A wind turbine main shaft sliding bearing lubrication test system and method

Abstract

The application discloses a kind of wind generating set main shaft sliding bearing lubrication test system and method, it is related to wind generating set test technical field, including independent oil tank, and the oil outlet pipeline of independent oil tank is connected with overflow pipeline, oil supply manifold by check valve, and oil supply manifold is divided into first oil supply branch pipe, second oil supply branch pipe by temperature control valve, and first oil supply branch pipe, second oil supply branch pipe are converged to test pipeline, and test pipeline is divided into four branches and is respectively connected with the front radial bearing, rear radial bearing, front thrust bearing, rear thrust bearing of wind generating set main shaft sliding bearing, and test pipeline, overflow pipeline is converged into oil return manifold, and oil return manifold is connected with independent oil tank.The application simulates wide temperature range, wide flow range and dynamic damping change, realizes the multiple working condition coverage;While quantifying the pressure and flow distribution of each bearing branch, effectively solve the problem of bearing bush lubrication deficiency caused by uneven flow before leaving factory.

Description

Technical Field

[0001] This invention relates to the field of wind turbine generator testing technology, specifically disclosing a lubrication test system and method for the sliding bearing of the main shaft of a wind turbine generator. Background Technology

[0002] As the capacity of wind turbine units continues to increase, sliding bearings for the main shaft are expected to gradually replace traditional rolling bearings in the future due to their compact structure, high load-bearing capacity, modular design, and convenient tower maintenance. When sliding bearings are working, the lubricating oil not only reduces friction but also dissipates heat and forms a load-bearing oil film. Uneven flow distribution among the bearing bushes can easily lead to excessively high local bearing temperatures, bearing burnout, or even shaft seizure. Therefore, flow testing before shipment is a crucial step in ensuring bearing reliability. Traditional flow testing typically simulates a single stable operating condition (such as rated speed, normal temperature and pressure) to check the smoothness of the oil supply lines, determine if there are obvious blockages or leaks in each branch, and thus assess assembly quality and basic lubrication performance. This type of test is helpful in detecting manufacturing defects.

[0003] However, single-condition testing is insufficient to cover the complex environment of actual operation. First, the simulation of operating conditions is inadequate; during low-temperature cold starts (e.g., -40℃), the flow resistance of high-viscosity lubricating oil in the pipeline increases significantly, and the flow distribution deviation caused by pipeline geometric differences cannot be revealed by room-temperature testing. Second, dynamic damping simulation is lacking; the internal damping of the bearing changes dynamically with rotational speed and flow rate, thus affecting the flow distribution characteristics of each bearing bush, but existing test benches cannot construct closed-loop testing devices to reproduce this process. Finally, the data dimension is limited; current test benches only monitor the total inlet pressure or total flow rate, making it difficult to accurately quantify the dynamic relationship between pressure and flow rate in each bearing bush branch, and thus unable to scientifically assess the uniformity of flow distribution and the rationality of lubrication pipeline design. These shortcomings make it difficult for existing technology to meet the urgent need for multi-condition, high-precision flow distribution testing of large-capacity wind turbine sliding bearings. Summary of the Invention

[0004] To address the problem that existing test benches cannot simulate wide temperature ranges, wide flow ranges, and dynamic damping changes in wind turbine sliding bearing factory testing, making it difficult to effectively identify the risk of bearing failure caused by uneven flow distribution among bearings before delivery, this invention provides a lubrication test system and method for wind turbine main shaft sliding bearings.

[0005] To address the aforementioned problems, in a first aspect, the present invention provides the following technical solution: A lubrication test system for the sliding bearing of a wind turbine main shaft includes an independent oil tank. The oil outlet of the independent oil tank is connected to an overflow pipe and a main oil supply pipe via a one-way valve. The main oil supply pipe branches into a first oil supply branch pipe and a second oil supply branch pipe via a temperature control valve. The oil temperature of the first oil supply branch pipe is less than 45°C, and the oil temperature of the second oil supply branch pipe is greater than or equal to 45°C. The first and second oil supply branch pipes converge into a test pipe. The test pipe branches into four branches, which are respectively connected to the front radial bearing, rear radial bearing, front thrust bearing, and rear thrust bearing of the sliding bearing of the wind turbine main shaft. The test pipe and the overflow pipe converge into a return oil main pipe, which is connected to the independent oil tank.

[0006] Preferably, the independent oil tank is provided with an oil filling hole and a first oil drain ball valve at the top and bottom of the side, and multiple sets of heaters are installed inside the independent oil tank. The independent oil tank is equipped with a first temperature sensor, an air filter, a liquid level and temperature gauge, and a liquid level and temperature switch.

[0007] Preferably, the oil outlet pipeline is equipped with an electric pump for adjusting the oil outlet rate, the electric pump is equipped with a variable frequency motor, and the variable frequency motor is equipped with a frequency converter.

