AT525355B1 - Method for controlling the temperature of an exhaust gas cleaning system connected to an internal combustion engine with an SCR catalytic converter - Google Patents

Abstract

The invention relates to a method for controlling the temperature of an exhaust gas cleaning system (2) connected to an internal combustion engine (1) and having an SCR catalytic converter. According to the invention, compressed combustion air is fed to the internal combustion engine (1) via a charge air cooler (10) and/or via a first, unheated charge air cooler bypass (11) and/or via a second charge air cooler bypass (12) that can be heated with engine coolant. is supplied, wherein in low-load operation of the internal combustion engine (1), compressed combustion air is fed to the internal combustion engine (1) when the temperature of the engine coolant falls below a threshold value, at least predominantly via the first, unheated charge air cooler bypass (10) and when a threshold value for the temperature of the Engine coolant is supplied at least predominantly via the second intercooler bypass (12) that can be heated with engine coolant.

Description

Description

PROCESS FOR TEMPERATURE CONTROL OF AN EXHAUST GAS CONTROL SYSTEM WITH AN SCR CATALYTIC CONVERTER CONNECTED TO AN INTERNAL COMBUSTION ENGINE

The invention relates to a method for controlling the temperature of an exhaust gas cleaning system connected to an internal combustion engine with an SCR catalytic converter.

[0002] In order to reduce the nitrogen oxides (NOx) contained in the exhaust gas from internal combustion engines, a minimum temperature of approximately 200° C. is required for SCR catalytic converters used for this purpose. In the case of low-load operation, in particular over a longer period, the exhaust gas temperatures and thus also the catalytic converter temperatures drop below this value without appropriate countermeasures, which is why NOx removal from the exhaust gas is then no longer possible or not possible to a sufficient extent. To remedy this disadvantage, DE 10 2004 026 797 A1 proposes mixing uncooled, recirculated exhaust gas into the combustion air compressed by a compressor of an exhaust gas turbocharger. This increases the temperature of the combustion air and at the same time reduces the combustion air ratio, which in turn leads to an increase in the exhaust gas temperature and thus the temperature of the SCR catalytic converter. To further increase the temperature level, the combustion air can be routed via a bypass of an intercooler.

[0003] Further methods for controlling the temperature of an exhaust gas cleaning system connected to an internal combustion engine with an SCR catalytic converter are known, for example, from DE 102007005246 A1 and WO 2018183059 A1.

However, it has been shown that these measures do not always lead to a sufficient increase in the catalyst temperature. It is therefore the object of the invention to specify a method which enables more effective temperature control of an exhaust gas cleaning system connected to an internal combustion engine with an SCR catalytic converter, in particular a more effective increase in the catalytic converter temperature when the internal combustion engine is operated at low load.

[0005] This object is achieved with a method having the features of claim 1. Advantageous refinements of the method according to the invention are specified in the dependent claims.

In the method according to the invention for controlling the temperature of an exhaust gas cleaning system connected to an internal combustion engine with an SCR catalytic converter, compressed combustion air is fed to the internal combustion engine via an intercooler and/or via a first, unheated intercooler bypass and/or via a second bypass with engine coolant heatable intercooler bypass, wherein in low-load operation of the internal combustion engine, combustion air compressed at least as a function of a temperature of the engine coolant is fed to the internal combustion engine either at least predominantly via the first, unheated intercooler bypass or at least predominantly via the second intercooler bypass that can be heated with engine coolant is supplied. The second intercooler bypass is heated via a heat exchanger arranged therein and integrated into the coolant circuit of the internal combustion engine. Intercooler, first intercooler bypass and second intercooler bypass are arranged in parallel in terms of flow, it being possible for a flow through a respective combustion air path to be set by shut-off valves which can preferably be controlled in a controlled manner. The internal combustion engine can be an internal combustion engine for a passenger car or for a commercial vehicle. Although the internal combustion engine can be designed as a spark-ignited Otto engine, the method is particularly suitable when using a diesel engine due to the lower exhaust gas temperatures. As far as the low-load operating range of the internal combustion engine is concerned, in the simplest case this can be limited to a load range of less than 60% or less than about 50% of the engine load. A more precise determination of the low-load operating range can also be obtained using the following formula for an engine

upper speed limit must be specified: Dz = uLDZz + F * (DzNI - uLDZz)

[0007] Here, Dz designates the upper speed limit, uLDz a lower idling speed, DzNI a speed at rated load and F a multiplication factor of approximately 0.6.

