Dual fuel transient emission control method, apparatus, dual fuel injector, and engine

Abstract

This application provides a method, apparatus, dual-fuel injector, and engine for controlling transient emissions in a dual-fuel engine. The method is applied to a dual-fuel engine, which includes a dual-fuel injector with an internal cavity connection structure linking a diesel fuel line to an alternative fuel inlet. The method includes: acquiring transient operating parameters of the dual-fuel engine, including transient fuel quantity change rate and speed change rate; determining the level of the transient operating condition of the dual-fuel engine based on the values ​​of the transient operating parameters and a preset threshold; and adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition, so as to drive diesel fuel through the internal cavity connection structure into the alternative fuel inlet, where it is mixed with the alternative fuel and then enters the combustion chamber. This application solves the problem of emission degradation caused by unstable combustion in dual-fuel engines under transient operating conditions.

Description

Technical Field

[0001] This application relates to the field of engine control technology, and more specifically, to a dual-fuel transient emission control method, a dual-fuel injector, a dual-fuel engine, and a dual-fuel transient emission control device. Background Technology

[0002] Dual-fuel internal combustion engines (such as diesel-ignited methanol or natural gas) often experience problems such as unstable combustion and low heat release rate due to rapid fluctuations in speed and torque and changes in air-fuel ratio under transient operating conditions of the vehicle, leading to the deterioration of emission indicators such as nitrogen oxides and hydrocarbons.

[0003] In the existing technology, there is a lack of effective control methods for the transient process of dual-fuel systems, making it difficult to optimize the ignition effect in real time during dynamic changes, resulting in difficulties in transient emission control and the inability to reduce emissions. Summary of the Invention

[0004] The main objective of this application is to provide a dual-fuel transient emission control method, a dual-fuel injector, a dual-fuel engine, and a dual-fuel transient emission control device, so as to at least solve the problem of emission degradation caused by combustion instability in dual-fuel engines under transient operating conditions in the prior art.

[0005] To achieve the above objectives, according to one aspect of this application, a dual-fuel transient emission control method is provided. The method is applied to a dual-fuel engine, which includes a dual-fuel injector having an internal cavity communication structure connecting a diesel fuel line and an alternative fuel inlet. The method includes: acquiring transient operating condition parameters of the dual-fuel engine, the transient operating condition parameters including a transient fuel quantity change rate and a speed change rate; determining the level of the transient operating condition of the dual-fuel engine based on the values ​​of the transient operating condition parameters and a preset threshold, the transient operating condition levels including a first transient operating condition, a second transient operating condition, and a third transient operating condition with decreasing urgency; and adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition, so as to drive diesel fuel through the internal cavity communication structure into the alternative fuel inlet, and mix it with the alternative fuel before entering the combustion chamber.

[0006] Optionally, the level of the transient operating condition of the dual-fuel engine is determined based on the values ​​of the transient operating condition parameters and the magnitude of preset thresholds, including: determining that the dual-fuel engine is in the first transient operating condition when the transient fuel quantity change rate is greater than a first transient fuel quantity change threshold, or the speed change rate is greater than a first speed change threshold; determining that the dual-fuel engine is in the second transient operating condition when the transient fuel quantity change rate is greater than a second transient fuel quantity change threshold and less than the first transient fuel quantity change threshold, or the speed change rate is greater than a second speed change threshold and less than the first speed change threshold; and determining that the dual-fuel engine is in the third transient operating condition when the transient fuel quantity change rate is less than the second transient fuel quantity change threshold, or the speed change rate is less than the second speed change threshold.

[0007] Optionally, adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition includes: adjusting the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition, such that the diesel rail pressure is higher than the alternative fuel rail pressure.

[0008] Optionally, adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition includes: querying a preset rail pressure calibration mapping table according to the level of the transient operating condition to determine the target opening degree of the alternative fuel metering unit and the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure; determining the alternative fuel rail pressure under the current operating condition according to the target opening degree of the alternative fuel metering unit, and determining the target diesel rail pressure based on the alternative fuel rail pressure and the target pressure difference; querying the preset rail pressure calibration mapping table according to the target diesel rail pressure to determine the target opening degree of the diesel pressure control valve; and controlling the opening degree of the alternative fuel metering unit and the opening degree of the diesel pressure control valve to reach the corresponding target opening degrees.

[0009] Optionally, based on the level of the transient operating condition, a preset rail pressure calibration mapping table is consulted to determine the target opening degree of the alternative fuel metering unit, including: when the dual-fuel engine is in the first transient operating condition, determining the target opening degree of the alternative fuel metering unit as a first opening degree according to the preset rail pressure calibration mapping table; when the dual-fuel engine is in the second transient operating condition, determining the target opening degree of the alternative fuel metering unit as a second opening degree according to the preset rail pressure calibration mapping table; when the dual-fuel engine is in the third transient operating condition, determining the target opening degree of the alternative fuel metering unit as a third opening degree according to the preset rail pressure calibration mapping table; wherein, the first opening degree is less than the second opening degree, and the second opening degree is less than the third opening degree.

[0010] Optionally, based on the level of the transient operating condition, a preset rail pressure calibration mapping table is consulted to determine the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure, including: when the dual-fuel engine is in the first transient operating condition, determining the target pressure difference as a first target pressure difference; when the dual-fuel engine is in the second transient operating condition, determining the target pressure difference as a second target pressure difference; when the dual-fuel engine is in the third transient operating condition, determining the target pressure difference as a third target pressure difference; wherein, the first target pressure difference is greater than the second target pressure difference, and the second target pressure difference is greater than the third target pressure difference.

[0011] Optionally, determining the target diesel rail pressure based on the alternative fuel rail pressure and the target pressure difference includes: adding the alternative fuel rail pressure and the target pressure difference to obtain the target diesel rail pressure.

