Vibration suppression system and method based on adjustable position of tail shaft bearing

Abstract

The invention discloses a vibration suppression system and method based on an adjustable tail shaft bearing position, and relates to the technical field of tail shaft vibration suppression, and the vibration suppression system comprises a sensing module, a signal processing control module and a bearing position adjustment execution module; wherein the sensing module is used for monitoring a ship body vibration signal; a mapping relation database is stored in the signal processing control module, and the signal processing control module is used for processing the real-time vibration signals and querying the mapping relation database to generate a bearing position adjusting instruction; and the bearing position adjustment execution module is used for receiving the bearing position adjustment instruction and driving the tail shaft bearing to move to a target position. The position of the tail shaft bearing can be adjusted in a self-adaptive mode, target frequency vibration is attenuated, navigation comfort and concealment are improved, and the service life of key components of a propelling system is effectively prolonged. Meanwhile, the invention discloses a vibration suppression method based on the adjustable position of the tail shaft bearing.

Description

Technical Field

[0001] This invention relates to the field of stern shaft vibration suppression technology, and more particularly to a vibration suppression system and method based on adjustable stern shaft bearing position. Background Technology

[0002] The propulsion system is a core component of high-performance vessels such as speedboats; however, the vibration generated by the stern shaft and propeller during operation has always been a prominent issue affecting the vessel's comfort, safety, and stealth. During operation, the propeller generates periodic excitation forces due to uneven airflow and vortex shedding. These excitation forces are transmitted through the stern shaft and bearings to the bearing housing, ultimately causing severe vibrations and radiated noise in the hull. This vibration not only affects passenger comfort but also accelerates equipment fatigue damage, increases maintenance costs, and even impacts the vessel's acoustic stealth performance. The vibration problem is particularly pronounced at high speeds, severely hindering further improvements in vessel performance.

[0003] Currently, control methods for this type of vibration are mainly divided into two categories: passive control and active control. Passive control methods include using high-damping materials, optimizing the base structure, and installing dynamic vibration absorbers. Although these methods are simple in structure and highly reliable, their vibration suppression effect is limited, especially for low-frequency line spectrum vibrations. Passive methods often have inherent drawbacks such as increased weight, affecting shaft alignment, and difficulty in adapting to different operating conditions. For example, while traditional rubber vibration isolators can isolate vibrations to a certain extent, their stiffness characteristics are fixed and cannot adapt to changes in vibration characteristics at different speeds. In addition, passive control methods often require compromises between vibration reduction effects and other performance indicators, making it difficult to achieve optimal overall performance.

[0004] Active control methods, such as active vibration isolation systems, counteract vibrations by applying counterforces through actuators. However, their control laws are complex to design, energy consumption is high, and they place extremely high demands on the response speed and control precision of the actuators. Existing active control schemes mostly employ feedback-based control strategies, requiring real-time acquisition and rapid processing of vibration signals, which places high demands on the computational power and response speed of the control system. Furthermore, these methods often rely on accurate system models, while the dynamic characteristics of ship propulsion systems are complex, which to some extent limits the practical application effectiveness of active control methods.

[0005] In-depth patent searches and technical research revealed that while existing technologies involve vibration reduction adjustments through sensor detection, these solutions primarily focus on the control algorithm itself or the specific design of the actuator. They fail to fundamentally address a core theoretical problem: how to actively and precisely adjust the installation position of the stern shaft bearing—a critical mechanical node—during actual operation to directly optimize the vibration transmission path from the propeller to the hull. Traditional trial-and-error methods are not only inefficient but also struggle to find the globally optimal solution. Furthermore, existing methods often lack a deep understanding of the system's dynamic characteristics, failing to establish a quantitative relationship between vibration response and bearing position. This limits control effectiveness, leaving ship vibration control largely confined to attenuating or counteracting fixed paths, hindering systematic optimization from the source and restricting further improvements in overall ship performance. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a vibration suppression system and method based on an adjustable stern shaft bearing position, which can adaptively adjust the stern shaft bearing position, attenuate target frequency vibrations, improve navigation comfort and stealth, and effectively extend the service life of key components of the propulsion system.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] A vibration damping system based on an adjustable stern shaft bearing is applied to the stern shaft bearing, which is vertically mounted to the hull via a bearing housing. A horizontally positioned stern shaft is installed inside the stern shaft bearing. The vibration damping system includes:

[0009] The sensing module is used to monitor hull vibration signals;

[0010] The signal processing and control module is connected to the sensing module. The signal processing and control module stores a database of the mapping relationship between bearing position and vibration response. The signal processing and control module is used to process real-time vibration signals to identify the dominant vibration frequency and query the mapping relationship database to generate corresponding bearing position adjustment commands.

[0011] The bearing position adjustment execution module is connected to the signal processing control module. The bearing position adjustment execution module is used to receive bearing position adjustment commands and drive the stern shaft bearing to move to the target position in a two-dimensional plane and then rigidly lock it.

[0012] Preferably, the bearing position adjustment execution module includes:

[0013] The hydraulic flexible bushing has a ring structure and is sleeved between the stern shaft bearing and the bearing housing. The inner wall of the hydraulic flexible bushing is recessed with an annular oil cavity, which is connected to the low-pressure hydraulic station.

[0014] Two displacement adjustment devices are respectively located on both sides of the stern shaft. The displacement adjustment devices include an X-direction displacement mechanism for adjusting the stern shaft bearing along the X direction and a Y-direction displacement mechanism for adjusting the stern shaft bearing along the Y direction.

[0015] The X-axis displacement mechanism is set along the axis of the stern shaft. The X-axis displacement mechanism is installed on the hull and its actuating end is connected to the stern shaft bearing.

[0016] The Y-axis displacement mechanism is set perpendicularly to the X-axis displacement mechanism, and the Y-axis displacement mechanism is installed on the hull.

