A method for monitoring the sinking amount and vibration of a ship's outboard stern shaft

Abstract

The present application relates to the technical field of ship measuring equipment, and more particularly to a ship outboard stern shaft sinking amount and vibration online monitoring method. The present application fills the blank of the existing ship outboard stern shaft online real-time monitoring means, and can replace the traditional manual mechanical measurement method, improve the convenience and real-time performance; realizes multifunctional integration, realizes the integration of wear amount, wear line type and stern shaft transverse vibration monitoring; has strong universality and good environmental adaptability, and can be applied not only to civilian high-end ships and surface warships, but also to underwater vehicles and other fields; can provide effective means for preventive maintenance of ships, and provide effective support for intelligent monitoring, operation and management of future ship propulsion systems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship measuring equipment, and particularly relates to a ship outboard shaft sinking amount and vibration online monitoring method. BACKGROUND

[0002] The tail shaft is an important component of the ship propulsion shafting, the tail end of which is installed with a propeller, and the head end is connected with other shafting transmission equipment in the cabin through a shaft coupling, thereby playing a role in transmitting the main engine torque and propeller thrust. The tail shaft is mostly located outboard and is supported by a water-lubricated tail shaft bearing also located outboard. Due to the unbalance of the rotating parts and the rotor dynamics characteristics of the concentrated mass-cantilever beam system formed by the propeller and the tail shaft, when the propulsion shafting is running, rotational (lateral) vibration will be generated, and the tail end of the outboard tail shaft is one of the positions with the largest vibration amplitude. The rotational vibration of the shafting will be transmitted to the ship structure through the shafting and the tail shaft bearing, thereby inducing the generation of stern structure vibration sound radiation. In addition, the tail shaft bearing used to support the outboard tail shaft has a poor working condition, uses seawater for lubrication and cooling, bears heavy load, friction and vibration impact, and may also face the invasion of foreign matters such as silt, marine organisms and fishing nets, and is extremely prone to abnormal wear and rapid wear, thereby causing the tail shaft to sink, changing the load distribution characteristics of the shafting and the working condition of the tail shaft bearing, and bringing adverse effects to the safe operation and long-term reliability of the propulsion shafting. Therefore, it is necessary to perform online monitoring on the sinking amount and vibration of the ship outboard tail shaft.

[0003] The existing sinking amount and tail shaft bearing wear amount of the ship outboard tail shaft are generally measured under specific conditions by using a mechanical measuring instrument through an artificial method, the means is backward, the measurement convenience is poor, and the online real-time monitoring cannot be performed. In addition, the existing ship still lacks a monitoring means for the lateral vibration of the outboard tail shaft. The above two problems result in that the existing technology and means cannot meet the urgent needs of high-end civilian ships and professional warships for online monitoring of the sinking amount of the outboard tail shaft, the wear amount of the tail shaft bearing and the lateral vibration of the tail shaft. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a ship outboard tail shaft sinking amount and vibration online monitoring method, which can perform online real-time monitoring on the sinking amount and lateral vibration of the outboard tail shaft during ship navigation, has high measurement accuracy, and can improve the safety, reliability and economy of ship navigation.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0006] The application discloses an online monitoring method for the sinking amount and vibration of a ship outboard stern shaft, which is used for detecting the sinking amount and transverse vibration of a ship stern shaft (5), wherein a propeller (1) of the ship is installed at the tail end of the stern shaft (5), the stern shaft (5) is supported by a stern shaft front bearing (6) and a stern shaft rear bearing (4), the stern shaft front bearing (6) and the stern shaft rear bearing (4) are both installed on the ship body structure (3) outside the ship, the stern shaft rear bearing (4) is provided with an outboard stern shaft sinking and vibration integrated measuring instrument (2) at the tail end, and a plurality of groups of displacement sensors are arranged in the outboard stern shaft sinking and vibration integrated measuring instrument (2).

[0007] Further, the outboard stern shaft sinking and vibration integrated measuring instrument (2) is internally provided with five integrated eddy current displacement sensors, namely, integrated eddy current displacement sensor 1# (7), integrated eddy current displacement sensor 2# (8), integrated eddy current displacement sensor 3# (9), integrated eddy current displacement sensor 4# (10) and integrated eddy current displacement sensor 5# (11).

[0008] Specifically, the sinking amount measuring method comprises the following steps.

[0009] S1, in the initial installation state, the detection values x1, x2, x3, x4 and x5 of the five displacement sensors are recorded, and the distances between the five displacement sensors and the initial shaft center Os of the stern shaft are determined.

