Hydrogen engine transient combustion optimization and nitrogen oxide suppression control method and device

Abstract

The invention relates to a transient combustion optimization and nitrogen oxide suppression control method and device of a hydrogen engine in the technical field of hydrogen engines. The method comprises the following steps that the rotating speed change rate and the throttle opening change rate of the hydrogen engine within set time are obtained; the cooling liquid temperature and the air inlet temperature are obtained; judging whether the hydrogen engine is in one of the following working conditions: a steady-state working condition, a cold start working condition, a rapid acceleration working condition and a slow acceleration working condition or not according to the rotating speed change rate, the throttle opening change rate, the coolant temperature and the intake temperature; and executing a corresponding control strategy according to the working condition that the hydrogen engine is about to be in. According to the method and device, through real-time coordinated regulation and control over the air-fuel ratio, the EGR rate and the water spraying strategy of the hydrogen engine, stable combustion and clean emission of the hydrogen engine are achieved.

Description

Technical Field

[0001] This application relates to the field of hydrogen engine technology, and in particular to a method and apparatus for transient combustion optimization and nitrogen oxide suppression control in hydrogen engines. Background Technology

[0002] Hydrogen has advantages such as zero carbon, high calorific value, and fast combustion speed, making it an ideal alternative fuel for engines. Using hydrogen in engines can improve engine performance while achieving clean combustion. However, the high combustion temperature of hydrogen results in high levels of NOx produced in the cylinder, making it difficult for hydrogen engines to achieve net-zero emissions.

[0003] During the dynamic operation of a vehicle, the engine often operates under transient conditions. Under these conditions, the combustion state within the engine cylinder changes frequently, with significant fluctuations in combustion rate and pressure, causing abrupt changes in peak temperature and pressure, thus increasing abnormal combustion phenomena within the cylinder. Data shows that emissions from transient engine conditions can account for 50% to 60% of total emissions, and the changes in air-fuel ratio during transient acceleration in hydrogen engines lead to a surge in NOx emissions during these transient periods. Optimizing the in-cylinder combustion state during transient processes can effectively improve engine NOx emissions. However, current emission control technologies used in vehicles are mostly focused on steady-state operation and cannot effectively address the problems of abnormal transient combustion and NOx emissions in hydrogen engines. Therefore, a transient NOx control solution suitable for hydrogen engines is urgently needed to solve this problem. Summary of the Invention

[0004] In view of the problems existing in the background technology, this application provides a method and device for transient combustion optimization and nitrogen oxide suppression control of hydrogen engine, which realizes stable combustion and clean emissions of hydrogen engine by real-time coordinated control of air-fuel ratio, EGR rate and water injection strategy of hydrogen engine.

[0005] According to one aspect of the present invention, a method for transient combustion optimization and nitrogen oxide suppression control in a hydrogen engine is provided, comprising the following steps: The engine speed change rate and throttle opening change rate of the hydrogen engine within a set time period are obtained; the coolant temperature and intake air temperature are also obtained.

[0006] Based on the speed change rate, throttle opening change rate, coolant temperature, and intake air temperature, determine whether the hydrogen engine is in one of the following operating conditions: steady-state condition, cold start condition, rapid acceleration condition, or slow acceleration condition.

[0007] When the hydrogen engine is in steady-state operation, the engine speed is acquired, and the excessive air dilution, exhaust gas recirculation, and in-cylinder water injection are controlled accordingly. When the hydrogen engine is in cold-start operation, the appropriate range and detection value interval of the cold-start air-fuel ratio of the hydrogen engine are acquired, and the excessive air dilution is controlled accordingly. When the hydrogen engine is in rapid acceleration operation, cylinder pressure, cylinder temperature, nitrogen oxide emission rate, and the appropriate range and detection value interval of the rapid acceleration air-fuel ratio are acquired, and the excessive air dilution, exhaust gas recirculation, and in-cylinder water injection are controlled accordingly. When the hydrogen engine is in slow acceleration operation, cylinder pressure, cylinder temperature, nitrogen oxide emission value, and the appropriate range and detection value interval of the slow acceleration air-fuel ratio are acquired, and the excessive air dilution, exhaust gas recirculation, and in-cylinder water injection are controlled accordingly.

[0008] According to another aspect of the present invention, a transient combustion optimization and nitrogen oxide suppression control device for a hydrogen engine is provided, applied to the aforementioned transient combustion optimization and nitrogen oxide suppression control method for a hydrogen engine, comprising: a data acquisition module for acquiring the rate of change of engine speed and the rate of change of throttle opening, as well as the coolant temperature and intake air temperature of the hydrogen engine within a set time; an operating condition determination module for determining the operating condition of the hydrogen engine based on the magnitude of the rate of change of engine speed, the rate of change of throttle opening, the coolant temperature, and the intake air temperature; and an execution module for selecting at least one of air over-dilution, exhaust gas recirculation, and in-cylinder water injection for execution based on the operating condition of the hydrogen engine.

[0009] Compared with the prior art, the present invention achieves the following technical effects: 1. NOx control method with synergistic effect of multiple dilution methods: The present invention designs a NOx control method with "lean combustion + EGR" as the main method and water spray as the auxiliary method. Through the synergistic effect of multiple dilution methods, the NOx emission suppression effect is effectively improved.

[0010] 2. Combustion stability control method: This invention improves the combustion stability of hydrogen engines by detecting exhaust emissions and in-cylinder combustion status and using EGR and water injection technology for pre-regulation.

[0011] 3. NOx Real-time Suppression Method: This invention increases the responsiveness of the EGR system by adding an EGR pump; based on development test calibration, a transient change trend curve of the hydrogen engine is plotted, and the transient change trend of the hydrogen engine is predicted according to the speed change rate and throttle opening change rate, so as to adjust the EGR rate in advance, saving system reaction time and enhancing the timeliness of NOx control.

[0012] 4. Graded Suppression Scheme: This invention determines the specific motion state of transient operating conditions and adjusts the frequency and proportion of use of "excessive air dilution", "EGR" and "water spray strategy". By reasonably combining different NOx suppression methods in different operating states, it achieves efficient and economical instantaneous NOx suppression.

[0013] 5. In addition, the hydrogen engine of the present invention uses hydrogen as fuel, which is beneficial to achieving traffic emission reduction; multiple dilution methods work together to effectively reduce the NOx content in the exhaust gas; prediction of the operating status of the hydrogen engine can effectively suppress the occurrence of NOx peaks; multiple dilution methods work together to suppress abnormal combustion phenomena in the cylinder of the hydrogen engine and reduce the risk of knocking. Attached Figure Description

[0014] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the transient combustion optimization and nitrogen oxide suppression control device for hydrogen engines of the present invention.

