Natural gas and gasoline dual-fuel engine nozzle arrangement structure and control method

Abstract

The invention discloses a nozzle arrangement structure of a natural gas and gasoline dual-fuel engine. The nozzle arrangement structure comprises a natural gas common rail, a plurality of natural gas nozzle assemblies, a gasoline common rail and a plurality of gasoline nozzle assemblies. The natural gas common rail is communicated with the plurality of groups of natural gas nozzle assemblies, and the gasoline common rail is communicated with the plurality of groups of gasoline nozzle assemblies; the natural gas common rail and the gasoline common rail are arranged on the upper side and the lower side of an engine intake manifold in parallel. The number of the natural gas nozzle assemblies is the same as that of the gasoline nozzle assemblies, the number of the natural gas nozzle assemblies is the same as that of cylinders of an engine, the natural gas nozzle assemblies are arranged above the intake manifold, and the gasoline nozzle assemblies are arranged below the intake manifold. And the natural gas nozzle assembly and the gasoline nozzle assembly are both communicated with the intake manifold.

Description

Technical Field

[0001] This invention relates to the field of dual-fuel engine technology, and in particular to a nozzle arrangement structure and control method for a natural gas and gasoline dual-fuel engine. Background Technology

[0002] In the field of automotive powertrains, both natural gas engines and gasoline engines are widely used due to their respective characteristics, but both have significant limitations. Pure natural gas engines mostly employ port injection or direct injection, offering advantages such as low fuel cost and clean emissions, but they suffer from reduced power (e.g., power loss), inconvenient fuel transport, and insufficient refueling infrastructure, limiting their application scenarios. Pure gasoline engines are technologically mature, offer fast power response, and are convenient to refuel, but their fuel economy is relatively poor, and their combustion emissions of CO, HC, and NO... x Natural gas produces more pollutants and is heavily reliant on high-octane fuels. Under the dual pressures of fuel costs and environmental regulations, its limitations are becoming increasingly apparent. To balance the advantages of both, dual-fuel engines have emerged, aiming to combine the economy and cleanliness of natural gas with the power and refueling convenience of gasoline.

[0003] However, existing dual-fuel systems mostly employ a parallel fuel-gas injection structure, which still suffers from numerous technical shortcomings. Firstly, the fuel injection system layout is chaotic, the intake manifold structure is complex, and interference between different fuel lines and components leads to low utilization of engine compartment space, increasing layout complexity and subsequent maintenance costs. Secondly, the two fuel injection points often share the same common rail, causing premature or uneven mixing of natural gas and gasoline, disrupting the injection characteristics of each fuel, reducing combustion efficiency, and consequently affecting engine power output and fuel economy. Thirdly, poor component compatibility in modified vehicles, difficult and costly installation, weakens the promotional value of dual-fuel technology in existing models. In summary, existing dual-fuel engines still have shortcomings in terms of structural layout, combustion efficiency, and modification adaptability. There is an urgent need for a technical solution that optimizes the fuel injection structure, improves space utilization, ensures combustion efficiency, and facilitates modification, in order to promote the performance upgrade and large-scale application of dual-fuel engines.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] The purpose of this invention is to propose a nozzle arrangement structure and control method for a natural gas and gasoline dual-fuel engine, so as to solve the structural defects of fuel mixing interference and chaotic spatial layout, as well as the technical problems of abrupt switching and low cold start reliability in the prior art.

[0006] Therefore, this invention proposes a nozzle arrangement structure for a dual-fuel engine that can operate on both natural gas and gasoline.

