DE102018218011A1 - Method for reducing the formation of condensate in a device for mixing exhaust gas and charge air - Google Patents

Abstract

Method for operating an internal combustion engine arrangement (50), comprising the steps of: a) determining the condensed fluid mass and / or ice mass in the mixing device (1); b) performing an initial phase (2) with the following steps b1) to b4): b1) calculating a minimum temperature of an exhaust gas-air mixture upstream of the compressor (52), b2) calculating the maximum temperature at which condensation in the Exhaust gas-air mixture occurs, b3) updating the condensed fluid mass and / or ice mass in the mixing device, b4) setting a temperature setpoint of a fluid in the heat exchanger (36); c) if the minimum temperature is higher than the maximum temperature or the condensed fluid mass and / or ice mass in the mixing device (20) is greater than an upper limit value, carry out a heating phase (4) with steps c1) to c4): c1) Performing steps b1) to b3), c2) calculating a maximum evaporation mass flow, c3) deactivating the exhaust gas recirculation (54) if the condensed fluid mass and / or ice mass in the mixing device (20) is higher than a critical limit value which is higher than the upper limit, c4) setting a temperature set point of the fluid in the heat exchanger; d) if the minimum temperature is not less than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device (20) is less than a lower limit value, carry out a temperature control phase (8) with steps d1) to d3): d1 ) Performing steps c1) to c2), d2) calculating a temperature setpoint of the exhaust gas / air mixture upstream of the compressor, d3) determining a temperature setpoint of the fluid in the heat exchanger (36) and regulating the temperature of the fluid in the heat exchanger ( 36) to the set temperature setpoint.

Description

The present invention relates to a method for operating an internal combustion engine arrangement, the temperature of a fluid in a heat exchanger in a mixing device for mixing exhaust gas and air or charge air being regulated in particular. The invention further relates to a computer program product, a computer-readable storage medium, a mixing device for mixing exhaust gas and charge air, an internal combustion engine arrangement and a vehicle, in particular a motor vehicle.

Internal combustion engine arrangements are often equipped with superchargers, with charge air or fresh air being mixed upstream of the supercharger with recirculated exhaust gas and then being compressed in the supercharger of the supercharger. This can lead to the formation of condensate upstream of the compressor, which may adversely affect the functionality of the compressor or other components. In particular at low ambient temperatures, the use of low-pressure exhaust gas recirculation may be impossible due to the condensate that occurs. The formation of condensate is a problem especially at very low ambient temperatures.

The formation of condensate can be reduced by using a bypass to bypass a low pressure exhaust gas recirculation cooler, but it cannot be completely eliminated. In particular, during the start of the internal combustion engine, there is no exhaust gas heat required to reduce the formation of condensate. If the low-pressure exhaust gas recirculation to the charger is switched off, the area downstream of the mixing device for mixing exhaust gas and charge air cools and restarting the low-pressure exhaust gas recirculation is problematic, especially if condensation is to be avoided.

In the document US 8,960,166 B2 the wall of the flow channel upstream of the compressor is heated by means of coolant of the internal combustion engine which has already been heated in order to avoid the formation of condensate. In the document US 6,367,256 B1 To avoid the formation of condensate in connection with the exhaust gas recirculation, an electric heater is used to evaporate the condensate formed. In the document US 2017/0335748 A1 the use of a cooling fluid to control the temperature of an area for mixing exhaust gas and charge air is also disclosed.

Against the background described, it is an object of the present invention to provide an improved method for operating an internal combustion engine arrangement which further reduces and in particular prevents the formation of condensate. Further tasks consist in providing a correspondingly advantageous computer program product, a computer-readable storage medium, a mixing device for mixing exhaust gas and charge air, an internal combustion engine arrangement and a vehicle.

Said objects are achieved by a method for operating an internal combustion engine arrangement according to claim 1, a computer program product according to claim 12, a computer readable storage medium according to claim 13, a mixing device according to claim 14, an internal combustion engine arrangement according to claim 15 and a vehicle according to claim 16. The dependent claims contain further advantageous refinements of the invention.

1. a) Die kondensierte Fluidmasse und/oder Eismasse in der Mischvorrichtung wird ermittelt. Dies kann zum Beispiel durch Auslesen eines entsprechenden Wertes aus einer Speichervorrichtung, beispielsweise einem KAM (Keep Alive Memory), erfolgen.
2. b) Es wird eine Anfangsphase bzw. Startphase mit den folgenden Schritten b1) bis b4) durchgeführt. In dem Schritt b1) wird eine minimale Temperatur, beispielsweise eine effektive minimale Temperatur, eines Abgas-Luft-Gemisches stromaufwärts des Kompressors berechnet. Die Berechnung erfolgt vorzugsweise für gegebene Randbedingungen.

