INTERNAL COMBUSTION ENGINE AND METHOD FOR OPERATING AN INTERNAL COMBUSTION ENGINE

Abstract

An internal combustion engine with an open-loop or closed-loop control device (2), wherein at least one combustion chamber (3) of the internal combustion engine (1) is designed to burn a fuel-air mixture using at least one combustion parameters that can be influenced by the open-loop or closed-loop control device (2), wherein the open-loop or closed-loop control device (2) has an emission control loop that is configured to actuate the at least one actuator that influences the at least one combustion parameter as a substitute parameter for NOx emissions by means of a functional relationship in such way that at last one combustion parameter can be set for each target or actual power rating of the internal combustion engine (1), wherein the functional relationship takes account of an influence of a change of the exhaust backpressure (p.sub.3′) affecting at least one combustion chamber (3).

Claims

1. An internal combustion engine with an open-loop or closed-loop control device, wherein at least one combustion chamber of the internal combustion engine is designed to burn a fuel-air mixture using at least one combustion parameter that can be influenced by the open-loop or closed-loop control device, wherein the open-loop or closed-loop control device has an emission control loop that is configured to actuate the at least one actuator that influences the at least one combustion parameter as a substitute parameter for NOx emissions by a functional relationship in such way that the at last one combustion parameter can be set for each target or actual power rating of the internal combustion engine, wherein the functional relationship defines a charge pressure (p.sub.2′) based on a desired value for a power (P.sub.mech), the NO.sub.x emissions and a given level of an exhaust backpressure (p.sub.3′) and is saved in the open-loop or closed-loop control device, wherein the functional relationship takes account of an influence of a change of the exhaust backpressure (p.sub.3′) affecting at least one combustion chamber.

2. The internal combustion engine according to claim 1, wherein, when the exhaust backpressure (p.sub.3′) increases, due account is taken of the functional relationship in such way that the emission control loop sets a leaner fuel-air mixture compared to the previous operating point by changing the at least one combustion parameter.

3. The internal combustion engine according to claim 1, wherein, when the exhaust backpressure (p.sub.3′) increases, due account is taken of the functional relationship in such way that the emission control loop adjusts the ignition to a later time compared to the prior operating point by changing the at least one combustion parameter.

4. The internal combustion engine according to claim 1, wherein, when the exhaust backpressure (p.sub.3′) increases, due account is taken of the functional relationship in such way that the emission control loop sets a lower fill level relative to the previous operating point in at least one combustion chamber by changing the at least one combustion parameter.

5. The internal combustion engine according to claim 1, wherein the at least one combustion parameter that can be influenced by the open-loop or closed-loop control device comprises a combustion air ratio (λ).

6. The internal combustion engine according to claim 5, wherein the open-loop or closed-loop control device affects the combustion air ratio (λ) by at least one of: setting the charge pressure (p2′); setting an injection volume for fuel in at last one combustion chamber; and/or setting a mix ratio for the fuel-air mixture.

7. The internal combustion engine according to claim 1, wherein the at least one combustion parameter that can be influenced by the open-loop or closed-loop control device comprises the charge pressure (p.sub.2′).

8. The internal combustion engine according to the claim 7, wherein, when influencing the charge pressure (p2′), the open-loop or closed-loop control device open loop or closed loop controls a corresponding combustion air ratio (λ) by at least one of: setting an injection volume for fuel in at last one combustion chamber; and/or setting a mix ratio for the fuel-air mixture.

9. The internal combustion engine according to claim 1, wherein the at least one combustion parameter that can be influenced by the open-loop or closed-loop control device includes a time of ignition.

10. The internal combustion engine according to claim 1, wherein the open-loop or closed-loop control device is configured to actuate the at least one actuator that influences the at least one combustion parameter to bring about a change in a fill level in the at least one combustion chamber by adjusting at least one variable valve drive.

11. The internal combustion engine according to claim 1, wherein the at least one actuator that can influence the at least one combustion parameter comprises a throttle valve.

12. The internal combustion engine according to claim 1, characterised in that die wherein the open-loop or closed-loop control device is designed to actuate the at least one actuator that can influence the at least one combustion parameter in order to bring about an adjustment of an amount of fuel directed to at least one combustion chamber and/or of an injection time for the fuel directed to the at least one combustion chamber by actuating at least one port injection valve.

13. The internal combustion engine according to claim 1, wherein the open-loop or closed-loop control device is designed to actuate the at least one actuator that influences the at least one combustion parameter in order to perform a setting of the charge pressure (p.sub.2′) by adjusting a bypass valve for a compressor and/or a variable compressor geometry of the compressor.

