A method for constructing an engine torque model and an engine torque model

Abstract

The application provides an engine torque model construction method and an engine torque model, and relates to the technical field of model construction methods.The engine torque model construction method constructs an initial ignition angle efficiency model according to a preset ignition angle efficiency curve, inputs the difference between an actual ignition angle and an optimal ignition angle into the initial ignition angle efficiency model to output ignition angle efficiency, and substitutes a plurality of groups of arrays into the initial ignition angle efficiency model to obtain a plurality of ignition angle efficiency models corresponding to the plurality of groups of arrays.The ignition angle efficiency model construction process can make the constructed engine torque model high in precision, thereby improving the precision of engine output torque, and making the torque deviation within a certain range, and improving the NVH characteristics of the engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of model construction methods, in particular to a construction method of an engine torque model. BACKGROUND

[0002] Ignition angle efficiency, also known as ignition loss rate, is the relationship between the change in ignition angle output and the change in torque when other control parameters remain unchanged. Ignition angle efficiency is the core content of engine torque model calibration, and the accuracy of ignition angle efficiency calibration directly determines the accuracy of torque control. Torque accuracy has a direct impact on vehicle shift quality and vehicle drivability, and also has an indirect impact on engine emissions and fuel consumption.

[0003] The existing ignition angle efficiency confirmation method is polynomial fitting.

[0004] Torque data is collected under different conditions such as engine speed and load, and under different ignition angles. An ignition angle efficiency curve is fitted by filtering and processing the collected data. The ignition angle efficiency confirmation method described above has the following disadvantages: 1. Insufficient torque model accuracy; 2. The optimal ignition angle (MBT) represents the ignition angle corresponding to the maximum torque output. Normally, the optimal ignition angle should not be less than the base ignition angle, making the optimal ignition angle output unreasonable. SUMMARY

[0005] One object of the first aspect of the present application is to provide a construction method of an engine torque model to solve the problem of insufficient torque model accuracy in the prior art.

[0006] Another object of the first aspect of the present application is to solve the problem of unreasonable optimal ignition angle output of the existing torque model.

[0007] One object of the second aspect of the present application is to provide a construction method of an engine torque model.

[0008] In particular, the present application also provides a construction method of an engine torque model, which includes an ignition angle efficiency model for outputting a target ignition angle efficiency curve. The construction method of the ignition angle efficiency model includes the following steps:

[0009] An initial ignition angle efficiency model is built according to a preset ignition angle efficiency curve. The initial ignition angle efficiency model is a mathematical function related to a sine function and containing a plurality of unknown coefficients.

[0010] inputting a difference between the actual ignition angle and an optimal ignition angle into the initial ignition angle efficiency model to output an ignition angle efficiency, and performing multiple input and output cycles to obtain multiple sets of arrays containing numerical values of all unknown coefficients, the optimal ignition angle being obtained according to the rotational speed and the load;

[0011] substituting the multiple sets of arrays into the initial ignition angle efficiency model to obtain multiple ignition angle efficiency models corresponding to the multiple sets of arrays.

[0012] Optionally, in the step of establishing the initial ignition angle efficiency model according to the preset ignition angle efficiency curve, a mathematical relationship of the initial ignition angle efficiency model is:

[0013] y = asin(bx + c) + dsin(ex + f)

[0014] wherein y is the ignition angle efficiency, x is the difference between the optimal ignition angle and the actual ignition angle, and a, b, c, d, e and f are the unknown coefficients.

[0015] Optionally, a mathematical relationship of the initial ignition angle efficiency model is:

[0016] y = (bcos(c)sin(ex + f) - ecos(f)sin(bx + c)) / (bcos(c)sin(f) - ecos(f)sin(c)).

