Magnetic levitation centrifugal blower

Abstract

This invention discloses a magnetically levitated centrifugal blower, whose permanent magnet synchronous motor is an axial flux permanent magnet synchronous motor. The rotor includes a spindle connected to the impeller at one end, and a turntable is fixedly mounted perpendicular to the spindle axis at the middle of the spindle. The stator of the axial flux permanent magnet synchronous motor and the stator of the axial magnetic levitation bearing are respectively arranged on both sides of the turntable, which simultaneously serves as both the rotor of the axial flux permanent magnet synchronous motor and the rotor of the axial magnetic levitation bearing. The radial magnetic levitation bearing is a permanent magnet bearing, with a pre-set radial offset between the stator permanent magnet ring and the rotor permanent magnet ring in the radial direction, and a pre-set axial offset between the stator permanent magnet ring and the rotor permanent magnet ring in the axial direction. This axial offset causes the axial magnetic force direction of the radial magnetic levitation bearing to be opposite to the aerodynamic axial force direction of the rotor. This invention simplifies the shaft system structure and reduces the aerodynamic axial force load of the axial magnetic levitation bearing.

Description

Technical Field

[0001] This invention relates to magnetic levitation hydrodynamic equipment, and in particular to a magnetic levitation centrifugal blower. Background Technology

[0002] A magnetic levitation centrifugal blower is an integrated device that employs an active magnetic levitation bearing, a high-speed permanent magnet synchronous motor, a high-efficiency pneumatic system, and a high-performance variable frequency control system. Its traditional main unit structure typically features a "slender shaft system" layout, such as the magnetic levitation centrifugal blower disclosed in CN203717391U. During operation, the magnetic levitation control system monitors the rotor's spatial position in real time through position sensors and dynamically adjusts the electromagnetic force of the magnetic levitation bearing, ensuring the rotor is stably suspended at the bearing center, achieving support without mechanical contact. The high-speed permanent magnet synchronous motor directly drives the centrifugal impeller mounted on the rotor shaft to rotate at high speed. Air is drawn in and accelerated by the impeller, increasing its kinetic and pressure energy under centrifugal force. This kinetic energy is then further converted into static pressure energy through a volute or diffuser, ultimately outputting high-pressure gas.

[0003] The magnetic bearing-rotor system, as the "heart" of a magnetic levitation centrifugal blower, determines the operational stability and reliability of the entire system. A commonly used structural composition is as follows: a rotor shaft integrating a permanent magnet motor rotor and a centrifugal impeller forms the rotating core of the system; a radial magnetic levitation bearing, consisting of two stator electromagnets at both ends of the rotor and a rotor ferromagnetic sleeve, generates a controllable radial electromagnetic force by controlling the current in each set of coils to balance the rotor's vertical offset; an electromagnetic thrust bearing (axial magnetic levitation bearing), located at one end of the rotor and consisting of a stator electromagnet disk and a rotor thrust disk, generates electromagnetic force by controlling the axial current to balance the axial thrust of the rotor; and position sensors are installed at each magnetic bearing location for high-precision, high-frequency detection of the gap between the rotor shaft and the bearing stator. Furthermore, the controller and power amplifier receive sensor signals, run control algorithms (such as PID and sliding mode control), calculate in real time the current required to maintain stable rotor levitation, and drive the magnetic bearing coils through the power amplifier. The system operates on a typical closed-loop active control process: the sensor detects displacement deviation → the controller calculates the control input → the power amplifier outputs control current → the magnetic bearing generates adjusting electromagnetic force → the rotor returns to the target position. This process is repeated tens of thousands of times per second, thereby achieving dynamic and stable levitation of the rotor.

[0004] Compared with traditional positive displacement Roots blowers, magnetic levitation centrifugal blowers have the advantages of high efficiency, low energy consumption, and low noise. However, existing magnetic levitation centrifugal blowers still have the following disadvantages: 1) Thrust magnetic bearing overload: In pursuit of high flow rate and high pressure ratio, the impeller size is increased, leading to a significant increase in aerodynamic axial force. This requires the electromagnetic thrust bearing to have extremely high load-bearing capacity. Traditional electromagnetic thrust bearings generate load-bearing capacity by increasing the current, but this results in excessive coil power consumption, severe heat generation, low efficiency, and a saturation limit, becoming a key bottleneck for system power density and reliability.

[0005] 2) Difficulties in thermal management: Long-shaft motors have long rotor heat dissipation paths and low efficiency, and the risk of permanent magnet demagnetization at high temperatures is increased. At the same time, the heating of the electromagnetic thrust bearing is coupled with the heating of the motor, which further worsens the thermal management of the system and is prone to cause the winding temperature rise to exceed the limit and the rotor thermal bending vibration.