[0008] Preferably, the overflow pipeline is equipped with an overflow valve, and a first pressure testing connector is installed on the pipeline at the front end of the overflow valve. The main oil supply pipeline is connected to an oil drain pipeline, and a first pressure sensor, a second oil drain ball valve, and a second temperature sensor are installed on the oil drain pipeline.

[0009] Preferably, an auxiliary pipeline is provided between the overflow pipeline and the main oil supply pipeline, and a second pressure testing connector is installed on the auxiliary pipeline. The rated pressure of the overflow valve is 16 bar.

[0010] Preferably, the front end of the temperature control valve is provided with a filter mounted on the oil supply main pipe, the filter is connected in parallel with a safety valve, the safety valve is set with a pressure of 4.5 bar, and a differential pressure transmitter is externally connected to the oil supply main pipe.

[0011] Preferably, the filter is a two-stage filter element structure, with the two filter elements having filtration calibers of 10μm and 50μm respectively. The differential pressure transmitter is calibrated to transmit a differential pressure of 3.5 bar. The safety valve is connected in parallel with the 10μm filter element of the filter, and the safety valve is calibrated to a pressure of 4.5 bar.

[0012] Preferably, a third pressure testing connector and a fourth pressure testing connector are respectively installed on the first oil supply branch pipe and the second oil supply branch pipe, and an air cooler is installed on the rear end of the fourth pressure testing connector on the second oil supply branch pipe.

[0013] Preferably, each of the four branches of the test pipeline is equipped with a second pressure sensor, a third temperature sensor, a throttle valve, and a flow meter, and the second pressure sensor, the third temperature sensor, the throttle valve, and the flow meter are all mounted at the front end of the front radial bearing, the rear radial bearing, the front thrust bearing, and the rear thrust bearing.

[0014] On the other hand, the present invention also provides a method for testing the lubrication of sliding bearings on the main shaft of a wind turbine generator set, the method comprising: During lubrication tests of the front radial bearing, rear radial bearing, front thrust bearing, and rear thrust bearing of the main shaft sliding bearing of the wind turbine generator set, the independent oil tank supplies pressurized lubricating oil to the main oil supply pipe through the oil outlet pipe. When the pressure in the oil outlet pipe is greater than or equal to 16 bar, the overflow valve opens, and the pressurized lubricating oil returns to the independent oil tank sequentially through the overflow pipe and the return oil main pipe. When the pressure in the oil outlet pipe is less than 16 bar, the pressurized lubricating oil passes through the 10 μm filter element and the 50 μm filter element of the filter before reaching the temperature control valve. When the temperature of the pressurized lubricating oil in the main oil supply pipe is less than 45°C, the pressurized lubricating oil enters the test pipe through the first oil supply branch pipe. When the temperature of the pressurized lubricating oil in the main oil supply pipe is greater than or equal to 45°C, the pressurized lubricating oil enters the test pipe through the second oil supply branch pipe and is cooled by the air cooler. The pressurized lubricating oil in the test pipe returns to the independent oil tank through the return oil main pipe.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention achieves wide-range environmental reproduction through a collaborative structure of an independent oil tank, heater, temperature control valve, and air cooler. The independent oil tank is equipped with multiple heaters and a first temperature sensor, which can accurately heat the oil to low-temperature cold start or high-temperature rated operating conditions, covering the extreme environmental temperatures encountered in actual wind farm operation. A variable frequency motor and inverter drive an electric pump on the oil outlet pipeline, with the inverter steplessly adjusting the output flow rate, achieving continuous adjustment across a wide flow range from small to large flow rates to meet the oil supply needs under different operating conditions. A temperature control valve is installed at the rear end of the main oil supply pipe, automatically switching at a set threshold. Low-temperature oil flows directly to the test pipeline via the first oil supply branch pipe, while high-temperature oil switches to the second oil supply branch pipe and is cooled as needed or kept at a high temperature by the air cooler. This design structure overcomes the limitations of a single stable operating condition, realistically reproducing the flow resistance at low temperatures and high viscosity, as well as the distribution characteristics under high temperatures and large flow rates. This allows factory testing to effectively identify flow distribution deviations caused by changes in operating conditions, reducing the risk of bearing failure at the source.

[0016] 2. In this invention, the oil outlet pipeline is led out from an independent oil tank and sequentially connected to a check valve and an electric pump. The check valve employs an adjustable spring structure, allowing for flexible setting of different opening pressures by adjusting the spring preload. These pressures correspond to the back pressure damping caused by oil film thickness and wedge effect under low spindle speed, rated speed, and overspeed conditions. When pressurized lubricating oil flows through the check valve, a stable simulated pressure difference is formed across the valve core, and this pressure difference dynamically changes with the set value, thus constructing a closed-loop, damping-adjustable test environment. Compared to traditional test benches that only provide a constant flow path, this invention quantifies the influence of rotational speed on the dynamic characteristics of the oil film inside the bearing as a repeatably adjustable hydraulic resistance. This allows each bearing branch to fully expose flow resistance matching defects under variable damping conditions, effectively solving the test distortion problem caused by the lack of dynamic damping.

