Phase change cooling control method and system for wind power gear box

Abstract

The invention relates to the technical field of gear boxes, in particular to a wind power gear box phase change cooling control method and system.The method comprises the steps that a motor gear pump is started, high-temperature oil in a gear box is conveyed to an oil tank, and the oil temperature T2 of the oil tank, the condenser air inlet temperature T3, the gear box inlet pressure value and the refrigerant loop pressure value are obtained in real time; whether the oil temperature T2 is lower than or equal to a first temperature threshold value or not is judged, if yes, the variable-frequency fan is in a closed state, if not, the variable-frequency fan is started to the preset minimum rotating speed, the real-time temperature difference value of the oil temperature T2 of the oil tank and the temperature T3 of the air inlet is calculated, and the rotating speed adjusting strategy of the variable-frequency fan is determined according to the real-time temperature difference value. The heat exchange capacity is high, and the problem that the upper limit of the capacity of an existing oil-water heat exchange system is insufficient is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of gear boxes, and in particular to a phase change cooling control method and system for a wind power gear box. Background Art

[0002] With the continuous advancement of wind power generation technology and the gradual occupation of high-wind speed resource areas, the trend of larger turbines is becoming increasingly obvious. This is accompanied by the enlargement of core components and a significant increase in heat dissipation requirements.

[0003] Currently in the wind power industry, the technologies commonly used by most large units are doubly fed or semi-direct drive. A gearbox is required in the transmission chain to increase the speed of the main shaft driven by the front impeller and then drive the generator at the rear end to generate electricity.

[0004] Existing traditional cooling systems for wind turbine gearboxes generally use air cooling or water cooling. The air cooling system relies on a fixed-speed variable-frequency fan, which wastes energy when continuously running under low-temperature or small temperature difference conditions. The water cooling system is prone to scaling and clogging and requires additional anti-freeze measures. Furthermore, the existing technology has not established an oil temperature-ambient temperature difference coordination mechanism, resulting in defects such as high energy consumption, delayed response, and poor adaptability to extreme working conditions. Summary of the Invention

[0005] The object of the present invention is to provide a phase change cooling control method and system for a wind turbine gearbox, so as to solve the problems of high energy consumption and delayed response mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a wind turbine gearbox phase change cooling control method, comprising: Start the motor gear pump to transport the high-temperature oil in the gear box to the oil tank; Obtain the oil tank temperature T2, condenser air inlet temperature T3, gearbox inlet pressure and refrigerant circuit pressure in real time; determining whether the oil temperature T2 is higher than a second temperature threshold; if so, increasing the speed of the variable frequency fan to full speed at a third rate; if not, determining whether the oil temperature T2 is lower than or equal to a first temperature threshold; if so, turning off the variable frequency fan; if not, starting the variable frequency fan to a preset minimum speed, and calculating a real-time temperature difference between the oil tank temperature T2 and the air inlet temperature T3; Determine whether the real-time temperature difference is lower than a first temperature difference threshold, and if so, increase the speed of the variable frequency fan at a first rate; determining whether the real-time temperature difference is higher than a second temperature difference threshold, and if so, reducing the speed of the variable frequency fan at a second rate; Determine whether the real-time temperature difference is between a first temperature difference threshold and a second temperature difference threshold; if so, maintain the current speed of the variable frequency fan.

[0007] In some embodiments, when the gearbox inlet pressure value is lower than a preset pressure and the oil temperature T2 is lower than or equal to a first temperature threshold, the heater is started to heat the oil in the oil tank.

[0008] In some embodiments, when the refrigerant circuit pressure exceeds a preset pressure and lasts for 3 minutes, a power reduction instruction for the unit is triggered; If the refrigerant circuit pressure value still exceeds the preset pressure after power reduction and lasts for 3 minutes, the system will be triggered to shut down.

[0009] In some embodiments, the first temperature threshold is 45-55°C.

[0010] In some embodiments, the second temperature threshold is 65-75°C.

[0011] In some embodiments, the first temperature difference threshold is 4-6°C.

[0012] In some embodiments, the second temperature difference threshold is 9-11°C.

[0013] In some embodiments, the first rate and the second rate are both adjusted to 10% of the rated speed within five seconds.

