DE10319333A1 - System for influencing suction gas temperature and thus power level in combustion chamber of an internal combustion engine, comprises coolant control valve to influence coolant flow through exhaust gas cooler - Google Patents

Abstract

The system comprises a coolant control valve (50) so that the suction gas temperature can be adjusted and/or regulated by influencing the coolant flow through the exhaust gas cooler (32) with consideration of measured values and/or model-technically determined values. The exhaust gas cooler is arranged in a separate heat exchanger circuit (46). An independent claim is also included for the method of influencing the suction gas temperature and thus the power level in combustion chamber of a combustion engine.

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 to feed of exhaust from a previous one Combustion cycle to fresh air or to fresh air comprising mixture to form an air / fuel / exhaust gas mixture after fuel injection with one for to provide the combustion with advantageous energy levels, and at least one as an exhaust gas cooler acting heat exchanger to lower 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 Internal combustion engine, in particular an HCCI-capable internal combustion engine, in the exhaust gas from an earlier combustion cycle Fresh air or a mixture containing fresh air is fed to form an air / fuel / exhaust gas mixture after fuel injection with one for to provide the combustion with advantageous energy levels, 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 There are different relationships with gasoline direct injection systems Operating conditions known. Common to these is that direct injection of fuel under high pressure takes place directly in a combustion chamber. The mixture is then formed within the combustion chamber. Traditionally differentiates the operating modes homogeneous operation and shift or mode of operation Lean operation. In homogeneous operation, one is homogeneous over the entire Combustion chamber distributed mixture.

At the Shift or lean operation is 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 fresh air drawn in, one Inert gas from the exhaust gas recirculation or a very lean air-fuel mixture, so that overall results in an air ratio of λ> 1.

Next this conventional Operating modes are increasingly another operating mode as promising assessed, the operation of the auto-igniting Diesel engine resembles. This is called HCCI mode (Homogeneous Charge Compression Ignition) known and represents a self-igniting combustion process represents at which the ignition point and thus the course of combustion over the reactive amount of energy is controlled in the cylinder. To provide a sufficient level of energy is usually used exhaust gas recirculation via external Actuators 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, 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 gas may not be affected possible, the exhaust gas recirculation rate both in terms of the temperature in the combustion chamber as well as in terms of to the stated mixing ratio to choose optimally. So you can Compromises in setting the exhaust gas recirculation rate may be required for a reliable Ensure the operation of the internal combustion engine.

in the Relation to conventional ignited Internal combustion engines have already been proposed to cool exhaust gas recirculation use this cooling of the exhaust gas, in particular on a reduction in nitrogen oxide emissions aimed.

For this is, for example, on MTZ Motortechnische Zeitschrift 60 (1999) 7/8, page 470 ff. Referred to: "Compliance future Emission regulations through refrigerated Exhaust gas recirculation "by Karl-Heinrich Lösing and Rainer Lutz.

The Invention is based on the object, the disadvantages of the prior art of technology, and in particular a system and method to disposal to ask by setting the temperature in the combustion chamber of the internal combustion engine at least partially from the setting of the optimal mixing ratio can be decoupled from air, fuel and exhaust gas.

This The object is achieved with the features of the independent claims.

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

The invention builds on the generic system in that a coolant control valve is provided, so that the intake gas temperature is set or regulated by influencing the coolant flow through the exhaust gas cooler, taking into account measured values or values determined using model technology can be. The recirculated exhaust gas quantity is therefore no longer necessarily linked to the temperature increase in the combustion chamber that is achieved with exhaust gas recirculation. Rather, the adjustable exhaust gas cooling allows the energy content in the combustion chamber to be set within certain limits independently of the exhaust gas recirculation rate. This means that both the mixing ratio and the energy level in the combustion chamber can be optimally adjusted.

The system according to the invention is further developed in an advantageous manner in that the exhaust gas cooler in arranged in a separate heat exchanger circuit is. The exhaust gas cooler can thus be self-sufficient without being influenced by other components of the motor vehicle work. There is also no influence on other components 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 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 an efficient system is implemented overall becomes.

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

• – 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 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 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.

