Device for detecting the load deviation of a toothed belt and method for detecting the load deviation of a toothed belt

Abstract

The present disclosure provides a toothed belt load deviation detection device and a method for detecting the load deviation degree of a toothed belt. The two ends of the toothed belt are fixed on a pitch bearing to drive the pitch bearing to rotate. The toothed belt load deviation detection device comprises: at least two flexible filament elements, which are detachably arranged on the two side edges of a first surface of the toothed belt, the first surface facing the pitch bearing; a thickness measuring element for measuring the thickness of the compressed part of the at least two flexible filament elements on the first surface when the pitch bearing rotates by a predetermined angle and remains for a predetermined time; and a processor for determining the tensile stress difference of the two side edges of the toothed belt according to the thickness, and determining the load deviation degree of the toothed belt according to the tensile stress difference.

Description

Technical Field

[0001] This disclosure relates to the field of detection technology, specifically to a toothed belt off-center load detection device and a method for detecting the degree of off-center load on a toothed belt. Background Technology

[0002] In wind power pitch technology, the synchronous toothed belt pitch method uses an open toothed belt to transmit the driving force of the power mechanism. A power unit (e.g., a motor and a reducer) drives a pinion, which in turn drives the toothed belt (which can be called a synchronous toothed belt or a flexible synchronous belt) to rotate. The two ends of the synchronous toothed belt are fixed to the pitch bearing, thereby driving the blades on the pitch bearing to rotate and realize the change of the blade pitch angle. It has the advantages of stable output torque and maintenance-free operation.

[0003] As wind turbines become larger, the load on the pitch system increases accordingly, necessitating improvements in the load-bearing capacity of the toothed belt. This is primarily achieved by increasing the belt width to enhance its tensile strength. Statistical analysis of toothed belt fracture failures reveals that the probability of lateral fracture increases with the width of the toothed belt. Furthermore, once the toothed belt reaches a certain width, the occurrence of lateral fracture is positively correlated with its width.

[0004] Whether the toothed belt fails due to misalignment during assembly or excessive wear of the pulley bearings, identifying the resulting breakage is difficult, posing a significant challenge to on-site maintenance. Therefore, a method is urgently needed to accurately detect the stress distribution or off-center loading of the toothed belt during routine maintenance, providing robust data support for its maintenance. Summary of the Invention

[0005] The purpose of this disclosure is to provide a toothed belt off-center load detection device and a method for detecting the degree of toothed belt off-center load, which can accurately detect the toothed belt off-center load during the regular maintenance of the pitch system, and at least partially overcome the shortcomings of the prior art.

[0006] According to embodiments of this disclosure, a toothed belt off-center load detection device is provided. The two ends of the toothed belt are fixed to a pitch bearing to drive the pitch bearing to rotate. The device includes: at least two flexible filamentary elements detachably disposed on both sides of a first surface of the toothed belt, the first surface facing the pitch bearing; a thickness measuring element for measuring the thickness of the compressed portion of the at least two flexible filamentary elements on the first surface when the pitch bearing rotates at a predetermined angle and is held for a predetermined time; and a processor for determining the tensile stress difference between the two sides of the toothed belt based on the thickness, and determining the degree of off-center load of the toothed belt based on the tensile stress difference.

[0007] According to another embodiment of this disclosure, a method for detecting the degree of off-center loading of a toothed belt using the toothed belt off-center loading detection device as described above is provided. The method includes: detachably disposing at least two flexible filamentary elements on both sides of a first surface of the toothed belt, wherein the first surface faces the pitch bearing; measuring the thickness of the compressed portion of the at least two flexible filamentary elements on the first surface when the pitch bearing rotates a predetermined angle and remains there for a predetermined time; determining the tensile stress difference between the two sides of the toothed belt based on the thickness; and determining the degree of off-center loading of the toothed belt based on the tensile stress difference.

[0008] By employing the toothed belt off-center load detection device and method for detecting the degree of off-center load of the toothed belt according to embodiments of the present disclosure, at least one of the following technical effects can be achieved: by setting flexible filamentary elements on the toothed belt, the force distribution of the toothed belt can be detected, the degree of off-center load of the toothed belt can be determined, and the operating status of the pitch transmission system can be diagnosed to ensure the maximum life of the toothed belt; the technical solution proposed in this disclosure is well applicable to on-site wind turbine maintenance, has important reference value for guiding pitch system maintenance and preliminary fault diagnosis, and is of great significance for improving the life of the toothed belt; the technical solution proposed in this disclosure has the advantages of flexible and convenient use, high accuracy, and is a non-destructive testing method, which is suitable for actual production. Attached Figure Description

[0009] The above and other objects and features of this disclosure will become clearer from the following description taken in conjunction with the accompanying drawings.

