Method for controlling gas pressure of dual-fuel engine, electronic device, and storage medium

Abstract

The application provides a dual-fuel engine gas pressure control method, relates to the technical field of dual-fuel engines, and is applied to a dual-fuel engine.The dual-fuel engine comprises a diesel system and a natural gas system.The natural gas system comprises a natural gas booster pump, a natural gas filter, a high-pressure gas buffer tank and a natural gas rail.The dual-fuel engine gas pressure control method comprises the following steps: obtaining the working condition of the dual-fuel engine;controlling the natural gas booster pump and a flow metering valve according to the engine speed, the pressure value in the high-pressure gas buffer tank and the pressure value in the natural gas rail in the starting state, the load increasing condition and the load decreasing condition of the dual-fuel engine respectively;decoupling the fuel rail pressure and the gas rail pressure; and performing zoned control on the natural gas set pressure so as to reduce the natural gas pressure fluctuation, reduce the adjustment difficulty, cancel the gas pressure control module and reduce the system cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dual-fuel engines, and particularly relates to a dual-fuel engine gas pressure control method, electronic equipment and storage medium. BACKGROUND

[0002] The HPDI engine is a diesel pilot diesel gas dual-fuel engine, and the engine includes a diesel supply system and a natural gas supply system. The diesel supply system components are similar to those of a diesel engine, mainly composed of a high-pressure oil pump, a common rail pipe and an oil injector; the natural gas supply system includes a gas pressure regulating module, a common rail pipe and an oil injector. Among them, the gas pressure regulating module is a mechanical pressure regulating device for adjusting the gas rail pressure according to the fuel rail pressure, so that the adjusted gas rail pressure is always lower than the fuel rail pressure. However, using the gas pressure regulating module for pressure regulation cannot decouple the fuel rail pressure and the gas rail pressure, and the fuel rail pressure and the gas rail pressure are coupled, the fuel pressure cannot be increased alone, the fuel pressure is low, the combustion is not good, and the thermal efficiency is low, resulting in high smoke. SUMMARY

[0003] The present application provides a dual-fuel engine gas pressure control method, electronic equipment and storage medium to at least solve one technical problem in the related art.

[0004] According to one aspect of an embodiment of the present application, a dual-fuel engine gas pressure control method is provided, applied to a dual-fuel engine including a diesel system and a natural gas system, and the dual-fuel engine gas pressure control method includes:

[0005] According to the engine torque, a plurality of natural gas rail pressure setting regions are set, and the plurality of natural gas rail pressure setting regions correspond to a plurality of natural gas rail pressure target values respectively;

[0006] An engine operating state and an engine torque are obtained;

[0007] The natural gas system is controlled according to the engine operating state, the engine torque and the natural gas rail pressure target value.

[0008] As an optional implementation, the natural gas system includes a natural gas booster pump, a natural gas filter, a high-pressure gas buffer tank and a natural gas rail; the engine operating state includes a starting state, an increasing load state and a decreasing load state; and the control of the natural gas system according to the engine operating state, the engine torque and the natural gas rail pressure target value includes obtaining a high-pressure gas buffer tank internal pressure value and a natural gas rail internal pressure value; and controlling the natural gas booster pump and a flow metering valve according to the engine operating state, the engine torque, the natural gas rail pressure target value, the high-pressure gas buffer tank internal pressure value and the natural gas rail internal pressure value.

[0009] As an optional implementation, when the fuel engine is in the starting state: the first natural gas rail pressure target value is determined according to the engine torque; it is judged whether the pressure value in the high-pressure fuel gas buffer tank is greater than the first natural gas rail pressure target value; if the pressure value in the high-pressure fuel gas buffer tank is greater than the first natural gas rail pressure target value, it is judged whether the difference between the pressure value in the natural gas rail and the first natural gas rail pressure target value is less than a first preset difference value; if the difference between the pressure value in the natural gas rail and the first natural gas rail pressure target value is less than the first preset difference value, the natural gas booster pump is started, and the flow metering valve is controlled to be fully opened.

