A bolt loosening angle sensor

Abstract

This application discloses a bolt loosening angle sensor for monitoring the relative looseness between a bolt and a nut. The bolt loosening angle sensor includes a bolt fixing assembly and a nut fixing assembly. The bolt fixing assembly, fixed to the bolt, includes a base and a bipolar magnet, with the bipolar magnet fixed to the base. The nut fixing assembly, fixed to the nut, includes a housing and a monitoring module, with the monitoring module fixed to the housing. The monitoring module monitors changes in the magnetic field direction of the bipolar magnet to detect the loosening angle between the bolt and nut fixing assemblies. Compared to existing technologies, this bolt loosening angle sensor, by utilizing a monitoring module to detect changes in the magnetic field direction of a bipolar magnet to monitor the loosening angle between the bolt and nut fixing assemblies, offers high testing accuracy, simple installation, convenient maintenance, effectively reduces costs, and can quickly locate the loose bolt.

Description

Technical Field

[0001] This application relates to the field of mechanical structure technology, and in particular to a bolt loosening angle sensor. Background Technology

[0002] Due to factors such as vibration from mechanical movement, metal stress, and external loads, coupled with harsh operating environments and complex working conditions, the high-strength connecting bolts used in wind turbines are subjected to the combined effects of various loads, including vibration, torsion, and shear, over a long period of time during operation. This leads to varying degrees of loosening of the high-strength connecting bolts. Once a bolt becomes loose and goes undetected, the stress amplitude between the loose bolt and surrounding bolts will increase, creating a vicious cycle that significantly shortens fatigue life. Bolt breakage will become inevitable. This can result in minor damage to components, such as secondary damage from a broken bolt falling off and incurring significant repair costs. In severe cases, it can lead to serious safety accidents and huge economic losses.

[0003] People have tried various methods to prevent high-strength bolts from loosening after installation, but so far, a solution that works for all types of bolts and completely prevents loosening has not been found. Therefore, the problem of loose bolts remains fundamentally unresolved.

[0004] Regularly inspecting and tightening loose bolts is a common practice across various industries. High-strength bolts on large wind turbine towers require 100% manual inspection every 3-6 months. This manual method is not only labor-intensive and time-consuming, but also makes it difficult to accurately assess the looseness of each bolt, potentially leading to safety hazards if omissions occur. To ensure the safe and stable operation of wind turbines, reduce maintenance costs, and prevent major accidents, monitoring the loosening angle of high-strength connecting bolts on wind turbine blades and towers, and promptly tightening loose bolts to prevent accidents, is an urgent industry need.

[0005] In monitoring the relative loosening of screws and nuts, traditional methods include the torque method and the line marking method. However, these two methods are labor-intensive, lack precision, and require manual inspection or machine operation.

[0006] In monitoring bolt preload, bolt preload sensors mounted on the bolts transmit and receive ultrasonic pulse signals, measure and calculate the time difference between the transmitted and echo signals, and determine the magnitude of the bolt preload by comparing the measurement time changes between tightened and loose states, thus indicating the bolt's looseness. However, this method is complex to implement, has high online monitoring costs, is inconvenient to install, and requires regular calibration, making its application to high-strength connection bolts difficult.

[0007] In monitoring the flange clearance of high-strength bolted connections, high-precision displacement sensors can be installed at several locations on the flange to detect the gap between the flanges and indirectly identify the loosening of the high-strength bolts. However, this method is only effective when there is a gap in the flange due to the tension and loosening of the bolts. Since wind turbine flanges have a large number of high-strength bolts, the loosening of a small number of bolts usually does not cause flange clearance displacement; therefore, this method cannot be used to monitor bolt loosening.

[0008] How to accurately monitor bolt loosening while ensuring simple installation and convenient maintenance is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a bolt loosening angle sensor that features high testing accuracy, simple installation, and convenient maintenance.

[0010] The technical solution provided by this invention is as follows:

[0011] A bolt loosening angle sensor is disclosed for monitoring the relative looseness between a bolt and a nut. The bolt loosening angle sensor includes a bolt fixing assembly and a nut fixing assembly. The bolt fixing assembly, which is fixed to the bolt, includes a base and a bipolar magnet, with the bipolar magnet fixed to the base. The nut fixing assembly, which is fixed to the nut, includes a housing and a monitoring module, with the monitoring module fixed to the housing. The monitoring module monitors changes in the magnetic field direction of the bipolar magnet to detect the loosening angle between the bolt fixing assembly and the nut fixing assembly.