[0010] Figure 1 This is a schematic diagram of the installation of the toothed belt according to an embodiment of the present disclosure;

[0011] Figure 2 and Figure 3 This is a planar mounting schematic diagram of a flexible filamentary element and a stress measuring element disposed on a toothed belt according to an embodiment of the present disclosure;

[0012] Figure 4 This is a three-dimensional mounting diagram of a flexible filamentary element and a stress measuring element disposed on a toothed belt according to an embodiment of the present disclosure;

[0013] Figure 5 This is a block diagram of a toothed belt off-center load detection device according to an embodiment of the present disclosure;

[0014] Figure 6 This is a flowchart of a method for detecting the degree of off-center loading of a toothed belt according to an embodiment of the present disclosure;

[0015] Figure 7 This is another flowchart of a method for detecting the degree of off-center loading of a toothed belt according to an embodiment of the present disclosure;

[0016] Figure 8This is another flowchart of a method for detecting the degree of off-center loading of a toothed belt according to an embodiment of the present disclosure. Detailed Implementation

[0017] In wind power pitch control technology, synchronous toothed belt pitch control can be used to perform pitch control. For example... Figure 1 As shown, Figure 1 This is a schematic diagram of the installation of a toothed belt according to an embodiment of the present disclosure. The two ends of the toothed belt 1 are fixed to the pitch bearing 2 to drive the pitch bearing 2 to rotate. The toothed belt 1, which meshes with the pitch bearing 2, can be driven by the drive wheel 3 and the tension wheel 4, causing the toothed belt 1 to drive the pitch bearing 2 to rotate, thereby causing the blades on the pitch bearing 2 to rotate.

[0018] Toothed belt fracture failure is usually caused by uneven stress within the cross-section. The tearing begins on the side of the toothed belt with the highest tensile strength and extends across the entire width of the belt. Fatigue in the area of ​​excessive localized stress at the tooth root ultimately leads to premature failure of the toothed belt, posing significant challenges to its maintenance. Currently, when a toothed belt fractures, few people carefully inspect the pulley; it is usually assumed to be a problem with the toothed belt itself.

[0019] Based on the on-site investigation, the cause of the toothed belt's eccentric load fracture was identified. Firstly, during installation, there were assembly gaps between the pre-tensioning device (e.g., base and pressure plate), the toothed belt, and the pitch bearing. This led to varying degrees of assembly errors by different personnel, affecting the uniformity of stress on the toothed belt. Secondly, during long-term operation, the pulley bearings (e.g., drive pulley, tension pulley) experienced wear. For example, the bearings at both ends of the pulley shaft might have different wear levels, resulting in excessive radial clearance at one end. This caused the pulley shaft's parallelism to exceed tolerances, meaning the drive pulley or tension pulley shaft was not parallel to the pitch bearing axis. Consequently, there was uneven stress distribution within the toothed belt's cross-section. One side of the toothed belt experienced excessive stress, while the other side experienced less stress. When the stress on the side with higher stress exceeded the ultimate stress, fatigue fracture of the toothed belt occurred. Both improper assembly and excessive wear of the pulley bearings can cause toothed belt fracture failure, which is difficult to identify.

[0020] In past transmission systems, the toothed belts were relatively narrow, so the load distribution within the cross-section of the toothed belt received little attention or research from those skilled in the art. Currently, only the tension of the toothed belt is measured, and methods and tools for detecting uneven loading are lacking. With the application of ultra-wide synchronous toothed belts in wind turbine pitch systems, the requirements for the performance of the toothed belt (especially in terms of load uniformity) are much higher. As the service life of the unit increases, the frequency of toothed belt fractures also gradually increases. Investigations have shown that almost all toothed belt fractures are caused by uneven loading, making the detection of the uniformity of stress on the toothed belt particularly important.

[0021] For example, in a belt drive system, non-parallel pulley shafts cause uneven stress on the toothed belt across its cross-section, resulting in a greater tension on one side than the other, creating a tension difference. Different degrees of wear or damage to the bearings on both sides of the pulley (e.g., the upper and lower bearings) cause differences in the direction and angle of the pulley shaft's tilt. For instance, in one scenario, if the upper bearing is more worn than the lower bearing, the upper end of the pulley shaft will tilt to one side (e.g., the left), gradually increasing the load or force along the width of the toothed belt from top to bottom, meaning the tension on the upper side is less than the tension on the lower side. In another scenario, if the lower bearing is more worn than the upper bearing, the lower end of the pulley shaft will tilt to one side (e.g., the left), gradually increasing the load or force along the width of the toothed belt from bottom to top, again with less tension on the lower side than the upper side. Therefore, by measuring the tension on both sides of the toothed belt, the stress distribution within its cross-section can be assessed.

[0022] The tension of a toothed belt can be calculated by measuring its frequency using a tension tester. However, due to variations in individual operating methods, the frequency of the toothed belt can deviate significantly, making it impossible to accurately measure the tension deviation on both sides of the belt. Therefore, it is difficult to detect uneven stress on the toothed belt using a tension tester, and this electronic instrument is not suitable for practical applications such as low-temperature environments.

[0023] There is an urgent need for a reliable technology to detect whether the forces on both sides of the toothed belt are consistent and to accurately identify the eccentric loading of the toothed belt.

[0024] This disclosure presents a toothed belt off-center load detection device and a method for detecting the degree of off-center load on the toothed belt. The technical solution proposed in this disclosure can accurately detect the stress distribution or off-center load of the toothed belt during the regular maintenance of the pitch system, providing strong data support for toothed belt maintenance.

[0025] The technical solution proposed in this disclosure can identify the force distribution within the cross-section of the toothed belt and assess the degree of eccentric loading. If there is uneven force distribution, the test results can guide on-site maintenance personnel to take corrective measures for the uneven force distribution, provide a reliable basis for developing detailed maintenance plans, take practical measures to extend the life of the toothed belt, and avoid the damage caused by fatigue fracture of the toothed belt.