The method according to the invention for operating an internal combustion engine arrangement relates to an internal combustion engine arrangement which comprises a supercharger with a compressor and a mixing device arranged upstream of the compressor for mixing exhaust gas from an exhaust gas recirculation and charge air. The mixing device comprises a heat exchanger. The heat exchanger is preferably integrated in the mixing device. The method according to the invention, which is preferably carried out during operation of the internal combustion engine, comprises the following steps a) to d):

1. a) The condensed fluid mass and / or ice mass in the mixing device is determined. This can be done, for example, by reading out a corresponding value from a memory device, for example a KAM (Keep Alive Memory).
2. b) An initial phase or start phase is carried out with the following steps b1) to b4). In step b1), a minimum temperature, for example an effective minimum temperature, of an exhaust gas / air mixture upstream of the compressor is calculated. The calculation is preferably carried out for given boundary conditions.

In step b2), the maximum temperature at which condensation occurs in the exhaust gas / air mixture is calculated, that is to say the temperature at which condensation still occurs. In a step b3), the condensed fluid mass and / or ice mass is then updated in the mixing device. In a step b4) a temperature setpoint of a fluid in the heat exchanger fixed. The temperature setpoint of the fluid in the heat exchanger can be determined as the temperature of the exhaust gas / air mixture, at which no fog and / or condensation occurs on the walls of a flow channel leading to the compressor and / or a specified condensation rate in the mixing device is not exceeded .

In a subsequent step c), a heating phase with steps c1) to c4) is carried out if the minimum temperature is higher than the maximum temperature or the condensed fluid mass and / or ice mass in the mixing device is greater than an upper limit value. In step c1), steps b1) to b3) are carried out. In step c2), a maximum evaporation mass flow is calculated, in particular a maximum evaporation mass flow permissible for stable operation of the internal combustion engine. In step c3), the exhaust gas recirculation is deactivated if the condensed fluid mass and / or ice mass in the mixing device is higher than a critical limit value. The critical limit is higher than the upper limit. In step c4), a temperature setpoint of the fluid in the heat exchanger is set. The temperature setpoint is preferably determined as a function of the maximum evaporation mass flow and the minimum temperature.

In a subsequent step d), a temperature control phase with steps d1) to d3) is carried out if the minimum temperature is not less than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device is less than a lower limit value. In step d1), steps c1) to c2) are carried out. In step d2), a temperature setpoint of the exhaust gas / air mixture upstream of the compressor is calculated.

In step d3), a temperature setpoint of the fluid in the heat exchanger is determined, preferably as a function of the temperature setpoint and the maximum temperature calculated in step d2). The temperature of the fluid in the heat exchanger is then regulated to the specified temperature setpoint.

The effective minimum temperature is the lowest gas temperature that can arise along the route from the mixing point to the compressor inlet under stationary operation. The effective minimum temperature is calculated on the basis of the instantaneous maximum achievable coolant temperature in the heat exchanger. The maximum coolant temperature is either the temperature in the low-temperature cooling circuit or the temperature in the high-temperature cooling circuit, whichever is higher. Since the heat exchanger is very effective, the influence of the gas velocity or the gas mass flow can normally be neglected. After passing through the heat exchanger, the mixture is preferably cooled somewhat before it has reached the compressor. The resulting temperature loss can be represented (simplified) as a function of the gas velocity and the material temperature of the compressor supply pipe. That means, the calculation of the effective minimum temperature can be done according to TCompFunMin = f (max (T LT, T_HT), T_mix (gas mass flow)) - g (gas mass flow, temperature of the compressor supply pipe), where TCompFunMin is the effective minimum temperature, T_LT is the coolant temperature in the low temperature circuit, T_HT is the HT coolant temperature in the high temperature circuit, T_mix is the gas temperature of the mixture before entering the heat exchanger, f is a function of the gas temperature immediately after the heat exchanger, and g is a description of the gas temperature drop down to the compressor.

The temperature setpoint of the exhaust gas / air mixture upstream of the compressor is preferably calculated in such a way that a condensate-free gas mass flow towards the compressor is ensured, the maximum desired compressor inlet temperature is not exceeded, the maximum desired compressor outlet temperature is not exceeded, operation the compressor is guaranteed with minimal energy expenditure, an operation of the compressor is guaranteed within a normal operating range. If the aforementioned points cannot be guaranteed at the same time, a priority can be set between the points.

