DE102018209238B4 - Turbocharged internal combustion engine with exhaust gas recirculation and method for operating such an internal combustion engine - Google Patents

Abstract

Supercharged internal combustion engine with - an intake system (1) for supplying charge air, - an exhaust gas discharge system for discharging exhaust gas, - at least one exhaust gas turbocharger, which comprises a turbine arranged in the exhaust gas discharge system and a compressor (2) arranged in the intake system (1), the compressor (2) is equipped with at least one impeller mounted in a compressor housing on a rotatable shaft, and - an exhaust gas recirculation (5) comprising a return line (5a) which, upstream of the at least one compressor impeller, enters the intake system (5c) with the formation of a first node (5c) 1) opens, characterized in that the intake system (1) upstream of the at least one compressor impeller is equipped with a phase change material (4) which is present as a liquid phase or as a solid phase, the phase change material (4) either absorbing heat during a phase transition or give off heat.

Description

• - einem Ansaugsystem zum Zuführen von Ladeluft,
• - einem Ansaugsystem zum Zuführen von Ladeluft,
• - einem Abgasabführsystem zum Abführen von Abgas,
• - mindestens einem Abgasturbolader, der eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst, wobei der Verdichter mit mindestens einem in einem Verdichtergehäuse auf einer drehbaren Welle gelagerten Laufrad ausgestattet ist, und
• - einer Abgasrückführung umfassend eine Rückführleitung, die stromaufwärts des mindestens einen Verdichterlaufrades unter Ausbildung eines ersten Knotenpunktes in das Ansaugsystem mündet.

The invention relates to a supercharged internal combustion engine

• - an intake system for supplying charge air,
• - an intake system for supplying charge air,
• - an exhaust gas removal system for removing exhaust gas,
• - At least one exhaust gas turbocharger, which comprises a turbine arranged in the exhaust gas discharge system and a compressor arranged in the intake system, the compressor being equipped with at least one impeller mounted in a compressor housing on a rotatable shaft, and
• an exhaust gas recirculation system comprising a recirculation line which opens into the intake system upstream of the at least one compressor impeller with the formation of a first junction.

The invention also relates to a method for operating such an internal combustion engine.

An internal combustion engine of the type mentioned is used as a motor vehicle drive and, for example, in the German Offenlegungsschrift DE 10 2009 046 016 A1 described. In the context of the present invention, the term internal combustion engine relates to diesel engines and Otto engines, but also hybrid internal combustion engines, ie internal combustion engines that are operated with a hybrid internal combustion process, as well as hybrid drives that, in addition to the internal combustion engine, have at least one additional torque source for driving a motor vehicle include, for example, an electric machine that can be or is drive-connected to the internal combustion engine and which delivers power instead of the internal combustion engine or in addition to the internal combustion engine.

In the development of internal combustion engines, constant efforts are made to minimize fuel consumption. Internal combustion engines are therefore increasingly often equipped with a supercharger, the supercharging primarily a process for increasing performance in which the charge air required for the engine combustion process is compressed, whereby a larger charge air mass can be supplied to each cylinder per work cycle. This allows the fuel mass and thus the mean pressure to be increased.

Supercharging is a suitable means of increasing the output of an internal combustion engine with unchanged cubic capacity or reducing the cubic capacity with the same output. In any case, the charging leads to an increase in the installation space performance and a more favorable power mass. If the cubic capacity is reduced, the collective load can be shifted towards higher loads at which the specific fuel consumption is lower. So-called downspeeding can also be achieved by charging in combination with a suitable transmission design, in which a lower specific fuel consumption can also be achieved.

Supercharging consequently supports the constant effort in the development of internal combustion engines to minimize fuel consumption, i.e. to improve the efficiency of the internal combustion engine.