[0017] Optionally, in the step of inputting the difference between the actual ignition angle and the optimal ignition angle into the initial ignition angle efficiency model, the optimal ignition angle is obtained by an optimal ignition angle model, and a method for establishing the optimal ignition angle model comprises the following steps:

[0018] establishing a relationship of adding an ignition angle offset value to a basic ignition angle to obtain the optimal ignition angle as an initial optimal ignition angle model, the basic ignition angle being obtained according to the rotational speed and the load;

[0019] inputting the rotational speed and the load into the initial optimal ignition angle model;

[0020] constraining the ignition angle offset value in the initial optimal ignition angle model to be positive;

[0021] performing input and output cycles of the entire engine torque model when the initial optimal ignition angle model is combined with the initial ignition angle efficiency model to obtain multiple target optimal ignition angle models corresponding to different rotational speeds and loads.

[0022] Optionally, the initial optimal ignition angle model is combined with the initial ignition angle efficiency model, and input and output cycles are performed to further obtain multiple sets of values of the unknown coefficients.

[0023] Optionally, after obtaining the values of the plurality of unknown coefficients, the method further comprises:

[0024] The values of any one of the plurality of unknown coefficients are brought into the initial ignition angle efficiency model to obtain a target ignition angle efficiency model corresponding to the rotational speed and the load corresponding to the unknown coefficient.

[0025] Optionally, the target optimal ignition angle model is combined with the target ignition angle efficiency model, and an input-output cycle is performed, and a plurality of sets of corresponding basic ignition angle arrays, ignition angle offset value arrays and ignition angle efficiency curves under different rotational speeds and loads are obtained.

[0026] In particular, the application also provides an engine torque model obtained by the above-mentioned method for constructing an engine torque model.

[0027] Optionally, the method comprises:

[0028] The ignition angle efficiency model is obtained by bringing the values of the plurality of unknown coefficients into the initial ignition angle efficiency model after obtaining the values of the plurality of unknown coefficients from the initial ignition angle efficiency model containing a plurality of unknown numbers through various input and output;

[0029] The optimal ignition angle model is obtained by bringing the values of the plurality of unknown coefficients into the initial ignition angle efficiency model after obtaining the values of the plurality of unknown coefficients from the initial optimal ignition angle model and the initial ignition angle efficiency model through multiple input and output.

[0030] Optionally, the initial ignition angle efficiency model is a mathematical function containing a plurality of unknown coefficients related to a sine function;

[0031] The mathematical function is y=asin(bx+c)+dsin(ex+f), x is the difference between the optimal ignition angle and the actual ignition angle, y is the ignition angle efficiency, and a, b, c, d, e, and f are the unknown parameters;

[0032] Wherein, x=0 is input, y=1 is output, and x=0 is input, y′=0 is output, the initial ignition angle efficiency model is obtained by solving, and the initial ignition angle efficiency model is y=(bcos(c)sin(ex+f)-ecos(f)sin(bx+c)) / (bcos(c)sin(f)-ecos(f)sin(c)).

[0033] In the present application, the initial ignition angle efficiency model is built according to the preset ignition angle efficiency curve, the difference between the actual ignition angle and the optimal ignition angle is input into the initial ignition angle efficiency model to output the ignition angle efficiency, and the multiple sets of arrays are substituted into the initial ignition angle efficiency model to obtain multiple ignition angle efficiency models corresponding to the multiple sets of arrays. The engine torque model built by the process can have high precision, thereby improving the precision of the engine output torque and making the torque deviation within a certain range, and improving the NVH characteristics of the engine.

[0034] Further, in the present application, the relationship formula of obtaining the optimal ignition angle by adding the base ignition angle to the ignition angle offset value is constructed as an initial optimal ignition angle model, the base ignition angle is obtained according to the speed and load, and the ignition angle offset value in the initial optimal ignition angle model is constrained to be positive, and the optimal ignition angle model is obtained by the process. The real-time optimal ignition angle is greater than the base ignition angle, so that the output of the optimal ignition angle is reasonable, and the output ignition efficiency curve is improved.

