Method for operating an internal combustion engine, computer program, storage medium, control device for carrying out such a method, and internal combustion engine

Abstract

The invention relates to a method for operating an internal combustion engine, the method comprising the following steps: - providing a gas-path model (S1) for a gas path of the internal combustion engine and an internal combustion engine actual value (S2) of at least one internal-combustion-engine parameter of the internal combustion engine that is input into the gas path model, - determining at least one constraint (S4) for at least one gas-path parameter of the gas path based on the gas-path model and the at least one internal combustion engine actual value by varying at least one control value for controlling at least one gas-path adjustment device of the gas path, and - operating the internal combustion engine depending on the at least one determined constraint (S5).

Description

[0001] DESCRIPTION

[0002] Method for operating an internal combustion engine, computer program, storage medium and control device for carrying out such a method, and internal combustion engine

[0003] The invention relates to a method for operating an internal combustion engine, a computer program, a computer-readable storage medium and a control device for an internal combustion engine for carrying out such a method, as well as an internal combustion engine with such a control device.

[0004] When controlling a gas path based on physical and / or mathematical models, particularly so-called hyperspace control, input and output linearization is typically used, whereby manipulated variables are determined to achieve desired setpoints. In concrete technical applications, however, it is possible that a superimposed control system specifies a setpoint for the gas path that cannot be reached in a given operating situation, or at least not within a specific timeframe. For example, depending on the current operating point of the internal combustion engine, there may be limitations on boost pressures achievable within a specific timeframe.

[0005] combustion air conditions result. This is obviously disadvantageous not only because the requested setpoint cannot be regulated, but also because the superimposed control system calculates with the setpoint – which in reality cannot be regulated – and thus determines other setpoints or manipulated variables suboptimally, taking this setpoint into account.

[0006] The invention is therefore based on the objective of providing a method for operating an internal combustion engine, a computer program, a computer-readable storage medium, and a control device for an internal combustion engine for carrying out such a method, as well as an internal combustion engine with such a control device, wherein the aforementioned disadvantages are at least reduced, and preferably do not occur. This objective is achieved by providing the present technical teaching, in particular the teaching of the independent claims and the preferred embodiments disclosed in the dependent claims and the description.

[0007] The task is solved, particularly in a first aspect, by creating a method for operating an internal combustion engine, which includes the following steps:

[0008] - Providing a gas path model for a gas path of the internal combustion engine, and providing an actual value of at least one internal combustion engine parameter included in the gas path model,

[0009] - Determine at least one limit for at least one gas path parameter of the gas path based on the gas path model and the at least one internal combustion engine actual value by varying at least one control value for controlling at least one gas path adjustment device of the gas path, and

[0010] - Operating the internal combustion engine depending on the at least one determined limit.

[0011] By determining at least one limit for at least one gas path parameter and operating the internal combustion engine according to this limit, it is advantageously possible to consider which objectives can actually be achieved in the current operating situation, i.e., which setpoints can actually be regulated. This particularly helps to avoid a higher-level control system outputting unattainable setpoints; this, in turn, means that other setpoints or manipulated variables are calculated assuming realistic, actually achievable setpoints, thus improving the overall control system.

[0012] In one embodiment, the internal combustion engine is controlled at least two levels. A higher-level control system globally regulates the engine, while a gas path control system locally regulates the gas path based on a gas path model. The higher-level control system specifies gas path setpoints for the gas path control system based on the overall operating conditions of the internal combustion engine. These setpoints are then regulated by the gas path control system, for example, a specific boost pressure or a specific fresh air mass flow rate. In one embodiment, the gas path control system determines the at least one limit and then transmits this limit to the higher-level control system.The higher-level regulation then advantageously takes into account the at least one transmitted limitation when determining the gas path setpoints for the at least one gas path parameter.

[0013] In one embodiment, a gas path model created prior to the execution of the method, i.e., in steps preceding the method proposed here, can be used. This model is preferably provided in a predefined or pre-configured form. In another embodiment, the gas path model is created anew within the framework of the method proposed here; that is, it is provided by being created.

[0014] The actual value of at least one internal combustion engine parameter is preferably detected by means of a suitable parameter sensor on the internal combustion engine, for example by means of a speed sensor to detect the rotational speed of the internal combustion engine, and is made available - in particular to the gas path model - directly or indirectly via a higher-level control system.