The method according to the invention has the advantage that it enables regulation of the temperature of the fluid in the heat exchanger that is adapted to the specific situation and thus reduces or completely eliminates the formation of condensate in a particularly efficient manner. Another advantage of the present method is that the condensate formed can be efficiently evaporated and removed.

If the internal combustion engine is stopped, the last determined condensed fluid mass and / or ice mass can be stored in the mixing device, for example in the KAM. This has the advantage that the last determined condensed fluid mass and / or ice mass can be read out the next time the method according to the invention is started, and thus a current value is always available.

Evaporative mass flow can be calculated using, for example, ambient temperature, pressure, humidity, and / or the inlet temperature and the combustion mass fraction of the exhaust gas recirculation mass flow and / or the temperature of the fluid in the heat exchanger and / or the charge air mass flow and / or the exhaust gas / air mixture mass flow and / or the condensed fluid mass and / or ice mass, which are characterized by Has collected condensation in the mixing device. The evaporation mass flow can also be determined by means of a sensor, in particular by means of a gas composition sensor. The condensation mass flow can be calculated using the parameters previously mentioned for the calculation of the evaporation mass flow.

In an advantageous variant, the heating phase is repeated if the minimum temperature is lower than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device is greater than an upper limit. Furthermore, the initial phase can be repeated if the minimum temperature is lower than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device is not greater than an upper limit. In a further variant, the heating phase can be repeated if the minimum temperature is not less than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device is not less than a lower limit. The variants described have the advantage that the initial phase and / or the heating phase are repeated until suitable input conditions for carrying out the temperature control phase are met.

The temperature control phase is preferably continued or repeated if the minimum temperature is not lower than the maximum temperature. If the minimum temperature is lower than the maximum temperature, the initial phase or the heating phase is repeated depending on whether the condensed fluid mass and / or ice mass in the mixing device is greater than an upper limit. The initial phase is repeated if the condensed fluid mass and / or ice mass in the mixing device is not greater than an upper limit. The heating phase is repeated if the condensed fluid mass and / or ice mass in the mixing device is greater than an upper limit. The procedure described has the advantage that the temperature control phase is carried out only if suitable conditions are met, and the initial phase and the heating phase are carried out for as long as is necessary and are repeated if necessary.

The condensed fluid mass and / or ice mass in the mixing device can be calculated. This can be done, for example, by integrating the condensation rate or condensate formation rate using the maximum realizable temperature, for example effective temperature, the fluid in the heat exchanger of the mixing device and / or the temperature of the fresh air to be supplied and / or the humidity of the fresh air and / or the pressure of the Fresh air and / or the temperature of the recirculated exhaust gas and / or the combustion mass fraction and / or a certain, for example a desired, combustion mass fraction of the exhaust-air mixture generated by the mixing device and / or a condensation rate, in particular an effective condensation rate, as the difference from the Condensate mass flow and the evaporated mass flow or the evaporation mass flow. In addition, the condensed fluid mass and / or ice mass in the mixing device can be calculated using a zero point, in particular a dry condition, of the condensed fluid mass and / or ice mass in the mixing device. The zero point can be calculated for an exhaust gas recirculation mass flow, in particular a low-pressure exhaust gas recirculation mass flow, to be zero using the ambient air humidity and / or the charge air humidity determined by means of a sensor.

In a further variant, the minimum temperature can be calculated as an instantaneous or averaged minimum temperature, in particular as an instantaneous or averaged effective temperature. The effective minimum temperature can be calculated using a maximum realizable effective temperature of the fluid in the heat exchanger and / or the temperature of the air, that is to say the fresh air supplied, and / or the humidity of the air, that is to say the fresh air supplied, and / or the temperature of the recirculated exhaust gas and / or the combustion mass fraction and / or a certain, for example a desired, combustion mass fraction of the exhaust-air mixture generated by the mixing device.

The maximum temperature can be calculated using the temperature of the air, in particular the fresh air supplied and / or the humidity of the air and / or the combustion mass fraction and / or a specific, in particular a desired, combustion mass fraction of the exhaust-air mixture generated by the mixing device .

erfolgen. Dabei ist O_2,Air,Dry die Sauerstoffkonzentration der Ladeluft.The combustion mass fraction F _Man in the exhaust-air mixture downstream of the mixing device can be determined by measurement using a sensor, for example using a gas composition sensor, and / or by measuring the oxygen concentration O _{2, Man} in the exhaust-air mixture. This can be done, for example, using the formula $$F_{Man}\equiv 1-\frac{O_{\mathrm{2,}Man}}{O_{\mathrm{2,}Air,Dry}}=1-\frac{O_{\mathrm{2,}Man}}{0.2315}$$

respectively. O _{2, Air, Dry is} the oxygen concentration of the charge air.

