Variable frequency oil-free screw blower

Abstract

The application relates to the technical field of air blowers, and discloses a variable-frequency oil-free screw blower, which comprises a blower shell, one side of the blower shell is fixedly provided with an air suction end cover, the other side of the blower shell is fixedly provided with an air exhaust end cover, a compression cavity is formed in the blower shell, a female rotor and a male rotor are rotatably arranged in the compression cavity, a variable-frequency motor for driving the male rotor to rotate is further connected to one side of the male rotor, the surfaces of the female rotor and the male rotor are sprayed with protective coating, and a compensation structure for compensating the gap between the female rotor and the male rotor due to the axial movement of the female rotor and the male rotor caused by thermal expansion is arranged between the two ends of the female rotor and the blower shell; during the rotation of the female rotor, the centrifugal force generated by the rotation of the counterweight block along with the female rotor is converted into axial force for driving the female rotor through a radial wedge surface, the meshing gap between the female rotor and the male rotor is self-adaptively adjusted, and the problem of gap reduction caused by the thermal expansion of the female rotor and the male rotor is effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of blower technology, specifically to a variable frequency oil-free screw blower. Background Technology

[0002] An oil-free screw blower is a gas conveying device with a compression chamber completely free of lubricating oil. Gas compression is achieved through the meshing and rotation of male and female rotors in a non-contact state. The rotor gap is controlled by a synchronous gear system to ensure that the conveyed gas is absolutely pure and oil-free. Compared with traditional oil-lubricated blowers, oil-free screw blowers have advantages such as high gas cleanliness, low maintenance requirements, stable and reliable operation, and excellent energy efficiency. They are widely used in fields with strict requirements for gas quality, such as food and pharmaceutical production, sewage treatment, electronics manufacturing, and chemical processes.

[0003] Existing oilless screw blowers typically have a pre-set meshing clearance between the male and female rotors to prevent gas leakage and dry friction during compression. However, during blower operation, the meshing of the male and female rotors to compress the gas generates a large amount of heat. Furthermore, the lack of effective heat dissipation due to the absence of lubricating oil in oilless operation causes the rotor temperatures to rise rapidly and expand thermally. This results in a significant reduction in the originally reserved meshing clearance. While the thermal expansion of the male and female rotors under stable operating conditions is usually calculated, when the rotors operate at excessively high speeds and generate loads, the thermal expansion can exceed the allowable range, causing the clearance between the rotors to decrease to a critical value. When the clearance falls below this critical value, it can easily lead to mutual scraping or even jamming between the rotors. This not only causes blower shutdown but also severe wear on the rotor teeth and coating peeling, reducing equipment reliability and service life. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a variable frequency oil-free screw blower with the advantage of adaptive adjustment of rotor meshing clearance with thermal expansion. This solves the problem of rotor scraping and jamming caused by rotor thermal expansion exceeding the critical value during load operation in oil-free screw blowers, which reduces the reserved meshing clearance.

[0005] (II) Technical Solution To achieve the aforementioned objective of adaptive adjustment of rotor meshing clearance with thermal expansion, the present invention provides the following technical solution: a variable frequency oil-free screw blower, comprising a blower housing, an intake end cover fixedly mounted on one side of the blower housing, an exhaust end cover fixedly mounted on the other side of the blower housing, a compression chamber machined inside the blower housing, and a female rotor and a male rotor rotatably mounted in the compression chamber to mesh and compress gas, wherein the two ends of the female rotor and the male rotor are respectively rotatably connected to the exhaust end cover and the intake end cover, and a variable frequency motor for driving the male rotor to rotate is also connected to one side of the male rotor. The surfaces of the female rotor and the male rotor are coated with a protective coating to prevent thermal expansion of the female rotor and the male rotor. A compensation structure is provided between the two ends of the female rotor and the blower housing to compensate for the gap between the female rotor and the male rotor due to axial movement caused by thermal expansion of the male rotor and the female rotor.

[0006] Preferably, a gap is provided between the meshing surfaces of the female rotor and the male rotor helical teeth, and the protective coating is a ceramic coating.

[0007] Preferably, the intake end cover has an axial sliding cavity coaxial with the female rotor. The compensation structure includes an annular top block, a cylindrical roller bearing, and a disc spring. The cylindrical roller bearing is coaxially assembled in the sliding cavity, and its inner ring is coaxially interference-fitted with the female rotor. The top block is coaxially disposed on the side of the cylindrical roller bearing away from the compression cavity. The top block is coaxially fixedly connected to the female rotor and abuts against the end face of the sliding cavity. Two or more sets of inclined radial wedges distributed circumferentially are formed on the abutting end face of the top block and the sliding cavity. The small end of the radial wedge is close to the radial outer side of the top block, and the large end is close to the female rotor. The rotor's axis has a counterweight block slidably mounted within the radial wedge surface, the counterweight block having an angle adapted to its tilt. A spring mounting groove is provided on the end face of the sliding cavity near the compression cavity. The disc spring is fixedly mounted within the spring mounting groove, with one end connected to the end face of the cylindrical roller bearing away from the top block. When the female rotor synchronously drives the top block and the counterweight block to rotate coaxially, the counterweight block slides radially outward from the top block along the radial wedge surface under centrifugal force, generating an axial displacement increment relative to the top block, thereby generating an axial force on the end face of the sliding cavity, pushing the top block to move in an axial direction away from the end face of the sliding cavity.

