A design method for an axial passive magnetic bearing with dual damping

Abstract

The invention discloses a design method of an axial passive magnetic bearing with dual damping effect. The axial passive magnetic bearing with dual damping effect comprises a stator, a rotor, an eddy current damping conductor arranged on the stator, an eddy current damping permanent magnet arranged on the rotor, and a magnetic fluid arranged between the stator and the rotor. The design method comprises: determining the numerical range of the eddy current damping force based on the set numerical range of the equivalent damping coefficient and the eddy current loss damping force of the magnetohydrodynamic vibration absorption; determining the thickness of the eddy current damping conductor according to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet and the thickness of the eddy current damping conductor, the numerical range of the eddy current damping force, and the size design requirements of the eddy current damping permanent magnet; and designing the structure of the axial passive magnetic bearing with dual damping effect according to the thickness of the eddy current damping conductor. The quantitative design of the axial passive magnetic bearing with dual damping effect is realized, and the design accuracy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of transmission magnetic bearings, and in particular to a design method for an axial passive magnetic bearing with double damping effects. Background Art

[0002] Existing magnetic bearings can be divided into active magnetic bearings and passive magnetic bearings according to whether the magnetic force is controllable. Active magnetic bearings can actively control the bearing stiffness and damping effect by controlling the size and direction of the current in the coil winding. They have the functions of active vibration control and active vibration suppression, but they need to be installed with high-precision and high-quality displacement sensors, controllers and power amplifiers. The system is complex, the cost is high, and the reliability is low. Passive magnetic bearings do not need to be used with components such as sensors and controllers. They have the advantages of simple structure, low cost, low power consumption, and high system reliability. They can meet the requirements of contactless suspension support of rotating motion machinery. However, most of the current patent documents only propose the structure of passive magnetic bearings, and lack corresponding analysis and design models. Summary of the invention

[0003] In order to overcome the problems existing in the related art, the present invention provides a design method of an axial passive magnetic bearing with dual damping effect.

[0004] According to a first aspect of the present invention, a design method for an axial passive magnetic bearing with dual damping effect is provided, wherein the axial passive magnetic bearing with dual damping effect comprises a stator, a rotor, an eddy current damping conductor arranged on the stator, an eddy current damping permanent magnet arranged on the rotor, and a magnetic fluid arranged between the stator and the rotor, and the design method comprises:

[0005] Determine the numerical range of the eddy current damping force based on the set numerical range of the equivalent damping coefficient and the magnetohydrodynamic vibration absorption eddy current loss damping force;

[0006] Determining the thickness of the eddy current damping conductor according to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet and the thickness of the eddy current damping conductor, the value range of the eddy current damping force and the size design requirements of the eddy current damping permanent magnet;

[0007] The structure of the axial passive magnetic bearing with dual damping effect is designed according to the thickness of the eddy current damping conductor.

[0008] In some embodiments, the method for determining the set value range of the equivalent damping coefficient includes:

[0009] Determine the axial resonance speed through modal analysis;

[0010] The set value range of the equivalent damping coefficient is determined based on the design requirements of the equivalent damping coefficient, the axial resonant speed, the rotor weight, and the value range of the logarithmic decay rate.

[0011] In some embodiments, the method for determining the magnetohydrodynamic vibration absorption eddy current loss damping force includes:

[0012] Determine the magnetohydrodynamic vibration absorption damping coefficient and magnetohydrodynamic vibration absorption stiffness coefficient;

[0013] The magnetohydrodynamic vibration absorption eddy current loss damping force is determined based on the magnetohydrodynamic vibration absorption damping coefficient, the magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorber damping dynamics model.

[0014] In some embodiments, the determining of the magnetohydrodynamic vibration absorption damping coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient comprises:

[0015] Determine the target stiffness coefficient;

[0016] Determining the magnetohydrodynamic vibration absorption stiffness coefficient based on the target stiffness coefficient and the corresponding relationship between the eddy current equivalent stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient;

[0017] The magnetohydrodynamic vibration absorption damping coefficient is determined based on the relationship between the magnetohydrodynamic vibration absorption damping coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient.

[0018] In some embodiments, determining the target stiffness coefficient comprises:

[0019] Determining a first design parameter of the axial passive magnetic bearing according to the mechanical performance requirements of the axial passive magnetic bearing;

[0020] Based on the first design parameter, a target stiffness coefficient of the axial passive magnetic bearing is obtained.

[0021] In some embodiments, obtaining a target stiffness coefficient of the axial passive magnetic bearing based on the first design parameter includes:

[0022] A target stiffness coefficient of the axial passive magnetic bearing is calculated based on the first design parameter, the rotor weight and the safety factor.

[0023] In some embodiments,

[0024] The multiple structural dimensions include the inner diameter and the outer diameter of the eddy current damping permanent magnet, the relationship between the eddy current damping force and the multiple structural dimensions of the eddy current damping permanent magnet and the thickness of the eddy current damping conductor is a functional relationship between the eddy current damping force and the multiple structural dimensions of the eddy current damping permanent magnet and the thickness of the eddy current damping conductor, and the inner diameter of the eddy current damping permanent magnet is a set value;

[0025] Determining the thickness of the eddy current damping conductor according to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet and the thickness of the eddy current damping conductor, the value range of the eddy current damping force and the size design requirements of the eddy current damping permanent magnet includes:

[0026] The functional relationship is to obtain the first-order derivative of the variable of the thickness of the eddy current damping conductor and make it equal to 0, so as to obtain the corresponding relationship between the inner diameter and the outer diameter of the eddy current damping permanent magnet;

[0027] Based on the set value of the inner diameter of the eddy current damping permanent magnet and the corresponding relationship between the inner diameter and the outer diameter of the eddy current damping permanent magnet, the outer diameter value of the eddy current damping permanent magnet is obtained;

[0028] Determining a thickness range of an eddy current damping conductor based on the numerical range of the eddy current damping force, the inner diameter value and the outer diameter value of the eddy current damping permanent magnet, and the functional relationship;

[0029] Based on the thickness range of the eddy current damping conductor, the thickness of the eddy current damping conductor is determined.

