Online monitoring system and method for grease metal particles of main bearing of wind driven generator

Abstract

The invention discloses a wind driven generator main bearing grease metal particle on-line monitoring system and method, and relates to the technical field of wind power generation monitoring, the system comprises a grease diversion mechanism, a grease sampling box, a heating mechanism, an on-line monitoring device, a waste oil tank, a real-time signal processing module, a data analysis processing module and a man-machine interaction terminal, the grease guide mechanism is arranged beside the low point of the partition plate between the bearing seat of the main bearing and the oil return cavity; the heating mechanism is used for heating the lubricating grease in the grease sampling box; the on-line monitoring device is connected to the downstream of the grease sampling box, detects the content of magnetic metal particles in the lubricating grease based on an inductance principle, and uploads collected signals to the real-time signal processing module; the processed signal is uploaded to the data analysis processing module for analysis processing, the health state of the bearing is evaluated and displayed through the man-machine interaction terminal, and the problem that in the prior art, online monitoring of the lubricating grease containing magnetic metal particles of the main bearing of the wind driven generator is difficult to achieve is solved.

Description

Technical Field

[0001] This invention relates to the field of wind power generation monitoring technology, specifically to an online monitoring system and method for metal particles in grease of wind turbine main bearings. Background Technology

[0002] In the field of wind power generation, large wind turbines generally adopt a horizontal layout structure and can be divided into three categories according to their transmission type: low-speed direct-drive, medium-speed semi-direct-drive, and high-speed. Regardless of the transmission type, wind turbines are equipped with a mechanical transmission chain system (referred to as the shaft system) consisting of a main shaft and bearing housings. A main bearing must be installed between the main shaft and the bearing housings to bear the load of the entire wind turbine. Due to the low rotational speed of the wind turbine rotor and the large wind load it bears, the main bearings are usually large grease-lubricated rolling bearings, commonly including double-row tapered bearings, single-row tapered bearings, and three-row column bearings.

[0003] As a core component of wind turbines, the main bearing's operating condition directly determines the safe and stable operation of the turbine. If the main bearing malfunctions, fails, or malfunctions, it must be removed from the turbine for repair. This process is extremely costly, often costing several times the value of the bearing itself, or even equivalent to the value of the entire turbine. Failure to address this promptly can lead to severe bearing wear and even breakage, causing the entire turbine to seize up. In extreme cases, it can even trigger a turbine overturning, further amplifying economic losses and safety concerns.

[0004] Because the main bearing operates in a closed environment, it is impossible to directly observe the real-time operating status of its internal components. Therefore, indirect methods are needed to monitor and evaluate its operating status. Among these methods, analyzing the properties of the lubricating grease is one of the most commonly used monitoring techniques. The performance of the lubricating grease in wind turbine main bearings (such as water content and solid particle content) has a decisive impact on the bearing's service life and reliability. During unit operation, the main bearing inevitably experiences wear. Because the bearing is made of special rolling bearing steel, the metal particles generated by wear are mainly ferromagnetic iron particles, which are then encapsulated and mixed with the lubricating grease. During the initial break-in period, a small amount of iron particles usually does not significantly affect bearing performance and can be discharged through the lubrication circuit by the fresh grease injected by the automatic grease injection system. However, when abnormal bearing operation leads to abnormal wear, the iron particle content in the lubricating grease will gradually increase. This not only degrades the lubricating performance of the grease but also further exacerbates bearing wear, potentially leading to main bearing failure. Conversely, abnormal iron particle content in the lubricating grease (especially abnormal trends) often indicates potential main bearing failure or even imminent failure. Therefore, by monitoring the content and trend of iron particles in the grease, the operating status of the main bearing can be effectively assessed, providing a basis for bearing condition assessment and fault diagnosis.

[0005] The grease used in wind turbines mainly consists of base oil, thickener, and limiting additives. Its working characteristics are as follows: during bearing operation, the base oil precipitates from the thickener to form an oil film; when the bearing stops operating, the base oil is reabsorbed by the thickener. The viscosity of the base oil determines the oil film thickness; the higher the viscosity, the thicker the oil film. The penetration of the thickener affects the grease's fluidity; a higher penetration results in better fluidity. In the wind power field, to balance effective grease discharge and leak prevention, greases with a 0.1mm penetration of 305-340 mm at room temperature are typically selected. From a monitoring convenience perspective, the grease needs good fluidity to smoothly enter the monitoring equipment; however, excessively high penetration increases the risk of leakage. Therefore, the characteristics of the grease impose specific requirements on the monitoring scheme.

[0006] Currently, the main methods for monitoring the lubricating grease in the main bearings of wind turbines include spectral analysis, capacitive measurement, and inductive measurement. However, all existing methods have significant drawbacks and cannot meet actual monitoring needs: First, spectral analysis equipment has a complex structure and cumbersome testing process, and is only suitable for offline measurement, requiring samples to be taken from the operating unit and sent to a professional institution or laboratory for testing, making it impossible to achieve equipment miniaturization and online monitoring deployment. Second, capacitive measurement methods are easily affected by various factors such as moisture, non-metallic particles, and non-magnetic metallic particles in the lubricating grease, and cannot accurately achieve online monitoring and analysis of ferromagnetic particles. Third, although inductive measurement methods are highly sensitive to magnetic metallic particles, existing technologies and equipment still use offline measurement modes, failing to achieve true online monitoring.

[0007] The core technical challenges of existing monitoring methods for online monitoring lie in two aspects: First, the high viscosity of the main bearing grease makes online collection and sampling difficult using conventional methods such as suction. This is especially true in cold winters in northern regions or at high altitudes and other special environments, where the grease viscosity further increases, significantly increasing the difficulty of online sampling. Second, when the grease contains a high content of particulate matter such as iron particles, its fluidity further deteriorates, exacerbating the difficulty of online collection and sampling. In summary, existing technologies cannot achieve accurate, real-time online monitoring of the iron particle content in the grease of wind turbine main bearings, resulting in the inability to detect early potential failures in the main bearing in a timely manner and hindering the safe and stable operation of the wind turbine. Therefore, there is an urgent need to develop an online monitoring solution that can solve these technical challenges. Summary of the Invention

[0008] The purpose of this invention is to provide an online monitoring system and method for metal particles in the grease of wind turbine main bearings, solving the problem of difficulty in online monitoring of magnetic metal particles in the lubricating grease of wind turbine main bearings in existing technologies. The monitoring system and method of this invention are applicable to online monitoring of metal particles in the grease of main bearings in various types of wind turbine mechanical transmission chains, including direct-drive, doubly-fed, and semi-direct-drive wind turbines.