berechnet werden. Dabei sind η_MCIS die Effizienz des Wärmetauschers, T_ChargeMixln die Temperatur des Abgas-Luft-Gemisches, T_MCIS,Fluid die Temperatur des Fluids im Wärmetauscher, T_LpEgr die Temperatur des über eine Niedrigdruck-Abgasrückführung rückgeführten Abgases und R_LpEgr die spezifische Gaskonstante des rückgeführten Abgases. Falls die Effizienz des Wärmetauschers hinreichend nahe eins ist und der Fluidmassenstrom so hoch ist, dass die Temperaturdifferenz zwischen einem Einlass und einem Auslass der Mischvorrichtung vernachlässigbar ist, so kann die Temperatur T_CompFun des Abgas-Luft-Gemisches mit der Temperatur T_MCIS,Fluid des Fluids im Wärmetauscher approximiert werden.Furthermore, the temperature T _{CompFun of} the exhaust gas-air mixture downstream of the mixing _device or upstream of the compressor according to the formula $$\begin{array}{c}{T}_{\mathrm{C.}OmpFun}=\left(1-{\eta }_{M\mathrm{C.}\mathrm{I.}S}\right)T_{\mathrm{C.}HarGeMix\mathrm{I.}n}\\ +{\eta }_{M\mathrm{C.}\mathrm{I.}S}{T}_{M\mathrm{C.}\mathrm{I.}S,Fluid}\\ \approx \left(1-{\eta }_{M\mathrm{C.}\mathrm{I.}S}\right)(\left(1-R_{LpEGr}\right)T_{Amb}\\ +R_{LpEGr}{T}_{LpEGr})+{\eta }_{M\mathrm{C.}\mathrm{I.}S}{T}_{M\mathrm{C.}\mathrm{I.}S,Fluid}\end{array}$$

be calculated. Here η _{MCIS are} the efficiency of the heat exchanger, T _ChargeMixln the temperature of the exhaust gas-air mixture, T _{MCIS, fluid} the temperature of the fluid in the heat exchanger, T _LpEgr the temperature of the exhaust gas recirculated via a low pressure exhaust gas recirculation and R _LpEgr the specific gas constant of recirculated exhaust gas. If the efficiency of the heat exchanger is sufficiently close to one and the fluid mass flow is so high that the temperature difference between an inlet and an outlet of the mixing _device is negligible, then the temperature T _{CompFun of} the exhaust gas / air mixture with the temperature T _{MCIS, fluid} des Fluids in the heat exchanger are approximated.

In a preferred variant, the mixing device is designed for low-pressure exhaust gas recirculation. The method according to the invention is particularly advantageous in connection with low-pressure exhaust gas recirculation, since in this case there is an increased risk of condensate formation, especially at low ambient temperatures, and the method described effectively reduces the formation of condensate.

The computer program product according to the invention comprises commands which, when the program is executed by a computer, cause the computer to carry out a previously described method according to the invention. The computer-readable storage medium according to the invention comprises commands which, when executed by a computer, cause the computer to execute an inventive method described above. The computer program product and the computer-readable storage medium have the advantages already mentioned above. They can in particular be integrated into existing systems and thus enable the method according to the invention to be used.

The mixing device according to the invention for mixing exhaust gas and charge air comprises a heat exchanger. The mixing device also comprises a control device which is designed to carry out a method according to the invention described above. The internal combustion engine arrangement according to the invention comprises a mixing device according to the invention. The vehicle according to the invention comprises an internal combustion engine arrangement according to the invention. The mixing device according to the invention, the internal combustion engine arrangement according to the invention and the vehicle according to the invention have the advantages mentioned in connection with the method according to the invention. The vehicle according to the invention is preferably a motor vehicle, for example a truck, a car, a minibus, a bus, a motorcycle or a moped.

• 1 zeigt schematisch eine Ausführungsvariante des erfindungsgemäßen Verfahrens in Form eines Flussdiagramms.
• 2 zeigt schematisch eine erfindungsgemäße Mischvorrichtung.
• 3 zeigt schematisch die erfindungsgemäße Mischvorrichtung während der Durchführung der Anfangsphase des erfindungsgemäßen Verfahrens.
• 4 zeigt schematisch eine erfindungsgemäße Mischvorrichtung während der Durchführung der Aufheizphase.
• 5 zeigt schematisch die erfindungsgemäße Mischvorrichtung während der Durchführung der Temperatursteuerphase.
• 6 zeigt schematisch eine erfindungsgemäße Verbrennungsmotoranordnung.
• 7 zeigt schematisch eine weitere Variante einer erfindungsgemäßen Verbrennungsmotoranordnung.
• 8 zeigt schematisch ein erfindungsgemäßes Kraftfahrzeug.