[0012] According to another aspect of this application, a dual-fuel injector is provided, comprising: an injector body having a diesel pressure chamber and an alternative fuel inlet; and an inner cavity communication structure formed in the injector body, connecting the diesel pressure chamber and the alternative fuel inlet, such that when the pressure in the diesel pressure chamber is higher than the pressure at the alternative fuel inlet, diesel fuel can enter the alternative fuel inlet through the inner cavity communication structure.

[0013] According to another aspect of this application, a dual-fuel engine is provided, comprising: the dual-fuel injector; and a controller connected to the dual-fuel injector, the controller being configured to perform any of the dual-fuel transient emission control methods to control the operation of the dual-fuel injector.

[0014] According to another aspect of this application, a dual-fuel transient emission control device is provided, comprising: an acquisition unit for acquiring transient operating condition parameters of a dual-fuel engine, the transient operating condition parameters including transient fuel quantity change rate and speed change rate; a determination unit for determining the level of transient operating condition of the dual-fuel engine based on the value of the transient operating condition parameters and the magnitude of a preset threshold, the level of transient operating condition including a first transient operating condition, a second transient operating condition, and a third transient operating condition with decreasing urgency; and an adjustment unit for adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition, so as to drive diesel fuel through an internal cavity connecting structure into the alternative fuel inlet, and mix it with the alternative fuel before entering the combustion chamber.

[0015] By applying the technical solution of this application, transient operating condition parameters of a dual-fuel engine are obtained, including transient fuel quantity change rate and speed change rate. Based on the values ​​of the transient operating condition parameters and the magnitude of a preset threshold, the level of the transient operating condition of the dual-fuel engine is determined. The levels of the transient operating condition include a first transient operating condition, a second transient operating condition, and a third transient operating condition, with the urgency decreasing sequentially. Based on the level of the transient operating condition, the pressure difference between the diesel rail pressure and the alternative fuel rail pressure is adjusted to drive diesel fuel through the internal cavity connecting structure into the alternative fuel inlet, where it is mixed with the alternative fuel and then enters the combustion chamber. In this scheme, the transient operating condition level is identified based on the transient fuel quantity change rate and speed change rate. The rail pressure difference between diesel and alternative fuel is dynamically adjusted accordingly. High-pressure diesel leaks through the internal cavity connecting structure to the alternative fuel inlet and mixes with the alternative fuel. The compression ignition characteristics of diesel ignite the alternative fuel, thereby improving the combustion stability of the dual-fuel engine under transient operating conditions, increasing the heat release rate, and ultimately reducing engine transient emissions. This solves the problem of emission degradation caused by unstable combustion in existing dual-fuel engines under transient operating conditions. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 A schematic flowchart of a dual-fuel transient emission control method according to an embodiment of this application is shown;

[0018] Figure 2 A schematic diagram of a dual-fuel injector according to an embodiment of this application is shown;

[0019] Figure 3 A partially enlarged schematic diagram of a dual-fuel injector provided according to an embodiment of this application is shown;

[0020] Figure 4 A flowchart of a specific dual-fuel transient emission control method according to an embodiment of this application is shown;

[0021] Figure 5 A structural block diagram of a dual-fuel transient emission control device according to an embodiment of this application is shown.

[0022] The above figures include the following reference numerals:

[0023] 1. Alternative fuel inlet; 2. First diesel pressure chamber; 3. Second diesel pressure chamber; 4. Balance valve; 5. Needle valve; 6. Needle valve body; 7. Injection orifice; 8. Washer; 9. Spring; 10. Diesel sealing oil passage; 11. Injector body; 12. Balance valve damping orifice. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] As described in the background section, the existing technology lacks effective control methods for the transient process of dual-fuel systems, making it difficult to optimize the ignition effect in real time during dynamic changes. This leads to difficulties in transient emission control and makes it impossible to reduce emissions. To solve the problem of emission degradation caused by unstable combustion in dual-fuel engines under transient operating conditions, the embodiments of this application provide a dual-fuel transient emission control method, a dual-fuel injector, a dual-fuel engine, and a dual-fuel transient emission control device.

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0029] Figure 1 This is a schematic flowchart of a dual-fuel transient emission control method according to an embodiment of this application. Figure 1 As shown, the method includes the following steps:

[0030] Step S101: Obtain the transient operating parameters of the dual-fuel engine, including the transient fuel quantity change rate and the speed change rate.

[0031] Specifically, real-time monitoring and collection of key dynamic data reflecting the current operating status of a dual-fuel engine (hereinafter referred to as the engine) requires obtaining two core parameters: the transient fuel quantity change rate, which is the rate of change in fuel injection quantity per unit time, used to characterize the intensity of engine load or acceleration demand; and the speed change rate, which is the rate of change in engine speed per unit time, used to characterize changes in engine inertial load or response speed. These two parameters together constitute the basic data for determining whether the engine is operating in a non-steady-state condition.

[0032] Step S102: Based on the values ​​of the transient operating condition parameters and the preset threshold, determine the level of the transient operating condition of the dual-fuel engine. The levels of the transient operating condition include a first transient operating condition, a second transient operating condition, and a third transient operating condition, which are successively reduced in urgency.

[0033] Specifically, step S102 compares the transient operating condition parameters obtained in step S101 with preset thresholds to classify the severity or urgency of the current transient operating condition. The transient operating condition levels include the first transient operating condition with the highest urgency (such as rapid acceleration), the second transient operating condition with moderate urgency (such as normal acceleration), and the third transient operating condition with the lowest urgency (such as slight load fluctuation). This process achieves quantitative classification of transient operating conditions, providing a basis for subsequent differentiated control.

[0034] Step S103: According to the level of the transient operating condition, adjust the pressure difference between the diesel rail pressure and the alternative fuel rail pressure to drive the diesel fuel through the internal cavity connection structure into the alternative fuel inlet, and mix it with the alternative fuel before entering the combustion chamber.

