Engine torque calculation method and device, electronic equipment, storage medium and vehicle

Abstract

The invention discloses an engine torque calculation method and device, electronic equipment, a storage medium and a vehicle. The engine torque calculation method comprises the following steps: acquiring an engine crankshaft angle; according to the deviation degree of the thermodynamic process when the thermodynamic process in the cylinder is converted from the adiabatic process to the constant temperature process, the cylinder pressure at the moment corresponding to the engine crank angle is corrected, and a first cylinder pressure correction value is obtained; and the engine torque corresponding to the engine crank angle is obtained through calculation based on the first in-cylinder pressure correction value. According to the method, the change of compression and expansion of the engine is reflected based on conversion of the adiabatic process and the constant temperature process, so that the problem of asymmetry of internal pressure of the engine is considered in calculation of the engine torque, the engine torque is accurately predicted, and shutdown continuity control is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle-related technologies, and in particular to an engine torque calculation method, device, electronic equipment, storage medium and vehicle. Background Art

[0002] Precise control of the vehicle engine requires determining the engine torque based on the engine crankshaft angle. For this purpose, the prior art has established an engine torque model to determine the torque corresponding to different engine crankshaft angles during the stroke.

[0003] However, the existing model only considers the pressure change caused by volume change. The maximum and minimum values ​​of the piston's volume remain unchanged when it moves up and down, so the pressure obtained is symmetrical. However, the actual situation is that both the compression process and the expansion process will exchange heat, so the pressure is not symmetrical. Therefore, the existing torque model does not take into account the impact of the engine compression and expansion process on the internal pressure, making the torque calculated during the model control process inaccurate, which is not conducive to the precise control of the engine torque shutdown. Summary of the invention

[0004] Based on this, it is necessary to provide an engine torque calculation method, device, electronic device, storage medium and vehicle to address the technical problem that the torque model of the prior art calculates inaccurate torque during the model control process.

[0005] The present invention provides an engine torque calculation method, comprising:

[0006] Get the engine crankshaft angle;

[0007] According to the degree of deviation of the thermodynamic process when the in-cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, the in-cylinder pressure at the time corresponding to the engine crankshaft angle is corrected to obtain a first in-cylinder pressure correction value;

[0008] The engine torque corresponding to the engine crankshaft angle is calculated based on the first cylinder pressure correction value.

[0009] Further, the in-cylinder pressure at the time corresponding to the engine crankshaft angle is corrected according to the degree of deviation of the thermodynamic process when the in-cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process to obtain a first in-cylinder pressure correction value, specifically including:

[0010] Calculating the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle, wherein the degree of thermodynamic process deviation is the degree of deviation from the adiabatic process to the constant temperature process;

[0011] According to the degree of deviation of the thermodynamic process, the cylinder pressure at the time corresponding to the engine crankshaft angle is corrected to obtain a first cylinder pressure correction value.

[0012] Furthermore, the calculation of the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle specifically includes:

[0013] Calculate the total heat transfer in the cylinder at the corresponding moment of the engine crankshaft angle and the maximum heat of the adiabatic process in the cylinder;

[0014] The degree of thermodynamic process deviation is calculated as Among them, x is the degree of thermodynamic process deviation, Q sum is the total heat exchange in the cylinder, Q isoT is the maximum heat of the adiabatic process in the cylinder.

[0015] Furthermore, the in-cylinder pressure at a time corresponding to the engine crankshaft angle is corrected according to the degree of deviation of the thermodynamic process to obtain a first in-cylinder pressure correction value, which specifically includes:

[0016] Calculate the correction value of the pressure in the first cylinder as follows: Where P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, V d is the volume from top dead center to piston, V c is the clearance volume, γ is the adiabatic index, x is the degree of deviation of the thermodynamic process from adiabatic to isothermal, k1 is the first pressure weight, k2 is the second pressure weight, and the first pressure weight and the second pressure weight are obtained by fitting the reverse dragging experimental data according to the reverse dragging experimental data of the engine.

[0017] Further, the calculating the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value specifically includes:

[0018] Calculating a stroke correction coefficient and a throttle opening correction coefficient; the stroke correction coefficient represents the influence of the stroke on the cylinder pressure; the throttle opening correction coefficient represents the influence of the throttle opening on the cylinder pressure;

[0019] Calculating a second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value;

[0020] The engine torque is calculated based on the second cylinder pressure correction value and the engine crank angle.

[0021] Furthermore, the calculation of the stroke correction coefficient specifically includes:

[0022] Calculate the stroke correction factor as Among them, coe s is the stroke correction coefficient, C is the adjustment coefficient, and θ is the engine crankshaft angle.

[0023] Furthermore, the calculation of the throttle opening correction coefficient specifically includes:

[0024] Calculate the throttle opening correction coefficient as coe K =C1+C2log2(C3K+C4), where coe K is the throttle opening correction coefficient, C1 is the first throttle weight, C2 is the second throttle weight, C3 is the third throttle weight, C4 is the fourth throttle weight, K is the throttle opening, the first throttle weight, the second throttle weight, the third throttle weight and the fourth throttle weight are obtained by fitting the reverse drag test data of the engine reverse drag test data.

[0025] Furthermore, the calculating the second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value specifically includes:

[0026] The calculated pressure correction value in the second cylinder is: P M,corred =[(P M1 -P0)·coe s +P0]·coe K , where P M,corred is the pressure correction value in the second cylinder, P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, coe s is the stroke correction factor, coe K is the throttle opening correction coefficient.