[0015] Figure 2 This is a flowchart of the transient combustion optimization and nitrogen oxide suppression control method for hydrogen engines of the present invention.

[0016] Figure 3 This is the flowchart of transient NOx control under cold start conditions of the present invention.

[0017] Figure 4 This is the flowchart of the transient NOx control under rapid acceleration conditions of the present invention.

[0018] Figure 5 This is the flowchart of the transient NOx control under slow acceleration conditions of the present invention.

[0019] The labels in the attached diagram represent the following: 1. Throttle valve; 2. Throttle position sensor; 3. Air flow meter; 4. EGR valve; 5. Exhaust gas flow meter; 6. ECU; 7. Cooler; 8. NOx concentration sensor; 9. EGR pump; 10. Hydrogen flow meter; 11. First backfire valve; 12. Hydrogen injector; 13. Cylinder pressure sensor; 14. Spark plug; 15. Cylinder temperature sensor; 16. Water injector; 17. Second backfire valve; 18. High-pressure water pump; 19. Hydrogen tank; 20. Photoelectric sensor; 21. Water tank. Detailed Implementation

[0020] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0021] In the following description, when referring to the accompanying drawings, the same numbers in different drawings denote the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0022] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0023] When a hydrogen engine is under transient operating conditions, parameters such as intake air volume, fuel gas volume (hydrogen intake), cylinder temperature, and cylinder pressure continuously change, leading to continuous variations in the air-fuel ratio and an increase in the frequency of abnormal combustion. Under these conditions, traditional combustion and emission control methods, such as simple air dilution or exhaust gas recirculation (EGR), struggle to achieve comprehensive control, especially during transient acceleration when the pressure to control NOx emissions surges. Currently, most designs for aftertreatment emission control in hydrogen engines focus on steady-state operation, while research on NOx emission control under transient conditions is relatively limited.

[0024] Therefore, this invention addresses the problem of continuously enriched air-fuel mixture caused by untimely responses in air and EGR during the transient acceleration process of hydrogen engines, such as rapid acceleration, gradual acceleration, and cold start. This leads to a surge in NOx emissions and an increase in the frequency of abnormal combustion. The invention develops and designs a structural scheme and control method for transient combustion optimization and NOx suppression in hydrogen engines. By using the ECU to predict the engine's operating state, it combines "excessive air dilution" and "exhaust gas recirculation," supplemented by a high-temperature in-cylinder water injection scheme, to achieve effective NOx control while ensuring efficient and stable combustion.

[0025] This application discloses a method for transient combustion optimization and nitrogen oxide suppression control in a hydrogen engine. This method can be executed by a hydrogen engine transient combustion optimization and nitrogen oxide suppression control device, which includes a data acquisition module, an operating condition determination module, and an execution module. The data acquisition module is used to acquire the rate of change of engine speed and throttle opening within a set time, as well as the coolant temperature and intake air temperature. The operating condition determination module is used to determine the operating condition of the hydrogen engine based on the rate of change of engine speed, the rate of change of throttle opening, and the coolant and intake air temperatures. The execution module is used to select at least one of the following for execution based on the operating condition of the hydrogen engine: excessive air dilution, exhaust gas recirculation, and in-cylinder water injection.

[0026] In some embodiments of the present invention, such as Figure 1 As shown, the transient combustion optimization and nitrogen oxide suppression control device for the hydrogen engine is located in the hydrogen engine. The device includes a throttle valve 1, a throttle position sensor 2, an air flow meter 3, an EGR valve 4, an exhaust gas flow meter 5, an ECU 6, a cooler 7, a NOx concentration sensor 8, an EGR pump 9, a hydrogen flow meter 10, a first backfire valve 11, a hydrogen injector 12, a cylinder pressure sensor 13, a spark plug 14, a cylinder temperature sensor 15, a water injector 16, a second backfire valve 17, a high-pressure water pump 18, a hydrogen tank 19, a photoelectric sensor 20, a water tank 21, a coolant temperature sensor, and an intake air temperature sensor. The exhaust pipe of the hydrogen engine passes sequentially through the EGR pump 9, the cooler 7, and the exhaust gas flow meter 5. The EGR valve 4 is connected to the intake manifold; the water tank 21 is connected to the hydrogen engine cylinder via the high-pressure water pump 18, the second backfire valve 17, and the water nozzle 16; the hydrogen cylinder 19 is connected to the hydrogen engine cylinder via the hydrogen flow meter 10, the first backfire valve 11, and the hydrogen nozzle 12; the throttle valve 1, throttle position sensor 2, air flow meter 3, EGR valve 4, exhaust gas flow meter 5, NOx concentration sensor 8, EGR pump 9, hydrogen flow meter 10, hydrogen nozzle 12, cylinder pressure sensor 13, spark plug 14, cylinder temperature sensor 15, water nozzle 16, high-pressure water pump 18, photoelectric sensor 20, coolant temperature sensor, and intake air temperature sensor are all electrically connected to the ECU 6.

[0027] Throttle valve 1 is used to regulate the intake air volume, and throttle position sensor 2 is used to measure the opening degree of throttle valve 1 in real time. Air enters the cylinder after passing through throttle valve 1 and air flow meter 3 in the intake manifold. Air flow meter 3 is used to measure the intake air volume in real time. In-cylinder exhaust gas is discharged through the exhaust manifold, and NOx concentration sensor 8 is used to measure the concentration of nitrogen oxides in the exhaust gas in real time. Some in-cylinder exhaust gas flows into the EGR pipeline, and after being cooled by cooler 7, it flows into the intake manifold through EGR valve 4. The opening degree of EGR valve 4 is controlled by ECU 6. EGR pump 9 adopts a "normally open" design, that is, it maintains the open state (gas can pass through in a limited way) when not powered, and pressurizes the exhaust gas when powered, balancing the accuracy of active control and For safety and reliability under passive operating conditions, the exhaust gas flow meter 5 provides the ECU 6 with real-time intake air volume; hydrogen gas is injected directly into the cylinder from the hydrogen cylinder 19 through a pipeline equipped with a hydrogen flow meter 10, and the hydrogen flow meter 10 provides the ECU 6 with real-time fuel volume; the cylinder pressure sensor 13 is used to measure cylinder pressure in real time; the cylinder temperature sensor 15 is used to measure cylinder temperature in real time; water is transported from the water tank 21 through the high-pressure water pump 18, and the ECU 6 controls the water nozzle 16 to achieve water spraying and cooling in the cylinder; the photoelectric sensor 20 is installed at the crankshaft to measure the speed of the hydrogen engine in real time; the coolant temperature sensor is used to measure the temperature of the hydrogen engine coolant in real time; and the intake air temperature sensor is used to measure the intake air temperature of the hydrogen engine in real time.