[0012] Preferably, the bipolar magnet is a bipolar magnetic column, and the base includes a base plate and a snap-fit ​​structure on the base plate that is adapted to the bipolar magnetic column. The snap-fit ​​structure fixes the bipolar magnetic column to the base and keeps the axis of the bipolar magnetic column perpendicular to the axis of the base.

[0013] Preferably, the buckle structure is located on the side of the base plate facing the screw or away from the screw; the buckle structure includes four buckle posts, and the bipolar magnetic post is clamped and fixed between the four buckle posts; or the buckle structure includes two buckle members forming an arc-shaped clamping structure, and the bipolar magnetic post is pressed and fixed between the two buckle members.

[0014] Preferably, it includes a first set of magnetic field markings, each corresponding to a bipolar magnet pole, and the first set of magnetic field markings is located around the periphery of the base;

[0015] and / or a second set of magnetic field markers, wherein the second set of magnetic field markers is located at the periphery of the housing;

[0016] And / or a third set of magnetic field markers, wherein the third set of magnetic field markers is located on the base and is disposed at both ends of the bipolar magnet.

[0017] The bolt loosening angle sensor as described in claim 1 is characterized in that the base is fixed to the screw rod by a threaded connection or a snap-fit ​​method.

[0018] Preferably, there is a gap between the base and the housing in the axial direction of the screw to prevent the base from abutting against the housing after the bolts loosen.

[0019] Preferably, the housing includes a mating outer shell and a cover plate, the outer shell and the cover plate forming a cavity to fix and encapsulate the monitoring module in the cavity.

[0020] Preferably, the housing includes a top plate and a fixing portion extending downward from the top plate to be fixed to the nut; the inner wall of the fixing portion is provided with a stop structure to prevent the nut fixing assembly from sliding relative to the nut.

[0021] Preferably, the fixing part includes a plurality of support bars, the ends of which are fixed to nuts by clamps; the clamps include a retaining ring for surrounding the outer edge of the support bar and a clamping member for adjusting the retaining ring to fasten the support bar to the nut; each of the support bars has a clamp groove on its outer side that is adapted to the clamp to restrict the installation position of the clamp.

[0022] Preferably, the fixing part is annular, and has a flexible movable lateral end formed by a horizontal slit at the top and a longitudinal slit at the end. The movable lateral end is locked to the adjacent fixing end by a locking tooth engagement.

[0023] Preferably, the locking teeth of the movable lateral end and the fixed end are respectively arranged inward and outward, and the inward locking teeth of the movable lateral end cooperate with the outward locking teeth of the fixed end; or the locking teeth of the movable lateral end and the fixed end are both arranged vertically, the first locking tooth of the movable lateral end includes two locking tooth portions arranged opposite to each other, and the second locking tooth of the fixed end includes two locking tooth portions arranged facing each other, and the first locking tooth cooperates with the second locking tooth.

[0024] Preferably, the fixing part includes two semi-annular parts with a gap between the side ends of the two semi-annular parts, and each semi-annular part has a buckle protruding outward at the bottom of both sides. The buckles of the two semi-annular parts are fastened and fixed by the buckles.

[0025] Preferably, the monitoring module includes a circuit board, a monitoring element, and a connector. The circuit board is fixed to the housing, the monitoring element is mounted on the circuit board, and the connector is electrically connected to the circuit board.

[0026] Preferably, the connector includes a male and a female connector that are compatible with each other, for direct connection in series with an adjacent bolt loosening angle sensor; the monitoring module also includes two cables, with the male or female connector of the connector connected to the circuit board at both ends of the two cables respectively; the surfaces of the housing and the cover plate that are in contact with each other are respectively provided with a first cable groove and a second cable groove, and the first cable groove and the second cable groove are respectively provided with a first holding part and a second holding part for holding the cable sheath.

[0027] Preferably, the connector is an onboard connector, which is mounted on a circuit board, and the housing is provided with a mounting groove to expose the onboard connector.

[0028] Preferably, the upper surface of the housing is provided with a circuit board groove for matching the circuit board, and the cover plate is placed on the upper surface of the housing to form a cavity for fixing the monitoring module; or the lower surface of the housing is provided with a circuit board groove for matching the circuit board, and the cover plate is placed on the lower surface of the housing to form a cavity for fixing the monitoring module.

[0029] Preferably, the cover plate is secured by screws and / or clips.

