Dual fuel supply system, control method thereof and dual fuel engine

Abstract

The present invention relates to the field of engine technology, specifically disclosing a dual-fuel supply system, a control method thereof, and a dual-fuel engine. The dual-fuel supply system includes a first fuel supply device and a second fuel supply device. The first fuel supply device is provided with an oil pump and a composite oil rail. The composite oil rail includes a high-pressure oil rail and a pressure regulating valve. The outlet of the high-pressure oil rail is connected to the first fuel inlet of the fuel injector. The second fuel supply device is provided with an electric pressure control valve and a high-pressure gas rail. The outlet of the high-pressure gas rail is connected to the second fuel inlet of the fuel injector. The outlet of the pressure regulating valve is connected to the control oil port of the fuel injector and is used to open or close the control valve of the fuel injector. The high-pressure oil rail and the pressure regulating valve are combined into a composite oil rail. Only a single oil pump is used to supply fuel and control oil to the fuel injector. Compared with the prior art, one oil pump and corresponding pipeline are eliminated, thereby reducing structural complexity and reducing the space occupied by the engine compartment.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a dual-fuel supply system, a control method thereof, and a dual-fuel engine. Background Art

[0002] Dual-fuel engines generally use both liquid and gaseous fuels, each with its own independent supply system for feeding fuel to the fuel injectors. The fuel injectors inject fuel into the combustion chamber using control oil. Specifically, this control oil enters the fuel injector's control port and pushes the injector's control valve, opening or closing it to control the injector's injection. Conventional control oil requires a separate oil circuit system, requiring at least two oil pumps, one for fuel and one for control oil. This results in a complex structure and occupies a significant amount of space in the engine compartment. Summary of the Invention

[0003] The object of the present invention is to provide a dual-fuel supply system, a control method thereof and a dual-fuel engine to solve the problem of a large number of parts in the existing fuel cell air system.

[0004] The present invention provides a dual fuel supply system, comprising a fuel injector for injecting fuel into a combustion chamber, a first fuel supply device, and a second fuel supply device. The first fuel supply device is provided with an oil pump and a composite oil rail. The oil pump is used to pump oil into the composite oil rail. The composite oil rail includes a high-pressure oil rail and a pressure regulating valve. The outlet of the high-pressure oil rail is communicated with a first fuel inlet of the fuel injector and is capable of supplying fuel to the first fuel inlet. The second fuel supply device is provided with an electric pressure control valve and a high-pressure gas rail. The electric pressure control valve is used to change the pressure of gaseous fuel in the high-pressure gas rail. The outlet of the high-pressure gas rail is communicated with a second fuel inlet of the fuel injector and is capable of supplying gaseous fuel to the second fuel inlet. The inlet of the pressure regulating valve is communicated with the high-pressure oil rail, and the outlet is communicated with a control oil port of the fuel injector, and is used to open or close the control valve of the fuel injector.

[0005] As a preferred technical solution of the dual fuel supply system, it also includes a first sensor and a second sensor, the first sensor is used to measure the pressure and temperature values ​​at the outlet of the high-pressure fuel rail, and the second sensor is used to measure the pressure and temperature values ​​at the outlet of the pressure regulating valve.

[0006] As a preferred technical solution of the dual fuel supply system, a third sensor is further included, and the third sensor is used to measure the pressure value and temperature value at the outlet of the high-pressure gas rail.

[0007] As a preferred technical solution of the dual fuel supply system, a fuel injector is provided on the communication path between the high-pressure fuel rail and the fuel injector, and the fuel injector is used to open or close the communication path between the high-pressure fuel rail and the fuel injector.

[0008] As an optimal technical solution for the dual fuel supply system, it also includes an ECU, and the first sensor, the second sensor, the third sensor, the oil pump and the electric pressure control valve are all communicatively connected to the ECU. The oil pump can change the pumping power according to the pressure value and temperature value measured by the first sensor and / or the second sensor, and the electric pressure control valve can change the opening according to the pressure value and temperature value measured by the third sensor.