Often an exhaust gas turbocharger is used for supercharging, in which a compressor and a turbine are arranged on the same shaft. The hot exhaust gas flow is fed to the turbine and relaxes while releasing energy in the turbine, causing the shaft to rotate. The energy released by the exhaust gas flow to the turbine and finally to the shaft is used to drive the compressor, which is also located on the shaft. The compressor conveys and compresses the charge air supplied to it, as a result of which the cylinders are charged. A charge air cooler is often provided downstream of the compressor in the intake system, with which the compressed charge air is cooled before it enters the at least one cylinder. The cooler lowers the temperature and thus increases the density of the charge air, so that the charge air cooler also contributes to better filling of the cylinders, i.e. to a larger air mass. There is a compression by cooling.

The advantage of an exhaust gas turbocharger compared to a mechanical charger is that there is or is no mechanical connection for power transmission between the charger and the internal combustion engine. While a mechanical supercharger draws the energy required for its drive entirely from the internal combustion engine and thus reduces the power provided and thus adversely affects the efficiency, the exhaust gas turbocharger uses the exhaust gas energy of the hot exhaust gases.

Another fundamental goal is to reduce pollutant emissions. In solving this task, charging can also be effective. With a targeted design of the supercharging, advantages in terms of efficiency and exhaust emissions can be achieved. To comply with future limit values for pollutant emissions In addition to charging, other internal engine measures are required.

Exhaust gas recirculation is used to reduce raw nitrogen oxide emissions. The rate of return x _ACR is determined as x _ACR = m _AGR / (m _AGR + m _{fresh air} ), where m _AGR the mass of recirculated exhaust gas and m _{fresh air} denotes the fresh air supplied. The oxygen provided via exhaust gas recirculation may have to be taken into account.

The internal combustion engine according to the invention charged by means of an exhaust gas turbocharger is equipped with an exhaust gas recirculation system, the return line of which opens up into the intake system upstream of the at least one compressor impeller, forming a first junction.

In the present case, the exhaust gas recirculation can be a high-pressure EGR, which takes exhaust gas from the exhaust gas discharge system upstream of the turbine of the exhaust gas turbocharger and introduces it into the intake system, or a low-pressure EGR, which recirculates exhaust gas to the inlet side that has already flowed through the turbine. A low-pressure EGR comprises a return line which branches off from the exhaust gas removal system downstream of the turbine and opens into the intake system upstream of the compressor.

The main advantage of low-pressure EGR compared to high-pressure EGR is that the exhaust gas flow introduced into the turbine is not reduced by the amount of exhaust gas that is recirculated in the case of exhaust gas recirculation. The entire exhaust gas flow is always available at the turbine to generate a sufficiently high boost pressure.

The preferably cooled exhaust gas, which is returned to the inlet side by means of exhaust gas recirculation, is mixed with fresh air upstream of the compressor. The mixture of fresh air and recirculated exhaust gas produced in this way forms the charge air, which is fed to the compressor and compressed.

It is harmless that exhaust gas is passed through the compressor as part of exhaust gas recirculation, since exhaust gas is preferably used which has been subjected to exhaust gas aftertreatment, in particular in a particle filter, downstream of the turbine. Deposits in the compressor, which change the geometry of the compressor, in particular the flow cross-sections, and in this way impair the efficiency of the compressor, are therefore not to be feared.

On the other hand, problems can arise upstream of the compressor if the temperature of the recirculated hot exhaust gas decreases and condensate forms. A distinction must be made between two scenarios.

On the one hand, condensate can form when the recirculated hot exhaust gas meets and is mixed with cool fresh air. The exhaust gas cools down, whereas the temperature of the fresh air is raised. The temperature of the mixture of fresh air and recirculated exhaust gas, i.e. the charge air temperature, is below the exhaust gas temperature of the recirculated exhaust gas. As part of the cooling of the exhaust gas, liquids contained in gaseous form in the exhaust gas or in the charge air, in particular water, can condense out beforehand if the dew temperature of a component of the gaseous charge air flow is not reached.

Condensate forms in the free charge air flow, with impurities in the charge air frequently forming the starting point for the formation of condensate droplets.

On the other hand, condensate can form when the recirculated hot exhaust gas or the charge air hits the inner wall of the intake system or the inner wall of the compressor housing, since the wall temperature is usually below the dew temperature of the relevant gaseous components.

Condensate and condensate droplets are undesirable and lead to increased noise emissions in the intake system, possibly damaging the blades of the at least one compressor impeller. The latter is associated with a reduction in the efficiency of the compressor.

