Integrated permanent magnet synchronous two-stage compression screw air compressor

Abstract

The invention relates to the technical field of air compressors, and discloses an integrated permanent magnet synchronous two-stage compression screw air compressor which comprises a second-stage screw structure, a flange block, a first-stage screw structure and a permanent magnet synchronous motor. Gas compressed by the first-stage screw structure enters the second-stage screw structure from a gas flow channel in the flange block to be secondarily compressed, grooves used for arranging sealing rings are formed in the contact faces, connected with the second-stage screw structure and the first-stage screw structure, of the flange block, and a pressurization sealing groove and a magnetic fluid sealing groove are sequentially formed outwards from the center cavity. A sealing ring arranged in the pressurization sealing groove is of a bag structure, one side of the sealing ring can make contact with high-pressure gas in the flange block, a sealing ring arranged in the magnetic fluid sealing groove is of a bag structure, magnetic powder capable of flowing is arranged in a sealing bag, and when the permanent magnet synchronous motor works and magnetic force is conducted to the flange block along the shaft body, the magnetic powder forms a chain, and the magnetic powder is separated from the flange block. And the side wall in the magnetofluid sealing groove is tightly attached.

Description

Technical Field

[0001] This invention relates to the field of air compressor technology, specifically to an integrated permanent magnet synchronous two-stage compression screw air compressor. Background Technology

[0002] The two-stage screw air compressor is a highly efficient and energy-saving air compression device. Its core design lies in dividing the compression process into two stages. Air first enters the low-pressure stage screw compressor, is compressed to an intermediate pressure, and then, instead of being discharged directly, enters an intercooler for thorough cooling. The cooled, low-temperature air then enters the high-pressure stage screw compressor for a second compression, ultimately reaching the required higher operating pressure. This stepped "compression-cooling-recompression" design significantly reduces the compression ratio and temperature rise of each compression stage. Its core advantage lies in a substantial improvement in energy efficiency, because the cooled air has a higher density and smaller volume, significantly reducing the power consumption of the second-stage compression. Overall energy consumption can be reduced by approximately 10-15% compared to a single-stage screw compressor. Simultaneously, the two-stage compression balances the bearing load and lowers the exhaust temperature, reducing the risk of lubricant aging and extending the service life of the compressor and key components, making the entire machine more reliable and stable in operation. It is particularly suitable for industrial sectors requiring medium-to-high pressure, a continuous and stable air supply, and where long-term operating costs are a concern, making it an ideal choice for energy-saving renovations and air compressor station upgrades in modern industrial enterprises.

[0003] A common structure for a two-stage screw air compressor is shown in patent number CN119532199A. It connects two screw compression structures to each other through a flange connecting block, allowing airflow to flow from the first-stage screw compression structure to the second-stage screw compression structure. This connection structure allows high-pressure gas to be introduced into the flange block used for connection, greatly increasing the difficulty of sealing. At the same time, due to the limitations of the connection structure, the maintenance process of the flange block is extremely troublesome. Therefore, it is necessary to ensure the sealing strength of the sealing structure while reducing its probability of damage. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an integrated permanent magnet synchronous two-stage compression screw air compressor, which has the advantage of enhanced sealing and solves the problem of sealing the connection passage.

[0005] (II) Technical Solution To achieve the aforementioned enhanced sealing objective, this invention provides the following technical solution: an integrated permanent magnet synchronous two-stage compression screw air compressor, comprising a housing and a compression structure disposed therein. The compression structure includes a two-stage screw structure, a flange block, a first-stage screw structure, and a permanent magnet synchronous motor. Each of the two-stage and first-stage screw structures has a pair of meshing male and female rotors. The first-stage and second-stage screw structures are horizontally connected via the flange block, which has a passage for gas flow. Gas compressed by the first-stage screw structure enters the second-stage compressor through the gas flow passage in the flange block. The primary screw structure performs secondary compression. The contact surface between the flange block and the secondary and primary screw structures is provided with grooves for setting sealing rings. From the central cavity outwards, there are sequentially arranged pressure sealing grooves and magnetic fluid sealing grooves. The sealing ring set in the pressure sealing groove is a bladder structure, and one side can contact the high-pressure gas in the flange block. The sealing ring set in the magnetic fluid sealing groove is a bladder structure, and the sealing bladder contains flowable magnetic powder. When the permanent magnet synchronous motor works, when the magnetic force is transmitted to the flange block along the shaft, the magnetic powder forms chains and adheres tightly to the side wall in the magnetic fluid sealing groove.

