Anti-backfire control method for a nozzle, hydrogen supply system and hydrogen engine

Abstract

The application relates to a nozzle, a hydrogen supply system and a backfire prevention control method of a hydrogen engine, and is applied to a hydrogen engine. The nozzle comprises a nozzle body, the nozzle body has an inlet end for receiving airflow and an outlet end for spraying the airflow; the outlet end is configured as a Laval tubular structure, the Laval tubular structure comprises a converging section and a diverging section which are connected in communication, and a jet port of the nozzle is formed on one side of the diverging section away from the converging section; the Laval tubular structure is configured to enable the airflow to flow through the converging section and the diverging section in sequence and then increase in flow velocity. The nozzle, the hydrogen supply system and the backfire prevention control method of the hydrogen engine can effectively reduce the backfire risk.

Description

Technical Field

[0001] This application relates to the field of fuel supply technology for engines, and in particular to a nozzle, a hydrogen supply system, and a method for preventing backfire in a hydrogen engine. Background Technology

[0002] With increasing environmental awareness and the depletion of fossil fuel resources, hydrogen fuel has gradually become an emerging research area in the automotive industry. Compared with traditional engines, hydrogen engines have advantages such as zero emissions and high efficiency, thus attracting much attention. However, issues related to the safety, storage, supply, and combustion of hydrogen fuel remain bottlenecks restricting its commercial application. Among these, backfire prevention technology is one of the most critical technologies for solving the application of hydrogen engines.

[0003] Common backfire prevention technologies in the present technology include multi-point injection, decompression backfire prevention, and exhaust gas recirculation. Among them, multi-point injection technology is currently the most widely used. Its principle is that when hydrogen is injected into the engine cylinder, it is simultaneously injected through multiple injectors, forming a high-speed airflow to accelerate combustion and thus reduce the probability of backfire. However, due to engine structural limitations, each injector in the multi-point injection system of related technologies needs to be equipped with a nozzle, and the gas in the injector is injected into the cylinder through the nozzle. However, there is often a certain distance between the nozzle head and the cylinder intake, and hydrogen diffusion often occurs as it travels from the nozzle head to the cylinder intake. Due to the flammable and explosive nature of hydrogen, hydrogen combustion backfire is very likely to occur. Therefore, existing hydrogen engines still have a high risk of backfire. Summary of the Invention

[0004] Therefore, it is necessary to provide a backfire prevention control method for the nozzle, hydrogen supply system, and hydrogen engine to address the high risk of backfire in existing hydrogen engines.

[0005] In a first aspect, this application provides a nozzle for use in a hydrogen supply system of a hydrogen engine. The nozzle includes a nozzle body having an inlet end for receiving airflow and an outlet end for ejecting airflow. The outlet end is constructed as a Laval tubular structure, which includes a converging section and a diverging section connected to each other. The nozzle's air outlet is formed on the side of the diverging section opposite to the converging section. The Laval tubular structure is configured to increase the flow velocity of the airflow after it passes through the converging section and the diverging section in sequence.

[0006] In one embodiment, the nozzle further includes a one-way valve connected to the inlet end, with the nozzle's air inlet formed on the side of the one-way valve opposite to the inlet end. The one-way valve has an airflow passage configured to allow airflow to flow unidirectionally from the nozzle's air inlet to the nozzle's air outlet.

[0007] In one embodiment, the one-way valve is configured as a Tesla valve, comprising a valve body and a valve core. The valve body has a valve cavity, the cavity wall of which has multiple first protrusions arranged circumferentially around the valve cavity wall. Each first protrusion includes a first inclined surface near the air inlet and a first arcuate surface away from the air inlet. The multiple first protrusions are spaced apart sequentially along the axial direction of the valve cavity. The valve core is disposed within the valve cavity, and its outer wall has multiple second protrusions arranged circumferentially around the valve core wall. Each second protrusion includes a second inclined surface near the air inlet and a second arcuate surface away from the air inlet. The multiple second protrusions are spaced apart sequentially along the axial direction of the valve core. The first and second protrusions are staggered along the axial direction of the valve core, and the valve cavity and valve core together define an airflow passage.

[0008] In one embodiment, the nozzle further includes a mounting base, which has a receiving cavity with an opening at one end. The mounting base is sealed to the inlet end and the receiving cavity is in communication with the inlet end. A first flange is provided at the edge of the opening. The valve body is disposed in the receiving cavity through the opening, and the valve core is provided with a second flange. The second flange extends out of the receiving cavity and is connected to the first flange.

[0009] In one embodiment, there are two nozzle bodies, and the inlet end of each nozzle body is sealed and connected to the same side of the mounting base.

[0010] Secondly, this application provides a hydrogen supply system for a hydrogen engine. The hydrogen engine has multiple cylinders, and the hydrogen supply system includes multiple nozzles as described above, a common rail hydrogen injection mechanism, and an intake box. The common rail hydrogen injection mechanism has multiple hydrogen injectors corresponding one-to-one with each nozzle, and each hydrogen injector is connected to a nozzle to inject high-pressure gas flow into the nozzle. The intake box has an intake chamber, and each nozzle is located in the intake chamber. Each nozzle is arranged one-to-one with each cylinder, and the nozzle nozzle is oriented towards the intake valve of the corresponding cylinder.

[0011] In one embodiment, an air intake pipe and an air release valve are arranged opposite to each other on both sides of the air intake box, and both the air intake pipe and the air release valve are connected to the air intake chamber of the air intake box.