The figures show:

• 1 schematically shows an embodiment variant of the method according to the invention in the form of a flow chart.
• 2nd schematically shows a mixing device according to the invention.
• 3rd schematically shows the mixing device according to the invention during the implementation of the initial phase of the method according to the invention.
• 4th schematically shows a mixing device according to the invention during the implementation of the heating phase.
• 5 shows schematically the mixing device according to the invention during the implementation of the temperature control phase.
• 6 schematically shows an internal combustion engine arrangement according to the invention.
• 7 schematically shows a further variant of an internal combustion engine arrangement according to the invention.
• 8th schematically shows a motor vehicle according to the invention.

An embodiment variant of the method according to the invention is described below on the basis of the 1 shown flowchart explained. The Indian 1 shown block 10th includes process steps that are carried out during the operation of the internal combustion engine. In a first step 1 the condensed fluid mass and / or ice mass is determined in a mixing device arranged upstream of a compressor for mixing exhaust gas and charge air during the operation of an internal combustion engine. Preferably the condensed fluid mass and / Ice mass is read out from a storage device, for example a KAM.

Then step 2nd an initial phase or start phase. In the initial phase, a minimum temperature of an exhaust gas-air mixture upstream of the compressor, preferably for given boundary conditions, is calculated. Furthermore, the maximum temperature at which condensation still occurs in the exhaust-air mixture is calculated. The condensed fluid mass and / or ice mass in the mixing device is updated. A temperature setpoint of a fluid is then defined in a heat exchanger which is preferably integrated in the mixing device. The temperature setpoint is preferably defined as the temperature of the exhaust gas / air mixture at which there is no formation of fog and / or condensation on the walls of a flow channel leading to the compressor and / or a specified condensation rate in the mixing device is not exceeded.

In step 3rd it is checked whether the minimum temperature is higher than the maximum temperature or the condensed fluid mass and / or ice mass in the mixing device is greater than an upper limit. If none of the conditions are met, the method jumps to step 2nd back. If one of the two conditions is met, then in step 4th performed a heating phase.

As part of the heating phase, the first three steps of the initial phase are carried out again, that is to say the calculation of the minimum temperature, the calculation of the maximum temperature and the updating of the condensed fluid mass and / or ice mass. A maximum evaporation mass flow that is permissible for stable operation of the internal combustion engine is then calculated. Furthermore, the exhaust gas recirculation is deactivated if the condensed fluid mass and / or ice mass in the mixing device is higher than a critical limit value. The critical limit is higher than the upper limit. In addition, a temperature setpoint is set in the heat exchanger as part of the heating phase. The temperature setpoint can be set as a function of the maximum evaporative mass flow and the minimum temperature.

In step 5 it is checked whether the minimum temperature is lower than the maximum temperature. If this is the case, then step 7 checked whether the condensed fluid mass and / or ice mass in the mixing device is greater than an upper limit. If this is the case, then the heating phase 4th repeated. If this is not the case, then the initial phase 2nd repeated.

Is at step 5 the minimum temperature is not less than the maximum temperature, so at step 6 checked whether the condensed fluid mass and / or ice mass is less than a lower limit. If this is not the case, then the heating phase 4th repeated. If so, the process goes to step 8th continued with a temperature control phase.

As part of the temperature control phase 8th are the first two steps of the heating phase 4th the first three steps of the initial phase 2nd carried out and a maximum evaporation mass flow calculated. Furthermore, as part of the temperature control phase 8th a temperature setpoint of the exhaust-air mixture is calculated upstream of the compressor. In addition, a temperature setpoint of the fluid is set in the heat exchanger, for example as a function of the calculated temperature setpoint and the minimum temperature of the exhaust gas / air mixture upstream of the compressor. The temperature of the fluid in the heat exchanger is then regulated to the specified temperature setpoint.

Following the temperature control phase 8th will in step 9 checked whether the minimum temperature is lower than the maximum temperature. If this is not the case, the temperature control phase 8th repeated. If so, the process continues with step 7 continued.