[0006] In the first-stage screw structure, one end of the male rotor is connected to and driven by a permanent magnet synchronous motor, while the other end is equipped with a gear that meshes with the gear at the end of the male rotor in the second-stage screw structure within the flange block.

[0007] The flange block and the cavity connected to the secondary screw structure and the primary screw structure are generally rectangular with rounded corners, and the pressure sealing groove and the magnetic fluid sealing groove are matched with the shape of the cavity.

[0008] The bottom of the pressurized sealing groove is provided with a pressurized channel. The pressurized channel is slotted, with one end connected to the pressurized sealing groove and the other end located on the side wall of the flange block cavity opening. The pressurized channels are arranged in a spaced array along the side wall of the flange block.

[0009] The pressure sealing groove is provided with at least two, and the adjacent pressure sealing grooves have different depths, with the grooves further away from the center of the flange block being deeper.

[0010] A self-compensating sealing groove with a matching shape is provided between the pressurized sealing groove and the magnetic fluid sealing groove. The sealing ring in the self-compensating sealing groove has a metal ring that can be magnetically attracted. The shape of the metal ring matches the self-compensating sealing groove, and there are two of them. They respectively contact the wall surface near the magnetic fluid sealing groove and the wall surface of the pressurized sealing groove. The sealing ring completely covers the metal ring.

[0011] The magnetic fluid sealing groove is segmented, consisting of a rounded corner groove and a right-angle groove.

[0012] The capsule in the magnetic fluid sealing groove is a flexible sealing capsule filled with magnetic powder and liquid fluid.

[0013] The filling medium of the bladder in the magnetic fluid sealing groove is nano carbonyl iron powder magnetic powder and synthetic hydrocarbon carrier liquid, as well as stabilizer and defoamer.

[0014] (III) Beneficial Effects Compared with the prior art, the present invention provides an integrated permanent magnet synchronous two-stage compression screw air compressor, which has the following beneficial effects: 1. This integrated permanent magnet synchronous two-stage compression screw air compressor, when started by the permanent magnet synchronous motor, instantly activates the intelligent sealing bladder within the magnetic fluid sealing groove of the flange block through the magnetic field transmitted by the shaft system. This causes the magnetic particles inside to align, chain, and cross-link along the magnetic lines of force, forming a dense, rigid network. This transforms the sealing medium from a low-viscosity fluid into a high-strength semi-solid, essentially constructing a reinforced concrete wall on the sealing surface that is instantly generated by the magnetic field. The sealing pressure is automatically established and matched with the system pressure, achieving perfect synchronization of "motor rotation, seal tightening," ensuring efficient and zero-leakage transmission of compressed gas between the two stages. Simultaneously, the traditional pressure sealing groove also utilizes the gas pressure after the first stage compression to deform the bladder structure, further tightening the contact surface and forming a double dynamic sealing guarantee. When the motor stops, the magnetic field disappears, and the magnetic powder network inside the magnetofluid sealing bladder immediately disintegrates, returning to a flexible fluid state. The sealing pressure is automatically relieved, which avoids unnecessary long-term static stress on the seal during non-working periods, greatly reducing material fatigue and permanent deformation, and significantly extending the service life of the sealing system and even the entire connection interface. First, it achieves near-zero leakage interstage sealing, ensuring that each stage of compression operates under design conditions, maximizing the overall efficiency of the two-stage compression and reducing energy consumption. Second, the adaptive characteristics of the sealing system reduce the extreme demands on machining precision and assembly, improving production stability and fault tolerance. Third, the reduction in seal wear directly extends the maintenance cycle of core components, reducing the maintenance cost over the entire life cycle. Finally, the combination of the high efficiency of the permanent magnet synchronous motor and intelligent sealing makes the whole machine run more smoothly and quietly, and reduces energy loss and potential oil mist pollution caused by leakage at the source, reflecting a higher level of environmental protection and energy saving.