[0027] Furthermore, the calculating the engine torque corresponding to the engine crankshaft angle according to the second cylinder pressure correction value specifically includes:

[0028] Calculate the engine torque as Among them, Trq p is the engine torque, r is the crankshaft radius, A is the piston area, P M,corred is the second cylinder pressure correction value, P0 is the initial cylinder pressure, θ is the engine crankshaft angle, and L is the connecting rod length.

[0029] The present invention provides an engine torque calculation device, comprising:

[0030] A crankshaft angle acquisition module, used for acquiring the engine crankshaft angle;

[0031] The cylinder pressure correction module is used to correct the cylinder pressure at the time corresponding to the engine crankshaft angle according to the degree of deviation of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, so as to obtain a first cylinder pressure correction value;

[0032] The torque calculation module is used to calculate the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value.

[0033] The present invention provides an electronic device, comprising:

[0034] at least one processor; and,

[0035] a memory communicatively connected to at least one of the processors; wherein,

[0036] The memory stores instructions that can be executed by at least one of the processors. The instructions are executed by at least one of the processors to enable the at least one of the processors to perform the engine torque calculation method as described above.

[0037] The present invention provides a storage medium, wherein the storage medium stores computer instructions. When a computer executes the computer instructions, the storage medium is used to execute all steps of the engine torque calculation method as described above.

[0038] The present invention provides a vehicle, comprising the engine torque calculation device as described above, or the electronic device as described above.

[0039] The present invention corrects the cylinder pressure at the time corresponding to the engine crankshaft angle according to the offset degree of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, obtains a first cylinder pressure correction value, calculates the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value, and corrects the calculation of the engine torque by using the first cylinder pressure correction value calculated based on the conversion between the adiabatic process and the constant temperature process, thereby adding the conversion between the adiabatic process and the constant temperature process to the calculation of the engine torque. The present invention reflects the changes in engine compression and expansion based on the conversion between the adiabatic process and the constant temperature process, so in the calculation of the engine torque, the asymmetric problem of the internal pressure of the engine is taken into account, thereby accurately predicting the engine torque and facilitating shutdown continuity control. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a working flow chart of a method for calculating engine torque according to an embodiment of the present invention;

[0041] Figure 2 This is a working flow chart of an engine torque calculation method according to another embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of throttle opening correction coefficient fitting in one example of the present invention;

[0043] Figure 4 This is a schematic diagram of a curve showing the relationship between the crankshaft angle and the engine torque according to an example of the present invention;

[0044] Figure 5 A schematic diagram of an engine torque calculation device according to an embodiment of the present invention;

[0045] Figure 6 The figure is a schematic diagram of the hardware structure of an electronic device of the present invention. DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. The same components are represented by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0047] like Figure 1 The figure shows a working flow chart of an engine torque calculation method according to an embodiment of the present invention, comprising:

[0048] Step S101, obtaining the engine crankshaft angle;

[0049] Step S102, correcting the cylinder pressure at the time corresponding to the engine crankshaft angle according to the degree of deviation of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, to obtain a first cylinder pressure correction value;

[0050] Step S103: Calculate the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value.

[0051] Specifically, the present invention can be applied to electronic devices with processing capabilities, such as an electronic control unit (ECU) or an extended domain control unit (XCU) of a vehicle.

[0052] The electronic device executes step S101 to obtain the engine crankshaft angle.

[0053] Specifically, the engine crankshaft angles at different times in the entire stroke cycle of the engine can be used as the engine crankshaft angles, thereby obtaining all engine crankshaft angles in the entire stroke cycle of the engine.

[0054] Then, step S102 is executed to correct the cylinder pressure at the time corresponding to the engine crankshaft angle according to the degree of deviation of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, so as to obtain a first cylinder pressure correction value.

[0055] Among them, the heat exchange process during the reverse drag of the engine can be considered as an adiabatic process, so as to calculate the in-cylinder temperature and the overall heat exchange in the cylinder (the combustion process can be fitted with the Weber function). During the compression and expansion process of the engine, the working fluid in the cylinder continuously exchanges heat with the environment. From the perspective of the polynomial index, heat exchange makes the thermodynamic process evolve from an adiabatic process to a constant temperature process. Therefore, the in-cylinder pressure at the corresponding moment of the engine crankshaft angle can be corrected according to the degree of deviation of the thermodynamic process when the in-cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, and the first in-cylinder pressure correction value is obtained.

[0056] Thereafter, step S103 is executed to calculate the engine torque corresponding to the engine crankshaft angle based on the first in-cylinder pressure correction value, and the first in-cylinder pressure correction value is introduced into the calculation of the engine crankshaft angle and the engine torque, so that the calculation of the engine torque includes the conversion between the adiabatic process and the constant temperature process.

[0057] Steps S101 to S103 can be performed based on all engine crankshaft angles in the entire engine stroke cycle to obtain all engine torques in the entire engine stroke cycle. The obtained engine torque can be used for accurate control of engine torque shutdown.

[0058] The present invention corrects the cylinder pressure at the time corresponding to the engine crankshaft angle according to the offset degree of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, obtains a first cylinder pressure correction value, calculates the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value, and corrects the calculation of the engine torque by using the first cylinder pressure correction value calculated based on the conversion between the adiabatic process and the constant temperature process, thereby adding the conversion between the adiabatic process and the constant temperature process to the calculation of the engine torque. The present invention reflects the changes in engine compression and expansion based on the conversion between the adiabatic process and the constant temperature process, so in the calculation of the engine torque, the asymmetric problem of the internal pressure of the engine is taken into account, thereby accurately predicting the engine torque and facilitating shutdown continuity control.

