Magnetic levitation compressor based on target disc type magnetic concentrating structure

Abstract

The application relates to a magnetic suspension compressor based on a target disc type magnetic concentration structure, a plurality of multi-pole shoe type electromagnetic circuit components are arranged at equal angles and uniformly distributed on a mounting plate; the mounting plate is fixed in the inside of a shell body, the center of which is provided with a circular hole; a rotor magnetic concentration disc is provided with a plurality of annular magnetic concentration teeth which are concentric and respectively face the pole shoes, a main rotating shaft vertically penetrates through the circular hole and is matched with the circular hole; one centrifugal impeller is connected to the upper end and the lower end of the main rotating shaft respectively; a compression cavity assembly is fixedly connected to the upper end and the lower end of the shell body, has two axial air inlets, and a pair of radial air outlets are arranged on the shell body; the centrifugal impeller extends into the cavity of the compression cavity assembly and is aligned with the axial air inlets. The application greatly improves the effective magnetic flux utilization rate and generates controllable and adjustable axial electromagnetic bearing force, so that stable and non-contact thrust support of the compressor rotor shaft system is realized under the compact radial and axial dimensions of the whole machine, and the integrated deployment requirement of small-sized and portable fluid compression equipment is met.

Description

Technical Field

[0001] This invention relates to a magnetic levitation compressor, specifically a magnetic levitation compressor based on a target-disc magnetic focusing structure, belonging to the field of magnetic levitation compressor technology. Background Technology

[0002] Existing active magnetic levitation compressors typically employ radial-axial separable electromagnetic bearings or hybrid magnetic bearings as the core of contactless rotor support. Rotor stability, power consumption reduction, and adaptation to high-speed centrifugal impeller loads are improved through permanent magnet offset, axial thrust disk optimization, integrated control coils, or multi-degree-of-freedom coupling. While these improvements have yielded some progress in suppressing eddy current losses, enhancing dynamic response, and extending continuous operating life, they still generally suffer from engineering bottlenecks such as a large number of bearing actuators, complex magnetic circuit topology and assembly, sensitivity to air gap uniformity and rotor coaxiality, difficulty in further reducing the radial / axial dimensions of the system, and strong reliance on high-precision multi-dimensional displacement sensing and high-bandwidth multi-channel closed-loop control.

[0003] In the prior art, for example:

[0004] The paper "Magnetic Levitation Centrifugal Compressor and Its Control Method" published on May 22, 2020, with publication number CN111188778A, proposes a combination structure of magnetic levitation main shaft, thrust disc, front axial bearing and rear axial bearing. Active adjustment is achieved through labyrinth shaft seal and axial clearance control to improve load-bearing capacity and high-speed stability. However, it has many bearing units and large mutual interference between axial magnetic circuits. It still does not provide sufficient support for miniaturizing the overall size of the compressor and reducing the dependence on high-precision displacement sensors and complex control algorithms.

[0005] The publication date is January 18, 2019. The publication number is CN109236712A. The "Magnetic Levitation Centrifugal Compressor System and its Control Method, Device and Storage Medium" discloses a system structure including a magnetic levitation centrifugal compressor, a condenser, an evaporator and a check valve for the exhaust pipe. It aims to reduce active power consumption and improve reliability through system-level anti-backflow design and closed-loop control. However, it still requires multiple sets of radial / axial control components and sensors, and the system is relatively complex. In compact or portable application scenarios, the radial dimension is relatively large and the assembly tolerance requirements are strict.

[0006] The publication date is March 26, 2021. The publication number is CN212803628U. The invention "A magnetic levitation centrifugal compressor" shortens the axial length and improves the overall compactness by integrating the radial and axial bearing functions (magnetic levitation support combined with impeller direct connection structure). However, it still relies on multiple sets of magnetic bearing assemblies and auxiliary sealing structures, which results in high manufacturing costs and miniaturization difficulties. Furthermore, the sensitivity to rotor dynamic balance and air gap consistency has not been fundamentally alleviated.

[0007] The paper "A Magnetic Levitation Compressor Structure" published on April 20, 2018, with publication number CN107939699A, proposes a coupling structure that uses a sensor bracket to fix an axial displacement sensor and a matching magnetic bearing and rotor support. It achieves five-degree-of-freedom active levitation by superimposing multi-channel sensor signals to control the current. It emphasizes the advantages of compact size and energy efficiency. However, the overall system still highly depends on precision sensing links and high-performance power electronic modules, and the engineering implementation cost and reliability pressure are relatively large.

[0008] Therefore, it is evident that existing magnetic levitation compressors, especially the active magnetic bearings used in their rotor supports, typically require separate arrangements of radial and axial magnetic bearings, or a combination of multiple magnetic pole assemblies, control coils, and permanent magnet bias units to achieve five-degree-of-freedom rotor levitation control. This results in an excessive number of bearing actuators, complex interwoven magnetic circuit links, a bulky and redundant overall structure, and difficulty in further compressing axial and radial dimensions. Consequently, this leads to cumbersome assembly and debugging processes, stringent requirements for component machining accuracy and air gap uniformity / rotor coaxiality, high overall system manufacturing and maintenance costs, and a high barrier to engineering implementation. While some solutions introduce permanent magnet bias units, the magnetic flux coupling path design between the permanent magnet and the electromagnetic coil is unreasonable, often consisting of a simple superposition of a planar thrust disk and a single magnetic pole. This results in low magnetic flux utilization, an inability to effectively combine with a magnetically focused structure to improve force density, and the continued need for high-current excitation assistance, failing to fundamentally reduce power consumption and control complexity. Meanwhile, to ensure the stable suspension state and anti-disturbance dynamic response performance of the high-speed rotor under the load of the centrifugal impeller, the bearing control system often relies heavily on multi-dimensional high-resolution displacement sensing elements (such as eddy current displacement sensors) and high-bandwidth multi-channel controllers to carry out real-time closed-loop regulation, which greatly increases the design complexity and operating energy consumption of the power electronic module. In the application scenarios of miniaturized or compact magnetic levitation compressors, due to the narrow constraints of magnetic pole layout space, the physical upper limit of coil winding density, and insufficient heat dissipation conditions of the equipment, a series of problems are prone to occur, such as insufficient bearing force density, significantly increased control current power consumption and equipment temperature rise, and continuously decreasing suspension control margin. This further exacerbates the system's strong dependence on precision sensing links, complex control algorithms, and highly integrated hardware, which seriously limits its large-scale promotion and widespread application in the fields of miniaturization, high reliability, medium and low cost, and portable fluid machinery. Summary of the Invention