[0015] In the context of this technical teaching, the fact that the at least one limit for the at least one gas path parameter is determined by varying the at least one control value for controlling the at least one gas path adjustment device means, in particular, that the at least one control value is varied and, using the gas path model (i.e., computationally), it is checked which values ​​the at least one gas path parameter can assume when the at least one control value is varied. In this process, certain discrete control values ​​can be checked, which are assigned, in particular, to certain discrete positions of the at least one gas path adjustment device, for example, extremal positions, i.e., in particular a minimum and a maximum position. However, it is also possible that the control value is varied continuously, in particular between control values ​​assigned to a minimum and a maximum position.In one embodiment, actual values ​​of a plurality of internal combustion engine parameters included in the gas path model are provided. Alternatively or additionally, limits for a plurality of gas path parameters are determined, and the internal combustion engine is operated depending on these limits. Alternatively or additionally, control values ​​for controlling a plurality of gas path adjustment devices are varied to determine at least one limit.

[0016] The minimum limit can be a momentary limit. Alternatively or additionally, the minimum limit can apply to a predetermined time horizon, meaning it can specify which values ​​or value ranges are unattainable within that predetermined time horizon.

[0017] In the context of this technical teaching, a gas path is understood to be a path of the internal combustion engine that carries gas flows, in particular an air or charging path - hereinafter referred to as a fresh air path -, an exhaust gas path, a combination of a fresh air and an exhaust gas path, or at least a separate sub-path of a fresh air and / or exhaust gas path.

[0018] In the context of the present technical teaching, a gas path adjusting device is understood to be a device, for example a flap or a valve, which is designed to change, in particular adjust, a flow cross-section at least in a section of the gas path.

[0019] In the context of this technical teaching, a control value for controlling at least one gas path adjusting device is understood to be, in particular, a value or quantity suitable for controlling a gas path adjusting device, that is, for moving the gas path adjusting device into an adjusting position associated with the control value or achievable by control with the control value. The control value can be directly suitable for controlling the gas path adjusting device, for example, by being configured directly as an adjusting position or as a voltage or current value associated with the adjusting position. However, it can also be indirectly suitable for controlling the gas path adjusting device by causing the gas path adjusting device, when set or specified, to at least approach, and preferably reach, the corresponding adjusting position through further mechanisms or resulting effects.In one embodiment, the control value is a flap position or valve position of a flap or valve in the gas path, particularly in terms of timing.

[0020] In the context of this technical teaching, a gas path parameter is understood to be a parameter suitable for characterizing, influencing, or being influenced by the flow in the gas path or a sub-path of the gas path. The gas path parameter may, for example, be selected from a group consisting of a temperature, a pressure, a mass flow rate, and a combination of at least two of the aforementioned quantities. The gas path parameter may also be a quantity located or measured outside the gas path, for example, a parameter of another gas path. In particular, the gas path parameter may be a quantity of the fresh air path, such as a fresh air mass, a fresh air mass flow rate, or a boost pressure, especially if the at least one gas path adjustment device is / are arranged in the fresh air path or exhaust gas path.For example, there is a relationship between the fresh air mass flow or boost pressure and a flow cross-section in a turbine bypass path of an exhaust gas turbocharger.

[0021] In one embodiment of the method, a gas path is controlled which has at least one gas path component selected from a group consisting of a fresh air compressor, an exhaust gas turbine, a compressor bypass path (also referred to as a compressor bypass), a turbine bypass path (also referred to as a turbine bypass), an exhaust gas recirculation path, an exhaust gas donor path, and a combination of at least two of the aforementioned gas path components.

[0022] The fresh air compressor can be designed as a motor-driven compressor, for example by an electric motor or – for example via a belt or chain drive – by the internal combustion engine itself, in particular as a so-called compressor. Alternatively or additionally, the fresh air compressor can be driven by the exhaust gas turbine; in this case, the fresh air compressor and the exhaust gas turbine are part of an exhaust gas turbocharger, or simply turbocharger of the gas path. The exhaust gas turbine can also be driven by an electric machine acting as a generator. Furthermore, it can be driven directly via a drive shaft or indirectly, for example electrically, via a magnetic coupling, or via a belt or chain drive.

[0023] In one embodiment, the gas path features a two-stage or multi-stage compression system, preferably with a low-pressure compressor and a high-pressure compressor. Alternatively or additionally, the gas path features a high-pressure turbine and a low-pressure turbine. It is possible for the low-pressure turbine to be driven by the low-pressure compressor, and for the high-pressure turbine to be driven by the high-pressure compressor, in which case the gas path as a whole comprises a low-pressure turbocharger and a high-pressure turbocharger.

[0024] According to the foregoing embodiments, the gas path can include a low-pressure compressor bypass path and, alternatively or additionally, a high-pressure compressor bypass path. Alternatively or additionally, the gas path can include a low-pressure turbine bypass path and, further alternatively or additionally, a high-pressure turbine bypass path.