[0035] The above and other objects, advantages and features of the present application will become more apparent from the following detailed description of some embodiments thereof, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0036] Some specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that the drawings are not necessarily drawn to scale. In the drawings:

[0037] Figure 1 is a schematic flow chart of a method for constructing an engine torque model according to one specific embodiment of the present application;

[0038] Figure 2 is a schematic flow chart of a method for constructing an engine torque model according to another specific embodiment of the present application;

[0039] Figure 3 is a schematic flow chart of a method for constructing an engine torque model according to another specific embodiment of the present application;

[0040] Figure 4 is a schematic structural block diagram of an engine torque model according to one specific embodiment of the present application;

[0041] Figure 5 is a graph of an ignition angle efficiency curve output by an engine torque model according to one specific embodiment of the present application;

[0042] Figure 6 is a deviation diagram of an engine torque model according to one specific embodiment of the present application. DETAILED DESCRIPTION

[0043] Figure 1 is a schematic flow chart of a method for constructing an engine torque model according to a specific embodiment of the present application. As a specific embodiment of the present application, the embodiment provides a method for constructing an engine torque model. The engine torque model can include a spark angle efficiency model for outputting a target spark angle efficiency curve, and the method for constructing the spark angle efficiency model can include the following steps:

[0044] Step S100, constructing an initial spark angle efficiency model according to a preset spark angle efficiency curve, the initial spark angle efficiency model being a mathematical function related to a sine function and containing a plurality of unknown coefficients;

[0045] Step S200, inputting a difference between an actual spark angle and an optimal spark angle into the initial spark angle efficiency model to output a spark angle efficiency, and performing a plurality of input and output cycles to obtain a plurality of sets of arrays containing numerical values of all unknown coefficients, the optimal spark angle being obtained according to a speed and a load;

[0046] Step S300, substituting the plurality of sets of arrays into the initial spark angle efficiency model to obtain a plurality of spark angle efficiency models corresponding to the plurality of sets of arrays.

[0047] Specifically, before constructing the initial spark angle efficiency model, the inventors obtain a large number of spark angle efficiency curves, the shapes of which are generally similar to a sine function. Therefore, when constructing the initial spark angle efficiency model, the initial spark angle efficiency model is constructed as a sine function model. Specifically, the initial spark angle efficiency model can be y = asin(bx + c) + dsin(ex + f), where y is the spark angle efficiency, x is the difference between the optimal spark angle and the actual spark angle, and a, b, c, d, e, and f are all unknown coefficients.

[0048] Since in the actual use of the engine, it is known that when x = 0, y = 1, and when x = 0, y' = 0. Substituting them into the above relationship and converting can obtain the initial spark angle efficiency model as y = (bcos(c)sin(ex + f) - ecos(f)sin(bx + c)) / (bcos(c)sin(f) - ecos(f)sin(c)).

[0049] In step S200, the difference between the actual spark angle and the optimal spark angle is input into the model to output the spark angle efficiency, and after a plurality of input and output cycles, a plurality of spark angle efficiency models can be obtained.

[0050] The model built in the above manner can obtain a high-precision ignition angle efficiency model, thereby improving the precision of engine output torque and making the torque precision deviation within a certain range, and improving the torque characteristics of the engine.

[0051] Figure 2 is a schematic flow chart of a method for building an engine torque model according to another specific embodiment of the present application; as a specific embodiment of the present application, in the step of inputting the difference between the actual ignition angle and the optimal ignition angle into the initial ignition angle efficiency model, the optimal ignition angle is obtained by calculation of an optimal ignition angle model, and the method for building the optimal ignition angle model comprises the following steps:

[0052] In step S400, a relationship formula of adding the base ignition angle to the ignition angle offset value to obtain the optimal ignition angle is built as an initial optimal ignition angle model, and the base ignition angle is obtained according to the rotation speed and the load;

[0053] In step S500, the rotation speed and the load are input into the initial optimal ignition angle model;

[0054] In step S600, the ignition angle offset value in the initial optimal ignition angle model is constrained to be positive;

[0055] In step S700, the input-output cycle of the entire engine torque model is performed when the initial optimal ignition angle model is combined with the initial ignition angle efficiency model, so as to obtain a target optimal ignition angle model corresponding to a plurality of different rotation speeds and loads.