[0012] In one embodiment, the intake chamber is further provided with a hydrogen concentration sensor, which is configured to obtain the hydrogen concentration in the intake chamber.

[0013] Thirdly, this application provides a backfire prevention control method for a hydrogen engine. The hydrogen engine includes a hydrogen supply system and cylinders as described above. The backfire prevention control method includes the following steps: causing each hydrogen injector of the common rail hydrogen injection mechanism to inject hydrogen into its corresponding nozzle, and supplying hydrogen to each cylinder through each nozzle.

[0014] In one embodiment, an intake pipe and a vent valve are arranged opposite to each other on both sides of the intake box, and both the intake pipe and the vent valve are connected to the intake chamber of the intake box; the backfire prevention control method further includes the following steps: obtaining the hydrogen concentration in the intake chamber and comparing it with a hydrogen concentration threshold; when the hydrogen concentration in the intake chamber is greater than the hydrogen concentration threshold, opening the vent valve to allow air to enter the intake chamber through the intake pipe and be discharged through the vent valve.

[0015] In one embodiment, the backfire prevention control method further includes the following steps: determining the operating condition of the hydrogen engine, wherein the operating condition of the hydrogen engine is one of idling, partial load, or rated operating condition; when the hydrogen engine is idling, causing each hydrogen injector to continue operating; when the hydrogen engine is under partial load, causing at least two spaced-apart cylinders corresponding to hydrogen injectors to alternately stop operating for a preset time; and when the hydrogen engine is under rated operating condition, causing at least two spaced-apart cylinders corresponding to hydrogen injectors to stop operating simultaneously.

[0016] In one embodiment, the backfire prevention control method further includes the following steps: acquiring the pressure inside the intake chamber and calculating and correcting the intake volume of the intake chamber based on the acquired pressure inside the intake chamber; comparing the corrected intake volume with the intake volume threshold of the intake chamber; and stopping the power supply to each hydrogen injector in the hydrogen supply system when the corrected intake volume is greater than the intake volume threshold.

[0017] In one embodiment, the backfire prevention control method further includes the following steps: obtaining the gas pressure in the cylinder and comparing it with the gas pressure threshold of the cylinder; when the gas pressure in the cylinder is greater than the gas pressure threshold, reducing the injection flow rate of each hydrogen injector in the hydrogen supply system.

[0018] The nozzle, hydrogen supply system, and backfire prevention control method for a hydrogen engine provided in this application utilize a Laval tubular structure at the inlet end of the nozzle body to throttle and accelerate the gas flow injected through the nozzle. This allows the hydrogen gas flow to enter the cylinder rapidly. Simultaneously, the high-speed gas flow creates a localized negative pressure, forming a siphon effect on the gas surrounding the hydrogen flow stream, suppressing the amount of hydrogen diffusing into the intake box, thereby reducing the probability of backfire. Therefore, the backfire prevention control method for the nozzle, hydrogen supply system, and hydrogen engine provided in this application can effectively reduce the backfire risk of hydrogen engines and improve their safety and reliability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the hydrogen supply system provided in the embodiments of this application.

[0020] Figure 2 This is a schematic diagram of the nozzle structure provided in the embodiments of this application.

[0021] Figure 3This is a partial cross-sectional view of the nozzle provided in the embodiments of this application.

[0022] Figure 4 This is a partial enlarged view of the nozzle provided in the embodiments of this application.

[0023] Figure 5 This is a cross-sectional view of the check valve provided in the embodiments of this application.

[0024] Figure 6 This is a schematic diagram illustrating the design principle of the nozzle provided in the embodiments of this application.

[0025] Figure 7 This is a schematic flowchart of the backfire prevention control method for a hydrogen engine provided in the embodiments of this application.

[0026] Reference numerals: 1. Common rail hydrogen injection mechanism; 11. Hydrogen injector; 12. Common rail pipe; 13. First temperature and pressure sensor; 14. Hydrogen inlet connector; 15. Hydrogen delivery pipe; 2. Nozzle; 21. Nozzle body; 21a. Inlet end; 21b. Outlet end; 211. Converging section; 212. Diverging section; 213. Throat; 22. One-way valve; 220. Airflow channel; 221. Valve body; 2211. First protrusion; 222. Valve core; 2221. Second protrusion; 2222. Second flange; 23. Mounting base; 231. First flange; 3. Inlet box; 31. Inlet pipe; 32. Vent valve; 33. Hydrogen concentration sensor; 34. Second pressure sensor; 4. Cylinder; 41. Inlet valve; 42. Third sensor. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0028] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0033] With increasing environmental awareness and the decreasing use of fossil fuels, hydrogen fuel, as a new type of green energy, is gradually attracting attention. In the field of engines, the combustion of hydrogen produces fewer pollutants, but it also presents some problems, one of which is hydrogen backfire.

[0034] In existing technologies, to address the hydrogen backfire problem, methods typically involve reducing the hydrogen injection volume or increasing the oxygen supply. However, these methods often lead to incomplete hydrogen combustion, reducing the performance of the internal combustion engine. Additionally, existing technologies employ additives or complex gas recirculation systems to control hydrogen combustion, but these methods are not only costly but also complex to operate, making widespread application difficult.

[0035] Hydrogen backfire has been a persistent bottleneck in the field of hydrogen fuel cell engines. During combustion, hydrogen can backfire, generating pressure waves that cause engine vibration and noise, and may even damage the engine. Furthermore, hydrogen diffusion increases hydrogen concentration, raising the risk of hydrogen explosion.

