EP3470646A1 - Combustion engine, motor vehicle and method for operating a combustion engine - Google Patents

Abstract

A method for operating an internal combustion engine 10 is provided, wherein the internal combustion engine 10 has at least one internal combustion engine 12, for which an automatic stop function is provided, a fresh gas train 74, an exhaust line 76 and a cooling system. Furthermore is
- In the fresh strand a compressor 98 and between the compressor 98 and the internal combustion engine 12, a charge air cooler 78 integrated, which also integrates into a cooling circuit of the cooling system, and / or
- Provided at least one cooling circuit of the cooling system, the
- A cooling channel 26, 28 of the engine 12 and / or
a radiator 34 for an exhaust gas turbocharger 20 and / or
an EGR cooler 38, 40 integrated into an exhaust gas recirculation line 22, 24.

In addition, it is provided that coolant is conveyed in the cooling circuit or, in the case of different cooling circuits, in at least one of the cooling circuits while the stop function is activated and consequently in a non-operation of the internal combustion engine.

Description

The invention relates to a method for operating an internal combustion engine, an internal combustion engine suitable for carrying out such a method and a motor vehicle having such an internal combustion engine.

An internal combustion engine for a motor vehicle generally has a cooling system in which a coolant is conveyed by means of one or more coolant pumps in at least one cooling circuit and thereby thermal energy of integrated components in the cooling circuit, u.a. an internal combustion engine. This heat energy is, if an operating temperature range of the internal combustion engine has already been reached, then in an ambient heat exchanger, especially the so-called main radiator, and temporarily in a heating heat exchanger to the ambient air, in the case of Heizungswärmetauschers to the provided for air conditioning an interior of the vehicle ambient air delivered.

An internal combustion engine for a motor vehicle may further comprise an exhaust gas recirculation, by means of which a portion of the exhaust gas generated by an internal combustion engine of the internal combustion engine from an exhaust line of the internal combustion engine in a fresh gas train of the engine and can be returned via this in the engine, which in particular certain pollutant emissions during operation of Internal combustion engine to be kept low. The use of a so-called high-pressure exhaust gas recirculation is known in which the associated exhaust gas recirculation line branches off the exhaust line upstream of a turbine of an exhaust gas turbocharger integrated in the exhaust gas line and flows into the fresh gas line downstream of a compressor of the exhaust gas turbocharger integrated into the fresh gas train. Furthermore, the use of a so-called low-pressure exhaust gas recirculation is known, in which the associated exhaust gas recirculation line branches off from the turbine downstream of an exhaust gas turbocharger from the exhaust line and flows upstream of the compressor of the exhaust gas turbocharger in the fresh gas line. In order to avoid a too high temperature of the internal combustion engine supplied fresh gas, which is an activated exhaust gas recirculation is an air-exhaust mixture, it can be provided that in an exhaust gas recirculation an (EGR) cooler is integrated, as a heat exchanger a transition from Heat energy from the recirculated exhaust gas to a heat exchanger also flowing through the coolant allows. Usually, such an EGR cooler is integrated into a cooling system of the internal combustion engine that also encompasses cooling channels of the internal combustion engine.

For the internal combustion engine of a motor vehicle, an automatic stop function or stop / start function can furthermore be provided, in which the internal combustion engine is automatically switched off, provided that no drive power is to be generated by it. On the one hand, this can be the case when the motor vehicle is at a standstill, for example at a traffic light, or when the motor vehicle is coasting out. The internal combustion engine is then automatically restarted as soon as the engine control assumes that drive power is to be generated again by means of the internal combustion engine. This can be determined, for example, by the fact that the driver of the motor vehicle relieves a brake pedal of the motor vehicle and / or actuates a clutch pedal when the motor vehicle is at a standstill and when the stop function is activated and thus when the internal combustion engine is switched off.

Internal combustion engines, which are intended to drive motor vehicles, are usually charged in order to increase the specific power and to reduce the specific fuel consumption. There is widespread charging of internal combustion engines by means of one or more exhaust gas turbochargers. These include a turbine having a turbine runner that is impinged by exhaust gas exhausted from an internal combustion engine of the internal combustion engine and thereby rotationally driven. The turbine wheel drives via a shaft to a compressor impeller of a compressor, which is integrated into a fresh gas line of the internal combustion engine and thereby compresses the fresh gas. Alternatively, such a compressor can also be driven by means of another drive, for example by the internal combustion engine itself or by an electric drive motor. By the compression, inter alia, the amount of introduced into the combustion chambers of the engine fresh gas and thus the amount of convertible in a working cycle in the combustion chamber fuel can be increased. At the same time, however, the temperature and thus the specific volume of the compressed fresh gas is increased by the compression, which counteracts the intended by the compression increase the filling of the combustion chambers. To avoid this, charge air coolers are usually integrated into the fresh gas train downstream of the compressor, which cause at least partial re-cooling of the heated by the compression of fresh gas (charge air). Such a charge air cooler can also be integrated into the cooling system of the internal combustion engine, so that its cooling effect on a Heat transfer from the fresh gas to the intercooler coolant flowing through the cooling system is based.

The DE 196 28 576 A1 discloses a radiator fan for a motor vehicle, in which the fan is driven on the one hand by an internal combustion engine of the motor vehicle and on the other hand by an electric motor integrated in the radiator fan.

The DE 10 2013 111 455 A1 describes a method and systems for reducing the corrosion of an intercooler. In response to a range of condensate formation in a charge air cooler, a grille shutter system is adjusted, with the area of condensate being moved to another location in the charge air cooler. The orientation of the grille shutter system may also be adjusted in response to the operating conditions of the motor vehicle and the condensate-forming weather conditions.

The DE 10 2015 113 476 A1 discloses a cooled by liquid coolant charge air cooler for an internal combustion engine, wherein the liquid coolant is conveyed by means of an electric motor driven coolant pump through the charge air cooler. The delivery rate of the coolant pump is thereby controlled as a function of the temperatures of the air flow entering and leaving the intercooler.