The problem described above is exacerbated as the recirculation rate increases, since with the increase in the amount of recirculated exhaust gas, the proportions of the individual exhaust gas components in the charge air inevitably increase, in particular the proportion of the water contained in the exhaust gas. According to the prior art, the amount of exhaust gas that is recirculated is therefore often limited in order to prevent or reduce condensation. The necessary limitation on the one hand and the high exhaust gas recirculation rates required for a significant reduction in nitrogen oxide emissions on the other hand lead to different objectives when measuring the amount of recirculated exhaust gas. The legal requirements for the reduction of nitrogen oxide emissions illustrate the high relevance of this problem for practice.

According to the prior art, the intake system is therefore also equipped with a heating device in individual cases, with which the temperature of the inner wall of the intake system can be increased can. The formation of condensation on the inner wall of the intake system can be avoided or reduced in this way. This is a complex and costly concept.

The German Offenlegungsschrift DE 199 14 438 A1 describes a combination of an exhaust gas heat exchanger for cooling recirculated exhaust gas and a cooling water heat store. The utility model DE 200 13 781 U1 concerns a two-stroke engine in which a latent heat accumulator is provided with which the combustion air and the fuel-air mixture are preheated on the way from the air inlet to the combustion chamber when the two-stroke engine is cold-started.

The German Offenlegungsschrift DE 100 04 545 A1 describes a honeycomb body for an exhaust system, in the interior of which a heat accumulator is arranged, the heat accumulator preferably being made of a phase change material.

In this respect, the conflict shown cannot be resolved cost-effectively according to the prior art, so that a high-pressure EGR must often also be used, the exhaust gas taken from the exhaust gas discharge system upstream of the turbine of the exhaust gas turbocharger into the intake system and the exhaust gas located in the intake system downstream of the compressor introduces compressed and heated charge air.

Against this background, it is an object of the present invention to provide a supercharged internal combustion engine according to the preamble of claim 1, with which the disadvantages known from the prior art are overcome, large amounts of exhaust gas can be introduced upstream of the compressor into the intake system and with which in particular the formation of condensate in the context of exhaust gas recirculation can be counteracted.

Another sub-object of the present invention is to provide a method for operating such an internal combustion engine.

• - einem Ansaugsystem zum Zuführen von Ladeluft,
• - einem Abgasabführsystem zum Abführen von Abgas,
• - mindestens einem Abgasturbolader, der eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst, wobei der Verdichter mit mindestens einem in einem Verdichtergehäuse auf einer drehbaren Welle gelagerten Laufrad ausgestattet ist, und
• - einer Abgasrückführung umfassend eine Rückführleitung, die stromaufwärts des mindestens einen Verdichterlaufrades unter Ausbildung eines ersten Knotenpunktes in das Ansaugsystem mündet,

die dadurch gekennzeichnet ist, dass

• - das Ansaugsystem stromaufwärts des mindestens einen Verdichterlaufrades mit einem Phasenwechselmaterial ausgestattet ist, welches als flüssige Phase oder als feste Phase vorliegt, wobei das Phasenwechselmaterial bei einem Phasenübergang entweder Wärme aufnimmt oder Wärme abgibt.

The first sub-task is also solved by a supercharged internal combustion engine

• - an intake system for supplying charge air,
• - an exhaust gas removal system for removing exhaust gas,
• - At least one exhaust gas turbocharger, which comprises a turbine arranged in the exhaust gas discharge system and a compressor arranged in the intake system, the compressor being equipped with at least one impeller mounted in a compressor housing on a rotatable shaft, and
• - An exhaust gas recirculation system comprising a recirculation line which opens into the intake system upstream of the at least one compressor impeller with the formation of a first junction,

which is characterized in that

• - The intake system upstream of the at least one compressor impeller is equipped with a phase change material which is present as a liquid phase or as a solid phase, the phase change material either absorbing heat or giving off heat during a phase transition.

