Magnetic thrust bearing longitudinal vibration detection device and verification method

Abstract

The invention belongs to the technical field of magnetic thrust bearing vibration reduction and isolation, and provides a magnetic thrust bearing longitudinal vibration detection device and a verification method. Firstly, the advantage of non-contact measurement of a laser displacement sensor is utilized to realize accurate measurement of longitudinal vibration of the magnetic thrust bearing in a rotating state; secondly, the vertical position of the laser displacement sensor is adjusted through a manual displacement platform fixed to the main body device; and finally, synchronous adjustment of the positions of the two laser displacement sensors is realized by using a synchronous linkage device. According to the method for detecting the longitudinal vibration of the magnetic thrust bearing, vibration analysis is carried out on the specific frequency band of the magnetic thrust bearing through a time domain filtering method, and therefore the longitudinal vibration level fall of the magnetic thrust bearing under different frequency bands can be rapidly and accurately evaluated. The method has good practical application performance in the aspect of practical engineering application, operation is easy, and calculation is accurate.

Description

Technical Field

[0001] This invention belongs to the field of magnetic thrust bearing vibration reduction and isolation technology, and relates to a longitudinal vibration detection device and calibration method for magnetic thrust bearings. Background Technology

[0002] Large underwater equipment such as unmanned underwater vehicles (UUVs) are crucial to my country's national defense and security. Their acoustic stealth performance directly impacts the survivability of underwater equipment and my country's national defense security. Propulsion shaft noise is a major source of noise for underwater equipment and a core factor limiting its acoustic stealth performance. Traditional propulsion shaft systems often use contact transmission, resulting in limited vibration reduction. Permanent magnet propulsion shaft systems, however, utilize the non-contact transmission characteristics of magnetic force, significantly reducing vibration and noise. Specifically, permanent magnet thrust bearings achieve non-contact transmission of axial thrust through the interaction force between permanent magnets on the stator and rotor, effectively reducing the longitudinal vibration of the thrust bearing and even the entire shaft system. Therefore, the longitudinal vibration reduction effect of the thrust bearing is of significant value in evaluating the vibration reduction effect of the transmission shaft system. Since large underwater equipment such as UUVs have even more stringent requirements for acoustic stealth during navigation, the vibration measurement of thrust bearings must assess not only the static vibration reduction effect but also the vibration reduction effect during shaft rotation. The longitudinal vibration level drop of a permanent magnet thrust bearing is the most intuitive way to reflect its vibration reduction effect. The accurate detection of the longitudinal vibration of the inner rotor under rotating conditions is the key to calculating the longitudinal vibration level drop of the permanent magnet thrust bearing. Therefore, developing a longitudinal vibration detection device and calibration method for permanent magnet thrust bearings is of great significance for evaluating the vibration reduction effect of permanent magnet thrust bearings.

[0003] Regarding bearing vibration detection devices, Cheng Yuquan proposed using three internal support plates to position bearings of different sizes with measuring capabilities in his patent "A Measuring Device for Bearing Mechanical Vibration" (CN120121299A). While this greatly improves the measurement range, it cannot measure the longitudinal vibration of magnetic thrust bearings. Regarding longitudinal vibration verification methods in rotating shaft systems, Xia Yu of Dalian University of Technology, in his 2023 master's thesis "Research on Vibration Monitoring of Ship Propulsion Shafts Based on Triaxial Accelerometers," fixed a triaxial accelerometer to the shaft with magnets and collected data using an infinite acquisition module. Although this method can measure the longitudinal vibration of the shaft system, it requires binding the acquisition module to the shaft, increasing the shaft's instability and making it susceptible to interference from electromagnetic and acoustic fields at the measurement site, thus limiting measurement accuracy.

[0004] Therefore, proposing a non-contact magnetic thrust bearing longitudinal vibration detection device and calibration method is of great significance for evaluating the longitudinal vibration reduction effect of permanent magnet thrust bearings and for studying the low-noise design and characteristics of magnetic thrust bearings. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a longitudinal vibration detection device and calibration method for magnetic thrust bearings. Its purpose is to leverage the non-contact measurement advantages of laser displacement sensors to achieve accurate measurement of the longitudinal vibration of magnetic thrust bearings under rotational conditions. Furthermore, by employing time-domain filtering to analyze vibrations within specific frequency bands of the magnetic thrust bearing, it enables rapid and accurate assessment of the longitudinal vibration level difference across different frequency bands. This method is simple to operate, computationally accurate, and highly practical in engineering applications.

