WO2010020265A1

WO2010020265A1 - Flexible use of exhaust gas energy in operating an internal combustion engine

Info

Publication number: WO2010020265A1
Application number: PCT/EP2008/006846
Authority: WO
Inventors: Karl Krebber-Hortmann; Enno Lohse
Original assignee: Fev Motorentechnik Gmbh
Priority date: 2008-08-20
Filing date: 2008-08-20
Publication date: 2010-02-25

Abstract

The invention relates to a method for operating an internal combustion engine 11 having a liquid cooling system comprising an air intake train 16, an exhaust gas train 23 in which a means for exhaust gas treatment are disposed, and a controllable exhaust gas recirculation line 24, 25 from the exhaust gas train 23 to the air intake train 16, in which an exhaust gas heat exchanger 27 incorporated in the liquid cooling system is disposed, wherein the exhaust gas train 23 is throttled or blocked at one location after a cold start of the internal combustion engine, and the exhaust gas flow is fed from the exhaust gas train 23 through the exhaust gas heat exchanger 27 and back to the exhaust gas train 23, and the exhaust gas recirculation line 25 is blocked before the inlet to the air intake train 16.

Description

Flexible use of exhaust gas energy in the operation of an internal combustion engine

description

The invention relates to a method for operating an internal combustion engine having a liquid cooling system, which has an air intake line, an exhaust line in which exhaust aftertreatment means are arranged, and a controllable exhaust gas recirculation line from the exhaust line to the air intake line, in which an exhaust gas heat exchanger included in the liquid cooling system is arranged. Moreover, the invention relates to an internal combustion engine with a liquid cooling system having an air intake line, an exhaust line and an exhaust gas recirculation line from the exhaust gas line to the air intake line, in which an exhaust gas heat exchanger included in the liquid cooling system is arranged.

An exhaust gas recirculation device for an internal combustion engine of a motor vehicle is known from DE 297 22 813 U1, with an exhaust gas recirculation line leading away from an exhaust line and leading to the air supply of the internal combustion engine, in which an exhaust gas recirculation valve and an exhaust gas cooler are arranged, which are connected to a circuit for the engine coolant connected.

Here, a thermostatic valve is arranged between the exhaust gas cooler and the circuit of the engine coolant, which blocks a flow of the exhaust gas cooler up to a predetermined above the ambient temperature lying minimum temperature of the coolant. By means of this design of the exhaust gas recirculation line is to ensure that not reached due to a flow of coolant into the exhaust gas cooler the achievement of the operating temperature of the engine is delays, in which the engine operates cheaper in terms of consumption and emission, than in a cold state. From DE 10 2006 033 314 A1, a heat exchanger system with an engine cooled by an engine cooling circuit is known, to which recirculated exhaust gas and / or charge air can be supplied. It is provided to limit the cooling capacity of the heat exchanger system so that the dew point temperature of the cooled medium, ie the recirculated exhaust gas or the charge air is not exceeded.

From DE 103 20 801 A1 an internal combustion engine is known, in which an exhaust gas heat exchanger is arranged in the exhaust gas strut, which is located in the cooling circuit of the internal combustion engine. This can be a heat recovery from the exhaust gas into the coolant. Here, the exhaust gas temperature should be kept in a temperature window for optimum exhaust aftertreatment and at the same time the internal combustion engine to be heated quickly to achieve a friction reduction with a faster heating of the coolant and thus the engine after the cold start.

From DE 100 43 621 A1, an internal combustion engine with an exhaust gas heat exchanger included in the liquid cooling system is known, wherein the exhaust gas heat exchanger is located in a controllable bypass line in the exhaust gas line. By an exhaust gas temperature-controlled management of the exhaust gas via the exhaust gas heat exchanger temperature peaks in the downstream nitrogen oxide storage catalyst should be avoided.

In the development of modern internal combustion engines, low fuel consumption and favorable emissions are in the foreground. In this context, regardless of the working process, an increase in process efficiencies is sought and implemented.

Increasing the process efficiency leads to a slowing down of the heating of the internal combustion engine after the cold start. In order to increase the process efficiency and to reduce the raw emissions, the supply of cooled exhaust gas to the combustion air (EGR) is of particular importance. Catalysts for exhaust aftertreatment, in particular NOx storage catalysts (DeNOx catalyst) and selective catalytic regeneration catalysts (SCR catalyst), show a pronounced temperature dependence of their conversion efficiency. The positioning of DeNOx or SCR catalytic converter in the exhaust system must be based on the maximum temperatures occurring at nominal power. In the lean-tuned partial load range, this leads to a non-optimal temperature operating range of the DeNOx catalyst or of the SCR catalyst. In the lower load range must be throttled accordingly to maintain the temperature, or the fuel-air mixture can not be tuned lean in idle and thus not be low fuel consumption.

