsequent times as a function of the bypass valve actuation and the exhaust gas flap actuation.

[0019] The nonlinear model predictive controller is capable of predicting the exhaust gas temperature at one or more subsequent times as a function of the bypass valve actuation and the exhaust gas flap actuation.

[0020] The nonlinear model predictive controller can minimize a merit function, where the merit function is a function of the difference between a target boost pressure and a predicted boost pressure at one or more downstream time points and / or the difference between a target exhaust gas temperature range and a predicted exhaust gas temperature at one or more subsequent time points. If the predicted exhaust temperature is within the target exhaust temperature range, the difference between the target exhaust temperature range and the predicted exhaust temperature is zero. The quality function is also referred to as a cost function or quality function.

[0021] In a further refinement of the method, the nonlinear model predictive controller can predict the boost pressure for a prediction period as a function of the bypass valve actuation amount and the exhaust gas flap actuation amount. The nonlinear model predictive controller can predict the exhaust gas temperature for a prediction range depending on the bypass valve actuation amount and the exhaust gas flap actuation amount. If the predicted exhaust temperature is within the target exhaust temperature range, the difference between the target exhaust temperature range and the predicted exhaust temperature is zero. The prediction range extends in time from a start time tS to an end time tS+T. The duration of the prediction horizon is T. The actual time t0 can be selected as the start time tS. The prediction range can include one or more downstream time points mentioned above.

[0022] In the above case, the nonlinear model predictive controller can minimize a merit function as a function of the difference between the desired boost pressure and the predicted boost pressure within the prediction time period and / or the difference between the target exhaust gas temperature range and the predicted exhaust gas temperature within the prediction time period. The merit function can be an integral function of the difference between the desired boost pressure and the predicted boost pressure over the prediction time period and / or an integral function of the difference between the target exhaust gas temperature range and the predicted exhaust gas temperature over the prediction time period.

[0023] In one possible embodiment of the invention, the nonlinear model predictive controller is capable of minimizing a merit function taking into account at least one secondary condition, in particular the maximum speed of an exhaust gas turbocharger of the internal combustion engine, the maximum exhaust back pressure of the internal combustion engine, the maximum exhaust gas temperature in an exhaust gas duct of the internal combustion engine, the maximum exhaust gas temperature at a turbine of an exhaust gas turbocharger of the internal combustion engine, the minimum fuel-air ratio in a combustion chamber of the internal combustion engine, the maximum actuation amount of an exhaust flap as at least one secondary condition.

[0024] The amount of operation of the exhaust gas flap can take a value between the maximum amount of operation at which the exhaust gas flap is fully closed and the minimum amount of operation at which the exhaust gas flap is fully opened, and is set to this value.

[0025] The maximum exhaust flap operation can be determined as a function of the predicted exhaust gas temperature, and if the predicted exhaust temperature is below the target exhaust temperature range, the maximum exhaust flap operation can be set to a maximum exhaust flap closure.

[0026] Alternatively or in combination therewith, the maximum amount of exhaust flap manipulation can be set to a minimum amount of movement at which the exhaust flap is opened to the maximum when the predicted exhaust gas temperature is equal to or greater than the target exhaust gas temperature range, or the maximum amount of exhaust flap manipulation can be set to a value between the maximum amount of movement and the minimum amount of movement when the predicted exhaust temperature is equal to or greater than the target exhaust gas temperature range, the difference between the predicted exhaust gas temperature and the target minimum exhaust gas temperature of the exhaust gas temperature range decreasing continuously in value with increasing in the direction of the minimum amount of movement.

[0027] The amount of operation of the bypass valve can take or be set to a value between a minimum amount of operation where the bypass valve is fully closed and a maximum amount of operation where the bypass valve is fully open.

[0028] In one possible embodiment of the invention, a target minimum exhaust gas temperature of the exhaust gas temperature range can be determined to determine the target exhaust gas temperature range. The target exhaust gas temperature range is limited to an exhaust gas temperature value that is smaller than the target minimum exhaust gas temperature. The exhaust gas temperature range can therefore be referred to as an opening interval that is too large for the exhaust gas temperature value.

[0029] In order to determine the target minimum exhaust gas temperature of the exhaust gas temperature range, a minimum temperature of a particulate filter of the internal combustion engine can be determined. In particular, the minimum temperature of the particulate filter can be determined as a function of the actual temperature of the particulate filter. The actual temperature of the particulate filter can be measured using a temperature sensor. Alternatively or in combination therewith, the minimum temperature of the particulate filter can be determined as a function of the actual soot content of the particulate filter. The actual soot content of the particulate filter can be measured or determined in a manner known to the person skilled in the art.