[0028] like Figure 2 As shown, the transient combustion optimization and nitrogen oxide suppression control method for the hydrogen engine includes the following steps: S1. Obtain the rate of change of the hydrogen engine speed and the rate of change of the throttle opening within a set time; obtain the coolant temperature and intake air temperature.

[0029] S2. Based on the rate of change of engine speed, the rate of change of throttle opening, and the magnitude of coolant temperature and intake air temperature, determine whether the hydrogen engine is in one of the following operating conditions: steady-state condition, cold start condition, rapid acceleration condition, and slow acceleration condition.

[0030] S3. Execute the corresponding control strategy based on the operating conditions that the hydrogen engine will soon be in.

[0031] When the hydrogen engine is in steady-state operation, the engine speed is acquired, and based on the engine speed, the excessive air dilution, exhaust gas recirculation, and in-cylinder water injection are controlled.

[0032] When the hydrogen engine is in cold start condition, the appropriate range and detection value range of the cold start air-fuel ratio of the hydrogen engine are obtained, and the excessive dilution of air is controlled according to the appropriate range and detection value range of the cold start air-fuel ratio.

[0033] When the hydrogen engine is under rapid acceleration, the appropriate range and detection range of cylinder pressure, cylinder temperature, nitrogen oxide emission rate, and rapid acceleration air-fuel ratio are obtained. Based on the appropriate range and detection range of cylinder pressure, cylinder temperature, nitrogen oxide emission rate, and rapid acceleration air-fuel ratio, the excessive air dilution, exhaust gas recirculation, and in-cylinder water injection are controlled.

[0034] When the hydrogen engine is in a slow acceleration condition, the cylinder pressure, cylinder temperature, nitrogen oxide emission values, and the appropriate range and detection range of the slow acceleration air-fuel ratio are obtained. Based on the cylinder pressure, cylinder temperature, nitrogen oxide emission values, and the appropriate range and detection range of the slow acceleration air-fuel ratio, the excessive air dilution, exhaust gas recirculation, and in-cylinder water injection are controlled.

[0035] In this invention, when the driver performs driving operations, by acquiring the rate of change of the hydrogen engine's rotational speed and throttle opening, as well as the coolant temperature and intake air temperature within a set time period at the beginning of the driving operation, the operating condition of the hydrogen engine can be predicted in advance based on these parameters: steady-state condition, cold start condition, rapid acceleration condition, or slow acceleration condition. Then, according to the characteristics of different operating conditions, excessive air dilution and exhaust gas recirculation are combined, supplemented by high-temperature in-cylinder water injection, to achieve real-time coordinated control of the hydrogen engine's air-fuel ratio, EGR rate, and water injection strategy, thereby achieving stable combustion and clean emissions from the hydrogen engine. While ensuring efficient and stable combustion, NOx is effectively controlled.

[0036] In some embodiments of the present invention, the set time in step S1 can be 40ms-60ms, and can be reasonably designed according to needs, preferably 50ms; that is, the rate of change of the speed of the hydrogen engine and the rate of change of the throttle opening within 50ms in the initial stage of driving operation can be evaluated, so as to timely and effectively determine whether the hydrogen engine is in a transient condition.

[0037] In some embodiments of the present invention, the rate of change of the rotational speed of the hydrogen engine is calculated by the difference in rotational speed dn between a second time point and a first time point at a set time and the difference in time dt between the second time point and the first time point.

[0038] (1) In some embodiments of the present invention, the throttle opening change rate of the hydrogen engine is calculated by the difference dθ between the throttle opening at a second time point and a first time point at a set time and the time difference dt between the second time point and the first time point.

[0039] (2) In some embodiments of the present invention, photoelectric sensors and throttle position sensors are used to monitor the instantaneous speed and throttle opening of the hydrogen engine, and coolant temperature sensors and intake air temperature sensors are used to monitor the coolant temperature and intake air temperature of the hydrogen engine, and the collected electrical signals are transmitted to the ECU.

[0040] In some embodiments of the present invention, step S2, based on the rate of change of engine speed and the rate of change of throttle opening, as well as the coolant temperature and intake air temperature, determines whether the hydrogen engine is in a steady-state operating condition or a cold start condition, a rapid acceleration condition, or a slow acceleration condition in a transient operating condition, including the following steps: S21. Set the speed change rate threshold for transient operating conditions of the hydrogen engine. 1 and the threshold of throttle opening change rate 1. Set the coolant temperature threshold and intake air temperature threshold. Set the minimum speed change threshold for rapid acceleration of the hydrogen engine. high and the minimum threshold of throttle opening change rate high Set the minimum threshold for the rate of change of engine speed under slow acceleration conditions of the hydrogen engine. low and the minimum threshold of throttle opening change rate low .

[0041] S22, Measure the actual speed change rate Throttle opening change rate and 1 and 1. Compare the results to determine whether the hydrogen engine is in a steady-state or transient operating condition.

[0042] Specifically, in this embodiment, if the measured rate of change of rotational speed... Throttle opening change rate None exceeded the threshold 1 and 1. If the hydrogen engine is in steady-state operation, then the measured speed change rate is considered to be within a certain range. Throttle opening change rate Any exceeding the threshold 1 and If 1 is selected, it can be determined that the hydrogen engine is in a transient operating state.

[0043] S23. When it is determined that the hydrogen engine is in a transient operating condition, the measured coolant temperature and intake air temperature are compared with the coolant temperature threshold and intake air temperature threshold to determine whether the hydrogen engine is in a cold start condition or an acceleration condition.

[0044] Specifically, in this embodiment, if the measured coolant temperature and intake air temperature are lower than the coolant temperature threshold and intake air temperature threshold, it is determined that the current condition is a cold start condition; if the measured coolant temperature and intake air temperature are higher than the coolant temperature threshold and intake air temperature threshold, it is determined that the current condition is an acceleration condition.

[0045] S24. When it is determined that the hydrogen engine is in acceleration mode, the measured speed change rate will be... Throttle opening change rate and high , low and high , low By comparison, it can be determined whether the hydrogen engine is in a rapid acceleration condition or a slow acceleration condition.

[0046] Specifically, in this embodiment, if the rate of change of the hydrogen engine throttle opening is... > high and the rate of change of rotational speed > high If the hydrogen engine is about to enter a rapid acceleration phase, then it is determined that the hydrogen engine is about to enter a rapid acceleration phase; if the rate of change of the hydrogen engine throttle opening is at this time... low < high and the rate of change of rotational speed low < high If so, it can be determined that the hydrogen engine is about to enter a slow acceleration mode.

