Sliding bearing oil film instability suppression method and device based on electromagnetic damping

Abstract

The invention discloses a sliding bearing oil film instability suppression method and device based on electromagnetic damping, and relates to the technical field of rotating machine state monitoring and fault control. The method comprises the steps of collecting a vibration signal of a rotor in real time and preprocessing the vibration signal; and performing spectral analysis on the preprocessed vibration signal, extracting an amplitude in a preset oil film instability characteristic frequency band, and determining a fault characteristic quantity based on the extracted amplitude. And comparing the fault characteristic quantity with a preset stable threshold value, and if the fault characteristic quantity exceeds the preset stable threshold value, determining that the sliding bearing is subjected to oil film instability. And when it is judged that the sliding bearing is subjected to oil film instability, a control instruction including a staged adjustment strategy is generated based on the deviation between the fault characteristic quantity and a preset stability threshold value. And based on the control instruction, by adjusting a radial gap between a permanent magnet assembly and a conductor ring assembly in the electromagnetic damping module, the electromagnetic damping force acting on the rotor is dynamically adjusted to suppress oil film instability until the fault characteristic quantity is recovered to be lower than a preset stable threshold value.

Description

Technical Field

[0001] This invention relates to the field of rotating machinery condition monitoring and fault control technology, and in particular to a method and device for suppressing oil film instability in sliding bearings based on electromagnetic damping. Background Technology

[0002] Sliding bearings are widely used in large rotating machinery such as steam turbines, generators, centrifugal compressors, and high-speed machine tools due to their advantages of high load-bearing capacity, smooth operation, and low noise. However, under high-speed and light-load operating conditions, the lubricating oil film can become relatively thick, making sliding bearings prone to oil film instability. In severe cases, this can lead to bearing wear, rotor rubbing, and even unplanned shutdowns of the unit, posing a serious threat to the safe and stable operation and service life of the equipment.

[0003] Currently, existing technologies mainly improve the stability of sliding bearings and suppress oil film instability through bearing design optimization, lubrication parameter adjustment, and the application of external control or damping. However, all of these methods have significant limitations. Methods involving bearing body modification, such as optimizing bearing structural parameters, changing the bearing type to tilting pads, or using extrusion oil film dampers, while effective to some extent, usually require redesigning, calculating, or replacing the entire bearing. This involves a large workload, high costs, and may also cause problems such as critical speed deviation and increased bearing temperature, making them difficult to apply conveniently to existing equipment. Methods involving adjusting operating parameters, such as increasing oil temperature to reduce viscosity, have limited inhibitory effects and can accelerate the deterioration of lubricating oil performance. Furthermore, the increased oil temperature may affect the normal operation of the bearing, making them unsuitable as a fundamental solution. Active control methods, such as using magnetic bearings, offer precise control, but the system is extremely complex, costly, and energy-intensive. They also present electromagnetic interference problems and require a complete overhaul of the original transmission system, limiting their applicability. Summary of the Invention

[0004] To address the problems of existing sliding bearing oil film instability suppression technologies, such as complex implementation, high cost, significant modification, easy introduction of side effects, and inability to adaptively control in real time, this invention proposes a sliding bearing oil film instability suppression method and device based on electromagnetic damping. Without altering the original bearing and lubrication system, this invention, through an additional adjustable electromagnetic damping module, applies a controllable electromagnetic damping force online and actively to the rotor system based on the real-time vibration state of the rotor. This directly counteracts the vibration energy that leads to instability, thereby effectively suppressing oil film eddy and oscillation, and improving the stability, safety, and reliability of the sliding bearing system.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] A method for suppressing oil film instability in sliding bearings based on electromagnetic damping includes:

[0007] The vibration signal of the rotor is acquired in real time and preprocessed.

[0008] Spectral analysis is performed on the preprocessed vibration signal to extract the amplitude within the preset oil film instability characteristic frequency band, and the fault characteristic quantity is determined based on the extracted amplitude.

[0009] The fault characteristic quantity is compared with the preset stability threshold. If the fault characteristic quantity exceeds the preset stability threshold, it is determined that the sliding bearing has experienced oil film instability.

[0010] When it is determined that the sliding bearing has experienced oil film instability, a control command is generated based on the deviation between the fault characteristic quantity and the preset stability threshold; the control command includes a phased adjustment strategy.

[0011] Based on control commands, the electromagnetic damping force acting on the rotor is dynamically adjusted by regulating the radial gap between the permanent magnet assembly and the conductor ring assembly in the electromagnetic damping module to suppress oil film instability until the fault characteristic quantity recovers to below the preset stability threshold.

[0012] As a preferred embodiment of the present invention, the preprocessing includes baseline drift removal, bandpass filtering, and integer period truncation.

[0013] As a preferred embodiment of the present invention, the step of determining the fault feature quantity based on the extracted amplitude includes:

[0014] The maximum value among the extracted amplitudes is selected as the fault feature quantity.

[0015] As a preferred embodiment of the present invention, the step of determining the fault feature quantity based on the extracted amplitude includes:

[0016] Based on the extracted amplitude, combined with one or more other time-domain or frequency-domain features, and fused according to preset rules, fault feature quantities are generated.

[0017] As a preferred embodiment of the present invention, the adjustment strategy includes:

[0018] When the deviation exceeds the first preset deviation threshold, the radial clearance is reduced by the first adjustment step size;

[0019] When the deviation exceeds the second preset deviation threshold but does not exceed the first preset deviation threshold, the adjustment direction is determined by directional trial, and the second large step size and the second small step size are used alternately for adjustment.