[0014] In some embodiments, the third rate is adjusted by 3% of the rated speed per second.

[0015] In a second aspect, the present invention further provides a phase change heat transfer system for implementing any of the above methods, comprising: A motor gear pump, the input end of which is connected to the oil outlet of the gear box, and the output end is connected to the oil inlet of the oil tank via a pipeline. The oil tank is connected to an external condensing unit. An evaporator, a heater, and an automatic exhaust valve located at the top of the oil tank are provided inside the oil tank. A safety bypass valve is also provided between the oil inlet pipe and the oil outlet pipe of the oil tank. The external condensing unit includes a condenser, a variable frequency fan, and a temperature sensor provided at the air inlet of the condenser. A safety valve is connected in parallel to the outlet pipeline of the motor gear pump and is connected to the gear box and the motor gear pump respectively; The filter assembly is arranged upstream of the oil inlet pipeline of the fuel tank, and has differential pressure transmitters connected to both ends of the filter assembly; One-way valve, installed on the pipeline between the filter assembly and the fuel tank; The pressure sensor is installed in the pipeline and is used to detect the gear box inlet pressure sensor and the refrigerant circuit pressure sensor.

[0016] Furthermore, the beneficial effects of the present invention are: The present invention eliminates the secondary heat exchange system on the water side and uses air directly as a cold source to exchange heat with the phase change medium. Compared with the secondary heat exchange system, it can effectively reduce costs. At the same time, the heat dissipation part only has a variable frequency fan motor. Compared with the secondary heat exchange system, which also requires the use of water pumps / compressors and other devices, this solution consumes less self-used electricity.

[0017] Furthermore, the present invention eliminates the need for a plate-type oil-water heat exchanger, thus avoiding the risk of oil and cooling medium mixing due to its rupture. Even if the evaporator leaks, the refrigerant inside will not contaminate the system. If the leak occurs outside the tank, it will dissipate directly into the outside air. If the leak occurs inside the tank, due to its low gas density, it will automatically rise to the top of the tank and escape through the exhaust valve located at the top of the tank.

[0018] In addition, the present invention adopts latent heat exchange, which has high heat exchange efficiency and strong heat exchange capacity, and solves the problem of insufficient upper limit of the capacity of the current oil-water heat exchange system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the heat exchange system in the prior art; Figure 2 This is an overall logic diagram of the phase change cooling control method for a wind turbine gearbox provided by the present invention; Figure 3 This is a schematic diagram of the overall structure of the wind turbine gearbox phase change heat conversion system provided by the present invention.

[0020] In the figure: 1-motor gear pump, 2-safety valve, 3-filter assembly, 4-differential pressure transmitter, 5-check valve, 6-fuel tank, 7-safety bypass valve, 8-heater, 9-evaporator, 10-condenser, 11-variable frequency fan, 12-automatic exhaust valve, 13-pressure sensor, 14-temperature sensor, 15-gear box. DETAILED DESCRIPTION

[0021] The following, in conjunction with the accompanying drawings, provides a clear and complete description of the technical solutions in the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments derived by persons of ordinary skill in the art without inventive effort are within the scope of protection of the present invention. In the description of the embodiments of the present invention, unless otherwise specified, " / " represents an "or" (or). For example, "A / B" can represent either A or B. "And / or" in the text is merely a description of an association between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, in the description of the embodiments of the present invention, "plurality" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed to imply or suggest relative importance or to implicitly specify the number of the technical features indicated. Therefore, features designated "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, unless otherwise specified, "plurality" means two or more.

[0022] But before that, let’s combine Figure 1 Let me explain the solution in the existing technology. The existing wind turbine gearbox lubrication system adopts oil-air primary cooling, that is, the oil is pumped to the oil-air heat exchanger, and the air cools the oil, but the heat exchange capacity is low. With the large-scale power of the unit, the oil-air primary heat exchange is gradually disappearing from the historical stage. The current large-scale wind turbine gearbox lubrication cooling system has mainly adopted the oil-water secondary heat exchange system. Its principle is shown in the attached principle. Figure 1 .

