Multi-stage roots vacuum pump

Abstract

The invention discloses a multistage roots vacuum pump which is characterized by comprising a pump body and two groups of mutually meshed rotor parts rotationally arranged in the pump body, the rotor component comprises a connecting shaft and a roots rotor component arranged on the connecting shaft, the roots rotor component comprises at least three stages of roots rotor bodies which are sequentially arranged in the axis direction of the connecting shaft, and the sizes of part or all of the roots rotor bodies are sequentially reduced from the first end to the second end; pump body cavities used for containing the roots rotor components are formed in the pump body, part of the pump body cavities or all the pump body cavities become smaller in sequence from the first end to the second end, and each stage of roots rotor body is matched with the pump body cavity at the corresponding position; a partition plate is further arranged in the pump body cavity between every two adjacent roots rotor bodies, and the partition plates are detachably connected with the pump body. According to the invention, the convenience of assembly and debugging is improved, and the manufacturing difficulty and cost are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of vacuum pumps, especially to a kind of multi-stage Roots vacuum pump. BACKGROUND

[0002] Roots vacuum pump is a kind of rotary displacement vacuum pump, can work in wide pressure range, and there is no oil in pump cavity, it has been widely used in semiconductor, electronics, petroleum, chemical industry and other industries vacuum system.Roots vacuum pump is a kind of double rotor compression machinery, the axis of two rotors is parallel to each other.Rotor is combined by impeller and shaft, there is small gap between impeller, between impeller and shell and wallboard, to avoid mutual contact.Two rotors are driven by a pair of synchronous gears through prime mover, and rotate at equal speed in opposite directions, so as to realize gas from import into, and then from export.

[0003] Roots vacuum pump generally includes single-stage Roots vacuum pump, double-stage Roots vacuum pump and multi-stage Roots vacuum pump (three or more stages), conventional multi-stage Roots vacuum pump, such as application number "202320709235.2", patent name "a kind of multi-stage Roots vacuum pump", in this structure, there are the following deficiencies: 1, pump shell adopts upper and lower split pump shell assembly, pump body needs to be sealed first when sealing, then the two side end covers are sealed, the sealing method of sealing ring is difficult to realize, generally only sealing glue can be used, which will greatly increase the risk of leakage; 2, when preparing, the preparation process is more complex, and the preparation cost is higher; 3, when assembling pump body, not only the axial gap between pump cavity and rotor needs to be considered, but also the circumferential gap between pump cavity and rotor needs to be considered, due to the upper and lower half structure of pump body, the assembly and debugging difficulty is high due to tolerance during preparation, and the assembly and debugging effect is poor, which not only affects the service life, but also affects the vacuum effect; 4, when the vacuum pump is used, especially in harsh environment, if more sundries enter the vacuum pump, it needs to be disassembled and cleaned, and subsequent complex assembly and debugging need to be carried out. SUMMARY

[0004] The present application aims to provide a kind of multi-stage Roots vacuum pump, by using the structure, the preparation difficulty of multi-stage Roots vacuum pump can be reduced, the assembly difficulty is also reduced, and the vacuum effect can be guaranteed.

[0005] To achieve the above object, the technical scheme adopted by the present application is: a kind of multi-stage Roots vacuum pump, including pump body and two groups of mutually meshing rotor components rotatingly arranged in the pump body; The rotor component comprises a shaft and a Roots rotor component arranged on the shaft, the Roots rotor component comprises at least three Roots rotor bodies arranged in sequence along the axis direction of the shaft, and the sizes of part or all of the Roots rotor bodies gradually decrease from the first end to the second end; The pump body is provided with a pump body cavity for accommodating the Roots rotor component, and part or all of the pump body cavity gradually decreases in size in a stepped manner from the first end to the second end, and each level of the Roots rotor body is matched with the corresponding position of the pump body cavity; The pump body comprises a main body and end covers arranged at both ends of the main body, and the pump body cavity is completely arranged in the main body, or the pump body cavity is arranged in the main body and the end covers on both sides; The pump body cavity between adjacent Roots rotor bodies is further provided with a partition plate, the outer surface of the partition plate is close to or in contact with the inner wall of the pump body cavity, and the partition plate is detachably connected with the pump body.

