Combustion control method and system for an engine

Abstract

The application provides a combustion control method and system of an engine, the method comprising: obtaining a combustion fluctuation error of a plurality of combustion cycles after starting of the engine, the combustion fluctuation error being an absolute value of a difference between an actual combustion fluctuation amount determined by an average indicated mean effective pressure of a plurality of reference combustion cycles corresponding to the combustion cycle and a preset standard combustion fluctuation amount; calculating an EGR valve opening degree according to the combustion fluctuation error, a preset proportional link adjustment gain and a preset integral link adjustment gain; and controlling an actual EGR valve opening degree of the engine to be equal to the EGR valve opening degree. Based on this, the application can calculate the corresponding EGR valve opening degree in real time according to the actual operation condition of the engine, so that the application can obtain the EGR valve opening degree under various operation conditions of the engine in actual operation, and the overall performance of the EGR technology applied to the engine is improved.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and specifically to a combustion control method and system for an engine. Background Technology

[0002] Exhaust Gas Recirculation (EGR) is a technology in internal combustion engines that separates a portion of the exhaust gases after combustion and introduces them into the intake side for re-combustion. The application of EGR technology improves engine combustion thermal efficiency to some extent, thus improving the fuel economy of gasoline engines. However, under constant conditions (such as engine speed, load, and ignition timing), a higher EGR gas flow rate leads to greater combustion fluctuations in the engine. This means that using EGR technology in gasoline engines can exacerbate combustion fluctuations, thereby increasing the likelihood of knocking.

[0003] To address this, existing technologies employ a calibration map-based control of the EGR gas flow rate input to the engine to reduce combustion fluctuations. The calibration map contains pre-calibrated reference values ​​for the EGR valve opening under specific operating conditions (e.g., a certain vehicle speed and load).

[0004] However, because related technologies cannot simulate various operating conditions of the engine in actual operation in advance, they cannot obtain the EGR valve opening under various operating conditions of the engine through calibration maps, resulting in poor performance of EGR technology applied to the engine. Therefore, how to obtain the EGR valve opening under various operating conditions of the engine in actual operation and improve the overall performance of EGR technology applied to the engine has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the problem that existing technologies struggle to obtain the EGR valve opening under various operating conditions of an engine in actual operation, thus hindering the improvement of the overall performance of EGR technology in engines, this invention provides an engine combustion control method and system.

[0006] The technical solution of this invention is as follows:

[0007] This invention provides a combustion control method for an engine, comprising:

[0008] The system acquires multiple combustion cycles after engine startup and combustion fluctuation data for each of these combustion cycles. The combustion fluctuation data includes combustion fluctuation error, which is the absolute value of the difference between the actual combustion fluctuation amount of the combustion cycle and a preset standard combustion fluctuation amount. The actual combustion fluctuation amount of the combustion cycle is determined based on the average indicated effective pressure of the reference combustion cycle corresponding to that combustion cycle. The reference combustion cycle includes a preset number of combustion cycles whose occurrence time is no later than the occurrence time of the combustion cycle and whose time difference with the combustion cycle is less than a preset duration.

[0009] The product of the combustion fluctuation error of the last combustion cycle in the plurality of combustion cycles and the preset proportional element adjustment gain is calculated to obtain the opening degree of the first EGR valve;

[0010] The sum of the combustion fluctuation errors of each of the multiple combustion cycles is multiplied by the preset integral element adjustment gain to obtain the opening degree of the second EGR valve.

[0011] The sum of the opening degree of the first EGR valve and the opening degree of the second EGR valve is calculated to obtain the opening degree of the EGR valve of the engine;

[0012] The actual EGR valve opening of the engine is controlled to be equal to the EGR valve opening.

[0013] This invention also provides a combustion control method for an engine, wherein the opening degree of the engine's EGR valve is adjusted according to a first preset frequency; the ignition advance angle of the engine is adjusted according to a second preset frequency; the first preset frequency is greater than the second preset frequency; the method includes:

[0014] For any adjustment cycle of the ignition advance angle of the engine, obtain the adjustment data of the EGR valve opening generated in the time period corresponding to the previous adjustment cycle of the any adjustment cycle; the EGR valve opening is determined according to the method described in any one of claims 1-5.

[0015] Based on the adjustment data, calculate the adjustment amount of the EGR valve opening;

[0016] Based on the adjustment amount and the ignition advance angle calculation value of the previous adjustment cycle, calculate the ignition advance angle calculation value for any adjustment cycle.

[0017] The ignition advance angle of any adjustment cycle is obtained by summing the calculated value of the ignition advance angle of any adjustment cycle with the preset feedforward value of any adjustment cycle.

