A method for measuring the sinking amount of a stern shaft outside the hull of a ship

Abstract

This invention relates to the field of ship propeller shaft system technology, specifically to a method for measuring the stern shaft subsidence of a ship. Based on an electromagnetic ultrasonic measurement scheme, this invention measures the stern shaft subsidence of a ship, enabling continuous measurement and monitoring of the wear of the stern shaft tube bearing slats. This allows for real-time monitoring of the stern shaft tube bearing wear, improving the safety and reliability of the shafting system, preventing sudden failures, and extending the bearing's service life. This invention allows for continuous measurement of the stern shaft subsidence of a ship without the need for divers to manually measure it near the stern, significantly saving labor costs and improving the safety and accuracy of the measurement. Furthermore, this invention prevents the ranging sensor from directly contacting seawater, resulting in good environmental adaptability and avoiding the adverse consequences of direct sensor contact with seawater, such as measurement errors, corrosion and aging of test elements, and short service life. This significantly improves the reliability of the measurement system, has broad application prospects, and is easy to promote.

Description

Technical Field

[0001] This invention relates to the field of ship propeller shaft system technology, and specifically to a method for measuring the subsidence of the ship's stern shaft. Background Technology

[0002] The stern tube bearing is located outside the ship's hull and is exposed to complex and harsh environments such as swells, corrosion, and silt. When the shafting is running, the stern tube bearing is affected by factors such as the cantilever load of the propeller and propeller vibration, making it the bearing with the greatest stress in the power shafting. In addition, the load on the stern tube bearing is characterized by heavy load, unevenness, and time-varying characteristics due to changes in operating conditions such as start-up, shutdown, low speed, and acceleration. The unevenness of the load will affect the formation of the lubricating water film between the bearing and the rotor, causing it to be in a state of "boundary lubrication" or "mixed lubrication", or even direct contact, which can easily lead to bearing wear.

[0003] Because the stern tube bearing is located underwater at the stern, it is difficult to measure bearing wear. Existing methods for measuring stern tube bearing wear mainly involve measuring bearing clearance after the ship enters dry dock, or sending divers to the stern bottom while the ship is anchored to measure the stern tube subsidence with a depth gauge, and then calculating the bearing slat wear value. However, these existing methods do not allow for real-time monitoring of the stern tube bearing's wear status, which can easily lead to sudden malfunctions, and the timeliness and accuracy of the measurements are difficult to guarantee. Therefore, there is an urgent need to research a method for measuring the subsidence of the stern tube bearing overboard, to guide the development and installation of a device for measuring the stern tube bearing slat wear overboard, enabling continuous measurement and monitoring of stern tube bearing slat wear, thus allowing for real-time understanding of the stern tube bearing wear condition, improving the safety and reliability of shafting operation, preventing sudden malfunctions, and extending bearing service life. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for measuring the stern shaft subsidence of a ship, which can realize the continuous measurement and monitoring of the wear of the stern tube bearing slats, so as to grasp the wear of the stern tube bearing in real time, improve the safety and reliability of shafting operation, avoid sudden failures, and extend the service life of the bearing.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for measuring the stern shaft subsidence of a ship mainly includes the following steps:

[0007] Step S1, Measurement component installation: The outboard stern shaft sinking measurement module is pre-embedded and installed on the bottom side of the stern shaft tube at the stern of the ship, and the outboard stern shaft sinking measurement module is electrically connected to the signal processing and display system in the cabin through the signal cable pre-embedded in the hull.

[0008] The measuring end of the outboard stern shaft sinking measurement module is covered with a tin-based alloy material layer, and the outer surface of the tin-based alloy material layer is flush with the surface of the bottom side strip of the stern shaft tube bearing and in contact with the lower surface of the outboard stern shaft. The wear resistance coefficient of the tin-based alloy material layer is lower than that of the bottom side strip of the stern shaft tube bearing.

[0009] Step S2, Stern shaft sinking measurement: During the rotation of the ship's outboard stern shaft, the slat surface on the bottom side of the stern shaft tube bearing and the outer surface of the tin-based alloy material layer are simultaneously worn, resulting in sinking. The ship's outboard stern shaft sinking measurement signal is obtained by real-time monitoring the distance signal between the measuring end of the outboard stern shaft sinking measurement module and the lower surface of the ship's outboard stern shaft.

[0010] Step S3, Measurement signal processing: The signal processing module of the signal processing and display system processes the sinking measurement signal sent by the outboard stern shaft sinking measurement module to obtain the measured value of the outboard stern shaft sinking.

