A method and system for phase change cooling control of wind turbine gearboxes

Abstract

This invention relates to the field of gearbox technology, specifically to a phase change cooling control method and system for wind turbine gearboxes. The method includes starting a motor gear pump to deliver high-temperature oil from the gearbox to an oil tank, acquiring real-time oil temperature T2, condenser inlet temperature T3, gearbox inlet pressure, and refrigerant circuit pressure, and determining whether the oil temperature T2 is lower than or equal to a first temperature threshold. If so, the variable frequency fan is turned off; otherwise, the variable frequency fan is started at a preset minimum speed. The real-time temperature difference between the oil temperature T2 and the inlet temperature T3 is calculated, and a variable frequency fan speed adjustment strategy is determined based on this real-time temperature difference. This invention utilizes latent heat exchange, resulting in high heat exchange efficiency and strong heat exchange capacity, thus solving the problem of insufficient capacity limits in current oil-water heat exchange systems.

Description

Technical Field

[0001] This invention relates to the field of gearbox technology, and specifically to a phase change cooling control method and system for wind turbine gearboxes. Background Technology

[0002] With the continuous advancement of wind power technology and the gradual occupancy of high-wind-speed resource areas, the trend towards larger wind turbine units is becoming increasingly apparent. This is accompanied by the increasing size of core components and a significant increase in heat dissipation requirements.

[0003] Currently in the wind power industry, most large-scale wind turbines commonly use doubly-fed or semi-direct-drive technologies. In both cases, a gearbox is required in the transmission chain to increase the speed of the main shaft driven by the front impeller before driving the generator at the rear to generate electricity.

[0004] Existing wind turbine gearboxes generally use air cooling or water cooling methods for their traditional cooling systems. Air cooling systems rely on fixed-speed variable frequency fans, which waste energy when operating continuously at low temperatures or small temperature differences. Water cooling systems are prone to scaling and clogging and require additional antifreeze measures. Furthermore, existing technologies have not established a coordinated mechanism between oil temperature and ambient temperature difference, resulting in defects such as high energy consumption, slow response, and poor adaptability to extreme operating conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a phase change cooling control method and system for wind turbine gearboxes to solve the problems of high energy consumption and slow response mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a phase change cooling control method for a wind turbine gearbox, comprising:

[0008] Start the motor gear pump to deliver the high-temperature oil from the gearbox to the oil tank;

[0009] Real-time acquisition of oil temperature T2 in the oil tank, condenser inlet air temperature T3, gearbox inlet pressure, and refrigerant circuit pressure;

[0010] Determine whether the oil temperature T2 is higher than the second temperature threshold. If yes, increase the speed of the variable frequency fan to full speed at the third rate. If no, determine whether the oil temperature T2 is lower than or equal to the first temperature threshold. If yes, the variable frequency fan is in the off state. If no, start the variable frequency fan to the preset minimum speed and calculate the real-time temperature difference between the oil tank temperature T2 and the air inlet temperature T3.

[0011] Determine whether the real-time temperature difference value is lower than the first temperature difference threshold. If so, increase the speed of the variable frequency fan at the first rate.

[0012] Determine whether the real-time temperature difference value is higher than the second temperature difference threshold. If so, reduce the speed of the variable frequency fan at the second rate.

[0013] Determine whether the real-time temperature difference value is between the first temperature difference threshold and the second temperature difference threshold. If so, maintain the current speed of the variable frequency fan.

[0014] In some embodiments, when the gearbox inlet pressure is lower than a preset pressure and the oil temperature T2 is lower than or equal to a first temperature threshold, the heater is activated to heat the oil inside the tank.

[0015] In some embodiments, when the refrigerant circuit pressure exceeds the preset pressure and remains so for 3 minutes, a power reduction command for the unit is triggered.

[0016] Furthermore, if the refrigerant circuit pressure value still exceeds the preset pressure after the power is reduced and continues for 3 minutes, the system will be triggered to shut down.

[0017] In some embodiments, the first temperature threshold is 45-55°C.

[0018] In some embodiments, the second temperature threshold is 65-75°C.

[0019] In some embodiments, the first temperature difference threshold is 4-6°C.

[0020] In some embodiments, the second temperature difference threshold is 9-11°C.

[0021] In some embodiments, both the first rate and the second rate are adjusted by 10% of the rated rotational speed within five seconds.

[0022] In some embodiments, the third rate is a 3% adjustment per second of the rated rotational speed.