The DE 10 2015 210 615 A1 describes a hybrid vehicle with a supercharged combustion engine and an integrated in a cooling system of the hybrid vehicle intercooler, which is not flowed through during a purely electromotive drive of the hybrid vehicle by coolant.

The invention was based on the object, in an internal combustion engine with an internal combustion engine, for which an automatic stop function is provided to avoid negative effects resulting from an activation of the automatic stop function as possible.

This object is achieved by a method for operating an internal combustion engine according to claim 1. A suitable for automated implementation of such a method internal combustion engine and a motor vehicle with such an internal combustion engine are subject matter of claims 4 and 9. Advantageous embodiments of the method and preferred embodiments of the internal combustion engine according to the invention and thus also of the motor vehicle according to the invention are objects the further claims and / or emerge from the following description of the invention.

• in den Frischstrang ein Verdichter und zwischen dem Verdichter und dem Verbrennungsmotor ein Ladeluftkühler integriert, der zudem in einen Kühlkreis des Kühlsystems integriert ist, und/oder
• mindestens ein Kühlkreis des Kühlsystems vorgesehen, der
  • einen Kühlkanal des Verbrennungsmotors und/oder
  • einen Kühler für einen Abgasturbolader und/oder
  • einen AGR-Kühler, der in eine (aus dem Abgasstrang abgehende und in den Frischgasstrang mündende) Abgasrückführleitung integriert ist, umfasst.

Zudem ist vorgesehen, dass (zumindest zweitweise) während aktivierter Stoppfunktion und folglich in einem Nichtbetrieb des Verbrennungsmotors Kühlmittel in dem Kühlkreis oder, bei unterschiedlichen Kühlkreisen, in zumindest einem der Kühlkreise gefördert wird.According to the invention, a method is provided for operating an internal combustion engine, wherein the internal combustion engine according to the invention comprises at least one internal combustion engine (in particular a diesel engine or a gasoline engine or a combination thereof, ie a combustion engine with homogeneous compression ignition) for which an automatic stop function is provided; an exhaust line and a cooling system. Furthermore is

• in the fresh strand a compressor and integrated between the compressor and the internal combustion engine, a charge air cooler, which is also integrated in a cooling circuit of the cooling system, and / or
• provided at least one cooling circuit of the cooling system, the
  • a cooling passage of the internal combustion engine and / or
  • a cooler for an exhaust gas turbocharger and / or
  • an EGR cooler, which is integrated in a (outgoing from the exhaust line and the fresh gas line opening) exhaust gas recirculation line is integrated.

In addition, it is provided that (at least partly) during activated stop function and consequently in a non-operation of the internal combustion engine, coolant is conveyed in the cooling circuit or, in the case of different cooling circuits, in at least one of the cooling circuits.

In order to enable an implementation of such a method according to the invention, an internal combustion engine according to the invention also has a control device which is designed such that it can perform a method according to the invention (automated).

In the first case, ie if a compressor is integrated in the exhaust gas line and an intercooler between the compressor and the internal combustion engine, the delivery of the coolant in the corresponding cooling circuit serves to overheat the intercooler, in particular due to a still ongoing heat transfer from the Charge air to the intercooler, to avoid. Would the coolant in the intercooler integrating the integrated cooling circuit during activated stop function of the internal combustion engine not further promoted, this would heat relatively strong due to the heat transfer from the charge air, which could lead to a restart of the engine to the fact that the charge air supplied to the engine due to a initially insufficient cooling capacity of the intercooler is temporarily warmer than intended, whereupon possibly with a withdrawal of the EGR rate, ie the proportion of flow rate of the guided via the exhaust gas recirculation line in the fresh gas line exhaust gas on the total exhaust duct led via the exhaust gas, would react, which in turn leads to a temporary deterioration of the pollutant content and in particular to an increase in nitrogen oxides (NO _X ) could result in the exiting the internal combustion engine exhaust gas. This problem is inventively avoided by the ongoing while stop function promotion of coolant through the cooling circuit of the cooling system comprising the intercooler.

In the (alternative or additional) second case, i. if at least one cooling circuit of the cooling system, which comprises a cooling passage of the internal combustion engine and / or a cooling channel of the exhaust gas turbine and / or an EGR cooler, is provided, the delivery of the coolant in this cooling circuit serves to prevent heat accumulation in the cooling system, which Otherwise it could be adjusted, since various integrated into the cooling system of the internal combustion engine components of the internal combustion engine, in particular the internal combustion engine (and in particular a cylinder head of the internal combustion engine), the exhaust gas turbine and the EGR cooler (in particular an EGR cooler for a low-pressure exhaust gas recirculation), may have a high component temperature due to the previous operation of the internal combustion engine and then enter a significant thermal performance in the coolant of the cooling system due to the thermal inertia even during activated stop function of the internal combustion engine. If then the coolant in the cooling system due to the activated stop function and thus the non-operation of the internal combustion engine no longer promoted in the cooling system and thereby not cooled in the main radiator, it could locally come to overheat to boiling of the coolant, which according to the invention can be avoided by the continuous operation of the cooling system in at least one or the said cooling circuit (s).

In order to allow a promotion of coolant in the cooling circuit or even during activated stop function and thus during non-operation of the internal combustion engine, in the cooling circuit or, in various cooling circuits, in at least one of the cooling circuits of the cooling system (optionally, respectively) at least one electric motor or on otherwise be integrated independently of the internal combustion engine drivable coolant pump.