[0006] In the above technical solution, the adjacent partition plates and the partition plates at the most side edges and the end faces of the pump body cavity form pump body sub-cavities, respectively, and each level of the Roots rotor body in the two groups of rotor components is arranged in a pump body sub-cavity.

[0007] In the above technical solution, the pump body cavity is completely arranged in the main body, and the two ends of the pump body cavity penetrate the two ends of the main body, respectively.

[0008] In the above technical solution, the main body is an integral structure. And / or, the end cover is an integral structure.

[0009] In the above technical solution, the main body is provided with a main pump body cavity penetrating the two ends, the end face of the end cover is provided with an end pump body cavity opposite to the end of the main pump body cavity, and the main pump body cavity and the end pump body cavity form the pump body cavity.

[0010] In the above technical solution, the Roots rotor bodies at the two ends of the Roots rotor component are arranged in the end pump body cavities of the two groups of end covers, and the other Roots rotor bodies are arranged in the main pump body cavity.

[0011] In the above technical solution, the end cover comprises a first end cover connected with the first end of the main body and a second end cover connected with the second end of the main body, the size of the end pump body cavity on the second end cover is less than or equal to the size of the second end of the main pump body cavity, and the size of the first end of the main pump body cavity is less than or equal to the size of the end pump body cavity on the first end cover.

[0012] In the above technical solution, the main pump body cavity comprises at least two chambers, a plurality of the chambers are in communication with each other, and the sizes of a plurality of the chambers gradually decrease from the first end to the second end. And / or, the size of the chamber located at the first end of the main body is less than or equal to the size of the end pump body cavity on the first end cover, and the size of the chamber located at the second end of the main body is greater than or equal to the size of the end pump body cavity on the second end cover.

[0013] In the above technical solution, the pump body is provided with an air inlet and an air outlet. The air inlet is connected to the first end of the pump body cavity, and the air outlet is connected to the second end of the pump body cavity.

[0014] In the above technical solution, the pump body is provided with a plurality of inlets and outlets communicating with the pump body cavity. Each inlet and outlet is respectively arranged opposite to two meshing Roots rotor bodies, and the inlet and outlet are respectively arranged on both sides of the two meshing Roots rotor bodies. The pump body outside the pump body cavity is also provided with several connecting channels, each of which is connected to an inlet and an outlet on the adjacent side.

[0015] In the above technical solution, the outer wall of the pump body is provided with a through groove communicating with the connecting channel, and a sealing plate that seals the through groove is detachably installed on the pump body.

[0016] In the above technical solution, the partition includes an upper partition and a lower partition arranged opposite to each other. The bottom of the upper partition is provided with two upper arc-shaped notches that match the outer surfaces above the two connecting shafts respectively. The top of the lower partition is provided with two lower arc-shaped notches that match the outer surfaces below the two connecting shafts respectively. The upper partition and the lower partition are detachably connected to the pump body by fasteners.

[0017] In the above technical solution, the outer surface of the partition is provided with a plurality of mounting holes, which are positioned opposite the inner wall of the pump body cavity; The outer wall of the pump body is provided with a plurality of connection holes communicating with the pump body cavity. Each mounting hole is positioned opposite to one of the connection holes, and the inner end of the fastener passes through the connection hole and is connected to the mounting hole.

[0018] In the above technical solution, the Roots rotor component and the coupling shaft are an integral structure; Alternatively, the Roots rotor component and the connecting shaft may be separate structures.

[0019] In the above technical solution, the two ends of the connecting shaft are rotatably connected to the two ends of the pump body, and a driving part is provided on one side of the pump body. The driving part is used to drive the two rotor components to rotate.