If hereinafter the term "quantity" is used, can also mean a "mass" and vice versa. The current exhaust gas temperature and the returned amount of exhaust gas are known as engine operating variables in modern engine controls. she can either calculated using model technology or using appropriate sensors can 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. Is also the amount of coolant or the amount of oil known by the exhaust gas heat exchanger flows, can with knowledge of the heat exchanger characteristics the exhaust gas temperature at the heat exchanger outlet and thus the mixing temperature of the intake air can be determined.

As particularly useful it has been found that a temperature sensor for detecting the Fresh gas temperature, a temperature sensor for recording the exhaust gas temperature at the engine outlet, an air mass or volume measuring device for Detection of the fresh gas mass or quantity and an exhaust gas mass or quantity measuring device for detecting the exhaust gas mass or amount are provided. Leave out of these sizes become aware of certain models or certain characteristics the essential parameters for reliable control determine the intake gas temperature.

berechnet wird, wobei
m ·_FG: Frischgasmassenstrom
m ·_AG: Abgasmassenstrom
T_FG: Frischgastemperatur
T_AG: Abgastemperatur
T_ASG: Ansauggastemperatur
C_p,FG: Wärmekapazität des Frischgases
C_p,AG: Wärmekapazität des Abgases.So the system is useful in that the intake gas temperature according to the equation

is calculated, where
m · _FG : fresh gas mass flow
m · _AG : exhaust gas mass flow
T _FG : fresh gas temperature
T _AG : exhaust gas temperature
T _ASG : intake gas temperature
C _{p, FG} : heat capacity of the fresh gas
C _{p, AG} : heat capacity of the exhaust gas.

The Intake gas temperature can thus be measured with knowledge of known ones or also variables already calculated using model technology become.

In this context, it is useful that the exhaust gas temperature at the heat exchanger outlet is calculated using the following system of equations: | ΔQ · KM | = | ΔQ · AG | = Q WT ΔQ KM = m KM c p, KM (T KM, AUS - T KM, ON ) ΔQ 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 gas
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.

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

The system according to the invention is further developed in a particularly useful manner in that a compression device for compressing fresh air drawn in is provided, which has a temperature T ₁ before the compression, and expansion means are provided which bring about an expansion of the compressed fresh air drawn in, the compressed air being compressed and subsequently expanded fresh air has a temperature T ₂ > T ₁ , and that the increase in temperature of the fresh air from T ₁ to T _{2 is used} to influence the temperature level and thus the energy level in the combustion chamber in addition to the exhaust gas recirculation. 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. The combustion process in HCCI mode can thus be precisely controlled. The temperature level in the combustion chamber can be influenced via the degree of compression and the subsequent expansion, in addition to influencing the temperature level through the exhaust gas recirculation.

The system according to the invention is especially useful then can be used if the compression device is an exhaust gas turbocharger is. It is a frequently used device for increase the gas density in the intake system, so that an increased amount of air in the combustion chamber can be provided, which leads to an increase in performance of the Internal combustion engine leads. The exhaust gas turbocharger is driven by a compressor rotor turbine lying in the exhaust gas stream.

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

Usefully it is envisaged that the expansion will take place on a throttle valve. With direct injection systems, the throttle valve is used for metering Respectively of fresh air, with a reduction due to the throttling effect of pressure. Ultimately, it points in the turbocharger or Air compressed in the compressor and expanded at the throttle valve according to thermodynamic Basic rules a higher Temperature up than that originally fresh air drawn in.

The invention is developed in a particularly advantageous manner in that a temperature sensor for detecting the temperature T ₂ is arranged behind the expansion means in the flow direction of the fresh gas, so that this can be taken into account in the context of regulating the intake gas temperature. The temperature of the fresh air behind the throttle valve is therefore an important input variable in order ultimately to advantageously determine the energy level in the combustion chamber for the HCCI operating mode.

The Invention builds on the generic method in that that by influencing the coolant flow through the exhaust gas cooler by means of a coolant control valve considering of measured values or values determined using model technology the intake gas temperature is set or regulated. In this way, the advantages and special features of the system according to the invention also implemented as part of a process. 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 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.