[0006] The technical solution of the present invention:

[0007] A longitudinal vibration detection device for magnetic thrust bearings is disclosed. First, two manually operated displacement platforms are symmetrically fixed to the main body using screws, and the platforms are adjusted to the same height using knobs on both sides. Second, a synchronous linkage is installed on the sliders opposite the knobs of the two manually operated displacement platforms using screws, achieving synchronous movement of the two platforms. Finally, two connecting plates are fixed to the sliders of the two platforms with screws, and two laser displacement sensors are fixed to the inner sides of the connecting plates with screws, completing the installation of the detection device. This invention has a compact structure and is easy to operate. It can achieve synchronous or asynchronous adjustment of the laser displacement sensors, and utilizes the measurement principle of laser sensors to achieve non-contact measurement of rotating components. It has high practicality and engineering application value for longitudinal vibration measurement of magnetic thrust bearings in rotation.

[0008] A longitudinal vibration detection device for a magnetic thrust bearing includes a main body 7-1, a first manual displacement platform 7-2, a first connecting plate 7-3, a first laser displacement sensor 7-4, a synchronous linkage component 7-5, a second laser displacement sensor 7-6, a second connecting plate 7-7, and a second manual displacement platform 7-8.

[0009] The first manual displacement platform 7-2 and the second manual displacement platform 7-8 are symmetrically mounted on the main body 7-1 using fixing screws, and the first manual displacement platform 7-2 and the second manual displacement platform 7-8 are adjusted to the same height using knobs on both sides; the synchronous linkage component 7-5 is fixed to the slider on the opposite side of the knobs of the first manual displacement platform 7-2 and the second manual displacement platform 7-8 using fixing screws, so as to realize the synchronous movement of the first manual displacement platform 7-2 and the second manual displacement platform 7-8; the first connecting plate 7-3 and the second connecting plate 7-7 are fixed to the first manual displacement platform 7-2 and the second manual displacement platform 7-8 respectively using fixing bolts, and the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 are respectively mounted on the inner side of the first connecting plate 7-3 and the second connecting plate 7-7 using fixing bolts, so as to realize the synchronous adjustment of the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6.

[0010] A method for longitudinal vibration testing of magnetic thrust bearings is disclosed. This method utilizes the non-contact measurement advantage of laser displacement sensors. Laser displacement sensors are arranged on a test bench to simultaneously measure the longitudinal vibration displacement of the rotor and stator of the magnetic thrust bearing. After excitation of the excitation disk using an exciter, the time-domain displacement signals of the longitudinal vibration of the magnetic thrust bearing rotor and stator are acquired separately. After bandpass filtering, the effective values ​​of the time-domain displacement of the longitudinal vibration of the magnetic thrust bearing rotor and stator are obtained. Finally, the vibration level difference between the excitation input and output ends of the magnetic thrust bearing, i.e., the vibration level difference between the rotor and stator of the magnetic thrust bearing, is calculated. This is used as an evaluation index of the vibration reduction effect of the magnetic thrust bearing, reducing interference from external unstable factors and achieving rapid and accurate evaluation of the vibration reduction effect of the magnetic thrust bearing under rotating conditions.

[0011] The specific steps are as follows:

[0012] The first step is to build the test bench and arrange the longitudinal vibration detection device for the magnetic thrust bearing.