[0030] In some embodiments, the design method further includes:

[0031] Determine the second design parameter of the axial passive magnetic bearing according to the structure and magnetization property requirements and magnetization parameters of the permanent magnet of the axial passive magnetic bearing;

[0032] Based on the second design parameter, the bearing stiffness of the axial passive magnetic bearing is obtained;

[0033] The number of permanent magnet layers of the axial passive magnetic bearing is determined according to the target stiffness and the bearing stiffness of the axial passive magnetic bearing.

[0034] In some embodiments, the structure of the axial passive magnetic bearing is designed according to the thickness of the eddy current damping conductor, including:

[0035] The structure of the axial passive magnetic bearing is designed according to the thickness of the eddy current damping conductor and the number of permanent magnet layers.

[0036] According to a second aspect of the present invention, an axial passive magnetic bearing with dual damping effect is provided. The axial passive magnetic bearing with dual damping effect is designed using the design method described in any one of the above embodiments.

[0037] The beneficial effects of the present invention are:

[0038] In the design method of the axial passive magnetic bearing with dual damping effect provided by the present invention, according to the principle of dynamics, the numerical range of eddy current damping force is obtained, on this basis, with the design parameters and design margin of the axial passive magnetic bearing with dual damping effect as constraints, the magnetic bearing is designed by example, according to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet and the thickness of the eddy current damping conductor, the numerical range of the eddy current damping force and the size design requirements of the eddy current damping permanent magnet, the thickness of the eddy current damping conductor between the stator and the rotor is determined, and the quantitative design of the permanent magnet axial passive magnetic bearing with dual damping effect is realized, the design accuracy is greatly improved, and the safety of the use of the axial passive magnetic bearing is effectively guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use 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 work.

[0040] Figure 1 It is a schematic cross-sectional view of an axial passive magnetic bearing with double damping effect according to an exemplary embodiment.

[0041] Figure 2 The figure is a flow chart of a design method of an axial passive magnetic bearing with dual damping effect according to an exemplary embodiment.

[0042] In the figure: 1. stator; 2. rotor; 3. eddy current damping conductor; 4. magnetic fluid; 5. permanent magnet layer; 6. eddy current damping permanent magnet. DETAILED DESCRIPTION

[0043] The technical scheme in the embodiment of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present invention.

[0044] Reference to an "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0045] With the rapid development of modern science and technology, the performance requirements for workbenches in high-end manufacturing and precision measurement are increasing. Non-contact high-precision workbenches have shown great application potential in many key fields such as defense industry, aerospace, and high-end equipment manufacturing due to their excellent stability and positioning accuracy. Most traditional non-contact high-precision workbenches use air as a medium to achieve the suspension of the stage, which has the advantages of active vibration suppression and high control accuracy. However, its large size, high cost of clean air source, and demanding operating environment have seriously restricted its promotion and application. Magnetic bearing technology has the advantages of simple structure, low processing and manufacturing precision requirements, low vibration and noise, and strong environmental adaptability. It is a new way to achieve non-contact suspension support for high-precision workbenches.

[0046] In magnetic bearing technology, there are two types: active magnetic bearings and passive magnetic bearings. Active magnetic bearings achieve active control of bearing stiffness and damping by controlling the magnitude and direction of the current in the coil. This control method enables active magnetic bearings to have excellent active vibration control and active vibration suppression functions. However, active magnetic bearing systems require the installation of auxiliary equipment such as high-precision displacement sensors, high-quality controllers and power amplifiers, which not only increases the cost of the system, but also increases the complexity of the system and reduces the reliability of the system.

[0047] In contrast, passive magnetic bearings do not require auxiliary equipment such as sensors and controllers, and have significant advantages such as simple structure, low cost, low power consumption, and high system reliability. They can meet the requirements of contactless suspension support for high-precision workbenches. Passive magnetic bearings convert the energy of the moving part into eddy current loss through the bearing damper, thereby rapidly attenuating the axial oscillation of the moving part and improving the stability and reliability of the system. However, most existing passive magnetic bearing systems only stay at the level of structural design, lacking in-depth construction and design of magnetic bearing analysis models. Most of the current patent literature only proposes the structure of passive magnetic bearings and lacks corresponding analysis and design models, which limits the application and development of passive magnetic bearings in a wider range of fields.

[0048] In order to solve the problems existing in the related art, an embodiment of the present invention provides a design method for an axial passive magnetic bearing with dual damping effect. First, the numerical range of the eddy current damping force is determined according to the set numerical range of the equivalent damping coefficient and the magnetohydrodynamic vibration absorption eddy current loss damping force. On this basis, the design parameters and design margin of the axial passive magnetic bearing with dual damping effect are constrained to perform an example design of the magnetic bearing. According to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet and the thickness of the eddy current damping conductor, the numerical range of the eddy current damping force and the size design requirements of the eddy current damping permanent magnet, the thickness of the eddy current damping conductor between the stator and the rotor is determined, and the quantitative design of the axial passive magnetic bearing with dual damping effect is realized, which greatly improves the design accuracy and effectively ensures the safety of the use of the axial passive magnetic bearing.

[0049] The technical scheme in the embodiment of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present invention.