[0026] The following description, in conjunction with the accompanying drawings, provides specific embodiments to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, upon understanding this disclosure, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will become apparent. For example, the order of operations described herein is merely illustrative and is not limited to those orders set forth herein, but may be altered as will become clear upon understanding this disclosure, except for operations that must occur in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0027] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein, which will become clear upon understanding the disclosure of this application.

[0028] As used herein, the term “and / or” includes any one of the associated listed items and any combination of any two or more.

[0029] Although terms such as “first,” “second,” and “third” may be used herein to describe various components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts should not be limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Thus, without departing from the teaching of the examples described herein, the first component, first assembly, first region, first layer, or first part referred to as the first component, first assembly, first region, first layer, or first part may also be referred to as the second component, second assembly, second region, second layer, or second part.

[0030] The terminology used herein is for the purpose of describing various examples only and is not intended to limit disclosure. Unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. The terms “comprising,” “including,” and “having” indicate the presence of the described features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0031] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains upon understanding this disclosure. Unless expressly defined herein, terms (such as those defined in a general dictionary) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field and in this disclosure, and shall not be interpreted in an idealized or overly formalistic manner.

[0032] Furthermore, in the description of the examples, detailed descriptions of well-known related structures or functions will be omitted when it is believed that such detailed descriptions would lead to a vague interpretation of this disclosure.

[0033] Figure 2 and Figure 3 This is a planar mounting schematic diagram of a flexible filamentary element and a stress measuring element disposed on a toothed belt according to an embodiment of the present disclosure. Figure 4 This is a three-dimensional mounting diagram of a flexible filamentary element and a stress measuring element disposed on a toothed belt according to an embodiment of the present disclosure. Figure 5 This is a block diagram of a toothed belt off-center load detection device according to an embodiment of the present disclosure.

[0034] like Figure 5 As shown, the toothed belt off-center load detection device 5 may include at least two flexible filament elements 51, a thickness measuring element 52, and a processor 53.

[0035] During the rotation of the pitch bearing, the toothed belt bears a significant tensile force. Due to the pulley wrap angle, each tooth of the toothed belt in contact with the outer ring of the pitch bearing exerts a certain amount of pressure on the bearing. Based on this characteristic, a flexible filament element 51 can be placed between the side of the toothed belt and the outer ring of the pitch bearing, causing it to deform under pressure. The deformation of the flexible filament element 51 is positively correlated with the magnitude of the applied pressure, and the pressure exerted by the side teeth on the flexible filament element 51 is proportional to the side tension of the toothed belt. Therefore, the detection of the side tension of the toothed belt can be transformed into the detection of the pressed thickness of the flexible filament element 51. Considering the influence of measurement factors and errors, calibration tests can be performed at several preload points of the toothed belt to accurately determine the quantitative relationship between the side tension of the toothed belt and the thickness of the compressed portion of the flexible filament element 51. Calibration tests can be performed on various models of toothed belts to ensure applicability for detecting the operating conditions of toothed belts on all aircraft models in the field. (Further details follow...) Figures 2 to 4 The calibration tests will be further described in the illustrated embodiments.

[0036] At least two flexible filamentary elements 51 are detachably disposed on both sides of a first surface of the toothed belt, wherein the first surface faces the pitch bearing. A thickness measuring element 52 is used to measure the thickness of the at least two flexible filamentary elements on the first surface under pressure when the pitch bearing rotates a predetermined angle and remains there for a predetermined time. A processor 53 is used to determine the tensile stress difference between the two sides of the toothed belt based on the thickness, and to determine the degree of off-center loading of the toothed belt based on the tensile stress difference.

[0037] According to embodiments of this disclosure, at least two flexible filamentary elements 51 are detachably disposed on one side near the drive wheel or one side near the tension wheel; however, this disclosure is not limited to this, and they may be disposed in other locations as needed. Lead wire may be used as the flexible filamentary element 51, but this disclosure is not limited to this, and other flexible filamentary elements 51 made of materials with good ductility and easy deformation may also be used. In embodiments of this disclosure, the pitch bearing rotates a predetermined angle and holds for a predetermined time, causing at least two flexible filamentary elements 51 to reach a stable state under pressure deformation.

[0038] The processor 53 can determine the first thickness and the second thickness corresponding to the two sides of the toothed strip, respectively, based on the thickness measured by the thickness measuring element 52; based on the first thickness and the second thickness, it queries a predetermined thickness-tensile stress mapping table to obtain the first tensile stress and the second tensile stress corresponding to the two sides of the toothed strip, respectively; based on the first tensile stress and the second tensile stress, it determines the tensile stress difference between the two sides of the toothed strip. In the embodiments of this disclosure, the thickness measuring element 52 can be implemented using high-precision thickness measuring tools such as vernier calipers and micrometers.

[0039] In embodiments of this disclosure, the first thickness may be the average thickness of the compressed portion of the flexible filament element on the first side of the toothed belt, and the second thickness may be the average thickness of the compressed portion of the flexible filament element on the second side of the toothed belt. However, this disclosure is not limited thereto, and the first thickness and the second thickness may be other statistical values ​​of the thickness of the compressed portion of the flexible filament element on the first and second sides of the toothed belt, respectively.

[0040] According to embodiments of this disclosure, the predetermined thickness-tensile stress mapping table can be calibrated using a stress measuring element, a thickness measuring element, and another processor. The following is in conjunction with... Figures 2 to 4 An exemplary description is provided.

