An internal combustion engine combustion exhaust gas recirculation control system and control method

Abstract

The present invention discloses a combustion optimization control method for a methanol pure-oxygen combustion exhaust gas recirculation internal combustion engine. The method includes the following steps: collecting the operating parameters of the engine; calculating the current combustion efficiency and emission levels; determining the control error; calculating the adjustment amount by using a multivariable adaptive control algorithm and executing it; monitoring the performance of the engine after adjustment and performing cyclic optimization. This method uses high-precision sensors to monitor multiple parameters in real time, constructs a multivariable mathematical model through a PID control algorithm, and introduces adaptive control calculations. A comprehensive performance index function F is also defined, considering factors such as combustion efficiency, equivalence ratio, temperature, emissions, and fuel consumption, for optimizing the EGR rate. The present invention realizes the efficient, clean, and economical operation of a methanol pure-oxygen combustion internal combustion engine, improves the combustion efficiency, improves the emission control and fuel economy, and enhances the intelligence and self-adaptability of the control system.

Description

Technical Field

[0001] The present invention relates to engine power control technology, and in particular to a control system and a control method for realizing combustion exhaust gas recirculation of an internal combustion engine. Background Art

[0002] With the improvement of environmental protection awareness and the transformation of energy structure, methanol as a clean alternative fuel is receiving more and more attention. Methanol pure oxygen combustion internal combustion engine has become a research hotspot due to its high efficiency and low emission characteristics. However, traditional methanol pure oxygen combustion engine still faces some challenges in practical application, mainly including:

[0003] Unstable combustion efficiency, fuel economy needs to be improved, and control methods are complex: Since the physical and chemical properties of methanol are different from those of traditional fuels, it is difficult to maintain optimal combustion efficiency under different operating conditions. While ensuring performance, how to maximize fuel utilization remains an important issue. Traditional single-parameter control methods are difficult to cope with the multivariable and strongly coupled characteristics of methanol pure oxygen combustion, so the control methods are relatively backward, especially the control methods for combustion exhaust gas recirculation are even more backward. Summary of the invention

[0004] The object of the present invention is to provide a control system and a control method for realizing exhaust gas recirculation of an internal combustion engine, which solves the above-mentioned technical problems pointed out in the prior art.

[0005] The present invention provides a combustion optimization control system for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, comprising:

[0006] Multiple sensors are used to collect engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow, oxygen flow and exhaust gas composition; based on the engine operating parameters, calculate the current actual combustion efficiency, and then detect and obtain the actual nitrogen oxide emission concentration;

[0007] The central control unit is used to set the target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable; under the preset condition of limiting the methanol flow, use the multivariable adaptive control algorithm to calculate the adjustment amount of the methanol flow, oxygen flow and combustion chamber temperature; under the preset condition of not limiting the methanol flow, use the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node to calculate the adjustment amount of the valve opening; execute the adjustment amount and adjust the corresponding control device actuator; the control device actuator includes a switch valve and a pump, a flow valve and a combustion temperature controller;

[0008] The combustion optimization control system of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine further includes: a high-precision thermocouple, a piezoresistive pressure sensor, a Coriolis mass flowmeter, and an infrared spectrum analyzer;

[0009] The high-precision thermocouple is used to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber, and calculate the average temperature as the combustion chamber temperature;

[0010] The piezoresistive pressure sensor is used to measure the combustion chamber pressure and obtain the combustion chamber pressure;

[0011] The Coriolis mass flowmeter is used to measure the methanol flow rate and the oxygen flow rate respectively;

[0012] The infrared spectrum analyzer is used to analyze the exhaust gas components in real time.

[0013] Correspondingly, the present invention also provides a combustion optimization control method for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, which uses the combustion optimization control system of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine to implement control processing, including the following steps:

[0014] S1. Collect the engine operation parameters, including the combustion chamber temperature, the combustion chamber pressure, the methanol flow rate, the oxygen flow rate, and the exhaust gas components;

[0015] S2. Based on the engine operation parameters, calculate the current actual combustion efficiency, and then detect and obtain the actual nitrogen oxide emission concentration;

[0016] S3. According to the preset target combustion chamber temperature T target and the target nitrogen oxide emission concentration u o,target and the set target methanol flow rate u m,target , calculate the error of the control variable;

[0017] S4. Under the preset conditions of restricting the methanol flow rate, use the multivariable adaptive control algorithm to calculate the adjustment amounts of the methanol flow rate, the oxygen flow rate, and the combustion chamber temperature; under the preset conditions without restricting the methanol flow rate, use the optimal control parameters of the exhaust gas recirculation rate EGR for solving the next control time sequence node to calculate the adjustment amount of the valve opening; execute the adjustment amounts and adjust the corresponding control device actuators; the control device actuators include a switching valve, a pump, a flow valve, and a combustion temperature controller.

[0018] Preferably, as an implementable solution; the operation parameters collected in the step S1 further include:

[0019] S11. Use the high-precision thermocouple to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber, and calculate the average temperature as the combustion chamber temperature;

[0020] S12. Measure the combustion chamber pressure using a piezoresistive pressure sensor to obtain the combustion chamber pressure;

[0021] S13. Use a Coriolis mass flowmeter to measure the methanol flow rate and oxygen flow rate respectively;

[0022] S14. Analyze the exhaust gas composition in real time through an infrared spectroscopy analyzer to obtain the exhaust gas composition analysis result.

[0023] Preferably, as an implementable solution; the method for calculating the combustion efficiency in step S2 includes:

[0024] S21. Calculate the theoretical thermal efficiency based on the combustion chamber temperature and combustion chamber pressure;

[0025] S22. Use the implementation detection ratio of the methanol flow rate and oxygen flow rate to calculate the current actual air-fuel ratio; then calculate the corrected current air-fuel ratio based on the current actual air-fuel ratio, the preset ideal air-fuel ratio, and the adjustment parameter;

[0026] Corrected current air-fuel ratio

[0027] Where: AFR 实际 : The actual air-fuel ratio calculated in step S22;

[0028] AFR 理想 : Ideal air-fuel ratio;

[0029] σ: Represents an adjustment parameter;

[0030] S23. Calculate the proportion of unburned fuel according to the exhaust gas composition analysis result;

[0031] S24. Output and calculate the actual combustion efficiency by integrating the theoretical thermal efficiency, the corrected current air-fuel ratio, and the proportion of unburned fuel to obtain the actual combustion efficiency.

[0032] The calculation formula for the actual combustion efficiency is: η 实际( = η 理论( ·k 空燃比( ·1 - r 末完全燃烧 ;

[0033] η 实际 : The finally calculated actual combustion efficiency;

[0034] η 理论 : Theoretical thermal efficiency;

[0035] k 空燃比 : Corrected current air-fuel ratio k 空燃比 ;

[0036] r 末完全燃烧 : Represents the proportion of unburned fuel.