14. The internal combustion engine according to claim 1, wherein the open-loop or closed-loop control device for determining a change of the exhaust backpressure (p.sub.3′) acting on the at least one combustion chamber takes account of an adjustment of at least one actuator that affects the exhaust backpressure (p.sub.3′) acting on the at least one combustion chamber.

15. The internal combustion engine according to claim 14, wherein the at least one actuator that influences the exhaust backpressure (p.sub.3′) acting on the at least one combustion chamber includes a bypass valve for an exhaust turbine of a turbocharger.

16. The internal combustion engine according to claim 14, wherein the at least one actuator that influences the exhaust backpressure (p.sub.3′) to the at least one combustion chamber includes a variable turbine geometry for an exhaust turbine of a turbocharger.

17. The internal combustion engine according to claim 14, wherein the at least one actuator that influences the exhaust backpressure (p.sub.3′) acting on the at least one combustion chamber includes a bypass valve for a catalytic converter arranged upstream of an exhaust turbine of a turbocharger.

18. The internal combustion engine according to claim 1, wherein the open-loop or closed-loop control device for determining any change of the exhaust backpressure (p.sub.3′) acting on the at least one combustion chamber, takes account of a change of a measuring signal recorded by at least one sensor in an exhaust line of the internal combustion engine.

19. A process for regulating or controlling an internal combustion engine, wherein in at least one combustion chamber of the internal combustion engine a fuel-air mixture with at least one combustion parameter that can be influenced is combusted, and wherein the at least one combustion parameter is open loop or closed loop controlled through at least one actuator that influences the at least one combustion parameter as a substitute parameter for NOx emissions as part of an emission control loop by a functional relationship in such way that at least one combustion parameter is set for each target or actual power rating of the internal combustion engine, wherein the functional relationship defines a charge pressure (p.sub.2′) based on a desired value for a power (P.sub.mech), the NOx emissions and a given level of an exhaust backpressure (p.sub.3′), wherein by the functional relationship it is taken account of an influence of a change of the exhaust backpressure (p3′) acting on at least one combustion chamber.

20. The internal combustion engine according to claim 1, wherein the open-loop or closed-loop control device is configured to change a bypass valve of a compressor when the bypass valve is adjusted such that the NO.sub.x emissions can be maintained at a constant level.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Further advantages and details of this invention are provided in the Figures and the associated description of those Figures. In that respect,

[0062] FIG. 1 shows a first embodiment of an internal combustion engine according to the invention,

[0063] FIG. 2 shows a second embodiment of an internal combustion engine according to the invention,

[0064] FIG. 3 shows a third embodiment of an internal combustion engine according to the invention,

[0065] FIG. 4 shows a fourth embodiment of an internal combustion engine according to the invention,

[0066] FIG. 5 shows a fifth embodiment of an internal combustion engine according to the invention,

[0067] FIG. 6 shows a sixth embodiment of an internal combustion engine according to the invention,

[0068] FIG. 7 shows a seventh embodiment of an internal combustion engine according to the invention,

[0069] FIG. 8 shows an eighth embodiment of an internal combustion engine according to the invention and

[0070] FIG. 9 shows a diagram of charge pressure over power for different exhaust backpressures.

DETAILED DESCRIPTION

[0071] FIG. 1 illustrates a first embodiment of an internal combustion engine 1 according to the invention. This internal combustion engine 1 has a combustion chamber 3 in which a fuel-air mixture is combusted. This invention is, of course, not restricted to a combustion chamber 3 and the combustion chamber 3 used in the Figures serves only as an example. The invention can be used on an internal combustion engine 1 for one or more combustion chambers 3 selectively and/or globally for all applications.

[0072] The fuel-air mixture is supplied to at least one combustion chamber 3 through a compressor 11 of a turbocharger 14, wherein the fuel-air mixture can be cooled after compression by the compressor 11 in a mixture cooler 17. The mixture cooler 17 and the compressor 11 can be bypassed by means of a bypass line with a bypass valve 10, wherein a charge pressure p2′ can be adjusted by this bypass valve 10 and with that charge pressure p2′ at least one combustion chamber 3 can be filled.

[0073] By changing the charge pressure p.sub.2′, it is possible to vary the filling of at least one combustion chamber 3 when having constant valve opening times for the internal combustion engine 1.

[0074] In addition, the turbocharger 14 has an exhaust turbine 13 that can be bypassed by a bypass line along with the bypass valve 12. By means of this bypass valve 12, an exhaust backpressure p.sub.3′ can be set which acts on the at least one combustion chamber 3.

