Permanent magnet transmission shaft system and vibration and noise reduction performance evaluation method

Abstract

The invention belongs to the technical field of ship propulsion shafting, and discloses a permanent magnet transmission shafting and a vibration and noise reduction performance evaluation method, the method fully considers each part having great influence on the vibration and noise reduction performance of the shafting in the transverse direction, the vertical direction, the longitudinal direction and the circumferential direction, and arranges acceleration sensors on the corresponding parts; the vibration acceleration response is acquired through the wireless acquisition module, and the device has the advantages of simple operation, convenient measurement and the like. According to the evaluation method, the difference between the coordinate systems where the acceleration sensors on the shaft and the base are located when the shaft system operates is fully considered, and rapid, effective and accurate evaluation of vibration and noise reduction performance of the shaft system in all directions can be obtained by performing coordinate transformation on acceleration responses measured under different coordinate systems; important technical support is provided for initial structural design iteration, vibration and noise reduction performance testing and the like of the permanent magnet transmission shaft system, and the method has good practicability, operability and convenience in practical engineering application.

Description

Technical Field

[0001] The invention belongs to the technical field of ship propulsion shaft systems and relates to a permanent magnet transmission shaft system structure design and an effective evaluation method for its vibration reduction and noise reduction performance. Background Art

[0002] The ship shaft system is a basic component of the ship power plant. During the voyage of the ship, the exciting force exerted on the propeller is transmitted to the hull through the ship shaft system and causes vibration and noise at the tail, which affects the ride comfort and safety, and also aggravates the wear and fatigue damage of the transmission system components. Therefore, the research on the shaft system vibration reduction technology is of great significance to the control of ship vibration and noise and stable and reliable service. At present, the ship shaft system mostly adopts the mechanical contact transmission mode, the vibration is directly transmitted, and the vibration reduction and noise reduction effect tends to be a bottleneck; in contrast, the magnetic non-contact transmission is a way of supporting and transmitting by using the magnetic field generated by rare earth permanent magnet materials, which can complete the efficient transmission of power without physical contact, friction and wear, and isolation of vibration, and has broad application prospects and development potential; in addition, due to the complex structure and space limitations of the shaft system, there is currently a lack of effective means for the evaluation of the multi-directional vibration reduction and noise reduction performance of the permanent magnet transmission shaft system. Therefore, it is of great significance to propose a permanent magnet transmission shaft system structure design and an effective evaluation method for vibration reduction and noise reduction performance to guide the initial design iteration of the permanent magnet transmission shaft system.

[0003] In response to the design problem of transmission shaft vibration reduction structure, Shao Jiayao, Tang Changde, Zhao Yupeng and others proposed a shaft vibration reduction structure design installed on the outer package or bracket of the transmission shaft in the patent "Ship Shaft Vibration Reduction Structure" (CN201720704456.5) to improve the impact resistance and vibration reduction performance of the ship. However, the vibration reduction structure proposed in the article is complex and it is difficult to test its vibration reduction and noise reduction effect in the form of a simple test bench. In addition, no effective evaluation method for the vibration reduction and noise reduction performance of the transmission shaft is given, and it is impossible to directly make an effective evaluation of the performance of the proposed shaft vibration reduction structure. In order to effectively evaluate the vibration and noise reduction performance of the system, Jia Ruihao, Niu Junchuan and Guo Juncai conducted a dynamic modeling analysis on the vibration isolation performance of the multi-layer vibration isolation system of the internal combustion engine and its supporting equipment installed in the ship in the article "Modeling of Vibration Isolation System for Ship Diesel Engines and Evaluation of Vibration Isolation Effects". Based on the transmission force, the transmission force difference was defined, which can be used to evaluate the vibration isolation performance of the multi-support vibration isolation system in the theoretical calculation and design stages. However, the transmission force difference evaluation method proposed in the article is limited by the complex structure and limited space of the system. In actual application, there is a problem that the exciting force is difficult to measure. In addition, the research object focuses on the vibration isolation effect evaluation of the multi-layer vibration isolation system of the internal combustion engine installed in the ship, and cannot be directly applied to the vibration isolation performance evaluation of the transmission shaft system.