[0030] Preferably, the circuit board has lugs at both ends, and the circuit board groove has a side groove corresponding to the lugs; each lug has a screw mounting through hole, and the outer shell has a screw hole corresponding to the screw mounting through hole, so that the screw can be screwed into the screw hole through the screw mounting through hole.

[0031] Preferably, the circuit board has a notch on one side to serve as a direction indicator; the cavity is filled with insulating adhesive for encapsulating the monitoring module.

[0032] Preferably, the monitoring element is a TMR sensitive chip that can convert the direction of the sensed magnetic field into a resistance value; the circuit board also includes a microcontroller module, which stores sensor identification information.

[0033] Preferably, the monitoring module further includes an indicator light mounted on the circuit board for displaying the working status of the sensor and a zeroing device for zeroing the initial angle signal of the sensor. The indicator light and the zeroing device are exposed outside the housing. The cover plate has multiple device through holes, corresponding to the zeroing device and the indicator light respectively, so that the zeroing device and the indicator light are exposed, while providing a potting channel.

[0034] Compared to existing technologies, the bolt loosening angle sensor of this invention uses a bipolar magnet on the screw fastening assembly and a monitoring module on the nut fastening assembly to monitor changes in the magnetic field direction of the bipolar magnet. By monitoring changes in the magnetic field direction of the bipolar magnet, the loosening angle between the screw fastening assembly and the nut fastening assembly can be monitored. This sensor offers high testing accuracy, simple installation, convenient maintenance, and can effectively reduce costs. It can also quickly locate the position of loose bolts. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is an exploded perspective view of the bolt loosening angle sensor according to an embodiment of the present invention;

[0037] Figure 2 for Figure 1 The cross-sectional view of the bolt loosening angle sensor shown;

[0038] Figure 3 for Figure 1 The diagram shows a cross-sectional view of the bolt loosening angle sensor and the screw and nut in use.

[0039] Figure 4 for Figure 1 A cross-sectional view of the screw fastening assembly in the bolt loosening angle sensor shown.

[0040] Figure 5 for Figure 4 A perspective view of the base in the screw fastening assembly shown;

[0041] Figure 6 for Figure 5 A bottom view of the base shown;

[0042] Figure 7 for Figure 5 Top view of the base shown;

[0043] Figure 8 for Figure 5 A cross-sectional view of the base shown;

[0044] Figure 9 for Figure 1 A top view of another embodiment of the screw fastening assembly in the bolt loosening angle sensor shown;

[0045] Figure 10 for Figure 9 A cross-sectional view of the screw fastening assembly shown;

[0046] Figure 11 for Figure 1 A 3D view of the circuit board of the nut fastening assembly in the bolt loosening angle sensor shown.

[0047] Figure 12 for Figure 1A perspective view of the housing of the nut fastening assembly in the bolt loosening angle sensor shown.

[0048] Figure 13 for Figure 12 A three-dimensional view of the outer shell from another angle;

[0049] Figure 14 for Figure 1 A perspective view of the housing of the nut fastening assembly in the bolt loosening angle sensor, according to a second embodiment;

[0050] Figure 15 for Figure 1 A perspective view of the housing of the nut fastening assembly in the bolt loosening angle sensor, according to a third embodiment;

[0051] Figure 16 for Figure 1 A perspective view of the housing of the nut fastening assembly in the bolt loosening angle sensor, according to a fourth embodiment;

[0052] Figure 17 for Figure 1 A perspective view of the cover plate of the nut fastening assembly in the bolt loosening angle sensor shown.

[0053] Figure 18 for Figure 1 An exploded perspective view of the second embodiment of the nut fastening assembly in the bolt loosening angle sensor shown;

[0054] Figure 19 for Figure 18 A three-dimensional assembly diagram of the nut fastening assembly shown;

[0055] Figure 20 for Figure 1 An exploded perspective view of the third embodiment of the nut fastening assembly in the bolt loosening angle sensor shown;

[0056] Figure 21 for Figure 1 An exploded perspective view of the fourth embodiment of the nut fastening assembly in the bolt loosening angle sensor shown;

[0057] Figure 22 for Figure 21 A three-dimensional assembly diagram of the nut fastening assembly shown;

[0058] Figure 23 for Figure 21 The nut fastening assembly shown is a three-dimensional assembly diagram from another angle. Detailed Implementation

[0059] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0060] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0061] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0063] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0064] As shown in the figure, this embodiment of the invention provides a bolt loosening angle sensor for monitoring the relative looseness between the bolt and the nut, particularly for installation on several bolts in areas prone to loosening of high-strength connecting bolts in wind turbine units. The bolt loosening angle sensor includes a bolt fixing assembly 1 and a nut fixing assembly 2.