[0008] Preferably, the axial length of the disc spring is greater than the length of the spring mounting groove, and the difference between the axial length of the disc spring and the axial length of the spring mounting groove is the maximum axial movement length of the female rotor.

[0009] Preferably, a sealing ring is also provided between the disc spring and the cylindrical roller bearing.

[0010] Preferably, a radially arranged radial return spring is assembled between the counterweight and the radial wedge surface. One end of the return spring is connected to the side of the counterweight facing the female rotor axis, and the other end of the return spring is fixedly connected to the inner wall of the large end of the radial wedge surface. The radial preload of the return spring is adapted to the centrifugal force threshold of the counterweight. When the centrifugal force generated by the rotation of the female rotor is greater than the radial elastic force of the return spring, the counterweight slides radially outward along the inclined direction of the radial wedge surface and is converted into axial force by the radial compression of the radial wedge surface.

[0011] Preferably, the cylindrical roller bearing and the sliding cavity are axially slidably connected.

[0012] Preferably, a slide rail is further machined on the radial wedge surface along a direction parallel to its inclination, the counterweight is slidably connected to the slide rail, and the return spring is embedded inside the slide rail and connected to the counterweight.

[0013] Preferably, the slide rail is also fixedly equipped with an adjusting block that can slide along the slide rail direction and be fixed on the slide rail, thereby limiting the radial sliding distance of the counterweight in the radial wedge surface by using adjusting blocks of different diameters.

[0014] Preferably, journals are machined on both sides of the female rotor. The journal near the intake end cover is equipped with the compensation structure. A driven gear is provided on the journal near the exhaust end cover to transmit the rotational force of the male rotor to the journal and drive the female rotor to rotate synchronously. A driving gear that meshes with the driven gear is coaxially fixed on the male rotor near the exhaust end cover. A sealing structure is also provided between the male rotor, the exhaust end cover, and the intake end cover. A guide key is provided between the driven gear and the journal to allow the journal to slide axially relative to the driven gear. An axial fixing structure is provided between the driven gear and the exhaust end cover to restrict the axial sliding of the driven gear.

[0015] Preferably, the blower housing has an intake end seat at the top and an exhaust end seat at the bottom, both of which are connected to the compression chamber. An intake pipe is connected to the intake end seat, and an exhaust pipe is fixedly connected to the exhaust end seat. A filter module is provided on the intake pipe. A support base is fixedly connected to the bottom of the variable frequency motor. The blower housing is fixedly mounted on the support base via the exhaust end cover and the intake end cover. The male rotor, with one end near the exhaust end cover, passes through the exhaust end cover and is coaxially and fixedly connected to the drive end of the variable frequency motor.

[0016] Preferably, the angle of the end face of the counterweight toward the radial wedge surface is parallel to the radial wedge surface, and the angle of the end face of the counterweight toward the sliding cavity end face is parallel to the sliding cavity end face.

[0017] (III) Beneficial Effects Compared with the prior art, the present invention provides a variable frequency oil-free screw blower, which has the following beneficial effects: 1. This variable frequency oil-free screw blower, through the combined use of the female rotor structure and the compensation structure, converts the centrifugal force generated by the counterweight as the female rotor rotates into an axial force that drives the female rotor to move towards the exhaust end cover through the inclined surface of the radial wedge. This achieves adaptive adjustment of the meshing gap between the female and male rotors with thermal expansion, effectively suppressing the problem of gap reduction caused by thermal expansion of the male and female rotors at high speeds, avoiding scraping or jamming between the female and male rotors, protecting the helical tooth meshing surface and surface protective coating of the female and male rotors, and reducing blower downtime failures.

[0018] 2. This variable frequency oil-free screw blower, through the coordinated use of the adjustable stop block structure and the counterweight block structure, can flexibly adjust the fixed position of the adjusting stop block on the slide rail according to the thermal expansion clearance requirements of the female rotor and the male rotor at different speeds. This limits the maximum radial sliding distance of the counterweight block along the radial wedge surface, realizing the on-demand adjustment of the maximum axial sliding distance of the female rotor. It effectively solves the problem of mismatch between the axial movement distance of the female rotor and the clearance required after thermal expansion, avoids excessive compression of the sliding cavity end face by the counterweight block, and ensures that the axial movement of the female rotor always matches the clearance requirements after thermal expansion. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural schematic diagram of the variable frequency oil-free screw blower in this invention; Figure 2 This is a front view of the structure of the variable frequency oil-free screw blower in this invention; Figure 3 This is a three-dimensional structural diagram of the blower housing of the variable frequency oil-free screw blower in this invention; Figure 4 This is a cross-sectional view of the blower housing structure of the variable frequency oil-free screw blower in this invention; Figure 5 This is a schematic diagram of the female rotor structure transmission of the variable frequency oil-free screw blower in this invention; Figure 6 This is a schematic diagram of the axial compensation direction of the compensation structure of the variable frequency oil-free screw blower in this invention; Figure 7 This is a schematic diagram of the top block structure movement of the variable frequency oil-free screw blower in this invention; Figure 8This is a cross-sectional view of the structure in Embodiment 2 of the present invention; Figure 9 This is a front view of the structure of Embodiment 2 of the present invention.