[0007] Preferably, the present invention may also have the following technical features:

[0008] A nozzle arrangement structure for a natural gas and gasoline dual-fuel engine includes: a natural gas common rail, several sets of natural gas nozzle assemblies, a gasoline common rail, and several sets of gasoline nozzle assemblies; the natural gas common rail is connected to several sets of natural gas nozzle assemblies, and the gasoline common rail is connected to several sets of gasoline nozzle assemblies; the natural gas common rail and the gasoline common rail are arranged parallel to each other on the upper and lower sides of the engine intake manifold; the number of natural gas nozzle assemblies and gasoline nozzle assemblies is the same and consistent with the number of cylinders in the engine; the natural gas nozzle assemblies are located above the intake manifold, and the gasoline nozzle assemblies are located below the intake manifold, and both the natural gas nozzle assemblies and the gasoline nozzle assemblies are connected to the intake manifold.

[0009] Preferably, the natural gas common rail is located above the intake manifold, and the gasoline common rail is located below the intake manifold, with both extending along the arrangement direction of the engine cylinders.

[0010] Preferably, the natural gas nozzle assembly injects natural gas into the inner wall of the intake manifold, and the fuel jet ejected by the gasoline nozzle assembly is injected into the combustion chamber through the intake passage.

[0011] Preferably, it further includes a first mounting bracket and a second mounting bracket; the natural gas nozzle assembly is fixed to the upper region outside the intake pipe via the first mounting bracket, and the gasoline nozzle assembly is fixed to the lower region outside the intake pipe via the second mounting bracket; both the first mounting bracket and the second mounting bracket are adapted to and connected to the outer wall of the intake pipe.

[0012] Preferably, the first mounting bracket and the second mounting bracket are fixedly connected to the outer wall of the air intake pipe by bolts or snap-fit ​​structures.

[0013] Preferably, both the natural gas common rail and the gasoline common rail are connected to the fuel supply system via flexible hoses.

[0014] Preferably, the flexible hose has the characteristics of high pressure resistance and oil / gas corrosion resistance, and the connection part of the flexible hose with the natural gas common rail or the gasoline common rail is provided with a sealing structure.

[0015] A method for controlling the nozzle of a natural gas and gasoline dual-fuel engine, based on the aforementioned nozzle arrangement structure for a natural gas and gasoline dual-fuel engine, includes the following steps:

[0016] S01. Signal Acquisition: The ECU acquires the natural gas pressure signal through a preset pressure sensor, which is located between the inlet of the high-pressure regulator of the CNG transmission system and the CNG cylinder; at the same time, the ECU acquires the gasoline level signal through a preset liquid level sensor, which is located inside the gasoline tank.

[0017] S02. Remaining Amount Calculation: Based on the natural gas pressure signal collected by S01, the ECU calculates the remaining amount of natural gas that can be supplied by the common rail; based on the gasoline level signal, it calculates the remaining amount of gasoline that can be supplied by the common rail.

[0018] S03. Parameter Configuration and Switching Control: The ECU acquires and stores the preferred fuel type and fuel switching threshold, which is matched with the injection requirements of the corresponding fuel injector assembly. When the remaining amount of the preferred fuel is lower than the switching threshold, the ECU performs a "cut-off-activation" timing control: first, the common rail supply path of the preferred fuel and the injection control of the corresponding injector assembly are cut off, and then the common rail supply path of the other fuel and the injection control of the corresponding injector assembly are activated. The physical isolation structure of the two sets of injector assemblies placed on the upper and lower sides of the intake manifold avoids the mixing of the two fuels.

[0019] Preferably, the control timing of "cut off first and then activate" in S03 is as follows: after the ECU controls the current fuel injector assembly to stop injecting, it activates another fuel injector assembly after an interval of 50-100ms. Combined with the structure of natural gas injectors and gasoline injectors being placed on the upper and lower sides of the intake manifold, fuel mixing and interference in the intake manifold are completely avoided.

[0020] Preferably, it also includes an optimized switching step for operating condition adaptation, triggered by the ECU based on engine operating conditions, specifically including:

[0021] (1) Cold start phase: The ECU prioritizes the gasoline injector assembly to perform direct injection. After the engine coolant temperature is ≥70℃ or the speed is stable at 800-1000rpm, it automatically switches to the natural gas injector assembly to perform premixed injection according to the logic of S03.

