Method and device for operating a combustion engine by means of a firing angle model

Abstract

The invention relates to a computer-implemented method for operating a motor system (1) having a combustion motor (2), wherein a functional relationship between one or more operating state variables and an ignition angle (ZW max ) is depicted by means of a non-parametric data-based ignition angle model (13), in particular as a Gaussian process model, wherein the combustion motor (2) is operated with operating variables which depend on the ignition angle model (13).

Description

Technical Field

[0001] This invention relates to a method for operating a combustion motor based on its internal torque. Furthermore, this invention relates to a method for determining the internal torque of the combustion motor and the ignition angle to be set. Background Technology

[0002] To operate a motor system with a combustion motor, the internal torque of the combustion motor is typically determined based on its operating parameters. The internal torque of the combustion motor corresponds to the torque generated by the combustion of fuel, without considering frictional or scavenging losses.

[0003] Generally, the internal torque is determined using a torque model based on the operating parameters of the combustion motor. This torque model is based on a software structure of combined characteristic curves, which has multiple characteristic curves and combined characteristic curves. These characteristic curves or combined characteristic curves must be parameterized individually for each type of combustion motor. The torque model is guided by physical correlations and influencing factors.

[0004] The torque model is complex, and the inaccuracy of the operating parameters significantly affects the accuracy of determining the internal torque of the combustion motor. However, the accuracy required for determining the internal torque is particularly high when using a combustion motor in a hybrid drive system. Therefore, for example, to coordinate the partial drive torque to be provided by the electric drive unit and the combustion motor in the hybrid drive system, the torque of the electric drive unit must be matched with the internal torque of the combustion motor. Thus, the accuracy of modeling the internal torque of the combustion motor determines the torque coordinates and thereby the drivability of the vehicle operating with such a hybrid drive system. Summary of the Invention

[0005] According to the present invention, a method for operating a motor system having a combustion motor according to internal torque is provided according to claim 1, as well as an apparatus and a motor system according to the parallel claims.

[0006] Other design options are described in the dependent claims.

[0007] According to a first aspect, a method for operating a motor system with a combustion motor, implemented by a computer, is provided, wherein a nonparametric, data-based ignition angle model, particularly constructed as a Gaussian process model, is used to describe the functional relationship between one or more operating state parameters and the ignition angle, wherein the combustion motor is operated using operating parameters that depend on the ignition angle model.

[0008] The drawback of the torque models used to date for determining internal torque is that they rely on operating state parameters that are either inaccurately measured or cannot be directly measured and must be modeled using a suitable operating state model. This can result in these operating state parameters having considerably high errors, which propagate through the conventional torque model and lead to inaccurate determinations of the internal torque.

[0009] The residual gas ratio, for example, represents an operating parameter that can only be determined imprecisely, indicating the proportion of exhaust gas present in the cylinder after the intake valve is closed.

[0010] Therefore, the calculated internal torque of the combustion motor may be more or less accurate depending on the operating point. Consequently, the determination of the internal torque of the combustion motor is not robust enough for specific applications, such as torque coordination in hybrid drive systems. Although such inaccuracies can be compensated for in conventional torque models by means of calibration characteristic curves, this significantly increases parameterization overhead.

[0011] The idea behind the above method is to use a data-based ignition angle model to obtain the ignition angle (ignition timing relative to the crankshaft angle) for the reference torque that can be determined at the current operating point by means of operating state parameters, and to calculate the actual internal torque of the combustion motor based on the obtained ignition angle and the current ignition angle by means of a pre-given efficiency characteristic curve.

[0012] The reference torque is the theoretically possible maximum torque, which cannot be achieved at all operating points in practice, for example due to detonation or other physical limitations, and it is generated during the optimization process.

[0013] By utilizing a data-based ignition angle model that can depict operating state parameters onto the ignition angle used as a reference torque using training data, it is possible to achieve this without needing to understand the physical relationship between the operating state parameters and the parameters used as input parameters.

[0014] To train the ignition angle model, measurements are taken of the motor system, where all important operating parameters are modified using optimized rasterization. This data is then used to train the ignition angle model as a whole.

[0015] Therefore, it is possible to detect the ignition angle for the reference torque in a test bench over a large operating range that depends on the operating state parameters, and to learn, train, or obtain a data-based ignition angle model from it.