[0006] 3) Poor rotor impact resistance: The low bending stiffness of the slender rotor makes it prone to bending and rubbing damage to the protective bearings due to the huge kinetic energy and impact load when it is dropped due to a fault or external impact. This is a reliability problem that limits its application in harsh working conditions.

[0007] 4) Complex magnetic bearing control system: The magnetic levitation control system needs to simultaneously handle the large load of aerodynamic axial force on the electromagnetic thrust bearing side, multi-degree-of-freedom vibration in the radial direction of the rotor, and strong coupling between the degrees of freedom, which makes the control algorithm more complex and puts severe tests on hardware and software such as controllers and sensors. The accumulation of axial dimensional tolerances of various parts and the thermal axial expansion of the rotor make it difficult to guarantee the centering of the radial sensor, which reduces the accuracy and reliability of the radial motion control of the rotor.

[0008] 5) High cost problem: Long shaft rotors require more high-performance permanent magnet materials, and there are many main parts. In order to meet the dimensional tolerance requirements, the processing procedures of materials such as the base, end cover, and rotor are complex and the processing precision is high, making it difficult to reduce costs from the design.

[0009] To address some of the aforementioned issues, conventional improvement solutions, such as enhancing thrust bearing cooling, using larger thrust bearings, or optimizing control algorithms to distribute the load, are all incremental improvements on the existing architecture. These solutions fail to physically eliminate or offset the steady-state axial load; instead, they increase the system's complexity, size, and cost, and cannot fundamentally solve the problems of the thrust bearing's load-bearing limit and the root cause of heat generation.

[0010] Therefore, there is an urgent need for a new type of magnetic levitation centrifugal blower that can simplify the shaft structure, distribute the aerodynamic axial force load of the electromagnetic thrust bearing, improve the rotor's impact resistance, increase the system's heat dissipation capacity, reduce costs, and improve overall reliability while maintaining the inherent advantages of magnetic levitation technology. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to address the comprehensive technical difficulties of existing magnetic levitation centrifugal blowers under high load conditions, such as axial suspension bearing overload, difficult thermal management, poor rotor impact resistance, complex magnetic bearing control system and high cost caused by large aerodynamic axial force and excessively long shaft system. The present invention provides a magnetic levitation centrifugal blower with a shorter shaft system and a pre-compensation function for aerodynamic axial force load.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A magnetically levitated centrifugal blower includes a base, an axial magnetic levitation bearing, and a permanent magnet synchronous motor. A first end cover is installed on one side of the base, and a second end cover is installed on the other side. Rotor mounting holes are provided opposite to each other on the first and second end covers. A rotor is mounted in the rotor mounting holes of the first and second end covers via a radial magnetic levitation bearing. One end of the rotor is connected to an impeller. Its structural features are: The axial magnetic levitation bearing includes an axial bearing stator and an axial bearing rotor; The permanent magnet synchronous motor is an axial flux permanent magnet synchronous motor. The axial flux permanent magnet synchronous motor includes a motor stator and a motor rotor. The motor stator includes windings and an iron core. The iron core is arranged in a ring shape, and the windings are installed in a ring shape on the iron core. The rotor includes a spindle with one end connected to the impeller, and a turntable is fixedly mounted in the middle of the spindle perpendicular to the spindle axis. Both the spindle and the turntable are made of magnetically conductive material, and a permanent magnet is mounted on the outer axial end face of the turntable. The motor stator and the axial bearing stator are respectively arranged on both sides of the turntable. The turntable serves as both the motor rotor and the axial bearing rotor, and the permanent magnet is arranged directly opposite the iron core of the motor stator. The radial magnetic levitation bearing is a permanent magnet bearing, comprising a radial bearing stator and a radial bearing rotor. The radial bearing stator includes a bearing stator permanent magnet ring, and the radial bearing rotor includes a bearing rotor permanent magnet ring. The axis of the bearing stator permanent magnet ring and the axis of the bearing rotor permanent magnet ring are pre-biased in the radial direction of the rotor, and this radial bias makes the repulsive force of the radial magnetic levitation bearing in the direction of gravity just balanced with the gravity of the rotor. At the same time, the bearing stator permanent magnet ring and the bearing rotor permanent magnet ring are pre-biased in the axial direction of the rotor, and this axial bias makes the direction of the axial magnetic force of the radial magnetic levitation bearing opposite to the direction of the aerodynamic axial force of the rotor.