[0047] In some embodiments of the present invention, the preset numerical range of steady-state operating conditions for the hydrogen engine is calibrated by engine development tests. Under steady-state operating conditions, the hydrogen engine uses the optimal air-fuel ratio, EGR rate, and water injection strategy calibrated by the development tests at different speed loads, thereby achieving NOx emission control of the hydrogen engine under steady-state operating conditions.

[0048] In some embodiments of the present invention, the exhaust gas recirculation system meets the requirements under steady-state conditions without the need to turn on the EGR pump to accelerate the EGR response; that is, the exhaust gas recirculation adopts the ordinary EGR mode without EGR pump drive.

[0049] In some embodiments of the present invention, the air-fuel ratio λ of the hydrogen engine is calculated using the hydrogen mass flow rate Mfuel and the air mass flow rate Mair measured by the hydrogen flow meter and the air flow meter, respectively.

[0050] (3) In some embodiments of the present invention, the real-time EGR rate of the hydrogen engine is determined by the mass flow rate M of the EGR gas measured by the exhaust gas flow meter. EGR The mass flow rate of fresh air measured by the air flow meter in the intake duct is calculated by Mair.

[0051] (4) In some embodiments of the present invention, the speed change rate threshold of the hydrogen engine transient operating condition is... 1. Minimum threshold for the rate of change of speed under slow acceleration conditions low The threshold value for the rate of change of throttle opening under transient operating conditions of a hydrogen engine can be the same. 1. Minimum threshold for throttle opening change rate under slow acceleration conditions low They can be the same value.

[0052] In some embodiments of the present invention, the speed change rate threshold of the hydrogen engine transient operating condition is... 1 ( low Threshold for throttle opening change rate 1 ( low And the minimum threshold for the rate of change of speed under rapid acceleration conditions. high and the minimum threshold of throttle opening change rate high Calibrated by engine development and testing.

[0053] In some embodiments of the present invention, the preset numerical range of the rapid acceleration condition is calibrated by engine development tests. During rapid acceleration, the torque and speed of the hydrogen engine increase rapidly in a short period, which severely degrades its combustion stability. Therefore, rapid acceleration requires coordinated adjustment using three dilution methods. Simultaneously, due to the high responsiveness requirements of EGR during rapid acceleration, the EGR pump needs to be activated in advance to improve responsiveness under transient conditions. That is, during rapid acceleration, the exhaust gas recirculation system cannot meet the demand, and the EGR pump needs to be activated to accelerate EGR responsiveness. The exhaust gas recirculation employs a strategy combining a transient response EGR mode driven by an EGR pump and a normal EGR mode without an EGR pump.

[0054] In some embodiments of the present invention, the preset numerical range of the slow acceleration condition is calibrated by engine development tests. Under slow acceleration, the engine runs relatively smoothly, but the acceleration time is relatively long. At this time, the air-fuel ratio of the engine fluctuates relatively little, but the prolonged heating results in a large accumulation of heat load in the hydrogen engine cylinder. Three dilution methods are also required for coordinated adjustment under slow acceleration. Unlike rapid acceleration, the fluctuations in cylinder temperature and pressure change rates are relatively small under slow acceleration, eliminating the need for pre-injection of water for suppression. Simultaneously, the responsiveness requirements for EGR are also higher during slow acceleration, necessitating the early activation of the EGR pump to improve responsiveness under transient conditions. That is, when the hydrogen engine is in slow acceleration, the EGR pump needs to be activated to accelerate EGR response. The exhaust gas recirculation employs a strategy combining a transient response EGR mode driven by an EGR pump and a normal EGR mode without an EGR pump.

[0055] In this invention, compared to traditional exhaust gas recirculation systems that rely on the pressure difference between the exhaust pipe and the intake manifold and control the amount of exhaust gas recirculation through the EGR valve to reduce combustion temperature and reduce nitrogen oxide emissions, the present invention addresses the problem of poor control accuracy under transient conditions and difficulty in achieving smooth and rapid switching between various dilution modes by adding an EGR pump. This allows for highly efficient EGR transient response, meaning that under rapid or slow acceleration conditions, either a transient response EGR mode driven by an EGR pump or a normal EGR mode without an EGR pump can be used as needed to better handle rapid and slow acceleration conditions.

[0056] In some embodiments of the present invention, in step S3, the air over-dilution technology refers to the pre-adjustment of the amount of air entering the hydrogen engine cylinder by the ECU. That is, when the accelerator pedal opening and its rate of change change, the ECU will increase the throttle opening amplitude and speed when adjusting the intake air volume and air volume, thus advancing the turbocharger's engagement time. During the acceleration of the hydrogen engine, due to the rapid response of hydrogen supply, the air-fuel ratio in the cylinder drops sharply, leading to a surge in nitrogen oxide emissions. Through the air over-dilution technology, the air-fuel ratio is reversed at the initial stage of acceleration, exceeding the stable value, so that the air-fuel ratio remains relatively stable during the acceleration phase, thereby achieving over-air adjustment.

[0057] Exhaust gas recirculation (EGR) technology reduces NOx emissions by reintroducing a portion of exhaust gas into the cylinder, lowering the oxygen concentration and combustion temperature. In hydrogen engines, although hydrogen has a high octane rating, lean combustion significantly increases the risk of engine knock. EGR helps reduce this risk, improves combustion stability, increases thermal efficiency, and substantially reduces NOx emissions. However, because EGR relies on the pressure difference between the exhaust and intake manifolds, even with rapid adjustment using an electromagnetic EGR valve, the overall system response time remains relatively long. This results in poor control of NOx emissions under transient conditions in hydrogen engines, making it difficult to suppress NOx emissions to ideal levels. Therefore, this invention adds an EGR pump at the EGR pipeline inlet and adjusts its opening and closing based on transient condition predictions, thereby solving the problem of poor transient response of EGR.

[0058] In-cylinder water injection technology is used to suppress in-cylinder combustion pressure and abnormal combustion phenomena in engines. Because water has a latent heat of vaporization of 2260 kJ / kg, it can significantly absorb combustion heat and reduce peak in-cylinder temperature. However, the control of water injection timing and quantity is inherently complex, further increasing the difficulty of control under transient conditions. Furthermore, water mixed with high-temperature engine oil easily forms emulsions, damaging the lubricity of the oil film and corroding metal components such as cylinder liners and pistons. This makes it difficult to use for extended periods, even though it can effectively suppress transient NOx emissions from hydrogen engines. Therefore, this invention employs in-cylinder water injection technology as a rapid control method. When abnormal combustion occurs in the cylinder, a brief water injection can quickly reduce in-cylinder pressure and temperature, thereby effectively suppressing abnormal combustion.