[0050] like Figure 1 and Figure 2 As shown, this embodiment provides a design method for an axial passive magnetic bearing with dual damping effect, wherein, referring to Figure 1 The axial passive magnetic bearing with dual damping effect comprises a stator 1, a rotor 2, an eddy current damping conductor 3 arranged on the stator 1, an eddy current damping permanent magnet 6 arranged on the rotor 2, and a magnetic fluid 4 arranged between the stator 1 and the rotor 2. The eddy current damping permanent magnet 6 is used to provide a bias magnetic field for the eddy current damping conductor 3 to generate eddy currents, and the eddy current damping permanent magnet 6 and the magnetic fluid 4 together provide dual damping effect for the axial passive magnetic bearing.

[0051] The design method specifically includes the following steps:

[0052] Step S110. Determine the numerical range of the eddy current damping force based on the set numerical range of the equivalent damping coefficient and the magnetohydrodynamic vibration absorption eddy current loss damping force.

[0053] According to the principle of dynamics, the dynamic model of the magnetic suspension measurement platform system is established, and the calculation model of the eddy current damping of the magnetic bearing is built through the principle of virtual displacement, and the calculation formula of the eddy current damping force of the bearing is obtained. On this basis, the design parameters and design margin of the axial passive magnetic bearing with dual damping effect are constrained, and an example design of the magnetic bearing is carried out, and a design method of the axial passive magnetic bearing with dual damping effect is obtained, which can be used for the rapid and accurate design of the axial passive magnetic bearing with dual damping effect.

[0054] For example, the eddy current damping force of the system is calculated using the virtual displacement principle, assuming that the equivalent damping coefficient of the moving part of the magnetic suspension measurement platform is , then this part of energy is expressed as:

[0055]

[0056] in, It is mechanical energy. It should be noted that the sum of the eddy current loss consumed by the moving part of the magnetic suspension measurement platform and the magnetohydrodynamic vibration absorption loss is the mechanical energy of vibration. is the maximum displacement caused by axial vibration, is the speed generated by axial vibration, is the period of axial vibration, is the angular frequency of vibration.

[0057] It is assumed that the relationship between the displacement caused by the axial vibration of the moving part of the magnetic suspension measurement platform and the time t is:

[0058]

[0059] Then the velocity generated by the axial vibration of the moving part of the magnetic suspension measurement platform is:

[0060]

[0061] According to the above formula, the equivalent damping coefficient of the moving part of the magnetic suspension measurement platform can be obtained: for:

[0062]

[0063] in, is the eddy current damping force, is the magnetohydrodynamic vibration absorption eddy current loss damping force.

[0064] In this way, the numerical range of the eddy current damping force can be determined according to the set numerical range of the equivalent damping coefficient and the magnetohydrodynamic vibration absorption eddy current loss damping force.

[0065] Step S120. Determine the thickness of the eddy current damping conductor according to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet, the thickness of the eddy current damping conductor, the numerical range of the eddy current damping force, and the size design requirements of the eddy current damping permanent magnet.

[0066] The thickness of the eddy current damping conductor 3 directly affects the magnitude of the eddy current damping force. The appropriate thickness of the eddy current damping conductor 3 can ensure that the eddy current is evenly distributed in the conductor, avoid local overheating and energy loss, and improve the damping efficiency. In the case of high-speed rotation of the rotor 2 or dynamic load changes, the appropriate thickness of the eddy current damping conductor 3 can ensure that the eddy current damping force responds quickly, effectively suppresses vibration and shaking, improves the dynamic performance of the system, and can also reduce the heat generated by the eddy current, reduce the thermal load of the system, and extend the service life of the equipment.

[0067] Step S130. Designing a structure of an axial passive magnetic bearing with dual damping effect according to the thickness of the eddy current damping conductor.

[0068] According to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet 6, the numerical range of the eddy current damping force and the size design requirements of the eddy current damping permanent magnet 6, the thickness of the eddy current damping conductor 3 between the stator 1 and the rotor 2 is determined, and the quantitative design of the axial passive magnetic bearing with dual damping effect is realized, which greatly improves the design accuracy and effectively ensures the safety of the use of the axial passive magnetic bearing.

[0069] In one embodiment, if Figure 1 As shown, the method for determining the setting value range of the equivalent damping coefficient includes:

[0070] Step S111. Determine the axial resonance speed through modal analysis.

[0071] For example, the function of the eddy current damping permanent magnet 6 is to suppress the axial vibration caused by the rigid mode or load disturbance, so before designing the axial passive magnetic bearing, it is necessary to first perform a modal analysis to obtain the axial vibration frequency and then the axial resonant speed. The modal analysis can be implemented in various ways such as software simulation, and this embodiment does not limit this.

[0072] Step S112: Determine a set value range of the equivalent damping coefficient based on the design requirements of the equivalent damping coefficient, the axial resonance speed, the rotor weight, and the value range of the logarithmic decay rate.

[0073] The axial resonance speed obtained by analyzing step S111 is: , then the required equivalent damping coefficient satisfies the following relationship:

[0074]

[0075] in, is the equivalent damping coefficient; is the logarithmic attenuation rate required by the damping system, which is generally required to be between 0.7 and 1; is the weight of the rotor.

[0076] The axial resonance speed is , logarithmic decay rate , rotor weight are all known numbers, so the setting value range of the equivalent damping coefficient can be determined based on the above relationship. Among them, the logarithmic attenuation rate You can select according to actual needs, for example, you can choose 0.7, 0.8, 0.9, 1, etc.

[0077] In one embodiment, if Figure 1 As shown, the method for determining the eddy current loss damping force of the magnetohydrodynamic vibration absorption includes:

[0078] The magnetohydrodynamic vibration absorption damping coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient are determined, and based on the magnetohydrodynamic vibration absorption damping coefficient, the magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorber damping dynamics model, the magnetohydrodynamic vibration absorption eddy current loss damping force is determined.