[0017] 3. This invention integrates pressure sensors, temperature sensors, throttle valves, and flow meters on the four branches of the test pipeline, and combines them with an asymmetric manifold structure to achieve multi-dimensional data acquisition and quantitative evaluation. The test pipeline branches into multiple parallel branches, corresponding to the front radial bearing, rear radial bearing, front thrust bearing, and rear thrust bearing, respectively. Each branch's bearing inlet is equipped with a pressure sensor, temperature sensor, and throttle valve, allowing independent monitoring of the inlet pressure and oil temperature of each branch. The flow distribution ratio can be flexibly changed by adjusting the throttle valve. During testing, the pressure values ​​of each branch are recorded and the average value is calculated. By comparing the deviation of each branch's pressure from the average value, the uniformity of flow distribution can be quantitatively determined. This structure upgrades the traditional single inlet total pressure monitoring to a multi-point, multi-dimensional, precise quantitative system, providing reliable data support for evaluating the rationality of lubrication pipeline design. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the oil circuit layout of the test system of the present invention; In the diagram: 1. Independent oil tank, 2. Oil outlet pipe, 3. Check valve, 4. Overflow pipe, 5. Main oil supply pipe, 6. Temperature control valve, 7. First oil supply branch pipe, 8. Second oil supply branch pipe, 9. Test pipe, 10. Front bearing, 11. Rear bearing, 12. Thrust bearing, 13. Main oil return pipe, 14. Oil filling hole, 15. First drain ball valve, 16. Multiple heaters, 17. First temperature sensor, 18. Air filter, 19. Liquid level and temperature gauge, 20. Liquid level and temperature switch, 21. Electric pump, 22. Variable frequency motor. 23. Frequency converter, 24. Overflow valve, 25. First pressure test connector, 26. Oil drain line, 27. First pressure sensor, 28. Second oil drain ball valve, 29. Second temperature sensor, 30. Auxiliary line, 31. Second pressure test connector, 32. Filter, 33. Safety valve, 34. Differential pressure transmitter, 35. Third pressure test connector, 36. Fourth pressure test connector, 37. Air cooler, 38. Second pressure sensor, 39. Third temperature sensor, 40. Throttling valve, 41. Rear thrust bearing, 42. Flow meter. Detailed Implementation

[0019] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] This specific embodiment provides a lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set, such as... Figure 1 As shown, this system is designed to simulate various temperature, flow rate, and dynamic damping conditions that the sliding bearings of the main shaft of a wind turbine may encounter in actual operation in a wind farm before they leave the factory, thereby accurately evaluating the uniformity of flow distribution in each bearing branch and the rationality of the lubrication system design.

[0021] The system includes an independent oil tank 1, which serves as the storage, heating, and return oil collection center for the lubricating oil. The independent oil tank 1 is the central hub for oil storage and thermal management of the entire system. The volume of the independent oil tank 1 should be no less than 3-5 times the total system flow rate. For example, when the maximum test flow rate is 120 L / min, the effective volume of the oil tank is recommended to be 400-600 L to facilitate heat dissipation and bubble removal.

[0022] At the top of the fuel tank, there is a fuel filling hole 14 equipped with a removable filter screen to prevent impurities from entering the system during the filling process. An air filter 18 is installed on the independent fuel tank 1. Its function is to balance the air pressure inside and outside the tank when the fuel level changes, and to filter dust particles in the air entering the tank. A filtration accuracy of 10μm is recommended.

[0023] To simulate the start-up temperature of a wind farm under different seasonal and geographical conditions, multiple sets of heaters 16 are installed inside the independent oil tank 1. Each set of heaters 16 can be an immersion flange electric heater, and its power can be calculated based on the oil tank volume and the required heating rate. For example, the total power is 6kW-15kW, with segmented control. The independent oil tank 1 is also equipped with a first temperature sensor 17, which is used to monitor the oil temperature in real time and feed it back to the control system to achieve precise heating start-up and shutdown and PID regulation.

[0024] A level and temperature gauge 19 is installed on the side of the independent oil tank 1, allowing on-site personnel to visually observe the oil level and approximate oil temperature. Simultaneously, to ensure automatic control and safety interlocking, a level and temperature switch 20 is also installed on the tank. This switch can output low-level and high-level alarm signals, and can also issue an alarm when the oil temperature exceeds the set upper limit to prevent oil overheating and deterioration. For convenient system maintenance and oil changes, a first drain ball valve 15 is located at the bottom side of the independent oil tank 1. This ball valve allows for easy connection of a hose to discharge waste oil into a designated container.