For a passenger car with assumed values for a lower idling speed of about 800 rpm and a speed of about 3000 rpm at rated load, this results in a speed upper limit of 2720 1/min with a factor F of 0.6 for the low-load range. at least

For a heavy commercial vehicle with assumed values for a lower idling speed of around 500 rpm and a speed of around 1700 rpm at rated load and with a factor F of 0.6, the upper speed limit for the low-load range is 1220 l /min

By providing the second intercooler bypass, which can be heated by an engine coolant, in conjunction with the first, unheated intercooler bypass, it is possible to react flexibly, in particular to the operating conditions prevailing at low load, and depending on the current temperature of the engine coolant, a particularly effective increase in the combustion air temperature can be reached. In addition to the engine coolant temperature, a temperature of the emission control system can also be used as a criterion for adjusting the combustion air supply to the internal combustion engine either via the first charge air cooler bypass or via the second charge air cooler bypass.

In the method according to the invention it is provided that in the low load range of the internal combustion engine when the temperature of the engine coolant falls below a threshold value, compressed combustion air is supplied to the internal combustion engine at least predominantly via the first, unheated intercooler bypass. “At least predominantly” is to be understood as meaning at least a large part, preferably more than 75%, more than 80% and particularly preferably at least approximately 100% of the compressed combustion air supplied to the internal combustion engine. Any remaining small amount is fed to the internal combustion engine via the second, heatable intercooler bypass.

Conversely, it is provided that in the low-load range of the internal combustion engine when a threshold value for a temperature of the engine coolant is exceeded, the internal combustion engine is supplied with compressed combustion air at least predominantly via the second, heatable intercooler bypass. The statement made above applies accordingly to the proportion of the combustion air routed via the second intercooler bypass. In this case, a small residual portion of the combustion air that may be present is fed to the combustion engine via the first, unheated intercooler bypass. This mode of operation is set in particular when a temperature of the emission control system reaches or falls below a predefinable lower limit value, or an imminent imminent falling below it is detected. The lower limit is preferably about 250 °C. If the lower limit is exceeded, there is not always an urgent need to increase the temperature of the emission control system and the combustion air can also be at least largely, preferably at least almost completely, fed to the internal combustion engine via the first intercooler bypass.

In a further embodiment of the method according to the invention, the threshold value for the temperature of the engine coolant is based on which a decision is made as to whether the compressed combustion air is fed to the internal combustion engine at low load either at least predominantly via the first, unheated intercooler bypass or at least predominantly via the second a charge air cooler bypass that can be heated with engine coolant, in a range from 45 °C to 70 °C. A hysteresis of 1° C. to 20° C. can be provided for the threshold temperature. This avoids frequent switching when the engine coolant temperature is close to the threshold. Although the decisive engine coolant temperature can be determined in the coolant path inside the engine block, it is provided in a further embodiment of the invention that a coolant outlet temperature is decisive. The coolant outlet temperature is preferably at the coolant outlet from the internal combustion engine or at

Coolant entry detected in the arranged in the second intercooler bypass heat exchanger or in an intermediate line area.

In a further embodiment of the method according to the invention, it is provided that in the low-load range of the internal combustion engine, recirculated exhaust gas is admixed with the compressed combustion air without being cooled. The exhaust gas recirculated from an exhaust pipe into the air supply tract can come from a low-pressure exhaust gas recirculation, but preferably it comes from a high-pressure exhaust gas recirculation, i.e. exhaust gas is removed from the exhaust pipe before it is fed to an exhaust gas turbocharger turbine. The recirculated exhaust gas is preferably mixed with the combustion air downstream of the intercooler. In order to increase the recirculated exhaust gas mass flow, the combustion air supplied to the internal combustion engine can also be throttled. For this purpose, an inlet air throttle valve, which is preferably arranged downstream of the intercooler in the intake tract, can be actuated accordingly.

In a further embodiment of the method, when a predetermined load point for the operation of the internal combustion engine is exceeded and a predetermined lower temperature limit for the emission control system is exceeded, compressed combustion air is supplied to the internal combustion engine at least predominantly via the intercooler. In this case, compressed combustion air is preferably supplied to the internal combustion engine at least almost completely via the intercooler, i.e. a shut-off valve is closed in the flow paths of the first, unheated and second, heatable intercooler bypass. In addition, it is preferably provided that the compressed combustion air is mixed with cooled exhaust gas routed via an EGR cooler, i.e. an exhaust gas path leading via an EGR cooler bypass is closed. The recirculated exhaust gas is mixed with the compressed combustion air downstream of the intercooler.