[0022] (2) Normal operation phase: The ECU executes steps S01-S03 in a cycle and updates the remaining amount data in real time. When the remaining amount of priority fuel rises back to above the switching threshold, it can automatically switch back to priority fuel injection.

[0023] (3) Endurance guarantee stage: When the ECU receives the manual switching command, it directly switches to another fuel injector assembly according to the timing control of S03 without adjusting the injector arrangement structure.

[0024] The beneficial effects of this invention compared to the prior art include:

[0025] 1. This application utilizes a core structure in which natural gas common rail and gasoline common rail are placed parallel to each other on the upper and lower sides of the intake manifold, and the nozzle assemblies are placed on the upper and lower sides corresponding to the number of cylinders, both of which are connected to the intake manifold. This structure enables the two fuel injection systems to be completely physically isolated, eliminating mixing interference caused by crossover of fuel supply or injection paths from the source. At the same time, it makes full use of the unused space on the upper and lower sides of the intake manifold, avoids pipe entanglement, improves the utilization rate of engine compartment space, and significantly reduces the integration difficulty of the dual-fuel system.

[0026] 2. In this application, the two fuels are connected to their respective nozzle assemblies via independent common rails, and the number of nozzle assemblies is the same as the number of cylinders, forming a structural basis of "one cylinder with two fuels and independent supply". This ensures that each fuel is accurately delivered to the corresponding cylinder through a dedicated passage, avoiding uneven fuel distribution caused by a shared passage. The dual common rails extend parallel to the cylinder arrangement direction, so that the pressure difference between the nozzles of each cylinder is ≤0.1MPa, significantly improving the consistency of combustion state and effectively avoiding engine vibration.

[0027] 3. The structure of this application does not require modification of the engine body or the core structure of the intake manifold. Upgrades can be completed simply by adding common rail and nozzle components externally. The "separate upper and lower, independently connected" layout is compatible with more than 80% of gasoline engine intake manifolds on the market. The modular component design simplifies the assembly process, reduces installation time by 50%, and significantly reduces the cost of new model configurations and existing vehicle retrofits.

[0028] 4. The control method of this application, through the core steps of pressure / liquid level signal acquisition and remaining quantity calculation, enables the ECU to accurately identify the fuel supply status. Combined with the timing control of "cut off first and then activate", and the physical isolation of the structure, it ensures that the two fuel injections do not overlap and there is no residual mixing. The engine speed fluctuation during switching is ≤50rpm, which completely solves the pain points of the existing dual-fuel system switching jerks and combustion disorder.

[0029] 5. The control method of this application adopts a working condition adaptation logic that prioritizes gasoline direct injection for cold start and natural gas premixing for normal operation. It takes advantage of the easy ignition of gasoline to achieve a cold start success rate of over 98% at -20℃, while also giving full play to the economic advantages of natural gas, reducing fuel usage costs for normal operation by 60%. At the same time, it supports automatic and manual switching, adapts to complex refueling scenarios, and greatly improves the flexibility of driving range. Attached Figure Description

[0030] Figure 1 This is a front view of a specific embodiment of the present invention.

[0031] Figure 2 This is the present invention. Figure 1A cross-sectional view taken along section GG.

[0032] Figure 3 This is a first axonometric view of a specific embodiment of the present invention.

[0033] Figure 4 This is a second axonometric view of a specific embodiment of the present invention.

[0034] Figure 5 This is a flowchart of a second specific embodiment of the present invention.

[0035] Explanation of reference numerals in the attached drawings: 1-Common rail for natural gas; 2-Natural gas nozzle assembly; 3-Common rail for gasoline; 4-Gas nozzle assembly; 5-Intake manifold; 6-First mounting bracket; 7-Second mounting bracket; 8-Intake pipe. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope or application of the present invention.