[0025] An oil pipeline 2 extends from the side of the independent oil tank 1, serving as the main output channel for lubricating oil. Several key components are connected sequentially to the oil pipeline 2; first is a one-way valve 3, which not only prevents backflow of oil but, more importantly, is used in this system to simulate the back pressure damping caused by changes in the thickness of the oil film inside the bearing under different speed conditions. The outlet of the one-way valve 3 is simultaneously connected to an overflow pipeline 4 and a main oil supply pipeline 5, forming the first branch point. The overflow pipeline 4 is used for overpressure protection and low-flow bypass, while the main oil supply pipeline 5 carries the main lubricating oil flow to subsequent processing modules.

[0026] The power for oil delivery in pipeline 2 is provided by an electric pump 21. The electric pump 21 is directly connected to a variable frequency motor 22, which is further driven by a frequency converter 23. By adjusting the motor speed through the frequency converter 23, the output flow rate of the electric pump 21 can be steplessly adjusted. For example, when simulating low-speed, light-load conditions, the output flow rate is set to 10 L / min; when simulating rated conditions, it is set to 60 L / min; and when simulating extreme flow requirements, it is set to 120 L / min. This wide flow range simulation capability is one of the key innovations of this invention.

[0027] Unlike conventional check valves, which are only used to prevent backflow, the check valve 3 on the oil outlet line 2 in this invention is equipped with the function of actively adjusting back pressure damping. Specifically, a straight-through check valve with an adjustable spring can be selected. By adjusting the spring preload, the valve opening pressure can be set, for example, 0.3 bar, 0.5 bar, 0.8 bar, etc. When lubricating oil flows through the check valve, a stable pressure difference is formed before and after the valve core. This pressure difference simulates the dynamic damping of the spindle sliding bearing at different speeds due to the oil film thickness and wedge effect. For example, under low-speed conditions, the oil film is thinner and the damping is smaller, so the check valve opening pressure can be lowered; under high-speed conditions, the oil film is thicker and the dynamic pressure effect is significant, increasing the damping, so the check valve opening pressure is correspondingly increased.

[0028] After the check valve 3, the oil outlet line 2 splits into two lines: one is the overflow line 4, and the other is the main oil supply line 5. An overflow valve 24 is connected in series on the overflow line 4. This overflow valve 24 is a direct-acting type with a rated pressure of 16 bar. The function of the overflow valve 24 is to limit the maximum operating pressure of the system. When the pressure in the oil outlet line 2 rises to 16 bar or higher for some reason (such as blockage in subsequent lines or excessively high oil viscosity), the overflow valve 24 opens, and the excess high-pressure oil is directly discharged to the return oil main line 13 through the overflow line 4, thereby protecting the electric pump 21 and pipeline components from damage. A first pressure test connector 25 is also installed on the pipeline upstream of the overflow valve 24 (i.e., near the oil outlet line 2) for pressure measurement during temporary on-site calibration or troubleshooting.

[0029] In addition to receiving the main oil flow from the outlet line 2, the main oil supply line 5 is also connected to a drain line 26 and an auxiliary line 30. The drain line 26 is sequentially equipped with a first pressure sensor 27, a second drain ball valve 28, and a second temperature sensor 29. The first pressure sensor 27 is used for remote real-time monitoring of the pressure in the main oil supply line 5; the second temperature sensor 29 is used to monitor the oil temperature before filtration; and the second drain ball valve 28 is opened when the system is shut down for maintenance or when the oil in the main oil supply line 5 needs to be drained, discharging the oil in the line to the return line 13 or a dedicated container.

[0030] The auxiliary pipeline 30 connects the overflow pipeline 4 and the main oil supply pipeline 5, and is equipped with a second pressure test connector 31. The function of the auxiliary pipeline 30 is to allow a small portion of lubricating oil to bypass from the main oil supply pipeline 5 to the overflow pipeline 4 and eventually return when the system pressure is low (e.g., less than 16 bar), thereby maintaining a certain circulation flow within the system and preventing the electric pump 21 from overheating due to operation at extremely low flow rates. The second pressure test connector 31 serves as the pressure monitoring point for the auxiliary pipeline 30.

[0031] To ensure sufficient cleanliness of the lubricating oil entering the tested bearing and prevent particulate contaminants from causing surface scratches or clogging of oil holes, a filter 32 is connected in series on the oil supply main pipe 5. Considering the cleanliness requirements of the wind turbine main shaft sliding bearing, the filter 32 in this embodiment adopts a two-stage filter element structure. Specifically, two filter elements are installed inside the housing of the filter 32: the first-stage filter element has a filtration accuracy of 50μm, and the second-stage filter element has a filtration accuracy of 10μm. The oil first flows through the 50μm coarse filter element to intercept larger particles, and then flows through the 10μm fine filter element to remove minute impurities. This two-stage design extends the service life of the fine filter element and reduces maintenance costs.