[0025] In the context of this technical teaching, an exhaust gas recirculation path is understood to be a flow path that is arranged and configured to direct exhaust gas from an exhaust gas path into a fresh air path, thereby partially mixing the exhaust gas into a fresh air mass flow that is supplied to at least one combustion chamber of the internal combustion engine. An exhaust gas recirculation path cooler – also referred to as an EGR cooler – may be arranged in the exhaust gas recirculation path.

[0026] In the context of this technical teaching, an exhaust gas donor path is understood to be a flow path that is arranged and configured to direct exhaust gas from a first partial exhaust gas path originating from at least one combustion chamber not intended, or not primarily intended, for exhaust gas recirculation – also referred to as a non-donor cylinder – into a second partial exhaust gas path originating from a combustion chamber intended primarily or solely for exhaust gas recirculation – also referred to as a donor cylinder – or directly into the exhaust gas recirculation path. The second partial exhaust gas path is fluidically connected to the exhaust gas recirculation path or is itself part of the exhaust gas recirculation path.Alternatively or additionally, the gas path includes at least one gas path adjusting device selected from a group consisting of a compressor bypass path adjusting device, a turbine bypass path adjusting device, an exhaust gas recirculation path adjusting device, an exhaust gas donor adjusting device, and a fresh air path adjusting device, and a combination of at least two of the aforementioned gas path adjusting devices.

[0027] A compressor bypass path adjusting device is understood to be, in particular, a flap or a valve which is arranged and configured in the compressor bypass path bypassing the fresh air compressor in order to change, preferably adjust, a flow cross-section of the compressor bypass path.

[0028] A turbine bypass path adjusting device is understood to be, in particular, a flap or a valve which is arranged and configured in the turbine bypass path bypassing the exhaust turbine in order to change, preferably adjust, a flow cross-section of the turbine bypass path.

[0029] In one embodiment, the gas path includes a low-pressure compressor bypass path adjustment device and, alternatively or additionally, a high-pressure compressor bypass path adjustment device. Alternatively or additionally, the gas path includes a low-pressure turbine bypass path adjustment device and, further alternatively or additionally, a high-pressure turbine bypass path adjustment device.

[0030] An exhaust gas recirculation path adjusting device is understood to be, in particular, a flap or a valve which is configured to change, preferably to adjust, the exhaust gas recirculation rate in the exhaust gas recirculation path. The exhaust gas recirculation path adjusting device is preferably arranged in the exhaust gas recirculation path and configured to change, preferably to adjust, the flow cross-section of the exhaust gas recirculation path.

[0031] An exhaust gas distributor adjustment device is understood to be, in particular, a flap or a valve which is arranged and configured to change, preferably adjust, the flow cross-section of the exhaust gas distributor path. Preferably, the exhaust gas distributor adjustment device is arranged within the exhaust gas distributor path. In one embodiment, the exhaust gas distributor path containing the exhaust gas distributor adjustment device and the exhaust gas return path containing the exhaust gas recirculation path adjustment device are arranged such that the exhaust gas from the at least one distributor cylinder is completely routed into the fresh air path when the exhaust gas distributor adjustment device is fully closed and, optionally, when the exhaust gas recirculation path adjustment device is fully open.When the exhaust gas donor adjustment device is opened in this configuration, a portion of the exhaust gas from at least one non-donor cylinder enters the exhaust gas recirculation path, depending on the specific pressure differential. Simultaneously, a portion of the exhaust gas from the donor cylinder also enters the exhaust gas path through which it is discharged. As a result, in this configuration—assuming the exhaust gas recirculation path adjustment device is held in a constant position—the more the exhaust gas donor adjustment device is opened, the less exhaust gas is typically recirculated into the fresh air path. In an embodiment where there are the same number of donor cylinders as non-donor cylinders, 50% of the exhaust gas mass flow is recirculated into the fresh air path when the exhaust gas donor adjustment device is fully closed and, optionally, the exhaust gas recirculation path adjustment device is fully open.

[0032] In one embodiment, however, the dispenser adjustment device is preferably designed such that it cannot be completely closed. Preferably, the dispenser adjustment device is open from 40% to 100%.

[0033] A fresh air path adjustment device is understood to be, in particular, a flap or a valve which is configured to change, preferably to adjust, the flow cross-section in the fresh air path. The fresh air path adjustment device can, for example, be designed as a throttle valve.

[0034] The gas path model preferably includes at least one internal combustion engine parameter as a gas path model parameter. The at least one internal combustion engine parameter can be selected from a group consisting of an actuation position of the at least one gas path adjusting device, in particular the actuation positions of all gas path adjusting devices, an exhaust gas temperature, the internal combustion engine speed, a fuel mass flow rate or a fuel mass introduced into the at least one combustion chamber, and a combination of at least two of the aforementioned parameters.