[0004] Therefore, a permanent magnet transmission shaft system structure design and an effective evaluation method for its vibration reduction and noise reduction performance that is convenient for bench testing are proposed, which is of great significance for guiding its initial structural design iteration and vibration reduction and isolation performance testing. Summary of the invention

[0005] In order to make up for the defects of the prior art, the present invention invents a permanent magnet transmission shaft system structure design and an effective evaluation method for its vibration reduction and noise reduction performance. Its purpose is to propose a permanent magnet transmission shaft system structure design that is easy to test on a bench, realize the flexible connection of the permanent magnet support between the ship propulsion shaft system and the hull, reduce the transmission of the shaft system to the hull vibration and the radiation noise of the ship's tail, and combine the proposed permanent magnet transmission shaft system bench structure characteristics to propose a shaft system-base vibration reduction and noise reduction performance evaluation method based on multi-point acceleration measurement, realize the permanent magnet transmission shaft system lateral, vertical, longitudinal and circumferential vibration reduction and noise reduction performance Rapid and effective evaluation, provide important technical support for the permanent magnet transmission shaft system structure design iteration, vibration reduction and noise reduction performance testing, etc. This method has good practicality, operability and convenience in actual engineering applications.

[0006] The technical solution of the present invention:

[0007] A permanent magnet transmission shaft system is fixed on a cast iron platform 13, and realizes multi-directional vibration reduction and noise reduction in the lateral and vertical, longitudinal and circumferential directions of the permanent magnet transmission shaft system through a permanent magnet radial bearing 11, a permanent magnet thrust bearing 10 and a permanent magnet coupling 7; wherein the driving end of the permanent magnet transmission shaft system adopts a motor 1 in combination with a reducer 2, and is fixed to the cast iron platform 13 through a motor base 19 and a reducer base 18 during installation, and between the motor 1 and the reducer 2 and between the reducer 2 and the torque sensor 4 The permanent magnet coupling 7 is connected through a mechanical coupling 3; the torque sensor 4 is used to measure the load torque size and fluctuation of the permanent magnet transmission shaft system, which is connected to the permanent magnet coupling 7 through an intermediate shaft 5 and fixed to the cast iron platform 13 through a torque sensor base 17; the permanent magnet coupling 7 is used to isolate the torsional vibration transmission caused by torque load fluctuation between the power source and the permanent magnet transmission shaft system, and the mounting interfaces at both ends of the permanent magnet coupling 7 are designed the same, and the two ends are respectively transferred to the mounting shaft 9 and the intermediate shaft 5 through an adapter plate 8; the mounting shaft 9 is a transmission shaft, and the permanent magnet coupling 7 is connected to the intermediate shaft 5 through an adapter plate 8; the mounting shaft 9 is a transmission shaft, and the permanent magnet coupling 7 is connected to the intermediate shaft 5 through an adapter plate 8; the permanent magnet coupling 7 is connected to the intermediate shaft 5 through an intermediate shaft 5 ... The structural design connects the permanent magnet coupling 7, the permanent magnet thrust bearing 10, the permanent magnet radial bearing 11, and the propeller counterweight 12 in series to form the main part of the permanent magnet transmission shaft system; the intermediate shaft 5 is the right side support of the permanent magnet coupling 7, and is fixed to the cast iron platform 13 through the sliding bearing seat 6 and the sliding bearing seat base 16 during installation; the permanent magnet thrust bearing 10 is used to bear the longitudinal propulsion reaction force of the permanent magnet transmission shaft system and weaken the transmission of the longitudinal vibration of the permanent magnet transmission shaft system caused by the external exciting force to the base. It is fixed to the cast iron platform 13 through the permanent magnetic thrust bearing base 15; the magnetic force generated by the magnets inside the permanent magnetic radial bearing 11 is used to offset the gravity of the propeller counterweight 12 and the installation shaft 9, and to weaken the lateral and vertical vibrations from the tail end of the shaft system. The permanent magnetic radial bearing 11 and the sliding bearings on the permanent magnetic thrust bearing 10 jointly provide two fulcrums of the permanent magnetic transmission shaft system, and their relative positions determine the center of mass distribution of the permanent magnetic transmission shaft system. During installation, the permanent magnetic radial bearing 11 is fixed to the cast iron platform 13 through the permanent magnetic radial bearing base 14.

[0008] A method for evaluating the vibration and noise reduction performance of a permanent magnet transmission shaft system, the steps are as follows:

[0009] The first step is to build a permanent magnet transmission shaft system test bench and adjust the alignment of the permanent magnet transmission shaft system parts;