[0017] Preferred,

[0018] The X-axis displacement mechanism includes an X-axis servo motor and an X-axis ball screw pair; the X-axis servo motor is slidably mounted on the hull along the axis of the stern shaft; the X-axis ball screw pair includes an X-axis ball screw and an X-axis ball nut, one end of the X-axis ball screw is connected to the output shaft of the X-axis servo motor, and the other end of the X-axis ball screw is connected to the stern shaft bearing through a ball joint.

[0019] The Y-axis displacement mechanism includes a Y-axis servo motor and a Y-axis ball screw pair; the Y-axis servo motor is fixedly mounted on the hull; the Y-axis ball screw pair includes a Y-axis ball screw and a Y-axis ball nut, one end of the Y-axis ball screw is connected to the output shaft of the Y-axis servo motor; the Y-axis ball nut is fixedly connected to the X-axis ball nut.

[0020] The X-axis ball screw is equipped with a Y-axis magnetorheological damper arranged along the Y-axis, and the bottom end of the Y-axis magnetorheological damper is fixedly connected to the hull.

[0021] The Y-axis ball screw is equipped with an X-axis magnetorheological damper arranged along the X-axis, and one end of the X-axis magnetorheological damper is connected to the stern shaft bearing.

[0022] Preferably, the X-direction magnetorheological damper and the Y-direction magnetorheological damper have the same structure, both including a damper housing, a magnetorheological fluid filled inside the damper housing, and an excitation coil disposed inside the damper housing.

[0023] When the excitation coil is energized, the magnetorheological fluid filling the damper housing is in a low-viscosity fluid state, allowing the corresponding ball screw to rotate freely; when the excitation coil is de-energized, the magnetorheological fluid filling the damper housing changes to a Bingham solid state, locking the corresponding ball screw.

[0024] Preferably, the cross-section of the annular oil chamber is trapezoidal, and the low-pressure hydraulic station is connected to the annular oil chamber through a hydraulic pipeline, on which a solenoid valve is installed.

[0025] When the pressure in the annular oil chamber rises to the set high pressure, the hydraulic flexible bushing expands outward along its radial direction to release the interference fit between the stern shaft bearing and the bearing housing and form a micro gap.

[0026] When the pressure in the annular oil chamber drops to the set low pressure, the hydraulic flexible bushing returns to the pre-compression state to rebuild the interference fit between the stern shaft bearing and the bearing housing.

[0027] The vibration suppression method based on the adjustable stern shaft bearing position, applied to the aforementioned vibration suppression system based on the adjustable stern shaft bearing position, includes the following steps:

[0028] S1. Obtain the frequency response function matrix of the stern structure of the hull obtained in advance through experimental modal analysis; establish a parameterized multibody dynamics model based on the frequency response function matrix; optimize the parameter vector to be corrected in the multibody dynamics model with the frequency response function matrix as the correction target, so as to minimize the error between the simulated frequency response and the experimental frequency response, and obtain the corrected digital twin model.

[0029] S2. Define the bearing's position coordinates (ΔX, ΔY) in a two-dimensional plane as design variables; in the digital twin model, minimize the vibration response amplitude of the target monitoring point as the optimization objective and set constraints; use optimization algorithms to perform iterative simulation calculations to obtain the optimal bearing position and its corresponding vibration response data under different preset working conditions or target frequencies; use spatial interpolation methods to generate a continuous and quantitative mapping relationship between bearing position and vibration response, and store it as a mapping relationship database;

[0030] S3. Continuously collect hull vibration signals in real time through the sensing module; perform real-time spectrum analysis on the collected vibration signals to identify and extract the current dominant vibration frequency and its amplitude characteristics; use the dominant vibration frequency as an index to query the mapping relationship database to obtain the optimal bearing position adjustment amount corresponding to the frequency; generate bearing position adjustment instructions containing specific X-direction displacement and Y-direction displacement based on the optimal bearing position adjustment amount.

[0031] S4. According to the bearing position adjustment command, coordinate and control each component of the bearing position adjustment execution module in a preset sequence.

[0032] Preferably, step S4 includes the following steps:

[0033] S41. Control the hydraulic pressure of the flexible bushing to rise to the set high pressure, so that it expands radially to release the interference fit, and at the same time energize the excitation coil of the X-axis magnetorheological damper and / or the Y-axis magnetorheological damper, so that the magnetorheological fluid is converted to a low viscosity fluid state.

[0034] S42. Based on the bearing position adjustment command, control the X-axis servo motor and / or the Y-axis servo motor to rotate, drive the X-axis ball screw pair and / or the Y-axis ball screw pair to move, and drive the stern shaft bearing to move; at the same time, perform closed-loop position control through servo motor encoder feedback until the bearing reaches the target position.

[0035] S43. Cut off the current to the excitation coil to convert the magnetorheological fluid into a Bingham solid state to lock the lead screw; then, reduce the oil pressure of the hydraulic flexible bushing to the set low pressure to restore it to the pre-compression state to rebuild the interference fit and complete the final fixation of the bearing position.

[0036] Preferably, in S1, the frequency response function matrix is ​​obtained in the following way:

[0037] The time-domain acceleration signal acquired in the experiment Discrete signals are obtained by digital sampling. The spectrum was obtained by fast Fourier transform. ; and adopt Estimation method for calculating frequency response function :

[0038] ;

[0039] in, For motivation With response acceleration cross power spectrum, For motivation The self-power spectrum and the FRF of all measurement points constitute the frequency response function matrix of the system. .

[0040] Preferably, in S1, the equations of motion for the multibody dynamics model are:

[0041] ;

[0042] in, , , These are the mass, damping, and stiffness matrices of the system, respectively.

[0043] Model correction is achieved by minimizing the following objective function:

[0044] ;

[0045] in, This is the parameter vector to be corrected.