[0016] Because the data-based ignition angle model can also depict higher-dimensional interactions between operating parameters, its use improves accuracy in determining internal torque. These higher-dimensional interactions involve the form g(x1,…,x…). n The relationship between n and n is defined as follows: n > 2. Using only standard combined characteristic curves and characteristic curves requires breaking down such relationships into multiple low-dimensional functions and the operations between them. This is not always possible without loss of accuracy. However, with a Gaussian process model, this limitation to a maximum of three interacting input parameters is unnecessary.

[0017] It can be specified that the efficiency characteristic curve is used to plot the ignition angle difference onto the efficiency.

[0018] Furthermore, a reference torque model can be provided to obtain a reference torque at an operating point described by one or more operating state parameters, thereby generating the internal torque of the combustion motor by applying the efficiency to the reference torque.

[0019] According to one implementation, the internal torque can be obtained based on the current ignition angle by: obtaining a reference ignition angle with reference torque using the ignition angle model, obtaining the ignition angle difference relative to the current ignition angle, and determining the internal torque of the combustion motor based on the ignition angle difference using an efficiency characteristic curve, wherein the combustion motor is operated based on the internal torque.

[0020] According to another implementation, the ignition angle to be set can be determined based on the rated torque by: obtaining the reference ignition angle with the reference torque using the ignition angle model; obtaining the efficiency from the rated torque and the reference torque present at the existing operating point; determining the ignition angle difference using an inverted efficiency characteristic curve; obtaining the ignition angle to be set with the reference torque from the ignition angle difference and the reference ignition angle; and operating the combustion motor according to the ignition angle to be set.

[0021] It can be specified that one or more operating status parameters include one or more of the following parameters or descriptions:

[0022] -Motor speed;

[0023] - Description of valve lift distribution, especially valve closing and opening times and / or camshaft phase information;

[0024] -λ value (air-fuel ratio of combustion exhaust gas);

[0025] - Residual gas ratio;

[0026] -External or internal exhaust gas recirculation rate;

[0027] - When the intake valve opens;

[0028] - The closing time of the exhaust valve;

[0029] -The pressurization pressure in the suction tube;

[0030] - The amount of fresh air filling the cylinder;

[0031] - Parameters, which indicate the adjustment positions of the combustion motor's regulating elements, such as the camshaft-phase adjuster, camshaft-lift adjuster, regulator for adjusting the compression ratio, throttle, exhaust valve, etc.

[0032] -Motor load;

[0033] - Ignition angle,

[0034] - Parameters that indicate fuel composition, such as the ethanol content of the fuel; and

[0035] - Description of environmental conditions.

[0036] Furthermore, a correction factor-model can be provided for correcting ignition angle difference, wherein the correction factor-model is particularly constructed as a data-based function model, and particularly as a Gaussian process model.

[0037] According to another aspect, there is provided an apparatus, in particular a motor controller, for operating a motor system having a combustion motor, wherein the apparatus is configured to describe the functional relationship between one or more operating state parameters and the ignition angle by means of a nonparametric, data-based ignition angle model, particularly as a Gaussian process model, and to operate the combustion motor with operating parameters depending on the ignition angle model.

[0038] According to another aspect, a motor system is provided, which includes a combustion motor and the aforementioned device. Attached Figure Description

[0039] The embodiments are explained in detail below with reference to the accompanying drawings. Wherein:

[0040] Figure 1 A schematic diagram of a motor system with a combustion motor is shown;

[0041] Figure 2 A flowchart is shown to illustrate a method for determining the internal torque of a combustion motor.

[0042] Figure 3A flowchart is shown illustrating a method for determining the internal torque at the operating point of a combustion motor; and

[0043] Figure 4 A flowchart is shown to illustrate a method for determining an optimized ignition angle to be set at the operating point of a combustion motor. Detailed Implementation

[0044] Figure 1 A schematic diagram of an exemplary motor system 1 with a combustion motor 2, particularly an externally ignited combustion motor 2, is shown. The combustion motor 2 can be configured as a four-stroke motor, particularly as a gasoline motor. Other types of combustion motors can also be used in the methods described below, where the internal torque needs to be known to operate the combustion motor. Therefore, alternative motor systems can provide external exhaust gas recirculation, camshaft phase adjustment, valve lift adjustment, and / or other adjustments.