[0037] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0038] Example 1:

[0039] like Figure 1 and Figure 2As shown, the nozzle arrangement structure of the natural gas and gasoline dual-fuel engine provided in this embodiment specifically includes a natural gas common rail 1, several sets of natural gas nozzle assemblies 2, a gasoline common rail 3, and several sets of gasoline nozzle assemblies 4. The natural gas common rail 1 is connected to several sets of natural gas nozzle assemblies 2, and the gasoline common rail 3 is connected to several sets of gasoline nozzle assemblies 4. The two fuels are supplied through independent channels to avoid mixing and interference from the source. The natural gas common rail 1 and the gasoline common rail 3 are arranged parallel to each other on the upper and lower sides of the engine intake manifold 5. The number of natural gas nozzle assemblies 2 and gasoline nozzle assemblies 4 is the same and is consistent with the number of cylinders in the engine. For example, a six-cylinder engine corresponds to six sets of natural gas nozzle assemblies 2 and six sets of gasoline nozzle assemblies 4. The natural gas nozzle assemblies 2 are located above the intake manifold 5, and the gasoline nozzle assemblies 4 are located below the intake manifold 5. Both are connected to the intake manifold 5 to achieve an independent supply mode of "one cylinder, two nozzles". This structure requires no modification to the engine block; dual-fuel upgrades can be achieved simply by adding external components. The upper and lower sides of the intake manifold 5 have pre-drilled mounting holes adapted to the nozzle assembly, with the hole diameter and nozzle interface tolerance controlled within ±0.05mm to ensure a tight seal. This structure solves the problems of "poor component compatibility and difficult installation" in existing modification schemes, possessing strong versatility. Furthermore, the "upper and lower separated" physical isolation layout overcomes the shortcomings of existing technologies, such as intersecting pipelines and low space utilization, providing hardware support for independent dual-fuel control.

[0040] Specifically, the natural gas common rail 1 is located above the intake manifold 5, and the gasoline common rail 3 is located below the intake manifold 5. Both extend along the direction of the engine cylinder arrangement. The common rail body is made of 304 stainless steel with a wall thickness of 3mm, capable of withstanding pressures above 20MPa to avoid the risk of fuel leakage. One end of the common rail is sealed, and the other end is connected to the fuel supply system via a flexible hose. The connection between the flexible hose and the common rail uses a double-sealing structure with double ferrules and O-rings. The O-rings are made of oil-resistant and aging-resistant nitrile rubber, and the ferrules are made of copper. They are fixed by crimping with a special tool, and the sealing performance has been tested for 1000 hours without leakage. The design of the common rail extending along the cylinder arrangement direction ensures that the connection distance error between each set of nozzle assemblies and the common rail is ≤5cm, ensuring that the fuel supply pressure difference between each cylinder is controlled within 0.1MPa, guaranteeing combustion uniformity. This layout and adaptation design to the supply system further improves the operational stability of the dual-fuel system.

[0041] Specifically, the natural gas nozzle assembly 2 injects natural gas into the inner wall of the intake manifold 5. The high-speed jet of natural gas impacts the inner wall of the manifold and instantly disperses, forming a fan-shaped film that adheres evenly to the wall surface. Subsequently, driven by the airflow within the intake manifold 5, it gradually peels off and diffuses, forming a dynamic mixture with the flowing air. By precisely controlling the injection amount of natural gas, the air-fuel ratio of the mixture can be stably maintained at 14.7:1 (this ratio is the theoretical optimal value for the complete combustion of natural gas), and finally enters the combustion chamber through the intake passage. The gasoline nozzle assembly 4 injects a jet of fuel into the combustion chamber through the intake passage. The gasoline nozzle has a multi-hole direct injection structure, and the convergence point of the fuel jet is precisely pointed to the central area of ​​the combustion chamber, ensuring that gasoline and air quickly form a locally combustible mixture. This structure employs a differentiated design of "natural gas impact diffusion along the wall + gasoline direct injection at the center." The increased contact area between the natural gas and air after impact diffusion solves the problem of "locally excessively high or low concentrations" in traditional premixing modes, resulting in improved combustion efficiency compared to existing dual-fuel systems and a corresponding increase in engine thermal efficiency. The gasoline direct injection structure requires only 70% of the ignition energy of natural gas, achieving a 98% cold start success rate at -20℃, far exceeding the 65% success rate of existing systems relying on natural gas for starting, thus addressing the industry pain point of "difficult cold starts" in dual-fuel engines. The injection paths of the two fuels are completely isolated in physical space. Natural gas is premixed on the upper side of the manifold, while gasoline is directly injected through the intake manifold on the lower side, preventing combustion disturbances caused by premixing of fuels from the source. Compared to existing structures with shared injection areas, NO x Emissions are reduced, including HC emissions. This design does not require modification of the engine intake manifold 5 itself; the upgrade can be completed simply by adding an external nozzle assembly, reducing modification costs by 40%. It is compatible with more than 80% of gasoline engine models on the market, solving the shortcomings of existing modification solutions such as "poor compatibility and complex installation," and has extremely strong promotional value.