[0020] In the diagram: 1. Blower housing; 11. Compression chamber; 12. Intake end seat; 13. Exhaust end seat; 14. Intake end cover; 15. Exhaust end cover; 16. Intake pipe; 17. Exhaust pipe; 18. Support seat; 2. Female rotor; 3. Male rotor; 4. Variable frequency motor; 5. Compensation structure; 51. Sliding chamber; 52. Spring mounting slot; 53. Top block; 531. Radial wedge surface; 532. Counterweight block; 533. Return spring; 534. Slide rail; 535. Adjusting stop; 54. Cylindrical roller bearing; 55. Disc spring; 56. Sealing ring; 6. Journal; 61. Driven gear; 62. Guide key; 7. Drive gear. Detailed Implementation

[0021] 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.

[0022] Example 1 Please see Figures 1-7A variable frequency oil-free screw blower includes a blower housing 1. An intake end cover 14 is fixedly mounted on one side of the blower housing 1, and an exhaust end cover 15 is fixedly mounted on the other side. A compression chamber 11 is machined inside the blower housing 1. A female rotor 2 and a male rotor 3, which mesh with each other to compress gas, are rotatably mounted within the compression chamber 11. Annular positioning stops are machined on both end faces of the blower housing 1. The intake end cover 14 and the exhaust end cover 15 are assembled at the positioning stops by circumferentially evenly distributed fastening bolts. A sealing gasket is installed between the end cover and the housing contact surface to achieve gas sealing. The compression chamber 11 is a double cylindrical chamber adapted to the shape of the female rotor 2 and the male rotor 3. The inner wall of the chamber is precision-bored and then polished. The female rotor 2 and the male rotor 3 adopt a conjugate helical tooth structure, and are arranged parallel to each other within the compression chamber 11 and maintain a meshing state. The female rotor 2 and the male rotor 3 are rotatably connected to the exhaust end cover 15 and the intake end cover 14 at their respective ends. A variable frequency motor 4 that drives the male rotor 3 is also connected to one side of the male rotor 3. The end of the male rotor 3 near the exhaust end cover 15 extends out of the end cover and is coaxially connected to the output shaft of the variable frequency motor 4 through a coupling. The two ends of the coupling are fixed to the journal 6 of the male rotor 3 and the output shaft of the motor through flat keys, respectively. The surfaces of the female rotor 2 and the male rotor 3 are coated with a protective coating to prevent thermal expansion of the female rotor 2 and the male rotor 3. A compensation structure 5 is provided between the two ends of the female rotor 2 and the blower housing 1 to compensate for the gap between the female rotor 2 and the male rotor 3 due to axial movement caused by the thermal expansion of the male rotor 3 and the female rotor 2.

