Diesel oil ignition methanol dual-fuel engine exhaust reforming and combustion system and control method

Abstract

The invention relates to an exhaust reforming and combustion system of a diesel ignition methanol dual-fuel engine and a control method. The system comprises an exhaust reforming device, a combustion device and a diesel ignition methanol dual-fuel engine, wherein the exhaust reforming device is used for carrying out catalytic reforming on unburned methanol in exhaust; a reformed gas circulation branch flow regulating valve; the gas cylinder is connected with the valve; the reforming gas inlet channel injection common rail and the reforming cylinder internal direct injection common rail are respectively connected with the gas storage cylinder; the reformed gas inlet channel nozzle is connected with the gas inlet channel common rail; the in-cylinder direct injection gas auxiliary nozzle is simultaneously connected with the methanol in-cylinder direct injection common rail and the reformed gas direct injection common rail; a cylinder pressure sensor for monitoring a cylinder pressure; the first methanol and hydrogen sensor is used for monitoring reformed gas components; and an ECU. Compared with the prior art, stable control over the hydrogen-alcohol ratio of the reformed gas and intelligent optimization of the in-cylinder combustion state can be achieved, and the problem that high-ratio methanol combustion is unstable is solved.

Description

Technical Field

[0001] This invention relates to the field of methanol engine technology, and in particular to an exhaust gas reforming and combustion system and control method for a diesel-ignited methanol dual-fuel engine. Background Technology

[0002] In existing solutions, methanol engines cannot achieve independent auto-ignition under extreme operating conditions, especially in cold regions. Therefore, it is usually necessary to introduce traditional fossil fuels, such as diesel, for ignition. Under the guidance of the dual-carbon policy, the demand for high methanol substitution rates has led to engine misfires, cycle fluctuations, and abnormal pollutant emissions.

[0003] Currently, existing solutions enhance engine combustion by reforming the exhaust gas, catalytically converting unburned methanol into hydrogen, and then reinjecting it into the cylinder. For high-substitution-rate methanol-diesel dual-fuel engines, the exhaust contains a significant amount of unburned methanol. A portion of the reformed gas is injected into the intake manifold via EGR to create a uniform, trace hydrogen atmosphere, enhancing methanol ignition. On the other hand, the trace hydrogen not introduced into the reformed gas can also act as an additional reducing agent to enhance NOx control in SCR (Selective Catalytic Reduction).

[0004] Patent application CN201810933593.5 discloses a combustion organization method for a methanol / hydrogen-ethanol fuel internal combustion engine and its application. It utilizes waste heat from exhaust gas for online catalytic reforming or cracking of a portion of methanol fuel to produce hydrogen-ethanol, the main component of which is hydrogen. A portion of the produced hydrogen-ethanol is supplied to the ignition chamber to form a hydrogen-rich mixture, which is then ignited by a spark plug, forming a high-energy turbulent flame jet ignition source. This ignites the homogeneous lean mixture of methanol and hydrogen-ethanol injected into the cylinder from the intake manifold or cylinder. The flame front formed by the proposed jet flame upon entering the main combustion chamber is quenched upon encountering the cold cylinder wall, preventing the cold mixture near the cylinder wall from igniting and causing it to be directly discharged.

[0005] Patent application CN202110301045.2 discloses a control method for controllable reforming of fuel in an engine cylinder. The steps are as follows: dividing a multi-cylinder engine into two working cylinders and one reforming cylinder; the ECU determines the engine operating load; under low load conditions, partial fuel reforming is required, and a three-way valve is controlled to give the reforming cylinder a separate intake and exhaust pipe, using engine exhaust gas to preheat the intake air of the reforming cylinder; the fuel injector in the intake manifold of the reforming cylinder is controlled to work independently; the opening of the intake throttle valve and the power of the electric heater in the reforming cylinder are controlled to form a rich premixed air-fuel mixture with a fixed equivalence ratio in the reforming cylinder; under high load and full load conditions, the three-way valve is controlled to switch the reforming cylinder to the same normal operating mode as the working cylinder. However, the proposed premixed concentration is a uniform concentration throughout the cylinder, which wastes some reformed fuel far from the nozzle under conditions requiring strong ignition.

[0006] Patent application CN202211462356.8 discloses a hybrid power system and method based on two-stage fuel reforming in a cylinder-type internal combustion engine. In this system, the fuel first undergoes a first-stage compression in a low-pressure cylinder. The high temperature and pressure at the end of the compression cause the fuel to reform, with some fuel decomposing into ammonia and hydrogen. In the second-stage reforming, the unreformed ammonia further decomposes under thermocatalytic conditions and enters the high-pressure cylinder for a second-stage compression, effectively increasing the engine's intake pressure, improving the average pressure during operation, and enhancing the engine's thermal efficiency. Although reforming utilizes unburned fuel from the engine, the input conditions of the engine in the second stage are unstable, increasing the possibility of abnormal combustion.

[0007] Existing solutions cannot flexibly promote methanol combustion with reformed gas. Due to the limited efficiency of reforming units and the complex operating conditions of high-proportion methanol diesel engines, it is impossible to guarantee that the active substances in the reformed gas are consistent with those under calibration conditions. Using a simple EGR cycle can easily lead to engine cycle instability. At the same time, injecting reformed gas into the intake manifold requires mixing with a large amount of fresh air, necessitating a stable supply of reformed gas from the EGR. When the hydrogen-to-methanol ratio in the exhaust is unbalanced, it will lose its ignition effect or even inhibit combustion. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects of the prior art by providing an exhaust reforming and combustion system and control method for a diesel-ignited methanol dual-fuel engine, which can effectively treat unburned methanol fuel, while taking into account the ignition requirements of internal combustion engines under different operating conditions and improving the methanol combustion organization.

[0009] The objective of this invention can be achieved through the following technical solutions: The first aspect of this invention provides an exhaust reforming and combustion system for a diesel-ignited methanol dual-fuel engine, comprising: an exhaust reforming device, a reforming gas recirculation branch flow regulating valve, a gas receiver, a reforming gas intake manifold injection common rail and a reforming gas direct injection common rail, a reforming gas intake manifold nozzle, a methanol direct injection common rail, a direct injection gas auxiliary nozzle, a cylinder pressure sensor, a first methanol and hydrogen sensor, and an ECU, wherein specifically: An exhaust reforming device, located on the engine exhaust pipe, is used to catalytically reform unburned methanol in the exhaust gas. A flow regulating valve for the reforming gas circulation branch is located on the downstream exhaust pipe of the exhaust reforming device; The gas storage cylinder is connected to the exhaust pipe via the flow regulating valve of the reformer gas circulation branch; The reformer intake manifold injection common rail and the reformer cylinder direct injection common rail are respectively connected to the gas storage cylinder; A reforming gas intake nozzle is connected to the reforming gas intake common rail and is used to inject reforming gas into the engine intake manifold. Methanol direct injection common rail system; The in-cylinder direct injection gas auxiliary nozzle is connected to both the methanol in-cylinder direct injection common rail and the reforming gas in-cylinder direct injection common rail. The cylinder pressure sensor is installed on the engine cylinder head and is used to detect the pressure inside the cylinder. The first methanol and hydrogen sensor is installed on the exhaust pipe between the exhaust reforming device and the flow regulating valve of the reforming gas circulation branch; The ECU has its signal input terminal electrically connected to the cylinder pressure sensor and the first methanol and hydrogen sensors, and its signal control output terminal electrically connected to the reforming gas circulation branch flow regulating valve, the reforming gas intake nozzle, and the in-cylinder direct injection gas auxiliary nozzle.