[0036] Based on this, on the one hand, this application provides a hydrogen supply system for a hydrogen engine and a nozzle 2 for the hydrogen supply system, so as to reduce the probability of backfire and improve the safety and reliability of the hydrogen engine.

[0037] See Figure 1 , Figure 1 This is a schematic diagram of the hydrogen supply system provided in an embodiment of this application. The hydrogen supply system provided in one embodiment of this application is applied to a hydrogen engine, which has multiple cylinders 4. Specifically, the hydrogen supply system includes a common rail hydrogen injection mechanism 1, nozzles 2, and an air intake box 3. The common rail hydrogen injection mechanism 1 is provided with multiple hydrogen injectors 11 corresponding one-to-one with each nozzle 2. Each hydrogen injector 11 is connected to each nozzle 2 to inject high-pressure gas flow into the nozzle 2. The air intake box 3 has an air intake chamber, and each nozzle 2 is disposed within the air intake chamber. Each nozzle 2 is arranged one-to-one with each cylinder 4, and the nozzle of each nozzle 2 is oriented towards the air intake valve 41 of the corresponding cylinder 4.

[0038] For specific details on what can be achieved, please refer to [link / reference]. Figures 1 to 4 , Figure 2 This is a schematic diagram of the structure of the nozzle 2 provided in the embodiments of this application. Figure 3 This is a partial cross-sectional view of the nozzle 2 provided in the embodiments of this application. Figure 4 The image shown is a partial enlarged view of the nozzle 2 provided in the embodiments of this application. The nozzle 2, applied to the hydrogen supply system of a hydrogen engine, includes a nozzle body 21. The nozzle body 21 has an inlet end 21a for receiving airflow and an outlet end 21b for expelling airflow. The outlet end 21b is constructed as a Laval tube structure, which includes a converging section 211 and a diverging section 212 that are connected. The nozzle 2's nozzle orifice is formed on the side of the diverging section 212 opposite to the converging section 211. The Laval tube structure is configured to increase the flow velocity of the airflow after it sequentially passes through the converging section 211 and the diverging section 212.

[0039] In this design, the nozzle 2 provided in this application has a Laval tube structure at the inlet end 21a of the nozzle body 21 forming the jet nozzle. This structure throttles and accelerates the airflow injected through the nozzle 2, allowing the hydrogen gas flow to enter the cylinder 4 quickly. Simultaneously, the high-speed gas flow creates a localized negative pressure, forming a siphon effect on the gas surrounding the hydrogen flow stream, suppressing hydrogen diffusion into the intake box 3, thereby reducing the probability of backfire. Therefore, the nozzle 2 provided in this application and the hydrogen supply system using this nozzle 2 can effectively reduce the risk of backfire in hydrogen engines and improve the safety and reliability of hydrogen engines.

[0040] This application does not specifically limit the shape of the nozzle body 21, as long as it can realize the function of jetting gas. For example, the nozzle body 21 can be constructed as a cylindrical tubular structure. For example, the end of the nozzle body 21 opposite to the inlet end 21a can be provided with a bend, which forms the outlet end 21b. This application does not specifically limit the cross-sectional dimensions of the nozzle body 21, as long as it can meet the flow requirements of the hydrogen engine. For example, the inner diameter of the nozzle 2 can be in the range of 5-10 mm, preferably 7 mm.

[0041] The nozzle 2 provided in this application, while meeting the hydrogen supply flow requirements of the hydrogen engine, can effectively prevent hydrogen combustion backfire, thereby delaying the closing of the hydrogen engine intake valve 41, achieving the Miller cycle, improving the power of the hydrogen engine, and reducing the operating risks of the hydrogen engine. Furthermore, the nozzle 2 has a simple structure, low cost, high reliability, requires no maintenance, and has a lifespan equivalent to that of the hydrogen engine. It is understood that the nozzle 2 provided in this application is not limited to applications in hydrogen supply systems for hydrogen engines, and also has broad application prospects in other alternative fuel engines or hybrid fuel engines.

[0042] Furthermore, in some embodiments, such as Figure 4 As shown, a throat 213 is formed at the junction of the converging section 211 and the expanding section 212 at the outlet end 21b. When the airflow passes through this throat 213, the flow Mach number is slightly greater than 1, so that the shock wave of the airflow forms on the side of the throat 213 away from the converging section 211, avoiding choking. For example, the cross-sectional dimensions of the throat 213 can be calculated using CFD (Computational Fluid Dynamics) simulation to ensure that the airflow is at a flow Mach number slightly greater than 1 when passing through the throat 213. For example, the difference between the maximum cross-sectional dimension of the converging section 211 and the cross-sectional dimension of the throat 213 can be 0.5-2 mm, preferably 1 mm.

[0043] See Figure 6 , Figure 6This is a schematic diagram of the design principle of the nozzle 2 provided in the embodiment of this application. Figure a shows the change state of the airflow Mach number preset during the design of the nozzle 2. Figure b shows one possible change state of the airflow Mach number during actual use of the nozzle 2. The arrow indicates the flow direction of the airflow from the air inlet to the jet outlet of the nozzle 2. Ma refers to the flow Mach number of the airflow. Region A refers to the area where airflow can flow defined by the tapering section 211. Region B refers to the area where airflow can flow defined by the expanding section 212. Position C refers to the position where the airflow forms a shock wave in the nozzle 2.