[0011] Step S4, Measurement value display and storage: The measurement value of the ship's stern shaft subsidence is displayed and stored in real time through the display and storage module of the signal processing and display system.

[0012] Preferably, the outboard stern shaft sinking measurement module includes an electromagnetic ultrasonic sensor probe 5 pre-embedded and installed on the bottom side of the stern shaft tube 3 at the stern of the ship. The bottom end of the electromagnetic ultrasonic sensor probe 5 is provided with an AD conversion module 6, and the AD conversion module 6 is electrically connected to the signal processing and display system in the cabin through a signal cable 7 pre-embedded in the hull.

[0013] Preferably, the electromagnetic ultrasonic sensor probe 5 is covered with a tin-based alloy material layer 4. After the top of the electromagnetic ultrasonic sensor probe 5 is inserted into the copper sleeve 2 of the stern tube bearing, the outer surface of the tin-based alloy material layer 4 is flush with the upper surface of the bottom side plate 1 of the stern tube bearing, and the upper surface of the bottom side plate 1 of the stern tube bearing and the outer surface of the tin-based alloy material layer 4 are simultaneously in contact with the lower surface of the ship's stern shaft.

[0014] Preferably, during the process of the stern shaft of the ship sinking due to wear on the upper surface of the bottom side plate 1 of the stern shaft tube bearing, the outer surface of the tin-based alloy material layer 4 is simultaneously worn, so that the outer surface of the tin-based alloy material layer 4 is always flush with the upper surface of the bottom side plate 1 of the stern shaft tube bearing. The ultrasonic sensor probe 5 monitors the change in distance signal between the probe end and the lower surface of the ship's stern shaft in real time, and obtains the measurement signal of the sinking amount of the ship's stern shaft.

[0015] Preferably, the signal processing and display system inside the cabin includes a signal processing module 8 and a display and storage module 9. The signal processing module 8 is used to process the sinking measurement signal sent by the outboard stern shaft sinking measurement module to obtain the measured value of the outboard stern shaft sinking.

[0016] Preferably, the display and storage module 9 is used to display and store the measured value of the ship's stern shaft subsidence in real time.

[0017] Specifically, the data processing includes:

[0018] Step S31, Signal reception: Receive the sinking measurement signal sent by the outboard stern shaft sinking measurement module in real time;

[0019] Step S32, Signal comparison and sampling: The effective signal and noise in the sinking measurement signal are distinguished by a preset comparator, the effective range of the measurement signal is sampled, and noise is removed;

[0020] Step S33, Waveform Delay Processing and Storage: The time deviation of the transmitted ultrasonic waveform is calibrated by the digital delay unit, and the sampled digital waveform data is stored;

[0021] Step S34, Echo Judgment: Identify the valid echo signal and interference signal in the received echo, and remove the interference signal;

[0022] Step S35, acoustic time value calculation: Based on the time from ultrasonic wave transmission to receiving the echo, calculate and determine the real-time distance between the probe tip and the lower surface of the ship's stern shaft.

[0023] Step S36, Signal Output: Output the change in the real-time distance value as the measured value of the ship's outboard stern shaft subsidence.

[0024] Preferably, the preset comparator compares the received analog signal with a preset threshold: when the signal amplitude exceeds the preset threshold, it is considered a valid signal; when the signal amplitude is lower than the preset threshold, it is considered noise.

[0025] Preferably, the echo determination specifically involves: based on the waveform correlation between the echo and the transmitted wave, comparing the waveform characteristics of the received signal and the transmitted signal, and determining that the echo signal is valid when the correlation coefficient exceeds the correlation threshold.

[0026] Preferably, the display and storage module 9 displays the measured value of the ship's stern shaft subsidence in real time on the screen for operators to monitor, and stores the measured value of the ship's stern shaft subsidence in the storage medium in real time.

[0027] Compared with the prior art, the present invention has the following main advantages:

[0028] 1. This invention uses an electromagnetic ultrasonic measurement method to measure the sinking of the stern shaft outside the ship, which enables continuous measurement and monitoring of the wear of the stern tube bearing slats, so as to grasp the wear of the stern tube bearing in real time, improve the safety and reliability of shafting operation, avoid sudden failures, and extend the service life of the bearing.

[0029] 2. This invention can continuously measure the stern shaft subsidence of a ship without the need for divers to dive into the bottom of the stern for manual measurement, which greatly saves labor costs and improves the safety and accuracy of the measurement.