[0059] In some embodiments of the present invention, when the hydrogen engine is in a cold start condition, it only uses an air over-dilution strategy for adjustment. Controlling air over-dilution includes the following steps: The appropriate range for the cold start air-fuel ratio of the hydrogen engine is set to λ'min-λ'max, and the detection value is set to λ1-λ2, where λ'min<λ1<λ2<λ'max.

[0060] If the measured air-fuel ratio λ' at startup is greater than λ2 but less than λ'max, then increase the hydrogen injection pulse width until λ' is less than λ2.

[0061] If the measured air-fuel ratio λ' at startup is less than λ1 but greater than λ'min, then increase the throttle opening to increase the intake air volume until λ' is greater than λ1.

[0062] Repeat the process of excessive air dilution until the hydrogen engine is running stably.

[0063] In some embodiments of the present invention, the appropriate range of air-fuel ratio for cold start and the detection value are obtained by experiment.

[0064] In some embodiments of the present invention, if the hydrogen engine still fluctuates when the air-fuel ratio is stable, the key boundary parameters such as hydrogen injection timing, ignition timing, and ignition energy should be corrected based on historical experience to eliminate the fluctuations in the operation of the hydrogen engine.

[0065] In some embodiments of the present invention, controlling excessive air dilution, exhaust gas recirculation, and in-cylinder water injection when the hydrogen engine is under rapid acceleration includes the following steps: First, excessive air dilution, exhaust gas recirculation, and in-cylinder water injection are activated simultaneously. The exhaust gas recirculation initially adopts a transient response EGR mode driven by an EGR pump to control the air-fuel ratio, cylinder pressure, cylinder temperature, and NOx emissions of the hydrogen engine in advance. The throttle opening and EGR rate are determined by development test calibration. The water injection limit time t1 is set.

[0066] When the water injection time t reaches t1, if the air-fuel ratio, cylinder pressure, and cylinder temperature of the hydrogen engine cylinder do not decrease to the maximum limit specified in the test, the water injection will be stopped immediately and the engine will switch to a slow acceleration mode.

[0067] If the air-fuel ratio, cylinder pressure, and cylinder temperature meet the requirements before the water injection time t reaches t1, water injection will be stopped immediately, and the mixture supply of the hydrogen engine will continue to be adjusted by excessive air dilution and exhaust gas recirculation. After the air-fuel ratio changes stabilize within the first set range, the exhaust gas recirculation will switch to the normal EGR mode without EGR pump drive until the hydrogen engine is running stably.

[0068] In some embodiments of the present invention, in addition to water injection within time t1, if abnormal combustion phenomena such as cylinder pressure or cylinder temperature occur again during rapid acceleration (e.g., cylinder pressure or cylinder temperature exceeds its threshold), water injection is immediately restarted. After eliminating the combustion abnormality, the air-fuel ratio adjustment of the hydrogen engine continues by excessive air dilution and exhaust gas recirculation.

[0069] In some embodiments of the present invention, the first set range can be ±3%, which can be reasonably designed as needed. That is, after the air-fuel ratio change stabilizes within ±3%, the EGR pump is turned off, and the exhaust gas is allowed to continue to pass through by utilizing its design of being always on when the power is off.

[0070] In some embodiments of the present invention, the excessive air dilution of a hydrogen engine under rapid acceleration conditions includes the following steps: The appropriate range for the air-fuel ratio during rapid acceleration of the hydrogen engine is set to λ''min-λ''max, and the detection value is set to λ3-λ4, where λ''min<λ3<λ4<λ''max.

[0071] If the measured air-fuel ratio λ'' is greater than λ4 but less than λ''max, then reduce the throttle opening until λ'' is less than λ4.

[0072] If the measured air-fuel ratio λ'' is less than λ3 but greater than λ''min, then increase the throttle opening to increase the intake air volume until λ'' is greater than λ3.

[0073] In some embodiments of the present invention, the exhaust gas recirculation of the hydrogen engine under rapid acceleration conditions includes the following steps: Set the maximum allowable change rate of nitrogen oxide emissions. max Set the nitrogen oxide emission change rate detection value as 1, and 1 < max .

[0074] If the current measured value of nitrogen oxide emission change rate Greater than 1 but less than max Immediately activate the transient response EGR mode driven by the EGR pump, increase the EGR valve opening, and improve the EGR rate of the hydrogen engine until... Less than 1.

[0075] like Less than If 1 is selected, the current acceleration process is determined to be stable, and the normal EGR mode without EGR pump drive is adopted.

[0076] In some embodiments of the present invention, the in-cylinder water injection of the hydrogen engine under rapid acceleration conditions includes the following steps: Set the maximum allowable cylinder pressure change rate. max Maximum permissible cylinder temperature change rate max Set cylinder pressure change rate detection value 1. Cylinder temperature change rate detection value 1.

[0077] If the measured cylinder pressure change rate occurs during the process of excessive air dilution and exhaust gas recirculation... Greater than 1 but less than max Or measured value of cylinder temperature change rate Greater than 1 but less than max In such cases, the water spray system should be activated immediately. Less than 1 and Less than 1. Then repeat the coordinated regulation process of excessive air dilution and exhaust gas recirculation until the hydrogen engine is running stably.

[0078] In some embodiments of the present invention, controlling excessive air dilution, exhaust gas recirculation, and in-cylinder water injection when the hydrogen engine is in a slow acceleration condition includes the following steps: First, the air-fuel ratio of the hydrogen engine is adjusted by using excessive air dilution and exhaust gas recirculation, and the exhaust gas recirculation initially adopts a transient response EGR mode driven by an EGR pump.

[0079] If abnormal cylinder pressure or cylinder temperature combustion occurs during slow acceleration, water injection will be started immediately. After the abnormal combustion is eliminated, the air-fuel ratio of the hydrogen engine will continue to be adjusted by excessive air dilution and exhaust gas recirculation.

[0080] After the air-fuel ratio stabilizes within the second set range, the exhaust gas recirculation switches to the normal EGR mode without an EGR pump until the hydrogen engine is running stably.

[0081] In some embodiments of the present invention, the second set range can be ±3%, and its specific design can be reasonably designed as needed. That is, after the air-fuel ratio change stabilizes within ±3%, the EGR pump is turned off, and the exhaust gas is allowed to continue to pass through by utilizing its design of being always on when the power is off.

[0082] In some embodiments of the present invention, the excessive air dilution of a hydrogen engine under slow acceleration conditions includes the following steps: The appropriate range for the slow acceleration air-fuel ratio of the hydrogen engine is set to λ'''min-λ'''max, and the detection value is set to λ5-λ6, where λ'''min<λ5<λ6<λ'''max.