[0009] This invention is achieved through the following technical solution: An online monitoring system for grease metal particles in the main bearing of a wind turbine includes a grease guiding mechanism, a grease sampling box, a heating mechanism, an online monitoring device, a waste oil tank, a real-time signal processing module, a data analysis and processing module, and a human-machine interaction terminal. A valve is provided on the channel connecting the grease guiding mechanism and the grease sampling box. The grease guiding mechanism is located at the low point of the partition between the bearing seat and the oil return chamber of the main bearing, and is used to guide the grease that has passed through the bearing raceway into the grease sampling box. The heating mechanism is used to heat the grease in the grease sampling box to reduce the viscosity of the grease. The waste oil tank is used to recycle waste lubricating grease after testing; The online monitoring device is connected downstream of the grease sampling box and detects the content of magnetic metal particles in the grease based on the inductive principle, and uploads the collected signal to the real-time signal processing module. The real-time signal processing module uploads the processed signal to the data analysis and processing module for analysis and processing, assesses the health status of the bearing, and displays it through the human-machine interface terminal.

[0010] Furthermore, the heating mechanism is installed and fixed at the bottom of the grease sampling box.

[0011] Furthermore, the grease guiding mechanism is equipped with a millimeter-level filter screen, and the lower part of the filter screen is connected to a conical guide groove. The lower pipe has a diameter of ≥30mm, and the pipe is equipped with a valve and a flow sensor I adapted to high-viscosity grease. The pipe of the grease guiding mechanism passes through the cover plate I of the oil return chamber. One end of the pipe is connected to the bearing seat by bolts; the other end is connected to the grease sampling box by flange. Both ends of the pipe are equipped with heat insulation layer and shock-absorbing rubber pad. A flat sealant layer is applied to the gaps of the cover plate I.

[0012] Furthermore, the grease sampling box is equipped with an exhaust valve I at the top and a valve at the bottom, and a temperature sensor is installed inside; the temperature sensor is connected to the heating mechanism by signal, and the heating mechanism is started and stopped by controlling the temperature threshold to ensure that the viscosity of the lubricating grease is reduced to the preset fluidity requirement.

[0013] Furthermore, the heating mechanism includes a housing, an electric heater, and a support frame; The box body is welded or attached to the lower part of the oil sampling box. The electric heater is fixed to the box body by a support frame. The electric heater adopts a ring-shaped double-layer heating tube and is fitted with heat sink. The rated power is 100W~2000W. The heating tube and fins are placed in high boiling point heat transfer oil. The heating mechanism is equipped with an exhaust valve II at the top, which is used to maintain the internal pressure balance under cold and hot conditions.

[0014] Furthermore, the online monitoring device includes a coil, a support frame, thermally conductive adhesive, a flow sensor II, a grease pipe, a housing, and a housing cover plate; The coil is wound with rectangular electromagnetic wire made of polyimide or polyester film, and the space between the coil and the outer shell is filled with insulating and thermally conductive adhesive. The outer casing and cover plate are made of copper sleeve, aluminum alloy or steel plate, and the gap between them and the coil is not less than 2 times the diameter of the oil pipe; The grease tube is made of polytetrafluoroethylene or alumina ceramic material; Flow sensor II is installed on the grease pipe to monitor whether the grease enters the monitoring equipment smoothly and whether the grease in the grease sampling box is emptied. The coil is supplied with a high-frequency alternating current of 50~1000Hz. The change in current caused by the change in magnetic flux is detected by the current detection module, and the real-time content of magnetic metal particles is calculated.

[0015] Furthermore, the waste oil tank is equipped with a liquid level sensor. Preferably, a high liquid level sensor is used to monitor the waste oil level and issue an early warning when the liquid level is too high; The real-time signal processing module is used to filter the detection signal and remove outliers. The data analysis and processing module connects the data processed by the real-time signal processing module to the main control and centralized control system of the whole machine for storage and analysis. When an abnormality in the lubricating grease is detected, it automatically sends a grease injection strategy adjustment command to the actuator of the automatic lubrication system.

[0016] A method for online monitoring of grease metal particles in the main bearing of a wind turbine includes the following steps: S1. A grease guide mechanism is provided by placing the grease guide mechanism at the low point of the partition plate between the main bearing housing and the oil return chamber, and the grease guide mechanism is provided with a millimeter-level filter screen and a conical guide groove, and the diameter of the lower pipe is ≥30mm. S2. Open the valve between the grease diversion mechanism and the grease sampling box. After the flow sensor I detects that the grease amount has reached the preset value, close the valve to leave the grease in the grease sampling box. S3. Activate the heating mechanism at the bottom of the grease sampling box to heat the grease inside the box. Use a temperature sensor to monitor the grease temperature in real time. When the temperature reaches the preset threshold and the grease viscosity decreases to the preset fluidity requirement, turn off the heating mechanism. S4. Open the valve at the bottom of the grease sampling box. When the flow sensor II of the online monitoring device detects that the grease flow meets the detection requirements, start the online monitoring device. The magnetic field is generated by the coil with a high frequency AC current of 50~1000Hz. The change in coil current caused by magnetic metal particles is detected, and the real-time content of magnetic metal particles is calculated. S5. The detection signal is filtered and outliers are removed by the real-time signal processing module. After being stored and analyzed by the data analysis and processing module, the health status of the main bearing is evaluated and displayed through the human-machine interaction terminal.

[0017] Furthermore, when an abnormal content of magnetic metal particles in the grease is detected in step S5, an instruction is issued to the automatic lubrication system actuator to adjust the grease injection cycle and the amount of grease injected; the waste grease after detection is discharged into the waste oil tank for recycling.