[0075] An open-loop or closed-loop control device 2 is provided which is signal-conductively connected by means of signal conducting connections, on the one hand to the bypass valve 10 of the compressor 11 and on the other hand to the bypass valve 12 of the exhaust turbine 13. The bypass valve 10 of the compressor 11 (and also of the mixture cooler 17) in this embodiment is configured as an actuator 4 that influences combustion parameters. The bypass valve 12 of the exhaust turbine 13 in this embodiment forms the actuator 5 that influences the exhaust backpressure p.sub.3.

[0076] The open-loop or closed-loop control device 2 is configured to actuate the at least one actuator 4 (in this embodiment, the bypass valve 10 of the compressor 11) that influences the at least one combustion parameter (in this embodiment, the charge pressure p2′) as a substitute parameter for the NOx emission by means of a functional relationship in such way that at least one combustion parameter can be set for each target power or actual power rating of the internal combustion engine 1, wherein the functional relationship takes account of an influence of an adjustment of the at least one actuator 5 (in this embodiment, the bypass valve 12 of the exhaust turbine 13) that influences the exhaust backpressure p3′ acting on the at least one combustion chamber 3.

[0077] In other words, the open-loop or closed-loop control device is configured to change the bypass valve 10 of the compressor 11 when the bypass valve 12 is adjusted such that the NO.sub.x emissions can be maintained at a constant level, because any change of the position of the bypass valve 12 of exhaust turbine 13 has a direct influence on the exhaust backpressure p.sub.3′ (which acts on at least one combustion chamber 3) and therefore affects the NO.sub.x production in the at least one combustion chamber 3 (through a modified efficiency rating and modified residual gas components and temperatures). However, the NO.sub.x emissions can be maintained at a constant level by adapting the charge pressure p.sub.2′ through the bypass valve 10 of the compressor 11.

[0078] By means of the functional relationship saved in the open-loop or closed-loop control unit 2, the charge pressure p.sub.2′ can be determined based on the desired value for the power P.sub.mech, the NO.sub.x emissions and a given level of exhaust backpressure p.sub.3′. Specific details regarding this functional relationship will be explained at a later point (see FIG. 9).

[0079] FIG. 2 shows a similar embodiment, but in this second embodiment of the internal combustion engine 1, the actuator 5 that affects the exhaust backpressure p.sub.3′ is the variable turbine geometry of the exhaust turbine 13 of the turbocharger 14. By adjusting this variable turbine geometry, a change of the exhaust backpressure p.sub.3′ that acts on the at least one combustion chamber 3 is effected with which the bypass valve 10 of the compressor 11 is adjustable by means of the open-loop or closed-loop control device 2 on and the charge pressure p.sub.2′ is configurable by means of a functional relationship in order to maintain NO.sub.x emissions at a constant level.

[0080] In the embodiment shown in FIG. 3, a catalytic converter 16 is provided between the at least one combustion chamber 3 and exhaust turbine 13. Catalytic converters 16 of this kind are also known by the synonym PTCC converters and are used to release chemical energy in the flow of exhaust emissions, causing the exhaust temperature to increase leading to an explosion of exhaust gas, which in turn enables the material flow acting on the exhaust turbine 13 to increase with which the efficiency of the turbocharger 14 is improved. In order to open or closed loop control this process, a bypass valve 15 is provided on catalytic converter 16 and that bypass valve 15 has a signal-conducting connection 6 to the open-loop or closed-loop control unit 2.

[0081] The bypass valve 15 of the catalytic converter 16 is an actuator 5 that influences the exhaust backpressure p.sub.3′ by means of which in turn the bypass valve 10 of the compressor 11—when changing the position of the actuator 5 (of the bypass valve 15 of the catalytic converter 16) that influences the exhaust backpressure p3′—is actuated via the functional relationship in such way that a charge pressure p2′ is corrected accordingly to obtain the most constant NOx emission value possible.

[0082] The embodiment in FIG. 4 shows an internal combustion engine 1 that is similar to the embodiment in FIG. 1. However, in this embodiment, a throttle valve 8 is used as actuator 4 that influences the combustion parameter, which in turn can also influence the fill level of the at least one combustion chamber 3.

[0083] Then again, the embodiment in FIG. 5 illustrates a similar embodiment to the one in FIG. 3, but here the internal combustion engine 1 of the embodiment in FIG. 5 has a compressor 11 with a variable compressor geometry, wherein the compressor geometry and/or the adjusting unit of the compressor geometry is signal-conductively connected to the open-loop or closed-loop control unit 2 by means of a signal conducting connection 6 and the open-loop or closed-loop control unit 2 uses the variable compressor geometry of the compressor 11 as an actuator 4 for setting a combustion parameter (or more accurately, the charge pressure p.sub.2′).