[0009] This invention aims to provide a novel magnetic levitation compressor based on a target-disc type axial magnetic levitation bearing, which can be extended to a permanent magnet electromagnetic hybrid levitation configuration. By constructing concentric annular magnetic teeth on the compressor rotor magnetic disk and cooperating with the multi-pole shoe-type electromagnetic circuit assembly at the stator end to form a magnetic focusing circuit, permanent magnets can be integrated into the stator yoke or rotor magnetic disk to construct a composite magnetic circuit with the superposition of permanent magnet bias flux and electromagnetic adjustment flux. The multi-pole shoe-type electromagnetic circuit assembly can be a U-shaped electromagnet, or two or more sets of U-shaped electromagnets connected in parallel to form an equivalent E-shaped electromagnet (or other equivalent multi-pole end magnetic circuit structure), so that the magnetic poles at the end of the electromagnet establish efficient magnetic circuit coupling with the inner and outer annular magnetic teeth of the rotor magnetic disk, thereby achieving stable non-contact levitation support of the compressor rotor with a small overall radial and axial dimensions, and rigidly connecting the magnetic disk to the compressor shaft to drive the centrifugal impeller to achieve low-friction (near-zero friction) high-speed rotation. Compared to traditional magnetic levitation compressors, which generally require radial-axial separated magnetic bearings or multiple sets of magnetic pole components and control coil combinations, and are highly dependent on high-precision multi-dimensional displacement sensing and high-bandwidth multi-channel closed-loop control, this invention simplifies the overall configuration of the compressor system from the perspective of structural topology and magnetic circuit mechanism. It improves magnetic flux utilization through permanent magnet electromagnetic hybrid design, reduces excitation power consumption and temperature rise, reduces manufacturing, assembly and subsequent maintenance costs, and enhances adaptability to miniaturized and compact fluid machinery applications. While meeting the requirements of stable rotor operation and efficient compression under high-speed centrifugal impeller load, it reduces the stringent dependence on displacement detection resolution and control bandwidth, thereby promoting the engineering realization and large-scale application of magnetic levitation compressors in the fields of low-cost, high-reliability and portable fluid machinery.

[0010] The present invention adopts the following technical solution:

[0011] A magnetic levitation compressor based on a target-disc magnetic focusing structure includes a stator assembly 1, a rotor assembly 2, a housing, a compression chamber assembly 3, and a drive motor 14. The stator assembly 1 includes a mounting plate 11 and a multi-pole shoe electromagnetic circuit assembly 12. The multi-pole shoe electromagnetic circuit assembly 12 includes a magnetic yoke 121, from which multiple pole shoes extend from one side. Several of the multi-pole shoe electromagnetic circuit assemblies 12 are evenly distributed at equal angles on the mounting plate 11. The mounting plate 11 is fixed inside the housing and has a circular hole at its center. The rotor assembly 2 includes a main shaft 21 and a rotor magnetic focusing disk 22, which are fixed as a single unit. The rotor magnetic focusing disk 22 has multiple concentric annular magnetic focusing teeth on one side, each corresponding to a pole shoe. The main shaft 21 passes vertically through the circular hole and is adapted to fit the circular hole. A centrifugal impeller 23 is connected to each of the upper and lower ends of the main shaft 21. The drive motor 14 includes a motor stator and a motor rotor; the motor rotor is fixed on the main shaft 21, and the motor stator is fixed on the inner wall of the housing; the compression chamber assembly 3 is fixedly connected to the upper and lower ends of the housing, and has two axial air inlets 32, and a pair of radial exhaust ports 33 are opened on the housing; the centrifugal impeller 23 extends into the cavity of the compression chamber assembly 3 and is aligned with the axial air inlets 32.

[0012] Preferably, the pair of radial exhaust ports 33 are spaced 180° apart; the cavity of the compression cavity assembly 3 consists of two symmetrical volute-shaped cavities 31, with flange connection holes reserved for connection with the compression cavity end cap 13; and a pressure sensor mounting thread hole is reserved on the end face of the exhaust port 33 for real-time monitoring of the cavity pressure.

[0013] Preferably, there are two rotor disks, namely an upper rotor disk and a lower rotor disk; the housing is provided with a support platform through which the main shaft 21 passes and which can prevent the lower rotor disk from falling. When the multi-pole shoe electromagnetic circuit assembly 12 of the stator assembly 1 is not powered, the support platform is used to support the rotor assembly 2.

[0014] Preferably, the multi-pole shoe-type electromagnetic circuit assembly 12 is a U-shaped electromagnet, and the corresponding rotor magnetic disk has two annular magnetic teeth, one inside and one outside.

[0015] Preferably, the multi-pole shoe-type electromagnetic circuit assembly 12 is an E-type electromagnet, and the corresponding rotor magnetic disk has three annular magnetic teeth: inner, middle, and outer.