[0023] Secondly, the present invention also proposes a phase change heat transfer system for implementing any of the methods described above, comprising:

[0024] The motor gear pump has an input end connected to the oil outlet of the gearbox and an output end connected to the oil inlet of the oil tank via a pipeline. The oil tank is connected to an external condensing unit. The oil tank is equipped with an evaporator, a heater, and an automatic exhaust valve located on the top of 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 located at the air inlet of the condenser.

[0025] A safety valve is connected in parallel to the outlet pipeline of the motor gear pump, and it is connected to the gearbox and the motor gear pump respectively.

[0026] The filter assembly is located upstream of the oil tank inlet line, and its two ends are connected to differential pressure transmitters;

[0027] A one-way valve is located on the pipeline between the filter assembly and the oil tank;

[0028] Pressure sensors, installed in pipelines, are used to detect gearbox inlet pressure sensors and refrigerant circuit pressure sensors.

[0029] Furthermore, the beneficial effects of the present invention are as follows:

[0030] This invention eliminates the water-side two-stage heat exchange system and uses air directly as the cold source to exchange heat with the phase change medium. Compared with the two-stage heat exchange system, it can effectively reduce costs. At the same time, the heat dissipation part only requires a variable frequency fan motor. Compared with the two-stage heat exchange system, which also requires water pumps / compressors and other components, this solution consumes less self-powered electricity.

[0031] Meanwhile, this invention eliminates the need for a plate-type oil-water heat exchanger, avoiding the risk of oil mixing with the cooling medium due to its rupture. In this solution, even if the evaporator leaks, the internal refrigerant will not cause any pollution to the system: if the leak is outside the oil tank, it will directly dissipate into the outside air; if the leak is inside the oil tank, due to the low gas density, it will automatically rise to the top of the oil tank and then escape from the exhaust valve located at the top of the oil tank.

[0032] Furthermore, by employing latent heat exchange, this invention achieves high heat exchange efficiency and strong heat exchange capacity, thus solving the problem of insufficient capacity limits in current oil-water heat exchange systems. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of a heat exchange system in the prior art;

[0034] Figure 2 A schematic diagram of the overall logic of the wind turbine gearbox phase change cooling control method provided by the present invention;

[0035] Figure 3 This is a schematic diagram of the overall structure of the wind turbine gearbox phase change heat transfer system provided by the present invention.

[0036] In the diagram: 1-Motor gear pump, 2-Safety valve, 3-Filter assembly, 4-Differential pressure transmitter, 5-Check valve, 6-Oil 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-Gearbox. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the embodiments of the present invention, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships, for example, A and / or B can mean: A alone, A and B simultaneously, and B alone. In addition, in the description of the embodiments of the present invention, "multiple" means two or more. Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, features defined with "first" and "second" can explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, unless otherwise stated, "multiple" means two or more.

[0038] But before that, let's combine them. Figure 1 To explain the existing solutions, current wind turbine gearbox lubrication systems use a single-stage oil-air cooling system. This means the oil is pumped to an oil-air heat exchanger where air cools it, but this method has limited heat exchange capacity. With the increasing power of wind turbine units, single-stage oil-air heat exchange is gradually becoming obsolete. Current large wind turbine gearbox lubrication and cooling systems primarily use a two-stage oil-water heat exchange system, the principle of which is described in the appendix. Figure 1 .

[0039] Its main working mechanism is as follows: a gear pump drives the oil in the 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 cooled oil returns to the tank. After the cold water is heated, it is pumped by a water pump in the secondary water-cooling loop to the air-cooled radiator, where a variable frequency motor fan blows out cold air to carry away the heat. The water temperature drops and it returns to the plate heat exchanger, thus completing the cycle. In addition to the main components such as the water pump, air-cooled radiator, and variable frequency motor fan, the secondary water-cooling loop is also equipped with relevant monitoring devices: pressure sensors, temperature sensors, and an electric three-way valve for flow regulation. An expansion tank is also included to prevent system pressure changes caused by the thermal expansion and contraction of the liquid.

[0040] However, it also has the following disadvantages: 1. Complex structure and high energy consumption. 2. As wind power units become larger but cooling system space is limited, although water cooling is highly efficient, this cooling method is gradually approaching its heat dissipation capacity limit. 3. Poor economic efficiency. Compared to oil-air heat exchange, adding an extra stage of heat exchange system is too costly. 4. Using a plate heat exchanger as the hub of primary and secondary heat exchange, if 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 sump will suffer from poor lubrication, and in severe cases, it may cause gearbox problems such as "gear seizing" or "jamming". If the oil-side medium enters the water side, it may affect the heat exchange effect.