[0084] The embodiment in FIG. 6 shows a similar embodiment to the one in FIG. 1, although the internal combustion engine 1 of the embodiment in FIG. 6 has a variable valve drive 7 that can be used to set the fill level of at least one combustion chamber 3 (for example, in accordance with an early or late Miller process). In turn, this variable valve drive 7 is connected to the open-loop or closed-loop control unit 2 by means of a signal-conducting connection 6, wherein the variable valve drive 7 as actuator 4 that affects the combustion parameter is closed loop or open loop controlled by means of the open-loop or closed-loop control unit 2.

[0085] The embodiment in FIG. 7 of an internal combustion engine 1 is also similar, but in the embodiment of FIG. 7 the actuation of an ignition device is used as the actuator 4 that influences the combustion parameter by means of such said actuation of an ignition device an ignition time for the combustion can be open-loop or closed-loop controlled. This happens by having the open-loop or closed-loop control unit 2 connected to the ignition unit of the at least one combustion chamber 3 by a signal-conducting connection 6.

[0086] The embodiment in FIG. 8 shows an internal combustion engine 1 that has an injection unit separated from the air intake for delivering fuel into at least one combustion chamber 3. This fuel injection unit for delivering fuel into at least one combustion chamber 3 is designed as a port injection valve 9.

[0087] Air is supplied via a compressor 11 of a turbocharger 14, wherein the compressed air is cooled before entering the at least one combustion chamber 3 by means of an intercooler 18. To be able to vary the charge pressure p.sub.2′, a bypass line with a bypass valve 10 for the compressor 11 is provided.

[0088] As already described in the preceding Figures, in the exhaust line an exhaust turbine 13 is provided and a catalytic converter 16 that is arranged between the exhaust turbine 13 and the at least one combustion chamber 3, and said catalytic converter 16 can be bypassed by a bypass line with a bypass valve 15 of the catalytic converter 16.

[0089] The open-loop or closed-loop control unit 2 is connected by signal conducting connections to an actuator 4 that influences combustion parameters and to an actuator 5 that influences the exhaust backpressure p.sub.3′.

[0090] The actuator 4 that influences combustion parameters in this embodiment is configured as port injection valve 9 by actuation of which can the combustion air ratio λ in the at least one combustion chamber 3 can be influenced. In this embodiment, the actuator 5 that affects exhaust backpressure p.sub.3′ is configured as bypass valve 15 of the catalytic converter 16.

[0091] FIG. 9 shows a diagram of the charge pressure p.sub.2′ of an internal combustion engine 1 illustrating the mechanical power P.sub.mech performed by the internal combustion engine 1. Shown here is the relationship regarding three different exhaust backpressures p.sub.3′ at a specified level of NO.sub.x emissions—i.e., identical on all three curves.

[0092] This diagram shows the mechanical power P.sub.mech of the internal combustion engine 1 with the charge pressure p.sub.2′ in context, wherein a curve is provided for each NO.sub.x target value (constant in the diagram shown here) and for each exhaust backpressure p.sub.3′. This set of curves forms the functional relationship.

[0093] To achieve a constant NO.sub.x emission level when changing the exhaust backpressure p.sub.3′ (for example, by changing actuator 5 that influences the exhaust backpressure p.sub.3′), a corresponding charge pressure p.sub.2′ must be selected to be able to maintain a constant mechanical power P.sub.mech of the internal combustion engine 1 of 75%. This functional relationship is to be used by the open-loop or closed-loop control unit 2 when regulating or controlling the internal combustion engine 1.

LIST OF REFERENCES

[0094] 1 Combustion engine [0095] 2 Open-loop or closed-loop control device [0096] 3 Combustion chamber [0097] 4 Actuator that influences combustion parameters [0098] 5 Actuator that influences exhaust backpressure [0099] 6 Signal conducting connection [0100] 7 Variable valve drive [0101] 8 Throttle valve [0102] 9 Port injection valve [0103] 10 Compressor bypass valve [0104] 11 Compressor [0105] 12 Exhaust turbine bypass valve [0106] 13 Exhaust turbine [0107] 14 Turbocharger [0108] 15 Catalytic converter bypass valve [0109] 16 Catalytic converter [0110] 17 Mixture cooler [0111] 18 Intercooler [0112] p.sub.2′ Charge pressure [0113] P.sub.3′ Exhaust backpressure [0114] λ Compression air ratio [0115] P.sub.mech Mechanical power