[0032] A safety valve 33 is connected in parallel with filter 32. The inlet of safety valve 33 is connected to the inlet side of filter 32 (i.e., the front end of the 10μm fine filter element), and the outlet is connected to the outlet side of filter 32 (i.e., the rear end of the 10μm fine filter element). The set pressure of safety valve 33 is 4.5 bar. Its working principle is as follows: When the 10μm fine filter element is gradually clogged by contaminants due to long-term use, the pressure difference across the filter element will gradually increase; when the pressure difference reaches 4.5 bar, safety valve 33 opens, and the oil bypasses the clogged fine filter element and flows directly through the 50μm filter element to the subsequent pipeline, thus ensuring that the system does not experience flow interruption due to filter element clogging. This design embodies the concept of redundancy protection.

[0033] To monitor the filter element's clogging level in real time, a differential pressure transmitter 34 is externally connected to the main oil supply line 5. The two pressure ports of the differential pressure transmitter 34 are connected to the inlet and outlet sides of the filter 32 (i.e., before and after the 10μm filter element), respectively. Its calibrated differential pressure is 3.5 bar. When the differential pressure reaches 3.5 bar, the differential pressure transmitter 34 outputs an electrical signal to remind the operator or control system that the fine filter element needs replacement. This effectively guides maintenance, avoids unnecessary premature replacement, and prevents passive bypassing only after the filter element is severely clogged.

[0034] In this design, safety valve 33 is connected in parallel only with the 10μm fine filter element, while the 50μm coarse filter element is always connected in series in the oil circuit. Therefore, even if safety valve 33 is open, the oil will still be filtered by the 50μm filter element to ensure the system's minimum cleanliness requirements.

[0035] The filtered lubricating oil enters the temperature control valve 6. The temperature control valve 6 is a valve that automatically switches the flow path based on the oil temperature, typically employing a wax-coated or thermally sensitive temperature sensing element. In this embodiment, the switching threshold set for the temperature control valve 6 is 45°C. When the oil temperature is below 45°C, the valve core of the temperature control valve 6 is in the first working position, guiding the oil to the first oil supply branch pipe 7; when the oil temperature reaches or exceeds 45°C, the valve core moves, guiding the oil to the second oil supply branch pipe 8.

[0036] The first oil supply branch pipe 7 is a straight-through pipe with the same diameter as the main oil supply pipe 5. Only one third pressure test connector 35 is installed on the pipe to measure the pressure of this branch. This branch is suitable for operating conditions that do not require active cooling, such as low-temperature start-up and normal-temperature operation.

[0037] The second oil supply branch pipe 8 is sequentially equipped with a fourth pressure testing connector 36 and an air cooler 37. The air cooler 37 is a temperature exchanger for air and oil heat, typically consisting of a tube bundle with heat dissipation fins and a forced-draft fan. Its cooling capacity should be designed according to the maximum heat load. For example, when the oil inlet temperature is 70℃ and cooling to 45℃ is desired, with a flow rate of 60L / min, the cooler's heat dissipation needs to reach approximately 15-20kW. The fan of the air cooler 37 can be configured with multiple speed settings and start / stop control to achieve different cooling depths. The oil temperature at the outlet of the air cooler 37 can be maintained at a set value, such as 45℃, 55℃, 65℃, or 70℃, through PID control of the fan speed. Since the switching threshold of the temperature control valve 6 is 45℃, when the oil temperature is ≥45℃, the oil enters the air cooler 37. However, if the test needs to simulate high-temperature conditions (such as 70℃), the air cooler 37 can be turned off or its fan can be stopped, so that the oil enters the test pipeline 9 through the second oil supply branch pipe 8 at a state close to the original high temperature. In other words, the second oil supply branch pipe 8 is not limited to the cooling function, but can also achieve the direct delivery of high-temperature oil by bypassing or controlling the start and stop of the cooler, thereby achieving the purpose of simulating a wide temperature range (e.g., -30℃ to 80℃).

[0038] The first oil supply branch pipe 7 and the second oil supply branch pipe 8 merge after the air cooler 37 to form the test pipeline 9. Before the merging point, no additional throttling elements are installed on either pipeline to ensure that the pressure loss of the oil is minimized during switching.

[0039] The first oil supply branch pipe 7 and the second oil supply branch pipe 8 converge into the test pipeline 9. The test pipeline 9 is the starting point of the three branches. To ensure independent adjustment and accurate monitoring of each branch, the test pipeline 9 branches into four parallel branches, named Branch 1 (corresponding to the front radial bearing 10), Branch 2 (corresponding to the rear radial bearing 11), Branch 3 (corresponding to the front thrust bearing 12), and Branch 4 (corresponding to the rear thrust bearing 41). Each branch is equipped with, in sequence, a throttle valve 40, a second pressure sensor 38, a third temperature sensor 39, and a flow meter 42. These components are arranged at the front end of the bearing inlet. The throttle valve 40 is used to manually or automatically adjust the flow rate into the bearing to simulate different bearing bearing distribution ratios. The second pressure sensor 38 is used to measure the oil pressure at the bearing inlet, the third temperature sensor 39 is used to measure the oil temperature at the bearing inlet, and the flow meter 42 is used to measure the lubricating oil flow rate of each branch.