[0010] Furthermore, the gas storage cylinder is equipped with a second methanol and hydrogen sensor for monitoring the composition of the reformed gas inside. The gas storage cylinder is also equipped with a reforming gas pressure sensor for monitoring its internal pressure. The second methanol and hydrogen sensor and the reforming gas pressure sensor are both electrically connected to the ECU to provide a gas storage cylinder status feedback signal for regulating the flow control valve of the reforming gas circulation branch.

[0011] Furthermore, it also includes a diesel direct injection common rail and a diesel direct injection nozzle connected to the diesel direct injection common rail. The diesel direct injection nozzle is connected to the ECU and is used to inject diesel into the cylinder as the main ignition source. The reformed gas introduced by the reforming gas intake nozzle and the direct injection gas auxiliary nozzle serves as an auxiliary ignition and combustion promoting medium.

[0012] A second aspect of the present invention provides a method for exhaust gas reforming and combustion control in a diesel-ignited methanol dual-fuel engine, comprising the following steps: The exhaust gas of the engine is catalytically reformed by an exhaust reforming device to produce reformed gas. A portion of the reformed gas is introduced into the gas storage cylinder through the reformed gas circulation branch flow regulating valve, and the flow regulating valve is adjusted based on the real-time exhaust composition data obtained by the methanol and hydrogen sensors to control the hydrogen-methanol ratio of the reformed gas in the gas storage cylinder. The reformed gas in the gas storage tank is introduced into the engine cylinder in two ways: part of it is injected into the engine intake manifold through the reformed gas intake manifold nozzle, and the other part is injected into the cylinder in conjunction with methanol from the methanol direct injection in the cylinder through the cylinder direct injection gas auxiliary nozzle. The cylinder pressure curve of the engine is acquired in real time by a cylinder pressure sensor. The cylinder pressure curve is compared with the calibrated cylinder pressure curve under the current operating conditions to determine the combustion state. When the cylinder pressure curve is lower than the calibrated curve, the amount of reformed gas injected into the cylinder direct injection auxiliary nozzle is increased through the reformed gas common rail injection. When the cylinder pressure curve is higher than the calibrated curve, part of the reformed gas is transferred from the cylinder direct injection to the reformed gas intake manifold nozzle through the reformed gas intake manifold injection common rail injection. Based on whether the methanol concentration in the exhaust gas detected by the first methanol and hydrogen sensor exceeds a preset threshold, it is determined whether to inject supplemental reforming gas during the exhaust combustion period of the engine expansion stroke.

[0013] Furthermore, the specific process of comparing the cylinder pressure curve with the calibrated cylinder pressure curve under the current operating condition to determine the combustion state includes: The ECU receives and processes the real-time cylinder pressure signal from the cylinder pressure sensor to generate a real-time cylinder pressure curve, and compares the real-time cylinder pressure curve with the calibrated cylinder pressure curve corresponding to the current engine speed and torque stored in the ECU's memory point by point, and calculates the average pressure deviation between the two in the combustion phase. When the average pressure deviation does not exceed the preset allowable error range, the in-cylinder combustion state is determined to be normal and the current reforming gas injection distribution strategy is maintained. When the average pressure deviation exceeds the allowable error range, the overall trend of the real-time cylinder pressure curve is further analyzed. If the measured pressure value is consistently lower than the calibrated cylinder pressure curve throughout the main combustion stage, it is determined to be a combustion suppression state, and an adjustment command to increase the amount of in-cylinder direct injection reforming gas is triggered. If the measured pressure value is consistently higher than the calibration curve, it is determined to be a rough combustion state, and an adjustment command is triggered to transfer the reformed gas from the direct injection section to the intake manifold injection.

[0014] Furthermore, the specific process of controlling the hydrogen alcohol ratio of the reformed gas in the gas storage cylinder includes: The specific process of controlling the hydrogen-ethanol ratio of the reformed gas in the gas storage cylinder includes: the ECU first determines the initial opening angle Q1 of the reformed gas circulation branch flow regulating valve by looking up a table according to the engine operating conditions; Then, the following monitoring and adjustment steps are executed repeatedly: Read the data from the first methanol and hydrogen sensor installed on the exhaust pipe to determine whether the hydrogen concentration in the exhaust is lower than the minimum threshold S2 required to ensure the normal operation of the reformer. If it is lower, immediately close the flow regulating valve of the reformer circulation branch to stop the introduction of exhaust that may dilute hydrogen. Read the data from the reforming gas pressure sensor installed on the gas cylinder to determine whether the pressure of the gas cylinder exceeds the safety limit S3. If it does, close the flow regulating valve of the reforming gas circulation branch. The data from the second methanol and hydrogen sensor installed on the gas storage cylinder is read to obtain the real-time methanol-hydrogen ratio S4 in the gas storage cylinder, and it is compared with the preset reasonable lower limit S5 and upper limit S6 of the methanol-hydrogen ratio. Based on the relationship between S4 and S5 and S6, combined with the value of the exhaust methanol-hydrogen ratio S1, the opening angle of the reforming gas circulation branch flow regulating valve is dynamically adjusted through preset decision logic to maintain S4 within the target range of S5 to S6.

[0015] Furthermore, under low-temperature cold start conditions, the starting control strategy executed by the ECU includes: After detecting the start signal, it determines the cold start mode based on the coolant temperature or intake air temperature; In cold start mode, the operation of the reforming gas intake nozzle is temporarily stopped, and all the reforming gas that can be supplied in the gas storage bottle is concentrated and distributed to the reforming gas cylinder direct injection common rail by controlling the distribution valve on the reforming gas intake injection common rail and the reforming gas cylinder direct injection common rail. When a methanol injection event is triggered, the ECU controls the in-cylinder direct injection gas auxiliary nozzle to start the auxiliary injection of reforming gas at the start of methanol injection or within a predetermined crankshaft angle interval before the start of methanol injection. The pressure of the auxiliary injection is set to be higher than the reforming gas injection reference pressure under normal operating conditions. As a result, the high-pressure reforming gas jet injected into the cylinder interacts violently with the methanol spray, and the resulting strong turbulence effectively promotes the secondary breakup and accelerated evaporation of methanol droplets, and forms a local high-concentration, high-activity reforming gas-methanol mixture core area in the initial development region of the methanol spray. The core area utilizes highly reactive components such as hydrogen in the reformed gas to significantly reduce the ignition threshold of the mixed gas, thereby greatly shortening the actual ignition delay period of methanol in low-temperature environments and ensuring stable and reliable first-time ignition success during cold starts. Once the engine has successfully started and is running stably, and the cylinder pressure or calculated cylinder temperature fed back by the cylinder pressure sensor reaches the preset exit threshold, the ECU automatically switches the reformer injection control mode back to the collaborative control mode based on real-time comparison and feedback of cylinder pressure curves as described in claim 4.