[0016] Preferably, each of the pole shoes is further provided with a block-shaped permanent magnet; or, an annular permanent magnet is provided in the gap between adjacent annular magnetic teeth.

[0017] Preferably, each of the pole shoes is provided with a coil, and the multi-pole shoe electromagnetic circuit assembly 12 generates an upward attraction force on the rotor magnetic disk.

[0018] Preferably, a plurality of rotor aggregate disks with the same orientation are integrally fixed on the main shaft 21 of the rotor assembly 2, and each rotor aggregate disk corresponds to a different stator assembly 1.

[0019] Preferably, the rotor magnetic disk is provided with the annular magnetic teeth on both sides, and the annular magnetic teeth on both sides correspond to the stator assembly 1. The function of the stator assembly 1 located at the lower part is to balance the load size, obtain bidirectional thrust bearing capacity or improve the anti-overturning capacity.

[0020] Preferably, each pole piece of the multi-pole shoe electromagnetic circuit assembly 12 has a concave side and a convex side, and the curvature of the concave side and the convex side corresponds to the curvature of the corresponding annular magnetic tooth.

[0021] The beneficial effects of this invention are as follows:

[0022] 1) By configuring end-pole shoe-type electromagnetic circuit components on the stator assembly (the magnetic pole structure can be two-pole, three-pole, or multi-pole, and the electromagnet configuration is not limited to U-shape; multiple sets of U-shaped electromagnets can also be connected in parallel to form an equivalent E-shape or other multi-end magnetic circuit structures adapted to multi-ring magnetic teeth), permanent magnets can be integrated into the stator yoke or rotor magnetic disk, and concentric annular magnetic teeth (inner ring, outer ring, and multi-ring magnetic teeth that can be expanded as needed) that precisely match the number and distribution of the end magnetic poles can be machined on the compressor rotor magnetic disk. The magnetic tooth structure enables the magnetic poles at each end to form a "multi-end-multi-ring" magnetic focusing coupling magnetic circuit with the corresponding annular magnetic teeth. From the perspective of magnetic circuit mechanism, it promotes the excitation magnetic flux to be concentrated and closed at each annular magnetic tooth. The permanent magnet bias magnetic flux and the electromagnetic regulation magnetic flux are superimposed, which greatly improves the effective magnetic flux utilization rate and generates controllable and adjustable axial electromagnetic bearing force. Thus, under the compact radial and axial dimensions of the whole machine, stable non-contact thrust support of the compressor rotor shaft system is achieved, which is suitable for the integrated deployment requirements of miniaturized and portable fluid compression equipment.

[0023] 2) At the same time, based on the inherent characteristic of magnetic flux tending to the low-resistance path, when the compressor rotor magnetic disk is radially offset relative to the stator, the air gap distribution between each ring magnetic tooth and the end magnetic pole will show a circumferential asymmetric change. The magnetic flux will automatically bias to the path with lower equivalent magnetic resistance, thereby causing the electromagnetic force to generate a radial component, forming a radial restoring constraint force pointing towards the rotor center balance position, which passively limits the radial offset and improves the system's anti-disturbance capability. The permanent magnet bias flux can enhance the response speed and amplitude of the radial restoring constraint force. Combined with the aerodynamic centering effect generated by the high-speed rotation of the centrifugal impeller, it can further enhance the stability of the rotor when running at high speed and broaden the operating range of the compressor.

[0024] 3) Since the axial load-bearing and radial constraint functions are simultaneously achieved by the same set of "end multi-pole electromagnets - concentric multi-ring magnetic teeth" magnetic circuit, this invention can reduce or even eliminate the configuration of independent radial magnetic bearing units, or significantly reduce the number of radial control channels and the degree of freedom required while meeting the stability and load-bearing requirements of the compressor under high-speed centrifugal load. This directly brings about technical effects such as reducing the number of equipment parts, simplifying the assembly and calibration process, reducing the overall size and weight, significantly reducing manufacturing costs, and reducing the difficulty of control parameter tuning and engineering implementation. The permanent magnet-electromagnetic composite magnetic circuit design can further reduce excitation current and power consumption, and improve system energy efficiency and operational stability.

[0025] 4) In addition, the rotor disk is rigidly connected to the compressor shaft and achieves contactless support by relying on magnetic levitation technology. This can completely eliminate the mechanical friction and wear of traditional mechanical bearings, reduce the configuration requirements of the lubrication system, avoid the contamination of the compression medium by the lubricating oil, and thus improve the operating reliability and service life of the compressor under high speed and long cycle conditions. It is especially suitable for applications of small diameter shafts and miniaturized, highly integrated fluid compression machinery.

[0026] 5) Preferably, the compressor structure can be flexibly expanded into a multi-stage accumulation or bidirectional opposed configuration, with a multi-stage accumulation design ( Figure 10 It can achieve higher compression ratios and output pressures, with a bidirectional opposed configuration ( Figure 11 This can improve anti-overturning ability and bidirectional thrust bearing effect, and is compatible with various compression media such as air and refrigerant, meeting the fluid compression needs of different fields, and has strong scene adaptability and promotion value. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the magnetic levitation compressor based on a target-disc magnetic focusing structure according to the present invention.

[0028] Figure 2 This is a schematic diagram of a U-shaped electromagnet.

[0029] Figure 3 This is a schematic diagram of an E-type / multi-terminal multi-end electromagnet structure.

[0030] Figure 4 This is a schematic diagram of the rotor assembly structure.

[0031] Figure 5 The diagram shown is a schematic of the rotor-type magnetic disk.

[0032] Figure 6 This is a schematic diagram of a rotor magnetic disk with three concentric magnetic teeth.

[0033] Figure 7 This is a schematic diagram showing the relative positional relationship between the U-shaped electromagnet and the rotor disk.