[0040] The front radial bearing 10, rear radial bearing 11, front thrust bearing 12, and rear thrust bearing 41 are actual wind turbine main shaft sliding bearing samples and equivalent simulated loads. The bearing housings have oil inlets and outlets, with the outlet connected to the return oil manifold 13 via a hose. For simulating low-temperature conditions, the front radial bearing 10, rear radial bearing 11, front thrust bearing 12, and rear thrust bearing 41 can all be mounted in a common low-temperature chamber. The low-temperature chamber has an openable / closable inspection door and a pipe-sealed interface. All lubricating oil inlets, outlets, and sensor cables enter the low-temperature chamber through sealed joints. The internal temperature of the low-temperature chamber is controlled by an independent refrigeration unit, adjustable within the range of -30℃ to +30℃. When simulating extremely low-temperature conditions, the refrigeration unit is started in advance to lower the internal air temperature to the target value and maintain this temperature for at least 30 minutes to allow the bearing body and surrounding structures to reach thermal equilibrium. At this time, when the lubricating oil delivered from the test pipeline 9 enters the bearing in the low temperature chamber, the oil temperature will drop due to the pipeline being exposed to a low temperature environment. However, more importantly, the bearing itself is in an extremely low temperature state, thus simulating the working condition of a low temperature bearing encountering a relatively high temperature lubricating oil during the cold start of a wind turbine in a frigid environment.

[0041] The foregoing has described in detail an embodiment of a wind turbine main shaft sliding bearing lubrication test system. Based on the wind turbine main shaft sliding bearing lubrication test system described above, this invention also provides a wind turbine main shaft sliding bearing lubrication test method corresponding to the system, including the following steps: Step 1: Experiment preparation and initial settings.

[0042] Check that all system piping connections are secure and electrical wiring is correct. Add lubricating oil to independent oil tank 1, filling it to the upper-middle mark of the level / temperature gauge 19. Close all first drain ball valves 15 and second drain ball valves 28. Open the cover of air filter 18 to ensure the vent is clear. Based on the operating conditions to be simulated, preset the parameters of inverter 23, the threshold of temperature control valve 6, the opening pressure of check valve 3, the calibration pressure of relief valve 24 (preset to 16 bar), and the calibration pressure of safety valve 33 (preset to 4.5 bar). Adjust the throttle valves 40 of each branch to fully open or to 50% of their initial opening.

[0043] Step 2: Oil heating and temperature range simulation.

[0044] According to the test requirements, the target oil temperature is determined. First, simulating a cold start condition in an extremely cold region (-30℃ environment), multiple sets of heaters 16 are activated to heat the oil in the independent oil tank 1 to, for example, -30℃. Alternatively, simulating a high-temperature rated condition (80℃), the heaters 16 heat the oil to 80℃ and maintain that temperature. The first temperature sensor 17 provides real-time feedback of the oil temperature to the controller, which uses PID control to adjust the output or start / stop of the heaters 16, stabilizing the oil temperature within ±2℃ of the set value.

[0045] Step 3: System back pressure damping setting.

[0046] Based on the spindle speed to be simulated, the corresponding dynamic damping value of the sliding bearing oil film is calculated and converted into an equivalent back pressure in the oil circuit. The spring preload of the check valve 3 on the oil outlet line 2 is adjusted so that the opening pressure of the check valve 3 equals this back pressure value. For example, when simulating low speed (500 rpm), the back pressure is set to 0.3 bar; when simulating rated speed (1500 rpm), the back pressure is set to 0.5 bar; and when simulating overspeed (2000 rpm), the back pressure is set to 0.8 bar. After adjustment, the electric pump 21 can be jogged briefly to observe whether the reading of the first pressure sensor 27 is close to the set back pressure.

[0047] Step 4: Set the oil supply flow rate.

[0048] The target speed of the variable frequency motor 22 is set by the frequency converter 23, thereby controlling the output flow rate of the electric pump 21. According to the test specifications, multiple flow points are set sequentially: low flow point 10L / min, medium flow point 60L / min, and high flow point 120L / min. After each flow point is set, the system is allowed to run stably for 1 minute, and the actual speed of the electric pump 21 and the pressure value on the oil outlet line 2 are recorded.

[0049] Step 5: Pressure protection verification.

[0050] Start the electric pump 21 and gradually increase the output frequency of the inverter 23 to raise the pressure in the oil outlet line 2. Observe whether the relief valve 24 opens normally and whether oil flows through the overflow line 4 when the pressure reaches 16 bar. At the same time, the value of the first pressure sensor 27 should stabilize around 16 bar and no longer rise. Then reduce the frequency, and the pressure drops below 16 bar. Confirm that the relief valve 24 is closed. This step verifies that the overpressure protection function is normal.

[0051] Step 6: Filtering and bypass function test.