[0059] like Figure 2 The flowchart of a method for calculating engine torque in another embodiment of the present invention is shown, comprising:

[0060] Step S201, obtaining the engine crankshaft angle.

[0061] Step S202, calculating the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle, wherein the degree of thermodynamic process deviation is the degree of deviation from the adiabatic process to the constant temperature process.

[0062] In one embodiment, the calculating of the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle specifically includes:

[0063] Calculate the total heat transfer in the cylinder at the corresponding moment of the engine crankshaft angle and the maximum heat of the adiabatic process in the cylinder;

[0064] The degree of thermodynamic process deviation is calculated as Among them, x is the degree of thermodynamic process deviation, Q sum is the total heat exchange in the cylinder, Q isoT is the maximum heat of the adiabatic process in the cylinder.

[0065] Step S203: Correcting the cylinder pressure at the time corresponding to the engine crankshaft angle according to the degree of the thermodynamic process deviation to obtain a first cylinder pressure correction value.

[0066] In one embodiment, the in-cylinder pressure at a time corresponding to the engine crankshaft angle is corrected according to the degree of deviation of the thermodynamic process to obtain a first in-cylinder pressure correction value, specifically including:

[0067] Calculate the correction value of the pressure in the first cylinder as follows: Where P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, V d is the volume from top dead center to piston, V c is the clearance volume, γ is the adiabatic index, x is the degree of thermodynamic process deviation, k1 is the first pressure weight, k2 is the second pressure weight, and the first pressure weight and the second pressure weight are obtained by fitting the reverse dragging experimental data based on the engine reverse dragging experimental data.

[0068] Step S204, calculating a stroke correction coefficient and a throttle opening correction coefficient; the stroke correction coefficient represents the influence of the stroke on the cylinder pressure; the throttle opening correction coefficient represents the influence of the throttle opening on the cylinder pressure.

[0069] In one embodiment, the calculation of the stroke correction coefficient specifically includes:

[0070] Calculate the stroke correction factor as Among them, coe s is the stroke correction coefficient, C is the adjustment coefficient, and θ is the engine crankshaft angle.

[0071] In one embodiment, the calculation of the throttle opening correction coefficient specifically includes:

[0072] Calculate the throttle opening correction coefficient as coe K =C1+C2log2(C3K+C4), where coe Kis the throttle opening correction coefficient, C1 is the first throttle weight, C2 is the second throttle weight, C3 is the third throttle weight, C4 is the fourth throttle weight, K is the throttle opening, the first throttle weight, the second throttle weight, the third throttle weight and the fourth throttle weight are obtained by fitting the reverse drag test data of the engine reverse drag test data.

[0073] Step S205 , calculating a second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value.

[0074] In one embodiment, calculating the second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value specifically includes:

[0075] The calculated pressure correction value in the second cylinder is: P M,corred =[(P M1 -P0)·coe s +P0]·coe K , where P M,corred is the pressure correction value in the second cylinder, P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, coe s is the stroke correction factor, coe K is the throttle opening correction coefficient.

[0076] Step S206: Calculate the engine torque corresponding to the engine crankshaft angle according to the second cylinder pressure correction value.

[0077] In one embodiment, calculating the engine torque corresponding to the engine crankshaft angle according to the second cylinder pressure correction value specifically includes:

[0078] Calculate the engine torque as Among them, Trq p is the engine torque, r is the crankshaft radius, A is the piston area, P M,corred is the second cylinder pressure correction value, P0 is the initial cylinder pressure, θ is the engine crankshaft angle, and L is the connecting rod length.

[0079] Specifically, step S201 is first executed to obtain the engine crankshaft angle.

[0080] Then, step S202 is executed to calculate the degree of deviation of the thermodynamic process at the corresponding moment of the engine crankshaft angle, where the degree of deviation of the thermodynamic process is the degree of deviation from the adiabatic process to the constant temperature process.

[0081] In one embodiment, the calculating of the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle specifically includes:

[0082] Calculate the total heat transfer in the cylinder at the corresponding moment of the engine crankshaft angle and the maximum heat of the adiabatic process in the cylinder;

[0083] The degree of thermodynamic process deviation is calculated as Among them, x is the degree of thermodynamic process deviation, Q sum is the total heat exchange in the cylinder, Q isoT is the maximum heat of the adiabatic process in the cylinder.

[0084] Specifically, the cylinder pressure is calculated according to the adiabatic compression expansion process.

[0085] The total volume in the cylinder varies according to the engine crankshaft angle. The total volume in the cylinder can be calculated based on the engine structural parameters:

[0086]

[0087] Where r is the crankshaft radius, L is the connecting rod length, B is the piston diameter, Vc is the clearance volume, and θ is the engine crankshaft angle.

[0088] The pressure in the cylinder is calculated based on the adiabatic process:

[0089]

[0090] Among them, P M is the cylinder pressure, P0 is the initial cylinder pressure, V d is the volume from top dead center to piston, V c is the clearance volume, and γ is the adiabatic index. d =VV c , V is the total volume in the cylinder.