In a further embodiment of the method, when a specified load point for the operation of the internal combustion engine is exceeded and when the temperature falls below the specified lower limit for the emission control system, compressed combustion air is fed to the internal combustion engine at least predominantly both via the intercooler and via the first, unheated intercooler bypass . Preferably, at least approximately 100% of the compressed combustion air is supplied to the internal combustion engine both via the intercooler and via the first, unheated intercooler bypass. In this case, a check valve arranged in the air flow path of the second, heatable charge air cooler bypass is closed and corresponding check valves in the air flow path of the first, unheated charge air cooler bypass or the air path that leads via the charge air cooler are at least approximately fully open. The distribution of the compressed combustion air supplied to the internal combustion engine thus results from the flow resistances of the latter two combustion air paths. In this operating mode, too, it is preferably provided that the compressed combustion air is admixed with cooled exhaust gas that is routed via an EGR cooler downstream of the intercooler.

The predetermined load point provided for the above two operating modes is preferably more than 60%, in particular more than 70% of the rated load and particularly preferably more than 80% of the rated load of the internal combustion engine. The predetermined lower temperature limit for the exhaust gas purification system provided for the two operating modes mentioned above is preferably in the range of 160° C. and 250° C., in particular in the range of 180° C. and 210° C. In this way, an SCR catalytic converter arranged in the exhaust gas cleaning system can be kept in a preferred working temperature range in a particularly reliable manner. Switching hysteresis in the range of approximately 10% to 20% of the nominal load or in the range of 5°C to 50°C can be provided both for the load point of the internal combustion engine and for the lower temperature limit of the exhaust gas purification system.

In a further embodiment of the method, it is provided that when a predeterminable first temperature threshold is exceeded in an air intake manifold of the internal combustion engine, the internal combustion engine compresses combustion air at least predominantly via the charging

air cooler is supplied. The compressed combustion air is preferably supplied to the internal combustion engine at least almost completely via the intercooler. The first temperature threshold is preferably in the range from 90°C to 170°C, particularly preferably in the range from 110°C to 150°C.

In a further refinement of the invention, cooled, recirculated exhaust gas which is routed via an EGR cooler is mixed with the compressed combustion air downstream of the intercooler if a second predeterminable temperature threshold in an air intake manifold of the internal combustion engine is exceeded, the second temperature threshold being higher than the first temperature threshold . The exhaust gas recirculation preferably takes place via a high-pressure EGR path. The second temperature threshold is preferably in the range from 100°C to 180°C, particularly preferably in the range from 120°C to 160°C.

The invention is explained in more detail below with reference to a drawing and associated examples. The only figure shows an overall system consisting of an internal combustion engine and an exhaust gas cleaning system connected to it, as well as an associated air supply system.

The overall system shown only as an example and schematically in the figure comprises an internal combustion engine 1 with a connected exhaust gas cleaning system 2 and an air supply system 3 connected on the intake side, as well as a high-pressure EGR system 4, with the inclusion of components that are not primarily relevant to the invention being dispensed with.

The internal combustion engine 1, hereinafter referred to simply as the engine, is designed here without loss of generality as a four-cylinder diesel engine of a motor vehicle. The engine 1 receives its combustion air for fuel combustion via an air supply line 8, which opens into an intake manifold 18 for supplying the individual engine cylinders with combustion air. Combustion air drawn in can be compressed by a compressor 6 of an exhaust gas turbocharger arranged in the air supply line 8 . Compressed combustion air can be routed via an intercooler 10 arranged in the air supply line 8 and thereby cooled. A first charge air cooler bypass 11 and a second charge air cooler bypass 12 branch off from the air supply line 8 downstream of the compressor 6 and upstream of the charge air cooler 10 and flow back into the air supply line 8 downstream of the charge air cooler 10 .

