DE10319333B4 - System and method for influencing the intake gas temperature in the combustion chamber of an internal combustion engine - Google Patents

Abstract

System for influencing the Ansauggastemperatur and thus the energy level in the combustion chamber (12) of an internal combustion engine (10), in particular a HCCI-capable internal combustion engine (10), with
- An exhaust gas recirculation device (14) with an exhaust gas recirculation valve for supplying exhaust gas of an earlier combustion cycle to fresh air or to a fresh air mixture having to provide after injection of fuel, an air / fuel / exhaust gas mixture with an advantageous energy level for combustion, and
At least one heat exchanger acting as an exhaust gas cooler (32) for lowering the temperature of the recirculated exhaust gas,
characterized,
in that a decoupling of the amount of intake gas supplied to the internal combustion engine (10) from the temperature of the intake gas and a specific adjustment of the energy level in the combustion chamber (12) are achieved by providing a coolant control valve (50) so that the coolant flow through the exhaust gas cooler (32 ), taking into account measured values or values derived from the model, the intake gas temperature can be adjusted or regulated.

Description

The The invention relates to a system for influencing the intake gas temperature and thus the energy level in the combustion chamber of an internal combustion engine, especially an HCCI-enabled Internal combustion engine, with an exhaust gas recirculation device with an exhaust gas recirculation valve for feeding from exhaust of an earlier one Combustion cycle to fresh air or to a fresh air having mixture after injection of fuel an air / fuel / exhaust gas mixture with a for to provide the combustion advantageous energy level, and at least one as an exhaust gas cooler acting heat exchanger for lowering the temperature of the recirculated exhaust gas.

The The invention further relates to a method for influencing the Intake gas temperature and thus the energy level in the combustion chamber of a Internal combustion engine, in particular a HCCI-capable internal combustion engine, at the exhaust of an earlier combustion cycle Fresh air or a fresh air mixture having is fed after injection of fuel an air / fuel / exhaust gas mixture with a for to provide the combustion advantageous energy level, and Exhaust gas in one as an exhaust gas cooler acting heat exchanger is cooled to lower the temperature of the recirculated exhaust gas.

in the Connection with gasoline direct injection systems are different Operating conditions known. This is common that a direct injection of fuel under high pressure directly into a combustion chamber. The Gemischbil tion then takes place within the combustion chamber. Conventionally different the operating modes homogeneous operation and shift or lean operation. At the Homogenous operation is homogeneous over the entire combustion chamber distributed mixture before. During shift or lean operation lies only in the area of the spark plug a mixture with an air ratio λ ≤ 1. The remaining volume of the combustion chamber is with sucked fresh air, an inert gas from the exhaust gas recirculation or a very lean air-fuel mixture filled so that total gives an air ratio of λ> 1.

Next this conventional Operating modes is increasingly becoming another mode of operation than promising assessed, the operation of the self-igniting Diesel engine resembles. This is called HCCI mode (Homogeneous Charge Compression Ignition) known and provides a self-igniting combustion process in which the ignition timing and thus the combustion process over the reactive energy amount is controlled in the cylinder. To provide a sufficient level of energy, you usually use an exhaust gas recirculation via external Adjusting means in the context of an external exhaust gas recirculation or by a suitable Gas exchange valve control as part of an internal exhaust gas recirculation.

at the setting of the temperature level and thus the energy level in the combustion chamber over the Exhaust gas recirculation rate is However, to take into account that this can only be done within certain limits. Because the exhaust gas recirculation rate is not only the temperature level in the combustion chamber but also the mixing ratio of Air, fuel and exhaust are affected, it may not be possible, the exhaust gas recirculation rate both with regard to the temperature in the combustion chamber as well as with regard to to the said mixing ratio optimal to choose.

Consequently can Compromises in setting the exhaust gas recirculation rate become necessary a reliable one To ensure operation of the internal combustion engine.

in the Related to conventional ignited Internal combustion engines have already been proposed, a cooled exhaust gas recirculation use this cooling the exhaust gas in particular to a reduction of nitrogen oxide emissions aimed. For this purpose, for example, on MTZ Motortechnische Zeitschrift 60 (1999) 7/8, page 470 et seq.: "Compliance with future emissions regulations by chilled Exhaust gas recirculation "by Karl-Heinrich Lösing and Rainer Lutz.

Of the Invention is based on the object, the disadvantages of the prior art to eliminate technology and in particular a system and a procedure to disposal through which the operating behavior of an internal combustion engine considering the energy level in the combustion chamber and the amount of intake gas supplied improves becomes.

These The object is achieved by the features of the independent claims.

advantageous embodiments of the invention are in the dependent claims specified.