[0034] Figure 8 This is a schematic diagram showing the relative positional relationship between a multi-ended electromagnet and a multi-ring magnetic disk.

[0035] Figure 9 This is a schematic diagram of a two-stage target-type magnetic levitation bearing structure.

[0036] Figure 10 This is a schematic diagram of a multi-stage target-type magnetic levitation bearing structure.

[0037] Figure 11 This is a schematic diagram showing that the rotor magnetic disk has the aforementioned annular magnetic teeth on both sides. Each of the annular magnetic teeth on both sides corresponds to a stator assembly. The lower stator assembly serves to balance the load size, obtain bidirectional thrust bearing capacity, or improve anti-overturning capability. 1 is the stator assembly, 11 is the mounting base plate, 12 is the electromagnetic assembly, 13 is the compression chamber end cap, and 14 is the permanent magnet synchronous motor.

[0038] 2 is the rotor assembly, 21 is the main shaft, 22 is the rotor disk, and 23 is the centrifugal impeller;

[0039] 3 is the compression chamber assembly, 31 is the volute-type chamber, 32 is the air inlet, 33 is the exhaust port, and 34 is the wear-resistant bushing on the inner wall of the chamber.

[0040] 121 is the yoke, and a permanent magnet can be embedded inside the yoke. 122 and 123 are coils, and 124 and 125 are pole shoes.

[0041] 121 is the yoke, into which a permanent magnet can be embedded; 122, 123, and 126 are coils; and 124, 125, and 127 are pole shoes.

[0042] 221 is the outer annular magnetic tooth, 222 is the inner annular magnetic tooth, and 223 is the middle annular magnetic tooth. The groove area between adjacent magnetic teeth can be used to embed annular permanent magnets.

[0043] 221 is an outer ring-shaped magnetic focusing tooth, and 222 is an inner ring-shaped magnetic focusing tooth.

[0044] A ring-shaped permanent magnet can be embedded in the groove area between the inner and outer annular magnetic teeth (not shown in the attached figure). Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0046] This invention provides a magnetic levitation compressor based on a target-disc type magnetic focusing structure: by machining concentric annular magnetic focusing tooth structures adapted to the stator end multi-pole electromagnetic components 12 on the upper and lower rotor magnetic focusing disks 22, and constructing a magnetic focusing coupling system with the upper and lower end electromagnets (U-shaped, equivalent E-shaped, or multi-pole structure) on the stator side, the electromagnet pole shoes and the corresponding annular magnetic focusing teeth form an efficient closed magnetic circuit. Optionally, permanent magnets can be integrated to form a permanent magnet-electromagnetic composite magnetic circuit. While simplifying the overall machine structure size, it achieves stable non-contact levitation of the rotor shaft system 21 and high-speed drive of the upper and lower centrifugal impellers 23. At the same time, relying on the low-resistance guiding characteristics of the magnetic circuit flux, when the rotor magnetic focusing disk 22 undergoes radial displacement, the air gap between the pole shoes and each annular magnetic focusing tooth is circumferentially asymmetrically distributed. The magnetic flux automatically deviates to the low-resistance path with smaller air gap, thereby generating a radial restoring constraint force pointing towards the rotor center, passively suppressing radial movement. Through the aforementioned integrated magnetic circuit design of "end-mounted multi-pole electromagnet 12—concentric multi-ring magnetic teeth," the independent radial magnetic bearing unit can be eliminated, or the radial control channel and degree of freedom configuration can be reduced, while meeting the fluid compression performance, rotor load-bearing capacity, and operational stability requirements of the double volute cavity 31. This simplifies the compressor system structure from the perspectives of structural topology and magnetic circuit mechanism, reduces manufacturing and assembly difficulty and cost, and improves adaptability to the scenario of small-diameter double impeller shafts shown in the figure. At the same time, it relaxes the stringent requirements for displacement detection resolution and control bandwidth, adapting to the development of low- to medium-cost, high-reliability portable fluid compression equipment, and facilitating engineering implementation and large-scale promotion. Specific details are as follows:

[0047] like Figure 1 As shown, the structure includes: stator assembly 1, rotor assembly 2 and compression chamber assembly 3; Figure 1 This is a schematic diagram of a magnetic levitation compressor based on a target-disc magnetic focusing structure. The assembly relationship and key mating dimensions of each component need to be determined in combination with the actual compression conditions (flow rate and pressure targets) and structural space requirements.

[0048] (a) Stator Assembly 1

[0049] The stator assembly 1 serves as the electromagnetic levitation force supply unit and the mounting reference for the entire machine. When implemented, it includes: a mounting base plate 11, several sets of multi-pole shoe-type electromagnetic circuit components 12 evenly distributed on the mounting base plate, a compression cavity end cap 13 rigidly connected to the mounting base plate, a permanent magnet synchronous motor 14 integrated into the base plate, and a heat dissipation and sealing auxiliary structure integrated into the base plate.

[0050] 1. The mounting base plate 11 is made of high-strength aluminum alloy (taking into account both structural rigidity and lightweight requirements). It can be designed as a plate or ring structure. The end face is precision ground to ensure uniform air gap. The base plate is reserved with flange connection holes for the compression cavity assembly 3. The holes are arranged circumferentially at equal intervals. At the same time, heat dissipation fins are integrally processed on the side of the base plate away from the electromagnetic components to reduce the operating temperature rise of the coil.