[0042] Specifically, this structure includes a first mounting bracket 6 and a second mounting bracket 7, both made of 6061 aluminum alloy and anodized for rust prevention. The natural gas nozzle assembly 2 is fixed to the upper area outside the intake pipe 8 via the first mounting bracket 6, and the gasoline nozzle assembly 4 is fixed to the lower area outside the intake pipe 8 via the second mounting bracket 7. The inner side of the bracket has an arc-shaped groove that fits the outer wall of the intake pipe 8, and a 3mm thick silicone anti-slip pad is pasted inside the groove, enhancing stability and preventing vibration transmission caused by direct metal contact. The installation can be secured with bolts and anti-loosening nuts to ensure the accuracy of the nozzle assembly's installation position. This installation structure requires no welding; fixation is achieved solely through mechanical connections, reducing modification costs by 40%. It is also easy to disassemble and maintain, meeting the needs of modular modification.

[0043] Specifically, both the natural gas common rail 1 and the gasoline common rail 3 are connected to the fuel supply system via flexible hoses. These flexible hoses are fluororubber-reinforced composite tubes, with an inner layer of fluororubber (oil and solvent resistant) and an outer layer of polyester fiber braided layer (enhancing compressive strength). They operate at pressures ranging from 0-25 MPa and are suitable for temperatures from -40℃ to 130℃, adapting to the complex environment of the engine compartment. The connection between the flexible hose and the common rail is equipped with a sealing structure, which can be a stepped O-ring plus clamp structure. The O-rings are made of hydrogenated nitrile rubber, adapted to the inner wall of the hose and the stepped surface of the common rail interface. The clamps are stainless steel hose clamps, tightened with a torque wrench. Furthermore, the routing of the fuel supply system hoses has been optimized, fixed to the engine compartment longitudinal beams with hose clamps to avoid contact with high-temperature components (such as the exhaust pipe), maintaining a distance of ≥50mm, further improving operational safety.

[0044] Example 2:

[0045] The control method in this embodiment is based on the layout structure of Embodiment 1, and specifically includes the following steps:

[0046] S01. Signal Acquisition

[0047] The engine controller (ECU) acquires natural gas pressure signals through a pre-set pressure sensor installed between the high-pressure regulator inlet of the CNG transmission system and the CNG cylinder. The sensor has a measurement range of 0-20 MPa, an accuracy of ±0.05 bar, and outputs a 4-20 mA analog signal, which is converted to a digital signal by the ECU's internal AD converter with a 12-bit conversion accuracy. Simultaneously, the ECU acquires gasoline level signals through a pre-set level sensor installed on a float inside the gasoline tank. This sensor has a measurement range of 0-100% level, a resolution of 0.1%, and transmits the signal to the ECU via a CAN bus at a transmission rate of 500 kbps with a delay of ≤5 ms. This embodiment requires the selection of sensors with vibration and interference resistance, capable of stable operation under conditions of engine idling vibration and complex electromagnetic environments, ensuring accurate signal acquisition and providing reliable data support for subsequent remaining fuel level calculations and switching control.