[0035] Specifically, step S103 involves dynamically adjusting the diesel rail pressure and the alternative fuel (such as methanol or natural gas) rail pressure based on the transient operating condition level determined in step S102, creating a pressure differential environment where the diesel rail pressure is higher than the alternative fuel rail pressure. Utilizing this pressure differential, high-pressure diesel fuel leaks or flows directly into the alternative fuel inlet through the injector's unique internal cavity connection structure (i.e., the physical channel connecting the diesel fuel line and the alternative fuel inlet). Ultimately, the diesel fuel and the alternative fuel are fully mixed at the inlet or in the combustion chamber, and the high-pressure ignition characteristics of the diesel fuel ignite the alternative fuel, thus completing the synergistic combustion process of the two fuels and suppressing emission deterioration under transient operating conditions.

[0036] This embodiment identifies the transient operating condition level based on the transient fuel quantity change rate and speed change rate, and dynamically adjusts the rail pressure difference between diesel and alternative fuel accordingly. High-pressure diesel leaks through the internal cavity connecting structure to the alternative fuel inlet and mixes with the alternative fuel. The compression ignition characteristics of diesel ignite the alternative fuel, thereby significantly improving the combustion stability of the dual-fuel engine under transient operating conditions, increasing the heat release rate, and ultimately reducing engine transient emissions. This solves the problem of emission degradation caused by unstable combustion in existing dual-fuel engines under transient operating conditions.

[0037] In the specific implementation process, the level of the transient operating condition of the dual-fuel engine is determined based on the values ​​of the aforementioned transient operating condition parameters and the magnitude of the preset threshold, including: determining that the dual-fuel engine is in the first transient operating condition when the transient fuel quantity change rate is greater than the first transient fuel quantity change threshold, or the speed change rate is greater than the first speed change threshold; determining that the dual-fuel engine is in the second transient operating condition when the transient fuel quantity change rate is greater than the second transient fuel quantity change threshold and less than the first transient fuel quantity change threshold, or the speed change rate is greater than the second speed change threshold and less than the first speed change threshold; and determining that the dual-fuel engine is in the third transient operating condition when the transient fuel quantity change rate is less than the second transient fuel quantity change threshold, or the speed change rate is less than the second speed change threshold.

[0038] Specifically, when the transient fuel quantity change rate is greater than the first transient fuel quantity change threshold, or the speed change rate is greater than the first speed change threshold, the engine is determined to be in the first transient operating condition, regardless of the other parameter. This usually corresponds to extreme transient scenarios such as rapid engine acceleration or a sudden increase in load.

[0039] When the transient fuel quantity change rate is between the second transient fuel quantity change threshold and the first transient fuel quantity change threshold, or when the engine speed change rate is between the second engine speed change threshold and the first engine speed change threshold, the engine is determined to be in a second transient operating condition, corresponding to a scenario of normal engine acceleration or moderate load variation. Specifically, the second transient fuel quantity change threshold is less than the first transient fuel quantity change threshold, and the second engine speed change threshold is less than the first engine speed change threshold.

[0040] When the transient oil quantity change rate is lower than the second transient oil quantity change threshold, or the speed change rate is lower than the second speed change threshold, the engine is determined to be in the third transient operating condition, which corresponds to a relatively stable transient scenario such as slight engine load fluctuation or slow acceleration.

[0041] The threshold values ​​for the first transient fuel quantity change, the second transient fuel quantity change, the first engine speed change, and the second engine speed change are primarily based on engine bench calibration tests. Determined through extensive transient operating condition test data, these threshold values ​​aim to balance emission suppression and fuel economy. The first transient fuel quantity change and the first engine speed change thresholds correspond to the critical points of most severe emission degradation, while the second transient fuel quantity change and second engine speed change thresholds serve as the defining criteria for moderate transients, distinguishing between mild and moderate transients. These threshold values ​​ensure precise matching of the appropriate diesel ignition ratio during transients of varying severity, avoiding excessive intervention that could lead to reduced fuel economy in mild transients while fully guaranteeing emission compliance in severe transients. Since different engines use different fuels, have different power outputs, different air-fuel ratios, and different injector flow rates, the above threshold values ​​for each engine must be recalibrated based on these variables through bench tests.

[0042] By setting two threshold ranges, transient operating conditions are finely divided into three levels: the first transient operating condition, the second transient operating condition, and the third transient operating condition, with decreasing urgency. This enables precise classification and identification of the severity of engine transient operation. This classification mechanism allows the control strategy to respond differently according to the specific characteristics of different operating condition levels (such as rapid acceleration, normal acceleration, or slight fluctuations), avoiding a one-size-fits-all approach. It ensures that sufficient ignition diesel fuel can be quickly provided to suppress emissions under severe transient operating conditions, while optimizing fuel economy under mild transient operating conditions.

[0043] To ensure that the diesel rail pressure is always higher than the alternative fuel rail pressure under any level of transient operating condition, in some embodiments of this application, the pressure difference between the diesel rail pressure and the alternative fuel rail pressure is adjusted according to the level of the transient operating condition, including: adjusting the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition, such that the diesel rail pressure is higher than the alternative fuel rail pressure.

[0044] Specifically, based on the currently determined transient operating condition level, the diesel rail pressure and the alternative fuel rail pressure are adjusted respectively. The core purpose is to establish and maintain a positive pressure differential environment between the two. This positive pressure differential is the power source that drives diesel fuel to flow through the unique internal cavity connection structure of the injector to the alternative fuel inlet, thereby ensuring that diesel fuel can leak smoothly and mix with the alternative fuel, creating conditions for subsequent ignition of the alternative fuel using the compression ignition characteristics of diesel fuel.

[0045] By ensuring that the diesel rail pressure is always higher than the alternative fuel rail pressure, a necessary positive pressure gradient is established, thus providing the driving force for the active flow of diesel fuel through the injector cavity connection structure to the alternative fuel inlet. This ensures that, under transient operating conditions, diesel fuel can reliably leak and fully mix with the alternative fuel, thereby effectively igniting the alternative fuel using the high-pressure ignition characteristics of diesel fuel. This solves the problem of uneven mixing or ignition failure of dual fuels under dynamic operating conditions, ensuring combustion stability and effectively suppressing transient emissions.