[0010] As an optional implementation, if the pressure value in the high-pressure fuel gas buffer tank is less than the first natural gas rail pressure target value, the diesel system is controlled to start, and the natural gas booster pump is started.

[0011] As an optional implementation, when the fuel engine is in the load increasing state: the second natural gas rail pressure target value is determined according to the engine torque; it is judged whether the pressure value in the high-pressure fuel gas buffer tank is greater than the second natural gas rail pressure target value; if the pressure value in the high-pressure fuel gas buffer tank is greater than the second natural gas rail pressure target value, it is judged whether the difference between the pressure value in the natural gas rail and the second natural gas rail pressure target value is less than a second preset difference value; if the difference between the pressure value in the natural gas rail and the second natural gas rail pressure target value is less than the second preset difference value, the natural gas booster pump is started, and the flow metering valve is controlled to be fully opened.

[0012] As an optional implementation, if the pressure value in the high-pressure fuel gas buffer tank is less than the second natural gas rail pressure target value, the natural gas booster pump is controlled to start, the inflow / outflow amount of natural gas in the high-pressure fuel gas buffer tank is controlled to be 0 through the flow metering valve, and all the natural gas output by the natural gas booster pump enters the natural gas rail through the pipeline until the natural gas rail pressure reaches the second natural gas rail pressure target value.

[0013] As an optional implementation, after all the natural gas output by the natural gas booster pump enters the natural gas rail through the pipeline until the natural gas rail pressure reaches the second natural gas rail pressure target value, the natural gas booster pump is controlled to continue to work, and the inflow amount of natural gas in the high-pressure fuel gas buffer tank is controlled through the control of the flow metering valve.

[0014] As an optional implementation, when the fuel engine is in a reduced load state: the third natural gas rail pressure target value is determined according to the engine torque; it is determined whether the difference between the natural gas rail pressure value and the third natural gas rail pressure target value is less than a third preset difference value; if the difference between the natural gas rail pressure value and the third natural gas rail pressure target value is less than the third preset difference value, the natural gas booster pump is started, and the flow metering valve is controlled to be fully opened.

[0015] Another aspect of the present application also discloses an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete communication with each other through the communication bus, the memory is used for storing a computer program, and the processor is used for executing the steps of the control method of the dual-fuel engine gas pressure by running the computer program stored on the memory.

[0016] Still another aspect of the present application also discloses a computer-readable storage medium, wherein the storage medium stores a computer program, and the computer program is arranged to execute the steps of the control method of the dual-fuel engine gas pressure when running.

[0017] In the embodiments of the present application, a control method of dual-fuel engine gas pressure is provided, which is applied to a dual-fuel engine comprising a diesel system and a natural gas system, and the control method of the dual-fuel engine gas pressure comprises the following steps: a plurality of natural gas rail pressure setting regions are set according to engine torque, and the plurality of natural gas rail pressure setting regions correspond to a plurality of natural gas rail pressure target values respectively; an engine operating state and an engine torque are acquired; and the engine operating state, the engine torque and the natural gas rail pressure target value control the natural gas system. The coupling between the fuel rail pressure and the gas rail pressure is released, the fuel pressure can be increased alone, so that better combustion effect is obtained, the thermal efficiency is improved, and the smoke emission is reduced; the natural gas setting pressure is controlled in a partitioned manner, so as to reduce the natural gas pressure fluctuation and the adjustment difficulty, and in addition, the gas pressure control module is cancelled, so that the system cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate an embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0020] Figure 1 is a flow chart of an optional control method of gas pressure of a dual-fuel engine according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to enable persons skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative labor should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] The HPDI engine is a diesel pilot diesel-gas dual-fuel engine, and the engine includes a diesel supply system and a natural gas supply system. The components of the diesel supply system are similar to those of a diesel engine, and mainly consist of a high-pressure oil pump, a common rail pipe and an oil injector; the natural gas supply system includes a gas pressure regulating module, a common rail pipe and an oil injector. Among them, the gas pressure regulating module is a mechanical pressure regulating device for adjusting the gas rail pressure according to the fuel rail pressure, so that the adjusted gas rail pressure is always lower than the fuel rail pressure. However, using the gas pressure regulating module for pressure regulation cannot decouple the fuel rail pressure and the gas rail pressure, the fuel rail pressure and the gas rail pressure are coupled, the fuel pressure cannot be raised alone, the fuel pressure is low, the combustion is not good, resulting in low thermal efficiency and high smoke.