[0083] If the measured air-fuel ratio λ''' is greater than λ6 but less than λ'''max, then increase the hydrogen injection pulse width until λ''' is less than λ6.

[0084] If the measured air-fuel ratio λ''' is less than λ5 but greater than λ'''min, then increase the throttle opening to increase the intake air volume until λ''' is greater than λ5.

[0085] In some embodiments of the present invention, the exhaust gas recirculation of the hydrogen engine under slow acceleration conditions includes the following steps: The maximum allowable nitrogen oxide emission concentration is set at [NOx]1.

[0086] If the measured value of the current nitrogen oxide concentration [NOx] is greater than [NOx]1, the transient response EGR mode driven by the EGR pump is immediately enabled, the opening of the EGR valve is increased, and the EGR rate of the hydrogen engine is increased until the measured value of the current nitrogen oxide emission is less than [NOx]1.

[0087] If the measured value of the current nitrogen oxide emission is less than [NOx]1, it is determined that the current slow acceleration process is stable, and the ordinary EGR mode without EGR pump drive is adopted.

[0088] In some embodiments of the present invention, the maximum allowable nitrogen oxide emission concentration [NOx]1 can be 90 ppm - 110 ppm, which can be reasonably designed according to needs, and is preferably 100 ppm.

[0089] In some embodiments of the present invention, the in-cylinder water injection of the hydrogen engine in the slow acceleration condition includes the following steps: Set the maximum peak cylinder pressure of the slow acceleration condition as Pmax and the maximum peak cylinder temperature as Tmax.

[0090] If, after air excess dilution and exhaust gas recirculation, the measured cylinder pressure P1 > Pmax or the measured cylinder temperature T1 > Tmax of the hydrogen engine appears, water injection is immediately started until the measured cylinder pressure P1 < Pmax and the measured cylinder temperature T1 < Tmax, and then the coordinated adjustment process of air excess dilution and exhaust gas recirculation is repeated until the hydrogen engine runs stably.

[0091] The above method will be described below in conjunction with specific embodiments.

[0092] Step 1: Use a photoelectric sensor and a throttle position sensor to monitor the instantaneous speed and throttle opening of the hydrogen engine, and transmit the collected electrical signals to the ECU. By evaluating the engine speed change rate and throttle opening change rate within 50 ms, it is judged whether the hydrogen engine is in a transient condition. The thresholds of the transient speed change rate and throttle opening change rate of the hydrogen engine are calibrated by development tests. If both the engine speed change rate and throttle opening change rate do not exceed the thresholds, the hydrogen engine is in a steady state condition. The preset numerical range of the steady state condition is calibrated by the engine development test. The hydrogen engine uses the best air-fuel ratio, EGR rate and water injection strategy at different speed loads calibrated by the development test, so as to achieve the NOx emission control under the steady state condition of the hydrogen engine. Under the steady state condition, the exhaust gas recirculation system meets the requirements, and there is no need to start the EGR pump to accelerate the EGR responsiveness. The air-fuel ratio λ of the hydrogen engine is calculated from the hydrogen mass flow rate and air mass flow rate measured by the hydrogen flow meter and the air flow meter. The real-time EGR rate of the hydrogen engine is calculated from the mass flow rate of the EGR gas measured by the exhaust gas flow meter and the mass flow rate of the fresh air measured in the intake port.

[0093] (5) (6) Step Two: If either the engine speed change rate or the throttle opening change rate exceeds the threshold, the hydrogen engine is in a transient operating condition, requiring real-time adjustments based on actual conditions. The preset value range for the transient operating condition is calibrated through engine development testing. The results measured by the coolant temperature sensor and intake air temperature sensor are compared with the preset values. If the values ​​of the coolant temperature sensor and intake air temperature sensor are lower than the preset values, then this is determined to be a cold start condition.

[0094] like Figure 3 As shown, only the "excessive air dilution" strategy is used for adjustment under cold start conditions. Experiments show that the suitable air-fuel ratio range for cold start is within the λ'min-λ'max interval. Detection values ​​are set to λ1 and λ2, where λ'min < λ1 < λ2 < λ'max. If the measured air-fuel ratio at start-up is greater than λ2 but less than λ'max, the hydrogen injection pulse width needs to be increased until λ is less than λ2. If the measured value is less than λ1 but greater than λ'min, the excessive air dilution scheme is activated, increasing the throttle opening in advance to increase the intake air volume until λ is greater than λ1. When the air-fuel ratio is stable, if fluctuations still occur in the hydrogen engine's operation, key boundary parameters such as hydrogen injection timing, ignition timing, and ignition energy should be corrected based on historical experience to eliminate these fluctuations.

[0095] Step 3: Test and calibrate the minimum threshold for the rate of change of throttle opening under rapid acceleration conditions. high The minimum threshold for the rate of change of rotational speed is high If the throttle opening change rate of the hydrogen engine > high and the rate of change of rotational speed > high If the signal is detected, it indicates that the hydrogen engine is about to enter a rapid acceleration phase. The preset value range for this phase is calibrated through engine development testing. During rapid acceleration, the torque and speed of the hydrogen engine increase rapidly in a short period, which severely degrades its combustion stability. Therefore, rapid acceleration requires coordinated adjustment using three dilution methods. Simultaneously, due to the high responsiveness requirements of the EGR system during acceleration, the EGR pump needs to be activated in advance to improve responsiveness under transient conditions.

[0096] like Figure 4As shown, at the start of rapid acceleration, superfluid air, EGR, and water injection technologies are simultaneously activated to pre-control the air-fuel ratio, cylinder pressure, cylinder temperature, and NOx emissions of the hydrogen engine. The throttle opening and EGR rate are determined by development and testing calibration. A water injection limit time t1 is set. If the air-fuel ratio, cylinder pressure, and cylinder temperature of the hydrogen engine have not decreased to the maximum limit set by the test calibration when the water injection time t reaches t1, water injection is immediately stopped, and the engine switches to a slow acceleration mode. If the above parameters in the cylinder meet the requirements before the water injection time t reaches t1, water injection is immediately stopped. Subsequently, superfluid air and EGR technologies continue to regulate the air-fuel mixture supply of the hydrogen engine. After the air-fuel ratio fluctuation stabilizes within ±3%, the EGR pump is stopped, and the engine switches to normal EGR mode. At the same time, if abnormal cylinder pressure or cylinder temperature occurs during rapid acceleration, water injection technology is immediately activated. After eliminating the combustion abnormality, superfluid air and EGR technologies are used to regulate the air-fuel ratio of the hydrogen engine.