[0018] Furthermore, in step S1, the pipe of the grease guiding mechanism passes through the two halves of the cover plate I of the oil return chamber. The interfaces at both ends of the pipe are provided with heat insulation layers and shock-absorbing rubber pads. The gaps of the cover plate I are coated with flat sealant to ensure that there is no heat transfer or vibration interference during the guiding process, and that the sample is fresh waste grease that is not contaminated.

[0019] Furthermore, in step S3, the electric heater of the heating mechanism adopts a ring-shaped double-layer structure and is equipped with heat sinks, with a rated power of 100W~2000W. During the heating process, the internal pressure balance under cold and hot states is maintained by the exhaust valve II at the top of the heating mechanism. The preset temperature threshold is determined according to the viscosity characteristics of the grease to ensure that the grease flowability meets the detection requirements.

[0020] Furthermore, in step S4, the coil of the online monitoring device is wound with rectangular electromagnetic wire made of polyimide or polyester film, and the space between the coil and the outer shell is filled with insulating and thermally conductive adhesive. The gap between the outer shell and the coil is not less than twice the diameter of the grease tube. The grease tube is made of polytetrafluoroethylene or alumina ceramic non-magnetic and non-conductive material to shield against external electromagnetic interference.

[0021] Furthermore, steps S2 to S4 employ step-by-step closed-loop control logic, with the following specific sequence: open the valve on the grease diversion mechanism → close the valve after the flow rate reaches the target → start the heating mechanism → close the heating mechanism after the temperature reaches the target → open the valve on the grease sampling box → start the online monitoring device after the flow rate reaches the target → close the online monitoring device after signal acquisition is completed → finally close the valve on the grease sampling box.

[0022] Furthermore, in step S5, the data analysis and processing module connects the processed detection data to the main control and centralized control system of the whole machine, establishes a health status assessment model in combination with the bearing operating parameters, and outputs the bearing wear level in real time.

[0023] Furthermore, a high-level sensor is installed on the waste oil tank. When the waste grease level is detected to exceed a preset value, a cleaning warning is issued to prevent waste grease from overflowing and contaminating the engine compartment.

[0024] Furthermore, in step S1, the valve (preferably a solenoid valve) of the grease guiding mechanism is normally closed. After sampling is completed, the valve is closed to prevent air backflow after heating from damaging the bearing and grease, and to ensure that the next sample is of the freshest grease flowing through the bearing raceway.

[0025] Furthermore, in step S3, the detection accuracy of the temperature sensor is not less than ±0.5℃. When the temperature of the grease is lower than the preset threshold, the heating mechanism is automatically restarted to maintain the fluidity of the grease.

[0026] Furthermore, in step S4, the preset standard curve is calibrated by testing a grease sample with a known magnetic metal particle content, and real-time calibration is performed during the testing process to ensure the accuracy of the metal particle content estimation.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention proposes an online monitoring system for grease-containing metal particles in the main bearings of wind turbine generators. This system achieves continuous online monitoring of magnetic metal particles in the grease of wind turbine generator main bearings through a rational layout of core modules including grease guiding, sampling, heating, monitoring, signal processing, and interaction. The grease guiding mechanism precisely guides the grease through the bearing raceway, ensuring the representativeness of the test sample; the heating mechanism reduces the viscosity of the grease, solving the detection difficulties caused by the poor flowability of high-viscosity grease; the online monitoring device based on inductive principle accurately captures the magnetic metal particle content signal. Combined with real-time signal processing and data analysis modules, it can quickly assess the bearing's health status and display it intuitively through a human-machine interface terminal, allowing staff to promptly grasp the bearing wear situation, provide early warning of potential failures, avoid wind turbine downtime losses due to bearing failure, and significantly improve the reliability and safety of wind turbine operation. Through the innovative combination of integrated online monitoring and heating viscosity reduction, it breaks through the technical limitations of traditional offline testing in low-temperature environments and high-viscosity grease sampling. It is adaptable to various turbine models such as direct-drive, doubly-fed, and semi-direct-drive, achieving real-time online monitoring of grease-containing metal particles in the main bearings.

[0028] II. This invention proposes a preferred online monitoring system for metal particles in the grease of wind turbine main bearings. The heating mechanism is installed and fixed at the bottom of the grease sampling box, allowing the heat source to directly act on the bottom area of ​​the grease within the sampling box. This achieves uniform heat conduction from bottom to top, avoiding inconsistent grease viscosity caused by uneven local heating. It ensures that the overall viscosity of the grease is stably reduced to the preset flowability requirement, guaranteeing the accuracy of subsequent online monitoring. Simultaneously, the bottom-mounted structure is compact, does not occupy excessive space around the sampling box, facilitates the overall system layout and installation, and is firmly fixed, adapting to the vibration environment during wind turbine operation and improving the stability of the heating mechanism.

[0029] III. This invention proposes a preferred online monitoring system for grease metal particles in the main bearing of a wind turbine generator. The millimeter-level filter inside the grease guiding mechanism can effectively filter larger impurities in the grease, preventing them from clogging subsequent pipes or affecting monitoring accuracy. The conical guide groove guides the grease to flow smoothly and prevents accumulation. The lower pipe diameter of ≥30mm is designed to meet the flow requirements of high-viscosity grease and reduce flow resistance. The dedicated valve and flow sensor I on the pipe can accurately control the grease flow and monitor the flow rate. The two ends of the pipe are connected by bolts and flanges, and with the help of heat insulation layer, shock-absorbing rubber pads and flat sealing adhesive layer, the connection is sealed and firm, and the heat loss and the impact of wind turbine vibration on the guiding mechanism are reduced, preventing grease leakage and ensuring a stable and reliable guiding process.

[0030] IV. This invention proposes a preferred online monitoring system for metal particles in the grease of wind turbine main bearings. The exhaust valve I at the top of the grease sampling box can promptly expel air from the box, preventing air residue from causing inaccurate grease levels or affecting subsequent flow. The lower valve facilitates control over the timing of grease release. The internally mounted temperature sensor and heating mechanism form a closed-loop control, enabling real-time monitoring of the grease temperature and automatic start / stop of the heating mechanism based on temperature thresholds. This precisely controls the grease viscosity within a preset flow range, avoiding detection obstruction due to insufficient heating and preventing damage to grease performance due to overheating, thus ensuring smooth online monitoring and accurate test results.