[0045] The combustion motor 2 has a plurality of cylinders 3 (four cylinders in the illustrated embodiment), each cylinder containing a combustion chamber and a piston (not shown) arranged in a movable manner. The pistons are coupled to a crankshaft 4 in a manner known per se to drive the crankshaft.

[0046] Each cylinder 3 is equipped with an ignition mechanism 5, which ignites the fuel-air mixture added to the combustion chamber of the cylinder 3. Fresh air is supplied to the combustion motor 2 via an air supply system 6. This fresh air is introduced into the relevant cylinder 3 at specific time intervals via a camshaft coupled to the crankshaft 4, under the control of an intake valve 7. Furthermore, each cylinder has an exhaust valve 8 through which combustion exhaust gases can be discharged into the exhaust gas discharge section 9.

[0047] In addition, a booster mechanism 10 can be provided, which has a turbine 12 in the exhaust gas discharge section 9 and a compressor 13 in the air supply system 6 for converting the supplied exhaust gas enthalpy into compression power and providing fresh air at a boost pressure upstream of the throttle valve 11.

[0048] A motor controller 15 is provided, which controls the operation of the combustion motor 2 according to a predetermined parameter V, such as a rated torque, which can be predetermined by or based on the accelerator pedal position. Furthermore, the motor controller 15 operates the combustion motor 2 according to operating state parameters, which may include parameters detected by sensors in the motor system 1, adjustment parameters for position encoders (e.g., for the position of the throttle valve 11), and for the power regulation of the boost regulator 10, as well as the opening and closing times of the intake and exhaust valves, etc.

[0049] exist Figure 2 The document provides a function circuit diagram for determining the internal torque of the combustion motor 2 based on one or more of the following operating state parameters, such as:

[0050] -Motor speed n;

[0051] - Motor load, which is expressed, for example, in the form of a relative air volume F in the relevant cylinder;

[0052] - Explanation regarding valve lift distribution;

[0053] -Current ignition angle,

[0054] - The ignition angle is used to generate an ignition spark through the ignition mechanism 5, wherein the ignition angle is defined as the crankshaft angle with the top dead center of the piston movement in the combustion chamber of the cylinder as the starting point.

[0055] -λ value (air-fuel ratio of combustion exhaust gas);

[0056] - Residual gas ratio (RR);

[0057] - The amount of fresh air filling the cylinder;

[0058] -External or internal exhaust gas recirculation rate (AGR);

[0059] - Intake valve 7 opening time (KW) E,O (At a specific crankshaft angle when the intake valve is opened);

[0060] - Closing time of exhaust valve 8 (KW) A,S (At a specific crankshaft angle when the exhaust valve is closed);

[0061] -The pressurization pressure in the suction tube;

[0062] - The amount of fresh air filling the cylinder;

[0063] - Parameters, which indicate the adjustment positions of the combustion motor's regulating elements, such as the camshaft-phase adjuster, camshaft-lift adjuster, regulator for adjusting the compression ratio, throttle, exhaust valve, etc.

[0064] - Parameters that indicate fuel composition, such as the ethanol content of the fuel; and

[0065] - Description of environmental conditions, such as ambient air temperature and / or ambient air pressure.

[0066] For the internal torque M i The calculation is performed based on the function shown in the function circuit diagram. The reference torque model 11 provides a series of combined characteristic curves and / or characteristic curves that, based on at least several of the operating state parameters, determine the reference torque M of the combustion motor 2 at the current operating point described by the considered operating state parameters. max .

[0067] The reference torque M max The signal is fed to multiplication block 12, where it is multiplied by the efficiency e to obtain the internal torque M. i .

[0068] In addition, an ignition angle model 13 was established, which was trained based on the data. This ignition angle model uses available operating state parameters to determine the reference ignition angle ZW for the reference torque. max In subtraction block 14, the reference ignition angle ZW used for the reference torque is... max Subtract the current ignition angle ZW from the middle akt This is used to provide the ignition angle difference ΔZW.