[0020] When the deviation does not exceed the second preset deviation threshold but exceeds the third preset deviation threshold, the radial clearance is adjusted using the third adjustment step.

[0021] Adjustment stops when the absolute value of the deviation does not exceed the third preset deviation threshold.

[0022] Among them, the first preset deviation threshold is greater than the second preset deviation threshold, the second preset deviation threshold is greater than the third preset deviation threshold; the first adjustment step is greater than the second large step, the second large step is greater than the second small step, and the second small step is greater than the third adjustment step.

[0023] As a preferred embodiment of the present invention, the step of determining the adjustment direction through direction probing includes:

[0024] Record deviations before the trial ;

[0025] Adjust the radial clearance in the preset initial probe direction with the second small step size, wait for the preset stabilization time, and then calculate the new deviation. The initial probing direction is to reduce the radial clearance.

[0026] when At that time, the adjustment direction is determined as the initial trial direction;

[0027] when When the current condition is determined to be in the adjustment insensitive zone, the trial step size is updated to the second largest step size, and the direction trial is restarted with the initial trial direction; among which, This represents the coefficient for the insensitive region.

[0028] As a preferred embodiment of the present invention, the dynamic adjustment of the electromagnetic damping force acting on the rotor is achieved by increasing the electromagnetic damping force by reducing the radial clearance and decreasing the electromagnetic damping force by increasing the radial clearance.

[0029] An electromagnetically damped sliding bearing oil film instability suppression device includes:

[0030] The vibration monitoring module is used to collect the vibration signals of the rotor in real time.

[0031] The signal processing module is used to preprocess and perform spectrum analysis on the vibration signal, extract the amplitude within the preset oil film instability characteristic frequency band, and determine the fault characteristic quantity based on the extracted amplitude.

[0032] The oil film instability determination module is used to compare the fault characteristic quantity with the preset stability threshold. If the fault characteristic quantity exceeds the preset stability threshold, it is determined that the sliding bearing has experienced oil film instability.

[0033] The control command generation module is used to generate control commands based on the deviation between the fault characteristic quantity and the preset stability threshold when it is determined that the sliding bearing has experienced oil film instability.

[0034] An electromagnetic damping module includes a permanent magnet assembly and a conductor ring assembly arranged radially opposite each other along the rotor; a dynamically adjustable radial gap is formed between the permanent magnet assembly and the conductor ring assembly.

[0035] The clearance adjustment mechanism is used to dynamically adjust the electromagnetic damping force acting on the rotor to suppress oil film instability by adjusting the radial clearance based on control commands, until the fault characteristic quantity recovers to below the preset stability threshold.

[0036] As a preferred embodiment of the present invention, the permanent magnet assembly includes a plurality of permanent magnets evenly distributed along the circumferential direction of the rotor, and the magnetic poles of each permanent magnet are arranged in the same radial direction.

[0037] The conductor ring assembly includes a conductor ring made of a highly conductive metallic material.

[0038] As a preferred embodiment of the present invention, the gap adjustment mechanism includes a combination of a servo motor driven adjustment mechanism and a manual screw fine-tuning mechanism.

[0039] Compared with existing technologies, the advantages of this invention are as follows: By analyzing the vibration spectrum in real time, focusing on the characteristic frequency band of oil film instability, the complex instability phenomenon is quantified into clear fault characteristics, effectively solving the pain points of traditional methods that rely on experience and have delayed judgment, and providing an immediate and reliable decision-making basis for the subsequent precise application of electromagnetic damping force. Based on real-time deviation, the optimal electromagnetic damping force increment required to suppress the current instability is dynamically calculated and output through a phased adjustment strategy, ensuring that the increase in electromagnetic damping force is precisely matched with the severity of instability, thus achieving adaptive control. With the help of the original adjustable electromagnetic damping module, the radial clearance can be directly adjusted to increase the electromagnetic damping force in a linear and precise manner; the direction of this force is always opposite to the vibration velocity, which can directly cancel the eddy energy that causes instability and suppress vibration from the physical root. In addition, the entire technical solution does not require modification of the original bearing structure or lubrication system, and can achieve non-contact, online, and active suppression effect with only an additional module, combining the advantages of high reliability, fast response, and maintenance-free operation. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 A flowchart of a sliding bearing oil film instability suppression method based on electromagnetic damping provided by the present invention; Figure 2 This is a schematic diagram of the divergence characteristics of rotor radial vibration after the instability fault of the sliding bearing oil film is triggered in an embodiment of the present invention. Figure 3 This is a schematic diagram of the attenuation and convergence characteristics of rotor radial vibration after applying electromagnetic damping in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the principle of a sliding bearing oil film instability suppression method based on electromagnetic damping in an embodiment of the present invention. Figure 5 A schematic diagram of a modular structure for a sliding bearing oil film instability suppression device based on electromagnetic damping, provided by the present invention; Figure 6 This is a schematic diagram of the circumferential arrangement of the electromagnetic damping module and the gap adjustment mechanism in an embodiment of the present invention; Figure 7 This is a schematic diagram of the axial cross-sectional structure of the electromagnetic damping module and the gap adjustment mechanism in an embodiment of the present invention;

[0041] The components include: 1. Rotor; 2. Sliding bearing; 3. Permanent magnet assembly; 4. Permanent magnet assembly mounting bracket; 5. Conductor ring assembly; 6. Honeycomb heat dissipation structure; 7. Insulating ring; and 8. Bearing housing. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0043] like Figure 1 As shown, this is an embodiment of the present invention, which provides a method for suppressing oil film instability in sliding bearings based on electromagnetic damping, comprising:

[0044] S1 acquires the rotor's vibration signal in real time and preprocesses the vibration signal. The preprocessing includes baseline drift removal, bandpass filtering, and integer cycle truncation.