[0010] First, the permanent magnetic radial bearing 11 and the permanent magnetic radial bearing base 14 are used as the positioning reference for assembly, and the installation shaft 9 is inserted therein; then the permanent magnetic thrust bearing 10 and the permanent magnetic thrust bearing base 15 are installed, the installation shaft 9 is inserted therein, and adjusted to the centered state; then, the propeller counterweight 12, the adapter plate 8, and the permanent magnetic coupling 7 are installed with the installation shaft 9 as the reference, the permanent magnetic coupling 7 is fixed by the sliding bearing seat 6 and the sliding bearing seat base 16, and the inner and outer rotors on both sides of the permanent magnetic coupling 7 are adjusted to the centered state; finally, the torque sensor 4, the reducer 2 and the motor 1 are connected through the mechanical coupling 3, and the relative positions of the torque sensor base 17, the reducer base 18 and the motor base 19 are adjusted so that the torque sensor 4, the reducer 2 and the motor 1 are centered with the shaft system;

[0011] Step 2: Arrange acceleration sensors at the permanent magnetic radial bearing 11, the permanent magnetic thrust bearing 10 and the permanent magnetic coupling 7

[0012] According to the permanent magnet transmission shaft system structure, firstly, acceleration sensors are arranged on the shaft section close to the permanent magnet radial bearing 11 and on the permanent magnet radial bearing base 14; then, acceleration sensors are arranged on the shaft section close to the permanent magnet thrust bearing 10 and on the permanent magnet thrust bearing base 15; finally, acceleration sensors are arranged on the circumferential side surfaces of the inner and outer rotors of the permanent magnet coupling 7;

[0013] The third step is to apply hammer excitation to the propeller counterweight to obtain the vibration acceleration response at various locations;

[0014] First, the motor 1 is turned on to make the permanent magnet transmission shaft system run stably at a certain speed n; then, the sampling frequency of the wireless acquisition module 20 is set to f; finally, hammer excitation is applied to the tail propeller counterweight 12, and the vibration response data of the acceleration sensor is collected; the lateral acceleration responses on the shaft section of the permanent magnet radial bearing 11 and the permanent magnet radial bearing base 14 are recorded as a and zx and a jx , vertical acceleration responses are a zy and a jy ; The longitudinal acceleration responses on the shaft section of the permanent magnetic thrust bearing 10 and the permanent magnetic thrust bearing base 15 are a zz and a jz ; The circumferential acceleration responses of the outer rotor and inner rotor of the permanent magnet coupling 7 are a wθ and a nθ ;

[0015] Step 4: coordinate transformation of the acceleration on the axis of the permanent magnetic radial bearing 11 is performed to calculate the lateral and vertical vibration level differences;

[0016] First, when calculating the lateral and vertical vibration level differences of the permanent magnetic radial bearing 11, since the acceleration sensor on the shaft section of the permanent magnetic radial bearing 11 and the acceleration sensor on the permanent magnetic radial bearing base 14 are located in different coordinate systems, coordinate transformation is required, and the calculation formula is as follows:

[0017] a zx '=a zx cosωt+a zy sinωt (1)

[0018] a zy '=-a zx sinωt+a zy cosωt (2)

[0019] Where, ω is the angular velocity of the permanent magnet transmission shaft system, and ω = 2πn, rad / s; n is the stable operating speed of the permanent magnet transmission shaft system, r / s; t is the relative recording time of the data, s; a zx ' is the coordinate transformation value of the lateral acceleration response on the shaft section of the permanent magnetic radial bearing 11 in the base coordinate system, m / s 2 ; a zy ' is the coordinate transformation value of the vertical acceleration response on the shaft section of the permanent magnetic radial bearing 11 in the base coordinate system, m / s 2 ;

[0020] Secondly, calculate the effective value of acceleration response a in the lateral and vertical directions on the shaft section of the permanent magnetic radial bearing 11 and in the lateral and vertical directions on the permanent magnetic radial bearing base 14 respectively. ezx 、a ezy 、a ejx and a ejy , and the calculation formula of the effective value of acceleration is as follows:

[0021]

[0022] In the formula, a e is the effective value of acceleration, m / s 2 ; a is the instantaneous acceleration value in discrete time domain measured at different measuring points, m / s 2 ; N is the number of sampling points; f is the sampling frequency, Hz; T is the sampling time, and T = N / f, s;

[0023] Then, the acceleration levels L in the lateral and vertical directions on the shaft section of the permanent magnetic radial bearing 11 and the lateral and vertical directions on the permanent magnetic radial bearing base 14 are calculated respectively. zx , L zy , L jx and L jy , and the acceleration level calculation formula is as follows:

[0024]

[0025] Where, L a is the acceleration level, dB; a0 is the acceleration reference value, take a0 = 10 -6 m / s 2 ;

[0026] Finally, the lateral vibration level drop L of the permanent magnetic radial bearing 11 is calculated x and vertical vibration level difference L y , and the vibration level difference calculation formula is as follows:

[0027] L=L m -L c (5)