[0030] To determine the target minimum exhaust gas temperature of the exhaust gas temperature range, a minimum temperature of the SCR catalytic converter of the internal combustion engine can be determined. In particular, the minimum temperature of the SCR catalytic converter of the internal combustion engine can be determined as a function of the ammonia load of the SCR catalytic converter. The ammonia load of the SCR catalytic converter can be measured or determined by methods known to those skilled in the art.

[0031] In order to determine the target minimum exhaust gas temperature of the exhaust gas temperature range, the maximum temperature of the SCR catalytic converter of the internal combustion engine can be determined. In particular, the maximum temperature of the SCR catalytic converter of the internal combustion engine can be determined as a function of the actual temperature of the SCR catalytic converter and / or the maximum temperature gradient of the SCR catalytic converter over time. Ammonia slip can be avoided by limiting the temperature gradient of the SCR catalytic converter to a maximum value. The temperature of the SCR catalytic converter can be measured using a temperature sensor.

[0032] A minimum temperature of the SCR metering system of the internal combustion engine can be determined to determine a target minimum exhaust gas temperature of an exhaust gas temperature range. In particular, the minimum temperature of the SCR metering system of the internal combustion engine can be determined as a function of a required reductant mass flow rate of the SCR metering system. The required reductant mass flow rate of the SCR dosing system is also referred to as a target reductant mass flow rate.

[0033] The target minimum exhaust gas temperature of the exhaust gas temperature range can be determined by comparing the maximum of the minimum temperature of the particulate filter of the internal combustion engine, the minimum temperature of the SCR catalytic converter of the internal combustion engine, and the minimum temperature of the SCR dosing system of the internal combustion engine. If necessary, the target minimum exhaust gas temperature of the exhaust gas temperature range can be set to a minimum value compared to the maximum temperature of the SCR catalytic converter of the internal combustion engine.

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an internal combustion engine according to the present invention and an embodiment of a method for simultaneously controlling the exhaust gas temperature and the boost pressure of an internal combustion engine will now be described with reference to the drawings. [Brief description of the drawings]

[0035] [Figure 1] 1 is a schematic diagram of an internal combustion engine according to the present invention; [Diagram 2] 2 illustrates a method according to the present invention for simultaneously controlling exhaust gas temperature and boost pressure in the internal combustion engine of FIG. 1; [Diagram 3] 4 is a graph for calculating the maximum operation amount ζ_AK_max of the exhaust flap. [Figure 4] FIG. 2 is a diagram of a control circuit implemented in the internal combustion engine of FIG. 1; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] [Figure 1] shows an internal combustion engine 1 according to the invention, in which a fuel mass flow rate W_F is converted into mechanical power P_mech. A crankcase 2 of the internal combustion engine 1 comprises, in a known manner, a number of combustion chambers 3 in which fuel is combusted. In the case of the figure, the internal combustion engine 1 has four combustion chambers 3.

[0037] The internal combustion engine 1 comprises an intake duct 4 which supplies fresh air to the individual combustion chambers 3 for fuel combustion. The intake duct 4 branches off from a central passage in the region of an intake manifold 5 into four individual streams, each connected to a combustion chamber 3.

[0038] A compressor 18 of an exhaust turbocharger 17 is arranged in the intake duct 4. Charge air from an environment having an atmospheric pressure P_O and an ambient temperature T_O is drawn in through the compressor 18 and compressed. The atmospheric pressure P_O is measured by an atmospheric pressure sensor and the ambient temperature T_O is measured by an ambient temperature sensor. The pressure of the charge air immediately downstream of the compressor 18 has a value P_18 and the temperature of the charge air has a value T_18.

[0039] Also arranged in the intake duct 4 downstream of the compressor 18 is a charge air cooler 7, by means of which the charge air can be cooled in a known manner.

[0040] In the region immediately preceding the intake manifold 5 there is a measuring point 6 at the intake port 4, where the boost pressure P_6 is determined using a boost pressure sensor, the charge air temperature T_6 is determined using a charge air temperature sensor and the mass flow rate W_ein of fresh air is supplied to the intake manifold 5.