[0046] Further, adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition includes: querying a preset rail pressure calibration mapping table to determine the target opening degree of the alternative fuel metering unit and the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition; determining the alternative fuel rail pressure under the current operating condition according to the target opening degree of the alternative fuel metering unit, and determining the target diesel rail pressure based on the alternative fuel rail pressure and the target pressure difference; querying the preset rail pressure calibration mapping table to determine the target opening degree of the diesel pressure control valve according to the target diesel rail pressure; and controlling the opening degree of the alternative fuel metering unit and the opening degree of the diesel pressure control valve to reach the corresponding target opening degrees.

[0047] Specifically, firstly, based on the determined transient operating condition level, a preset rail pressure calibration mapping table is consulted to obtain two key control targets: the target opening degree of the alternative fuel metering unit and the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure. Secondly, using the obtained target opening degree of the alternative fuel metering unit and the current engine operating status, the actual alternative fuel rail pressure value is calculated. Subsequently, this calculated alternative fuel rail pressure is compared with the target pressure difference obtained from the table to determine the required target diesel rail pressure. This ensures that the diesel rail pressure is always higher than the alternative fuel rail pressure by the specified target value. Next, the preset rail pressure calibration mapping table is consulted again, and the target opening degree of the corresponding diesel pressure control valve is found based on the determined target diesel rail pressure. This step establishes the correspondence between the diesel rail pressure and the actuator (diesel pressure control valve) action. Finally, commands are sent to the hardware to adjust the alternative fuel metering unit and the diesel pressure control valve respectively, so that their actual opening degrees reach the aforementioned determined target opening degrees. Through this closed-loop lookup and adjustment process, precise and rapid control of the rail pressure and differential pressure of diesel and alternative fuels is achieved, thereby meeting the requirements for dual-fuel blending and ignition under transient operating conditions.

[0048] The preset rail pressure calibration mapping table is a control database pre-calibrated based on engine bench test data. It is indexed by the level of transient operating conditions and stores the target opening degree of the alternative fuel metering unit and the target pressure difference between diesel and alternative fuel required for different levels of operating severity. This mapping table simplifies the complex transient control strategy into a lookup operation, enabling the optimal alternative fuel supply and pressure difference setpoint to be quickly determined based on the identified transient operating condition level. Then, combined with the real-time calculated alternative fuel rail pressure, the target diesel rail pressure and the target opening degree of the diesel pressure control valve are derived, thereby achieving precise and real-time dynamic adjustment of the dual-fuel rail pressure and pressure difference. This ensures the optimal blending ratio of diesel and alternative fuel under transient operating conditions to optimize combustion and reduce emissions.

[0049] By introducing a pre-defined rail pressure calibration mapping table, the complex transient control logic is transformed into an efficient lookup and calculation process, enabling rapid response and precise execution of the control strategy. This mapping table directly obtains the target opening and target pressure difference of the alternative fuel metering unit under different transient operating conditions. Combined with real-time alternative fuel rail pressure, the target diesel rail pressure is dynamically calculated, and the target opening of the diesel pressure control valve is further determined. This ensures that the optimal pressure difference between diesel and alternative fuel can be quickly and accurately established and maintained under transient conditions, guaranteeing the stability and effectiveness of dual-fuel blending ignition, and ultimately achieving real-time optimized control of transient emissions.

[0050] Furthermore, based on the aforementioned transient operating condition level, a preset rail pressure calibration mapping table is consulted to determine the target opening degree of the alternative fuel metering unit, including: when the dual-fuel engine is in the aforementioned first transient operating condition, the target opening degree of the alternative fuel metering unit is determined to be a first opening degree according to the aforementioned preset rail pressure calibration mapping table; when the dual-fuel engine is in the aforementioned second transient operating condition, the target opening degree of the alternative fuel metering unit is determined to be a second opening degree according to the aforementioned preset rail pressure calibration mapping table; when the dual-fuel engine is in the aforementioned third transient operating condition, the target opening degree of the alternative fuel metering unit is determined to be a third opening degree according to the aforementioned preset rail pressure calibration mapping table; wherein, the first opening degree is less than the second opening degree, and the second opening degree is less than the third opening degree.

[0051] Specifically, this embodiment defines the correspondence and order of magnitude between different transient operating condition levels and the target opening degree of the alternative fuel metering unit. When the dual-fuel engine is in the first transient operating condition (i.e., the most urgent and drastically changing condition), the target opening degree of the alternative fuel metering unit is determined by referring to a table as the first opening degree; when the engine is in the second transient operating condition (i.e., a moderately urgent condition), the target opening degree of the alternative fuel metering unit is determined by referring to a table as the second opening degree; when the engine is in the third transient operating condition (i.e., the least urgent and relatively stable condition), the target opening degree of the alternative fuel metering unit is determined by referring to a table as the third opening degree. The first opening degree is smaller than the second opening degree, and the second opening degree is smaller than the third opening degree. This indicates that as the intensity of the transient operating condition decreases (from the first level to the third level), the target opening degree of the alternative fuel metering unit gradually increases. The main rationale is as follows: Under severe transient conditions (first transient condition), the supply of alternative fuels needs to be reduced to allow diesel fuel to leak through the pressure differential and ignite, thereby suppressing emissions; while under mild transient conditions (third transient condition), more alternative fuels can be allowed to enter in order to optimize economy. Therefore, by limiting the decreasing relationship of the opening degree, a differentiated control strategy for the flow of alternative fuels under different transient severity levels is clarified.