The intake system of the internal combustion engine according to the invention is equipped with a phase change material with which the temperature of the inner wall of the intake system can be increased if necessary, for example also before or during a cold start of the internal combustion engine. By means of heating, the wall temperature can be raised above the dew temperature of the gaseous components of the charge air or of the recirculated exhaust gas.

A formation of condensate on the inner wall of the intake system or on the inner wall of the compressor housing can be avoided or reduced in this way.

By preventing the formation of condensate in the intake system and in the inlet area of the compressor, there is also no increased noise emission due to condensate droplets. The risk of damage to the impeller blades of the at least one compressor is eliminated.

It is not necessary to limit the amount of recirculated exhaust gas introduced into the intake system upstream of the compressor, so that high recirculation rates can be achieved in order to significantly reduce nitrogen oxide emissions.

If necessary, the phase change material is activated, for example mechanically or electrically stimulated, in such a way that heat is given off and entered into the intake system. The phase change material undergoes a phase transition from the liquid phase to the solid phase or vice versa; depending on the material used.

In order to prepare the phase change material again for the next use or the next use, heat must be supplied, with the phase change material in the context of this Regeneration again completes a phase transition in the opposite direction, ie back from the solid phase to the liquid phase or vice versa.

The phase change material either gives off heat or absorbs heat during a phase transition. This means that the material either acts like a thermal sink, i.e. as a heat-absorbing energy store, or as a heat-emitting heating device.

This achieves the first object on which the invention is based, namely a supercharged internal combustion engine with which the disadvantages known from the prior art are overcome, large amounts of exhaust gas can be introduced into the intake system upstream of the compressor and with which in particular the formation of condensate as part of exhaust gas recirculation can be counteracted.

Further advantageous embodiments of the supercharged internal combustion engine are discussed in connection with the subclaims.

Embodiments of the supercharged internal combustion engine are advantageous in which the intake system upstream of the compressor housing is equipped with a phase change material which is present as a liquid phase or as a solid phase, the phase change material either absorbing heat or giving off heat during a phase transition.

The compressor housing as such forms the intake system, so that it can be viewed as part of the intake system. According to the above embodiment, however, the compressor housing is excluded. The phase change material is expressly not placed or provided in the compressor housing, but in the intake system upstream of the compressor housing.

Embodiments of the supercharged internal combustion engine are also advantageous in which the intake system at the first node is equipped with a phase change material which is present as a liquid phase or as a solid phase, the phase change material either absorbing or releasing heat during a phase transition.

At the point of the intake system where the recirculated exhaust gas is introduced, namely at the first junction, the exhaust gas is mixed with the fresh air and regularly deflected more strongly, so that the risk of condensation forming at the first junction is particularly high. It is therefore particularly useful to equip the intake system at the first node with a phase change material.

Embodiments of the supercharged internal combustion engine are advantageous in which the phase change material ( 4th ) gives off heat during a phase transition from the liquid phase to the solid phase.

In this context, embodiments of the supercharged internal combustion engine are advantageous in which the phase change material absorbs heat during a phase transition from the solid phase to the liquid phase.

However, embodiments of the supercharged internal combustion engine in which the phase change material emits heat during a phase transition from the solid phase to the liquid phase can also be advantageous.

Embodiments of the supercharged internal combustion engine are advantageous in which the compressor of the at least one exhaust gas turbocharger is a radial compressor. This embodiment allows a tight packaging of the exhaust gas turbocharger and thus the supercharging as a whole. The compressor housing can be designed as a spiral or worm housing, whereby the deflection of the charge air flow in the compressor of the exhaust gas turbocharger can be used in an advantageous manner to transfer the compressed charge air via the shortest route from the outlet side, on which the turbine of the exhaust gas turbocharger is often arranged, to the To lead the inlet side.

In this context, embodiments of the supercharged internal combustion engine are advantageous in which the turbine of the at least one exhaust gas turbocharger is a radial turbine. This embodiment also allows a tight packaging of the exhaust gas turbocharger and thus of the supercharger as a whole.

In contrast to turbines, compressors are defined by their outflow. A radial compressor is thus a compressor whose outflow from the rotor blades takes place essentially radially. In the context of the present invention, essentially radial means that the speed component in the radial direction is greater than the axial speed component.

