Bidirectional multi-stage rotor and roots pump

Abstract

The utility model discloses a kind of bidirectional multistage rotor and roots pump, it is related to vacuum pump technical field, the bidirectional multistage rotor and roots pump provided by the utility model, by arranging the compression ratio gradually decreasing secondary blade unit to the axial two ends symmetrically in the middle part of rotating shaft with first blade unit, the bidirectional symmetric rotor working area is constructed, so that the axial force generated in gas compression process is mutually offset, bearing load is significantly reduced, so as to allow rotor to operate stably at higher speed;The structure simultaneously realizes the multistage gradual compression of gas, effectively widens the working pressure range, significantly improves the gas extraction efficiency.

Description

Technical Field

[0001] This utility model relates to the field of vacuum pump technology, specifically to a bidirectional multi-stage rotor and Roots pump. Background Technology

[0002] Roots vacuum pumps, as vacuum-generating devices based on the principle of volumetric transfer, utilize a pair of high-speed, synchronously reversing rotors engaging non-contactly within the pump chamber to transport gas from the inlet to the outlet. Traditional single-stage Roots pumps, due to their limited compression ratio, are prone to overheating and performance degradation under high inlet pressures, limiting their operating pressure range and pumping efficiency. To address this, multi-stage Roots pump structures have emerged, typically employing multiple Roots impeller units connected in series to form a pump group. Through progressive compression, the upstream pump operates at higher pressures, while the downstream pump continues compression at lower pressures, thus expanding the pump group's operating pressure range and improving pumping stability and efficiency from low to high vacuum. This multi-stage series structure alleviates, to some extent, the insufficient compression ratio and overheating problems of single-stage pumps, while also allowing the system to start at higher inlet pressures and shortening the vacuuming time.

[0003] However, most existing multistage Roots pumps adopt a unidirectional series arrangement, that is, the gas compression process is carried out along a single axis, which causes the rotor to generate a large unidirectional axial force during operation, causing the bearing to bear high stress and limiting the increase of rotor speed. The speed of traditional multistage Roots pumps is usually no more than 6000 r / min, which in turn restricts the further improvement of its pumping speed and ultimate vacuum.

[0004] Therefore, how to further optimize the rotor structure and pump body layout while ensuring high compression ratio, wide operating pressure range and rapid start-up characteristics, to achieve effective balance of axial force, support higher speed operation, and take into account structural compactness and manufacturing cost, has become a key issue that urgently needs to be solved in the field of Roots vacuum pump technology. Utility Model Content

[0005] The purpose of this invention is to address the aforementioned problems by providing a bidirectional multi-stage rotor and Roots pump. By placing the primary blade unit in the middle of the rotating shaft and symmetrically arranging secondary blade units with progressively decreasing compression ratios at both ends of the axial direction, a bidirectional symmetrical rotor working area is constructed. This allows the axial forces generated during gas compression to cancel each other out, significantly reducing bearing load and enabling the rotor to operate stably at higher speeds. This structure also achieves multi-stage progressive gas compression, effectively widening the working pressure range and significantly improving pumping efficiency.

[0006] The technical solution adopted in this utility model is as follows: A bidirectional multi-stage rotor includes a rotating shaft and multiple compression blade units disposed on the rotating shaft. Each compression blade unit includes a primary blade unit and multiple secondary blade units. The primary blade unit is located in the middle of the rotating shaft, and two rotor working areas are formed at both ends along the axial direction from the primary blade unit. Several secondary blade units are arranged along the axial direction in each rotor working area. The compression ratio of the secondary blade units is less than that of the primary blade units, and the compression ratio of the secondary blade units gradually decreases as they approach the shaft end.

[0007] By adopting the above technical solution, by setting the first-stage blade unit in the middle of the rotating shaft and symmetrically arranging multiple secondary blade units at both ends along the axial direction, a bidirectional rotor working area is formed, which allows the gas compression process to occur simultaneously in both the left and right directions. This effectively counteracts the unidirectional axial force generated during rotor operation, reduces the bearing load, and allows the rotor to operate at higher speeds. Combined with the multi-stage compression ratio decreasing design, the working pressure range is expanded, and the pumping efficiency and ultimate vacuum are improved.

[0008] Furthermore, the cross-sectional shapes of the compression blade units are consistent, and the thickness of the compression blade unit with a large compression ratio is greater than that of the compression blade unit with a small compression ratio.