According to a preferred embodiment of a method according to the invention, provision may be made for cooling the coolant in the cooling circuit (s), in which / which coolant is promoted during activated stop function is effected by means of an ambient heat exchanger. As a result, an effective re-cooling of the coolant can be achieved. An internal combustion engine according to the invention may include (if appropriate in each case) an ambient heat exchanger which is integrated in the cooling circuit or, in the case of different cooling circuits, in at least one of the cooling circuits mentioned. It can also be provided that the ambient heat exchanger is associated with a fan, so that a heat transfer sufficiently from the ambient heat exchanger flowing through the coolant to air, which also flows through the ambient heat exchanger and / or, even if it is an inventive Internal combustion engine comprehensive (inventive) motor vehicle is activated with stop function, ie does not drive. However, such an integration of an ambient heat exchanger in the one or more cooling circuits is not absolutely necessary, since possibly already by the promotion of the coolant in the one or more cooling circuits according to the invention aimed at avoiding excessive heating of the charge air cooler and / or a local thermal overload of the cooling system and In particular, the coolant can be avoided, because thereby the heat energy introduced by said components into the coolant can be distributed within the entire cooling system or at least in the sections thereof, which include the one or more cooling circuits, so that already achieved by a sufficient cooling effect and the formation of temperature peaks in the coolant can be avoided.

• in dem den Ladeluftkühler integrierenden Kühlkreis während aktivierter Stoppfunktion derart bewirkt wird, dass sich eine Temperatur des Kühlmittels an einem Austritt des Ladeluftkühlers im Bereich zwischen 70°C und 80°C einstellt, und/oder
• in dem den Kühlkanal des Verbrennungsmotors und/oder den Kühler für den Abgasturbolader und/oder den AGR-Kühler integrierenden Kühlkanal während aktivierter Stoppfunktion derart bewirkt wird, dass sich eine Temperatur des Kühlmittels an zumindest einem Austritt einer dieser Komponenten im Bereich zwischen 95°C und 105°C einstellt.

Diese Temperaturbereiche sind dabei derart gewählt, dass die negativen Effekte, die sich bei unterbrochener Förderung des Kühlmittels in dem oder den genannten Kühlkreisen bei aktivierter Stoppfunktion einstellen würden, in ausreichendem Maße vermieden oder gering gehalten werden und gleichzeitig die für den erfindungsgemäß andauernden Betrieb des Kühlsystems aufzubringende Leistung, die insbesondere zur Förderung des Kühlmittels und gegebenenfalls zum Betrieb eines Gebläses erforderlich ist, gering gehalten wird.According to a further preferred embodiment of a method according to the invention can be provided that a cooling of the coolant

• in which the charge air cooler integrating cooling circuit is effected during activated stop function such that a temperature of the coolant at an outlet of the charge air cooler in the range between 70 ° C and 80 ° C adjusts, and / or
• in which the cooling channel of the internal combustion engine and / or the cooler for the exhaust gas turbocharger and / or the EGR cooler integrating cooling channel is effected during activated stop function such that a temperature of the coolant at least one outlet of one of these components in the range between 95 ° C and 105 ° C.

These temperature ranges are chosen such that the negative effects that would occur in interrupted promotion of the coolant in the one or more cooling circuits with activated stop function, be sufficiently avoided or kept low and at the same time for the inventive operation of the Cooling system applied power, which is necessary in particular for the promotion of the coolant and possibly for the operation of a fan, is kept low.

According to a preferred embodiment of an internal combustion engine according to the invention can be provided that the said cooling circuits are separated, wherein the cooling channel of the internal combustion engine and / or the cooling channel of the exhaust turbine and / or the EGR cooler integrating cooling circuit is designed for a higher operating range of the coolant temperature than the the intercooler integrated cooling circuit. Accordingly, the former cooling circuit may in particular be part of a high-temperature cooling system and the second-named cooling circuit may be part of a low-temperature cooling system separated from the high-temperature cooling system, which each represent sections of the (overall) cooling system. The term "separate" or "separated" design of the cooling circuits or of the (partial) cooling systems is understood to mean that they do not have an integral section, i. no section that is part of either one cooling circuit or cooling system, as well as part of the other cooling circuit or cooling system. However, the separated cooling circuits or cooling systems can be indirectly connected to a common expansion tank, in particular via in each case at least one compensation line and in each case one vent line. In this case, a "reservoir" for the coolant of the cooling system is understood to be a "reservoir", which serves in particular to compensate for temperature-induced expansions of the coolant by changing the fill level of the coolant in the reservoir. For this purpose, such a surge tank may be partially filled in particular with the coolant and partly with a gas, in particular air. An associated vent line may preferably open into a portion of the surge tank in which the gas is present, while a corresponding compensation line opens into a coolant receiving portion to an overflow of coolant between the / the cooling circuit (s) and the surge tank with the primary The aim of the compensation of a temperature-induced expansion of the coolant, possibly also for a first or in the context of maintenance activities provided for filling the (total) cooling system or at least the associated cooling circuits with the coolant to allow.

The cooling channel of the internal combustion engine can be, in particular, a cooling channel of a cylinder head of the internal combustion engine because the cylinder head is generally subject to particularly high thermal stress during operation of the internal combustion engine, thereby having a relatively high component temperature and consequently the risk of local thermal overload for the engine inside the cooling channel of the cylinder head include coolant at activated stop function and interrupted delivery of the coolant can be particularly high.

Another way to avoid a local thermal overload up to a boiling of the coolant, which is basically independent of the other measures described here, but preferably combined with this is used, is in the operation of the cooling system, a defined pressure level for the Keep coolant upright because the boiling temperature is dependent on pressure and thereby increases with increasing pressure. In a closed cooling system, as is currently widely used in internal combustion engines for motor vehicles, the pressure increases from a cold start of the internal combustion engine until reaching the intended operating temperature range for the coolant, wherein limited by the provision of a closed surge tank, the pressure increase, due Compression of the gas therein, however, is not fully relieved, as is the case with an open cooling system or reservoir. If, for example, the coolant still has a relatively low temperature shortly after a cold start of the internal combustion engine, its pressure in the cooling system is still relatively low. If, for example, by a very high load request to the internal combustion engine, locally and in particular in a cylinder head of the engine registered a high thermal performance in the coolant, there is locally the risk of boiling the coolant, causing it can be damaged. To avoid this, it may be provided that in a state of the cooling system during operation of the internal combustion engine, a defined pressure level, which has not yet been reached due to still too low a temperature of the coolant, to actively generate by one or more suitable pressure generating devices. In this case, such a pressure generating device can be actuated in particular as a function of the measuring signal of a pressure sensor, which preferably determines the gas pressure in an expansion tank of the cooling system. Such an active influencing of the pressure of the coolant can be achieved in particular by a corresponding control of one or more coolant pumps of the cooling system, which are in particular electromotively or otherwise independently drivable by the internal combustion engine, optionally in combination with controllable throttles or other flow resistances. Alternatively or additionally, preferably also a pressure generating device can be provided, by which the pressure of the gas contained in the expansion tank can be influenced. For this purpose, such a pressure generating device may comprise a gas conveying device, in particular a compressor, through which additional gas with the aim of increasing the gas pressure in the expansion tank can be introduced. A Such pressure generating device may further preferably have a controllable valve, whereby the gas pressure in the expansion tank can also be selectively reduced again. Alternatively or additionally, a corresponding pressure generating device can also provide means by which the volume and thus the pressure of the gas contained in the expansion tank can be influenced. Such means can, for example, have a wall which at least partially delimits the gas volume, in particular in the form of a membrane, which can be displaced by means of an actuating device in order to change the gas volume.