[0035] A positioning position is understood in particular to be a functional position of the gas path adjustment device that determines the flow cross-section assigned to the respective gas path adjustment device, in particular a flap angle or a valve position.

[0036] According to a further development of the invention, the at least one gas path parameter is selected from a group consisting of a boost pressure, a fresh air mass flow, and a combination of the aforementioned gas path parameters. Advantageously, highly relevant limitations for the operation of the internal combustion engine can be determined and taken into account in this way.

[0037] According to a further development of the invention, the at least one internal combustion engine parameter – in particular as a gas path model parameter – is selected from a group consisting of an exhaust gas temperature, the internal combustion engine speed, a fuel mass, i.e., in particular a fuel mass flow rate or an absolute fuel mass introduced into the at least one combustion chamber per unit of time or per operating cycle, and a combination of the aforementioned internal combustion engine parameters. Advantageously, these internal combustion engine parameters are particularly relevant for determining the at least one limit.

[0038] According to a further development of the invention, at least one limiting parameter is determined as the at least one limiting parameter, which describes an operating range achievable for the at least one gas path parameter. The advantages already described are realized in a particularly effective way in this process.

[0039] In one embodiment, the at least one limiting parameter describes an operating range currently achievable for the at least one gas path parameter. Alternatively or additionally, the at least one limiting parameter describes an operating range achievable for the at least one gas path parameter over the predetermined time horizon. In one embodiment, the operating range is a one-dimensional operating range, in particular a scalar limit, for example a lower limit or an upper limit. In this case, the limiting parameter can be identical to the operating range. Alternatively, the operating range is a multidimensional operating range, in particular a range within a multidimensional characteristic map. In one embodiment, the operating range is a polytope, where, in the context of this technical teaching, a polytope is understood to be, in particular, a generalized polygon of arbitrary dimension.This is also referred to as a t / -polytope with dimension d.

[0040] In one embodiment, the at least one limiting parameter describes the operating range achievable for the at least one gas path parameter, which lies within a characteristic map defined by the at least one gas path parameter. In one embodiment, the characteristic map in which the operating range lies is thus defined by at least two gas path parameters, in particular by those gas path parameters for which a respective limit is determined. For example, the characteristic map can be defined by the fresh air mass flow and the boost pressure, wherein the operating range is a two-dimensional polytope arranged in this two-dimensional characteristic map, which can be described by vertices and boundary lines extending between the vertices, with values ​​accessible for the gas path parameters lying within the operating range.

[0041] According to a further development of the invention, the at least one limiting parameter is selected from a group consisting of a corner point of the achievable operating range, a boundary line of the achievable operating range, a slope of a boundary line of the achievable operating range, and a combination of at least two of the aforementioned limiting parameters. Each of these parameters is suitable for describing the achievable operating range and thus for describing or defining the at least one limit. Advantageously, when considering the slope of a boundary line, a dynamic aspect can also be taken into account.

[0042] According to a further development of the invention, it is provided that, in addition, the behavior of the achievable operating range is determined as a function of the at least one internal combustion engine parameter – in particular using the gas path model. In this way, in particular, dynamics can be advantageously taken into account.

[0043] In the context of this technical teaching, determining the behavior of the achievable operating range as a function of at least one internal combustion engine parameter means, in particular, determining the potential development of the achievable operating range as a function of that at least one internal combustion engine parameter. Preferably, the potential development of the achievable operating range is determined as a function of a predicted development of the at least one internal combustion engine parameter, and in particular, is predicted for a predetermined forecast period. Specifically, the achievable operating range depends on the at least one internal combustion engine parameter, both on its current value and on future values ​​of that parameter.For example, at a given operating point, characterized, for instance, by a specific fuel mass flow, engine speed, and exhaust gas temperature, a turbocharger can only achieve a certain maximum boost pressure due to limited exhaust gas enthalpy. This maximum achievable boost pressure varies with these parameters and, in particular, with their future values. Essentially, the entire achievable operating range is influenced by at least one engine parameter. Control of the gas path and the engine as a whole can be improved by considering this behavior of the achievable operating range.

[0044] According to a further development of the invention, at least one Gaussian process model is used as the gas path model. Preferably, a Gaussian process is used as the gas path model, which includes a Gaussian process model for each gas path parameter.