[0056] In the embodiment, the base ignition angle can be obtained by inputting the rotation speed and the load in the initial ignition angle model, the optimal ignition angle is obtained by adding the base ignition angle to the ignition angle offset value, and in actual cases, the optimal ignition angle is greater than the base ignition angle, so it is necessary to constrain the ignition angle offset value to be positive.

[0057] In the embodiment, since the ignition angle offset value is constrained to be positive, the real-time optimal ignition angle is greater than the base ignition angle, so that the output of the optimal ignition angle is reasonable, and the ignition efficiency curve output is improved.

[0058] Figure 3 is a schematic flow chart of a method for building an engine torque model according to another specific embodiment of the present application. As a specific embodiment of the present application, the method for building the engine torque model of the embodiment further comprises step S800 of combining the initial optimal ignition angle model with the initial ignition angle efficiency model and performing the input-output cycle, and further obtaining the values of a plurality of unknown coefficients.

[0059] Generally, the number of the values of the position coefficient determines the number of the output and the number of the input and output cycles, at least, in order to obtain the values of the position coefficient. The more the number of the input and output cycles, the more the subsequent values are obtained, and the more accurate the values are.

[0060] After obtaining the values of the plurality of unknown coefficients, the method further comprises:

[0061] In step S900, the values of the unknown coefficients are brought into the initial ignition angle efficiency model to obtain a target ignition angle efficiency model corresponding to the speed and the load.

[0062] The target optimal ignition angle model and the target ignition angle efficiency model are combined, and the input and output cycles are performed, and a plurality of basic ignition angle arrays, ignition angle offset value arrays and ignition angle efficiency curves corresponding to different speeds and loads are obtained.

[0063] Therefore, if a set of speed and load is input, the output data cannot be obtained, and a plurality of speeds and loads are required to be output, and a plurality of basic ignition angle arrays, ignition angle offset value arrays and ignition angle efficiency curves corresponding to the speeds and loads can be obtained after the model is processed.

[0064] Figure 5 is a target ignition angle efficiency curve diagram output by an engine torque model according to a specific embodiment of the application. The engine torque model is obtained by the method of the application. Figure 5 It can be seen that the ignition angle efficiency curve finally output by the engine torque model obtained by the method of the application is consistent with the actual situation.

[0065] Figure 6 is a deviation diagram of an engine torque model according to a specific embodiment of the application. In this embodiment, the whole process is optimized by means of the MBC toolbox of Matlab. As shown in Figure 6 The engine torque model of this embodiment meets the standard that the deviation is within ±5Nm when the torque is within 200Nm, and the deviation is within ±2.5% of the torque when the torque is above 200Nm, and the above standard can be guaranteed in the variable ignition angle range; at the same time, the optimal ignition angle output is reasonable, that is, the optimal ignition angle is greater than or equal to the basic ignition angle.

[0066] Specifically, as a specific embodiment of the application, the embodiment also provides an engine torque model, which can be obtained by the above method of constructing the engine torque model.

[0067] The engine torque model of the embodiment can include a spark angle efficiency model and an optimal spark angle model. The spark angle efficiency model and the optimal spark angle model are combined with the overall torque model of the current vehicle, and can output torque after input of engine speed and load. The torque data detected by each speed and load is input into the above model, and the engine torque model can be obtained according to the above method.

[0068] The spark angle efficiency model of the embodiment is obtained by inputting and outputting the initial spark angle efficiency model containing a plurality of unknown numbers to obtain the values of the unknown numbers, and then inputting the values into the initial spark angle efficiency model. The optimal spark angle model is obtained by inputting and outputting the initial optimal spark angle model and the initial spark angle efficiency model multiple times. The initial spark angle efficiency model is a mathematical function containing a plurality of unknown coefficients related to a sine function.

[0069] The mathematical function is y = asin(bx + c) + dsin(ex + f), x is the difference between the optimal spark angle and the actual spark angle, y is the spark angle efficiency, and a, b, c, d, e, and f are unknown parameters.