[0020] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. In this invention, the rotor component includes a multi-stage Roots rotor with progressively smaller dimensions, and the pump body cavity is adapted to the Roots rotor. The use of a Roots rotor with variable diameter dimensions facilitates assembly and also improves the vacuum level of the vacuum pump. 2. The pump body in this invention includes an integral main body and end caps at both ends of the main body. The pump body cavity inside the main body is connected at both ends. Compared with the previous two-half pump shell structure, it is easier to process, has higher processing accuracy, and is easier to assemble. 3. In this invention, since the main body is an integral structure and the dimensions of adjacent Roots rotor bodies are different, the rotor components and pump body can be quickly assembled. At the same time, in order to separate the Roots rotor bodies, the adjacent Roots rotor bodies and pump body cavity are separated by partitions, and the partitions are locked and limited on the pump body by fasteners. This facilitates quick assembly and ensures the strength of the vacuum pump. 4. In this invention, the rotor component can be an integral structure or a separate structure. Compared with the separate structure, the rotor component with an integral structure has higher precision and higher assembly precision with the pump body, which effectively ensures the assembly quality of the product, ensures the vacuuming effect, reduces the maintenance rate, and extends the service life. 5. In this invention, the connection between the connecting channel and the outer wall of the pump body is sealed with a sealing plate, which facilitates the preparation of the main body and makes subsequent cleaning easier, thereby extending the service life and reducing the maintenance rate. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure in this invention; Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure; Figure 3 yes Figure 1 A cross-sectional view of another location in the structure; Figure 4 This is a schematic diagram of the structure of the two sets of rotor components connected to the partition in this invention; Figure 5 This is a schematic diagram of the rotor component in this invention; Figure 6 This is a schematic diagram of the pump body in this invention; Figure 7 yes Figure 6 A schematic diagram of the cross-sectional structure; Figure 8 yes Figure 7 A schematic diagram of the three-dimensional structure; Figure 9 This is a schematic diagram of the structure of the main body in this invention (a partition is installed inside the main body); Figure 10 yes Figure 9A cross-sectional structural diagram.

[0022] The components are: 1. Pump body; 11. Pump body cavity; 12. Main body; 13. End cover; 14. Connecting hole; 15. Air inlet; 16. Air outlet; 17. Inlet; 18. Outlet; 19. Connecting channel; 101. Sealing plate; 110. Through groove; 111. First-stage pump body sub-cavity; 112. Second-stage pump body sub-cavity; 113. Third-stage pump body sub-cavity; 114. Fourth-stage pump body sub-cavity; 115. Fifth-stage pump body sub-cavity; 116. Sixth-stage pump body sub-cavity; 131. First end cap; 132. Second end cap; 2. Rotor assembly; 21. Coupling; 22. Roots rotor assembly; 23. Roots rotor body; 231. First-stage Roots rotor; 232. Second-stage Roots rotor; 233. Third-stage Roots rotor; 234. Fourth-stage Roots rotor; 235. Fifth-stage Roots rotor; 236. Sixth-stage Roots rotor; 3. Partition; 31. Upper partition; 32. Lower partition; 33. Upper arc-shaped notch; 34. Arc-shaped notch; 35. Mounting hole; 4. Drive unit. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example 1: See Figures 1-10 As shown, a multi-stage Roots vacuum pump includes a pump body 1 and two sets of meshing rotor components 2 rotatably disposed within the pump body 1. The rotor component 2 includes a connecting shaft and a Roots rotor component 22 disposed on the connecting shaft 21. The Roots rotor component 22 includes at least three stages of Roots rotor bodies 23 arranged sequentially along the axial direction of the connecting shaft 21. The size of some or all of the Roots rotor bodies 23 decreases sequentially from the first end toward the second end. The pump body 1 is provided with a pump body cavity 11 for accommodating the Roots rotor component 22. Part or all of the pump body cavity 11 gradually decreases in size from the first end to the second end in a stepped manner, and each stage of the Roots rotor 23 is respectively matched with the pump body cavity 11 at the corresponding position. The pump body 1 includes a main body 12 and end caps 13 respectively disposed at both ends of the main body 12. The pump body cavity 11 is completely disposed within the main body 12, or the pump body cavity 11 is disposed within the main body 12 and the end caps 13 on both sides. A partition 3 is also provided in the pump body cavity 11 between adjacent Roots rotor bodies 23. The outer surface of the partition 3 is close to or in contact with the inner wall of the pump body cavity 11, and the partition 3 is detachably connected to the pump body 1.