To maintain certain component temperatures in the exhaust system (catalytic converters and turbochargers), the fuel-air mixture is sometimes significantly enriched (λ <1) with corresponding additional consumption. This leads in particular to high CO and HC emissions after the three-way catalyst in the substoichiometric operating range.

On this basis, the present invention seeks to propose a method for the flexible use of the exhaust energy and an internal combustion engine with suitable means for both the operating temperature of the engine influenced in a favorable manner and the raw emission of the engine lowered and the exhaust aftertreatment can be optimized ,

The solution to this consists in a method for operating an internal combustion engine having a liquid cooling system, which has an air intake line, an exhaust line, are disposed in the means for exhaust aftertreatment, and a controllable exhaust gas recirculation line from the exhaust line to the air intake in which a included in the liquid cooling system exhaust gas heat exchanger is arranged, in which after the cold start of the internal combustion engine, the exhaust gas line is throttled or locked at one point and the exhaust gas flow from the exhaust line through the exhaust gas heat exchanger and back into the exhaust line is performed and the exhaust gas recirculation line is blocked before entering the Luftansaugstrang. (Mode 1) The inventive method thus opens up the possibility, in an internal combustion engine having the means for cooled exhaust gas recirculation, according to the invention control the exhaust gas so that an accelerated heating of the cooling water circuit in the internal combustion engine and thus the internal combustion engine altogether after the cold start possible becomes. By accelerated reaching the operating temperature, the internal friction of the internal combustion engine is thereby accelerated reduced, so that the disadvantages that arise in modern internal combustion engines as a result of process efficiency increase in the warm-up behavior, can be limited or canceled.

The method according to the invention and the internal combustion engine according to the invention with the abovementioned means are applicable to free-suction gasoline engines as well as to supercharged gasoline engines and supercharged diesel engines, with mixed-gasoline gasoline engines and direct-injection gasoline engines being included.

In the operation of an internal combustion engine with an exhaust gas turbocharger is provided in particular that after the cold start of the internal combustion engine, the exhaust stream is removed behind the exhaust gas turbocharger from the exhaust system and fed through the exhaust heat exchanger back into the exhaust system. (Mode 1)

According to a further improvement of the method according to the invention, it is provided that, in the partial load operation of the internal combustion engine, a variably controllable partial flow of the exhaust gas is conducted from the exhaust gas system via the exhaust gas heat exchanger into the air intake line. (Mode 2). With this procedure in part-load operation, it is possible to perform a cooled exhaust gas recirculation to increase the process efficiency and to reduce the high emissions after reaching the desired operating temperature of the internal combustion engine. In this case, the exhaust gas temperature of the non-recirculated exhaust gas remains uncooled on the substantially borrowed power-dependent normal value, which is within the temperature window required for the exhaust gas aftertreatment.

An operation of an internal combustion engine with an exhaust gas turbocharger is in particular provided that in the partial load operation of the internal combustion engine, the partial flow is removed from the exhaust gas line in front of the exhaust gas turbocharger and passed through the exhaust gas heat exchanger in the air intake line. (Mode 2)

According to a further embodiment of the method is provided at least at full load and / or high part load of the internal combustion engine, the exhaust system is throttled throttled at a point and the exhaust gas temperature is kept limited to the means for exhaust aftertreatment to a maximum value by a partial flow of the exhaust gas from the exhaust system is passed through the exhaust gas heat exchanger and passed a first variably controllable lower part of the stream into the air intake line and a second variably controllable sub-stream is fed back into the exhaust line. (Mode 3). With this procedure, the exhaust gas recirculation is shown on the one hand for the reasons already mentioned, on the other hand, the adjusting temperature of the exhaust gas can be limited and reduced by cooling a partial flow of the exhaust gas, if otherwise exhaust gas temperatures would be reached, which would lead to damage to the components for exhaust aftertreatment ,

For operation of an internal combustion engine with an exhaust gas turbocharger is provided here that at least at full load and / or at high partial load of the internal combustion engine, the partial flow is taken to the exhaust gas heat exchanger the exhaust line in front of the exhaust gas turbocharger. (Mode 3)

The product according to the invention is in an internal combustion engine having a liquid cooling system, which has an air intake line, an exhaust line and an exhaust gas recirculation line from the exhaust line to the air intake in which an integrated in the liquid cooling system exhaust heat exchanger is arranged, which is characterized in that in the exhaust gas recirculation line behind the Exhaust gas heat exchanger, a first shut-off and control valve is arranged and that branches off from the exhaust gas recirculation line between the exhaust gas heat exchanger and shut-off Abgasbypass- a line which opens into the exhaust line behind the branch point of the exhaust gas recirculation line and in which a second shut-off and control valve is arranged and that between the branch point the exhaust gas recirculation line and the junction of the exhaust gas bypass line in the exhaust line a throttle and check valve is arranged. It can be provided that the first shut-off valve and the second shut-off valve are combined to form a three-way valve at the point of branching.