[0023] Please see Figures 1-7A gap is provided between the meshing surfaces of the helical teeth of the female rotor 2 and the male rotor 3. An initial gap is reserved between the meshing surfaces of the helical teeth of the female rotor 2 and the male rotor 3. The setting of this gap is adapted to the thermal expansion characteristics of the rotor and the thermal stability of the ceramic coating, ensuring that the rotor tooth surfaces do not come into contact friction under low speed and normal temperature conditions, while avoiding gas leakage caused by excessive gap. The protective coating is a ceramic coating. Specifically, the ceramic coating adopts an alumina-zirconia composite ceramic material. The ceramic coating is prepared by atmospheric plasma spraying process. Before spraying, the surfaces of the female rotor 2 and the male rotor 3 need to be pretreated. First, the oxide scale and impurities on the rotor surface are removed by sandblasting to form a rough surface morphology to enhance the mechanical bonding force between the coating and the substrate. Then, a layer of metal bonding underlayer is sprayed to further improve the bonding strength between the composite ceramic coating and the female rotor 2 and the male rotor 3. Due to its excellent high temperature resistance, low thermal conductivity and good chemical stability, the ceramic coating will not deteriorate or contaminate the compressed gas under oil-free conditions. Moreover, its high surface smoothness can greatly reduce the friction coefficient during rotor meshing. An axial sliding cavity 51 coaxial with the female rotor 2 is provided inside the intake end cover 14. The compensation structure 5 includes an annular top block 53, a cylindrical roller bearing 54, and a disc spring 55. The cylindrical roller bearing 54 is coaxially assembled in the sliding cavity 51, and its inner ring is coaxially interference-fitted with the female rotor 2. The top block 53 is coaxially provided on the side of the cylindrical roller bearing 54 away from the compression cavity 11. The top block 53 is coaxially fixedly connected with the female rotor 2 and abuts against the end face of the sliding cavity 51. A cylindrical mounting surface adapted to the cylindrical roller bearing 54 is machined in the sliding cavity 51. The outer ring of the cylindrical roller bearing 54 is clearance-fitted with the mounting surface of the sliding cavity 51, allowing the bearing to slide axially. The inner ring is interference-fitted with the journal 6 of the female rotor 2. The top block 53 is an annular structure with a keyway machined on its inner diameter. It is fixedly connected to the journal 6 of the female rotor 2 by a flat key. One end face of the top block 53 is in contact with the end face of the inner ring of the cylindrical roller bearing 54, and the other end face is in close contact with the end face of the sliding cavity 51. The contact surfaces are ground to ensure flatness, reduce the loss in the force transmission process, or a bearing can be set between the end face of the sliding cavity 51 and the top block 53 to further reduce friction damage and reduce the frequency of equipment maintenance. Two or more sets of inclined radial wedge surfaces 531 distributed circumferentially are provided on the contact end face of the top block 53 and the sliding cavity 51. The small end of the radial wedge surface 531 is close to the radial outer side of the top block 53, and the large end is close to the axis of the female rotor 2. A counterweight block 532 adapted to its inclination angle is slidably assembled in the radial wedge surface 531. The contact end face of the top block 53 and the sliding cavity 51 is an annular flat surface. A bearing can be provided between the top block 53 and the sliding cavity 51 to reduce friction. Two or more sets of radial wedge surfaces 531 are evenly provided on the top block 53 along the circumferential direction. Each radial wedge surface 531 is a smooth inclined plane. Its inclination direction is at a certain angle with the radial direction of the top block 53. The surface of the wedge surface is finely ground and sprayed with a self-lubricating coating.The counterweight 532 is a block structure that perfectly matches the shape of the radial wedge surface 531. One end face of the counterweight 532 facing the radial wedge surface 531 is machined into an inclined surface with the same inclination angle as the wedge surface, while the other end face is flat. Both sides of the counterweight 532 are machined with bosses that match the slide rail 534. A spring mounting groove 52 is provided on the end face of the sliding cavity 51 near the compression cavity 11. The disc spring 55 is fixedly assembled in the spring mounting groove 52, with one end connected to the end face of the cylindrical roller bearing 54 away from the top block 53. An annular spring mounting groove 52 is machined on the end face of the sliding cavity 51 near the compression cavity 11. The inner and outer diameters of the mounting groove match the inner and outer diameters of the disc spring 55. The bottom of the groove is surface-ground to ensure flatness, and the groove wall has an annular positioning step to prevent the disc spring 55 from moving radially. The disc spring 55 is embedded in the mounting groove in a multi-piece stacked arrangement. One end of the disc spring is positioned against the positioning step of the mounting groove, and the other end abuts against the end face of the cylindrical roller bearing 54 away from the top block 53 via a circular washer. The washer is made of wear-resistant material and has a polished surface. When the female rotor 2 synchronously drives the top block 53 and the counterweight 532 to rotate coaxially, the counterweight 532 slides radially outward from the top block 53 along the radial wedge surface 531 under centrifugal force, and generates an axial displacement increment relative to the top block 53, thereby generating an axial force on the end face of the sliding cavity 51, pushing the top block 53 to move axially away from the end face of the sliding cavity 51.