[0030] 3. This invention allows the ranging sensor to avoid direct contact with seawater, resulting in good environmental adaptability. It avoids adverse consequences such as measurement errors, corrosion and aging of test elements, and short service life caused by direct contact between the sensor and the seawater environment. This significantly improves the reliability of the measurement system, and its application prospects are broad and it is easy to promote. Attached Figure Description

[0031] Figure 1 This is an overall flowchart of the method for measuring the stern shaft subsidence of a ship in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the arrangement of the stern shaft subsidence measurement component of a ship in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the stern shaft subsidence measurement module in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the signal processing and display system in an embodiment of the present invention.

[0035] In the diagram: 1-Stern tube bearing bottom side plate; 2-Stern tube bearing copper sleeve; 3-Stern tube; 4-Tin-based alloy material layer; 5-Electromagnetic ultrasonic sensor probe; 6-AD conversion module; 7-Signal cable; 8-Signal processing module; 9-Display and storage module. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0037] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0038] In this invention, unless otherwise expressly specified and limited, 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 indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0039] Example 1: This example provides a method for measuring the stern shaft subsidence of a ship, such as... Figure 1 As shown, the main steps include the following:

[0040] Step S1, Measurement component installation: The outboard stern shaft sinking measurement module is pre-embedded and installed on the bottom side of the stern shaft tube at the stern of the ship, and the outboard stern shaft sinking measurement module is electrically connected to the signal processing and display system in the cabin through the signal cable pre-embedded in the hull.

[0041] The measuring end of the outboard stern shaft sinking measurement module is covered with a tin-based alloy material layer, and the outer surface of the tin-based alloy material layer is flush with the surface of the bottom side strip of the stern shaft tube bearing and in contact with the lower surface of the outboard stern shaft. The wear resistance coefficient of the tin-based alloy material layer is lower than that of the bottom side strip of the stern shaft tube bearing.

[0042] Step S2, Stern shaft sinking measurement: During the rotation of the ship's outboard stern shaft, the slat surface on the bottom side of the stern shaft tube bearing and the outer surface of the tin-based alloy material layer are simultaneously worn, resulting in sinking. The ship's outboard stern shaft sinking measurement signal is obtained by real-time monitoring the distance signal between the measuring end of the outboard stern shaft sinking measurement module and the lower surface of the ship's outboard stern shaft.

[0043] Step S3, Measurement signal processing: The signal processing module of the signal processing and display system processes the sinking measurement signal sent by the outboard stern shaft sinking measurement module to obtain the measured value of the outboard stern shaft sinking.

[0044] Step S4, Measurement value display and storage: The measurement value of the ship's stern shaft subsidence is displayed and stored in real time through the display and storage module of the signal processing and display system.

[0045] Furthermore, the outboard stern shaft sinking measurement module includes an electromagnetic ultrasonic sensor probe 5 pre-embedded and installed on the bottom side of the stern shaft tube 3 at the stern of the ship. The bottom end of the electromagnetic ultrasonic sensor probe 5 is provided with an AD conversion module 6, and the AD conversion module 6 is electrically connected to the signal processing and display system in the cabin through a signal cable 7 pre-embedded in the hull.

[0046] Furthermore, the electromagnetic ultrasonic sensor probe 5 is covered with a tin-based alloy material layer 4. After the top of the electromagnetic ultrasonic sensor probe 5 is inserted into the copper sleeve 2 of the stern tube bearing, the outer surface of the tin-based alloy material layer 4 is flush with the upper surface of the bottom side plate 1 of the stern tube bearing. The upper surface of the bottom side plate 1 of the stern tube bearing and the outer surface of the tin-based alloy material layer 4 are simultaneously in contact with the lower surface of the ship's stern shaft.

[0047] Furthermore, during the process of the stern shaft wear and sinking of the upper surface of the bottom side plate 1 of the stern shaft tube bearing, the outer surface of the tin-based alloy material layer 4 is simultaneously worn, so that the outer surface of the tin-based alloy material layer 4 is always flush with the upper surface of the bottom side plate 1 of the stern shaft tube bearing. The ultrasonic sensor probe 5 monitors the change in distance signal between the probe end and the lower surface of the stern shaft in real time to obtain the measurement signal of the sinking of the stern shaft.

[0048] Furthermore, the signal processing and display system inside the cabin includes a signal processing module 8 and a display and storage module 9. The signal processing module 8 is used to process the sinking measurement signal sent by the outboard stern shaft sinking measurement module to obtain the measurement value of the outboard stern shaft sinking.