[0018] Based on the ignition advance angle of any adjustment cycle, the ignition timing of each combustion cycle of the engine within the time period corresponding to any adjustment cycle is controlled.

[0019] This invention also provides a combustion control system for an engine, comprising:

[0020] cylinder;

[0021] A cylinder pressure signal processing device is used to calculate the average indicated effective pressure of the cylinder in each combustion cycle;

[0022] A combustion fluctuation calculation device is used to calculate the actual combustion fluctuation of any given combustion cycle based on the average indicated effective pressure of each reference combustion cycle corresponding to that combustion cycle.

[0023] The EGR control device is used to calculate the EGR valve opening of the engine based on the combustion fluctuation error of multiple combustion cycles after engine start-up, and to control the actual EGR valve opening of the engine to be equal to the EGR valve opening; the combustion fluctuation error is the absolute value of the difference between the actual combustion fluctuation amount of the combustion cycle and the preset standard combustion fluctuation amount.

[0024] An ignition advance angle control device is used to acquire adjustment data of the EGR valve opening in the previous adjustment cycle of any adjustment cycle of the engine's ignition advance angle; calculate the adjustment amount of the EGR valve opening based on the adjustment data; calculate the calculated value of the ignition advance angle for any adjustment cycle based on the adjustment amount and the calculated value of the ignition advance angle in the previous adjustment cycle; calculate the sum of the calculated value of the ignition advance angle for any adjustment cycle and the preset feedforward value for any adjustment cycle to obtain the ignition advance angle for any adjustment cycle; and control the ignition timing of each combustion cycle of the engine within the time period corresponding to any adjustment cycle based on the ignition advance angle for any adjustment cycle.

[0025] The embodiments of the present invention employ the above technical solution and have the following beneficial effects:

[0026] The EGR valve opening of the engine under the current operating condition is calculated based on the combustion fluctuation error of multiple combustion cycles after engine start-up. This allows the embodiment of the invention to calculate the corresponding EGR valve opening in real time according to the actual operating conditions of the engine, thereby enabling the embodiment to obtain the EGR valve opening under various operating conditions of the engine in actual operation. Furthermore, the accuracy of the calculated EGR valve opening result is ensured by using the combustion fluctuation error of multiple combustion cycles to calculate the actual combustion fluctuation of the combustion cycle. These multiple reference combustion cycles include a preset number of combustion cycles whose occurrence time is no later than the occurrence time of the current combustion cycle and whose time difference with the current combustion cycle is less than a preset duration. This makes the calculated actual combustion fluctuation of the combustion cycle more accurate, further ensuring the accuracy of the calculated EGR valve opening result. In short, the embodiments of the present invention can obtain the EGR valve opening degree of the engine under various operating conditions in actual operation, and ensure the accuracy of the calculation results of the EGR valve opening degree, which improves the overall performance of the EGR technology when applied to the engine. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of a combustion control method for an engine provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic flowchart of another combustion control method for an engine provided in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure of a combustion control system for an engine provided in an embodiment of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] Figure 1 This is a schematic flowchart of a combustion control method for an engine provided by an embodiment of the present invention. Figure 1 As shown, this process includes:

[0034] Step 101: Obtain multiple combustion cycles after engine start-up and combustion fluctuation data for each of the multiple combustion cycles. The combustion fluctuation data includes combustion fluctuation error, which is the absolute value of the difference between the actual combustion fluctuation amount of the combustion cycle and the preset standard combustion fluctuation amount. The actual combustion fluctuation amount of the combustion cycle is determined based on the average indicated effective pressure of the reference combustion cycle corresponding to the combustion cycle. The reference combustion cycle includes a preset number of combustion cycles whose occurrence time is no later than the occurrence time of the combustion cycle and whose time difference with the combustion cycle is less than a preset duration.

[0035] In this embodiment of the invention, after the engine is started, the pressure inside the engine cylinders is continuously monitored, and after each combustion cycle of the engine is completed, the average indicated effective pressure of that combustion cycle is calculated based on the detected cylinder pressure data corresponding to that combustion cycle. Thus, the average indicated effective pressure of each combustion cycle after engine start is obtained.

[0036] Furthermore, for each combustion cycle after the engine starts (including the combustion cycle corresponding to the preset number of cycles), after the end of each combustion cycle, a reference combustion cycle corresponding to that combustion cycle is determined, and the actual combustion fluctuation of that combustion cycle is calculated based on the average indicated effective pressure of the reference combustion cycle. Thus, the actual combustion fluctuation of each combustion cycle after the preset number of cycles after the engine starts is obtained.