[0024] Please see Figures 1-7The cylindrical roller bearing 54 is axially slidingly connected to the sliding cavity 51. The outer ring of the cylindrical roller bearing 54 and the inner wall of the sliding cavity 51 are clearance-fitted. Two symmetrical guide grooves are machined axially on the inner wall of the sliding cavity 51. A guide boss is integrally formed at the corresponding position on the outer ring of the cylindrical roller bearing 54. The guide boss is embedded in the guide groove, restricting the circumferential rotation of the bearing but allowing free axial sliding. The axial length of the disc spring 55 is greater than the length of the spring mounting groove 52, and the difference between the axial length of the disc spring 55 and the axial length of the spring mounting groove 52 is the maximum axial movement length of the female rotor 2. The difference between the axial length of the disc spring 55 and the length of the spring mounting groove 52 is calculated to be exactly equal to the maximum axial compensation stroke required by the female rotor 2, and this difference is controlled within the elastic deformation range of the disc spring 55 to avoid excessive spring extension and contraction causing plastic damage. An angular contact ball bearing is also coaxially arranged between the cylindrical roller bearing 54 and the top block 53. An angular contact ball bearing is coaxially clamped between the cylindrical roller bearing 54 and the top block 53. Its inner ring is interference-fitted with the journal 6 of the female rotor 2 and fixed to the journal 6 by a heat-fitting process. The outer ring is connected to the sliding cavity 51 by the same guide boss and guide groove as the outer ring of the cylindrical roller bearing 54. A radially arranged radial return spring 533 is assembled between the counterweight 532 and the radial wedge surface 531. One end of the return spring 533 is connected to the side of the counterweight 532 facing the axis of the female rotor 2, and the other end of the return spring 533 is fixedly connected to the inner wall of the large end of the radial wedge surface 531. The radial preload of the return spring 533 is adapted to the centrifugal force threshold of the counterweight 532. The radial return spring 533 is a cylindrical helical spring. The radial preload of the return spring 533 is calibrated to match the centrifugal force generated by the counterweight 532 at the critical speed. This ensures that at low speeds, the spring can firmly hold the counterweight 532 in its initial position, while at high speeds, the centrifugal force is just enough to overcome the spring force and trigger the counterweight 532 to slide. When the centrifugal force generated by the rotation of the female rotor 2 driving the counterweight 532 is greater than the radial force of the return spring 533, the counterweight 532 slides radially outward along the inclined direction of the radial wedge surface 531 towards the top block 53 and is converted into axial force by the radial compression of the radial wedge surface 531. A sealing ring 56 is also provided between the disc spring 55 and the cylindrical roller bearing 54. The sealing ring 56 is an annular elastomer. Its inner diameter is adapted to the outer diameter of the end face of the cylindrical roller bearing 54, and its outer diameter fits the inner wall of the spring mounting groove 52. It is embedded in the gap between the disc spring 55 and the cylindrical roller bearing 54 by an interference fit. The two end faces of the sealing ring 56 are tightly fitted to the end faces of the disc spring 55 and the cylindrical roller bearing 54, respectively. A slide rail 534 parallel to its inclined direction is also machined on the radial wedge surface 531. The counterweight 532 is slidably connected to the slide rail 534. The return spring 533 is embedded in the slide rail 534 and connected to the counterweight 532.A rectangular or T-shaped groove is machined on the radial wedge surface 531 along its inclined direction to serve as a slide rail 534. The inner wall of the slide rail 534 is precision ground and coated with a self-lubricating coating. The counterweight 532 has integrally formed bosses on both sides that fit the grooves of the slide rail 534. The bosses are embedded in the slide rail 534 to form a sliding fit, ensuring that the counterweight 532 can only slide along the direction of the slide rail 534. An installation groove is machined along the length of the slide rail 534, and a return spring 533 is installed in this groove. The angle of the end face of the counterweight 532 facing the radial wedge surface 531 is parallel to the radial wedge surface 531, and the angle of the end face of the counterweight 532 facing the end face of the sliding cavity 51 is parallel to the end face of the sliding cavity 51. The side of the counterweight 532 facing the radial wedge surface 531 is precision ground, and its inclination angle is completely consistent with the inclination angle of the radial wedge surface 531. The side of the counterweight 532 facing the sliding cavity 51 is machined into a flat plane, and its plane angle is parallel to the end face angle of the sliding cavity 51, so that there is no tilt gap when they are in contact. Both end faces are coated with a self-lubricating coating to reduce the coefficient of friction during contact and sliding.