[0045] Furthermore, an eddy current displacement sensor is installed on the bearing housing perpendicular to the rotor surface. After installation, the sensor needs to be calibrated so that its initial operating point is located at the midpoint of the linear measurement range.

[0046] This sensor is used to acquire the radial vibration displacement signal of the rotor, and simultaneously acquires the speed pulse signal output by the speed sensor mounted on the shaft. The sampling frequency setting must satisfy the Nyquist sampling theorem and completely cover the characteristic frequency range of oil film instability. For a rotor with a maximum operating speed of 3000 rpm, its rotational frequency is 50 Hz. The dominant characteristic frequency of oil film instability is 0.4 to 0.5 times the rotational frequency. Considering higher harmonics, the analysis bandwidth usually needs to be extended to 250 Hz. Therefore, the sampling frequency is usually set to no less than 500 Hz, preferably 1 kHz, to ensure distortion-free signal acquisition.

[0047] The collected vibration signals undergo preprocessing, specifically including:

[0048] The least squares method or the moving average method is used to remove baseline drift in order to eliminate low-frequency interference caused by factors such as sensor zero-point drift.

[0049] A zero-phase digital filter is selected for the bandpass filter. To effectively extract oil film instability characteristics and suppress interference, the passband frequency range is typically set to 15Hz to 400Hz. Optionally, a narrowband bandstop filter with a center frequency of 50Hz is superimposed within the passband to filter out power frequency interference.

[0050] The whole-cycle truncation requires using the synchronously acquired rotational speed pulse signal as a trigger reference to truncate the filtered signal into data blocks that are integer multiples of one rotor rotation cycle. If the data length is less than an integer cycle, zeros are padded at the end. The purpose of this operation is to eliminate spectral leakage in subsequent spectrum analysis and improve spectral resolution.

[0051] By acquiring vibration signals in real time, the actual operating state of the rotor is continuously and directly monitored, providing immediate and raw data support for instability determination. Preprocessing the vibration signals can improve the accuracy and reliability of subsequent spectrum analysis and ensure the accuracy of fault feature extraction.

[0052] S2, perform spectrum analysis on the preprocessed vibration signal, extract the amplitude within the preset oil film instability characteristic frequency band, and determine the fault characteristic quantity based on the extracted amplitude.

[0053] Furthermore, for the truncated data segment, a Hanning window is first applied to reduce spectral leakage, followed by a Fast Fourier Transform (FFT) to obtain the frequency-amplitude spectrum. The FFT needs to have a sufficient number of points to ensure adequate frequency resolution within the band of interest, typically no less than 1024 points.

[0054] The preset oil film instability characteristic frequency band is usually set to 0.4 to 0.5 times the rotational frequency based on the mechanism of oil film instability. Those skilled in the art can make fine adjustments within this range according to the specific bearing type and operating conditions.

[0055] Based on the extracted amplitude, fault characteristic quantities are determined, including:

[0056] Option 1: Select the maximum value among the extracted amplitudes as the fault feature quantity.

[0057] Furthermore, the spectral line with the largest amplitude within a preset characteristic frequency band is identified in the spectrum, and its corresponding amplitude is the fault characteristic quantity. To obtain a more accurate peak value, spectral line interpolation is used for estimation.

[0058] Option 2: Based on the extracted amplitude, combine it with one or more other time-domain features or frequency-domain features, and fuse them according to preset rules to generate fault feature quantities.

[0059] Furthermore, the time-domain features include the effective value and kurtosis of the vibration signal; the frequency-domain features include the band energy of the characteristic frequency band; and the preset rules include weighted averaging. In a preferred embodiment, the preset weighting rule is the fault characteristic quantity. ,in, The extracted amplitude. This represents the effective value of the vibration signal. The kurtosis is the vibration signal. , and These are the corresponding weight coefficients, and they satisfy... . The recommended value is 0.6. The recommended value is 0.2. The recommended value is 0.2. The weighting coefficients can be fine-tuned through experiments based on actual working conditions.

[0060] Spectral analysis is performed on the preprocessed vibration signal to convert the time-domain vibration signal to the frequency domain, thereby accurately locating and identifying characteristic components within the characteristic frequency band of oil film instability. By extracting the amplitude of this characteristic frequency band to determine the fault characteristic quantity, the complex vibration spectrum information can be quantified into an intuitive and comparable single indicator, providing a clear and objective quantitative basis for subsequent instability determination.

[0061] S3. Compare the fault characteristic quantity with the preset stability threshold. If the fault characteristic quantity exceeds the preset stability threshold, it is determined that the sliding bearing has experienced oil film instability.

[0062] Furthermore, the preset stability threshold can be set according to the design parameters, operating conditions, and safety margin requirements of the bearing system. In a preferred embodiment, the preset stability threshold is set using an experimental calibration method. Specifically, on a bearing test bench, the sliding bearing is slowly transitioned from stable operation to a critical state near instability. The amplitude under this state is monitored and recorded in real time, and the average value of three consecutive sets of stable data is taken as the benchmark value. Set the preset stability threshold to .in, For safety, a value between 0.6 and 0.9 is recommended to balance the timeliness and reliability of the warning and avoid false alarms.