[0046] Preferably, in S2, the optimization solution process is defined as follows:

[0047] Design variables: ;

[0048] Objective function: ;

[0049] Constraints: The constraints include shaft alignment constraints and structural strength constraints. Shaft alignment constraints ensure that the misalignment of the shaft system after bearing position adjustment is lower than a preset threshold, and structural strength constraints ensure that the maximum stress of key load-bearing components after bearing position adjustment is lower than the allowable stress of the material.

[0050] The particle swarm optimization algorithm is used, and its position and velocity update formulas are as follows:

[0051] ;

[0052] in, The particle position represents a bearing position.

[0053] After adopting the above technical solution, the beneficial effects of the present invention are:

[0054] This application discloses a vibration suppression system based on an adjustable stern shaft bearing. The stern shaft bearing is vertically mounted to the hull via a bearing housing, and a horizontally positioned stern shaft is installed inside the bearing. The vibration suppression system includes a sensing module, a signal processing and control module, and a bearing position adjustment execution module. First, the sensing module detects hull vibration in real time. The signal processing and control module analyzes and identifies the dominant vibration frequency causing the vibration. Then, it queries its internal mapping database to determine the optimal bearing adjustment position to effectively suppress the vibration at that frequency. Finally, the bearing position adjustment execution module receives instructions and drives the stern shaft bearing to make precise displacements in a two-dimensional plane and rigidly lock it, thereby actively changing the path characteristics of vibration transmitted from the bearing to the hull, achieving intervention at the source of the target vibration.

[0055] This application fundamentally optimizes the vibration transmission path, thereby achieving efficient suppression of vibrations at specific critical frequencies such as propeller blade frequency and reducing hull vibration levels. Its built-in mapping database endows the system with full-condition adaptive capability, automatically matching the optimal vibration suppression strategy according to changes in ship speed, load, and sea state, ensuring excellent vibration reduction performance under different operating conditions. Furthermore, it effectively protects onboard precision equipment and extends the service life of the propulsion system and hull structure by reducing structural fatigue loads. The vibration suppression system also significantly reduces underwater acoustic radiation characteristics, enhancing acoustic concealment; it combines intelligent algorithms with engineering practice, boasts a high degree of automation, and is easy to integrate and maintain.

[0056] Meanwhile, this application discloses a vibration suppression method based on adjustable stern shaft bearing position, applied to the aforementioned vibration suppression system based on adjustable stern shaft bearing position. By establishing a digital twin model that matches experimental data and combining it with an optimization algorithm under constraints, the optimal bearing position mapping relationship covering multiple working conditions can be pre-calculated offline, thus providing a decision-making basis for online vibration suppression. In the online control phase, through real-time spectrum analysis and mapping database queries, the system can immediately obtain the optimal adjustment command under the current vibration state, achieving rapid vibration identification and precise suppression. The preset collaborative control logic ensures that each component of the actuator operates sequentially and reliably, ultimately driving the bearing to accurately reach the target position and lock firmly, completing the closed-loop adaptive control from vibration sensing to position adjustment. This method transforms complex real-time calculations into efficient database queries and execution, significantly improving the system's response speed and engineering practicality while ensuring vibration suppression effects. Attached Figure Description

[0057] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0058] Figure 1 This is a partial cross-sectional view of the vibration damping system based on the adjustable stern shaft bearing position according to Embodiment 1 of the present invention;

[0059] Figure 2 yes Figure 1 A partial sectional view;

[0060] Figure 3 yes Figure 2 Enlarged view of part A;

[0061] Figure 4 This is a flowchart of the vibration suppression method based on the adjustable position of the stern shaft bearing in Embodiment 2 of the present invention;

[0062] Figure 5 yes Figure 4 Flowchart for constructing a digital twin model in China;

[0063] Figure 6 yes Figure 4 A flowchart for constructing a mapping relationship database;

[0064] Figure 7 yes Figure 4 Flowchart for adjusting the position of the intermediate bearing;

[0065] In the picture:

[0066] 1. Stern shaft bearing; 11. Bearing boss; 2. Bearing housing; 3. Hull; 4. Stern shaft; 5. Sensing module;

[0067] 6. Bearing position adjustment actuator; 61. Hydraulic flexible bushing; 611. Annular oil chamber; 62. X-axis displacement mechanism; 621. X-axis servo motor; 622. X-axis ball screw pair; 63. Y-axis displacement mechanism; 631. Y-axis servo motor; 632. Y-axis ball screw pair; 64. Y-axis magnetorheological damper; 65. X-axis magnetorheological damper. Detailed Implementation

[0068] 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.

[0069] Example 1

[0070] like Figures 1 to 3 As shown, the vibration damping system based on adjustable stern shaft bearing of the present invention is applied to stern shaft bearing 1, which is vertically mounted on hull 3 via bearing housing 2. A horizontally arranged stern shaft 4 is installed inside stern shaft bearing 1. The vibration damping system includes a sensing module 5, a signal processing and control module (not shown in the figure), and a bearing position adjustment execution module 6.

[0071] The sensing module 5 is used to monitor hull vibration signals. For this application, the sensing module 5 includes multiple triaxial accelerometers, installed at key locations such as the bearing housing and nearby hull. The signal processing and control module is a known technology in this field and can be an ECU or other independent control module. The signal processing and control module is communicatively connected to the sensing module 5. It stores a database of mapping relationships between bearing position and vibration response. The signal processing and control module processes real-time vibration signals to identify the dominant vibration frequency and queries the mapping database to generate corresponding bearing position adjustment commands. The bearing position adjustment execution module 6 is communicatively connected to the signal processing and control module. The bearing position adjustment execution module 6 receives the bearing position adjustment commands and drives the stern shaft bearing 1 to move to the target position in a two-dimensional plane before rigidly locking it.