[0025] Please see Figures 1-7The female rotor 2 has journals 6 machined on both sides. The journal 6 near the intake end cover 14 is fitted with a compensation structure 5. The journal 6 near the exhaust end cover 15 is provided with a driven gear 61 that transmits the rotational force of the male rotor 3 to the journal 6 and drives the female rotor 2 to rotate synchronously. The two sides of the female rotor 2 are coaxially integrally machined with cylindrical journals 6. The surface of the journals 6 is precision ground to ensure coaxiality and surface smoothness. The outer diameter of the journal 6 near the intake end cover 14 is adapted to the inner ring of the cylindrical roller bearing 54 for mounting the compensation structure 5. The journal 6 near the exhaust end cover 15 is machined with a keyway adapted to the guide key 62 for mounting the driven gear 61. A driving gear 7, which meshes with the driven gear 61, is coaxially fixed on the side of the male rotor 3 near the exhaust end cover 15. A sealing structure is also provided between the male rotor 3 and the exhaust end cover 15 and the intake end cover 14. The sealing structure between the male rotor 3 and the end cover uses a lip seal 56 or a mechanical seal, assembled in the sealing groove of the end cover. The lip of the seal 56 fits tightly with the journal 6 of the male rotor 3 to achieve a rotary seal. A guide key 62 is provided between the driven gear 61 and the journal 6, allowing the journal 6 to slide axially relative to the driven gear 61. An axial fixing structure is provided between the driven gear 61 and the exhaust end cover 15 to restrict the axial sliding of the driven gear 61. The guide key 62 is rectangular and is fitted into the keyway of the journal 6 of the female rotor 2. The hub hole of the driven gear 61 has a long, narrow keyway that forms a clearance fit with the guide key 62, allowing the journal 6 of the female rotor 2 to slide axially relative to the driven gear 61. The axial fixing structure uses a combination of a retaining ring and a lock nut. The retaining ring fits against the end face of the driven gear 61, and the lock nut is threaded onto the exhaust end cover 15, cooperating with the exhaust end cover 15 to restrict the axial displacement of the driven gear 61. The end of the male rotor 3 closest to the exhaust end cover 15 passes through the exhaust end cover 15 and is coaxially and fixedly connected to the drive end of the variable frequency motor 4. Please see Figures 1-7The blower housing 1 has an intake end seat 12 at the top and an exhaust end seat 13 at the bottom. Both the intake and exhaust end seats 12 and 13 are connected to the compression chamber 11. The intake end seat 12 is integrally formed on the top of the blower housing 1, and the exhaust end seat 13 is integrally formed on the bottom. Both are cylindrical protrusions with flanges, and the interior of each end seat has an air passage communicating with the compression chamber 11. An intake pipe 16 is connected to the intake end seat 12, and an exhaust pipe 17 is fixedly connected to the exhaust end seat 13. One end of the intake pipe 16 is fixed to the flange face of the intake end seat 12 via a flange or threaded connection, with a gasket between the connecting surfaces to achieve a gas seal. One end of the exhaust pipe 17 is fixed to the flange face of the exhaust end seat 13 using the same connection method, and the connection is secured with locking bolts to ensure a firm connection. Both the intake pipe 16 and the exhaust pipe 17 are cylindrical pipes. A filter module is installed on the intake pipe 16. The filter module, consisting of a filter element, a filter housing, and an end cap, is assembled at the intake end of the intake pipe 16. The filter housing is fixed to the intake pipe 16 by threads or clips. A support base 18 is fixedly connected to the bottom of the variable frequency motor 4. The blower housing 1 is fixedly assembled to the support base 18 by the exhaust end cap 15 and the intake end cap 14. The bottom of the variable frequency motor 4 is fixedly connected to the support base 18 by bolts. The support base 18 is a rigid frame structure made of high-strength cast iron. The blower housing 1 is fixedly assembled to the support base 18 by fastening bolts. A shock-absorbing pad is installed between the end cap and the support base 18 to reduce the transmission of vibration during equipment operation.

[0026] Please see Figures 1-7During operation, the variable frequency motor 4 drives the male rotor 3 to rotate. The male rotor 3 drives the female rotor 2 to rotate synchronously in the compression chamber 11 of the blower housing 1 through the meshing drive gear 7 and driven gear 61. It draws in gas from the intake end seat 12, compresses it and discharges it from the exhaust end seat 13. During the compression process, as the female rotor 2 and the male rotor 3 gradually accelerate from low speed to high speed, they will generate thermal expansion due to the heat of compression, which will cause the reserved gap between their helical tooth meshing surfaces to gradually shrink. When the rotational speed of the female rotor 2 increases from low to high, the top block 53 in the compensation structure 5 rotates synchronously with the female rotor 2, thereby causing the counterweight 532 in its radial wedge surface 531 to rotate together and generate centrifugal force. When the centrifugal force generated by the increased rotational speed of the counterweight 532 exceeds the radial elastic force of the radial return spring 533, the counterweight 532 will slide radially outward from the top block 53 along the inclined direction within the radial wedge surface 531. Since the counterweight 532 is originally in contact with the end face of the sliding cavity 51 on the side of the radial wedge surface 531 closest to the axis of the female rotor 2, and the end face of the counterweight 532 in contact with the end face of the sliding cavity 51 during the sliding process, the counterweight 532 slides radially outward from the top block 53. Sliding towards the inclined direction of the wedge surface 531 will generate an incremental axial displacement relative to the top block 53, and the end face of the sliding cavity 51 will hinder the further radial sliding of the counterweight block 532. This causes the centrifugal force driving the radial sliding of the counterweight block 532 to be converted into an axial compressive force on the end face of the sliding cavity 51. This axial compressive force is further converted into an axial force driving the female rotor 2 to move towards the exhaust end cover 15 through the inclined structure of the radial wedge surface 531. This, in turn, drives the cylindrical roller bearing 54 to axially compress the disc spring 55 and move axially with the female rotor 2, increasing the gap between the female rotor 2 and the male rotor 3, thereby suppressing the decrease in gap caused by thermal expansion. The length of the disc spring 55 extending out of the spring mounting groove 52 is the maximum axial sliding distance that the female rotor 2 can achieve. When the rotational speed of the female rotor 2 decreases, and the centrifugal force generated by the counterweight 532 is less than the radial force of the radial return spring 533, the radial return spring 533 will pull the counterweight 532 back to its initial position along the slide rail 534. At the same time, the disc spring 55 will generate an axial force to push the cylindrical roller bearing 54, thereby driving the female rotor 2 back to its initial position, achieving adaptive adjustment of the meshing clearance. During the axial movement of the female rotor 2, the driven gear 61 and the journal 6 of the female rotor 2 are connected by a guide key 62. This connection method can stably transmit torque and also allow the female rotor 2 to slide axially relative to the driven gear 61.