In step 11 it is checked whether the internal combustion engine has been stopped. If this is the case, then step 12th the last determined value of the condensed fluid mass and / or ice mass is stored in the mixing device, preferably in a KAM. Then in step 13 checked whether the internal combustion engine was restarted. If this is the case, the procedure will be as related to Block 10th described starting with step 1 resumed.

The 2nd schematically shows a mixing device according to the invention 20th . The mixing device 20th includes a fresh air inlet 21 . The direction of flow of the charge air is indicated by an arrow with the reference number 22 featured. The mixing device 20th includes an air inlet chamber 27 and a mixing area 30th . Inside the air intake chamber 27 is an air filter 28 arranged. Furthermore, the air inlet chamber 27 with an air mass sensor 29 fitted.

To the mixing area 30th leads an exhaust gas recirculation inlet 31 and an air intake 32 . A valve 33 is for variable opening and closing of the air inlet 32 and the exhaust gas inlet 31 designed and arranged so that the air supply and the Exhaust gas supply, and thus the mixture ratio, can be variably controlled. In the mixing area 30th is also a heat exchanger 36 arranged. The heat exchanger 36 includes a fluid inlet 35 and a fluid outlet 37 . The fluid can be a heating and / or cooling fluid. Downstream of the heat exchanger 36 is an outlet 23 arranged, which can also be the inlet of a compressor. The flow direction of the in the mixing chamber 30th Exhaust gas-air mixture generated in the direction of the compressor is indicated by an arrow with the reference number 24th featured. In the variant shown, there is a gas mass sensor in the flow channel to the compressor 25th and a gas composition sensor 26 arranged.

The 3rd shows the in the 2nd shown mixing device 20th during the initial phase. The direction of flow of the fresh air drawn into the air chamber 27 downstream of the air filter 28 is by arrows with the reference number 40 featured. The direction of flow of the recirculated exhaust gas is indicated by arrows with the reference number 41 featured. The flow direction of the exhaust gas-air mixture formed in the mixing chamber 30th is by arrows with the reference number 42 featured. In the situation shown there is in the mixing chamber 30th condensate 43 educated. Ice can also form on the heat exchanger 44 have formed. The exhaust gas-air mixture is through the heat exchanger 36 dehumidified. The direction of flow of the exhaust-air mixture flowing in the direction of the compressor is indicated by the arrows with the reference number 45 featured. In the variant shown, this has the heat exchanger 36 flowing cooling fluid a temperature that corresponds approximately to the ambient temperature and is below the temperature of the exhaust gas-air mixture, which would be necessary to avoid the formation of condensation.

In the 4th the situation during the heating phase is shown. In this phase the fluid is in the heat exchanger 36 a temperature which corresponds approximately to the temperature of the coolant used for cooling the internal combustion engine and is higher than in the initial phase due to the operation of the internal combustion engine. The temperature of the fluid is lower than a maximum outlet temperature for the compressor and higher than a minimum temperature of the fresh air drawn in. Due to the increased temperature of the fluid in the heat exchanger 36 the accumulated condensate is evaporated. This is with the reference number 46 featured. The flow direction of the heat exchanger 36 Exhaust gas-air mixture leaving, which is then directed to the compressor, is indicated by arrows with the reference number 47 featured. It has a higher temperature than the corresponding exhaust gas / air mixture during the initial phase (see 3rd ).

The 5 shows schematically the mixing device 20th during the temperature control phase. In this phase is the temperature of the heat exchanger 36 flowing fluid regulated to a value that ensures that the temperature of the exhaust gas-air mixture is high enough to carry the water contained therein in gaseous form, i.e. high enough that no condensation in the mixing chamber or in flow channels arranged downstream thereof occurs in the direction of the compressor.

On the other hand, it is also cold enough to ensure efficient operation of the compressor.

The 6 schematically shows an internal combustion engine arrangement according to the invention 50 . The internal combustion engine assembly 50 includes an internal combustion engine 60 and a mixing device according to the invention 20th . It also includes a turbocharger 51 that a compressor 52 and a turbine 53 includes. Exhaust gas from the combustion engine 60 becomes the turbine 53 headed which the compressor 52 drives, and then an exhaust gas aftertreatment system 57 fed.

As part of a low-pressure exhaust gas recirculation 54 is already aftertreated exhaust gas from the mixing device 20th fed and with by means of the compressor 52 fresh air drawn in is mixed. The exhaust-air mixture generated in this way is by means of the compressor 52 compressed, then by means of an intercooler 58 cooled and then to the internal combustion engine 60 headed.