[0031] V. In this invention, a preferred online monitoring system for grease metal particles in the main bearing of a wind turbine generator is proposed. The heating mechanism's housing is fixed to the lower part of the grease sampling box by welding or clamping, ensuring a firm and reliable connection. The annular double-layer heating tube is fitted with heat sinks and high-boiling-point heat transfer oil, which increases the heating area and improves the heat transfer efficiency, allowing for uniform heat dissipation. The rated power range of 100W to 2000W can adapt to the heating requirements of greases of different viscosities. The upper exhaust valve II can balance the internal pressure of the mechanism under cold and hot conditions, preventing damage to the heating mechanism or sampling box caused by abnormal pressure due to temperature changes, ensuring the safety and stability of the heating process, and extending the service life of the heating mechanism.

[0032] VI. This invention proposes a preferred online monitoring system for grease and metal particles in the main bearing of a wind turbine generator. The coil is wound with rectangular electromagnetic wire made of heat-resistant and insulating polyimide or polyester film, and is combined with insulating thermally conductive adhesive between the coil and the outer shell. This ensures both electrical insulation and timely heat dissipation, preventing the coil from overheating. The outer shell and cover plate are made of copper sleeve, aluminum alloy, or steel plate, and the gap between them and the coil is not less than twice the diameter of the grease tube, which can effectively shield external electromagnetic interference and ensure the accuracy of coil detection. The grease tube is made of polytetrafluoroethylene or alumina ceramic material that does not affect magnetic detection, avoiding interference with the detection signal. Flow sensor II can confirm in real time whether grease has entered the monitoring equipment and whether the grease in the sampling box has been emptied, providing a basis for judging the timing of monitoring. The coil, which is energized with a high-frequency AC current of 50~1000Hz, can generate a stable magnetic field. By detecting the change in current caused by the change in magnetic flux, the real-time content of magnetic metal particles can be accurately calculated, significantly improving the monitoring accuracy and reliability.

[0033] VII. This invention proposes a preferred online monitoring system for grease and metal particles in the main bearings of wind turbines. A level sensor on the waste grease tank monitors the waste grease level in real time, facilitating timely disposal of waste grease and preventing overflow that could cause pollution or equipment malfunction. A real-time signal processing module filters and removes outliers from the detected signals, effectively improving the accuracy and validity of the data. A data analysis and processing module connects the processed data to the main control and centralized control system, enabling centralized storage and analysis of the data and facilitating unified management of the bearing status of multiple wind turbines. When an abnormality in the grease is detected, an automatic grease injection strategy adjustment command is sent to the automatic lubrication system actuator, optimizing the lubrication scheme without manual intervention, reducing bearing wear, extending bearing life, and lowering maintenance costs.

[0034] 8. This invention proposes an online monitoring method for metal particles in the grease of wind turbine main bearings. This method achieves accurate online monitoring of metal particles in the grease through standardized steps: In step S1, the millimeter-level filter, conical guide groove, and large-diameter pipe design of the grease guiding mechanism ensure effective grease extraction, impurity filtration, and smooth flow; in step S2, the sampling amount is precisely controlled by flow sensor I to ensure the consistency of the test samples; in step S3, the grease viscosity is precisely controlled through the cooperation of the heating mechanism and temperature sensor to create favorable conditions for detection; in step S4, the detection conditions are confirmed by flow sensor II, and the high-frequency AC detection method of the coil ensures the accuracy of the metal particle content calculation; in step S5, signal processing and data analysis enable a scientific assessment and intuitive display of the bearing's health status. The entire method is standardized and logically rigorous, efficiently and accurately capturing bearing wear signals, providing early warning of faults, offering a scientific basis for the operation and maintenance of wind turbine bearings, and ensuring the stable operation of wind turbines. The monitoring device based on the principle of high-frequency electromagnetic induction is highly sensitive to ferromagnetic metal particles; combined with the electromagnetic shielding structure of the metal shell and the filling process of insulating and thermally conductive adhesive, it can maintain stable measurement results in complex electromagnetic environments and effectively eliminate the influence of interference factors such as moisture compared with the capacitive measurement method.

[0035] 9. This invention proposes a preferred online monitoring method for grease metal particles in the main bearing of a wind turbine generator. When an abnormal content of magnetic metal particles is detected, the method promptly issues an adjustment command for the grease injection cycle and grease injection amount to the actuator of the automatic lubrication system. This allows for targeted optimization of the lubrication scheme. By increasing the grease injection amount or shortening the grease injection cycle, bearing wear can be effectively alleviated, preventing further expansion of the fault. The waste grease after detection is discharged into the waste oil tank for recycling, which avoids environmental pollution caused by indiscriminate discharge and enables centralized resource treatment, meeting environmental protection requirements. At the same time, it reduces the impact of waste on equipment and the surrounding environment, improving the environmental friendliness and practicality of the system.

[0036] 10. In this invention, a preferred method for online monitoring of grease metal particles in the main bearing of a wind turbine is proposed. When the pipe of the grease guiding mechanism passes through the oil return chamber cover plate I, the heat insulation layer and shock-absorbing rubber pads set at both ends of the interface can effectively reduce heat loss at the pipe and interface, avoid grease viscosity fluctuations caused by temperature changes, and at the same time alleviate the impact of wind turbine operation vibration on pipe connection and prevent interface loosening. The planar sealing adhesive layer applied between the gaps of cover plate I can significantly improve the sealing performance of the interface, effectively prevent grease leakage, ensure the stability and safety of the grease guiding process, avoid insufficient test samples or equipment contamination due to leakage, and extend the service life of the guiding mechanism and related components.

[0037] XI. In this invention, a phased closed-loop control logic of "flow guidance-heating-detection" is adopted, which can dynamically adjust the heating parameters according to the ambient temperature and oil viscosity in different regions. This effectively solves the problem of sampling difficulties in low-temperature environments such as winter in the north and high altitude, ensures stable and reliable sampling efficiency, realizes dynamic intelligent control, and adapts to complex environmental conditions.

[0038] 12. In this invention, the grease is directly discharged into the waste oil tank after testing, without the need for additional processing procedures; key components adopt a modular design, which facilitates replacement and maintenance and shortens maintenance time; it supports multi-protocol interfacing with existing main control and centralized control systems, and is compatible with different types of lubricating grease, which significantly reduces manpower and time costs compared with offline detection by spectral analysis.