[0051] 2. The number of multi-pole shoe electromagnetic circuit components 12 is preferably three, distributed at 120° equiangular angles along the circumference of the mounting base plate 11. If the axial load of the compressor is large, it can be expanded to four (90° interval) or five (72° interval). The electromagnetic components adopt a U-shaped iron core structure, or two U-shaped iron cores are connected in parallel to form an equivalent E-shaped structure. Each component includes a magnetic yoke 121, an integrally formed bipolar arm, an excitation coil 122 / 123 (and optional more coils) wound around the pole arm, and pole shoes 124 / 125 (and optional more pole shoes) assembled at the end of the pole arm. A high-performance permanent magnet can be embedded inside the magnetic yoke 121 along the center line of magnetic pole symmetry. The magnetization direction is consistent with the magnetic flux direction of the excitation coil to provide a stable bias magnetic flux.

[0052] 3. The excitation coils 122 / 123 are wound with copper enameled wire and can be wound in the same or opposite directions. The two sets of coils can be connected in series to form a single winding for synchronous drive, or they can be connected independently to achieve individual control. The end faces of the pole shoes 124 / 125 are machined into a flat or partially bossed structure and coated with an epoxy resin insulating and wear-resistant coating. Figure 2 This is a schematic diagram of the U-shaped end electromagnet structure; Figure 3 This is a schematic diagram of an E-type / multi-terminal multi-end electromagnet structure.

[0053] 4. The compression chamber end cover 13 and the mounting base plate 11 are fastened together with bolts, and a nitrile rubber sealing ring is installed at the connection. The diameter of the central through hole of the end cover is 5-8mm larger than the outer diameter of the rotor shaft, and a labyrinth-type non-contact seal is embedded in the inner wall of the through hole.

[0054] 5. The permanent magnet synchronous motor 14 is rigidly integrated with the mounting base plate 11 and the compression chamber end cover 13: the stator core is made of laminated silicon steel sheets and assembled through the positioning stop of the mounting base plate 11, with a coaxiality tolerance ≤0.02mm, ensuring smooth transmission of driving force; the stator winding uses high-temperature resistant enameled wire, and the ends are potted with epoxy resin to achieve insulation and shock resistance. The stator shell of the permanent magnet synchronous motor 14 is connected to the heat dissipation fins of the mounting base plate 11, and the side wall is reserved with cooling interfaces suitable for air cooling / liquid cooling; the air gap between the stator and rotor is set to 0.5-1mm, and a non-metallic isolation bushing is built-in to prevent contact wear. The winding leads are led out through the pre-set wire holes on the mounting base plate 11, and the holes are sealed with glass fiber plugs for insulation and dust prevention; the motor stator and the multi-pole shoe-type electromagnetic circuit assembly 12 are coaxial, ensuring coordination between levitation and driving action. Figure 1 The motor stator is fixed inside the housing by circumferentially arranged bolts or welding, which does not affect the gas flow.

[0055] (ii) Rotor assembly 2

[0056] The rotor assembly 2 is used to bear the levitation force, output high-speed rotational motion and drive fluid compression. In practice, it includes: a rotating shaft 21, a rotor disk 22 fixed to the shaft, and a centrifugal impeller 23 fixed to the end of the shaft. It must meet the high-speed dynamic balance accuracy requirements. Figure 4 This is a schematic diagram of the rotor assembly 2.

[0057] 1. The rotating shaft 21 and the rotor disk 22 can be manufactured by integral machining process, or they can be rigidly connected by welding, key connection, interference fit, bolt fastening, etc., to ensure reliable transmission of force and torque, while strictly ensuring the coaxiality accuracy of the two.

[0058] 2. The rotor magnetic disk 22 has a concentric annular magnetic tooth structure for forming magnetic focusing coupling with the multi-pole shoe electromagnetic circuit assembly 12. Taking the end electromagnet with a two-pole structure of two pole shoes as an example, the magnetic disk 22 includes an outer annular magnetic tooth 221 located on the radially outer side and an inner annular magnetic tooth 222 located on the radially inner side; the outer annular magnetic tooth 221 and the inner annular magnetic tooth 222 are arranged in a stepped tooth surface along the axial direction, which can be precisely aligned with the corresponding pole shoes of the multi-pole shoe electromagnetic circuit assembly 12 to form a preset air gap. A ring-shaped permanent magnet (not shown in the figure) can be embedded in the non-magnetic tooth area of ​​the magnetic disk, and the magnetization direction is arranged along the axial direction, superimposed with the magnetic flux of the stator electromagnet in the same direction. Figure 5 The diagram shown is a schematic diagram of the structure of the two-ring rotor disk 22.

[0059] 3. The outer annular magnetic focusing tooth 221 and the inner annular magnetic focusing tooth 222 can be designed as a continuous annular flange, annular step, annular groove-tooth fit configuration or other equivalent annular magnetic flux focusing structure. Their cross-sectional shape is not limited to rectangle, and trapezoidal, rounded corner or chamfered style can also be selected to improve the consistency of assembly gap and optimize the magnetic flux distribution effect.

[0060] In other embodiments, if the multi-pole shoe type electromagnetic circuit assembly 12 adopts a three-pole or multi-pole structure, the rotor magnetic disk 22 is correspondingly configured with three-ring or multi-ring concentric magnetic teeth, so that the number of end magnetic poles / pole shoes and the number of magnetic tooth rings are matched one-to-one, thereby forming a "multi-end-multi-ring" magnetic focusing coupling mode. Figure 6 The diagram shows a rotor magnetic disk structure with three concentric magnetic teeth.

[0061] 4. The centrifugal impeller 23 can be designed as a single-suction, double-suction, closed, or equivalent high-efficiency aerodynamic configuration. Its blade profile is not limited to the backward-curved blade style. Radial blades, forward-curved blades, or variable cross-section twisted blades can also be selected to improve fluid compression efficiency and broaden the operating condition adaptability range of the compressor.