[0024] In this invention, the pump body cavity can be completely disposed within the main body, or it can be disposed in the middle of the main body with both ends disposed within end caps on both sides. Regardless of the structure, both ends of the pump body cavity are connected to both ends of the main body. In this structure, during assembly, the rotor component can be quickly assembled by inserting it into the pump body cavity from one end of the main body. More preferably, since the gap between the assembled vacuum pump rotor component and the inner wall of the pump body cavity is relatively small, if all the Roots rotors are of the same size, jamming may occur during assembly, or the inner wall of the pump body cavity and the Roots rotors may be scratched. Therefore, in this embodiment, the multi-stage Roots rotors are of variable diameter, decreasing in size from the first end to the second end, in order to accommodate... Figure 2 Taking the direction as an example, with the first end at the right end and the second end at the left end, and assuming that the dimensions of all the Roots rotor bodies decrease sequentially from the first end to the second end, the outer dimensions of the right-side Roots rotor body are larger than the outer dimensions of the adjacent left-side Roots rotor body, and the right-side dimension of the pump body cavity is larger than the adjacent left-side dimension. During assembly, the left end of the rotor component is inserted from the right end of the main body. Because the left-side Roots rotor body is smaller and the right-side pump body cavity is larger, it can be easily and quickly inserted into the pump body cavity. Only when the corresponding Roots rotor body is inserted into the pump body cavity at the required installation position will the dimensions of the two parts match (the required matching distance is relatively short), thus effectively preventing scratches on the pump body cavity and the Roots rotor body, and making installation convenient without any jamming problems. Simultaneously, since a multi-stage Roots rotor is provided, the pump body cavity also needs to be divided into multiple sections. Each pump body cavity contains two mutually enclosing Roots rotors. Therefore, a partition is also provided, positioned between adjacent Roots rotors. The shape of the partition matches the shape of the pump body cavity at its installation location. The outer surface of the partition has a micro-gap or contact with the inner wall of the pump body cavity. Preferably, for ease of manufacturing, a micro-gap exists between the outer surface of the partition and the inner wall of the pump body cavity. The presence of this micro-gap facilitates assembly, disassembly, and maintenance, while not affecting normal vacuuming. The micro-gap is relatively small, allowing only a small amount of gas to move between the partition and the pump body cavity, thus having minimal impact on the vacuuming effect. More preferably, an elastic sealing ring can be provided on the outer surface of the partition, contacting the inner wall of the pump body cavity to achieve a sealing effect.

[0025] The adjacent partitions and the partition between the outermost partition and the pump body cavity end face respectively form a pump body sub-cavity, and each of the meshing Roots rotor bodies in the two sets of rotor components is respectively disposed in a pump body sub-cavity.

[0026] In this embodiment, taking a six-stage Roots vacuum pump as an example, each coupling is equipped with a six-stage Roots rotor body, with attachment Figure 2For example, the six-stage Roots rotor bodies are arranged alternately on the outer surface of the connecting shaft from left to right or from right to left. The connecting shafts on both sides of the Roots rotor assembly are rotatably connected to the end caps on both sides. The six-stage Roots rotor bodies include, in sequence, a first-stage Roots rotor body 231, a second-stage Roots rotor body 232, a third-stage Roots rotor body 233, a fourth-stage Roots rotor body 234, a fifth-stage Roots rotor body 235, and a sixth-stage Roots rotor body 236 arranged alternately from right to left. The outer dimensions of the first-stage Roots rotor body are larger than those of the second-stage Roots rotor body, the second-stage Roots rotor body is larger than those of the third-stage Roots rotor body, the third-stage Roots rotor body is larger than those of the fourth-stage Roots rotor body, the fourth-stage Roots rotor body is larger than those of the fifth-stage Roots rotor body, and the fifth-stage Roots rotor body is larger than those of the sixth-stage Roots rotor body. Similarly, the pump body sub-cavities are also divided by partitions into a first-stage pump body sub-cavity 111, a second-stage pump body sub-cavity 112, a third-stage pump body sub-cavity 113, a fourth-stage pump body sub-cavity 114, a fifth-stage pump body sub-cavity 115, and a sixth-stage pump body sub-cavity 116 arranged from right to left. The sizes of the first-stage, second-stage, third-stage, fourth-stage, fifth-stage, and sixth-stage pump body sub-cavities are arranged in descending order, and the first-stage, second-stage, third-stage, fourth-stage, fifth-stage, and sixth-stage pump body sub-cavities are arranged in a stepped manner from large to small and interconnected.