In the event that the internal combustion engine is a free-breathing gasoline engine, it is provided that a three-way catalytic converter before the branch point of Abgasrück- guide line and a DeNOx and / or SCR catalyst behind the junction of the exhaust gas bypass line is located in the exhaust system.

If the internal combustion engine has an exhaust gas turbocharger, it is provided that a high-pressure branch of the exhaust gas recirculation line connects the exhaust line in front of the turbine with the inlet to the exhaust gas heat exchanger and a low-pressure branch of the exhaust gas recirculation line the exhaust line behind the turbine with the inlet to the exhaust gas heat exchanger, in the high-pressure branch, a third shut-off and Control valve and the low-pressure branch a fourth shut-off and control valve is arranged. It can be provided that the third shut-off valve and the fourth shut-off valve are combined to form a three-way valve at the point of line merger.

In the case of a supercharged gasoline engine, a three-way catalytic converter is provided in front of the Ab branch of the exhaust gas recirculation line and a DeNOx and / or SCR catalyst behind the junction of the exhaust gas bypass line in the exhaust line.

In the case of a supercharged diesel engine, a diesel oxidation catalyst and / or a diesel particulate filter is to be provided in front of the branch point of the exhaust gas recirculation line and a DeNOx and / or SCR catalyst behind the junction of the exhaust gas bypass line in the exhaust line. For supercharged internal combustion engines in particular a charge air cooler is to be used in the intake manifold.

According to the inventive concept described above, alone or in combination, the utilization of the exhaust thermal energy for rapidly heating the engine cooling water and engine oil after the cold start, cooling the exhaust gas recirculation flow to reduce fuel consumption and NOx emissions in the lean operation mode (stratified or homogeneously lean) and the Cooling the exhaust gas recirculation flow to reduce fuel consumption in the upper load range possible. In this case, by cooling a partial flow of the exhaust gas in the exhaust gas flow, the maximum temperature before a NOx storage catalyst can be maintained even at full load, without enrichment of the fuel-air mixture is required for supercharged gasoline engines. In this case, a single integrated line system with control elements in a compact simple and clear design is used.

Two embodiments of internal combustion engines according to the invention are shown in the drawings in the basic structure and in various operating modes.

Figure 1 shows an internal combustion engine according to the invention in the form of a freischaugender gasoline engine in a schematic arrangement including the air intake and the exhaust ducts;

FIG. 2 shows the internal combustion engine according to FIG. 1 in the cold start mode (mode

D ^;

FIG. 3 shows the internal combustion engine according to FIG. 1 in part-load mode (mode 2);

FIG. 4 shows the internal combustion engine according to FIG. 1 in full load mode (mode

3);

Figure 5 shows an internal combustion engine according to the invention in the form of a supercharged gasoline engine or as a supercharged diesel engine in a schematic arrangement including the air intake and the exhaust ducts.

FIG. 6 shows the internal combustion engine according to FIG. 5 in cold start mode (mode

D ^;

FIG. 7 shows the internal combustion engine according to FIG. 5 in part-load mode (mode 2);

FIG. 8 shows the internal combustion engine according to FIG. 5 in full load mode (mode

3).

FIG. 9 shows an internal combustion engine according to FIG. 5 in a first modified embodiment with a cooled exhaust manifold;

FIG. 10 shows an internal combustion engine according to FIG. 5 in a second modified embodiment with cooled exhaust manifold.

1 shows an internal combustion engine 11 according to the invention in the form of a free-suction four-cylinder engine, which can be understood as a mixture-sucking or direct-injection gasoline engine, with four cylinders being symbolized by circles in plan view. On the intake side, an intake manifold 12 with a throttle valve 13 can be seen, which opens into an intake air collector 14. From the intake air collector 14, four intake manifolds 15 lead to the air intake side of the engine. The Luftansaugstrang total of the aforementioned parts is designated by the reference numeral 16.