By means of a heat exchanger 13 which is arranged in the second intercooler bypass 12 and through which engine coolant can flow, compressed combustion air can optionally be heated before it is supplied to the engine 1 . For this purpose, the heat exchanger 13 is integrated into an engine coolant circuit (not shown in more detail) in such a way that engine coolant fed out of the engine 1 enters the heat exchanger 13 . The first intercooler bypass 11, on the other hand, is designed without heat exchanger elements. Compressed combustion air flowing through the first charge air cooler bypass 11 thus returns to the air supply line 8 with an almost unchanged temperature. Controllable shut-off valves are used to distribute the combustion air flow to the air paths through the charge air cooler 10, the first charge air cooler bypass 11 and the second charge air cooler bypass 12 14, 15, 16 provided. A first check valve 14 is arranged in the air path leading through the charge air cooler 10 downstream of the charge air cooler 10 . Alternatively, this check valve 14 can also be positioned upstream of the intercooler 10 . A second check valve 15 arranged in the first charge air cooler bypass 11 enables the combustion air flow to be controlled through this air path. A third check valve 16 arranged in the second charge air cooler bypass 12 upstream of the heat exchanger 13 enables the combustion air flow to be controlled through the second charge air cooler bypass 12 . Alternatively, the check valve 16 can also be positioned downstream of the heat exchanger 13 . It goes without saying, however, that a different valve arrangement can also be provided, which enables the combustion air to be divided between the three air paths connected in parallel. Furthermore, an inlet air throttle valve 17 is provided in the air supply line 8 downstream of the junctions of the first charge air cooler bypass 11 and the second charge air cooler bypass 12, by means of which the quantity of combustion air supplied to the engine 1 can be throttled in an adjustable manner.

Exhaust gas produced during fuel combustion is discharged from the engine 1 via an exhaust manifold 19 and an exhaust pipe 9 leading therefrom. The exhaust gas can drive a turbine 5 of the exhaust gas turbocharger arranged in the exhaust line 9 , this in turn driving the compressor 6 arranged in the air supply line 8 via a shaft 7 . Upstream of the turbine 5, exhaust gas can be branched off from the exhaust gas line 9 via the HP-EGR system 4 and fed into the air supply line 8 downstream of the intake air throttle valve 17 and mixed with the combustion air. Exhaust gas branched off via an EGR line 23 can be routed via an EGR cooler 20 and thereby cooled, or the EGR cooler 20 can be bypassed via an EGR cooler bypass 21 and fed uncooled to the air supply line 8 . A 3-way valve 22 arranged upstream of the EGR cooler 20 makes it possible on the one hand to adjust the entire EGR quantity and on the other hand to divide the EGR quantity over the flow paths through the EGR cooler 20 and the EGR cooler bypass 21.

To clean the exhaust gas from unwanted pollutants, a first exhaust gas converter 24 and a second exhaust gas converter 25 arranged behind it are provided in the exhaust gas cleaning system 2 arranged downstream of the turbine 5 . At least one of the two exhaust gas converters 24, 25 is designed as a so-called SCR catalytic converter, which can reduce NOx even in the case of oxygen-containing exhaust gas by means of a reducing agent. In the present case, both exhaust gas converters 24, 25 are designed as SCR catalytic converters. Urea solution is preferably provided as the selectively acting reducing agent, which is injected into the exhaust pipe 9 on the inlet side of the first exhaust gas converter 24 and/or on the inlet side of the second exhaust gas converter 25 as required. Components required for this are not shown separately for reasons of clarity. It goes without saying that the exhaust gas purification system 2 can also contain additional, in particular catalytically and/or filter-technically active components, such as, for example, oxidation catalysts or particle filters.

Various sensors assigned to the engine 1, the exhaust gas cleaning system 2, the air supply system 3 and the HP-EGR system are provided to record operating variables such as temperature, pressure, gas concentration etc. in the overall system, of which only temperature sensors 26, 27, 28, 29, 30 are shown. A temperature sensor 26 is used to record the combustion air temperature in the intake manifold 18. Another temperature sensor 30 is used to record the engine coolant temperature on the inlet side of the heat exchanger 13. The temperature sensors 27, 28, 29 are used to record the temperatures between the turbine 5 and the first exhaust gas converter 27, between the first exhaust gas converter 24 and second exhaust gas converter 25 and on the outlet side of the second exhaust gas converter 24. A control unit, not shown, processes the temperatures recorded by sensors and signals from the other sensors and, depending on the signal values, in particular causes the shut-off valves 14, 15, 16 of the 3-way valve 22 to be actuated and the intake air throttle valve 17.

In the following, with further reference to the figure, preferred procedures for temperature control of the exhaust gas cleaning system 2 and in particular for increasing the exhaust gas temperature in a low-load operation of the engine 1 for the purpose of achieving or maintaining a temperature necessary for catalytic effectiveness of the first and/or of the second exhaust gas converter 24, 25 received.