[0009] The present invention provides a control method for a dual fuel supply system, which is applied to the dual fuel supply system of any of the above solutions. The control method for the dual fuel supply system includes:

[0010] Selecting a fuel supply mode, wherein the fuel supply mode includes an oil supply mode, an air supply mode, and a mixed supply mode;

[0011] The first fuel supply device and / or the second fuel supply device is selected to supply fuel to the fuel injector according to the selected fuel supply mode.

[0012] As a preferred technical solution for the control method of the dual fuel supply system, when the fuel supply mode is selected as the single fuel supply mode:

[0013] The oil pump supplies oil to the composite oil rail;

[0014] Adjust the oil pump power so that the oil pressure in the high-pressure fuel rail is within the preset injection pressure range;

[0015] The pressure regulating valve supplies control oil to the fuel injector, turning on the control valve of the fuel injector;

[0016] The high-pressure rail supplies fuel to the fuel injectors;

[0017] The fuel injectors spray fuel into the combustion chambers.

[0018] As a preferred technical solution for the control method of the dual fuel supply system, when the fuel supply mode is selected as the single gas supply mode:

[0019] The oil pump supplies oil to the composite oil rail, and the electric pressure control valve opens to supply gas to the high-pressure gas rail;

[0020] Adjust the opening of the electric pressure control valve so that the air pressure in the high-pressure air rail is within the preset injection pressure range;

[0021] Adjust the oil pump power so that the pressure at the outlet of the pressure regulating valve is greater than the air pressure in the high-pressure gas rail;

[0022] The pressure regulating valve supplies control oil to the fuel injector, turning on the control valve of the fuel injector;

[0023] A high-pressure gas rail supplies gaseous fuel to the fuel injectors;

[0024] The fuel injectors inject gaseous fuel into the combustion chambers.

[0025] As a preferred technical solution for the control method of the dual fuel supply system, when the fuel supply mode is selected as the mixed supply mode:

[0026] The oil pump supplies oil to the composite oil rail, and the electric pressure control valve opens to supply gas to the high-pressure gas rail;

[0027] Adjust the oil pump power so that the oil pressure in the high-pressure fuel rail is within the preset injection pressure range;

[0028] The pressure regulating valve supplies control oil to the fuel injector, turning on the control valve of the fuel injector;

[0029] Adjust the opening of the electric pressure control valve so that the air pressure in the high-pressure rail is lower than the pressure at the outlet of the pressure regulating valve;

[0030] The fuel injectors spray oil and gaseous fuel into the combustion chambers.

[0031] The present invention provides a dual-fuel engine, including the dual-fuel supply system of the above solution or a control method using the dual-fuel supply system of the above solution.

[0032] The beneficial effects of the present invention are:

[0033] The present invention provides a dual-fuel supply system that combines a high-pressure fuel rail and a pressure regulating valve into a composite fuel rail, thereby using only one fuel pump to supply fuel and control oil to the fuel injectors. Compared with the prior art, this system eliminates one fuel pump and corresponding pipelines, reduces structural complexity, and reduces the space occupied by the engine compartment.

[0034] The present invention provides a control method for a dual-fuel supply system. By setting up the dual-fuel supply system of the present invention, while satisfying different fuel supply modes, the setting of a composite fuel rail makes the control process more convenient.

[0035] The present invention provides a dual-fuel engine, which reduces cost and space occupation and makes the control process simpler by providing a dual-fuel supply system or using a control method of the dual-fuel supply system in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the principle of the dual fuel supply system in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the principle of a composite fuel rail in an embodiment of the present invention;

[0038] Figure 3 This is a flow chart of a dual fuel supply system operating in a single fuel supply mode according to an embodiment of the present invention;

[0039] Figure 4 This is a flow chart of a dual fuel supply system operating in a single gas supply mode according to an embodiment of the present invention;

[0040] Figure 5 FIG. 4 is a flow chart of a dual fuel supply system operating in a mixed supply mode according to an embodiment of the present invention.