[0009] By adopting the above technical solution, the thickness can be adjusted to adapt to different compression ratios while maintaining a consistent cross-sectional shape of the compression blade unit. This simplifies the manufacturing process, ensures the continuity and stability of airflow in each stage of the blade unit under high-speed rotation, optimizes compression efficiency, and reduces energy loss.

[0010] Furthermore, the compression blade unit is fitted onto the rotating shaft through a sleeve hole, and a separation unit is provided between adjacent compression blade units. Axial limiting devices that can limit the axial displacement of the compression blade units are respectively provided at both ends of the rotating shaft. The paired axial limiting devices cooperate with each other to limit multiple compression blade units on the rotating shaft.

[0011] By adopting the above technical solution, the modular arrangement of the compression blade unit is realized through the sleeve assembly and the partition unit. The axial limiting device effectively prevents the axial movement of the compression blade unit under high speed operation, improves the rigidity and reliability of the rotor structure, and is suitable for high speed conditions.

[0012] Furthermore, the axial limiting device includes a limiting sleeve fitted around the outer periphery of the rotating shaft and an external thread on the rotating shaft. The limiting sleeve has a limiting hole, and the inner wall of the limiting hole has an internal thread. The limiting sleeve can be fitted onto the rotating shaft through the limiting hole, and the axial position of the limiting sleeve on the rotating shaft is limited by the engagement of the internal thread and the external thread.

[0013] Thanks to the above technical solution, the threaded limiting sleeve provides an adjustable and secure axial fixing method, which facilitates assembly and maintenance, ensures the precise positioning of the compression blade unit on the shaft, and adapts to dynamic loads at high speeds.

[0014] Furthermore, the dividing unit is a shoulder of the rotating shaft or a bushing fitted around the outer periphery of the rotating shaft.

[0015] By adopting the above technical solution, using shaft shoulders or bushings as separation units, the structure is simple and the cost is low. It effectively maintains the axial spacing between compression blade units and ensures the independence of each level of compression blade unit.

[0016] Furthermore, the rotating shaft is provided with a circumferential limiting structure that can restrict the circumferential rotation of the compression blade unit.

[0017] Thanks to the above technical solution, the circumferential limiting structure prevents the relative rotation of the compression blade unit on the rotating shaft, thereby improving the pump's operational stability and lifespan.

[0018] Furthermore, the circumferential limiting structure includes a first positioning groove on the circumferential surface of the rotating shaft, a second positioning groove on the inner wall of the compression blade unit sleeve hole, and a positioning key assembled between the first positioning groove and the second positioning groove.

[0019] By adopting the above technical solution, the circumferential fixation of the compression blade unit and the rotating shaft is achieved through the cooperation of the positioning groove and the positioning key, the torque transmission is reliable, the slippage or misalignment of the compression blade unit is avoided, and the synchronization and efficiency of the compression process are guaranteed.

[0020] Furthermore, the two rotor working areas are symmetrically arranged, and each rotor working area is provided with four secondary blade units. Each rotor working area and the primary blade unit cooperate with each other to form a bidirectional five-stage compression structure.

[0021] Thanks to the above technical solution, the gas is compressed step by step from the middle to both ends through the bidirectional five-stage compression structure, which significantly improves the overall compression ratio and pumping speed. At the same time, the symmetrical arrangement balances the axial force, supports higher speed operation, and improves the overall performance of the vacuum pump.

[0022] A bidirectional multistage Roots pump includes a pump body, in which a pair of bidirectional multistage rotors are assembled. The compression blade units of the pair of bidirectional multistage rotors mesh with each other to form a vane pump assembly. The pump body has multiple working chambers, each corresponding to a vane pump assembly. The pump body has an air inlet and two air outlets. The air inlet is connected to the working chamber corresponding to the first-stage vane unit, and the two air outlets are respectively connected to the two working chambers closest to the shaft end.

[0023] Thanks to the above technical solutions, the multi-working-chamber and inlet / outlet layout optimizes gas flow, improves pumping efficiency and vacuum level, and the compact structure reduces installation space and leakage risk.

[0024] Furthermore, the pump body includes a first cylinder and a second cylinder that can be mated with each other. Multiple shaft grooves are provided along the length direction on the mating surfaces of the first and second cylinders. These shaft grooves are parallel to each other and spaced apart. The spacing between the shaft grooves matches the size of the compression blade unit. Working grooves are provided between the shaft grooves located on the same axis along the length direction of the pump body. The shaft grooves on the first cylinder correspond to the shaft grooves on the second cylinder, and each working groove on the first cylinder corresponds one-to-one with a working groove on the second cylinder. When the first and second cylinders are mated, the shaft grooves on the first cylinder and the shaft grooves on the second cylinder cooperate to form a shaft assembly cavity that can be matched with the rotating shaft. The working grooves on the first cylinder and the corresponding working grooves on the second cylinder cooperate to form a working cavity that can be matched with the compression blade unit.