[0045] Gaussian process models are particularly well-suited for controlling the gas path of an internal combustion engine: Compared to polynomial-based models, they are significantly easier to adapt to new or changed data points in the application field, and they exhibit more suitable and physically accurate behavior in the boundary regions of the given parameter space. Compared to physical models, they require considerably less computational effort. Furthermore, they allow the direct use of test bench data. Such a Gaussian process model is specifically defined by stored data points (Xb,Yb), obtained, for example, from test bench trials, where X b in particular n input variables for m different operating states and with Y b £ R m x k In particular, k output variables are specified for the m different operating states. Specifically, the input variables Xb form a subset of the union of the control values ​​for the at least one gas path adjustment device and the gas path model parameters. The output variables Y b are a subset of the gas path parameters. Furthermore, the Gaussian process model is defined by a predefined calculation scheme for an expected value E(X") e R. z x k and a variance Var(X) for input variables not included in the original dataset for 1 different operating states X u £ R" x / given: with a mean value function m(X u a predetermined variance 2, the identity matrix I, and a covariance function K, which depends on the Euclidean distance r between two points xi, X2 in the following way: with a predetermined baseline parameter d and a predetermined signal variance a F . Therefore, in equations (1) and (2) K(X) u ^ b ) ER z x m , KX b b) £ R m x m , I £ R m x m and Y b £ gm xk

[0046] The mean value function m(x) is preferably obtained in turn as a Gaussian process model.

[0047] In particular, a basic Gaussian process model, also referred to as a basic grid, is first fitted to second test bench data subject to at least one constraint derived from the first test bench data. Specifically, input variables X are considered. b selected, and the associated output variables Y bare calculated in such a way that a deviation of the expected value E(X) of the basic Gaussian process model, which is based on the input variables X bThe initial parameters Yb are determined and minimized to the second set of test bench data while adhering to the constraint. Furthermore, for the purpose of determining the basic Gaussian process model, m(x) = 0 is preferably assumed for its mean value function. The first set of test bench data comprises a larger parameter space than the second set of test bench data. It is possible that the first set of test bench data is measured on a single-cylinder test bench, while the second set of test bench data is measured on a complete engine or also on a single-cylinder test bench, and in the latter case preferably converted to the complete engine using a simulation model. The constraint is preferably obtained as a trend, whereby, for example, it is determined whether certain parameters behave linearly or monotonically with respect to each other.If no such trend is detected, the constraint can be omitted, in which case the adaptation of the basic Gaussian process model to the second test bench data is also referred to as unconstrained.

[0048] The expected value of the basic Gaussian process model obtained in this way is then used in a next step as the mean value function m(x) in an additional Gaussian process model, into which the second test bench data are now included as known input variables Xb2 and output variables Yb2.

[0049] According to a further development of the invention, the method is carried out continuously during the operation of the internal combustion engine. Advantageously, it can be ensured that the at least one limitation is continuously taken into account during the operation of the internal combustion engine.

[0050] The problem is also solved in a second aspect by creating a computer program that contains instructions which, when the computer program is executed on a computing device, in particular on a control device for an internal combustion engine, cause the computing device to carry out a method according to the invention or a method according to one or more of the embodiments described above. The advantages that arise in connection with the computer program are those already explained in connection with the method.

[0051] The task is also solved in a third aspect by using a computer-readable

[0052] A storage medium is created on which the computer program according to the invention or a computer program according to one or more of the embodiments described above is stored. The advantages associated with the storage medium are particularly those already explained in connection with the method or the computer program.

[0053] The problem is also solved in a fourth aspect by creating a control device for an internal combustion engine, which is configured to carry out a method according to the invention or a method according to one or more of the embodiments described above. The advantages that arise in connection with the control device are particularly those already explained in connection with the method, the computer program, or the storage medium.

[0054] In one embodiment, the control device comprises a first partial control device, which is designed and / or configured as the gas path control unit for controlling the gas path. In particular, the first partial control device is operatively connected to the gas path sensor and the gas path adjustment devices. Furthermore, the control device comprises a second partial control device, which is designed or configured as the higher-level control unit for the internal combustion engine. The first partial control device and the second partial control device are operatively connected to each other for data transmission, meaning they can communicate with each other and exchange data.In particular, the second control unit can transmit setpoints for the gas path to the first control unit, which then regulates them; furthermore, the first control unit can transmit at least one limit to the second control unit, which is then taken into account before the second control unit when specifying the setpoints for the gas path – and at least implicitly also when calculating other setpoints or control commands for the operation of the internal combustion engine. Thus, the internal combustion engine is operated by the second control unit depending on the at least one limit.

[0055] The first and second partial control devices can be designed as separate control units. Alternatively, they can be designed as separate modules of the same control unit; furthermore, they can also be implemented as software modules on a common control unit. A fourth aspect of the problem is also solved by creating an internal combustion engine with a gas path and a control device according to the invention or a control device according to one or more of the embodiments described above. In connection with the internal combustion engine, the advantages that have already been explained in connection with the method, the computer program, the storage medium, or the control device become particularly apparent.