[0016] Furthermore, under high engine load conditions, when the combustion is determined to be rough based on cylinder pressure curve comparison, the ECU executes a combustion mitigation strategy. The specific process of this strategy is as follows: While maintaining the total reformed gas supply mass flow rate set under the current operating conditions at a basically constant level, the flow control devices upstream or downstream of the reformed gas inlet injection common rail and the reformed gas in-cylinder direct injection common rail are adjusted to gradually reduce the amount of reformed gas injected through the reformed gas in-cylinder direct injection common rail to the auxiliary nozzle of the in-cylinder direct injection gas. At the same time, the amount of reformed gas injected through the reformed gas inlet injection common rail to the reformed gas inlet nozzle is increased proportionally. This adjustment aims to physically reduce the local reformed gas concentration directly surrounding the methanol spray jet and the turbulence intensity it introduces, thereby weakening the reaction rate in the initial stage of combustion and mitigating the pressure rise rate. However, the equal amount of reformed gas introduced through the intake can still form a uniform lean active atmosphere throughout the cylinder, continuing to provide assistance for subsequent combustion. This suppresses rough combustion while avoiding misfires or cycle fluctuations that may be caused by a sudden reduction in the active working fluid.

[0017] Furthermore, the specific process of determining whether to supplement the injection of reforming gas during the tail combustion period based on whether the methanol concentration in the exhaust gas detected by the first methanol and hydrogen sensor exceeds a preset threshold includes: The ECU continuously monitors the methanol concentration value in the exhaust gas fed back by the first methanol and hydrogen sensors and compares it with a dynamic threshold calibrated according to the current engine load and speed. When the methanol concentration value exceeds the dynamic threshold, it indicates that the combustion in the cylinder may be incomplete due to the drop in temperature and pressure at the end of the expansion stroke. At this time, the ECU will control the direct injection gas auxiliary nozzle or the reforming gas intake port nozzle to perform one or more short injections of reforming gas during the tail combustion stage of the current combustion cycle, that is, within a certain crankshaft angle range after the piston reaches top dead center. The supplemented reformed gas rapidly participates in the reaction in the high-temperature cylinder environment. Its highly active components, such as hydrogen, can effectively promote the oxidation of residual unburned methanol, achieving synergistic control of in-situ reduction of unburned hydrocarbon emissions within the cylinder and reducing the burden on the aftertreatment unit.

[0018] Furthermore, exhaust reforming and combustion control methods also include the following processes: The ECU continuously acquires and processes cylinder pressure signals from the cylinder pressure sensor, exhaust composition signals from the first methanol and hydrogen sensor, and gas reservoir status signals from the second methanol and hydrogen sensor and the reformer pressure sensor. Based on the cylinder pressure signal, the ECU compares and analyzes to diagnose the combustion stability in the cylinder in real time, and generates corresponding reforming gas injection quantity distribution adjustment commands to directly drive the in-cylinder direct injection gas auxiliary nozzle and the reforming gas intake port nozzle to work. Meanwhile, based on the exhaust component signal and the gas storage cylinder status signal, the ECU assesses the quality and storage safety of the reforming gas feedstock, and dynamically controls the opening of the reforming gas circulation branch flow control valve by generating flow control commands to maintain the reforming gas hydrogen alcohol ratio and pressure in the gas storage cylinder within the target range. For supplementary injection decisions during the tail combustion phase, the ECU independently generates and executes supplementary injection trigger commands based on the current operating parameters and the level of methanol concentration in the exhaust gas.

[0019] In terms of overall concept, the reformed gas recirculation and auxiliary combustion system proposed in this invention utilizes a gas-assisted nozzle to use a small amount of reformed gas to assist methanol direct injection into the cylinder, promoting methanol atomization and creating a locally rich mixed atmosphere in the spray area to assist methanol ignition, thus solving the problem of difficult methanol ignition under low temperature and low speed conditions. Simultaneously, since the amount of reformed gas consumed by direct injection into the cylinder is much smaller than that of intake manifold injection, the reformed gas concentration can be adjusted via a gas storage tank. Concentration adjustment can be achieved through pollutant monitoring and coordination with the flow valve of the reformed gas recirculation branch. Furthermore, the engine operating status can be monitored in real time through pollutant sensors and cylinder pressure sensors. Combustion and in-cylinder pollutant control can be achieved through the coordinated regulation of reformed gas from direct injection into the cylinder and intake manifold injection, enabling efficient and stable operation of a high-proportion methanol engine. The entire system considers both the coordinated organization of in-cylinder reformed gas and the intelligent regulation of the reformed gas recirculation system, overcoming the shortcomings of existing patents in ignition and pollutant control under certain operating conditions.

[0020] In terms of overall concept, this invention uses a reformer connected to the upstream end of the exhaust pipe to reform the engine exhaust gas. A portion of the reformed gas is introduced into the gas reservoir through a reformed gas recirculation branch flow valve. The reformed gas recirculation branch flow valve is controlled by the ECU and can adjust the hydrogen-methanol ratio in the gas reservoir based on real-time exhaust component data and preset strategies. The reformed gas can enter the cylinder through intake manifold injection and direct auxiliary injection into the cylinder. Through cylinder pressure monitoring and pollutant monitoring feedback, the overall methanol combustion situation can be judged in real time, and efficient and stable methanol combustion and synergistic control of pollutants can be achieved through reformed gas mass distribution and in-cylinder injection strategy.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1) Improve the utilization rate of reformed gas. By using a small amount of reformed gas through a gas-assisted nozzle, methanol atomization can be enhanced and a localized rich reformed gas atmosphere can be formed to assist in ignition, thus creating conditions for using gas storage cylinders to stabilize the active ratio of reformed gas. 2) Achieve intelligent control of reformed gas in the cylinder. By coordinating the control of reformed gas intake port injection and direct injection in the cylinder through calibrated operating conditions and real-time data acquisition, the system can achieve efficient and stable ignition of methanol and coordinated control of pollutants in the cylinder. 3) Maintain stable composition of reformed gas by intelligently controlling the ratio of hydrogen alcohol in reformed gas in the gas storage cylinder through real-time data acquisition and flow control valve of reformed gas circulation branch. 4) Intelligent control has safety redundancy, which can prevent damage to airtight parts from excessively high or low pressure in the gas cylinder. Attached Figure Description

[0022] Figure 1 A schematic diagram of the exhaust reforming and combustion system of a diesel-ignited methanol dual-fuel engine; In the diagram: 1-Exhaust gas reforming unit, 2-Aftertreatment unit, 3-Reformed gas circulation branch flow regulating valve, 4-Gas storage tank, 5-Reformed gas intake port injection common rail, 6-Reformed gas cylinder direct injection common rail, 7-Reformed gas intake port nozzle, 8-Diesel cylinder direct injection common rail, 9-Diesel cylinder direct injection nozzle, 10-Methanol cylinder direct injection common rail, 11-Cylinder direct injection gas auxiliary nozzle, 12-Exhaust turbine, 13-First methanol and hydrogen sensor, 14-Reformed gas pressure sensor, 15-Second methanol and hydrogen sensor, 16-Cylinder pressure sensor, 17-ECU; Figure 2 Flowchart of exhaust gas reforming and combustion control method for diesel-ignited methanol dual-fuel engine; Figure 3 Flowchart of the control strategy for the flow regulating valve in the reformer recirculation branch; Figure 4 This is a flowchart for the operation of the hydrogen alcohol ratio balance control in the reformer branch. Detailed Implementation

