Nut looseness symptom monitoring method and intelligent sensor

Abstract

The invention discloses a nut looseness symptom monitoring method and an intelligent sensor. The intelligent sensor comprises a first component and a second component. According to the nut looseness symptom monitoring method and the intelligent sensor, a first part comprises a sensor shell, a second part comprises a nut, a containing cavity is formed in the bottom of the sensor shell, the nut is arranged in the containing cavity, a circuit board groove is formed in the inner side of the upper portion of the sensor shell, and a circuit board matched with the circuit board groove is arranged in the circuit board groove; a magnetic direction sensing chip is arranged on the circuit board, a dial switch is installed on the side wall of the top of the sensor shell, penetrating holes are symmetrically formed in the front side and the rear side of the top of the sensor shell, aviation plugs are installed at the penetrating holes, and fixing jackscrews are symmetrically connected to the four sides, corresponding to the containing cavity, of the sensor shell in a threaded mode. The mounting cavity is internally provided with a magnet, the opening of the mounting cavity is covered with a magnet cover plate, the sensor is high in test precision, simple to mount and convenient to maintain, the cost can be effectively reduced, and the position of the loosened nut can be quickly positioned.

Description

Technical Field

[0001] This invention relates to the field of nut monitoring technology, specifically a method for monitoring signs of nut loosening and an intelligent sensor. Background Technology

[0002] High-strength bolts and nuts are widely used to fasten flanges on various structures, such as steel bridges, wind turbine blade roots and towers, and transmission towers. Under lateral, longitudinal, and torsional forces, the preload between the bolts and nuts on the flange can easily decrease. When the preload between the nut and bolt is lost to a certain extent, it can cause relative angular rotation between them—commonly known as nut loosening.

[0003] If a loose nut is not detected in time, it can cause the bolt to break or even the fan to collapse, posing a huge threat to property and personal safety.

[0004] Regularly inspecting the scale lines between bolts and nuts for misalignment is currently the standard method for detecting loose nuts. However, this method cannot guarantee real-time accuracy, is labor-intensive, and is prone to human error.

[0005] One method indirectly identifies nut loosening by monitoring changes in bolt tension and pressure using ultrasonic waves. This method calculates the time difference of ultrasonic wave reflection within the bolt based on the difference in the transmission rate of ultrasonic waves between the bolt and nut in a tightened and loose state, thus determining the current bolt tension and pressure. The advantage of this method is that it can measure the tension and pressure on the bolt while monitoring nut loosening; the disadvantages are high monitoring cost, poor consistency, and inability to accurately measure the nut loosening angle. Sensors are often installed using adhesive bonding, requiring removal to apply torque to the bolt later, making installation cumbersome and inefficient.

[0006] One method involves monitoring the axial stress of the bolt using strain gauges and calculating the degree of looseness between the bolt and nut based on the stress values. The advantage of this method is that it can directly monitor the axial stress value of the bolt while simultaneously monitoring nut looseness. The disadvantage is that a groove needs to be pre-cut in the bolt to embed the strain gauge, making construction very cumbersome, and the groove damages the bolt's structure, affecting its strength.

[0007] One method involves indirectly calculating nut loosening by monitoring flange gap displacement. This method assumes that a change in the monitored flange gap indicates that some bolts have loosened. The advantage of this method is that it can detect the approximate loosening of all nuts based on a small number of monitoring points. The disadvantage is that if only a few nuts on the flange are loose, while other nearby nuts remain tight, the flange gap will not change. Furthermore, once the flange gap widens, it indicates that multiple nuts have become significantly loose. Therefore, this method can only identify cases of severely loose nuts.