[0027] Example 2 Please see Figures 8-9An adjusting block 535, which can slide along the slide rail 534 and be fixed on the slide rail 534, is also fixedly mounted on the slide rail 534. By using adjusting blocks 535 of different diameters, the radial sliding distance of the counterweight block 532 within the radial wedge surface 531 is limited. The adjusting block 535 is a block structure adapted to the cross-sectional shape of the slide rail 534, and is designed with different radial thicknesses according to the required limiting distance. Multiple sets of threaded holes are uniformly machined circumferentially on the top block 53 at the position corresponding to the slide rail 534. The adjusting block 535 has positioning holes adapted to the threaded holes. Multiple sets of axial bolts are passed through the positioning holes and screwed into the threaded holes of the top block 53 to achieve the fixed assembly of the adjusting block 535 on the slide rail 534. When it is necessary to change the maximum radial movement distance of the counterweight 532, first loosen the axial bolts, remove the original adjusting block 535 from the slide rail 534, and select an adjusting block 535 with the corresponding radial thickness according to the thermal expansion gap requirements of the female rotor 2 and male rotor 3 at different speeds. Embed it into the target position of the slide rail 534, align the positioning hole with the threaded hole of the top block 53, and tighten the axial bolts to complete the replacement and fixing of the adjusting block 535. The reason for designing the adjusting block 535 is that the thermal expansion of the female rotor 2 and male rotor 3 varies under different speed conditions, and the required maximum axial movement distance of the female rotor 2 also needs to be adjusted accordingly. The maximum radial sliding distance of the counterweight 532 directly determines the total amount of axial force conversion. By replacing the adjusting block 535 with one of different radial thicknesses, the limit stroke can be flexibly adjusted without modifying the disc spring 55, counterweight 532, and other core components, adapting to diverse working conditions and reducing equipment debugging steps.

[0028] Please see Figures 8-9 When it is necessary to adapt to the clearance requirements of the female rotor 2 and male rotor 3 after thermal expansion at different speeds to change the maximum axial sliding distance of the female rotor 2, the adjusting block 535 on the slide rail 534 can be moved and fixed in the target position, thereby limiting the maximum radial sliding distance of the counterweight block 532 along the radial wedge surface 531. When the axial movement distance of the female rotor 2 does not match the clearance size required after thermal expansion, the maximum radial sliding stroke of the counterweight block 532 can be changed by adjusting the assembly position of the adjusting block 535 on the slide rail 534. After the adjustment is in place, the adjusting block 535 is fixed. When the counterweight block 532 slides radially outward along the radial wedge surface 531 to the adjusting block 535 under centrifugal force, the adjusting block 535 will prevent the counterweight block 532 from continuing to move radially outward, thereby avoiding excessive compression of the end face of the sliding cavity 51 by the counterweight block 532, and ensuring that the maximum axial sliding distance of the female rotor 2 matches the clearance requirements after thermal expansion.

[0029] 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.

[0030] 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. A variable frequency oil-free screw blower, comprising a blower housing (1), wherein an intake end cover (14) is fixedly mounted on one side of the blower housing (1), and an exhaust end cover (15) is fixedly mounted on the other side of the blower housing (1). A compression chamber (11) is machined inside the blower housing (1), and a female rotor (2) and a male rotor (3) for mutually meshing and compressing gas are rotatably mounted inside the compression chamber (11). The two ends of the female rotor (2) and the male rotor (3) are respectively rotatably connected to the exhaust end cover (15) and the intake end cover (14), characterized in that: A variable frequency motor (4) for driving the male rotor (3) to rotate is also connected to one side of the male rotor (3). The surfaces of the female rotor (2) and the male rotor (3) are coated with a protective coating to prevent thermal expansion of the female rotor (2) and the male rotor (3). A compensation structure (5) is provided between the two ends of the female rotor (2) and the blower housing (1) to compensate for the gap between the female rotor (2) and the male rotor (3) by axial movement caused by thermal expansion of the male rotor (3) and the female rotor (2).

2. The variable frequency oil-free screw blower according to claim 1, characterized in that: A gap is provided between the meshing surfaces of the helical teeth of the female rotor (2) and the male rotor (3), and the protective coating is a ceramic coating.