[0037] Furthermore, after the engine starts, the EGR valve opening needs to be continuously adjusted based on the actual operating conditions of the engine during operation. The process described in this specification is the process of calculating the EGR valve opening for any given engine cycle. Specifically, multiple combustion cycles after engine start-up and the actual combustion fluctuations of each of these cycles are obtained. These actual combustion fluctuations reflect the engine's historical combustion fluctuations. Then, by calculating the absolute value of the difference between each actual combustion fluctuation and a preset standard combustion fluctuation, the combustion fluctuation error of each combustion cycle is obtained. This combustion fluctuation error is used to calculate the EGR valve opening under the current operating conditions.

[0038] It should be noted that, for each combustion cycle before the preset number after the engine starts, the actual combustion fluctuation of each combustion cycle can be calculated using existing technology, and the embodiments in this specification are not limited thereto.

[0039] Step 102: Calculate the product of the combustion fluctuation error of the last combustion cycle in the plurality of combustion cycles and the preset proportional element adjustment gain to obtain the opening degree of the first EGR valve.

[0040] Step 103: Multiply the sum of the combustion fluctuation errors of each combustion cycle in the plurality of combustion cycles by the preset integral element adjustment gain to obtain the opening degree of the second EGR valve.

[0041] Step 104: Calculate the sum of the opening degree of the first EGR valve and the opening degree of the second EGR valve to obtain the opening degree of the EGR valve of the engine.

[0042] In the embodiments of this specification, the formula for calculating the EGR valve opening is as follows:

[0043]

[0044] Among them, u EGR Kp is the EGR valve opening; e(T) is the preset proportional gain; Ki is the combustion fluctuation error of the last combustion cycle in the plurality of combustion cycles; e(t) is the preset integral gain; and e(t) is the combustion fluctuation error of the t-th combustion cycle in the plurality of combustion cycles.

[0045] To illustrate the above process more clearly, the following example is provided:

[0046] In a specific example, assume that the multiple combustion cycles obtained are C1, C2, and C3, and that C1, C2, and C3 occur sequentially, meaning that C3 is the last combustion cycle among the multiple combustion cycles. Then, obtain the combustion fluctuation errors of C1, C2, and C3 as e(1), e(2), and e(3), respectively. Finally, according to the above formula for calculating the EGR valve opening, u can be calculated. EGR =Kp*e(3)+Ki*(e(1)+e(2)+e(3)).

[0047] Step 105: Control the actual EGR valve opening of the engine to be equal to the EGR valve opening.

[0048] In the embodiments described in this specification, after calculating the EGR valve opening, the actual EGR valve opening of the engine is controlled to be equal to the EGR valve opening, until a new EGR valve opening is calculated again, and then the actual EGR valve opening of the engine is adjusted to the newly calculated EGR valve opening.

[0049] In the embodiments of this specification, the method may be executed at a time, and the specific execution frequency may be each combustion cycle or other execution frequencies. The embodiments of this specification do not make specific limitations here.

[0050] This embodiment of the specification employs the above-described technical solution, calculating the EGR valve opening of the engine under the current operating condition based on the combustion fluctuation errors of multiple combustion cycles after engine start-up. This allows the embodiment to calculate the corresponding EGR valve opening in real time based on the actual operating conditions of the engine, thereby enabling it to obtain the EGR valve opening under various operating conditions during actual engine operation. Furthermore, by using the combustion fluctuation errors of multiple combustion cycles to calculate the engine's EGR valve opening, the accuracy of the calculated EGR valve opening is ensured. Additionally, by using the average indicated effective pressure of multiple reference combustion cycles corresponding to the combustion cycle to calculate the actual combustion fluctuation amount of that combustion cycle, including a preset number of combustion cycles whose occurrence time is no later than the occurrence time of the current combustion cycle and whose time difference with the current combustion cycle is less than a preset duration, the calculated actual combustion fluctuation amount of the combustion cycle is more accurate, further ensuring the accuracy of the EGR valve opening calculation. In short, the embodiments of this specification can obtain the EGR valve opening degree of the engine under various operating conditions in actual operation, and ensure the accuracy of the calculation results of the EGR valve opening degree. This makes the embodiments of this specification improve the overall performance of EGR technology when applied to the engine.

[0051] Preferably, step 101: acquiring multiple combustion cycles after engine start-up and combustion fluctuation data for each of the multiple combustion cycles, specifically may include:

[0052] For any one of the plurality of combustion cycles, determine each reference combustion cycle corresponding to that combustion cycle.

[0053] Obtain the target average indicated effective pressure for each reference combustion cycle corresponding to any given combustion cycle.

[0054] Calculate the standard deviation and average value of the target average indicated effective pressure.

[0055] The actual combustion fluctuation of any combustion cycle is obtained by calculating the quotient of the standard deviation and the average value.