[0037] Preferably, as an implementable solution; in step S3, according to the preset target combustion chamber temperature T target and the target nitrogen oxide emission concentration u o,target and the set target methanol flow rate u m,target , calculate the error of the control variable; step S4 uses a multivariable adaptive control algorithm to calculate the adjustment amounts of the methanol flow rate, oxygen flow rate, and combustion chamber temperature, including the following steps:

[0038] S41. Implement the PID control algorithm for each control variable to construct a multivariable mathematical model. The control variables include the methanol flow rate u m , the oxygen flow rate u o , and the combustion chamber temperature u T ;

[0039] The calculation formula of the multivariable mathematical model is:

[0040]

[0041] where i ∈ m, o, T, representing the methanol flow rate, oxygen flow rate, and combustion chamber temperature respectively;

[0042] S42. Implement adaptive control calculation for the multivariable mathematical model:

[0043]

[0044]

[0045]

[0046] where K p，i (t + 1) is the value of the proportional gain of the i-th control variable (such as methanol flow rate, oxygen flow rate, or combustion chamber temperature) at time t + 1. It is used to control the system's response to the current error.

[0047] K i，i (t + 1) is the value of the integral gain of the i-th control variable at time t + 1. The integral gain is used to eliminate the steady-state error, that is, to adjust the output by accumulating past errors.

[0048] K d，i (t + 1) is the value of the derivative gain of the i-th control variable at time t + 1. The derivative gain is used to predict future error changes and help reduce the overshoot phenomenon of the system;

[0049] α p ,α i ,α d are their respective learning rates, and E is the preset threshold index for the comprehensive performance of fuel energy saving;

[0050] are respectively the partial derivatives of the performance index E with respect to the proportional gain, integral gain, and derivative gain;

[0051] S43. Obtain the current demand input instruction, parse the current demand input instruction, and obtain the instruction information containing the set target combustion chamber temperature T target and the target nitrogen oxide emission concentration u o，target and the set target methanol flow rate u m，target ; Record the current methanol flow rate u m (t), oxygen flow rate u o (t), and combustion chamber temperature u T (t); Then, according to the current recorded information and instruction information, calculate the error of the current control variable:

[0052] e m = u m,target - u m (t);

[0053] e o = u o，target - u o (t);

[0054] e T = T target - u T (t);

[0055] Obtain the dynamic coupling effect G of each control variable built into the system: The coupling effect matrix G of each control variable built into the system is as follows:

[0056]

[0057] S44. Input the error of the control variable into the coupling effect matrix G, and then calculate the incremental adjustment of each control variable (i.e., the control increment Δu m of the methanol flow rate and the control increment Δu o of the oxygen flow rate and the control increment Δu T ) of the combustion chamber temperature, and sum up the incremental adjustment of each control variable and the recorded current methanol flow rate u m (t), oxygen flow rate u o (t), and combustion chamber temperature u T (t) to obtain and update the control variable at the next control timing node:

[0058] u m u(t + 1)=u m (t)+Δu m ;

[0059] u o u(t + 1)=u o (t)+Δu o ;

[0060] u T u(t + 1)=u T (t)+Δu T 。

[0061] When executing the control variable of the next control timing node under the current methanol flow update, it is judged in real time whether u m (t + 1) is greater than the maximum methanol flow rate u m，max ; If u m (t + 1)> the maximum methanol flow rate u m，max , then u m (t + 1)= the maximum methanol flow rate u m，max 。

[0062] Preferably, as an implementable solution; after step S44, it further includes:

[0063] Further judge whether a comprehensive control operation instruction for restricting methanol flow is received. If a comprehensive control operation instruction for restricting methanol flow is received, set the comprehensive performance index function F;

[0064] Set the comprehensive performance index function F; use the above comprehensive performance index function F to maximize and solve the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node.

[0065] The embodiment of the present invention provides a combustion exhaust gas recirculation control system and control method for an internal combustion engine, and the technical effects are as follows:

[0066] In specific applications, the present invention collects multiple key operating parameters including combustion chamber temperature, pressure, methanol flow rate, oxygen flow rate, and exhaust gas composition. The present invention uses a PID control algorithm to construct a multivariable mathematical model and introduces adaptive control calculation. This method can effectively handle the complexity and strong coupling characteristics in the process of methanol pure oxygen combustion, and improve the adaptability and accuracy of the control system.

[0067] Meanwhile, a comprehensive control mode is also set. When the comprehensive control mode is used, by introducing the comprehensive performance index function F, the present invention simultaneously considers multiple factors such as combustion efficiency, equivalence ratio, combustion chamber temperature, nitrogen oxide emissions, and fuel consumption. This method effectively balances the requirements of emission control and fuel economy. By using an optimization algorithm (such as the gradient descent method) to find the optimal EGR rate, the present invention fully exploits the potential of the exhaust gas recirculation technology in a methanol pure oxygen combustion engine, further improving the performance and emission control ability of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 FIG. is a schematic diagram of the overall control architecture of a combustion exhaust gas recirculation control system for an internal combustion engine;

[0069] Figure 2 FIG. is a schematic diagram of the flow of a combustion exhaust gas recirculation control method for an internal combustion engine;

[0070] Reference numerals: sensor 10; central control unit 20; human-machine interface 30. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0072] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings.

[0073] Embodiment 1: Refer to Figure 1 , the present invention provides a combustion exhaust gas recirculation control system for an internal combustion engine, including:

[0074] A plurality of sensors 10 for collecting engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate, and exhaust gas composition; based on the engine operating parameters, calculate the current actual combustion efficiency, and then detect and obtain the actual nitrogen oxide emission concentration;

[0075] A central control unit 20 for according to the preset target combustion chamber temperature T target and the target nitrogen oxide emission concentration u o,target and the set target methanol flow rate u m,target, calculate the error of the control variable; under the preset condition of restricting the methanol flow rate, use the multivariable adaptive control algorithm to calculate the adjustment amounts of the methanol flow rate, oxygen flow rate, and combustion chamber temperature; under the preset condition of not restricting the methanol flow rate, use the optimal control parameters of the exhaust gas recirculation rate EGR for solving the next control timing node to calculate the adjustment amount of the valve opening; execute the adjustment amount to adjust the corresponding control device actuator; the control device actuator includes a switching valve, a pump, a flow valve, and a combustion temperature controller;

[0076] The human-machine interaction interface 30 is used to display the system operation status and receive operation instructions.

[0077] The combustion optimization control system of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine further includes: a high-precision thermocouple, a piezoresistive pressure sensor, a Coriolis mass flowmeter, and an infrared spectrum analyzer;

[0078] The high-precision thermocouple is used to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber, and calculate the average temperature as the combustion chamber temperature;

[0079] The piezoresistive pressure sensor is used to measure the combustion chamber pressure and obtain the combustion chamber pressure;

[0080] The Coriolis mass flowmeter is used to measure the methanol flow rate and oxygen flow rate respectively;

[0081] The infrared spectrum analyzer is used to analyze the exhaust gas components in real time.

[0082] The present invention uses the PID control algorithm to construct a multivariable mathematical model and introduces adaptive control calculation. This method can effectively handle the complexity and strong coupling characteristics in the methanol pure oxygen combustion process, and improves the adaptability and accuracy of the control system.

[0083] At the same time, a comprehensive control evaluation parameter is introduced to set a comprehensive performance index function F, and the optimal EGR rate in the comprehensive performance index function F is found through an optimization algorithm (such as the gradient descent method). The present invention gives full play to the potential of the exhaust gas recirculation technology in the methanol pure oxygen combustion engine, and further improves the performance and emission control ability of the engine.