[0024] When the engine is running, first, the diesel rail pressure is established, the engine operating condition is determined by the electronic control unit according to the throttle signal (which can be obtained by the throttle pedal) and the engine speed signal (which can be obtained by the phase sensor), the pump oil amount of the high-pressure oil pump is controlled according to the specific operating condition, the high-pressure diesel is established in the oil rail, and the size of the diesel pressure is fed back and controlled through the diesel pressure sensor and the electronic control unit, so that the actual pressure of the diesel reaches the target value. The natural gas in the natural gas tank is pressurized by the booster pump to obtain high-pressure natural gas, and the size of the natural gas pressure can be fed back and controlled through the natural gas pressure sensor and the electronic control unit, so that the natural gas pressure reaches the target value as much as possible.

[0025] As shown in Figure 1 The embodiment of the present application provides a dual-fuel engine gas pressure control method, which is applied to a dual-fuel engine including a diesel system and a natural gas system, and the dual-fuel engine gas pressure control method comprises the following steps:

[0026] S1, a plurality of natural gas rail pressure setting regions are set according to engine torque, and the plurality of natural gas rail pressure setting regions correspond to a plurality of natural gas rail pressure target values respectively;

[0027] S2, an engine operating state and engine torque are obtained;

[0028] S3, the natural gas system is controlled according to the engine operating state, the engine torque and the natural gas rail pressure target value.

[0029] The coupling of the fuel rail pressure and the gas rail pressure is released, the fuel pressure can be increased alone, so that better combustion effect is obtained, the thermal efficiency is improved, and the smoke emission is reduced; the natural gas setting pressure is controlled in a partitioned manner, so that the natural gas pressure fluctuation is reduced, the adjustment difficulty is reduced, and in addition, the gas pressure control module is cancelled, so that the system cost is reduced.

[0030] For example, three natural gas rail pressure setting regions can be set, for example, in a first torque range, the natural gas rail pressure target value is set to 180 bar; in a second torque range, the natural gas rail pressure target value is set to 240 bar, and in a third torque range, the natural gas rail pressure target value is set to 300 bar. It should be noted that when the following embodiments are further expanded, the content related to the division of the natural gas rail pressure setting region is an optional implementation manner, and the present application does not limit this, and the specific division manner can be limited according to the selection and parameters of the specific engine.

[0031] As an optional implementation, the natural gas system comprises a natural gas booster pump, a natural gas filter, a high-pressure gas buffer tank and a natural gas rail; the engine operating state comprises a starting state, a load increasing state and a load decreasing state; the control of the natural gas system according to the engine operating state, the engine torque and the natural gas rail pressure target value comprises: obtaining a pressure value in the high-pressure gas buffer tank and a pressure value in the natural gas rail; and controlling the natural gas booster pump and a flow metering valve according to the engine operating state, the engine torque, the natural gas rail pressure target value, the pressure value in the high-pressure gas buffer tank and the pressure value in the natural gas rail.