On the opposite outlet side of the internal combustion engine 11 four exhaust nozzles 17 can be seen, which open into an exhaust manifold 18. From the exhaust manifold 18, an exhaust pipe 20 first leads into a three-way catalyst 19 and from there via a further section of the exhaust pipe 20 to a catalyst 21 in the form of a DeNOx catalyst or in the form of an SCR catalyst. The exhaust line in total from the aforementioned parts is designated by the reference numeral 23.

In the exhaust pipe 20, a controllable throttle and shut-off valve 22 is provided between the catalytic converters 19, 21. From the exhaust gas line 20, an exhaust branch line 24 departs in front of the throttle flap 22, which is branched at a branch point 29 into an exhaust gas recirculation line 25 and into an exhaust gas bypass line 26. In the exhaust gas recirculation line 24 before the branch is an exhaust gas heat exchanger 27th used, on the one hand can be traversed by branched off exhaust gas, on the other hand in an outer cooling water pipe 28 of the engine 11 and is constantly flowed through by the cooling water. A cooling water-air heat exchanger as the main heat exchanger, on which the internal combustion engine 11 also has, is not shown. In the exhaust gas recirculation line 25 behind the branch point 29 is an exhaust gas control valve 30. In the exhaust gas bypass 26 behind the branch 29 is another exhaust control valve 31. The exhaust gas recirculation line 25 is connected via a branching system 32 with the individual air intake 15. On the catalyst 21, a temperature measuring device 33 for the catalyst temperature T4 is indicated. The aforementioned parts in total are referred to as exhaust gas recirculation system 34.

By closing the throttle valve 22 in the exhaust pipe 20, a part or the entire exhaust gas flow can be performed via the exhaust branch line 24, while in the fully open position of the throttle valve 22 is given the opportunity to pass a large proportion of the exhaust stream directly to the catalyst 21.

By a variable opening and closing of the exhaust control valves 30, 31, it is possible to return an alternating amount of exhaust gas in the air intake 16 or to pass back through the heat exchanger 27 back into the exhaust line 23.

Further details of the various control options will become apparent from the following figures.

FIG. 2 shows the cold start mode of the internal combustion engine, wherein the line sections of the lines 24, 25, 26 through which exhaust gas flows are characterized by thin lines extending parallel to the line branches. The same details are assigned the same numbers as in FIG. 1.

In the cold start mode, no exhaust gas recirculation takes place in the air intake line, which is caused by the exhaust control valve 30 is fully closed. At the same time, however, the entire exhaust gas flow is guided by closing the throttle valve 22 and by opening the exhaust gas control valve 31 via the exhaust gas heat exchanger 27 and immediately back into the exhaust pipe 20 behind the throttle valve 22. As a result, the cooling water of the internal combustion engine is maximally and as quickly as possible brought to a desired elevated temperature, wherein the exhaust gas is cooled in a permissible manner. The catalyst 21 thereby remains effective.

FIG. 3 shows the partial load mode of the internal combustion engine according to FIG. The same details are given the same reference numerals as in FIG. The exhaust gas flow through portions of the lines 24, 25, 26 are marked with parallel to the lines running thin lines.

It is shown the operating mode at low partial load, which is driven in particular with an air ratio λ> 1 and thus requires the production of the ignitability, a stratification of the fuel-air mixture in order to ensure the spark plug, an air ratio within the ignition limits. At maximum open throttle valve 22, the exhaust control valve 31 is kept closed and the exhaust control valve 30 is opened, so that a return of exhaust gas in the air intake line 16 can take place. In this case, the exhaust gas forcibly flows via the exhaust gas heat exchanger 27, so that the cooling water is further heated and cooled exhaust gas is conducted into the intake line 16 to improve the efficiency. However, no cooled exhaust gas is returned to the exhaust line 23.

In Figure 4, the operating mode at high part load is again shown with an air ratio λ> 1 and the operating mode at full load. The same details are given the same numbers as in FIG. 1. The portions of the lines 24, 25, 26 through which exhaust gas flows are marked by thin lines running parallel to the lines.

The blocking flap 22 is partially closed and the part of the exhaust gas stream which is diverted via the exhaust branch line 24 is branched by opening the exhaust gas regulating valve 30 and regulating the exhaust gas regulating valve 31 variably to the line branches 25, 26. In this mode of operation, the exhaust gas is as previously described returned to the cooling system in the heat exchanger 27 in the intake air system, while for controlling and optimizing the exhaust gas temperature T4 in the catalyst 21, a variable large partial flow of the cooled exhaust gas before the catalyst 21 is returned to the exhaust pipe 20.