[0084] Therefore, the present invention adopts a cyclic optimization method, realizes the continuous optimization and self-regulation of the control system by continuously monitoring the performance of the engine after adjustment and returning to the parameter acquisition step. The control system of the present invention can dynamically adjust target parameters according to the current demand input instruction, such as setting the target combustion chamber temperature and target nitrogen oxide emission, so as to adapt to different working conditions and environmental changes.

[0085] The present invention effectively solves the main problems faced by traditional methanol pure-oxygen combustion internal combustion engines, achieving a stable increase in combustion efficiency, effective control of emissions, improvement in fuel economy, and enhanced intelligence and self-adaptability of the control system. This comprehensive optimization method provides a strong guarantee for the efficient, clean, and economic operation of methanol pure-oxygen combustion exhaust gas recirculation internal combustion engines.

[0086] In the embodiment of the present invention, the internal combustion engine mentioned adopts a multi-variable adaptive control algorithm to calculate the adjustment amounts of methanol flow rate, oxygen flow rate, and exhaust gas recirculation rate; at the same time, the control system adjusts according to the temperature sensor data feedback, and finally makes the engine reach the optimal state. For details, see Embodiment 2.

[0087] Embodiment 2

[0088] See Figure 2 , Embodiment 2 of the present invention provides a combustion optimization control method for a methanol pure-oxygen combustion exhaust gas recirculation internal combustion engine, including the following steps:

[0089] S1. Collect the engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate, and exhaust gas components;

[0090] S2. Based on the engine operating parameters, calculate the current actual combustion efficiency, and then detect and obtain the actual nitrogen oxide emission concentration;

[0091] S3. According to the preset target combustion chamber temperature T target and the target nitrogen oxide emission concentration u o,target and the set target methanol flow rate u m,target , calculate the error of the control variable;

[0092] S4. Under the preset conditions of restricting the methanol flow rate, use a multi-variable adaptive control algorithm to calculate the adjustment amounts of methanol flow rate, oxygen flow rate, and combustion chamber temperature; under the preset conditions without restricting the methanol flow rate, use the optimal control parameters of the exhaust gas recirculation rate EGR for solving the next control time sequence node to calculate the adjustment amount of the valve opening; execute the adjustment amount to adjust the corresponding control device actuator; the control device actuator includes a solenoid valve, a pump, a flow valve, and a combustion temperature controller;

[0093] Preferably, as an implementable solution; the operating parameters collected in step S1 further include:

[0094] S11. Use a high-precision thermocouple to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber, and calculate the average temperature as the combustion chamber temperature;

[0095] S12. Use a piezoresistive pressure sensor to measure the combustion chamber pressure and obtain the combustion chamber pressure;

[0096] S13. Measure the methanol flow rate and oxygen flow rate respectively using a Coriolis mass flowmeter;

[0097] S14. Analyze the exhaust gas components in real time through an infrared spectroscopy analyzer to obtain the exhaust gas component analysis results.

[0098] Analyze the exhaust gas components in real time through an infrared spectroscopy analyzer to obtain the exhaust gas component analysis results (assuming that there are three types of the above exhaust gas component analysis results, namely CO, CO2, and O2 and their respective concentrations.

[0099] Preferably, as an implementable solution; the method for calculating the combustion efficiency in step S2 includes:

[0100] S21. Calculate the theoretical thermal efficiency based on the combustion chamber temperature and combustion chamber pressure;

[0101] S22. Use the actual detection ratio of the methanol flow rate and oxygen flow rate to calculate the current actual air-fuel ratio; then calculate the corrected current air-fuel ratio based on the current actual air-fuel ratio, the preset ideal air-fuel ratio, and the adjustment parameter;

[0102] Corrected current air-fuel ratio

[0103] Where: AFR 实际 : The actual air-fuel ratio calculated in step S22;

[0104] AFR 理想 : Ideal air-fuel ratio;

[0105] σ: Represents an adjustment parameter;

[0106] S23. Calculate the proportion of unburned fuel according to the exhaust gas component analysis results;

[0107] S24. Output and calculate the actual combustion efficiency by comprehensively considering the above parameters, namely the theoretical thermal efficiency, the corrected current air-fuel ratio, and the proportion of unburned fuel, to obtain the actual combustion efficiency.

[0108] The calculation formula for the actual combustion efficiency is: η 实际( = η 理论( ·k 空燃比( ·1 - r 末完全燃烧 ;

[0109] η 实际 : The finally calculated actual combustion efficiency;

[0110] η 理论 : Theoretical thermal efficiency;

[0111] k 空燃比: The corrected current air-fuel ratio k 空燃比 ;

[0112] r 末完全燃烧 : Represents the proportion of unburned fuel.

[0113] Specifically, parameter S refers to calculating the output of the actual combustion efficiency by comprehensively utilizing the theoretical thermal efficiency, the corrected current air-fuel ratio, and the proportion of unburned fuel.

[0114] In the specific technical solution of this embodiment, during the execution of step S23, according to the exhaust gas component analysis result, calculate the proportion of unburned fuel, specifically:

[0115] For example: Calculate the proportion of unburned fuel

[0116] Suppose a combustion test is carried out for this technical solution, and the following exhaust gas component analysis results are obtained (it is also possible):

[0117] CO (nitric oxide) concentration: 1000 ppm;

[0118] CO2 (carbon dioxide) concentration: 12%;

[0119] O2 (oxygen) concentration: 3%;

[0120] Explanation: The reason why the exhaust gas (such as CO2) is recycled in the technical solution of this application embodiment is that it is found that it has the following technical effects: The high-temperature carbon dioxide and water vapor generated by the combustion of methanol and pure oxygen after mixing in the cylinder, when the high-temperature carbon dioxide and water vapor are input as the recycled gas medium again, will be mixed with oxygen, thereby reducing the pure oxygen concentration and ensuring the volume of the gas entering the engine cylinder (that is, by mixing the high-temperature carbon dioxide and water vapor with oxygen, the oxygen concentration entering the cylinder can be reduced. This is because carbon dioxide and water vapor occupy a part of the volume, reducing the volume ratio of pure oxygen. Although the oxygen concentration is reduced, by recycling the exhaust gas, the total volume of the gas entering the engine cylinder can be kept unchanged or increased appropriately. In this way, the power output of the engine can be maintained).

[0121] On the other hand, by recycling the high-temperature exhaust gas (such as CO2) after combustion, that is, these high-temperature gases can be used as the recycled gas medium, the fuel utilization rate can be further improved. On another aspect, recycling the exhaust gas can reduce the carbon dioxide emissions because part of the carbon dioxide is reused instead of being directly emitted into the atmosphere.

[0122] 1. First, calculate the theoretical proportion of unburned fuel:

[0123] The proportion of unburned fuel can usually be estimated by the concentrations of CO and CO2. The technical solution can use the following formula:

[0124]

[0125] Where:

[0126] C CO is the CO concentration (ppm).

[0127] is the CO2 concentration (expressed in ppm).

[0128] 2. Convert the concentration unit:

[0129] First, the technical solution needs to convert the CO2 concentration to ppm:

[0130]

[0131] 3. Calculate the proportion of unburned fuel

[0132] Substitute the concentration into the formula:

[0133] r 末完全燃烧 = 10001000 + 120000 = 1000121000 ≈ 0.00826;

[0134] 4. Convert to percentage:

[0135] Convert the proportion to percentage: r 末完全燃烧 ≈ 0.826%;

[0136] Analyzing the above embodiments, it can be seen that through the exhaust gas component analysis, the exhaust gas component analysis result is obtained, and then the software calculation operation is continued. The embodiment of the present application obtains that the proportion of unburned fuel is about 0.826%. This value can be used for further combustion efficiency calculation and optimization.