[0008] Therefore, a method for monitoring signs of loose nuts and an intelligent sensor are proposed to optimize the existing technology. Summary of the Invention

[0009] The purpose of this invention is to provide a method for monitoring signs of loose nuts and an intelligent sensor to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A method for monitoring signs of nut loosening and an intelligent sensor include a first component and a second component. The first component includes a sensor housing, and the second component includes a nut. The bottom of the sensor housing has a cavity, and the nut is disposed within the cavity. The upper inner side of the sensor housing has a circuit board groove, and a circuit board adapted to the groove is disposed within the groove. A magnetic direction sensing chip is disposed on the circuit board. A DIP switch is installed on the top sidewall of the sensor housing. Symmetrical through holes are provided on the front and rear sides of the top of the sensor housing, and a connector is installed at the through holes. Fixed set screws are symmetrically threaded on the four sides of the cavity corresponding to the sensor housing. An installation cavity is provided on the top inner side of the nut, and a magnet is disposed within the installation cavity. A magnet cover is provided at the opening of the installation cavity.

[0012] As a further aspect of the present invention: the top surface of the sensor housing is provided with a sealing groove, and a sealing O-ring is provided in the sealing groove.

[0013] As a further embodiment of the present invention: the top surface of the sensor housing is provided with an upper cover, and an upper cover fixing screw passes through the upper cover. The upper cover fixing screw is inserted into the sensor housing and is threadedly connected to the sensor housing.

[0014] As a further embodiment of the present invention: the circuit board has symmetrically formed fixing holes, and a circuit board fixing screw passes through the fixing hole. The circuit board fixing screw is inserted into the sensor housing and is threadedly connected to the sensor housing.

[0015] As a further embodiment of the present invention: the sensor housing is sleeved on the outside of the nut, and the nut is threadedly connected to the head of the bolt.

[0016] A method for monitoring signs of loose nuts, the method comprising the following steps:

[0017] Step 1: Solder the cable to the aviation connector and install it onto the sensor housing. Install the other end with a quick connector and install it onto the circuit board to limit the cable movement.

[0018] Step 2: Place the circuit board flat in the circuit board groove on the sensor housing, and screw the two circuit board fixing screws into the sensor housing along the fixing holes on the circuit board to achieve a fixed connection between the circuit board and the sensor housing; then pour in sealant to completely cover the circuit board and the soldered cable positions to achieve sensor sealing and insulation.

[0019] Step 3: Clean the surface of the sensor housing and place the sealing O-ring into the sealing groove of the sensor housing. Align the countersunk hole of the upper cover with the threaded hole of the sensor housing and fix the sensor housing to the upper cover with the upper cover fixing screws.

[0020] Step 4: Secure the nut to the end of the bolt, cover the outside of the sensor housing with the nut, leaving a gap between the nut and the sensor housing. Install the fixing screw into the threaded hole on the sensor housing, and tighten the fixing screw after installing it onto the nut to prevent it from falling off.

[0021] Step 5: When the nut rotates or vibrates relative to the magnet, the nut position remains unchanged, and the nut drives the sensor housing to rotate together. The circuit board contains a magnetic direction sensing chip, which can sense the direction of the relative magnetic field with the magnet in real time.

[0022] Step Six: When the first component and the second component rotate relative to each other, the signal output by the magnetic direction sensing chip of the first component will change proportionally. This change is equal to the change in the rotation angle of the nut relative to the bolt. Therefore, the nut loosening angle can be monitored. Multiple sensors are connected in series via a 485 bus.

[0023] Step 7: When tightening the bolts, it is inevitable to disassemble and reassemble the smart sensor for monitoring the signs of nut loosening. To avoid data jumps caused by secondary installation, the smart sensor for monitoring the signs of nut loosening is equipped with a DIP switch. Before disassembly, the DIP switch is turned to on, and after secondary installation, the DIP switch is turned to off. The sensor will match the current angle with the historical angle and transmit the original angle in the new position. This design can avoid the impact of multiple initializations on the continuity of long-term observation data.

[0024] As a further aspect of the present invention, the method also includes an algorithm one for analyzing its own data and identifying signs of nut loosening, an algorithm two for analyzing data from other sensors on the 485 bus and further identifying signs of nut loosening, and an algorithm three for analyzing the long-term trend of the nut loosening angle.