[0072] The sensing module 5 deploys multiple triaxial accelerometers at key locations such as the bearing housing 2 and the hull 3, ensuring comprehensive and accurate vibration signal monitoring and providing reliable input for the system. The signal processing and control module utilizes its internally stored database of the mapping relationship between bearing position and vibration response to efficiently process real-time vibration signals, quickly identify the dominant vibration frequency, and accurately generate bearing position adjustment commands by querying the database, achieving intelligent vibration sensing and suppression decision-making. The bearing position adjustment execution module 6 receives and executes this command, driving the stern shaft bearing 1 to precisely move to the target position in a two-dimensional plane and achieve rigid locking, thereby translating the optimal vibration suppression strategy into actual physical adjustment and ultimately effectively attenuating hull vibration. The entire system forms a rapid closed loop of sensing, decision-making, and execution, significantly improving the response speed, accuracy, and automation level of vibration suppression.

[0073] The vibration suppression system actively and precisely adjusts the position of the stern shaft bearing 1, fundamentally optimizing the vibration transmission path and thus effectively suppressing vibrations at specific critical frequencies such as propeller blade frequency, significantly reducing the vibration level of the hull 3. Its built-in mapping database endows the system with powerful all-condition adaptive capabilities, automatically matching the optimal vibration suppression strategy according to changes in ship speed, load, and sea state, ensuring excellent vibration reduction performance under different operating conditions. Furthermore, the application of the vibration suppression system significantly improves passenger comfort, effectively protects onboard precision equipment, and extends the service life of the propulsion system and hull structure by reducing structural fatigue loads. For ships with special requirements, the vibration suppression system can also significantly reduce underwater acoustic radiation characteristics, enhancing acoustic concealment. Balancing intelligent algorithms with engineering practice, it boasts a high degree of automation, facilitates integration and maintenance, and provides an innovative and efficient proactive solution for ship vibration and noise control.

[0074] In this application, the bearing position adjustment execution module 6 includes:

[0075] Hydraulic flexible bushing 61, which is an annular structure and is sleeved between stern shaft bearing 1 and bearing seat 2, has an annular oil cavity 611 recessed in its inner wall, which is connected to a low-pressure hydraulic station (not shown in the figure).

[0076] Two displacement adjustment devices are respectively arranged on both sides of the stern shaft 4 along the Z direction. The displacement adjustment devices include an X-direction displacement mechanism 62 for adjusting the stern shaft bearing 1 along the X direction and a Y-direction displacement mechanism 63 for adjusting the stern shaft bearing 1 along the Y direction.

[0077] The X-axis displacement mechanism 62 is arranged along the axis of the stern shaft 4. The X-axis displacement mechanism 62 is installed on the hull 3 and its actuating end is connected to the stern shaft bearing 1. The X-axis is the axis of the stern shaft 4, and the Y-axis is the direction perpendicular to the axis of the stern shaft 4.

[0078] The Y-direction displacement mechanism 63 is arranged perpendicularly to the X-direction displacement mechanism 62, and the Y-direction displacement mechanism 63 is installed on the hull 3.

[0079] The bearing position adjustment execution module 6 of this application achieves dynamic and precise adjustment of the position of the stern shaft bearing 1 through its ingenious structural design. A hydraulic flexible bushing 61 is fitted between the stern shaft bearing 1 and the bearing housing 2. Its inner wall's annular oil cavity 611, connected to a low-pressure hydraulic station, enables precise control of the oil pressure, allowing the hydraulic flexible bushing 61 to undergo controllable elastic deformation in the radial direction. This provides the possibility of dynamically releasing or restoring the bearing interference fit during ship operation, a prerequisite for the movement of the stern shaft 4. Two displacement adjustment devices arranged along the Z-axis of the stern shaft 4 are independently driven in a two-dimensional plane through an X-axis displacement mechanism 62 and a Y-axis displacement mechanism 63, respectively. The X-axis displacement mechanism 62 moves along the axial direction of the stern shaft 4, directly acting on the stern shaft bearing 1; the Y-axis displacement mechanism 63, arranged perpendicularly to it, provides adjustment in another dimension. This cross-shaped layout allows the stern shaft bearing 1 to achieve precise positioning and movement at any target location within the mounting plane of the hull 3, thereby accurately converting the optimal position command in the mapping database into physical displacement, and ultimately achieving precise and proactive vibration suppression through the coordinated action of the entire module.

[0080] Preferably, the X-axis displacement mechanism 62 includes an X-axis servo motor 621 and an X-axis ball screw assembly 622; the X-axis servo motor 621 is slidably mounted on the hull 3 along the axial direction of the stern shaft 4; the X-axis ball screw assembly 622 includes an X-axis ball screw and an X-axis ball nut, one end of the X-axis ball screw is connected to the output shaft of the X-axis servo motor 621, and the other end of the X-axis ball screw is connected to the stern shaft bearing 1 via a ball joint; preferably, a bearing boss 11 is mounted on the stern shaft bearing 1, and the other end of the X-axis ball screw is connected to the bearing boss 11 via a ball joint;

[0081] The Y-axis displacement mechanism 63 includes a Y-axis servo motor 631 and a Y-axis ball screw pair 632; the Y-axis servo motor 631 is fixedly installed on the hull 3; the Y-axis ball screw pair 632 includes a Y-axis ball screw and a Y-axis ball nut, one end of the Y-axis ball screw is connected to the output shaft of the Y-axis servo motor 631; the Y-axis ball nut is fixedly connected to the X-axis ball nut.

[0082] The X-axis ball screw is equipped with a Y-axis magnetorheological damper 64 arranged along the Y-axis, and the bottom end of the Y-axis magnetorheological damper 64 is fixedly connected to the hull 3.