The invention is based on the generic system in that a decoupling of the internal combustion engine supplied Ansauggasmenge of the temperature of the intake gas and a targeted adjustment of the energy level can be achieved in the combustion chamber by a coolant control valve is provided so that by influencing the coolant flow through the exhaust gas cooler Taking account of measured values or values determined by the model, the intake gas temperature can be adjusted or regulated. The recirculated exhaust gas Quantity is therefore no longer necessarily coupled to the temperature increase achieved in the combustion chamber with the exhaust gas recirculation. On the contrary, the energy content in the combustion chamber can be set within certain limits independently of the exhaust gas recirculation rate by way of the adjustable exhaust gas cooling. Thus, both the mixing ratio and the energy level in the combustion chamber can be optimally adjusted.

The inventive system is advantageously further developed in that the exhaust gas cooler in arranged a separate heat exchanger circuit is. The exhaust gas cooler can thus be self-sufficient without interference from other components of the motor vehicle work. Likewise, there is no influence on other components of the cooling system of the Vehicle through the exhaust gas cooler instead of. The self-sufficient cooling circuit then includes a separate cooler and a separate coolant pump.

It but it can also be useful be that the exhaust gas cooler in an engine coolant circuit is arranged. In this way, components of the engine coolant circuit for the exhaust gas cooling be used so that overall an efficient system is realized becomes.

As well can be provided that the exhaust gas cooler as engine or Transmission oil heat exchanger is designed. This can also be existing Components of the vehicle be shared.

• – Abgastemperatur,
• – zurückgeführte Abgasmasse beziehungsweise -menge,
• – Frischgastemperatur,
• – Frischgasmasse beziehungsweise -menge,
• – Ansauggastemperatur,
• – Ansauggasmasse beziehungsweise -menge,
• – Kühlmitteltemperatur beziehungsweise Öltemperatur des durch den Abgaskühler strömenden Kühlmittels beziehungsweise Öls und
• – Kühlmittelmasse beziehungsweise Ölmasse beziehungsweise Kühlmittelmenge beziehungsweise Ölmenge des durch den Abgaskühler strömenden Kühlmittels beziehungsweise Öls.

The invention is further developed in a particularly advantageous manner in that the measured values or the values determined by the method are assigned to at least one of the following variables:

• - exhaust gas temperature,
• - recirculated exhaust gas mass or quantity,
• - fresh gas temperature,
• Fresh gas mass or quantity,
• Intake gas temperature,
• - intake gas mass or quantity,
• - Coolant temperature or oil temperature of the coolant flowing through the exhaust gas cooler or oil and
• - Coolant mass or oil mass or coolant amount or amount of oil flowing through the exhaust gas cooler or oil.

If hereinafter the term "quantity" is used can also be meant a "mass" and vice versa. The current exhaust gas temperature and the recirculated exhaust gas quantity are known in modern engine controls as engine operating variables. she can either calculated by the model or via appropriate sensors be measured directly. The same applies to the amount of fresh gas and the fresh gas temperature. The coolant temperatures and the oil temperatures are also known. Furthermore, is the amount of coolant or the amount of oil known by the exhaust gas heat exchanger flows, can in knowledge of the heat exchanger characteristic the exhaust gas temperature at the heat exchanger outlet and thus the mixing temperature of the intake air are determined.

When especially useful It has been found that a temperature sensor for detecting the Fresh gas temperature, a temperature sensor for detecting the exhaust gas temperature occurs at the engine, an air mass or quantity measuring device for Detecting the fresh gas mass or quantity and an exhaust gas mass or quantity measuring device for detecting the exhaust gas mass or quantity are provided. Let out of these sizes in the knowledge of certain models or specific characteristics the essential quantities for a reliable regulation determine the intake gas temperature.

m ._FG:

Frischgasmassenstrom

m ._A:

Abgasmassenstrom

T_FG:

Frischgastemperatur

T_AG:

Abgastemperatur

C_p,FG:

Wärmekapazität des Frischgases

C_p,AG:

ärmekapazität des Abgases.

Thus, the system is usefully developed by calculating the intake gas temperature taking into account the following parameters:

m. _FG :

Fresh gas mass flow

m. _A :

Exhaust gas mass flow

T _FG :

Fresh gas temperature

T _AG :

exhaust gas temperature

C _{p, FG} :

Heat capacity of the fresh gas

C _{p, AG} :

heat capacity of the exhaust gas.

The Ansauggastemperatur can thus in knowledge of measured, known or likewise already calculated model-wise sizes become.

Q .:

Wärmestrom

KM:

Kühlmittel

AG:

Abgas

WT:

Wärmetauscher

C_p:

Wärmekapazität

k:

Wärmedurchgangskoeffizient des Wärmetauschers

A:

Heizfläche des Wärmetauschers

ΔT_m:

mittlere logarithmische Temperaturdifferenz.