[0015] 2. This integrated permanent magnet synchronous two-stage compression screw air compressor utilizes an array of pressurized channels at the bottom of the pressurized sealing groove. This allows high-pressure gas from the compression chamber to be directly and rapidly guided to the sealing chamber, achieving instantaneous and precise matching and dynamic balance between the sealing pressure and the system operating pressure. This transforms the sealing behavior from a static obstruction into an active response element in the system pressure cycle. The multi-layered pressurized sealing groove design of varying depths creates a gradient sealing barrier. As gas penetrates each layer, the pressure is gradually attenuated. This not only significantly improves the absolute reliability of the seal, providing multiple layers of protection, but more importantly, this design significantly reduces the stringent requirements on individual sealing elements, improving the system's fault tolerance and adaptability to minor assembly errors or wear. In terms of drive and structure, the direct drive of the secondary male rotor by the end gear of the primary male rotor eliminates the need for complex independent drives or long shaft systems. The extremely short transmission path and exceptionally compact structure greatly reduce potential vibration sources and energy loss points, improving transmission efficiency and overall rigidity. The matching rounded rectangular cavity and the perfectly matched sealing groove maximize the utilization of internal space, ensuring a smooth transition of the gas flow channel and reducing turbulence and pressure loss. Simultaneously, this circumferentially fitted sealing groove layout provides uniform support and constraint for the sealing capsule, avoiding localized stress concentration and resulting in a more balanced sealing pressure distribution. Particularly ingenious is the segmented design of the magnetorheological sealing groove (rounded corner and right-angle sections). This design significantly reduces the difficulty and cost of molding complex-shaped flexible capsules, enabling standardized and mass production of high-performance intelligent sealing components, making commercialization feasible. Secondly, the segmented design allows for more flexible adaptation to the magnetic field strength and mechanical stress characteristics of different areas. For example, different magnetic powder formulations or capsule wall thicknesses can be used at right-angle transitions, thereby optimizing local performance and ensuring a consistent and reliable magnetorheological sealing effect throughout the entire irregular sealing circumference.

[0016] 3. This integrated permanent magnet synchronous two-stage compression screw air compressor uses a self-compensating sealing groove as an independent intermediate sealing barrier between the pressurizing sealing groove and the magnetohydrodynamic sealing groove. This further refines the pressure gradient, making the pressure transition from the first-stage compression chamber to the second-stage compression chamber smoother and more controllable. This effectively dampens the impact that air pressure pulsations may cause on the sealing interface. Secondly, the metal ring embedded inside is attracted by the magnetic field conducted by the shaft system when the permanent magnet synchronous motor is running, generating an inward pre-tightening force. This magnetic attraction achieves a dual key function: firstly, when the motor starts and the air pressure has not yet fully established, the magnetic force first tightens the metal ring, causing the sealing ring to generate initial clamping force, achieving zero-pressure start-up sealing and perfectly filling the gap period for dynamic seal establishment; secondly, during long-term operation, if the clamping force of the pressurizing sealing bladder tends to decrease due to material relaxation or slight wear, the constant attraction of the magnetic force on the metal ring can automatically and continuously compensate for this loss, maintaining the stability of the sealing specific pressure at the interface, truly achieving self-compensation. Furthermore, the structure itself has extremely strong robustness and failure safety. Even in extreme cases where the front-end pressure seal unexpectedly weakens, the metal-ring-reinforced sealing ring itself provides a strong mechanical seal. Furthermore, the activation effect of the magnetic field makes it an active safety barrier that can be maintained solely by motor operation, independent of air pressure. From a manufacturing and system perspective, this design enhances the overall rigidity and shape retention of the sealing ring assembly through the built-in metal ring, reducing the risk of the sealing ring being squeezed into gaps or twisted under complex operating conditions, ensuring a uniform distribution of sealing pressure. It also effectively reduces over-reliance on the instantaneous response speed and absolute pressure of the front-end pressure seal, allowing for greater system design tolerance and smoother operation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the internal structure of the device housing of the present invention; Figure 2 This is a schematic diagram of the compression structure of the present invention; Figure 3 This is a schematic diagram of the flange block structure of the present invention; Figure 4 This is a schematic diagram of the pressure sealing groove structure of the present invention; Figure 5 This is a partial cross-sectional view of the flange block of the present invention.