[0025] As a further aspect of the present invention: the first algorithm judges the angle jump situation in real time during the monitoring process. If the angle jumps periodically for a long time and the frequency is close to the natural frequency of the flange vibration, the nut monitored by the sensor is considered to have signs of loosening.

[0026] As a further aspect of this invention: In Algorithm 2, multiple intelligent sensors for monitoring the signs of nut loosening are often installed within a monitoring system. The sensors themselves are connected in series via a 485 bus. Under this communication mechanism, the sensors can acquire data from sources other than themselves. Algorithm 2 is used to analyze the data from other sensors to determine if there are any signs of loosening. If most sensors on the bus do not show signs of loosening, and considering the conclusion of Algorithm 1, if the sensor itself shows signs of loosening, it issues a warning message to the host computer software, informing it that the nut is showing signs of loosening. The user can then conduct targeted inspections based on the prompts, controlling the risk at its initial stage. This invention introduces AI intelligent analysis, which, compared to the method of only issuing an alarm when the nut actually becomes loose, provides an earlier warning time.

[0027] As a further solution of the present invention: When analyzing the long-term trend of nut loosening, users often need to analyze data over a relatively long period of time. If the amount of data is too large, it will inevitably increase the pressure of subsequent data analysis. Algorithm 3 is used to simplify the processing of a large amount of raw data. The processing method is to sort the raw data from largest to smallest, remove the largest 10% and the smallest 10%, and take the median of the remaining data as the feature value of this period. The data is stored locally by the intelligent sensor for monitoring nut loosening symptoms and transmitted to the host computer in real time. Through Algorithm 3, the raw data can be compressed and the long-term analysis of the nut loosening trend can be realized locally by the sensor.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. The sensor of this invention has high testing accuracy, is easy to install and maintain, can effectively reduce costs, and can quickly locate the position of loose nuts.

[0030] 2. The sensor of this invention has two complementary connectors, which can meet the loosening detection requirements of high-strength connecting bolt groups of wind turbine towers or hubs with ring distribution, and reduce the wiring length.

[0031] 3. The sensor of this invention consists of two components. For the maintenance of loose high-strength connecting bolts, when the sensor detects that the nut is loose, it is only necessary to disassemble the nut fixing assembly installed on the loose nut to tighten the loose bolt. After tightening, the sensor's fixing screw can be fixed back to the nut to continue monitoring the nut's looseness. Therefore, this sensor can be reused.

[0032] 4. The sensor of this invention 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, thus ensuring high safety. Attached Figure Description

[0033] Figure 1This is a schematic diagram of a method for monitoring signs of loose nuts and a smart sensor.

[0034] Figure 2 This is a cross-sectional view of a method for monitoring signs of nut loosening and an intelligent sensor.

[0035] Figure 3 This is a schematic diagram of a method for monitoring signs of loose nuts and a smart sensor for fixing a circuit board.

[0036] Figure 4 This is a schematic diagram of a nut assembly in a method for monitoring signs of nut loosening and a smart sensor.

[0037] Figure 5 This is a schematic diagram of component one and component two in a method for monitoring signs of nut loosening and a smart sensor.

[0038] In the diagram: 1. Top cover; 2. Circuit board; 3. Sealing O-ring; 4. Sensor housing; 5. Nut; 6. Magnet; 7. Magnet cover plate; 8. Fixing screw; 9. Aviation connector; 10. Circuit board fixing screw; 11. Top cover fixing screw; 12. Nut; 13. Bolt; 14. DIP switch. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1:

[0041] Please see Figures 1-5 In this embodiment of the invention, a method for monitoring signs of nut loosening and an intelligent sensor are provided, including a first component and a second component. The first component includes a sensor housing 4, and the second component includes a nut 5. The bottom of the sensor housing 4 is provided with a cavity, and the nut 5 is disposed in the cavity. The upper inner side of the sensor housing 4 is provided with a circuit board groove, and a circuit board 2 adapted to it is disposed in the circuit board groove. A magnetic direction sensing chip is disposed on the circuit board 2. A DIP switch 14 is installed on the top sidewall of the sensor housing 4. The front and rear sides of the top of the sensor housing 4 are symmetrically provided with through holes, and a connector 9 is installed at the through holes. The sensor housing 4 is symmetrically threaded with fixing screws 8 on the four sides corresponding to the cavity. The top inner side of the nut 5 is provided with a mounting cavity, and a magnet 6 is disposed in the mounting cavity. A magnet cover plate 7 is provided at the opening of the mounting cavity.

