Device for recovering natural gas in a gas supply system, vehicle and control method thereof

Abstract

The present invention belongs to the technical field of vehicles, and discloses a device for recovering natural gas in a gas supply system, a vehicle and its control method. For the device for recovering natural gas in the gas supply system, the first air inlet of the oil-gas separator is communicated with the natural gas bleed port of the gas pressure regulating module, the air inlet of the low-pressure natural gas buffer tank is communicated with the air outlet of the oil-gas separator, the ejector includes a nozzle and a receiving chamber, a mixing chamber and a diffuser chamber that are sequentially communicated, the air outlet of the low-pressure natural gas buffer tank is communicated with the receiving chamber through a first pipeline, the diffuser chamber is communicated with the air inlet of the high-pressure natural gas buffer tank, the air outlet of the high-pressure natural gas buffer tank is communicated with the natural gas inlet of the gas pressure regulating module, the inlet and outlet of the LNG pump are respectively communicated with the LNG tank and the vaporizer, the vaporizer is communicated with the nozzle, and a first valve is arranged on the first pipeline. The structure is simple and the cost is low, which is beneficial to the stability of the engine.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and in particular, to a device for recovering natural gas in a gas supply system, a vehicle, and a control method thereof. Background Art

[0002] Compared with traditional diesel engines, although HPDI (High Pressure Direct Injection) gas engines have inherent advantages in reducing carbon dioxide emissions, since the gas pressure regulating module and the LNG tank will intermittently discharge methane gas into the atmosphere during the normal operation of the HPDI gas engine, its advantages in reducing greenhouse gases will be lost. In the prior art, a low-pressure gas reuse system for a high-pressure direct injection gas engine is provided to recover natural gas. In the low-pressure gas reuse system of the high-pressure direct injection gas engine, in addition to a gas pressure regulating module, an LNG storage bottle, and a high-pressure gas nozzle disposed in the engine cylinder connected by a high-pressure gas pipeline, a low-pressure gas pipeline is also provided. A buffer tank, an electromagnetic cut-off valve, a pressure reducer, and a low-pressure gas nozzle are disposed on the low-pressure gas pipeline. The buffer tank can collect the low-pressure natural gas released by the gas pressure regulating module and the LNG storage bottle. When the pressure in the buffer tank exceeds the preset gas pressure and the engine is in the starting state, the low-pressure gas nozzle injects the low-pressure gas in the buffer tank into the intake manifold. However, during the injection process of the low-pressure gas nozzle in the low-pressure gas pipeline, the gas needs to be pressurized. Therefore, a pressurizing system including an LNG pump is provided in the buffer tank. Compared with only one LNG pump working in the original system, adding one more LNG pump to work will increase the overall power consumption of the system, which is not conducive to the economy of the whole machine. Moreover, an intake manifold is added to the intake passage of each cylinder, and a low-pressure gas nozzle is added to each intake manifold. The engine electronic control unit requires more circuits and modules to increase the control of the low-pressure gas nozzle, which greatly increases the hardware and software requirements of the HPDI gas engine, is not conducive to controlling the cost of the whole machine. Also, by injecting the low-pressure gas into the intake manifold through the low-pressure gas nozzle, the low-pressure gas mixes with the intake air in the intake manifold and enters the cylinder following the intake air flow. The pre-mixing amount is high and the pre-mixing is uneven, and phenomena such as knocking are likely to occur, which is not conducive to the stability of the whole machine. Summary of the Invention

[0003] The purpose of the present invention is to provide a device for recovering natural gas in a gas supply system, a vehicle, and a control method thereof, so as to solve the problems in the prior art that the low-pressure gas reuse system for a high-pressure direct injection gas engine has poor economy, low cost, is prone to phenomena such as knocking, and is not conducive to the stability of the whole machine.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A device for recovering natural gas in a gas supply system, comprising:

[0006] Gas pressure regulating module;

[0007] Oil and gas separator, the first gas inlet of the oil and gas separator is communicated with the natural gas vent of the gas pressure regulating module;

[0008] Low-pressure natural gas buffer tank, the gas inlet of the low-pressure natural gas buffer tank is communicated with the gas outlet of the oil and gas separator;

[0009] Ejector, the ejector includes a nozzle and a receiving chamber, a mixing chamber and a diffuser chamber that are sequentially communicated. The nozzle penetrates through the receiving chamber, and the nozzle is communicated with the inlet of the mixing chamber. The gas outlet of the low-pressure natural gas buffer tank is communicated with the receiving chamber through a first pipeline;

[0010] High-pressure natural gas buffer tank, the diffuser chamber is communicated with the gas inlet of the high-pressure natural gas buffer tank, and the gas outlet of the high-pressure natural gas buffer tank is communicated with the natural gas inlet of the gas pressure regulating module;

[0011] LNG tank, LNG pump and vaporizer, the inlet and outlet of the LNG pump are respectively communicated with the LNG tank and the vaporizer, and the vaporizer is communicated with the nozzle;

[0012] First valve, the first valve is arranged on the first pipeline.