[0023] Overall, this invention addresses the issue of unburned methanol emissions during the operation of a diesel-ignited methanol dual-fuel engine. Through active reforming, the methanol is converted into a hydrogen-containing mixture, and then the in-cylinder combustion delay period is adjusted according to engine requirements by providing a lean / rich partial mixture atmosphere. This invention effectively handles unburned methanol fuel while also accommodating the ignition needs of internal combustion engines under different operating conditions, thus improving methanol combustion organization.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, circuit structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0025] Example 1 This embodiment provides an exhaust reforming and combustion system for a diesel-ignited methanol dual-fuel engine, including: an exhaust reforming device 1, a reforming gas recirculation branch flow regulating valve 3, a gas storage tank 4, a reforming gas intake manifold injection common rail 5 and a reforming gas direct injection common rail 6, a reforming gas intake manifold nozzle 7, a methanol direct injection common rail 10, a direct injection gas auxiliary nozzle 11, a cylinder pressure sensor 16, a first methanol and hydrogen sensor 13, and an ECU 17, wherein specific details can be found in the following description. Figure 1 .

[0026] An exhaust gas reforming device 1, installed on the engine exhaust pipe, is used for catalytic reforming of unburned methanol in the exhaust gas; a reformed gas recirculation branch flow regulating valve 3 is installed on the downstream exhaust pipe of the exhaust gas reforming device 1; a gas storage cylinder 4 is connected to the exhaust pipe through the reformed gas recirculation branch flow regulating valve 3; a reformed gas intake manifold injection common rail 5 and a reformed gas cylinder direct injection common rail 6 are respectively connected to the gas storage cylinder 4; a reformed gas intake manifold nozzle 7 is connected to the reformed gas intake manifold injection common rail 5 and is used to inject reformed gas into the engine intake manifold; a methanol cylinder direct injection common rail 10; and a cylinder direct injection gas auxiliary nozzle 11, simultaneously... The system is connected to the methanol direct injection common rail 10 and the reformed gas direct injection common rail 6; a cylinder pressure sensor 16 is installed on the engine cylinder head to detect the cylinder pressure; a first methanol and hydrogen sensor 13 is installed on the exhaust pipe between the exhaust reforming device 1 and the reformed gas recirculation branch flow regulating valve 3; an ECU 17 has its signal input terminal electrically connected to the cylinder pressure sensor 16 and the first methanol and hydrogen sensor 13, and its signal control output terminal electrically connected to the reformed gas recirculation branch flow regulating valve 3, the reformed gas intake nozzle 7, and the direct injection gas auxiliary nozzle 11.

[0027] In this embodiment, see Figure 1 An exhaust gas reforming unit 1 is installed upstream of the exhaust pipe to catalyze unburned methanol in the exhaust gas, forming reformed gas. Following the exhaust gas reforming unit 1 is the main exhaust pipe, which is connected in sequence to the aftertreatment unit 2. A reformed gas recirculation branch flow regulating valve 3 is installed between the exhaust gas reforming unit 1 and the aftertreatment unit 2 to control the introduction of reformed gas into the gas storage tank 4. The reformed gas recirculation branch flow regulating valve 3 is controlled by ECU 17.

[0028] After the air-fuel mixture enters the gas reservoir 4, it is redistributed by the ECU 17 and introduced into the reformed air intake manifold injection common rail 5 and the reformed air cylinder direct injection common rail 6.

[0029] In practice, the reformed gas intake duct injection common rail 5 injects reformed gas into the intake duct through the reformed gas intake duct nozzle 7, which mixes with fresh air to form a micro-reformed gas atmosphere intake.

[0030] In practice, diesel fuel is directly injected into the cylinder through the diesel in-cylinder direct injection common rail 8 and the diesel in-cylinder direct injection nozzle 9.

[0031] In practice, methanol is guided into the methanol direct injection auxiliary nozzle 11 via the methanol direct injection common rail 10. Reformed gas is guided into the methanol direct injection auxiliary nozzle 11 via the reformed gas direct injection common rail 6, assisting in methanol atomization at the nozzle orifice, weakening cavitation, and creating a richer reformed gas atmosphere in the fuel spray zone to accelerate methanol combustion. The reformed gas intake nozzle 7, diesel direct injection nozzle 9, and methanol direct injection auxiliary nozzle 11 are connected to the ECU 17. The ECU 17 controls the injection quantities of diesel, methanol, and reformed gas.

[0032] In practice, engine exhaust gas passes through exhaust turbine 12 and enters exhaust gas reforming unit 1 for catalytic reforming. Exhaust gas that does not enter the recirculation branch passes through aftertreatment unit 2 and is then discharged into the system.

[0033] In practice, the first methanol and hydrogen sensor 13 (including methanol sensor (YP-FS6) and hydrogen sensor (FH2-HY04)) is placed between the aftertreatment device 2 and the reformer gas recirculation branch flow regulating valve 3 to monitor the pollutant emission level and feed back data to the ECU 17 to assist in judging the in-cylinder combustion environment.

[0034] In practice, the reformer pressure sensor 14 is installed on the gas cylinder 4 to monitor the pressure of the gas cylinder and report it to the ECU 17 to avoid excessive pressure causing driving safety hazards.

[0035] In practice, the second methanol and hydrogen sensor 15 (including methanol sensor (YP-FS6) and hydrogen sensor (FH2-HY04)) is installed on the gas storage bottle 4 to monitor the proportion of substances in the gas storage bottle and feed it back to the ECU 17, so as to avoid excessive methanol injection into the cylinder and inhibit combustion.

[0036] In practice, the ECU17 can control the injection mode of the reforming gas based on feedback from the operating conditions, the first methanol and hydrogen sensor 13, the reforming gas pressure sensor 14, and the second methanol and hydrogen sensor 15.

[0037] In practice, the cylinder pressure sensor 16 is installed inside the engine cylinder to monitor the engine cylinder pressure in real time and is connected to the ECU 17.

[0038] Figure 2 This is a schematic flowchart of a diesel-ignited methanol engine exhaust reforming and combustion organization control method provided in an embodiment of the present invention. Figure 2 As shown, the method includes the following steps: S100: Determine the preset injection strategy for reformer gas injection. The injection parameters for the reformed gas include the intake manifold reformed gas injection quantity, the opening / closing phase angle of the intake manifold reformed gas injector 7, the reformed gas injection quantity of the in-cylinder direct injection auxiliary nozzle 11, and the opening / closing phase angle of the in-cylinder direct injection auxiliary nozzle 11. It can be understood that the nozzle opening and closing phase angles determine the reformed gas injection duration, and the reformed gas injection pressure can be determined based on the reformed gas injection quantity and injection duration.

[0039] Specifically, the memory pre-stores a first correspondence between injection parameters and engine operating conditions. The injection parameters of the reformed gas can be determined based on the engine operating conditions and this first correspondence. This first correspondence can be obtained through prior experiments.

[0040] S1001: Obtain engine speed and torque.

[0041] Engine speed can be detected by a speed sensor, and engine torque can be detected by a torque sensor.