[0039] Thirteen, in this invention, the overall system device is small in size and can be directly integrated next to the oil return chamber, saving the installation space of the nacelle; the annular double-layer heating tube design achieves efficient heating in a limited space, adapting to the compact layout requirements of wind power equipment, and is suitable for both newly designed units and intelligent diagnosis, maintenance and upgrade of existing units. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the online monitoring system of the present invention assembled on the main bearing of a wind turbine generator.

[0041] Figure 2 This is a schematic diagram of the online monitoring system for grease and metal particles in the main bearing of a wind turbine generator according to the present invention.

[0042] Figure 3 This is a schematic diagram illustrating the working principle of the online monitoring system of the present invention.

[0043] Figure 4 This is a schematic diagram of the grease guiding mechanism.

[0044] Figure 5 This is a schematic diagram of the structure of cover plate I (split cover plate) of the oil return chamber.

[0045] Figure 6 This is a schematic diagram of the oil sampling box and heating mechanism.

[0046] Figure 7 This is a partial diagram of an electric heater.

[0047] Figure 8 This is a schematic diagram of the online monitoring device.

[0048] Figure 9 This is a schematic diagram of the waste oil tank assembled on the bracket.

[0049] The components include: 1. Grease diversion mechanism; 2. Grease sampling box; 3. Heating mechanism; 4. Online monitoring device; 5. Waste oil tank; 6. Main shaft; 7. Main bearing; 8. Bearing pressure ring; 9. Bearing seat; 10. Oil return chamber; 11. Support; 12. Partition plate; 13. Cover plate I; 1.1 Filter screen; 1.2 Diversion channel; 1.3 Flow sensor I; 1.4 Solenoid valve I; 2.1 Exhaust valve I; 2.2 Temperature sensor; 3.1 Box body; 3.2 Electric heater; 3.3 Support frame; 3.4 Heating tube; 3.5 Exhaust valve II; 4.1 Coil; 4.2 Support frame; 4.3 Thermal conductive adhesive; 4.4 Flow sensor II; 4.5 Grease pipe; 4.6 Outer shell; 4.7 Shell cover plate; 5.1 Liquid level sensor. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0051] Example 1 To facilitate public understanding of the present invention, this embodiment uses a preferred online monitoring system for grease and metal particles in the main bearing of a wind turbine generator as an example to further illustrate the solution. This online monitoring system is applicable to the online monitoring of grease and metal particles in the main bearing 7 of the mechanical transmission chain of various types of wind turbine generators, including direct-drive, doubly-fed, and semi-direct-drive models.

[0052] This online monitoring system adds a bypass channel for monitoring lubricating grease and incorporates heating and viscosity-reducing technology. Without altering the normal working characteristics of lubricating grease, it significantly improves the fluidity of the grease under test, enabling real-time tracking of the metal element content in the grease. (Reference) Figures 1-3 The online monitoring system includes an oil diversion mechanism 1, an oil sampling box 2, a heating mechanism 3, an online monitoring device 4, a waste oil tank 5, a real-time signal processing module, a data analysis and processing module, and a human-machine interaction terminal.

[0053] Wind turbine generator sets mainly consist of mechanical transmission chains, electrical transmission chains, and auxiliary systems such as automatic lubrication. Among these, the shaft system, as a key link in the mechanical transmission chain, bears the responsibility of alternating loads and electromagnetic torque output. Its structure mainly includes components such as bearing housings 9, main shafts 6, main bearings 7, bearing retaining rings 8, and clamping bolts. These components form the shaft system through the design of the retaining rings and the preload of the connecting bolts. During bearing assembly, the bearing retaining rings 8 apply axial pressure to the outer ring of the bearing, while the preload of the clamping bolts creates a rigid connection between the shaft components. This structural design provides rigid support for the main bearing 7, and by precisely controlling the fit and preload, ensures that the bearing clearance is maintained within the design range, thereby meeting the stiffness requirements of the shaft system for wind load resistance and electromagnetic torque transmission.

[0054] In the shaft system structure, the bearing housing 9 and the main shaft 6 enclose each other at the middle to form an oil return chamber 10. Fresh grease flows into the oil return chamber 10 after passing through the bearing raceway. Waste oil in the chamber is periodically cleaned by maintenance personnel to maintain the normal circulation of the lubrication system. The automatic lubrication system delivers fresh grease to the bearing through periodic grease injection, building a protective oil film between the bearing raceway and the rolling elements. This oil film, as a transition surface between the relative dynamic and static connections of the bearing components, provides rigidity support for the bearing and forms a low-friction interface, ensuring stable bearing operation.

[0055] This embodiment adds the online monitoring system of this invention to the bypass within the unit based on the above-described shaft system structure. The grease, after passing through the bearing raceway, is divided into two paths: one flows into the return oil chamber 10; the other bypasses into the grease guiding mechanism 1, thus entering the online monitoring system. In this embodiment, a valve is provided on the channel connecting the grease guiding mechanism 1 and the grease sampling box 2. In this embodiment, a solenoid valve is used. The opening and closing of this solenoid valve controls whether the grease enters the grease sampling box 2. The grease guiding mechanism 1 is positioned at the lowest point of the partition 12 between the bearing seat 9 of the monitored main bearing 7 and the return oil chamber 10, to guide the grease passing through the bearing raceway into the grease sampling box 2, ensuring that the flowing grease is all grease that has passed through the bearing raceway and is not contaminated.

[0056] The heating mechanism 3 is used to heat the grease in the grease sampling box 2 to reduce the viscosity of the grease; the waste oil tank 5 is used to recycle the waste grease after testing; the online monitoring device 4 is connected downstream of the grease sampling box 2 and detects the content of magnetic metal particles in the grease based on the inductive principle, and uploads the collected signal to the real-time signal processing module; the real-time signal processing module uploads the processed signal to the data analysis and processing module for analysis and processing, evaluates the health status of the bearing, and displays it through the human-machine interaction terminal.