[0028] Where, L is the vibration level difference, dB; L m is the vibration acceleration level at the input end of the permanent magnetic radial bearing 11, dB; L c is the vibration acceleration level at the output end of the permanent magnetic radial bearing base 14, dB;

[0029] Step 5: Calculate the longitudinal vibration level difference of the permanent magnetic thrust bearing and the circumferential vibration level difference of the permanent magnetic coupling;

[0030] When calculating the longitudinal vibration level difference of the permanent magnetic thrust bearing 10 and the circumferential vibration level difference of the permanent magnetic coupling 7, there is no need to consider coordinate transformation. The longitudinal vibration level difference is used for calculation. The calculation process is as follows:

[0031] First, the effective value a of the longitudinal acceleration on the shaft section of the permanent magnetic thrust bearing 10 and the permanent magnetic thrust bearing base 15 is calculated by formula (3): ezz and a ejz , the formula is as follows:

[0032]

[0033] Then, the longitudinal acceleration level L on the shaft section of the permanent magnetic thrust bearing 10 and the permanent magnetic thrust bearing base 15 is calculated by formula (4): zz and L jz , the formula is as follows:

[0034]

[0035] Finally, the longitudinal vibration level drop of the permanent magnetic thrust bearing 10 is calculated by formula (5), and the formula is as follows:

[0036] L z =L zz -L jz (10)

[0037] Similarly, the effective value of the circumferential acceleration of the outer rotor and inner rotor of the permanent magnet coupling 7 is calculated to be a ewθ and a enθ , acceleration level is L wθand L nθ , the vibration level difference is L θ ;

[0038] Step 6: Based on the calculation results, evaluate the vibration and noise reduction performance of the shaft system in all directions;

[0039] According to the calculation results of the fourth and fifth steps, the horizontal, vertical, longitudinal and circumferential vibration level differences of the proposed permanent magnet transmission shaft system are L x , L y , L z and L θ At this point, the evaluation of the shaft system's all-directional vibration and noise reduction performance has been completed.

[0040] Beneficial effects of the invention: The invention proposes a permanent magnet transmission shaft system structure design that is easy to bench test. By introducing magnetic non-contact transmission technology, it can provide important technical support for the research on vibration reduction and noise reduction technology of ship propulsion shaft systems, and has high practical application value. In addition, combined with the structural characteristics of the proposed permanent magnet transmission shaft system bench, a simple and easy-to-implement method for evaluating the multi-directional vibration reduction and noise reduction performance between the shaft system and the base based on multi-point acceleration measurement is proposed. This method fully considers the components that have a great influence on the lateral, vertical, longitudinal and circumferential vibration reduction and noise reduction performance of the shaft system, and arranges acceleration on the corresponding components. The velocity sensor dynamically collects the vibration acceleration response through the wireless acquisition module, and has the advantages of simple operation and easy measurement in actual engineering applications. Furthermore, the evaluation method fully considers the difference in coordinate systems between the acceleration sensors on the shaft and the base when the shaft system is running. By transforming the acceleration responses measured in different coordinate systems, a rapid, effective and accurate evaluation of the vibration reduction and noise reduction performance of the shaft system in all directions can be obtained, which provides important technical support for the iteration of permanent magnet transmission shaft system structure design, vibration reduction and noise reduction performance testing, etc., and has good practicality, operability and convenience in actual engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the structure of a permanent magnet transmission shaft system gantry.

[0042] Figure 2 It is a flow chart of the vibration and noise reduction performance evaluation method of a permanent magnet transmission shaft system;

[0043] Figure 3 It is a schematic diagram of the arrangement of acceleration measurement points on the shaft system.

[0044] Figure 4 This is a schematic diagram of the axis-base lateral and vertical acceleration coordinate transformation; in the figure, ω-axis system stable running angular velocity, a zx - Transverse acceleration measurement on the axis, a zy -Vertical acceleration measurement value on the axis, a jx - Transverse acceleration measurement on the base, ajy -Vertical acceleration measurements on the base;

[0045] Figure 5 is the original measurement data of each acceleration response under hammer excitation; where: (a) is the lateral acceleration response a on the permanent magnetic radial bearing shaft zx ; (b) is the lateral acceleration response of the permanent magnetic radial bearing base a jx ; (c) is the vertical acceleration response a of the permanent magnetic radial bearing shaft zy ; (d) is the vertical acceleration response of the permanent magnetic radial bearing base a jy ; (e) is the longitudinal acceleration response a of the permanent magnetic thrust bearing shaft zz ; (f) Longitudinal acceleration response of permanent magnetic thrust bearing base a jz ; (g) is the circumferential acceleration response of the outer rotor of the permanent magnet coupling a wθ ; (h) is the circumferential acceleration response of the rotor in the permanent magnet coupling a nθ ;