[0013] First, a test bench is erected. The drive motor base 15 is fixed on the cast iron platform 14, and the drive motor 1 is fixed on the drive motor base 15. The reducer base 16 is placed on the cast iron platform 14 along the T-slot, and the reducer 3 is installed on the reducer base 16. The position of the reducer base 16 is adjusted so that the drive motor 1 and the reducer 3 are connected by the pin coupling 2. The flange on one side of the tire coupling 4 is connected to the reducer 3 by a flat key. Next, the magnetic thrust bearing base 17 is placed on the cast iron platform 14 along the T-slot, and the magnetic thrust bearing 6 is installed on the magnetic thrust bearing base 17. After the main shaft 9 is limited by the magnetic thrust bearing 6, the position of the magnetic thrust bearing base 17 is adjusted so that the flange on one side of the main shaft 9 is fixedly connected to the flange on the other side of the tire coupling 4. At this time, the magnetic thrust bearing base 17 is fixed on the cast iron platform 14. Radial bearing 5 is installed on main shaft 9, and the end face of radial bearing 5 is axially connected to the end face of magnetic thrust bearing 6; sliding bearing 8 is installed on main shaft 9 and placed on sliding bearing base 19. After the two are connected, sliding bearing base 19 is fixed on cast iron platform 14; connecting sleeve 10 is fitted to main shaft 9 through spline; loading device base 20 is placed on cast iron platform 14 along T-slot, and loading disk 11 is fixed on loading device base 20. The position of loading device base 20 is adjusted so that angular contact ball bearing connection is made between connecting sleeve 10 and loading disk 11. At this time, loading device base 20 is fixed on cast iron platform 14; then, hydraulic cylinder 13 is installed on loading device base 20, and vibrator 12 is suspended on overhead crane and connected to loading disk 11 through vibration rod to apply excitation of vibrator 12 to shaft system;

[0014] Subsequently, the longitudinal vibration detection device 7 is installed on the longitudinal vibration detection device base 18, and the longitudinal vibration detection device base 18 is installed on the cast iron platform 14. By adjusting the position of the longitudinal vibration detection device base 18 and the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 in the longitudinal vibration detection device 7, the lasers of the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 are respectively perpendicularly struck on the end faces of the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6, thereby realizing the measurement of the longitudinal vibration of the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6.

[0015] The second step is to drive motor 1 to rotate, increase the thrust to the specified working condition, apply exciter 12 to excite, and obtain the longitudinal displacement data of rotor measuring point 6-4 and stator measuring point 6-3.

[0016] The main shaft 9 is driven to a specified speed by the drive motor 1, and the hydraulic cylinder 13 provides thrust to the shaft system, simulating the actual operating conditions of the magnetic thrust bearing 6. After the shaft system stabilizes, the exciter 12 applies longitudinal excitation to the loading disk 11. The first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 are used to detect the longitudinal vibration of the rotor 6-2 end face and the stator 6-1 end face, respectively. The longitudinal vibration displacement data of the rotor measuring point 6-4 and the stator measuring point 6-3 within a time interval t are collected and recorded at a frequency fs, and x is respectively. R x S ;where x R x S Both are sequences with N terms, x R (n), x S (n) represent x R x S The relationship between the nth term, the number of terms N, the sampling frequency fs, and the sampling time t is as follows:

[0017]

[0018] The sampling period is:

[0019]

[0020] Where T is the sampling period, f s The sampling frequency;

[0021] The third step is to filter the vibration displacement time-domain signal and calculate the effective values ​​of the rotor 6-2 and stator 6-1 displacement data after filtering.

[0022] First, considering the influence of zero-point drift during the laser displacement sensor test, and removing the DC component of the rotor and stator displacement data, the actual displacement vibration data of rotor 6-2 and stator 6-1 of magnetic thrust bearing 6 are as follows:

[0023]

[0024] Where, x Ra x Sa These represent the longitudinal vibration displacement signals of the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6 after removing the DC component, respectively.

[0025] Secondly, the filter parameters are designed, taking into account the analysis frequency band of the magnetic thrust bearing, and the lower cutoff frequency of the passband is chosen as f. L The upper passband cutoff frequency is f H Convert the lower and upper cutoff frequencies of the passband into angular frequencies:

[0026]

[0027] Where, ω L ω H These represent the lower cutoff angular frequency of the analog passband and the upper cutoff angular frequency of the analog passband, respectively.

[0028] To obtain an accurate cutoff frequency after bilinear transformation, pre-distortion is required in the analog domain. Therefore:

[0029]

[0030] Among them, Ω L Ω H These represent the lower cutoff frequency and the upper cutoff frequency of the simulated passband after pre-distortion, respectively.