[0056] In the embodiments of this specification, any combustion cycle among the plurality of combustion cycles specifically refers to any combustion cycle among the combustion cycles after a predetermined number of times the engine is started (including the combustion cycle corresponding to the predetermined number of times). The occurrence time of each reference combustion cycle corresponding to any combustion cycle is close to the occurrence time of the arbitrary combustion cycle itself, and specifically, those skilled in the art can select each reference combustion cycle corresponding to the arbitrary combustion cycle according to actual needs. The actual combustion fluctuation of the arbitrary combustion cycle can be calculated using the following formula:

[0057]

[0058] Wherein, COV-IMEP represents the actual combustion fluctuation; σ IMEP The standard deviation of the target average indicated effective pressure for each reference combustion cycle corresponding to any given combustion cycle; μ IMEP The average of the target average indicated effective pressure for each reference combustion cycle corresponding to any given combustion cycle.

[0059] Preferably, obtaining the target average indicated effective pressure for each reference combustion cycle corresponding to any given combustion cycle may specifically include:

[0060] For any reference combustion cycle corresponding to any combustion cycle, the working volume of the engine cylinder, as well as the pressure data and volume change rate data of the cylinder in any reference combustion cycle, are obtained.

[0061] The average indicated effective pressure of any reference combustion cycle is calculated based on the working volume, the pressure data, and the volume change rate data.

[0062] In the embodiments of this specification, the formula for calculating the average indicated effective pressure is as follows:

[0063]

[0064] in,

[0065] Wherein, IMEP is the average indicated effective pressure; V d d is the working volume of the cylinder; P is the actual pressure of the cylinder at a certain moment; d V Let W be the rate of change of cylinder volume at a certain moment. i It represents the integral of the actual pressure and volume change rate of the cylinder during a combustion cycle.

[0066] Preferably, determining the reference combustion cycles corresponding to any given combustion cycle may specifically include:

[0067] In order of occurrence time from most recent to furthest, a predetermined number of combustion cycles are selected from each combustion cycle whose occurrence time is no later than that of any combustion cycle as reference combustion cycles corresponding to any combustion cycle.

[0068] To illustrate the above process more clearly, the following example is provided:

[0069] Assuming that after the engine starts, the combustion cycles that occur sequentially are C1, C2, C3, C4, C5, C6, C7, and C8, with a preset number of 6, then the reference combustion cycles corresponding to C6 are C1, C2, C3, C4, C5, and C6; the reference combustion cycles corresponding to C7 are C2, C3, C4, C5, C6, and C7; and the reference combustion cycles corresponding to C8 are C3, C4, C5, C6, C7, and C8. Therefore, those skilled in the art can easily determine that the method in the embodiments of this specification is not applicable to C1, C2, C3, C4, and C5.

[0070] Furthermore, in the embodiments of this specification, the reference combustion cycles corresponding to C7 can also be a set of combustion cycles consisting of C1, C3, C4, C5, C6 and C7, or a set of combustion cycles consisting of C2, C1, C4, C5, C6 and C7, etc. The same applies to the reference combustion cycles corresponding to C8. That is, those skilled in the art can fine-tune the reference combustion cycles corresponding to the combustion cycles based on the embodiments of this specification.

[0071] Preferably, step 101: acquiring multiple combustion cycles after engine start-up and combustion fluctuation data for each of the multiple combustion cycles, specifically may include:

[0072] Acquire the combustion cycles after engine startup, as well as the combustion fluctuation data of each combustion cycle.

[0073] Preferably, in the embodiments of this specification, acquiring multiple combustion cycles after engine start-up and combustion fluctuation data for each of the multiple combustion cycles may further include:

[0074] The method involves selecting multiple combustion cycles from those after engine startup by means of a preset number of combustion cycles at intervals, and acquiring combustion fluctuation data for each of these multiple combustion cycles. For example, assuming that the combustion cycles occurring sequentially after engine startup are C1, C2, C3, C4, C5, C6, C7, and C8, and the preset interval is set to 1, then the selected multiple combustion cycles include C1, C3, C5, and C7. This reduces the computational load in the embodiments of this specification and improves the computational efficiency of the EGR valve opening.

[0075] Example 2

[0076] Figure 2 This is a flowchart illustrating another combustion control method for an engine provided by an embodiment of the present invention. In this embodiment, the opening degree of the engine's EGR valve is adjusted according to a first preset frequency; the ignition advance angle of the engine is adjusted according to a second preset frequency; the first preset frequency is greater than the second preset frequency. Figure 2 As shown, this process includes:

[0077] Step 201: For any adjustment cycle of the ignition advance angle of the engine, obtain the adjustment data of the EGR valve opening generated in the time period corresponding to the previous adjustment cycle of the any adjustment cycle; the EGR valve opening is determined according to the method described in the aforementioned Embodiment 1.