[0091] Heat transfer factor calculation, assuming that the heat transfer process is adiabatic during the reverse drag process to calculate the cylinder temperature and the total heat transfer in the cylinder (the combustion process can be fitted by the Weibull function)

[0092]

[0093] Where Q is the heat transfer amount, T is the cylinder temperature, T0 is the initial temperature, which can be considered as the wall temperature, α is the air heat transfer coefficient, which can be replaced by an empirical average value, Area is the heat transfer area in the cylinder, which is the total area of ​​the cylinder wall, cylinder head, and piston during piston movement, where the cylinder wall will change as the piston moves, t is the time during the stroke, t θ＝-180CA is the time when the engine crankshaft angle is -180°CA, t θ is the time corresponding to the engine crankshaft angle.

[0094] Assuming that the reverse dragging process is an adiabatic process, T is

[0095]

[0096] Calculate the polytropic process coefficient. During the compression and expansion process of the engine, the working fluid in the cylinder continuously exchanges heat with the environment. From the perspective of the polytropic index, heat exchange makes the thermodynamic process evolve from an adiabatic process to a constant temperature process. Therefore, the polytropic process coefficient can be calculated as:

[0097] n=γ-f(x)(5)

[0098] Where n is the polytropic process coefficient, x is the degree of thermodynamic process deviation, which is used to indicate the degree of deviation of the thermodynamic process from adiabatic to isothermal (isothermal). When x = 0, it is an adiabatic process, and when x = 1, it is a isothermal process (isothermal process). x can be calculated by the following formula:

[0099]

[0100] Among them, Q sum is the total heat exchange in the cylinder, Q isoT It is the maximum heat of the adiabatic process in the cylinder.

[0101] Among them, the total heat exchange in the cylinder is Q sum is the actual total heat transfer in the cylinder, and the maximum heat of the adiabatic process in the cylinder is Q isoT The maximum heat generated in the cylinder during the adiabatic process. By calculating the total heat exchange in the cylinder Qsum and the maximum heat of the adiabatic process in the cylinder Q isoT The degree of thermodynamic process deviation is obtained. When x=1, all the heat in the cylinder is exchanged away by heat, so the temperature no longer changes and it is a constant temperature process. When x=0, there is no heat exchange in the cylinder and it is an adiabatic process. The actual heat exchange process in the cylinder is between adiabatic and constant temperature. Therefore, by calculating x, the degree of thermodynamic process deviation in the cylinder can be determined.

[0102] Specifically, according to the multi-variable process:

[0103] PV n =P0V0 n (6-1)

[0104] Among them, P0 is the initial cylinder pressure, V0 is the initial cylinder volume, P is the pressure at any time, and V is the volume at any time.

[0105] According to the gas state equation:

[0106]

[0107] in, is the air mass flow rate, R is the gas constant, and T is the cylinder temperature.

[0108] Therefore, the combination of formula (6-1) and formula (6-2) gives:

[0109]

[0110] When calculating Q sum When n=n1, the cylinder temperature T corresponding to n1 is calculated by formula (6-3). Substituting the obtained cylinder temperature T into formula (3), Q is obtained. sum When calculating Q isoT When n=n2, the cylinder temperature T corresponding to n2 is calculated by formula (6-3). Substituting the obtained cylinder temperature T into formula (3), Q is obtained. isoT Then the thermodynamic process deviation degree x is calculated according to formula (6).

[0111] In some embodiments, n1=1.25, n2=1.4.

[0112] This embodiment calculates the total heat exchange in the cylinder at the time corresponding to the engine crankshaft angle and the maximum heat of the adiabatic process in the cylinder to obtain the degree of deviation of the thermodynamic process, thereby accurately reflecting the degree of deviation from the adiabatic process to the constant temperature process.

[0113] Then, step S203 is executed to correct the cylinder pressure at the time corresponding to the engine crankshaft angle according to the degree of deviation of the thermodynamic process, so as to obtain a first cylinder pressure correction value.

[0114] In one embodiment, the in-cylinder pressure at a time corresponding to the engine crankshaft angle is corrected according to the degree of deviation of the thermodynamic process to obtain a first in-cylinder pressure correction value, specifically including:

[0115] Calculate the correction value of the pressure in the first cylinder as follows: Where P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, V d is the volume from top dead center to piston, V c is the clearance volume, γ is the adiabatic index, x is the degree of thermodynamic process deviation, k1 is the first pressure weight, k2 is the second pressure weight, and the first pressure weight and the second pressure weight are obtained by fitting the reverse drag test data according to the reverse drag test data of the engine. The reverse drag test is an experiment in which the engine is not sprayed with fuel and the engine is driven to rotate by the generator.

[0116] From adiabatic to constant temperature process, the polynomial index obeys the exponential function distribution, so multiple process coefficients can be expanded into polynomials to simplify the calculation. This embodiment is expanded with a second-order polynomial. The final polynomial process is determined by x, and the first correction function for calculating the first cylinder pressure is constructed as:

[0117]

[0118] Among them, P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, V d is the volume from top dead center to piston, V c is the clearance volume, γ is the adiabatic index, x is the degree of thermodynamic process deviation, k1 is the first pressure weight, and k2 is the second pressure weight. It should be noted that when x=0, n=γ, and when x=1, n=1.

[0119] The first pressure weight and the second pressure weight are obtained by fitting reverse dragging experimental data based on reverse dragging experimental data of the engine.