[0013] The rotor of the present invention includes a spindle for connecting and driving an impeller, and a turntable is fixedly mounted on the spindle. The permanent magnet synchronous motor of the present invention is an axial flux permanent magnet synchronous motor, and the permanent magnet synchronous motor and the axial magnetic levitation bearing share the turntable. This greatly simplifies and shortens the shaft structure of the magnetic levitation centrifugal blower of the present invention, thereby improving the rotor's impact resistance and reducing the cost of the magnetic levitation centrifugal blower.

[0014] Furthermore, in this invention, the axis of the permanent magnet ring of the bearing stator and the axis of the permanent magnet ring of the bearing rotor are pre-biased in the radial direction of the rotor. This radial bias ensures that the repulsive force of the radial magnetic bearing in the direction of gravity is exactly balanced with the gravity of the rotor. When the rotor is static, the radial magnetic bearing can provide a radial levitation force to levitate the rotor radially. Simultaneously, the permanent magnet ring of the bearing stator and the permanent magnet ring of the bearing rotor are pre-biased in the axial direction of the rotor. This axial bias ensures that the direction of the axial magnetic force of the radial magnetic bearing is opposite to the direction of the aerodynamic axial force of the rotor. When the rotor is running, the pre-biased axial bias of the radial magnetic bearing allows it to bear most of the axial load. The axial magnetic bearing only needs to handle the dynamic disturbance of the rotor, thereby achieving better control of power consumption and heat generation, significantly improving the overall efficiency, and simplifying the magnetic bearing control system.

[0015] Preferably, the axial bearing stator is arranged radially on the motor stator to further shorten the shaft length.

[0016] Preferably, a first protective bearing seat is installed on the outside of the rotor mounting hole of the first end cover, and a second protective bearing seat is installed on the outside of the rotor mounting hole of the second end cover. Radial protective bearings are installed in the first and second protective bearing seats respectively, and the gap between the radial protective bearing and the spindle is smaller than the gap between the radial bearing stator and the radial bearing rotor of the radial magnetic levitation bearing, so as to provide protection for the shaft structure during initial assembly and extreme harsh conditions.

[0017] Preferably, the impeller is mounted on the outside of the first end cover, and a thrust protection bearing housing is arranged on the outside of the second end cover. A thrust protection bearing is installed between the thrust protection bearing housing and the spindle to provide initial axial support when the rotor starts and stops.

[0018] Preferably, a non-magnetic first sheath is arranged inside the permanent magnet body to isolate the electromagnetic excitation magnetic circuit of the electromagnetic thrust bearing inside the inner turntable.

[0019] Preferably, a second protective sleeve is arranged around the outer periphery of the permanent magnet to protect the permanent magnet from being thrown out under the action of centrifugal force.

[0020] Preferably, the radial magnetic levitation bearing is a repulsive permanent magnet bearing or an attractive permanent magnet bearing.

[0021] Preferably, the axial bearing stator includes a magnetic ring, an axial bearing coil, and a magnetic plate. The magnetic ring and the magnetic plate surround the axial bearing coil. When the axial bearing coil is energized, the induced magnetic field passes through the magnetic ring, the magnetic plate, the air gap, and the turntable facing the axial bearing stator to form an axial magnetic circuit.

[0022] Preferably, the radial bearing rotor further includes an axial magnetic isolation ring, a bearing sleeve, and a radial magnetic isolation ring, wherein the axial magnetic isolation ring, the bearing sleeve, and the radial magnetic isolation ring form a cavity, and the bearing permanent magnet ring is arranged in the cavity.

[0023] Compared with the prior art, the beneficial effects of the present invention are: This invention combines "active load pre-compensation" with "structural reconfiguration" to achieve the following multi-objective synergistic optimization and solve comprehensive technical problems: (1) Fundamentally solve the overload and heat generation of the thrust bearing as an axial magnetic levitation bearing: The preset axial offset (misalignment) of the radial magnetic levitation bearing bears most (or even the vast majority) of the steady-state aerodynamic axial force, thereby freeing the thrust electromagnetic bearing from the heavy steady-state load, allowing it to only deal with dynamic disturbances, thus the power consumption and heat generation drop sharply, the load-bearing bottleneck is broken, and the system efficiency and reliability are greatly improved.

[0024] (2) Achieving ultra-short and rigid rotor: The permanent magnet synchronous motor of the present invention adopts an axial flux motor, which makes the axial length of the rotor extremely short. Combined with a high-strength spindle, it forms an ultra-short rigid rotor with extremely high critical speed. It always works in the rigid region, has simple dynamic characteristics, extremely strong bending stiffness, and a qualitative leap in drop resistance and impact resistance.