[0063] The criteria for determining the critical state are: when the amplitude change rate in the preset oil film instability characteristic frequency band exceeds 5% per second, or when the total amplitude of rotor vibration reaches 30% of the allowable radial clearance of the bearing, it is determined to be close to the critical state of instability.

[0064] By comparing the quantified fault characteristics with the preset stability threshold, the oil film instability state can be automatically and objectively determined, replacing the uncertainty of relying on human experience. This step can issue timely and accurate warnings in the early stage of instability or before the amplitude reaches a dangerous level, thus buying valuable time for subsequent targeted damping force adjustments.

[0065] S4, when it is determined that oil film instability has occurred in the sliding bearing, a control command is generated based on the deviation between the fault characteristic quantity and the preset stability threshold. The control command includes a phased adjustment strategy.

[0066] Regulation strategies include:

[0067] When the deviation exceeds the first preset deviation threshold, the radial clearance is reduced by the first adjustment step.

[0068] When the deviation exceeds the second preset deviation threshold but does not exceed the first preset deviation threshold, the adjustment direction is determined by directional trial, and the second large step size and the second small step size are used alternately for adjustment.

[0069] When the deviation does not exceed the second preset deviation threshold but exceeds the third preset deviation threshold, the radial clearance is adjusted using the third adjustment step.

[0070] Adjustment stops when the absolute value of the deviation does not exceed the third preset deviation threshold.

[0071] Specifically, the first preset deviation threshold is greater than the second preset deviation threshold, and the second preset deviation threshold is greater than the third preset deviation threshold. The first adjustment step size is greater than the second largest step size, the second largest step size is greater than the second smallest step size, and the second smallest step size is greater than the third adjustment step size.

[0072] Furthermore, the deviation threshold is determined based on the development rate of oil film instability and the control response characteristics. Specifically, the first preset deviation threshold can be set to 0.3 to 0.5 times the preset stability threshold, corresponding to a severe instability state; the second preset deviation threshold is set to 0.1 to 0.3 times the preset stability threshold, corresponding to a moderate instability state; and the third preset deviation threshold is set to 0.05 to 0.1 times the preset stability threshold, corresponding to a slight instability state.

[0073] The design of the adjustment step size is closely related to the scientific setting of the initial radial clearance, and the two together constitute the parameter basis of the adaptive control strategy.

[0074] The initial radial clearance is set according to the principles of safety first and adjustable damping, with a safe design range of 0.5 mm to 2 mm. The lower limit of 0.5 mm provides sufficient safety margin for the rotor's maximum transient vibration, thermal expansion, and cumulative assembly errors, fundamentally eliminating the risk of mechanical collision between the permanent magnet assembly and the conductor ring assembly. The upper limit of 2 mm ensures that the magnetic induction intensity at the clearance does not excessively attenuate due to excessive distance, preserving a sufficiently strong initial magnetic field, thus providing effective adjustment space for subsequently reducing the clearance to significantly increase the damping force. In engineering implementation, this clearance is usually preset to the middle value within the above range during installation. Subsequently, final fine-tuning and verification are performed, and this optimized value is locked as the baseline value.

[0075] Based on the initial radial clearance set above, the adjustment step size for each stage is determined according to the following rules to achieve a response that matches the degree of instability:

[0076] The first adjustment step size is set to 5% to 10% of the initial radial clearance. This step size is specifically designed for the rapid approach phase, in cases of severe instability, to quickly establish a strong electromagnetic damping force to curb the trend of vibration deterioration.

[0077] The second large step size is set to 2% to 5% of the initial radial clearance, and the second small step size is set to 0.5% to 2% of the initial radial clearance. The two are used together during the trial search phase. By probing the direction with the second large step size and finely adjusting with the second small step size, a balance is achieved between search efficiency and adjustment accuracy.

[0078] The third adjustment step size is set to 0.1% to 0.5% of the initial radial clearance. This extremely small step size is dedicated to the steady-state fine-tuning stage, enabling precise correction of the electromagnetic damping force, thereby stabilizing the system below the target threshold with minimal, necessary damping force increments.

[0079] Determining the adjustment direction through directional probing includes:

[0080] Record deviations before the trial .

[0081] Adjust the radial clearance in the preset initial probe direction with the second small step size, wait for the preset stabilization time, and then calculate the new deviation. The initial probe direction was to reduce the radial clearance.

[0082] when At that time, the adjustment direction is determined as the initial trial direction.

[0083] when When the current situation is determined to be in the adjustment insensitive zone, the trial step size is updated to the second largest step size, and the direction trial is restarted with the initial trial direction. This represents the coefficient for the insensitive region.

[0084] Furthermore, the preset settling time is determined based on the rotor speed, typically set to 2 to 5 rotor rotation cycles to ensure a sufficiently stable system response. Insensitive zone coefficient. The value is determined based on the adjustment resolution of the electromagnetic damping module and the vibration signal noise level, and is set to 0.05 to 0.1.

