A simulation test bench for unloading the main shaft bearing of a wind turbine

Abstract

This utility model relates to the field of wind turbine technology, specifically a simulation test bench for unloading the main shaft bearing of a wind turbine. It includes a main shaft passing through a front bearing bracket and a rear bearing bracket, on which front and rear bearings are mounted. A servo motor and a pressure sensor are respectively installed at both ends of the main shaft. The front and rear bearing brackets are sealed by end caps. An inner ring top sleeve and an outer ring top sleeve are provided inside the front bearing end cap. A thrust screw is located on the side of the front bearing bracket near the reducer, with the end of the thrust screw pressing against the inner ring of the thrust bearing. This test bench innovatively integrates independently controllable bearing inner ring unloading units and outer ring unloading units. Under the condition of main shaft rotation and bearing a set axial load, the unloading force of the inner or outer ring can be activated individually or in combination. The end sensor directly captures the changes in the axial force of the main shaft under different unloading modes, thus achieving for the first time a precise quantification and comparative analysis of the efficiency of the unloading device on the inner and outer ring paths.

Description

Technical Field

[0001] This utility model relates to the field of wind turbine technology, specifically a simulation test bench for unloading the main shaft bearing of a wind turbine. This test bench is used for the operation, maintenance and technical transformation of wind turbine units. Background Technology

[0002] During wind turbine operation, the enormous axial thrust of the main shaft system is primarily borne by the rear bearing, causing it to operate under extreme stress for extended periods. This leads to accelerated wear, significantly shortened lifespan, and makes it a weak link and frequent failure point in the transmission chain. To alleviate this problem, the industry commonly employs bearing unloading devices, which actively apply a reverse force to distribute the axial load on the rear bearing, theoretically extending its service life. However, the design and application of existing unloading devices have significant limitations. Due to the lack of a dedicated testing platform, the efficiency of unloading force transmission between the inner and outer rings of the bearing, the actual load reduction effect under different operating conditions, and the comparison of the advantages and disadvantages of inner and outer ring unloading strategies cannot be quantitatively verified experimentally. Existing unloading devices can only estimate the unloading effect based on theoretical models or whole-machine finite element simulations, often resulting in problems such as unreasonable unloading force distribution, delayed response, or large force deviations after actual installation. This not only fails to effectively protect the rear bearing but may also introduce additional vibrations. Therefore, developing a dedicated test bench that can realistically simulate spindle rotation and axial load, and independently test the unloading performance of the inner and outer rings of the bearing, to provide reliable data support for the design optimization of the unloading device, has become an urgent technical requirement to solve the problem of short bearing life and improve the reliability of the fan.

[0003] The wind power industry currently faces a dual dilemma when testing main shaft bearing unloading devices: On the one hand, mainstream test benches can only simulate radial loads or static axial forces, and cannot dynamically reproduce the complex axial load spectrum of actual wind turbine operation under high-speed rotation of the main shaft. It is even more difficult to integrate unloading devices for collaborative testing, resulting in unloading performance verification deviating from real working conditions. On the other hand, the design of existing unloading devices relies entirely on theoretical calculations and computer simulations, and there is a lack of experimental platforms to quantify their actual effects. For example, the transmission efficiency of unloading force in the inner and outer rings of the bearing, the unloading response speed at different speeds, and the actual load reduction ratio are all unsupported by measured data. Utility Model Content

[0004] This invention addresses the shortcomings of existing technologies by proposing a simulation test bench for unloading wind turbine main shaft bearings. This bench is used to simulate the main shaft system of a wind turbine under axial load. It includes a main shaft system test device with independent unloading functions for the inner and outer rings of the bearing and a rear bearing force monitoring device. The test bench is specifically designed for the optimization, reliability testing, and fault diagnosis of the main shaft bearing and its matching unloading device.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a simulation test bench for unloading the main shaft bearing of a wind turbine, including a main shaft, a front bearing installed on one side of the main shaft axial direction, and a rear bearing installed on the other side of the main shaft axial direction;

[0006] The front bearing is installed in the front bearing housing, and the rear bearing is installed in the rear bearing housing.