[0049] Furthermore, the display and storage module 9 is used to display and store the measured value of the ship's stern shaft subsidence in real time.

[0050] Specifically, the data processing includes:

[0051] Step S31, Signal reception: Receive the sinking measurement signal sent by the outboard stern shaft sinking measurement module in real time;

[0052] Step S32, Signal comparison and sampling: The effective signal and noise in the sinking measurement signal are distinguished by a preset comparator, the effective range of the measurement signal is sampled, and noise is removed;

[0053] Step S33, Waveform Delay Processing and Storage: The time deviation of the transmitted ultrasonic waveform is calibrated by the digital delay unit, and the sampled digital waveform data is stored;

[0054] Step S34, Echo Judgment: Identify the valid echo signal and interference signal in the received echo, and remove the interference signal;

[0055] Step S35, acoustic time value calculation: Based on the time from ultrasonic wave transmission to receiving the echo, calculate and determine the real-time distance between the probe tip and the lower surface of the ship's stern shaft.

[0056] Step S36, Signal Output: Output the change in the real-time distance value as the measured value of the ship's outboard stern shaft subsidence.

[0057] Furthermore, the preset comparator compares the received analog signal with a preset threshold: when the signal amplitude exceeds the preset threshold, it is considered a valid signal; when the signal amplitude is lower than the preset threshold, it is considered noise.

[0058] Furthermore, the echo determination specifically involves comparing the waveform characteristics of the received signal and the transmitted signal based on the waveform correlation between the echo and the transmitted wave. When the correlation coefficient exceeds the correlation threshold, the signal is determined to be a valid echo signal.

[0059] Furthermore, the display and storage module 9 displays the measured value of the ship's outboard stern shaft subsidence in real time on the screen for operators to monitor, and stores the measured value of the ship's outboard stern shaft subsidence in the storage medium in real time.

[0060] Example 2: This example also provides a method for measuring the subsidence of a ship's stern shaft outside the hull. The method uses electromagnetic ultrasonic measurement to measure the subsidence of the ship's stern shaft outside the hull. The basic principle is as follows:

[0061] Ultrasonic nondestructive testing (NDT) is a newly developed ranging technology. Electromagnetic ultrasound can transmit and receive sound waves without the probe making contact with the surface of the material being tested. During the testing process, electromagnetic ultrasound does not require a coupling agent as a sound wave transmission medium between the probe and the material being tested.

[0062] Electromagnetic ultrasonic thickness measurement utilizes the electromagnetic field generated by alternating current to induce eddy currents on the surface of the specimen. Under the action of the magnetic field of a permanent magnet, the eddy currents generate a force that causes mechanical vibration on the surface of the specimen, thereby generating ultrasonic waves. The ultrasonic waves propagate and reflect on the upper and lower surfaces of the specimen. The ultrasonic echoes generate current under the action of the magnetic field and are coupled to the receiving coil to generate an induced voltage. The thickness is measured based on the interval of the received echoes.

[0063] As ultrasound propagates perpendicular to the upper and lower surfaces within the specimen, it continuously cuts magnetic field lines during reflection and attenuation, generating eddy currents. Due to the attenuation of the magnetic field and the shielding effect of the upper surface of the specimen, the eddy currents generated inside the specimen are very small and difficult to be received by the receiving coil. However, at the upper surface of the specimen, due to its proximity to the receiving coil and the stronger magnetic field, the eddy currents are easily induced in the receiving coil, forming a periodic echo signal. The echo period is the sound time it takes for the sound wave to travel from the upper surface, be reflected by the lower surface, and return to the upper surface. Based on the sound time value, the thickness of the specimen can be calculated given the ultrasonic wave velocity.

[0064] This invention involves arranging an electromagnetic ultrasonic sensor at the bottom of the stern tube bearing. A low-hardness, easily worn special alloy material (in this example, a tin-based alloy containing 80-90% tin, 5-10% antimony, and 1-3% copper, with a low Brinell hardness, typically HB 15-40) is embedded in the stern tube bearing at the top of the sensor probe. When the shaft system rotates, the alloy material, along with the stern tube bearing, rubs against the stern tube bushing, ensuring that the outermost layer of the alloy material remains flush with the outer surface of the stern tube bearing slats. Furthermore, the abrasive particles generated after the alloy material wears are washed away by water flow, preventing any impact on the bearing slats. The electromagnetic ultrasonic sensor emits sound waves through the alloy material layer towards the lower surface of the stern tube and receives the reflected sound waves, thus measuring the change in the lower surface of the stern tube relative to an initial reference in real time. This allows for the real-time acquisition of the stern tube sinking signal. This electrical signal is transmitted back to the ship's hull via a pre-embedded line near the stern tube for processing, yielding the real-time measurement of the stern tube sinking.