[0085] The control objective of the above-mentioned phased adjustment strategy is to match radial clearance adjustment actions of different intensities according to the severity of oil film instability. The fundamental purpose is to inject an additional electromagnetic damping force of controllable magnitude and definite direction into the rotor system. Specifically:

[0086] During the rapid approach phase, if the instability is severe, a large step size is used to quickly reduce the gap in order to rapidly establish a sufficiently large electromagnetic damping force, thereby suppressing the tendency of vibration divergence.

[0087] During the trial search and steady-state fine-tuning phase, when the degree of instability decreases, a finer step size is used to precisely optimize the electromagnetic damping force, find the minimum electromagnetic damping force value that can just stabilize the system, avoid other problems that may be caused by excessive electromagnetic damping force, and thus achieve the optimal balance between suppressing instability and system energy consumption and temperature rise.

[0088] Therefore, the essence of this adjustment strategy is to dynamically calculate and output the optimal electromagnetic damping force increment required to just offset the oil film eddy energy and restore the system to a positive damping state based on real-time feedback, and to achieve this by adjusting the radial clearance.

[0089] S5, based on control commands, dynamically adjusts the electromagnetic damping force acting on the rotor by adjusting the radial gap between the permanent magnet assembly and the conductor ring assembly in the electromagnetic damping module to suppress oil film instability until the fault characteristic quantity recovers to below the preset stability threshold.

[0090] Among them, the electromagnetic damping force acting on the rotor is dynamically adjusted by increasing the electromagnetic damping force by reducing the radial clearance and decreasing the electromagnetic damping force by increasing the radial clearance.

[0091] Furthermore, in order to clarify the physical mechanism by which electromagnetic damping suppresses oil film instability, a theoretical analysis of the vibration characteristics of oil film instability and its damping suppression is first conducted.

[0092] Radial vibration signal of the rotor during oil film instability fault occurrence. It can be represented as:

[0093] ;

[0094] In the formula, This represents the initial amplitude of the rotor's radial vibration. is the inherent damping coefficient of the system, used to characterize the inherent attenuation characteristics of the sliding bearing system. The characteristic frequency of rotor oil film whirl is given, and the corresponding characteristic frequency range of oil film instability is given, satisfying the following conditions. ,in, The characteristic frequency of oil film eddy is denoted as . This is the initial phase of the rotor radial vibration, i.e., the initial phase angle of the rotor radial vibration at the moment of oil film instability excitation. For time.

[0095] like Figure 2 As shown, if the system's inherent damping coefficient A value less than zero indicates that the system is in a negative damping state, and vibration energy will continue to be input, which will lead to radial vibration divergence of the rotor and trigger oil film instability fault.

[0096] To suppress this fault, an additional damping effect can be introduced through an electromagnetic damping module, which will correspondingly generate an increment in the electromagnetic damping coefficient. This increment is related to the damping coefficient of the electromagnetic damping module. They are positively correlated, and at this time the total damping coefficient of the system is New rotor radial vibration signal Updated to:

[0097] ;

[0098] like Figure 3 As shown, when additional damping Large enough to make When the system returns to a positive damping state, the vibration signal will gradually attenuate, and the oil film instability fault will be suppressed accordingly.

[0099] The specific principles of electromagnetic damping force generation and adjustment are as follows:

[0100] When oil film eddy currents occur in the rotor, the conductor ring assembly vibrates with the rotor and generates radial relative motion with the permanent magnet assembly. This relative motion causes the conductor ring to cut magnetic lines of force, inducing eddy currents within it. These eddy currents interact with the magnetic field, generating an electromagnetic damping force that opposes the relative motion. And satisfy ,in, The vortex velocity of the rotor. This represents the electromagnetic damping coefficient. Therefore, to suppress oil film instability, the key lies in providing a sufficiently large and real-time adjustable electromagnetic damping force. .

[0101] Electromagnetic damping coefficient It mainly depends on the system structural parameters and the gap magnetic field; the core relationship can be simplified as follows: In the formula, The area of ​​the conductor ring that effectively cuts the magnetic field lines. The resistivity of the conductor ring material. For the conductor ring thickness, radial clearance The magnetic flux density at that location. Wherein, the magnetic flux density... It is radial clearance. The strong function of radial clearance The decrease significantly enhances the effect.

[0102] Therefore, based on control commands, the radial clearance is reduced through the clearance adjustment mechanism. It can drastically increase the magnetic induction intensity. This results in the electromagnetic damping coefficient and electromagnetic damping force Significantly enhances performance and effectively suppresses oil film whirl; conversely, it increases radial clearance. This reduces the electromagnetic damping force. .

[0103] It can be seen that by reducing the radial clearance in real time and actively enhancing the electromagnetic damping force, a controllable positive damping increment is injected into the system in a negative damping state, thereby stabilizing the rotor motion.

[0104] like Figure 4 As shown in the figure, the horizontal and vertical vibration arrows represent the whirl trajectory formed by the rotor within the bearing bore when the oil film becomes unstable. The horizontal and vertical damping force arrows represent the vector decomposition of the controllable electromagnetic damping force generated by the electromagnetic damping module in the horizontal and vertical directions, respectively. The direction of this electromagnetic damping force is always opposite to the instantaneous vibration velocity of the rotor, thereby achieving the dissipation and suppression of vibration energy.

[0105] like Figure 5 As shown, another embodiment of the present invention provides a sliding bearing oil film instability suppression device based on electromagnetic damping. The device includes a vibration monitoring module, a signal processing module, an oil film instability determination module, a control command generation module, an electromagnetic damping module, and a clearance adjustment mechanism.