[0065] like Figures 3 to 8As shown, the screw fixing assembly 1 is used to fix the screw 3, including a base 11 and a bipolar magnet, with the bipolar magnet fixed to the base 11.

[0066] A bipolar magnet has N poles and S poles. In this embodiment, it is a cylindrical bipolar magnetic column 12.

[0067] The base 11 includes a circular base plate 111 and an annular base sidewall 112 extending downward from the periphery of the base plate 111. The lower surface of the base plate 111 has a snap-fit ​​structure (not shown) adapted to the bipolar magnetic post 12 and a third set of magnetic field markings 1111 located at both ends of the bipolar magnetic post 12. The snap-fit ​​structure is used to fix the bipolar magnetic post 12 to the base 11, ensuring that the axis of the bipolar magnetic post 12 is perpendicular to the axis of the base 11. During installation, the axis of the bipolar magnetic post 12 is adjusted to be perpendicular to the axis of the base, and structural adhesive is applied to the joint between the bipolar magnetic post 12 and the snap-fit ​​structure of the base 11 for reinforcement. The third set of magnetic field markings 1111 are either "N" or "S", used for accurate installation of the bipolar magnetic post 12, located on the base 11 and positioned at both ends of the bipolar magnetic post 12.

[0068] In this embodiment, the snap-fit ​​structure includes four snap-fit ​​posts 1112, disposed on the lower surface of the base plate 111. A bipolar magnetic post 12 is clamped and fixed between the four snap-fit ​​posts 1112. Each snap-fit ​​post 1112 has a guide chamfer at its end to facilitate the insertion of the bipolar magnetic post 12. Because the bipolar magnetic post 12 is fixed to the lower surface of the base plate 111 (i.e., the side facing the screw) by the snap-fit ​​structure, structural adhesive can be applied to the screw before assembly. This forms a sealed space, and the bipolar magnetic post is insulated from the air and less prone to rusting. In other embodiments, the snap-fit ​​structure can be of other shapes, such as... Figure 9 , Figure 10 As shown, the snap-fit ​​structure includes two snap-fit ​​members 1113 forming an arc-shaped clamping structure, with a bipolar magnetic post 12 pressed and fixed between the two snap-fit ​​members 1113. The two snap-fit ​​members 1113 are located on the upper surface of the base plate, and the lower edge of the side wall is provided with a protruding structure 1114 for engaging with the screw. Each snap-fit ​​member 1113 has a guide chamfer at its end to facilitate the engagement of the bipolar magnetic post 12. The base plate adopts a hollow design around its perimeter to reduce weight.

[0069] The periphery of the base sidewall 112, corresponding to the magnetic poles of the bipolar magnetic post 12, is provided with a first set of magnetic field markings 1121. These markings are pentagonal grooves with directional arrows and internal "N" or "S" markings, indicating the direction of the magnetic field based on the arrow's orientation. This marking structure also provides a clamping position for base installation and removal. The bottom of the base sidewall 112 has an internal thread 1122, the end of which is flush with the top of the snap-fit ​​structure. After installation, the distance from the end face of the high-strength connecting bolt 3 to the top of the base is consistent, ensuring the consistency of the bolt 3's influence on the magnetic field.

[0070] like Figures 1 to 3 As shown, the nut fastening assembly 2 is used to fix the nut 4, and mainly includes a housing 21 and a monitoring module (not shown). The monitoring module is fixed to the housing 21 and is used to monitor the change in the magnetic field direction of the bipolar magnet, so as to monitor the loosening angle between the screw fastening assembly 1 and the nut fastening assembly 2 by monitoring the change in the magnetic field direction of the bipolar magnet.

[0071] The monitoring module includes a circuit board 22, a monitoring element (not shown), a connector (not labeled), cables 25, two indicator lights 26, and a zeroing device 27. The monitoring element, two cables 25, indicator lights 26, and zeroing device 27 are mounted on the circuit board 22. The monitoring element is the main component for monitoring changes in the magnetic field. The two indicator lights 26 are used to display the sensor's operating status. The zeroing device 27 is used to zero the initial angle signal of the sensor. Figure 11 As shown, in this embodiment, the circuit board 22 is a circular plate with two symmetrical lugs, each with a screw mounting through hole 221. One side of the circuit board 22 also has a notch 222 as a directional indicator. One end of the middle of the circuit board 22 has a device interface 223 for soldering the indicator light 26 and the zeroing device 27, and both sides have cable interfaces 224 for soldering the cables 25.