[0052] With filter 32 in normal condition, start the system and observe whether the differential pressure transmitter 34 sends a signal. Simulate filter blockage and observe whether the differential pressure transmitter 34 outputs an alarm signal when the differential pressure reaches 3.5 bar. Continue to increase the differential pressure to 4.5 bar. At this point, you should hear or observe the safety valve 33 opening, the pressure in the main oil supply line 5 no longer increasing, and the system can still maintain a certain flow rate through the 50μm filter element. This step verifies the effectiveness of the filter safety protection.

[0053] Step 7: Temperature control valve and cooling function test.

[0054] Set up independent oil tank 1 and heater 16 to stabilize the oil temperature at 40℃, 45℃, 50℃, and 70℃ respectively. Observe the operation of temperature control valve 6; when the oil temperature is 40℃, temperature control valve 6 should open the first oil supply branch pipe 7, and there should be no oil flow or a very small flow in the second oil supply branch pipe 8; when the oil temperature is 45℃, temperature control valve 6 should be in a critical switching state; when the oil temperature is 50℃, temperature control valve 6 should fully open the second oil supply branch pipe 8, and the first oil supply branch pipe 7 should be closed or only have a very small flow. For oil temperatures of 50℃ and above, select whether to turn on the air cooler 37 according to the test requirements. For example, when simulating a 70℃ high-temperature condition, turn off the air cooler 37 or stop the fan, allowing the 70℃ oil to directly enter the test pipeline 9; when simulating a 45℃ standard condition, turn on the air cooler 37 and run the fan at full speed to cool the 70℃ oil to 45℃. Record the temperature difference between the inlet and outlet of the cooler and the cooling time.

[0055] Step 8: Bearing branch flow distribution test.

[0056] After setting the above operating conditions (temperature, back pressure, total flow rate), introduce the oil into the test pipeline 9. Slowly adjust the throttle valves 40 on each branch to ensure that the flow distribution of the four branches meets the design target (e.g., 30% for the front radial bearing 10, 20% for the rear radial bearing 11, 30% for the front thrust bearing 12, and 20% for the rear thrust bearing 41, or according to the actual bearing design requirements). During adjustment, an external flow meter can be used or the change in the value of the second pressure sensor 38 can be observed indirectly to determine the flow distribution. After 5 minutes of stable operation, record the readings P_front, P_rear, and P_thrust of the second pressure sensor 38 for each branch. Calculate the average value P_avg of these three pressure values. If any pressure value deviates from the average value by more than ±10% (e.g., P_front < 0.9 × P_avg or P_front > 1.1 × P_avg), it is determined that there is an uneven flow distribution problem in that bearing branch. Furthermore, if the pressure in a branch is too low, it indicates that the flow resistance in that branch is too high or the throttle valve opening is too small; if the pressure is too high, it indicates that the flow rate in that branch is too high or there is a blockage downstream.

[0057] Step 9: Multi-condition combination test.

[0058] Following an orthogonal experimental design, temperatures (e.g., -30℃, 20℃, 45℃, 70℃), back pressures (e.g., 0.3, 0.5, 0.8 bar), and total flow rates (10, 60, 120 L / min) are combined, and steps 2-8 are repeated, recording the pressure and temperature data for each branch under each combination. These data can be plotted as a condition-pressure deviation curve to evaluate the lubrication robustness of the sliding bearing under a wide range of operating conditions.

[0059] Step 10: Test ends and system is restored.

[0060] After all tests are completed, first, gradually reduce the speed of electric pump 21 to zero using frequency converter 23 to stop oil supply. Then, turn off heater 16 and air cooler 37. Open the first drain ball valve 15 and the second drain ball valve 28 to drain the lubricating oil from independent oil tank 1 and pipelines to the oil storage tank, or retain it in the system for later use. Close all valves and disconnect the power supply.

[0061] This invention achieves the following beneficial effects: First, by combining the heating and air-cooling circuits of the independent oil tank 1 with the automatic switching of the temperature control valve 6, it can accurately simulate the complex operating conditions across temperature ranges from low to high temperatures, solving the problem of undetectable flow distribution deviations during low-temperature startup. Second, by setting an adjustable one-way valve 3 on the oil outlet pipeline 2, it simulates the dynamic changes in oil film damping at different speeds, making the test environment closer to the real operating state. Third, by setting pressure sensors and throttle valves on the four bearing branches respectively, and using a pressure deviation judgment method, it achieves a quantitative evaluation of the flow distribution of each bearing bush, providing data support for design improvement. Fourth, through multiple protections of the overflow valve 24, safety valve 33, and differential pressure transmitter 34, the safety and maintainability of the system are improved. Fifth, it provides a standardized multi-condition test procedure, which is convenient for unified execution in factory inspection, improving the level of product quality control.