[0025] By adopting the above technical solution, the manufacturing and assembly process of the pump body is simplified through the matching design of the first cylinder and the second cylinder. The precise matching of the shaft groove and the working groove ensures the accurate positioning of the rotating shaft and the compression blade unit, forming a well-sealed working chamber, reducing gas leakage, and improving the reliability and efficiency of the pump. At the same time, the modular structure facilitates maintenance and cost control.

[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are: By placing the primary blade unit in the middle of the rotating shaft and symmetrically arranging multiple secondary blade units at both ends along the axial direction to form a bidirectional rotor working area, the unidirectional axial force generated by the rotor operation is effectively counteracted, reducing the bearing load and thus supporting the rotor to operate at higher speeds. Combined with a multi-stage compression ratio decreasing design, the working pressure range is expanded, and the pumping efficiency and ultimate vacuum are improved. At the same time, the paired bidirectional multi-stage rotors and pump body optimize the gas flow path, and the compact structure reduces installation space and leakage risk, thus improving the overall reliability and performance of the vacuum pump. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the bidirectional multi-stage rotor of this utility model; Figure 2 This is a schematic diagram of the structure of the compression blade unit of this utility model; Figure 3 This is a cross-sectional view of the circumferential limiting structure of this utility model; Figure 4 This is a schematic diagram of the structure of the bidirectional multistage Roots pump of this utility model; Figure 5 This is a top view of the second cylinder block of this utility model; Figure 6 This is a schematic diagram of the structure of the impeller pump assembly of this utility model.

[0028] The markings in the diagram are: 1-rotating shaft, 2-compression blade unit, 201-sleeve hole, 202-first-stage blade unit, 203-secondary blade unit, 3-separation unit, 4-circumferential limiting structure, 401-first positioning groove, 402-second positioning groove, 403-positioning key, 5-axial limiting device, 6-pump body, 601-first cylinder, 602-second cylinder, 603-shaft groove, 604-working groove, 605-inlet, 606-outlet. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings.

[0030] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0031] Example 1 A bidirectional multi-stage rotor, such as Figures 1-3As shown, the device includes a rotating shaft 1 and multiple compression blade units 2 disposed on the rotating shaft 1. Each compression blade unit 2 includes a primary blade unit 202 and multiple secondary blade units 203. The primary blade unit 202 is located in the middle of the rotating shaft 1, forming two rotor working areas at both ends along the axial direction. Each rotor working area has four secondary blade units 203 arranged axially. The compression ratio of each secondary blade unit 203 is less than that of the primary blade unit 202, and the compression ratio of the secondary blade unit 203 gradually decreases as it approaches the shaft end. Specifically, by placing the primary blade unit 202 in the middle of the rotating shaft 1 and symmetrically arranging multiple secondary blade units 203 at both ends along the axial direction, a bidirectional rotor working area is formed. This allows the gas compression process to occur simultaneously in both directions, effectively counteracting the unidirectional axial force generated during rotor operation, reducing bearing load, and allowing the rotor to operate at higher speeds. Combined with a multi-stage decreasing compression ratio design, this expands the working pressure range and improves pumping efficiency and ultimate vacuum. In other embodiments, the rotor working area can be asymmetrically arranged, for example, the first-stage blade unit 202 is not in the exact center, or the number of secondary blade units 203 is different at both ends, to adapt to specific compression requirements; furthermore, the compression ratio can decrease in a stepwise manner rather than continuously and gradually. It should be further explained that when the rotor rotates, the first-stage blade unit 202 compresses the gas starting from the middle of the rotating shaft 1, and the resulting high-pressure gas flows axially to both ends, sequentially passing through each stage of secondary blade units 203 for progressive compression. Due to the bidirectional symmetrical design, the axial forces in the left and right directions are equal in magnitude and opposite in direction, thus canceling each other out and reducing the axial load on the bearings, enabling the rotor to operate stably at high speeds.