[0120] Specifically, according to the reverse dragging test data of the engine, the engine torque corresponding to the engine crankshaft angle calculated based on the first in-cylinder pressure correction value is fitted to obtain the fitting value of the first pressure weight and the fitting value of the second pressure weight, and the fitting value of the first pressure weight and the fitting value of the second pressure weight are substituted into the first correction function.

[0121] Specifically, when x=0 and n=γ, and when x=1 and n=1, the cylinder pressure values ​​corresponding to different x values ​​in the reverse dragging test data, the volume from the top dead center to the piston, and the initial cylinder pressure, clearance volume, and adiabatic index in the reverse dragging test data are substituted into formula (7), and the calculation result of formula (7) is substituted into the main function of the engine crankshaft angle and the engine torque, such as formula (11), and then the least squares method is used for fitting, and when the minimum torque error is obtained, the fitting values ​​of k1 and k2 are obtained.

[0122] Since the total heat exchange in the cylinder is Q sum It is determined based on the empirical polytropic index n1. Therefore, this embodiment uses the least squares method for fitting. When the minimum torque error is obtained, the fitting values ​​of k1 and k2 are obtained, so that the error between the empirical polytropic index n1 and the actual polytropic index n is compensated by k1 and k2 to ensure the accuracy of the overall model.

[0123] After obtaining the first in-cylinder pressure correction value, the engine torque corresponding to the engine crankshaft angle can be calculated directly based on the first in-cylinder pressure correction value according to the in-cylinder pressure and the forces acting on the connecting rod and the crankshaft.

[0124] In some embodiments, the calculating of the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value specifically includes:

[0125] Calculate the engine torque as Among them, Trq p is the engine torque, r is the crankshaft radius, A is the piston area, P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, θ is the engine crankshaft angle, and L is the connecting rod length.

[0126] On the other hand, the present embodiment further executes step S204 to step S205 to further correct the in-cylinder pressure based on the stroke correction coefficient and the throttle opening correction coefficient.

[0127] Specifically, step S204 is executed to calculate a stroke correction coefficient and a throttle opening correction coefficient; the stroke correction coefficient represents the influence of the stroke on the cylinder pressure; the throttle opening correction coefficient represents the influence of the throttle opening on the cylinder pressure.

[0128] In one embodiment, the calculation of the stroke correction coefficient specifically includes:

[0129] The stroke correction function is calculated as Among them, coe s is the stroke correction coefficient, C is the adjustment coefficient, and θ is the engine crankshaft angle.

[0130] Specifically, the stroke correction factor is as follows:

[0131]

[0132] Among them, the stroke cycle is 720°CA, and according to custom, from -180°CA to 540°CA, the stroke sequence is compression-expansion-intake-exhaust. The valve is open during the intake and exhaust strokes, and the pressure in the cylinder does not change much, which can be approximated to atmospheric pressure. In the coefficient calculation formula, C can adjust the steepness of the coefficient change. Preferably, C can be 10.

[0133] This embodiment performs stroke continuous correction on the cylinder pressure model and uses the sigmoid function to avoid the inability to obtain derivatives due to discontinuity caused by conditional judgment.

[0134] In one embodiment, the calculation of the throttle opening correction coefficient specifically includes:

[0135] Calculate the throttle opening correction coefficient as coe K =C1+C2log2(C3K+C4), where coe Kis the throttle opening correction coefficient, C1 is the first throttle weight, C2 is the second throttle weight, C3 is the third throttle weight, C4 is the fourth throttle weight, K is the throttle opening, the first throttle weight, the second throttle weight, the third throttle weight and the fourth throttle weight are obtained by fitting the reverse drag test data of the engine reverse drag test data.

[0136] Specifically, this embodiment fits the effect of throttle opening on cylinder pressure according to experimental parameters, takes the maximum pressure ratio as the fitting object, and as the throttle opening increases, the maximum compression pressure has a saturation trend, so the fitting is performed in the form of an ln function, and the fitting formula for constructing the throttle opening correction coefficient function is as follows:

[0137] coe K =C1+C2log2(C3K+C4) (9)

[0138] According to the reverse drag test data, the maximum in-cylinder pressure ratio corresponding to multiple throttle openings is calculated as the experimental value of the throttle opening correction coefficient, and the constant terms C1-C4 are optimized using the least square method according to the experimental values ​​of multiple throttle openings and the corresponding throttle opening correction coefficients. Among them, the maximum in-cylinder pressure ratio corresponding to the throttle opening is the ratio of the in-cylinder pressure corresponding to the throttle opening to the maximum in-cylinder pressure.

[0139] As an example, Figure 3 shown. Figure 3 The horizontal axis is the throttle opening, and the vertical axis is the maximum pressure ratio. It can be seen that the fitted intake coefficient curve 31 obtained by fitting is very close to the actual intake coefficient curve 32 actually measured.

[0140] This embodiment fits the effect of the throttle opening on the in-cylinder pressure according to the experimental parameters, thereby correcting the in-cylinder pressure based on the throttle opening.

[0141] Thereafter, step S205 is executed to calculate a second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value.

[0142] In one embodiment, calculating the second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value specifically includes:

[0143] The calculated pressure correction value in the second cylinder is: P M,corred =[(P M1 -P0)·coe s +P0]·coe K (10), where P M,corred is the pressure correction value in the second cylinder, PM1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, coe s is the stroke correction factor, coe K is the throttle opening correction coefficient.