[0010] S2, after the operation time T, the detection values x1'', x2'', x3'', x4'' and x5'' of the five displacement sensors are recorded again, and the distances between the five displacement sensors and the actual shaft center Os' of the stern shaft are determined.

[0011] S3, the eccentricity e and the eccentric angle phi of the shaft center of the stern shaft are solved.

[0012] S4, according to the eccentricity e and the eccentric angle phi, the inner hole diameter R of the rear bearing and the diameter r of the stern shaft, the center Ow of the rear bearing bottom wear circle is determined, and Os'Ow and OsOw are solved.

[0013] S5, according to the Os'Ow, OsOw and eccentricity e, the relative position of the center Ow of the rear bearing bottom wear circle is determined.

[0014] S6, according to the relative position of the center of the wear circle, the wear amount of the rear bearing and the radius of the bottom wear circle are solved.

[0015] S7, the monitoring values under different rotating speeds are processed and operated, and the complete wear line type of the bearing is identified.

[0016] Further, in step S1, the distances between the five displacement sensors and the initial shaft center Os of the tail shaft are respectively:

[0017] s1=R-x1

[0018] s2=R-x2

[0019] s3=R-x3

[0020] s4=R-x4

[0021] s5=R-x5

[0022] wherein R is the diameter of the inner hole of the rear bearing.

[0023] Further, in step S2, the distances between the five displacement sensors and the actual shaft center Os' of the tail shaft are respectively:

[0024] s1”=R-x1”

[0025] s2”=R-x2”

[0026] s3”=R-x3”

[0027] s4”=R-x4”

[0028] s5”=R-x5”

[0029] wherein R is the diameter of the inner hole of the rear bearing.

[0030] Further, in step S3, the eccentricity e and the eccentric angle φ of the shaft center of the tail shaft satisfy the following formula:

[0031]

[0032] s” n =R-x” n (n=1,2,…,5)

[0033] wherein R is the diameter of the inner hole of the rear bearing, r is the diameter of the tail shaft, and α is the included angle between the symmetrically arranged sensors 2# and 4# and the center line.

[0034] Further, in step S5, the relative position of the center Ow of the rear bearing wear circle includes ∠OsOs'Ow, ∠OsOs'A', and ∠OsOs'A, wherein A is the main measurement base point of the rear bearing in the initial state, and A' is the auxiliary measurement base point of the rear bearing in the initial state.

[0035] Further, in step S6, the bearing wear amount is:

[0036] A'B'=r-Os'A'

[0037] AB=r-Os'A,

[0038] In the formula, B is the main measuring base point of the rear bearing in the worn state, and B' is the auxiliary measuring base point of the rear shaft in the worn state.

[0039] The bottom wear circle radius is R'=r+OwOs'.

[0040] Further, the vibration measurement method specifically comprises the following steps: the integrated eddy current displacement sensor 1# (7) and the integrated eddy current displacement sensor 5# (11) are symmetrically arranged on the upper half of the tail shaft rear bearing (4), the vibration displacement X of the tail shaft along the direction of the sensor 1# (7) and the vibration displacement Y of the tail shaft along the direction of the sensor 5# (11) are monitored, then the Fourier transform is performed to obtain the displacement frequency spectrum curves in the two directions, and further the synthesized shaft center trajectory and the harmonic shaft center trajectory formed by the vibration of the tail shaft (5) are obtained.

[0041] Compared with the prior art, the present application has the following main advantages:

[0042] 1. The ship outboard tail shaft sinking amount and vibration online monitoring method fills the blank of the existing ship outboard tail shaft online real-time monitoring means, and can replace the traditional manual mechanical measurement method, thereby improving the convenience and real-time performance.

[0043] 2. The ship outboard tail shaft sinking amount and vibration online monitoring method realizes multifunctional integration, and realizes the integration of wear amount, wear line type and tail shaft transverse vibration monitoring.

[0044] 3. The ship outboard tail shaft sinking amount and vibration online monitoring method has strong universality and good environmental adaptability, and can be applied not only to civilian high-end ships and surface warships, but also to underwater vehicles and other fields.

[0045] 4. The ship outboard tail shaft sinking amount and vibration online monitoring method can provide an effective means for preventive maintenance of ships, and also provides effective support for intelligent monitoring, operation and management of future ship propulsion systems. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is an overall schematic diagram of the online monitoring device in the embodiment of the present application.

[0047] Figure 2 It is an internal sensor layout diagram of the outboard tail shaft sinking and vibration integrated measuring instrument in the embodiment of the present application.