[0032] The compression blade units 2 have a consistent cross-sectional shape, with the thickness of the compression blade unit 2 having a higher compression ratio than that of the compression blade unit 2 having a lower compression ratio. Specifically, by maintaining a consistent cross-sectional shape while adjusting the thickness to accommodate different compression ratios, the manufacturing process is simplified, while ensuring the continuity and stability of airflow at each stage of the blade unit under high-speed rotation, optimizing compression efficiency, and reducing energy loss. In other embodiments, the cross-sectional shape of the compression blade unit 2 can also be slightly different, for example, by changing the blade angle or profile to accommodate the compression ratio. It should be further noted that an increase in the thickness of the compression blade unit 2 generally means an increase in the radial height or axial width of the blade, thereby providing a higher compression ratio at the same rotational speed. Due to the consistent cross-sectional shape, the gas flow between stages is smoother, reducing turbulence and pressure loss, and improving overall efficiency.

[0033] The compression blade unit 2 is fitted onto the rotating shaft 1 through the sleeve hole 201. A separator unit 3 is provided between adjacent compression blade units 2. Axial limiting devices 5 are respectively provided at both ends of the rotating shaft 1 to restrict the axial displacement of the compression blade units 2. The paired axial limiting devices 5 cooperate to restrict multiple compression blade units 2 to the rotating shaft 1. Specifically, the modular arrangement of the compression blade units 2 is achieved through the fitting of the sleeve hole 201 and the separator unit 3. The axial limiting devices 5 effectively prevent axial movement of the compression blade units under high-speed operation, improving the rigidity and reliability of the rotor structure, and making it suitable for high-speed operating conditions. In other embodiments, the separator unit 3 can also be an integral structure with the compression blade unit 2, such as a flange. It should be further explained that during assembly, the compression blade units 2 are sequentially fitted onto the rotating shaft 1, with the axial spacing maintained by the separator unit 3, and then fixed at both ends by the axial limiting devices 5. This ensures that the compression blade units 2 will not move axially due to centrifugal force or gas force during high-speed rotation, thereby maintaining stable compression performance.

[0034] The axial limiting device 5 includes a limiting sleeve fitted around the outer circumference of the rotating shaft 1 and an external thread on the rotating shaft 1. The limiting sleeve has a limiting hole with an internal thread on its inner wall. The limiting sleeve can be fitted onto the rotating shaft 1 through the limiting hole, and the axial position of the limiting sleeve on the rotating shaft 1 is limited by the engagement of the internal and external threads. Specifically, the threaded limiting sleeve provides an adjustable and secure axial fixing method, facilitating assembly and maintenance, ensuring the precise positioning of the compression blade unit 2 on the shaft, and adapting to dynamic loads at high speeds. During installation, the limiting sleeve is screwed into the external thread of the rotating shaft 1, and the axial pressure is controlled by the tightening torque, thereby pressing the stack of compression blade units 2 tightly. The self-locking characteristic of the thread prevents loosening during rotation, ensuring long-term operational stability.

[0035] The separating unit 3 is either a shoulder of the rotating shaft 1 or a bushing fitted around the outer periphery of the rotating shaft 1. Specifically, using a shoulder or bushing as the separating unit 3 results in a simple structure, low cost, and effective maintenance of the axial spacing between the compression blade units 2, ensuring the independence of each stage of the compression blade unit 2. In other embodiments, the separating unit 3 can be a shim, a spacer ring, or a boss integrated into the compression blade unit 2, providing different spacing adjustment flexibility. It should be further explained that the shoulder is a step directly machined onto the rotating shaft 1, while the bushing is a separate part fitted onto the shaft. Both can accurately control the position between the compression blade units 2, prevent mutual interference, and ensure that each stage of compression takes place in an independent working chamber.

[0036] The rotating shaft 1 is provided with a circumferential limiting structure 4 that restricts the circumferential rotation of the compression blade unit 2. Specifically, the circumferential limiting structure 4 prevents the relative rotation of the compression blade unit 2 on the rotating shaft 1, ensuring that the compression blade unit 2 rotates synchronously with the rotating shaft 1, thereby improving the working stability and service life of the pump.

[0037] The circumferential limiting structure 4 includes a first positioning groove 401 on the circumferential surface of the rotating shaft 1, a second positioning groove 402 on the inner wall of the sleeve hole 201 of the compression blade unit 2, and a positioning key 403 assembled between the first positioning groove 401 and the second positioning groove 402. Specifically, the circumferential fixation of the compression blade unit 2 and the rotating shaft 1 is achieved through the cooperation of the positioning grooves and the positioning key 403, ensuring reliable torque transmission, preventing slippage or misalignment of the compression blade unit 2, and guaranteeing the synchronicity and efficiency of the compression process. In other embodiments, multiple keys can also be used to increase torque transmission capability. It should be further explained that during assembly, the positioning key 403 is embedded in the grooves of the rotating shaft 1 and the compression blade unit 2 to form a tight fit, so that the compression blade unit 2 rotates together with the shaft, ensuring that the phase of each stage of the compression blade unit 2 is consistent, thereby optimizing the continuity of gas compression.