In this context, it is useful that the exhaust gas temperature at the heat exchanger exit be calculated using the following equation system: | ΔQ. KM = | Q. AG | = Q. WT | Q. KM = m. KM C p, KM (T KM, AUS - T KM, ON ) Q.Q AG = m. AG C p, AG (T AG, A - T AG, AUS ) Q. WT = kAΔT m in which

Q .:

heat flow

KM:

coolant

AG:

exhaust

WT:

heat exchangers

C _p :

heat capacity

k:

Heat transfer coefficient of the heat exchanger

A:

Heating surface of the heat exchanger

.DELTA.T _m:

mean logarithmic temperature difference.

From the knowledge of the characteristic of the heat exchanger, that is to say in particular with knowledge of the parameters k and A, the heat flow Q _WT present in the heat exchanger can be calculated taking into account the average logarithmic temperature difference ΔT _m . This results in knowledge of mass flows, heat capacities and other temperatures, the exhaust gas temperature at the heat exchanger outlet T _{AG, OFF} .

The system according to the invention is further developed in a particularly useful manner in that a compression device is provided for compressing fresh intake air, which has a temperature T ₁ before compression, that expansion means are provided, which cause expansion of the compressed intake fresh air, wherein the compressed and subsequently expanded fresh air has a temperature T ₂ > T ₁ , and that the temperature increase of the fresh air from T ₁ to T ₂ for influencing the Temperaturni veaus and thus the energy level in the combustion chamber in addition to the exhaust gas recirculation is used selectively. In this way, the energy level in the combustion chamber can be varied and adjusted very finely by increasing the temperature or regulating the temperature of the fresh gas temperature. Thus, the combustion process can be accurately controlled in HCCI mode. The temperature level in the combustion chamber can be influenced by the degree of compression and the subsequent expansion, in addition to influencing the temperature level by the exhaust gas recirculation.

The inventive system is especially useful then can be used when the compression device is an exhaust gas turbocharger is. This is a commonly used device for increase the gas density in the intake system, so that in the combustion chamber an increased amount of air can be provided, resulting in a power increase of Internal combustion engine leads. The exhaust gas turbocharger is driven by a compressor rotor in the exhaust stream turbine.

As well the system is useful used when the compression device is a compressor. This also serves to compress the gas pressure in the intake system, wherein the drive energy provided mechanically by the internal combustion engine becomes.

Usefully is provided that the expansion takes place at a throttle valve. In direct injection systems, the throttle valve serves the dosed Respectively of fresh air, whereby by the throttling effect a reduction the pressure takes place. Ultimately, the points in the exhaust gas turbocharger or in the compressor compressed and expanded at the throttle air according to thermodynamic Principles a higher Temperature up than the original one sucked fresh air.

The invention is further developed in a particularly advantageous manner in that a temperature sensor for detecting the temperature T ₂ in the flow direction of the fresh gas is arranged behind the expansion means, so that it can be taken into account in the context of a regulation of the intake gas temperature. The temperature of the fresh air behind the throttle is thus an important input to ultimately set the energy level in the combustion chamber for the HCCI mode advantageous.

The Invention builds on the generic method thereby, a decoupling of the amount of intake gas supplied to the internal combustion engine from the temperature of the intake gas and a targeted adjustment of the energy level in the combustion chamber can be achieved by influencing the coolant flow through the exhaust gas cooler by means of a coolant control valve considering of measured values or model-technically determined values the intake gas temperature is adjusted or regulated. In this way, the advantages and peculiarities of the system according to the invention also implemented as part of a procedure. This also applies to the following specified particularly preferred embodiments of the method according to the invention.

• – Abgastemperatur,
• – zurückgeführte Abgasmasse beziehungsweise -menge,
• – Frischgastemperatur,
• Frischgasmasse beziehungsweise -menge,
• – Ansauggastemperatur,
• – Ansauggasmasse beziehungsweise -menge,
• – Kühlmitteltemperatur beziehungsweise Öltemperatur des durch den Abgaskühler strömenden Kühlmittels beziehungsweise Öls und
• – Kühlmittelmasse beziehungsweise Ölmasse beziehungsweise Kühlmittelmenge beziehungsweise Ölmenge des durch den Abgaskühler strömenden Kühlmittels beziehungsweise Öls.

This is developed in a particularly advantageous manner in that the measured values or the values determined by the model are assigned to at least one of the following variables:

• - exhaust gas temperature,
• - recirculated exhaust gas mass or quantity,
• - fresh gas temperature,
• Fresh gas mass or quantity,
• Intake gas temperature,
• - intake gas mass or quantity,
• - Coolant temperature or oil temperature of the coolant flowing through the exhaust gas cooler or oil and
• - Coolant mass or oil mass or coolant amount relatiefwei the amount of oil flowing through the exhaust gas cooler or oil.