[0007] The end of the main shaft near the front bearing bracket is connected in sequence to the reducer and the servo motor;

[0008] A pressure sensor is fixedly connected to the end of the main shaft away from the reducer;

[0009] The front bearing bracket and the rear bearing bracket are fixed on the base;

[0010] The front bearing end cap is tightly fitted onto the axial end face of the front bearing bracket;

[0011] The rear bearing end cap is tightly fitted onto the axial end face of the rear bearing bracket;

[0012] The front bearing end cover is provided with an inner ring top sleeve and an outer ring top sleeve. The side of the inner ring top sleeve abuts against the inner ring of the front bearing, and the outer ring top sleeve abuts against the outer ring of the front bearing.

[0013] The front bearing end cover is provided with a first unloading screw and a second unloading screw. The end of the first unloading screw abuts against the inner ring top sleeve, and the second unloading screw abuts against the outer ring top sleeve.

[0014] Thrust bearings are installed on the main shafts on both sides of the front bearing.

[0015] The front bearing bracket is provided with a thrust screw on the side near the reducer, and the end of the thrust screw is pressed against the inner ring of the thrust bearing.

[0016] This experimental platform addresses the issue of premature failure of the rear bearing due to excessive axial load in wind farm operation and maintenance. By accurately reproducing the main shaft rotation conditions and complex axial stress states in the laboratory, it provides a core verification platform for the following two key technologies:

[0017] First, the effectiveness of the bearing unloading device was quantified. Traditionally, the industry relies on theoretical models, which cannot directly measure the distribution of unloading force and the load reduction effect. This test bench innovatively designed independent unloading units for the inner and outer rings and equipped them with direct-measurement pressure sensors at the end of the spindle. For the first time, it outputs the change curve of the net axial force of the spindle under the action of the unloading device, thus providing data support for the optimization of unloading strategies. Second, accelerated life testing of a new type of high-reliability spindle bearing was conducted. Axial thrust was accurately simulated by manually tightening the set screw, and a coordinated load test was performed under the drive of a servo motor. This exposed potential defects in the bearing design and constructed a mapping model between the load spectrum and life.

[0018] This technology spans the entire chain from unloading device design and bearing failure analysis to transmission chain life extension strategies, filling the technical gap in dynamic simulation of axial load under rotating conditions and accurate measurement of unloading effect, and providing experimental-level data support for reducing wind turbine failure rate and operation and maintenance costs.

[0019] Furthermore, the main shaft is a stepped shaft, with its shoulder abutting against the inner ring of the front bearing.

[0020] Furthermore, the first unloading screw and the inner ring top sleeve are directly provided with a first disc spring, and the second unloading screw and the outer ring top sleeve are directly provided with a second disc spring.

[0021] Furthermore, the main shaft is provided with a rear bearing top sleeve, which abuts against the outer ring of the rear bearing.

[0022] Furthermore, the front bearing bracket is provided with a first clamping pin, which passes through the front bearing bracket and the inner ring top sleeve; a first disc spring is sleeved on the first clamping pin.

[0023] Furthermore, a second clamping pin is provided inside the front bearing bracket, and the second clamping pin passes through the front bearing bracket and the outer ring top sleeve;

[0024] A second disc spring is fitted onto the second clamping pin.