[0041] 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:

[0042] Start the motor gear pump 1 to deliver the high-temperature oil in the gearbox 15 to the oil tank 6;

[0043] Real-time acquisition of oil temperature T2 in oil tank 6, air inlet temperature T3 in condenser 10, inlet pressure of gearbox 15, and refrigerant circuit pressure;

[0044] Determine if the oil temperature T2 is higher than the second temperature threshold. If so, increase the speed of the variable frequency fan 11 to full speed at the third rate. If not, determine if 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 in the oil tank 6 and the air inlet temperature T3.

[0045] Determine whether the real-time temperature difference value is lower than the first temperature difference threshold. If so, increase the speed of the variable frequency fan 11 at the first rate.

[0046] Determine whether the real-time temperature difference value is higher than the second temperature difference threshold. If so, reduce the speed of the variable frequency fan 11 at the second rate.

[0047] Determine whether the real-time temperature difference value is between the first temperature difference threshold and the second temperature difference threshold. If so, maintain the current speed of the variable frequency fan 11.

[0048] In one possible implementation, when the inlet pressure of gearbox 15 is lower than a preset pressure and the oil temperature T2 is lower than or equal to a first temperature threshold, heater 8 is activated to heat the oil inside oil tank 6.

[0049] In one possible implementation, when the refrigerant circuit pressure exceeds the preset pressure and remains so for 3 minutes, a power reduction command for the unit is triggered.

[0050] Furthermore, if the refrigerant circuit pressure value still exceeds the preset pressure after the power is reduced and continues for 3 minutes, the system will be triggered to shut down.

[0051] In the above steps, when the cooling system receives the start command, the motor gear pump 1 starts running and transmits oil to the oil tank 6. The actual speed can be adjusted by monitoring the oil temperature of the temperature sensor 14.

[0052] When the oil flows into the oil tank 6, the heat of the oil is transferred to the refrigerant in the evaporator 9. After absorbing heat and vaporizing, part of the refrigerant enters the condenser 10. The heat exchange of the condenser 10 is mainly achieved by the variable frequency fan 11 blowing low-temperature outside air. After the refrigerant releases heat, it condenses and flows back to the evaporator 9. The speed of the variable frequency fan 11 is determined by the readings T2 and T3 of the temperature sensor 14. When the temperature T2 is lower than the start-up set value, i.e., 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 lowest speed. At this time, the real-time temperature difference between the oil temperature T2 in 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 its speed at the first rate. When the real-time temperature difference is higher than the second temperature difference threshold, the variable frequency fan 11 decreases its speed at the second rate. When the real-time temperature difference is between the first and second temperature difference thresholds, the variable frequency fan 11 maintains its current speed.

[0053] It is worth noting that in this embodiment, the speed and temperature difference judgment cycle of the variable frequency fan 11 can be adjusted according to actual requirements. In this example, one minute is used as a cycle, that is, the temperature difference is judged once every minute to determine whether the speed of the variable frequency fan 11 increases or decreases. At the same time, when the temperature T2 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 increases at the third rate until it reaches full speed.

[0054] The oil tank 6 is equipped with a heater 8. The heater 8 will start when the motor gear pump 1 is running, the oil temperature T2 is lower than or equal to the first temperature threshold, and the pressure sensor before the gearbox 15 is lower than the user's requirement. The heater 8 will heat the oil in the oil tank 6 to quickly preheat the heat exchange system and prevent the pressure at the inlet of the gearbox 15 from being too low. However, the above three triggering conditions must be met at the same time, otherwise the heater 8 will not start.

[0055] When the pressure monitoring value is higher than the set value and the duration exceeds 3 minutes, an overheat warning signal is sent to the main controller, suggesting reduced power operation. If the alarm still exists after reducing power and continues for more than 3 minutes, a shutdown alarm signal is issued to avoid damage to the overall equipment caused by overheating or overcooling.

[0056] This invention eliminates the water-side two-stage heat exchange system, using air directly as the cold source to exchange heat with the phase change medium. Compared to the two-stage heat exchange system, this effectively reduces costs. Furthermore, the heat dissipation component only requires a variable frequency fan motor (11), while the two-stage heat exchange system necessitates the use of pumps / compressors and other components, resulting in lower self-consumption of electricity.

[0057] In one possible implementation, the first temperature threshold is 45-55°C, and 55°C is preferred in this invention.