An inventive motor vehicle comprises at least one internal combustion engine according to the invention, which is preferably provided for generating a traction drive power for the motor vehicle. The motor vehicle may in particular be a wheel-based motor vehicle (preferably a car or a truck).

The indefinite articles ("a", "an", "an" and "an"), in particular in the patent claims and in the description generally describing the claims, are to be understood as such and not as numerical words. Corresponding to this concretized components are thus to be understood that they are present at least once and may be present more than once.

Fig. 1:

ein erfindungsgemäßes Kraftfahrzeug; und

Fig. 2:

eine erfindungsgemäße Brennkraftmaschine schematisch in einem Schaltbild.

The invention will be explained in more detail with reference to an exemplary embodiment shown in the drawings. In the drawings shows:

Fig. 1:

a motor vehicle according to the invention; and

Fig. 2:

an internal combustion engine according to the invention schematically in a circuit diagram.

The Fig. 1 shows a motor vehicle according to the invention with an internal combustion engine 10 according to the invention.

Such an internal combustion engine 10 according to the invention can according to the Fig. 2 an internal combustion engine 12, which may be designed in particular as operating on the diesel principle reciprocating internal combustion engine and which comprises a cylinder housing 14 with cylinders 16 formed therein and a cylinder head 18. Furthermore, the internal combustion engine 10 according to the Fig. 2 still a main cooling system and a secondary cooling system on.

The main cooling system is used for (direct) cooling of the internal combustion engine 12, engine oil for lubrication of the internal combustion engine 12, (gear) oil of the internal combustion engine 12 associated (manual or automatic) gearbox (not shown), an exhaust gas turbocharger 20, in particular a bearing chair or an exhaust gas turbine 96 of the exhaust gas turbocharger 20, as well as exhaust gas, which is recycled either via an exhaust gas recirculation line 22 a low-pressure exhaust gas recirculation or exhaust gas recirculation line 24 of a high-pressure exhaust gas recirculation. The main cooling system includes cooling channels 26, 28 of the cylinder housing 14 and the cylinder head 18, a motor oil cooler 30, a transmission oil cooler 32, a cooler for the exhaust gas turbocharger 20, specifically a cooling channel of the exhaust gas turbine 96 of the exhaust gas turbocharger (ATL cooler) 34, a cooler for a (or a cooling passage in a) exhaust gas recirculation valve 36 and each an EGR cooler in the exhaust gas recirculation line 22 of the low-pressure exhaust gas recirculation (LP EGR cooler 38) and the exhaust gas recirculation line 24 of the high-pressure exhaust gas recirculation (HD EGR cooler 40). Furthermore, the main cooling system comprises a main cooler 42, three coolant pumps 46, 48, 50 and a heating heat exchanger 44. The main cooler 42 serves to recool the coolant flowing through it by the transition of heat energy to ambient air, which also flows through the main cooler 42. On the other hand, the heating heat exchanger 44 serves, if required, ambient air which is used for air-conditioning an interior of a motor vehicle comprising the internal combustion engine 10 (in accordance with, for example, US Pat Fig. 1 ) heated air and thereby temper. Of the three coolant pumps 46, 48, 50 of the main cooling system, one is provided as the main coolant pump 46, which can be driven by an electric motor or, preferably, directly or indirectly by an output shaft (in particular a crankshaft, not shown) of the internal combustion engine 12, ie mechanically. In the case of such a mechanical drive of the main coolant pump 46, it can also be designed to be controllable or controllable with regard to the specific delivery rate (ie in each case related to the input rotational speed) and can also be switched off (ie generating in spite of rotational drive without relevant delivery rate). It can be provided that in the off state of the main coolant pump 46 whose flow is prevented or made possible. The two other (additional) coolant pumps 48, 50 of the main cooling system, however, are driven by an electric motor.

The various heat exchange components as well as the coolant pumps 46, 48, 50 are integrated into different cooling circuits of the main cooling system. A main cooling circuit comprises the cooling passages 26, 28 of the cylinder head 18 and the cylinder housing 14, the main radiator 42, a bypass 52 bypassing the main radiator 42, and the main coolant pump 46 Cooling channels 26, 28 of the cylinder head 18 and the cylinder housing 14 are integrated in parallel in the main cooling circuit. By means of a first control device 54 in the form of a (self-regulating) thermostatic valve (opening temperature: 105 ° C) and by means of a second control device 56 in the form of a controllable by a control device 58 control valve can be influenced whether and to what extent, the cooling channel 26 of the cylinder housing 14 is flowed through by the coolant when the cooling passage 28 of the cylinder head 18 is flowed through. By means of a third control device 60, which is also designed in the form of a controllable by the control device 58 control valve, it can be influenced whether and, if so, to what extent coolant flowing, inter alia, in the main cooling circuit, via the main cooler 42 or the associated bypass 52 is guided. The first, second and third control devices 54, 56, 60 and a fourth control device 62 each form part of a coolant distribution module 108.