[0052] By defining a hierarchical relationship where the first opening degree is less than the second opening degree and the second opening degree is less than the third opening degree, an inverse control logic is established between the severity of transient conditions and the supply of alternative fuels. That is, the supply of alternative fuels is minimized under the first transient condition with the highest urgency and emission risk, while the supply of alternative fuels is gradually increased under normal conditions. This hierarchical control strategy not only ensures that the ignition ratio of diesel is prioritized to effectively suppress emission degradation during severe transients, but also appropriately increases the proportion of alternative fuels used to optimize fuel economy during non-severe transients, thereby achieving a dynamic balance and precise coordination between transient emission control and fuel economy.

[0053] In some embodiments of this application, based on the level of the aforementioned transient operating condition, a preset rail pressure calibration mapping table is consulted to determine the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure. This includes: determining the target pressure difference as a first target pressure difference when the dual-fuel engine is in the aforementioned first transient operating condition; determining the target pressure difference as a second target pressure difference when the dual-fuel engine is in the aforementioned second transient operating condition; and determining the target pressure difference as a third target pressure difference when the dual-fuel engine is in the aforementioned third transient operating condition; wherein the first target pressure difference is greater than the second target pressure difference, and the second target pressure difference is greater than the third target pressure difference.

[0054] Specifically, when the dual-fuel engine is in the first transient operating condition (i.e., the condition with the most drastic changes and the highest emission risk), the target pressure difference is determined by referring to a table as the first target pressure difference; when the dual-fuel engine is in the second transient operating condition (i.e., the condition with moderate severity), the target pressure difference is determined by referring to a table as the second target pressure difference; and when the dual-fuel engine is in the third transient operating condition (i.e., the condition with relatively gentle changes), the target pressure difference is determined by referring to a table as the third target pressure difference. The first target pressure difference is greater than the second target pressure difference, and the second target pressure difference is greater than the third target pressure difference. This indicates that as the severity of the transient operating condition decreases, the required pressure difference between diesel and the alternative fuel gradually decreases. The main reason is that under severe transient conditions, a larger pressure difference is needed to drive more diesel to leak through the injector's internal gaps to the alternative fuel side, thereby enhancing the ignition effect and suppressing emissions; while under gentle transient conditions, a smaller pressure difference is sufficient to meet the ignition requirements, while also helping to reduce unnecessary diesel consumption.

[0055] By defining a hierarchical relationship where the first target pressure differential is greater than the second target pressure differential, and the second target pressure differential is greater than the third target pressure differential, a proportional control logic between the severity of transient conditions and the pressure differential between diesel and alternative fuels is established. Specifically, the maximum pressure differential is provided under the first transient condition, which is the most urgent and requires the strongest ignition effect, to drive more diesel to leak to the alternative fuel side, thereby effectively suppressing emissions. Under milder conditions, a smaller pressure differential is provided to balance fuel economy. This tiered pressure differential control strategy ensures precise matching of diesel ignition quantity under different transient severity levels. It guarantees combustion stability and low emission performance under severe transients, while avoiding excessive fuel injection under mild transients, thus ensuring simultaneous optimization of transient emissions and fuel economy across the entire operating range.

[0056] In some embodiments of this application, determining the target diesel rail pressure based on the alternative fuel rail pressure and the target pressure difference includes: adding the alternative fuel rail pressure and the target pressure difference to obtain the target diesel rail pressure.

[0057] Specifically, the target diesel rail pressure is obtained by adding the alternative fuel rail pressure under the current operating conditions to the target pressure difference obtained from a table. This embodiment establishes a baseline relationship between the diesel rail pressure and the alternative fuel rail pressure, meaning that the diesel rail pressure is always controlled to be higher than the alternative fuel rail pressure, and the excess value is consistent with the target pressure difference. Through this embodiment, the diesel rail pressure can be adjusted in real time and dynamically according to changes in the alternative fuel rail pressure, ensuring that the required pressure difference is always maintained between the two, thereby controlling the flow of diesel fuel leaking to the alternative fuel side through the internal gap of the injector, and achieving effective blending and ignition of the two fuels.

[0058] This control strategy based on differential pressure superposition ensures that the diesel rail pressure is always precisely higher than the alternative fuel rail pressure by a specific difference, thereby stably controlling the flow of diesel leaking to the alternative fuel side through the internal gap of the injector. This not only ensures that the optimal ignition-blending ratio can be maintained to suppress emissions under different alternative fuel rail pressure fluctuations, but also improves the response speed and execution accuracy of transient control.

[0059] This application also provides a dual-fuel injector, such as... Figure 2 As shown, the dual-fuel injector includes an injector body with a substitute fuel inlet 1 and a diesel pressure chamber, the diesel pressure chamber comprising a first diesel pressure chamber 2 and a second diesel pressure chamber 3. The dual-fuel injector also includes a balance valve 4, a needle valve 5, a needle valve body 6, a nozzle 7, a gasket 8, a spring 9, a diesel sealing oil passage 10, an injector body 11, and an internal cavity communication structure formed within the injector body, connecting the diesel pressure chamber and the substitute fuel inlet. This allows diesel fuel to enter the substitute fuel inlet through the internal cavity communication structure when the pressure in the diesel pressure chamber is higher than the pressure at the substitute fuel inlet. The balance valve is balanced at a certain position by the downward pressure of the control oil, the upward movement of the spring, and the upward movement of substitute fuels such as methanol. The needle valve is a movable pair, its lower end engaging with a sealing valve seat to form a seal. When the control requires opening, the needle valve moves upward, disengaging from the sealing valve seat, and the injector begins injection.

[0060] Figure 3 This is a partially enlarged view of the dual-fuel injector, which also includes a balance valve damping orifice 12. The function of this balance valve damping orifice is to generate a hydraulic damping effect on the movement of the balance valve, thereby slowing down the rapid displacement of the balance valve caused by drastic fluctuations in rail pressure under transient operating conditions, preventing the balance valve from oscillating at high frequencies or getting stuck, and ensuring that the balance valve can be smoothly and accurately maintained in a balanced position determined by the diesel pressure, the alternative fuel pressure, and the spring force. This, in turn, ensures the stability and controllability of the diesel leakage flow to the alternative fuel side through the nozzle gap.