It has proven to be particularly useful that the fresh gas temperature, the exhaust gas temperature at the engine outlet, or the fresh gas mass wise quantity and the exhaust gas mass or quantity are measured.

berechnet wird, wobei
m ·_FG: Frischgasmassenstrom
m ·_AG: Abgasmassenstrom
T_FG: Frischgastemperatur
T_AG: Abgastemperatur
T_ASG: Ansauggastemperatur
c_p,FG: Wärmekapazität des Frischgases
c_p,AG: Wärmekapazität des Abgases.The method is further developed in a useful manner in that the intake gas temperature according to the equation

is calculated, where
m · _FG : fresh gas mass flow
m · _AG : exhaust gas mass flow
T _FG : fresh gas temperature
T _AG : exhaust gas temperature
T _ASG : intake gas temperature
c _{p, FG} : heat capacity of the fresh gas
c _{p, AG} : heat capacity of the exhaust gas.

In this context it is useful that the exhaust gas temperature at the heat exchanger outlet is calculated using the following system of equations: | ΔQ · KM | = | ΔQ · AG | = Q WT ΔQ KM = m KM c p, KM (T KM, AUS - T KM, ON ) ΔQ 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 gas
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.

In a particularly advantageous embodiment of the method it is provided that fresh air drawn in, which has a temperature T ₁ before compression, is compressed, that the compressed fresh air drawn in is expanded, the compressed and subsequently expanded fresh air having a temperature T ₂ > T ₁ , and that the increase in temperature of the fresh air from T ₁ to T _{2 is used} to influence the temperature level and thus the energy level in the combustion chamber in addition to the exhaust gas recirculation.

This is particularly advantageous when the compression done by an exhaust gas turbocharger.

Is alike the procedure then useful if compression is done by a compressor.

Usefully it is also contemplated that the expansion on a throttle valve he follows.

The method is developed in a particularly advantageous manner in that the temperature T ₂ is detected after the expansion, so that this can be taken into account in the context of regulating the intake gas temperature.

The Invention is based on the finding that controlled adjustment the exhaust gas temperature in addition to the exhaust gas recirculation rate to influence another independent manipulated variable 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 ignition point of the compressed air / fuel / exhaust gas mixture and the resulting sequential variables, such as pressure curve and combustion, Peak pressure, focus of combustion and combustion speed. These in turn are crucially responsible for the overall motor Behavior with regard to efficiency, emissions, rough running and Acoustics. The invention accommodates the fact that in modern engine controls all relevant information and operating parameters, for example temperatures and substance masses or amounts, are already available for Control of the HCCI combustion process by means of exhaust gas temperature control. The invention can also be used effectively to change environmental or operating conditions encountered by internal combustion engines, such as during engine warm-up or in summer / winter operation with very different ambient temperatures the case is. In a preferred embodiment, it is special useful, that through the targeted influencing or the targeted consideration the fresh gas temperature is the energy level in the combustion chamber of the internal combustion engine can be varied very precisely and precisely controlled. 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 in particular the advantage that, starting from cold start conditions, among which an HCCI operation due to the too low temperature level not possible is that the fresh gas is 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 with reference to preferred examples of management explained.

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 intake gas temperature control 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 can be set. The exhaust gas recirculation device 14 further comprises a heat exchanger acting as an exhaust gas cooler 32 , The exhaust gas heat exchanger 32 will continue to have a coolant system 46 flows through a coolant. A cooler is used to cool the coolant 48 intended. In the present example, the exhaust gas heat exchanger circuit is designed as a parallel circuit. However, numerous other variants for exhaust gas cooling are also conceivable, in particular the cooler 48 can be designed as a separate cooler; it is also conceivable to share the radiator of the engine cooling. Cooling can also be done with engine or gear oil.