[0058] In one possible implementation, the second temperature threshold is 65-75°C, and 70°C is preferred in this invention.

[0059] In one possible implementation, the first temperature difference threshold is 4-6°C, and 5°C is preferred in this invention.

[0060] In one possible implementation, the second temperature difference threshold is 9-11°C, and 10°C is preferred in this invention.

[0061] In one possible implementation, both the first and second rates adjust the rated speed by 10% within five seconds.

[0062] In one possible implementation, the third rate is 3% of the rated speed per second.

[0063] The method of this invention is described below with reference to specific steps:

[0064] Upon receiving the start command, the motor gear pump 1 immediately starts running, delivering the high-temperature oil in the gearbox 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 unobstructed oil flow.

[0065] At the same time, the oil temperature T2 in oil tank 6 and the air inlet temperature T3 in condenser 10 are monitored in real time.

[0066] When T2 ≤ 55℃, the inverter fan 11 remains off;

[0067] When T2 > 55℃, the variable frequency fan 11 starts at the lowest speed, such as 800rpm, and the real-time temperature difference ΔT = T2 - T3 is calculated.

[0068] If ΔT < 5℃, the speed of variable frequency fan 11 will increase by 10% of the rated speed within 5 seconds;

[0069] If ΔT is in the range of 5℃-10℃, maintain the current speed of variable frequency fan 11;

[0070] If ΔT > 10℃ maximum setting value, the speed of variable frequency fan 11 will decrease by 10% of the rated speed within 5 seconds;

[0071] The above temperature difference determination is performed once every minute.

[0072] When T2 > 70℃, 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.

[0073] Please refer to Figure 3 Secondly, the present invention also proposes a phase change heat transfer system for implementing any of the above methods, comprising:

[0074] The motor gear pump 1 has an input end connected to the oil outlet of the gearbox 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 equipped with an evaporator 9, a heater 8, and an automatic exhaust valve 12 located on 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 located at the air inlet of the condenser 10.

[0075] Safety valve 2 is connected in parallel to the outlet pipeline of motor gear pump 1, and is connected to gearbox 15 and motor gear pump 1 respectively;

[0076] The filter assembly 3 is located upstream of the oil inlet pipeline of the oil tank 6, and its two ends are connected to differential pressure transmitters 4.

[0077] One-way valve 5 is located on the pipeline between filter assembly 3 and oil tank 6;

[0078] Pressure sensor 13 is installed in the pipeline and is used to detect the pressure at the inlet of gearbox 15 and the pressure in the refrigerant circuit.

[0079] 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 oil sump of the gearbox 15 via the safety valve 2, while most of the oil enters the oil inlet of the oil tank 6 via the filter assembly 3, differential pressure transmitter 4, and check valve 5. The oil tank 6 is mainly used to store the oil and ensure sufficient heat exchange. The oil temperature in the oil tank 6 is monitored in real time by the temperature sensor 14. Based on the oil temperature, the control logic controls the start and stop of devices such as the variable frequency fan and heater 8 to achieve heat exchange. The oil tank 6 is equipped with a heater 8, which appropriately heats 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 can be opened to release pressure and prevent damage to the oil tank 6. The oil tank 6 is equipped with an automatic exhaust valve 12, which allows the gas in the oil tank 6 to be discharged into the air in a timely manner, and at the same time allows the evaporator 9 to be fully immersed in the oil to improve the heat exchange efficiency. In addition, if the evaporator 9 leaks, the refrigerant inside can also escape from here after vaporization, avoiding mixing with the oil and affecting its performance.

[0080] When the oil temperature reaches the set value, the evaporator 9 starts working. The refrigerant inside absorbs heat and vaporizes from liquid to gas, rising along the pipeline to the condenser 10. A variable frequency fan 11 is installed outside the condenser 10. As the oil temperature rises, the variable frequency fan 11 gradually starts and increases in speed until it reaches the maximum speed, blowing low-temperature outside air to the condenser 10. The high-temperature gaseous refrigerant inside the condenser 10 releases heat and changes from gas to liquid, flowing back to the evaporator 9 under gravity to absorb heat again and start the next cycle.

[0081] The evaporator 9 and the condenser 10 are connected by a pipeline, and a pressure sensor 13 is installed on the loop to monitor the internal refrigerant pressure in real time.