[0041] In the picture:

[0042] 11. High-pressure gas source; 12. Electric pressure control valve; 13. High-pressure gas rail; 21. Fuel tank; 22. Fuel pump; 23. Composite fuel rail; 231. High-pressure fuel rail; 232. Pressure regulating valve; 3. ECU; 4. Fuel injector; 5. Combustion chamber; 61. First sensor; 62. Second sensor; 63. Third sensor. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0045] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0046] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0047] like Figure 1-Figure 2As shown, the present invention provides a dual-fuel supply system for a dual-fuel engine. The system includes a fuel injector 4 for injecting fuel into a combustion chamber 5. Specifically, the fuel injector 4 can be a liquid fuel, such as oil, or a gaseous fuel, such as natural gas or petroleum gas. Depending on the actual operating conditions of the engine, the fuel injector 4 can inject only oil or gaseous fuel into the combustion chamber 5, or it can inject both oil and gaseous fuel simultaneously. The fuel injector 4 is a conventional structure and will not be described in detail here. The dual-fuel supply system also includes a first fuel supply device and a second fuel supply device. The first fuel supply device supplies fuel to the fuel injector 4, and the second fuel supply device supplies gaseous fuel to the fuel injector 4. In this embodiment, the fuel can be gasoline or diesel, preferably diesel; the gaseous fuel can be natural gas, petroleum gas, or biomass gas, preferably natural gas. The first fuel supply device is equipped with an oil pump 22 and a composite fuel rail 23. The inlet of the oil pump 22 is connected to the fuel tank 21, and the outlet of the oil pump 22 is connected to the composite fuel rail 23. The oil pump 22 is used to draw fuel from the fuel tank 21 and pump fuel into the composite fuel rail 23. The composite fuel rail 23 includes a high-pressure fuel rail 231 and a pressure regulating valve 232 connected to the end of the high-pressure fuel rail 231. The outlet of the high-pressure fuel rail 231 communicates with the first fuel inlet of the fuel injector 4, and is capable of supplying fuel to the first fuel inlet. The second fuel supply device includes an electric pressure control valve 12 and a high-pressure gas rail 13. The electric pressure valve is positioned between the high-pressure gas rail 13 and the flow path of the high-pressure gas source 11. The electric pressure control valve 12 is used to change the pressure of the gaseous fuel within the high-pressure gas rail 13. The outlet of the high-pressure gas rail 13 communicates with the second fuel inlet of the fuel injector 4, and is capable of supplying gaseous fuel to the second fuel inlet. The inlet of the pressure regulating valve 232 is connected to the high-pressure rail 231, and the outlet is connected to the control port of the fuel injector 4. The pressure regulating valve 232 can adjust the pressure difference between the outlet and inlet pressures by adjusting the preload of the internal spring. This allows the pressure of the oil entering the control port of the fuel injector 4 from the outlet of the pressure regulating valve 232 to be variable, thus enabling it to open or close the control valve of the fuel injector 4. Those skilled in the art can also configure the pressure regulating valve 232 as a proportionally adjustable boost valve or pressure reducing valve as required. In this embodiment, the high-pressure rail 231 and the pressure regulating valve 232 together form the composite rail 23. Therefore, the oil flowing from the pressure regulating valve 232 to the control port of the fuel injector 4 is fuel, and a corresponding oil return line is provided to allow the fuel to flow back to the fuel tank 21. When the control valve of the fuel injector 4 is open, the fuel injector 4 receives the injection command transmitted by the ECU 3 and injects the fuel supplied by the first fuel supply device and / or the second fuel supply device into the combustion chamber 5 of the engine.

[0048] In this embodiment, the high-pressure oil rail 231 and the pressure regulating valve 232 are combined into a composite oil rail 23, so that only one oil pump 22 is used to supply fuel and control oil to the fuel injector 4. Compared with the prior art, one oil pump 22 and corresponding pipelines are reduced, the structural complexity is reduced, and the space occupied by the engine compartment is reduced.