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

The system shown works as follows. From the internal combustion engine 10 escaping exhaust gas is partially via the exhaust gas recirculation device 14 to the intake side of the internal combustion engine 10 recycled. The exhaust gas mass flow m · _AG can be controlled using the exhaust gas recirculation valve 36 to adjust. At the entrance to 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, AUS} which will generally be lower than the temperature at the inlet. The cooling effect of the exhaust gas cooler 32 can be adjusted by using 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, AUS} , the latter generally being higher than the temperature at the entrance. The coolant is then cooled in the cooler 48 , About the influence of the coolant flow through the exhaust gas cooler 32 through the coolant control valve 50 can therefore take into account the intake gas temperature of the in the internal combustion engine taking into account measured values or model-determined values 10 inflowing exhaust gas can be adjusted or regulated.

The exhaust gas temperature T _{AG, AUS} at the outlet of the exhaust gas cooler 32 can be calculated using the following system of equations, for example: | ΔQ · KM | = | ΔQ · AG | = Q WT ΔQ KM = m KM c p, KM (T KM, AUS - T KM, ON ) ΔQ 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 gas
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.

berechnet wird, wobei
m ·_FG: Frischgasmassenstrom
m ·_AG: Abgasmassenstrom
T_FG: Frischgastemperatur
T_AG: Abgastemperatur
T_ASG: Ansauggastemperatur
c_p,FG: Wärmekapazität des Frischgases
c_p,AG: Wärmekapazität des Abgases.The temperature of the intake gas, hereinafter referred to as T _ASG , can then be determined using the following equation:

is calculated, where
m · _FG : fresh gas mass flow
m · _AG : exhaust gas mass flow
T _FG : fresh gas temperature
T _AG : exhaust gas temperature
T _ASG : intake 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 pressure p2 starting from pressure p1 and temperature T1, this process does not run along an isentropic (process 1-2s), but with an increase in entropy (process 1-2). If there is an expansion after the compression, i.e. a decrease in pressure, this process will also not take place along an isentropic path (process 2-3s), but also with an increase in entropy (process 2-3). The processes shown here of increasing the pressure from p1 to p2 and subsequently expanding to the initial level p1 represent a special case. Expansion to any other pressure level also takes place with an increase in entropy. Ultimately, the gas after compression from p1 to p2 and expansion from p2 to p1 has a higher temperature level than before compression; the temperature rose from T1 to T3. The desired temperature change in the internal combustion engine can thus be set via the degree of compression and the subsequent expansion, for example on the throttle valve.

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 valve 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 accordance with the present presentation 3 not received. In the exhaust gas recirculation 14 is an exhaust gas recirculation valve 36 intended. The system also includes measuring devices or sensors at various points 20 . 22 . 24 . 26 . 28 . 30 , the output signals of a control / regulating / computing unit 34 can be supplied. The following are provided in detail: an air mass measuring device 28 , a temperature sensor 20 , which is in the direction of fresh air flow behind the throttle valve 18 A temperature sensor is arranged to detect the fresh air temperature 22 for recording the temperature of the intake gas before it flows into the combustion chamber 12 of the internal combustion engine 10 , an exhaust gas temperature sensor 24 as well as a temperature sensor 26 for recording the temperature at the air / exhaust gas mixing point. These sensors do not necessarily have to be present in order to implement the present invention. For example, the temperature sensor 26 be omitted if the intake gas temperature according to the related 1 explained calculations is determined. Output signals from these measuring devices and sensors 20 . 22 . 24 . 26 . 28 can the control / regulating / computing unit 34 are supplied, which in turn can control components of the system, such as the exhaust gas recirculation valve 36 , the exhaust gas cooler 32 who have favourited Throttle 18 and the exhaust gas 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 system shown works as follows. Fresh air is drawn in and from the exhaust gas turbocharger 16 , which is driven by the exhaust gas stream, compresses. This compressed air must go to the throttle valve 18 happen so that there is an expansion. Due to the context of 2 The thermodynamic principles shown have the air behind the throttle valve 18 a higher temperature than the fresh air originally drawn in. The air gets into the combustion chamber 12 of the internal combustion engine 10 , After the combustion, exhaust gas is emitted in an exhaust gas cooler 32 is cooled. The cooled exhaust gas is partially emitted via the exhaust line. Sometimes the cooled exhaust gas 32 via exhaust gas recirculation 14 and especially 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 The control / regulating / computing unit can detect signals 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 significant part of the suction gas temperature control is described below in connection with 4 described.

