A pneumatic system and control method for a closed oil tank

Abstract

This invention discloses a pneumatic system for a closed-loop oil tank, comprising a vacuum generator, a first reversing valve connected to an external air source, a second reversing valve connected to the oil tank, and a five-way reversing valve connected to the first reversing valve, the oil tank, and the second reversing valve simultaneously. It also includes a piping assembly comprising a main air source pipeline connected to the outlet of the first reversing valve, a first air source branch branch from the main air source pipeline, a main oil tank pipeline connected to the oil tank, a first oil tank branch branch and a second oil tank branch branch from the main oil tank pipeline, and an exhaust pipeline connecting the second reversing valve and the vacuum generator. This invention also discloses a pneumatic system control method for controlling the air pressure of a closed-loop oil tank. Using this invention, automatic inflation and deflation can be achieved, improving the degree of automation; moreover, vacuuming can be performed under both power and power-off conditions, improving the convenience and stability of maintenance.

Description

Technical Field

[0001] This invention relates to the field of closed-loop oil tank technology, and more particularly to a pneumatic system and control method for closed-loop oil tanks. Background Technology

[0002] In environments with severe dust pollution, many equipment systems utilize closed-loop pressure tank systems. These systems completely seal the tank, isolating the hydraulic fluid from the external atmosphere and preventing dust from entering and damaging hydraulic components. During operation, to prevent the hydraulic pump from drawing air into the system, the closed tank is pre-charged with air at a specific pressure. This pressure must be carefully controlled; too low a pressure will result in insufficient oil intake, while too high a pressure will affect the entire system's operation. Therefore, existing closed-loop pressure tank systems typically use pneumatic systems to control the air pressure. These systems generally only include an inflation system with multiple ball valves connected in parallel. A check valve controls the airflow direction, thus inflating the tank. When deflation is required, a vent valve on the tank is opened. Although this system is easy to install, it is difficult to achieve automated management of inflation and deflation because the inflation system and deflation valve are not integrated into the same control system, resulting in a low degree of automation. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a pneumatic system for a closed oil tank that can automatically realize inflation and deflation, thereby improving the degree of automation; moreover, it can perform vacuuming both when the system is powered on and when it is powered off, thereby improving the convenience and stability of maintenance.

[0004] To solve the above-mentioned technical problems, the present invention provides a pneumatic system for a closed oil tank, including a vacuum generator, a first reversing valve connected to an external air source, a second reversing valve connected to the oil tank, and a five-way reversing valve connected to the first reversing valve, the oil tank, and the second reversing valve.

[0005] It also includes a piping assembly, which includes a main air supply pipeline connected to the outlet of the first reversing valve, a first air supply branch branch branching from the main air supply pipeline, a main oil tank pipeline connected to the oil tank, a first oil tank branch branch branching from the main oil tank pipeline and a second oil tank branch branching from the main oil tank pipeline, and an exhaust pipeline connected between the second reversing valve and the vacuum generator.

[0006] The first air source branch is connected to the five-way reversing valve, the first oil tank branch is connected to the five-way reversing valve, the first air source branch can be connected to the first oil tank branch through the five-way reversing valve, the second oil tank branch is connected to the second reversing valve, and the second oil tank branch can be connected to the exhaust pipe through the second reversing valve.

[0007] As an improvement to the above solution, the first gas source branch is connected to the first port of the five-way reversing valve, and the first oil tank branch is connected to the second port of the five-way reversing valve; the exhaust pipe is connected to the vacuum pumping end of the vacuum generator, and the vacuum pumping end is connected to the exhaust end of the vacuum generator.

[0008] When the first end of the five-way reversing valve is energized, the first port is connected to the second port.

[0009] When the second reversing valve is de-energized, the second oil tank branch is connected to the exhaust pipe; when the second reversing valve is energized, the second oil tank branch is disconnected from the exhaust pipe.

[0010] As an improvement to the above solution, the piping assembly further includes a vacuum piping, one end of which is connected to the third port of the five-way reversing valve, and the other end is connected to the vacuuming end of the vacuum generator.

[0011] When the second end of the five-way reversing valve is energized, the second port is connected to the third port.