[0049] Furthermore, a first sensor 61 and a second sensor 62 are connected to the composite oil rail 23. Both are configured as pressure sensors or temperature-pressure sensors. In this embodiment, both are preferably temperature-pressure sensors. The first sensor 61 is used to measure the pressure and temperature within or at the outlet of the high-pressure oil rail 231, while the second sensor 62 is used to measure the pressure and temperature at the outlet of the pressure regulating valve 232. The first and second sensors 61 and 62 measure the pressure and temperature at the outlets of the high-pressure oil rail 231 and the pressure regulating valve 232, respectively, enabling the power of the oil pump 22 to be adjusted to ensure that the pressure and temperature at the outlets of the high-pressure oil rail 231 and the pressure regulating valve 232 meet operating requirements. A third sensor 63 is also provided on the high-pressure gas rail 13. This third sensor 63 measures the pressure and temperature within or at the outlet of the high-pressure gas rail 13, thereby further adjusting the opening of the electric pressure control valve 12 and changing the pressure and temperature within the high-pressure gas rail 13 to ensure that the pressure and temperature within the high-pressure gas rail 13 meet operating requirements.

[0050] It will be appreciated that regardless of the operating mode of the fuel injector 4, the oil pump 22 always pumps oil into the composite fuel rail 23. That is, the fuel in the high-pressure fuel rail 231 always maintains a certain oil pressure, allowing the oil at the outlet of the pressure regulating valve 232 to control the fuel injector 4. Therefore, a fuel injector is provided in the communication path between the high-pressure fuel rail 231 and the fuel injector 4. The fuel injector is used to open or close the communication path between the high-pressure fuel rail 231 and the fuel injector 4. The provision of the fuel injector prevents the high-pressure fuel rail 231 from supplying excess fuel when gas fuel is supplied alone. Similarly, to prevent the high-pressure gas rail 13 from supplying excess gas fuel to the fuel injector 4 when fuel fuel is supplied alone, an air nozzle can be provided between the high-pressure gas rail 13 and the fuel injector 4. The air nozzle is used to open or close the communication path between the high-pressure gas rail 13 and the fuel injector 4.

[0051] Specifically, the dual-fuel supply system also includes an ECU 3. A first sensor 61, a second sensor 62, a third sensor 63, an oil pump 22, an electric pressure control valve 12, a fuel tank 21, and a high-pressure gas source 11 are all communicatively connected to the ECU 3. The oil pump 22 can vary its pumping power based on the pressure and temperature values ​​measured by the first sensor 61 and / or the second sensor 62, thereby changing the fuel pressure within the high-pressure fuel rail 231 and the pressure at the outlet of the pressure regulating valve 232. The electric pressure control valve 12 can vary its opening based on the pressure and temperature values ​​measured by the third sensor 63, thereby changing the pressure of the gas fuel within the high-pressure gas rail 13. A fuel level sensor is installed within the fuel tank 21 to provide a timely alarm when fuel is low and to switch the fuel supply mode to gas fuel only to avoid power interruptions. A pressure sensor is also installed within the high-pressure gas source 11 to provide a timely alarm when the gas fuel pressure within the high-pressure gas source 11 is low and to switch the fuel supply mode to fuel fuel only to avoid power interruptions.

[0052] The present invention provides a control method for a dual-fuel supply system, which is applied to the dual-fuel supply system in this embodiment. The control method for the dual-fuel supply system includes the following steps:

[0053] Select a fuel supply mode, which includes a separate oil supply mode, a separate gas supply mode, and a mixed supply mode;

[0054] After the fuel supply mode is selected, the ECU 3 sends a corresponding control signal and selects the first fuel supply device and / or the second fuel supply mode to supply fuel to the fuel injector 4 according to the selected fuel supply mode.

[0055] The switch can be made manually or automatically by the onboard computer based on factors such as the vehicle's load and power requirements during the current driving conditions. When the fuel supply mode is selected, only the first fuel supply device supplies fuel to the fuel injector 4. When the gas supply mode is selected, only the second fuel supply device supplies gaseous fuel to the fuel injector 4. When the mixed supply mode is selected, the first fuel supply device supplies fuel to the fuel injector 4, and the second fuel supply device supplies gaseous fuel to the fuel injector 4.