[0018] In the diagram: 1. Compression structure; 2. Flange block; 21. Pressure sealing groove; 22. Self-compensating sealing groove; 23. Magnetorheological fluid sealing groove; 101. Equipment housing; 102. Secondary screw structure; 103. Primary screw structure; 104. Permanent magnet synchronous motor; 211. Pressure sealing ring; 212. Pressure channel; 221. Metal ring; 231. Magnetic powder fluid. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figures 1-5 An integrated permanent magnet synchronous two-stage screw air compressor includes a housing 101 and a compression structure 1 housed within it. The compression structure 1 includes a secondary screw structure 102, a flange block 2, a primary screw structure 103, and a permanent magnet synchronous motor 104. Each of the secondary screw structure 102 and the primary screw structure 103 has a pair of meshing male and female rotors. The internal rotor compression structure is consistent with existing screw air compressor structures and will not be described in detail here. The primary screw structure 103 and the secondary screw structure 102 are horizontally connected via the flange block 2. The flange block 2 has a passage for gas flow. The gas compressed by the primary screw structure 103 enters the secondary screw through the airflow passage in the flange block 2. Structure 102 undergoes secondary compression. The contact surface connecting the flange block 2 with the secondary screw structure 102 and the primary screw structure 103 is provided with a groove for setting a sealing ring. From the central cavity outward, there are sequentially provided a pressure sealing groove 21 and a magnetic fluid sealing groove 23. The sealing ring set in the pressure sealing groove 21 is a capsule structure, and one side can contact the high-pressure gas in the flange block 2. The sealing ring set in the magnetic fluid sealing groove 23 is a capsule structure. The capsule set in the magnetic fluid sealing groove 23 is a flexible sealing capsule filled with magnetic powder and liquid fluid. When the permanent magnet synchronous motor 104 works, when the magnetic force is transmitted to the flange block 2 along the shaft, the magnetic powder forms a chain and adheres tightly to the side wall in the magnetic fluid sealing groove 23.

[0021] When air enters the primary screw structure 103 and undergoes initial compression, the air pressure rises and enters the flange block 2, which has a passage for gas flow. The sealing ring in the pressure sealing groove 21 experiences a decrease in volume on one side due to its bladder-like structure. The fluid inside flows to the other side, i.e., the contact surface between the flange block 2 and the primary screw structure 103 or the secondary screw structure 102, causing the sealing ring to expand and enhancing the sealing effect. When the permanent magnet synchronous motor is not running, there is no shaft system conducting the magnetic field. The sealing bladder contains a low-viscosity fluid, and the bladder remains flexible, only providing basic... The static seal avoids long-term pressure fatigue of the sealing components. After the permanent magnet synchronous motor starts running, the rotor permanent magnet generates a magnetic field, which is conducted to the flange sealing area along the ferromagnetic shaft system, instantly triggering magnetic powder chaining. Attracted by the magnetic field, each single-domain magnetic powder particle is magnetized by the external magnetic field, and its inherent magnetic moment is forced to align along the direction of the magnetic field lines, so that the magnetic field direction of the magnetic powder is unified. Along the direction of the magnetic field lines, the S pole of the previous particle attracts the N pole of the next particle, and the particles overlap end to end along the direction of the magnetic field lines, forming short magnetic chains. At this time, the thermal motion of the carrier liquid molecules is still disturbed, but the external magnetic field... The directional force plus the magnetic dipole attraction is far greater than the thermal kinetic energy, so the short chains will not be broken up. After the short chains are formed, under the continuous action of the magnetic field, the ends of the chains continue to overlap along the direction of the magnetic field lines. The free ends of the short chains (i.e., N poles / S poles) will attract the opposite poles of other short chains, splicing them together along the direction of the magnetic field lines to form a long chain capsule. A rigid skeleton for pressure transmission is formed on the sealing surface of flange block 2 and the bottom of the magnetohydrodynamic sealing groove 23. After the long chains are formed, the lateral magnetic interaction (lateral N / S pole attraction) between adjacent long chains will cause the long chains to cross-link with each other, forming a three-dimensional dense network. The load inside the capsule... The liquid is locked in the gaps of the magnetic flux network and cannot flow freely. The viscosity of the medium increases by 100 to 150 times instantly, and the network structure generates shear yield strength—this is the source of the sealing pressure. If the external force (leakage pressure) wants to push the medium away, it must first overcome the resistance of this rigid network. At this time, the medium set in the magnetic fluid sealing groove 23 completely changes from a low-viscosity fluid to a rigid semi-solid, like reinforced concrete, which can stably support the sealing pressure, so that the sealing pressure is automatically generated at this point. The pressure is stable and constant with the motor magnetic field, realizing the synchronous triggering of motor rotation and sealing tightening. After the motor stops and the power is cut off, the magnetic field conducted by the shaft system disappears, and the magnetic powder returns to its disordered distribution. The magnetic powder is made of nano-sized magnetic powder, and each particle has only one magnetic domain. The magnetic moment direction is fixed, but without the directional effect of an external magnetic field, no force can make the magnetic moments of all particles uniformly oriented. The magnetic moment of each particle is randomly oriented, like a handful of small compass needles scattered on a table, spinning randomly. The magnetic moment of a single magnetic powder particle will generate a weak magnetic attraction / repulsion force on the surrounding particles, but because the magnetic moment direction is random, this interaction is also irregular and undirected. The medium returns to a low-viscosity flow dynamic, the sealing pressure of the capsule is automatically released, and the flexible state is restored.