[0031] Considering the balance between computational complexity in the steepness domain of the transition band during filtering, an M-order filter is chosen. Therefore, the low-pass transfer function is:

[0032]

[0033] The transformation formula for converting the low-pass transfer function to the band-pass transfer function is as follows:

[0034]

[0035] Where s is the Laplace variable and ω0 is the center frequency. B is the bandwidth. ;

[0036] Furthermore, a bilinear transformation is performed to convert the analog filter transfer function into a digital filter transfer function. The bilinear transformation formula is as follows:

[0037]

[0038] Where z is a complex frequency variable;

[0039] Substituting equations (7) and (8) into equation (6), we obtain the digital bandpass filter transfer function:

[0040]

[0041] Among them, a k b represents the denominator coefficients of the digital bandpass filter transfer function. k These are the numerator coefficients of the digital bandpass filter transfer function;

[0042] Then, the actual displacement vibration data of the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6 are subjected to bandpass filtering:

[0043]

[0044] Where, x Rp x Sp These represent the bandpass filtered longitudinal vibration displacement signals of the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6, respectively.

[0045] Further, the effective values ​​of the filtered data are obtained:

[0046]

[0047] Where, x Rrms x Srms These represent the effective values ​​of longitudinal vibration displacement after bandpass filtering of the rotor and stator of the magnetic thrust bearing, respectively.

[0048] Step 4: Calculate the vibration level difference between the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6;

[0049]

[0050] Where L represents the vibration level difference between the rotor and stator of the magnetic thrust bearing;

[0051] At this point, the calculation of the longitudinal vibration level drop of the magnetic thrust bearing is complete.

[0052] The beneficial effects of this invention are as follows: This invention proposes a longitudinal vibration detection device for magnetic thrust bearings. This device uses a laser displacement sensor to measure the longitudinal vibration of the stator and rotor of the magnetic thrust bearing under rotating conditions. It can effectively avoid electromagnetic interference and the influence of the acquisition module on the shaft system state, and more accurately acquire the true longitudinal vibration data of the magnetic thrust bearing. The introduction of a manual displacement platform and synchronous linkage not only enables synchronous adjustment of the laser displacement sensor position, but also enables the measurement of longitudinal vibration of the magnetic thrust bearing at different positions or even different thrust bearings, which has universality and ease of operation. At the same time, the longitudinal vibration detection method for magnetic thrust bearings proposed in this invention can calculate the vibration level drop at different frequency bands by bandpass filtering the time domain signal, and thus evaluate the vibration reduction effect of the magnetic thrust bearing at different frequency bands. In engineering applications, it has the characteristics of strong practicality, simple operation, and wide applicability. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of a longitudinal vibration detection device for magnetic thrust bearings.

[0054] Figure 2 This is a flowchart of a method for verifying the longitudinal vibration of a magnetic thrust bearing.

[0055] Figure 3 This is a schematic diagram of a test bench for longitudinal vibration testing of magnetic thrust bearings;

[0056] Figure 4 This is a schematic diagram of the distribution of measuring points on the magnetic thrust bearing;

[0057] Figure 5 In a specific embodiment, the longitudinal vibration displacement x of the rotor before filtering is... R [n] A dotted-line graph of index n;

[0058] Figure 6 In a specific embodiment, the stator longitudinal vibration displacement x before filtering is... S [n] A dotted-line graph of index n;

[0059] Figure 7 In a specific embodiment, the filtered longitudinal vibration displacement x of the rotor Rp [n] A dotted-line graph of index n;

[0060] Figure 8 In a specific embodiment, the filtered longitudinal vibration displacement x of the stator Sp [n] A dotted-line graph of index n;

[0061] Figure 1In the middle: 1-Drive motor, 2-Pin coupling, 3-Reducer, 4-Tire coupling, 5-Radial bearing, 6-Magnetic thrust bearing, 6-1 Stator, 6-2 Rotor, 6-3 Stator measuring point, 6-4 Rotor measuring point, 7-Longitudinal vibration detection device, 7-1-Main body, 7-2-First manual displacement platform, 7-3-First connecting plate, 7-4-First laser displacement sensor, 7-5-Synchronous linkage component, 7-6-Second laser displacement sensor, 7-7-Second connecting plate, 7-8-Second manual displacement platform, 8-Sliding bearing, 9-Main shaft, 10-Connecting sleeve, 11-Loading disk, 12-Vibrator, 13-Hydraulic cylinder, 14-Cast iron platform, 15-Drive motor base, 16-Reducer base, 17-Magnetic thrust bearing base, 18-Longitudinal vibration detection device base, 19-Sliding bearing base, 20-Loading device base. Detailed Implementation

[0062] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0063] Example

[0064] A magnetic thrust bearing with a rated thrust of 5t was selected for the design of a longitudinal vibration detection device and the verification of longitudinal vibration level drop.