3. The variable frequency oil-free screw blower according to claim 1, characterized in that: The intake end cover (14) has an axial sliding cavity (51) coaxial with the female rotor (2). The compensation structure (5) includes an annular top block (53), a cylindrical roller bearing (54), and a disc spring (55). The cylindrical roller bearing (54) is coaxially assembled in the sliding cavity (51), and its inner ring is coaxially interference-fitted with the female rotor (2). The top block (53) is coaxially arranged on the side of the cylindrical roller bearing (54) away from the compression cavity (11). The top block (53) is coaxially fixedly connected to the female rotor (2) and abuts against the end face of the sliding cavity (51). Two or more sets of inclined radial wedge surfaces (531) distributed circumferentially are provided on the abutting end face of the top block (53) and the sliding cavity (51). The small end of the radial wedge surface (531) is close to the radial outer side of the top block (53), and the large end is close to the female rotor. (2) The radial wedge surface (531) is slidably fitted with a counterweight (532) adapted to its tilt angle. The end face of the sliding cavity (51) near the compression cavity (11) is provided with a spring mounting groove (52). The disc spring (55) is fixedly fitted in the spring mounting groove (52) and one end of it is connected to the end face of the cylindrical roller bearing (54) away from the top block (53). When the female rotor (2) synchronously drives the top block (53) and the counterweight (532) to rotate coaxially, the counterweight (532) is subjected to centrifugal force and slides towards the radial outside of the top block (53) along the radial wedge surface (531), and generates an axial displacement increment relative to the top block (53), thereby generating an axial force on the end face of the sliding cavity (51) and pushing the top block (53) to move in the axial direction away from the end face of the sliding cavity (51).

4. A variable frequency oil-free screw blower according to claim 3, characterized in that: The cylindrical roller bearing (54) is axially slidably connected to the sliding cavity (51), the axial length of the disc spring (55) is greater than the length of the spring mounting groove (52), and the difference between the axial length of the disc spring (55) and the axial length of the spring mounting groove (52) is the maximum axial movement length of the female rotor (2).

5. A variable frequency oil-free screw blower according to claim 3, characterized in that: A sealing ring (56) is also provided between the disc spring (55) and the cylindrical roller bearing (54).

6. A variable frequency oil-free screw blower according to claim 3, characterized in that: A radially arranged radial return spring (533) is assembled between the counterweight (532) and the radial wedge (531). One end of the return spring (533) is connected to the side of the counterweight (532) facing the axis of the female rotor (2), and the other end of the return spring (533) is fixedly connected to the inner wall of the large end of the radial wedge (531). The radial preload of the return spring (533) is adapted to the centrifugal force threshold of the counterweight (532). When the centrifugal force generated by the rotation of the female rotor (2) is greater than the radial elastic force of the return spring (533), the counterweight (532) slides radially outward from the top block (53) along the inclined direction of the radial wedge (531) and is converted into axial force by the radial compression of the radial wedge (531).

7. A variable frequency oil-free screw blower according to claim 6, characterized in that: The radial wedge surface (531) is also machined with a slide rail (534) parallel to its inclined direction. The counterweight (532) is slidably connected to the slide rail (534), and the return spring (533) is embedded in the slide rail (534) and connected to the counterweight (532). The end face angle of the counterweight (532) facing the radial wedge surface (531) is parallel to the radial wedge surface (531), and the end face angle of the counterweight (532) facing the end face of the sliding cavity (51) is parallel to the end face of the sliding cavity (51).

8. A variable frequency oil-free screw blower according to claim 7, characterized in that: An adjusting block (535) that can slide along the direction of the slide rail (534) and can be fixed on the slide rail (534) is also fixedly mounted.

9. A variable frequency oil-free screw blower according to claim 1, characterized in that: The female rotor (2) has journals (6) machined on both sides. The journal (6) near the intake end cover (14) is fitted with the compensation structure (5). The journal (6) near the exhaust end cover (15) is provided with a driven gear (61) that transmits the rotational force of the male rotor (3) to the journal (6) and drives the female rotor (2) to rotate synchronously. The male rotor (3) near the exhaust end cover (15) is coaxially fixed with the driven gear. (61) A meshing drive gear (7); and a sealing structure is provided between the male rotor (3) and the exhaust end cover (15) and the intake end cover (14), and a guide key (62) is provided between the driven gear (61) and the journal (6) to allow the journal (6) to slide axially relative to the driven gear (61), and an axial fixing structure is provided between the driven gear (61) and the exhaust end cover (15) to restrict the axial sliding of the driven gear (61).

10. A variable frequency oil-free screw blower according to claim 1, characterized in that: The blower housing (1) has an intake end seat (12) at the top and an exhaust end seat (13) at the bottom. The intake end seat (12) and the exhaust end seat (13) are connected to the compression chamber (11). An intake pipe (16) is connected to the intake end seat (12), and an exhaust pipe (17) is fixedly connected to the exhaust end seat (13). A filter module is provided on the intake pipe (16). A support base (18) is fixedly connected to the bottom of the variable frequency motor (4). The blower housing (1) is fixedly assembled on the support base (18) through the exhaust end cover (15) and the intake end cover (14). The male rotor (3) has one end near the exhaust end cover (15) that passes through the exhaust end cover (15) and is coaxially fixedly connected to the drive end of the variable frequency motor (4).

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