[0041] The combustion chamber 1 has an exhaust gas duct 8 capable of discharging a mass flow rate W_aus of exhaust gas generated as a result of fuel combustion in the combustion chamber 3. The exhaust gas duct 8 has an exhaust manifold 9, and each flow connected to each combustion chamber 3 is gathered to form a central duct.

[0042] In the area immediately following the exhaust manifold 9, the exhaust gas duct 8 has a measuring point 10 in the central duct, at which the exhaust gas pressure P_10 can be measured by a first exhaust gas pressure sensor and the exhaust gas temperature T_10 can be measured by a first exhaust gas temperature sensor. The exhaust pressure P_10 is also called exhaust back pressure. The exhaust gas temperature T_10 can also be determined indirectly using other measured values ​​by situation monitoring devices.

[0043] The exhaust gas duct 8 branches into a turbine duct 11 and a bypass duct 12 downstream of the measurement point 10. Therefore, the mass flow rate W_aus of the exhaust gas is divided into the turbine duct 11 and the bypass duct 12, the exhaust gas mass flow rate W_T flows through the turbine duct 11, and the exhaust gas mass flow rate W_WG flows through the bypass duct 12.

[0044] A turbine 19 of the exhaust turbocharger 17 is arranged in the turbine duct 11, which turbine 19 is connected via a shaft 20 to a compressor 18. The turbine 19 extracts energy from the exhaust gas mass flow W_aus in a known manner in order to drive the compressor 18 via the shaft 20. The speed n_17 of the shaft 20 can be simulated using the above-mentioned condition monitoring device or can also be measured using a speed sensor.

[0045] The pressure of the exhaust gas mass flow W_T through the turbine passage 11 immediately after the turbine 19 has a value P_19, and the temperature of the exhaust gas mass flow W_T through the turbine passage 11 has a value T_19.

[0046] A bypass valve 13 is arranged in the bypass passage 12. This bypass valve 13 is also called a wastegate. The bypass valve 13 can be continuously adjusted between a closed position, also called a minimum operating manipulated variable, in which the bypass valve 13 is closed to the maximum, and an open position, in which the bypass valve 13 is open to the maximum. The maximum opening can also be called a maximum value. Each manipulated variable of the bypass valve 13 is called a bypass valve position ζ_WG. The mass flow rate W_WG of the exhaust gas flowing through the bypass passage 12 can be adjusted by opening and closing the bypass valve 13. In other words, the proportion of the exhaust gas mass flow rate W_aus flowing through the bypass passage 12 can be adjusted by opening and closing the bypass valve 13. The bypass valve position ζ_WG is measured by a bypass valve position sensor, for example a rotation angle sensor.

[0047] The pressure of the exhaust gas mass flow rate W_WG flowing through the bypass passage 12 immediately after the bypass valve 13 is a value P_13, and the temperature of the exhaust gas mass flow rate W_WG flowing through the bypass passage 12 is a value T_13.

[0048] Downstream of the turbine 19 and downstream of the bypass valve 13, the turbine passage 11 and the bypass passage 12 join at a collection point 14. Downstream of the collection point 14 in the exhaust gas duct 8, an exhaust gas flap 15 is arranged. This exhaust gas flap 15 can be continuously adjusted between a closed position, also called maximum operating variable, in which the exhaust gas flap 15 is closed to the maximum, and an open position, also called minimum operating variable, in which the exhaust gas flap 15 is opened to the maximum. The respective operating variable of the exhaust gas flap 15 is called the exhaust gas flap position ζ_AK. This exhaust gas flap position ζ_AK is measured by an exhaust gas flap position sensor, for example a rotation angle sensor.

[0049] In the area immediately before (upstream) the exhaust flap 15 the exhaust gas mass flow has a pressure value P_15', which is determined by a second exhaust gas pressure sensor or simulated by the situation monitoring device, and a temperature value T_15', which is measured by a second exhaust gas temperature sensor.

[0050] The exhaust gas mass flow in the area immediately behind (downstream) the exhaust gas flap 15 has a pressure value P_15 determined by a third exhaust gas pressure sensor or simulated by the situation monitoring device and a temperature value T_15 measured by a third exhaust gas temperature sensor.

[0051] The second exhaust pressure sensor and the third exhaust pressure sensor may be used in combination or alternately. The second exhaust gas temperature sensor and the third exhaust gas temperature sensor may also be used in combination or alternatively.