[0056] Specifically, if Figure 3 As shown, when the fuel supply mode is selected as the single fuel supply mode, the control method of the dual fuel supply system includes the following steps:

[0057] ECU3 sends out fuel injection signal;

[0058] The oil pump 22 supplies oil to the composite oil rail 23;

[0059] The power of the oil pump 22 is adjusted according to the pressure and temperature values ​​measured by the first sensor 61 and the second sensor 62, so that the oil pressure in the high-pressure oil rail 231 is within the preset injection pressure range, and at the same time, the pressure at the outlet of the pressure regulating valve 232 is sufficient to open the control valve of the fuel injector 4;

[0060] The pressure regulating valve 232 supplies control oil to the fuel injector 4, thereby opening the control valve of the fuel injector 4;

[0061] The fuel injector is opened and the high pressure fuel rail 231 supplies fuel to the fuel injector 4;

[0062] The fuel injector 4 injects fuel into the combustion chamber 5 .

[0063] The preset injection pressure range is determined by the onboard computer based on current operating conditions and engine calibration procedures. The relevant internals are state-of-the-art and are not specifically defined herein. When the fuel supply mode is set to single fuel supply, the air nozzle blocks the flow path between the high-pressure gas rail 13 and the fuel injector 4. The electric pressure control valve 12 remains open but does not adjust its opening. This ensures that when the fuel supply mode is switched, the high-pressure gas rail 13 can immediately supply gaseous fuel to the fuel injector 4, avoiding power interruptions or delays.

[0064] Specifically, if Figure 4 As shown, when the fuel supply mode is selected as the single gas supply mode, the control method of the dual fuel supply system includes the following steps:

[0065] ECU3 sends out an injection signal;

[0066] The oil pump 22 supplies oil to the composite oil rail 23, and the electric pressure control valve 12 opens to supply gas to the high-pressure gas rail 13;

[0067] Adjust the opening of the electric pressure control valve 12 according to the pressure and temperature values ​​measured by the third sensor 63 so that the air pressure in the high-pressure air rail 13 is within the preset injection pressure range;

[0068] The power of the oil pump 22 is adjusted according to the pressure value and temperature value at the outlet of the pressure regulating valve 232 measured by the second sensor 62, so that the pressure value at the outlet of the pressure regulating valve 232 is greater than the air pressure value in the high-pressure gas rail 13 measured by the third sensor 63;

[0069] The pressure regulating valve 232 supplies control oil to the fuel injector 4, thereby opening the control valve of the fuel injector 4;

[0070] The nozzle opens and the high pressure gas rail 13 supplies gaseous fuel to the fuel injector 4;

[0071] The fuel injector 4 injects gaseous fuel into the combustion chamber 5 .

[0072] The preset injection pressure range is determined by the onboard computer based on current operating conditions and engine calibration procedures. The relevant internal details are state of the art and are not specifically defined herein. Ensuring that the pressure at the outlet of pressure regulating valve 232 is greater than the pressure within high-pressure rail 13 measured by third sensor 63 ensures that the pressure of the gaseous fuel supplied to fuel injector 4 is lower than the pressure of the control oil within fuel injector 4, preventing gaseous fuel from entering pressure regulating valve 232 and high-pressure rail 231 along the control line. When the fuel supply mode is set to single gas supply, the fuel injector shuts off the flow path between high-pressure rail 231 and fuel injector 4, and the gaseous fuel is burned and produced through compression ignition. The fuel pump 22 is always on, providing pressure to pressure regulating valve 232 and ensuring that fuel from high-pressure rail 231 is immediately supplied to fuel injector 4 when the fuel supply mode is switched, avoiding power interruptions or delays. In other embodiments, the fuel injector may not be completely closed, so that a small amount of fuel enters the combustion chamber 5 together with the gas fuel. The fuel burns first and ignites the gas fuel. In this process, the fuel is only used to ignite the gas fuel and does not affect the power characteristics of the engine under this fuel supply mode.