[0012] As an improvement to the above solution, the pipeline assembly further includes a compressed air pipeline, one end of which is connected to the fourth port of the five-way reversing valve, and the other end is connected to the air inlet of the vacuum generator. The air inlet of the vacuum generator is connected to the air outlet of the vacuum generator. When the second end of the five-way reversing valve is energized, the first port is connected to the fourth port.

[0013] As an improvement to the above solution, a third reversing valve is also included. The pipeline assembly further includes a second air source branch and a third air source branch. The second air source branch is branched off from the main air source pipeline. The second air source branch is connected to the third air source branch through the third reversing valve. The third air source branch is connected to the compressed air pipeline.

[0014] As an improvement to the above solution, the first reversing valve and the third reversing valve are manual valves.

[0015] As an improvement to the above solution, a pressure sensor and a gas source processing module are also included. The pressure sensor is connected to the oil tank, and the gas source processing module is connected between the first reversing valve and the main gas source pipeline.

[0016] The present invention also provides a control method for controlling the pneumatic system for a closed oil tank as described above, comprising the following steps:

[0017] When the fuel tank pressure is detected to be lower than the target set value, the first end of the five-way reversing valve is energized, and the second reversing valve is also energized. At this time, the first port and the second port are connected, the second fuel tank branch is disconnected from the exhaust pipe, and the fuel tank main pipe is only connected to the first fuel tank branch. An external air source adds air to the fuel tank through the first reversing valve until the fuel tank pressure is detected to reach the target set range. Then, the five-way reversing valve is de-energized, and the first port and the second port are disconnected.

[0018] When the fuel tank pressure is detected to be higher than the target set value, the five-way reversing valve is de-energized, and the second reversing valve is also de-energized. At this time, the first port and the second port are disconnected, and the second fuel tank branch is connected to the exhaust pipe. The main fuel tank pipeline is only connected to the second fuel tank branch. The air in the fuel tank is discharged through the exhaust end of the vacuum generator until the fuel tank pressure is detected to reach the target set range. Then, the second reversing valve is energized, and the second fuel tank branch is disconnected from the exhaust pipe.

[0019] As an improvement to the above solution, the following steps are also included:

[0020] When the fuel tank system needs to be evacuated, the second end of the five-way reversing valve is energized, and the second reversing valve is also energized. At this time, the first port is connected to the fourth port, the second port is connected to the third port, and the second fuel tank branch is disconnected from the exhaust pipe. The main fuel tank pipe is only connected to the first fuel tank branch. An external gas source introduces gas into the vacuum generator through the first reversing valve to evacuate the fuel tank.

[0021] As an improvement to the above solution, the following steps are also included:

[0022] When the oil tank system needs to be evacuated while it is powered off, the first and fourth ports are disconnected, the second and third ports are disconnected, the second oil tank branch is connected to the exhaust pipe, and the oil tank is only connected to the second oil tank branch. An external gas source introduces gas into the vacuum generator through the first and third ports to evacuate the oil tank.

[0023] Implementing this invention has the following beneficial effects:

[0024] The pneumatic system for a closed-loop oil tank of the present invention includes a pipeline assembly, a vacuum generator, a first reversing valve, a second reversing valve, and a five-way reversing valve that simultaneously communicates with the first reversing valve, the oil tank, and the second reversing valve. The main air supply pipeline of the pipeline assembly is connected to the outlet of the first reversing valve, and a first air supply branch pipe branches off from the main air supply pipeline and connects to the five-way reversing valve. One end of the main oil tank pipeline of the pipeline assembly is connected to the oil tank, and the branched first oil tank branch pipe can connect to the oil tank via the five-way reversing valve. The first air source branch is connected, so an external air source can inflate the oil tank through the first air source branch, the five-way reversing valve, and the first oil tank branch. The second oil tank branch, branching off from the main oil tank pipeline, is connected to the exhaust pipeline through the second reversing valve. The exhaust pipeline is connected to the vacuum generator. Therefore, opening the second reversing valve allows the gas in the oil tank to be discharged from the vacuum generator through the main oil tank pipeline, the second oil tank branch, and the exhaust pipeline, thus achieving the venting operation. Therefore, the pneumatic system for closed oil tanks of this invention can automatically realize inflation and deflation, improving the degree of automation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the pneumatic system of the present invention for a closed oil tank in its initial state;

[0026] Figure 2 This is a schematic diagram of the pneumatic system of the present invention for a closed oil tank in an inflated state.