[0025] Compared with the prior art, the advantages of this utility model are:

[0026] This test bench addresses two key issues in the wind power industry: First, the difficulty in conveniently applying and quantifying axial loads under rotating conditions to simulate the actual stress on a wind turbine. This test bench innovatively incorporates a manually adjustable set screw loading mechanism at the front end of the main shaft. Operators can apply a controllable and stable axial thrust to the rotating main shaft without friction by precisely rotating the screw, achieving dynamic coupling between rotation and axial load. Furthermore, the loading process eliminates the risk of hydraulic oil contamination or electromagnetic interference. Combined with a high-precision pressure sensor directly connected to the end of the main shaft for real-time monitoring of the net axial force, it enables intuitive setting of the loading force. The system's design and verification significantly enhance the flexibility and purposefulness of testing. Secondly, addressing the challenge of separately evaluating the independent unloading effects of the inner and outer rings in bearing unloading technology research, this test bench innovatively integrates independently controllable inner and outer ring unloading units. Under the condition of spindle rotation and a set axial load, the unloading force of the inner or outer ring can be activated individually or in combination. End sensors directly capture changes in the axial force on the spindle under different unloading modes, thus achieving for the first time a precise quantification and comparative analysis of the efficiency of the unloading device along the inner and outer ring paths. This provides a direct and reliable experimental platform and data support for optimizing unloading device design, developing efficient unloading strategies, extending bearing life, and reducing fan failure rates. Attached Figure Description

[0027] Figure 1 A schematic diagram of the internal structure of the simulation test bench for unloading the main shaft bearing of the fan provided by this utility model;

[0028] Figure 2 A top view of the simulation test bench for unloading the main shaft bearing of the fan provided by this utility model;

[0029] Figure 3 for Figure 1 A partial enlarged view; in which: servo motor 1, reducer 2, front bearing bracket 3, front bearing end cover 4, base 5, rear bearing bracket 6, rear bearing end cover 7, thrust screw 8, clamping ring 9, thrust bearing 10, front bearing 11, outer ring top sleeve 12, inner ring top sleeve 13, first disc spring 14, first unloading screw 15, first clamping pin 16, rear bearing 17, rear bearing top sleeve 18, pressure sensor 19, spindle 20, second unloading screw 21, second clamping pin 22, second disc spring 23. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] like Figures 1-3 As shown, this embodiment provides a simulation test bench for unloading the main shaft bearing of a wind turbine, including a main shaft 20. A front bearing 11 is installed on one axial side of the main shaft 20, and a rear bearing 17 is installed on the other axial side of the main shaft 20. The front bearing 11 and the rear bearing 17 jointly support the rotation of the main shaft 20. The front bearing 11 bears the main radial force, and the rear bearing 17 bears all the axial and radial forces. The two work together to simulate the wear scenario in which the rear bearing in a wind turbine bears all the axial forces, providing a core force object for unloading effect testing.

[0032] The front bearing 11 is installed in the front bearing bracket 3, and the rear bearing 17 is installed in the rear bearing bracket 6. The front bearing bracket 3 and the rear bearing bracket 6 are fixed to the base 5 by high-strength bolts, forming a double support system for the main shaft 20. The bearing seat holes are precision machined inside to position and install the front bearing 11 and the rear bearing 17, and axial constraint is achieved by the end cover. The front bearing bracket 3 integrates the unloading device interface, and the rear bearing bracket 6 is designed with sensor mounting positions, forming a critical path carrier for load transmission.

[0033] The main shaft 20 serves as the core power transmission and load-bearing component. It passes through the center of the front bearing housing 3 and the rear bearing housing 6. The end of the main shaft 20 closest to the front bearing housing 3 is connected sequentially to the reducer 2 and the servo motor 1. The servo motor 1 drives the output shaft of the reducer 2 via a coupling, with the output end directly connected to the main shaft 20, providing rotational torque. The reducer 2 increases torque and reduces speed fluctuations, ensuring the main shaft maintains speed stability during axial loading and unloading tests. A pressure sensor 19 is fixedly connected to the end of the main shaft 20 furthest from the reducer 2. A high-precision diaphragm-type pressure sensor is rigidly connected to the end of the main shaft 20, directly measuring the net axial force transmitted by the main shaft 20. Its real-time data output is the core basis for quantifying unloading efficiency.

[0034] The front bearing bracket 3 and the rear bearing bracket 6 are fixed on the base 5. The base 5 serves as the basic support platform for the test bench. The base 5 bears all the core components. Its high-rigidity structural design ensures that vibration transmission is suppressed under high-speed rotation and axial loading conditions, providing a stable mechanical environment for precision testing. At the same time, it reserves standardized interfaces to realize modular assembly.