[0069] In another multiplication block 15, the ignition angle difference ΔZW is multiplied by the correction factor KF to obtain the corrected ignition angle difference ΔZW.

[0070] The correction factor KF can be provided through a combined characteristic curve model or another data-based correction factor function model 16. This is also based on the operating state parameters.

[0071] The corrected ignition angle difference ΔZW is fed to a pre-defined efficiency characteristic curve to provide efficiency e, particularly in a multiplicative manner to the reference torque M. max The efficiency is applied to obtain the internal torque M of the combustion motor 2. i .

[0072] In order to operate the combustion motor 2, a description of the internal torque can be used. Especially when the combustion motor is used in a hybrid drive system, the internal torque M... i A precise understanding is necessary. For the corresponding reference torque M... max Reference ignition angle ZW max The modeling can obtain intermediate information using the ignition angle model. From this, the efficiency of the combustion motor 2 can be determined using the efficiency characteristic curve 17, which can be used to reduce the reference torque M based on the efficiency. max .

[0073] exist Figure 3 The flowchart shown depicts the process for determining the internal torque M of the combustion motor 2. i The principle of the method.

[0074] Therefore, in step S1, the operating state parameters are detected or modeled, and in step S2, they are used as input parameters for a pre-given nonparametric, data-based ignition angle model. The nonparametric, data-based function model can be a function model compiled from measured data points, such as a Gaussian process model, etc. This nonparametric, data-based function model is compiled such that it provides combustion characteristics as model values ​​dependent on the input parameters.

[0075] The use of nonparametric, data-based function models is based on Bayesian regression. The foundations of Bayesian regression are illustrated, for example, in "Gaussian Processes for Machine Learning" by Rasmussen et al., published by MIT Press in 2006. Bayesian regression is a data-based approach, which in turn is model-based. To construct a model, measurement points from one or more input parameters and raw values ​​of the output parameters detected on the system to be modeled are required. The model is constructed using support point data, which is entirely or partially derived from or generated from the training data. Furthermore, abstract hyperparameters and coefficients are determined, which spatially parameterize the model function and effectively weight the influence of each measurement point in the training data onto the subsequent model predictions.

[0076] The abstract hyperparameters are determined through optimization methods. One feasible approach for such optimization methods lies in edge similarity. The optimization of edge similarity. Given model parameters H and the numerical values ​​of x in the training data (the values ​​of the input parameters), the reliability of the measured y values ​​in the training data is described as a vector Y. This is used during model training. Maximizing this is achieved by finding suitable hyperparameters that cause a curve of change in the model function, determined by the hyperparameters and training data, and that depicts the training data as accurately as possible. To simplify computation, [the following steps are taken]. The logarithm is maximized because the logarithm does not change the continuity of the credibility function.

[0077] The calculation of the Gaussian process model is performed according to the following steps. First, the input values ​​for the test point x (input parameter vector) are used. Standardize and settle, and more precisely, this is done according to the following formula:

[0078] .

[0079] Here, mx corresponds to the average function of the input values ​​of the support point data, and s x The variance of the input values ​​corresponding to the support point data, and d corresponds to the exponent of the dimension D used for the test point x.

[0080] As a result of compiling the nonparametric, data-based function model, parameters for the following functions are obtained:

[0081] .

[0082] The model value v thus obtained is standardized by means of output standardization, and more precisely, by standardization according to the following formula:

[0083] .

[0084] Here, v corresponds to the normalized model value (original value) at the normalized test point x (the input parameter vector of dimension D). Corresponding to (unstandardized) test points The (unnormalized) model values ​​(raw values) on the (input parameter vector of dimension D), x i For the support point data, N corresponds to the number of support points in the support point data, D corresponds to the dimension of the input data / training data / support point data space, and I d and σ f Corresponding to the hyperparameters derived from model training. The coefficient vector Q y It is calculated from hyperparameters and training data. Furthermore, m y The average function corresponding to the average of the raw values ​​of the support point data and s y The variance corresponding to the original values ​​of the support point data.

[0085] The data-based ignition angle model 13 can be developed by measuring the combustion motor 2 on a test bench within a large range of operating parameters and using the obtained measurement data as training data points to develop a Gaussian process model in a known manner. The Gaussian process model is defined as a set of support points, coefficient vectors, and hyperparameters.