When especially useful it has been proven that the fresh gas temperature, the exhaust gas temperature at Engine outlet, the fresh gas mass or quantity and the Exhaust mass or quantity to be measured.

m ._FG:

Frischgasmassenstrom

m ._AG:

Abgasmassenstrom

T_FG:

Frischgastemperatur

T_AG:

Abgastemperatur

C_p,FG:

Wärmekapazität des Frischgases

C_p,Ac:

Wärmekapazität des Abgases.

The method is usefully developed by calculating the intake gas temperature taking into account the following parameters:

m. _FG :

Fresh gas mass flow

m. _AG :

Exhaust gas mass flow

T _FG :

Fresh gas temperature

T _AG :

exhaust gas temperature

C _{p, FG} :

Heat capacity of the fresh gas

_{Cp, Ac} :

Heat capacity of the exhaust gas.

Q .:

Wärmestrom

KM:

Kühlmittel

AG:

Abgas

WT:

Wärmetauscher

C_p:

Wärmekapazität

k:

Wärmedurchgangskoeffizient des Wärmetauschers

A:

Heizfläche des Wärmetauschers

ΔT_m:

mittlere logarithmische Temperaturdifferenz.

In this context, it is useful that the exhaust gas temperature at the heat exchanger exit be calculated using the following equation system: | ΔQ. KM = | Q. AG | = Q. WT | Q. KM = m. KM C p, KM (T KM, AUS - T KM, ON ) Q.Q AG = m. AG C p, AG (T AG, A - T AG, AUS ) Q. WT = kAΔT m in which

Q .:

heat flow

KM:

coolant

AG:

exhaust

WT:

heat exchangers

C _p :

heat capacity

k:

Heat transfer coefficient of the heat exchanger

A:

Heating surface of the heat exchanger

.DELTA.T _m:

mean logarithmic temperature difference.

In a particularly advantageous embodiment of the method is provided that sucked fresh air, which has a temperature T ₁ before compression, is compressed, that the compressed sucked fresh air is expanded, wherein the compressed and subsequently expanded fresh air has a temperature T ₂ > T ₁ , And that the temperature increase of the fresh air from T ₁ to T ₂ for influencing the temperature level and thus the energy level in the combustion chamber is used in addition to the exhaust gas recirculation targeted.

This is particularly advantageous when the compression takes place through an exhaust gas turbocharger.

Equally is the process then useful when the compression is done by a compressor.

Usefully is further provided that the expansion of a throttle he follows.

The method is developed in a particularly advantageous manner in that the temperature T _{2 is} detected after the expansion, so that it can be considered in the context of a regulation of the intake gas temperature.

Of the Invention is based on the finding that the controlled setting the exhaust gas temperature in addition to the exhaust gas recirculation rate a further independent manipulated variable to influence the temperature level and thus the energy level in the combustion chamber to disposal stands and thus an additional Means for combustion process control. The influence on the Process takes place with regard to the time of ignition of the compressed air / fuel / exhaust gas mixture and the resulting resulting quantities, such as pressure curve and combustion, Peak pressure, combustion center and combustion speed. These in turn are critically responsible for the overall motor Behavior in terms of efficiency, emissions, rough running and Acoustics. The invention is opposed by the fact that in modern engine controls all relevant information and operating variables, such as temperatures and masses or quantities, already present, which Control of the HCCI combustion process necessary by means of exhaust gas temperature control. The invention can also be used effectively to changed environmental or operating conditions Combustion engine encounter, as for example during engine warm-up or in summer / winter operation at widely varying ambient temperatures the case is. In a preferred embodiment it is particular useful, that through the targeted influence or the targeted consideration the fresh gas temperature, the energy level in the combustion chamber of the internal combustion engine varies very finely and can be controlled exactly. Next to the Principle of exhaust gas recirculation and exhaust gas cooling is thus another independent Instrument for influencing the temperature level and thus for Combustion process control available. The invention offers especially the advantage that, starting from cold start conditions, HCCI operation due to low temperature levels not possible is, the fresh gas heated and thus an earlier switch to the low-emission HCCI mode possible is.

The Invention will now be described with reference to the accompanying drawings preferred embodiments exemplified.

It demonstrate:

1 a schematic representation of a system according to the invention;

2 a temperature-entropy diagram for explaining thermodynamic principles of a preferred embodiment of the present invention;

3 a schematic representation of a preferred embodiment of a system according to the invention; and

4 a functional block diagram for explaining the Ansauggastemperaturregelung in the context of a method according to the invention.