[0070] The initial spark angle efficiency model is obtained by solving the known input x = 0, output y = 1, and input x = 0, output y' = 0, and the initial spark angle efficiency model is y = (bcos(c)sin(ex + f) - ecos(f)sin(bx + c)) / (bcos(c)sin(f) - ecos(f)sin(c)).

[0071] The accuracy of the engine torque model obtained by the above method in the embodiment meets the deviation of ±5 Nm within 200 Nm, the deviation of ±torque multiplied by 2.5% within 200 Nm above, and the variable spark angle range can also guarantee the standard, while the optimal spark angle output is reasonable, i.e., the optimal spark angle is greater than or equal to the basic spark angle.

[0072] At this point, those skilled in the art should recognize that although the present application has been fully shown and described with reference to a plurality of exemplary embodiments, many other variations or modifications in accordance with the principles of the present application can be directly determined or deduced from the disclosure of the present application without departing from the spirit and scope of the present application. Therefore, the scope of the present application should be understood and recognized as covering all these other variations or modifications.

Claims

1. A method of constructing an engine torque model, characterized by, The engine torque model comprises a spark angle efficiency model for outputting a target spark angle efficiency curve, and a construction method of the spark angle efficiency model comprises the following steps: An initial spark angle efficiency model is built according to a preset spark angle efficiency curve, the initial spark angle efficiency model is a mathematical function related to a sine function and containing a plurality of unknown coefficients, and a mathematical relationship of the initial spark angle efficiency model is: y=asin(bx+c)+dsin(ex+f) wherein y is a spark angle efficiency, x is a difference between an optimal spark angle and an actual spark angle, a, b, c, d, e and f are the unknown coefficients, and the optimal spark angle is obtained by an optimal spark angle model, and a construction method of the optimal spark angle model comprises the following steps: An initial optimal spark angle model is built by taking a base spark angle and a spark angle offset value as the optimal spark angle, and the base spark angle is obtained according to a speed and a load; The speed and the load are input into the initial optimal spark angle model; The spark angle offset value in the initial optimal spark angle model is constrained to be positive; An input-output cycle of the entire engine torque model is performed when the initial optimal spark angle model and the initial spark angle efficiency model are combined, so as to obtain a target optimal spark angle model corresponding to a plurality of different speeds and loads; An actual spark angle and the base spark angle are input into the initial spark angle efficiency model to output a spark angle efficiency, and a plurality of input-output cycles are performed to obtain a plurality of arrays containing numerical values of all unknown coefficients; The plurality of arrays are substituted into the initial spark angle efficiency model to obtain a plurality of spark angle efficiency models corresponding to the plurality of arrays.

2. The construction method of the engine torque model according to claim 1, wherein a mathematical relationship of the initial spark angle efficiency model is obtained by solving y=asin(bx+c)+dsin(ex+f) with x=0 as input, y=1 as output, x=0 as input and y'=0 as output, and the mathematical relationship is: y=(bcos(c) sin(ex+f)-ecos(f) sin(bx+c)) / (bcos(c) sin(f)-ecos(f) sin(c)).

3. The construction method of the engine torque model according to claim 1, wherein the initial optimal spark angle model and the initial spark angle efficiency model are combined, and an input-output cycle is performed, and a plurality of values of the unknown coefficients are also obtained.

4. The construction method of the engine torque model according to claim 3, wherein after the plurality of values of the unknown coefficients are obtained, the method further comprises: a target spark angle efficiency model corresponding to the speed and the load is obtained by substituting any one of the values of the unknown coefficients into the initial spark angle efficiency model.

5. The method of claim 4, wherein, The target optimal ignition angle model is combined with the target ignition angle efficiency model, and an input-output cycle is performed, and a plurality of groups of corresponding basic ignition angle arrays, ignition angle offset value arrays and ignition angle efficiency curves under different rotating speeds and loads are also obtained.

6. An engine torque model characterized by, The engine torque model is obtained by the method of any one of claims 1-5. The engine torque model is obtained by the method of any one of claims 1-5.

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