[0025] (3) Greatly simplified control system: The present invention replaces the radial electromagnetic bearing used in the traditional scheme with a radial permanent magnet bias bearing (radial magnetic suspension bearing), so that the control system does not need to deal with the control of multiple degrees of freedom in the radial direction. The static active pre-compensation of the pneumatic axial force load greatly reduces the load of the electromagnetic thrust bearing (axial magnetic suspension bearing), significantly reduces the requirements of the control system algorithm and hardware, and improves reliability.

[0026] (4) Optimize heat dissipation and reduce costs: The compact structure of the above-mentioned "radial permanent magnet bias bearing + axial flux motor / electromagnetic thrust bearing shared turntable" greatly simplifies heat dissipation. The motor turntable has a large heat dissipation area, a short cooling path, and efficient heat dissipation. The amount of permanent magnets used in the compact structure is significantly reduced, and the material cost and control system cost are reduced simultaneously.

[0027] (5) Provides designable axial force load compensation: The preset misalignment (radial offset and axial offset) is a mechanical parameter that can be precisely designed and adjusted. It can be "customized" pre-compensated for different rotor weights and impeller specific aerodynamic axial forces, giving the system excellent working condition adaptability and scalability. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a structural diagram of the motor stator of the axial magnetic levitation permanent magnet synchronous motor of the present invention; Figure 3 This is a schematic diagram of the rotor assembly of the present invention; Figure 4 This is a schematic diagram of the cross-sectional structure of the turntable of the present invention; Figure 5 This is a schematic diagram of the axial bearing stator of the present invention; Figure 6 This is a schematic diagram of the rotor radial permanent magnet bias bearing assembly of the present invention; Figure 7 This is a schematic diagram of the stator radial permanent magnet bearing offset of the present invention; Figure 8 This is a schematic diagram of the axial offset of the permanent magnet bearing of the present invention; The markings in the diagram are as follows: 1-Rotor, 2-Motor stator, 3-Axial bearing stator, 4-First end cover, 5-Second end cover, 6-Frame, 7-Radial bearing stator, 8-First protective bearing housing, 9-Second protective bearing housing, 10-Radial protective bearing, 11-Thrust protective bearing housing, 12-Thrust protective bearing, 13-Rotor mounting hole; 1a-Mandrel, 1b-First sheath, 1c-Permanent magnet, 1d-Second sheath, 1e-Radial bearing rotor, 1f-Tie rod, 1g-Lock nut, 1h-Impeller, 1i-Thrust protection bearing retaining ring, 1j-Rotator, 1k-Magnetic shielding block, e0-Permanent magnet ring of bearing rotor, e1-Axial magnetic shielding ring, e2-Magnetic bearing sheath, e3-Radial magnetic shielding ring; 2a - Winding, 2b - Core; 3a-Magnetic ring, 3b-Axial bearing coil, 3c-Magnetic plate; 7a - Bearing stator permanent magnet ring; 7b - Inner bushing; δ - radial offset, α - axial offset. Detailed Implementation

[0030] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0031] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] like Figure 1 As shown, one embodiment of the main structure of the magnetic levitation centrifugal blower of the present invention includes a rotor 1, an axial magnetic levitation bearing, a permanent magnet synchronous motor, a first end cover 4, a second end cover 5, and a base 6.

[0034] The permanent magnet synchronous motor is an axial flux permanent magnet synchronous motor. The axial flux permanent magnet synchronous motor has a disc-type structure, mainly consisting of a base 6 and first end covers 4 and second end covers 5 mounted on both sides of the base 6, forming a supporting structure. The axial flux permanent magnet synchronous motor includes a motor stator 2 and a motor rotor. In this embodiment, the motor stator 2 is symmetrically arranged on both sides of the rotor 1's turntable 1j, and is respectively mounted on the first end cover 4 and the second end cover 5.

[0035] The axial magnetic levitation bearing includes an axial bearing stator 3 and an axial bearing rotor (thrust disk), and the axial magnetic levitation bearing is the basic structure for precisely controlling the axial movement of the rotor 1. In this embodiment, the axial magnetic levitation bearing is an electromagnetic thrust bearing. Obviously, the axial magnetic levitation bearing is not limited to electromagnetic thrust bearings, but can also be other axial magnetic levitation bearings that can achieve axial levitation, as known to those skilled in the art. The axial bearing stator 3 is arranged radially inside the axial flux motor stator 2. The axial bearing stator 3 is also symmetrically arranged on both sides of the rotor 1, and is respectively installed on the first end cover 4 and the second end cover 5. That is, the axial flux motor stator 2 and the axial bearing stator 3 share the rotor disk 1j of the rotor 1. The rotor disk 1j serves as both the motor rotor of the axial flux permanent magnet synchronous motor and the axial bearing rotor of the axial magnetic levitation bearing.