[0027] Figure 3 This is a schematic diagram of the pneumatic system of the present invention for a closed oil tank in the venting state;

[0028] Figure 4 This is a schematic diagram of the pneumatic system of the present invention for a closed oil tank in a vacuum state;

[0029] Figure 5 This is a schematic diagram of the pneumatic system of the present invention for a closed oil tank in a power-off and vacuum state;

[0030] Figure 6 This is a flowchart of the control method of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the directional terms such as up, down, left, right, front, back, inside, and outside used in this text are based solely on the accompanying drawings and are not intended to specifically limit the invention.

[0032] See Figure 1This invention discloses a pneumatic system for a closed oil tank, including a vacuum generator 8, a first reversing valve 1 connected to an external air source, a second reversing valve 2 connected to an oil tank 9, and a five-way reversing valve 3 connected to the first reversing valve 1, the oil tank 9, and the second reversing valve 2. The first reversing valve 1 and the second reversing valve 2 are both two-position three-way valves, capable of connecting or disconnecting different ports when energized or de-energized. The five-way reversing valve 3 is a three-position five-way valve; energizing or de-energizing electromagnets at different positions allows for the connection or disconnection of ports at different positions. The pneumatic system for the closed oil tank further includes a piping assembly 4, which includes a main air supply pipe 41 connected to the outlet of the first reversing valve 1, a first air supply branch pipe 411 branching from the main air supply pipe 41, an oil tank main pipe 42 connected to the oil tank 9, a first oil tank branch pipe 421 and a second oil tank branch pipe 422 branching from the oil tank main pipe 42, and an exhaust pipe 43 connecting the second reversing valve 2 and the vacuum generator 8. The main air supply pipe 41 receives air from the first reversing valve 1, the first air supply branch pipe 411 is one branch of the main air supply pipe 41, the oil tank main pipe 42 receives gas from the oil tank 9, and the first oil tank branch pipe 421 and the second oil tank branch pipe 422 are two branches of the oil tank main pipe 42. After the gas from the oil tank 9 enters different branches, it can achieve the effect of venting or vacuuming.

[0033] Specifically, the first air source branch 411 is connected to one port of the five-way reversing valve 3, and the first oil tank branch 421 is connected to one port of the five-way reversing valve 3. When the electromagnet at one end of the five-way reversing valve 3 is energized, the first air source branch 411 can connect to the first oil tank branch 421 through the five-way reversing valve 3. See [link / reference] Figure 2 When inflation is detected, air from an external air source enters the first air source branch 411 through the main air source pipeline 41, and then enters the main oil tank pipeline 42 through the five-way reversing valve 3 and the first oil tank branch 421, finally entering the oil tank 9 from the main oil tank pipeline 42 to achieve the inflation effect.

[0034] See Figure 3The second oil tank branch 422 is connected to the second reversing valve 2. After the second reversing valve 2 is de-energized, the second oil tank branch 422 can be connected to the exhaust pipe 43 through the second reversing valve 2. At this time, the exhaust pipe 43 is connected to the vacuum generator 8. The vacuum generator 8 is connected to the outside atmosphere. Therefore, when it is detected that gas needs to be released, the gas in the oil tank 9 will pass through the main oil tank pipe 42, the second oil tank branch 422, the second reversing valve 2 and the exhaust pipe 43 in sequence, and finally be discharged from the vacuum generator 8, thereby realizing automatic gas release.