[0137] Explanation, in the specific technical solution of the embodiment of the present application, since

[0138] The formula for the actual combustion efficiency is: η 实际( = η 理论( ·k 空燃比( ·1 - r 末完全燃烧 ;

[0139] Variable description of the above calculation formula:

[0140] η 实际 : The actual combustion efficiency finally calculated.

[0141] η 理论 : The theoretical thermal efficiency calculated in step S21.

[0142] k 空燃比 : The data obtained by implementing calculations based on the correction coefficient of the current air-fuel ratio, that is, the corrected current air-fuel ratio k 空燃比 .

[0143] r 末完全燃烧 : Represents the proportion of unburned fuel.

[0144] Specific implementation process description: η 理论 Calculated from the combustion chamber temperature and the combustion chamber pressure; the corrected current air-fuel ratio, namely k 空燃比 , is output and calculated based on the correction coefficient of the current air-fuel ratio, the preset ideal air-fuel ratio, and the adjustment parameter. The calculation formula is:

[0145] Corrected current air-fuel ratio

[0146] Where: AFR 实际 : The current air-fuel ratio calculated in step S22. AFR 理想 : Ideal air-fuel ratio (usually about 1.5 for methanol). σ: Represents an adjustment parameter (for example, it can be taken as 0.2). The above r 末完全燃烧 : The proportion of unburned fuel calculated in step S23.

[0147] During the execution of the above step S24, η 实际( = η 理论( ·k 空燃比( ·1 - r 末完全燃烧 ; The above processing process takes into account the theoretical efficiency, the influence of the corrected air-fuel ratio, and the efficiency loss caused by incomplete combustion. Through this information processing process, the embodiments of the present application obtain a relatively accurate estimate of the actual combustion efficiency.

[0148] Preferably, as an implementable solution; said step S3 calculates the error of the control variable according to the preset target combustion chamber temperature T target and the target nitrogen oxide emission concentration u o,target and the set target methanol flow rate u m,target , and said step S4 uses a multivariable adaptive control algorithm to calculate the adjustment amounts of the methanol flow rate, the oxygen flow rate, and the combustion chamber temperature, including the following steps:

[0149] S41. Implement the PID control algorithm for each control variable to construct a multivariable mathematical model. The control variables include the methanol flow rate u m , the oxygen flow rate u o , and the combustion chamber temperature u T ;

[0150] The calculation formula of the multivariate mathematical model is as follows:

[0151]

[0152] where i ∈ m, o, T, representing methanol flow rate, oxygen flow rate, and combustion chamber temperature respectively;

[0153] S42. Implement adaptive control calculation for the multivariate mathematical model:

[0154]

[0155]

[0156]

[0157] where K p,i (t + 1) is the value of the proportional gain of the i-th control variable (such as methanol flow rate, oxygen flow rate, or combustion chamber temperature) at time t + 1. It is used to control the system's response to the current error.

[0158] K i,i (t + 1) is the value of the integral gain of the i-th control variable at time t + 1t + 1t + 1. The integral gain is used to eliminate the steady-state error, that is, to adjust the output by accumulating past errors.

[0159] K d,i (t + 1 is the value of the derivative gain of the i-th control variable at time t + 1. The derivative gain is used to predict future error changes and helps reduce the overshoot phenomenon of the system;

[0160] α p ,α i ,α d are their respective learning rates, and E is the preset threshold index of the comprehensive fuel energy-saving performance;

[0161] α p : The learning rate of the proportional gain. It controls the adjustment amplitude of the proportional gain during the update process and affects the convergence speed and stability of the system.

[0162] ai: The learning rate of the integral gain. It controls the adjustment amplitude of the integral gain during the update process and affects the improvement speed of the steady-state performance.

[0163] ad: The learning rate of the derivative gain. It controls the adjustment amplitude of the derivative gain during the update process and affects the reaction sensitivity to error changes.

[0164] The preset threshold index for the comprehensive performance of E fuel saving. It is an objective function for measuring the system performance, and the update of PID parameters will be based on the gradient information of this index.

[0165] are the partial derivatives of the performance index E with respect to the proportional gain, integral gain, and derivative gain respectively;

[0166] S43. Obtain the current demand input instruction, parse the current demand input instruction, and obtain the instruction information containing the set target combustion chamber temperature T targe t and the target nitrogen oxide emission concentration u o，target as well as the set target methanol flow rate u m，target ; Record the current methanol flow rate u m (t), oxygen flow rate u o (t) and combustion chamber temperature u T (t); Then, according to the current recorded information and instruction information, calculate the error of the current control variable:

[0167] e m = u m，target - u m (t);

[0168] e o = u o，target - u o (t);

[0169] e T = T target - u T (t);

[0170] Obtain the dynamic coupling effect G of each control variable built into the system: The coupling effect matrix G of each control variable built into the system is as follows:

[0171]

[0172] S44. Input the error of the control variable into the coupling effect matrix G, and then calculate the incremental adjustment of each control variable (i.e., the control increment Δu of the output methanol flow rate m and the control increment Δu of the oxygen flow rate o and the control increment Δu of the combustion chamber temperature T ), and sum up the incremental adjustment of each control variable and the recorded current methanol flow rate u m (t), oxygen flow rate u o (t) and combustion chamber temperature u T (t) to obtain and update the control variable at the next control timing node:

[0173] u m(t + 1) = u m u(t) + Δu m ;

[0174] u o (t + 1) = u o u(t) + Δu o ;

[0175] u T (t + 1) = u T u(t) + Δu T .

[0176] When executing the control variable of the next control timing node under the current methanol flow update, it is judged in real time whether u m (t + 1) is greater than the maximum methanol flow u m,max ; If u m (t + 1) > the maximum methanol flow u m,max , then u m (t + 1) = the maximum methanol flow u m，max .

[0177] In the above execution process, sensor data is collected, that is, data is obtained from temperature sensors, pressure sensors, flow sensors, etc. Then the above error is calculated: the difference between the actual value and the set target value is calculated. The control amount to be adjusted (i.e., the control increment Δu m of methanol flow and the control increment Δu o of oxygen flow and the control increment Δu T of combustion chamber temperature) is calculated according to the control algorithm. Finally, the control is implemented: that is, the control is implemented by adjusting actuators such as valves and pumps.

[0178] For example: Suppose there is an internal combustion engine burning methanol in the above embodiment, and the goal is to optimize its operating performance so that it reaches the best combustion efficiency and emission control under specific load conditions. The following shows how to apply the above scheme to this case:

[0179] Obtain the current demand input instruction, parse the current demand input instruction, and obtain the set target combustion chamber temperature T target and the target nitrogen oxide emission NO x，target and the instruction information of the set target methanol flow u m,target and the maximum value of the set methanol flow u m,max ;

[0180] In the initial state, record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t). Calculate the current error: e m = um,target -u m (t); e o = u o,target -u o (t); e T = T target -u T (t);

[0181] Calculate the current multivariable control error, and output the control increment Δu of the methanol flow rate according to the current multivariable control error and the coupling effect matrix G of each control variable built in the system m and the control increment Δu of the oxygen flow rate o and the control increment Δu of the combustion chamber temperature T : Calculate Δu by using the dynamic coupling effect G of each control variable built in the system m , Δu o , Δu T , for example: Assume that the dynamic coupling effect G of each control variable built in the system is known, and calculate the required control increment. Among them, G is a 3x3 built-in parameter factor coupling matrix of the system.