[0061] The structure of a dual-fuel injector (fuel nozzle) includes, but is not limited to, the above. Figure 2 The structure and principle are defined by diesel fuel leaking to the alternative fuel side through the internal gap of the dual-fuel injector. Rail pressure adjustment includes, but is not limited to, the metering unit and the pressure regulating valve. The injector leakage rate can be calibrated and corrected based on factory test data: leakage rate, gap value, etc.

[0062] This application also provides a dual-fuel engine, including: the dual-fuel injector described above; and a controller connected to the dual-fuel injector, wherein the controller is configured to execute any of the dual-fuel transient emission control methods described above to control the operation of the dual-fuel injector.

[0063] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the dual-fuel transient emission control method of this application will be described in detail below with reference to specific embodiments.

[0064] This embodiment relates to a specific dual-fuel transient emission control method, such as... Figure 4 As shown, the process includes the following:

[0065] After the engine starts, the dual-fuel supply system activates and queries the rail pressure calibration MAP (a preset rail pressure calibration mapping table). If the condition is met that "the transient fuel quantity change rate is greater than the first transient fuel quantity change threshold, or the speed change rate is greater than the first speed change threshold," then the target opening degree of the alternative fuel metering unit is determined to be the first opening degree (based on the preset rail pressure calibration mapping table correction). If the condition is not met that "the transient fuel quantity change rate is greater than the first transient fuel quantity change threshold, or the speed change rate is greater than the first speed change threshold," then it is determined whether the condition is met that "the transient fuel quantity change rate is greater than the second transient fuel quantity change threshold and less than the first transient fuel quantity change threshold, or the speed change rate is greater than the second speed change threshold." If the following conditions are met: "the instantaneous fuel quantity change rate is greater than the second instantaneous fuel quantity change threshold and less than the first instantaneous fuel quantity change threshold, or the speed change rate is greater than the second speed change threshold and less than the first speed change threshold," then it is determined whether the following conditions are met: "the instantaneous fuel quantity change rate is less than the second instantaneous fuel quantity change threshold, or the speed change rate is less than the second speed change threshold." If so, then the target opening of the alternative fuel metering unit is determined to be the third opening (based on the preset rail pressure calibration mapping table). After determining the target opening of the alternative fuel metering unit, the opening of the diesel pressure control valve still queries the preset rail pressure calibration mapping table, maintaining the rail pressure difference between the alternative fuel (methanol, natural gas, hydrogen, ammonia, etc.) and diesel as the target difference value based on the operating conditions.

[0066] When the diesel rail pressure is higher than the alternative fuel rail pressure, diesel fuel in the dual-fuel injector enters the alternative fuel inlet through the gap between the balance valve and the needle valve body. After being blended, the two fuels enter the combustion chamber simultaneously, where the diesel fuel is ignited by compression ignition, improving combustion, increasing the heat release rate, and reducing emissions.

[0067] For example, if the transient fuel quantity change rate is greater than 50mg, or the speed change rate is greater than 300 rpm, the transient change is drastic, requiring a larger pressure difference (e.g., 50 bar) to inject more diesel fuel to suppress emissions.

[0068] This application also provides a dual-fuel transient emission control device. It should be noted that the dual-fuel transient emission control device of this application can be used to execute the dual-fuel transient emission control method provided in this application. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0069] The following describes the dual-fuel transient emission control device provided in the embodiments of this application.

[0070] Figure 5 This is a structural block diagram of a dual-fuel transient emission control device according to an embodiment of this application. Figure 5 As shown, the device includes an acquisition unit 51, a determination unit 52, and an adjustment unit 53. The acquisition unit is used to acquire transient operating parameters of the dual-fuel engine, including transient fuel quantity change rate and speed change rate. The determination unit is used to determine the level of transient operating condition of the dual-fuel engine based on the values ​​of the transient operating parameters and the magnitude of a preset threshold. The levels of transient operating conditions include a first transient operating condition, a second transient operating condition, and a third transient operating condition, with decreasing urgency. The adjustment unit is used to adjust the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition, so as to drive diesel fuel through the internal cavity connecting structure into the alternative fuel inlet, and mix it with the alternative fuel before entering the combustion chamber.

[0071] This embodiment identifies the transient operating condition level based on the transient fuel quantity change rate and speed change rate, and dynamically adjusts the rail pressure difference between diesel and alternative fuel accordingly. High-pressure diesel leaks through the internal cavity connecting structure to the alternative fuel inlet and mixes with the alternative fuel. The compression ignition characteristics of diesel ignite the alternative fuel, thereby significantly improving the combustion stability of the dual-fuel engine under transient operating conditions, increasing the heat release rate, and ultimately reducing engine transient emissions. This solves the problem of emission degradation caused by unstable combustion in existing dual-fuel engines under transient operating conditions.

[0072] In specific implementation, the aforementioned determining unit includes a first determining module, a second determining module, and a third determining module. The first determining module is used to determine that the dual-fuel engine is in the first transient operating condition when the transient fuel quantity change rate is greater than a first transient fuel quantity change threshold, or the speed change rate is greater than a first speed change threshold. The second determining module is used to determine that the dual-fuel engine is in the second transient operating condition when the transient fuel quantity change rate is greater than a second transient fuel quantity change threshold and less than the first transient fuel quantity change threshold, or the speed change rate is greater than a second speed change threshold and less than the first speed change threshold. The third determining module is used to determine that the dual-fuel engine is in the third transient operating condition when the transient fuel quantity change rate is less than the second transient fuel quantity change threshold, or the speed change rate is less than the second speed change threshold.

[0073] By setting two threshold ranges, transient operating conditions are finely divided into three levels: the first transient operating condition, the second transient operating condition, and the third transient operating condition, with decreasing urgency. This enables precise classification and identification of the severity of engine transient operation. This classification mechanism allows the control strategy to respond differently according to the specific characteristics of different operating condition levels (such as rapid acceleration, normal acceleration, or slight fluctuations), avoiding a one-size-fits-all approach. It ensures that sufficient ignition diesel fuel can be quickly provided to suppress emissions under severe transient operating conditions, while optimizing fuel economy under mild transient operating conditions.