[0048] Figure 3 It is a principle diagram of the outboard tail shaft sinking amount measurement in the initial state in the embodiment of the present application.

[0049] Figure 4This is a schematic diagram illustrating the principle of measuring the outboard stern shaft sinking under ideal wear conditions in an embodiment of the present invention.

[0050] Figure 5 This is a schematic diagram illustrating the principle of measuring the outboard tail shaft sinking under actual wear conditions in an embodiment of the present invention.

[0051] Figure 6 This is a schematic diagram illustrating the principle of measuring the vibration of the outboard tail shaft in an embodiment of the present invention.

[0052] In the diagram: 1. Propeller; 2. Integrated measuring instrument for stern shaft sinking and vibration; 3. Hull structure; 4. Aft stern shaft bearing (propeller bearing); 5. Stern shaft (propeller shaft); 6. Forward stern shaft bearing; 7. Integrated eddy current displacement sensor #1; 8. Integrated eddy current displacement sensor #2; 9. Integrated eddy current displacement sensor #3; 10. Integrated eddy current displacement sensor #4; 11. Integrated eddy current displacement sensor #5. Detailed Implementation

[0053] 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.

[0054] 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.

[0055] I. Online monitoring device

[0056] like Figure 1 As shown, a propeller 1 is mounted on the stern of the stern shaft 5 of the ship's propulsion shafting system. It is typically supported by a forward stern shaft bearing 6 and a rear stern shaft bearing 4 (also called a propeller bearing), which are installed within the hull structure 3. To measure the stern shaft 5's sinking caused by wear on the rear stern shaft bearing 6 due to shafting operation, this invention proposes an integrated outboard stern shaft sinking and vibration measuring instrument 2 installed at the stern of the rear stern shaft bearing 6. This instrument performs online real-time monitoring of the stern shaft 5's sinking at its stern. The monitoring signal is transmitted via a pressure-resistant watertight cable to the main monitoring unit inside the cabin for signal processing and display.

[0057] like Figure 2As shown, the integrated measuring instrument 2 for stern shaft sinking and vibration integrates five integrated eddy current displacement sensors (1#, 2#, 3#, 4#, and 5#). Among them, integrated eddy current displacement sensor 3# is placed on the top, coinciding with the theoretical center line of the inner hole of the stern shaft rear bearing 4. Integrated eddy current displacement sensors 2# and 4# are placed on the left and right sides of the top of integrated eddy current displacement sensor 3#, respectively, in symmetrical positions. The angle α between each sensor and the center line is set in the range of 10° to 15°. Integrated eddy current displacement sensors 1# and 5# are placed in the upper part of the measuring instrument, symmetrically arranged along the theoretical center line of the inner hole of the stern shaft rear bearing. The angle β between each sensor and the center line is set to 45°.

[0058] The five sensors are integrated and packaged in a seawater-resistant engineering plastic shell formed by one-piece casting, and filled with resin inside to achieve pressure resistance.

[0059] All five sensors mentioned above can be used to monitor the outboard tail shaft sinking. Among them, the two integrated eddy current displacement sensors (1# and 5#) are mainly used for monitoring the lateral vibration of the outboard tail shaft.

[0060] II. Measurement of Outboard Tailshaft Sinking

[0061] like Figure 3 As shown, in the initial installation state, the tail shaft 5 sits on the tail shaft rear bearing or propeller bearing 4, with the bottoms of the two tightly fitted together. The center of the tail shaft 5 is Os, the top clearance is δ, and the center distance between the two is δ / 2. At this time, the monitored values ​​at the locations of the upper integrated eddy current displacement sensors (1#, 2#, 3#, 4#, 5#) are x1, x2, x3, x4, and x5, respectively. The inner radius of the bearing is R. Then, the distances between each sensor location and the center Ob of the bearing inner hole are s1 = R - x1, s2 = R - x2, s3 = R - x3, s4 = R - x4, and s5 = R - x5, respectively.

[0062] like Figure 4As shown, when the stern shaft rear bearing 4 is worn after a long period of operation T, if the wear pattern is ideal bottom arc overall wear, the stern shaft 5 will produce a certain amount of sinking WD, the shaft center of the stern shaft 5 changes from Os to Ow, at this time, the monitoring values of the upper five sensors change to x1', x2', x3', x4', x5', the distance between each sensor site and Ow is s1'=R-x1', s2'=R-x2', s3'=R-x3', s4'=R-x4', s5'=R-x5', at this time, the wear of the stern shaft rear bearing 4 is equal to the sinking amount of the stern shaft 5, and also the amount of change of the shaft center position of the stern shaft 5 WD, and also the change of the monitoring value of the top integrated eddy current displacement sensor 3#, that is, WD=Ow-Os=x3'-x3=s3-s3'. Whether this kind of wear pattern occurs can be judged by the difference between the monitoring values of the integrated eddy current displacement sensors 1# and 5# and 2# and 4#.