[0057] For more specific details, please refer to Figure 4 , 5 The grease guiding mechanism 1 is equipped with a millimeter-level filter screen 1.1 to prevent abnormal fragments from entering the monitoring equipment and causing blockage. A tapered guide groove 1.2 is connected to the lower part of the filter screen 1.1 to facilitate the smooth flow of grease into the pipeline. The lower pipeline diameter is ≥30mm to prevent blockage by high-viscosity grease. The pipeline is equipped with a valve (solenoid valve I1.4) and a flow sensor I1.3 adapted to high-viscosity grease. Before testing, the solenoid valve I1.4 is opened, and the grease flows through the flow sensor I1.3 into the grease sampling box 2. After sampling, the solenoid valve I1.4 is closed to ensure that the next sample is of the most recently flowed grease through the bearing raceway and to prevent backflow of heated air from affecting the normal operation of the bearing.

[0058] The pipe of the grease guiding mechanism 1 passes through the cover plate I13 of the oil return chamber 10. The cover plate I13 is preferably a two-lobed cover plate. (Refer to...) Figure 5 For easy on-site maintenance, a flat sealant is applied to the gaps. One end of the pipe is connected to the bearing housing 9 by bolts; the other end is connected to the grease sampling box 2 by a flange. Both ends of the pipe are equipped with heat insulation layers and shock-absorbing rubber pads. A flat sealant layer is applied to the gaps of the cover plate I13 to reduce heat and vibration transmission.

[0059] Since lubricating grease has a high viscosity compared to liquid oil, it cannot flow from the grease guiding mechanism 1 into the online monitoring device by its own gravity. Therefore, the present invention sets a specific grease sampling box 2 between the grease guiding mechanism 1 and the online monitoring device 4, and adds a heating mechanism 3 at its bottom.

[0060] For details, please refer to Figure 6 The grease sampling box 2 is equipped with an exhaust valve I 2.1 at the top and a solenoid valve at the bottom, and is fitted with a temperature sensor 2.2 inside. The temperature sensor 2.2 is connected to the heating mechanism 3 by signal, and controls the start and stop of the heating mechanism 3 through the temperature threshold to ensure that the viscosity of the lubricating grease is reduced to the preset fluidity requirement.

[0061] In this embodiment, the heating mechanism 3 is installed and fixed to the bottom of the grease sampling box 2. (See reference) Figure 6 , 7 The heating mechanism 3 includes a housing 3.1, an electric heater 3.2, and a support frame 3.3. The housing 3.1 is welded or attached to the lower part of the grease sampling box 2. The electric heater 3.2 is fixed to the housing 3.1 by the support frame 3.3. The electric heater 3.2 adopts a ring-shaped double-layer heating tube 3.4 and is fitted with heat sinks, which reduces space occupation and has high heating efficiency. The rated power is determined according to the amount and viscosity of the grease required by the monitoring device. The rated power is preferably 100W~2000W. The heating tube 3.4 and fins are placed in high-boiling-point heat transfer oil. The upper part of the heating mechanism 3 is provided with an exhaust valve II 3.5 to maintain internal pressure balance under cold and hot conditions.

[0062] In this embodiment, reference Figure 8 The online monitoring device 4 includes a coil 4.1, a support frame 4.2, thermally conductive adhesive 4.3, a flow sensor II 4.4, an oil pipe 4.5, a housing 4.6, and a cover plate 4.7. The coil 4.1 is wound with rectangular electromagnetic wire made of polyimide or polyester film. Insulating thermally conductive adhesive 4.3 is filled between the coil 4.1 and the housing 4.6 to ensure good conductivity, insulation, and heat transfer. The support frame 4.2 is made of non-conductive and non-magnetic insulating material, such as epoxy phenolic glass cloth tubing. The housing 4.6 and cover plate 4.7 are made of copper sleeve, aluminum alloy, or steel plate, and the gap between them and the coil 4.1 is not less than twice the diameter of the oil pipe to shield against external electromagnetic interference affecting measurement accuracy.

[0063] The grease tube 4.5 is made of polytetrafluoroethylene or alumina ceramic. The flow sensor II 4.4 is installed on the grease tube 4.5 to monitor whether the grease enters the monitoring device smoothly and whether the grease in the grease sampling box 2 is emptied. The coil 4.1 is energized with a high-frequency AC current of 50~1000Hz. The current detection module detects the change in current caused by the change in magnetic flux and calculates the real-time content of magnetic metal particles.

[0064] In this embodiment, reference Figure 9 The monitored waste grease flows into the waste oil tank 5 for recycling, preventing it from flowing into the engine compartment. The waste oil tank 5 is equipped with a high liquid level sensor 5.1, which monitors the waste grease level and issues an early warning when the level is too high. The grease sampling box 2, heating mechanism 3, online monitoring device 4, and waste oil tank 5 are fixed on the same bracket 11 and placed as a whole inside the engine compartment.

[0065] In this embodiment, the real-time signal processing module is used to filter the detection signal and remove outliers; the data analysis and processing module connects the data processed by the real-time signal processing module to the main control and centralized control system of the whole machine for storage and analysis, and automatically sends a grease injection strategy adjustment command to the automatic lubrication system actuator when an abnormality in the lubricating grease is detected.

[0066] In this embodiment, the power line of the solenoid valve of the grease diversion mechanism 1 is led out through the cover plate I13 and then converges with the power line of the electric heater 3.2, the power line of the solenoid valve on the grease sampling box 2, the signal line of the flow sensor, the signal line of the liquid level sensor 5.1, the power line and signal line of the measuring mechanism to a dedicated control box separately set up in the engine room. All signal lines are effectively shielded by the shielding layer to avoid electromagnetic interference.

[0067] The monitoring method based on the above-mentioned online monitoring system for grease metal particles in the main bearing of a wind turbine includes the following steps: S1. The grease that has passed through the bearing raceway is drawn out by the grease guiding mechanism 1, which is located at the low point of the partition plate 12 between the main bearing 7 bearing seat 9 and the oil return chamber 10. The grease guiding mechanism 1 is equipped with a millimeter-level filter screen 1.1 and a conical guide groove 1.2, and the diameter of the lower pipe is ≥30mm.