[0062] (III) Compression Chamber Assembly 3

[0063] The compression chamber assembly 3 is used to constrain fluid flow and realize the conversion of kinetic energy to pressure energy. When implemented, it includes: a volute-shaped chamber 31, an inlet and outlet port 32 / 33, and a wear-resistant bushing 34 on the inner wall of the chamber. The flow channel profile must be matched with the aerodynamic characteristics of the impeller.

[0064] 1. The volute-type cavity 31 adopts a symmetrical double volute structure design. The inner wall of the cavity is precision polished to ensure smooth fluid flow. The cavity is reserved with flange connection holes for the end cover 13 of the compression cavity. The holes are evenly distributed along the circumferential direction of the cavity end face. At the same time, reinforcing ribs are integrally processed on the outer wall of the cavity to improve the pressure resistance of the cavity and reduce deformation under high pressure conditions.

[0065] 2. The air inlet 32 ​​adopts an axial air intake form, and the exhaust port 33 adopts a radial exhaust form; the air inlet specifications match the compressor's rated flow rate, and the exhaust port is adapted to the nominal diameter of the downstream pipeline. Both are connected by flanges and equipped with metal spiral wound gaskets to enhance the seal; a pressure sensor mounting thread hole is reserved on the end face of the exhaust port for real-time monitoring of the cavity pressure.

[0066] 3. The wear-resistant bushing 34 is embedded in the impeller corresponding area of ​​the volute cavity 31 by interference fit; the fit clearance between the inner wall of the bushing and the centrifugal impeller 23 is controlled at 1-2mm, which not only ensures the compression efficiency, but also avoids hard contact damage between the impeller and the cavity when the suspension is abnormal.

[0067] (iv) Relative positional relationship of each assembly

[0068] The relative positional accuracy of each assembly directly determines the magnetic circuit coupling efficiency, suspension stability and fluid compression performance. During implementation, precise control is required for dimensions such as magnetic pole-magnetic tooth alignment, stator-rotor coaxiality, multi-level structural spacing, and bidirectional parallelism.

[0069] 1. Air gap alignment control between magnetic poles and concentrating teeth

[0070] During the assembly stage, precision tooling fixtures are needed to position the stator assembly 1 and rotor assembly 2, ensuring that the pole shoes of each multi-pole-shoe type electromagnetic circuit component 12 are aligned one-to-one with the corresponding annular magnetic teeth of the rotor magnetic disk 22. Taking the two-pole-shoe-two-ring magnetic tooth configuration as an example, the design values ​​of the outer and inner air gaps must be consistent, and the circumferential air gap deviation must be controlled within 0.05mm, which can be calibrated by multi-point circumferential measurement using a dial indicator. For the multi-pole-shoe-multi-ring magnetic tooth configuration, the axial alignment of each stage of pole shoe with the corresponding magnetic tooth must be ensured to avoid magnetic flux leakage due to misalignment, which would affect the magnetic focusing effect. After the above alignment operation is completed, the relative positions of the stator assembly and the compression chamber assembly must be locked with locating pins to prevent displacement caused by operating vibration. Figure 7 This is a schematic diagram showing the relative positional relationship between the two ends and the two rings; Figure 8 This is a schematic diagram showing the relative positional relationship between a multi-terminal electromagnet and a multi-ring magnetic disk.

[0071] 2. Stator-rotor coaxiality control

[0072] The end face of the mounting plate 11 of the stator assembly 1 must be strictly perpendicular to the axis of rotation of the rotor assembly 2, with a perpendicularity error ≤0.02mm. The coaxiality of the stator assembly and the rotor assembly must be detected by a laser alignment instrument, and the radial deviation must be controlled within 0.03mm. Excessive coaxiality will lead to uneven circumferential distribution of the air gap, exacerbating radial vibration during rotor rotation. Therefore, an unloaded suspension test must be performed after assembly, and the coaxiality must be verified by displacement sensor data. Figure 9 This illustrates a two-stage target-type magnetic levitation bearing structure. Figure 10 The multi-stage target-type magnetic levitation bearing structure is shown.

[0073] 3. Spacing and coaxiality control of multi-level cumulative structures

[0074] When using a two- or multi-stage rotor impeller 22 extension structure, the axial spacing of each impeller stage needs to be determined according to the load distribution requirements, with a spacing deviation ≤ 0.1mm. Each stage stator assembly 1 needs to be coaxially arranged with the corresponding rotor impeller, and the coaxiality consistency deviation of each stator assembly needs to be ≤ 0.05mm. Precise positioning can be achieved through positioning holes in the stator base plates of each stage using a long guide shaft. At the same time, it is necessary to ensure that the axial spacing of adjacent centrifugal impellers matches the flow channel design of the compression chamber to avoid airflow disturbance caused by spacing deviation, which would reduce the multi-stage compression efficiency. Figure 11 This is a schematic diagram of a bidirectional target-type magnetic levitation bearing.

[0075] 4. Parallelism control of bidirectional thrust structures

[0076] When using an upper and lower opposed stator assembly structure, the mounting base end faces of the upper and lower stator assemblies must be parallel, with a parallelism error ≤0.03mm; the pole shoes of the upper and lower stator assemblies must be precisely aligned with the magnetic teeth on the upper and lower end faces of the rotor magnetic disk, and the bidirectional air gap must be symmetrical, with a deviation ≤0.04mm. Excessive parallelism and air gap symmetry will lead to bidirectional thrust imbalance, causing rotor axial tilting. Therefore, after assembly, calibration is required using bidirectional displacement detection data from the suspension controller.

[0077] 5. Impeller-cavity clearance control

[0078] The outer diameter of the upper and lower centrifugal impellers 23 must be within 1-2 mm of the inner diameter of the wear-resistant bushing 33 in the corresponding compression chamber assembly 3. The axial clearance between the end face of each impeller and the end cover 13 of the corresponding compression chamber must be 2-3 mm. This clearance must be greater than the maximum suspension displacement stroke of the rotor to prevent hard contact between the impeller and the volute-type cavity 31 or the end cover 13 of the compression chamber in case of malfunction in the suspension control system. During assembly, the radial and axial clearance values ​​of the upper and lower impellers can be measured with a feeler gauge to ensure compliance with design requirements.