[0044] In the hydrogen supply system of this application, the gas flow velocity injected into the nozzle 2 via the hydrogen injector 11 is very high, which is supersonic flow. Therefore, it is considered to be close to isentropic flow, that is, the total pressure loss is zero. For isentropic flow of gas in a variable cross-section pipe, the cross-section with a flow Mach number of 1 is always the cross-section with the smallest pipe cross-sectional area. If the gas flow reaches a Mach number of 1 upstream of the throat 213 cross-section, that is, in the contraction section 211, the required pipe cross-sectional area increases as the gas flows downstream from this position, regardless of whether the flow Mach number increases or decreases. However, this location is actually in the tapering section 211, where the cross-sectional dimensions gradually decrease. At this point, the throat 213 of the nozzle 2 is insufficient to meet the flow rate requirements of all the airflow entering from the nozzle 2's inlet. This forces a change in the airflow state at the nozzle 2's inlet, creating a choked flow and resulting in a significant total pressure loss. The airflow ejected from the nozzle 2 is suppressed, leading to insufficient hydrogen supply. The hydrogen velocity at the nozzle 2's nozzle decreases, further increasing the amount of hydrogen diffusing into the intake box 3 and increasing the risk of backfire. Therefore, during design (such as...) Figure 6 As shown in Figure a), this application achieves a flow Mach number slightly greater than 1 when the airflow passes through the throat 213, ensuring that the shock wave formation location C is within region B. At this point, the airflow transforms into subsonic flow through the shock wave. Since the Mach number before the shock wave is not too large (slightly greater than 1), the total pressure loss caused by the shock wave is not significant. Thus, even in practical applications (such as...), Figure 6 As shown in Figure b), the flow Mach number decreases slightly when the airflow passes through the converging section 211. This only causes the position C of the shock wave to move slightly towards the throat 213, and will not cause a choking flow that slows down the hydrogen flow rate.

[0045] In some embodiments, for example, the outlet end 21b and the inlet end 21a of the nozzle body 21 are integrally formed on the nozzle body 21, resulting in a simple structure and high reliability. For example, the inlet end 21a of the nozzle body 21 is integrally formed on the nozzle body 21, and the outlet end 21b is separately provided from the nozzle body 21. The outlet end 21b is sealed to the side of the nozzle body 21 opposite to the inlet end 21a and communicates with the inlet end 21a. For example, the outlet end 21b and the nozzle body 21 can be sealed by welding, crimping, threaded connection, or other connection methods.

[0046] For further details, please refer to [link / reference]. Figure 2 , Figure 3 and Figure 5 , Figure 5 This is a cross-sectional view of the one-way valve 22 provided in the embodiments of this application. In some embodiments, the nozzle 2 further includes a one-way valve 22, which is connected to the inlet end 21a. The air inlet of the nozzle 2 is formed on the side of the one-way valve 22 away from the inlet end 21a. An airflow channel 220 is constructed inside the one-way valve 22, which is configured to allow the airflow to flow unidirectionally from the air inlet to the jet nozzle of the nozzle 2. In this application, a one-way valve 22 is provided at the inlet end 21a of the nozzle body 21, so that the airflow can flow unidirectionally from the air inlet to the jet nozzle of the nozzle 2. When backfire occurs, the pressure wave generated by the flame is blocked by the one-way valve 22, and the flame cannot flow back into the upstream components, thereby protecting the upstream components, further reducing the risk of engine backfire, and improving safety and reliability.

[0047] In some embodiments, the one-way valve 22 is configured as a Tesla valve, which, through a fixed structure, enables the airflow to flow unidirectionally from the air inlet of the nozzle 2 to the jet outlet, thereby protecting upstream components during tempering.

[0048] For specific details on what can be achieved, please refer to [link / reference]. Figure 5The one-way valve 22 includes a valve body 221 and a valve core 222. The valve body 221 has a valve cavity, and the cavity wall is provided with a plurality of first protrusions 2211. Each first protrusion 2211 is arranged circumferentially along the cavity wall. Each first protrusion 2211 includes a first inclined surface near the air inlet and a first arcuate surface away from the air inlet. The plurality of first protrusions 2211 are arranged sequentially at intervals along the axial direction of the valve cavity. The valve core 222 is disposed within the valve cavity. The outer wall of the valve core 222 is provided with a plurality of second protrusions 2221. Each second protrusion 2221 is arranged circumferentially along the outer wall of the valve core 222. Each second protrusion 2221 includes a second inclined surface near the air inlet and a second arcuate surface away from the air inlet. The plurality of second protrusions 2221 are arranged sequentially at intervals along the axial direction of the valve core 222. Each first protrusion 2211 and each second protrusion 2221 are staggered along the axial direction of the valve core 222, and the valve cavity of the valve body 221 and the valve core 222 together define the airflow passage 220. In this embodiment, the valve body 221 and the valve core 222 together form a Tesla valve, which is easy to assemble, has high reliability, and the relative position between the valve body 221 and the valve core 222 can be adjusted to improve the unidirectional flow effect of the airflow.

[0049] For example, the Tesla valve can also be a one-piece molded configuration, with the airflow channel 220 formed inside the Tesla valve. Preferably, the Tesla valve can be manufactured using a precision casting process, resulting in high reliability.

[0050] For further details, please refer to [link / reference]. Figure 2 , Figure 3 and Figure 5 In some embodiments, the nozzle 2 further includes a mounting base 23 for mounting the nozzle body 21. Specifically, the mounting base 23 has a receiving cavity with an opening at one end. The mounting base 23 is sealed to the inlet end 21a, and the receiving cavity communicates with the inlet end 21a. A first flange 231 is provided at the edge of the opening. The valve body 221 is disposed in the receiving cavity through the opening, and the valve core 222 has a second flange 2222. The second flange 2222 extends out of the receiving cavity and is connected to the first flange 231. The mounting base 23 not only facilitates the installation of the nozzle 2 but also enables the nozzle body 21 and the one-way valve 22 to form an integral structure, improving the reliability of the application.