4 shows a functional block diagram to explain the intake gas temperature control in the context of a method according to the invention. The functional units shown can be components of the in 2 shown control / regulating / computing unit 34 his. It is an establishment 38 provided for calculating the target exhaust gas temperature. This is with one facility 40 to calculate the coolant flow through the in 2 Exhaust gas cooler shown 32 connected. The facility 40 the calculation of the coolant flow is again via a controlled system 42 with a regulator 44 in connection. Furthermore, in 3 Signals are shown, signals which have the ending AV indicate current values, while signals which have the ending SP identify desired values.

The intake gas temperature control according to 4 works as follows. A setpoint for the temperature of the intake air in the intake manifold (TIA_IM_SP) is specified in accordance with the engine operating conditions. This is together with the current fresh gas temperature (TIA_AV) and the masses of the supplied fresh gas (MAF_KGH_AV) and the returned exhaust gas (M_EGR_AV) of the facility 38 to calculate the target exhaust gas temperature. Taking into account the specific heat capacities of the fresh air (c _{p, air} ) and the exhaust gas (c _{p, exhaust gas} ), this calculates the exhaust gas temperature at the mixing point (T_EGR_DOWN_SP), which is required to achieve the desired gas temperature tur in the intake manifold. In the facility 40 the device calculates the coolant flow 38 Setpoint (T_EGR_DOWN_SP) determined for calculating the exhaust gas target temperature is compared with the actual exhaust gas temperature at the engine outlet (T_EGR_UP_AV) upstream of the exhaust gas cooler. From the difference, a coolant flow (M_COOL) through the exhaust gas cooler is determined, which is required to obtain the desired exhaust gas temperature at the mixing point (T_EGR_DOWN_SP). This coolant flow is then realized by a corresponding control of an electrical coolant pump, whereby other types of flow control are equally possible. The coolant flow is controlled according to the present regulation over the controlled system 42 converted into a certain gas temperature in the intake manifold (TIA_IM_AV), which will be present after a certain settling phase. This gas temperature in the intake manifold (TIA_IM_AV) is compared with the setpoint (TIA_IM_SP) in the controller 44 compared. If the values differ from each other, the coolant flow through the exhaust gas cooler is corrected by one value (ΔM_COOL), so that the desired intake air temperature is ultimately set according to the setpoint (TIA_IM_SP) using a suitable exhaust gas temperature at the mixing point (T_EGR_DOWN_AV).

To those related to 4 explained regulation with the in 3 To be able to better relate the system shown, it is specified below where the values used for the control should be measured or set. The air mass measuring device 28 determines the value MAF_KGH_AV. The recirculated exhaust gas portion M_EGR_AV is within the scope of the exhaust gas recirculation by appropriately controlling 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. The 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 through the temperature sensor 26 are recorded, but this for those related to 4 described regulation is not absolutely necessary.

The invention can be summarized as follows: In an HCCI-compatible internal combustion engine, which has an exhaust gas recirculation device 14 and an exhaust gas cooler 32 is equipped, a system and a method are proposed, on the basis of which an improved setting of the temperature level in the combustion chamber can take place. By using a coolant control valve 50 is provided by the exhaust gas cooler 32 flowing coolant liquid amount, it is possible to influence the intake gas temperature.

The in the above description, in the drawings and in the claims Features of the invention disclosed can be both individually and in any combination for the realization of the invention may 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 ), especially an HCCI-compatible internal combustion engine ( 10 ), with - an exhaust gas recirculation device ( 14 ) with an exhaust gas recirculation valve for supplying exhaust gas from an earlier combustion cycle to fresh air or to a mixture comprising fresh air, in order to provide an air / fuel / exhaust gas mixture having an energy level which is advantageous for combustion after fuel injection, and - at least one as an exhaust gas cooler ( 32 ) acting heat exchanger for lowering the temperature of the recirculated exhaust gas, characterized in that a coolant control valve ( 50 ) is provided so that by influencing the coolant flow through the exhaust gas cooler ( 32 ) the intake gas temperature can be set or regulated taking into account measured values or model-determined values. 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 in that that the exhaust gas cooler in an engine coolant circuit is arranged. System according to one of the preceding claims, characterized characterized that the exhaust gas cooler is designed as an engine or transmission oil heat exchanger. System according to one of the preceding claims, characterized 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 tempera structure 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 ) to record the fresh gas temperature, a temperature sensor ( 24 ) to measure 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 gas mass or quantity. System according to one of the preceding claims, characterized in that the intake gas temperature according to the equation