[0073] Specifically, if Figure 5 As shown, when the fuel supply mode is selected as the mixed supply mode, the control method of the dual fuel supply system includes the following steps:

[0074] ECU3 sends fuel injection and air jet signals;

[0075] The oil pump 22 supplies oil to the composite oil rail 23, and the electric pressure control valve 12 opens to supply gas to the high-pressure gas rail 13;

[0076] The power of the oil pump 22 is adjusted according to the pressure and temperature values ​​measured by the first sensor 61 and the second sensor 62, so that the oil pressure in the high-pressure oil rail 231 is within the preset injection pressure range, and at the same time, the pressure at the outlet of the pressure regulating valve 232 is sufficient to open the control valve of the fuel injector 4;

[0077] The pressure regulating valve 232 supplies control oil to the fuel injector 4, thereby opening the control valve of the fuel injector 4;

[0078] Adjust the opening of the electric pressure control valve 12 according to the pressure value and temperature value measured by the third sensor 63, so that the air pressure value in the high-pressure gas rail 13 measured by the third sensor 63 is lower than the pressure value at the outlet of the pressure regulating valve 232;

[0079] The fuel injector is open, the air nozzle is open, and the high-pressure oil rail 231 and the high-pressure gas rail 13 supply fuel oil and gas fuel to the fuel injector 4 respectively;

[0080] The fuel injector 4 injects fuel oil and gaseous fuel into the combustion chamber 5 .

[0081] The air pressure within the high-pressure gas rail 13, as measured by the third sensor 63, is set to be lower than the pressure at the outlet of the pressure regulating valve 232. This ensures that the pressure of the gaseous fuel supplied to the fuel injector 4 is lower than the pressure of the control oil of the fuel injector 4, thereby preventing the gaseous fuel from entering the pressure regulating valve 232 and the high-pressure fuel rail 231 along the control line. In the mixed supply mode, by adjusting the power of the oil pump 22 and the opening of the electric pressure control valve 12, combined with varying the opening time of the fuel injector and the air jet nozzle, the fuel oil and gaseous fuel can be mixed in any proportion and then combusted in the combustion chamber 5, achieving a balance between engine power and fuel economy.

[0082] The present invention provides a dual-fuel engine, including the dual-fuel supply system of this embodiment or a method for using the dual-fuel supply system of this embodiment. By providing the dual-fuel supply system of this embodiment or using the control method of the dual-fuel supply system, costs and space requirements are reduced, and the control process is simplified.

[0083] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A dual fuel supply system comprising a fuel injector (4) for injecting fuel into a combustion chamber (5), characterized in that: Also includes: A first fuel supply device and a second fuel supply device, wherein the first fuel supply device is provided with an oil pump (22) and a composite oil rail (23), wherein the oil pump (22) is used to pump oil to the composite oil rail (23), wherein the composite oil rail (23) comprises a high-pressure oil rail (231) and a pressure regulating valve (232), and only one oil pump is used to supply fuel and control oil to the fuel injector (4), wherein the outlet of the high-pressure oil rail (231) is connected to the first fuel inlet of the fuel injector (4) and can supply fuel to the first fuel inlet, and the second fuel rail (232) is connected to the first fuel inlet of the fuel injector (4). The material supply device is provided with an electric pressure control valve (12) and a high-pressure gas rail (13). The electric pressure control valve (12) is used to change the pressure of the gas fuel in the high-pressure gas rail (13). The outlet of the high-pressure gas rail (13) is connected to the second fuel inlet of the fuel injector (4) and can supply gas fuel to the second fuel inlet. The inlet of the pressure regulating valve (232) is connected to the high-pressure oil rail (231), and the outlet is connected to the control oil port of the fuel injector (4), and is used to conduct or cut off the control valve of the fuel injector (4).