FIG. 5 shows an internal combustion engine 11 according to the invention in the form of a turbocharged four-cylinder engine, which can be understood as a mixed-intake or direct-injection gasoline engine or as a diesel engine, four cylinders being symbolized by circles in plan view. On the suction side, a Ansaugstut- zen 12 is shown, which is connected via the compressor 42 of an exhaust gas turbocharger 41 with a charge air pipe 45. In the charge air pipe 45 is a charge air cooler 44, which can use ambient air or cooling water of the internal combustion engine as a coolant. In the charge air pipe 45, which opens into an intake air collector 14, a throttle valve 13 can be seen. From the intake air collector 14, four intake manifolds 15 lead to the air intake side of the engine. The charge air line as a whole is designated by the reference numeral 16.

On the opposite outlet side of the internal combustion engine 11 four exhaust nozzles 17 can be seen, which open into an exhaust manifold 18. The exhaust gas collector 18 acts on the turbine 43 of the exhaust gas turbocharger 41. In a gasoline engine, an exhaust gas line 20 leads from the exhaust gas collector 18 initially into a three-way catalytic converter 19 (TWC) and from there via a further section of the exhaust gas line 20 to a catalytic converter 21 in the form of a DeNOx - or an SCR catalyst. In a diesel engine, a diesel oxidation catalyst (DOC) and / or a diesel particulate filter (DPF) replace the three-way catalytic converter 19. The exhaust line in total from the aforementioned parts is designated by the reference numeral 23.

In the exhaust pipe 20, a controllable throttle and shut-off valve 22 is provided between the two catalysts. From the exhaust pipe 20, an exhaust branch line 24 branches off in front of the throttle valve 22, which branches off at a branch point 29 into an exhaust gas recirculation line 25 and into an exhaust gas bypass line 26. In the exhaust gas recirculation line 25 before the branch, an exhaust gas heat exchanger 27 is used, which can be traversed on the one hand by diverted exhaust gas, on the other hand in an outer cooling water line 28 of the internal combustion engine 11 is constantly flowed through by the cooling water. A cooling water-air heat exchanger as the main heat exchanger, on which the internal combustion engine 11 also has, is not shown. In the exhaust gas recirculation line 25 behind the branch point 29 is an exhaust gas control valve 30. In the exhaust gas bypass 26 behind the branch 29 is another exhaust control valve 31. The exhaust gas recirculation line 25 is connected via a branching system 32 with the individual air intake 15. From the exhaust manifold 18 in front of the turbine 43 leads a high-pressure branch line 35 at high pressure level in the exhaust branch line 24. A low-pressure branch 36 goes behind the turbine, ie with low pressure level of the exhaust pipe 20 to the exhaust branch line 24 from. At a junction 39, the high-pressure branch line 35 opens into the low-pressure branch line 36. Respectively before the junction 39 exhaust control valves 37 and 38 are used in the lines, indicated. By closing the throttle valve 22 in the exhaust pipe 20, a part or the entire exhaust gas flow can be guided via the exhaust branch line 24, while in the fully open position of the throttle valve 22 is given the opportunity to pass a large proportion of the exhaust gas flow directly to the catalyst 21. On the catalyst 21, a temperature measuring device 33 for the catalyst temperature T4 is provided. The aforementioned parts are referred to collectively as Abgasrückführsystem 34.

By a variable opening and closing of the exhaust gas control valves 30, 31 and 37, 38, it is possible to return a changing proportion of exhaust gas in the air intake 16 or after passing through the heat exchanger 27 back into the exhaust line 23.

FIG. 6 shows the cold start mode of the internal combustion engine, wherein the line sections of the lines 24, 25, 26, 35, 36 through which exhaust gas flows are characterized by thin lines running parallel to the line sections. The same details are given the same numbers as in FIG. 5. In the cold start mode, no exhaust gas recirculation takes place in the air intake line, which is caused by the exhaust control valve 30 is fully closed. At the same time, however, the entire exhaust stream or a partial stream is guided by closing the throttle valve 22 and by opening the exhaust control valves 36 and 31 via the exhaust heat exchanger 27 and immediately back into the exhaust pipe 20 behind the throttle valve 22. The exhaust control valve 37 is closed in this case, so that the exhaust branch line 24 is fed exclusively via the low-pressure branch 36. As a result, the cooling water of the internal combustion engine is maximally and as quickly as possible brought to a desired elevated temperature, wherein the exhaust gas is cooled in a permissible manner. The catalyst 21 remains effective

FIG. 7 shows the partial load mode of the internal combustion engine according to FIG. 5. The same details are given the same reference numerals as in FIG. The exhaust gas flow through portions of the lines 24, 25, 26, 35, 36 are marked with parallel to the lines extending thin lines.