[0036] The radial magnetic levitation bearing is a permanent magnet bearing, which includes a radial bearing stator 7 and a radial bearing rotor. Rotor mounting holes 13 are provided opposite to each other on the first end cover 4 and the second end cover 5, and the radial bearing stator 7 is installed in each of the two rotor mounting holes 13.

[0037] A first protective bearing seat 8 and a second protective bearing seat 9 are respectively arranged on the outer side of the first end cover 4 and the second end cover 5. A radial protective bearing 10 is installed in the first protective bearing seat 8 and the second protective bearing seat 9. A thrust protective bearing seat 11 is arranged on the outer side of the second protective bearing seat 9, and a thrust protective bearing 12 is installed between the thrust protective bearing seat 11 and the right end face of the spindle 1a of the rotor 1.

[0038] like Figure 2 As shown, the stator 2 of the axial flux motor consists of windings 2a and an iron core 2b. The windings 2a are wound into ring coils and embedded in each slot of the iron core 2b. The beginning and end of each coil are connected in a specific manner to form a three-phase balanced winding arrangement. When the windings are energized, a three-phase symmetrical rotating magnetomotive force is generated. The iron core 2b is made of slotted strip silicon laminations wound together; it is both the basic structure for arranging the windings 2a and the main medium for forming the axial magnetic circuit of the axial flux motor.

[0039] like Figure 3 , Figure 4 As shown, the integrated rotor 1 mainly consists of a spindle 1a, a non-magnetic first sheath 1b, a permanent magnet 1c, a carbon fiber second sheath 1d, a radial bearing rotor 1e, a tie rod 1f, a lock nut 1g, an impeller 1h, a thrust protection bearing retaining ring 1i, and a turntable 1j. The impeller 1h is mounted on one end of the spindle 1a via the tie rod 1f and lock nut 1g. The turntable 1j is integrally formed perpendicular to the spindle axis at the middle of the spindle 1a. Both the spindle 1a and the turntable 1j are made of magnetically conductive material.

[0040] Reference Figure 5The axial bearing stator 3 consists of a magnetic ring 3a, an axial bearing coil 3b, and a magnetic plate 3c. When the axial bearing coil 3b is energized, the induced magnetic field passes through the magnetic ring 3a, the magnetic plate 3c, the air gap, and the turntable 1j facing the axial bearing stator 3 to form a second axial magnetic circuit. When the rotor 1 rotates, a displacement sensor (not shown in the figure) arranged within the axial bearing stator 3 monitors the axial position of the spindle 1a in real time, thereby controlling the magnitude of the electromagnetic levitation force of the axial magnetic levitation bearing. To prevent the second axial magnetic circuit formed by the axial magnetic levitation bearing (electromagnetic thrust bearing) from coupling with the first axial magnetic circuit passing through the permanent magnet 1c and interfering with the control of the electromagnetic thrust bearing, a non-magnetic first sheath 1b is installed on the outer axial end face of the turntable 1j. The first sheath 1b is interference-fitted with the turntable 1j to prevent them from loosening due to centrifugal force. The permanent magnet 1c is installed on the outer periphery of the first sheath 1b, referring to… Figure 1 , Figure 2 The permanent magnet 1c is directly opposite the iron core 2b of the stator 2 of the axial flux motor. The magnetic field forms the first axial magnetic circuit through the permanent magnet 1c, the air gap, and the iron core 2b of the stator 2 of the axial flux motor. After the winding 2a is energized, the rotating magnetic field synthesized by the stator 2 of the axial flux motor drives the rotor 1 to rotate.

[0041] It should be noted that the integrated rotor 1 can simultaneously serve as the magnetic circuit medium for both the axial flux motor stator 2 and the axial bearing stator 3. This design greatly simplifies the shaft structure of the magnetic levitation centrifugal blower. The topology of the permanent magnet 1c can be designed according to the motor pole slot fit to ensure the sinusoidal nature of the back electromotive force. Furthermore, a second sheath 1d made of carbon fiber is wound around the outside of the permanent magnet 1c to prevent it from being thrown out under centrifugal force.

[0042] refer to Figure 4 A magnetic isolation block 1k is arranged between two adjacent permanent magnets 1c, which not only isolates the magnetic field of the adjacent magnets, but also serves as a constraint in the circumferential direction.