[0038] The two rotor working areas are symmetrically arranged, and each rotor working area is provided with four secondary blade units 203. Each rotor working area and the primary blade unit 202 cooperate to form a bidirectional five-stage compression structure. Specifically, through the bidirectional five-stage compression structure, gas is compressed stepwise from the middle to both ends, significantly improving the overall compression ratio and pumping speed. At the same time, the symmetrical arrangement balances the axial force, supports higher speed operation, and improves the overall performance of the vacuum pump. In other embodiments, the number of secondary blade units 203 can be different, for example, three or five at each end, forming different stages of compression structure to adapt to different compression ratio requirements. It should be further explained that in the five-stage compression, gas is drawn in and initially compressed from the primary blade unit 202 in the middle, then flows to both ends, is compressed stepwise by the four secondary blade units 203, and finally discharged from the shaft end. The bidirectional design balances the axial force, allowing the use of lighter bearings and higher speeds.

[0039] Example 2 A bidirectional multistage Roots pump, such as Figures 4-6As shown, the pump includes a pump body 6, within which are assembled pairs of the aforementioned bidirectional multi-stage rotors. The compression blade units 2 of the paired bidirectional multi-stage rotors mesh with each other to form a blade pump assembly. The pump body 6 has multiple working chambers, each corresponding to a blade pump assembly. The pump body 6 has an air inlet 605 and two air outlets 606. The air inlet 605 communicates with the working chamber corresponding to the first-stage blade unit 202, and the two air outlets 606 communicate with the two working chambers closest to the shaft end of the rotating shaft 1, respectively. Specifically, the multi-working-chamber and air inlet / outlet layout optimizes gas flow, improves pumping efficiency and vacuum, and the compact structure reduces installation space and leakage risk. Furthermore, during pump operation, gas enters through the central air inlet 605, is compressed by the first-stage blade unit 202, and then distributed to the working chambers at both ends. After being progressively compressed by the secondary blade units 203, it is discharged from the air outlets 606 at both ends. This layout reduces flow path length and pressure loss, and increases pumping speed.

[0040] The pump body 6 includes a first cylinder 601 and a second cylinder 602 that can be mated with each other. Multiple shaft grooves 603 are provided along the length direction on the mating surfaces of the first cylinder 601 and the second cylinder 602. The multiple shaft grooves 603 are parallel to each other and spaced apart. The spacing of the multiple shaft grooves 603 matches the size of the compression blade unit 2. A working groove 604 is provided between the multiple shaft grooves 603 located on the same axis along the length direction of the pump body 6. The shaft grooves 603 on the first cylinder 601 and the shaft grooves 603 on the second cylinder 602... The shaft groove 603 corresponds to the working groove 604 on the first cylinder 601, and each working groove 604 on the second cylinder 602 corresponds one-to-one. When the first cylinder 601 and the second cylinder 602 are engaged, the shaft groove 603 on the first cylinder 601 and the shaft groove 603 on the second cylinder 602 cooperate to form a shaft assembly cavity that can be matched with the rotating shaft 1. The working groove 604 on the first cylinder 601 and the corresponding working groove 604 on the second cylinder 602 cooperate to form a working cavity that can be matched with the compression vane unit 2. Specifically, the engagement design of the first cylinder 601 and the second cylinder 602 simplifies the manufacturing and assembly process of the pump body 6. The precise matching of the shaft groove 603 and the working groove 604 ensures the accurate positioning of the rotating shaft 1 and the compression vane unit 2, forming a well-sealed working cavity, reducing gas leakage, and improving the reliability and efficiency of the pump. At the same time, the modular structure facilitates maintenance and cost control. In other embodiments, the pump body 6 can be composed of more parts, such as multiple segments. When assembling the pump body 6, the first cylinder 601 and the second cylinder 602 are mated, the shaft groove 603 forms a circular hole to accommodate the rotating shaft 1, and the working groove 604 forms a cylindrical cavity to accommodate the compression blade unit 2. The mating surfaces are sealed with gaskets to ensure airtightness, thereby creating an independent working chamber and optimizing the compression process.