[0052] In this case, an exhaust gas aftertreatment device 16 is arranged downstream of the exhaust gas flap 15. This device comprises a particle filter 24 which purifies the mass flow of exhaust gas particles, in particular soot particles, in a known manner. The temperature T_24 of this particle filter 24 is measured by a particle filter temperature sensor or simulated by means of a suitable temperature model.

[0053] Furthermore, the exhaust gas aftertreatment device 16 includes an SCR catalytic converter 26 which purifies the exhaust gas mass flow of nitrogen oxides in a known manner by selective catalytic reduction. The temperature T_26 of this SCR catalytic converter 26 is measured by a catalytic converter temperature sensor or simulated by means of a suitable temperature model.

[0054] Between the particle filter 24 and the SCR catalytic converter 26 an SCR dosing system 25 is arranged, by means of which ammonia, for example in the form of urea, can be dosed into the exhaust gas duct 8 or into the SCR catalytic converter 26. The temperature T_25 of this SCR dosing system 25 is measured by a dosing system temperature sensor or simulated by means of a suitable temperature model.

[0055] The internal combustion engine 1 comprises a control unit 21 (also called a computer), by means of which the internal combustion engine 1 can be controlled. This control unit 21 is designed to detect a state vector χ of the internal combustion engine 1. This state vector χ can include one or more values ​​from the power requirements of the internal combustion engine, including for example the mass flow rate of the fuel, the crankshaft speed n_mot, the exhaust gas turbocharger speed n_17, the bypass valve position ζ_WG, the exhaust flap position ζ_AK, the air-fuel ratio λ, the ambient pressure P_0, the ambient temperature T_0, the charge air pressure P_18, the boost pressure P_6, the exhaust gas pressure P_10, the charge air temperature T_18, the charge air temperature T_6, the exhaust gas temperature T_10, the temperature T_19 of the water flowing through the turbine channel 11, the mass flow rate of the exhaust gas, the temperature T_13 of the exhaust gas mass flow flowing through the bypass channel 12, the particulate filter temperature T_24, the age of the mass flow rate of soot in the particulate filter 24, the particulate load of the particulate filter 24 and the nitrogen oxide load of the SCR catalytic converter 26.

[0056] The control unit 21 can be designed to use the situation monitoring device to simulate one or more values ​​of the state vector χ as a function of further values ​​of the state vector χ. The control unit 21 can also simultaneously control the exhaust temperature T_15 and the boost pressure P_6. The control unit 21 is also switched off to set the bypass valve position ζ_WG and the exhaust gas flap position ζ_AK.

[0057] 2 shows a flow chart of one embodiment of a method for simultaneously regulating the exhaust gas temperature and the boost pressure of an internal combustion engine according to the present invention. Here, the method for the internal combustion engine will be described.

[0058] In step V10 of the method according to the invention, the actual boost pressure P_6_Ist at the first time point t0 is determined. This actual boost pressure P_6_Ist is measured by a boost pressure sensor or it can also be determined as a function of the actual exhaust gas turbocharger speed n_17_ist using the situation monitoring device described above.

[0059] In a further step V20 of the inventive method, the actual exhaust gas temperature is determined at the actual time t0. In this case, the actual exhaust gas temperature is determined by a third exhaust gas temperature sensor behind the exhaust gas flap 15 and before the exhaust gas aftertreatment system 16. The actual exhaust gas temperature in this case therefore corresponds to the value T_15_Ist. Alternatively, the actual exhaust gas temperature can also be measured directly in front of the exhaust gas flap 15 by a second exhaust gas temperature sensor. The actual exhaust gas temperature in this case corresponds to the value T_15'_Ist.

[0060] In a further step V30 of the inventive method, the desired boost pressure P_6_Soll is determined at a time t0+T following the actual time t0. The actual time t0 and the subsequent time t0+T limit a prediction horizon for the time T. The desired boost pressure P_6_Soll is determined for the entire prediction horizon. This can be done as a function of the crankshaft speed n_mot and / or the fuel mass flow W_F.

[0061] In a further step V40 of the inventive method, a target range for the exhaust gas temperature T_15 (or exhaust gas temperature T15') is determined for said prediction period, also called target exhaust gas temperature range. For this purpose, a target minimum exhaust gas temperature T_15_min of the exhaust gas temperature range is determined.