[0035] A front bearing end cover 4 is fastened to the axial end face of the front bearing housing 3; a rear bearing end cover 7 is fastened to the axial end face of the rear bearing housing 6; a rear bearing top sleeve 18 is provided on the main shaft 20, and the rear bearing top sleeve 18 abuts against the outer ring of the rear bearing 17; the front bearing end cover 4 and the rear bearing end cover 7 are pressed onto the end face of the bearing housing by bolts to realize the axial preload function, accurately control the bearing clearance, prevent grease leakage and external impurities from entering, limit the axial displacement of the bearing outer ring, and ensure that the unloading force transmission path is controllable;

[0036] The front bearing end cover 4 is provided with an inner ring top sleeve 13 and an outer ring top sleeve 12. The inner ring top sleeve 13 abuts against the inner ring of the front bearing 11, and the outer ring top sleeve 12 abuts against the outer ring of the front bearing 11.

[0037] The front bearing end cover 4 is provided with a first unloading screw 15 and a second unloading screw 21. The end of the first unloading screw 15 abuts against the inner ring top sleeve 13, and the second unloading screw 21 abuts against the outer ring top sleeve 12.

[0038] Thrust bearings 10 are mounted on the main shafts 20 on both sides of the front bearing 11. A thrust screw 8 is provided on the side of the front bearing bracket 3 near the reducer 2. A clamping ring 9 is provided between the thrust screw 8 and the thrust bearing 10. The end of the thrust screw 8 is pressed against the thrust clamping ring 9. The thrust bearing 10 is installed between the front end of the main shaft 20 and the thrust screw 8, and between the inner ring top sleeve 13 of the unloading device and the inner ring of the front bearing 11. The manually screwed thrust screw 8 is located at the front end of the main shaft. Its flat head is pressed against the inner ring of the thrust bearing 10. The axial thrust of the thrust screw 8 is transmitted to the main shaft 20 by adjusting the advance amount through the precision thread, and the set axial load is applied to the rotating main shaft 20. The load force value is calibrated in real time by the end pressure sensor 19. The thrust bearing 10 avoids mechanical interference between the rotating main shaft and the thrust screw 8 during manual adjustment, and at the same time reduces transmission loss and ensures accurate introduction of the load force.

[0039] Servo motor 1 drives spindle 20 to rotate, simulating the rotation of a wind turbine. By manually tightening the thrust screw 8 at the front end of spindle 20, the axial load is transmitted to spindle 20 via thrust bearing 10, simulating the axial wind load during wind turbine operation. At this time, the axial force on spindle 20 is transmitted to rear bearing bracket 6 through rear bearing 17, and the initial load value is monitored in real time by pressure sensor 19 at the end of spindle. When it is necessary to test the unloading effect, the first unloading screw 15 and the second unloading screw 21 are rotated separately or simultaneously, pushing the corresponding inner ring top sleeve 13 to press against the inner ring of the front bearing 11. The outer ring end face and the outer ring top sleeve 12 press against the outer ring end face of the front bearing 11, and apply a reverse axial force to the front bearing 11 under the buffer of the disc spring. The clamping pin restricts the top sleeve to move only axially to prevent torsion. The unloading force directly offsets part of the axial load of the main shaft, resulting in a decrease in the net axial resultant force displayed by the pressure sensor 19. By comparing the sensor data before and after unloading, the actual efficiency of independent or coordinated unloading of the inner and outer rings can be accurately quantified. This direct measurement method eliminates the signal transmission distortion of the bearing housing, and makes the quantification of unloading efficiency free from indirect speculation, providing experimental basis for extending the life of the fan bearing.