[0106] The vibration monitoring module is used to collect the vibration signals of rotor 1 in real time.

[0107] Furthermore, the vibration monitoring module includes an eddy current displacement sensor, a speed sensor, and a data acquisition unit. The speed sensor outputs a pulse signal synchronized with the rotor 1's speed to achieve full-cycle truncation.

[0108] The signal processing module is used to preprocess and perform spectrum analysis on the vibration signal, extract the amplitude within the preset oil film instability characteristic frequency band, and determine the fault characteristic quantity based on the extracted amplitude.

[0109] Furthermore, the signal processing module is typically implemented by an embedded processor or industrial computer, including a data preprocessing unit and a spectrum analysis unit.

[0110] The data preprocessing unit is used to preprocess the vibration signal and send the preprocessed data to the spectrum analysis unit.

[0111] The spectrum analysis unit is used to perform spectrum analysis, extract the amplitude within the preset oil film instability characteristic frequency band, and determine the fault characteristic quantity based on the extracted amplitude.

[0112] The oil film instability determination module is used to compare the fault characteristic quantity with the preset stability threshold. If the fault characteristic quantity exceeds the preset stability threshold, it is determined that the sliding bearing 2 has experienced oil film instability.

[0113] Furthermore, the oil film instability determination module is integrated into the controller, which is responsible for comparing fault characteristic quantities with thresholds and making an instability determination.

[0114] The control command generation module is used to generate control commands based on the deviation between the fault characteristic quantity and the preset stability threshold when it is determined that the sliding bearing 2 has experienced oil film instability.

[0115] Furthermore, the control command generation module is typically a dedicated controller that works in conjunction with the oil film instability determination module. Upon receiving an instability determination signal, it immediately generates a command containing specific adjustment actions based on the real-time deviation and sends the command to the clearance adjustment mechanism. During trial and error phases where the adjustment effect needs to be evaluated, the control command generation module, after issuing an adjustment command, waits for a preset stabilization time. It then actively obtains the latest fault characteristic quantities from the oil film instability determination module and recalculates the real-time deviation, using this as the basis for evaluating the adjustment effect and deciding on the next action.

[0116] The electromagnetic damping module includes a permanent magnet assembly 3 and a conductor ring assembly 5 arranged radially opposite each other along the rotor 1; wherein a dynamically adjustable radial gap is formed between the permanent magnet assembly 3 and the conductor ring assembly 5. The permanent magnet assembly 3 includes a plurality of permanent magnets evenly distributed along the circumference of the rotor, and the magnetic poles of each permanent magnet are arranged in the same radial direction. The conductor ring assembly 5 includes a conductor ring made of a highly conductive metal material.

[0117] Furthermore, the permanent magnet assembly 3 features circumferentially distributed and radially aligned magnetic poles to ensure that the eddy currents of the rotor 1 can cut magnetic field lines in any direction, generating an effective and directional electromagnetic damping force. The conductor ring assembly 5 can be selected from copper and 6061 aluminum alloy depending on the operating conditions, and its thickness is optimized, for example, set to 50 mm, to achieve a balance between ensuring sufficient induced current density, controlling structural weight, and suppressing the skin effect.

[0118] The conductor ring assembly 5 is coaxially fixed to the rotor 1 and rotates synchronously with it at high speed through a rotor integrated structure that meets electrical insulation requirements. In a preferred embodiment, the rotor integrated structure includes: a stepped shaft section machined on the shaft body of the rotor 1 for axial positioning; an interference fit between the inner hole of the conductor ring assembly 5 and the stepped shaft section to achieve radial positioning and torque transmission; and a high-temperature resistant insulating clamping ring, which uses multiple circumferentially distributed countersunk bolts to axially press the conductor ring assembly 5 between the shoulder of the stepped shaft section and the insulating clamping ring.

[0119] To completely eliminate eddy current short circuits, insulating rings 7 made of high-strength engineering plastic are installed between the metal surfaces of the conductor ring assembly 5 and the rotor 1, and between the conductor ring assembly 5 and the insulating clamping ring. The high-strength engineering plastic can be polyetheretherketone (PEEK). The insulating rings 7 ensure that the induced eddy current loop exists only within the conductor ring assembly 5, effectively preventing leakage and improving electromagnetic damping efficiency.

[0120] In addition, after the above assembly is completed, the rotor section containing the conductor ring assembly 5 needs to be dynamically balanced to eliminate new unbalanced vibrations caused by the added mass.

[0121] In a specific embodiment, such as Figure 6 and Figure 7As shown, the permanent magnet assembly 3 is fixed to the bearing seat 8 by the permanent magnet assembly mounting bracket 4, and is evenly distributed along the circumference, corresponding to the 0°, 90°, 180° and 270° orientations respectively. Each permanent magnet assembly 3 contains multiple permanent magnets. To achieve the shortest magnetic flux closed loop effect, multiple identical permanent magnets are arranged closely side by side, with all N poles facing the same side, forming a uniform radial magnetic field. The smaller the gap between the permanent magnets, the better. To reduce magnetic leakage, soft magnetic material such as low-carbon steel or pure iron plate is attached to the tail end magnetic pole face. The conductor ring assembly 5 is isolated from adjacent components by the insulating ring 7, and is fixed on the rotating shaft and rotates with the shaft. In addition, the two axial end faces of the conductor ring assembly 5 are designed with a regular hexagonal honeycomb heat dissipation structure 6. The honeycomb depth is recommended to be set to 3 mm to 5 mm. This structure increases the heat dissipation area and timely dissipates the Joule heat generated by the eddy current effect, ensuring the conductivity of the conductor ring and the long-term operational stability of the system.