[0062] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set, comprising an independent oil tank (1), characterized in that, The oil outlet pipe (2) of the independent oil tank (1) is connected to the overflow pipe (4) and the main oil supply pipe (5) through the check valve (3). The main oil supply pipe (5) is divided into the first oil supply branch pipe (7) and the second oil supply branch pipe (8) through the temperature control valve (6). The oil temperature of the first oil supply branch pipe (7) is less than 45°C, and the oil temperature of the second oil supply branch pipe (8) is greater than or equal to 45°C. The first oil supply branch pipe (7) and the second oil supply branch pipe (8) flow together to the test pipe (9). The test pipe (9) is divided into four branches and is connected to the front radial bearing (10), the rear radial bearing (11), the front thrust bearing (12), and the rear thrust bearing (41) of the sliding bearing of the main shaft of the wind turbine generator set, respectively. The test pipe (9) and the overflow pipe (4) flow together to the return oil main pipe (13). The return oil main pipe (13) is connected to the independent oil tank (1).

2. The lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 1, characterized in that, The independent oil tank (1) is provided with an oil filling hole (14) and a first oil drain ball valve (15) at the top and bottom of the side, respectively. Multiple sets of heaters (16) are installed in the independent oil tank (1). The independent oil tank (1) is equipped with a first temperature sensor (17), an air filter (18), a liquid level and temperature gauge (19), and a liquid level and temperature switch (20).

3. The lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 1, characterized in that, An electric pump (21) for adjusting the oil output rate is installed on the oil outlet pipeline (2). The electric pump (21) is equipped with a variable frequency motor (22), and the variable frequency motor (22) is equipped with a frequency converter (23).

4. The lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 1, characterized in that, An overflow valve (24) is provided on the overflow pipeline (4). A first pressure test connector (25) is installed on the pipeline at the front end of the overflow valve (24). An oil supply main pipe (5) is connected to an oil drain pipeline (26). A first pressure sensor (27), a second oil drain ball valve (28), and a second temperature sensor (29) are installed on the oil drain pipeline (26).

5. The lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 4, characterized in that, An auxiliary pipeline (30) is provided between the overflow pipeline (4) and the main oil supply pipeline (5). A second pressure tester (31) is installed on the auxiliary pipeline (30). The rated pressure of the overflow valve (24) is 16 bar.

6. The lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 1, characterized in that, The front end of the temperature control valve (6) is provided with a filter (32) mounted on the oil supply main pipe (5). The filter (32) is connected in parallel with a safety valve (33). The set pressure of the safety valve (33) is 4.5 bar. The oil supply main pipe (5) is externally connected with a differential pressure transmitter (34).

7. The lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 6, characterized in that, The filter (32) is a two-stage filter structure with two filter elements having calibers of 10μm and 50μm respectively. The differential pressure transmitter (34) is calibrated to transmit a differential pressure of 3.5 bar. The safety valve (33) is connected in parallel with the 10μm filter element of the filter (32). The safety valve (33) is calibrated to a pressure of 4.5 bar.

8. The lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 1, characterized in that, The first oil supply branch pipe (7) and the second oil supply branch pipe (8) are respectively equipped with a third pressure tester (35) and a fourth pressure tester (36). The rear end of the fourth pressure tester (36) is provided with an air cooler (37) mounted on the second oil supply branch pipe (8).

9. A lubrication test system for the sliding bearing of the main shaft of a wind turbine generator set according to claim 1, characterized in that, The test pipeline (9) is equipped with a second pressure sensor (38), a third temperature sensor (39), a throttle valve (40), and a flow meter (42) on each of its four branches. The second pressure sensor (38), the third temperature sensor (39), the throttle valve (40), and the flow meter (42) are all mounted at the front end of the front radial bearing (10), the rear radial bearing (11), the front thrust bearing (12), and the rear thrust bearing (41).

10. A method for testing the lubrication of sliding bearings on the main shaft of a wind turbine generator set, comprising the lubrication testing system for sliding bearings on the main shaft of a wind turbine generator set according to any one of claims 1-9, characterized in that, The method includes: When the front radial bearing (10), rear radial bearing (11), front thrust bearing (12), and rear thrust bearing (41) of the main shaft sliding bearing of the wind turbine generator set are lubricated, the independent oil tank (1) supplies pressurized lubricating oil to the main oil supply pipe (5) through the oil outlet pipe (2); when the pressure of the oil outlet pipe (2) is greater than or equal to 16 bar, the overflow valve (24) is opened, and the pressurized lubricating oil returns to the independent oil tank (1) through the overflow pipe (4) and the return oil main pipe (13) in sequence; when the pressure of the oil outlet pipe (2) is less than 16 bar, the pressurized lubricating oil is filtered. After being filtered by the 10μm and 50μm filter elements of the device (32), the oil reaches the temperature control valve (6); when the temperature of the pressure lubricating oil in the main oil supply pipe (5) is less than 45℃, the pressure lubricating oil enters the test pipeline (9) through the first oil supply branch pipe (7); when the temperature of the pressure lubricating oil in the main oil supply pipe (5) is greater than or equal to 45℃, the pressure lubricating oil enters the test pipeline (9) through the second oil supply branch pipe (8) and after being cooled by the air cooler (37); the pressure lubricating oil in the test pipeline (9) returns to the independent oil tank (1) through the return oil main pipe (13).

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