Embodiments of the supercharged internal combustion engine in which the compressor of the at least one exhaust gas turbocharger is an axial compressor can also be advantageous. The outflow from the impeller blades of an axial compressor takes place essentially axially.

Embodiments of the supercharged internal combustion engine are advantageous in which the compressor of the at least one exhaust gas turbocharger has an inlet area which is coaxial with the shaft of the compressor runs and is designed so that the flow of charge air to the compressor takes place essentially axially.

In the case of an axial flow towards the compressor, there is often no diversion or change of direction of the charge air flow in the intake system upstream of the at least one compressor impeller, which avoids unnecessary pressure losses in the charge air flow due to flow deflection and increases the pressure of the charge air at the inlet to the compressor of the exhaust gas turbocharger. The lack of a change in direction also reduces the contact of the exhaust gas or the charge air with the inner wall of the intake system or with the inner wall of the compressor housing and thus reduces the heat transfer and the formation of condensate.

Embodiments of the supercharged internal combustion engine are advantageous in which the return line branches off from the exhaust gas discharge system downstream of the turbine of the at least one exhaust gas turbocharger, forming a second junction. The exhaust gas recirculation is then a low-pressure EGR, the return line of which branches off from the exhaust gas discharge system downstream of the turbine and opens into the intake system upstream of the compressor.

When exhaust gas recirculation is switched on, the exhaust gas flow introduced into the turbine is not reduced by the amount of recirculated exhaust gas, so that the entire exhaust gas flow is always made available to the turbine to generate a sufficiently high boost pressure.

In this context, embodiments of the supercharged internal combustion engine are advantageous in which a first shut-off element is arranged in the exhaust gas discharge system downstream of the second junction. The first shut-off element can be used to increase the exhaust gas pressure upstream in the exhaust gas discharge system, and thus contribute to or be used to increase the pressure gradient between the exhaust gas discharge system and the intake system. This is particularly advantageous in the case of high return rates, which require a greater pressure gradient.

Embodiments of the supercharged internal combustion engine are advantageous in which a second shut-off element is arranged in the intake system upstream of the first node. The second shut-off element serves on the inlet side to reduce the pressure in the intake system and can thus - like the first shut-off element - contribute to an increase in the pressure gradient between the exhaust gas discharge system and the intake system.

Embodiments of the supercharged internal combustion engine in which the first and / or second shut-off element is a pivotable flap are advantageous in this context.

Embodiments of the supercharged internal combustion engine are advantageous in which the intake system has at least one cavity for receiving the phase change material.

The suction system according to the invention must have at least one cavity or at least one container for receiving the phase change material. A cavity or container for receiving the phase change material could be formed as an integral part of the intake system as part of a manufacturing process. The intake system could have a modular structure, with a cavity being formed as part of the assembly, which accommodates the phase change material.

A cavity could be formed by providing the actual suction system with a casing, so that a cavity is formed between the suction system and the at least one spaced-apart casing element in which phase change material is received. The suction system expanded by the casing then comprises the cavity or the container for receiving the phase change material.

For the reasons mentioned above, embodiments of the supercharged internal combustion engine are also advantageous in which the intake system for receiving the phase change material is at least partially double-walled.

The intake system does not have to be a monolithic component into which the at least one cavity is incorporated as an integral part of the manufacturing process. Rather, the intake system is preferably a system built - for example from sheet metal - in which the at least one cavity is formed in the context of the assembly using components or formwork elements arranged at a distance. This also results in the possibility of retrofitting intake systems that are already on the market or already designed.

Embodiments of the supercharged internal combustion engine are advantageous in which the exhaust gas recirculation comprises a shut-off element which is used to adjust the recirculated exhaust gas quantity.

Embodiments of the supercharged internal combustion engine are advantageous in which the shut-off element, which is used to adjust the amount of recirculated exhaust gas, is arranged at the first node.

Particularly advantageous in this context are embodiments which are characterized in that the shut-off element is a combined valve with which both the amount of recirculated exhaust gas and the amount of fresh air can be adjusted. Such a combined valve can comprise, in addition to the valve housing, a pivotable flap and further valve components.