[0013] As a preferred solution of the device for recovering natural gas in the above-mentioned gas supply system, the device for recovering natural gas in the gas supply system further includes a second valve, the second valve is arranged in the ejector. When the second valve is closed, the receiving chamber is disconnected from the mixing chamber; when the second valve is opened, the receiving chamber is communicated with the mixing chamber.

[0014] As a preferred solution of the device for recovering natural gas in the above-mentioned gas supply system, the second valve includes a first barrier member, a second barrier member, an elastic member and an electric driving member. One end of the first barrier member is fixedly arranged at the junction of the receiving chamber and the mixing chamber, the second barrier member is rotatably arranged at the other end of the first barrier member, both ends of the elastic member are fixedly connected with the first barrier member and the second barrier member respectively, the electric driving member is in transmission connection with the second barrier member, and the second barrier member can abut against or separate from the outer shell of the nozzle.

[0015] As a preferred solution of the device for recovering natural gas in the above-mentioned gas supply system, the device for recovering natural gas in the gas supply system further includes a first pressure sensor, and the first pressure sensor is arranged on the low-pressure natural gas buffer tank.

[0016] As a preferred solution of the device for recovering natural gas in the above-mentioned gas supply system, the LNG tank is provided with an LNG tank gas outlet, and the LNG tank gas outlet is communicated with the second air inlet of the oil-gas separator through a second pipeline. The device for recovering natural gas in the gas supply system further includes a third valve, and the third valve is arranged on the second pipeline.

[0017] As a preferred solution of the device for recovering natural gas in the above-mentioned gas supply system, the device for recovering natural gas in the gas supply system further includes a second pressure sensor, and the second pressure sensor is arranged on the LNG tank.

[0018] As a preferred solution of the device for recovering natural gas in the above-mentioned gas supply system, the device for recovering natural gas in the gas supply system further includes a fuel storage tank, and the fuel storage tank is communicated with the fuel outlet of the oil-gas separator.

[0019] As a preferred solution of the device for recovering natural gas in the above-mentioned gas supply system, check valves are arranged on the pipelines between the vaporizer and the nozzle, between the diffuser chamber and the high-pressure natural gas buffer tank, between the high-pressure natural gas buffer tank and the gas pressure regulating module, between the gas pressure regulating module and the oil-gas separator, and between the oil-gas separator and the low-pressure natural gas buffer tank.

[0020] A vehicle includes the device for recovering natural gas in the above-mentioned gas supply system.

[0021] As a preferred solution of the control method of the device for recovering natural gas in the above-mentioned gas supply system, the device for recovering natural gas in the above-mentioned gas supply system is adopted, including:

[0022] Judge whether the pressure of the low-pressure natural gas buffer tank is greater than or equal to the first set pressure;

[0023] If not, close the first valve;

[0024] If so, open the first valve.

[0025] The beneficial effects of the present invention:

[0026] The present invention provides a device for recovering natural gas in a gas supply system, a vehicle and a control method thereof. In the device for recovering natural gas in the gas supply system, after the engine is started, the LNG pump starts to work. The LNG pump is used to pump LNG (Liquefied Natural Gas) in the LNG tank to the vaporizer. The vaporizer vaporizes the liquefied natural gas into high-pressure natural gas and transports it to the nozzle of the ejector. Then, it enters the high-pressure natural gas buffer tank through the mixing chamber and the diffuser chamber of the ejector. The natural gas in the high-pressure natural gas buffer tank supplies gas to the engine cylinder through the gas pressure regulating module. The gas pressure regulating module adjusts the flow rate of the natural gas supplied to the cylinder according to the operating conditions of the engine. The excess natural gas entering the gas pressure regulating module is discharged through the natural gas bleed port and enters the oil-gas separator. The natural gas separated by the oil-gas separator enters the low-pressure natural gas buffer tank. The low-pressure natural gas enters the receiving chamber through the first pipeline. When the pressure in the low-pressure natural gas buffer tank is greater than or equal to the first set pressure, the first valve opens, and the low-pressure natural gas enters the receiving chamber. When natural gas is ejected from the nozzle, the low-pressure natural gas in the receiving chamber enters the mixing chamber and mixes with the high-pressure natural gas ejected from the nozzle, and then enters the high-pressure natural gas buffer tank through the diffuser chamber, thus completing the recovery of natural gas. The device for recovering natural gas in the gas supply system has a simple structure, does not require additional LNG pumps for recovering natural gas, does not require additional low-pressure gas nozzles, and does not require major modifications to the engine, has good economy and low cost. Moreover, the recovered low-pressure natural gas and the high-pressure natural gas ejected from the nozzle enter the high-pressure natural gas buffer tank together and then are supplied to the cylinder through the gas pressure regulating module, which can make the low-pressure natural gas and the high-pressure natural gas fully mixed and then supplied to the cylinder, which is beneficial to the working stability of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic structural diagram of a device for recovering natural gas in a gas supply system provided by a specific embodiment of the present invention;

[0028] Figure 2 FIG. is a partial structural schematic diagram of a device for recovering natural gas in a gas supply system provided by a specific embodiment of the present invention.

[0029] In the figure:

[0030] 1. Gas pressure regulating module; 2. Oil-gas separator; 3. Low-pressure natural gas buffer tank; 4. Ejector; 5. LNG tank; 6. LNG pump; 7. Vaporizer; 8. High-pressure natural gas buffer tank; 9. First valve; 10. Second valve; 11. First pressure sensor; 12. Fuel storage tank; 13. Cylinder; 14. Third valve; 15. First pipeline; 16. Second pipeline; 41. Nozzle; 42. Receiving chamber; 43. Mixing chamber; 44. Diffuser chamber. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only for explaining the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0032] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above and to the right of", and "on top of" the second feature includes the first feature being directly above and diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal height than the second feature. The first feature being "below", "below and to the left of", and "beneath" the second feature includes the first feature being directly below and diagonally below the second feature, or simply indicating that the first feature is at a lower horizontal height than the second feature.

[0034] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "right" are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0035] The present invention provides a device for recovering natural gas in a gas supply system, a vehicle, and a control method thereof, as Figure 1 and Figure 2As shown in the figure, the device for recovering natural gas in the gas supply system includes a gas pressure regulating module 1, an oil-gas separator 2, a low-pressure natural gas buffer tank 3, an ejector 4, a high-pressure natural gas buffer tank 8, an LNG tank 5, an LNG pump 6, a vaporizer 7 and a second valve 10. The first gas inlet of the oil-gas separator 2 is communicated with the natural gas bleeder of the gas pressure regulating module 1. The gas inlet of the low-pressure natural gas buffer tank 3 is communicated with the gas outlet of the oil-gas separator 2. The ejector 4 includes a nozzle 41 and a receiving chamber 42, a mixing chamber 43 and a diffuser chamber 44 that are sequentially communicated. The nozzle 41 penetrates through the receiving chamber 42, and the nozzle 41 is communicated with the inlet of the mixing chamber 43. The gas outlet of the low-pressure natural gas buffer tank 3 is communicated with the receiving chamber 42 through a first pipeline 15. The diffuser chamber 44 is communicated with the gas inlet of the high-pressure natural gas buffer tank 8. The gas outlet of the high-pressure natural gas buffer tank 8 is communicated with the natural gas inlet of the gas pressure regulating module 1. The inlet and outlet of the LNG pump 6 are respectively communicated with the LNG tank 5 and the vaporizer 7. The vaporizer 7 is communicated with the nozzle 41. A first valve 9 is arranged on the first pipeline 15.