[0079] According to the principle of dynamics, the damping dynamics model of the magnetohydrodynamic vibration absorber for the magnetic suspension measurement platform is established. The specific formula is as follows:

[0080]

[0081] in, is the ratio of the system mass borne by the magnetohydrodynamic vibration absorber, is the magnetohydrodynamic vibration absorption damping coefficient, is the magnetohydrodynamic vibration absorption stiffness coefficient, is the displacement caused by axial vibration, is the rotor weight, is the maximum axial load, is the acceleration due to gravity, For displacement About Time The second-order derivative of For displacement About Time The first derivative of .

[0082] The above dynamic model can be used to determine the magnetohydrodynamic vibration absorption eddy current loss damping force .

[0083] In one embodiment, determining the magnetohydrodynamic vibration absorption damping coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient includes:

[0084] Determine the target stiffness coefficient, determine the magnetohydrodynamic vibration absorption stiffness coefficient based on the target stiffness coefficient and the corresponding relationship between the eddy current equivalent stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient, and determine the magnetohydrodynamic vibration absorption damping coefficient based on the relationship between the magnetohydrodynamic vibration absorption damping coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient.

[0085] For example, the target stiffness coefficient is set to , eddy current equivalent stiffness coefficient and magnetohydrodynamic vibration absorption stiffness coefficient The corresponding relationship is:

[0086]

[0087] in, is the ratio of the system mass borne by the magnetohydrodynamic vibration absorber, is the system damping ratio.

[0088] According to the design requirements, the ratio of the system mass borne by the magnetohydrodynamic vibration absorber In the range of 0.1~0.3, its value can be determined according to actual needs, for example, it can be 0.1, 0.2, 0.3, etc. In the range of system damping ratio Z=0~0.125, a suitable value can be selected in this range according to actual needs, such as 0.1, 0.12, 0.125, etc. In this way, the eddy current equivalent stiffness coefficient can be determined and magnetohydrodynamic vibration absorption stiffness coefficient The relationship is:

[0089]

[0090] The ratio of the mass of the system borne by the magnetohydrodynamic vibration absorber can be determined And determine the system damping ratio Calculated.

[0091] Target stiffness coefficient And the eddy current equivalent stiffness coefficient and magnetohydrodynamic vibration absorption stiffness coefficient The corresponding relationship is:

[0092]

[0093] Therefore, according to the target stiffness coefficient And the eddy current equivalent stiffness coefficient and magnetohydrodynamic vibration absorption stiffness coefficient The corresponding relationship between the magnetohydrodynamic vibration absorption stiffness coefficient can be obtained Then according to the magnetohydrodynamic vibration damping coefficient and magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient , determine the magnetohydrodynamic vibration damping coefficient , where the magnetohydrodynamic vibration damping coefficient is and magnetohydrodynamic vibration absorption stiffness coefficient The relationship satisfies the following formula:

[0094]

[0095] In one embodiment, determining the target stiffness coefficient includes:

[0096] According to the mechanical performance requirements of the axial passive magnetic bearing, the first design parameter of the axial passive magnetic bearing is determined. Among them, the axial passive magnetic bearing has different requirements for mechanical performance due to different factors such as the location, purpose, and use environment. Therefore, when designing the axial passive magnetic bearing, its requirements for mechanical performance (such as axial load and operating stability) can be determined first, and then the value of the first design parameter (such as maximum axial load and maximum allowable axial displacement) can be determined according to the mechanical performance requirements. The numerical determination standard of the first design parameter can be set according to actual conditions and is not limited here. For example, for the maximum axial load force, 1.5-2.0 times the commonly used axial load of the axial passive magnetic bearing in the actual working environment can be set as its maximum axial load force. For the maximum allowable axial displacement, for example, the displacement critical value of the unbalanced rotor 2 and the maximum allowable displacement fluctuation value of the rotating part of the equipment connected to the rotor 2 can be comprehensively considered, and 0.7-0.8 times the minimum value of the two can be taken.

[0097] Based on the first design parameter, the target stiffness coefficient of the axial passive magnetic bearing is obtained. Stiffness refers to the elastic property of the bearing, which can reflect the ability of the bearing to resist deformation. The greater the stiffness, the smaller the deformation of the bearing when it is under load. Generally, the bearing is used to achieve the movement between the component connected to the stator 1 and the component connected to the rotor 2. Therefore, the higher the bearing stiffness, the less likely the movement between the two parts will be disturbed by the outside world, so that the normal operation of the mechanical equipment can be better guaranteed. Based on the first design parameter, the target stiffness of the axial passive magnetic bearing can be obtained, and the target stiffness can ensure that the axial passive magnetic bearing can meet its mechanical performance requirements and have good operating stability. The target stiffness can be derived or characterized according to the operational relationship between it and the first design parameter, or it can also be simulated using relevant software to output the target stiffness value based on the first design parameter.

[0098] In one embodiment, obtaining a target stiffness coefficient of the axial passive magnetic bearing based on the first design parameter includes: calculating the target stiffness coefficient of the axial passive magnetic bearing based on the first design parameter, rotor weight and safety factor.

[0099] Among them, the first design parameter includes the maximum axial load force is The rotor weight is , the safety factor is For example, since the magnetic suspension measurement platform is placed vertically, the gravity of the moving part is in the same direction as the axial load force, and the bearing capacity required by the axial spherical passive magnetic bearing is the superposition of gravity and axial load force. In addition, in order to ensure reliable axial suspension, the maximum axial bearing capacity should have a certain safety factor based on these forces. Assuming that the weight of the rotor of the moving part of the magnetic suspension measurement platform is , the maximum axial load is , the maximum permissible axial displacement is , then the target stiffness coefficient required is ,in:

[0100]

[0101] in, is the safety factor, which is generally between 2 and 3, such as 2, 2.5, 3, etc.; is the maximum axial load force; is the dead weight of the rotor; is the maximum allowable axial displacement; g is the acceleration of gravity, g=9.8m / s 2 .