[0041] In embodiments of this disclosure, stress measuring elements are detachably disposed on both sides of the second surface of the toothed belt and are used to measure multiple tensile stress measurements on both sides when a predetermined preload is applied to the toothed belt, with the second surface of the toothed belt facing away from the first surface. The stress measuring elements can be implemented using stress sensors or other components that are easy to install and remove, such as strain gauges. A thickness measuring element can be used to measure multiple thickness measurements at the compressed portions of the at least two flexible filamentary elements on the first surface when a predetermined preload is applied to the toothed belt. Another processor can be used to determine tensile stress calibration values ​​based on the multiple tensile stress measurements, determine thickness calibration values ​​based on the multiple thickness measurements, and determine the thickness-tensile stress mapping table based on the correspondence between the tensile stress calibration values ​​and the thickness calibration values.

[0042] like Figure 2 and Figure 3As shown, a flexible filamentary element that is detachably mounted on one side of the drive wheel 22 will be used as an example for illustration. Figure 2 A top view of the back of the toothed belt and a partial side view of the toothed belt are shown. Figure 3 This is a top view of the toothed strip segment AA. Figure 2 and Figure 3 In the example shown, the front side of the toothed belt represents the first surface of the toothed belt, facing the pitch bearing 21; the back side of the toothed belt represents the second surface of the toothed belt, facing away from the first surface and the pitch bearing 21. Figure 2 The dashed box in the image shows a partial side view of the toothed strip.

[0043] Lead wires 24, as flexible filamentary elements, can be symmetrically arranged on both sides of the front surface of the toothed belt in the width direction. For simplicity, only two lead wires 24 are shown here, but more lead wires can be arranged on both sides of the front surface of the toothed belt. In the width direction of the toothed belt, the distance between the center line of the lead wire 24 and the edge of the toothed belt is d1. Lead wires 24 can be arranged along the length direction of the toothed belt. The length of the lead wire 24 is L. In the length direction of the toothed belt, the shortest distance between the lead wire 24 and the axis of the drive wheel 22 is d2. Lead wires 24 are detachably arranged on the tooth tips of the front surface of the toothed belt.

[0044] To improve the accuracy of toothed belt off-center load detection, lead wires 24 are installed on both sides of the toothed belt, and these lead wires 24 are fixed close to the edges of the toothed belt. The distance d1 between the centerline of the lead wire 24 and the edge of the toothed belt can be set according to the width of the toothed belt; for example, the distance d1 can be set to a predetermined ratio (e.g., 0.1 times) of the toothed belt width. The shortest distance d2 between the lead wire 24 and the axis of the drive wheel 22 can be determined through testing to meet the practical application requirements when maintaining the toothed belt.

[0045] According to embodiments of this disclosure, the diameter of the lead wire 24 can be determined through testing to meet requirements such as significant compressive deformation effect, moderate deformation amount, and ease of measurement and analysis. The length L of the lead wire 24 can be set according to the width of the teeth of the toothed belt. For example, the sum of the widths of 2-3 teeth can be set as the length L so that the lead wire 24 can be rolled across 2-3 teeth.

[0046] The lead wire 24 can be glued to the top of the teeth of the toothed belt using adhesive or tape, or it can be bent into a certain shape and then clipped onto the top of the teeth of the toothed belt. The installation requirements for the lead wire 24 include: secure installation and easy disassembly; no deformation or breakage during disassembly.

[0047] Strain gauge 23, as a stress measuring element, can be symmetrically arranged on both sides of the back of the toothed belt and used to measure multiple tensile stress values ​​on both sides when a predetermined preload is applied to the toothed belt. Strain gauge 23 can be configured to be coaxial with lead wire 24 (i.e., the center lines of strain gauge 23 and lead wire 24 overlap in the thickness direction of the toothed belt), and the shortest distance between strain gauge 23 and lead wire 24 is d3.

[0048] By installing strain gauges 23 and lead wires 24 on the toothed belt, the thickness of the lead wires 24 pressed against both sides of the toothed belt under different preloads can be measured, thus determining the relationship between the lead wire thickness and the lateral tensile stress. Force analysis of the toothed belt shows that the thinner the lead wires 24 are compressed, the greater the pressure from the teeth, and therefore the greater the lateral tensile stress; conversely, the greater the compression, the smaller the lateral tensile stress. Strain gauges 23 can accurately measure the tensile stress on both sides of the toothed belt. Strain gauges 23 can output a signal indicating the tensile stress to an external stress display device for testing personnel to read the magnitude of the tensile stress. By installing strain gauges 23 and lead wires 24 on both sides of the toothed belt, calibration tests can be performed to provide sample data for calibration. Multiple calibrations can improve measurement accuracy and subsequent toothed belt off-center load detection accuracy.

[0049] In the embodiments of this disclosure, the tensile stress calibration value can be the average of the tensile stress measurements on both sides, and the thickness calibration value can be the average of the thicknesses of all compressed parts of the lead wire 24.

[0050] The following is combined with Figure 4 The calibration test process will be described in further detail.

[0051] like Figure 4 As shown, a preload device 32 is provided on the pitch bearing 31. The axial tension of the adjusting bolt of the preload device 32 can be set by the torque method, thereby enabling the toothed belt 33 to reach the set preload. That is, the set preload is transmitted to the toothed belt 33 through the adjusting bolt. First, the torque value of the adjusting bolt is obtained according to the bolt preload calculation method. Then, the torque of the torque wrench is set, and the adjusting bolt is tightened to the set preload using the torque wrench. This completes the preload adjustment of the toothed belt 33.