[0046] Figure 6 is the acceleration coordinate transformation value on the permanent magnetic radial bearing shaft; where: (1) is the lateral acceleration response coordinate transformation value a on the permanent magnetic radial bearing shaft zx ', (2) is the vertical acceleration response coordinate transformation value a on the permanent magnetic radial bearing axis zy ';

[0047] In the figure: 1-motor, 2-reducer, 3-mechanical coupling, 4-torque sensor, 5-intermediate shaft, 6-sliding bearing seat, 7-permanent magnetic coupling, 8-adapter, 9-mounting shaft, 10-permanent magnetic thrust bearing, 11-permanent magnetic radial bearing, 12-propeller counterweight, 13-cast iron platform, 14-permanent magnetic radial bearing base, 15-permanent magnetic thrust bearing base, 16-sliding bearing seat base, 17-torque sensor base, 18-reducer base, 19-motor base; 20-wireless acquisition module, 21-acceleration input measuring point on permanent magnetic radial bearing shaft, 22-acceleration output measuring point on permanent magnetic radial bearing base, 23-acceleration input measuring point on permanent magnetic thrust bearing shaft, 24-acceleration output measuring point on permanent magnetic thrust bearing base, 25-acceleration input measuring point of outer rotor of permanent magnetic coupling, 26-acceleration output measuring point of inner rotor of permanent magnetic coupling. DETAILED DESCRIPTION

[0048] The implementation examples of the present invention are further described below in conjunction with the accompanying drawings and technical solutions.

[0049] This implementation case uses a permanent magnet transmission shaft system with a rated power of 45kW and a rated speed of 150rpm to conduct a quantitative evaluation of the anisotropic vibration and noise reduction performance.

[0050] Figure 1It is a schematic diagram of the structure of a permanent magnet transmission shaft system test bench, wherein: 1-motor, 2-reducer, 3-mechanical coupling, 4-torque sensor, 5-intermediate shaft, 6-sliding bearing seat, 7-permanent magnet coupling, 8-adapter plate, 9-mounting shaft, 10-permanent magnet thrust bearing, 11-permanent magnet radial bearing, 12-propeller counterweight, 13-cast iron platform, 14-permanent magnet radial bearing base, 15-permanent magnet thrust bearing base, 16-sliding bearing base, 17-torque sensor base, 18-reducer base, 19-motor base.

[0051] Figure 2 This is a flow chart of the vibration and noise reduction performance evaluation method of a permanent magnet transmission shaft system. The specific steps are as follows:

[0052] Step 1: Build a permanent magnet transmission shaft test bench and adjust the alignment of the shaft components

[0053] First, the permanent magnetic radial bearing 11 and the permanent magnetic radial bearing base 14 are used as the positioning reference for assembly, and the installation shaft 9 is inserted therein; secondly, the permanent magnetic thrust bearing 10 and the permanent magnetic thrust bearing base 15 are installed, the installation shaft 9 is inserted therein, and they are adjusted to the centered state; then, the propeller counterweight 12, the adapter plate 8, the permanent magnetic coupling 7 and other components are installed based on the installation shaft 9, the permanent magnetic coupling 7 is fixed by the sliding bearing seat 6 and the sliding bearing seat base 16, and the inner and outer rotors on both sides of the permanent magnetic coupling 7 are adjusted to the centered state; finally, the shaft system drive part is installed, the torque sensor 4, the reducer 2 and the motor 1 are connected through the mechanical coupling 3, and the torque sensor 4, the reducer 2 and the motor 1 are aligned with the shaft system by adjusting the relative positions of the torque sensor base 17, the reducer base 18 and the motor base 19.

[0054] Step 2: Arrange acceleration sensors at permanent magnetic radial bearings, permanent magnetic thrust bearings and permanent magnetic couplings

[0055] Figure 3 This is a schematic diagram of the acceleration measurement point arrangement on the shaft system, in which: 20-wireless acquisition module, 21-acceleration input measurement point on the permanent magnetic radial bearing shaft, 22-acceleration output measurement point on the permanent magnetic radial bearing base, 23-acceleration input measurement point on the permanent magnetic thrust bearing shaft, 24-acceleration output measurement point on the permanent magnetic thrust bearing base, 25-acceleration input measurement point on the outer rotor of the permanent magnetic coupling, 26-acceleration output measurement point on the inner rotor of the permanent magnetic coupling.