[0086] Specifically, the ignition angle model 13 can be trained by determining the ignition timing for reference torque for each specific operating state defined by operating state parameters. Here, the ignition angle can be changed when adjusting the operating state to select an ignition angle for which the torque provided by the combustion motor is maximized.

[0087] Now, in step S3, the reference ignition angle ZW, obtained by reading from the ignition angle model, can be used as the reference torque. max The information ZW relative to the current ignition timing is obtained in the manner described above. akt The ignition angle difference ΔZW.

[0088] In step S4, a correction factor KF is applied to the ignition angle difference ΔZW. This correction factor is generated from the correction factor function model 16 based on the operating state parameters. The correction factor model 16 is then trained in a corresponding manner.

[0089] In particular, the application parameters, data-based ignition angle model, and correction factor-function model were optimized using tools such as ETAS, ASCMO, and MOCA. Here, we need to observe the optimization issues:

[0090]

[0091] Where N corresponds to the number of measurement points, p corresponds to the application parameters, and the data-based ignition angle model and the correction factor-function model are... The measurement point i is achieved by means of... Figure 2 The model shown in the figure is used to model the internal torque M. i When using the application parameter p, The torque M corresponding to the force measured at measurement point i i Because optimization with reasonable overhead may not find the overall optimal value, a suitable starting point can be chosen. Furthermore, the optimization order can be predetermined, allowing optimization to be performed in multiple steps, with only a subset of the parameters p observed in each step. Therefore, for example, the correction factor-function model cannot be observed for the first optimization and can only be used again in the second step to further improve accuracy.

[0092] Then, in step S5, the efficiency characteristic curve is used to calculate the corrected ignition angle difference loaded with a correction factor. To determine the efficiency. The efficiency characteristic curve shows that it depends on the corrected ignition angle difference. The efficiency is used as a factor, and the efficiency e is used to provide the efficiency.

[0093] In step S6, the reference torque M is generated from the operating state parameters and a suitable reference torque model. max The reference torque model can be obtained from operating state parameters, for example, using characteristic curves and combined characteristic curves. Alternatively, this reference torque model can also be described using a data-based function model.

[0094] In step S7, by directing the reference torque M max The internal torque is determined by the loading efficiency e.

[0095] In step S8, the combustion motor 2 can be operated according to the internal torque. Then, the process jumps back to step S1.

[0096] In another mode of operation— Figure 4 The process is illustrated—the ignition angle to be set is obtained from a pre-given rated torque for internal torque. To obtain the ignition angle produced at a specific rated torque from a pre-given model, the model shown can be inverted along the dimensions of the ignition angle difference ΔZW. This enables the process as described in... Figure 2 The torque model architecture shown is based on the efficiency characteristic curve and the reference torque M. max Reference ignition angle ZW max With the current ignition angle ZW akt The difference between them is not part of the ignition angle model 13.

[0097] In step S11, the internal torque M is provided. i The rated torque.

[0098] In step S12, the reference torque M is determined from the provided operating state parameters using the reference torque model 11. max .

[0099] The rated torque and the reference torque M in the current operating condition. max The quotient between the two can be used to determine the efficiency e in step S13.

[0100] By inverting the efficiency characteristic curve 17, the corrected ignition angle difference can be obtained in step S14. .

[0101] The corrected ignition angle difference can be obtained by dividing the correction factor KF known at the current operating point based on the forward calculation of the correction factor-function model 16 in step S15, in order to obtain the uncorrected ignition angle difference ΔZW.

[0102] In step S16, based on the forward calculation of the ignition angle model 13, the reference ignition angle ZW for the reference torque is subtracted from the uncorrected ignition angle difference ΔZW at the current operating point. max This method is used to obtain the current ignition angles ZW and ZW that need to be set. akt This causes the desired rated torque.

[0103] In step S17, the determined current ignition angle ZW is used akt To run the combustion motor 2 and continue the method using step S11.

Claims

1. A computer-implemented method for operating a motor system (1) with an internal combustion engine (2), wherein one or more operating state parameters are described in relation to the ignition angle (ZW) by means of a nonparametric, data-based ignition angle model (13). max The functional relationship between the internal combustion engine (2) and the internal combustion engine (2) is operated using operating parameters that depend on the ignition angle model (13), wherein the efficiency characteristic curve (17) is used to map the ignition angle difference (ΔZW) to the efficiency of the internal combustion engine (2) operation.