[0048] S02. Calculation of Remaining Amount

[0049] Based on the natural gas pressure signal collected by S01, the ECU calculates the remaining natural gas supply available through the common rail system using a built-in algorithm. The algorithm formula is: Remaining natural gas (L) = (Current pressure P - Atmospheric pressure P0) × Cylinder volume V × Temperature correction coefficient K / Standard atmospheric pressure Pstandard. The temperature correction coefficient K is collected in real-time by a temperature sensor installed on the common rail system (range -40℃ to 120℃), with a corresponding K value of 0.92-1.08, used to compensate for the influence of temperature on natural gas pressure. The calculation algorithm based on the gasoline level signal is: Remaining gasoline (L) = Level height H × Tank cross-sectional area S × Gasoline density ρ. The gasoline density ρ is set to 0.75 kg / L by default and can be automatically corrected according to the fuel grade (e.g., 0.737 kg / L for 95 octane gasoline). After calculation, the ECU converts the remaining data into "driving range" (calculated in conjunction with current fuel consumption) and displays it in real-time on the instrument cluster. This function fully addresses the inventor's requirement for "users to monitor fuel status in real time," improving ease of use.

[0050] S03. Parameter Configuration and Switching Control

[0051] The ECU acquires and stores the preferred fuel type and fuel switching threshold. Parameter acquisition methods include two types: one is factory pre-configuration, with natural gas as the default preferred fuel and a switching threshold of 8 barG; the other is external input, where operators manually adjust the threshold via the "Fuel Settings" interface on the vehicle's central control screen (natural gas threshold can be set from 5-15 barG, and gasoline threshold from 10%-30% of the fuel level). The switching threshold setting is closely matched to the injection requirements of the nozzle assembly. The 8 barG natural gas threshold is the normal operating lower limit of the high-pressure regulator; below this value, the natural gas nozzle injection pressure will be insufficient, resulting in poor premixing. The 10% gasoline threshold corresponds to the safe fuel level at the bottom of the fuel tank, preventing the fuel pump from burning dry and being damaged. When the remaining amount of preferred fuel is below the switching threshold, the ECU executes a "cut-off-activation" timing control: first, a power-off command is sent to the common rail solenoid valve of the current fuel to cut off the supply path, and a shutdown signal is sent to the nozzle assembly; after a 100ms delay (ensuring residual pressure in the nozzle is released), a power-on command is sent to the common rail solenoid valve of the other fuel to activate the supply path and simultaneously activate the nozzle assembly for injection. This process utilizes the structural advantage of "dual nozzles positioned vertically" and combines it with the precise control of the ECU to achieve fuel-free switching, ensuring safe fuel supply and improving fuel economy.

[0052] The "cut-off-activation" control timing in S03 has been calibrated through bench testing: After the ECU stops the current fuel injector assembly from injecting, it activates the other fuel injector assembly after an interval of 50-100ms. The specific interval is dynamically adjusted according to the engine speed: 100ms at idle (800rpm) and 50ms at high speed (3000rpm), ensuring that residual fuel in the intake manifold completely enters the combustion chamber. To further ensure safety, the ECU monitors the feedback signals of the injector assembly (such as the solenoid valve operating current) in real time during the switching process. If an abnormality of "fuel supply after cut-off" occurs, the fuel pump relay is immediately de-energized to stop fuel supply, and a fault code is displayed on the instrument panel, ensuring safe fuel supply and avoiding safety risks caused by abnormal switching.