[0083] The Y-axis ball screw is equipped with an X-axis magnetorheological damper 65 arranged along the X-axis, and one end of the X-axis magnetorheological damper 65 is connected to the stern shaft bearing 1.

[0084] In this application, the X-direction magnetorheological damper 65 and the Y-direction magnetorheological damper 64 have the same structure, both including a damper housing, a magnetorheological fluid filled inside the damper housing, and an excitation coil disposed inside the damper housing.

[0085] When the excitation coil is energized, the magnetorheological fluid filling the damper housing is in a low-viscosity fluid state, allowing the corresponding ball screw to rotate freely; when the excitation coil is de-energized, the magnetorheological fluid filling the damper housing changes to a Bingham solid state, locking the corresponding ball screw.

[0086] The preferred structural design of the displacement adjustment device in this application provides key technical guarantees for the precise and reliable adjustment of the bearing position, and its technical effects are reflected in multiple aspects. The X-axis displacement mechanism 62 adopts a scheme in which the X-axis servo motor 621 drives the X-axis ball screw pair 622. The design of the X-axis servo motor 621 slidingly mounted on the hull 3 allows it to move with the stern shaft bearing 1, avoiding drive interference. One end of the X-axis ball screw is connected to the X-axis servo motor 621, and the other end is connected to the bearing boss 11 on the stern shaft bearing 1 through a ball joint. This structure not only ensures the efficient transmission of axial thrust, but also eliminates installation errors and additional bending moments through the ball joint. The Y-axis servo motor 631 of the Y-axis displacement mechanism 63 is fixed to the hull 3, and the Y-axis ball nut of its Y-axis ball screw pair 632 is fixedly connected to the X-axis ball nut. This design allows the X and Y-axis movements to be decoupled and linked, enabling the precise synthesis of any displacement vector in the plane. Most importantly, the Y-axis magnetorheological damper 64 mounted on the X-axis ball screw and the X-axis magnetorheological damper 65 mounted on the Y-axis ball screw constitute a cross-interlocking mechanism. During adjustment, they are in a fluid state, allowing the screw to rotate freely; after adjustment, they can instantly transform into a solid state, locking the screw movement vertically. This achieves rigid locking of the bearing position in a two-dimensional plane in a way that is free from mechanical wear and has an extremely fast response, greatly improving the positioning accuracy, rigidity, and long-term reliability of the entire actuator module.

[0087] In this application, the cross-section of the annular oil cavity 611 is trapezoidal, and the low-pressure hydraulic station is connected to the annular oil cavity 611 through a hydraulic pipeline, on which a solenoid valve is installed.

[0088] When the oil pressure in the annular oil chamber 611 rises to the set high pressure, the hydraulic flexible bushing 61 expands outward along its radial direction to release the interference fit between the stern shaft bearing 1 and the bearing housing 2 and form a micro gap.

[0089] When the pressure in the annular oil chamber 611 drops to the set low pressure, the hydraulic flexible bushing 61 returns to the pre-compression state to rebuild the interference fit between the stern shaft bearing 1 and the bearing housing 2.

[0090] The annular layout of the annular oil cavity 611 ensures that the pressurized oil is uniformly applied to the inner wall of the bushing in the circumferential direction, thereby enabling the hydraulic flexible bushing 61 to produce uniform and controllable radial deformation. This is the basis for achieving stable and unbiased release or reconstruction of the interference fit. Its trapezoidal cross-section design further optimizes the mechanical properties: First, the trapezoidal hypotenuse structure can more effectively convert the liquid pressure into radial force for the outward expansion of the bushing rubber layer when the oil pressure increases, improving the response efficiency; second, this cross-sectional shape has better structural stability under pressure, which can reduce stress concentration, enhance the pressure fatigue resistance of the oil cavity itself, and extend its service life; third, the trapezoidal design facilitates a smoother and more complete rebound of the bushing material to the pre-compressed state after the oil pressure is released, ensuring the reliability and consistency of the interference fit reconstruction.

[0091] Adjusting the stern shaft bearing 1 can be performed simultaneously in the X and Y directions, or separately. The following example illustrates this by first adjusting in the Y direction and then in the X direction. The system first controls the pressure in the annular oil chamber 611 of the hydraulic flexible bushing 61 to increase according to the bearing position adjustment command, causing it to expand radially to release the interference fit between the stern shaft bearing 1 and the bearing housing 2, creating a micro-clear gap. Simultaneously, the Y-direction magnetorheological damper 64 and the X-direction magnetorheological damper 65 are energized, causing the magnetorheological fluid inside to change to a low-viscosity fluid state. Subsequently, the Y-direction servo motor 631 of the Y-direction displacement mechanism 63 is activated first, driving the Y-direction ball screw pair 632. Since the Y-direction ball nut is fixedly connected to the X-direction ball nut of the X-direction displacement mechanism 62, the entire X-direction displacement mechanism 62 and its end stern shaft bearing 1 are moved along the Y direction to the command-set ΔY position. This step primarily ensures the alignment of the bearing and the stern shaft 4 in the vertical direction (radial), maintaining the coaxiality of the shaft system. Next, the X-axis servo motor 621 of the X-axis displacement mechanism 62 is activated, driving the X-axis ball screw pair 622 to push the stern shaft bearing 1, connected to the bearing boss 11 via a ball joint, to move along the X direction (axial direction) to the command-set ΔX position. During this process, the Y-axis mechanism mainly plays a supporting and guiding role. Throughout the driving process, the encoders of each servo motor provide real-time feedback of position information for closed-loop precise control. When the stern shaft bearing 1 reaches the target coordinate, the system immediately cuts off the current to the Y-axis magnetorheological damper 64 and the X-axis magnetorheological damper 65. The magnetorheological fluid instantly transforms into a Bingham solid state, rigidly locking the two ball screws from their vertical direction, achieving wear-free rapid locking. Finally, the hydraulic flexible bushing 61 releases oil pressure to restore the interference fit, thus completing the complete adjustment and fixing cycle from dynamic unlocking, sequential drive to double locking.