[0072] In this embodiment, the monitoring element is a TMR (Tunnel Magnet Resistance) sensitive chip, which converts the direction of the sensed magnetic field into a resistance value. The sensor body is fixed to the bolt by a nut, and the other part is a magnet mounting assembly, which is mounted on the end face of the screw by a screw connection. When the bolt rotates, it causes the sensor body to rotate, and the PCB board containing the TMR sensitive chip also rotates. The magnet is fixed to the screw and does not rotate. As a result, the TMR sensitive chip and the magnet rotate relative to each other in the horizontal direction, and the direction of the magnetic field detected by the TMR sensitive chip changes, thereby detecting the bolt loosening angle.

[0073] The circuit board can also be equipped with a communication unit (such as a 485 circuit), a power supply circuit, a power control circuit, and a microcontroller module, which are electrically connected through the circuitry. The microcontroller module can store sensor identification information, and the communication unit can be used to remotely monitor each sensor, thereby quickly locating the position of loose bolts.

[0074] The connector connects to the monitoring element via circuit board 22, providing power and transmitting signals. In this embodiment, the connector includes a mating male connector 241 and a female connector 242, and can be a six-pin waterproof connector. The two ends of two cables 25 connect the male connector 241 and the female connector 242 to circuit board 22, respectively, so that the male connector 241 and the female connector 242 are connected to circuit board 22 via cables 25. Thus, when adjacent sensors need to be connected in series, the male connector of one sensor is directly plugged into the female connector of the adjacent sensor. In other embodiments, the connector can also be directly mounted on the circuit board. Figure 20 As shown, in other embodiments, the onboard connector 243 can also be directly soldered and fixed to the circuit board 22'. A mounting groove 2111' is provided in the housing 211' to expose the onboard connector 243. This allows signal output without using cables, and makes it easier to achieve circuit board sealing and waterproofing. The onboard connector 243 can be two identical five-pin connector females, and the cover plate 212' assists in fixing the onboard connector by screw connection or snap-fit ​​connection. The shape of the onboard connector is not limited, but rectangular or circular shapes are preferred. Thus, when adjacent sensors need to be connected in series, a cable with male connector heads at both ends can be inserted into the connector female.

[0075] The housing 21 includes a mating outer shell 211 and a cover plate 212, which form a cavity to fix and encapsulate the monitoring module. After assembly, the cavity is filled with insulating adhesive for encapsulating the monitoring module.

[0076] The housing 211 is mainly used as a casing for the sensor to protect the internal components. For example... Figure 12 , Figure 13 As shown, in this embodiment, the outer casing 211 includes a top plate 2111 and a fixing portion (not shown) extending downward from the top plate 2111 for fixing to the nut 4.

[0077] The top plate 2111 has a circuit board recess 2112 in the middle of its upper surface to accommodate the circuit board 22 and avoid components on the circuit board. The circuit board recess has side grooves corresponding to the lugs on the circuit board. Two screw mounting interfaces 2113 are provided within the circuit board recess 2112. These interfaces can be blind holes or threaded holes, allowing screws 28 to pass through screw mounting through holes 221 on the circuit board to fix the circuit board 22 into the circuit board recess 2112. The top plate 2111 has first cable recesses 2114 on both sides of its upper surface, connecting the circuit board recess to the outside. The central portion of the first cable recess 2114 is smaller than the dimensions of the sides, forming a first retaining portion 2115. This retaining portion is used to hold the cable 25 in place after installation. If there is a gap between the first cable recess 2114 and the cable 25, it can be covered by applying structural adhesive. The upper periphery of the top plate 2111 has four snap-fit ​​recesses 2116 for engaging with the cover plate 212. The top plate 2111 also has a second set of magnetic field markings 2117 around the perimeter, corresponding to the first set of magnetic field markings 1121.

[0078] In this embodiment, the fixing part includes six support bars 2118, the ends of which are fixed to the nut 4 by clamps 29. The inner side of the support bar 2118 is provided with a serrated protrusion structure 2119 as a stop structure to increase the friction between the nut fixing assembly and the nut during installation, preventing the nut fixing assembly from sliding relative to the nut. The serrated protrusions can also be wavy, strip-shaped, or block-shaped, or other shapes that can prevent relative sliding of the nut fixing assembly. The outer side of the support bar 2118 is provided with a clamp groove 21181 that matches the clamp, restricting the installation position of the clamp 29, preventing the clamp 29 from falling off due to external forces after installation, ensuring uniform force distribution at the joint between the nut fixing assembly and the nut after clamp installation, and reducing the space dimension of the nut fixing assembly after installation. The clamp includes a retaining ring for wrapping around the outer edge of the support bar and a clamping member for adjusting the retaining ring to secure the support bar to the nut.