[0040] In another embodiment of this application, the main shaft 20 is a stepped shaft, with its shoulder abutting against the inner ring of the front bearing 11. The stepped shaft structure design achieves three functions: front shoulder positioning: abutting against the inner ring of the front bearing 11, bearing the axial load transmitted by the thrust screw 8 through the thrust bearing; mid-section torque transmission: the surface is finely ground to ensure an interference fit with the inner ring of the bearing, transmitting torque and composite stress to the bearing during rotation; end sensing interface: the tail flange or threaded structure is rigidly connected to the pressure sensor 19, ensuring that the axial force is transmitted to the measurement unit without loss. The main shaft 20 integrates rotation drive, axial loading, unloading force transmission and real-time measurement into one unit, and is the core carrier for simulating the stress state of the wind turbine main shaft and verifying the unloading effect.

[0041] In another embodiment of this application, a first disc spring 14 is provided between the first unloading screw 15 and the inner ring top sleeve 13, and a second disc spring 23 is provided between the second unloading screw 21 and the outer ring top sleeve 12. Rotating the inner ring first unloading screw 15 pushes the inner ring top sleeve 13 to compress the first disc spring 14, so that the inner ring top sleeve 13 directly presses against the inner ring end face of the thrust bearing 10 to apply axial unloading force. Simultaneously or independently rotating the second unloading screw 21 drives the outer ring top sleeve 12 to squeeze the outer ring end face of the front bearing 11. The pressure is kept stable by the second disc spring 23. The disc spring continuously absorbs vibration under rotational load, ensuring that the manually applied unloading force is smoothly transmitted and ensuring data repeatability.

[0042] In another embodiment of this application, a first clamping pin 16 is provided in the front bearing bracket 3, the first clamping pin 16 passes through the front bearing bracket 3 and the inner ring top sleeve 13; a first disc spring 14 is sleeved on the first clamping pin 16.

[0043] The front bearing bracket 3 is provided with a second clamping pin 22, which passes through the front bearing bracket 3 and the outer ring top sleeve 12; a second disc spring 23 is sleeved on the second clamping pin 22.

[0044] The first clamping pin 16 passes through the pin hole on the inner ring top sleeve 13 and the front bearing bracket 3, and the second clamping pin 22 passes through the pin hole on the outer ring top sleeve 12 and the front bearing bracket 3. This forcibly constrains the inner ring top sleeve 13 and the outer ring top sleeve 12 to move only axially and prohibits circumferential rotation. This ensures that the torque of manually rotating the thrust screw 8 is accurately converted into pure axial thrust. Finally, the pressure sensor 19 at the end of the spindle captures the reduction effect of the unloading force on the net axial load in real time, forming a closed-loop mechanical force transmission chain of "thrust screw rotation - top sleeve displacement - disc spring energy storage - bearing force - sensor feedback".

[0045] Work process:

[0046] 1. Simulate the axial load on the wind turbine.

[0047] Start the servo motor 1 to drive the spindle 20 to the set speed to simulate the rotation of the wind turbine. Manually tighten the thrust screw 8 at the front end of the spindle 20. The pushing force of the thrust screw 8 is converted into a pure axial load through the front thrust bearing 10 and transmitted to the rotating spindle 20. The screw depth of the thrust screw 8 is controlled by the precision thread to apply the target axial force to the spindle 20. At this time, the pressure sensor 19 at the end of the spindle 20 displays the load value in real time. The thrust screw 8 is finely adjusted until the reading of the pressure sensor 19 stabilizes at the target value, thus completing the simulation of the working condition load.

[0048] 2. Provides axial unloading force

[0049] Rotating the first unloading screw 15 and the second unloading screw 21 pushes the inner ring top sleeve 13 and the outer ring top sleeve 12 to move axially. The top sleeve compresses the disc spring assembly and presses against the end faces of the inner and outer rings of the front bearing 11, applying a reverse thrust to the inner and outer rings of the front bearing 11. The first clamping pin 16 and the second clamping pin 22 penetrate the inner ring top sleeve 13, the outer ring top sleeve 12 and the bearing bracket, forcibly restricting the inner ring top sleeve 13 and the outer ring top sleeve 12 to only axial displacement, ensuring that the rotation angle of the first unloading screw 15 and the second unloading screw 21 is accurately converted into unloading force.