[0052] On the toothed belt 33, six lead wires 36 are arranged on one side near the drive wheel 37, that is, three pairs of lead wires 36 are arranged symmetrically. At the same time, two strain gauges 35 and a stress display device 34 connected to the strain gauges are also arranged accordingly.

[0053] For example, in the calibration test of a certain type of toothed belt 33 with lead wire 36, based on the rated preload T, the following preload T can be selected. nMeasurements were taken: T1 = 1.2T, T2 = 1.15T, T3 = 1.1T, T4 = 1.05T, T5 = T, T6 = 0.95T, T7 = 0.9T, T8 = 0.85T, T9 = 0.8T, T 10 =0.75T, the obtained tensile stress calibration value q n They are q1, q2, q3, q4, q5, q6, q7, q8, q9, and q 10 The corresponding thickness calibration value δ n They are δ1, δ2, δ3, δ4, δ5, δ6, δ7, δ8, δ9 and δ respectively. 10 However, this disclosure is not limited to this, and more or fewer calibration points can be used. In the calibration test, the toothed belt drives the pitch bearing 31 to rotate a predetermined angle α under each set preload and holds it for a predetermined time t (i.e., a set pressing time, for example, t can be 30s) to allow the lead wire 36 to reach a stable state under pressure deformation. The purpose of setting the predetermined angle α is to unify the rotation angle of the pitch bearing so that the lead wire is subjected to the pressure of the teeth at the same position. If the rotation angle is different, the wrap angle of the toothed belt on the pitch bearing and the position of the lead wire will be different, which will increase the measurement error. The predetermined time t and the predetermined angle α can be determined by on-site measurement tests. This invention exemplifies installing the lead wire on the toothed belt on the drive wheel side, but the lead wire can also be installed on the toothed belt on the tension wheel side, which will not be described in detail here.

[0054] The tensile stress calibration value q can be calculated using the following formula. n and thickness calibration value δ n .

[0055] δ n =(δ n上1 +δ n上2 +δ n上3 +δ n下1 +δ n下2 +δ n下3 ) / 6 (1)

[0056] q n =(q n上 +q n下 ) / twenty two)

[0057] Where n represents the preload T n The subscript number, δ n上1 δ n上2 δ n上3 δ represents the thickness of the compressed portion of the three lead wires located on the first side (e.g., the upper side) of the toothed belt. n下1 δ n下2 δ n下3q represents the thickness measurement of the compressed portion of the three lead wires located on the second side (e.g., the lower side) of the toothed belt. n上 q n下 These represent the tensile stress measurements of the first side (e.g., the upper side) and the second side (e.g., the lower side) of the toothed belt, respectively.

[0058] For example, after the lead wires are installed in the specified positions, the toothed belt drives the pitch bearing to rotate a predetermined angle under each set preload force, then stops rotating and holds for a predetermined time. During this time, the lead wires are pressed between the toothed belt and the outer ring of the pitch bearing. The pitch bearing holds the predetermined angle for a predetermined time, allowing the lead wires to reach a stable state under pressure deformation. Then, the pitch bearing is rotated in the opposite direction to a suitable angle, causing the lead wires to leave the pressure zone of the pitch bearing, and the lead wires on both sides can be removed from the toothed belt. The thickness of the compressed part of each lead wire is measured using a thickness measuring element, and the average value is taken. At the same time, the tensile stress values ​​on both sides are viewed on the stress display device and their average value is taken. The data are recorded in Table 1 below.

[0059] Through a series of measurement tests, the thickness of the pressed lead wire under different preloads of various types of toothed belts was calibrated, and the correspondence between the tensile stress calibration value and the thickness calibration value was established, which can be used as a reference value for on-site pitch system maintenance. According to the embodiments of this disclosure, a predetermined thickness-tensile stress mapping table can be determined based on the correspondence between the tensile stress calibration value and the thickness calibration value, as shown in Table 1 below.

[0060] Table 1: Mapping Table of Predetermined Thickness and Tensile Stress

[0061]

[0062] Furthermore, data analysis methods can be used to fit a curve showing the relationship between the obtained tensile stress calibration value and the thickness calibration value, thereby predicting the tensile stress data corresponding to the unknown thickness. A thickness-tensile stress mapping table can then be determined based on the fitted curve.

[0063] After completing the above calibration test, the degree of off-center loading of the toothed belt under test can be detected using a predetermined thickness-tensile stress mapping table. According to embodiments of this disclosure, the placement positions of at least two flexible filamentary elements during the calibration process can be the same as their placement positions during the detection of the off-center loading of the toothed belt. Therefore, the accuracy of detecting the off-center loading of the toothed belt can be improved.

[0064] When performing off-center load testing on the toothed belt, the test can be conducted under the aforementioned rated preload conditions. By measuring the thickness of the lead wire on both sides of the toothed belt and referring to a predetermined thickness-tensile stress mapping table, the tensile stress on each side can be obtained. This allows for the determination of the tensile stress difference between the two sides of the toothed belt, thus identifying the degree of off-center load. Referring to relevant standards or technical requirements for toothed belts, it should be determined whether the measured tensile stress difference is within the allowable range. If it exceeds the normal range, the off-center load problem should be analyzed and the cause identified as soon as possible to prevent excessive local stress on the toothed belt, which could lead to fatigue fracture or affect the lifespan of the transmission system.