[0102] In one embodiment, the multiple structural dimensions include the inner diameter and outer diameter of the eddy current damping permanent magnet 6, the relationship between the eddy current damping force and the multiple structural dimensions of the eddy current damping permanent magnet 6 and the thickness of the eddy current damping conductor 3 is a functional relationship between the eddy current damping force and the multiple structural dimensions of the eddy current damping permanent magnet 6 and the thickness of the eddy current damping conductor 3, and the inner diameter of the eddy current damping permanent magnet 6 is a set value.

[0103] Exemplarily, the magnetic field energy in the air gap at the eddy current damping permanent magnet 6 is first calculated. The eddy current damping force is the inverse of the energy in the axial displacement. The magnetic field energy at the air gap of the eddy current damping permanent magnet 6 is:

[0104]

[0105] in, is the magnetic field energy in the air gap at the eddy current damping permanent magnet; is the inner diameter of the eddy current damping permanent magnet; is the outer diameter of the eddy current damping permanent magnet; is the air gap thickness of the air gap at the eddy current damping permanent magnet; is the thickness of the eddy current damping conductor, is the magnetic field strength of the eddy current damping main circuit, ; is the leakage magnetic field strength of the eddy current damping permanent magnet, ; is the relative magnetic permeability; is the vacuum permeability; is the amount of axial displacement of this energy.

[0106] Eddy current damping force The functional relationship between the multiple structural dimensions of the eddy current damping permanent magnet 6 and the thickness of the eddy current damping conductor is:

[0107]

[0108] According to the eddy current damping force The thickness of the eddy current damping conductor 3 is determined based on the relationship between the multiple structural dimensions of the eddy current damping permanent magnet 6 and the thickness of the eddy current damping conductor 3, the numerical range of the eddy current damping force, and the size design requirements of the eddy current damping permanent magnet 6, including:

[0109] Step S121. The function relationship is used to calculate the first-order derivative of the variable of the thickness of the eddy current damping conductor and make it equal to 0, so as to obtain the corresponding relationship between the inner diameter and the outer diameter of the eddy current damping permanent magnet.

[0110] Eddy current damping force There is a certain relationship between the thickness of the eddy current damping conductor and the damping force first increases and then decreases as the thickness of the eddy current damping conductor increases. The maximum optimum thickness can be obtained by solving the differential equation to obtain the optimum thickness of the eddy current damping conductor:

[0111]

[0112] The thickness of the eddy current damping conductor can be calculated by the above functional relationship. The first-order derivative of this variable is calculated and made equal to 0, and the inner diameter of the eddy current damping permanent magnet 6 is obtained. and outer diameter The corresponding relationship.

[0113] Step S122: Based on the set value of the inner diameter of the eddy current damping permanent magnet and the corresponding relationship between the inner diameter and the outer diameter of the eddy current damping permanent magnet, obtain the outer diameter value of the eddy current damping permanent magnet.

[0114] Since the inner diameter of the eddy current damping permanent magnet 6 is determined in step S121 and outer diameter In this way, the outer diameter value of the eddy current damping permanent magnet 6 can be determined according to the set value of the inner diameter of the eddy current damping permanent magnet 6.

[0115] Step S123: Determine the thickness range of the eddy current damping conductor based on the numerical range of the eddy current damping force, the inner diameter value and the outer diameter value of the eddy current damping permanent magnet, and the functional relationship.

[0116] According to the eddy current damping force The numerical range of the inner diameter of the eddy current damping permanent magnet 6 and outer diameter And the functional relationship, the thickness range of the eddy current damping conductor 3 can be determined.

[0117] Step S124: Determine the thickness of the eddy current damping conductor based on the thickness range of the eddy current damping conductor.

[0118] Any thickness can be selected within the thickness range of the eddy current damping conductor 3 as the thickness of the eddy current damping conductor 3 , for example, a middle value within the thickness range can be selected as the thickness of the eddy current damping conductor 3 .

[0119] In one embodiment, the design method further includes:

[0120] Step S210: Determine the second design parameters of the axial passive magnetic bearing according to the structure and magnetization property requirements and magnetization parameters of the permanent magnet of the axial passive magnetic bearing.

[0121] The space used for bearing installation and operation in mechanical equipment is often limited, so the value of the second design parameter of the axial passive magnetic bearing (such as the relevant structural dimensions of the permanent magnet layer 5) can be determined first. In one example, the second design parameter may include the radius, radial thickness, and thickness of the bearing air gap of the permanent magnet in the permanent magnet layer 5. The value of the determined second design parameter can make the size of the magnetic bearing less than or equal to its spatial size, so that the permanent magnet layer 5 can meet the spatial limitations of the axial passive magnetic bearing. The specific value of the second design parameter can be set according to actual conditions. For example, when determining the radial thickness of the permanent magnet, the radial thickness of the permanent magnet of the existing specifications can be preferentially selected to facilitate subsequent bearing processing and manufacturing.

[0122] Step S220. Based on the second design parameter, obtain the bearing stiffness of the axial passive magnetic bearing.

[0123] As mentioned above, the permanent magnets on the stator 1 and the rotor 2 of the axial passive magnetic bearing repel each other and thus provide load capacity for the magnetic bearing. Therefore, the bearing stiffness of each permanent magnet layer 5 can be determined to ensure that the load capacity provided by the permanent magnet layer 5 can meet the needs of the axial passive magnetic bearing. After determining the value of the second design parameter, the bearing stiffness of each permanent magnet layer 5 in the axial passive magnetic bearing can be obtained based on the second design parameter, and the sum of the bearing stiffness of each permanent magnet layer 5 is the stiffness that the permanent magnet layer 5 in the axial passive magnetic bearing can provide. The method for determining the bearing stiffness of the permanent magnet layer 5 can refer to the target stiffness of the aforementioned axial passive magnetic bearing, and can be obtained by means of an operational relationship with the second design parameter (described in detail later) or software simulation.