If a low-load operating state is determined during operation of the engine 1, then the first check valve 14 downstream of the intercooler 10 is at least predominantly controlled into a closed position, preferably completely closed. Furthermore, depending on the temperature of the engine coolant detected by the temperature sensor 30 in the region of the engine coolant inlet on the heat exchanger 13, the second and the third check valve 15, 16 are actuated in such a way that the engine 1 is supplied with combustion air compressed by the compressor 6 either at least predominantly via the first intercooler Bypass 11 or at least predominantly via the second intercooler bypass 12 is supplied. In the event that the detected temperature falls below a predetermined threshold value in the range from about 45 °C to about 70 °C, for example about 60 °C, the second shut-off valve 15 is at least mostly, preferably completely, opened and the third shut-off valve 16 at least mostly preferably fully closed. This ensures that compressed combustion air is at least predominantly

is preferably supplied at least almost completely via the first intercooler bypass 11 . A cooling of the combustion air by the intercooler 10 or by the heat exchanger 13 is thereby avoided, or heating is achieved. Provision is also made for the 3-way valve 22 to be actuated in such a way that exhaust gas is routed at least predominantly, preferably at least almost completely, via the EGR cooler bypass 21 and thus uncooled to the intake manifold 18 . In this way, highly heated combustion air is supplied to the engine 1 even when the engine coolant has been heated up comparatively little. This results in correspondingly increased exhaust gas temperatures and the exhaust gas cleaning system 2 is prevented from cooling down. In this operating state, the intake air throttle valve 17 can also be turned on and the amount of combustion air supplied to the engine 1 can thus be throttled. When the exhaust gas cleaning system 2 is comparatively cold, for example after a cold engine start or for the purpose of reheating the exhaust gas cleaning system 2, the check valves 14, 15, 16 and the 3-way valve 22 are preferably also brought into the above positions.

In the event that at low engine load, the temperature detected by the temperature sensor 30 exceeds the predetermined threshold value in the range of about 45 ° C to about 70 ° C, for example about 60 ° C, with the first check valve 14 also closed, the second Blocking valve 15 is at least mostly, preferably completely closed and the third blocking valve 16 is at least mostly, preferably completely open. This ensures that compressed combustion air is supplied to the engine 1 at least predominantly, preferably at least almost completely, via the second intercooler bypass 12 and is correspondingly heated as a result of the heated engine coolant. The amount of combustion air supplied to the engine 1 can also be throttled by means of the intake air throttle valve 17 and can contribute to increasing the temperature of the exhaust gas. The 3-way valve 22 is in turn actuated in such a way that exhaust gas is routed at least predominantly, preferably at least almost completely, via the EGR cooler bypass 21 and thus uncooled to the intake manifold 18 . This operating state has proven to be particularly effective for maintaining a temperature of the first or second exhaust gas converter 24, 25, which is required for the catalytic effectiveness, in particular during prolonged low-load or idling operation. If, starting from a hot emission control system 2, there is a transition from high-load operation of the engine 1 to low-load operation, heating of the compressed combustion air by hot engine coolant in the heat exchanger 13 can be dispensed with as long as a lower temperature limit of approx. 250 °C for the emission control system 2 is not reached. In such a case, the compressed combustion air can be routed completely or mostly via the first intercooler bypass 11 .

If, during operation of the engine 1, a load condition is detected which is above the low-load range, in particular in the higher part-load range or in the high-load range, the third check valve 16 relevant to the second intercooler bypass 12 is at least approximately, preferably completely, closed. Compressed combustion air is thus supplied to the engine 1 at least almost completely via the first charge air cooler bypass 11 and/or the charge air cooler 10 . Specifically, when a predetermined threshold temperature for the exhaust gas cleaning system 2 is exceeded, the engine 1 is supplied with compressed combustion air at least predominantly, preferably completely, via the intercooler 10 . For this purpose, the second check valve 15, which is decisive for flow through the first charge air cooler bypass 11, is at least approximately completely closed and the first check valve 14, which is decisive for the flow through the charge air cooler 10, is at least approximately fully opened. If, on the other hand, the predetermined threshold temperature for the exhaust gas cleaning system 2 is not reached, then both the first shut-off valve 14 and the second shut-off valve 15 are at least approximately fully opened. The engine 1 is thus supplied with combustion air both via the intercooler 10 and via the first intercooler bypass 11 . In both cases, the 3-way valve relevant for the high-pressure EGR is controlled in such a way that exhaust gas recirculated to the inlet side of the engine 1 is at least almost completely routed via the EGR cooler 20 . As far as the predetermined threshold temperature for the exhaust gas cleaning system 2 relevant for the above-mentioned operating points is concerned, this is preferably in the range from 160° C. to 250° C., in particular

particularly preferably in the range from 180°C to 210°C. It is preferably sufficient to detect that the temperature has fallen below the threshold if at least one of the two exhaust gas converters 24, 25 has fallen below the threshold temperature or that at least one of the temperature sensors 27, 28, 29 reports a lower temperature. The same can apply to detecting that the threshold temperature has been exceeded. If one of the temperature sensors 27, 28, 29 reports a lower temperature, but another reports a higher temperature, priority can be given to the lower temperature. Furthermore, a hysteresis in the range from 5° C. to 50° C., in particular in the range from 15° C. to 30° C., is preferably provided for the detection of falling below or exceeding the threshold temperature.