[0023] Its main working mechanism is that a gear pump drives the oil in the oil tank into the filter assembly and then into the plate heat exchanger. The cold water in the heat exchanger dissipates heat from the oil through heat conduction, and the oil returns to the oil tank after cooling. After the cold water heats up, it is pumped to the air-cooled radiator by the water pump in the secondary water-cooling circuit. The motor-variable frequency fan blows in cold air from the outside to remove the heat. After the water temperature drops, it returns to the plate heat exchanger again, and the cycle continues. In addition to the main components such as the water pump, air-cooled radiator, and motor-variable frequency fan in the secondary water-cooling circuit, the system is also equipped with relevant monitoring devices: pressure sensors, temperature sensors, and an electric three-way valve for flow control. To prevent system pressure changes caused by thermal expansion and contraction of the liquid, an expansion tank is also installed.

[0024] However, there are also the following disadvantages: 1. Complex structure and high energy consumption. 2. As wind power units in the industry become larger and larger but the space for cooling systems is limited, although water cooling is more efficient, this cooling method has gradually approached the upper limit of its heat dissipation capacity. 3. Poor economy. Compared with oil-air heat exchange, the cost of adding an additional stage of heat exchange system is too high. 4. Using a plate heat exchanger as the hub of the first and second stage heat exchange, once internal leakage occurs, the media on both the oil and water sides may mix. If the water side medium enters the oil side, the gearbox oil pool will cause the lubrication effect to deteriorate, and in severe cases, it will cause problems such as "gnawing teeth" and "stuck" of the gearbox. If the oil side medium enters the water side, it may affect the heat exchange effect.

[0025] like Figure 2 As shown, in a first aspect, the present invention provides a phase change cooling control method for a wind turbine gearbox, comprising: Start the motor gear pump 1 to deliver the high-temperature oil in the gear box 15 to the oil tank 6; Real-time acquisition of the oil temperature T2 of the oil tank 6, the air inlet temperature T3 of the condenser 10, the inlet pressure value of the gear box 15, and the refrigerant circuit pressure value; Determine whether the oil temperature T2 is higher than the second temperature threshold. If so, increase the speed of the variable frequency fan 11 to the full speed at a third rate. If not, determine whether the oil temperature T2 is lower than or equal to the first temperature threshold. If so, the variable frequency fan 11 is in the off state. If not, start the variable frequency fan 11 to the preset minimum speed and calculate the real-time temperature difference between the oil temperature T2 of the oil tank 6 and the air inlet temperature T3; Determine whether the real-time temperature difference is lower than a first temperature difference threshold, and if so, increase the speed of the variable frequency fan 11 at a first rate; Determine whether the real-time temperature difference is higher than a second temperature difference threshold, and if so, reduce the speed of the variable frequency fan 11 at a second rate; It is determined whether the real-time temperature difference value is between the first temperature difference threshold and the second temperature difference threshold. If so, the current speed of the variable frequency fan 11 is maintained.

[0026] In one possible implementation, when the inlet pressure of the gearbox 15 is lower than a preset pressure and the oil temperature T2 is lower than or equal to a first temperature threshold, the heater 8 is started to heat the oil in the oil tank 6 .

[0027] In one possible implementation, when the refrigerant circuit pressure exceeds a preset pressure and lasts for 3 minutes, a power reduction command for the unit is triggered; If the refrigerant circuit pressure value still exceeds the preset pressure after power reduction and lasts for 3 minutes, the system will be triggered to shut down.

[0028] In the above steps, when the cooling system receives the start-up command, the motor gear pump 1 starts to operate and transfers the oil to the oil tank 6. The actual speed can be adjusted by monitoring the oil temperature of the temperature sensor 14.