[0043] As a supplement, the stator 2 of the axial flux motor can adopt a coreless or slotless structure, the winding 2a can adopt a centralized or distributed winding, and the permanent magnet 1c in the integrated rotor 1 can adopt various topological structures, radial or axial arrangement methods, magnetization methods, etc. All implementation methods that actually form the axial magnetic circuit structure can be used as implementation schemes of the present invention.

[0044] As a supplement, the axial magnetic circuit formed by the shared integrated rotor 1 of the axial flux motor stator 2 and the axial bearing stator 3 can be realized in various ways, such as outer electromagnetic thrust bearing-inner axial flux motor, outer electromagnetic thrust bearing-middle axial flux motor-inner electromagnetic thrust bearing, etc., double stator-single rotor, double stator-double rotor, multiple stator-multiple rotor, etc., vertical or horizontal arrangement, etc. The actual implementation of the axial magnetic circuit structure formed by the turntable of the shared integrated rotor 1 of the axial flux motor stator 2 and the axial bearing stator 3 can all be used as implementation schemes of the present invention.

[0045] Reference Figure 1 The radial bearing rotor 1e is mounted at both ends of the integrated rotor 1 and is the moving part of the radial magnetic levitation bearing. For example... Figure 6 , Figure 7 As shown, the radial bearing rotor 1e consists of a bearing rotor permanent magnet ring e0, an axial magnetic isolation ring e1, a magnetic bearing sleeve e2, and a radial magnetic isolation ring e3. The bearing rotor permanent magnet ring e0 consists of a pair of permanent magnet rings arranged in opposite directions after magnetization, i.e., the two sides are S poles and the middle is an N pole. (Reference) Figure 1 The radial bearing stator 7 also consists of a pair of permanent magnet rings with S poles on both sides and N poles in the middle. In this case, the radial bearing stator 7 and the radial bearing rotor 1e form a repulsive permanent magnet bearing. As a supplement, the above-mentioned radial magnetic levitation bearing can use one or more pairs of permanent magnet rings, and the magnetization method can adopt various magnetization methods such as radial, axial, and Halebeck magnetization. Moreover, the attraction-type or repulsion-type permanent magnet levitation method formed by the magnetic circuit of the permanent magnet bearing can be used as a solution.

[0046] like Figure 7 As shown, the radial bearing stator 7 consists of a bearing stator permanent magnet ring 7a and an inner bushing 7b. The inner bushing 7b mainly protects the bearing stator permanent magnet ring 7a. The axis of the bearing stator permanent magnet ring 7a and the axis of the bearing rotor permanent magnet ring e0 are pre-biased by a radial amount δ in the radial direction of the rotor. This radial bias ensures that the repulsive force of the radial magnetic levitation bearing in the direction of gravity is exactly balanced with the gravity of the rotor 1, that is, the rotor 1 can achieve stable levitation in the radial direction when it is static.

[0047] This radial offset δ can be achieved in the following way: 1) The inner and outer diameters of the permanent magnet ring e0 of the radial bearing rotor 1e are concentric, while the permanent magnet ring 7a of the radial bearing stator 7 adopts an eccentric design, i.e. Figure 7 As shown, the inner circle of the bearing stator permanent magnet ring 7a is concentric with the bearing rotor permanent magnet ring e0, and the outer circle of the bearing stator permanent magnet ring 7a is biased in the opposite direction of the rotor 1's gravity, which makes the bearing stator permanent magnet ring 7a use more material in the direction of the rotor's gravity. 2) The permanent magnet ring e0 of the radial bearing rotor 1e and the permanent magnet ring 7a of the radial bearing stator 7 are designed with the same center. However, the permanent magnet ring e0 of the radial bearing rotor and the permanent magnet ring 7a of the radial bearing stator 7 are not on the same axis when assembled. That is, the axis offset is preset on the first and second end covers, so that the axis of the permanent magnet ring 7a of the radial bearing stator 7 deviates from the direction of gravity of the rotor 1 during the initial assembly.