[0074] To ensure that the diesel rail pressure is always higher than the alternative fuel rail pressure under any level identified as a transient condition, in some embodiments of this application, the adjustment unit includes an adjustment module for adjusting the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient condition, such that the diesel rail pressure is higher than the alternative fuel rail pressure.

[0075] By ensuring that the diesel rail pressure is always higher than the alternative fuel rail pressure, a necessary positive pressure gradient is established, thus providing the driving force for the active flow of diesel fuel through the injector cavity connection structure to the alternative fuel inlet. This ensures that, under transient operating conditions, diesel fuel can reliably leak and fully mix with the alternative fuel, thereby effectively igniting the alternative fuel using the high-pressure ignition characteristics of diesel fuel. This solves the problem of uneven mixing or ignition failure of dual fuels under dynamic operating conditions, ensuring combustion stability and effectively suppressing transient emissions.

[0076] Furthermore, the aforementioned adjustment module includes a first determining submodule, a second determining submodule, a third determining submodule, and a control submodule. The first determining submodule is used to query a preset rail pressure calibration mapping table based on the level of the transient operating condition to determine the target opening degree of the alternative fuel metering unit and the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure. The second determining submodule is used to determine the alternative fuel rail pressure under the current operating condition based on the target opening degree of the alternative fuel metering unit, and to determine the target diesel rail pressure based on the alternative fuel rail pressure and the target pressure difference. The third determining submodule is used to query the preset rail pressure calibration mapping table based on the target diesel rail pressure to determine the target opening degree of the diesel pressure control valve. The control submodule is used to control the opening degree of the alternative fuel metering unit and the opening degree of the diesel pressure control valve to reach their respective target opening degrees.

[0077] By introducing a pre-defined rail pressure calibration mapping table, the complex transient control logic is transformed into an efficient lookup and calculation process, enabling rapid response and precise execution of the control strategy. This mapping table directly obtains the target opening and target pressure difference of the alternative fuel metering unit under different transient operating conditions. Combined with real-time alternative fuel rail pressure, the target diesel rail pressure is dynamically calculated, and the target opening of the diesel pressure control valve is further determined. This ensures that the optimal pressure difference between diesel and alternative fuel can be quickly and accurately established and maintained under transient conditions, guaranteeing the stability and effectiveness of dual-fuel blending ignition, and ultimately achieving real-time optimized control of transient emissions.

[0078] Furthermore, the first determining submodule is used to determine the target opening degree of the alternative fuel metering unit as a first opening degree according to the preset rail pressure calibration mapping table when the dual-fuel engine is in the first transient operating condition; when the dual-fuel engine is in the second transient operating condition, it determines the target opening degree of the alternative fuel metering unit as a second opening degree according to the preset rail pressure calibration mapping table; and when the dual-fuel engine is in the third transient operating condition, it determines the target opening degree of the alternative fuel metering unit as a third opening degree according to the preset rail pressure calibration mapping table; wherein the first opening degree is smaller than the second opening degree, and the second opening degree is smaller than the third opening degree.

[0079] By defining a hierarchical relationship where the first opening degree is less than the second opening degree and the second opening degree is less than the third opening degree, an inverse control logic is established between the severity of transient conditions and the supply of alternative fuels. That is, the supply of alternative fuels is minimized under the first transient condition with the highest urgency and emission risk, while the supply of alternative fuels is gradually increased under normal conditions. This hierarchical control strategy not only ensures that the ignition ratio of diesel is prioritized to effectively suppress emission degradation during severe transients, but also appropriately increases the proportion of alternative fuels used to optimize fuel economy during non-severe transients, thereby achieving a dynamic balance and precise coordination between transient emission control and fuel economy.

[0080] In some embodiments of this application, the first determining submodule is used to determine the target pressure difference as a first target pressure difference when the dual-fuel engine is in the first transient operating condition; to determine the target pressure difference as a second target pressure difference when the dual-fuel engine is in the second transient operating condition; and to determine the target pressure difference as a third target pressure difference when the dual-fuel engine is in the third transient operating condition; wherein the first target pressure difference is greater than the second target pressure difference, and the second target pressure difference is greater than the third target pressure difference.

[0081] By defining a hierarchical relationship where the first target pressure differential is greater than the second target pressure differential, and the second target pressure differential is greater than the third target pressure differential, a proportional control logic between the severity of transient conditions and the pressure differential between diesel and alternative fuels is established. Specifically, the maximum pressure differential is provided under the first transient condition, which is the most urgent and requires the strongest ignition effect, to drive more diesel to leak to the alternative fuel side, thereby effectively suppressing emissions. Under milder conditions, a smaller pressure differential is provided to balance fuel economy. This tiered pressure differential control strategy ensures precise matching of diesel ignition quantity under different transient severity levels. It guarantees combustion stability and low emission performance under severe transients, while avoiding excessive fuel injection under mild transients, thus ensuring simultaneous optimization of transient emissions and fuel economy across the entire operating range.

[0082] In some embodiments of this application, the second determining submodule is used to add the alternative fuel rail pressure to the target pressure difference to obtain the target diesel rail pressure.

[0083] This control strategy based on differential pressure superposition ensures that the diesel rail pressure is always precisely higher than the alternative fuel rail pressure by a specific difference, thereby stably controlling the flow of diesel leaking to the alternative fuel side through the internal gap of the injector. This not only ensures that the optimal ignition-blending ratio can be maintained to suppress emissions under different alternative fuel rail pressure fluctuations, but also improves the response speed and execution accuracy of transient control.