[0029] When the oil flows into the oil tank 6, the heat of the oil is transferred to the refrigerant in the evaporator 9. Part of the refrigerant absorbs heat and vaporizes and then enters the condenser 10. The heat exchange of the condenser 10 is mainly achieved by the variable frequency fan 11 blowing the low-temperature air from the outside. The refrigerant after releasing heat condenses and flows back to the evaporator 9. The speed of the variable frequency fan 11 is determined by the reading T2 of the temperature sensor 14 and the reading T3 of the temperature sensor 14. When the temperature T2 is lower than the starting set value, that is, the first temperature threshold, the variable frequency fan 11 does not start. When the temperature T2 is not lower than or equal to the first temperature threshold, the variable frequency fan 11 starts at the minimum speed. At this time, the real-time temperature difference between the oil temperature T2 of the oil tank 6 and the air inlet temperature T3 is calculated. When the real-time temperature difference is lower than the first temperature difference threshold, the variable frequency fan 11 increases the speed of the variable frequency fan 11 at a first rate. When the real-time temperature difference is higher than the second temperature difference threshold, the variable frequency fan 11 reduces the speed of the variable frequency fan 11 at a second rate. When the real-time temperature difference is between the first temperature difference threshold and the second temperature difference threshold, the variable frequency fan 11 maintains the current speed. It is worth noting that in this embodiment, the speed of the variable frequency fan 11 and the temperature difference judgment period can be adjusted according to actual requirements. In this example, the period is 1 minute, that is, the temperature difference is judged once per minute to determine whether the speed of the variable frequency fan 11 is increased or decreased. At the same time, when the T2 temperature is higher than the second temperature threshold, no matter how large the real-time temperature difference is, the speed of the variable frequency fan 11 is increased at the third rate until it reaches the full speed.

[0030] A heater 8 is provided in the oil tank 6. Only when the motor gear pump 1 is running and the oil temperature T2 is lower than or equal to the first temperature threshold, and the pressure sensor in front of the gear box 15 is lower than the user requirement, the heater 8 is started to heat the oil in the oil tank 6 to quickly preheat the heat exchange system and avoid the pressure at the inlet of the gear box 15 being too low. However, the above three trigger conditions must be met at the same time, otherwise the heater 8 will not start.

[0031] When the pressure monitoring value is higher than the set value and lasts for more than 3 minutes, an overheating warning signal will be sent to the main control, and it is recommended to reduce the power operation. If the alarm still exists after the power is reduced and lasts for more than 3 minutes, a shutdown alarm signal will be issued to avoid damage to the entire equipment due to overcooling or overheating.

[0032] This invention eliminates the secondary water-side heat exchange system and uses air directly as the cooling source to exchange heat with the phase-change medium. Compared to a two-stage heat exchange system, this significantly reduces costs. Furthermore, the heat dissipation component consists solely of a variable-frequency fan 11 motor, unlike a two-stage heat exchange system that also requires components such as a water pump and compressor. This solution also consumes less self-use electricity.

[0033] In one possible implementation, the first temperature threshold is 45-55°C, and 55°C is preferred in the present invention.

[0034] In one possible implementation, the second temperature threshold is 65-75°C, and 70°C is preferred in the present invention.

[0035] In one possible implementation, the first temperature difference threshold is 4-6°C, and 5°C is preferred in the present invention.

[0036] In one possible implementation, the second temperature difference threshold is 9-11°C, and 10°C is preferred in the present invention.

[0037] In one possible implementation, both the first rate and the second rate are adjusted to 10% of the rated speed within five seconds.

[0038] In one possible implementation, the third rate is to adjust the rated rotation speed by 3% per second.

[0039] The method of the present invention is described below with reference to specific steps: After receiving the start command, the motor gear pump 1 starts running immediately, and delivers the high-temperature oil in the gear box 15 to the oil tank 6. When the oil flows through the filter assembly 3, if the pressure difference between the two ends is too large, the safety bypass valve 7 automatically opens to ensure that the oil path is unobstructed.

[0040] At the same time, the oil temperature T2 of the oil tank 6 and the air inlet temperature T3 of the condenser 10 are monitored in real time; When T2 ≤ 55°C, the variable frequency fan 11 remains off; When T2 > 55°C, the variable frequency fan 11 is started at the lowest speed, such as 800 rpm, and the real-time temperature difference ΔT = T2 - T3 is calculated; If ΔT < 5°C, the speed of the variable frequency fan 11 is increased uniformly by 10% of the rated speed within 5 seconds; If ΔT is in the range of 5°C-10°C, maintain the current speed of the variable frequency fan 11; If ΔT > 10°C maximum setting value, the speed of the variable frequency fan 11 is uniformly reduced by 10% of the rated speed within 5 seconds; The above temperature difference determination is performed once every 1 minute.