[0065] According to embodiments of this disclosure, the degree of off-center loading of the toothed belt may include at least one of the following: slight off-center loading, moderate off-center loading, and heavy off-center loading. Accordingly, the processor in the toothed belt off-center loading detection device may be used to perform at least one of the following operations: determining that the toothed belt is under slight off-center loading in response to determining, based on the thickness (i.e., the thickness of the compressed portion of at least two flexible filamentary elements on the first surface when the pitch bearing rotates a predetermined angle and is held for a predetermined time), that the tensile stress difference between the two sides of the toothed belt is greater than zero and less than or equal to a first stress difference threshold; determining that the toothed belt is under moderate off-center loading in response to determining, based on the thickness, that the tensile stress difference between the two sides of the toothed belt is greater than the first stress difference threshold and less than or equal to a second stress difference threshold; and determining that the toothed belt is under heavy off-center loading in response to determining, based on the thickness, that the tensile stress difference between the two sides of the toothed belt is greater than the second stress difference threshold.

[0066] According to embodiments of this disclosure, the degree of off-center loading of the toothed belt can be detected during routine maintenance. Before performing the off-center loading test, the preload of the toothed belt can be checked with a torque wrench to ensure that the preload is normal. If the preload is insufficient, the adjusting bolt of the preload device can be tightened to the specified torque using a torque wrench.

[0067] Lead wires can be installed on both sides of the toothed belt to be tested, following the lead wire placement positions during calibration, to ensure that the measured parameters are the same as those during calibration. For example, the pitch bearing can be rotated to a predetermined angle α and held for a predetermined time t, then rotated in the opposite direction to a suitable angle to remove the lead wires from the toothed belt. The thickness δ of the lead wire-compressed portion on the upper side of the toothed belt can then be measured. 上1 δ 上2 δ 上3 The thickness δ of the lead wire under pressure on the lower side of the toothed belt 下1 δ 下2 δ 下3 δ is calculated according to equations (3) and (4) below. 上1 δ 上2 δ 上3 average thickness δ 上 and δ 下1 δ 下2 δ下3 average thickness δ 下 Based on the average thickness δ of the two sides 下 and δ 下 By consulting the predetermined thickness-tensile stress mapping table, the first tensile stress q corresponding to both sides of the toothed strip can be obtained. 上 Second tensile stress q 下 Then, the tensile stress difference Δq between the two sides is calculated according to equation (5).

[0068] δ 上 =(δ 上1 +δ 上2 +δ 上3 ) / 3 (3)

[0069] δ 下 =(δ 下1 +δ 下2 +δ 下3 ) / 3 (4)

[0070] Δq=|q 上 -q 下 | (5)

[0071] Finally, referring to relevant standards and technical requirements for toothed belts, the stress distribution of the toothed belt and its corresponding treatment measures are evaluated. For example, based on the magnitude of the tensile stress difference Δq between the two sides of the toothed belt, the degree of uneven stress distribution is divided into three levels: slight eccentric loading, moderate eccentric loading, and severe eccentric loading, and corresponding maintenance measures are taken for each type of eccentric loading.

[0072] (1) When 0 < Δq ≤ m, the toothed belt is under slight off-center load and no maintenance measures are needed for the time being, but close monitoring is required in the later stage;

[0073] (2) When m<Δq≤n, the toothed belt is under moderate off-center load. It is necessary to check the clearance of the pulley bearing or adjust the installation position of the toothed belt and its fixed base to reduce the uneven force on the toothed belt.

[0074] (3) When n < Δq, the toothed belt is under heavy off-center load and the toothed belt and the severely damaged pulley bearing need to be replaced.

[0075] The first stress difference threshold m and the second stress difference threshold n can be determined through relevant standards and tests for toothed belts.

[0076] The following reference Figures 6 to 8 A method for detecting the degree of off-center load of a toothed belt according to an embodiment of the present disclosure is described. The method can be performed using the toothed belt off-center load detection device described above, but the present disclosure is not limited thereto, and detection devices with other configurations can also be used.

[0077] Figure 6This is a flowchart of a method for detecting the degree of off-center loading of a toothed belt according to an embodiment of the present disclosure.

[0078] In step S61, at least two flexible filamentary elements are detachably disposed on both sides of the first surface of the toothed belt, wherein the first surface faces the pitch bearing.

[0079] In step S62, the thickness of the compressed portion of at least two flexible filamentary elements on the first surface is measured when the pitch bearing rotates a predetermined angle and remains in this position for a predetermined time. For example, the pitch bearing rotates a predetermined angle and remains in this position for a predetermined time, causing the compression deformation of at least two flexible filamentary elements to reach a stable state.

[0080] In step S63, the tensile stress difference between the two sides of the toothed strip is determined based on the thickness.

[0081] Figure 7 This is another flowchart of a method for detecting the degree of off-center loading of a toothed belt according to an embodiment of the present disclosure. In step S71, a first thickness and a second thickness corresponding to the two sides of the toothed belt are determined based on the thickness measured above. In step S72, a predetermined thickness-tensile stress mapping table is consulted based on the first thickness and the second thickness to obtain the first tensile stress and the second tensile stress corresponding to the two sides of the toothed belt, respectively. In step S73, the tensile stress difference between the two sides of the toothed belt is determined based on the first tensile stress and the second tensile stress.

[0082] For example, the first thickness can be the average thickness of the compressed portion of the flexible filament element on the first side of the toothed belt, and the second thickness can be the average thickness of the compressed portion of the flexible filament element on the second side of the toothed belt.