[0056] Step 3: Apply hammer excitation to the propeller counterweight to obtain the vibration acceleration response at various locations

[0057] Set the axis system stable running speed n = 10rpm = 0.167r / s, sampling frequency f = 25600Hz, Figure 5 It is the original measurement data of each acceleration response under hammer excitation.

[0058] Step 4: Transform the coordinates of the acceleration on the permanent magnetic radial bearing axis and calculate the horizontal and vertical vibration level differences.

[0059] First, a zx and a zy Substituting into equations (1) and (2), we can obtain the coordinate transformation value a of the lateral and vertical acceleration on the permanent magnetic radial bearing axis: zx ' and a zy 'like Figure 6 As shown;

[0060] Secondly, a zx '、a jx 、a zy ' and a jy Substituting them into formula (3) respectively, we can get the effective value of acceleration a ezx =1.151m / s 2 、a ejx =0.440m / s 2 、a ezy =1.569m / s 2 and a ejy =0.391m / s 2 ;

[0061] Then, a ezx 、a ejx 、a ezy and a ejy Substituting them into formula (4) respectively, we can get the acceleration level L zx =121.223dB, L jx =112.869dB, L zy =123.912dB and L jy =111.836dB;

[0062] Finally, the lateral vibration level drop L of the permanent magnetic radial bearing is calculated by formula (5): x =L zx -L jx =8.35dB, vertical level difference L y =L zy -L jy =12.08dB.

[0063] Step 5: Calculate the longitudinal vibration level difference of the permanent magnetic thrust bearing and the circumferential vibration level difference of the permanent magnetic coupling

[0064] First, the effective value a of the longitudinal acceleration of the permanent magnetic thrust bearing 10 can be calculated by equations (6) and (7): ezz =3.355m / s 2 、a ejz =0.877m / s2 Then, the acceleration level L can be calculated by equations (8) and (9): zz =130.513dB, L jz =118.862dB; Finally, the longitudinal vibration level difference L of the permanent magnetic thrust bearing 10 can be calculated by formula (10): z =L zz -L jz =11.65dB.

[0065] Similarly, the effective value of the circumferential acceleration of the permanent magnet coupling 7 is calculated as a ewθ =2.1303m / s 2 and a enθ =0.365m / s 2 , the acceleration level is L wθ =126.569dB and L nθ =111.246dB, the level difference is L θ =L wθ -L nθ =15.32dB.

[0066] Step 6: Based on the calculation results, evaluate the vibration and noise reduction performance of the shaft system in all directions

[0067] According to the calculation results of the fourth and fifth steps, it can be known that the horizontal, vertical, longitudinal and circumferential vibration level differences of the proposed permanent magnet transmission shaft system are L x =8.35dB, L y =12.08dB, L z =11.65dB and L θ =15.32dB. So far, the quantitative evaluation of the vibration and noise reduction performance of the shaft system in all directions has been completed.

[0068] This method fully considers the difference in coordinate systems between the acceleration sensors on the shaft and on the base when the shaft system is running. By transforming the acceleration responses measured in different coordinate systems, a rapid and effective evaluation of the vibration and noise reduction performance of the shaft system in all directions can be obtained, providing important technical support for the iteration of permanent magnet transmission shaft system structure design, vibration and noise reduction performance testing, etc. In actual engineering applications, it has the advantages of simple operation, strong adaptability, and short evaluation time. It is a calculation method with practical engineering application value.