[0053] The control method also includes an optimized switching step for operating condition adaptation, triggered by the ECU based on engine operating conditions, specifically including:

[0054] (1) Cold start phase

[0055] During a cold start (coolant temperature < 50℃), the ECU prioritizes direct injection using the gasoline injector assembly. Gasoline is easier to ignite than natural gas, with a minimum ignition energy of 0.24mJ, significantly lower than natural gas's 0.35mJ. In low-temperature environments (-20℃), gasoline's ignition success rate reaches 98%, while natural gas's is only 65%. Once the engine coolant temperature reaches ≥ 70℃ or the engine speed stabilizes at 800-1000rpm, the ECU automatically switches to natural gas injection according to logic S03. During the switching process, engine speed fluctuations are ≤ 50rpm, and the driver experiences no noticeable jerking.

[0056] (2) Normal operation phase

[0057] The ECU executes steps S01-S03 cyclically every 100ms, updating fuel remaining data in real time. Under normal circumstances, natural gas is used preferentially to take full advantage of its economic advantage of being cheaper than gasoline. Based on the current gasoline price of 8 yuan / L and the gas price of 3 yuan / m³, the cost of using natural gas is reduced by 60% for the same driving range. When the natural gas pressure drops below 8 barG, it automatically switches to gasoline. The ECU will indicate the switch on the instrument panel and record the switch time and remaining amount for later reference.

[0058] (3) Endurance Guarantee Phase

[0059] When a certain fuel supply facility is scarce (such as when there is no gas station during a long journey), the operator can trigger the switch in three ways: ① touch buttons on the central control screen; ② shortcut keys on the steering wheel; ③ voice command ("Switch to gasoline"). After receiving the command, the ECU controls the switch according to the S03 timing sequence. After the switch is completed, the instrument panel displays the current fuel type and remaining range. Similar to the concept of range-extended electric vehicles, this solves the pain point of inconvenient single-fuel supply and expands the vehicle's applicability in various scenarios.

[0060] When the pressure or level sensor malfunctions (e.g., no signal, abnormal signal), the ECU immediately illuminates the instrument panel malfunction indicator light and automatically switches to the backup fuel system. It then controls the injectors in a "fixed injection pulse width" mode to ensure vehicle emergency driving, limiting the maximum speed to 80 km / h to prevent power loss. The ECU can identify the natural gas purity through injection feedback signals; if the purity is insufficient, it automatically increases the injection volume to compensate for power loss. During automatic engine start-stop, the ECU remembers the current fuel type and prioritizes using that fuel upon restarting, avoiding start-up delays caused by frequent switching and improving the user experience.

[0061] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0062] Although exemplary embodiments of the invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the invention without departing from the central concepts of the invention described herein. Therefore, the invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the invention.

Claims

1. A nozzle arrangement structure for a natural gas and gasoline dual-fuel engine, characterized in that, include: The system includes a natural gas common rail, several sets of natural gas nozzle assemblies, a gasoline common rail, and several sets of gasoline nozzle assemblies. The natural gas common rail is connected to several sets of natural gas nozzle assemblies, and the gasoline common rail is connected to several sets of gasoline nozzle assemblies. The natural gas common rail and the gasoline common rail are arranged parallel to each other on the upper and lower sides of the engine intake manifold. The number of natural gas nozzle assemblies and gasoline nozzle assemblies is the same and corresponds to the number of cylinders in the engine. The natural gas nozzle assemblies are located above the intake manifold, and the gasoline nozzle assemblies are located below the intake manifold. Both the natural gas nozzle assemblies and the gasoline nozzle assemblies are connected to the intake manifold.

2. The nozzle arrangement structure for a natural gas and gasoline dual-fuel engine according to claim 1, characterized in that, The natural gas common rail is located above the intake manifold, and the gasoline common rail is located below the intake manifold, both extending along the direction of the engine cylinder arrangement.

3. The nozzle arrangement structure for a natural gas and gasoline dual-fuel engine according to claim 1, characterized in that, The natural gas nozzle assembly injects natural gas into the inner wall of the intake manifold, while the gasoline nozzle assembly injects fuel jets into the combustion chamber through the intake passage.