[0050] 3. Observation data

[0051] After the unloading force is applied, the pressure sensor 19 directly connected to the end of the spindle 20 captures the change in net axial net force in real time. Single-path test: when the inner ring is unloaded alone, the decrease in the reading of the pressure sensor 19 is the contribution of the inner ring unloading. Dual-path test: when the first unloading screw 15 and the second unloading screw 21 are rotated synchronously, the pressure sensor 19 shows a further reduction in net force, reflecting the synergistic effect. Based on the rotation angle of the first unloading screw 15 and the second unloading screw 21 and the decrease in net force, the unloading efficiency per unit angle is calculated, and the "unloading force - net load" relationship curve is plotted. During the continuous rotation of the spindle 20, the stability of the data from the pressure sensor 19 verifies the effectiveness of the disc spring assembly in absorbing vibration.

[0052] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A simulation test bench for unloading of a main shaft bearing of a fan, characterized in that: include A spindle (20) is provided with a front bearing (11) mounted on one side of the spindle (20) and a rear bearing (17) mounted on the other side of the spindle (20). The front bearing (11) is installed in the front bearing bracket (3), and the rear bearing (17) is installed in the rear bearing bracket (6); The end of the main shaft (20) near the front bearing bracket (3) is connected in sequence to the reducer (2) and the servo motor (1); A pressure sensor (19) is fixedly connected to the end of the main shaft (20) away from the reducer (2); The front bearing bracket (3) and the rear bearing bracket (6) are fixed on the base (5); The front bearing end cap (4) is tightly fastened to the axial end face of the front bearing bracket (3); The rear bearing end cap (7) is tightly fitted onto the axial end face of the rear bearing bracket (6); The front bearing end cover (4) is provided with an inner ring top sleeve (13) and an outer ring top sleeve (12). The inner ring top sleeve (13) abuts against the inner ring of the front bearing (11) on its side, and the outer ring top sleeve (12) abuts against the outer ring of the front bearing (11). The front bearing end cover (4) is provided with a first unloading screw (15) and a second unloading screw (21). The end of the first unloading screw (15) abuts against the inner ring top sleeve (13), and the second unloading screw (21) abuts against the outer ring top sleeve (12). Thrust bearings (10) are installed on the main shafts (20) on both sides of the front bearing (11); The front bearing bracket (3) is provided with a thrust screw (8) on the side near the reducer (2), and the end of the thrust screw (8) is pressed against the inner ring of the thrust bearing (10).

2. The test bench for simulating the unloading of the main shaft bearing of a fan according to claim 1, characterized in that: The main shaft (20) is a stepped shaft, and its shoulder abuts against the inner ring of the front bearing (11).

3. The test rig for simulating the unloading of a main shaft bearing of a fan according to claim 1, characterized in that: A first disc spring (14) is provided between the first unloading screw (15) and the inner ring top sleeve (13), and a second disc spring (23) is provided between the second unloading screw (21) and the outer ring top sleeve (12).

4. The test bench for simulating the unloading of the main shaft bearing of a fan according to claim 1, characterized in that: The main shaft (20) is provided with a rear bearing top sleeve (18), which abuts against the outer ring of the rear bearing (17).

5. The test rig for simulating the unloading of a main shaft bearing of a fan according to claim 3, characterized in that: The front bearing bracket (3) is provided with a first clamping pin (16), which passes through the front bearing bracket (3) and the inner ring top sleeve (13); a first disc spring (14) is sleeved on the first clamping pin (16).

6. The test bench for simulating the unloading of the main shaft bearing of a fan according to claim 3, characterized in that: The front bearing bracket (3) is provided with a second clamping pin (22), which passes through the front bearing bracket (3) and the outer ring top sleeve (12); a second disc spring (23) is sleeved on the second clamping pin (22).

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