[0062] The actual soot load of the particulate filter 24 at the actual time t0 and / or the actual temperature T_24_ist of the particulate filter 24 at the actual time t0 are used to determine the minimum temperature T_24_min of the particulate filter 24 in the target exhaust gas temperature range T_15_min.

[0063] To determine the target minimum exhaust gas temperature T_15_min of the target exhaust gas temperature range, a minimum temperature T_26_min of the SCR catalytic converter 26 is also determined as a function of the actual ammonia loading of the SCR catalytic converter 26 at the actual time t0.

[0064] To determine the target minimum exhaust gas temperature T_15_min of the target exhaust gas temperature range, a maximum temperature T_26_max of the SCR catalytic converter 26 is also determined as a function of the actual temperature T_26_Ist at the actual time t0 and the maximum allowable temperature gradient dT26_max of the SCR catalytic converter 26. The temperature gradient dT26_max represents the change in the mean temperature T_26_mean of the SCR catalytic converter 26 over time.

[0065] A minimum temperature T_25_min of the SCR dosing system 25 is also determined to determine a target minimum exhaust gas temperature T_15_min of the target exhaust gas temperature range, which is obtained as a function of a target reductant mass flow rate of the SCR metering system 25 during the prediction period.

[0066] To determine the target minimum exhaust gas temperature T_15_min of the target exhaust gas temperature range, a comparison value of the minimum temperature T_26_min of the SCR catalytic converter 26 and the minimum temperature T25_min of the SCR dosing system 25 is determined from the maximum of the minimum temperatures T_24_min of the particulate filter 24 .

[0067] If necessary, a target minimum exhaust gas temperature T_15_min of the exhaust gas temperature range can be set to the minimum value from the comparison value and the maximum temperature T_26_max of the SCR catalytic converter 26 .

[0068] In a further step V50 of the inventive method, the manipulated variable ζ_WG of the bypass valve 13 and the manipulated variable ζ_AK of the exhaust gas valve are determined simultaneously using a nonlinear model predictive controller with the actual boost pressure P_6_Ist, the actual exhaust gas temperature T_15_Ist, the desired boost pressure P_6_Soll and the desired exhaust gas temperature range.

[0069] The nonlinear model predictive controller simulates the boost pressure P_6_pred at one or more downstream points in the prediction range as a function of the bypass valve manipulated variable ζ_WG and the exhaust gas flap manipulated variable ζ_AK. The nonlinear model predictive controller simulates the exhaust gas temperature T_15_pred at one or more downstream points in the prediction range as a function of the bypass valve 13 manipulated variable ζ_WG and the exhaust flap 15 manipulated variable ζ_AK.

[0070] The nonlinear model predictive controller minimizes a merit function (quality function) that is a function of the difference between the desired boost pressure P_6_Soll and the predicted boost pressure P_6_pred at one or more subsequent time points. The merit function is also a function of the difference between the desired exhaust gas temperature range and the predicted exhaust gas temperature T_15_pred at one or more subsequent time points. If the predicted exhaust temperature T_15_pred is within the desired exhaust temperature range, the difference between the desired exhaust temperature range and the predicted exhaust temperature T_15_pred is set to zero.

[0071] The nonlinear model predictive controller minimizes a quality function subject to the following constraints:

[0072] The rotation speed n_17 of the exhaust turbocharger 17 must not exceed the maximum rotation speed n_17_max of the exhaust turbocharger 17.

[0073] The exhaust pressure P_10 must not exceed the maximum exhaust back pressure P_10_max.

[0074] The exhaust gas temperature T_10 at the measuring point 10 must not exceed the maximum exhaust gas temperature T_10_max in the exhaust gas duct 8.

[0075] The exhaust gas temperature T_19 immediately after the turbine 19 of the exhaust-gas turbocharger 17 must not exceed the maximum exhaust gas temperature T_19_max at the turbine 19 of the exhaust-gas turbocharger 17.

[0076] The fuel / air ratio λ in the combustion chamber 3 must not fall below a minimum fuel / air ratio λ_min.

[0077] The operation amount ζ_AK of the exhaust flap 15 does not exceed the maximum operation variable ζ_AK_max. The maximum operation amount ζ_AK_max of the exhaust flap 15 is determined as a function of the predicted exhaust gas temperature T_15_pred. When the maximum operation amount ζ_AK_max of the exhaust flap 15 is set to the maximum actuation operation amount ζ_AK_1, the exhaust flap 15 is closed to the maximum extent when the predicted exhaust gas temperature T_15_pred is below the target exhaust gas temperature range.