1 shows a schematic representation of a system according to the invention. It is an internal combustion engine 10 with an external exhaust gas recirculation device 14 shown. The exhaust gas recirculation device 14 includes an exhaust gas recirculation valve 36 , via which the exhaust gas recirculation rate is adjustable. The exhaust gas recirculation device 14 further comprises a heat exchanger acting as exhaust gas cooler 32 , The exhaust gas heat exchanger 32 will continue via a coolant system 46 flows through a coolant. To cool the coolant is a cooler 48 intended. In the present example, the exhaust gas heat exchanger circuit is designed as a parallel circuit. However, there are also numerous other variants for exhaust gas cooling conceivable, in particular the radiator 48 can be designed as a separate cooler; It is also conceivable to use the radiator of the engine cooling. The cooling can also be done by engine or gear oil.

The coolant system 46 further comprises a coolant control valve, via which the amount of coolant passing through the exhaust gas cooler 32 flows, is adjustable.

The system shown works as follows. From the internal combustion engine 10 Exiting exhaust gas is partially via the exhaust gas recirculation device 14 to the inlet side of the internal combustion engine 10 recycled. In this case, the exhaust gas mass flow m. _AG by means of the exhaust gas recirculation valve 36 to adjust. At the entrance of the exhaust gas cooler 32 the exhaust gas has a temperature T _{AG, ON} , and at the outlet the exhaust gas cooler 32 the exhaust gas has a temperature T _{AG, OFF} , which will generally be lower than the temperature at the inlet. The cooling effect of the exhaust gas cooler 32 can be adjusted by the coolant control valve 50 the coolant mass flow m _{KM is} set. The coolant has at the entrance of the exhaust gas cooler 32 the temperature T _{KM, ON} and at the outlet of the exhaust gas cooler 32 the temperature T _{KM, OFF} , the latter will generally be higher than the temperature at the entrance. Cooling of the coolant then takes place in the cooler 48 , About the influence of the coolant flow through the exhaust gas cooler 32 through the coolant control valve 50 Thus, taking into account measured values or values determined by the model, the intake gas temperature of the combustion engine can be determined 10 inflowing exhaust gas can be adjusted or regulated.

Q .:

Wärmestrom

KM:

Kühlmittel

AG:

Abgas

WT:

Wärmetauscher

C_p:

Wärmekapazität

k:

Wärmedurchgangskoeffizient des Wärmetauschers

A:

Heizfläche des Wärmetauschers

ΔT_m:

mittlere logarithmische Temperaturdifferenz.

The exhaust gas temperature T _{AG, OFF} at the outlet of the exhaust gas cooler 32 can be calculated, for example, using the following equation system: | ΔQ. KM = | Q. AG | = Q. WT | Q. KM = m. KM C p, KM (T KM, AUS - T KM, ON ) Q.Q AG = m. AG C p, AG (T AG, A - T AG, AUS ) Q. WT = kAΔT m in which

Q .:

heat flow

KM:

coolant

AG:

exhaust

WT:

heat exchangers

C _p :

heat capacity

k:

Heat transfer coefficient of the heat exchanger

A:

Heating surface of the heat exchanger

.DELTA.T _m:

mean logarithmic temperature difference.

m ._FG:

Frischgasmassenstrom

m ._AG:

Abgasmassenstrom

T_FG:

Frischgastemperatur

T_AG:

Abgastemperatur

C_p,FG:

Wärmekapazität des Frischgases

C_p,AG:

Wärmekapazität des Abgases.

The temperature of the intake gas can then be calculated using the following parameters:

m. _FG :

Fresh gas mass flow

m. _AG :

Exhaust gas mass flow

T _FG :

Fresh gas temperature

T _AG :

exhaust gas temperature

C _{p, FG} :

Heat capacity of the fresh gas

C _{p, AG} :

Heat capacity of the exhaust gas.

2 shows a temperature-entropy diagram for explaining thermodynamic principles of a preferred embodiment of the present invention. The diagram shows the temperature-entropy curves in a gas for two different pressures p1 and p2. If a gas is compressed to the pressure p2 starting from the pressure p1 and the temperature T1, this process does not take place along an isentropic path (process 1-2s), but with an increase in entropy (process 1-2). Finds an expansion after compaction, that is, a decrease in pressure takes place, so this process will not take place along an isentropic path (process 2-3s), but also with an increase in entropy (process 2-3). The processes illustrated here of an increase in pressure from p1 to p2 and the subsequent expansion to the initial level p1 represent a special case. An expansion to any other pressure level also occurs with an increase in entropy. Finally, after compression of p1 to p2 and expansion of p2 to p1, the gas has a higher temperature level than before compression; the temperature has risen from T1 to T3. The desired temperature change can thus be adjusted in the internal combustion engine on the degree of compression and the subsequent expansion, for example, at the throttle.