[0079] In other embodiments, the fixing part may also have other shapes and structures. For example... Figure 14 , Figure 15 As shown, the fixing part is ring-shaped. The first half of the fixing part is connected to the top plate, and the second half of the fixing part has a transverse slit. The end of the second half of the fixing part has a longitudinal slit to make the second half of the fixing part elastic. The end of the longitudinal slit forms a movable transverse end. The movable transverse end is locked to the adjacent fixing end by a locking tooth engagement. Figure 14 In the embodiment shown, the locking teeth are disposed on the inner and outer sides of the fixed part, that is, the locking teeth of the movable lateral end and the fixed end are respectively disposed inward and outward, and the inward locking teeth of the movable lateral end cooperate with the outward locking teeth 2118' of the fixed end. Figure 15In the illustrated embodiment, the locking teeth are disposed on the upper and lower sides of the fixed part, that is, the locking teeth of both the movable lateral end and the fixed end are disposed facing up and down. The first locking tooth 2118” of the movable lateral end includes two locking tooth portions disposed opposite to each other, and the second locking tooth 2119” of the fixed end includes two locking tooth portions disposed facing each other. The first locking tooth 2118” of the movable lateral end and the second locking tooth 2119” of the fixed end cooperate with each other. Figure 16 As shown, the fixing part may also include two semi-circular parts 2118”', with a gap between the side ends 2118”' of the two semi-circular parts, and outwardly protruding buckle 21181”' at the bottom of both sides of each semi-circular part 2118”', and the adjacent buckle 21181”' of the two semi-circular parts are fastened and fixed by buckle 2119”'.

[0080] like Figure 17 As shown, in this embodiment, the cover plate 212 is generally circular, with four snap-fit ​​protrusions 2121 extending downwards on its lower surface to engage with the snap-fit ​​grooves 2116 of the outer casing, thus securing the cover plate 212 to the outer casing 211. The lower surface of the cover plate 212 has two second cable grooves 2122 corresponding to the first cable groove 2114. The size of the middle portion of the second cable groove 2122 is smaller than the sizes of the sides, forming a second holding portion 2123. This allows the cable 25 to be held in place by the middle portion after installation. If there is a gap between the second cable groove 2122 and the cable 25, located between the second holding portion 2123 and the outside, it can be covered by applying structural adhesive. The cover plate 212 also has a first device through-hole 2124 and two second device through-holes 2125, corresponding to the placement of the component 27 and the two indicator lights 26, respectively, so that the component 27 and the two indicator lights 26 are exposed, while providing a channel for potting adhesive. The second device through-holes 2125 can be chamfered to accommodate the shape of the indicator lights. In other embodiments, such as... Figures 21 to 23 As shown, the circuit board groove 2112”' can be set inside the housing 211”', the upper surface of the housing 211”' is provided with a first device through hole 2124”' and two second device through holes 2125”' and exposed, the cover plate 212”' is set inside the housing 211”', and the circuit board and the cover plate are fixed with screws 213”'.

[0081] In other embodiments, the outer casing and the cover plate can also be fixed in other ways, such as... Figure 18 , Figure 19 As shown, the outer shell 211” and the cover plate 212” can be fixed with screws. The outer shell has threaded holes, and the cover plate has countersunk holes, which are fixed with countersunk screws 213”. Alternatively, a combination of clips and screws can be used, which can strengthen the connection and prevent the cover plate from falling off if the screws loosen.

[0082] In this embodiment, the outer shell, cover plate, base, and male / female connectors are made of weather-resistant engineering plastics, the screws and clamps are made of stainless steel, and the bipolar magnetic pillars are made of permanent magnet material. All components are assembled together, giving the sensor good toughness. The stainless steel clamps, plastic shell, and high-strength structural steel nuts work together to ensure even stress distribution on the shell and guarantee the reliability of the connection between the shell and the nut.

[0083] The assembly process of the screw fastening assembly is as follows: the bipolar magnet is fixed to the base by a snap fastener.

[0084] The assembly process of the nut fastening assembly is described as follows:

[0085] Place the circuit board flat in the circuit board groove provided on the outer casing, and screw two screws into the outer casing along the screw mounting through holes provided on the circuit board to achieve a fixed connection between the circuit board and the outer casing.