2. The method according to claim 1, wherein a reference torque model is provided, the reference torque model being used to determine the reference torque (M) at the operating point described by one or more operating state parameters. max ), thereby by directing the reference torque (M) max The efficiency is achieved by generating the internal torque (M) of the internal combustion engine (2) in this manner. i ).

3. The method according to claim 1 or 2, wherein the current ignition angle (ZW) is used. akt To obtain the internal torque (M) i The method is as follows: using the ignition angle model (13) as a reference torque (M) max To obtain the reference ignition angle (ZW) max From this, the ignition angle difference (ΔZW) relative to the current ignition angle is obtained, and the internal torque (M) of the internal combustion engine (2) is determined by means of the efficiency characteristic curve (17) based on the ignition angle difference (ΔZW). i ), where according to the internal torque (M) i (2) to run the internal combustion engine.

4. The method according to claim 1 or 2, wherein the ignition angle (ZW) to be set is determined based on the rated torque by: using the ignition angle model (13) with reference torque (M) max To obtain the reference ignition angle (ZW) max The method is as follows: from the rated torque and the possible reference torque (M) at the existing operating point. max The efficiency (e) is obtained from the inverted efficiency characteristic curve, wherein the ignition angle difference (ΔZW) is determined by means of the ignition angle difference (ΔZW) and the ignition angle, wherein the reference torque (M) is obtained from the ignition angle difference (ΔZW) and the ignition angle. max (2) to obtain the ignition angle (ZW) to be set, wherein the internal combustion engine (2) is operated according to the ignition angle (ZW) to be set.

5. The method according to claim 1 or 2, wherein one or more operating status parameters include one or more of the following parameters or descriptions: -Motor speed (n); -λ value (air-fuel ratio of combustion exhaust gas); - Explanation of valve lift and its distribution; - Residual gas ratio (RR); - Internal exhaust gas recirculation rate (AGR); -Intake valve (7) opening time (KW) E,O ); - Closing time of exhaust valve (8) (KW) A,S ); -Boost pressure in the intake manifold; - The amount of fresh air filled in cylinder (3); - Parameters, which indicate the adjustment position of the adjustment element of the internal combustion engine (2); -Motor load; - Ignition angle (ZW) - A parameter indicating the adjustment position of the adjustment element of the internal combustion engine (2); - Parameters indicating the composition of the fuel; and - Description of environmental conditions.

6. The method of claim 3, wherein a correction factor-model (16) is provided for correcting the ignition angle difference (ΔZW), wherein the correction factor-model (16) is constructed as a data-based function model.

7. The method of claim 1, wherein one or more operating state parameters are described in relation to the ignition angle (ZW) by means of a nonparametric, data-based ignition angle model (13) constituting a Gaussian process model. max The functional relationship between them.

8. The method of claim 5, wherein the parameter indicating the composition of the fuel is the ethanol content of the fuel.

9. The method according to claim 6, wherein the correction factor-model (16) is constructed as a Gaussian process model.

10. An apparatus for operating a motor system (1) having an internal combustion engine (2), wherein the apparatus is configured to depict a functional relationship between one or more operating state parameters and the ignition angle (ZW) by means of a nonparametric, data-based ignition angle model (13) and to operate the internal combustion engine (2) with operating parameters depending on the ignition angle model (13), wherein the apparatus is configured to map the ignition angle difference (ΔZW) to the efficiency of the operation of the internal combustion engine (2) using an efficiency characteristic curve (17).

11. The apparatus of claim 10, wherein the apparatus is a motor controller.

12. The apparatus of claim 10, wherein the apparatus is configured to describe the functional relationship between one or more operating state parameters and the ignition angle (ZW) by means of a nonparametric, data-based ignition angle model (13) which is a Gaussian process model.

13. Motor system (1), including -Internal combustion engine (2) and - The apparatus according to any one of claims 10 to 12.

14. A computer program configured to perform all the steps of the method according to any one of claims 1 to 9.

15. A machine-readable storage medium having stored thereon the computer program according to claim 14.

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