[0042] S1002: Engine operating conditions are obtained based on engine speed and torque. Specifically, the memory stores a second correspondence between engine speed, torque, and engine operating conditions. The ECU17 can obtain the corresponding engine operating conditions in real time based on the actual speed, torque, and the second correspondence. The second correspondence can be determined based on previous experiments.

[0043] Through step S1002, the real-time operating condition of the engine can be obtained. Based on the real-time operating condition and the first correspondence, ECU17 controls the gas reservoir to provide a preset amount of reformed gas to the reformed gas intake manifold injection common rail 5 and the reformed gas direct injection common rail 6. ECU17 controls the intake manifold reformed gas nozzle 7 and the in-cylinder gas auxiliary nozzle 11 to execute opening / closing commands at a preset crankshaft angle.

[0044] S110: Adjust the initial opening angle Q1 of the reforming gas recirculation branch flow regulating valve 3 according to engine operating conditions. Specifically, the memory pre-stores a third correspondence between the engine operating conditions and the opening angle of the reformer recirculation branch flow regulating valve 3. Based on the acquired engine operating conditions, the initial opening angle Q1 of the reformer recirculation branch flow regulating valve 3 can be determined. This third correspondence can be determined based on previous experiments.

[0045] Among them, the reforming efficiency of exhaust gas reformer 1 is limited. When the ratio of hydrogen to unburned methanol in the exhaust gas exceeds the threshold S1, the ignition effect of the reformed gas will be weakened. Therefore, it is necessary to adjust Q1 to reduce or even stop the gas cylinder intake to keep the ratio of hydrogen supplied from gas storage cylinder 4 to the nozzle within a safe range. The threshold S1 was determined by previous experiments.

[0046] Please refer to Figure 3 In step S110, the initial opening angle of the reforming gas circulation branch flow regulating valve 3 is Q1, and the adjusted angle is Q2. The following opening angle adjustment steps are performed: S1101: Reformer Operation Monitoring Specifically, the exhaust hydrogen concentration is compared with the lower limit of the hydrogen threshold S2, where S2 is the minimum hydrogen content in the exhaust. If yes, the exhaust reformer 1 is working normally and the engine is running normally, and step S1102 is executed; if no, the unburned methanol emission is low under this condition or the exhaust reformer 1 is not working properly. Continuing to introduce exhaust into the gas storage tank 4 will dilute the hydrogen concentration and reduce the ignition effect of the reformed gas, so the flow regulating valve 3 of the reformed gas circulation branch is closed.

[0047] S1102: Detect the pressure of gas cylinder 4 Specifically, the pressure of gas cylinder 4 is compared with the safe pressure threshold S3, where S3 is the upper limit of the safe pressure of gas cylinder 4. If yes, gas cylinder 4 is operating normally, and step S1103 is executed; otherwise, gas cylinder 4 has reached the safe critical value for storing reformed gas, so the flow regulating valve 3 of the reformed gas circulation branch is closed.

[0048] S1103: Detecting the balance of 4-hydrogen alcohol ratio in gas storage cylinders Specifically, it is determined whether the hydrogen alcohol ratio in gas cylinder 4 is between the pre-stored lower limit S5 and the pre-stored upper limit S6 of the hydrogen alcohol ratio in the storage tank. If yes, the hydrogen alcohol ratio in the gas cylinder is normal, and step S1104 is executed; if no, the hydrogen alcohol ratio balancing operation in the gas cylinder is executed. The pre-stored lower limit S5 and upper limit S6 of the hydrogen alcohol ratio in the storage tank are obtained through previous experiments.

[0049] In practice, the hydrogen alcohol balance operation is performed based on a combination of the exhaust hydrogen alcohol ratio S1, the storage cylinder hydrogen alcohol ratio S4, and the storage cylinder pressure. The execution process is as follows: Figure 4 As shown, the execution steps are as follows: S110301: Determination of the 4-hydrogen alcohol ratio in gas storage cylinders Specifically, this step involves determining whether the 4-hydrogen alcohol ratio in the gas storage cylinder is less than the lower limit S5. If yes, it indicates that the 4-hydrogen alcohol ratio in the gas storage cylinder is too low, and step S110302 is executed; if no, it indicates that the 4-hydrogen alcohol ratio in the gas storage cylinder is greater than the upper limit S6, and step S110301A is executed.

[0050] S110301A: Determination of Exhaust Hydrogen-Methanol Ratio Specifically, it is determined whether the exhaust hydrogen-to-ethanol ratio is within the range of the lower limit S5 and the upper limit S6. If so, the hydrogen-to-ethanol ratio in the gas storage cylinder 4 is adjusted by introducing more fresh exhaust gas, and the initial opening angle Q1 to Q2 of the reformer gas circulation branch flow control valve is increased. Otherwise, the hydrogen-to-ethanol ratio needs to be further assessed, and step S110301B is executed. The increased angle is obtained based on the empirical formula from previous experiments.

[0051] S110301B: Safety Pressure Detection of Gas Storage Cylinder 4 Specifically, comparing the pressure in gas cylinder 4 with the lower pressure safety limit S7 aims to prevent excessively low pressure in gas cylinder 4 from damaging the airtight device and affecting the supply of reformed gas. If the pressure exceeds the lower pressure safety limit S7, it indicates that the reformed gas in the gas cylinder is sufficient, requiring further assessment of the exhaust hydrogen-ethanol ratio and proportional adjustment, executing operation S110301C; otherwise, it indicates that the gas in gas cylinder 4 is insufficient, requiring timely replenishment, executing the minimum reformed gas replenishment operation. The lower pressure safety limit S7 was obtained through previous experiments.

[0052] In practice, the minimum replenishment of reforming gas refers to adjusting the opening angle Q1 of the reforming gas circulation branch flow regulating valve 3 to the minimum flow angle Q3. Q3 is the value that precisely meets the injection reforming gas flow requirement under this operating condition, obtained from previous experiments.

[0053] S110301C: Exhaust alcohol-to-hydrogen ratio S1 detection Specifically, determine whether the exhaust hydrogen-to-ethanol ratio S1 is less than the lower limit S5. If so, it indicates a low exhaust hydrogen-to-ethanol ratio, which can dilute the hydrogen concentration under the condition of an excessively high hydrogen-to-ethanol ratio in gas cylinder 4. In this case, the initial opening angle Q1 to Q2 of the reformer gas circulation branch flow regulating valve is increased. Otherwise, it is necessary to further determine the exhaust hydrogen-to-ethanol ratio and the hydrogen-to-ethanol ratio in gas cylinder 4 to determine whether the introduced exhaust gas has a dilution effect. The increased angle is obtained based on the empirical formula from previous experiments.

[0054] S110301D: Comparison of exhaust hydrogen alcohol ratio S1 and storage cylinder 4 hydrogen alcohol ratio S4 Specifically, determine whether the exhaust hydrogen-to-ethanol ratio S1 is greater than the hydrogen-to-ethanol ratio S4 in gas storage cylinder 4. If so, it indicates that the exhaust hydrogen-to-ethanol ratio is too high and has no regulating effect on the hydrogen-to-ethanol ratio in gas storage cylinder 4, in which case the flow regulating valve 3 of the reformer circulation branch is closed; otherwise, it indicates that the exhaust helps dilute the mixture in gas storage cylinder 4, in which case the initial opening angle Q1 to Q2 of the flow regulating valve of the reformer circulation branch is increased. The increased angle is obtained based on the empirical formula from previous experiments.