[0079] (v) Implementation and configuration of the control and drive system

[0080] The control and drive system is used to achieve suspension stability control and compression condition adjustment. When implemented, it includes: displacement detection unit, current detection unit, power drive module, main controller, pressure detection unit, and speed detection unit. Each module is integrated into an independent control box for easy installation and maintenance.

[0081] 1. The displacement detection unit adopts an eddy current displacement sensor. The probe is integrated into the reserved hole of the mounting base plate, aligned with the edge of the rotor disk, and collects axial displacement and suspension gap data in real time. If necessary, 3-4 probes are arranged, and the rotor tilt attitude is determined by data fusion.

[0082] 2. The current detection unit uses a Hall current sensor connected in series in the coil circuit to monitor the excitation current and feed it back to the main controller to realize overcurrent protection and current closed-loop regulation.

[0083] 3. The pressure detection unit uses a diffused silicon pressure sensor, which is installed in the reserved hole of the exhaust port; the speed detection unit uses a non-contact Hall sensor, which obtains speed data by detecting the magnetic signal on the shaft.

[0084] 4. The main controller uses a DSP chip and runs a PID or sliding mode control algorithm to generate control commands based on displacement, current, pressure, and speed signals; the power drive module uses an IGBT module to adjust the coil excitation current; the drive motor is integrated into the stator assembly.

[0085] (vi) Implementation process of complete machine assembly and operation

[0086] 1. Assembly process: First, fix the upper and lower sets of multi-pole shoe electromagnetic circuit components 12 to the corresponding mounting base plates 11. If it is a stator-side permanent magnet integrated scheme, the permanent magnet needs to be embedded into the magnetic yoke in advance and magnetized and fixed. The alignment position of the pole shoe and the magnetic tooth is calibrated. Then, assemble and fix the upper and lower rotor magnetic disks 22 and the rotating shaft 21. If it is a rotor-side permanent magnet integrated scheme, the permanent magnet needs to be embedded into the magnetic disk and the dynamic balance correction is completed. The dynamic balance correction of the entire shaft system is then completed. Subsequently, align and install the rotor assembly and the stator assembly (including the integrated permanent magnet synchronous motor 14), and adjust the axial suspension air gap to the design value. Finally, assemble the upper and lower double volute structure compression chamber assembly 3 and the control box, and connect the pipe interfaces of each electrical interface and the air inlet 32 ​​and exhaust port 33.

[0087] 2. Workflow: After the equipment is started, the main controller drives the power module to energize the coils of the upper and lower multi-pole shoe-type electromagnetic circuit components 12. The bias magnetic flux provided by the permanent magnet is superimposed with the electromagnetic flux of the coil to generate an axial levitation force, which makes the rotor shaft system levitate without contact. The displacement sensor provides real-time feedback on the gap data of the upper and lower magnetic disks 22, and the controller dynamically adjusts the excitation current to maintain levitation stability. At the same time, the drive motor 14 drives the rotor to rotate at high speed. The upper and lower centrifugal impellers 23 synchronously accelerate and pressurize the fluid drawn in by the axial air inlet 32, which is then collected through the double volute flow channel 31 and output from the radial exhaust port 33. The main controller dynamically adjusts the speed of the motor 14 according to the exhaust pressure signal to adapt to the changing working conditions. If the rotor is radially offset, it automatically generates a radial restoring constraint force through magnetic flux offset, which, together with the aerodynamic centering effect of the double impellers, suppresses vibration and ensures stable operation of the whole machine.

[0088] This invention addresses the technical bottlenecks of existing magnetic levitation compressors, including a large number of bearing actuators, complex magnetic circuit topology, difficulty in compressing structural dimensions, high dependence on high-precision sensing and multi-channel control, and high assembly and debugging thresholds. It achieves this through an innovative configuration integrating a target-disc type axial magnetic levitation bearing with fluid compression functionality. Relying on the precise coupling design of the multi-pole electromagnet at the stator end and the concentric annular magnetic teeth of the rotor's magnetic disk, it optionally integrates permanent magnets to construct a permanent magnet-electromagnetic composite magnetic circuit, building a "single magnetic circuit, dual function" support system. This systematically overcomes the shortcomings of existing technologies from the perspectives of structural topology and magnetic circuit mechanism, achieving the technical effects of simplified system configuration, reduced implementation costs, and improved miniaturization adaptability. The specific implementation path is as follows:

[0089] This invention processes inner and outer concentric annular magnetic tooth structures on the compressor rotor magnetic disk, and makes the end pole shoes of the stator end electromagnets (which can be U-shaped electromagnets, or equivalent E-shaped electromagnets composed of two or more U-shaped electromagnets connected in parallel, or other equivalent multi-end magnetic circuit structures) form double air gap magnetic focusing coupling with the inner and outer annular teeth of the magnetic disk, respectively. This allows the excitation flux to be concentrated and closed at the inner and outer annular magnetic teeth, achieving controllable and stable axial electromagnetic bearing force with relatively compact radial and axial dimensions, realizing non-contact suspension support of the compressor rotor shaft system. At the same time, the integrated configuration of the centrifugal impeller and the compression chamber eliminates the need for independent arrangement of radial and axial bearings in traditional solutions, significantly reducing the overall volume of the machine and reducing the dependence on complex magnetic pole configurations and ultra-high precision assembly processes.