Claims

1. A permanent magnet transmission shaft system, characterized in that: The permanent magnet transmission shaft system is fixed on a cast iron platform (13), and realizes multi-directional vibration reduction and noise reduction of the permanent magnet transmission shaft system in the lateral and vertical, longitudinal and circumferential directions respectively through a permanent magnet radial bearing (11), a permanent magnet thrust bearing (10) and a permanent magnet coupling (7); wherein the driving end of the permanent magnet transmission shaft system adopts the form of a motor (1) and a reducer (2), and is fixed to the cast iron platform (13) through a motor base (19) and a reducer base (18) during installation, and a mechanical connection is formed between the motor (1) and the reducer (2) and between the reducer (2) and the torque sensor (4). The permanent magnet coupling (7) is connected to the permanent magnet transmission shaft system through a mechanical coupling (3); the torque sensor (4) is used to measure the load torque size and fluctuation of the permanent magnet transmission shaft system, and is connected to the permanent magnet coupling (7) through an intermediate shaft (5), and is fixed to the cast iron platform (13) through a torque sensor base (17); the permanent magnet coupling (7) is used to isolate the torsional vibration transmission caused by torque load fluctuation between the power source and the permanent magnet transmission shaft system, and the mounting interfaces at both ends of the permanent magnet coupling (7) are designed in the same way, and the two ends are respectively transferred to the mounting shaft (9) and the intermediate shaft (5) through a transfer plate (8); the mounting shaft (9) is a transmission shaft, and is connected to the permanent magnet transmission shaft system through a torque sensor base (17). The structure design connects the permanent magnet coupling (7), the permanent magnet thrust bearing (10), the permanent magnet radial bearing (11), and the propeller counterweight (12) in series to form the main part of the permanent magnet transmission shaft system; the intermediate shaft (5) is the right side support of the permanent magnet coupling (7), and is fixed to the cast iron platform (13) through the sliding bearing seat (6) and the sliding bearing seat base (16) during installation; the permanent magnet thrust bearing (10) is used to bear the longitudinal propulsion reaction force of the permanent magnet transmission shaft system and weaken the transmission of the longitudinal vibration of the permanent magnet transmission shaft system caused by the external exciting force to the base. ) is fixed to the cast iron platform (13) through a permanent magnetic thrust bearing base (15); the magnetic force generated by the magnets inside the permanent magnetic radial bearing (11) is used to offset the gravity of the propeller counterweight (12) and the installation shaft (9), and to weaken the lateral and vertical vibrations from the tail end of the shaft system. The sliding bearings on the permanent magnetic radial bearing (11) and the permanent magnetic thrust bearing (10) jointly provide two fulcrums of the permanent magnetic transmission shaft system, and their relative positions determine the center of mass distribution of the permanent magnetic transmission shaft system. During installation, the permanent magnetic radial bearing (11) is fixed to the cast iron platform (13) through the permanent magnetic radial bearing base (14).

2. A method for evaluating the vibration and noise reduction performance of a permanent magnet transmission shaft system according to claim 1, characterized in that: Here are the steps: The first step is to build a permanent magnet transmission shaft system test bench and adjust the alignment of the permanent magnet transmission shaft system parts; The second step is to arrange acceleration sensors at the permanent magnetic radial bearing (11), the permanent magnetic thrust bearing (10) and the permanent magnetic coupling (7); The third step is to apply hammer excitation to the propeller counterweight to obtain the vibration acceleration response at various locations; Step 4: coordinate transformation of the acceleration on the axis of the permanent magnetic radial bearing (11) to calculate the lateral and vertical vibration level differences; Step 5: Calculate the longitudinal vibration level difference of the permanent magnetic thrust bearing and the circumferential vibration level difference of the permanent magnetic coupling; Step 6: Based on the calculation results, evaluate the vibration and noise reduction performance of the shaft system in all directions; According to the calculation results of the fourth and fifth steps, the horizontal, vertical, longitudinal and circumferential vibration level differences of the proposed permanent magnet transmission shaft system are L x , L y , L z and L θ At this point, the evaluation of the shaft system's all-directional vibration and noise reduction performance has been completed.

3. The vibration reduction and noise reduction performance evaluation method according to claim 2, characterized in that: The specific implementation process of the first step is as follows: First, the permanent magnetic radial bearing (11) and the permanent magnetic radial bearing base (14) are used as the positioning reference for assembly, and the installation shaft (9) is inserted therein; then the permanent magnetic thrust bearing (10) and the permanent magnetic thrust bearing base (15) are installed, the installation shaft (9) is inserted therein, and adjusted to a centered state; then, the propeller counterweight (12), the adapter plate (8), and the permanent magnetic coupling (7) are installed with the installation shaft (9) as the reference, the permanent magnetic coupling (7) is fixed by the sliding bearing seat (6) and the sliding bearing seat base (16), and the inner and outer rotors on both sides of the permanent magnetic coupling (7) are adjusted to a centered state; finally, the torque sensor (4), the reducer (2) and the motor (1) are connected by the mechanical coupling (3), and the relative positions of the torque sensor base (17), the reducer base (18) and the motor base (19) are adjusted so that the torque sensor (4), the reducer (2) and the motor (1) are centered with the shaft system.

4. The vibration reduction and noise reduction performance evaluation method according to claim 2, characterized in that: The specific implementation process of the second step is as follows: According to the permanent magnet transmission shaft system structure, firstly, acceleration sensors are arranged on the shaft section close to the permanent magnet radial bearing (11) and on the permanent magnet radial bearing base (14); then, acceleration sensors are arranged on the shaft section close to the permanent magnet thrust bearing (10) and on the permanent magnet thrust bearing base (15); finally, acceleration sensors are arranged on the circumferential side surfaces of the inner and outer rotors of the permanent magnet coupling (7).