[0055] S110302: Determine whether the exhaust hydrogen alcohol ratio is within the normal range. Specifically, it is determined whether the exhaust hydrogen-to-methanol ratio S1 is within the range of the lower limit S5 and the hydrogen-to-methanol ratio S6. If it is, then charging in fresh exhaust gas helps to regulate the ignition effect of the mixture in the gas storage cylinder 4, and the initial opening angle Q1 to Q2 of the reformer circulation branch flow regulating valve is increased; if not, step S110302A is executed to further perform the pressure safety test of the gas storage cylinder 4. The increased angle is obtained based on the empirical formula from previous experiments.

[0056] S110302A: Safety Pressure Detection of Gas Storage Cylinder 4 Specifically, comparing the pressure in gas cylinder 4 with the lower pressure safety limit S7 aims to prevent excessively low pressure in gas cylinder 4 from damaging the airtight device and affecting the supply of reformate gas. If the pressure exceeds the lower pressure safety limit S7, it indicates that the reformate gas in the gas cylinder is sufficient, requiring further assessment of the exhaust hydrogen-ethanol ratio and proportional adjustment, executing operation S110302C; if the pressure is below the lower pressure safety limit S7, it indicates that the storage in gas cylinder 4 is insufficient, requiring timely replenishment, executing the minimum reformate gas replenishment operation. The lower pressure safety limit S7 was obtained through previous experiments.

[0057] In practice, the minimum replenishment of reforming gas refers to adjusting the opening angle Q1 of the reforming gas circulation branch flow regulating valve 3 to the minimum flow angle Q3. Q3 is the value that precisely meets the injection reforming gas flow requirement under this operating condition, obtained from previous experiments.

[0058] S110302B: Exhaust hydrogen alcohol ratio S1 detection Specifically, determine whether the exhaust hydrogen-to-ethanol ratio S1 is greater than the upper limit of the hydrogen-to-ethanol ratio S6. If so, it means that introducing fresh exhaust gas can increase the hydrogen-to-ethanol ratio of the reformed gas in the gas storage cylinder 4, and execute the step of expanding the initial opening angle Q1 to Q2 of the reformed gas circulation branch flow regulating valve; otherwise, further judgment is required, and step S110302C is executed. The expansion angle is obtained based on the empirical formula from previous experiments.

[0059] S110302C: Comparison of exhaust hydrogen alcohol ratio S1 and storage cylinder 4 hydrogen alcohol ratio S4 Specifically, determine whether the hydrogen-to-ethanol ratio S1 is greater than the hydrogen-to-ethanol ratio in the storage cylinder 4. If so, introducing fresh exhaust gas can increase the hydrogen-to-ethanol ratio in the storage cylinder 4, and the initial opening angle Q1 to Q2 of the reformer recirculation branch flow regulating valve is increased; otherwise, introducing fresh exhaust gas will further dilute the hydrogen and suppress the ignition effect, and the reformer recirculation branch flow regulating valve 3 is closed. The increased angle is obtained based on the empirical formula from previous experiments.

[0060] S1104: Monitor the exhaust hydrogen-to-methanol ratio S1, and change the opening angle Q1 of the reformer recirculation branch flow regulating valve 3. Specifically, it is determined whether the exhaust alcohol-to-hydrogen ratio S1 is within the range of the pre-stored lower limit S5 and the hydrogen-to-ethanol ratio S6 in the storage tank, in order to determine whether the fresh reformed gas will cause an imbalance in the hydrogen-to-ethanol ratio in the gas storage cylinder 4. If so, the initial opening angle Q1 of the reformed gas circulation branch flow regulating valve 3 remains unchanged; otherwise, a pressure safety test is performed on the gas storage cylinder 4, and step S1105 is executed.

[0061] S1105: Safety Pressure Test of Gas Cylinder 4 Specifically, determine whether the safety pressure of gas cylinder 4 is greater than the lower safety limit S7. If yes, the reformed gas storage in gas cylinder 4 is sufficient, and there is no need to introduce fresh exhaust gas to affect the hydrogen-to-ethanol ratio in gas cylinder 4. Then, close the reformed gas circulation branch flow regulating valve 3. If no, the storage in gas cylinder 4 is insufficient. Adjust the opening angle Q1 of the reformed gas circulation branch flow regulating valve 3 to the minimum flow angle Q3 to prevent the gas pressure in gas cylinder 4 from becoming too low. Here, Q3 is the value that just meets the injection reformed gas flow requirement under this operating condition, obtained from previous experiments.

[0062] S120: Cylinder pressure curve determines in-cylinder combustion status. Specifically, determine whether the error between the cylinder pressure curve and the operating condition calibration curve is less than 10%. If yes, it indicates that the engine is operating normally, and proceed to step S130; otherwise, it is necessary to further determine the engine operating status through cylinder pressure, and proceed to step S1201. The operating condition calibration curve is stored in the memory and obtained from previous experiments.

[0063] S1201: Cylinder pressure curve determines the intensity of in-cylinder combustion. Specifically, determine if the cylinder pressure curve is generally lower than the calibration curve. If so, it indicates that in-cylinder combustion is suppressed. Increase the reformed gas supply to the common rail injection system 6, injecting more reformed gas into the cylinder. On one hand, more reformed gas creates more intense turbulence, enhancing the initial atomization and breakup of methanol. On the other hand, more reformed gas will surround the methanol spray, creating a richer reformed gas atmosphere within the spray area, shortening the methanol ignition delay period. Otherwise, it indicates that in-cylinder combustion is too aggressive. Move some of the reformed gas input to the common rail injection system 6 to the common rail injection system 5 in the reformed gas intake duct, injecting it into the cylinder through the reformed gas intake nozzle 7. This is to prevent a sudden reduction in reformed gas concentration from excessively reducing methanol ignition. By reducing in-cylinder direct injection, methanol atomization is weakened, and the reformed gas atmosphere within the spray jet is diluted, thus mitigating the aggressive combustion of methanol.

[0064] This embodiment provides two specific application scenarios for step S1201: When starting a car in northern winters, the low ambient temperature and low engine intake air temperature pose a serious challenge to methanol injection atomization and ignition, leading to starting difficulties and the emission of large amounts of unburned methanol. Traditional reformed air recirculation systems will actively shut down when the methanol content in the exhaust exceeds the reformer's operating limit. As the driver starts the car and pushes the engine to high load conditions, such as on highways, the engine cylinder temperature remains stable at a high temperature, resulting in rough combustion. Traditional reformed air recirculation systems switch the EGR on and off repeatedly to stabilize methanol combustion, but the unstable content of reformed air in the cylinder causes unstable engine operation. Starting conditions: When the car starts, the system automatically distributes all reformed air to the auxiliary nozzles in the cylinder to ensure stable methanol ignition at extremely low temperatures. This strategy enhances methanol fragmentation, atomization, and evaporation through strong turbulence, and creates a rich, active atmosphere in the spray area to promote methanol combustion, overcoming the challenge of low-temperature starting.