[0090] Meanwhile, based on the inherent characteristic of magnetic flux tending towards the low-resistance path, when the compressor rotor is radially offset relative to the stator, the air gap distribution between the inner and outer ring magnetic teeth and the electromagnet pole shoes will undergo circumferential asymmetric changes. The magnetic flux will automatically deflect towards the air gap region with lower equivalent magnetic resistance, thereby causing the electromagnetic force to generate a radial component, forming a restoring constraint force pointing towards the rotor's center equilibrium position, thus passively limiting the radial offset. Combined with the aerodynamic centering effect generated by the high-speed rotation of the centrifugal impeller, the anti-disturbance stability of the rotor during high-speed operation can be further improved.

[0091] Since the axial load and radial constraint functions are generated synchronously by the same set of "end electromagnets - inner and outer ring magnetic teeth" magnetic circuit, this technical solution does not require additional independent radial electromagnetic bearing units. It can also significantly reduce the number of radial control channels and the control degree of freedom requirements, simplifying the "sensing-drive-control" link design from the structural source and breaking through the strong dependence of existing technologies on high-precision multidimensional displacement sensors and high-bandwidth multi-channel controllers.

[0092] In summary, this invention effectively overcomes the shortcomings of traditional magnetic levitation compressors, such as redundant bearing actuators, complex magnetic circuits, bulky structures, cumbersome control links, and high manufacturing costs, through magnetic circuit integration design and functional reuse. Ultimately, it achieves the technical effects of reducing overall system complexity, shrinking the overall size of the machine, lowering the manufacturing and assembly threshold, and improving miniaturization adaptability. It is suitable for the application needs of portable and low- to medium-cost fluid compression equipment, and promotes the engineering implementation of magnetic levitation compressors in a wider range of scenarios.

[0093] The above are preferred embodiments of the present invention. Those skilled in the art can make various modifications or improvements based on these embodiments. Without departing from the overall concept of the present invention, such modifications or improvements should fall within the scope of protection claimed by the present invention.

Claims

1. A magnetic levitation compressor based on a target-disc type magnetic focusing structure, characterized in that: Includes stator assembly (1), rotor assembly (2), housing, compression chamber assembly (3), and drive motor (14); The stator assembly (1) includes a mounting plate (11) and a multi-terminal pole shoe electromagnetic circuit assembly (12). The multi-pole-shoe type electromagnetic circuit assembly (12) includes a magnetic yoke (121), from which multiple pole shoes are led out from one side; several of the multi-pole-shoe type electromagnetic circuit assemblies (12) are evenly distributed on the mounting plate (11) at equal angles; the mounting plate (11) is fixed inside the housing, and a circular hole is provided in its center; The rotor assembly (2) includes a main shaft (21) and a rotor magnetic disk (22), which are fixed together. The rotor magnetic disk (22) has multiple concentric annular magnetic teeth on one side, which are aligned with the pole shoes one by one. The main shaft (21) passes vertically through the circular hole and is adapted to the circular hole. A centrifugal impeller (23) is connected to each of the upper and lower ends of the main shaft (21). The drive motor (14) includes a motor stator and a motor rotor; the motor rotor is fixed on the main shaft (21), and the motor stator is fixed on the inner wall of the housing; The compression chamber assembly (3) is fixedly connected to the upper and lower ends of the housing and has two axial air inlets (32). A pair of radial exhaust ports (33) are opened on the housing. The centrifugal impeller (23) extends into the cavity of the compression chamber assembly (3) and is aligned with the axial air inlets (32).

2. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: The pair of radial exhaust ports (33) are 180° apart; the cavity of the compression cavity assembly (3) consists of two symmetrical volute-shaped cavities (31) on the upper and lower sides, and the volute-shaped cavity (31) is reserved with a flange connection hole for connection with the end cover (13) of the compression cavity; the end face of the exhaust port (33) is reserved with a pressure sensor mounting thread hole for real-time monitoring of the cavity pressure.

3. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: The rotor aggregate disk has two parts, namely the upper rotor aggregate disk and the lower rotor aggregate disk; the housing is provided with a support platform through which the main shaft (21) passes and which can prevent the lower rotor aggregate disk from falling. When the multi-pole shoe electromagnetic circuit assembly (12) of the stator assembly (1) is not powered, the support platform is used to support the rotor assembly (2).

4. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: The multi-pole shoe-type electromagnetic circuit assembly (12) is a U-shaped electromagnet, and the corresponding rotor magnetic disk has two inner and outer annular magnetic teeth.

5. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: The multi-pole shoe-type electromagnetic circuit assembly (12) is an E-type electromagnet, and the corresponding rotor magnetic disk has three annular magnetic teeth: inner, middle, and outer.

6. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: Each of the pole shoes is also fixedly provided with a block-shaped permanent magnet; or, an annular permanent magnet is provided in the gap between adjacent annular magnetic teeth.

7. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: Each of the pole shoes is provided with a coil, and the multi-pole shoe electromagnetic circuit assembly (12) generates an upward attraction on the rotor disk.

8. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: Multiple rotor disks with the same orientation are integrally fixed on the main shaft (21) of the rotor assembly (2), and each rotor disk corresponds to a different stator assembly (1).

9. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: The rotor magnetic disk is provided with the annular magnetic teeth on both sides. The annular magnetic teeth on both sides correspond to the stator assembly (1). The function of the stator assembly (1) located at the bottom is to balance the load size, obtain bidirectional thrust bearing capacity or improve the anti-overturning capacity.

10. The magnetic levitation compressor based on a target-disc type magnetic focusing structure as described in claim 1, characterized in that: Each pole shoe of the multi-pole shoe electromagnetic circuit assembly (12) has a concave side and a convex side, and the curvature of the concave side and the convex side corresponds to the curvature of the corresponding annular magnetic tooth.

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