[0068] In this step, the pipe of the grease guiding mechanism 1 passes through the two halves of the cover plate I13 of the oil return chamber 10. The interfaces at both ends of the pipe are provided with heat insulation layer and shock-absorbing rubber pads. The gaps of the cover plate I13 are coated with flat sealant to ensure that there is no heat transfer or vibration interference during the guiding process, and the sample is fresh waste grease that is not contaminated.

[0069] In this step, the valve (preferably a solenoid valve) of the grease guiding mechanism 1 is normally closed. After sampling is completed, the valve is closed to prevent air backflow after heating from damaging the bearing and grease, and to ensure that the next sample is the freshest grease flowing through the bearing raceway.

[0070] S2. Open the valve between the grease diversion mechanism 1 and the grease sampling box 2. After the flow sensor I1.3 detects that the amount of grease has reached the preset value, close the valve (solenoid valve) to leave the grease in the grease sampling box 2.

[0071] S3. Start the heating mechanism 3 at the bottom of the grease sampling box 2 to heat the grease in the box 3.1. Use the temperature sensor 2.2 to monitor the grease temperature in real time. When the temperature reaches the preset threshold and the grease viscosity decreases to the preset fluidity requirement, turn off the heating mechanism 3.

[0072] In this step, the electric heater 3.2 of the heating mechanism 3 adopts a ring-shaped double-layer structure and is equipped with heat sinks. The rated power is 100W~2000W. During the heating process, the internal pressure balance under cold and hot states is maintained by the exhaust valve II 3.5 on the upper part of the heating mechanism 3. The preset temperature threshold is determined according to the viscosity characteristics of the grease to ensure that the grease fluidity meets the testing requirements.

[0073] In this step, the temperature sensor 2.2 is preferably a sensor with a detection accuracy of not less than ±0.5℃. When the temperature of the grease is lower than the preset threshold, the heating mechanism 3 is automatically restarted to maintain the fluidity of the grease.

[0074] S4. Open the valve (solenoid valve) at the bottom of the grease sampling box 2. When the flow sensor II 4.4 of the online monitoring device 4 detects that the grease flow meets the detection requirements, start the online monitoring device 4. The magnetic field is generated by the coil 4.1 which is energized with a high frequency AC current of 50~1000Hz. The change in current of the coil 4.1 caused by the magnetic metal particles is detected, and the real-time content of the magnetic metal particles is calculated.

[0075] In this step, the coil 4.1 of the online monitoring device 4 is wound with rectangular electromagnetic wire of polyimide or polyester film. The space between the coil 4.1 and the outer shell 4.6 is filled with insulating thermally conductive adhesive 4.3. The gap between the outer shell 4.6 and the coil 4.1 is not less than twice the diameter of the grease tube 4.5. The grease tube 4.5 is made of polytetrafluoroethylene or alumina ceramic non-magnetic and non-conductive material to shield external electromagnetic interference.

[0076] In this step, the preset standard curve is calibrated by testing grease samples with known magnetic metal particle content. The calibration is performed in real time during the testing process to ensure the accuracy of the metal particle content estimation.

[0077] The magnetic permeability of ferromagnetic metal elements (such as iron, nickel, cobalt, etc.) in bearings is much higher than that of air or fresh grease (for example, the relative magnetic permeability of iron can reach 10). 3 ~10 4The permeability of the grease is significantly altered when metal particles generated by the wear of air (approximately 1) mix with the grease. When a high-frequency alternating current (e.g., 50-1000Hz, with higher frequencies resulting in greater sensitivity) is applied to the wound coil 4.1 to generate a magnetic field, metal particles passing through the middle of coil 4.1 will cause a change in the magnetic flux through coil 4.1 due to the difference in permeability. This induces an electromotive force in coil 4.1, leading to a change in current. By measuring the change in current and combining it with a pre-established standard curve (calibrated using samples with known metal particle content), the real-time content of metal particles in the grease can be calculated.

[0078] S5. The detection signal is filtered and outliers are removed by the real-time signal processing module. After being stored and analyzed by the data analysis and processing module, the health status of the main bearing 7 is evaluated and displayed through the human-machine interaction terminal.

[0079] In this step, when an abnormal content of magnetic metal particles in the grease is detected, an instruction is given to the automatic lubrication system actuator to adjust the grease injection cycle and the amount of grease injected; the waste grease after detection is discharged into the waste oil tank 5 for recycling.

[0080] The detection signal is connected to the main control and centralized control system. By establishing a standard curve of current change and metal particle content, the bearing health status can be intelligently assessed. In case of abnormality, the grease injection cycle and grease injection amount can be automatically adjusted, upgrading the traditional post-diagnosis to early wear warning and reducing the risk of equipment removal.

[0081] The data analysis and processing module connects the processed detection data to the main control and centralized control system of the whole machine, and establishes a health status assessment model in combination with the bearing operating parameters, and outputs the bearing wear level in real time.

[0082] The waste oil tank 5 is equipped with a high liquid level sensor 5.1. When the waste lubricating grease level is detected to exceed the preset value, a cleaning warning is issued to prevent waste grease from overflowing and polluting the engine compartment.

[0083] The above steps S2~S4 adopt step-by-step closed-loop control logic. The specific sequence is as follows: open the valve on the grease diversion mechanism 1 → close the valve after the flow rate reaches the standard → start the heating mechanism 3 → close the heating mechanism 3 after the temperature reaches the standard → open the valve on the grease sampling box 2 → start the online monitoring device 4 after the flow rate reaches the standard → close the online monitoring device 4 after the signal acquisition is completed → finally close the valve on the grease sampling box 2.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An online monitoring system for grease metal particles in the main bearing of a wind turbine generator, characterized in that: It includes an oil diversion mechanism (1), an oil sampling box (2), a heating mechanism (3), an online monitoring device (4), a waste oil tank (5), a real-time signal processing module, a data analysis and processing module, and a human-machine interaction terminal. A valve is provided on the channel connecting the oil diversion mechanism (1) and the oil sampling box (2). The grease guiding mechanism (1) is placed at the low point of the partition (12) between the bearing seat (9) and the oil return chamber (10) of the main bearing (7) to guide the grease that has passed through the bearing raceway into the grease sampling box (2). The heating mechanism (3) is used to heat the grease in the grease sampling box (2) to reduce the viscosity of the grease; The waste oil tank (5) is used to recycle waste lubricating grease after testing; The online monitoring device (4) is connected downstream of the grease sampling box (2) and detects the content of magnetic metal particles in the grease based on the inductive principle, and uploads the collected signal to the real-time signal processing module. The real-time signal processing module uploads the processed signal to the data analysis and processing module for analysis and processing, assesses the health status of the bearing, and displays it through the human-machine interface terminal.