is calculated, where m · _FG : fresh gas mass flow m · _AG : exhaust gas mass flow T _FG : fresh gas temperature T _AG : exhaust gas temperature T _ASG : intake gas 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 at the heat exchanger outlet is calculated using the following system of equations: | ΔQ · KM | = | ΔQ · AG | = Q WT ΔQ KM = m KM c p, KM (T KM, AUS - T KM, ON ) ΔQ AG = m AG c p, AG (T AG, A - T AG, AUS ) Q WT = kAΔT m where Q ·: heat flow KM: coolant AG: exhaust gas 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 compression device ( 16 ) is provided for compressing fresh air drawn in, which has a temperature T ₁ before compression, - that expansion means ( 18 ) are provided, which cause an expansion of the compressed fresh air sucked in, - the compressed and subsequently expanded fresh air having a temperature T ₂ > T ₁ , and - that the temperature increase in the fresh air from T ₁ to T ₂ to influence the temperature level and thus the Energy levels in the combustion chamber ( 12 ) is used in addition to exhaust gas recirculation. System according to one of the preceding claims, characterized in that the compression device is an exhaust gas turbocharger ( 16 ) is. System according to one of claims 1 to 9, characterized in that that the compression device is a compressor. System according to one of the preceding claims, characterized in that the expansion on a throttle valve ( 18 ) he follows. System according to one of the preceding claims, characterized in that a temperature sensor ( 20 ) for detecting the temperature T ₂ in the flow direction of the fresh gas is arranged behind the expansion means, so that this can be taken into account in the context of regulating the intake gas temperature. Process for influencing the intake gas temperature and thus the energy level in the combustion chamber ( 12 ) of an internal combustion engine ( 10 ), especially an HCCI-compatible internal combustion engine ( 10 ), in which - exhaust gas from an earlier combustion cycle fresh air or a mixture comprising fresh air is supplied in order to provide an air / fuel / exhaust gas mixture with an energy level which is advantageous for combustion after fuel injection, and - exhaust gas in an exhaust gas cooler ( 32 ) acting heat exchanger for lowering the temperature of the recirculated exhaust gas is cooled, characterized in that by influencing the coolant flow through the exhaust gas cooler ( 32 ) by means of a coolant control valve ( 50 ) the intake gas temperature is set or controlled taking into account measured values or model-determined values. Method according to claim 14, characterized in that the measured values or the values determined by the model are at least one The following variables are assigned: - 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. A method according to claim 14 or 15, characterized in that that the fresh gas temperature, the exhaust gas temperature at the engine outlet, the fresh gas mass or quantity and the exhaust gas mass or -quantity can be measured. Method according to one of claims 14 to 16, characterized in that the intake gas temperature according to the equation

is calculated, where m · _FG : fresh gas mass flow m · _AG : exhaust gas mass flow T _FG : fresh gas temperature T _AG : exhaust gas temperature T _ASG : intake 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 at the heat exchanger outlet is calculated using the following system of equations: | ΔQ · KM | = | ΔQ · AG | = Q WT ΔQ KM = m KM c p, KM (T KM, AUS - T KM, ON ) ΔQ AG = m AG c p, AG (T AG, A - T AG, AUS ) Q WT = kAΔT m where Q ·: heat flow KM: coolant AG: exhaust gas 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 - fresh air sucked in, which has a temperature T ₁ before compression, is compressed, - the compressed fresh air drawn in is expanded, - 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 to influence the temperature level and thus the energy level in the combustion chamber ( 12 ) is used in addition to 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 compression is carried out by a compressor. Method according to one of claims 14 to 21, characterized in that the expansion on 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 this can be taken into account as part of a regulation of the intake gas temperature.