[0041] This document uses specific embodiments to illustrate the principles and implementation methods of this utility model. The descriptions of the embodiments above are only intended to help understand the method and core ideas of this utility model. It should be noted that those skilled in the art can make various improvements and modifications to this utility model without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

[0042] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0043] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

Claims

1. A bidirectional multi-stage rotor, comprising a rotating shaft and a plurality of compression blade units disposed on the rotating shaft, characterized in that, The compression blade unit includes a primary blade unit and multiple secondary blade units. The primary blade unit is located in the middle of the rotating shaft, and two rotor working areas are formed at both ends along the axial direction from the primary blade unit. Several secondary blade units are arranged along the axial direction in each rotor working area. The compression ratio of the secondary blade unit is less than that of the primary blade unit, and the compression ratio of the secondary blade unit gradually decreases as it approaches the shaft end.

2. The bidirectional multi-stage rotor as described in claim 1, characterized in that, The compression blade units have the same cross-sectional shape, and the thickness of the compression blade unit with a larger compression ratio is greater than that of the compression blade unit with a smaller compression ratio.

3. The bidirectional multi-stage rotor as described in claim 1, characterized in that, The compression blade unit is fitted onto the rotating shaft through a sleeve hole. A separation unit is provided between adjacent compression blade units. Axial limiting devices that can limit the axial displacement of the compression blade units are respectively provided at both ends of the rotating shaft. The paired axial limiting devices cooperate to restrict multiple compression blade units on the rotating shaft.

4. The bidirectional multi-stage rotor as described in claim 3, characterized in that, The axial limiting device includes a limiting sleeve fitted around the outer circumference of the rotating shaft and an external thread on the rotating shaft. The limiting sleeve has a limiting hole, and the inner wall of the limiting hole has an internal thread. The limiting sleeve can be fitted onto the rotating shaft through the limiting hole, and the axial position of the limiting sleeve on the rotating shaft is limited by the engagement of the internal thread and the external thread.

5. The bidirectional multi-stage rotor as described in claim 3, characterized in that, The dividing unit is a shoulder of the rotating shaft or a sleeve fitted around the outer periphery of the rotating shaft.

6. The bidirectional multi-stage rotor as described in claim 3, characterized in that, The rotating shaft is provided with a circumferential limiting structure that can restrict the circumferential rotation of the compression blade unit.

7. The bidirectional multi-stage rotor as described in claim 6, characterized in that, The circumferential limiting structure includes a first positioning groove on the circumferential surface of the rotating shaft, a second positioning groove on the inner wall of the compression blade unit sleeve hole, and a positioning key assembled between the first positioning groove and the second positioning groove.

8. The bidirectional multi-stage rotor as described in claim 1, characterized in that, Another rotor working area is symmetrically arranged, and each rotor working area is provided with four secondary blade units. Each rotor working area and the primary blade unit cooperate with each other to form a bidirectional five-stage compression structure.

9. A bidirectional multistage Roots pump, characterized in that, The pump body includes a pump body in which a pair of bidirectional multi-stage rotors as described in any one of claims 1-8 are assembled. The compression blade units of the pair of bidirectional multi-stage rotors mesh with each other to form a blade pump assembly. The pump body is provided with a plurality of working chambers, each working chamber corresponding to a blade pump assembly. The pump body is provided with an air inlet and two air outlets. The air inlet is connected to the working chamber corresponding to the first-stage blade unit, and the two air outlets are respectively connected to the two working chambers closest to the shaft end.

10. The bidirectional multistage Roots pump as described in claim 9, characterized in that, The pump body includes a first cylinder and a second cylinder that can be mated with each other. Multiple shaft grooves are provided along the length of the mating surfaces of the first and second cylinders. These shaft grooves are parallel to each other and spaced apart. The spacing between the shaft grooves matches the size of the compression blade unit. Working grooves are provided between the shaft grooves located on the same axis along the length of the pump body. The shaft grooves on the first cylinder correspond to the shaft grooves on the second cylinder, and each working groove on the first cylinder corresponds one-to-one with a working groove on the second cylinder. When the first and second cylinders are mated, the shaft grooves on the first cylinder and the shaft grooves on the second cylinder cooperate to form a shaft assembly cavity that can be matched with the rotating shaft. The working grooves on the first cylinder and the corresponding working grooves on the second cylinder cooperate to form a working cavity that can be matched with the compression blade unit.

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