It shows the operating mode at low partial load. At maximum open throttle valve 22, the exhaust control valve 31 is kept closed and the exhaust gas control valve 30 is opened, so that a return of exhaust gas in the air intake line 16 can take place. In this part-load mode, the exhaust control valve 37 is opened and the exhaust control valve 38 is closed, so that the exhaust branch line 24 is fed exclusively via the high-pressure branch 35. In this case, the exhaust gas forcibly flows via the exhaust gas heat exchanger 27, so that the cooling water is further heated up and cooled exhaust gas is led into the intake line 16 in order to improve the efficiency and to reduce the raw emissions. However, no cooled exhaust gas is returned to the exhaust line 23.

FIG. 8 shows the operating mode at high partial load and the operating mode at full load. The same details are given the same reference numbers as in FIG. 5. The sections of the lines 24, 25, 26, 35, 36 through which exhaust gas flows are marked by thin lines running parallel to the lines. The blocking flap 22 is partially closed and the part of the exhaust gas stream which is diverted via the exhaust branch line 24 is branched by opening the exhaust gas regulating valve 30 and regulating the exhaust gas regulating valve 31 variably to the line branches 25, 26. In this mode of operation, the exhaust gas is fed from the high-pressure branch 35 into the exhaust branch line as described above and after cooling in the heat exchanger 27 in a partial flow in the intake air system, while limiting the exhaust gas temperature T4 a variable large part flow of the cooled exhaust gas cooled in front of the catalyst 21 is returned to the exhaust pipe 20.

Insofar as in FIGS. 5 to 8 a gasoline engine is used as the basis, here too in the partial load flow according to FIG. 7 and in operation with a high partial load according to FIG.

FIGS. 9 and 10 each show an internal combustion engine 11 according to the invention in the form of a turbocharged four-cylinder engine, which can be understood as a gasoline engine or as a diesel engine, wherein four cylinders are symbolized by circles in plan view. On the intake side, an intake 12 is shown, which is connected via the compressor 42 of an exhaust gas turbocharger 41 with a charge air pipe 45. In the charge air pipe 45 is a charge air cooler 44, which can use ambient air or cooling water of the internal combustion engine as a coolant. In the charge air pipe 45, which opens into an intake air collector 14, a throttle valve 13 can be seen. From the intake air collector 14, four intake manifolds 15 lead to the air intake side of the engine. The charge air line as a whole is designated by the reference numeral 16.

On the opposite outlet side of the internal combustion engine 11 four exhaust nozzles 17 ^{'can be seen} , which open into an exhaust manifold 18 ^' .

In Figure 9, the exhaust port 17 ^' and exhaust manifold 18 ^' enclosed by a cooling water jacket 46 which is integrated into the cooling water circuit of the internal combustion engine, and the exhaust heat, z. B. can escape for accelerated warming of the engine after the cold start. In FIG. 10, the exhaust nozzles 17 ^' and the exhaust collector 18 ^{' are} enclosed by a cooling water jacket 46, which is exclusively part of an outer coolant circuit 47, which is not connected to the coolant circuit of the internal combustion engine. In this outer coolant circuit is a recooler or energy converter 48, with the transferred by the coolant exhaust heat transferred to other media or can be converted directly into electrical or mechanical energy.

In both embodiments, the exhaust gas collector 18 ^' acts on the turbine 43 of the exhaust gas turbocharger 41. In a gasoline engine, an exhaust gas line 20 leads from the exhaust gas collector 18 initially into a three-way catalytic converter 19 (TWC) and from there via a further section of the exhaust gas line 20 to a catalyst 21 in the form a DeNOx or an SCR catalyst. In a diesel engine, a diesel oxidation catalyst (DOC) and / or a diesel particulate filter (DPF) replace the three-way catalyst 19. The exhaust line in total from the aforementioned parts is designated by the reference numeral 23.