Furthermore, a first subcooling circuit is provided, which includes a branch line immediately downstream (with respect to a provided flow direction of the coolant in the main cooling circuit) of an outlet of the cooling channel 28 of the cylinder head 18 from a portion of the main cooling circuit and upstream of the third control device 60 again in a Section of the main cooling circuit opens. The section of the main cooling circuit between the branch and the mouth of this branch line of the first auxiliary cooling circuit is closed by means of the fourth control device 62, which is designed in the form of a controllable by the control device 58 control valve, so that, if necessary, by means of this fourth control device 62, a flow through this portion of the Main cooling circuit (and thus the main cooling circuit in total) can be prevented. In the first auxiliary cooling circuit, a first (48) of the additional coolant pump 48, 50 is integrated. Downstream of this first auxiliary coolant pump 48, the first secondary cooling circuit divides into two parallel strands, wherein in a first of these strands of the LP EGR cooler 38 and downstream of the heater core 44 are integrated, and in the second strand of the ATL cooler 34th is integrated. The two strands of the branch line of the first auxiliary cooling circuit are merged again before their mouth in the main cooling circuit.

The main cooling system further comprises a second auxiliary cooling circuit. A branch line of the second auxiliary cooling circuit, in which the radiator (cooling channel) is integrated for the exhaust gas recirculation valve 36, goes off in the vicinity of the outlet of the cooling channel 28 of the cylinder head 18, wherein in this branch a throttle 64 for limiting the amount of the second secondary cooling circuit flowing through Coolant is integrated. The secondary line of the second auxiliary cooling circuit opens upstream of the main coolant pump 46 (and downstream of the main cooler 42 and upstream of the mouth of the bypass 52 belonging to the main radiator 42) into a section of the main cooling circuit.

A third auxiliary cooling circuit comprises a branch line which branches off in the region of the branch between the cooling channels 26, 28 of the cylinder head 18 and the cylinder housing 14 and upstream of the main coolant pump 46 (and downstream of the main cooler 42 and the mouth of the bypass 52 belonging to the main cooler 42) opens into a section of the main cooling circuit. In this branch line of the engine oil cooler 30 is integrated.

A fourth subcooling circuit comprises a branch line which leaves the branch line of the third subcooling circuit and which integrates a fifth control device 66 in the form of a thermostatic valve (opening temperature: for example 75 ° C.) and the transmission oil cooler 32. The branch line of the fourth auxiliary cooling circuit also flows upstream of the main coolant pump 46 (and downstream of the main cooler 42 and upstream of the mouth of the bypass 52 belonging to the main cooler 42) into a section of the main cooling circuit.

A fifth subcooling circuit of the main cooling system comprises a branch line, which leaves upstream of the first auxiliary coolant pump 48 from the branch line of the first secondary cooling circuit and the second auxiliary coolant pump 50 and downstream of the HD-EGR cooler 40 integrated. Downstream of the HD EGR cooler 40, a sixth controller 68 is arranged in the form of a thermostatic valve (switching temperature, for example, between 70 ° C and 80 ° C). By means of this sixth control device, coolant that has passed through the HP-EGR cooler 40, temperature-dependent on either an end portion of the branch line of the EGR cooling circuit or on a short-circuit line 70, which opens upstream of the second auxiliary coolant pump 50 in an initial section of the branch line of the fifth auxiliary cooling circuit , be split.

The auxiliary cooling system serves to cool the fresh gas (charge air) charged by a compressor 98 of the exhaust gas turbocharger 20, which is supplied to the internal combustion engine 12 via a fresh gas train 74 of the internal combustion engine 10, and a metering valve 72, by means of which a reducing agent in exhaust gas, the exhaust line 76 of the Internal combustion engine 10 flows through, can be introduced to achieve by means of selective catalytic reduction, a reduction of pollutants, in particular of nitrogen oxides, the exhaust gas. The provided for cooling the charge air charge air cooler 78 on the one hand and provided for cooling the metering valve 72 cooling channel on the other hand are integrated in parallel strands of a cooling circuit of the secondary cooling system. Furthermore, in these Cooling circuit (in that section, which is not divided into the two strands), an electric motor driven coolant pump 80 and an additional cooler 82, which serves to recool the coolant flowing through the cooling circuit of the secondary cooling system by a transition of heat energy to the additional cooler 82 by flowing ambient air integrated. The additional cooler 82 is bypassable by means of a bypass 84, wherein a division of the coolant flowing through the cooling circuit of the secondary cooling system on either the additional cooler 82 or the associated bypass 84 by means of a seventh control device 86, which may be formed as a thermostatic valve or as controllable by a control unit control valve, is changeable.

The temperature of the coolant during a regular operation of the internal combustion engine 10 in the main cooling system can be at least partially significantly higher than in the secondary cooling system, so that the former can also be referred to as a high-temperature cooling system and the latter as a low-temperature cooling system.

The cooling system further includes a surge tank 88, which is partially filled with the coolant and partly with air. Via a connecting line 90, which emerges from a coolant receiving (lower) portion of the surge tank 88, the surge tank 88 is fluidly connected both to the main cooling circuit of the main cooling system and to the cooling circuit of the secondary cooling system. Further connect vent lines 92, with the interposition of either one or more check valves 94 or a throttle 64, the HD-EGR cooler 40, the main cooler 42, the cooling channel 28 of the cylinder head 18 and the intercooler 78 with the air receiving (upper) portion of Expansion tank 88.

The main cooling system of the cooling system according to the Fig. 1 For example, it can be operated as follows.