[0084] The aforementioned dual-fuel transient emission control device includes a processor and a memory. The acquisition unit, determination unit, and adjustment unit are all stored as program units in the memory, and the processor executes these program units to achieve their respective functions. All of the above modules reside in the same processor; alternatively, the modules may be located in different processors in any combination.

[0085] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0086] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0087] 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.

[0088] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0089] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A dual-fuel transient emission control method, characterized in that, The method is applied to a dual-fuel engine, the dual-fuel engine including a dual-fuel injector having an internal cavity communication structure connecting a diesel fuel line and an alternative fuel inlet, the method comprising: The transient operating parameters of the dual-fuel engine are obtained, including the transient fuel quantity change rate and the speed change rate. Based on the values ​​of the transient operating condition parameters and the magnitude of the preset threshold, the level of the transient operating condition of the dual-fuel engine is determined. The levels of the transient operating condition include a first transient operating condition, a second transient operating condition, and a third transient operating condition, which are successively reduced in urgency. According to the level of the transient operating condition, the pressure difference between the diesel rail pressure and the alternative fuel rail pressure is adjusted to drive diesel through the internal cavity connecting structure into the alternative fuel inlet, and then mixed with the alternative fuel before entering the combustion chamber.

2. The method according to claim 1, characterized in that, Based on the values ​​of the transient operating parameters and the magnitude of a preset threshold, the level of the transient operating condition of the dual-fuel engine is determined, including: If the transient fuel quantity change rate is greater than the first transient fuel quantity change threshold, or the speed change rate is greater than the first speed change threshold, the dual-fuel engine is determined to be in the first transient operating condition. If the transient fuel quantity change rate is greater than the second transient fuel quantity change threshold and less than the first transient fuel quantity change threshold, or if the speed change rate is greater than the second speed change threshold and less than the first speed change threshold, the dual-fuel engine is determined to be in the second transient operating condition. If the transient fuel quantity change rate is less than the second transient fuel quantity change threshold, or the speed change rate is less than the second speed change threshold, the dual-fuel engine is determined to be in the third transient operating condition.

3. The method according to claim 1, characterized in that, Adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition includes: Based on the level of the transient operating condition, the diesel rail pressure and the alternative fuel rail pressure are adjusted so that the diesel rail pressure is higher than the alternative fuel rail pressure.

4. The method according to claim 3, characterized in that, Adjusting the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition includes: Based on the level of the transient operating condition, the target opening degree of the alternative fuel metering unit and the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure are determined by querying the preset rail pressure calibration mapping table. Based on the target opening degree of the alternative fuel metering unit, the alternative fuel rail pressure under the current operating conditions is determined, and the target diesel rail pressure is determined based on the alternative fuel rail pressure and the target pressure difference. Based on the target diesel rail pressure, the target opening degree of the diesel pressure control valve is determined by consulting the preset rail pressure calibration mapping table. The opening degree of the alternative fuel metering unit and the opening degree of the diesel pressure control valve are controlled to reach the corresponding target opening degree.

5. The method according to claim 4, characterized in that, Based on the level of the transient operating condition, the target opening degree of the alternative fuel metering unit is determined by querying a preset rail pressure calibration mapping table, including: When the dual-fuel engine is in the first transient operating condition, the target opening degree of the alternative fuel metering unit is determined to be the first opening degree according to the preset rail pressure calibration mapping table. When the dual-fuel engine is in the second transient operating condition, the target opening degree of the alternative fuel metering unit is determined to be the second opening degree according to the preset rail pressure calibration mapping table; When the dual-fuel engine is in the third transient operating condition, the target opening degree of the alternative fuel metering unit is determined to be the third opening degree according to the preset rail pressure calibration mapping table. Wherein, the first opening degree is smaller than the second opening degree, and the second opening degree is smaller than the third opening degree.

6. The method according to claim 4, characterized in that, Based on the level of the transient operating condition, a preset rail pressure calibration mapping table is consulted to determine the target pressure difference between the diesel rail pressure and the alternative fuel rail pressure, including: When the dual-fuel engine is in the first transient operating condition, the target pressure difference is determined to be the first target pressure difference; When the dual-fuel engine is in the second transient operating condition, the target pressure difference is determined to be the second target pressure difference; When the dual-fuel engine is in the third transient operating condition, the target pressure difference is determined to be the third target pressure difference; Wherein, the first target pressure difference is greater than the second target pressure difference, and the second target pressure difference is greater than the third target pressure difference.

7. The method according to claim 4, characterized in that, Determining the target diesel rail pressure based on the alternative fuel rail pressure and the target pressure difference includes: The target diesel rail pressure is obtained by adding the alternative fuel rail pressure to the target pressure difference.

8. A dual-fuel injector, characterized in that, include: The injector body is equipped with a diesel pressure chamber and an alternative fuel inlet; An internal cavity connecting structure is formed in the injector body, connecting the diesel pressure chamber and the alternative fuel inlet, so that when the pressure in the diesel pressure chamber is higher than the pressure at the alternative fuel inlet, diesel can enter the alternative fuel inlet through the internal cavity connecting structure.

9. A dual-fuel engine, characterized in that, include: The dual-fuel injector as described in claim 8; A controller, connected to the dual-fuel injector, is configured to perform the dual-fuel transient emission control method according to any one of claims 1 to 7 to control the operation of the dual-fuel injector.

10. A dual-fuel transient emission control device, characterized in that, include: The acquisition unit is used to acquire the transient operating parameters of the dual-fuel engine, including the transient fuel quantity change rate and the speed change rate. The determining unit is used to determine the level of the transient condition of the dual-fuel engine based on the value of the transient condition parameter and the size of the preset threshold. The levels of the transient condition include a first transient condition, a second transient condition, and a third transient condition with decreasing urgency. The regulating unit is used to adjust the pressure difference between the diesel rail pressure and the alternative fuel rail pressure according to the level of the transient operating condition, so as to drive the diesel fuel through the internal cavity connecting structure into the alternative fuel inlet, and mix it with the alternative fuel before entering the combustion chamber.

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