[0124] Step S230: Determine the number of permanent magnet layers of the axial passive magnetic bearing according to the target stiffness and the bearing stiffness of the axial passive magnetic bearing.

[0125] When determining the number of permanent magnet layers, a larger number of layers can be appropriately selected so that the sum of the bearing stiffness of each permanent magnet layer 5 is greater than the target stiffness of the axial passive magnetic bearing, ensuring that the stiffness provided by the permanent magnet layer 5 can always meet the target stiffness requirements.

[0126] The number of permanent magnet layers N can be determined by the following formula:

[0127]

[0128] In the formula, is the target stiffness of the axial passive magnetic bearing, is the bearing stiffness of the single-layer permanent magnet layer 5.

[0129] In this design method, based on the requirements of multiple aspects of the axial passive magnetic bearing, its target stiffness and the bearing stiffness of each permanent magnet layer 5 are determined respectively, and then the number of permanent magnet layers 5 is determined. According to the determined number of permanent magnet layers, the structure of the axial passive magnetic bearing can be designed more accurately, and the quantitative design of the axial passive magnetic bearing is realized, which greatly improves the design accuracy and effectively ensures the safety of the axial passive magnetic bearing.

[0130] For example, according to Coulomb's law of magnetism, the magnetic charge between any two points is established and The formula for the force between them is:

[0131]

[0132] in: For any two points of magnetic charge and The forces between is the vacuum permeability, =4π× H / m; is the relative magnetic permeability of the magnetic fluid; r is the magnetic charge and The spatial distance between them; r is the magnetic charge and The magnetic charge is used to represent the distance vector between the two.

[0133] Assuming that the magnetic charge is evenly distributed on the upper and lower spherical surfaces of the permanent magnet of the spherical axial passive magnetic bearing, the magnetic charge density on the upper spherical surface is + , the magnetic charge density on the lower spherical surface is - . From the magnetostatics theory, we can get:

[0134]

[0135]

[0136] in, is the magnetic charge density on the spherical surface, is the magnetic pole magnetization intensity vector, is the unit vector in the normal direction of the end surface of the permanent magnet ring of the spherical axial passive magnetic bearing, is the magnetization intensity, is the magnetic field strength, is the residual magnetization of the permanent magnet.

[0137] Since the normal direction of the end face of the permanent magnet ring of the spherical axial passive magnetic bearing is the same as the magnetization direction, we have:

[0138]

[0139] in, is the residual magnetization of the permanent magnet.

[0140] Assuming that the axial air gap between the end faces of the permanent magnet ring of the spherical axial passive magnetic bearing is δ, the upper and lower spherical surfaces of the permanent magnet ring of the spherical passive magnetic bearing interact with each other, and the permanent magnet axial repulsion force generated is , the integral unit of the axial permanent magnetic repulsion is:

[0141]

[0142] in, df z is the integral of the axial permanent magnetic repulsion of the spherical passive magnetic bearing; δ is the axial air gap between the upper and lower end surfaces of the permanent magnet ring of the spherical axial passive magnetic bearing; z is the axial position change between the upper and lower spherical surfaces of the spherical axial passive magnetic bearing; ; is the magnetic charge density on the lower spherical surface; θ is the magnetic charge at any two points on the upper and lower end surfaces of the permanent magnet ring of the spherical axial passive magnetic bearing and The spatial angle between is the integral of the spherical surface area on the permanent magnet ring of the spherical passive magnetic bearing; is the integral of the spherical surface area under the permanent magnet ring of the spherical passive magnetic bearing.

[0143] Therefore, the integral of the spherical surface area on the permanent magnet ring of the spherical passive magnetic bearing is The integral of the spherical surface area under the permanent magnet ring of the spherical passive magnetic bearing They are:

[0144]

[0145]

[0146] in, is the radius of the spherical surface on the permanent magnet ring of the spherical passive magnetic bearing, is the radius of the spherical surface under the permanent magnet ring of the spherical passive magnetic bearing, is the angle corresponding to the single-layer magnetic ring on the spherical passive magnetic bearing permanent magnet, It is the angle corresponding to the single-layer magnetic ring on the spherical surface under the permanent magnet of the spherical passive magnetic bearing.

[0147] From the above formula we can get:

[0148]

[0149] The axial repulsion generated by the single-layer permanent magnet of the spherical axial passive magnetic bearing can be obtained by performing area integration on the upper and lower spherical magnetic charge distribution surfaces of the permanent magnet ring of the passive magnetic bearing. for:

[0150]

[0151] Therefore, when there is Total axial repulsion generated by the spherical axial permanent magnet for:

[0152]

[0153] The target stiffness coefficient of the axial passive magnetic bearing is :

[0154]

[0155] From the above content, it can be seen that assuming the weight of the moving part of the magnetic levitation measurement platform is , the maximum axial load is , the maximum permissible axial displacement is , then the required stiffness is:

[0156]

[0157] in, is the safety factor, which is generally between 2 and 3; is the maximum axial load force; is the dead weight of the rotor; is the maximum allowable axial displacement; g is the acceleration of gravity, g=9.8m / s 2 .

[0158] Therefore, the number of spherical axial permanent magnet layers can be obtained for:

[0159]

[0160] In one embodiment, the structure of the axial passive magnetic bearing is designed according to the thickness of the eddy current damping conductor 3, including: designing the structure of the axial passive magnetic bearing according to the thickness of the eddy current damping conductor 3 and the number of permanent magnet layers. In this way, the structure of the axial passive magnetic bearing designed according to the thickness of the eddy current damping conductor 3 and the number of permanent magnet layers obtains an axial passive magnetic bearing with dual damping effect, which can adapt to different working environments and load requirements. By adjusting the thickness of the eddy current damping conductor 3 and the number of permanent magnet layers, the performance of the magnetic bearing can be accurately controlled, thereby meeting various complex application requirements and enhancing the suspension force and stability of the magnetic bearing.