[0065] Figure 1 This is a schematic diagram of a longitudinal vibration detection device for magnetic thrust bearings. The main unit 7-1 has a 75mm×75mm×10mm cube base. The transition section support measures 25mm×25mm×45mm, and the top support measures 45mm×45mm×310mm. Each of the two symmetrical planes of the top support has 20 M2 threaded holes. The sliders on the first manual displacement platform 7-2 and the second manual displacement platform 7-8 are connected to the guide rails by a rack and pinion mechanism, allowing for vertical movement with a stroke of 180mm via a knob. The first connecting plate 7-3 and the second connecting plate 7-7 measure 130mm×45mm×5mm. The synchronous linkage 7-5 is a U-shaped plate. The base plate measures 84mm×36mm×4mm, and the two side plates each measure 17mm×36mm. ×18mm, the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 are Keyence LK-H080 models, with a measurement range of 80mm±18mm and a repeatability of 0.1μm;

[0066] The installation steps for the magnetic thrust bearing longitudinal vibration detection device are as follows:

[0067] First, the first manual displacement platform 7-2 and the second manual displacement platform 7-8 are symmetrically mounted on the main body 7-1 using 16 M2×6 fixing screws, and the first manual displacement platform 7-2 and the second manual displacement platform 7-8 are adjusted to the same height using knobs on both sides. Second, the synchronous linkage 7-5 is fixed to the slider on the opposite side of the knobs of the first manual displacement platform 7-2 and the second manual displacement platform 7-8 using 8 M4×28 fixing screws, so as to realize the synchronous movement of the first manual displacement platform 7-2 and the second manual displacement platform 7-8. Finally, the first connecting plate 7-3 and the second connecting plate 7-7 are fixed to the first manual displacement platform 7-2 and the second manual displacement platform 7-8 respectively using 4 M4×12 fixing bolts, and the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 are installed on the inner side of the first connecting plate 7-3 and the second connecting plate 7-7 respectively using 2 M4×12 fixing bolts, so as to realize the synchronous adjustment of the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6.

[0068] The installation of a longitudinal vibration detection device for magnetic thrust bearings is now complete.

[0069] Figure 2 This is a flowchart of a method for verifying the longitudinal vibration of a magnetic thrust bearing. The specific steps of the calculation method are as follows:

[0070] The first step is to build the test bench and arrange the longitudinal vibration detection device for the magnetic thrust bearing.

[0071] Figure 3This is a schematic diagram of a test bench for longitudinal vibration testing of magnetic thrust bearings. First, the test bench frame is erected. The drive motor base 15 is fixed on the cast iron platform 14, and the drive motor 1 is fixed on the drive motor base 15. The reducer base 16 is placed on the cast iron platform 14 along the same T-slot, and the reducer 3 is installed on the reducer base 16. The position of the reducer base 16 is adjusted so that the drive motor 1 and the reducer 3 are connected via a pin coupling 2. The flange on one side of the tire coupling 4 is connected to the reducer 3 using a flat key. Next, the magnetic thrust bearing base 17 is placed on the cast iron platform 14 along the same T-slot, and the magnetic thrust bearing 6 is installed on the magnetic thrust bearing base 17. After the main shaft 9 is limited by the magnetic thrust bearing 6, the position of the magnetic thrust bearing base 17 is adjusted so that the flange on one side of the main shaft 9 is fixed to the flange on the other side of the tire coupling 4 with bolts. At this point, the magnetic thrust bearing base 17 is fixed to the cast iron platform 14. The upper and lower parts of the radial bearing 5 are then... The radial bearing 5 is mounted on the main shaft 9 with screws, and the end face of the radial bearing 5 is connected to the end face of the magnetic thrust bearing 6 axially with bolts. The sliding bearing 8 is mounted on the main shaft 9 and placed on the sliding bearing base 19. After the two are connected by fixing screws, the sliding bearing base 19 is fixed on the cast iron platform 14. The connecting sleeve 10 is engaged with the main shaft 9 through a spline. The loading device base 20 is placed on the cast iron platform 14 along the same T-slot, and the loading disk 11 is fixed on the loading device base 20. The position of the loading device base 20 is adjusted so that the angular contact ball bearing connects the connecting sleeve 10 and the loading disk 11. At this time, the loading device base 20 is fixed on the cast iron platform 14. Subsequently, the hydraulic cylinder 13 is mounted on the loading device base 20, and the vibrator 12 is suspended on the overhead crane and connected to the loading disk 11 through the vibration rod, so that vibration excitation can be applied to the shaft system. At this point, the test bench is completed.