3 shows a schematic representation of a preferred embodiment of a system according to the invention. It is an internal combustion engine 10 with exhaust gas recirculation device 14 and exhaust gas turbocharger 16 shown. In the fresh air supply of the internal combustion engine 10 is a throttle 18 arranged. The exhaust system of the internal combustion engine 10 is with an exhaust gas cooler 32 fitted. On the special features of the exhaust gas cooler 32 is in the present presentation according to 3 not received. In the exhaust gas recirculation 14 is an exhaust gas recirculation valve 36 intended. Furthermore, the system comprises measuring devices or sensors at various points 20 . 22 . 24 . 26 . 28 . 30 , whose output signals of a control / processing unit 34 can be supplied. In detail, there are provided: an air mass measuring device 28 , a temperature sensor 20 , in the direction of flow of fresh air behind the throttle 18 is arranged for detecting the fresh air temperature, a temperature sensor 22 for detecting the temperature of the intake gas before flowing into the combustion chamber 12 of the internal combustion engine 10 , an exhaust temperature sensor 24 and a temperature sensor 26 for detecting the temperature at the air / exhaust gas mixing point. These sensors do not necessarily have to be present in order to realize the present invention. For example, the temperature sensor 26 be omitted if the Ansauggastem temperature in accordance with 1 explained calculations is determined. Output signals of these measuring devices and sensors 20 . 22 . 24 . 26 . 28 can the control / processing unit 34 fed, which in turn can drive components of the system, such as the exhaust gas recirculation valve 36 , the exhaust gas cooler 32 , the throttle 18 and the turbocharger 16 , These components can thus be influenced in their function and ultimately to provide the desired energy level in the combustion chamber 12 of the internal combustion engine 10 contribute.

This in 3 The system shown works as follows. Fresh air is sucked in and from the turbocharger 16 , which is driven by the exhaust stream, compacted. This compressed air needs the throttle 18 happen so that it comes to an expansion. Because of related 2 shown thermodynamic principles has the air behind the throttle 18 a higher temperature than the originally sucked fresh air. The air enters the combustion chamber 12 of the internal combustion engine 10 , After combustion, exhaust gas is expelled in an exhaust gas cooler 32 is cooled. The cooled exhaust gas is partly emitted via the exhaust gas line. Partially the cooled exhaust gas 32 via the exhaust gas recirculation 14 and in particular the exhaust gas recirculation valve 36 to the input side of the internal combustion engine 10 recycled. Because of the measuring equipment and sensors 20 . 22 . 24 . 26 . 28 detected signals, the control / processing unit 34 influence the system so that ultimately an energy level suitable for HCCI operation in the combustion chamber 12 of the internal combustion engine 10 is present. A substantial part of the intake gas temperature control will be discussed below 4 described.

4 shows a functional block diagram for explaining the intake gas temperature control in the context of a method according to the invention. The illustrated functional units may be components of in 2 illustrated control / processing unit 34 be. It is a facility 38 intended to calculate the exhaust gas target temperature. This is with a device 40 for calculating the coolant flow through the in 2 illustrated exhaust gas cooler 32 connected. The device 40 for the calculation of the coolant flow is again via a controlled system 42 with a regulator 44 in connection. Furthermore, in 3 Signals are represented, wherein signals having the suffix AV indicate current values, while signals having the suffix SP denote desired values.

The intake gas temperature control according to 4 works as follows. In accordance with the engine operating conditions, a setpoint for the temperature of the intake air in the intake manifold (TIA_IM_SP) is specified. This is determined together with the current fresh-gas temperature (TIA_AV) and the masses of the fresh gas supplied (MAF_KGH_AV) and the recirculated exhaust gas (M_EGR_AV) of the device 38 supplied for calculating the target exhaust gas temperature. This calculates, taking into account the specific heat capacities of the supplied fresh air (c _{p, air} ) and the exhaust gas (c _{p, exhaust gas} ), the exhaust gas temperature at the mixing point (T_EGR_DOWN_SP), which is required to obtain the desired gas temperature in the intake manifold. In the facility 40 for the calculation of the coolant flow is that of the device 38 to calculate the exhaust gas target Temperature determined setpoint (T_EGR_DOWN_SP) compared to the actual exhaust gas temperature at the engine outlet (T_EGR_UP_AV) before the exhaust gas cooler. From the difference, a coolant flow rate (M_COOL) determined by the exhaust gas cooler required to obtain the desired exhaust temperature at the mixing point (T_EGR_DOWN_SP) is determined. This coolant flow is then realized by a corresponding control of an electric coolant pump, as well as other types of flow control are possible. The coolant flow is in accordance with the present regulation via the controlled system 42 converted into a certain gas temperature in the intake manifold (TIA_IM_AV), which will be present after a certain transient phase. This gas temperature in the intake manifold (TIA_IM_AV) is set with the setpoint (TIA_IM_SP) in the controller 44 compared. If the values deviate from one another, the coolant flow through the exhaust gas cooler is corrected by a value (ΔM_COOL) so that the desired intake air temperature is finally set in accordance with the desired value (TIA_IM_SP) via a suitable exhaust gas temperature at the mixing point (T_EGR_DOWN_AV).