[0035] The beneficial effects of the embodiments of the present invention are as follows:

[0036] The pneumatic system for a closed-loop oil tank in this embodiment of the invention includes a pipeline assembly 4, a vacuum generator 8, a first reversing valve 1, a second reversing valve 2, and a five-way reversing valve 3 that simultaneously connects to the first reversing valve 1, the oil tank 9, and the second reversing valve 2. The main air supply pipeline 41 of the pipeline assembly 4 is connected to the outlet of the first reversing valve 1. A first air supply branch 411 branches off from the main air supply pipeline 41 and connects to the five-way reversing valve 3. One end of the main oil tank pipeline 42 of the pipeline assembly 4 is connected to the oil tank 9. The branch 421 can connect to the first oil tank 9 via the five-way reversing valve 3. A gas source branch 411 is connected, allowing an external gas source to inflate the oil tank 9 via the first gas source branch 411, the five-way reversing valve 3, and the first oil tank branch 421. A second oil tank branch 422, branching off from the main oil tank pipeline 42, is connected to the exhaust pipeline 43 via the second reversing valve 2. The exhaust pipeline 43 is connected to the vacuum generator 8. Therefore, opening the second reversing valve 2 allows the gas inside the oil tank 9 to be discharged from the vacuum generator 8 through the main oil tank pipeline 42, the second oil tank branch 422, and the exhaust pipeline 43, thus achieving a venting operation. Therefore, the pneumatic system for closed oil tanks of this invention can automatically perform inflation and deflation, improving the degree of automation.

[0037] Specifically, when the second reversing valve 2 is de-energized, the second oil tank branch 422 is connected to the exhaust pipe 43; when the second reversing valve 2 is energized, the second oil tank branch 422 is disconnected from the exhaust pipe 43. The first air source branch 411 is connected to the first port 31 of the five-way reversing valve 3, and the first oil tank branch 421 is connected to the second port 32 of the five-way reversing valve 3. When the first end of the five-way reversing valve 3 is energized, the first port 31 is connected to the second port 32. In this way, the gas coming out of the main air source pipe 41 will enter the first air source branch 411, and then enter the first oil tank branch 421 through the five-way reversing valve 3, and then enter the main oil tank pipe 42 from the first oil tank branch 421. Since the main oil tank line 42 is connected to the second oil tank branch line 422, in order to prevent gas from being discharged from the second oil tank branch line 422 during inflation, the second reversing valve 2 needs to be energized during inflation, thereby disconnecting the second oil tank branch line 422 from the exhaust line 43. In this way, the gas can smoothly enter the oil tank 9 through the main oil tank line 42 to complete the inflation.

[0038] The exhaust pipe 43 is connected to the vacuum pumping end 81 of the vacuum generator 8, and the vacuum pumping end 81 is connected to the exhaust end 82 of the vacuum generator 8. The exhaust end 82 of the vacuum generator 8 is connected to the outside atmosphere. Therefore, when releasing gas, the five-way reversing valve 3 is de-energized. At this time, the first oil tank branch 421 cannot be connected to the first gas source branch 411. The oil tank 9 is only connected to the second oil tank branch 422 through the oil tank main pipe 42. Then, the second reversing valve 2 is de-energized, so that the second oil tank branch 422 is connected to the exhaust pipe 43. Finally, the gas is introduced into the vacuum pumping end 81 of the vacuum generator 8 and discharged to the outside atmosphere from the exhaust end 82 to achieve gas release.

[0039] When performing maintenance work on the hydraulic system, such as replacing valves and oil pipes, the air pressure in the closed oil tank 9 needs to be controlled at a negative pressure state to prevent hydraulic oil from leaking out.

[0040] See Figure 4In order to enable the vacuuming operation, the pipeline assembly 4 also includes a vacuuming pipeline 44, one end of which is connected to the third port 33 of the five-way reversing valve 3, and the other end is connected to the vacuuming end 81 of the vacuum generator 8. When the second end of the five-way reversing valve 3 is energized, the second port 32 is connected to the third port 33, and the first port 31 is connected to the fourth port 34. The pipeline assembly 4 also includes a compressed air pipeline 45. One end of the compressed air pipeline 45 is connected to the fourth port 34 of the five-way reversing valve 3, and the other end is connected to the air inlet 83 of the vacuum generator 8. In this way, air from an external air source will enter the compressed air pipeline 45 through the first air source branch 411 connected to the first port 31, and enter the air inlet 83 of the vacuum generator 8 from the compressed air pipeline 45. The air inlet 83 of the vacuum generator 8 is connected to the exhaust end 82 of the vacuum generator 8, and air will be discharged from the exhaust end 82. By controlling the second reversing valve 2 to be energized, the oil tank 9 is connected to the second oil tank branch 422, and is connected to the vacuum line 44 through the five-way reversing valve 3. The vacuum line 44 is connected to the vacuum end 81 of the vacuum generator 8. Since the air from the external air source will generate negative pressure when it enters the air inlet 83 of the vacuum generator 8 from the compressed air line 45, the negative pressure is transmitted to the oil tank 9 through the vacuum line, thus forming a vacuum effect.