[0041] When T2 > 70°C, regardless of the size of ΔT, the fan speed increases to the maximum speed at a rate of 3% of the rated speed per second.

[0042] Please refer to Figure 3 In a second aspect, the present invention further provides a phase change heat transfer system for implementing any of the above methods, comprising: The motor gear pump 1 has an input end connected to the oil outlet of the gear box 15, and an output end connected to the oil inlet of the oil tank 6 via a pipeline. The oil tank 6 is connected to an external condensing unit. The oil tank 6 is provided with an evaporator 9, a heater 8, and an automatic exhaust valve 12 located at the top of the oil tank 6. A safety bypass valve 7 is also provided between the oil inlet pipe and the oil outlet pipe of the oil tank 6. The external condensing unit includes a condenser 10, a variable frequency fan 11, and a temperature sensor 14 provided at the air inlet of the condenser 10; The safety valve 2 is connected in parallel to the outlet pipeline of the motor gear pump 1, and is connected to the gear box 15 and the motor gear pump 1 respectively; The filter assembly 3 is arranged upstream of the oil inlet pipeline of the oil tank 6, and the two ends of the filter assembly are connected to the pressure difference transmitter 4; A one-way valve 5 is provided on the pipeline between the filter assembly 3 and the oil tank 6; The pressure sensor 13 is provided in the pipeline and is used to detect the gear box 15 inlet pressure sensor 13 and the refrigerant circuit pressure sensor 13 .

[0043] In the above structure, the motor gear pump 1 draws high-temperature oil from the oil sump of the gearbox 15. A portion of the oil enters the gearbox 15 oil sump through the safety valve 2, while the majority of the oil enters the oil inlet of the oil tank 6 through the filter assembly 3, the pressure differential transmitter 4, and the check valve 5. The oil tank 6 is primarily used to store the oil and allow for sufficient heat exchange. The oil temperature in the oil tank 6 is monitored in real time by a temperature sensor 14. Based on the oil temperature, control logic activates and deactivates components such as the variable frequency blower and heater 8, thereby achieving heat exchange. The oil tank 6 is equipped with a heater 8 to appropriately heat the oil in the oil tank 6 when conditions are met. The oil tank 6 is also equipped with a safety bypass valve 7. When the pressure in the oil tank 6 is too high, the bypass valve opens to relieve pressure and prevent damage to the oil tank 6. The oil tank 6 is equipped with an automatic exhaust valve 12, so that the gas in the oil tank 6 can be discharged into the air in time, and the evaporator 9 can be fully immersed in the oil to improve the heat exchange efficiency. In addition, once the evaporator 9 leaks, the internal refrigerant can also escape from here after vaporization, avoiding mixing with the oil and affecting its performance.

[0044] When the oil temperature reaches the set value, the evaporator 9 works, and the internal refrigerant absorbs heat and vaporizes from liquid to gas, and rises along the pipeline to the condenser 10. A variable frequency fan 11 is configured outside the condenser 10. As the oil temperature rises, the variable frequency fan 11 gradually starts, and then the speed increases until it reaches the maximum speed, blowing the outside low-temperature air to the condenser 10. The high-temperature gaseous refrigerant in the condenser 10 releases heat and is converted from gas to liquid. It flows back to the evaporator 9 under the action of gravity, and absorbs heat again to start the next cycle.

[0045] The evaporator 9 and the condenser 10 are connected by a pipeline, and a pressure sensor 13 is provided on the circuit to monitor the pressure of the internal refrigerant in real time.

[0046] It is worth noting that the oil tank 6 adopts a layered design, in which a heater 8 is installed on the bottom layer for heating the oil under low temperature conditions, an immersed evaporator 9 is installed in the middle layer, which is filled with refrigerant and realizes the phase change from liquid to gas by absorbing the heat of the oil, and an automatic exhaust valve 12 is configured on the top layer for discharging the gas in the oil tank 6 and the leaked refrigerant vapor.

[0047] In addition, it should be noted that different refrigerants can be selected according to different working conditions, such as R134a, and the present invention does not make specific limitations on this.