[0078] In the embodiments described in this specification, the adjustment of the engine's EGR valve opening and the adjustment of the ignition advance angle are performed in a coordinated manner. However, the adjustment frequency of the EGR valve opening is greater than the adjustment frequency of the ignition advance angle. Therefore, within the time period corresponding to one ignition advance angle adjustment cycle, multiple adjustments of the EGR valve opening will occur. The adjustment data generated by these multiple adjustments of the EGR valve opening is referred to as the adjustment data corresponding to one ignition advance angle adjustment cycle.

[0079] Step 202: Calculate the adjustment amount of the EGR valve opening based on the adjustment data.

[0080] In the embodiments of this specification, calculating the adjustment amount of the EGR valve opening based on the adjustment data may specifically include:

[0081] Obtain the opening degree of each EGR valve from the adjustment data;

[0082] According to the calculation rule of subtracting the EGR valve opening of the previous EGR valve opening from the EGR valve opening of the next EGR valve opening adjustment cycle for the EGR valve opening of each adjacent EGR valve opening adjustment cycle, the opening of each EGR valve is calculated to obtain the calculation results.

[0083] The calculation results are summed to obtain the adjustment amount of the EGR valve opening.

[0084] To illustrate the above process more clearly, the following example is provided:

[0085] In a specific example, assuming that the engine's EGR valve opening is adjusted five times within the time period corresponding to the first adjustment cycle of the ignition advance angle, with the five EGR valve openings being a, b, c, d, and e respectively, then for the second adjustment cycle of the ignition advance angle, the EGR valve openings corresponding to the previous adjustment cycle are a, b, c, d, and e respectively. The calculation process for the adjustment amount of the EGR valve opening corresponding to the previous adjustment cycle is as follows:

[0086] Adjustment amount = (ba) + (cb) + (dc) + (ed).

[0087] Step 203: Calculate the ignition advance angle for any adjustment cycle based on the adjustment amount and the ignition advance angle calculation value of the previous adjustment cycle.

[0088] In the embodiments described in this specification, the calculated ignition advance angle value for the first adjustment cycle can be obtained based on the calibration map of the prior art, and is not limited here. The calculated ignition advance angle value for each adjustment cycle after the second adjustment cycle needs to be calculated based on the adjustment amount of the EGR valve opening corresponding to the previous adjustment cycle and the calculated ignition advance angle value.

[0089] To illustrate the above process more clearly, the following example is provided:

[0090] In a specific example, the calculated ignition advance angle value fb1 for the first adjustment cycle of the ignition advance angle corresponds to the adjustment amount W1 of the EGR valve opening. Then, based on fb1 and W1, the calculated ignition advance angle value fb2 for the second adjustment cycle of the ignition advance angle can be calculated. And, assuming that the adjustment amount W2 of the EGR valve opening corresponds to the second adjustment cycle of the ignition advance angle, then based on fb2 and W2, the calculated ignition advance angle value fb3 for the third adjustment cycle of the ignition advance angle can be calculated. And so on, the calculated ignition advance angle value for each adjustment cycle of the ignition advance angle can be calculated.

[0091] Step 204: Calculate the sum of the calculated ignition advance angle value for any adjustment cycle and the preset feedforward value for any adjustment cycle to obtain the ignition advance angle for any adjustment cycle.

[0092] In the embodiments described in this specification, the preset feedforward value is the minimum ignition advance angle at the peak torque corresponding to any operating condition of the engine under the equivalent air-fuel ratio without EGR gas introduction, which can be obtained from the pre-calibrated Map.

[0093] The formula for calculating the ignition advance angle in any adjustment cycle is as follows:

[0094]

[0095] Among them, u SA (j) represents the ignition advance angle for the j-th adjustment cycle; This is the preset feedforward value for the j-th adjustment period; This is the calculated value of the ignition advance angle for the j-th adjustment cycle.

[0096] Step 205: Based on the ignition advance angle of any adjustment cycle, control the ignition timing of each combustion cycle of the engine within the time period corresponding to any adjustment cycle.

[0097] In the embodiments described in this specification, the adjustment period of the ignition advance angle is longer than the period of the combustion cycle. Therefore, multiple combustion cycles will occur within the time period corresponding to one adjustment period of the ignition advance angle. After calculating the ignition advance angle of any adjustment period, the ignition advance angle of each combustion cycle corresponding to that adjustment period is controlled to be the calculated ignition advance angle of that adjustment period.

[0098] Preferably, the first preset frequency can be each combustion cycle.