[0056] According to a further development of the invention, the gas path comprises at least one gas path component selected from a group consisting of a fresh air compressor, an exhaust gas turbine, a compressor bypass path, a turbine bypass path, an exhaust gas recirculation path, an exhaust gas donor path, and a combination of at least two of the aforementioned gas path components.

[0057] Alternatively or additionally, the gas path has at least one gas path adjusting device selected from a group consisting of a compressor bypass path adjusting device, a turbine bypass path adjusting device, an exhaust gas recirculation path adjusting device, an exhaust gas donor adjusting device, a fresh air path adjusting device, and a combination of at least two of the aforementioned gas path adjusting devices.

[0058] The exhaust gas recirculation path adjustment device is advantageously arranged upstream of an exhaust gas recirculation path cooler (EGR cooler). Alternatively or additionally, the exhaust gas donor adjustment device is arranged in an exhaust gas donor path of the internal combustion engine and, from a fluid dynamics perspective, between a first combustion chamber (a donor cylinder) primarily or solely intended for exhaust gas recirculation and a second combustion chamber (a non-donor cylinder) of the internal combustion engine, not primarily intended for exhaust gas recirculation.

[0059] In a preferred embodiment, the internal combustion engine has at least two gas path adjustment devices selected from the group consisting of the compressor bypass path adjustment device, the turbine bypass path adjustment device, the exhaust gas recirculation path adjustment device, the exhaust gas donor adjustment device, the fresh air path adjustment device, and a combination of at least two of the aforementioned gas path adjustment devices.

[0060] In a particularly preferred embodiment, the internal combustion engine has three gas path adjusting devices, in particular the turbine bypass path adjusting device, the exhaust gas recirculation path adjusting device, and the exhaust gas donor adjusting device.

[0061] The internal combustion engine preferably has at least one gas path sensor configured to determine an actual value of at least one gas path parameter and / or the actual value of at least one internal combustion engine parameter. Particularly preferably, the internal combustion engine has a first gas path sensor configured to determine an actual value of the engine's boost pressure. Alternatively or additionally, the internal combustion engine has a second gas path sensor configured to determine an actual value of the engine's fresh air mass flow rate. The at least one gas path sensor is preferably operatively connected to the control device – in particular to at least one interface of the control device.Alternatively or additionally, the internal combustion engine preferably has at least one parameter sensor which is configured to determine the at least one actual value of the internal combustion engine parameter, for example a speed sensor for recording the rotational speed of the internal combustion engine.

[0062] The task will be explained in more detail below using the drawing, which will show:

[0063] Figure 1 shows a schematic representation of an embodiment of an internal combustion engine with a control device for operating the internal combustion engine;

[0064] Figure 2 shows a schematic representation of an embodiment of a method for operating the internal combustion engine, and

[0065] Figure 3 shows a schematic representation of an embodiment of an operating range achievable for at least one gas path parameter of the gas path.

[0066] Fig. 1 shows a schematic representation of an embodiment of an internal combustion engine 1 with a control device 3 for operating the internal combustion engine 1. In this embodiment, the internal combustion engine has a gas path 5, in particular a fresh air path 6 as a first sub-path of the gas path 5, and an exhaust gas path 7 as a second sub-path of the gas path 5. Furthermore, the internal combustion engine 1 includes, by way of example, two combustion chambers 9 and a turbocharger 11 with a fresh air compressor 11.1 and an exhaust gas turbine 11.2. Gas path adjustment devices 13 are arranged in the gas path 5, specifically an exhaust gas recirculation path adjustment device 17 in an exhaust gas recirculation path 15, an exhaust gas donor adjustment device 21 in an exhaust gas donor path 19, and a turbine bypass path adjustment device 25 in a turbine bypass path 23. The fresh air compressor 11.1 and the exhaust gas turbine 11.2, the exhaust gas recirculation path 15, the exhaust gas donor path 19 and the turbine bypass path 23 are in particular gas path components 10 of the gas path 5.

[0067] The internal combustion engine 1 can optionally also have a compressor bypass path 22, indicated here only schematically by a dashed line, as a further gas path component 10. A compressor bypass path adjusting device 24 can be arranged in the compressor bypass path 22 as a further gas path adjusting device 13. A fresh air path adjusting device 26, indicated only by a dashed line, can optionally be arranged in the fresh air path 6 as a further gas path adjusting device 13.

[0068] As shown in Figure 1, fresh air is supplied to the internal combustion engine 1 via a fresh air opening 27 of the fresh air path 6. Exhaust gas is also discharged from the internal combustion engine 1 via an exhaust gas opening 29 of the exhaust gas path 7.

[0069] The internal combustion engine 1 also has a gas path sensor 31, which is arranged in the fresh air path 6 of the internal combustion engine 1. The gas path sensor 31 is configured to determine the actual value of at least one gas path parameter and / or the actual value of at least one internal combustion engine parameter.