[0072] Figure 4 This is a schematic diagram of the distribution of measuring points on the magnetic thrust bearing. After the test bench is built, the longitudinal vibration detection device 7 is installed on the longitudinal vibration detection device base 18, and the longitudinal vibration detection device base 18 is installed on the cast iron platform 14. By adjusting the position of the longitudinal vibration detection device base 18 and the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 in the longitudinal vibration detection device 7, the lasers of the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 are respectively perpendicularly struck on the end faces of the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6, thereby realizing the measurement of the longitudinal vibration of the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6. At this point, the arrangement of the longitudinal vibration detection device 7 is completed.

[0073] The second step is to drive motor 1 to rotate, increase the thrust to the specified working condition, apply exciter excitation, and obtain longitudinal displacement data of rotor measuring point 6-4 and stator measuring point 6-3.

[0074] The spindle 9 is driven by drive motor 1 to a speed of 6 rpm, and the hydraulic cylinder applies a thrust of 3t to simulate the actual operating conditions of the magnetic thrust bearing. After the shaft system stabilizes, longitudinal excitation is applied using exciter 12 and loading disk 11. The sampling frequency of the first laser displacement sensor 7-4 and the second laser displacement sensor 7-6 is set to 2kHz, the sampling time is 20s, and the number of data items collected is 40,000. The longitudinal vibration displacement data of rotor measuring point 6-4 and stator measuring point 6-3 are recorded as x. R x S , respectively Figure 5 , Figure 6 As shown;

[0075] The third step is to filter the vibration displacement time-domain signal and calculate the effective values ​​of the rotor 6-2 and stator 6-1 displacement data after filtering.

[0076] The original vibration displacement time-domain data is subjected to a fourth-order bandpass filter of 5Hz-500Hz, and the filtered data is substituted into equation (11) to obtain the effective value of the longitudinal vibration displacement x of the rotor after bandpass filtering. Rrms 1.30×10 -7 m, the effective value of longitudinal vibration displacement after stator bandpass filtering, x Srms It is 6.38×10 -8 m;

[0077] Step 4: Calculate the vibration level difference between the rotor 6-2 and stator 6-1 of the magnetic thrust bearing 6;

[0078] From formula (12), the vibration level difference L between the rotor and stator of the magnetic thrust bearing is 6.21 dB;

[0079] At this point, the calculation of the longitudinal vibration level drop of the magnetic thrust bearing is complete.

[0080] This novel magnetic thrust bearing longitudinal vibration detection device measures the longitudinal vibration of the stator and rotor of the magnetic thrust bearing under rotating conditions using a laser displacement sensor. It effectively avoids electromagnetic interference and the influence of the acquisition module on the shaft system state, and acquires more accurate true longitudinal vibration data of the magnetic thrust bearing. Furthermore, the introduction of a manual displacement platform and synchronous linkage not only enables synchronous adjustment of the laser displacement sensor position, but also allows for the measurement of longitudinal vibration of the magnetic thrust bearing at different positions or even different thrust bearings, making it universal and easy to operate.

[0081] This method can calculate the vibration level drop at different frequency bands by bandpass filtering the time domain signal collected by the laser displacement sensor, and thus evaluate the vibration reduction effect of the magnetic thrust bearing at different frequency bands. It has the characteristics of strong practicality, simple operation and wide applicability in engineering applications.