[0042] The top surface of the sensor housing 4 is provided with a sealing groove, and a sealing O-ring 3 is provided inside the sealing groove.

[0043] The top surface of the sensor housing 4 is provided with an upper cover 1, and an upper cover fixing screw 11 passes through the upper cover 1. The upper cover fixing screw 11 is inserted into the sensor housing 4 and is threadedly connected to the sensor housing 4.

[0044] The circuit board 2 has symmetrically arranged fixing holes, and the circuit board fixing screws 10 pass through the fixing holes. The circuit board fixing screws 10 are inserted into the sensor housing 4 and are threadedly connected to the sensor housing 4.

[0045] The sensor housing 4 is fitted onto the outside of the nut 12, and the nut 5 is threaded onto the head of the bolt 13.

[0046] A method for monitoring signs of loose nuts, the steps of which are as follows:

[0047] Step 1: Solder the cable to the aviation connector 9 and install it onto the sensor housing 4. Install the other end with a quick connector and install it onto the circuit board 2 to limit the cable movement.

[0048] Step 2: Place the circuit board 2 flat in the circuit board groove provided in the sensor housing 4, and screw the two circuit board fixing screws 10 into the sensor housing 4 along the fixing holes provided in the circuit board 2 to achieve a fixed connection between the circuit board 2 and the sensor housing 4; then pour in sealant to completely cover the circuit board 2 and the cable soldering positions to achieve sensor sealing and insulation.

[0049] Step 3: Clean the surface of the sensor housing 4, and place the sealing O-ring 3 into the sealing groove of the sensor housing 4. Align the countersunk hole of the upper cover 1 with the threaded hole of the sensor housing 4, and fix the sensor housing 4 and the upper cover 1 with the upper cover fixing screw 11.

[0050] Step 4: Secure the nut 5 to the end of the bolt 13, cover the outside of the nut 12 with the sensor housing 4, and leave a gap between the nut 5 and the sensor housing 4 to prevent the nut 12 from loosening and coming into contact with the housing, thus avoiding friction. Install the fixing screw 8 into the threaded hole of the sensor housing 4, and tighten the fixing screw 8 after installing it onto the nut 12 to prevent it from falling off.

[0051] Step 5: When the nut 12 rotates or vibrates relative to the sensor housing 4, the position of the nut 5 remains unchanged. The nut 12 drives the sensor housing 4 to rotate together. The circuit board 2 contains a magnetic direction sensing chip, which can sense the direction of the relative magnetic field with the magnet 6 in real time.

[0052] Step 6: When the first component and the second component rotate relative to each other, the signal output by the magnetic direction sensing chip of the first component will change proportionally. This change is equal to the change in the rotation angle of the nut 12 relative to the bolt 13. Therefore, the loosening angle of the nut 12 can be monitored. Multiple sensors are connected in series via a 485 bus.

[0053] Step 7: When applying torque to bolt 13, it is inevitable to disassemble and reassemble the smart sensor for monitoring the signs of nut loosening. To avoid data jumps caused by secondary installation, the smart sensor for monitoring the signs of nut loosening is equipped with a DIP switch 14. Before disassembly, switch 14 is turned to on. After secondary installation, switch 14 is turned to off. The sensor will match the current angle with the historical angle and transmit the original angle in the new position. This design can avoid the impact of multiple initializations on the continuity of long-term observation data.

[0054] The method also includes Algorithm 1 for analyzing its own data and identifying signs of nut loosening, Algorithm 2 for analyzing data from other sensors on the 485 bus and further identifying signs of nut loosening, and Algorithm 3 for analyzing the long-term trend of nut loosening angle.