[0161] It can be understood that the values ​​of the parameters in the above design method can refer to the structural values ​​of the existing passive magnetic bearings, and on this basis, the above design method can be used for calculation to obtain appropriate size results (target thickness of the eddy current damping conductor 3 and the number of permanent magnet layers) to meet the requirements of design accuracy and safety of use.

[0162] like Figure 1 As shown, this embodiment provides an axial passive magnetic bearing with dual damping effect, which can be designed by the design method in any of the above embodiments. In the design process, the numerical range of the eddy current damping force is first determined according to the set numerical range of the equivalent damping coefficient and the magnetohydrodynamic vibration absorption eddy current loss damping force. On this basis, the magnetic bearing is designed by example with the design parameters and design margin of the axial passive magnetic bearing with dual damping effect as constraints. According to the relationship between the eddy current damping force and the multiple structural dimensions of the eddy current damping permanent magnet 6, the numerical range of the eddy current damping force and the size design requirements of the eddy current damping permanent magnet 6, the thickness of the eddy current damping conductor 3 between the rotors is determined, and the quantitative design of the axial passive magnetic bearing with dual damping effect is realized, which greatly improves the design accuracy and effectively ensures the safety of the use of the axial passive magnetic bearing.

[0163] The contents described above may be implemented individually or in combination in various ways, and these variations are all within the protection scope of the present invention.

[0164] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements.

[0165] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for an axial passive magnetic bearing with dual damping effect, the axial passive magnetic bearing with dual damping effect comprising a stator (1), a rotor (2), an eddy current damping conductor (3) arranged on the stator (1), an eddy current damping permanent magnet (6) arranged on the rotor (2), and a magnetic fluid (4) arranged between the stator (1) and the rotor (2), characterized in that: The design method comprises: Determine the numerical range of the eddy current damping force based on the set numerical range of the equivalent damping coefficient and the magnetohydrodynamic vibration absorption eddy current loss damping force; Determining the thickness of the eddy current damping conductor (3) according to the relationship between the eddy current damping force and multiple structural dimensions of the eddy current damping permanent magnet (6) and the thickness of the eddy current damping conductor (3), the value range of the eddy current damping force and the size design requirements of the eddy current damping permanent magnet (6); Designing the structure of the axial passive magnetic bearing with dual damping effect according to the thickness of the eddy current damping conductor (3); The plurality of structural dimensions include an inner diameter and an outer diameter of the eddy current damping permanent magnet (6); the relationship between the eddy current damping force and the plurality of structural dimensions of the eddy current damping permanent magnet (6) and the thickness of the eddy current damping conductor (3) is a functional relationship between the eddy current damping force and the plurality of structural dimensions of the eddy current damping permanent magnet (6) and the thickness of the eddy current damping conductor (3); and the inner diameter of the eddy current damping permanent magnet (6) is a set value; Determining the thickness of the eddy current damping conductor (3) according to the relationship between the eddy current damping force and a plurality of structural dimensions of the eddy current damping permanent magnet (6) and the thickness of the eddy current damping conductor (3), the numerical range of the eddy current damping force and the dimensional design requirements of the eddy current damping permanent magnet (6), comprises: The magnetic field energy in the air gap at the eddy current damping permanent magnet (6) is calculated. The eddy current damping force is the inverse of the energy in the axial displacement. The magnetic field energy at the air gap of the magnetic pole of the eddy current damping permanent magnet (6) is: in, is the magnetic field energy in the air gap at the eddy current damping permanent magnet; is the inner diameter of the eddy current damping permanent magnet; is the outer diameter of the eddy current damping permanent magnet; is the air gap thickness of the air gap at the eddy current damping permanent magnet; is the thickness of the eddy current damping conductor, is the magnetic field strength of the eddy current damping main circuit, ; is the leakage magnetic field strength of the eddy current damping permanent magnet, ; is the relative magnetic permeability; is the vacuum permeability; is the axial displacement of the energy; is the residual magnetization of the permanent magnet; Determining Eddy Current Damping Force The functional relationship between the multiple structural dimensions of the eddy current damping permanent magnet (6) and the thickness of the eddy current damping conductor is: The functional relationship is used to obtain the first-order derivative of the variable of the thickness of the eddy current damping conductor (3) and make it equal to 0, thereby obtaining the corresponding relationship between the inner diameter and the outer diameter of the eddy current damping permanent magnet (6); Based on the set value of the inner diameter of the eddy current damping permanent magnet (6) and the corresponding relationship between the inner diameter and the outer diameter of the eddy current damping permanent magnet (6), the outer diameter value of the eddy current damping permanent magnet (6) is obtained; Determining a thickness range of the eddy current damping conductor (3) based on the numerical range of the eddy current damping force, the inner diameter value and the outer diameter value of the eddy current damping permanent magnet (6) and the functional relationship; Based on the thickness range of the eddy current damping conductor (3), the thickness of the eddy current damping conductor (3) is determined; wherein the thickness of the eddy current damping conductor is: in, is the eddy current damping force; is the thickness of the eddy current damping conductor.

2. The design method of the axial passive magnetic bearing with dual damping effect according to claim 1 is characterized in that: The method for determining the setting value range of the equivalent damping coefficient includes: Determine the axial resonance speed through modal analysis; Determining a set numerical range of the equivalent damping coefficient based on the design requirements of the equivalent damping coefficient, the axial resonant speed, the rotor weight, and the numerical range of the logarithmic attenuation rate; Among them, the equivalent damping coefficient satisfies the following relationship: in, is the equivalent damping coefficient; is the logarithmic attenuation rate required by the damping system, and its value is between 0.7 and 1; is the weight of the rotor, is the axial resonance speed.