[0182] Adjust the control variable according to the increment calculated at the next control timing node (i.e., the next control moment): u m (t + 1)= u m (t)+Δu m ; u o (t + 1)= u o (t)+Δu o ; u T (t + 1)= u T (t)+Δu T ;

[0183] Explanation: In the multivariable control algorithm, Δu m represents the control increment of the methanol flow rate. It is achieved by adjusting the control error (for example, the difference between the actual output and the target output). Specifically, the control system calculates the methanol flow rate that needs to be adjusted according to the dynamic characteristics of the system and the error feedback to make the system closer to the set target.

[0184] When executing the control variable at the next control timing node for the current methanol flow rate update, judge in real time whether u m (t + 1) is greater than the maximum methanol flow rate u m,max ; if u m (t + 1)> the maximum methanol flow rate u m,max , then u m (t + 1)= the maximum methanol flow rate u m,max .

[0185] In the multivariable control algorithm, the control increments are described using the following matrix equation:

[0186]

[0187] Here G is a dynamic matrix that includes the coupling effect of the system on each control variable. By solving this equation, the adjustment amount of each control variable (such as Δu m ). This indicates the adjustments that need to be made to each control variable in order to eliminate the error e.

[0188] In another synchronous specific implementation, each control variable can also be adjusted by a comprehensive performance index function; after step S44, it also includes: further determining whether a comprehensive control operation instruction is received, and if a comprehensive control operation instruction is received, setting a comprehensive performance index function F;

[0189] By maximizing the comprehensive performance index function F, the optimal control parameters of the exhaust gas recirculation rate EGR at the next control timing node are solved.

[0190] Preferably, as an implementable embodiment; the setting of the comprehensive performance index function F; utilizing the above-mentioned comprehensive performance index function F to maximize and solve the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node, specifically includes:

[0191] S45: Setting comprehensive performance index function F:

[0192] F = w1*η exhaust methanol detection side combustion efficiency + w2*(1-|φ-φopt|)+w3*(1-|T-Topt| / Tmax)-w4*(NOx(t) / NOx,target)-w5*(FC / FCbaseline)+w6*(1-|EGR-EGRopt| / EGRmax);

[0193] η is the combustion efficiency of the exhaust gas methanol detection side;

[0194] φ: current equivalence ratio;

[0195] φ opt : Optimal equivalence ratio;

[0196] T: current combustion chamber temperature;

[0197] T opt : Optimal combustion chamber temperature;

[0198] T max : Maximum permissible combustion chamber temperature;

[0199] NOx(t): current nitrogen oxide emissions;

[0200] NOx target : Target NOx emissions;

[0201] FC: Current fuel consumption rate;

[0202] FC bascline : Baseline fuel consumption rate;

[0203] EGR: Current exhaust gas recirculation rate;

[0204] EGR opt : Optimal exhaust gas recirculation rate;

[0205] EGR max : Maximum allowable exhaust gas recirculation rate;

[0206] S46: Define the calculation methods for each parameter:

[0207] First, define η methanol detection side combustion efficiency of exhaust gas = (LHVin - LHV_out) / LHVin;

[0208] Where, LHV_in is the lower heating value of methanol entering the combustion chamber, and LHV_out is the lower heating value of unburned methanol in the exhaust gas;

[0209] Then, define the equivalence ratio φ:

[0210] Equivalence ratio φ = (m f uel / m o xygen) / (m f uel / m o xygen)stoich iometric;

[0211] Where: φ: represents the equivalence ratio; m f uel: represents the fuel mass; m o xygen: represents the oxygen mass;

[0212] (m f uel / m o xygen)stoich iometric: represents the theoretical stoichiometric ratio;

[0213] Then, directly obtain the actual combustion chamber temperature T and the actual NOx emissions N0x(t); obtain the optimal combustion chamber temperature T opt and the maximum allowable combustion chamber temperature Tmax and the target NOx emissions NOx target

[0214] Obtain the baseline fuel consumption rate, and then calculate the fuel consumption rate FC: FC = m f uel / Poweroutput;

[0215] Among them, FC represents the fuel consumption rate; m f uel represents the fuel mass; Poweroutput represents the engine output power;

[0216] mfuel represents the fuel mass, usually expressed in grams per second (g / s) or kilograms per hour (kg / h)

[0217] Poweroutput represents the engine output power, usually expressed in kilowatts (kW);

[0218] The formula calculates the fuel consumption per unit power output, usually expressed in grams per kilowatt-hour (g / kWh). It is an important indicator to measure the fuel efficiency of the engine. The lower the value, the higher the fuel efficiency of the engine.

[0219] Calculate the EGR rate: EGR = m_recirculated / m_total_intake;

[0220] Among them, EGR represents the exhaust gas recirculation rate; m_recirculated represents the mass of the recirculated exhaust gas; m_total_intake represents the total intake mass (including fresh intake and recirculated exhaust gas);

[0221] This formula calculates the proportion of the recirculated exhaust gas in the total intake. EGR is usually expressed as a percentage and is used to control the combustion temperature and nitrogen oxide (NOx) emissions of the engine. A higher EGR rate can reduce the combustion temperature, thereby reducing the formation of NOx, but it may also affect the performance and efficiency of the engine.

[0222] Obtain the specific values of the matching weight coefficients w1 - w6, and substitute all parameters into the formula for the comprehensive performance index function F to calculate the F value under the current working conditions;

[0223] S46. Optimize the EGR rate to solve for the maximum comprehensive performance index F: First, obtain the search range and step size for defining the EGR rate;

[0224] EGRmin = x1%, EGRmax = x2%, step size ΔEGR = n%;

[0225] Optimize EGR using the gradient descent method according to the above EGRmin, EGRmax, and ΔEGR. When specifically optimizing, obtain the set learning rate learning_rate, maximum number of iterations max_iterations, and tolerance tolerance to iteratively update the EGR value;

[0226] In each iteration, calculate the gradient of the comprehensive performance index F with respect to EGR, update the EGR value, and check whether the termination condition is met. Meanwhile, the EGR value will be adjusted iteratively during this process until a local maximum is found and recorded as the optimal EGR value.

[0227] Take the optimal EGR value as the target value, and parse the optimal actuator control parameters corresponding to the current target value when it is applied to the engine control system.

[0228] During the execution of a specific case, determine the weight coefficients: obtain the corresponding weight coefficients according to the engine type. For example, determine the values of w1 to w6 through experiments and expert experience. For example:

[0229] w1 = 0.3, w2 = 0.15, w3 = 0.15, w4 = 0.2, w5 = 0.1, w6 = 0.1

[0230] Calculate the value of F: Substitute all parameters into the formula of the comprehensive performance index function F to calculate the value of F under the current working conditions.