[0083] According to embodiments of this disclosure, the predetermined thickness-tensile stress mapping table is obtained by referring to... Figure 8 The steps described are used to define it. Figure 8 This is another flowchart of a method for detecting the degree of off-center loading of a toothed belt according to an embodiment of the present disclosure.

[0084] In step S81, stress measuring elements are detachably disposed on both sides of the second surface of the toothed belt. In step S82, multiple tensile stress measurements are taken on both sides when a predetermined preload is applied to the toothed belt, wherein the second surface faces away from the first surface. In step S83, multiple thickness measurements are taken at the compressed portions of at least two flexible filamentary elements on the first surface when the toothed belt is subjected to a predetermined preload. In step S84, a tensile stress calibration value is determined based on the multiple tensile stress measurements. In step S85, a thickness calibration value is determined based on the multiple thickness measurements. In step S86, a predetermined thickness-tensile stress mapping table is determined based on the correspondence between the tensile stress calibration value and the thickness calibration value.

[0085] Refer again Figure 6 In step S64, the degree of off-center loading of the toothed belt is determined based on the tensile stress difference. According to embodiments of this disclosure, the degree of off-center loading includes at least one of the following: slight off-center loading, moderate off-center loading, and severe off-center loading. For example, the degree of off-center loading of the toothed belt can be determined by at least one of the following steps: in response to determining that the tensile stress difference between the two sides of the toothed belt is greater than zero and less than or equal to a first stress difference threshold based on the thickness, the toothed belt is determined to be under slight off-center loading; in response to determining that the tensile stress difference between the two sides of the toothed belt is greater than the first stress difference threshold and less than or equal to a second stress difference threshold based on the thickness, the toothed belt is determined to be under moderate off-center loading; in response to determining that the tensile stress difference between the two sides of the toothed belt is greater than the second stress difference threshold based on the thickness, the toothed belt is determined to be under severe off-center loading.

[0086] In reference Figures 1 to 5 The examples described already depict the operations corresponding to each step in the method for detecting the degree of off-center loading of the toothed belt, and for the sake of brevity, they will not be repeated here.

[0087] By employing the toothed belt off-center load detection device and method for detecting the degree of off-center load of the toothed belt according to embodiments of this disclosure, at least one of the following technical effects can be achieved: by setting flexible filamentary elements on the toothed belt, the force distribution of the toothed belt can be detected, the degree of off-center load of the toothed belt can be determined, and the operating status of the pitch transmission system can be diagnosed to ensure the maximum lifespan of the toothed belt; the technical solution proposed in this disclosure is well applicable to on-site wind turbine maintenance, and has important reference value for guiding pitch system maintenance and preliminary fault diagnosis, and is of great significance for improving the lifespan of the toothed belt; the technical solution proposed in this disclosure is flexible and convenient to use, and has high accuracy. It has advantages such as being a non-destructive testing method, suitable for actual production; by detecting the difference in tensile stress on both sides of the toothed belt, the stress distribution and degree of off-center loading of the toothed belt can be identified, effectively utilizing the structural characteristics and stress distribution characteristics of the toothed belt; through calibration tests, a mapping table between the pressing thickness of the flexible filament element and tensile stress was established, transforming the detection of tensile stress on the side of the toothed belt into the detection of the pressing thickness of the flexible filament element, effectively improving the accuracy of off-center loading detection; and the calibration test and related components in the detection process (e.g., flexible filament element, stress measuring element) are easy to disassemble and assemble, thus adapting well to the field maintenance environment and facilitating operation by field maintenance personnel.

[0088] In the technical solutions disclosed in this invention, the control logic or functions executed by various components or the processor itself can be represented by flowcharts or similar diagrams in one or more accompanying drawings. These drawings provide representative control strategies and / or logic, which can be implemented using one or more processing strategies (such as event-driven, interrupt-driven, multitasking, multithreading, etc.). Therefore, the illustrated steps or functions may be executed in the illustrated order, in parallel, or in some cases omitted. Although not always explicitly shown, those skilled in the art will recognize that one or more illustrated steps or functions may be repeatedly executed depending on the specific processing strategy used.

[0089] Although this disclosure has been shown and described with reference to preferred embodiments, those skilled in the art will understand that various modifications and variations may be made to these embodiments without departing from the spirit and scope of this disclosure as defined by the claims.

Claims

1. A toothed belt off-center load detection device, characterized in that, The toothed belt is fixed at both ends to the pitch bearing to drive the pitch bearing to rotate. The device includes: At least two flexible filamentary elements are detachably disposed on both sides of the first surface of the toothed belt, the first surface facing the pitch bearing; A thickness measuring element is used to measure the thickness of the at least two flexible filamentary elements on the first surface under pressure when the pitch bearing rotates at a predetermined angle and is held for a predetermined time; The processor is used to determine the tensile stress difference between the two sides of the toothed belt based on the thickness, and to determine the degree of off-center loading of the toothed belt based on the tensile stress difference.

2. The apparatus according to claim 1, characterized in that, The at least two flexible filamentary elements are detachably disposed on the side near the drive wheel or the side near the tension wheel.

3. The apparatus according to claim 1, characterized in that, The pitch bearing rotates at a predetermined angle and holds for a predetermined time, causing the at least two flexible filamentary elements to reach a stable state under pressure deformation.