[0032] As an optional implementation, when the fuel engine is in the starting state: the first natural gas rail pressure target value is determined according to the engine torque; it is determined whether the pressure value in the high-pressure gas buffer tank is greater than the first natural gas rail pressure target value; if the pressure value in the high-pressure gas buffer tank is greater than the first natural gas rail pressure target value, it is determined whether the difference between the pressure value in the natural gas rail and the first natural gas rail pressure target value is less than a first preset difference value; if the difference between the pressure value in the natural gas rail and the first natural gas rail pressure target value is less than the first preset difference value, the natural gas booster pump is started and the flow metering valve is controlled to be fully opened.

[0033] As an optional implementation, if the pressure value in the high-pressure gas buffer tank is less than the first natural gas rail pressure target value, the diesel system is controlled to be started and the natural gas booster pump is started.

[0034] Specifically, for example, when the natural gas rail pressure setting region is divided, the torque range of the engine in the starting state can be in the first torque range. At this time, when the pressure in the buffer tank is greater than 180 bar (i.e. the natural gas rail pressure target value corresponding to the first torque range, which is the first natural gas rail pressure target value in this embodiment), the natural gas booster pump does not work, the flow metering valve is controlled to control the outflow of natural gas from the high-pressure gas buffer tank, and then the pressure in the natural gas rail is controlled to reach or approach the target pressure corresponding to the first torque range. When the difference between the pressure value in the natural gas rail and the first natural gas rail pressure target value is less than -5 bar (i.e. an example value of the first preset difference value, which is not limited in the present application), the natural gas booster pump is started and the flow metering valve is fully opened. When the pressure P3 in the buffer tank is less than 180 bar, the engine is started in the diesel mode, and after starting, the natural gas booster is started and the flow metering valve is fully opened.

[0035] As an optional embodiment, when the fuel engine is in the load-increasing state: the second natural gas rail pressure target value is determined according to the engine torque; it is determined whether the pressure value in the high-pressure fuel gas buffer tank is greater than the second natural gas rail pressure target value; if the pressure value in the high-pressure fuel gas buffer tank is greater than the second natural gas rail pressure target value, it is determined whether the difference between the pressure value in the natural gas rail and the second natural gas rail pressure target value is less than a second preset difference value; if the difference between the pressure value in the natural gas rail and the second natural gas rail pressure target value is less than the second preset difference value, the natural gas booster pump is started, and the flow metering valve is fully opened.

[0036] As an optional embodiment, if the pressure value in the high-pressure fuel gas buffer tank is less than the second natural gas rail pressure target value, the natural gas booster pump is controlled to be started, the inflow / outflow amount of natural gas in the high-pressure fuel gas buffer tank is controlled to be 0 by controlling the flow metering valve, and the natural gas output by the natural gas booster pump is all introduced into the natural gas rail through the pipeline until the pressure in the natural gas rail reaches the second natural gas rail pressure target value.

[0037] As an optional embodiment, after the natural gas output by the natural gas booster pump is all introduced into the natural gas rail through the pipeline until the pressure in the natural gas rail reaches the second natural gas rail pressure target value, the natural gas booster pump is controlled to continue to work, and the inflow amount of natural gas in the high-pressure fuel gas buffer tank is controlled by controlling the flow metering valve to be opened.

[0038] It needs to be understood that when the engine is in the load-increasing state, the engine torque can increase from the first torque range to the third torque range, or from the first torque range to the second torque range, or from the second torque range to the third torque range, and thus the corresponding second natural gas rail pressure target value is not a unique value.

[0039] If the natural gas rail pressure target value increases from the first torque range to the second torque range, when the pressure in the buffer tank is greater than 240 bar, the natural gas booster pump does not work, the outflow amount of natural gas in the high-pressure fuel gas buffer tank is controlled by the flow metering valve, and thus the pressure in the natural gas rail is controlled to reach or approach the target pressure in region 2; when the difference between the pressure value in the natural gas rail and the second natural gas rail pressure target value is less than -5 bar (i.e., the second preset difference value, which can be equal to or not equal to the first preset difference value, and the present application does not limit this), the natural gas booster pump is started, and the flow metering valve is fully opened.