[0063] As shown in Figure 5 For actual ships, the wear pattern is generally not ideal wear, but a combination of curves, causing the stern shaft 5 not only to sink, but also to produce a certain amount of horizontal offset. At this time, the shaft center of the stern shaft 5 moves from Os to Os', the eccentricity is e, the eccentric angle is φ, the angle between the top 2#, 4# and 3# sensors is α, the sinking amount of the stern shaft 5 in the vertical direction is WD1, and the maximum wear of the stern shaft rear bearing 4 at the bottom is WD2, the maximum wear of the stern shaft rear bearing 4 in the bottom bearing area is WD3, and WD1≠WD2≠WD3. At this time, the monitoring values of the upper integrated eddy current displacement sensors (1#, 2#, 3#, 4#, 5#) are x1'', x2'', x3'', x4'', x5'', the bearing bore radius is R, the stern shaft radius is r, and each parameter satisfies the following relationship:

[0064]

[0065] s” n =R-x” n (n=1, 2, …, 5)

[0066] By comparing (x1'', x2'') and (x5'', x4''), the horizontal offset direction and offset value of the stern shaft can be obtained. Through the above formula, the eccentricity e, the eccentric angle φ, the bearing bore diameter R and the stern shaft diameter r (note: in the initial state, R and r can be known parameters; after a period of operation, R and r may change due to deformation and wear, which can be treated as variables and solved through the above formula) can be obtained.

[0067] Using the eccentricity e, eccentricity angle φ, bearing inner diameter R, and tail shaft diameter r obtained from the solution, Os'Ow and OsOw can be solved again, thus determining the center Ow of the bottom wear circle after wear. Then, based on Os'Ow, OsOw, and eccentricity e, ∠OsOs'Ow, ∠OsOs'A', and ∠OsOs'A can be solved. Then, based on the ∠OsOs'A', ∠OsOs'A, and eccentricity e obtained from the solution, Os'A' and Os'A can be solved. Thus, the wear amount A'B' = r - Os'A' and AB = r - Os'A. At the same time, the radius R' of the bottom wear circle can also be identified as r + OwOs'.

[0068] By solving and processing multiple speeds and multiple monitoring values, the complete wear line pattern of the bearing can be identified.

[0069] III. Measurement of Outboard Tailshaft Vibration

[0070] like Figure 6 As shown, integrated eddy current displacement sensors 1# and 5#, arranged on the upper half of the tail shaft rear bearing 4, are at an angle of 45° to the vertical centerline. They can simultaneously monitor vibration displacement in two directions. Through Fourier transform, the displacement spectrum curves in the two directions are obtained, thus obtaining the synthetic shaft center trajectory and the shaft center trajectory of each harmonic formed by the vibration of the tail shaft 5. This allows for precise control of the vibration characteristics of the outboard propeller-tail shaft-bearing system during shaft operation, including parameters such as vibration displacement amplitude, characteristic frequency, shaft center trajectory, and shaft center trajectory line during start-up and shutdown.

[0071] In summary:

[0072] 1. The online monitoring method for the sinking and vibration of the ship's outboard stern shaft of the present invention fills the gap in the existing online real-time monitoring methods for the ship's outboard stern shaft and can replace the traditional manual mechanical measurement method, improving convenience and real-time performance;

[0073] 2. The online monitoring method for the stern shaft subsidence and vibration of the ship of the present invention realizes multi-functional integration, and realizes integrated monitoring of wear amount, wear line shape and stern shaft lateral vibration;

[0074] 3. The online monitoring method for ship stern shaft subsidence and vibration of the present invention has strong versatility and good environmental adaptability. It can be applied not only to high-end civilian ships and surface vessels, but also to underwater vehicles and other fields.

[0075] 4. The online monitoring method for ship stern shaft subsidence and vibration of the present invention can provide an effective means for preventive maintenance of ships, and also provide effective support for intelligent monitoring, operation and management of ship propulsion systems in the future.