[0055] Algorithm 1 determines the angle jump situation in real time during the monitoring process. If the angle jumps periodically for a long time and the frequency is close to the natural frequency of the flange vibration, it is assessed that the nut 12 monitored by the sensor has signs of loosening.

[0056] In Algorithm 2, multiple intelligent sensors for detecting loose nuts are often installed within a monitoring system. The sensors themselves are connected in series via a 485 bus. Under this communication mechanism, the sensors can acquire data from sources other than themselves. Algorithm 2 is used to analyze the data from other sensors to see if there are any signs of loosening. If most sensors on the bus do not show signs of loosening, combined with the conclusion of Algorithm 1, if the sensor itself shows signs of loosening, it issues a warning message to inform the host computer software that nut 12 shows signs of loosening. The user can then conduct targeted inspections based on the prompts, controlling the risk at its initial stage. This invention introduces AI intelligent analysis, which, compared to the method of triggering an alarm only after nut 12 actually becomes loose, provides an earlier warning time.

[0057] When analyzing the long-term trend of nut 12 loosening, users of Algorithm 3 often need to analyze data over a relatively long period. If the data volume is too large, it will inevitably increase the pressure of subsequent data analysis. Algorithm 3 is used to simplify the processing of a large amount of raw data. The processing method is to sort the raw data from largest to smallest, remove the largest 10% and the smallest 10%, and take the median of the remaining data as the feature value of this period. The data is stored locally by the smart sensor for monitoring nut loosening symptoms and transmitted to the host computer in real time. Through Algorithm 3, the raw data can be compressed and the long-term analysis of the nut 12 loosening trend can be realized locally on the sensor.

[0058] 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.

[0059] Example 2:

[0060] In this embodiment of the invention, a method for monitoring signs of nut loosening and an intelligent sensor are provided, wherein component two is fixed by adhesive bonding.

[0061] Example 1:

[0062] In this embodiment of the invention, a method for monitoring signs of nut loosening and an intelligent sensor are provided, wherein component one is fixed by a snap ring or a metal strap.

[0063] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A smart sensor for monitoring signs of nut loosening, comprising a first component and a second component, characterized in that: The first component includes a sensor housing (4), and the second component includes a nut (5). The bottom of the sensor housing (4) is provided with a cavity, and the nut (5) is located in the cavity. The upper inner side of the sensor housing (4) is provided with a circuit board groove, and a circuit board (2) adapted to it is provided in the circuit board groove. A magnetic direction sensing chip is provided on the circuit board (2). A DIP switch (14) is installed on the top sidewall of the sensor housing (4). The front and rear sides of the top of the sensor housing (4) are symmetrically provided with through holes, and a connector (9) is installed at the through holes. The sensor housing (4) is symmetrically threaded with fixing screws (8) on the four sides corresponding to the cavity. The top inner side of the nut (5) is provided with a mounting cavity, and a magnet (6) is provided in the mounting cavity. A magnet cover plate (7) is provided at the opening of the mounting cavity.

2. The intelligent sensor for monitoring signs of nut loosening according to claim 1, characterized in that: The top surface of the sensor housing (4) is provided with a sealing groove, and a sealing O-ring (3) is provided in the sealing groove.

3. The intelligent sensor for monitoring signs of nut loosening according to claim 1, characterized in that: The top surface of the sensor housing (4) is covered with an upper cover (1), and an upper cover fixing screw (11) passes through the upper cover (1). The upper cover fixing screw (11) is inserted into the sensor housing (4) and threadedly connected to the sensor housing (4).

4. The intelligent sensor for monitoring signs of nut loosening according to claim 1, characterized in that: The circuit board (2) has symmetrical fixing holes, and a circuit board fixing screw (10) passes through the fixing hole. The circuit board fixing screw (10) is inserted into the sensor housing (4) and is threadedly connected to the sensor housing (4).