[0078] Also, when the predicted exhaust gas temperature is equal to or higher than the target exhaust gas temperature range, the maximum operation amount ζ_AK_max of the exhaust flap 15 is set to the minimum operation amount ζ_AK_O at which the exhaust flap 15 is opened to the maximum, as shown by the dashed line in FIG. 3. Alternatively, when the predicted exhaust gas temperature is within or exceeds the target exhaust gas temperature range, as shown by the solid line in FIG. 3, the maximum operation amount ζ_AK_max of the exhaust flap 15 can be set to a value between the maximum operation amount ζ_AK_1 and the minimum operation amount ζ_AK_O. This value decreases toward the minimum operation amount as the difference between the predicted exhaust gas temperature T_15_pred and the target minimum exhaust gas temperature T_15_min increases.

[0079] In a further step V60 of the inventive method, the manipulated variable ζ_WG of the bypass valve 13 is set by a first actuator and the manipulated variable ζ_AK of the exhaust gas flap 15 is set by a second actuator.

[0080] The method of the present invention is executed on the control unit 21 .

[0081] [Fig. 4] shows a simplified control circuit used in the method of the present invention. The target minimum exhaust gas temperature T_15_min is determined by the target exhaust gas temperature range determination unit 23 from the state vector χ of the internal combustion engine 1 and transferred to the model predictive controller MPC. In addition, the set boost pressure P_6_Soll is also determined by the set boost pressure P_6_Soll determination unit 23' from the state vector 2 of the internal combustion engine 1 and transferred to the model predictive controller.

[0082] The determined actual boost pressure P_6_ist and actual exhaust gas temperature T_15_Ist are transferred to a model predictive controller MPC, which simultaneously determines the bypass valve operation amount ζ_AIG 13 and the exhaust flap operation amount ζ_AK as functions of the actual boost pressure P_6_Ist, the actual exhaust gas temperature T_15_Ist, the target boost pressure P_6_Soll and the target exhaust gas temperature range of the target minimum exhaust gas temperature T_15_min.

[0083] New values ​​for the charge pressure P_6 and the exhaust gas temperature T_15 are obtained at a later point in time by means of the control system 22. [Explanation of symbols]

[0084] 1. Internal combustion engine 2 Crankcase 3. Combustion chamber 4 Suction Channels 5. Intake manifold 6 Measurement points 7. Intercooler 8 Exhaust Duct 9 Exhaust manifold 10 Measurement points 11 Turbine duct 12 Bypass duct 13 Bypass valve 14 Collection Point 15 Exhaust flap 16 Exhaust aftertreatment device 17 Exhaust gas turbocharger 18 Compressor 19 Turbine 20 Shaft 21 Control unit 22 Control System 23 Decision Section 24 Particle Filter 25 SCR Dosing System 26 SCR catalytic converter T_ Temperature P_ Pressure χ State vector of the internal combustion engine

Claims

1. An exhaust gas turbocharger (17) having a turbine (19) located in an exhaust gas duct (8) and a compressor (18) located in an intake passage (4), A bypass valve (13) that allows at least a portion of the exhaust gas mass flow rate of the internal combustion engine to pass through the turbine (19), The exhaust flap (15) located downstream of the bypass valve (13) positioned within the turbine (19) and the exhaust gas duct (8), An internal combustion engine characterized by having the following features.

2. The internal combustion engine according to Claim 1, characterized in that the exhaust gas duct (8) has an exhaust gas aftertreatment device (16) equipped with a particle filter (24) and an SCR catalytic converter (26).

3. The internal combustion engine according to claim 2, characterized in that the intake passage (4) and the exhaust gas passage (8) are in fluid communication with each other only through the combustion chamber (3) of the internal combustion engine (1).

4. A method for simultaneously controlling the exhaust gas temperature and boost pressure of an internal combustion engine according to claim 1, comprising the following steps: (V10) Determine the actual boost pressure (P_6_Ist), (V20) Determine the actual exhaust gas temperature (T_15_Ist), (V30) Determine the target boost pressure (P_6_Soll), (V40) Determine the target exhaust gas temperature range, (V50) Using a nonlinear model predictive controller (MPC), the operating amount (ζ_WG) of the bypass valve (13) that guides at least a portion of the exhaust gas mass flow rate of the internal combustion engine (1) to pass through the turbine (19) of the exhaust gas turbocharger (17), and the operating variable (ζ_AK) of the exhaust flap (15) are simultaneously determined as functions of the actual boost pressure (P_6_Ist), the actual exhaust gas temperature (T_15_Ist), the target boost pressure (P_6_Soll), and the target exhaust gas temperature range. (V60) The amount of operation of the bypass valve (13) (ζ_WG) and the amount of operation of the exhaust flap (15) (ζ_AK) are adjusted.