In the exhaust pipe 20, a controllable throttle and shut-off valve 22 is provided between the two catalysts. From the exhaust pipe 20, an exhaust branch line 24 branches off in front of the throttle valve 22, which branches off at a branch point 29 into an exhaust gas recirculation line 25 and into an exhaust gas bypass line 26. In the exhaust gas recirculation line 25 before the branch, an exhaust gas heat exchanger 27 is used, which can be traversed by branched off exhaust gas, on the other hand in an outer cooling water line 28 of the internal combustion engine 11 and is constantly flowed through by the cooling water. A cooling water-air heat exchanger as the main heat exchanger, on which the internal combustion engine 11 also has, is not shown. In the exhaust gas recirculation line 25 behind the branch point 29 is an exhaust gas control valve 30. In the exhaust gas bypass 26 behind the branch 29 is another exhaust control valve 31. The exhaust gas recirculation line 25 is connected via a branching system 32 with the individual air intake 15. From the exhaust manifold 18 ^'in front of the turbine 43 leads a high-pressure branch line 35 at high pressure level in the exhaust branch line 24. A low-pressure branch 36 goes behind the turbine, ie with low pressure level of the exhaust pipe 20 to the exhaust branch line 24 off. At a junction 39, the high-pressure branch line 35 opens into the low-pressure branch line 36. Respectively before the junction 39 exhaust control valves 37 and 38 are used in the lines, indicated. By closing the throttle valve 22 in the exhaust pipe 20, a part or the entire exhaust gas flow can be guided via the exhaust branch line 24, while in the fully open position of the throttle valve 22 is given the opportunity to pass a large proportion of the exhaust gas flow directly to the catalyst 21. On the catalyst 21, a temperature measuring device 33 for the catalyst temperature T4 can be seen. The aforementioned parts are referred to collectively as Abgasrückführsystem 34.

LIST OF REFERENCE NUMBERS

11 internal combustion engine

12 intake manifold

13 throttle

14 intake air collector

15 intake manifold

16 intake manifold

17 exhaust gas outlet

18 exhaust collector

19 Three-way catalytic converter 0 Exhaust line 1 Catalyst 2 Throttle 3 Exhaust line 4 Exhaust branch line 5 Exhaust gas recirculation line 6 Exhaust bypass line 7 Heat exchanger 8 Cooling water bypass line 9 Branching point 0 Exhaust control valve 1 Exhaust control valve 2 Branching system 3 Temperature measuring device 4 Exhaust gas recirculation system 5 High-pressure branch 6 Low-pressure branch Emission control system

Exhaust gas control valve

junction point

turbocharger

compressor

turbine

Intercooler

Turbo pipe

Cooling water jacket

Cooling water circuit

Drycoolers / energy converter

Claims

Flexible use of exhaust energy in the operation of an internal combustion engine Patent claims

1. A method for operating an internal combustion engine (11) with a liquid cooling system, which an air intake line (16), an exhaust line (23) are arranged in the means for exhaust aftertreatment, and a controllable exhaust gas recirculation line (24, 25) from the exhaust line (23 ) to the air intake line (16), in which an exhaust gas heat exchanger (27) included in the liquid cooling system is arranged,

in which

After the cold start of the internal combustion engine, the exhaust gas line (23) is throttled or blocked at one point and the exhaust gas flow from the exhaust line (23) via the exhaust gas heat exchanger (27) and back into the exhaust line (23) and the exhaust gas recirculation line (25) before Entry into the air intake line (16) is blocked. (Mode 1)

2. The method according to claim 1,

in which

in part-load operation of the internal combustion engine (11) a variable partial flow of the exhaust gas from the exhaust line (23) via the exhaust gas heat exchanger (27) into the air intake line (16) is passed. (Mode 2)

BESTATIGUNGSKOPIE

3. The method according to any one of claims 1 or 2,

in which

at least at full load and / or at high part load of the internal combustion engine (11) the exhaust line (23) is controllably throttled at a point and the exhaust gas temperature is kept limited before the exhaust aftertreatment means to a maximum by a partial flow of the exhaust gas from the exhaust line (23 ) is guided over the exhaust gas heat exchanger (27) and a first variably controllable sub-stream is passed into the air intake line (16) and a second variably controllable sub-stream in the exhaust line (23) is returned. (Mode 3)

4. The method according to any one of claims 1 to 3 for operating an internal combustion engine with an exhaust gas turbocharger,

in which

after the cold start of the internal combustion engine (11), the exhaust gas stream behind the exhaust gas turbocharger (41) from the exhaust line (23) and out via the exhaust gas heat exchanger (27) back into the exhaust line (23). (Mode 1)

5. The method according to any one of claims 2 to 4 for operating an internal combustion engine with an exhaust gas turbocharger,

in which

in part-load operation of the internal combustion engine, the partial flow is removed from the exhaust gas line (23) in front of the exhaust gas turbocharger (41) and guided into the air intake line (16) via the exhaust gas heat exchanger (27). (Mode 2)

6. The method according to any one of claims 3 to 5 for operating an internal combustion engine with an exhaust gas turbocharger,

in which

at least at full load and / or at high partial load of the internal combustion engine (11) of the partial flow to the exhaust gas heat exchanger (27) the exhaust line (23) in front of the exhaust gas turbocharger (41) is removed. (Mode 3)

7. The method according to any one of claims 2, 3, 5 or 6 for the operation of a mixture-compression or air-compression internal combustion engine with spark ignition (gasoline engine, gasoline engine with direct injection),

in which

operated at partial load and / or at high part load with an air ratio λ> 1.