[0065] High-load conditions: When the vehicle operates under high-speed or high-torque conditions, the system judges the degree of combustion intensity based on real-time monitoring of the in-cylinder pressure. If signs of rough combustion are detected, the reformed gas will be redistributed according to a predetermined plan, injecting more gas into the intake manifold instead of the in-cylinder gas auxiliary nozzle. This strategy can maintain a consistent working fluid in the in-cylinder reformed gas, reduce the turbulence intensity and local reactive atmosphere concentration around the methanol spray, and ensure that combustion gradually stabilizes, rather than directly reducing the amount of reformed gas injected, which could lead to engine instability.

[0066] S130: Exhaust Methanol Ratio Detection Specifically, determine whether the methanol ratio is below the threshold. If so, it indicates that the methanol in the cylinder is completely oxidized and no abnormal combustion has occurred, and the original strategy is maintained; otherwise, the reaction intensity at the end of the methanol oxidation in the cylinder is insufficient, and there is excessive methanol. In this case, inject reformate again during the tail combustion period to enhance methanol oxidation during the tail combustion period and achieve coordinated control of unburned methanol inside and outside the cylinder.

[0067] This application provides a specific use case for step S130: Under low-load conditions, combustion within the engine cylinders becomes complex. Due to the generally low pressure and temperature, unburned methanol is easily formed at the end of combustion due to insufficient oxidation. Excessive unburned methanol at this point exceeds the working range of the reformer, causing an imbalance in the hydrogen-to-methanol ratio in the exhaust. In traditional reformer recirculation systems, the hydrogen-to-methanol imbalanced reformed gas is reinjected into the cylinder, further suppressing methanol combustion.

[0068] When the pressure in gas cylinder 4 is stable, if the proportion of methanol in the exhaust gas exceeds the threshold, after checking the engine operating conditions, step S110 will be executed first to close the flow regulating valve 3 of the reformed gas recirculation branch to prevent the exhaust gas from further affecting the hydrogen-methanol ratio of the reformed gas in gas cylinder 4. Furthermore, reformed gas will be injected again in the later stage of the tail combustion to enhance methanol oxidation in the tail combustion stage and achieve in-cylinder coordinated control of pollutant emissions.

[0069] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A diesel-ignited methanol dual-fuel engine exhaust reforming and combustion system, characterized in that, include: An exhaust reforming device (1) is installed on the engine exhaust pipe and is used to catalytically reform unburned methanol in the exhaust; The flow regulating valve (3) of the reforming gas circulation branch is located on the downstream exhaust pipe of the exhaust reforming device (1); The gas storage cylinder (4) is connected to the exhaust pipe through the flow regulating valve (3) of the reforming gas circulation branch; The reformer intake common rail (5) and the reformer cylinder direct injection common rail (6) are respectively connected to the gas storage cylinder (4); The reforming gas intake nozzle (7) is connected to the reforming gas intake injection common rail (5) and is used to inject reforming gas into the engine intake manifold. Methanol direct injection common rail (10); The in-cylinder direct injection gas auxiliary nozzle (11) is connected to the methanol in-cylinder direct injection common rail (10) and the reforming gas in-cylinder direct injection common rail (6); A cylinder pressure sensor (16) is installed on the engine cylinder head to detect the cylinder pressure; The first methanol and hydrogen sensor (13) is installed on the exhaust pipe between the exhaust reforming device (1) and the reforming gas circulation branch flow regulating valve (3); The ECU (17) has its signal input terminal electrically connected to the cylinder pressure sensor (16) and the first methanol and hydrogen sensor (13), and its signal control output terminal electrically connected to the reforming gas circulation branch flow regulating valve (3), the reforming gas intake nozzle (7), and the in-cylinder direct injection gas auxiliary nozzle (11).

2. The exhaust gas reforming and combustion system for a diesel-ignited methanol dual-fuel engine according to claim 1, characterized in that, The gas storage cylinder (4) is equipped with a second methanol and hydrogen sensor (15) for monitoring the composition of the reformed gas inside. The gas storage cylinder (4) is also equipped with a reforming gas pressure sensor (14) for monitoring its internal pressure. The second methanol and hydrogen sensor (15) and the reforming gas pressure sensor (14) are both electrically connected to the ECU (17) to provide a gas storage cylinder status feedback signal for regulating the flow regulating valve (3) of the reforming gas circulation branch.

3. The exhaust gas reforming and combustion system for a diesel-ignited methanol dual-fuel engine according to claim 1, characterized in that, It also includes a diesel in-cylinder direct injection common rail (8) and a diesel in-cylinder direct injection nozzle (9) connected to the diesel in-cylinder direct injection common rail (8). The diesel in-cylinder direct injection nozzle (9) is connected to the ECU (17) and is used to inject diesel into the cylinder as the main ignition source. The reformed gas introduced by the reforming gas intake nozzle (7) and the in-cylinder direct injection gas auxiliary nozzle (11) serves as an auxiliary ignition and combustion promotion medium.

4. A method for exhaust gas reforming and combustion control in a diesel-ignited methanol dual-fuel engine, characterized in that, Includes the following steps: The engine exhaust gas is catalytically reformed by an exhaust reforming device (1) to produce reformed gas; Part of the reformed gas is introduced into the gas storage cylinder (4) through the reformed gas circulation branch flow regulating valve (3), and the flow regulating valve (3) is adjusted based on the real-time exhaust composition data obtained by the methanol and hydrogen sensors to control the hydrogen-methanol ratio of the reformed gas in the gas storage cylinder (4). The reformed gas in the gas storage cylinder (4) is introduced into the engine cylinder in two ways: part of it is injected into the engine intake manifold through the reformed gas intake manifold nozzle (7), and the other part is injected into the cylinder in conjunction with methanol from the methanol in-cylinder direct injection common rail (10) through the in-cylinder direct injection gas auxiliary nozzle (11). The cylinder pressure curve of the engine is obtained in real time by the cylinder pressure sensor (16). The cylinder pressure curve is compared with the calibrated cylinder pressure curve under the current working condition to determine the combustion state. When the cylinder pressure curve is lower than the calibrated curve, the amount of reforming gas injected into the cylinder direct injection auxiliary nozzle (11) is increased through the reforming gas cylinder direct injection common rail (6). When the cylinder pressure curve is higher than the calibrated curve, part of the reforming gas is transferred from the cylinder direct injection to the reforming gas intake port nozzle (7) supplied through the reforming gas intake port injection common rail (5) for injection. Whether the methanol concentration in the exhaust gas detected by the first methanol and hydrogen sensor (13) exceeds the preset threshold is determined to determine whether to inject supplemental reforming gas during the tail combustion period of the engine expansion stroke.

5. The method for exhaust gas reforming and combustion control of a diesel-ignited methanol dual-fuel engine according to claim 4, characterized in that, The specific process of comparing the cylinder pressure curve with the calibrated cylinder pressure curve under the current operating condition to determine the combustion state includes: The ECU (17) receives and processes the real-time cylinder pressure signal from the cylinder pressure sensor (16) to generate a real-time cylinder pressure curve, and compares the real-time cylinder pressure curve with the calibrated cylinder pressure curve stored in the memory of the ECU (17) that corresponds to the current engine speed and torque point by point, and calculates the average pressure deviation between the two in the combustion phase. When the average pressure deviation does not exceed the preset allowable error range, the in-cylinder combustion state is determined to be normal and the current reforming gas injection distribution strategy is maintained. When the average pressure deviation exceeds the allowable error range, the overall trend of the real-time cylinder pressure curve is further analyzed. If the measured pressure value is consistently lower than the calibrated cylinder pressure curve throughout the main combustion stage, it is determined to be a combustion suppression state, and an adjustment command to increase the amount of in-cylinder direct injection reforming gas is triggered. If the measured pressure value is consistently higher than the calibration curve, it is determined to be a rough combustion state, and an adjustment command is triggered to transfer the reformed gas from the direct injection section to the intake manifold injection.