2. The system according to claim 1, characterized in that: The heating mechanism (3) is installed and fixed at the bottom of the grease sampling box (2).

3. The system according to claim 1, characterized in that: The grease guiding mechanism (1) is equipped with a millimeter-level filter screen (1.1). The lower part of the filter screen (1.1) is connected to a conical guide groove (1.2). The lower pipe diameter is ≥30mm. The pipe is equipped with a valve and flow sensor I (1.3) adapted to high viscosity grease. The pipe of the grease guiding mechanism (1) passes through the cover plate I (13) of the oil return chamber (10). One end of the pipe is connected to the bearing seat (9) by bolts; the other end is connected to the grease sampling box (2) by flange. Both ends of the pipe are provided with heat insulation layer and shock-absorbing rubber pad. The gap of the cover plate I (13) is coated with a flat sealing adhesive layer.

4. The system according to claim 1, characterized in that: The grease sampling box (2) is equipped with an exhaust valve I (2.1) at the top and a valve at the bottom, and is fitted with a temperature sensor (2.2) inside. The temperature sensor (2.2) is connected to the heating mechanism (3) by signal, and controls the start and stop of the heating mechanism (3) through the temperature threshold to ensure that the viscosity of the grease is reduced to the preset fluidity requirement.

5. The system according to claim 2, characterized in that: The heating mechanism (3) includes a housing (3.1), an electric heater (3.2), and a support frame (3.3). The box body (3.1) is welded or attached to the lower part of the oil sampling box (2). The electric heater (3.2) is fixed to the box body (3.1) by the support frame (3.3). The electric heater (3.2) adopts a ring-shaped double-layer heating tube (3.4) and is fitted with heat sink. The rated power is 100W~2000W. The heating tube (3.4) and heat sink are placed in high boiling point heat transfer oil. The heating mechanism (3) is equipped with an exhaust valve II (3.5) on its upper part, which is used to maintain the internal pressure balance under cold and hot conditions.

6. The system according to claim 1, characterized in that: The online monitoring device (4) includes a coil (4.1), a support frame (4.2), thermally conductive adhesive (4.3), a flow sensor II (4.4), a grease pipe (4.5), a housing (4.6), and a housing cover plate (4.7). The coil (4.1) is wound with rectangular electromagnetic wire of polyimide or polyester film, and the space between the coil (4.1) and the outer shell (4.6) is filled with insulating thermally conductive adhesive (4.3). The outer shell (4.6) and the shell cover (4.7) are made of copper sleeve, aluminum alloy or steel plate material, and the gap between them and the coil (4.1) is not less than twice the diameter of the grease tube (4.5); The grease tube (4.5) is made of polytetrafluoroethylene or alumina ceramic material; Flow sensor II (4.4) is installed on the grease pipe (4.5) to monitor whether grease enters the monitoring equipment and whether the grease in the grease sampling box (2) is emptied; The coil (4.1) is supplied with a high-frequency alternating current of 50~1000Hz. The change in current caused by the change in magnetic flux is detected by the current detection module, and the real-time content of magnetic metal particles is calculated.

7. The system according to claim 1, characterized in that: The waste oil tank (5) is equipped with a liquid level sensor (5.1) for monitoring the waste grease level; The real-time signal processing module is used to filter the detection signal and remove outliers. The data analysis and processing module connects the data processed by the real-time signal processing module to the main control and centralized control system of the whole machine for storage and analysis. When an abnormality in the lubricating grease is detected, it automatically sends a grease injection strategy adjustment command to the actuator of the automatic lubrication system.

8. A method for online monitoring of grease metal particles in the main bearing of a wind turbine generator, characterized in that, Includes the following steps: S1. The grease that passes through the bearing raceway is drawn out by the grease guiding mechanism (1) placed at the low point of the partition plate (12) between the main bearing (7) bearing seat (9) and the oil return chamber (10). The grease guiding mechanism (1) is equipped with a millimeter-level filter screen (1.1) and a conical guide groove (1.2). The diameter of the lower pipe is ≥30mm. S2. Open the valve between the grease guiding mechanism (1) and the grease sampling box (2). After the flow sensor I (1.3) detects that the amount of grease has reached the preset value, close the valve so that the grease remains in the grease sampling box (2). S3. Start the heating mechanism (3) at the bottom of the grease sampling box (2) to heat the grease in the box (3.1). Use the temperature sensor (2.2) to monitor the grease temperature in real time. When the temperature reaches the preset threshold and the grease viscosity decreases to the preset fluidity requirement, turn off the heating mechanism (3). S4. Open the valve at the bottom of the grease sampling box (2). When the flow sensor II (4.4) of the online monitoring device (4) detects that the flow rate of the lubricating grease meets the detection requirements, start the online monitoring device (4). The magnetic field is generated by the coil (4.1) which is supplied with a high frequency AC current of 50~1000Hz. The change in current of the coil (4.1) caused by the magnetic metal particles is detected, and the real-time content of the magnetic metal particles is calculated. S5. The detection signal is filtered and out of abnormal values ​​are removed by the real-time signal processing module. After being stored and analyzed by the data analysis and processing module, the health status of the main bearing (7) is evaluated and displayed through the human-machine interaction terminal.

9. The method according to claim 8, characterized in that: When an abnormal content of magnetic metal particles in the grease is detected in step S5, an instruction is given to the automatic lubrication system actuator to adjust the grease injection cycle and the amount of grease injected; the waste grease after detection is discharged into the waste oil tank (5) for recycling.

10. The method according to claim 8, characterized in that: In step S1, the pipe of the grease guiding mechanism (1) passes through the cover plate I (13) of the oil return chamber (10). The pipe ends are provided with heat insulation layer and shock-absorbing rubber pads, and the gap of the cover plate I (13) is coated with flat sealant.

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