[0144] In this embodiment, the stroke correction coefficient and the throttle opening correction coefficient are used to correct the cylinder pressure respectively. At the same time, the first cylinder pressure correction value P M1 Substitute it into the final second cylinder pressure correction value P M,corred .

[0145] This embodiment realizes the correction of the cylinder pressure through the stroke, throttle opening and variable process.

[0146] Then, step S206 is executed to calculate the engine torque corresponding to the engine crankshaft angle according to the second cylinder pressure correction value.

[0147] In one embodiment, calculating the engine torque corresponding to the engine crankshaft angle according to the second cylinder pressure correction value specifically includes:

[0148] Calculate the engine torque as Among them, Trq p is the engine torque, r is the crankshaft radius, A is the piston area, P M,corred is the second cylinder pressure correction value, P0 is the initial cylinder pressure, θ is the engine crankshaft angle, and L is the connecting rod length.

[0149] Specifically, based on the in-cylinder pressure and the force calculation on the connecting rod and crankshaft, the indicated torque generated by the in-cylinder pressure is

[0150]

[0151] This embodiment calculates the engine torque corresponding to the engine crankshaft angle based on the relevant structural parameters of the engine, and introduces a correction value of the in-cylinder pressure into the calculation.

[0152] Specifically, the engine crankshaft angle at different times in the entire stroke cycle of the engine can be used as the engine crankshaft angle, and the engine torque corresponding to the engine crankshaft angle can be calculated based on the first cylinder pressure correction value, thereby obtaining all engine torques in the entire stroke cycle of the engine. Specifically, the engine crankshaft angle is substituted into formula (1) to obtain the total volume in the cylinder, the offset degree corresponding to the engine crankshaft angle is substituted into formula (7) to obtain the first cylinder pressure correction value, the engine crankshaft angle is substituted into formula (8) to obtain the stroke correction coefficient, the throttle opening corresponding to the engine crankshaft angle is substituted into formula (9) to obtain the throttle opening correction coefficient, and the calculated first cylinder pressure correction value, stroke correction coefficient, and throttle opening correction coefficient are substituted into formula (10) to obtain the second cylinder pressure correction value. Finally, the calculated second cylinder pressure correction value and the engine crankshaft angle are substituted into formula (11) to obtain the engine torque corresponding to the engine crankshaft angle. As an example, the following is obtained: Figure 4 The relationship curve between the crankshaft angle and the engine torque is shown in FIG41. The obtained engine torque can be used for accurate control of the engine torque shutdown.

[0153] This embodiment uses reverse drag test data, based on the conversion between adiabatic process and constant temperature process, to reflect the changes in engine compression and expansion through a variable process, and corrects the cylinder pressure based on the stroke and throttle opening. The correction is performed in a semi-physical and semi-fitting manner, thereby accurately predicting the engine torque and facilitating shutdown continuity control.

[0154] Based on the same inventive concept, Figure 5 FIG. 1 is a schematic diagram of an engine torque calculation device according to an embodiment of the present invention, comprising:

[0155] A crankshaft angle acquisition module 501 is used to acquire the engine crankshaft angle;

[0156] The cylinder pressure correction module 502 is used to correct the cylinder pressure at the time corresponding to the engine crankshaft angle according to the degree of deviation of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, so as to obtain a first cylinder pressure correction value;

[0157] The torque calculation module 503 is used to calculate the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value.

[0158] The present invention corrects the cylinder pressure at the time corresponding to the engine crankshaft angle according to the offset degree of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, obtains a first cylinder pressure correction value, calculates the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value, and corrects the calculation of the engine torque by using the first cylinder pressure correction value calculated based on the conversion between the adiabatic process and the constant temperature process, thereby adding the conversion between the adiabatic process and the constant temperature process to the calculation of the engine torque. The present invention reflects the changes in engine compression and expansion based on the conversion between the adiabatic process and the constant temperature process, so in the calculation of the engine torque, the asymmetric problem of the internal pressure of the engine is taken into account, thereby accurately predicting the engine torque and facilitating shutdown continuity control.

[0159] In one embodiment, the in-cylinder pressure at a time corresponding to the engine crankshaft angle is corrected according to the degree of deviation of the thermodynamic process when the in-cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process to obtain a first in-cylinder pressure correction value, specifically including:

[0160] Calculating the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle, wherein the degree of thermodynamic process deviation is the degree of deviation from the adiabatic process to the constant temperature process;

[0161] According to the degree of deviation of the thermodynamic process, the cylinder pressure at the time corresponding to the engine crankshaft angle is corrected to obtain a first cylinder pressure correction value.

[0162] In one embodiment, the calculating of the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle specifically includes:

[0163] Calculate the total heat transfer in the cylinder at the corresponding moment of the engine crankshaft angle and the maximum heat of the adiabatic process in the cylinder;

[0164] The degree of thermodynamic process deviation is calculated as Among them, x is the degree of thermodynamic process deviation, Q sum is the total heat exchange in the cylinder, Q isoT is the maximum heat of the adiabatic process in the cylinder.

[0165] In one embodiment, the in-cylinder pressure at a time corresponding to the engine crankshaft angle is corrected according to the degree of deviation of the thermodynamic process to obtain a first in-cylinder pressure correction value, specifically including:

[0166] Calculate the correction value of the pressure in the first cylinder as follows: Where P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, V d is the volume from top dead center to piston, V cis the clearance volume, γ is the adiabatic index, x is the degree of deviation of the thermodynamic process from adiabatic to isothermal, k1 is the first pressure weight, k2 is the second pressure weight, and the first pressure weight and the second pressure weight are obtained by fitting the reverse dragging experimental data according to the reverse dragging experimental data of the engine.