[0099] In the embodiments of this specification, the adjustment frequency of the EGR valve opening can be every combustion cycle. Specifically, after the end of each combustion cycle, the EGR valve opening corresponding to the next combustion cycle is calculated, and based on the calculated EGR valve opening corresponding to the next combustion cycle, the actual EGR valve opening of the engine in the next combustion cycle is controlled to be the calculated EGR valve opening corresponding to the next combustion cycle.

[0100] Preferably, step 203: Based on the adjustment amount and the ignition advance angle calculation value of the previous adjustment cycle, calculate the ignition advance angle calculation value for any adjustment cycle, which may specifically include:

[0101] Calculate the value of the sigmoid function with the adjustment amount as the independent variable.

[0102] The product of the function value and the gain of the preset ignition advance angle control loop is summed with the calculated ignition advance angle value of the previous adjustment cycle to obtain the calculated ignition advance angle value for any adjustment cycle.

[0103] In the embodiments of this specification, the calculation formula for the ignition advance angle of any adjustment cycle is as follows:

[0104]

[0105] in, This is the (j+1)th adjustment period for the ignition advance angle; is the j-th adjustment cycle of the ignition advance angle; G is the gain of the control loop for the ignition advance angle; Wj is the adjustment amount of the EGR valve opening corresponding to the j-th adjustment cycle of the ignition advance angle.

[0106] Example 3

[0107] Figure 3 This is a schematic diagram of the structure of a combustion control system for an engine provided in an embodiment of the present invention. Figure 3 As shown, this system includes:

[0108] Cylinder 31.

[0109] Cylinder pressure signal processing device 32 is used to calculate the average indicated effective pressure (IMEP) of the cylinder in each combustion cycle.

[0110] Combustion fluctuation calculation device 33 is used to calculate the actual combustion fluctuation amount (COV_IMEP) of any combustion cycle based on the average indicated effective pressure of each reference combustion cycle corresponding to the any combustion cycle.

[0111] EGR control device 34 is used to calculate the EGR valve opening of the engine based on the combustion fluctuation error of multiple combustion cycles after engine start-up, and control the actual EGR valve opening of the engine to be equal to the EGR valve opening; the combustion fluctuation error is the absolute value of the difference between the actual combustion fluctuation amount of the combustion cycle and the preset standard combustion fluctuation amount.

[0112] The ignition advance angle control device 35 is used to acquire the adjustment data of the EGR valve opening in the previous adjustment cycle of any adjustment cycle of the engine's ignition advance angle; calculate the adjustment amount of the EGR valve opening based on the adjustment data; calculate the calculated value of the ignition advance angle for any adjustment cycle based on the adjustment amount and the calculated value of the ignition advance angle in the previous adjustment cycle; calculate the sum of the calculated value of the ignition advance angle for any adjustment cycle and the preset feedforward value for any adjustment cycle to obtain the ignition advance angle for any adjustment cycle; and control the ignition time of each combustion cycle of the engine within the time period corresponding to any adjustment cycle based on the ignition advance angle for any adjustment cycle.

[0113] In this embodiment of the specification, the EGR control device 34 can be specifically used to: acquire multiple combustion cycles after engine start-up and the combustion fluctuation error of each combustion cycle in the multiple combustion cycles; calculate the product of the combustion fluctuation error of the last combustion cycle in the multiple combustion cycles and a preset proportional element adjustment gain to obtain a first EGR valve opening; multiply the sum of the combustion fluctuation errors of each combustion cycle in the multiple combustion cycles by a preset integral element adjustment gain to obtain a second EGR valve opening; calculate the sum of the first EGR valve opening and the second EGR valve opening to obtain the EGR valve opening of the engine; and control the actual EGR valve opening of the engine to be equal to the EGR valve opening.

[0114] In the embodiments of this specification, the cylinder pressure signal processing device 32 can be specifically used for:

[0115] For any reference combustion cycle corresponding to any combustion cycle, the working volume of the engine cylinder, as well as the pressure data and volume change rate data of the cylinder in any reference combustion cycle, are obtained.

[0116] The average indicated effective pressure of any reference combustion cycle is calculated based on the working volume, the pressure data, and the volume change rate data.

[0117] In the embodiments of this specification, the combustion fluctuation calculation device 33 can be specifically used for:

[0118] For any one of the plurality of combustion cycles, determine each reference combustion cycle corresponding to that combustion cycle.

[0119] Obtain the target average indicated effective pressure for each reference combustion cycle corresponding to any given combustion cycle.

[0120] Calculate the standard deviation and average value of the target average indicated effective pressure.

[0121] The actual combustion fluctuation of any combustion cycle is obtained by calculating the quotient of the standard deviation and the average value.

[0122] In the embodiments of this specification, the EGR control device 34 can be specifically used for:

[0123] In order of occurrence time from most recent to furthest, a predetermined number of combustion cycles are selected from each combustion cycle whose occurrence time is no later than that of any combustion cycle as reference combustion cycles corresponding to any combustion cycle.