[0051] This application does not specifically limit the connection method between the nozzle body 21 and the mounting base 23. For example, the inlet end 21a of the nozzle body 21 can be welded to the side of the mounting base 23 away from the opening of the accommodating cavity to achieve a sealed connection between the two. Preferably, the inlet end 21a can be welded to the mounting base 23 into an integral structure by argon arc welding.

[0052] For example, the check valve 22 can also be disposed outside the mounting base 23, and the check valve 22 and the mounting base 23 are connected by a transition flange.

[0053] In some embodiments, see Figure 2 and Figure 3 The nozzle body 21 has two parts, and the inlet end 21a of each nozzle body 21 is sealed and connected to the same side of the mounting base 23. On one hand, having two nozzle bodies 21 for one nozzle 2 increases the injected gas flow, more fully meeting the hydrogen flow requirements of the hydrogen engine. On the other hand, in some applications, each cylinder 4 of the hydrogen engine has two intake valves 41, and the nozzle 2 has two nozzle bodies 21, each corresponding to an intake valve 41. This allows the nozzle nozzle 2's nozzle outlet to be as close as possible to its corresponding intake valve 41, minimizing the distance the injected hydrogen travels to the cylinder 4, thus shortening the hydrogen flow path time, reducing hydrogen overflow from the cylinder 4, and lowering the probability of backfire. For example, the distance between the nozzle nozzle 2's nozzle outlet and its corresponding intake valve 41 can range from 0-50 mm, preferably 20-30 mm.

[0054] It is understood that in the nozzle 2 provided in this application, the number of nozzle bodies 21 can also be set to one, and the inlet end 21a of the nozzle body 21 is sealed to one side of the mounting base 23.

[0055] Furthermore, in some embodiments, see [reference] Figure 1 The common rail hydrogen injection mechanism 1 also includes a common rail pipe 12, a first temperature and pressure sensor 13, a hydrogen inlet connector 14, and a hydrogen delivery pipe 15. The common rail pipe 12 ensures a consistent hydrogen supply pressure before the hydrogen enters each hydrogen injector 11. Specifically, the multiple hydrogen injectors 11 are all connected to the common rail pipe 12 and are spaced apart along the axial direction of the common rail pipe 12. The common rail pipe 12 is equipped with a hydrogen inlet connector 14, through which hydrogen enters the common rail pipe 12 to form a certain hydrogen supply pressure, and then flows into each hydrogen injector 11. Furthermore, the common rail pipe 12 is also equipped with a first temperature and pressure sensor 13, which can be used to detect the gas pressure and temperature inside the common rail pipe 12, so as to control the hydrogen supply flow rate based on the gas pressure and temperature inside the common rail pipe 12. Furthermore, multiple hydrogen supply pipes 15 are provided, each hydrogen supply pipe 15 is connected between the hydrogen injector 11 and the air inlet of the nozzle 2, so that each hydrogen injector 11 can supply gas to each nozzle 2.

[0056] In some embodiments, see Figure 1In the hydrogen supply system provided in this application, an inlet pipe 31 and a vent valve 32 are arranged opposite to each other on both sides of the inlet box 3. Both the inlet pipe 31 and the vent valve 32 are connected to the inlet chamber of the inlet box 3. The inlet pipe 31 provides a passage for air to enter the inlet chamber, and the vent valve 32 is opened when the hydrogen concentration in the inlet chamber is abnormal, so that the air entering through the inlet pipe 31 can flow out through the vent valve 32. Exemplarily, the inlet pipe 31 can be integrally formed with the inlet box 3, or it can be detachably connected to the inlet box 3. Exemplarily, the vent valve 32 can be a solenoid valve.

[0057] In some embodiments, see Figure 1 The intake chamber 3 is also equipped with a hydrogen concentration sensor 33, which is configured to acquire the hydrogen concentration in the intake chamber to determine whether the vent valve 32 needs to be opened. For example, the hydrogen concentration sensor 33 can be used to detect the average hydrogen concentration or the instantaneous hydrogen concentration in the intake chamber.

[0058] In some embodiments, see Figure 1 The air intake box 3 is also equipped with a second pressure sensor 34, which is configured to detect the air pressure in the air intake chamber in order to monitor the air intake volume in the air intake chamber.

[0059] Because the hydrogen supply system and nozzle 2 provided in this application can achieve hydrogen rectification and high-speed gas jet injection, they effectively suppress hydrogen diffusion and backfire. This technical solution has high practicality and feasibility and can be widely applied in the fields of internal combustion engines, fuel injection systems, and nozzles. Meanwhile, with increasing environmental awareness and the demand for green energy, hydrogen fuel, as a new type of fuel, is experiencing growing market demand. Therefore, the technical solution of this application has broad market and application prospects in the fields of hydrogen fuel cell internal combustion engines, automobiles, and power generation.

[0060] On the other hand, this application also provides a backfire prevention control method for a hydrogen engine, wherein the hydrogen engine includes the hydrogen supply system mentioned in any of the above embodiments and a plurality of cylinders 4. See also Figure 7 , Figure 7 This is a flowchart illustrating the backfire prevention control method for a hydrogen engine provided in this application embodiment. Specifically, the backfire prevention control method includes the following steps:

[0061] S1: The hydrogen injectors 11 of the common rail hydrogen injection mechanism 1 inject hydrogen into the corresponding nozzles 2, and the nozzles 2 supply hydrogen to the cylinders 4.