[0022] See Figures 3-5 The bottom of the pressure sealing groove 21 is provided with a pressure channel 212. The pressure channel 212 is slot-shaped, with one end connected to the pressure sealing groove 21 and the other end set on the side wall of the flange block 2 cavity opening. The pressure channels 212 are arranged in a spaced array along the side wall of the flange block 2. There are at least two pressure sealing grooves 21, and the depths of adjacent pressure sealing grooves 21 are different, with the depth further away from the center of the flange block 2 being deeper, forming a multi-layer seal. When high-pressure gas passes through the flange block 2, it can squeeze the sealing ring set in the pressure sealing groove 21 through the pressure channel 212 on the wall.

[0023] In the primary screw structure 103, one end of the male rotor is connected to and driven by the permanent magnet synchronous motor 104, and the other end is equipped with a gear that meshes with the gear at the end of the male rotor in the secondary screw structure 102 in the flange block 2. The cavity in which the flange block 2 communicates with the secondary screw structure 102 and the primary screw structure 103 is generally rounded rectangular. The pressure sealing groove 21 and the magnetic fluid sealing groove 23 match the shape of the cavity. The magnetic fluid sealing groove 23 is segmented, consisting of a rounded corner groove and a right-angle groove. The segmented sealing groove reduces the processing difficulty of the flexible capsule in the magnetic fluid sealing groove 23 and enables better mass production.

[0024] A self-compensating sealing groove 22 with a matching shape is provided between the pressurized sealing groove 21 and the magnetohydrodynamic sealing groove 23. The sealing ring in the self-compensating sealing groove 22 contains a magnetically attractive metal ring 221. The metal ring 221 is shaped to match the self-compensating sealing groove 22, and there are two of them, one contacting the wall of the magnetohydrodynamic sealing groove 23 and the other the wall of the pressurized sealing groove 21. The sealing ring completely encloses the metal ring 221. When the motor is stopped, the magnetic field disappears, and the metal ring 221 has no magnetic force. The sealing ring mainly relies on its own elasticity and interference fit to provide a basic static seal. When the motor starts running, the principle is immediately triggered in two steps: the first step is magnetic pre-tightening. The shaft magnetic field is quickly established and penetrates the flange material, attracting the metal ring 211 in the self-compensating sealing groove. Under the influence of magnetic force, the metal ring 211 tends to move towards the magnetic field source (i.e., the axial direction), but is constrained by the sealing ring material and the groove, thus converting the magnetic attraction into a radial compressive force on the sealing ring body, pressing it tightly against the sealing contact surfaces on both sides. This process is almost synchronous with the motor being energized, quickly establishing a reliable initial seal. The second step is pressure-magnetic synergy. As the compressor loads, the high pressure generated by the primary compressed gas enters the pressurized sealing groove through the pressurization channel, pushing the bladder within the groove to expand and press against the sealing surface. This pressure also acts on the self-compensating sealing groove area. At this point, under the continuous magnetic attraction, the metal ring 211 inside the sealing ring acts like a skeleton implanted in the flexible sealing ring. This not only enhances the sealing ring's resistance to deformation under high-pressure gas, preventing excessive deformation and damage, but more importantly, the magnetic attraction, as a constant, directional reference force, forms a dynamic balance with the fluctuating gas pressure. When the gas pressure fluctuates or the preceding seal loosens slightly, the magnetic attraction can immediately pull the sealing ring back through the rigid metal ring and maintain a compressed state. Conversely, when the pressure abnormally increases, the magnetic force and the structure of the metal ring 211 together limit the deformation limit of the sealing ring, protecting it from damage. Therefore, this structure, by locking the rigid core with a magnetic field and driving overall deformation with gas pressure, achieves an intelligent self-compensation effect where the sealing force dynamically changes with operating conditions and automatically returns to a stable set value.