[0124] In the embodiments described in this specification, the EGR control device 34 can also be used for:

[0125] Acquire the combustion cycles after engine startup, as well as the combustion fluctuation data of each combustion cycle.

[0126] In this embodiment of the specification, the opening degree of the engine's EGR valve is adjusted according to a first preset frequency; the ignition advance angle of the engine is adjusted according to a second preset frequency; the first preset frequency is greater than the second preset frequency; wherein, the first preset frequency can specifically be each combustion cycle.

[0127] In the embodiments of this specification, the ignition advance angle control device 35 can be specifically used for:

[0128] Obtain the opening degree of each EGR valve from the adjustment data;

[0129] According to the calculation rule of subtracting the EGR valve opening of the previous EGR valve opening from the EGR valve opening of the next EGR valve opening adjustment cycle for the EGR valve opening of each adjacent EGR valve opening adjustment cycle, the opening of each EGR valve is calculated to obtain the calculation results.

[0130] The calculation results are summed to obtain the adjustment amount of the EGR valve opening.

[0131] In the embodiments described in this specification, the ignition advance angle control device 35 can also be used for:

[0132] Calculate the value of the sigmoid function with the adjustment amount as the independent variable.

[0133] The product of the function value and the gain of the preset ignition advance angle control loop is summed with the calculated ignition advance angle value of the previous adjustment cycle to obtain the calculated ignition advance angle value for any adjustment cycle.

[0134] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0135] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For apparatus embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0136] The steps in the methods of the various embodiments of the present invention can be adjusted, merged, or deleted in order according to actual needs, and the technical features described in the various embodiments can be replaced or combined.

[0137] The modules and sub-modules in the various embodiments of the present invention can be merged, divided, and deleted according to actual needs.

[0138] In the embodiments provided by this invention, it should be understood that the disclosed terminals, devices, and methods can be implemented in other ways. For example, the terminal embodiments described above are merely illustrative. For instance, the division of modules or sub-modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple sub-modules or modules may be combined or integrated into another module, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or modules, and may be electrical, mechanical, or other forms.

[0139] The modules or submodules described as separate components may or may not be physically separate. The components that constitute a module or submodule may or may not be physical modules or submodules; that is, they may be located in one place or distributed across multiple network modules or submodules. Some or all of the modules or submodules can be selected to achieve the purpose of this embodiment's solution, depending on actual needs.

[0140] Furthermore, the functional modules or sub-modules in the various embodiments of the present invention can be integrated into one processing module, or each module or sub-module can exist physically separately, or two or more modules or sub-modules can be integrated into one module. The integrated modules or sub-modules described above can be implemented in hardware or in the form of software functional modules or sub-modules.

[0141] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0142] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software unit executed by a processor, or a combination of both. The software unit can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0143] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0144] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A combustion control method for an engine, characterized in that, include: The system acquires multiple combustion cycles after engine startup and combustion fluctuation data for each of these combustion cycles. The combustion fluctuation data includes combustion fluctuation error, which is the absolute value of the difference between the actual combustion fluctuation amount of the combustion cycle and a preset standard combustion fluctuation amount. The actual combustion fluctuation amount of the combustion cycle is determined based on the average indicated effective pressure of the reference combustion cycle corresponding to that combustion cycle. The reference combustion cycle includes a preset number of combustion cycles whose occurrence time is no later than the occurrence time of the combustion cycle and whose time difference with the combustion cycle is less than a preset duration. The product of the combustion fluctuation error of the last combustion cycle in the plurality of combustion cycles and the preset proportional element adjustment gain is calculated to obtain the opening degree of the first EGR valve; The sum of the combustion fluctuation errors of each of the multiple combustion cycles is multiplied by the preset integral element adjustment gain to obtain the opening degree of the second EGR valve. The sum of the opening degree of the first EGR valve and the opening degree of the second EGR valve is calculated to obtain the opening degree of the EGR valve of the engine; The actual EGR valve opening of the engine is controlled to be equal to the EGR valve opening.

2. The method according to claim 1, characterized in that, The acquisition of multiple combustion cycles after engine start-up and combustion fluctuation data for each of the multiple combustion cycles specifically includes: For any one of the plurality of combustion cycles, determine each reference combustion cycle corresponding to that combustion cycle; Obtain the target average indicated effective pressure for each reference combustion cycle corresponding to any given combustion cycle; Calculate the standard deviation and average value of the target average indicated effective pressure; The actual combustion fluctuation of any combustion cycle is obtained by calculating the quotient of the standard deviation and the average value.