During a warm-up phase, in particular after a cold start of the internal combustion engine, if consequently the coolant in the entire cooling system has a relatively low temperature, it may be provided not to operate the main coolant pump 46, whereby or in addition this is switched off and consequently can not be flowed through. At the same time, during this warm-up phase, the first auxiliary coolant pump 48 (variable capacity) may be operated, thereby delivering coolant (in conjunction with an interrupting position of the fourth controller 62) in the first subcooling circuit. The coolant flows through the integrated into the branch line of the first auxiliary cooling circuit ATL cooler 34, the LP EGR cooler 38 and the heater core 44. Further, this coolant (fully) flows through the bypass 52, which also constitutes a portion of the first auxiliary cooling circuit, to the main water cooler 42 (due to a corresponding position of the third control device 60) the branch line of the third auxiliary cooling circuit (in a flow direction opposite to that in a regular operation, see arrowhead without filling), wherein a flow through the engine oil cooler 30 can optionally be prevented by the integration of a corresponding bypass (not shown) in this branch line and the cooling passage 28 of the cylinder head 18. A flow through the cooling channel 26 of the cylinder housing 14, with the exception of a relatively small pilot flow for temperature control of the formed as a thermostat valve first control device 54 is prevented by appropriate positions of the first control device 54 and the second control device 56 in the rule. In exceptional situations, especially if, despite the warm-up phase, an operation of the internal combustion engine 12 with high loads, especially full load, is provided, but can also be provided to adjust the second control device 56 by means of the control device 58 in a releasing position to also flow through the cooling channel 26 of the cylinder housing 14 to ensure. Depending on the temperature of the coolant flowing through the first secondary cooling circuit, a flow through the secondary branch of the fourth auxiliary cooling circuit and consequently of the transmission oil cooler 32 is at least initially prevented during the warm-up phase by means of the fifth control device 66.

As a result of the flow through the likewise a portion of the first auxiliary cooling circuit performing cooling channel 28 of the cylinder head 18 and the second auxiliary cooling circuit with the integrated therein cooler (cooling passage) for the exhaust gas recirculation valve 36 is flowed through.

During the warm-up phase, provision is further made for the sixth control device 68 to be set in such a way that coolant is conveyed by means of the second auxiliary coolant pump 50 operated in the short-circuit circuit which otherwise only contains the HD EGR cooler 40 and the short-circuit line 70.

During a regular operation of the internal combustion engine 10, the main coolant pump 46 is operated (variable specific delivery capacity) and coolant is at least temporarily conveyed in all of the cooling circuits of the main cooling system. The two additional coolant pumps 48, 50 of the main cooling system can also be operated if necessary to support the main coolant pump 46. For the second auxiliary coolant pump 50, however, this only applies after the sixth control device 68 has switched over in such a way that a flow of coolant is permitted in the fifth cooling circuit. Before this is provided, the second auxiliary coolant pump 50 is operated to deliver coolant (even during a regular operation of the internal combustion engine 10) within the short circuit.

During a normal operation of the internal combustion engine 10, the main cooling circuit is continuously flowed through, whereby a flow through the cooling channel 28 of the cylinder head 18 is always provided, whereas a flow of the cooling channel 26 of the cylinder housing 14 (unless in exceptional situations, the second control device 56 is adjusted to the releasing position ) is released only by means of the first control device 54, when the temperature of the coolant in the cooling channel 26 of the cylinder housing 14 has reached the temperature of about 105 ° C.

By means of the third control device 60, a variable distribution of the coolant flowing through the main cooling circuit to either the main radiator 42 or the associated bypass 52 during normal operation of the internal combustion engine 10, whereby a target temperature for the coolant of approximately 90 ° leaving the cooling channel 28 of the cylinder head 18 C can be adjusted.

During the regular operation of the internal combustion engine 10, the first auxiliary cooling circuit with the integrated ATL cooler 34, the LP EGR cooler 38 and the heating heat exchanger 44 is also permanently flowed through. By adapted operation of the first auxiliary coolant pump 48, the volumetric flow of the coolant through the secondary line of the first auxiliary cooling circuit can also be adjusted in overlay to the delivery rate of the main coolant pump 46. This can be relevant in particular for achieving a sufficient heat transfer in the heating heat exchanger 44 and thus a sufficient heating functionality for the interior heating of a motor vehicle comprising the internal combustion engine 10.

The second auxiliary cooling circuit with the radiator (cooling channel) integrated therein for the exhaust gas recirculation valve 36 and the third auxiliary cooling circuit with the engine oil cooler 30 integrated therein are also flowed through permanently.

For the fourth auxiliary cooling circuit with the transmission oil cooler 32 integrated therein, on the other hand, this applies only if the temperature of the coolant applied to the fifth control device 66, which is likewise integrated into the branch line of the fourth auxiliary cooling circuit, is at least 75 ° C., so that then the fifth control device 66 (depending on the temperature variable) one Flow also allows the transmission oil cooler 32. Again, in the occluding position, a relatively small pilot flow for temperature control of designed as a thermostat valve fifth control device 66 may be provided.

The fifth secondary cooling circuit is only flowed through when the temperature of the previously promoted in the short circuit coolant has reached at least the associated limit temperature, which may be between 70 ° C and 80 ° C. As soon as the sixth control device 68 has released an at least partial flow through the fifth cooling circuit, the HD EGR cooler 40 is permanently charged with coolant whose temperature essentially corresponds to that which was reached in the outlet of the cooling channel 28 of the cylinder head 18 and which in particular is approx 90 ° C.

For the cooling channel 26 of the cylinder housing 14, for the branch line of the fourth auxiliary cooling circuit and thus the transmission oil cooler 32 and for the branch line of the EGR cooling circuit is that the respective flow through the corresponding control devices 54, 66, 68 can be interrupted again, if the respective associated limit or opening temperature has been fallen below.

A flow through the cooling circuit of the secondary cooling system is effected by means of the integrated coolant pump 80 as needed and independently of the controls / regulations of the main cooling system.

The cooling system of the internal combustion engine 10 also allows Nachheizfunktionalität no longer running internal combustion engine 12 by coolant is conveyed by the first auxiliary coolant pump 48 in which then possibly also the main cooler 42 comprehensive first subcooling circuit, whereby the still in particular the main radiator 42, the cylinder head 18 and The ND-EGR cooler 38 contained heat energy in the heating heat exchanger 44 for controlling the temperature of the interior of a motor vehicle 10 comprehensive motor vehicle can be used.