3. The design method of the axial passive magnetic bearing with dual damping effect according to claim 1 is characterized in that: The method for determining the magnetohydrodynamic vibration absorption eddy current loss damping force comprises: Determine the magnetohydrodynamic vibration absorption damping coefficient and magnetohydrodynamic vibration absorption stiffness coefficient; Determining the magnetohydrodynamic vibration absorption eddy loss damping force based on the magnetohydrodynamic vibration absorption damping coefficient, the magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorber damping dynamics model; Among them, according to the principle of dynamics, the damping dynamics model of the magnetohydrodynamic vibration absorber for the magnetic levitation measurement platform is established, and the specific formula is as follows: in, is the magnetohydrodynamic vibration absorption eddy current loss damping force, is the ratio of the system mass borne by the magnetohydrodynamic vibration absorber, is the magnetohydrodynamic vibration absorption damping coefficient, is the magnetohydrodynamic vibration absorption stiffness coefficient, is the displacement caused by axial vibration, is the rotor weight, is the maximum axial load, is the acceleration due to gravity, For displacement About Time The second-order derivative of For displacement About Time The first derivative of .

4. The design method of the axial passive magnetic bearing with dual damping effect according to claim 3 is characterized in that: The determining of the magnetohydrodynamic vibration absorption damping coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient comprises: Determine the target stiffness coefficient; Determining the magnetohydrodynamic vibration absorption stiffness coefficient based on the target stiffness coefficient and the corresponding relationship between the eddy current equivalent stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient; Determining the magnetohydrodynamic vibration absorption damping coefficient based on the relationship between the magnetohydrodynamic vibration absorption damping coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient; Among them, the target stiffness coefficient is set to , eddy current equivalent stiffness coefficient and magnetohydrodynamic vibration absorption stiffness coefficient The corresponding relationship is: in, is the ratio of the system mass borne by the magnetohydrodynamic vibration absorber, is the system damping ratio, the ratio of the mass of the system borne by the magnetohydrodynamic vibration absorber In the range of 0.1~0.3, the system damping ratio Z is in the range of 0~0.125, from which the eddy current equivalent stiffness coefficient can be determined and magnetohydrodynamic vibration absorption stiffness coefficient The relationship is: The ratio of the mass of the system borne by the magnetohydrodynamic vibration absorber can be determined And determine the system damping ratio Calculated; Target stiffness coefficient And the eddy current equivalent stiffness coefficient and magnetohydrodynamic vibration absorption stiffness coefficient The corresponding relationship is: According to the target stiffness coefficient And the eddy current equivalent stiffness coefficient and magnetohydrodynamic vibration absorption stiffness coefficient The corresponding relationship between the magnetohydrodynamic vibration absorption stiffness coefficient can be obtained The value of magnetohydrodynamic vibration damping coefficient and magnetohydrodynamic vibration absorption stiffness coefficient and the magnetohydrodynamic vibration absorption stiffness coefficient , determine the magnetohydrodynamic vibration damping coefficient , where the magnetohydrodynamic vibration damping coefficient is and magnetohydrodynamic vibration absorption stiffness coefficient The relationship satisfies the following formula: 。 5. The design method of the axial passive magnetic bearing with dual damping effect according to claim 4 is characterized in that: Determining the target stiffness coefficient includes: Determining a first design parameter of the axial passive magnetic bearing according to the mechanical performance requirements of the axial passive magnetic bearing; Based on the first design parameter, obtaining the target stiffness coefficient of the axial passive magnetic bearing; Wherein, obtaining the target stiffness coefficient of the axial passive magnetic bearing based on the first design parameter includes: Calculating the target stiffness coefficient of the axial passive magnetic bearing based on the first design parameter, rotor weight and safety factor; Among them, the first design parameter includes the maximum axial load force is The rotor weight is , the safety factor is ; Assume that the weight of the rotor of the moving part of the magnetic suspension measurement platform is , the maximum axial load is , the maximum permissible axial displacement is , then the target stiffness coefficient required is ,in: in, is the safety factor, which is between 2 and 3; is the maximum axial load force; is the dead weight of the rotor; is the maximum allowable axial displacement; g is the acceleration of gravity, g=9.8m / s 2 .

6. The design method of the axial passive magnetic bearing with dual damping effect according to claim 1 is characterized in that: The design method further comprises: Determining second design parameters of the axial passive magnetic bearing according to the structure and magnetization property requirements and magnetization parameters of the permanent magnet of the axial passive magnetic bearing, wherein the second design parameters include the radius and radial thickness of the permanent magnet in the permanent magnet layer (5), and the thickness of the bearing air gap; Based on the second design parameter, the bearing stiffness of the axial passive magnetic bearing is obtained, the bearing stiffness of the axial passive magnetic bearing being the sum of the bearing stiffnesses of each permanent magnet layer (5); Determining the number of permanent magnet layers of the axial passive magnetic bearing according to the target stiffness and the bearing stiffness of the axial passive magnetic bearing; Among them, the number of permanent magnet layers N can be determined by the following formula: In the formula, is the target stiffness of the axial passive magnetic bearing, is the bearing stiffness of the single-layer permanent magnet layer (5).

7. The design method of the axial passive magnetic bearing with dual damping effect according to claim 6 is characterized in that: The structure of the axial passive magnetic bearing is designed according to the thickness of the eddy current damping conductor (3), comprising: The structure of the axial passive magnetic bearing is designed according to the thickness of the eddy current damping conductor (3) and the number of permanent magnet layers.

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