[0082] It is worth noting that the oil tank 6 adopts a layered design. The bottom layer is equipped with a heater 8 for heating the oil under low temperature conditions. The middle layer is a submerged evaporator 9, which is filled with refrigerant and achieves a phase change from liquid to gas by absorbing heat from the oil. The top layer is equipped with an automatic exhaust valve 12 for discharging gas and leaked refrigerant vapor from the oil tank 6.

[0083] In addition, it should be noted that different refrigerants can be selected depending on the operating conditions, such as R134a, but the present invention does not make a specific limitation on this.

[0084] This invention eliminates the need for a plate-type oil-water heat exchanger, thus avoiding the risk of oil mixing with the cooling medium due to its rupture. In this solution, even if the evaporator 9 leaks, the internal refrigerant will not cause any pollution to the system: if the leak is outside the oil tank 6, it will directly escape into the outside air; if the leak is inside the oil tank 6, due to the low gas density, it will automatically rise to the top of the oil tank 6 and then escape from the exhaust valve located at the top of the oil tank 6.

[0085] Furthermore, by employing latent heat exchange, this invention achieves high heat exchange efficiency and strong heat exchange capacity, thus solving the problem of insufficient capacity limit of current oil-water heat exchange systems.

[0086] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for controlling phase change cooling in a wind turbine gearbox, characterized in that, include: Start the motor gear pump to deliver the high-temperature oil from the gearbox to the oil tank; Real-time acquisition of oil temperature T2 in the oil tank, condenser inlet air temperature T3, gearbox inlet pressure, and refrigerant circuit pressure; Determine whether the oil temperature T2 is higher than the second temperature threshold. If yes, increase the speed of the variable frequency fan to full speed at the third rate. If no, determine whether the oil temperature T2 is lower than or equal to the first temperature threshold. If yes, the variable frequency fan is in the off state. If no, start the variable frequency fan to the preset minimum speed and calculate the real-time temperature difference between the oil tank temperature T2 and the air inlet temperature T3, wherein the first temperature threshold is less than the second temperature threshold. Determine whether the real-time temperature difference value is lower than the first temperature difference threshold. If so, increase the speed of the variable frequency fan at the first rate. Determine whether the real-time temperature difference value is higher than the second temperature difference threshold. If so, reduce the speed of the variable frequency fan at the second rate. Determine whether the real-time temperature difference value is between the first temperature difference threshold and the second temperature difference threshold. If so, maintain the current speed of the variable frequency fan, wherein the first temperature difference threshold is less than the second temperature difference threshold. When the gearbox inlet pressure is lower than the preset pressure and the oil temperature T2 is lower than or equal to the first temperature threshold, the heater is activated to heat the oil inside the tank. If the refrigerant circuit pressure exceeds the preset pressure for 3 minutes, the unit will be triggered to reduce power. If the refrigerant circuit pressure still exceeds the preset pressure for 3 minutes after the power reduction, the system will be triggered to shut down.

2. The wind turbine gearbox phase change cooling control method as described in claim 1, characterized in that, The first temperature threshold is 45-55℃.

3. The wind turbine gearbox phase change cooling control method as described in claim 1, characterized in that, The second temperature threshold is 65-75℃.

4. The wind turbine gearbox phase change cooling control method as described in claim 1, characterized in that, The first temperature difference threshold is 4-6℃.

5. The wind turbine gearbox phase change cooling control method as described in claim 1, characterized in that, The second temperature difference threshold is 9-11℃.

6. The wind turbine gearbox phase change cooling control method as described in claim 1, characterized in that, Both the first rate and the second rate are adjusted by 10% of the rated speed within five seconds.

7. The wind turbine gearbox phase change cooling control method as described in claim 1, characterized in that, The third rate is a 3% adjustment per second to the rated speed.

8. A phase change heat transfer system for implementing the method according to any one of claims 1-7, characterized in that, include: The motor gear pump has an input end connected to the oil outlet of the gearbox and an output end connected to the oil inlet of the oil tank via a pipeline. The oil tank is connected to an external condensing unit. The oil tank is equipped with an evaporator, a heater, and an automatic exhaust valve located on the top of 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 located at the air inlet of the condenser. A safety valve is connected in parallel to the outlet pipeline of the motor gear pump, and it is connected to the gearbox and the motor gear pump respectively. The filter assembly is located upstream of the oil tank inlet line, and its two ends are connected to differential pressure transmitters; A one-way valve is located on the pipeline between the filter assembly and the oil tank; Pressure sensors, installed in pipelines, are used to detect gearbox inlet pressure sensors and refrigerant circuit pressure sensors.

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