[0041] See Figure 5 The pneumatic system for the closed oil tank can also perform vacuuming operations in the event of a power outage.

[0042] Specifically, the pneumatic system for the closed oil tank further includes a third reversing valve 5, and the pipeline assembly 4 further includes a second air source branch 412 and a third air source branch 413. The second air source branch 412 is branched off from the main air source pipeline 41. The second air source branch 412 is connected to the third air source branch 413 through the third reversing valve 5. The third air source branch 413 is connected to the compressed air pipeline 45. The compressed air pipeline 45 is branched off from the third air source branch 413. One branch of the third air source branch 413 is connected to the compressed air pipeline 45, and the other branch is connected to the fourth port 34. When a power outage is required for vacuuming, the second reversing valve 2 is de-energized. At this time, the main oil tank pipeline 42 is connected to the second oil tank branch pipeline 422, and is connected to the vacuuming end 81 of the vacuum generator 8 through the exhaust pipeline 43. The five-way reversing valve 3 is also de-energized. At this time, the second port 32 and the third port 33 are not connected, and the fourth port 34 is not connected to the first port 31. That is, the main air source pipeline 41 will be connected to the compressed air pipeline 45 through the second air source branch pipeline 412. In this way, the air introduced into the main air source pipeline 41 will generate negative pressure in the vacuum generator 8, thereby driving the exhaust pipeline 43 to draw in air to complete the vacuuming operation.

[0043] To facilitate control of the external air supply during power outages, the first reversing valve 1 and the third reversing valve 5 are manual valves. The pneumatic system for the closed-loop oil tank also includes a pressure sensor 6 and an air supply processing module 7. The pressure sensor 6 is connected to the oil tank 9, and the air supply processing module 7 is connected between the first reversing valve 1 and the main air supply pipeline 41. The pressure sensor 6 can detect the air pressure in the oil tank 9 in real time. When the air pressure is lower than a preset value, it restores the air pressure to normal through an inflation operation. When the air pressure is higher than the preset value, it restores the air pressure to normal through deflation.

[0044] See Figure 6 The present invention also discloses a control method for controlling the pneumatic system for a closed oil tank as described above, comprising the following steps:

[0045] S01: When the pressure in the fuel tank 9 is detected to be lower than the target set value, the first end of the five-way reversing valve 3 is energized, and the second reversing valve 2 is also energized. The five-way reversing valve 3 is de-energized only when the pressure in the fuel tank 9 is detected to reach the target set range.

[0046] The first air source branch 411 is connected to the first port 31 of the five-way reversing valve 3, and the first oil tank branch 421 is connected to the second port 32 of the five-way reversing valve 3. When the first end of the five-way reversing valve 3 is energized and the second reversing valve 2 is energized, the first port 31 and the second port 32 are connected, the second oil tank branch 422 is disconnected from the exhaust pipe 43, and the main oil tank pipe 42 is only connected to the first oil tank branch 421. An external air source can enter the first air source branch 411 through the first reversing valve 1, then enter the five-way reversing valve 3 from the first air source branch 411, then enter the first oil tank branch 421 from the five-way reversing valve 3, and finally enter the oil tank 9 from the main oil tank pipe 42. Therefore, an external air source can add air to the oil tank 9 through the first reversing valve 1. After inflation is completed, when the air pressure in the oil tank 9 returns to the target set range, the five-way reversing valve 3 is de-energized, the first port 31 and the second port 32 are disconnected, and the first air source branch 411 cannot be connected to the first oil tank branch 421, thereby shutting off inflation.

[0047] S02: When the pressure in the oil tank 9 is detected to be higher than the target set value, the five-way reversing valve 3 is de-energized, and the second reversing valve 2 is de-energized until the pressure in the oil tank 9 is detected to reach the target set range, at which point the second reversing valve 2 is energized.