[0231] S46. Optimize the EGR rate to maximize the comprehensive performance index F:

[0232] Define the search range and step size of the EGR rate:

[0233] EGRmin = 0%, EGRmax = 30%, step size ΔEGR = 0.5%;

[0234] For example, the code to implement the golden section search algorithm:

[0235] def golden_section_search(f, a, b, tol = 1e - 5):

[0236] gr = (Sqrt(5)+1) / 2 # Golden ratio c = b - (b - a) / gr

[0237] d = a+(b - a) / gr while abs(b - a)>tol: if f(c)>f(d): b = d

[0238] else:

[0239] a = c

[0240] c = b - (b - a) / gr

[0241] d = a+(b - a) / gr return (b + a) / 2 # Define the objective function (negative F because we want to maximize F in this embodiment) def objective(EGR):

[0242] return-calculate_F(EGR) # The calculate_F function implements the F calculation in S45

[0243] Use the golden section search to find the optimal EGR. EGR_optimal =

[0244] golden_section_search(objective, EGRmin, EGRmax)

[0245] Real-time EGR control strategy:

[0246] According to the above EGRmin, EGRmax, and ΔEGR, use the gradient descent method to optimize EGR. When specifically optimizing, obtain the set learning rate learning_rate, the maximum number of iterations max_iterations, and the tolerance tolerance to iteratively update the EGR value.

[0247] In each iteration, calculate the gradient of the maximized comprehensive performance index F with respect to EGR, update the EGR value, and check whether the termination condition is satisfied. At the same time, in this process, the EGR value will be iteratively adjusted until a local maximum is found and recorded as the optimal EGR value.

[0248] Take the optimal EGR value as the target value and parse the optimal actuator control parameters (such as valve opening) corresponding to the current target value applied to the engine control system.

[0249] For example: This technical solution sets the search range of EGR. For example, EGRmin = 0% and EGRmax = 20%. Select an initial EGR value, such as EGR = 5%.

[0250] Use the gradient descent method to optimize EGR. In this embodiment, the learning rate learning_rate =

[0251] 0.01, the maximum number of iterations max_iterations = 100, and a tolerance tolerance =

[0252] 0.001. In each iteration, calculate the gradient of F with respect to EGR, update the EGR value, and check whether the termination condition is satisfied. This process will iteratively adjust EGR until a local maximum is found. Once the optimal EGR value is found, such as EGR_optimal = 12%, apply it to the engine control system and parse the optimal actuator control parameters (such as valve opening) corresponding to the current target value applied to the engine control system to implement the control strategy of this optimal value.

[0253] EGR_optimal represents the optimal exhaust gas recirculation rate that can maximize the comprehensive performance index function F under given conditions. After obtaining the EGR_optimal value, implementing this optimal value control strategy through actuator control parameters can achieve the overall optimization of engine performance. It helps to better balance the control of nitrogen oxide (NOx) emissions and combustion efficiency, and the optimal EGR value takes into account the balance of multiple performance indicators.

[0254] Illustrative example:

[0255] The current engine parameters are as follows:

[0256] Combustion efficiency η: 85%;

[0257] Equivalence ratio φ: 1.2;

[0258] Combustion chamber temperature T: 1800K;

[0259] Optimal combustion temperature Topt: 1750K;

[0260] Maximum allowable combustion temperature Tmax: 2000K;

[0261] Current nitrogen oxide emissions NOx(t): 100 ppm;

[0262] Target nitrogen oxide emissions NOx,target: 50 ppm;

[0263] Current fuel consumption rate FC: 250 g / kWh;

[0264] Baseline fuel consumption rate FCbaseline: 270 g / kWh;

[0265] The weight coefficients w1 - w5 are set according to actual requirements and engineers' judgments. For example:

[0266] w1 = 0.4 (attach importance to combustion efficiency);

[0267] w2 = 0.2 (attach medium importance to equivalence ratio);

[0268] w3 = 0.1 (attach relatively low importance to temperature deviation);

[0269] w4 = 0.2 (attach importance to nitrogen oxide emissions);

[0270] w5 = 0.1 (concern about fuel consumption);

[0271] Now, this embodiment applies S45 and S46 to optimize the EGR control:

[0272] First, calculate the comprehensive performance index function F:

[0273] F = (0.4 * 0.85) + (0.2 * (1 - |1.2 - 1|)) + (0.1 * (1 - |1800 - 1750| / 2000)) - (0.2 * (100 / 50)) - (0.1 * (250 / 270));

[0274] Then, in this embodiment, the search range of EGR is set. For example, EGRmin = 0% and EGRmax = 20%. An initial EGR value is selected, such as EGR = 5%. The gradient descent method is used to optimize EGR. In this embodiment, the learning rate learning_rate = 0.01, the maximum number of iterations max_iterations = 100, and a tolerance tolerance = 0.001 can be set. In each iteration, the gradient of F with respect to EGR is calculated, the EGR value is updated, and it is checked whether the termination condition is satisfied. This process will iteratively adjust EGR until a local maximum is found. Once the optimal EGR value is found, such as EGR_optimal = 12%, it is applied to the engine control system to adjust the EGR valve opening to achieve this optimal value.

[0275] Based on reality: It is found through research that if there is still methanol in excessive exhaust gas, the following problems may occur: 1. Increase in nitrogen oxide (NOx) emissions; 2. Temperature rise: The presence of methanol in the exhaust gas may cause the combustion chamber temperature to rise, increase the generation of NOx, resulting in environmental pollution and non-compliance with regulations. Engine performance problems; 3. Power loss: Unburned methanol may affect the overall performance and power output of the engine, leading to slower acceleration and response. 4. Excessive unburned methanol may cause carbon deposition, which in turn affects the combustion efficiency (comprehensive performance index function F). 4. Excessive methanol may affect the performance of the catalyst, resulting in a decrease in the working efficiency of the catalytic converter, thus affecting the comprehensive performance index function F.

[0276] However, further research finds that the above problems 1 - 3 are long-term problems and will not affect the engine performance in a short time. However, carbon deposition and the impact on catalyst performance have a greater impact on the comprehensive performance index function F in a short time;

[0277] In the further research process, it is found that even if the methanol flow rate is not restricted, but if the methanol flow rate is excessive, it still affects the comprehensive performance index function F of the above steps; an improved design is proposed, and then the improved comprehensive performance index function F' is output;

[0278] To more comprehensively consider the impacts of introducing excessive methanol on catalyst performance degradation, increased carbon deposition, and combustion efficiency attenuation, we will redesign step S45, which is the modified step S50. The maximum working efficiency of the catalyst, the working efficiency of the current catalyst, and the influence factor of carbon deposition on combustion efficiency will be introduced into the comprehensive performance index function. The following is the redesigned content:

[0279] Execute the following step S50: Reset the comprehensive performance index function F', and then recalculate and iteratively adjust the EGR:

[0280] The comprehensive performance index function F' is defined as:

[0281]

[0282] Parameter description:

[0283] w1, w2, w3, w4, w5, w6, w7, w8w_1, w_2, w_3, w_4, w_5, w_6, w_7, w_8w1

[0284] , w2, w3, w4, w5, w6, w7, w8: Weight coefficients used to adjust the influence degree of each index on the comprehensive performance, and need to be set according to specific applications.

[0285] φ: The current equivalence ratio, representing the ratio of fuel to oxygen, and the ideal value should be close to the theoretical value.

[0286] φ opt : The optimal equivalence ratio, determined through experiments or model analysis.

[0287] T: The current combustion chamber temperature, which affects combustion efficiency and emissions.

[0288] T opt : The optimal combustion chamber temperature, determined through experiments.