2. The dual fuel supply system according to claim 1, characterized in that: The invention also includes a first sensor (61) and a second sensor (62), wherein the first sensor (61) is used to measure the pressure and temperature values ​​at the outlet of the high-pressure oil rail (231), and the second sensor (62) is used to measure the pressure and temperature values ​​at the outlet of the pressure regulating valve (232).

3. The dual fuel supply system according to claim 2, characterized in that: The invention also comprises a third sensor (63), wherein the third sensor (63) is used to measure the pressure value and the temperature value at the outlet of the high-pressure gas rail (13).

4. The dual fuel supply system according to claim 3, characterized in that: A fuel injection nozzle is provided on the communication path between the high-pressure fuel rail (231) and the fuel injector (4), and the fuel injection nozzle is used to open or close the communication flow path between the high-pressure fuel rail (231) and the fuel injector (4).

5. The dual fuel supply system according to claim 4, characterized in that: The invention also includes an ECU (3), wherein the first sensor (61), the second sensor (62), the third sensor (63), the oil pump (22) and the electric pressure control valve (12) are all communicatively connected to the ECU (3), the oil pump (22) can change the oil pumping power according to the pressure value and temperature value measured by the first sensor (61) and / or the second sensor (62), and the electric pressure control valve (12) can change the opening degree according to the pressure value and temperature value measured by the third sensor (63).

6. A control method for a dual fuel supply system, characterized in that: Applied to the dual fuel supply system according to any one of claims 1 to 5, the control method of the dual fuel supply system includes: Selecting a fuel supply mode, wherein the fuel supply mode includes an oil supply mode, an air supply mode, and a mixed supply mode; The first fuel supply device and / or the second fuel supply device is selected to supply fuel to the fuel injector (4) according to the selected fuel supply mode.

7. The control method of the dual fuel supply system according to claim 6, characterized in that: When the fuel supply mode is selected as the separate fuel supply mode: The oil pump (22) supplies oil to the composite oil rail (23); Regulating the power of the oil pump (22) so that the oil pressure in the high-pressure oil rail (231) is within a preset injection pressure range; The pressure regulating valve (232) supplies control oil to the fuel injector (4), thereby opening the control valve of the fuel injector (4); The high pressure fuel rail (231) supplies fuel to the fuel injector (4); The fuel injector (4) injects fuel into the combustion chamber (5).

8. The control method of the dual fuel supply system according to claim 6, characterized in that: When the fuel supply mode is selected as the separate air supply mode: The oil pump (22) supplies oil to the composite oil rail (23), and the electric pressure control valve (12) opens to supply air to the high-pressure air rail (13); Adjusting the opening of the electric pressure control valve (12) so that the air pressure in the high-pressure air rail (13) is within a preset jet pressure range; Regulating the power of the oil pump (22) so that the pressure at the outlet of the pressure regulating valve (232) is greater than the air pressure in the high-pressure air rail (13); The pressure regulating valve (232) supplies control oil to the fuel injector (4), thereby opening the control valve of the fuel injector (4); The high pressure gas rail (13) supplies gaseous fuel to the fuel injector (4); The fuel injector (4) injects gaseous fuel into the combustion chamber (5).

9. The control method of the dual fuel supply system according to claim 6, characterized in that: When the fuel supply mode is selected as the mixed supply mode: The oil pump (22) supplies oil to the composite oil rail (23), and the electric pressure control valve (12) opens to supply air to the high-pressure air rail (13); Regulating the power of the oil pump (22) so that the oil pressure in the high-pressure oil rail (231) is within a preset injection pressure range; The pressure regulating valve (232) supplies control oil to the fuel injector (4), thereby opening the control valve of the fuel injector (4); Adjusting the opening of the electric pressure control valve (12) so that the air pressure in the high-pressure air rail (13) is less than the pressure at the outlet of the pressure regulating valve (232); The fuel injector (4) injects fuel oil and gaseous fuel into the combustion chamber (5).

10. Dual fuel engine, characterized in that The invention comprises the dual fuel supply system according to any one of claims 1 to 5 or the control method using the dual fuel supply system according to any one of claims 6 to 9.

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