Claims

1. A longitudinal vibration detection device for magnetic thrust bearings, characterized in that, The longitudinal vibration detection device for the magnetic thrust bearing includes a main body (7-1), a first manual displacement platform (7-2), a first connecting plate (7-3), a first laser displacement sensor (7-4), a synchronous linkage component (7-5), a second laser displacement sensor (7-6), a second connecting plate (7-7), and a second manual displacement platform (7-8). The first manual displacement platform (7-2) and the second manual displacement platform (7-8) are symmetrically installed on the main body (7-1), and the first manual displacement platform (7-2) and the second manual displacement platform (7-8) are adjusted to the same height using the knobs on both sides; the synchronous linkage component (7-5) is fixed on the slider on the opposite side of the knobs of the first manual displacement platform (7-2) and the second manual displacement platform (7-8) to realize the synchronous movement of the first manual displacement platform (7-2) and the second manual displacement platform (7-8); the first connecting plate (7-3) and the second connecting plate (7-7) are respectively fixed on the first manual displacement platform (7-2) and the second manual displacement platform (7-8), and the first laser displacement sensor (7-4) and the second laser displacement sensor (7-6) are respectively installed on the inner side of the first connecting plate (7-3) and the second connecting plate (7-7) to realize the synchronous adjustment of the first laser displacement sensor (7-4) and the second laser displacement sensor (7-6).

2. A method for detecting longitudinal vibration of a magnetic thrust bearing, characterized in that, The specific steps are as follows: The first step is to build the test bench and arrange the longitudinal vibration detection device for the magnetic thrust bearing. The second step is to drive the motor (1) to rotate, increase the thrust to the specified working condition, apply the exciter (12) to excite, and obtain the longitudinal displacement data of the rotor measuring point (6-4) and the stator measuring point (6-3); Step 3: Filter the vibration displacement time domain signal and calculate the effective values ​​of the rotor (6-2) and stator (6-1) displacement data after filtering; Step 4: Calculate the vibration level difference between the rotor (6-2) and stator (6-1) of the magnetic thrust bearing (6).

3. The method for detecting longitudinal vibration of a magnetic thrust bearing according to claim 2, characterized in that, The specific implementation process of the first step is as follows: First, a test bench is set up. The drive motor base (15) is fixed on the cast iron platform (14), and the drive motor (1) is fixed on the drive motor base (15). The reducer base (16) is placed on the cast iron platform (14) along the T-slot, and the reducer (3) is installed on the reducer base (16). The position of the reducer base (16) is adjusted so that the drive motor (1) and the reducer (3) are connected by a pin coupling (2). The flange on one side of the tire coupling (4) Connect the magnetic thrust bearing base (17) to the reducer (3) via a flat key; then, place the magnetic thrust bearing base (17) along the T-slot on the cast iron platform (14), install the magnetic thrust bearing (6) on the magnetic thrust bearing base (17), and after the main shaft (9) is limited by the magnetic thrust bearing (6), adjust the position of the magnetic thrust bearing base (17) so that the flange on one side of the main shaft (9) is fixedly connected to the flange on the other side of the tire coupling (4). At this time, fix the magnetic thrust bearing base (17) on the cast iron platform (14); A radial bearing (5) is mounted on the main shaft (9), and the end face of the radial bearing (5) is axially connected to the end face of the magnetic thrust bearing (6); a sliding bearing (8) is mounted on the main shaft (9) and placed on the sliding bearing base (19). After the two are connected, the sliding bearing base (19) is fixed on the cast iron platform (14); the connecting sleeve (10) is fitted to the main shaft (9) through a spline; the loading device base (20) is placed on the cast iron platform (14) along the T-slot, and Fix the loading disk (11) on the loading device base (20), adjust the position of the loading device base (20) so that the connecting sleeve (10) and the loading disk (11) are connected by an angular contact ball bearing, and then fix the loading device base (20) on the cast iron platform (14); then, install the hydraulic cylinder (13) on the loading device base (20), and suspend the vibrator (12) on the crane, and connect it to the loading disk (11) through the vibrating rod to apply the excitation of the vibrator (12) to the shaft system; Subsequently, the longitudinal vibration detection device (7) is installed on the longitudinal vibration detection device base (18), and the longitudinal vibration detection device base (18) is installed on the cast iron platform (14). By adjusting the position of the longitudinal vibration detection device base (18) and the first laser displacement sensor (7-4) and the second laser displacement sensor (7-6) in the longitudinal vibration detection device (7), the lasers of the first laser displacement sensor (7-4) and the second laser displacement sensor (7-6) are respectively vertically struck on the end faces of the rotor (6-2) and stator (6-1) of the magnetic thrust bearing (6), thereby realizing the measurement of the longitudinal vibration of the rotor (6-2) and stator (6-1) of the magnetic thrust bearing (6).