[0289] T max : The maximum allowable combustion chamber temperature, above which may cause engine damage or excessive NOx emissions.

[0290] NOx(t): The current nitrogen oxide emissions, which need to be controlled within the range permitted by regulations.

[0291] NOx target : The set target nitrogen oxide emissions.

[0292] FC: The current fuel consumption rate, reflecting fuel usage efficiency.

[0293] EGR: The current exhaust gas recirculation rate, which directly affects combustion characteristics and emission levels.

[0294] EGRopt : Optimal Exhaust Gas Recirculation (EGR) rate, determined by an optimization algorithm.

[0295] EGR max : Maximum allowable Exhaust Gas Recirculation rate.

[0296] C max : Maximum operating efficiency of the catalyst, determined based on the catalyst's design and material properties.

[0297] C current : Current operating efficiency of the catalyst, which needs to be monitored regularly to evaluate the catalyst's performance.

[0298] S max : Maximum carbon deposition tolerance of the catalyst, referring to the maximum amount of carbon deposition that the catalyst can accept while maintaining its performance. S current : Current carbon deposition level of the catalyst, which affects the effectiveness of the catalyst and the combustion efficiency.

[0299] The technical solution adopted in the embodiments of the present invention takes into account the influence of catalyst performance and carbon deposition;

[0300] In the new comprehensive performance index function, two new terms are added:

[0301] 1. Influence of catalyst operating efficiency:

[0302] The term is introduced to evaluate the influence of the decrease in catalyst performance. When the current catalyst efficiency is lower than the maximum efficiency, this term will have a negative impact on the comprehensive performance index F, prompting the system to adjust the operation to restore the catalyst performance.

[0303] 2. Influence of carbon deposition:

[0304] The term is introduced to evaluate the influence of carbon deposition on the catalyst performance. The increase in carbon deposition will lead to a decrease in the activity of the catalyst, thereby affecting the combustion efficiency and emission control.

[0305] In summary, through the redesign of the comprehensive performance index function FFF, the potential influence of excessive methanol introduction on the decrease in catalyst performance and the increase in carbon deposition has been comprehensively considered. This improvement will help achieve more refined engine control, ensure compliance with environmental regulations while optimizing the combustion efficiency and catalyst performance. By dynamically adjusting the EGR rate and other control parameters, emissions can be effectively reduced, and the overall system economy and reliability can be improved.

[0306] Then recalculate and iteratively adjust the EGR, which means that after step S50 is executed, then return to execute step S46, that is, optimize the EGR rate to solve for the maximum value of the output comprehensive performance index F, and optimally obtain the updated optimal target value of the EGR.

[0307] The control method of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine adopted in the embodiment of the present invention improves the engine power and thermal efficiency through the mixing combustion technology of methanol, pure oxygen and the high-temperature exhaust gas of the engine, realizes the recycling of the high-temperature exhaust gas of the internal combustion engine, and especially conducts in-depth control in a specific direction around the reasonable ratio control of the methanol flow rate, ensuring the comprehensive combustion performance of the engine.

[0308] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments, and will not be described herein again.

[0309] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A combustion optimization control system for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, characterized in that Including: Multiple sensors for collecting engine operation parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate, and exhaust gas components; based on the engine operation parameters, calculate the current actual combustion efficiency, and then detect and obtain the concentration of actual nitrogen oxide emissions. A central control unit, configured to calculate the error of a control variable according to a preset target combustion chamber temperature and a target nitrogen oxide emission concentration as well as a set target methanol flow rate , and calculate the adjustment amounts of the methanol flow rate, the oxygen flow rate, and the combustion chamber temperature by using a multivariable adaptive control algorithm under a preset condition for restricting the methanol flow rate; Under the preset condition of no restriction on methanol flow rate, set the comprehensive performance index function F; maximize the above comprehensive performance index function F to solve the optimal control parameter of the exhaust gas recirculation rate EGR at the next control time sequence node, and calculate the adjustment amount of the valve opening. Maximize the above comprehensive performance index function F to solve the optimal control parameter of the exhaust gas recirculation rate EGR at the next control time sequence node, where the comprehensive performance index function F = w1 * η exhaust gas methanol detection side combustion efficiency + w2 * (1 - |φ - φopt|) + w3 * (1 - |T - Topt| / Tmax) - w4 * (NOx(t) / NOx, target) - w5 * (FC / FCbaseline) + w6 * (1 - |EGR - EGRopt| / EGRmax); η is the combustion efficiency of the exhaust gas methanol detection side; φ: current equivalence ratio; φ opt : Optimal equivalence ratio; T: current combustion chamber temperature; T opt : Optimal combustion chamber temperature; T max : Maximum allowable combustion chamber temperature; NOx(t): current nitrogen oxide emissions; NOx target : Target nitrogen oxide emissions; FC: current fuel consumption rate; FC bascline : Benchmark fuel consumption rate; EGR: current exhaust gas recirculation rate; EGR opt : Optimal exhaust gas recirculation rate; EGR max : Maximum allowable exhaust gas recirculation rate; Execute the adjustment amount to adjust the corresponding control device actuator; the control device actuator includes a switch valve, a pump, a flow valve, and a combustion temperature controller; A human-machine interaction interface for displaying the system operation status and receiving operation instructions.

2. The combustion optimization control system of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine according to claim 1, characterized in that, Also including: A high-precision thermocouple, a piezoresistive pressure sensor, a Coriolis mass flowmeter, and an infrared spectroscopy analyzer; The high-precision thermocouple is used to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber, and calculate the average temperature as the combustion chamber temperature; The piezoresistive pressure sensor is used to measure the combustion chamber pressure and obtain the combustion chamber pressure; The Coriolis mass flowmeter is used to measure the methanol flow rate and the oxygen flow rate respectively; The infrared spectroscopy analyzer is used to analyze the exhaust gas components in real time.

3. A combustion optimization control method for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, characterized in that, It uses the combustion optimization control system of a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine that implements the method described in any one of claims 1-2 to perform control processing, including the following steps: S1. Collect engine operation parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate, and exhaust gas components; S2. Based on the engine operation parameters, calculate the current actual combustion efficiency, and then detect and obtain the concentration of actual nitrogen oxide emissions; S3. Calculate the error of the control variable according to the preset target combustion chamber temperature and the target nitrogen oxide emission concentration as well as the set target methanol flow rate . S4. Under the preset condition of restricting the methanol flow rate, use the multivariable adaptive control algorithm to calculate the adjustment amounts of the methanol flow rate, oxygen flow rate, and combustion chamber temperature. Under the preset condition of not restricting the methanol flow rate, set the comprehensive performance index function F; maximize the above comprehensive performance index function F to solve the optimal control parameters of the exhaust gas recirculation rate EGR at the next control timing node, and calculate the adjustment amount of the valve opening. Maximize the above comprehensive performance index function F to solve the optimal control parameters of the exhaust gas recirculation rate EGR at the next control timing node, where the comprehensive performance index function F = w1 * η combustion efficiency on the methanol detection side of the exhaust gas + w2 * (1 - |φ - φopt|) + w3 * (1 - |T - Topt| / Tmax) - w4 * (NOx(t) / NOx, target) - w5 * (FC / FCbaseline) + w6 * (1 - |EGR - EGRopt| / EGRmax); η is the combustion efficiency on the methanol detection side of the exhaust gas; φ: current equivalence ratio; φ opt : Optimal equivalence ratio; T: current combustion chamber temperature; T opt : Optimal combustion chamber temperature; T max : Maximum allowable combustion chamber temperature; NOx(t): current nitrogen oxide emission; NOx target : Target nitrogen oxide emissions; FC: current fuel consumption rate; FC bascline : Benchmark fuel consumption rate; EGR: current exhaust gas recirculation rate; EGR opt : Optimal exhaust gas recirculation rate; EGR max : Maximum allowable exhaust gas recirculation rate; Execute the above adjustment amount to adjust the corresponding control device actuator; the control device actuator includes a switching valve, a pump, a flow valve, and a combustion temperature controller.