The effects of the above-described measures for controlling the temperature of the exhaust gas cleaning system 2 can be tracked and evaluated by detecting the temperature in the intake manifold 18 using the temperature sensor 26 . According to the invention, the detected temperature can be compared to temperature thresholds for this purpose. When a first temperature threshold in the range of approximately 90° C. to 170° C., preferably in the range of 110° C. to 150° C., is exceeded, provision can be made for combustion air to be supplied to engine 1 at least predominantly, preferably at least almost completely, via charge air cooler 10. If a second temperature threshold, which is higher than the first, is exceeded, it can be provided that the exhaust gas routed exclusively via the EGR cooler 20 is admixed to the combustion air. The second temperature threshold is preferably in the range from 100°C to 180°C, particularly preferably in the range from 120°C to 160°C.

REFERENCE LIST

1 combustion engine

2 Emission control system 3 Air supply system

4 HP EGR system

5 turbines

6 compressors

7 wave

8 air supply line

9 exhaust pipe

10 intercooler

11 First charge air cooler bypass 12 Second charge air cooler bypass 13 Heat exchanger

14 First check valve

15 Second check valve

16 Third check valve

17 Intake air throttle 18 Intake manifold

19 exhaust manifold

20 EGR cooler

21 EGR cooler bypass

22 3-way valve

23 EGR line

24 First exhaust gas converter 25 Second exhaust gas converter

26-30 Temperature Sensor

Claims (8)

patent claims 1. Method for temperature control of an exhaust gas cleaning system (2) connected to an internal combustion engine (1) with an SCR catalytic converter, the internal combustion engine (1) being supplied with compressed combustion air via a charge air cooler (10) and/or via a first, unheated charge air cooler bypass (11 ) and/or via a second charge air cooler bypass (12) that can be heated with engine coolant, wherein when the internal combustion engine (1) is operating at low load, compressed combustion air is at least predominantly above the internal combustion engine (1) when the temperature of the engine coolant falls below a threshold value the first, unheated intercooler bypass (10) and when a threshold value for a temperature of the engine coolant is exceeded at least predominantly via the second intercooler bypass (12) that can be heated with engine coolant. 2. The method according to claim 1, characterized in that the threshold value for the temperature of the engine coolant is in the range of 45°C to 70°C. 3. The method according to any one of claims 1 to 2, characterized in that a coolant outlet temperature is decisive for the threshold value for the temperature of the engine coolant. 4. The method according to any one of claims 1 to 3, characterized in that in the low load range of the internal combustion engine (1) of the compressed combustion air recirculated exhaust gas is mixed uncooled. 5. The method according to any one of claims 1 to 4, characterized in that when a predetermined load point for the operation of the internal combustion engine (1) is exceeded and when a predetermined lower temperature limit for the exhaust gas purification system (2) is exceeded, the internal combustion engine (1) is at least predominantly supplied with compressed combustion air is supplied via the intercooler (10). 6. The method according to any one of claims 1 to 5, characterized in that when a predetermined load point for the operation of the internal combustion engine (1) is exceeded and the predetermined lower temperature limit for the exhaust gas cleaning system (2) is not reached, the internal combustion engine (1) is at least predominantly supplied with compressed combustion air is supplied both via the intercooler (10) and via the first, unheated intercooler bypass (11). 7. The method according to any one of claims 1 to 6, characterized in that when a predeterminable first temperature threshold is exceeded in an air intake manifold (18) of the internal combustion engine (1), compressed combustion air is supplied to the internal combustion engine (1), at least predominantly via the intercooler (10). 8. The method according to any one of claims 1 to 7, characterized in that when a predetermined second temperature threshold is exceeded in an air intake manifold (18) of the internal combustion engine (1), the compressed combustion air via an EGR cooler (20) guided, cooled recirculated exhaust gas is mixed , wherein the second temperature threshold is higher than the first temperature threshold. 1 sheet of drawings