In this context, embodiments of the supercharged internal combustion engine are advantageous in which the shut-off element is equipped with the phase change material as part of the intake system.

If a combined valve is used as the shut-off element, the valve housing and / or the pivotable flap is preferably equipped with the phase change material.

The shut-off element as such or the valve housing also forms the intake system, so that it can be viewed as part of the intake system. According to the above embodiment, the phase change material is placed or provided in the shut-off element or in the valve housing.

Embodiments of the supercharged internal combustion engine are advantageous in which the intake system is equipped with a heating device upstream of the at least one compressor impeller.

A heating device can be activated and used at any time in order to regenerate the phase change material by supplying heat and, if necessary, instead of the phase change material or in addition to the heating of the inner wall of the intake system.

In this context, embodiments of the supercharged internal combustion engine are advantageous in which the heating device comprises at least one electrically heatable wire integrated in the intake system.

This electrical heating device can be supplied with energy independently of the operating state of the internal combustion engine, for example by means of the on-board battery of a vehicle. The wire can already be introduced during the manufacture of the intake system, for example implemented in the intake system. In this way, a high level of heat transfer from the wire into the walls of the intake system is guaranteed or implemented.

In the present context, embodiments of the supercharged internal combustion engine can also be advantageous in which the heating device comprises at least one duct arranged in the intake system and exposed to a fluid. The internal combustion engine usually has several operating fluids that can be used or drawn upon for introducing heat into the intake system, for example the coolant of a liquid cooling system or the oil from an oil circuit of the internal combustion engine.

In this context, embodiments of the supercharged internal combustion engine are advantageous in which the at least one duct can at least be connected to the exhaust gas discharge system. In the present case, the hot exhaust gas is used to introduce heat into the housing, with the exhaust gas being able to be taken from the exhaust gas removal system or the exhaust gas recirculation system.

In the case of supercharged internal combustion engines with liquid cooling, embodiments are also advantageous in this context which are characterized in that the at least one channel can at least be connected to the liquid cooling.

Embodiments of the supercharged internal combustion engine are advantageous in which the first node is formed and arranged in the vicinity of the at least one compressor impeller with the formation of a distance Δ. An arrangement of the first node close to the compressor shortens the path of the hot recirculated exhaust gas from the point of introduction into the intake system to the at least one compressor impeller, so that the time in which condensate droplets can form in the free charge air flow is reduced. This counteracts the formation of condensate droplets.

In this context, embodiments are advantageous in which the following applies to the distance Δ: Δ 1.5Dv, where D _V indicates the diameter of the at least one compressor impeller. Embodiments are advantageous in which the following applies to the distance Δ: Δ 1.0D _V , preferably Δ 0.75D _V.

Embodiments of the internal combustion engine are advantageous in which at least two exhaust gas turbochargers are provided.

The design of the exhaust gas turbocharger often causes difficulties, with a noticeable increase in performance in all speed ranges being aimed for. But it will often be a strong torque drop observed when falling below a certain speed.

This torque drop becomes understandable if it is taken into account that the boost pressure ratio depends on the turbine pressure ratio. If the engine speed is reduced, this leads to a smaller exhaust gas mass flow and thus to a smaller turbine pressure ratio. As a result, the boost pressure ratio also decreases towards lower engine speeds. This is equivalent to a drop in boost pressure or a drop in torque.

The torque characteristics of a supercharged internal combustion engine can also be improved by several turbochargers arranged in parallel, i.e. several turbines with a smaller turbine cross-section arranged in parallel, with turbines being switched on successively as the amount of exhaust gas increases; similar to register charging.

The torque characteristic can also be advantageously influenced by means of several exhaust gas turbochargers connected in series. By connecting two exhaust gas turbochargers in series, of which one exhaust gas turbocharger serves as the high pressure stage and one exhaust gas turbocharger serves as the low pressure stage, the compressor map can be expanded in an advantageous manner, both towards smaller compressor flows and towards larger compressor flows.

In addition to an exhaust gas turbocharger, a mechanical or electrical charger can in principle also be provided.