6. The method for exhaust gas reforming and combustion control of a diesel-ignited methanol dual-fuel engine according to claim 4, characterized in that, The specific process of controlling the hydrogen alcohol ratio of the reformed gas in the gas storage cylinder (4) includes: The specific process of controlling the hydrogen alcohol ratio of the reformed gas in the gas storage cylinder (4) includes: The ECU (17) first determines the initial opening angle Q1 of the reforming gas circulation branch flow regulating valve (3) by referring to the table based on the engine operating conditions; Then, the following monitoring and adjustment steps are executed repeatedly: Read the data from the first methanol and hydrogen sensor (13) installed on the exhaust pipe, and determine whether the hydrogen concentration in the exhaust is lower than the minimum threshold S2 required to ensure the normal operation of the reformer. If it is lower, immediately close the flow regulating valve (3) of the reformer circulation branch to stop the introduction of exhaust that may dilute hydrogen. Read the data from the reforming gas pressure sensor (14) set on the gas storage cylinder (4) to determine whether the pressure of the gas storage cylinder exceeds the safety limit S3. If it does, close the flow regulating valve (3) of the reforming gas circulation branch. The data from the second methanol and hydrogen sensor (15) installed on the gas storage cylinder (4) is read to obtain the real-time methanol-hydrogen ratio S4 in the gas storage cylinder, and it is compared with the preset reasonable lower limit S5 and upper limit S6 of the methanol-hydrogen ratio. Based on the relationship between S4 and S5 and S6, combined with the value of the exhaust methanol-hydrogen ratio S1, the opening angle of the reforming gas circulation branch flow regulating valve (3) is dynamically adjusted through the preset decision logic to maintain S4 within the target range of S5 to S6.

7. The method for exhaust gas reforming and combustion control of a diesel-ignited methanol dual-fuel engine according to claim 4, characterized in that, Under low-temperature cold start conditions, the ECU (17) executes a start-up control strategy, which includes: After detecting the start signal, it determines the cold start mode based on the coolant temperature or intake air temperature; In cold start mode, the operation of the reforming gas intake nozzle (7) is temporarily stopped, and the distribution valves on the reforming gas intake injection common rail (5) and the reforming gas cylinder direct injection common rail (6) are controlled to concentrate and distribute all the reforming gas that can be supplied in the gas storage cylinder (4) to the reforming gas cylinder direct injection common rail (6). When a methanol injection event is triggered, the ECU (17) controls the in-cylinder direct injection gas auxiliary nozzle (11) to start the auxiliary injection of reforming gas at the start of methanol injection or within a predetermined crankshaft angle interval before the start of methanol injection. The pressure of the auxiliary injection is set to be higher than the reforming gas injection reference pressure under normal operating conditions. As a result, the high-pressure reforming gas jet injected into the cylinder interacts violently with the methanol spray, and the resulting strong turbulence effectively promotes the secondary breakup and accelerated evaporation of methanol droplets, and forms a local high-concentration, high-activity reforming gas-methanol mixture core area in the initial development region of the methanol spray. The core area utilizes highly reactive components such as hydrogen in the reformed gas to significantly reduce the ignition threshold of the mixed gas, thereby greatly shortening the actual ignition delay period of methanol in low-temperature environments and ensuring stable and reliable first-time ignition success during cold starts. Once the engine has started successfully and is running stably, and the cylinder pressure or calculated cylinder temperature fed back by the cylinder pressure sensor (16) reaches the preset exit threshold, the ECU (17) automatically switches the reforming gas injection control mode back to the collaborative control mode based on real-time comparison and feedback of the cylinder pressure curve.

8. The method for exhaust gas reforming and combustion control of a diesel-ignited methanol dual-fuel engine according to claim 4, characterized in that, Under high engine load conditions, when the combustion is determined to be rough based on the comparison of cylinder pressure curves, the ECU (17) executes a combustion mitigation strategy. The specific process of this strategy is as follows: While maintaining the total reforming gas supply mass flow rate set under the current operating conditions, the amount of reforming gas injected through the reforming gas in-cylinder direct injection common rail (6) to the in-cylinder direct injection auxiliary nozzle (11) is gradually reduced by adjusting the flow control devices upstream or downstream of the reforming gas inlet injection common rail (5) and the reforming gas in-cylinder direct injection common rail (6), while the amount of reforming gas injected through the reforming gas inlet injection common rail (5) to the reforming gas inlet nozzle (7) is increased proportionally.

9. The method for exhaust gas reforming and combustion control of a diesel-ignited methanol dual-fuel engine according to claim 4, characterized in that, The process of determining whether to inject reforming gas during the tail combustion period based on whether the methanol concentration in the exhaust gas detected by the first methanol and hydrogen sensor (13) exceeds a preset threshold includes: The ECU (17) continuously monitors the methanol concentration value in the exhaust gas fed back by the first methanol and hydrogen sensor (13) and compares it with a dynamic threshold calibrated according to the current engine load and speed. When the methanol concentration value exceeds the dynamic threshold, it indicates that the combustion in the cylinder may be incomplete due to the drop in temperature and pressure at the end of the expansion stroke. At this time, the ECU (17) will control the in-cylinder direct injection gas auxiliary nozzle (11) or the reforming gas intake nozzle (7) to perform one or more short reforming gas supplement injections during the tail combustion stage of the current combustion cycle, that is, within a certain crankshaft angle range after the piston reaches the top dead center.

10. The method for exhaust gas reforming and combustion control of a diesel-ignited methanol dual-fuel engine according to claim 4, characterized in that, Exhaust reforming and combustion control methods also include the following processes: The ECU (17) continuously acquires and processes the cylinder pressure signal from the cylinder pressure sensor (16), the exhaust component signal from the first methanol and hydrogen sensor (13), and the gas storage tank status signal from the second methanol and hydrogen sensor (15) and the reformer pressure sensor (14). Based on the cylinder pressure signal, the ECU (17) diagnoses the combustion stability in the cylinder in real time by comparison and analysis, and generates corresponding reforming gas injection quantity distribution adjustment commands to directly drive the in-cylinder direct injection gas auxiliary nozzle (11) and reforming gas intake port nozzle (7) to work. Meanwhile, based on the exhaust component signal and the gas storage cylinder status signal, the ECU (17) assesses the quality and storage safety of the reforming gas feedstock, and dynamically controls the opening of the reforming gas circulation branch flow regulating valve (3) by generating flow regulation commands, so as to maintain the reforming gas hydrogen alcohol ratio and pressure in the gas storage cylinder (4) within the target range. For the supplementary injection decision during the tail combustion period, the ECU (17) independently generates and executes the supplementary injection trigger command by taking into account the current operating parameters and the excessive methanol concentration in the exhaust.

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