4. The nozzle arrangement structure for a natural gas and gasoline dual-fuel engine according to claim 1, characterized in that, It also includes a first mounting bracket and a second mounting bracket; the natural gas nozzle assembly is fixed to the upper region outside the intake pipe via the first mounting bracket, and the gasoline nozzle assembly is fixed to the lower region outside the intake pipe via the second mounting bracket; both the first mounting bracket and the second mounting bracket are adapted to and connected to the outer wall of the intake pipe.

5. The nozzle arrangement structure for a natural gas and gasoline dual-fuel engine according to claim 4, characterized in that, The first mounting bracket and the second mounting bracket are fixedly connected to the outer wall of the air intake pipe by bolts or snap-fit ​​structures.

6. The nozzle arrangement structure for a natural gas and gasoline dual-fuel engine according to claim 1, characterized in that, Both the natural gas common rail and the gasoline common rail are connected to the fuel supply system via flexible hoses.

7. The nozzle arrangement structure for a natural gas and gasoline dual-fuel engine according to claim 6, characterized in that, The flexible hose is resistant to high pressure and oil / gas corrosion, and the connection between the flexible hose and the natural gas common rail or the gasoline common rail is equipped with a sealing structure.

8. A method for controlling the nozzle of a natural gas and gasoline dual-fuel engine, based on the nozzle arrangement structure of a natural gas and gasoline dual-fuel engine according to any one of claims 1 to 7, characterized in that, Includes the following steps: S01. Signal Acquisition: The ECU acquires the natural gas pressure signal through a preset pressure sensor, which is located between the inlet of the high-pressure regulator of the CNG transmission system and the CNG cylinder; at the same time, the ECU acquires the gasoline level signal through a preset liquid level sensor, which is located inside the gasoline tank. S02. Remaining Amount Calculation: Based on the natural gas pressure signal collected by S01, the ECU calculates the remaining amount of natural gas that can be supplied by the common rail; based on the gasoline level signal, it calculates the remaining amount of gasoline that can be supplied by the common rail. S03. Parameter Configuration and Switching Control: The ECU acquires and stores the preferred fuel type and fuel switching threshold, which is matched with the injection requirements of the corresponding fuel injector assembly. When the remaining amount of the preferred fuel is lower than the switching threshold, the ECU executes a "cut-off-activation" timing control: first, the common rail supply path of the preferred fuel and the injection control of the corresponding injector assembly are cut off, and then the common rail supply path of the other fuel and the injection control of the corresponding injector assembly are activated. The physical isolation structure of the two sets of injector assemblies placed on the upper and lower sides of the intake manifold avoids the mixing of the two fuels.

9. The method for controlling the nozzle of a natural gas and gasoline dual-fuel engine according to claim 8, characterized in that, The "cut-off-activate" control sequence in S03 is as follows: after the ECU controls the current fuel injector assembly to stop injection, it activates another fuel injector assembly after an interval of 50-100ms. Combined with the structure of natural gas injectors and gasoline injectors being placed on the upper and lower sides of the intake manifold, it completely avoids fuel mixing and interference in the intake manifold.

10. The method for controlling the nozzle of a natural gas and gasoline dual-fuel engine according to claim 8, characterized in that, It also includes optimized switching steps for operating condition adaptation, triggered by the ECU based on engine operating conditions, specifically including: (1) Cold start phase: The ECU prioritizes the gasoline injector assembly to perform direct injection. After the engine coolant temperature is ≥70℃ or the speed is stable at 800-1000rpm, it automatically switches to the natural gas injector assembly to perform premixed injection according to the logic of S03. (2) Normal operation phase: The ECU executes steps S01-S03 in a cycle and updates the remaining amount data in real time. When the remaining amount of priority fuel rises back to above the switching threshold, it can automatically switch back to priority fuel injection. (3) Endurance guarantee stage: When the ECU receives the manual switching command, it directly switches to another fuel injector assembly according to the timing control of S03 without adjusting the injector arrangement structure.

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