[0048] refer to Figure 8 The permanent magnet ring 7a of the radial bearing stator 7 and the permanent magnet ring e0 of the radial bearing rotor 1e on the rotor 1 are pre-biased by an axial amount α in the axial direction, and the axial bias α makes the direction of the axial magnetic force of the radial magnetic levitation bearing opposite to the direction of the aerodynamic axial force of the rotor 1. In this embodiment, a repulsive type permanent magnet levitation bearing is used as an example for explanation, wherein the axial bias of the permanent magnet ring 7a of the radial bearing stator 7 makes the repulsive force direction between the permanent magnet ring 7a of the bearing stator 7a and the permanent magnet ring e0 of the bearing rotor opposite to the direction of the aerodynamic axial force of the rotor 1. Figure 1 The axial forces of the impellers shown are in opposite directions. The preset axial offset can be adjusted according to the weight of different rotor models and the aerodynamic axial force. While achieving radial suspension of rotor 1, the goal is to distribute more axial suspension force to offset or weaken the aerodynamic axial force of the axial magnetic suspension bearing. This achieves the purpose of the radial magnetic suspension bearing as the main bearing and the axial magnetic suspension bearing as the auxiliary bearing. That is, the radial magnetic suspension bearing achieves radial suspension and axial load "pre-compensation" of rotor 1, while the axial magnetic suspension bearing (electromagnetic thrust bearing) basically does not bear aerodynamic load and only makes fine adjustments to the axial movement of rotor 1 during startup and normal operation.

[0049] refer to Figure 1 , Figure 6 and Figure 7 To prevent high-temperature demagnetization of the radial magnetic levitation bearing under extreme working conditions, a radial protection bearing 10 is installed in the inner hole of the first protective bearing seat 8 and the second protective bearing seat 9. The gap between the radial protection bearing 10 and the spindle 1a is smaller than the gap between the radial bearing stator 7 and the radial bearing rotor 1e of the radial magnetic levitation bearing. When the bearing rotor permanent magnet ring e0 on the rotor 1 and the radial bias permanent magnet ring 7a on the first end cover 4 undergo high-temperature demagnetization or local demagnetization, making it impossible for the rotor 1 to achieve radial stable levitation, the radial protection bearing 10 serves as the basic protective structure for the rotor 1, preventing serious damage caused by the rotor 1 becoming unstable.

[0050] In addition, before rotor 1 starts working, due to axial instability, it is necessary to provide initial axial support to rotor 1, therefore, as follows Figure 1 , Figure 3As shown, a thrust protection bearing 12 is installed inside the thrust protection bearing housing 11, directly opposite the thrust protection bearing retaining ring 1i on the integrated rotor 1. As previously described, the radial magnetic levitation bearing with a pre-set axial offset α causes the integrated rotor 1 to have an initial movement away from the aerodynamic axial direction, that is, the initial axial position of the rotor 1 is offset from the impeller side. Before the rotor 1 starts running, the thrust protection bearing 12 can provide initial axial support for the rotor 1. When the rotor 1 starts running, the axial displacement of the rotor 1 is briefly adjusted by the axial magnetic levitation bearing (electromagnetic thrust bearing) and disengaged from the thrust protection bearing 12. As the rotor 1 speed increases, the aerodynamic axial force gradually increases. At this time, the radial magnetic levitation bearing with load pre-compensation function gradually balances the aerodynamic axial force. The axial magnetic levitation bearing (electromagnetic thrust bearing) only handles dynamic disturbances, and the rotor 1 achieves stable levitation.

[0051] The rotor 1 of the present invention integrates a radial bearing rotor with a radial magnetic levitation bearing, a motor rotor with an axial flux permanent magnet synchronous motor, and an axial bearing rotor with an axial magnetic levitation bearing (preferably an electromagnetic thrust bearing), making the shaft system structure of the present invention compact, and the radial magnetic levitation bearing has a pneumatic axial force load pre-compensation function by setting the axial offset α.

[0052] In use, when rotor 1 is static, radial levitation force is provided by radial magnetic levitation bearing to levitate the rotor radially. However, at this time, rotor 1 is axially unstable, and the non-impeller side shaft end of rotor spindle 1a is tightly attached to thrust protection bearing 12. Before rotor 1 starts running, axial levitation force is provided by axial magnetic levitation bearing (electromagnetic thrust bearing) to make the shaft end of rotor spindle 1a leave thrust protection bearing 12. The gap between turntable 1j and motor stator 2 and axial bearing stator 3 is adjusted to the design value in real time by electromagnetic force control. At this time, the winding of motor stator 2 is energized, and rotor 1 achieves stable operation. As the rotational speed of rotor 1 increases, the aerodynamic axial force continuously increases. Thanks to the preset axial offset α of radial magnetic levitation bearing, radial magnetic levitation bearing bears most of the axial load. Axial magnetic levitation bearing (electromagnetic thrust bearing) only needs to handle the dynamic disturbance of rotor 1, thereby achieving better control of power consumption and heat generation, and also achieving a significant improvement in overall efficiency.