[0122] The electromagnetic damping module is an innovative component of this device. It features a compact structure, convenient installation, and requires no major modifications to the existing bearing system. Furthermore, the electromagnetic damping force generated by this module is synchronized with the vibration velocity of rotor 1 in real time, exhibiting characteristics such as non-contact wear, fast response speed, and wide adjustable range, effectively improving the operational stability of sliding bearing 2.

[0123] The clearance adjustment mechanism is used to suppress oil film instability by dynamically adjusting the electromagnetic damping force acting on the rotor based on control commands and adjusting the radial clearance, until the fault characteristic value recovers to below the preset stability threshold. The clearance adjustment mechanism includes a combination of a servo motor-driven adjustment mechanism and a manual screw fine-tuning mechanism.

[0124] Furthermore, the gap adjustment mechanism can be installed on the bearing housing 8 or fixed on a dedicated bracket on the bearing housing 8, and its output end is connected to the mounting back plate of the permanent magnet assembly 3 through a stainless steel adapter plate. The servo motor driven adjustment mechanism and the manual screw fine-tuning mechanism are arranged at a 90-degree offset along the circumference of the mounting back plate of the permanent magnet assembly 3.

[0125] The servo motor drive mechanism is the main adjustment mechanism, used for automatic and high-precision adjustment under normal operating conditions; the manual screw fine-tuning mechanism serves as a backup adjustment structure, used for emergency adjustment when the servo fails, thus balancing automation and reliability.

[0126] Servo motor drive mechanisms typically include servo motors, reducers, precision ball screws, and displacement sensors, enabling high-precision, high-response position control.

[0127] In one specific embodiment, the core components of the manual screw fine-tuning mechanism include an adjusting screw, a locking nut, and a dial. The adjusting screw is made of 45# quenched and tempered steel, with a pitch set at 0.5 mm, an effective adjustment stroke of 1.5 mm, and a single-turn adjustment displacement of 0.5 mm. Combined with the dial, it can achieve micro-displacement adjustments of no more than 0.005 mm. The adjusting nut is made of copper alloy and integrates a locking washer. The working principle of this mechanism is as follows: rotating the graduated adjusting knob drives the adapter plate to move the permanent magnet assembly 3 radially in minute increments via the screw and nut's helical transmission, thereby precisely changing the radial clearance. The switching logic between the two mechanisms is as follows: When the servo motor drive mechanism is working normally, the locking washer of the manual screw fine adjustment mechanism is in a tightened state, and the screw and the adapter plate maintain non-rigid contact to avoid the screw rotating during servo adjustment; if the servo mechanism malfunctions, the operator can first loosen the locking washer and manually adjust by rotating the scale knob. During adjustment, the real-time data of the vibration monitoring module should be observed until the fault characteristic quantity drops below the threshold, and then the locking washer is tightened to lock the current position.

[0128] Specifically, reducing the radial clearance can enhance the magnetic field and electromagnetic damping force, and vice versa, so as to achieve continuous and precise control of the electromagnetic damping force. When the amplitude recovers and stabilizes below the preset stability threshold, the servo motor drive mechanism stops adjusting and maintains the current clearance through the self-locking function. If instability occurs again, the adjustment process is restarted. If the servo motor drive mechanism fails, manual adjustment can be performed using a manual screw fine-tuning mechanism.

[0129] In summary, this invention proposes a method and device for suppressing oil film instability in sliding bearings based on electromagnetic damping. This method actively and precisely enhances the electromagnetic damping force applied to the rotor, directly counteracting and eliminating the negative damping effect that leads to instability. Specifically, at the sensing and diagnostic level, high-frequency sampling and real-time spectrum analysis continuously focus on and quantify the vibration energy of the characteristic frequency band of oil film instability, achieving accurate and early identification of instability precursors. This provides crucial quantitative input for determining how much electromagnetic damping force needs to be added, realizing a shift from passive processing to active intervention. At the decision-making and control level, an innovative phased intelligent adjustment strategy based on real-time deviation grading is adopted. This adjustment strategy dynamically calculates and decides the precise value and optimal application sequence of the electromagnetic damping force required to suppress instability based on the severity of the instability, achieving a leap from fixed adjustment to adaptive precision control. At the execution and vibration suppression level, by linearly and continuously adjusting the radial gap between the permanent magnet assembly and the conductor ring assembly in the electromagnetic damping module, the physical action of increasing the electromagnetic damping force is directly executed. The direction of this increased electromagnetic damping force is always opposite to the rotor whirl velocity, thereby directly and efficiently counteracting the whirl energy that causes instability. This is the direct physical means by which the present invention suppresses instability. At the system integration and engineering implementation level, this device adopts a modular and add-on design, ensuring that the above-mentioned function of enhancing damping force can be easily loaded into existing units. The redundant design of the adjustment mechanism ensures the continuity and reliability of this core function of enhancing damping force. Finally, through the innovative synergy of the above four levels, the present invention successfully provides a systematic solution that can inject controllable additional electromagnetic damping force online in real time without relying on modification of the bearing body. By actively enhancing the damping force, the negative damping state of the system is directly reversed, thereby fundamentally achieving efficient and precise suppression of oil film instability, and significantly improving the operational stability and safety of the equipment.