[0092] Existing active vibration suppression methods all rely on external force counteraction, using actuators to generate a reverse force along the transmission path to instantly cancel out vibration. The core of this application lies in using the position of the stern shaft bearing 1 as a control variable, actively altering the vibration transmission path characteristics by adjusting this position, thereby achieving vibration suppression at its source.

[0093] This application solves the engineering problem of traditional bearings being unable to be adjusted online due to interference fit. Existing solutions typically require an additional actuating mechanism outside the bearing housing 2, increasing system complexity and potential failure points. This application achieves dynamic unlocking through a hydraulic flexible bushing 61, precise positioning using a displacement adjustment device, and wear-free rigid locking using a magnetorheological damper, thereby completing the in-situ, online adjustment and fixation of the bearing position during operation.

[0094] Example 2

[0095] like Figures 4 to 7 As shown in the figure, this embodiment discloses a vibration suppression method based on an adjustable stern shaft bearing position, applied to the vibration suppression system based on an adjustable stern shaft bearing position described in the above embodiment, including the following steps:

[0096] S1. Obtain the frequency response function matrix of the stern structure of the hull obtained in advance through experimental modal analysis; establish a parameterized multibody dynamics model based on the frequency response function matrix; optimize the parameter vector to be corrected in the multibody dynamics model with the frequency response function matrix as the correction target, so as to minimize the error between the simulated frequency response and the experimental frequency response, and obtain the corrected digital twin model.

[0097] S2. Define the bearing's position coordinates (ΔX, ΔY) in a two-dimensional plane as design variables; in the digital twin model, minimize the vibration response amplitude of the target monitoring point as the optimization objective and set constraints; use optimization algorithms to perform iterative simulation calculations to obtain the optimal bearing position and its corresponding vibration response data under different preset working conditions or target frequencies; use spatial interpolation methods to generate a continuous and quantitative mapping relationship between bearing position and vibration response, and store it as a mapping relationship database;

[0098] S3. Continuously collect hull vibration signals in real time through the sensing module; perform real-time spectrum analysis on the collected vibration signals to identify and extract the current dominant vibration frequency and its amplitude characteristics; use the dominant vibration frequency as an index to query the mapping relationship database to obtain the optimal bearing position adjustment amount corresponding to the frequency; generate bearing position adjustment instructions containing specific X-direction displacement and Y-direction displacement based on the optimal bearing position adjustment amount.

[0099] S4. According to the bearing position adjustment command, coordinate and control each component of the bearing position adjustment execution module in a preset sequence.

[0100] In S1, the frequency response function matrix is ​​obtained in the following way:

[0101] The time-domain acceleration signal acquired in the experiment Discrete signals are obtained by digital sampling. The spectrum was obtained by fast Fourier transform. ; and adopt Estimation method for calculating frequency response function :

[0102] ;

[0103] in, For motivation With response acceleration cross power spectrum, For motivation The self-power spectrum and the FRF of all measurement points constitute the frequency response function matrix of the system. .

[0104] The equations of motion for the multibody dynamics model are:

[0105] ;

[0106] in, , , These are the mass, damping, and stiffness matrices of the system, respectively.

[0107] Model correction is achieved by minimizing the following objective function:

[0108] ;

[0109] in, This is the parameter vector to be corrected.

[0110] In S2, the optimization solution process is defined as follows:

[0111] Design variables: ;

[0112] Objective function: ;

[0113] Constraints: The constraints include shaft alignment constraints and structural strength constraints. Shaft alignment constraints ensure that the misalignment of the shaft system after bearing position adjustment is lower than a preset threshold, and structural strength constraints ensure that the maximum stress of key load-bearing components after bearing position adjustment is lower than the allowable stress of the material.

[0114] The particle swarm optimization algorithm is used, and its position and velocity update formulas are as follows:

[0115] ;

[0116] in, The particle position represents a bearing position.

[0117] S4 includes the following steps:

[0118] S41. Control the hydraulic pressure of the flexible bushing to rise to the set high pressure, so that it expands radially to release the interference fit, and at the same time energize the excitation coil of the X-axis magnetorheological damper and / or the Y-axis magnetorheological damper, so that the magnetorheological fluid is converted to a low viscosity fluid state.

[0119] S42. Based on the bearing position adjustment command, control the X-axis servo motor and / or the Y-axis servo motor to rotate, drive the X-axis ball screw pair and / or the Y-axis ball screw pair to move, and drive the stern shaft bearing to move; at the same time, perform closed-loop position control through servo motor encoder feedback until the bearing reaches the target position.

[0120] S43. Cut off the current to the excitation coil to convert the magnetorheological fluid into a Bingham solid state to lock the lead screw; then, reduce the oil pressure of the hydraulic flexible bushing to the set low pressure to restore it to the pre-compression state to rebuild the interference fit and complete the final fixation of the bearing position.

[0121] With the goal of suppressing the first-order blade frequency (123Hz) vibration of its propeller, the specific implementation process and technical details of this embodiment are described in detail as follows:

[0122] During the system identification phase, the experimental setup was first conducted. Three triaxial accelerometers (PCB352C33) were placed on bearing housing 2, and two identical sensors were placed on the bulkhead of hull 3 to ensure comprehensive capture of vibration information. A professional force hammer (PCB086C03) was used to excite the propeller hub, with the excitation point selected at a critical location in the power transmission path.

[0123] A multi-channel data acquisition instrument (NIPXIe-4499) was used to simultaneously acquire signals from all channels. The sampling frequency was set to 5120Hz, and the frequency band covered 0-2000Hz. During the data acquisition process, 30 sets of data were collected at each measurement point and averaged to reduce the impact of random errors.