5. The method according to claim 4, wherein the nonlinear model predictive controller (MPC) predicts the boost pressure (P_6_pred) at a later time as a function of the bypass valve (13) variable (ζ_WG) and the exhaust flap (15) operating variable (ζ_AK), the nonlinear model predictive controller (MPC) predicts the exhaust gas temperature (T_15_pred) at a later time as a function of the bypass valve (13) operating variable (ζ_WG) and the exhaust flap (15) operating variable (ζ_AK), and the nonlinear model predictive controller (MPC) minimizes a merit function as a function of the difference between the target boost pressure (P_6_Soll) and the predicted boost pressure (P_6_pred) at a downstream time, and the difference between the target exhaust temperature range and the predicted exhaust gas temperature (T_15_pred) at a downstream time.

6. The above nonlinear model predictive controller (MPC) is as follows: The maximum speed (n_17_max) of the exhaust gas turbocharger (17) of the internal combustion engine (1), The maximum exhaust gas pressure (P_10_max) of the internal combustion engine (1), The maximum exhaust gas temperature (T_10_max) inside the exhaust gas duct (8) of the internal combustion engine (1), The maximum exhaust gas temperature (T_19_max) of the turbine (19) of the exhaust gas turbocharger (17) of the internal combustion engine (1), The minimum fuel-air ratio λ_min in the combustion chamber (3) of the internal combustion engine (1), and Maximum operating amount of exhaust flap (15) (ζ_AK_max) The method according to claim 5, which minimizes the merit function by considering at least one secondary condition.

7. The method according to claim 6, wherein the maximum operating amount (ζ_AK_max) of the exhaust gas flap (15) is determined as a function of the predicted exhaust gas temperature (T_15_pred), where, if the predicted exhaust gas temperature (T_15_pred) is below the target exhaust gas temperature range, the maximum operating amount (ζ_AK_max) of the exhaust gas flap (15) is set to the maximum operating variable (ζ_AK_1) which closes the exhaust gas flap (15) to its maximum extent, and if the predicted exhaust gas temperature (T_15_pred) is above the target exhaust gas temperature range, it is set to the minimum operating amount (LAK_O), or the maximum operating amount (ζ_AK_max) of the exhaust gas flap (15) is set to the state where the exhaust gas flap (15) is fully open.

8. The method according to claim 4, wherein the target exhaust gas temperature range is determined by determining the target minimum exhaust gas temperature (T_15_min) of the target exhaust gas temperature range.

9. The method according to claim 8, wherein a target minimum exhaust gas temperature (T_15_min) of the exhaust gas temperature range and the minimum temperature (T_24_min) of the particle filter (24) of the internal combustion engine are determined as a function of the actual temperature of the particle filter (24) and / or the actual amount of soot of the particle filter (24), the minimum temperature (T_26_min) of the SCR catalytic converter (26) of the internal combustion engine (1) is determined as a function of the ammonia load of the SCR catalytic converter (26), the maximum temperature (T_26_max) of the SCR catalytic converter (26) of the internal combustion engine (1) is determined as a function of the maximum temperature gradient (dT_26_max) of the SCR catalytic converter (26), and the minimum temperature (T_25_min) of the SCR metering system (25) of the internal combustion engine (1) is determined as a function of the required reducing agent mass flow rate of the SCR metering system (25).

10. The method according to claim 9, wherein, in order to determine the target minimum exhaust gas temperature (T_15_min) of the target exhaust gas temperature range, a comparison value is obtained between the minimum temperature (T_24_min) of the particle filter (24) of the internal combustion engine (1), the minimum temperature (T_26_min) of the SCR catalytic converter (26) of the internal combustion engine (1), and the maximum value of the minimum temperature (T_25_min) of the SCR metering system (25) of the internal combustion engine (1), and if necessary, the target minimum exhaust gas temperature (T_15_min) of the exhaust gas temperature range is set to the minimum value from the above comparison value and the maximum temperature of the SCR catalytic converter (26) of the internal combustion engine.

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