## 2 Structural Design of Modular Multi-Unit Cell Permanent Magnet Thrust Bearing  
### General Design  
Conventional permanent magnet thrust bearings typically use permanent magnet rings or permanent magnets directly embedded into the main bearing structure. While this design approach is simple and involves fewer parts, it has certain limitations. Due to the large size of the permanent magnet ring, assembly becomes challenging. Furthermore, in the event of magnet damage, the lack of isolation between the permanent magnets can lead to secondary damage to the bearing structure, resulting in the need to scrap the entire bearing, as illustrated in Figure 2. In normal conditions, magnet replacement is also extremely difficult, requiring complete disassembly of the entire bearing. This significantly limits the practical engineering applications of permanent magnet thrust bearings. In addition to the poor generalization and maintainability of such bearings, another major issue restricting their broader use is their low load-carrying capacity. Conventional permanent magnet thrust bearings often adopt a two-layer nested structure, with the rotor's permanent magnets in the inner layer and the stator's permanent magnets in the outer layer, as shown in Figure 3. While this structure has the advantage of a simpler design, its two-layer nested configuration, featuring two layers of permanent magnets alongside a single working surface, limits the efficient use of the magnets' magnetic force. As a result, the load-carrying capacity is relatively modest. Therefore, it is primarily suitable for low load-bearing applications, such as in high-precision instruments, where a high load capacity is not essential. Figure 2: Broken permanent magnet thrust bearing. To improve the adaptability of permanent magnet thrust bearings in various scenarios and enhance the versatility of the bearing structure, a new approach is proposed. This design is based on the concept of bionics and references the honeycomb structure. By adopting the modular concept and utilizing a multi-unit cell combination approach, where each unit cell is composed of four permanent magnets, and referring to the basic structure of the permanent magnet thrust bearing, the original method of directly embedding permanent magnets or permanent magnet rings into the structure is changed to one involving the connection of multiple unit cells. The number and arrangement of these unit cells can be adjusted to achieve various nested and cross configurations. This flexibility allows for the design of modular, multi-unit cell permanent magnet thrust bearings. One such example is the four-layer nested four-pole crossover bearing design, as shown in Figure 4. In operation, the magnetic force of the permanent magnets allows the rotor and stator to levitate without direct contact. When axial forces are applied, the bearing rotor experiences a slight axial displacement. The attraction and repulsion forces of the permanent magnets maintain stable levitation, ensuring smooth operation without friction. This design improves the load-carrying capacity and enhances the adaptability of the thrust bearing across a wide range of applications. The modular multi-unit cell permanent magnet thrust bearing consists of a rotor and stator housing, rotor and stator chokes, and multiple unit cells. The rotor and stator housings feature a disk-type design, while the rotor and stator chokes are bolted to these housings. These circular chokes contain multiple square openings to accommodate the unit cells, which are bolted to the chokes. Shock-absorbing rubber cushions are employed to reduce vibrations. When the size and load-carrying capacity of the bearing have different requirements, the size of the bearing housings and chokes can be changed, which in turn alters the number and arrangement of the unit cells.