[0076] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for on-line monitoring of the sinking and vibration of a marine outboard propeller shaft, for detecting the sinking and transverse vibration of a marine outboard propeller shaft (5), the propeller (1) of the marine vessel being mounted on the aft end of the propeller shaft (5), the propeller shaft (5) being supported by a propeller shaft front bearing (6) and a propeller shaft rear bearing (4), the propeller shaft front bearing (6) and the propeller shaft rear bearing (4) both being mounted on the hull structure (3) of the marine vessel outside the hull, characterized in that: The stern shaft rear bearing (4) tail end is provided with an outboard stern shaft sinking and vibration integrated measuring instrument (2), and a plurality of displacement sensors are arranged in the outboard stern shaft sinking and vibration integrated measuring instrument (2); the online monitoring method comprises an outboard stern shaft sinking amount measuring method and a vibration amount measuring method. The outboard stern shaft sinking and vibration integrated measuring instrument (2) is internally provided with five integrated eddy current displacement sensors, namely, integrated eddy current displacement sensor 1# (7), integrated eddy current displacement sensor 2# (8), integrated eddy current displacement sensor 3# (9), integrated eddy current displacement sensor 4# (10) and integrated eddy current displacement sensor 5# (11). The sinking amount measuring method comprises the following steps: S1, in the initial installation state, the detection values x1, x2, x3, x4 and x5 of the five displacement sensors are recorded, and the distances of the five displacement sensors from the initial shaft center Os of the stern shaft are determined; S2, after the operation time T, the detection values x1'', x2'', x3'', x4'' and x5'' of the five displacement sensors are recorded again, and the distances of the five displacement sensors from the actual shaft center Os' of the stern shaft are determined; S3, the eccentricity e and the eccentric angle φ of the shaft center of the stern shaft are solved; S4, according to the eccentricity e and the eccentric angle φ, the inner hole diameter R of the rear bearing and the diameter r of the stern shaft, the center Ow of the bottom wear circle of the rear bearing is determined, and Os'Ow and OsOw are solved; S5, according to Os'Ow, OsOw and the eccentricity e, the relative position of the center Ow of the bottom wear circle of the rear bearing is determined; S6, according to the relative position of the center of the wear circle, the wear amount of the rear bearing and the radius of the bottom wear circle are solved; S7, the monitoring values under different rotating speeds are processed and operated to identify the complete wear line type of the bearing.

2. The method according to claim 1, wherein In step S1, the distances of the five displacement sensors from the initial shaft center Os of the stern shaft are respectively: s1=R-x1 s2=R-x2 s3=R-x3 s4=R-x4 s5=R-x5 In the formula, R is the inner hole diameter of the rear bearing.

3. The method according to claim 1, wherein In step S2, the distances of the five displacement sensors from the actual shaft center Os' of the stern shaft are respectively: s1''=R-x1'' s2''=R-x2'' s3''=R-x3'' s4''=R-x4'' s5''=R-x5'' In the formula, R is the inner hole diameter of the rear bearing.

4. The method according to claim 1, wherein In step S3, the eccentricity e and the eccentric angle φ of the shaft center of the stern shaft satisfy the following formula: s” n = R - x n (n = 1, 2, …, 5) In the formula, R is the inner hole diameter of the rear bearing, r is the diameter of the stern shaft, and α is the included angle between the symmetrically arranged sensors 2# and 4# and the center line.

5. The method according to claim 1, wherein In step S5, the relative position of the center Ow of the bottom wear circle of the rear bearing specifically includes ∠OsOs'Ow, ∠OsOs'A' and ∠OsOs'A, wherein A is the main measurement base point of the rear bearing in the initial state, and A' is the auxiliary measurement base point of the rear bearing in the initial state.

6. The method according to claim 1, wherein In step S6, the bearing wear amount is: A'B'=r-Os'A' AB=r-Os'A, In the formula, B is the main measurement base point of the rear bearing in the wear state, and B' is the auxiliary measurement base point of the rear bearing in the wear state. The bottom wear circle radius is R'=r+OwOs'.

7. The method according to claim 1, wherein: The vibration measurement method is specifically as follows: integrated eddy current displacement sensors 1# (7) and 5# (11) are symmetrically arranged on the upper half of the tail shaft rear bearing (4), the vibration displacement X of the tail shaft along the direction of the sensor 1# (7) and the vibration displacement Y of the tail shaft along the direction of the sensor 5# (11) are monitored, then the Fourier transform is performed to obtain the displacement frequency spectrum curves in two directions, and then the synthesized shaft center track formed by the vibration of the tail shaft (5) and each harmonic shaft center track are obtained.

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