5. The intelligent sensor for monitoring signs of nut loosening according to claim 1, characterized in that: The sensor housing (4) is fitted onto the outside of the nut (12), and the nut (5) is threaded onto the head of the bolt (13).

6. A method for monitoring signs of loose nuts, characterized in that: The method steps are as follows: Step 1: Solder the cable to the aviation connector (9) and install it onto the sensor housing (4). Install the other end with a quick connector and install it onto the circuit board (2) to limit the cable position. Step 2: Place the circuit board (2) flat in the circuit board groove set in the sensor housing (4), and screw the two circuit board fixing screws (10) into the sensor housing (4) along the fixing holes set in the circuit board (2) to achieve a fixed connection between the circuit board (2) and the sensor housing (4); then pour in sealant to cover the circuit board (2) and the cable welding position to achieve sensor sealing and insulation. Step 3: Clean the surface of the sensor housing (4), and put the sealing O ring (3) into the sealing groove of the sensor housing (4). Align the countersunk hole of the upper cover (1) with the threaded hole of the sensor housing (4), and fix the sensor housing (4) and the upper cover (1) with the upper cover fixing screw (11). Step 4: Tighten the nut (5) to the end of the bolt (13), cover the outside of the nut (12) with the sensor housing (4), there is a gap between the nut (5) and the sensor housing (4), install the fixing screw (8) into the threaded hole of the sensor housing (4), install it on the nut (12), and tighten the fixing screw (8) to keep it from falling off. Step 5: When the nut (12) rotates or vibrates relative to the sensor housing (4), the position of the nut (5) remains unchanged. The nut (12) drives the sensor housing (4) to rotate together. The circuit board (2) contains a magnetic direction sensing chip, which can sense the relative magnetic field direction with the magnet (6) in real time. Step 6: When the first component and the second component rotate relative to each other, the signal output by the magnetic direction sensing chip of the first component will change proportionally. This change is equal to the change in the rotation angle of the nut (12) relative to the bolt (13). Therefore, the loosening angle of the nut (12) can be monitored. Multiple sensors are connected in series via a 485 bus. Step 7: When applying torque to the bolt (13), it is inevitable to disassemble and reassemble the smart sensor for monitoring the signs of nut loosening. To avoid data jumps caused by secondary installation, the smart sensor for monitoring the signs of nut loosening is equipped with a DIP switch (14). Before disassembly, the DIP switch (14) is turned to on. After secondary installation, the DIP switch (14) is turned to off. The sensor will match the current angle with the historical angle and transmit the original angle in the new position. This design can avoid the impact of multiple initializations on the continuity of long-term observation data.

7. The method for monitoring signs of nut loosening according to claim 6, characterized in that: The method also includes Algorithm 1 for analyzing its own data and identifying signs of nut loosening, Algorithm 2 for analyzing other sensor data on the 485 bus and further identifying signs of nut loosening, and Algorithm 3 for analyzing the long-term trend of nut loosening angle.

8. The method for monitoring signs of nut loosening according to claim 7, characterized in that: The algorithm 1 judges its own angle jump in real time during the monitoring process. If the angle jumps periodically for a long time and the frequency is close to the natural frequency of the flange vibration, it is evaluated that the nut (12) monitored by the sensor has signs of loosening.

9. The method for monitoring signs of nut loosening according to claim 7, characterized in that: Algorithm 2 is used to analyze whether there are signs of loosening in the data of other sensors. If most sensors on the bus do not show signs of loosening, combined with the conclusion of Algorithm 1, if there are signs of loosening in the sensor itself, the sensor will issue a warning message to inform the host computer software that the nut (12) has signs of loosening. The user can then conduct a targeted inspection based on the prompt message.

10. A method for monitoring signs of nut loosening according to claim 7, characterized in that: Algorithm 3 is used to simplify a large amount of raw data. The processing method is to sort the raw data from largest to smallest, remove the largest 10% and the smallest 10%, and take the median of the remaining data as the feature value of this period. The data is then stored locally by the smart sensor for monitoring the signs of loose nuts and transmitted to the host computer in real time.

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