[0070] The control device 3 is set up to carry out a procedure described in more detail below in connection with Figure 2.

[0071] The control device 3 preferably comprises a first sub-control device 3.1, which is configured for controlling the gas path 5. In particular, the first sub-control device 3.1 is operatively connected to the gas path sensor 31 and the gas path adjustment device in 13. Furthermore, the control device 3 comprises a second sub-control device 3.2, which is configured as a higher-level control unit for the internal combustion engine 1 or is configured for higher-level control of the internal combustion engine 1. The first sub-control device 3.1 and the second sub-control device 3.2 are operatively connected to each other for data transmission, i.e., they can communicate with each other and exchange data. In particular, the second sub-control device 3.2 can transmit setpoint values ​​for the gas path 5 to the first sub-control device 3.1, which are then adjusted by the first sub-control device 3.1; furthermore, the first sub-control device 3.2 can...1. At least one limit is transmitted to the second sub-control device 3.2, which is then taken into account before the second sub-control device 3.1 when specifying the setpoint values ​​for the gas path 5 – and at least implicitly also when calculating other setpoint values ​​or control commands for the operation of the internal combustion engine 1. Thus, the internal combustion engine 1 is operated by the second sub-control device 3.2 depending on the at least one limit.

[0072] Fig. 2 shows a schematic representation of an embodiment of a method for operating the internal combustion engine 1.

[0073] Identical and functionally equivalent elements are provided with the same reference symbols in all figures, so that reference is made to the preceding description in each case.

[0074] In a first step S1, a gas path model is provided, in particular in the form of a Gaussian process, which preferably includes a Gaussian process model for each gas path parameter to be calculated.

[0075] In a second step S2, an actual value of at least one internal combustion engine parameter of internal combustion engine 1, which is included in the gas path model, is provided, preferably a plurality of such actual values ​​for a plurality of internal combustion engine parameters. In particular, an overall situation of internal combustion engine 1 is considered.

[0076] In a third step S3, optional maximum positioning positions of the gas path are set.

[0077] The adjustment devices 13 determine, read, or receive the data. It is possible that the maximum adjustment positions are predetermined by the design, but it is also possible that the maximum adjustment positions change during the operation of the gas path adjustment devices 13 or depending on an operating situation of the internal combustion engine 1.

[0078] In a fourth step S4, at least one limit for at least one gas path parameter of the gas path 5 is determined based on the gas path model and the at least one internal combustion engine actual value by varying at least one control value for controlling at least one gas path adjustment device 13. Preferably, the maximum adjustment positions from step S3 are taken into account.

[0079] In a fifth step S5, the internal combustion engine 1 is operated depending on the at least one determined limit.

[0080] In particular, the second step S2, the fourth step S4, and the fifth step S5 are preferably repeated continuously during the operation of the internal combustion engine 1 – in the form of a loop. Thus, a current limit is always available. It is possible that the third step S3 is also repeated in every iteration. However, it is also possible that the third step S3 is performed only temporarily, in particular only once during a first iteration, or as needed. Furthermore, it is possible that the first step S1 is performed only initially before a first iteration of the process; however, it is also possible that the first step S1 is performed temporarily, in particular as needed, especially to be able to adapt the gas path model if necessary. It is also possible that the first step S1 is performed in every iteration.

[0081] The at least one gas path parameter is preferably selected from a group consisting of a boost pressure, a fresh air mass flow, and a combination of the aforementioned gas path parameters.

[0082] The at least one internal combustion engine parameter is preferably selected from a group consisting of an exhaust gas temperature, an internal combustion engine speed, a fuel mass, and a combination of the aforementioned internal combustion engine parameters. The at least one limit is preferably determined as a limit parameter that describes an operating range achievable for the at least one gas path parameter, preferably within a characteristic map defined by the at least one gas path parameter.

[0083] Fig. 3 shows a schematic representation of an embodiment of an operating range 33 achievable for at least one gas path parameter of the gas path 5.

[0084] Operating range 33 is a two-dimensional area within a characteristic map spanned by a fresh air mass flow m. L and a boost pressure PL. In particular, operating range 33 is a 2-polytope. The characteristic map is thus defined by two gas path parameters, specifically by those gas path parameters for which a respective limit is also determined. The 2-polytope can be described by corner points 35 and boundary lines 37 extending between the corner points 35. Values ​​accessible for the gas path parameters lie within the 2-polytope.