[0065] like Figure 2 As shown, the outboard stern shaft sinking measurement component provided by the present invention mainly consists of an outboard stern shaft sinking measurement module and a signal processing and display system. The outboard stern shaft sinking measurement module is arranged on the bottom side of the stern shaft tube at the stern of the ship and is embedded inside the stern shaft tube. The monitoring signal is transmitted to the signal processing and display system inside the cabin through the laying of cables to complete the processing and display of the measurement signal.

[0066] like Figures 3-4 As shown, the working method of the outboard stern shaft sinking measurement component is as follows:

[0067] When the stern tube bearing operates in harsh environments, friction between the bearing and the stern tube bushing causes wear on the stern tube bearing slat 1, reducing its thickness. Simultaneously, the tin-based alloy material layer 4, which is less hard and more easily worn, also thins accordingly, while both maintain the same top height and curvature. Since the bottom of the stern tube bearing is tangent to both the stern tube bearing slat 1 and the tin-based alloy material layer 4, the bottom of the stern tube bearing will also decrease accordingly as these layers wear down. The outermost layer of the alloy material remains flush with the stern tube bearing. Furthermore, the abrasive particles generated by the wear of the alloy material are washed away by water flow, preventing damage to the bearing slats. The electromagnetic ultrasonic sensor probe 5 detects changes in the analog signal indicating the distance to the lower surface of the stern tube bearing. The AD conversion module 6 converts this analog information and transmits it to the signal processing and display system inside the cabin via signal cable 7.

[0068] After receiving the signal, the signal processing and display system inside the cabin performs the following steps: signal processing module 8 receives, compares, samples, performs waveform delay processing, waveform storage, echo judgment, sound time calculation, sound time value transmission, and signal output on the analog signal. Then, display and storage module 9 displays and stores the real-time data of the stern shaft subsidence. In this way, the measurement of the stern shaft subsidence can be automated, eliminating the need for divers to perform manual measurements, greatly improving work efficiency. This enables continuous measurement and monitoring of the ship's stern shaft subsidence, allowing for real-time monitoring of stern bearing wear and improving the safety and reliability of the shafting system.

[0069] Furthermore, all parts of this application that are not described in detail are the same as or implemented using existing technology.

[0070] In summary:

[0071] 1. This invention uses an electromagnetic ultrasonic measurement method to measure the sinking of the stern shaft outside the ship, which enables continuous measurement and monitoring of the wear of the stern tube bearing slats, so as to grasp the wear of the stern tube bearing in real time, improve the safety and reliability of shafting operation, avoid sudden failures, and extend the service life of the bearing.

[0072] 2. This invention can continuously measure the stern shaft subsidence of a ship without the need for divers to dive into the bottom of the stern for manual measurement, which greatly saves labor costs and improves the safety and accuracy of the measurement.

[0073] 3. This invention allows the ranging sensor to avoid direct contact with seawater, resulting in good environmental adaptability. It avoids adverse consequences such as measurement errors, corrosion and aging of test elements, and short service life caused by direct contact between the sensor and the seawater environment. This significantly improves the reliability of the measurement system, and its application prospects are broad and it is easy to promote.

[0074] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0075] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0076] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring the stern shaft subsidence of a ship, characterized in that, Includes the following steps: S1, Measurement component installation: The outboard stern shaft sinking measurement module is pre-embedded and installed on the bottom side of the stern shaft tube at the stern of the ship, and the outboard stern shaft sinking measurement module is electrically connected to the signal processing and display system in the cabin through the signal cable pre-embedded in the hull. The measuring end of the outboard stern shaft sinking measurement module is covered with a tin-based alloy material layer, and the outer surface of the tin-based alloy material layer is flush with the surface of the bottom side strip of the stern shaft tube bearing and in contact with the lower surface of the outboard stern shaft. The wear resistance coefficient of the tin-based alloy material layer is lower than that of the bottom side strip of the stern shaft tube bearing. S2, Stern shaft sinking measurement: During the rotation of the ship's outboard stern shaft, the slat surface on the bottom side of the stern shaft tube bearing and the outer surface of the tin-based alloy material layer are simultaneously worn, causing sinking. The ship's outboard stern shaft sinking measurement signal is obtained by real-time monitoring of the distance signal between the measuring end of the outboard stern shaft sinking measurement module and the lower surface of the ship's outboard stern shaft. S3, Measurement signal processing: The signal processing module of the signal processing and display system processes the data of the sinking measurement signal sent by the stern shaft sinking measurement module to obtain the measured value of the stern shaft sinking. S4, Measurement value display and storage: The measurement value of the ship's stern shaft subsidence is displayed and stored in real time through the display and storage module of the signal processing and display system.