Furthermore, the cooling system also allows a Nachkühlfunktionalität with no longer operated, previously thermally highly loaded internal combustion engine 12 by coolant is promoted by the first auxiliary coolant pump 48 in the then also the main cooler 42 comprehensive first subcooling circuit, whereby the thermally critical components of the cooling system, in particular the cylinder head 18 and the exhaust gas turbocharger 20 (by means of the ATL cooler 34) and the LP EGR cooler 38, can be post-cooled.

This aftercooling functionality may be relevant in particular in connection with an automatic stop function for the internal combustion engine 12. As a result of the automatic stop function, the internal combustion engine 12 is automatically switched off during operation of the internal combustion engine 10 or of the motor vehicle comprising the internal combustion engine 10, provided that no drive power is to be generated therefrom. To during a stop function activated and thus in the non-operation of the internal combustion engine 12, a local thermal overload of the main cooling system and the components integrated therein, in particular the engine 12, the LP EGR cooler 38 and the ATL cooler 34, the particular extent in the previous Operation of the internal combustion engine 12 may have been subjected to high thermal load, it is intended to promote coolant by operating the first auxiliary coolant pump 48 in the first secondary cooling circuit. Depending on the positions of the control devices 66, 68 and the switching position for the permeability of the main coolant pump 46 while the transmission oil cooler 32, the engine oil cooler 30, the main coolant pump 46 and the cooling channels 26 of the cylinder housing 14 are flowed through. Partially the direction of the flow (see direction arrows without filling in the Fig. 2 vice versa in comparison to the direction of flow (see directional arrows with filling in the Fig. 2 During the operation of the internal combustion engine 12, it may be provided that the entire coolant flowing in the first secondary cooling circuit is routed via the main cooler 42. By means of the third control device 60, however, also a variable proportion (up to the total amount) of this coolant can be guided via the bypass 52. As a result, in particular overcooling of the coolant during prolonged non-operation of the internal combustion engine 12 due to an activated stop function can be avoided.

Alternatively or additionally, it is provided that the coolant during a non-operation of the internal combustion engine 12 due to an activated stop function by means of the coolant pump 80 is also conveyed in the cooling circuit of the secondary cooling system, whereby excessive heating of the charge air cooler 78 is avoided. When the internal combustion engine 12 is restarted as a result of a manual or automatic deactivation of the automatic stop function, the charge air cooler 78 can again directly apply sufficient cooling power for the charge air to be supplied to the internal combustion engine 12, so that it is supplied to the combustion chambers of the internal combustion engine 12 in the temperature range provided for this purpose , By means of the seventh control device 86, it can be varied which portion of the coolant flowing in the cooling circuit of the secondary cooling system is conducted via the additional cooler 82 or via the associated bypass 84 on the one hand to achieve a sufficient cooling capacity for the particular intercooler 78 and on the other hand to avoid excessive cooling of the coolant.

Furthermore, it is provided for the internal combustion engine 10, that at certain transient operating conditions of the internal combustion engine 12, specifically at an increase in the load requirement, which is placed on the operation of the engine 12, by at least 20% based on the full load, the temperature of the in the cooling circuit of By-cooling system flowing cooling system is lowered by, for example, about 20 ° C compared to the previous stationary operation to achieve by means of such a realized increase in the cooling capacity of the charge air cooler 78 an improved filling of the combustion chambers of the engine 12 and consequent improved charge pressure build-up, whereby the dynamic operating behavior of the internal combustion engine 12 is improved.

In order to lower the temperature of the coolant flowing in the cooling circuit of the secondary cooling system, an increased proportion of the coolant arriving at the seventh control device 86 is led via the auxiliary radiator 82, if possible. Furthermore, provision may be made for a fan 106 assigned to the additional cooler 82 to be put into operation or to increase its drive power, as a result of which the cooling capacity of the additional cooler 82 can be increased.

In the exhaust line 76 of the internal combustion engine 10, a NO _x storage catalyst 100 and a particulate filter 102 is further integrated. The NOx storage catalyst 100 serves to store nitrogen oxides contained in the exhaust gas, if they can not be sufficiently reduced by the introduced reducing agent in combination with a reduction or SCR catalyst, not shown. This may for example be the case after a cold start of the internal combustion engine 10 or at a relatively long-lasting operation of the internal combustion engine 12 with low loads and speeds, whereby the SCR catalyst is not or no longer has a required for a sufficient reduction operating temperature. By contrast, the particle filter 102 serves to filter out particles from the exhaust gas.

For both the NO _x storage catalyst 100 and for the particulate filter 102 applies that they must be regenerated when reaching a defined load limit in order to maintain their operability. In the case of a NO _x storage catalytic converter 100, it must be added that this must be desulphurized at regular intervals because the sulfur usually contained in the fuel is compatible with the storage material of the NO _x storage catalytic converter 100 react, whereby the amount of storage material available for the storage of nitrogen oxides decreases. For desulfurization, the NO _x storage catalytic converter 100 must be heated, inter alia, by targeted measures to a temperature which is between 600 ° C. and 650 ° C. Comparable temperatures are also required for regeneration of the particulate filter 102.

The heating of the NO _x storage catalyst 100 and the particulate filter 102 to the temperatures required for desulfurization or regeneration takes place by a corresponding increase in the temperature of the exhaust gas, for which various, basically known, in particular internal engine measures are provided.

While the temperature of the exhaust gas is increased correspondingly to effect the desulfurization of the NO _x storage catalyst 100 and the regeneration of the particulate filter 102, a significantly increased thermal power is input to the engine 12 (specifically, directly due to the increase in the temperature of the Exhaust gas effecting internal engine measures) as well as in the entire main cooling system or at least in one or more sections thereof, namely on the one hand via the internal combustion engine 12 and on the other hand via the two EGR cooler 38, 40 introduced.