5. The vibration reduction and noise reduction performance evaluation method according to claim 2, characterized in that: The specific implementation process of the third step is as follows: First, the motor (1) is turned on to make the permanent magnet transmission shaft system run stably at a certain speed n; then, the sampling frequency of the wireless acquisition module 20 is set to f; finally, hammer excitation is applied to the tail propeller counterweight (12), and the vibration response data of the acceleration sensor is collected; the lateral acceleration responses on the shaft section of the permanent magnet radial bearing (11) and on the permanent magnet radial bearing base (14) are recorded as a and b respectively. zx and a jx , vertical acceleration responses are a zy and a jy The longitudinal acceleration responses on the shaft section of the permanent magnetic thrust bearing (10) and the permanent magnetic thrust bearing base (15) are respectively a zz and a jz ; The circumferential acceleration responses of the outer rotor and inner rotor of the permanent magnet coupling (7) are a wθ and a nθ .

6. The vibration reduction and noise reduction performance evaluation method according to claim 2, characterized in that: The specific implementation process of the fourth step is as follows: First, when calculating the lateral and vertical vibration level differences of the permanent magnetic radial bearing (11), since the acceleration sensor on the shaft section of the permanent magnetic radial bearing (11) and the acceleration sensor on the permanent magnetic radial bearing base (14) are located in different coordinate systems, coordinate transformation is required, and the calculation formula is as follows: a zx '=a zx cosωt+a zy sinωt (1) a zy '=-a zx sinωt+a zy cosωt (2) Where, ω is the angular velocity of the permanent magnet transmission shaft system, and ω = 2πn, rad / s; n is the stable operating speed of the permanent magnet transmission shaft system, r / s; t is the relative recording time of the data, s; a zx ' is the coordinate transformation value of the lateral acceleration response on the shaft section of the permanent magnetic radial bearing (11) in the base coordinate system, m / s 2 ; a zy ' is the coordinate transformation value of the vertical acceleration response on the shaft section of the permanent magnetic radial bearing (11) in the base coordinate system, m / s 2 ; Secondly, the effective value of the acceleration response a in the lateral and vertical directions on the shaft section of the permanent magnetic radial bearing (11) and in the lateral and vertical directions on the permanent magnetic radial bearing base (14) is calculated respectively. ezx 、a ezy 、a ejx and a ejy , and the calculation formula of the effective value of acceleration is as follows: In the formula, a e is the effective value of acceleration, m / s 2 ; a is the instantaneous acceleration value in discrete time domain measured at different measuring points, m / s 2 ; N is the number of sampling points; f is the sampling frequency, Hz; T is the sampling time, and T = N / f, s; Then, the acceleration levels L in the lateral and vertical directions on the shaft section of the permanent magnetic radial bearing (11) and the lateral and vertical directions on the permanent magnetic radial bearing base (14) are calculated respectively. zx , L zy , L jx and L jy , and the acceleration level calculation formula is as follows: Where, L a is the acceleration level, dB; a0 is the acceleration reference value, take a0=10 -6 m / s 2 ; Finally, the lateral vibration level drop L of the permanent magnetic radial bearing (11) is calculated x and vertical vibration level difference L y , and the vibration level drop calculation formula is as follows: L=L m -L c (5) Where, L is the vibration level difference, dB; L m is the vibration acceleration level at the input end of the permanent magnetic radial bearing (11) on the shaft, dB; L c is the vibration acceleration level at the output end of the permanent magnetic radial bearing base (14), dB.

7. The vibration reduction and noise reduction performance evaluation method according to claim 2, characterized in that: The specific implementation process of the fifth step is as follows: When calculating the longitudinal vibration level difference of the permanent magnetic thrust bearing (10) and the circumferential vibration level difference of the permanent magnetic coupling (7), it is not necessary to consider coordinate transformation, and the longitudinal vibration level difference is used for calculation. The calculation process is as follows: First, the effective value a of the longitudinal acceleration on the shaft section of the permanent magnetic thrust bearing (10) and the permanent magnetic thrust bearing base (15) is calculated by formula (3): ezz and a ejz , the formula is as follows: Then, the longitudinal acceleration level L on the shaft section of the permanent magnetic thrust bearing (10) and the permanent magnetic thrust bearing base (15) is calculated by formula (4): zz and L jz , the formula is as follows: Finally, the longitudinal vibration level drop of the permanent magnetic thrust bearing (10) is calculated by formula (5), and the formula is as follows: L z =L zz -L jz (10) Similarly, the effective value of the circumferential acceleration of the outer rotor and inner rotor of the permanent magnet coupling (7) is calculated to be a ewθ and a enθ , acceleration level is L wθ and L nθ , the vibration level difference is L θ .

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