To the related 4 explained regulation with the in 3 In the following, it will be specified in detail where the values used for regulation should be measured or adjusted. The air mass measuring device 28 determines the value MAF_KGH_AV. The recirculated exhaust gas fraction M_EGR_AV is in the context of the exhaust gas recirculation by appropriate control of the exhaust gas recirculation valve 36 known. The fresh gas temperature TIA_AV is determined by the temperature sensor 20 behind the throttle 18 measured. Intake gas temperature TIA_IM_AV is determined by the temperature sensor 22 before entering the combustion chamber 12 of the internal combustion engine 10 detected. The temperature sensor 24 at the exit from the combustion chamber 12 of the internal combustion engine 10 detects the exhaust gas temperature T_EGR_UP_AV. In addition, the temperature TIA_EGR_DOWN_AV at the mixing point by the temperature sensor 26 However, this is related to 4 described regulation is not absolutely necessary.

The invention can be summarized as follows: In an HCCI-capable internal combustion engine, with an exhaust gas recirculation device 14 and an exhaust gas cooler 32 is proposed, a system and a method are proposed, based on which an improved adjustment of the temperature level in the combustion chamber can take place. By a coolant control valve 50 is provided, which through the exhaust gas cooler 32 it is possible to influence the intake gas temperature.

The in the above description, in the drawings and in the claims disclosed features of the invention can both individually and also in any combination for the realization of the invention be essential.

Claims (23)