[0085] For example, a first vertex 35.1 is reached when the turbine bypass path adjusting device 25 and the exhaust gas recirculation path adjusting device 17 are fully closed, and at the same time the exhaust gas dispenser adjusting device 21 is fully open. A second vertex 35.2 is reached when the exhaust gas recirculation path adjusting device 17 is fully closed, and at the same time the turbine bypass path adjusting device 25 and the exhaust gas dispenser adjusting device 21 are fully open. A third vertex 35.3 is reached when the turbine bypass path adjusting device 25 and the exhaust gas recirculation path adjusting device 17 are fully open, and at the same time the exhaust gas dispenser adjusting device 21 is fully closed. A fourth vertex 35.A fifth corner point 35.5 is reached when the exhaust gas recirculation path adjusting device 17 is fully open and, at the same time, the turbine bypass path adjusting device 25 and the exhaust gas dispenser adjusting device 21 are fully closed. A fifth corner point 35.5 is reached when the turbine bypass path adjusting device 25 is fully closed and, at the same time, the exhaust gas recirculation path adjusting device 17 and the exhaust gas dispenser adjusting device 21 are fully open. Preferably, the at least one limiting parameter is selected from a group consisting of a corner point 35, a limit line 37, a slope of the limit line 37, and a combination of at least two of the aforementioned limiting parameters.

[0086] Preferably, the behavior of the achievable operating range 33 is additionally determined using the gas path model as a function of the at least one internal combustion engine parameter – in particular, using the gas path model. Preferably, a potential development of the achievable operating range 33 is determined as a function of a predicted development of the at least one internal combustion engine parameter, and in particular, a prediction is made for a predetermined forecast period. In this way, the achievable operating range 33 essentially "breathes" with the at least one internal combustion engine parameter.

Claims

REQUIREMENTS 1. Method for operating an internal combustion engine (1) comprising the following steps: - Providing a gas path model (Sl) for a gas path (5) of the internal combustion engine (1) and an internal combustion engine actual value (S2) of at least one internal combustion engine parameter of the internal combustion engine (1) that is included in the gas path model, - Determine at least one limit (S4) for at least one gas path parameter of the gas path (5) using the gas path model and the at least one internal combustion engine actual value by varying at least one control value for controlling at least one gas path adjustment device (13) of the gas path (5), and - Operating the internal combustion engine (S5; 1) depending on the at least one determined limit.

2. Method according to claim 1, wherein the at least one gas path parameter is selected from a group consisting of a boost pressure, a fresh air mass flow, and a combination of the aforementioned gas path parameters.

3. Method according to one of the preceding claims, wherein the at least one internal combustion engine parameter is selected from a group consisting of an exhaust gas temperature, an internal combustion engine speed, a fuel mass, and a combination of the aforementioned internal combustion engine parameters.

4. Method according to one of the preceding claims, wherein the at least one limit is determined as at least one limiting parameter which describes an operating range (33) achievable for the at least one gas path parameter, in particular in a characteristic field spanned by the at least one gas path parameter.

5. Method according to claim 4, wherein the at least one limiting parameter is selected from a group consisting of a corner point (35) of the achievable operating range (33), a limit line (37) of the achievable operating range (33), a slope of a Limit line (37) of the achievable operating range (33), and a combination of at least two of the limit parameters mentioned.

6. Method according to one of claims 4 or 5, wherein, in addition, the behavior of the achievable operating range (33) is determined as a function of the at least one internal combustion engine parameter using the gas path model.

7. Method according to any of the preceding claims, wherein at least one Gaussian process model is used as the gas path model.

8. Method according to any of the preceding claims, wherein the method is carried out continuously during the operation of the internal combustion engine (1).

9. Computer program comprising instructions which, when the computer program is executed on a computing device, in particular on a control device (3) for an internal combustion engine (1), cause the computing device to carry out a method according to one of claims 1 to 8.

10. Computer-readable storage medium on which the computer program according to claim 9 is stored.

11. Control device (3) for an internal combustion engine (1), configured to carry out a method according to claims 1 to 8.

12. Internal combustion engine (1) with a gas path (5) and a control device (3) according to claim 11.

13. Internal combustion engine (1) according to claim 12, wherein the gas path (5) - at least one gas path component (10) selected from a group consisting of a fresh air compressor (11.1), an exhaust gas turbine (11.2), a compressor bypass path (22), a turbine bypass path (23), an exhaust gas recirculation path (15), an exhaust gas donor path (19), and a combination of at least two of the aforementioned gas path components (10), and / or - at least one gas path adjustment device (13) selected from a group consisting of a compressor bypass path adjustment device (24), a turbine bypass path adjustment device (25), an exhaust gas recirculation path adjustment device (17), an exhaust gas dispenser adjustment device (21), and a fresh air path adjustment device (26), and a combination of at least two of the aforementioned gas path adjustment devices (13).

Images