[0048] The present invention eliminates the need for a plate-type oil-water heat exchanger, thus avoiding the risk of oil and cooling medium mixing due to its rupture. In this solution, even if the evaporator 9 leaks, the refrigerant inside will not contaminate the system. If the leak occurs outside the oil tank 6, it will escape directly into the outside air. If the leak occurs inside the oil tank 6, due to its low gas density, it will automatically rise to the top of the oil tank 6 and escape through the exhaust valve located at the top of the oil tank 6.

[0049] In addition, the present invention adopts latent heat exchange, which has high heat exchange efficiency and strong heat exchange capacity, and solves the problem of insufficient upper limit of the capacity of the current oil-water heat exchange system.

[0050] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A wind turbine gearbox phase change cooling control method, characterized in that: include: Start the motor gear pump to transport the high-temperature oil in the gear box to the oil tank; Obtain the oil tank temperature T2, condenser air inlet temperature T3, gearbox inlet pressure and refrigerant circuit pressure in real time; determining whether the oil temperature T2 is higher than a second temperature threshold; if so, increasing the speed of the variable frequency fan to full speed at a third rate; if not, determining whether the oil temperature T2 is lower than or equal to a first temperature threshold; if so, turning off the variable frequency fan; if not, starting the variable frequency fan to a preset minimum speed, and calculating a real-time temperature difference between the oil tank temperature T2 and the air inlet temperature T3; Determine whether the real-time temperature difference is lower than a first temperature difference threshold, and if so, increase the speed of the variable frequency fan at a first rate; determining whether the real-time temperature difference is higher than a second temperature difference threshold, and if so, reducing the speed of the variable frequency fan at a second rate; Determine whether the real-time temperature difference is between a first temperature difference threshold and a second temperature difference threshold; if so, maintain the current speed of the variable frequency fan.

2. The wind turbine gearbox phase change cooling control method according to claim 1, characterized in that: When the gearbox inlet pressure value is lower than the preset pressure and the oil temperature T2 is lower than or equal to the first temperature threshold, the heater is started to heat the oil in the oil tank.

3. The wind turbine gearbox phase change cooling control method according to claim 2, characterized in that: When the refrigerant circuit pressure exceeds the preset pressure and lasts for 3 minutes, the unit power reduction command is triggered; If the refrigerant circuit pressure value still exceeds the preset pressure after power reduction and lasts for 3 minutes, the system will be triggered to shut down.

4. The wind turbine gearbox phase change cooling control method according to claim 1, characterized in that: The first temperature threshold is 45-55°C.

5. The wind turbine gearbox phase change cooling control method according to claim 1, characterized in that: The second temperature threshold is 65-75°C.

6. The wind turbine gearbox phase change cooling control method according to claim 1, characterized in that: The first temperature difference threshold is 4-6°C.

7. The wind turbine gearbox phase change cooling control method according to claim 1, characterized in that: The second temperature difference threshold is 9-11°C.

8. The wind turbine gearbox phase change cooling control method according to claim 1, characterized in that: The first rate and the second rate are both adjusted to 10% of the rated speed within five seconds.

9. The wind turbine gearbox phase change cooling control method according to claim 1, characterized in that: The third speed is adjusted by 3% of the rated speed per second.

10. A phase change heat transfer system for implementing the method according to any one of claims 1 to 9, characterized in that: include: A motor gear pump, the input end of which is connected to the oil outlet of the gear box, and the output end is connected to the oil inlet of the oil tank via a pipeline. The oil tank is connected to an external condensing unit. An evaporator, a heater, and an automatic exhaust valve located at the top of the oil tank are provided inside the oil tank. A safety bypass valve is also provided between the oil inlet pipe and the oil outlet pipe of the oil tank. The external condensing unit includes a condenser, a variable frequency fan, and a temperature sensor provided at the air inlet of the condenser. A safety valve is connected in parallel to the outlet pipeline of the motor gear pump and is connected to the gear box and the motor gear pump respectively; The filter assembly is arranged upstream of the oil inlet pipeline of the fuel tank, and has differential pressure transmitters connected to both ends of the filter assembly; One-way valve, installed on the pipeline between the filter assembly and the fuel tank; The pressure sensor is installed in the pipeline and is used to detect the gear box inlet pressure sensor and the refrigerant circuit pressure sensor.

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