The cooling device shown 69 comprises a degassing device 65 . Using a pump 61 coolant becomes the internal combustion engine 60 headed. That the combustion engine 60 leaving, heated coolant becomes a heat exchanger 62 (HT radiator or high-temperature heat exchanger) and cooled there and then via the pump 61 again the internal combustion engine 60 fed. Another part of that is through the internal combustion engine 60 heated cooling fluid is through a flow channel 67 to a fluid temperature control unit 66 headed. The fluid temperature control unit 66 is through another flow channel 68 cold cooling fluid supplied. Cooling fluid is still pumped 64 on the one hand to the fluid temperature control unit 66 and on the other hand to the intercooler 58 headed. The intercooler 58 Leaving heated cooling fluid becomes a heat exchanger 63 (LT radiator or low-temperature heat exchanger) passed and cooled there and then back to the pump 64 headed.

By means of the fluid temperature control unit 66 is using a coolant with the Method according to the invention or a temperature regulated to a predetermined temperature to the inlet 35 of the heat exchanger 36 the mixing device 20th headed. Upstream of the inlet 35 is a temperature sensor in the variant shown 71 arranged to check the temperature of the fluid. That is the heat exchanger 36 through the outlet 37 leaving fluid becomes upstream of the heat exchanger 36 into one of the intercoolers 58 coming flow channel 72 of the heated cooling fluid.

The low pressure exhaust gas recirculation device 54 may include an uncooled return duct only. Alternatively, it can use a low pressure EGR cooler 55 comprise or have a bypass system in addition to the low pressure exhaust gas recirculation cooler. The last variant is with the reference number 56 featured.

The in the 7 variant shown differs from that in the 6 variant shown in that between the fluid temperature control unit 66 and the inlet 35 another pump 73 for pumping the cooling fluid to the inlet 35 is arranged. Furthermore, the pump 64 no longer between the heat exchanger 63 and the fluid temperature control unit 66 , but only between the heat exchanger 63 and the intercooler 58 arranged. The 6 therefore shows an embodiment with two pumps 64 and 61 and the 7 shows an embodiment with three pumps 61 , 64 and 73 .

The 8th schematically shows a motor vehicle according to the invention 70 . The motor vehicle according to the invention 70 comprises a previously described internal combustion engine arrangement according to the invention 50 .

Reference list

1

Determine the condensed fluid mass and / or ice mass

2nd

Perform the initial phase

3rd

Is the minimum temperature higher than the maximum temperature or is the condensed fluid mass and / or ice mass greater than an upper limit?

4th

Carrying out the heating phase

5

Is the minimum temperature lower than the maximum temperature?

6

Is the condensed fluid mass and / or ice mass less than a lower limit?

7

Is the condensed fluid mass and / or ice mass in the mixing device greater than an upper limit?

8th

Perform the temperature control phase

9

Is the minimum temperature less than the maximum temperature?

10th

Process steps during the operation of the internal combustion engine

11

Combustion engine stopped?

12th

Storage of the last determined value of the condensed fluid mass and / or ice mass in the mixing device

13

Combustion engine started up?

20th

Mixing device

21

Fresh air intake

22

Flow direction of the charge air

23

Outlet

24th

Flow direction of the exhaust gas / air mixture in the direction of the compressor

25th

Gas mass sensor

26

Gas composition sensor

27

Air inlet chamber

28

Air filter

29

Air mass sensor

30th

Mixing area

31

Exhaust gas recirculation inlet

32

Air intake

33

Valve

35

Fluid inlet

36

Heat exchanger

37

Fluid outlet

40

Direction of flow of the intake air

41

Direction of flow of the recirculated exhaust gas

42

Direction of flow of the exhaust gas-air mixture

43

condensate

44

ice

45

Direction of flow of the exhaust gas-air mixture to the compressor

46

Evaporation of condensate

47

Flow direction of the exhaust gas-air mixture downstream of the heat exchanger

50

Internal combustion engine arrangement

51

Internal combustion engine

52

compressor

53

turbine

54

Low pressure exhaust gas recirculation

55

Low pressure exhaust gas recirculation cooler

56

Low pressure exhaust gas recirculation cooler with bypass system

57

Exhaust aftertreatment system

58

Intercooler

60

Internal combustion engine

61

pump

62

High temperature heat exchanger

63

Low temperature heat exchanger

64

pump

65

Degassing device

66

Fluid temperature control unit

67

Flow channel

68

Flow channel

69

Cooling device

70

Motor vehicle

71

Temperature sensor

72

Flow channel

73

pump

J

Yes

N

No

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 8960166 B2 [0004]
• US 6367256 B1 [0004]
• US 2017/0335748 A1 [0004]

Claims (16)