[0062] In this scheme, because the nozzle 2 in the gas supply system of this application has a Laval tube structure at the inlet end 21a of the nozzle body 21 forming the jet nozzle, it generates a throttling and acceleration effect on the airflow injected through the nozzle 2, allowing the hydrogen gas flow to enter the cylinder 4 quickly. At the same time, the high-speed flowing gas generates a negative pressure locally, forming a siphon effect on the gas around the hydrogen flow stream, suppressing the amount of hydrogen diffused into the intake box 3, thereby reducing the probability of backfire. Therefore, the backfire prevention control method of the hydrogen engine of this application, by injecting hydrogen into the cylinder 4 through the nozzle 2, can reduce the diffusion of hydrogen into the intake box 3, effectively reduce the risk of backfire in the hydrogen engine, and improve the safety and reliability of the hydrogen engine.

[0063] Specifically, hydrogen enters the common rail 12 via the hydrogen supply pipe 15 of the common rail hydrogen injection mechanism 1, and is then distributed by the common rail 12 to each hydrogen supplier. Each hydrogen supplier injects hydrogen into the nozzle 2 through the hydrogen supply pipe 15. Alternatively, hydrogen can be directly injected into the nozzle 2 by the hydrogen injector 11. For example, the first temperature and pressure sensor 13 can acquire the gas pressure and temperature within the common rail 12 to determine and control the hydrogen intake rate.

[0064] For further details, please refer to [link / reference]. Figure 7 In some embodiments, an intake pipe 31 and a vent valve 32 are arranged opposite to each other on both sides of the intake box 3, and both the intake pipe 31 and the vent valve 32 are connected to the intake chamber of the intake box 3. The above-mentioned backfire prevention control method further includes the following steps:

[0065] S2: Obtain the hydrogen concentration in the intake chamber and compare it with the hydrogen concentration threshold.

[0066] S3: When the hydrogen concentration in the intake chamber is greater than the hydrogen concentration threshold, open the vent valve 32 to allow air to enter the intake chamber through the intake pipe 31 and be discharged through the vent valve 32.

[0067] In this embodiment, when the hydrogen concentration in the intake chamber exceeds the hydrogen concentration threshold, it indicates that a large amount of hydrogen has entered the intake box 3, posing a significant risk of backfire. At this time, the vent valve 32 is opened, and fresh air enters the intake chamber through the intake pipe 31 and is discharged through the vent valve 32 to purge the intake chamber, thereby reducing the hydrogen concentration in the intake chamber to within the hydrogen combustion limit and ensuring that the hydrogen in the intake chamber will not burn, thus further reducing the risk of backfire.

[0068] For example, a hydrogen concentration sensor 33 may be installed inside the intake chamber 3. This hydrogen concentration sensor 33 can be used to detect the average hydrogen concentration or the instantaneous hydrogen concentration in the intake chamber. When the hydrogen concentration sensor 33 detects the average hydrogen concentration in the intake chamber, the hydrogen concentration threshold can be 4%. When the average hydrogen concentration in the intake chamber is greater than 4%, the vent valve 32 is opened. Alternatively, when the hydrogen concentration sensor 33 detects the instantaneous hydrogen concentration in the intake chamber, the hydrogen concentration threshold can be 7%. When the instantaneous hydrogen concentration in the intake chamber is greater than 7%, the vent valve 32 is opened.

[0069] In some embodiments, the backfire prevention control method further includes the following steps:

[0070] S2': Determine the exhaust frequency of the intake box 3;

[0071] S3': Open the vent valve 32 for a preset time according to the exhaust frequency of the intake box 3, so that air enters the intake chamber through the intake pipe 31 and is discharged through the vent valve 32.

[0072] In this embodiment, based on the actual data of the hydrogen engine's operation during bench testing, the required exhaust frequency for the intake chamber 3 is determined. At this exhaust frequency, the hydrogen concentration in the intake chamber is consistently kept below the hydrogen explosion limit, i.e., below 4%. Then, in conjunction with specific operating conditions, the vent valve 32 is opened periodically for a preset time according to the determined exhaust frequency, allowing air to enter the intake chamber through the intake pipe 31 and be discharged through the vent valve 32, thereby purging the intake chamber and reducing the risk of backfire.

[0073] For further details, please refer to [link / reference]. Figure 7 In some implementations, the backfire prevention control method also includes the following steps:

[0074] S4: Determine the operating condition of the hydrogen engine, which is one of the following: idling, partial load, or rated operating conditions.

[0075] When the hydrogen engine is idling, each hydrogen injector 11 continues to work.

[0076] When the hydrogen engine is under partial load, the hydrogen injectors 11 corresponding to at least two phase-separated cylinders 4 are alternately stopped for a preset time.

[0077] When the hydrogen engine is in rated operating condition, the hydrogen injectors 11 corresponding to at least two spaced cylinders 4 will stop working simultaneously.

[0078] In this embodiment, by controlling the hydrogen injection quantity of the hydrogen injector 11 according to the operating conditions of the hydrogen engine, the diffusion of hydrogen into the intake box 3 can be further reduced, thus lowering the probability of backfire. Specifically, this step can be performed simultaneously with step S3, or separately. When steps S3 and S4 are performed simultaneously, on the one hand, the intake chamber of the intake box 3 is purged through the intake pipe 31 and the vent valve 32; on the other hand, under the condition that the operating conditions of the hydrogen engine allow, some hydrogen injectors 11 are stopped to reduce the amount of hydrogen injected, thereby reducing the amount of hydrogen diffusion, further reducing the risk of backfire, and ensuring the safety and reliability of the hydrogen engine. For example, in order to further save energy, while stopping the hydrogen injector 11, the piston in the cylinder 4 corresponding to the hydrogen injector 11 can also be stopped, thus achieving fuel cut-off and cylinder deactivation of cylinder 4.