[0040] When the pressure in the buffer tank is less than 240 bar, the natural gas booster pump works immediately, the flow metering valve controls the inflow / outflow of the high-pressure gas buffer tank to be 0, and the natural gas output by the natural gas booster pump enters the natural gas rail through the pipeline. After the pressure of the natural gas rail is quickly raised to 240 bar, the natural gas booster pump continues to work, and the flow metering valve opens to control the inflow of the high-pressure gas buffer tank to ensure that the pressure of the natural gas rail is stable. When the pressure in the buffer tank is greater than 240 bar, the flow metering valve is fully opened.

[0041] Similarly, the engine torque increases from the first torque range to the third torque range, or from the second torque range to the third torque range, which can be controlled according to the above method.

[0042] As an optional embodiment, when the fuel engine is in the reduced load state: determining the third natural gas rail pressure target value according to the engine torque; determining whether the difference between the pressure value in the natural gas rail and the third natural gas rail pressure target value is less than a third preset difference value; if the difference between the pressure value in the natural gas rail and the third natural gas rail pressure target value is less than the third preset difference value, starting the natural gas booster pump and controlling the flow metering valve to be fully opened.

[0043] Similarly, when the engine is in the reduced load state, the engine torque can decrease from the third torque range to the second torque range, or from the second torque range to the first torque range, or from the third torque range to the first torque range, so the corresponding second natural gas rail pressure target value is not a unique value.

[0044] In addition, when the engine is in the stopped state, the natural gas booster pump can be stopped, the flow metering valve controls the inflow / outflow of the high-pressure gas buffer tank to be 0, the diesel injection is stopped, the nozzle is empty, the natural gas is injected, the pressure of the natural gas rail is reduced, and the engine is stopped.

[0045] Another aspect of the present application also discloses an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete communication with each other through the communication bus, the memory is used to store a computer program, and the processor is used to execute the steps of the control method of the dual-fuel engine gas pressure by running the computer program stored in the memory.

[0046] Still another aspect of the present application also discloses a computer-readable storage medium, wherein the storage medium stores a computer program, and the computer program is set to execute the steps of the control method of the dual-fuel engine gas pressure when running.

[0047] As an optional embodiment, the specific examples in the embodiment can refer to the examples described in the above embodiments, and the embodiment will not be described here again.

[0048] Those skilled in the art can understand that the device implementing the above-mentioned method for controlling gas pressure of a dual-fuel engine can be a terminal device, which can be a smart phone (such as an Android phone, an IOS phone, etc.), a tablet computer, a palm computer, a mobile internet device (MID), a PAD, or the like.

[0049] Those skilled in the art can understand that all or part of the steps in the various methods of the above-mentioned embodiments can be completed by instructing the hardware related to the terminal device through a program, which can be stored in a computer readable storage medium, and the storage medium can include a flash disk, a ROM, a RAM, a magnetic disk or an optical disk, etc.

[0050] The serial numbers of the above-mentioned embodiments of the present application are only for description, and do not represent the advantages or disadvantages of the embodiments.

[0051] The integrated units in the above-mentioned embodiments, if realized in the form of software function units and sold or used as independent products, can be stored in the above-mentioned computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that make contributions to the prior art or the whole or part of the technical solutions can be embodied in the form of software products, and the computer software products are stored in the storage medium, including a plurality of instructions for causing one or more electronic devices (which can be personal computers, servers or network devices, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application.

[0052] In the above-mentioned embodiments of the present application, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0053] In the several embodiments provided by the present application, it should be understood that the disclosed client can be implemented in other ways. Of course, the above device embodiment is only a schematic, for example, the division of the units is only a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, units or modules, and can be electrical or other forms.

[0054] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place or distributed on multiple network units. Part or all of the units can be selected to achieve the purpose of the scheme provided in the embodiment according to actual needs.

[0055] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0056] In the above embodiments of the present application, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can refer to the relevant description of other embodiments.