[0167] In one embodiment, the calculating the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value specifically includes:

[0168] Calculating a stroke correction coefficient and a throttle opening correction coefficient; the stroke correction coefficient represents the influence of the stroke on the cylinder pressure; the throttle opening correction coefficient represents the influence of the throttle opening on the cylinder pressure;

[0169] Calculating a second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value;

[0170] The engine torque is calculated based on the second cylinder pressure correction value and the engine crank angle.

[0171] In one embodiment, the calculation of the stroke correction coefficient specifically includes:

[0172] The stroke correction function is calculated as Among them, coe s is the stroke correction coefficient, C is the adjustment coefficient, and θ is the engine crankshaft angle.

[0173] In one embodiment, the calculation of the throttle opening correction coefficient specifically includes:

[0174] Calculate the throttle opening correction coefficient as coe K =C1+C2log2(C3K+C4), where coe K is the throttle opening correction coefficient, C1 is the first throttle weight, C2 is the second throttle weight, C3 is the third throttle weight, C4 is the fourth throttle weight, K is the throttle opening, the first throttle weight, the second throttle weight, the third throttle weight and the fourth throttle weight are obtained by fitting the reverse drag test data of the engine reverse drag test data.

[0175] In one embodiment, calculating the second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value specifically includes:

[0176] The calculated pressure correction value in the second cylinder is: P M,corred =[(P M1 -P0)·coe s +P0]·coeK , where P M,corred is the pressure correction value in the second cylinder, P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, coe s is the stroke correction factor, coe K is the throttle opening correction coefficient.

[0177] In one embodiment, calculating the engine torque corresponding to the engine crankshaft angle according to the second cylinder pressure correction value specifically includes:

[0178] Calculate the engine torque as Among them, Trq p is the engine torque, r is the crankshaft radius, A is the piston area, P M,corred is the second cylinder pressure correction value, P0 is the initial cylinder pressure, θ is the engine crankshaft angle, and L is the connecting rod length.

[0179] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0180] like Figure 6 The figure shows a hardware structure diagram of an electronic device of the present invention, including:

[0181] at least one processor 601; and,

[0182] A memory 602 is communicatively connected to at least one of the processors 601; wherein,

[0183] The memory 602 stores instructions that can be executed by at least one of the processors. The instructions are executed by at least one of the processors to enable the at least one of the processors to perform the engine torque calculation method described above.

[0184] Figure 6 A processor 601 is taken as an example.

[0185] The electronic device may further include: an input device 603 and a display device 604 .

[0186] The processor 601, the memory 602, the input device 603 and the display device 604 may be connected via a bus or other means, and the figure takes the connection via a bus as an example.

[0187] The memory 602 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the engine torque calculation method in the embodiment of the present application, for example, Figure 1 , Figure 2 The processor 601 executes various functional applications and data processing by running the non-volatile software programs, instructions and modules stored in the memory 602, that is, the engine torque calculation method in the above embodiment is implemented.

[0188] The memory 602 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and applications required by at least one function; the data storage area may store data created according to the use of the engine torque calculation method, etc. In addition, the memory 602 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 602 may optionally include a memory remotely arranged relative to the processor 601, and these remote memories may be connected to the device for executing the engine torque calculation method via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0189] The input device 603 can receive user clicks and generate signal inputs related to user settings and function controls of the engine torque calculation method. The display device 604 can include display devices such as a display screen.

[0190] The one or more modules are stored in the memory 602 , and when run by the one or more processors 601 , the engine torque calculation method in any of the above method embodiments is executed.

[0191] The present invention corrects the cylinder pressure at the time corresponding to the engine crankshaft angle according to the offset degree of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, obtains a first cylinder pressure correction value, calculates the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value, and corrects the calculation of the engine torque by using the first cylinder pressure correction value calculated based on the conversion between the adiabatic process and the constant temperature process, thereby adding the conversion between the adiabatic process and the constant temperature process to the calculation of the engine torque. The present invention reflects the changes in engine compression and expansion based on the conversion between the adiabatic process and the constant temperature process, so in the calculation of the engine torque, the asymmetric problem of the internal pressure of the engine is taken into account, thereby accurately predicting the engine torque and facilitating shutdown continuity control.

[0192] An embodiment of the present invention provides a storage medium, wherein the storage medium stores computer instructions. When a computer executes the computer instructions, the storage medium is used to execute all steps of the engine torque calculation method as described above.

[0193] In the context of the present disclosure, a storage medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or apparatus. The storage medium may be a machine-readable signal medium or a machine-readable storage medium. Alternatively, the storage medium may be a non-temporary computer-readable storage medium, for example, a non-temporary computer-readable storage medium may be a ROM, a random access memory (Random Access Memory, RAM), a compact disc read-only memory (Compact Disc ROM, CD-ROM), a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0194] An embodiment of the present invention provides a vehicle, including the engine torque calculation device as described above, or the electronic device as described above. It is understandable that the vehicle may also include: a processor, a memory, and a computer program. The computer program is stored in the memory and is configured to be executed by the processor to implement the engine torque calculation method provided in the embodiment of the present disclosure. The processor and the memory are already in Figure 6 The parts described in the illustrated embodiment will not be repeated here.