[0130] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for suppressing oil film instability in sliding bearings based on electromagnetic damping, characterized in that, include: The vibration signal of the rotor is acquired in real time and preprocessed. Spectral analysis is performed on the preprocessed vibration signal to extract the amplitude within the preset oil film instability characteristic frequency band, and the fault characteristic quantity is determined based on the extracted amplitude. The fault characteristic quantity is compared with the preset stability threshold. If the fault characteristic quantity exceeds the preset stability threshold, it is determined that the sliding bearing has experienced oil film instability. When it is determined that the sliding bearing has experienced oil film instability, a control command is generated based on the deviation between the fault characteristic quantity and the preset stability threshold; the control command includes a phased adjustment strategy. Based on control commands, the electromagnetic damping force acting on the rotor is dynamically adjusted by regulating the radial gap between the permanent magnet assembly and the conductor ring assembly in the electromagnetic damping module to suppress oil film instability until the fault characteristic quantity recovers to below the preset stability threshold.

2. The method for suppressing oil film instability in sliding bearings based on electromagnetic damping according to claim 1, characterized in that, The preprocessing includes baseline drift removal, bandpass filtering, and integer truncation.

3. The method for suppressing oil film instability in sliding bearings based on electromagnetic damping according to claim 1, characterized in that, The determination of fault feature quantities based on the extracted amplitude includes: The maximum value among the extracted amplitudes is selected as the fault feature quantity.

4. The method for suppressing oil film instability in sliding bearings based on electromagnetic damping according to claim 1, characterized in that, The determination of fault feature quantities based on the extracted amplitude includes: Based on the extracted amplitude, combined with one or more other time-domain or frequency-domain features, and fused according to preset rules, fault feature quantities are generated.

5. The method for suppressing oil film instability in sliding bearings based on electromagnetic damping according to claim 1, characterized in that, The adjustment strategy includes: When the deviation exceeds the first preset deviation threshold, the radial clearance is reduced by the first adjustment step size; When the deviation exceeds the second preset deviation threshold but does not exceed the first preset deviation threshold, the adjustment direction is determined by directional trial, and the second large step size and the second small step size are used alternately for adjustment. When the deviation does not exceed the second preset deviation threshold but exceeds the third preset deviation threshold, the radial clearance is adjusted using the third adjustment step. Adjustment stops when the absolute value of the deviation does not exceed the third preset deviation threshold. Among them, the first preset deviation threshold is greater than the second preset deviation threshold, the second preset deviation threshold is greater than the third preset deviation threshold; the first adjustment step is greater than the second large step, the second large step is greater than the second small step, and the second small step is greater than the third adjustment step.

6. The method for suppressing oil film instability in sliding bearings based on electromagnetic damping according to claim 5, characterized in that, The process of determining the adjustment direction through directional probing includes: Record deviations before the trial ; Adjust the radial clearance in the preset initial probe direction with the second small step size, wait for the preset stabilization time, and then calculate the new deviation. The initial probing direction is to reduce the radial clearance. when At that time, the adjustment direction is determined as the initial trial direction; when When the current condition is determined to be in the adjustment insensitive zone, the trial step size is updated to the second largest step size, and the direction trial is restarted with the initial trial direction; among which, This represents the coefficient for the insensitive region.

7. The method for suppressing oil film instability in sliding bearings based on electromagnetic damping according to claim 1, characterized in that, The dynamic adjustment applies electromagnetic damping force to the rotor by increasing the electromagnetic damping force by reducing the radial clearance and decreasing the electromagnetic damping force by increasing the radial clearance.

8. A sliding bearing oil film instability suppression device based on electromagnetic damping, used to implement the sliding bearing oil film instability suppression method based on electromagnetic damping as described in any one of claims 1 to 7, characterized in that, include: The vibration monitoring module is used to collect the vibration signals of the rotor in real time. The signal processing module is used to preprocess and perform spectrum analysis on the vibration signal, extract the amplitude within the preset oil film instability characteristic frequency band, and determine the fault characteristic quantity based on the extracted amplitude. The oil film instability determination module is used to compare the fault characteristic quantity with the preset stability threshold. If the fault characteristic quantity exceeds the preset stability threshold, it is determined that the sliding bearing has experienced oil film instability. The control command generation module is used to generate control commands based on the deviation between the fault characteristic quantity and the preset stability threshold when it is determined that the sliding bearing has experienced oil film instability. An electromagnetic damping module includes a permanent magnet assembly and a conductor ring assembly arranged radially opposite each other along the rotor, with a dynamically adjustable radial gap formed between the permanent magnet assembly and the conductor ring assembly. The clearance adjustment mechanism is used to dynamically adjust the electromagnetic damping force acting on the rotor to suppress oil film instability by adjusting the radial clearance based on control commands, until the fault characteristic quantity recovers to below the preset stability threshold.

9. The sliding bearing oil film instability suppression device based on electromagnetic damping according to claim 8, characterized in that, The permanent magnet assembly includes a plurality of permanent magnets evenly distributed along the circumference of the rotor, and the magnetic poles of each permanent magnet are arranged in the same radial direction. The conductor ring assembly includes a conductor ring made of a highly conductive metallic material.

10. The sliding bearing oil film instability suppression device based on electromagnetic damping according to claim 8, characterized in that, The gap adjustment mechanism includes a combination of a servo motor driven adjustment mechanism and a manual screw fine-tuning mechanism.

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