System for influencing the intake gas temperature and thus the energy level in the combustion chamber ( 12 ) of an internal combustion engine ( 10 ), in particular a HCCI-capable internal combustion engine ( 10 ), with - an exhaust gas recirculation device ( 14 ) with an exhaust gas recirculation valve for supplying exhaust gas of an earlier combustion cycle to fresh air or to a mixture having fresh air, in order to provide an air / fuel / exhaust gas mixture with an energy level advantageous for the combustion after injection of fuel, and - at least one exhaust gas cooler ( 32 ) acting heat exchanger for lowering the temperature of the recirculated exhaust gas, characterized in that a decoupling of the internal combustion engine ( 10 ) amount of intake gas from the temperature of the intake gas and a targeted adjustment of the energy level in the combustion chamber ( 12 ) can be achieved by a coolant control valve ( 50 ) is provided, so that by influencing the coolant flow through the exhaust gas cooler ( 32 ), taking into account measured values or values derived from the model, the intake gas temperature can be adjusted or regulated. System according to claim 1, characterized in that the exhaust gas cooler ( 32 ) in a separate heat exchanger circuit ( 46 ) is arranged. System according to claim 1 or 2, characterized that the exhaust gas cooler in an engine coolant circuit is arranged. System according to one of the preceding claims, characterized characterized in that the exhaust gas cooler is designed as engine or transmission oil heat exchanger. System according to one of the preceding claims, characterized in that the measured values or the model-technically determined values are assigned to at least one of the following variables: exhaust gas temperature, recirculated exhaust gas mass or quantity, fresh gas temperature, fresh gas mass or quantity, intake gas temperature, Intake gas mass or quantity, coolant temperature or oil temperature of the coolant or oil flowing through the exhaust gas cooler, and coolant mass or oil mass or coolant quantity or oil quantity of the coolant or oil flowing through the exhaust gas cooler. System according to one of the preceding claims, characterized in that a temperature sensor ( 20 ) for detecting the fresh gas temperature, a temperature sensor ( 24 ) for detecting the exhaust gas temperature at the engine outlet, an air mass or quantity measuring device ( 28 ) for detecting the fresh gas mass or quantity and an exhaust gas mass or quantity measuring device ( 28 ) are provided for detecting the exhaust mass or quantity. System according to one of the preceding claims, characterized in that the intake gas temperature is calculated taking into account the following parameters: m. _FG : Fresh gas mass flow m. _AG : Exhaust mass flow T _FG : Fresh gas temperature T _AG : Exhaust temperature C _{p, FG} : Heat capacity of the fresh gas C _{p, AG} : Heat capacity of the exhaust gas. System according to one of the preceding claims, characterized in that the exhaust gas temperature is calculated at the heat exchanger output using the following equation system | ΔQ. KM = | Q. AG | = Q. WT | Q. KM = m. KM C p, KM (T KM, AUS - T KM, ON ) Q. Q AG = m. AG C p, AG (T AG, A - T AG, AUS ) Q. WT = kAΔT m where Q.: Heat flow KM: Coolant AG: Exhaust WT: Heat exchanger C _p : Heat capacity k: Heat transfer coefficient of the heat exchanger A: Heating surface of the heat exchanger ΔT _m : Mean logarithmic temperature difference. System according to one of the preceding claims, characterized in that - a compacting device ( 16 ) is provided for compressing sucked fresh air, which has a temperature T1 before compression, - that expansion means ( 18 ) are provided, which cause an expansion of the compressed sucked fresh air, - wherein the compressed and subsequently expanded fresh air has a temperature T ₂ > T1, and - that the temperature increase of the fresh air from T ₁ to T ₂ to influence the temperature level and thus the energy level in the combustion chamber ( 12 ) is used selectively in addition to the exhaust gas recirculation. System according to one of the preceding claims, characterized in that the compression device is an exhaust gas turbocharger ( 16 ). System according to one of claims 1 to 9, characterized that the compression device is a compressor. System according to one of the preceding claims, characterized in that the expansion of a throttle valve ( 18 ) he follows. System according to one of the preceding claims, characterized in that a temperature sensor ( 20 ) is arranged for detecting the temperature T ₂ in the flow direction of the fresh gas behind the expansion means, so that it can be considered in the context of a regulation of the intake gas temperature. Method for influencing the intake gas temperature and thus the energy level in the combustion chamber ( 12 ) of an internal combustion engine ( 10 ), in particular a HCCI-capable internal combustion engine ( 10 in which exhaust gas of an earlier combustion cycle is supplied with fresh air or a mixture containing fresh air, in order to provide an air / fuel / exhaust mixture with an energy level advantageous for combustion after injection of fuel, and exhaust gas in an exhaust gas cooler (FIG. 32 ) acting heat exchanger for lowering the temperature of the recirculated exhaust gas is cooled, characterized in that a decoupling of the internal combustion engine ( 10 ) amount of intake gas from the temperature of the intake gas and a targeted adjustment of the energy level in the combustion chamber ( 12 ) can be achieved by influencing the coolant flow through the exhaust gas cooler ( 32 ) by means of a coolant control valve ( 50 ), taking into account measured values or values determined by the model, the intake gas temperature is set or regulated. Method according to claim 14, characterized, that the measured values or the values determined by the model are assigned to at least one of the following sizes: - exhaust gas temperature, - recirculated exhaust gas mass or quantity, - fresh gas temperature, - fresh gas mass or quantity, Intake gas temperature, - Intake gas mass or quantity, - Coolant temperature or oil temperature that through the exhaust gas cooler flowing refrigerant or oil and - Coolant mass or oil mass or coolant quantity or amount of oil that through the exhaust gas cooler flowing coolant or oil. A method according to claim 14 or 15, characterized in that the fresh gas temperature, the exhaust gas temperature at the engine outlet, the fresh gas mass or quantity and the exhaust mass or quantity be measured. Method according to one of claims 14 to 16, characterized in that the intake gas temperature is calculated taking into account the following parameters: m. _FG : Fresh gas mass flow m. _AC : exhaust gas mass flow T _FG : fresh gas temperature T _AG : exhaust gas temperature C _{p, FG} : heat capacity of the fresh gas c _p , _AG : heat capacity of the exhaust gas. Method according to one of claims 14 to 17, characterized in that the exhaust gas temperature is calculated at the heat exchanger output using the following equation system: | ΔQ. KM = | Q. AG | = Q. WT | Q. KM = m. KM C p, KM (T KM, AUS - T KM, ON ) Q.Q AG = m. AG C p, AG (T AG, A - T AG, AUS ) Q. WT = kAΔT m where Q.: Heat flow KM: Coolant AG: Exhaust WT: Heat exchanger C _p : Heat capacity k: Heat transfer coefficient of the heat exchanger A: Heating surface of the heat exchanger ΔT _m : Mean logarithmic temperature difference. Method according to one of claims 14 to 18, characterized in that - sucked fresh air, which has a temperature T1 before compression, is compressed, - that the compressed sucked fresh air is expanded, - wherein the compressed and subsequently expanded fresh air has a temperature T ₂ > T1, and - that the temperature increase of the fresh air from T ₁ to T ₂ for influencing the temperature level and thus the energy level in the combustion chamber ( 12 ) is used selectively in addition to the exhaust gas recirculation. Method according to one of claims 14 to 19, characterized in that the compression by an exhaust gas turbocharger ( 16 ) he follows. Method according to one of claims 14 to 19, characterized in that the compression is done by a compressor. Method according to one of claims 14 to 21, characterized in that the expansion of a throttle valve ( 18 ) he follows. Method according to one of claims 14 to 22, characterized in that the temperature T _{2 is} detected after the expansion, so that it can be considered in the context of a regulation of the intake gas temperature.