2. The method for measuring the stern shaft subsidence of a ship according to claim 1, characterized in that, The outboard stern shaft sinking measurement module includes an electromagnetic ultrasonic sensor probe (5) pre-embedded and installed on the bottom side of the stern shaft tube (3) at the stern of the ship. The bottom end of the electromagnetic ultrasonic sensor probe (5) is provided with an AD conversion module (6), and the AD conversion module (6) is electrically connected to the signal processing and display system in the cabin through a signal cable (7) pre-embedded in the hull.

3. The method for measuring the stern shaft subsidence of a ship according to claim 2, characterized in that, The electromagnetic ultrasonic sensor probe (5) is covered with a tin-based alloy material layer (4). After the top of the electromagnetic ultrasonic sensor probe (5) is inserted into the copper sleeve (2) of the stern tube bearing, the outer surface of the tin-based alloy material layer (4) is flush with the upper surface of the bottom side plate (1) of the stern tube bearing. The upper surface of the bottom side plate (1) of the stern tube bearing and the outer surface of the tin-based alloy material layer (4) are in contact with the lower surface of the ship's stern tube bearing.

4. The method for measuring the stern shaft subsidence of a ship according to claim 3, characterized in that, During the process of the stern shaft wear and sinking of the upper surface of the bottom side plate (1) of the stern shaft tube bearing, the outer surface of the tin-based alloy material layer (4) is worn down simultaneously, so that the outer surface of the tin-based alloy material layer (4) is always flush with the upper surface of the bottom side plate (1) of the stern shaft tube bearing. The ultrasonic sensor probe (5) monitors the change in distance signal between the probe end and the lower surface of the stern shaft in real time, and obtains the measurement signal of the sinking of the stern shaft.

5. The method for measuring the stern shaft subsidence of a ship according to claim 1, characterized in that, The signal processing and display system inside the cabin includes a signal processing module (8) and a display and storage module (9). The signal processing module (8) is used to process the sinking measurement signal sent by the outboard stern shaft sinking measurement module to obtain the measurement value of the outboard stern shaft sinking.

6. A method for measuring the stern shaft subsidence of a ship according to claim 5, characterized in that, The display and storage module (9) is used to display and store the measured value of the ship's stern shaft subsidence in real time.

7. The method for measuring the stern shaft subsidence of a ship according to claim 1, characterized in that, The data processing includes: S31, Signal reception: Real-time reception of the sinking measurement signal sent by the outboard stern shaft sinking measurement module; S32, Signal comparison and sampling: The effective signal and noise in the sinking measurement signal are distinguished by a preset comparator, the effective range of the measurement signal is sampled, and noise is removed; S33, Waveform Delay Processing and Storage: The time deviation of the transmitted ultrasonic waveform is calibrated through a digital delay unit, and the sampled digital waveform data is stored. S34, Echo Detection: Identify valid echo signals and interference signals in the received echo and remove interference signals; S35, Sound time value calculation: Based on the time from the transmission of the ultrasonic wave to the reception of the echo, calculate and determine the real-time distance between the probe tip and the lower surface of the ship's stern shaft. S36, Signal Output: Output the change in the real-time distance value as a measurement of the ship's outboard stern shaft subsidence.

8. A method for measuring the stern shaft subsidence of a ship according to claim 7, characterized in that, The preset comparator compares the received analog signal with a preset threshold: when the signal amplitude exceeds the preset threshold, it is considered a valid signal; when the signal amplitude is lower than the preset threshold, it is considered noise.

9. A method for measuring the stern shaft subsidence of a ship according to claim 7, characterized in that, The echo determination is specifically as follows: based on the waveform correlation between the echo and the transmitted wave, the waveform characteristics of the received signal and the transmitted signal are compared, and when the correlation coefficient exceeds the correlation threshold, it is determined to be a valid echo signal.

10. A method for measuring the stern shaft subsidence of a ship according to claim 6, characterized in that, The display and storage module (9) displays the measured value of the ship's stern shaft subsidence in real time on the screen for operators to monitor, and stores the measured value of the ship's stern shaft subsidence in the storage medium in real time.

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