[0079] For example, the hydrogen engine can be a six-cylinder engine, including six cylinders 4. Correspondingly, the air intake box 3 is provided with six nozzles 2, each nozzle 2 being configured to correspond to the air intake of one of the cylinders 4, and each nozzle 2 being connected to a hydrogen injector 11 for injecting hydrogen into the nozzle 2. Along the arrangement direction of the cylinders 4, the cylinders 4 can be sequentially defined as cylinder 1, cylinder 2, cylinder 3, cylinder 4, cylinder 5, and cylinder 6.

[0080] In step S4 above, specifically, when the hydrogen engine is determined to be idling, the engine speed is low and the amount of hydrogen injected by the hydrogen supply system is very small. Therefore, during intake chamber purging, cylinder 4 of the hydrogen engine is not cut off from fuel supply to prevent unstable engine idling and potential stalling.

[0081] When a hydrogen engine operates under partial load, the engine speed is typically between 1000-1400 rpm, which is relatively high, resulting in a relatively large amount of hydrogen injected by the hydrogen supply system. Therefore, during intake chamber purging, cylinders 1 and 3 of the hydrogen engine can be alternately deactivated by fuel cutoff to reduce hydrogen diffusion. It is understandable that when the hydrogen engine operates under partial load, alternative fuel cutoffs could be made for cylinders 1, 3, and 5, or cylinders 2 and 4, or cylinders 2, 4, and 6, as long as the selected cylinder 4 consists of at least two spaced-apart cylinders, ensuring that the piston in that cylinder stops moving without affecting the balance of the other pistons.

[0082] When the hydrogen engine is operating at its rated speed, the engine speed is generally around 1800 rpm. This high speed results in a large hydrogen injection volume from the hydrogen supply system. Therefore, during intake box purging, cylinders 1 and 3 can be simultaneously deactivated to reduce hydrogen diffusion. It is understandable that, when the hydrogen engine is operating at its rated speed, cylinders 1, 3, and 5 can also be deactivated simultaneously, or cylinders 2 and 4, or cylinders 2, 4, and 6, as long as the selected cylinders are at least two spaced apart, ensuring that the piston in that cylinder stops moving and does not affect the balance of the other piston movements.

[0083] It is understood that the backfire prevention control method of this application can also be applied to single-cylinder engines, two-cylinder engines, three-cylinder engines, four-cylinder engines, or engines with other numbers of cylinders.

[0084] Furthermore, in some embodiments, the backfire prevention control method of this application further includes the following steps:

[0085] S5: Obtain the pressure inside the intake chamber and calculate and correct the intake volume of the intake chamber based on the obtained pressure inside the intake chamber.

[0086] S6: Compare the corrected intake volume with the intake volume threshold of the intake chamber;

[0087] S7: When the corrected intake volume is greater than the intake volume threshold, stop supplying power to each hydrogen injector 11 in the hydrogen supply system.

[0088] In this implementation step, when the intake volume obtained from the acquired intake chamber pressure exceeds the set intake volume threshold, it indicates that backfire has occurred. At this time, the hydrogen injector is powered off to cut off the gas source and suppress backfire, thereby protecting upstream components such as the common rail hydrogen injection mechanism 1 and improving the safety and reliability of the hydrogen engine. A second pressure sensor 34 can be installed on the intake box 3 to acquire the pressure inside the intake chamber.

[0089] Furthermore, in some embodiments, the backfire prevention control method further includes the following steps:

[0090] S8: Obtain the air pressure inside cylinder 4 and compare it with the air pressure threshold of cylinder 4;

[0091] S9: When the gas pressure in cylinder 4 is greater than the gas pressure threshold, reduce the injection flow rate of each hydrogen injector 11 in the hydrogen supply system.

[0092] In this embodiment, when the pressure inside cylinder 4 exceeds a pressure threshold, it indicates abnormal hydrogen combustion and a risk of backfire. Reducing the injection flow rate of the hydrogen injector 11 at this time stabilizes the combustion within the cylinder, eliminates the risk of backfire in advance, and further improves the safety and reliability of the hydrogen engine. For example, the hydrogen engine includes a cylinder block, with multiple cylinders 4 formed within it. A third sensor 42 may be installed on the cylinder block to detect the pressure inside each cylinder 4. For example, the third sensor 42 may be a knock sensor, which obtains the vibration acceleration of the cylinder 4 and uses this vibration acceleration to obtain the pressure inside the cylinder 4. For example, the third sensor 42 may also be a pressure sensor.