[0124] Signal processing employs the following steps: First, the acquired time-domain signal... Digital sampling was performed to obtain Then, anti-aliasing filtering is performed. After applying a Hanning window, a Fast Fourier Transform is performed.

[0125] ;

[0126] When calculating the frequency response function, use Estimation method:

[0127] ;

[0128] The cross-power spectrum and self-power spectrum were calculated using the Welch method, with a segment length of 1024 points and an overlap rate of 50%, to obtain the frequency response function matrix of the system.

[0129] In the simulation modeling and correction phase, a parametric model of the stern shaft system was built using Adams / View software. The model includes major components such as the shaft system, bearings, and support structures, taking into account the material properties, geometry, and connection relationships of each part in detail. The bearing support was simulated using Busching force elements, and its radial stiffness was... , and damping , Parameters to be corrected .

[0130] During model refinement, FRF data measured experimentally around 123Hz were used as the target, and a genetic algorithm was employed for parameter optimization. The optimization objective function was:

[0131] ;

[0132] After 200 iterations, the objective function converged, and the simulation results of the corrected model showed good agreement with the experimental data, with an error of less than 5%. This corrected model was then used as a digital twin for subsequent optimization analysis.

[0133] In the mapping relationship construction phase, the optimization problem is first defined as follows:

[0134] Design variables: , mm;

[0135] Objective function: ;

[0136] Constraints: Shaft misalignment mm;

[0137] The particle swarm optimization algorithm is used to solve the problem, with 50 particles, 100 iterations, and inertia weights. Learning factor The formulas for updating particle position and velocity are:

[0138] ;

[0139] After 5000 simulations, the globally optimal solution was found. mm. At this location, the 123Hz vibration amplitude drops from 0.52m / s² to 0.39m / s², an attenuation of 25%.

[0140] Further local optimization methods, such as gradient descent, can be employed to perform fine-tuning and data supplementation on the neighboring regions in the simulation model. This improves the prediction accuracy of the mapping relationship near the optimal solution in offline mode. Finally, based on this set of calibrated simulation data, the Kriging interpolation method is used to generate the response surface function:

[0141] ;

[0142] This function precisely quantifies the mapping relationship between bearing position and target frequency vibration response, and stores it as a mapping relationship database for subsequent online control queries.

[0143] During the online control phase, intelligent operation is achieved. The system collects sensor data in real time, performs FFT analysis, and automatically identifies the dominant vibration frequency. When the dominant frequency is identified as 123Hz, the optimal bearing adjustment is obtained by querying the mapping database. mm. Position adjustment is performed using a high-precision servo actuator, with a total response time of less than 100ms.

[0144] The system continuously monitors the vibration level and uses the gradient descent method for fine-tuning.

[0145] ;

[0146] in For learning rate, The gradient of the objective function is given. During the online control phase, instead of relying on complex real-time optimization algorithms, the optimal adjustment commands are obtained by directly querying a high-precision offline mapping database, thus ensuring rapid control response (<100ms) and deterministic decision-making. The mapping database covers a preset full operating condition range, enabling the system to automatically maintain excellent vibration damping performance under different navigation conditions.

[0147] The above description is only 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 protection scope of the present invention.

Claims

1. A vibration suppression system based on adjustable stern shaft bearing position, applied to a stern shaft bearing, the stern shaft bearing being vertically installed on a ship body through a bearing seat, and a horizontally arranged stern shaft being installed in the stern shaft bearing; characterized in that, The vibration damping system includes: The sensing module is used to monitor hull vibration signals; The signal processing and control module is connected to the sensing module. The signal processing and control module stores a database of the mapping relationship between bearing position and vibration response. The signal processing and control module is used to process real-time vibration signals to identify the dominant vibration frequency and query the mapping relationship database to generate corresponding bearing position adjustment commands. The bearing position adjustment execution module is connected to the signal processing control module. The bearing position adjustment execution module is used to receive bearing position adjustment commands and drive the stern shaft bearing to move to the target position in a two-dimensional plane and then rigidly lock it.

2. The adjustable stern shaft bearing position based vibration suppression system of claim 1, wherein, The bearing position adjustment execution module includes: The hydraulic flexible bushing has a ring structure and is sleeved between the stern shaft bearing and the bearing housing. The inner wall of the hydraulic flexible bushing is recessed with an annular oil cavity, which is connected to the low-pressure hydraulic station. Two displacement adjustment devices are respectively located on both sides of the stern shaft. The displacement adjustment devices include an X-direction displacement mechanism for adjusting the stern shaft bearing along the X direction and a Y-direction displacement mechanism for adjusting the stern shaft bearing along the Y direction. The X-axis displacement mechanism is set along the axis of the stern shaft. The X-axis displacement mechanism is installed on the hull and its actuating end is connected to the stern shaft bearing. The Y-axis displacement mechanism is set perpendicularly to the X-axis displacement mechanism, and the Y-axis displacement mechanism is installed on the hull.

3. The vibration damping system based on adjustable stern shaft bearing position as described in claim 2, characterized in that, The X-axis displacement mechanism includes an X-axis servo motor and an X-axis ball screw pair; the X-axis servo motor is slidably mounted on the hull along the axis of the stern shaft; the X-axis ball screw pair includes an X-axis ball screw and an X-axis ball nut, one end of the X-axis ball screw is connected to the output shaft of the X-axis servo motor, and the other end of the X-axis ball screw is connected to the stern shaft bearing through a ball joint. The Y-axis displacement mechanism includes a Y-axis servo motor and a Y-axis ball screw pair; the Y-axis servo motor is fixedly mounted on the hull; the Y-axis ball screw pair includes a Y-axis ball screw and a Y-axis ball nut, one end of the Y-axis ball screw is connected to the output shaft of the Y-axis servo motor; the Y-axis ball nut is fixedly connected to the X-axis ball nut. The X-axis ball screw is equipped with a Y-axis magnetorheological damper arranged along the Y-axis, and the bottom end of the Y-axis magnetorheological damper is fixedly connected to the hull. The Y-axis ball screw is equipped with an X-axis magnetorheological damper arranged along the X-axis, and one end of the X-axis magnetorheological damper is connected to the stern shaft bearing.