4. The method according to claim 3, wherein The operating parameters collected in step S1 further include: S11. Use a high-precision thermocouple to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber, and calculate the average temperature as the combustion chamber temperature; S12. Use a piezoresistive pressure sensor to measure the combustion chamber pressure and obtain the combustion chamber pressure; S13. Use a Coriolis mass flowmeter to measure the methanol flow rate and oxygen flow rate respectively; S14. Analyze the exhaust gas components in real time through an infrared spectroscopic analyzer to obtain the exhaust gas component analysis result.

5. The method according to claim 4, wherein The method for calculating the combustion efficiency in step S2 includes: S21. Calculate the theoretical thermal efficiency based on the combustion chamber temperature and combustion chamber pressure; S22. Use the actual detection ratio of the methanol flow rate and oxygen flow rate to calculate the current actual air-fuel ratio; then calculate the corrected current air-fuel ratio based on the current actual air-fuel ratio, the preset ideal air-fuel ratio, and the adjustment parameter; Corrected current air-fuel ratio ; Wherein: AFR 实际 : The actual air-fuel ratio calculated in step S22; AFR 理想 : Ideal air-fuel ratio; : represents a regulation parameter; S23. Calculate the proportion of unburned fuel according to the exhaust gas component analysis result; S24. Output and calculate the actual combustion efficiency by comprehensively considering the theoretical thermal efficiency, the corrected current air-fuel ratio, and the proportion of unburned fuel to obtain the actual combustion efficiency; The calculation formula for the actual combustion efficiency is: ; : The finally calculated actual combustion efficiency; : Theoretical thermal efficiency; : The corrected current air-fuel ratio ; : Represents the proportion of unburned fuel.

6. The method according to claim 5, wherein The step S3 is based on a preset target combustion chamber temperature and a target nitrogen oxide emission concentration as well as a set target methanol flow rate , and calculates the error of the control variable; The step S4 uses a multivariable adaptive control algorithm to calculate the adjustment amounts of the methanol flow rate, the oxygen flow rate, and the combustion chamber temperature, including the following steps: S41. Implement the PID control algorithm for each control variable to construct a multivariable mathematical model, where the control variables include ; The calculation formula of the multivariable mathematical model is: ； i represents three control variables; S42. Implement adaptive control calculation for the multivariable mathematical model: ； ； ； is the value of the proportional gain of the control variable, which is one of the three control variables of methanol flow rate, oxygen flow rate, or combustion chamber temperature, at time t + 1; it is used to control the system's response to the current error; is the value of the integral gain of a control variable that is one of three control variables: methanol flow rate, oxygen flow rate, or combustion chamber temperature, at time t+1; the integral gain is used to eliminate the steady-state error, i.e., to adjust the output by accumulating past errors. is the value of the derivative gain of a control variable that is one of three control variables: methanol flow rate, oxygen flow rate, or combustion chamber temperature, at time t+1; the derivative gain is used to predict future error changes and helps reduce the overshoot phenomenon of the system; ; is the error of the current control variable; They are the partial derivatives of the performance index E with respect to the proportional gain, integral gain, and derivative gain, respectively; S43. Obtain the current demand input instruction, parse the current demand input instruction, and obtain the instruction information containing the set target combustion chamber temperature and the target nitrogen oxide emission concentration as well as the set target methanol flow rate ; Record the current methanol flow rate , oxygen flow rate and combustion chamber temperature ; Then, according to the current recorded information and instruction information, calculate the error of the current control variable: ； ； ； Obtain the dynamic coupling effect of each built-in control variable of the system : The coupling effect matrix of each built-in control variable of the system , as follows: ； S44. Input the error of the control variable into the coupling effect matrix , then calculate the incremental adjustment of each control variable obtained, adjust each control variable incrementally, and record the current methanol flow rate , oxygen flow rate , and combustion chamber temperature to perform a summation operation to obtain and update the control variable for the next control timing node: ； ； 。 7. Update the control variables of the next control timing node with the current methanol flow rate and judge in real time whether it is greater than the maximum methanol flow rate ; if > the maximum methanol flow rate , then = the maximum methanol flow rate .

8. The method according to claim 6, wherein After step S44, it further includes: Further determine whether a comprehensive control operation instruction for not restricting the methanol flow rate is received. If a comprehensive control operation instruction for restricting the methanol flow rate is received, set the comprehensive performance index function F; It further includes S46: Define the calculation methods of each parameter: First, define ηtail gas methanol detection side combustion efficiency = (LHV _in - LHV_ out ) / LHV _in ; Among them, LHV _in is the lower heating value of methanol entering the combustion chamber, and LHV _out is the lower heating value of unburned methanol in the exhaust gas; Then define the equivalence ratio φ: Equivalence ratio φ = (m fuel / m oxygen ) / (m fuel / m oxygen ) stoichiometric ; Where: φ represents the equivalence ratio; m fuel represents the fuel mass; m oxygen represents the oxygen mass; (m fuel / m oxygen ) stoichiometric : represents the theoretical stoichiometry; Then directly obtain the actual combustion chamber temperature T and the actual nitrogen oxide emissions NOx(t); obtain the optimal combustion chamber temperature T opt and the maximum allowable combustion chamber temperature Tmax and the target nitrogen oxide emissions NOx target Obtain the reference fuel consumption rate, and then calculate the fuel consumption rate FC: FC = m fuel / Power output ; Among them, FC represents the fuel consumption rate; m fuel represents the fuel mass; Power output represents the engine output power; Calculate the exhaust gas recirculation rate EGR: EGR = m_recirculated / m_total_intake; Among them, EGR represents the exhaust gas recirculation rate; m_recirculated represents the mass of the recirculated exhaust gas; m_total_intake represents the total intake air mass; Obtain the specific values of the matching weight coefficients w1 - w6, substitute all the parameters into the formula for the comprehensive performance index function F, and calculate the value of F under the current working condition; S46. Optimize EGR to solve for the maximum output of the comprehensive performance index F: First, obtain the search range and step size for defining EGR; EGRmin = x1%, EGRmax = x2%, step size ΔEGR = n%; Optimize EGR using the gradient descent method based on the above EGRmin, EGRmax, and ΔEGR. During the specific optimization, obtain the set learning rate learning_rate, maximum number of iterations max_iterations, and tolerance tolerance to iteratively update the EGR value; In each iteration, calculate the gradient of the maximized comprehensive performance index F with respect to EGR, update the EGR value, and check if the termination condition is met. At the same time, during this process, the EGR value will be iteratively adjusted until a local maximum is found and recorded as the optimal EGR value; Take the optimal EGR value as the target value and adjust the valve opening to achieve this optimal target value.

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