[0025] The filling medium in the magnetic fluid sealing groove 23 consists of nano-carbonyl iron powder magnetic powder and synthetic hydrocarbon carrier liquid, as well as stabilizer and defoamer. The nano-carbonyl iron powder has a particle size of 50~80nm, a saturation magnetization of 150~180 emu / g, and accounts for 35%~40% by mass. The polyalphaolefin synthetic oil (compatible with air compressor lubricating oil) has a viscosity of 40mm at 40℃. 2 / s, with a mass ratio of 58%~63%, the medium is a low-viscosity flowing liquid when there is no magnetic field.

[0026] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0027] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An integrated permanent magnet synchronous two-stage compression screw air compressor, comprising a housing (101) and a compression structure (1) disposed therein, the compression structure (1) comprising a two-stage screw structure (102), a flange block (2), a first-stage screw structure (103), and a permanent magnet synchronous motor (104), characterized in that: The secondary screw structure (102) and the primary screw structure (103) each have a pair of meshing male and female rotors. The primary screw structure (103) and the secondary screw structure (102) are horizontally connected by a flange block (2). The flange block (2) has a passage for gas flow. The gas compressed by the primary screw structure (103) enters the secondary screw structure (102) through the airflow passage in the flange block (2) for secondary compression. The contact surface between the flange block (2) and the secondary screw structure (102) and the primary screw structure (103) is provided with a sealing ring. The groove is provided with a pressure sealing groove (21) and a magnetic fluid sealing groove (23) in sequence from the central cavity outward. The sealing ring in the pressure sealing groove (21) is a bladder structure and one side can contact the high pressure gas in the flange block (2). The sealing ring in the magnetic fluid sealing groove (23) is a bladder structure. The bladder in the magnetic fluid sealing groove (23) is a flexible sealing bladder filled with magnetic powder and liquid fluid. When the permanent magnet synchronous motor (104) is working, when the magnetic force is transmitted to the flange block (2) along the shaft, the magnetic powder forms a chain and sticks tightly to the side wall in the magnetic fluid sealing groove (23).

2. The integrated permanent magnet synchronous two-stage compression screw air compressor according to claim 1, characterized in that: In the first-stage screw structure (103), one end of the male rotor is connected to and driven by a permanent magnet synchronous motor (104), and the other end is provided with a gear that meshes with the gear at the end of the male rotor in the second-stage screw structure (102) in the flange block (2).

3. The integrated permanent magnet synchronous two-stage compression screw air compressor according to claim 2, characterized in that: The flange block (2) and the cavity connected to the secondary screw structure (102) and the primary screw structure (103) are in the shape of a rounded rectangle. The pressure sealing groove (21) and the magnetic fluid sealing groove (23) are matched with the shape of the cavity.

4. The integrated permanent magnet synchronous two-stage compression screw air compressor according to claim 1, characterized in that: The bottom of the pressurized sealing groove (21) is provided with a pressurized channel (212). The pressurized channel (212) is in the shape of a slot, with one end connected to the pressurized sealing groove (21) and the other end set on the side wall of the cavity opening of the flange block (2). The pressurized channels (212) are arranged in a spaced array along the side wall of the flange block (2).

5. The integrated permanent magnet synchronous two-stage compression screw air compressor according to claim 4, characterized in that: The pressure sealing groove (21) is provided in at least two, and the adjacent pressure sealing grooves (21) have different depths, with the one further away from the center of the flange block (2) being deeper.

6. The integrated permanent magnet synchronous two-stage compression screw air compressor according to claim 1, characterized in that: A self-compensating sealing groove (22) with a matching shape is provided between the pressurized sealing groove (21) and the magnetic fluid sealing groove (23). The sealing ring provided in the self-compensating sealing groove (22) has a metal ring (221) that can be magnetically attracted. The shape of the metal ring (221) matches the self-compensating sealing groove (22), and there are two of them, which respectively contact the wall surface near the magnetic fluid sealing groove (23) and the wall surface of the pressurized sealing groove (21). The sealing ring completely covers the metal ring (221).

7. The integrated permanent magnet synchronous two-stage compression screw air compressor according to claim 3, characterized in that: The magnetic fluid sealing groove (23) is segmented, consisting of a rounded corner groove and a right-angle groove.

8. The integrated permanent magnet synchronous two-stage compression screw air compressor according to claim 1 or 7, characterized in that: The filling medium of the bladder in the magnetic fluid sealing groove (23) is nano carbonyl iron powder magnetic powder and synthetic hydrocarbon carrier liquid, as well as stabilizer and defoamer.

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