4. The method for detecting longitudinal vibration of a magnetic thrust bearing according to claim 3, characterized in that, The specific implementation process of the second step is as follows: The main shaft (9) is driven by the drive motor (1) to reach the specified speed. The hydraulic cylinder (13) provides thrust to the shaft system to simulate the actual operating conditions of the magnetic thrust bearing (6). After the shaft system is stable, the exciter (12) is used to apply longitudinal exciter (12) excitation to the loading disk (11). The first laser displacement sensor (7-4) and the second laser displacement sensor (7-6) are used to detect the longitudinal vibration of the rotor (6-2) end face and the stator (6-1) end face, respectively. The longitudinal vibration displacement data of the rotor measuring point (6-4) and the stator measuring point (6-3) within time t are collected and recorded at a frequency fs, respectively. R x S ;where x R x S Both are sequences with N terms, x R (n), x S (n) represent x R x S The relationship between the nth term, the number of terms N, the sampling frequency fs, and the sampling time t is as follows: The sampling period is: Where T is the sampling period, f s The sampling frequency.

5. The method for detecting longitudinal vibration of a magnetic thrust bearing according to claim 4, characterized in that, The specific implementation process of the third step is as follows: First, considering the influence of zero-point drift during the laser displacement sensor test, and removing the DC component of the rotor and stator displacement data, the actual displacement vibration data of the rotor (6-2) and stator (6-1) of the magnetic thrust bearing (6) are as follows: Where, x Ra x Sa These represent the longitudinal vibration displacement signals of the rotor (6-2) and stator (6-1) of the magnetic thrust bearing (6) after removing the DC component, respectively. Secondly, the filter parameters are designed, taking into account the analysis frequency band of the magnetic thrust bearing, and the lower cutoff frequency of the passband is chosen as f. L The upper passband cutoff frequency is f H Convert the lower and upper cutoff frequencies of the passband into angular frequencies: Where, ω L ω H These represent the lower cutoff angular frequency of the analog passband and the upper cutoff angular frequency of the analog passband, respectively. To obtain an accurate cutoff frequency after bilinear transformation, pre-distortion is required in the analog domain. Therefore: Among them, Ω L Ω H These represent the lower cutoff frequency and the upper cutoff frequency of the simulated passband after pre-distortion, respectively. Considering the balance between computational complexity in the steepness domain of the transition band during filtering, an M-order filter is chosen. Therefore, the low-pass transfer function is: The transformation formula for converting the low-pass transfer function to the band-pass transfer function is as follows: Where s is the Laplace variable and ω0 is the center frequency. B is the bandwidth. ; Furthermore, a bilinear transformation is performed to convert the analog filter transfer function into a digital filter transfer function. The bilinear transformation formula is as follows: Where z is a complex frequency variable; Substituting equations (7) and (8) into equation (6), we obtain the digital bandpass filter transfer function: Among them, a k b represents the denominator coefficients of the digital bandpass filter transfer function. k These are the numerator coefficients of the digital bandpass filter transfer function; Then, the actual displacement vibration data of the rotor (6-2) and stator (6-1) of the magnetic thrust bearing (6) are subjected to bandpass filtering: Where, x Rp x Sp These represent the bandpass filtered longitudinal vibration displacement signals of the rotor (6-2) and stator (6-1) of the magnetic thrust bearing (6), respectively. Further, the effective values ​​of the filtered data are obtained: Where, x Rrms x Srms These represent the effective values ​​of longitudinal vibration displacement of the rotor and stator of the magnetic thrust bearing after bandpass filtering, respectively.

6. The method for detecting longitudinal vibration of a magnetic thrust bearing according to claim 5, characterized in that, The specific implementation process of the fourth step is as follows: Where L represents the vibration level difference between the rotor and stator of the magnetic thrust bearing.

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