[0195] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for calculating engine torque, characterized in that: include: Get the engine crankshaft angle; According to the degree of deviation of the thermodynamic process when the in-cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, the in-cylinder pressure at the time corresponding to the engine crankshaft angle is corrected to obtain a first in-cylinder pressure correction value; The engine torque corresponding to the engine crankshaft angle is calculated based on the first cylinder pressure correction value.

2. The engine torque calculation method according to claim 1, characterized in that: The method of correcting the cylinder pressure at a time corresponding to the engine crankshaft angle according to the degree of deviation of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process to obtain a first cylinder pressure correction value specifically includes: Calculating the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle, wherein the degree of thermodynamic process deviation is the degree of deviation from the adiabatic process to the constant temperature process; According to the degree of deviation of the thermodynamic process, the cylinder pressure at the time corresponding to the engine crankshaft angle is corrected to obtain a first cylinder pressure correction value.

3. The engine torque calculation method according to claim 2, characterized in that: The calculation of the degree of thermodynamic process deviation at the corresponding moment of the engine crankshaft angle specifically includes: Calculate the total heat transfer in the cylinder at the corresponding moment of the engine crankshaft angle and the maximum heat of the adiabatic process in the cylinder; The degree of thermodynamic process deviation is calculated as Among them, x is the degree of thermodynamic process deviation, Q sum is the total heat exchange in the cylinder, Q isoT is the maximum heat of the adiabatic process in the cylinder.

4. The engine torque calculation method according to claim 2, characterized in that: The step of correcting the cylinder pressure at a time corresponding to the engine crankshaft angle according to the offset degree of the thermodynamic process to obtain a first cylinder pressure correction value specifically includes: Calculate the correction value of the pressure in the first cylinder as: Where P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, V d is the volume from top dead center to piston, V c is the clearance volume, γ is the adiabatic index, x is the degree of thermodynamic process deviation, k1 is the first pressure weight, k2 is the second pressure weight, and the first pressure weight and the second pressure weight are obtained by fitting the reverse dragging experimental data based on the engine reverse dragging experimental data.

5. The engine torque calculation method according to claim 1, characterized in that: The calculating the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value specifically includes: Calculating a stroke correction coefficient and a throttle opening correction coefficient; the stroke correction coefficient represents the influence of the stroke on the cylinder pressure; the throttle opening correction coefficient represents the influence of the throttle opening on the cylinder pressure; Calculating a second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value; The engine torque corresponding to the engine crank angle is calculated according to the second cylinder pressure correction value.

6. The engine torque calculation method according to claim 5, characterized in that: The calculation of the stroke correction coefficient specifically includes: Calculate the stroke correction factor as Among them, coe s is the stroke correction coefficient, C is the adjustment coefficient, and θ is the engine crankshaft angle.

7. The engine torque calculation method according to claim 5, characterized in that: The calculation of the throttle opening correction coefficient specifically includes: Calculate the throttle opening correction coefficient as coe K =C1+C2log2(C3K+C4), where coe K is the throttle opening correction coefficient, C1 is the first throttle weight, C2 is the second throttle weight, C3 is the third throttle weight, C4 is the fourth throttle weight, K is the throttle opening, the first throttle weight, the second throttle weight, the third throttle weight and the fourth throttle weight are obtained by fitting the reverse drag test data of the engine reverse drag test data.

8. The engine torque calculation method according to claim 5, characterized in that: The calculating the second cylinder pressure correction value according to the stroke correction coefficient, the throttle opening correction coefficient and the first cylinder pressure correction value specifically includes: The calculated pressure correction value in the second cylinder is: P M,corred =[(P M1 -P0)·coe s +P0]·coe K , where P M,corred is the pressure correction value in the second cylinder, P M1 is the first cylinder pressure correction value, P0 is the initial cylinder pressure, coe s is the stroke correction factor, coe K is the throttle opening correction coefficient.

9. The engine torque calculation method according to claim 5, characterized in that: The calculating the engine torque corresponding to the engine crankshaft angle according to the second cylinder pressure correction value specifically includes: Calculate the engine torque as Among them, Trq p is the engine torque, r is the crankshaft radius, A is the piston area, P M,corred is the second cylinder pressure correction value, P0 is the initial cylinder pressure, θ is the engine crankshaft angle, and L is the connecting rod length.

10. An engine torque calculation device, characterized in that: include: A crankshaft angle acquisition module, used for acquiring the engine crankshaft angle; The cylinder pressure correction module is used to correct the cylinder pressure at the time corresponding to the engine crankshaft angle according to the degree of deviation of the thermodynamic process when the cylinder thermodynamic process is converted from an adiabatic process to a constant temperature process, so as to obtain a first cylinder pressure correction value; The torque calculation module is used to calculate the engine torque corresponding to the engine crankshaft angle based on the first cylinder pressure correction value.

11. An electronic device, characterized in that: include: at least one processor; as well as, a memory communicatively connected to at least one of the processors; wherein, The memory stores instructions that can be executed by at least one of the processors, and the instructions are executed by at least one of the processors to enable at least one of the processors to execute the engine torque calculation method according to any one of claims 1 to 9.

12. A storage medium, characterized in that: The storage medium stores computer instructions, and when a computer executes the computer instructions, it is used to execute all steps of the engine torque calculation method according to any one of claims 1 to 9.

13. A vehicle, characterized in that: It comprises the engine torque calculation device as claimed in claim 10, or the electronic device as claimed in claim 11.

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