The second sub-task on which the invention is based, namely to show a method for operating a supercharged internal combustion engine of the type described above, is achieved by a method which is characterized in that the phase change material is activated in order to give off heat in the context of a phase transition for the purpose of heating the intake system and to counteract the separation of condensate; preferably if exhaust gas is returned via a return line.

What has already been said for the internal combustion engine according to the invention also applies to the method according to the invention, which is why reference is generally made at this point to the statements made above with regard to the charged internal combustion engine. The various internal combustion engines sometimes require different process variants.

Method variants in which the phase change material is activated before or during a cold start, for example by means of an ignition key, can be advantageous.

Process variants in which the phase change material is indirectly heated and regenerated by means of compressed charge air are advantageous.

Process variants in which the phase change material is heated and regenerated by means of hot exhaust gas are advantageous.

Process variants in which the phase change material is heated and regenerated by means of heated cooling liquid or hot oil are advantageous.

• 1a schematisch ein Fragment des Ansaugsystems einer ersten Ausführungsform der Brennkraftmaschine mitsamt Abgasrückführleitung, teilweise geschnitten, und
• 1b schematisch das in der 1a dargestellte Ansaugsystem im Querschnitt entlang des in 1a gekennzeichneten Schnittes A-A.

In the following, the invention is based on an exemplary embodiment and according to the 1a and 1b described in more detail. Here shows:

• 1a schematically a fragment of the intake system of a first embodiment of the internal combustion engine including exhaust gas recirculation line, partially in section, and
• 1b schematically that in the 1a Intake system shown in cross section along the in 1a marked section AA.

1a shows schematically a fragment of the intake system 1 a first embodiment of the internal combustion engine including exhaust gas recirculation line 5a , partially cut.

The internal combustion engine has an intake system to supply the charge air to the cylinders 1 and for the purpose of charging the cylinders, an exhaust gas turbocharger is provided, which has a turbine arranged in the exhaust gas discharge system and one in the intake system 1 arranged compressor 2 includes (not shown). The entry area 2a of the compressor 2 is indicated.

The entry area 2a is coaxial with the shaft of the compressor 2 designed so that the flow of charge air to the compressor 2 of the exhaust gas turbocharger takes place essentially axially and the section of the intake system 1 upstream of the compressor 2 shows no changes in direction.

The internal combustion engine is also equipped with exhaust gas recirculation 5 equipped, which has a return line 5a comprises, which branches off downstream of the turbine from the exhaust gas removal system and upstream of the compressor 2 or compressor impeller with the formation of a first node 5c into the intake system 1 flows out.

A shut-off element is used to adjust the amount of recirculated exhaust gas 5b , which is present at the junction 5c arranged and as a combined valve 5b is designed, with which not only the amount of recirculated exhaust gas, but also the amount of fresh air can be adjusted. Such a combined valve 5b comprises a pivotable flap in addition to the valve housing.

The suction system 1 at the first junction 5c , which is also the valve housing of the shut-off element 5b forms is with a phase change material 4th equipped, which is present as a liquid phase or as a solid phase and either absorbs heat or gives off heat as part of a phase transition. Here is the phase change material 4th in a cavity 3 the double-walled suction system 1 placed.

1b shows schematically that in FIG 1a illustrated suction system 1 in cross section along the in 1a marked section AA.

List of reference symbols

1

Suction system

2

Compressor of the exhaust gas turbocharger

2a

Entrance area of the compressor

3

cavity

4th

Phase change material

5

Exhaust gas recirculation

5a

Return line

5b

Exhaust gas recirculation shut-off element, EGR valve, combined valve

5c

first junction

EGR

Exhaust gas recirculation

mAGR

Mass of recirculated exhaust gas

mFresh air

Mass of fresh air or charge air supplied

xACR

Exhaust gas recirculation rate

Claims (22)