3. The method according to claim 2, characterized in that, The acquisition of the target average indicated effective pressure for each reference combustion cycle corresponding to any given combustion cycle specifically includes: For any reference combustion cycle in each reference combustion cycle corresponding to any combustion cycle, obtain the working volume of the engine cylinder, as well as the pressure data and volume change rate data of the cylinder in any reference combustion cycle; The average indicated effective pressure of any reference combustion cycle is calculated based on the working volume, the pressure data, and the volume change rate data.

4. The method according to claim 2, characterized in that, The determination of each reference combustion cycle corresponding to any given combustion cycle specifically includes: According to the order of occurrence time from most recent to oldest, a preset number of combustion cycles are selected from each combustion cycle whose occurrence time is no later than the occurrence time of any combustion cycle as reference combustion cycles corresponding to any combustion cycle.

5. The method according to claim 1, characterized in that, The acquisition of multiple combustion cycles after engine start-up and combustion fluctuation data for each of the multiple combustion cycles specifically includes: Acquire the combustion cycles after engine startup, as well as the combustion fluctuation data of each combustion cycle.

6. A combustion control method for an engine, characterized in that, The opening degree of the engine's EGR valve is adjusted according to a first preset frequency; the ignition advance angle of the engine is adjusted according to a second preset frequency. The first preset frequency is greater than the second preset frequency; the method includes: For any adjustment cycle of the ignition advance angle of the engine, obtain the adjustment data of the EGR valve opening generated in the time period corresponding to the previous adjustment cycle of the any adjustment cycle; the EGR valve opening is determined according to the method described in any one of claims 1-5. Based on the adjustment data, calculate the adjustment amount of the EGR valve opening; Based on the adjustment amount and the ignition advance angle calculation value of the previous adjustment cycle, calculate the ignition advance angle calculation value for any adjustment cycle. The ignition advance angle of any adjustment cycle is obtained by summing the calculated value of the ignition advance angle of any adjustment cycle with the preset feedforward value of any adjustment cycle. Based on the ignition advance angle of any adjustment cycle, the ignition timing of each combustion cycle of the engine within the time period corresponding to any adjustment cycle is controlled.

7. The method according to claim 6, characterized in that, The first preset frequency is specifically for each combustion cycle.

8. The method according to claim 6, characterized in that, The step of calculating the adjustment amount of the EGR valve opening based on the adjustment data specifically includes: Obtain the opening degree of each EGR valve from the adjustment data; According to the calculation rule of subtracting the EGR valve opening of the previous EGR valve opening from the EGR valve opening of the next EGR valve opening adjustment cycle for the EGR valve opening of each adjacent EGR valve opening adjustment cycle, the opening of each EGR valve is calculated to obtain the calculation results. The calculation results are summed to obtain the adjustment amount of the EGR valve opening.

9. The method according to claim 6, characterized in that, The step of calculating the ignition advance angle value for any adjustment cycle based on the adjustment amount and the ignition advance angle calculation value of the previous adjustment cycle specifically includes: Calculate the value of the sigmoid function with the adjustment amount as the independent variable; The product of the function value and the gain of the preset ignition advance angle control loop is summed with the calculated ignition advance angle value of the previous adjustment cycle to obtain the calculated ignition advance angle value for any adjustment cycle.

10. A combustion control system for an engine, characterized in that, include: cylinder; A cylinder pressure signal processing device is used to calculate the average indicated effective pressure of the cylinder in each combustion cycle; A combustion fluctuation calculation device is used to calculate the actual combustion fluctuation of any given combustion cycle based on the average indicated effective pressure of each reference combustion cycle corresponding to that combustion cycle. The EGR control device is used to calculate the EGR valve opening of the engine based on the combustion fluctuation error of multiple combustion cycles after engine start-up, and to control the actual EGR valve opening of the engine to be equal to the EGR valve opening; the combustion fluctuation error is the absolute value of the difference between the actual combustion fluctuation amount of the combustion cycle and the preset standard combustion fluctuation amount. An ignition advance angle control device is used to acquire adjustment data of the EGR valve opening in the previous adjustment cycle of any adjustment cycle of the engine's ignition advance angle, calculate the adjustment amount of the EGR valve opening based on the adjustment data, and calculate the ignition advance angle calculation value for any adjustment cycle based on the adjustment amount and the ignition advance angle calculation value of the previous adjustment cycle. The ignition advance angle of any adjustment cycle is calculated by summing the calculated value of the ignition advance angle of any adjustment cycle with the preset feedforward value of any adjustment cycle to obtain the ignition advance angle of any adjustment cycle; based on the ignition advance angle of any adjustment cycle, the ignition time of each combustion cycle of the engine within the time period corresponding to any adjustment cycle is controlled.

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