[0053] The structure of this invention can be used in other similar fluid equipment, such as compressors with impellers on both sides of the rotor, vacuum pumps with an impeller on one side, heat pumps, refrigeration compressors, etc.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A magnetically levitated centrifugal blower, comprising a base (6), an axial magnetic levitation bearing, and a permanent magnet synchronous motor, wherein a first end cover (4) is installed on one side of the base and a second end cover (5) is installed on the other side, and rotor mounting holes (13) are provided opposite to each other on the first end cover (4) and the second end cover (5), and a rotor (1) is mounted in the rotor mounting holes of the first end cover (4) and the second end cover (5) via a radial magnetic levitation bearing, and one end of the rotor is connected to an impeller (1h), characterized in that: The axial magnetic levitation bearing includes an axial bearing stator (3) and an axial bearing rotor; The permanent magnet synchronous motor is an axial flux permanent magnet synchronous motor. The axial flux permanent magnet synchronous motor includes a motor stator (2) and a motor rotor. The motor stator includes a winding (2a) and an iron core (2b). The iron core is arranged in a ring shape, and the winding is installed in a ring shape on the iron core. The rotor includes a spindle (1a) with one end connected to the impeller, and a turntable (1j) is fixedly mounted in the middle of the spindle perpendicular to the spindle axis. Both the spindle and the turntable are made of magnetically conductive material, and a permanent magnet (1c) is mounted on the outer axial end face of the turntable. The motor stator and the axial bearing stator are respectively arranged on both sides of the turntable. The turntable serves as both the motor rotor and the axial bearing rotor, and the permanent magnet (1c) is arranged facing the iron core (2b) of the motor stator. The radial magnetic levitation bearing is a permanent magnet bearing, which includes a radial bearing stator (7) and a radial bearing rotor (1e). The radial bearing stator (7) includes a bearing stator permanent magnet ring (7a), and the radial bearing rotor (1e) includes a bearing rotor permanent magnet ring (e0). The axis of the bearing stator permanent magnet ring and the axis of the bearing rotor permanent magnet ring are pre-biased in the radial direction of the rotor. The radial bias makes the repulsive force of the radial magnetic levitation bearing in the direction of gravity just balanced with the gravity of the rotor. At the same time, the bearing stator permanent magnet ring and the bearing rotor permanent magnet ring are pre-biased in the axial direction of the rotor. The axial bias makes the direction of the axial magnetic force of the radial magnetic levitation bearing opposite to the direction of the aerodynamic axial force of the rotor.

2. The magnetic levitation centrifugal blower according to claim 1, characterized in that, The axial bearing stator is arranged radially on the motor stator (2).

3. The magnetic levitation centrifugal blower according to claim 1, characterized in that, A first protective bearing seat (8) is installed on the outside of the rotor mounting hole of the first end cover, and a second protective bearing seat (9) is installed on the outside of the rotor mounting hole of the second end cover. Radial protective bearings (10) are installed in the first protective bearing seat (8) and the second protective bearing seat (9), respectively. The gap between the radial protective bearing and the spindle is smaller than the gap between the radial bearing stator and the radial bearing rotor of the radial magnetic levitation bearing.

4. The magnetic levitation centrifugal blower according to claim 3, characterized in that, The impeller is installed on the outside of the first end cover, and a thrust protection bearing seat (11) is arranged on the outside of the second end cover. A thrust protection bearing (12) is installed between the thrust protection bearing seat and the spindle.

5. The magnetic levitation centrifugal blower according to claim 1, characterized in that, The permanent magnet (1c) has a non-magnetic first sheath (1b) arranged inside it.

6. The magnetic levitation centrifugal blower according to claim 1, characterized in that, A second sheath (1d) is arranged around the periphery of the permanent magnet (1c).

7. The magnetic levitation centrifugal blower according to claim 1, characterized in that, The radial magnetic levitation bearing is a repulsive permanent magnet bearing or an attractive permanent magnet bearing.

8. The magnetic levitation centrifugal blower according to claim 1, characterized in that, The axial bearing stator includes a magnetic ring (3a), an axial bearing coil (3b), and a magnetic plate (3c). The magnetic ring (3a) and the magnetic plate (3c) surround the axial bearing coil. When the axial bearing coil is energized, the induced magnetic field passes through the magnetic ring, the magnetic plate, the air gap, and the turntable facing the axial bearing stator to form an axial magnetic circuit.

9. The magnetic levitation centrifugal blower according to claim 1, characterized in that, The radial bearing rotor also includes an axial magnetic isolation ring (e1), a bearing sleeve (e2), and a radial magnetic isolation ring (e3). The axial magnetic isolation ring (e1), the bearing sleeve (e2), and the radial magnetic isolation ring (e3) form a cavity, and the bearing permanent magnet ring is arranged in the cavity.

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