Supercharged internal combustion engine with - an intake system (1) for supplying charge air, - an exhaust gas discharge system for discharging exhaust gas, - at least one exhaust gas turbocharger, which comprises a turbine arranged in the exhaust gas discharge system and a compressor (2) arranged in the intake system (1), the compressor (2) is equipped with at least one impeller mounted in a compressor housing on a rotatable shaft, and - an exhaust gas recirculation system (5) comprising a return line (5a) which, upstream of the at least one compressor impeller, enters the intake system (5c) with the formation of a first node (5) 1) opens, characterized in that - the intake system (1) upstream of the at least one compressor impeller is equipped with a phase change material (4) which is present as a liquid phase or as a solid phase, the phase change material (4) either absorbing heat during a phase transition or gives off heat. Supercharged internal combustion engine after Claim 1 , characterized in that the intake system (1) upstream of the compressor housing is equipped with a phase change material (4) which is present as a liquid phase or as a solid phase, the phase change material (4) either absorbing heat or giving off heat during a phase transition. Supercharged internal combustion engine after Claim 1 or 2 , characterized in that the suction system (1) at the first node (5c) is equipped with a phase change material (4) which is present as a liquid phase or as a solid phase, the phase change material (4) either absorbing heat or giving off heat during a phase transition . Supercharged internal combustion engine according to one of the preceding claims, characterized in that the phase change material (4) gives off heat during a phase transition from the liquid phase to the solid phase. Supercharged internal combustion engine according to one of the preceding claims, characterized in that the phase change material (4) absorbs heat during a phase transition from the solid phase to the liquid phase. Supercharged internal combustion engine according to one of the Claims 1 until 3 , characterized in that the phase change material (4) gives off heat during a phase transition from the solid phase to the liquid phase. Supercharged internal combustion engine according to one of the preceding claims, characterized in that the compressor (2) of the at least one exhaust gas turbocharger is a radial compressor. Supercharged internal combustion engine according to one of the preceding claims, characterized in that the compressor (2) of the at least one exhaust gas turbocharger has an inlet area (2a) which runs coaxially to the shaft of the compressor (2) and is designed so that the charge air flows to the Compressor (2) takes place essentially axially. Supercharged internal combustion engine according to one of the preceding claims, characterized in that the return line (5a) branches off from the exhaust gas discharge system downstream of the turbine of the at least one exhaust gas turbocharger, forming a second junction. Supercharged internal combustion engine after Claim 9 , characterized in that a first shut-off element is arranged in the exhaust gas discharge system downstream of the second node. Supercharged internal combustion engine according to one of the preceding claims, characterized in that a second shut-off element is arranged in the intake system (1) upstream of the first node. Supercharged internal combustion engine after Claim 10 or 11th , characterized in that the first and / or second shut-off element is a pivotable flap. Supercharged internal combustion engine according to one of the preceding claims, characterized in that the intake system (1) has at least one cavity (3) for receiving the phase change material (4). Supercharged internal combustion engine according to one of the preceding claims, characterized in that the intake system (1) for receiving the phase change material (4) is at least partially double-walled. Supercharged internal combustion engine according to one of the preceding claims, characterized in that a shut-off element (5b) is arranged at the node (5c), which is used to adjust the amount of recirculated exhaust gas. Supercharged internal combustion engine after Claim 15 , characterized in that the shut-off element (5b) is equipped with the phase change material (4) as part of the intake system (1). Supercharged internal combustion engine according to one of the preceding claims, characterized in that the intake system (1) is equipped with a heating device upstream of the at least one compressor impeller. Supercharged internal combustion engine after Claim 17 , characterized in that the heating device comprises at least one electrically heatable wire integrated in the intake system (1). Supercharged internal combustion engine after Claim 17 , characterized in that the heating device comprises at least one channel which is arranged in the intake system (1) and can be acted upon by a fluid. Supercharged internal combustion engine after Claim 19 , characterized in that the at least one channel can at least be connected to the exhaust gas discharge system. Supercharged internal combustion engine after Claim 19 , in which liquid cooling is provided, characterized in that the at least one channel can at least be connected to the liquid cooling. Method for operating a supercharged internal combustion engine according to one of the preceding claims, characterized in that the phase change material (4) is activated in order to give off heat in the context of a phase transition for the purpose of heating the intake system (1) and to counteract the separation of condensate, if exhaust gas via Return line (5a) is returned.

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