[0036] In the device for recovering natural gas in this gas supply system, after the engine starts, the LNG pump 6 begins to operate. The LNG pump 6 is used to pump the LNG (Liquefied Natural Gas) in the LNG tank 5 to the vaporizer 7. The vaporizer 7 vaporizes the liquefied natural gas into high-pressure natural gas and transports it to the nozzle 41 of the ejector 4. Then, it enters the high-pressure natural gas buffer tank 8 through the mixing chamber 43 and the diffuser chamber 44 of the ejector 4. The natural gas in the high-pressure natural gas buffer tank 8 supplies gas to the engine cylinder 13 through the gas pressure regulating module 1. The gas pressure regulating module 1 adjusts the flow rate of the natural gas supplied to the cylinder 13 according to the operating conditions of the engine. The excess natural gas entering the gas pressure regulating module 1 is discharged through the natural gas bleed port and enters the oil-gas separator 2. The natural gas separated by the oil-gas separator 2 enters the low-pressure natural gas buffer tank 3, and the low-pressure natural gas enters the receiving chamber 42 through the first pipeline 15. When the pressure in the low-pressure natural gas buffer tank 3 is greater than or equal to the first set pressure, the first valve 9 opens, and the low-pressure natural gas enters the receiving chamber 42. When the high-pressure natural gas is ejected from the nozzle 41, the low-pressure natural gas in the receiving chamber 42 enters the mixing chamber 43 and mixes with the high-pressure natural gas ejected from the nozzle 41, and then enters the high-pressure natural gas buffer tank 8 through the diffuser chamber 44, thus completing the recovery of natural gas. The structure of the device for recovering natural gas in this gas supply system is simple. There is no need to additionally increase the LNG pump 6 for recovering natural gas, nor is it necessary to add a low-pressure gas nozzle 41. There is no need to substantially modify the engine, with good economy and low cost. Moreover, the recovered low-pressure natural gas and the high-pressure natural gas ejected from the nozzle 41 enter the high-pressure natural gas buffer tank 8 together, and then are supplied to the cylinder 13 through the gas pressure regulating module 1, enabling the low-pressure natural gas and the high-pressure natural gas to be fully mixed before being supplied to the cylinder 13, which is beneficial to the working stability of the engine. When the pressure in the low-pressure natural gas buffer tank 3 is less than the first set pressure, the first valve 9 closes, which can prevent the high-pressure natural gas ejected from the nozzle 41 from entering the low-pressure natural gas buffer tank 3.

[0037] It can be understood that the high-pressure natural gas ejected by the nozzle 41 will entrain the surrounding low-pressure natural gas due to the turbulent diffusion effect of the jet flow, resulting in momentum exchange. The low-pressure natural gas and the high-pressure natural gas are mixed in the mixing chamber 43, and momentum and mass exchange occur. During the flow process, the velocities gradually equalize, and this is often accompanied by an increase in pressure. The mixed gas exits the mixing chamber 43 and enters the diffuser chamber 44, and the pressure continues to increase due to the slowing down of the flow velocity. At the outlet of the diffuser chamber 44, the pressure of the mixed gas is higher than the pressure of the low-pressure natural gas when it enters the receiving chamber 42. Increasing the pressure of the low-pressure natural gas without directly consuming mechanical energy is the most important and fundamental performance of the ejector 4. In addition to its particularly simple structure itself, the system connecting the ejector 4 to various devices is also very simple, and the manufacturing is not complex.

[0038] Optionally, the device for recovering natural gas in the gas supply system further includes a second valve 10. The second valve 10 is disposed in the ejector 4. When the second valve 10 is closed, the receiving chamber 42 is disconnected from the mixing chamber 43. When the second valve 10 is opened, the receiving chamber 42 communicates with the mixing chamber 43. After the low-pressure natural gas in the low-pressure natural gas buffer tank 3 enters the receiving chamber 42, it waits for the second valve 10 to open. When the pressure in the low-pressure natural gas buffer tank 3 is greater than or equal to the first set pressure and the nozzle 41 outputs high-pressure natural gas, the second valve 10 opens, and the low-pressure natural gas is mixed with the high-pressure natural gas in the mixing chamber 43 and flows together with the high-pressure natural gas. Optionally, the second valve 10 includes a first barrier member, a second barrier member, an elastic member, and an electric driving member. One end of the first barrier member is fixedly disposed at the junction of the receiving chamber 42 and the mixing chamber 43. The second barrier member is rotatably disposed at the other end of the first barrier member. The two ends of the elastic member are respectively fixedly connected to the first barrier member and the second barrier member. The electric driving member is in transmission connection with the second barrier member, and the second barrier member can abut against or separate from the outer shell of the nozzle 41. When the second valve 10 is energized, the electric driving member drives the second barrier member to rotate relative to the first barrier member until the second barrier member abuts against the outer shell of the nozzle 41. At this time, the second valve 10 disconnects the receiving chamber 42 from the mixing chamber 43. When the second valve 10 is de-energized, the second barrier member rotates back under the drive of the elastic member to separate the second barrier member from the outer shell of the nozzle 41. At this time, the second valve 10 connects the receiving chamber 42 to the mixing chamber 43.