[0086] The cable is soldered and fixed to the corresponding soldering position on the circuit board. Structural adhesive is applied to the cable groove in the outer shell, and the cable is inserted to limit the cable position.

[0087] Structural adhesive is applied to the upper surface of the outer shell (the side in contact with the cover plate). The buckle protrusions of the cover plate are aligned with the buckle grooves of the outer shell and pressed in to achieve a fixed connection between the outer shell and the cover plate, and at the same time, to fix the cable.

[0088] Sealant is injected through the device through-holes on the cover plate to completely cover the circuit board and cable soldering positions, thereby achieving sensor sealing and insulation.

[0089] Install the male and female connectors at both ends of the cable, respectively;

[0090] Install the clamp into the clamp groove on the outer shell, and tighten it onto the nut to prevent it from falling off.

[0091] The installation process of the bolt loosening angle sensor and the bolt is as follows:

[0092] The screw fastening assembly is screwed and fixed onto the screw;

[0093] The nut fastening assembly is fixed to the nut from above the screw fastening assembly, and the housing support is secured to the outer edge of the nut using clamps. After installation, there is a gap between the base and the housing along the screw axis to prevent the base and housing from abutting each other and rubbing together after the bolts loosen, which could cause the base or housing to shift and affect the monitoring effect of the sensor.

[0094] Compared to existing technologies, the bolt loosening angle sensor in this embodiment has the following advantages: high testing accuracy, simple installation, convenient maintenance, effective cost reduction, and rapid location of loose bolts. The sensor has two complementary connectors, adapting to the loosening detection needs of high-strength connecting bolt groups in a ring-shaped distribution on wind turbine towers or hubs, reducing wiring length. The sensor consists of two components. For the maintenance of loose high-strength connecting bolts, when the sensor detects a loose bolt, only the nut fixing assembly installed on the loose nut needs to be removed to tighten the loose bolt. After tightening, the nut fixing assembly of the sensor can be reattached to the nut to continue monitoring the bolt loosening situation; therefore, this sensor is reusable. The sensor has exposed indicator lights and a zeroing device. The indicator lights can be used to determine the sensor's working status, and the zeroing device can be used to initialize the angle signal of the reinstalled sensor to zero. The sensor can adapt to bolt groups with limited installation space. For multiple sensors connected in series, the fall of a single sensor is constrained by the cable, and the sensor will not have a significant impact on the wind turbine, ensuring high safety. The main structural components of the sensor are made of plastic, which can withstand harsh environmental humidity and salt spray, ensuring that the sensor works stably in various environments and has a long service life.

[0095] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bolt loosening angle sensor for monitoring the relative loosening condition between a screw rod and a nut, characterized by, The bolt loosening angle sensor includes a screw fixing assembly and a nut fixing assembly. The screw fixing assembly, used to fix itself to the screw, includes a base and a bipolar magnet, with the bipolar magnet fixed to the base. The bottom of the base's side wall has an internal thread for screwing the screw fixing assembly to the screw. The nut fixing assembly, used to fix itself to the nut, includes a housing and a monitoring module. The monitoring module, fixed to the housing, monitors changes in the magnetic field direction of the bipolar magnet to detect the loosening angle between the screw fixing assembly and the nut fixing assembly. The housing includes a mating outer shell and a cover plate, forming a cavity to fix and encapsulate the monitoring module within the cavity. The housing includes a top plate and a fixing part extending downward from the top plate for fixing to the nut. The inner wall of the fixing part has a stop structure to prevent the nut fixing assembly from sliding relative to the nut. The nut fixing assembly is fixed to the nut from above the screw fixing assembly. The base and housing have a gap along the screw axis to prevent the base from contacting the housing after the bolt loosens. The fixing part includes multiple support bars, the ends of which are fixed to nuts by clamps; the clamps include a retaining ring for surrounding the outer edge of the support bar and a clamping member for adjusting the retaining ring to fasten the support bar to the nut; each of the support bars has a clamp groove on its outer side that is adapted to the clamp to restrict the installation position of the clamp. Alternatively, the fixing part is annular, with a flexible movable lateral end formed by a horizontal slit at the top and a longitudinal slit at the end. The movable lateral end and the adjacent fixed end are locked together by a locking tooth. The locking teeth of the movable lateral end and the fixed end are respectively arranged inward and outward, and the inward locking tooth of the movable lateral end and the outward locking tooth of the fixed end cooperate. Alternatively, the locking teeth of the movable lateral end and the fixed end are both arranged vertically. The first locking tooth of the movable lateral end includes two locking tooth portions arranged opposite each other, and the second locking tooth of the fixed end includes two locking tooth portions arranged facing each other. The first locking tooth and the second locking tooth cooperate. Alternatively, the fixing part includes two semi-annular parts with a gap between the side ends of the two semi-annular parts. Each semi-annular part has outwardly protruding buckle clips at the bottom of both sides. The buckle clips of the two adjacent semi-annular parts are fastened and fixed by the buckle clips.