4. The adjustable stern shaft bearing position based vibration suppression system of claim 3, wherein, The X-direction magnetorheological damper and the Y-direction magnetorheological damper have the same structure, both including a damper shell, a magnetorheological fluid filled inside the damper shell, and an excitation coil located inside the damper shell. When the excitation coil is energized, the magnetorheological fluid filling the damper housing is in a low-viscosity fluid state, allowing the corresponding ball screw to rotate freely; when the excitation coil is de-energized, the magnetorheological fluid filling the damper housing changes to a Bingham solid state, locking the corresponding ball screw.

5. The adjustable stern shaft bearing position based vibration suppression system of claim 2, wherein, The cross-section of the annular oil chamber is trapezoidal. The low-pressure hydraulic station is connected to the annular oil chamber through a hydraulic pipeline, and a solenoid valve is installed on the hydraulic pipeline. When the pressure in the annular oil chamber rises to the set high pressure, the hydraulic flexible bushing expands outward along its radial direction to release the interference fit between the stern shaft bearing and the bearing housing and form a micro gap. When the pressure in the annular oil chamber drops to the set low pressure, the hydraulic flexible bushing returns to the pre-compression state to rebuild the interference fit between the stern shaft bearing and the bearing housing.

6. A vibration suppression method based on an adjustable stern shaft bearing position, applied to the vibration suppression system based on an adjustable stern shaft bearing position as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Obtain the frequency response function matrix of the stern structure of the hull obtained in advance through experimental modal analysis; establish a parameterized multibody dynamics model based on the frequency response function matrix; optimize the parameter vector to be corrected in the multibody dynamics model with the frequency response function matrix as the correction target, so as to minimize the error between the simulated frequency response and the experimental frequency response, and obtain the corrected digital twin model. S2. Define the bearing's position coordinates (ΔX, ΔY) in a two-dimensional plane as design variables; in the digital twin model, minimize the vibration response amplitude of the target monitoring point as the optimization objective and set constraints; use optimization algorithms to perform iterative simulation calculations to obtain the optimal bearing position and its corresponding vibration response data under different preset working conditions or target frequencies; use spatial interpolation methods to generate a continuous and quantitative mapping relationship between bearing position and vibration response, and store it as a mapping relationship database; S3. Continuously collect hull vibration signals in real time through the sensing module; perform real-time spectrum analysis on the collected vibration signals to identify and extract the current dominant vibration frequency and its amplitude characteristics; use the dominant vibration frequency as an index to query the mapping relationship database to obtain the optimal bearing position adjustment amount corresponding to the frequency; generate bearing position adjustment instructions containing specific X-direction displacement and Y-direction displacement based on the optimal bearing position adjustment amount. S4. According to the bearing position adjustment command, coordinate and control each component of the bearing position adjustment execution module in a preset sequence.

7. The vibration suppression method based on adjustable stern shaft bearing position as described in claim 6, characterized in that, S4 includes the following steps: S41. Control the hydraulic pressure of the flexible bushing to rise to the set high pressure, so that it expands radially to release the interference fit, and at the same time energize the excitation coil of the X-axis magnetorheological damper and / or the Y-axis magnetorheological damper, so that the magnetorheological fluid is converted to a low viscosity fluid state. S42. Based on the bearing position adjustment command, control the X-axis servo motor and / or the Y-axis servo motor to rotate, drive the X-axis ball screw pair and / or the Y-axis ball screw pair to move, and drive the stern shaft bearing to move; at the same time, perform closed-loop position control through servo motor encoder feedback until the bearing reaches the target position. S43. Cut off the current to the excitation coil to convert the magnetorheological fluid into a Bingham solid state to lock the lead screw; then, reduce the oil pressure of the hydraulic flexible bushing to the set low pressure to restore it to the pre-compression state to rebuild the interference fit and complete the final fixation of the bearing position.

8. The vibration suppression method based on adjustable stern shaft bearing position as described in claim 6, characterized in that, In S1, the frequency response function matrix is ​​obtained in the following way: The time-domain acceleration signal acquired in the experiment Discrete signals are obtained by digital sampling. The spectrum was obtained by fast Fourier transform. ; and adopt Estimation method for calculating frequency response function : ； in, For motivation With response acceleration cross power spectrum, For motivation The self-power spectrum and the FRF of all measurement points constitute the frequency response function matrix of the system. .

9. The vibration suppression method based on adjustable stern shaft bearing position as described in claim 6, characterized in that, In S1, the equations of motion for the multibody dynamics model are: ； in, , , These are the mass, damping, and stiffness matrices of the system, respectively. Model correction is achieved by minimizing the following objective function: ； in, This is the parameter vector to be corrected.

10. The vibration suppression method based on adjustable stern shaft bearing position as described in claim 6, characterized in that, In S2, the optimization solution process is defined as follows: Design variables: ; Objective function: ; Constraints: The constraints include shaft alignment constraints and structural strength constraints. Shaft alignment constraints ensure that the misalignment of the shaft system after bearing position adjustment is lower than a preset threshold, and structural strength constraints ensure that the maximum stress of key load-bearing components after bearing position adjustment is lower than the allowable stress of the material. The particle swarm optimization algorithm is used, and its position and velocity update formulas are as follows: ； in, The particle position represents a bearing position.

Images