Method for operating an internal combustion engine arrangement (50), which comprises a supercharger (51) with a compressor (52) and a mixing device (20) arranged upstream of the compressor (52) for mixing exhaust gas from an exhaust gas recirculation (54) and charge air (22) , wherein the mixing device (20) comprises a heat exchanger (36), characterized in that the method comprises the following steps: a) determining the condensed fluid mass and / or ice mass in the mixing device (1), b) performing an initial phase (2) with the following steps b1) to b4): b1) calculating a minimum temperature of an exhaust gas-air mixture upstream of the compressor (52), b2) calculating the maximum temperature at which condensation occurs in the exhaust gas-air mixture, b3) Updating the condensed fluid mass and / or ice mass in the mixing device, b4) setting a temperature setpoint of a fluid in the heat exchanger (36), c) if the minimum temperature is higher is greater than an upper limit as the maximum temperature or the condensed fluid mass and / or ice mass in the mixing device (20), performing a heating phase (4) with steps c1) to c4): c1) performing steps b1) to b3 ), c2) calculating a maximum evaporation mass flow, c3) deactivating the exhaust gas recirculation (54) if the condensed fluid mass and / or ice mass in the mixing device (20) is higher than a critical limit value which is higher than the upper limit value, c4) setting a temperature setpoint of the fluid in the heat exchanger, d) if the minimum temperature is not less than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device (20) is less than a lower limit value, performing a temperature control phase (8) with the Steps d1) to d3): d1) performing steps c1) to c2), d2) calculating a temperature target value of the exhaust gas / air mixture upstream the compressor, d3) setting a temperature setpoint of the fluid in the heat exchanger (36) and regulating the temperature of the fluid in the heat exchanger (36) to the set temperature setpoint. Procedure according to Claim 1 , characterized in that the heating phase (4) is repeated if the minimum temperature is lower than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device (20) is greater than an upper limit value. Procedure according to Claim 1 or 2nd , characterized in that the initial phase (2) is repeated if the minimum temperature is lower than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device (20) is not greater than an upper limit value. Procedure according to one of the Claims 1 to 3rd , characterized in that the heating phase (4) is repeated if the minimum temperature is not less than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device is not less than a lower limit. Procedure according to one of the Claims 1 to 4th , characterized in that if the minimum temperature is not less than the maximum temperature, the temperature control phase is continued or if the minimum temperature is less than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device (20) is not greater as an upper limit, the initial phase (2) is repeated, or if the minimum temperature is lower than the maximum temperature and the condensed fluid mass and / or ice mass in the mixing device (20) is greater than an upper limit, the heating phase (2) is repeated. Procedure according to one of the Claims 1 to 5 , characterized in that the condensed fluid mass and / or ice mass is calculated in the mixing device (20). Procedure according to one of the Claims 1 to 6 , characterized in that the minimum temperature is calculated as the instantaneous or averaged effective minimum temperature. Procedure according to Claim 7 , characterized in that the effective minimum temperature using a maximum realizable effective temperature of a fluid in the heat exchanger (36) and / or the temperature of the charge air (22) and / or the humidity of the charge air (22) and / or the temperature of the recirculated Exhaust gas (41) and / or the combustion mass fraction and / or a certain combustion mass fraction of the exhaust-air mixture generated by means of the mixing device (20). Procedure according to one of the Claims 1 to 8th , characterized in that the maximum temperature is calculated using the temperature of the charge air and / or the humidity of the charge air and / or the combustion mass fraction and / or a specific combustion mass fraction of the exhaust-air mixture generated by the mixing device (20). Procedure according to one of the Claims 1 to 9 , characterized in that the combustion mass fraction in the exhaust-air mixture downstream of the mixing device (20) is determined by measurement by means of a sensor (26) and / or by measurement of the oxygen concentration in the exhaust-air mixture. Procedure according to one of the Claims 1 to 10th , characterized in that the mixing device (20) is designed for low-pressure exhaust gas recirculation (54). A computer program product, comprising instructions which cause the computer to execute the program, a method according to one of the Claims 1 to 11 to execute. Computer-readable storage medium, comprising instructions which cause a computer to execute it, a method according to one of the Claims 1 to 11 to execute. Mixing device (20) for mixing exhaust gas and charge air, which comprises a heat exchanger (36), characterized in that the mixing device (20) comprises a control device (66) which is designed to implement a method according to one of the Claims 1 to 11 to execute. Internal combustion engine arrangement (50), according to a mixing device (20) Claim 14 includes. Vehicle (70) which has an internal combustion engine arrangement (50) Claim 15 includes.

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