8. The method of claim 6 for the operation of an air-compressing auto-ignition internal combustion engine (diesel engine)

in which

the intermittent regeneration of a diesel particulate filter is initiated and carried out, while the partial flow is taken to the exhaust gas heat exchanger (27) the exhaust line (23) in front of the exhaust gas turbocharger (41).

9. Internal combustion engine (11) having a liquid cooling system, which has an air intake line (16), an exhaust line (23) and an exhaust gas recirculation line (24, 25) from the exhaust line (23) to the air intake line (16), in which an included in the liquid cooling system exhaust gas heat exchanger (27) is arranged characterized,

that in the exhaust gas recirculation line (25) behind the exhaust gas heat exchanger (27) a first shut-off and control valve (30) is arranged and that of the exhaust gas recirculation line (25) between the exhaust gas heat exchanger (27) and shut-off valve (30) branches off an exhaust gas bypass line (26) in the exhaust line (23) behind the branch point of the exhaust gas recirculation line (24) opens and in which a second shut-off and control valve (31) is arranged and that between the branch point of the exhaust gas recirculation line (24) and the junction of the exhaust gas bypass line (26) in the exhaust line ( 23) a throttle and check valve (22) is arranged.

10. Internal combustion engine according to claim 9,

characterized,

the first shut-off valve (30) and the second shut-off valve (31) are combined to form a three-way valve at the point of the manifold (29).

11. Internal combustion engine according to any one of claims 9 to 10,

characterized,

in that the internal combustion engine (11) is a free-running gasoline engine and a three-way catalytic converter (TWC) (19) before the branching point of the exhaust gas recirculation line (24) and a NOx storage catalytic converter (DeNOx) and / or a selective catalytic reduction catalytic converter (SCR) (21) behind the junction of the exhaust gas bypass line (26) in the exhaust line is located.

12. Internal combustion engine according to any one of claims 9 to 10,

characterized, that the internal combustion engine (11) is provided with an exhaust gas turbocharger, wherein in the intake line (16) of the compressor (42) and in the exhaust line (23), the turbine (43) of the exhaust gas turbocharger (41) of the internal combustion engine (11) is arranged, and that a High-pressure branch (35) of the exhaust gas recirculation line (24) the exhaust line in front of the turbine (43) with the inlet to the exhaust gas heat exchanger (27) and a low-pressure branch (36) of the exhaust gas recirculation line (24) the exhaust line behind the turbine (43) with the inlet to the exhaust gas heat exchanger ( 27), wherein in the high-pressure branch (35) a third shut-off and control valve (37) and in the low-pressure branch (36), a fourth shut-off and control valve (38) is arranged.

13. Internal combustion engine according to claim 12,

characterized,

in that the third shut-off valve (37) and the fourth shut-off valve (38) are combined to form a three-way valve at the point of line connection (39).

14. Internal combustion engine according to any one of claims 12 to 13,

characterized,

in that the internal combustion engine (11) is a turbocharged gasoline engine and a three-way catalytic converter (TWC) (19) before the branching point of the exhaust gas recirculation line (24) and a NOx storage catalytic converter (DeNOx) and / or a selective catalytic reduction catalytic converter (SCR) (21) behind the junction of the exhaust gas bypass line (26) in the exhaust line (23).

15. Internal combustion engine according to one of claims 12 to 13,

characterized,

that the internal combustion engine (11) is a supercharged diesel engine and a diesel engine Seloxidationskatalysator (DOC) and / or a diesel particulate filter (DPF) before the branch point of the exhaust gas recirculation line (24) and a NOx storage catalyst (DeNOx) and / or a selective catalytic reduction catalyst (SCR) (21) behind the junction of the exhaust gas bypass line (26) in Exhaust line (23) is located.

16. Internal combustion engine according to any one of claims 12 to 15,

characterized,

a charge air cooler (44) lies behind the compressor (42) of the exhaust gas turbocharger (41) in the intake line (16).

17. Internal combustion engine according to any one of claims 9 to 16,

characterized,

in that an exhaust gas collector (18 ^' ) is provided which has a double-walled construction, the space between the walls being included in the coolant circuit of the internal combustion engine (11).

18. Internal combustion engine according to one of claims 9 to 16,

characterized,

in that an exhaust collector (18 ^' ) is provided, which is double-walled, wherein the space between the walls in an external coolant circuit (47) with radiator elements (48) is included.