[0048] One end of the compressed air pipeline 45 is connected to the fourth port 34 of the five-way reversing valve 3, and the other end is connected to the air inlet 83 of the vacuum generator 8. One end of the vacuum pumping pipeline 44 is connected to the third port 33 of the five-way reversing valve 3, and the other end is connected to the vacuum pumping end 81 of the vacuum generator 8. When the five-way reversing valve 3 is de-energized, the first port 31 is disconnected from the second port 32, and the first oil tank branch 421 is not connected to the first air source branch 411. In this way, the main oil tank pipeline 42 is only connected to the second oil tank branch 422. Moreover, by de-energizing the second reversing valve 2, the second oil tank branch 422 can be connected to the exhaust pipe. In this way, the air in the oil tank 9 can be discharged from the exhaust end 82 of the vacuum generator 8 through the second oil tank branch 422 and the exhaust pipeline 43, thereby achieving venting. After the venting is complete, when the air pressure in the oil tank 9 is detected to reach the target set range, the second reversing valve 2 is energized, which disconnects the second oil tank branch 422 from the exhaust pipe 43, and the oil tank 9 stops venting.

[0049] Using the above method, inflation and deflation can be achieved automatically, thus improving the level of automation.

[0050] S03: When the oil tank system needs to be evacuated, the second end of the five-way reversing valve 3 is energized, and the second reversing valve 2 is energized.

[0051] When the second end of the five-way reversing valve 3 is energized and the second reversing valve 2 is energized, the first port 31 is connected to the fourth port 34, the second port 32 is connected to the third port 33, and the second oil tank branch 422 is disconnected from the exhaust pipe 43. The main oil tank pipe 42 is only connected to the first oil tank branch 421. At this time, the oil tank 9 is connected to the vacuum pipe 44 through the first oil tank branch 421, and the oil tank 9 can be connected to the vacuum end 81 of the vacuum generator 8. Step 1: An external air source introduces gas into the first air source branch 411 through the first reversing valve 1. The first air source branch 411 is connected to the fourth pipe 34 and the compressed air pipeline 45 through the first pipe port 31. In the vacuum generator 8, gas can flow from the air inlet 83 to the exhaust end 82 of the vacuum generator 8. At this time, a negative pressure is generated on the vacuum pumping end 81 of the vacuum generator 8. The oil tank 9 connected to the vacuum pumping end 81 of the vacuum generator 8 gradually generates a vacuum to evacuate the oil tank 9.

[0052] S04: When the oil tank system needs to be evacuated while it is powered off, the five-way reversing valve 3 is de-energized, the second reversing valve 2 is de-energized, and the third reversing valve 5 is de-energized.

[0053] At this time, the first port 31 and the fourth port 34 are disconnected, the second port 32 and the third port 33 are disconnected, the second oil tank branch 422 is connected to the exhaust pipe 43, and the oil tank 9 is only connected to the second oil tank branch 422. Therefore, the oil tank 9 is connected to the vacuuming end 81 of the vacuum generator 8. The external air source introduces gas into the second air source branch 412 through the first reversing valve 1, and then enters the third air source branch 413 through the third reversing valve 5. Since the first port 31 and the fourth port 34 are disconnected, the gas coming out of the third air source branch 413 enters the compressed air pipe 45, and then enters the air inlet 83 of the vacuum generator 8 from the compressed air pipe 45. The gas is discharged from the air inlet 83 to the exhaust end 82 to evacuate the oil tank 9.

[0054] Using the above method, inflation and deflation can be automatically achieved, improving the degree of automation; moreover, vacuuming can be performed both when the system is powered on and when it is powered off, improving the convenience and stability of maintenance.