4. The apparatus according to any one of claims 1 to 3, characterized in that, The processor is used to perform the following operations: Based on the thickness, determine the first thickness and the second thickness corresponding to the two sides of the toothed strip, respectively; Based on the first thickness and the second thickness, a predetermined thickness-tensile stress mapping table is consulted to obtain the first tensile stress and the second tensile stress corresponding to the two sides of the toothed strip, respectively. The tensile stress difference between the two sides of the toothed belt is determined based on the first tensile stress and the second tensile stress.

5. The apparatus according to claim 4, characterized in that, The first thickness is the average thickness of the compressed portion of the flexible filament element on the first side of the toothed belt, and the second thickness is the average thickness of the compressed portion of the flexible filament element on the second side of the toothed belt.

6. The apparatus according to claim 4, characterized in that, The predetermined thickness-tensile stress mapping table is calibrated using a stress measuring element, the thickness measuring element, and another processor. The stress measuring element is detachably mounted on both sides of the second surface of the toothed belt and is used to measure multiple tensile stress values ​​on both sides when a predetermined preload is applied to the toothed belt. The second surface faces away from the first surface. The thickness measuring element is used to measure multiple thickness values ​​of the at least two flexible filamentary elements on the first surface at the pressure points when a predetermined preload is applied to the toothed belt. The other processor is used to determine a tensile stress calibration value based on the plurality of tensile stress measurements, determine a thickness calibration value based on the plurality of thickness measurements, and determine the thickness-tensile stress mapping table based on the correspondence between the tensile stress calibration value and the thickness calibration value.

7. The apparatus according to claim 6, characterized in that, The at least two flexible filamentary elements are positioned in the same way as those used in detecting the off-center load of the toothed belt during the calibration process.

8. The apparatus according to claim 1, characterized in that, The degree of off-center loading includes at least one of the following: slight off-center loading, moderate off-center loading, and severe off-center loading. The processor is used to perform at least one of the following operations: In response to the determination that the tensile stress difference between the two sides of the toothed belt is greater than zero and less than or equal to a first stress difference threshold based on the thickness, it is determined that the toothed belt is under slight off-center loading. In response to determining that the tensile stress difference between the two sides of the toothed belt is greater than a first stress difference threshold and less than or equal to a second stress difference threshold based on the thickness, it is determined that the toothed belt is under moderate off-center load. In response to the determination that the tensile stress difference between the two sides of the toothed belt is greater than the second stress difference threshold based on the thickness, it is determined that the toothed belt is under heavy off-center load.

9. A method for detecting the degree of off-center loading of a toothed belt using the off-center loading detection device as described in any one of claims 1 to 8, characterized in that, The method includes: At least two flexible filamentary elements are detachably disposed on both sides of the first surface of the toothed belt, wherein the first surface faces the pitch bearing; The thickness of the at least two flexible filamentary elements on the first surface under pressure is measured when the pitch bearing rotates a predetermined angle and is held for a predetermined time. The tensile stress difference between the two sides of the toothed strip is determined based on the thickness. The degree of off-center loading of the toothed belt is determined based on the tensile stress difference.

10. The method according to claim 9, characterized in that, The pitch bearing rotates at a predetermined angle and holds for a predetermined time, causing the at least two flexible filamentary elements to reach a stable state under pressure deformation.

11. The method according to claim 9 or 10, characterized in that, Determining the tensile stress difference between the two sides of the toothed strip based on the thickness includes: Based on the thickness, determine the first thickness and the second thickness corresponding to the two sides of the toothed strip, respectively; Based on the first thickness and the second thickness, a predetermined thickness-tensile stress mapping table is consulted to obtain the first tensile stress and the second tensile stress corresponding to the two sides of the toothed strip, respectively. The tensile stress difference between the two sides of the toothed belt is determined based on the first tensile stress and the second tensile stress.

12. The method according to claim 11, characterized in that, The first thickness is the average thickness of the compressed portion of the flexible filament element on the first side of the toothed belt, and the second thickness is the average thickness of the compressed portion of the flexible filament element on the second side of the toothed belt.

13. The method according to claim 11, characterized in that, The predetermined thickness-tensile stress mapping table is determined through the following steps: The stress measuring element is detachably mounted on both sides of the second surface of the toothed belt; Measure multiple tensile stress values ​​on both sides of the toothed belt when a predetermined preload is applied, wherein the second surface faces away from the first surface; Measure multiple thickness measurements of the at least two flexible filamentary elements on the first surface at the pressure points when the toothed belt is subjected to the predetermined preload; The tensile stress calibration value is determined based on the multiple tensile stress measurements. The thickness calibration value is determined based on the multiple thickness measurements; The thickness-tensile stress mapping table is determined based on the correspondence between the tensile stress calibration value and the thickness calibration value.

14. The method according to claim 9, characterized in that, The degree of off-center loading includes at least one of the following: slight off-center loading, moderate off-center loading, and severe off-center loading. Determining the degree of off-center loading of the toothed belt based on the tensile stress difference includes at least one of the following steps: In response to the determination that the tensile stress difference between the two sides of the toothed belt is greater than zero and less than or equal to a first stress difference threshold based on the thickness, it is determined that the toothed belt is under slight off-center loading. In response to determining that the tensile stress difference between the two sides of the toothed belt is greater than a first stress difference threshold and less than or equal to a second stress difference threshold based on the thickness, it is determined that the toothed belt is under moderate off-center load. In response to the determination that the tensile stress difference between the two sides of the toothed belt is greater than the second stress difference threshold based on the thickness, it is determined that the toothed belt is under heavy off-center load.

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