In order to avoid a local thermal overload of the cooling system, in particular in the area of the internal combustion engine 12 (in particular boiling of the coolant should be avoided), it is provided briefly before and at least temporarily during a desulphurization of the NO _x storage catalyst 100 and / or the Regeneration of the particulate filter 102 provided increase the temperature of the exhaust gas, a temperature of the coolant, specifically that of the coolant, which is to be routed via the main coolant pump 46 into the internal combustion engine 12 to lower the increased thermal load of the engine 12 and the main cooling system due to the increase of Compensate temperature of the exhaust gas. The temperature of the coolant is measured by means of a temperature sensor 104, which is integrated into the outlet of the cooling channel 28 of the cylinder head 18.

In order to lower the temperature of the coolant flowing into the internal combustion engine 12, if possible, an increased proportion of the coolant arriving at the third control device 60 is guided via the main cooler 42. Furthermore, it can be provided to take a main cooler 42 associated fan 106 in operation or the To increase drive power, whereby the cooling capacity of the main radiator 42 can be increased.

Shortly before, at the same time or shortly after the measure of the desulfurization of the NO _x storage catalytic converter 100 and / or the regeneration of the particulate filter 102 is increased, the temperature of the exhaust gas is terminated, the reduction of the temperature of the coolant is also terminated or reversed, To avoid excessive cooling of the components integrated into the main cooling system by the coolant.

LIST OF REFERENCE NUMBERS

10

Internal combustion engine

12

internal combustion engine

14

cylinder housing

16

cylinder

18

cylinder head

20

turbocharger

22

Exhaust gas recirculation line of the low-pressure exhaust gas recirculation

24

Exhaust gas recirculation line of the high-pressure exhaust gas recirculation

26

Cooling channel of the cylinder housing

28

Cooling channel of the cylinder head

30

Engine oil cooler

32

Transmission oil cooler

34

ATL cooler

36

Exhaust gas recirculation valve

38

LP EGR cooler

40

HP EGR cooler

42

Ambient heat exchanger / main radiator

44

Heater core

46

Main coolant pump

48

first auxiliary coolant pump

50

second auxiliary coolant pump

52

Bypass to the main cooler

54

first control device

56

second control device

58

control device

60

third control device

62

fourth control device

64

throttle

66

fifth control device

68

sixth control device

70

Short-circuit line

72

metering valve

74

Fresh gas line

76

exhaust gas line

78

Intercooler

80

Coolant pump of the secondary cooling system

82

Ambient heat exchanger / Additional coolers

84

Bypass to the additional cooler

86

seventh control device

88

surge tank

90

connecting line

92

vent line

94

check valve

96

Exhaust gas turbine of the exhaust gas turbocharger

98

Compressor of the exhaust gas turbocharger

100

NO _X storage catalyst

102

particulate Filter

104

temperature sensor

106

fan

108

Coolant Distribution Module

Claims (9)

Method for operating an internal combustion engine (10) with an internal combustion engine (12) for which an automatic stop function is provided, a fresh gas train (74), an exhaust line (76) and a cooling system, wherein - In the fresh strand (74) is a compressor (98) and between the compressor (98) and the internal combustion engine (12) a charge air cooler (78) is integrated, which is also integrated in a cooling circuit of the cooling system, and / or - A cooling circuit of the cooling system, the - A cooling channel (26, 28) of the internal combustion engine (12) and / or - A cooler (34) for an exhaust gas turbocharger (20) and / or an EGR cooler (38, 40), which is integrated in an exhaust gas recirculation line (22, 24), is provided, characterized in that during activated stop function coolant in the cooling circuit or, in different cooling circuits, is conveyed in at least one of the cooling circuits. A method according to claim 1, characterized in that a cooling of the coolant in the one or more cooling circuits in which / which coolant is promoted during activated stop function, by means of an ambient heat exchanger (42, 82) is effected. A method according to claim 2, characterized in that a cooling of the coolant - In which the charge air cooler (78) integrating cooling circuit is effected during activated stop function such that a temperature of the coolant at an outlet of the charge air cooler (78) in the range between 70 ° C and 80 ° C, and / or in which the cooling channel (26, 28) of the internal combustion engine (12) and / or the cooler (34) for the exhaust gas turbocharger (20) and / or the EGR cooler (38, 40) integrating cooling circuit is effected during activated stop function such a temperature of the coolant at at least one outlet of one of these components is in the range between 95 ° C and 105 ° C. Internal combustion engine (10) having an internal combustion engine (12), a fresh gas train (74), an exhaust line (76) and a cooling system comprising an ambient heat exchanger, wherein - In the fresh gas train a compressor (98) and between the compressor (98) and the internal combustion engine (12) a charge air cooler (78) is integrated, which is also integrated in a cooling circuit of the cooling system, and / or - At least one cooling circuit, the - A cooling channel (26, 28) of the internal combustion engine (12) and / or - A cooler (34) for an exhaust gas turbocharger (20) and / or an EGR cooler (38, 40), which is integrated in an exhaust gas recirculation line (22, 24), is provided, characterized by a control device (58) adapted to execute a method according to any one of the preceding claims. Internal combustion engine (10) according to claim 4, characterized in that in the cooling circuit or, in different cooling circuits, in at least one of the cooling circuits, an ambient heat exchanger (42, 82) is integrated. Internal combustion engine (10) according to claim 4 or 5, characterized in that in the cooling circuit or, in various cooling circuits, in at least one of the cooling circuits, an electric motor driven coolant pump (48, 50, 80) is integrated. Internal combustion engine (10) according to one of claims 4 to 6, characterized in that the cooling circuits are separated, wherein the cooling channel (26, 28) of the internal combustion engine (12) and / or the radiator (34) of the exhaust gas turbocharger (20) and / or the EGR cooler (38, 40) integrating cooling circuit is designed for a higher operating range of the coolant temperature than the intercooler (78) integrating the cooling circuit. Internal combustion engine (10) according to one of claims 4 to 7, characterized in that the cooling channel (26, 28) of the internal combustion engine (12) is a cooling passage (28) of a cylinder head (18) of the internal combustion engine (12). Motor vehicle with an internal combustion engine (10) according to one of claims 4 to 8.

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