[0055] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A pneumatic system for a closed oil tank, characterized in that, It includes a vacuum generator, a first reversing valve connected to an external air source, a second reversing valve connected to an oil tank, and a five-way reversing valve that is simultaneously connected to the first reversing valve, the oil tank, and the second reversing valve. It also includes a piping assembly, which includes a main air supply pipeline connected to the outlet of the first reversing valve, a first air supply branch branch branching from the main air supply pipeline, a main oil tank pipeline connected to the oil tank, a first oil tank branch branch branching from the main oil tank pipeline and a second oil tank branch branching from the main oil tank pipeline, and an exhaust pipeline connected between the second reversing valve and the vacuum generator. The first air source branch is connected to the five-way reversing valve, the first oil tank branch is connected to the five-way reversing valve, the first air source branch can be connected to the first oil tank branch through the five-way reversing valve, the second oil tank branch is connected to the second reversing valve, and the second oil tank branch can be connected to the exhaust pipe through the second reversing valve. The first gas source branch is connected to the first port of the five-way reversing valve, and the first oil tank branch is connected to the second port of the five-way reversing valve; the exhaust pipe is connected to the vacuum pumping end of the vacuum generator, and the vacuum pumping end is connected to the exhaust end of the vacuum generator; When the first end of the five-way reversing valve is energized, the first port is connected to the second port. When the second reversing valve is de-energized, the second oil tank branch is connected to the exhaust pipe; when the second reversing valve is energized, the second oil tank branch is disconnected from the exhaust pipe. The piping assembly also includes a vacuum piping, one end of which is connected to the third port of the five-way reversing valve, and the other end is connected to the vacuum pumping end of the vacuum generator. When the second end of the five-way reversing valve is energized, the second port is connected to the third port. The piping assembly also includes a compressed air piping, one end of which is connected to the fourth port of the five-way reversing valve, and the other end of which is connected to the air inlet of the vacuum generator. The air inlet of the vacuum generator is connected to the air outlet of the vacuum generator. When the second end of the five-way reversing valve is energized, the first port is connected to the fourth port. It also includes a third reversing valve. The pipeline assembly further includes a second air source branch and a third air source branch. The second air source branch is branched off from the main air source pipeline. The second air source branch is connected to the third air source branch through the third reversing valve. The third air source branch is connected to the compressed air pipeline.

2. The pneumatic system for a closed oil tank according to claim 1, characterized in that, The first reversing valve and the third reversing valve are manual valves.

3. The pneumatic system for a closed oil tank according to claim 1, characterized in that, It also includes a pressure sensor and a gas source processing module. The pressure sensor is connected to the oil tank, and the gas source processing module is connected between the first reversing valve and the main gas source pipeline.

4. A control method for controlling a pneumatic system for a closed oil tank as described in any one of claims 1-3, characterized in that, Includes the following steps: When the fuel tank pressure is detected to be lower than the target set value, the first end of the five-way reversing valve is energized, and the second reversing valve is also energized. At this time, the first port and the second port are connected, the second fuel tank branch is disconnected from the exhaust pipe, and the fuel tank main pipe is only connected to the first fuel tank branch. An external air source adds air to the fuel tank through the first reversing valve until the fuel tank pressure is detected to reach the target set range. Then, the five-way reversing valve is de-energized, and the first port and the second port are disconnected. When the fuel tank pressure is detected to be higher than the target set value, the five-way reversing valve is de-energized, and the second reversing valve is also de-energized. At this time, the first port and the second port are disconnected, and the second fuel tank branch is connected to the exhaust pipe. The main fuel tank pipe is only connected to the second fuel tank branch. The air in the fuel tank is discharged through the exhaust end of the vacuum generator until the fuel tank pressure is detected to reach the target set range. Then, the second reversing valve is energized, and the second fuel tank branch is disconnected from the exhaust pipe.

5. The control method according to claim 4, characterized in that, It also includes the following steps: When the oil tank system needs to be evacuated, the second end of the five-way reversing valve is energized, and the second reversing valve is also energized. At this time, the first port is connected to the fourth port, the second port is connected to the third port, and the second oil tank branch is disconnected from the exhaust pipe. The main oil tank pipe is only connected to the first oil tank branch. An external gas source introduces gas into the vacuum generator through the first reversing valve to evacuate the oil tank.

6. The control method according to claim 5, characterized in that, It also includes the following steps: When the oil tank system needs to be evacuated while it is powered off, the first and fourth ports are disconnected, the second port is disconnected, and the second oil tank branch is connected to the exhaust pipe. The oil tank is only connected to the second oil tank branch. An external gas source introduces gas into the vacuum generator through the first and third ports to evacuate the oil tank.

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