[0093] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0094] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A nozzle for use in a hydrogen supply system of a hydrogen engine, characterized in that, The nozzle includes a nozzle body having an inlet end for receiving airflow and an outlet end for ejecting airflow. The outlet end is constructed as a Laval tubular structure, which includes a converging section and a diverging section connected to each other. A throat is formed at the junction of the converging and diverging sections. The cross-section of the throat is matched by CFD simulation to ensure that the Mach number of the airflow is greater than 1 when it passes through the throat, and that the shock wave falls entirely inside the diverging section to avoid choking and reducing the hydrogen jet velocity. The nozzle's jet outlet is formed on the side of the diverging section opposite to the converging section. The Laval tubular structure is configured to increase the velocity of the airflow after it passes through the converging and diverging sections sequentially. The high-speed flowing gas generates a local negative pressure, creating a siphon effect on the gas surrounding the hydrogen jet, thus inhibiting hydrogen diffusion into the intake box. The nozzle also includes a one-way valve connected to the inlet end. The air inlet of the nozzle is formed on the side of the one-way valve away from the inlet end. The one-way valve has an airflow channel configured to allow the airflow to flow unidirectionally from the air inlet of the nozzle to the jet nozzle. The one-way valve is configured as a Tesla valve, the one-way valve comprising: A valve body having a valve cavity, the valve cavity wall having a plurality of first protrusions, each first protrusion being arranged circumferentially around the valve cavity wall, each first protrusion including a first inclined surface near the air inlet and a first arcuate surface away from the air inlet, the plurality of first protrusions being sequentially spaced along the axial direction of the valve cavity; and A valve core is disposed in the valve cavity. The outer wall of the valve core is provided with a plurality of second protrusions. Each second protrusion is arranged circumferentially along the outer wall of the valve core. Each second protrusion includes a second inclined surface near the air inlet and a second arc surface away from the air inlet. The plurality of second protrusions are arranged sequentially at intervals along the axial direction of the valve core. Each of the first protrusions and each of the second protrusions are arranged alternately along the axial direction of the valve core, and the valve cavity of the valve body and the valve core together define the airflow passage; The nozzle also includes a mounting base, which has a receiving cavity with an opening at one end. The mounting base is sealed to the inlet end and the receiving cavity is in communication with the inlet end. A first flange is provided at the edge of the opening. The valve body is disposed in the receiving cavity through the opening. The valve core is provided with a second flange, which extends out of the receiving cavity and is connected to the first flange.

2. The nozzle according to claim 1, characterized in that, The number of nozzle bodies is two; The inlet end of each nozzle body is sealed and connected to the same side of the mounting base.

3. A hydrogen supply system for use in a hydrogen engine, the hydrogen engine having multiple cylinders, characterized in that, The hydrogen supply system includes: Multiple nozzles as described in any one of claims 1-2; A common rail hydrogen injection mechanism is provided, wherein the common rail hydrogen injection mechanism is provided with a plurality of hydrogen injectors corresponding one to one with the nozzle, and each of the hydrogen injectors is connected to each of the nozzles to inject high-pressure gas flow into the nozzle. An air intake box has an air intake chamber, and each of the nozzles is disposed in the air intake chamber. Each of the nozzles is arranged in a one-to-one correspondence with each of the cylinders, and the air outlet of each nozzle is respectively set toward the air intake valve of the corresponding cylinder.

4. The hydrogen supply system according to claim 3, characterized in that, An air intake pipe and an air release valve are arranged opposite each other on both sides of the air intake box, and both the air intake pipe and the air release valve are connected to the air intake chamber of the air intake box.

5. The hydrogen supply system according to claim 3, characterized in that, The air intake chamber is also equipped with a hydrogen concentration sensor, which is configured to obtain the hydrogen concentration in the air intake chamber.

6. A method for preventing backfire in a hydrogen engine, the hydrogen engine comprising a hydrogen supply system as described in any one of claims 3-5 and a cylinder, characterized in that, The backfire prevention control method includes the following steps: The hydrogen injectors of the common rail hydrogen injection mechanism inject hydrogen into their corresponding nozzles, and the nozzles supply hydrogen to the cylinders.

7. The backfire prevention control method for a hydrogen engine according to claim 6, characterized in that, An intake pipe and a vent valve are arranged opposite each other on both sides of the intake box, and both the intake pipe and the vent valve are connected to the intake chamber of the intake box; the backfire prevention control method further includes the following steps: The hydrogen concentration in the air intake chamber is obtained and compared with a threshold value for hydrogen concentration. When the hydrogen concentration in the air intake chamber is greater than the hydrogen concentration threshold, the vent valve is opened to allow air to enter the air intake chamber through the air intake pipe and be discharged through the vent valve.

8. The backfire prevention control method for a hydrogen engine according to claim 7, characterized in that, The backfire prevention control method further includes the following steps: The operating condition of the hydrogen engine is determined, which is one of the following: idling condition, partial load condition, or rated condition. When the hydrogen engine is in idling mode, each of the hydrogen injectors continues to operate. When the hydrogen engine is in partial load operation, the hydrogen injectors corresponding to at least two phase-spaced cylinders are alternately stopped for a preset time. When the hydrogen engine is in rated operating condition, the hydrogen injectors corresponding to at least two spaced-apart cylinders simultaneously stop working.

9. The backfire prevention control method for a hydrogen engine according to claim 8, characterized in that, The backfire prevention control method further includes the following steps: The pressure inside the intake chamber is obtained, and the intake volume of the intake chamber is calculated and corrected based on the obtained pressure inside the intake chamber. The corrected intake volume is compared with the intake volume threshold of the intake chamber; When the corrected intake volume is greater than the intake volume threshold, power supply to each of the hydrogen injectors in the hydrogen supply system is stopped.

10. The backfire prevention control method for a hydrogen engine according to claim 9, characterized in that, The backfire prevention control method further includes the following steps: The air pressure inside the cylinder is obtained and compared with the air pressure threshold of the cylinder; When the gas pressure in the cylinder is greater than the gas pressure threshold, the injection flow rate of each hydrogen injector in the hydrogen supply system is reduced.

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