[0057] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A method of controlling gas pressure in a dual-fuel engine, characterized by, The application is applied to a dual-fuel engine, which comprises a diesel system and a natural gas system, the natural gas system comprises a natural gas booster pump, a natural gas filter, a high-pressure gas buffer tank and a natural gas rail; the control method of the dual-fuel engine gas pressure comprises: a plurality of natural gas rail pressure setting areas are set according to engine torque, and the plurality of natural gas rail pressure setting areas correspond to a plurality of natural gas rail pressure target values respectively; an engine operating state and engine torque are obtained; the engine operating state comprises a starting state, a load increasing state and a load decreasing state; the natural gas system is controlled according to the engine operating state, the engine torque and the natural gas rail pressure target value, which comprises: a high-pressure gas buffer tank internal pressure value and a natural gas rail internal pressure value are obtained; the natural gas booster pump and the flow metering valve are controlled according to the engine operating state, the engine torque, the natural gas rail pressure target value, the high-pressure gas buffer tank internal pressure value and the natural gas rail internal pressure value; when the fuel engine is in the load increasing state: a second natural gas rail pressure target value is determined according to the engine torque; it is judged whether the high-pressure gas buffer tank internal pressure value is greater than the second natural gas rail pressure target value; if the high-pressure gas buffer tank internal pressure value is less than the second natural gas rail pressure target value, the natural gas booster pump is controlled to start, the flow metering valve is controlled to make the inflow / outflow amount of the natural gas in the high-pressure gas buffer tank be 0, and the natural gas output by the natural gas booster pump is made to enter the natural gas rail through a pipeline until the natural gas rail pressure reaches the second natural gas rail pressure target value; after the natural gas output by the natural gas booster pump enters the natural gas rail through the pipeline until the natural gas rail pressure reaches the second natural gas rail pressure target value, the natural gas booster pump is controlled to work continuously, and the flow metering valve is controlled to open to control the inflow amount of the natural gas in the high-pressure gas buffer tank. when the fuel engine is in the starting state:

2. The method of controlling gas pressure of a dual fuel engine according to claim 1, characterized by, a first natural gas rail pressure target value is determined according to the engine torque; it is judged whether the high-pressure gas buffer tank internal pressure value is greater than the first natural gas rail pressure target value; if the high-pressure gas buffer tank internal pressure value is greater than the first natural gas rail pressure target value, it is judged whether the difference between the natural gas rail internal pressure value and the first natural gas rail pressure target value is less than a first preset difference value; if the difference between the natural gas rail internal pressure value and the first natural gas rail pressure target value is less than the first preset difference value, the natural gas booster pump is started, and the flow metering valve is controlled to be fully opened. if the high-pressure gas buffer tank internal pressure value is less than the first natural gas rail pressure target value, the diesel system is controlled to start, and the natural gas booster pump is started.

3. The method of controlling fuel gas pressure of a dual fuel engine according to claim 2, characterized by, if the high-pressure gas buffer tank internal pressure value is greater than the second natural gas rail pressure target value, it is judged whether the difference between the natural gas rail internal pressure value and the second natural gas rail pressure target value is less than a second preset difference value; 4. The method of controlling fuel gas pressure of a dual fuel engine according to claim 1, characterized by, ​ If the difference between the natural gas rail pressure value and the second natural gas rail pressure target value is less than a second preset difference value, the natural gas booster pump is started, and the flow metering valve is controlled to be fully open.

5. The method of controlling gas pressure of a dual fuel engine according to claim 1, wherein, When the fuel engine is in a load reduction state: A third natural gas rail pressure target value is determined according to the engine torque; It is judged whether the difference between the natural gas rail pressure value and the third natural gas rail pressure target value is less than a third preset difference value; If the difference between the natural gas rail pressure value and the third natural gas rail pressure target value is less than the third preset difference value, the natural gas booster pump is started, and the flow metering valve is controlled to be fully open.

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