2. The bolt loosening angle sensor according to claim 1, wherein The bipolar magnet is a bipolar magnetic column, and the base includes a base plate and a snap-fit ​​structure on the base plate that is adapted to the bipolar magnetic column. The snap-fit ​​structure fixes the bipolar magnetic column to the base and keeps the axis of the bipolar magnetic column perpendicular to the axis of the base.

3. The bolt loosening angle sensor according to claim 2, wherein The buckle structure is located on the side of the base plate facing the screw or away from the screw; the buckle structure includes four buckle posts, and the bipolar magnetic post is clamped and fixed between the four buckle posts; or the buckle structure includes two buckle members forming an arc-shaped clamping structure, and the bipolar magnetic post is pressed and fixed between the two buckle members.

4. The bolt loosening angle sensor according to claim 1, wherein Includes a first set of magnetic field markings, each corresponding to a bipolar magnet pole, located around the periphery of the base; and / or a second set of magnetic field markers, wherein the second set of magnetic field markers is located at the periphery of the housing; And / or a third set of magnetic field markers, wherein the third set of magnetic field markers is located on the base and is disposed at both ends of the bipolar magnet.

5. The bolt looseness angle sensor according to claim 1, wherein The base is fixed to the screw rod by threaded connection or snap-fit.

6. The bolt looseness angle sensor according to claim 1, wherein The monitoring module includes a circuit board, a monitoring element, and a connector. The circuit board is fixed to the housing, the monitoring element is mounted on the circuit board, and the connector is electrically connected to the circuit board.

7. The bolt loosening angle sensor according to claim 6, wherein The connector includes a male and a female connector that are compatible with each other, for direct connection with an adjacent bolt loosening angle sensor; the monitoring module also includes two cables, with the male or female connector of the connector connected to the circuit board at both ends of the two cables respectively; the surfaces of the housing and the cover plate that are in contact with each other are respectively provided with a first cable groove and a second cable groove, and the first cable groove and the second cable groove are respectively provided with a first holding part and a second holding part for holding the cable sheath.

8. The bolt loosening angle sensor as described in claim 6, characterized in that, The connector is specifically an onboard connector, which is mounted on a circuit board, and the housing is provided with a mounting groove that exposes the onboard connector.

9. The bolt loosening angle sensor as described in claim 6, characterized in that, The upper surface of the housing is provided with a circuit board groove for matching the circuit board, and the cover plate is placed on the upper surface of the housing to form a cavity for fixing the monitoring module; or the lower surface of the housing is provided with a circuit board groove for matching the circuit board, and the cover plate is placed on the lower surface of the housing to form a cavity for fixing the monitoring module.

10. The bolt loosening angle sensor as described in claim 9, characterized in that, The cover plate is secured by screws and / or clips.

11. The bolt loosening angle sensor as described in claim 9, characterized in that, The circuit board has lugs at both ends, and the circuit board groove has a side groove corresponding to the lugs; each lug has a screw mounting through hole, and the outer shell has a screw hole corresponding to the screw mounting through hole, so that the screw can be screwed into the screw hole through the screw mounting through hole.

12. The bolt loosening angle sensor as described in claim 6, characterized in that, The circuit board has a notch on one side to serve as a direction indicator; the cavity is filled with insulating adhesive for encapsulating the monitoring module.

13. The bolt loosening angle sensor as described in claim 6, characterized in that, The monitoring element is a TMR sensitive chip that can sense the direction of the magnetic field and convert it into a resistance value; the circuit board also includes a microcontroller module, which stores the sensor's identification information.

14. The bolt loosening angle sensor as described in claim 6, characterized in that, The monitoring module also includes an indicator light mounted on the circuit board for displaying the working status of the sensor and a zeroing device for setting the initial angle signal of the sensor to zero. The indicator light and the zeroing device are exposed outside the housing. The cover plate has multiple device through holes, corresponding to the zeroing device and the indicator light respectively, so that the zeroing device and the indicator light are exposed, while providing a potting channel.

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