[0097] The optimal air-fuel ratio for rapid acceleration is within the range of λ''min-λ''max. The detection values ​​are set to λ3 and λ4, with λ''min < λ3 < λ4 < λ''max. If the measured value of λ is greater than λ4 but less than λ''max, decrease the throttle opening until λ is less than λ4. If the measured value of λ is less than λ3 but greater than λ''min, increase the throttle opening until λ is greater than λ3. Set the maximum NOx emission change rate to... max Set the detection value to 1, and 1< max If at this time Greater than 1 but less than max If necessary, immediately activate the EGR pump, increase the EGR valve opening, and improve the EGR rate of the hydrogen engine until... Less than 1. At this point, the acceleration process can be considered stable, and the EGR pump can be turned off, switching to normal EGR mode. Set the in-cylinder pressure change rate to... The rate of change of cylinder temperature Set the maximum allowable pressure change rate. max The maximum temperature change rate is max Set the detection value to 1< max , 1< max If, during excessive air dilution and EGR adjustment, [the following occurs]... Greater than 1 but less than max or Greater than 1 but less than max In such cases, the water spray system should be activated immediately. Less than 1 and Less than 1. Then repeat the above-mentioned coordinated regulation process of air dilution and EGR until the hydrogen engine is running stably.

[0098] Step 4: Test and calibrate the minimum threshold for the rate of change of throttle opening under slow acceleration conditions. low The minimum threshold for the rate of change of rotational speed is low If the throttle opening change rate of the hydrogen engine low < < high and the rate of change of rotational speed low < high If the engine is about to enter a slow acceleration mode, it is determined that the hydrogen engine is about to enter a slow acceleration mode. The preset value range for the slow acceleration mode is calibrated by engine development tests. Under slow acceleration, the engine runs relatively smoothly, but the acceleration time is relatively long. At this time, the air-fuel ratio fluctuation is relatively low, but the prolonged heating results in a significant accumulation of heat load in the hydrogen engine cylinder. Under slow acceleration, three dilution methods are also required for coordinated adjustment. Unlike rapid acceleration, the fluctuation rate of cylinder temperature and pressure change is relatively small under slow acceleration, eliminating the need for pre-injection of water for suppression. Therefore, if... Figure 5 As shown, the air-fuel ratio of the hydrogen engine is first adjusted using excess air dilution and EGR technology. After the air-fuel ratio fluctuation stabilizes within ±3%, the EGR pump is stopped, and the engine switches to normal EGR mode. Simultaneously, if abnormal cylinder pressure or temperature combustion occurs during slow acceleration, water injection technology is immediately activated. After eliminating the combustion abnormality, the air-fuel ratio of the hydrogen engine is adjusted again using excess air dilution and EGR technology.

[0099] The appropriate range of the air-fuel ratio with slow acceleration is in the λ'''min - λ'''max interval. Set the detection values as λ5 and λ6, and λ'''min < λ5 < λ6 < λ'''max. If the measured value of the air-fuel ratio at startup is greater than λ6 but less than λ'''max, it is necessary to increase the hydrogen injection pulse width until λ is less than λ6. If the measured value is less than λ5 but greater than λ'''min, start the air excess dilution scheme, increase the throttle opening in advance, and increase the intake air volume until λ is greater than λ5. Set the maximum value of NOx emissions to 100 ppm. If the actual NOx emissions > 100 ppm, increase the opening of the EGR valve and increase the EGR rate of the hydrogen engine until the actual NOx emissions < 100 ppm. Let the highest peak pressure in the slow acceleration condition be Pmax and the highest peak temperature be Tmax. If, after air dilution and EGR adjustment, the measured pressure P1 of the hydrogen engine > Pmax or the measured temperature T1 > Tmax still occurs, open the water nozzle for water injection until the measured pressure P1 < Pmax and the measured temperature T1 < Tmax. Subsequently, repeat the above collaborative adjustment process of air dilution and EGR until the hydrogen engine runs stably.

[0100] [[ID=

Claims

1. A method for transient combustion optimization and nitrogen oxide suppression control in a hydrogen engine, characterized in that, Includes the following steps: Obtain the rate of change of the hydrogen engine's rotational speed and the rate of change of the throttle opening within a set time period; obtain the coolant temperature and the intake air temperature; Based on the speed change rate, throttle opening change rate, coolant temperature, and intake air temperature, determine whether the hydrogen engine is in one of the following operating conditions: steady-state condition, cold start condition, rapid acceleration condition, or slow acceleration condition. When the hydrogen engine is in steady-state operation, the rotational speed of the hydrogen engine is obtained, and the excessive air dilution, exhaust gas recirculation and in-cylinder water injection are controlled accordingly. When the hydrogen engine is in cold start condition, the appropriate range and detection value range of the cold start air-fuel ratio of the hydrogen engine are obtained, and the excessive air dilution is controlled accordingly. When the hydrogen engine is in a rapid acceleration condition, the cylinder pressure, cylinder temperature, nitrogen oxide emission rate, and the appropriate range and detection value range of the rapid acceleration air-fuel ratio are obtained, and the excessive air dilution, exhaust gas recirculation and in-cylinder water injection are controlled accordingly. When the hydrogen engine is in a slow acceleration condition, the cylinder pressure, cylinder temperature, nitrogen oxide emission values, and the appropriate range and detection range of the slow acceleration air-fuel ratio are obtained, and the excessive air dilution, exhaust gas recirculation and in-cylinder water injection are controlled accordingly.

2. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 1, characterized in that, The exhaust pipe and intake manifold of the hydrogen engine are connected via an EGR pump. An EGR valve is provided between the EGR pump and the intake manifold. The EGR pump is normally open when power is off and pressurized when power is on. When the hydrogen engine is in steady-state operation, the exhaust gas recirculation adopts the ordinary EGR mode without EGR pump drive; When the hydrogen engine is in a rapid acceleration or slow acceleration condition, the exhaust gas recirculation adopts a strategy that combines a transient response EGR mode driven by an EGR pump and a normal EGR mode without an EGR pump.

3. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 1, characterized in that, Controlling excessive air dilution during cold start operation of the hydrogen engine includes the following steps: The appropriate range for the cold start air-fuel ratio of the hydrogen engine is set to λ'min-λ'max, and the detection value is set to λ1-λ2, where λ'min<λ1<λ2<λ'max; If the measured air-fuel ratio λ' is greater than λ2 but less than λ'max at startup, increase the hydrogen injection pulse width until λ' is less than λ2. If the measured air-fuel ratio λ' is less than λ1 but greater than λ'min at startup, increase the throttle opening to increase the intake air volume until λ' is greater than λ1. Repeat the process of excessive air dilution until the hydrogen engine is running stably.

4. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 2, characterized in that, When the hydrogen engine is under rapid acceleration, controlling excessive air dilution, exhaust gas recirculation, and in-cylinder water injection includes the following steps: First, simultaneously activate air over-dilution, exhaust gas recirculation, and in-cylinder water injection, with the initial exhaust gas recirculation using the transient response EGR mode driven by the EGR pump; set the water injection limit time t1. When the water injection time t reaches t1, if the air-fuel ratio, cylinder pressure, and cylinder temperature of the hydrogen engine cylinder do not drop to the maximum limit specified in the test, the water injection will be stopped immediately and the engine will switch to slow acceleration mode. If the air-fuel ratio, cylinder pressure, and cylinder temperature meet the requirements before the water injection time t reaches t1, water injection will be stopped immediately, and the hydrogen engine's air-fuel ratio will continue to be adjusted using excessive air dilution and exhaust gas recirculation. If abnormal combustion occurs during rapid acceleration, water injection will be started immediately. After the abnormal combustion is eliminated, the air-fuel ratio of the hydrogen engine will continue to be adjusted by excessive air dilution and exhaust gas recirculation. After the air-fuel ratio fluctuation stabilizes within the first set range, the exhaust gas recirculation will switch to the normal EGR mode without an EGR pump until the hydrogen engine is running stably.

5. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 4, characterized in that, The excessive air dilution during rapid acceleration of the hydrogen engine includes the following steps: The appropriate range for the rapid acceleration air-fuel ratio of the hydrogen engine is set to λ''min-λ''max, and the detection value is set to λ3-λ4, where λ''min<λ3<λ4<λ''max; If the measured air-fuel ratio λ'' is greater than λ4 but less than λ''max, then reduce the throttle opening until λ'' is less than λ4; If the measured air-fuel ratio λ'' is less than λ3 but greater than λ''min, then increase the throttle opening to increase the intake air volume until λ'' is greater than λ3.

6. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 4, characterized in that, The exhaust gas recirculation of the hydrogen engine under rapid acceleration conditions includes the following steps: Set the maximum allowable change rate of nitrogen oxide emissions. max Set the nitrogen oxide emission change rate detection value as 1, and 1 < max ; If the current measured value of nitrogen oxide emission change rate Greater than 1 but less than max Immediately activate the transient response EGR mode driven by the EGR pump, increase the EGR valve opening, and improve the EGR rate of the hydrogen engine until... Less than 1; like Less than If 1 is selected, the current acceleration process is determined to be stable, and the normal EGR mode without EGR pump drive is adopted.

7. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 4, characterized in that, The in-cylinder water injection of the hydrogen engine under rapid acceleration conditions includes the following steps: Set the maximum allowable cylinder pressure change rate. max Maximum permissible cylinder temperature change rate max Set cylinder pressure change rate detection value 1. Cylinder temperature change rate detection value 1; If the measured cylinder pressure change rate occurs during the process of excessive air dilution and exhaust gas recirculation... Greater than 1 but less than max Or measured value of cylinder temperature change rate Greater than 1 but less than max In such cases, the water spray system should be activated immediately. Less than 1 and Less than 1. Then repeat the coordinated regulation process of excessive air dilution and exhaust gas recirculation until the hydrogen engine is running stably.

8. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 2, characterized in that, When the hydrogen engine is in a slow acceleration condition, controlling excessive air dilution, exhaust gas recirculation, and in-cylinder water injection includes the following steps: First, the air-fuel ratio of the hydrogen engine is adjusted by using excessive air dilution and exhaust gas recirculation, and the exhaust gas recirculation initially adopts a transient response EGR mode driven by an EGR pump. If abnormal cylinder pressure or cylinder temperature combustion occurs during slow acceleration, water injection will be started immediately. After the abnormal combustion is eliminated, the air-fuel ratio of the hydrogen engine will continue to be adjusted by excessive air dilution and exhaust gas recirculation. After the air-fuel ratio stabilizes within the second set range, the exhaust gas recirculation switches to the normal EGR mode without an EGR pump until the hydrogen engine is running stably.

9. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 8, characterized in that, The excessive air dilution during the slow acceleration of the hydrogen engine includes the following steps: The appropriate range for the slow acceleration air-fuel ratio of the hydrogen engine is set to λ'''min-λ'''max, and the detection value is set to λ5-λ6, where λ'''min<λ5<λ6<λ'''max; If the measured air-fuel ratio λ''' is greater than λ6 but less than λ'''max, then increase the hydrogen injection pulse width until λ''' is less than λ6; If the measured air-fuel ratio λ''' is less than λ5 but greater than λ'''min, then increase the throttle opening to increase the intake air volume until λ''' is greater than λ5.

10. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 8, characterized in that, The exhaust gas recirculation of the hydrogen engine under slow acceleration conditions includes the following steps: The maximum allowable nitrogen oxide emission concentration is set at [NOx]1; If the current measured value of nitrogen oxide concentration [NOx] is greater than [NOx]1, the transient response EGR mode driven by the EGR pump will be activated immediately to increase the opening of the EGR valve and improve the EGR rate of the hydrogen engine until the current measured value of nitrogen oxide emissions is less than [NOx]1. If the measured value of the current nitrogen oxide emissions is less than [NOx]1, it is determined that the current slow acceleration process is stable, and the ordinary EGR mode without EGR pump drive is adopted.

11. The method for transient combustion optimization and nitrogen oxide suppression control of a hydrogen engine according to claim 8, characterized in that, The in-cylinder water injection of the hydrogen engine under the slow acceleration condition includes the following steps: Set the maximum peak cylinder pressure of the slow acceleration condition as Pmax and the maximum peak cylinder temperature as Tmax; If, after air excess dilution and exhaust gas recirculation, the measured cylinder pressure P1 of the hydrogen engine > Pmax or the measured cylinder temperature T1 > Tmax appears, water injection is immediately started until the measured cylinder pressure P1 < Pmax and the measured cylinder temperature T1 < Tmax, and then the coordinated adjustment process of air excess dilution and exhaust gas recirculation is repeated until the hydrogen engine runs stably.

12. A transient combustion optimization and nitrogen oxide suppression control device for a hydrogen engine, applied to the transient combustion optimization and nitrogen oxide suppression control method for a hydrogen engine as described in any one of claims 1 to 11, characterized in that, Includes: A data acquisition module for obtaining the rotational speed change rate and throttle opening change rate of the hydrogen engine within a set time, as well as obtaining the coolant temperature and intake air temperature; A working condition determination module for judging the working condition of the hydrogen engine according to the magnitudes of the rotational speed change rate, throttle opening change rate, coolant temperature, and intake air temperature; An execution module for selecting at least one of air excess dilution, exhaust gas recirculation, and in-cylinder water injection for execution according to the working condition of the hydrogen engine.

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