[0039] Optionally, the device for recovering natural gas in the gas supply system further includes a first pressure sensor 11. The first pressure sensor 11 is disposed in the low-pressure natural gas buffer tank 3. The first pressure sensor 11 is used to detect the pressure in the low-pressure natural gas buffer tank 3.

[0040] Optionally, the LNG tank 5 is provided with an LNG tank gas outlet, and the LNG tank gas outlet is communicated with the second inlet of the oil-gas separator 2 through a second pipeline 16. The device for recovering natural gas in the gas supply system further includes a third valve 14. The third valve 14 is disposed in the second pipeline 16. After the LNG tank 5 is placed for a long time, the pressure in the tank will increase. When the pressure in the LNG tank 5 reaches the second set pressure, the third valve 14 opens, and the natural gas in the LNG tank 5 will enter the oil-gas separator 2 for pressure reduction.

[0041] Optionally, the device for recovering natural gas in the gas supply system further includes a second pressure sensor. The second pressure sensor is disposed in the LNG tank 5. The second pressure sensor is used to detect the pressure in the LNG tank 5.

[0042] Optionally, the device for recovering natural gas in the gas supply system further includes a fuel storage tank 12. The fuel storage tank 12 is communicated with the fuel outlet of the oil-gas separator 2. The fuel separated by the oil-gas separator 2 will be collected in the fuel storage tank 12.

[0043] Optionally, check valves are provided in the pipelines between the vaporizer 7 and the nozzle 41, between the diffuser chamber 44 and the high-pressure natural gas buffer tank 8, between the high-pressure natural gas buffer tank 8 and the gas pressure regulating module 1, between the gas pressure regulating module 1 and the oil-gas separator 2, and between the oil-gas separator 2 and the low-pressure natural gas buffer tank 3. The check valves can prevent the reverse flow of natural gas in the pipelines. The present invention also provides a vehicle, which includes the device for recovering natural gas in the above-mentioned gas supply system.

[0044] The present invention further provides a control method for the device for recovering natural gas in the gas supply system. Using the device for recovering natural gas in the above-mentioned gas supply system, the control method for the device for recovering natural gas in the gas supply system includes:

[0045] Judge whether the pressure of the low-pressure natural gas buffer tank 3 is greater than or equal to the first set pressure; if not, close the first valve 9; if so, open the first valve 9.

[0046] Judge whether the nozzle 41 outputs high-pressure natural gas; if so, open the second valve 10; if not, keep the second valve 10 closed.

[0047] When the pressure of the low-pressure natural gas buffer tank 3 is less than the first set pressure, the ejector 4 works normally. After the engine starts, the LNG pump 6 works, and the nozzle 41 sprays high-pressure natural gas, which enters the high-pressure natural gas buffer tank 8 through the mixing chamber 43 and the diffuser chamber 44. At this time, the first valve 9 is closed and the second valve 10 is closed, which can prevent the high-pressure natural gas in the mixing chamber 43 from entering the receiving chamber 42 and the low-pressure natural gas buffer tank 3, and can also avoid the destruction of the pressure balance in the pipeline caused by the normal operation of the ejector 4.

[0048] When the pressure of the low-pressure natural gas buffer tank 3 is greater than or equal to the first set pressure, the first valve 9 is opened, and the low-pressure natural gas in the low-pressure natural gas buffer tank 3 enters the receiving chamber 42, waiting for the opening of the second valve 10. When the pressure of the low-pressure natural gas buffer tank 3 is greater than or equal to the first set pressure and the nozzle 41 outputs high-pressure natural gas, the second valve 10 is opened, and the low-pressure natural gas is mixed with the high-pressure natural gas in the mixing chamber 43 and flows together with the high-pressure natural gas.

[0049] Optionally, the control method for the device for recovering natural gas in the gas supply system further includes: judging whether the pressure in the LNG tank 5 is greater than or equal to the second set pressure; if so, open the third valve 14; if not, close the third valve 14. When the pressure in the LNG tank 5 is greater than or equal to the second set pressure, the third valve 14 is opened, and the natural gas in the LNG tank 5 enters the oil-gas separator 2 to reduce the pressure of the LNG tank 5.

[0050] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A device for recovering natural gas in a gas supply system, characterized in that, Comprising: A gas pressure regulating module (1); An oil-gas separator (2), a first gas inlet of the oil-gas separator (2) being communicated with a natural gas bleed port of the gas pressure regulating module (1); A low-pressure natural gas buffer tank (3), an inlet of the low-pressure natural gas buffer tank (3) being communicated with an outlet of the oil-gas separator (2); An ejector (4), the ejector (4) comprising a nozzle (41) and a receiving chamber (42), a mixing chamber (43) and a diffuser chamber (44) that are sequentially communicated, the nozzle (41) being disposed through the receiving chamber (42), the nozzle (41) being communicated with an inlet of the mixing chamber (43), and an outlet of the low-pressure natural gas buffer tank (3) being communicated with the receiving chamber (42) through a first pipeline (15); A high-pressure natural gas buffer tank (8), the diffuser chamber (44) being communicated with an inlet of the high-pressure natural gas buffer tank (8), and an outlet of the high-pressure natural gas buffer tank (8) being communicated with a natural gas inlet of the gas pressure regulating module (1); An LNG tank (5), an LNG pump (6) and a vaporizer (7), an inlet and an outlet of the LNG pump (6) being respectively communicated with the LNG tank (5) and the vaporizer (7), and the vaporizer (7) being communicated with the nozzle (41); A first valve (9), the first valve (9) being disposed on the first pipeline (15); A second valve (10), the second valve (10) being disposed in the ejector (4), when the second valve (10) is closed, the receiving chamber (42) is disconnected from the mixing chamber (43); when the second valve (10) is opened, the receiving chamber (42) is communicated with the mixing chamber (43); Judge whether the pressure of the low-pressure natural gas buffer tank (3) is greater than or equal to a first set pressure; if not, close the first valve (9); if so, open the first valve (9); Judge whether the nozzle (41) outputs high-pressure natural gas; if so, open the second valve (10); if not, keep the second valve (10) closed.

2. The device for recovering natural gas in the gas supply system according to claim 1, wherein, The second valve (10) comprises a first barrier member, a second barrier member, an elastic member and an electric drive member, one end of the first barrier member is fixedly disposed at a junction of the receiving chamber (42) and the mixing chamber (43), the second barrier member is rotatably disposed at the other end of the first barrier member, two ends of the elastic member are respectively fixedly connected with the first barrier member and the second barrier member, the electric drive member is in transmission connection with the second barrier member, and the second barrier member can abut against or separate from an outer shell of the nozzle (41).

3. The device for recovering natural gas in the gas supply system according to claim 1, wherein The device for recovering natural gas in the gas supply system further comprises a first pressure sensor (11), the first pressure sensor (11) being disposed on the low-pressure natural gas buffer tank (3).

4. The device for recovering natural gas in the gas supply system according to claim 1, characterized in that, The LNG tank (5) is provided with an LNG tank gas vent, and the LNG tank gas vent is communicated with a second air inlet of the oil-gas separator (2) through a second pipeline (16). The device for recovering natural gas in the gas supply system further includes a third valve (14), and the third valve (14) is arranged on the second pipeline (16).

5. The device for recovering natural gas in the gas supply system according to claim 1, characterized in that The device for recovering natural gas in the gas supply system further includes a second pressure sensor, and the second pressure sensor is arranged on the LNG tank (5).

6. The device for recovering natural gas in the gas supply system according to claim 1, characterized in that, The device for recovering natural gas in the gas supply system further includes a fuel storage tank (12), and the fuel storage tank (12) is communicated with a fuel outlet of the oil-gas separator (2).

7. The device for recovering natural gas in the gas supply system according to claim 1, characterized in that, Check valves are provided in the pipeline between the vaporizer (7) and the nozzle (41), the pipeline between the diffuser chamber (44) and the high-pressure natural gas buffer tank (8), the pipeline between the high-pressure natural gas buffer tank (8) and the gas pressure regulating module (1), the pipeline between the gas pressure regulating module (1) and the oil-gas separator (2), and the pipeline between the oil-gas separator (2) and the low-pressure natural gas buffer tank (3).

8. A vehicle, characterized in that, Comprises the device for recovering natural gas in the gas supply system according to any one of claims 1-7.

9. Control method for a device for recovering natural gas in a gas supply system, characterized in that, Using the device for recovering natural gas in the gas supply system according to any one of claims 1-7, comprising: Judging whether the pressure of the low-pressure natural gas buffer tank (3) is greater than or equal to a first set pressure; If not, close the first valve (9); If so, open the first valve (9).

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