[0027] In this embodiment, each connecting shaft is equipped with a six-stage Roots rotor, resulting in five empty spaces between adjacent rotors. A set of partitions is installed in each of these five spaces. The connecting shafts of both sets of rotor components are inserted into the five sets of partitions, or the partitions are secured to the connecting shafts of the two sets of rotor components. Preferably, the five sets of partitions, from right to left, include a primary partition, a secondary partition, a tertiary partition, a quaternary partition, and a quinary partition. The primary partition is located within the primary pump body sub-cavity, and its external dimensions are larger than those of the secondary pump body sub-cavity. The outer edge of the left side of the primary partition abuts against (or is close to) the left side wall of the primary pump body sub-cavity. The secondary partition is located within the secondary pump body sub-cavity, and its external dimensions are larger than those of the tertiary pump body sub-cavity. The outer edge of the left side of the secondary partition abuts against (or is close to) the secondary pump body sub-cavity. The third-stage diaphragm is located within the third-stage pump body sub-cavity. The outer dimensions of the third-stage diaphragm are larger than those of the fourth-stage pump body sub-cavity. The outer edge of the left side of the third-stage diaphragm abuts against (or is close to) the left side wall of the third-stage pump body sub-cavity. The fourth-stage diaphragm is located within the fourth-stage pump body sub-cavity. The outer dimensions of the fourth-stage diaphragm are larger than those of the fifth-stage pump body sub-cavity. The outer edge of the left side of the fourth-stage diaphragm abuts against (or is close to) the left side wall of the fourth-stage pump body sub-cavity. The fifth-stage diaphragm is located within the fifth-stage pump body sub-cavity. The outer dimensions of the fifth-stage diaphragm are larger than those of the sixth-stage pump body sub-cavity. The outer edge of the left side of the fifth-stage diaphragm abuts against (or is close to) the left side wall of the fifth-stage pump body sub-cavity. The left side of the sixth-stage pump body sub-cavity is limited by the left end face of the pump body cavity, and the right side of the first-stage pump body sub-cavity is limited by the right end face of the pump body cavity.

[0028] The partition 3 includes an upper partition 31 and a lower partition 32 arranged opposite to each other. The bottom of the upper partition 31 has two upper arc-shaped notches 33 that match the upper outer surfaces of the two connecting shafts 21, respectively. The top of the lower partition 32 has two lower arc-shaped notches 34 that match the lower outer surfaces of the two connecting shafts 21, respectively. The upper partition 31 and the lower partition 32 are detachably connected to the pump body 1 by fasteners. Each upper arc-shaped notch is opposite to a lower arc-shaped notch, and an upper arc-shaped notch and a lower arc-shaped notch form a circular hole. The diameter of this hole is exactly matched with the outer diameter of the connecting shaft between adjacent Roots rotor bodies, or the outer diameter of this hole is slightly larger than the outer diameter of the connecting shaft between adjacent Roots rotor bodies to prevent friction between the connecting shaft and the partition when the connecting shaft rotates. Even if the diameter of the hole is slightly larger than the diameter of the connecting shaft at the corresponding position, it will only be slightly larger and will not cause much air leakage. A sealing ring or other sealing element can also be set between the hole and the connecting shaft to prevent air leakage without affecting the rotation of the connecting shaft. Meanwhile, the bottom surfaces of the upper and lower partitions are in contact. A sealing strip can be installed between the bottom and top surfaces of the upper and lower partitions to completely seal the gap at their contact point. Alternatively, a sealing strip can be omitted, with higher machining precision on the outer surfaces of the upper and lower partitions to ensure minimal gap between them after contact, minimizing or eliminating air leakage, or ensuring that any leakage does not affect vacuuming. Preferably, a micro-gap exists between the partition and the inner wall of the pump body cavity. An elastic sealing ring can be installed at the outer edge of the left end face of the partition, with its left end abutting against the left side wall of the corresponding pump body cavity, thus providing a seal and preventing leakage. Alternatively, a groove can be provided on the outer surface of the partition, with an elastic sealing ring installed within it. The outer surface of the elastic sealing ring abuts against the outer surface of the pump body cavity. This method is optimal as it does not occupy the axial space of the pump body cavity.

[0029] In this method, during assembly, the two sets of rotor components are first meshed and assembled, and the partition assembly is then assembled with the two sets of rotor components. Alternatively, the leftmost partition assembly can be assembled first. Then, the assembled rotor components and one set of partitions are moved to the left and inserted into the pump body cavity from the right end of the main body. After the leftmost partition assembly is in the pump body cavity, another partition assembly is assembled, and then moved to the left and inserted into the pump body cavity. This process is repeated until all partitions are in the pump body cavity. Finally, the upper and lower partitions are connected to the pump body using fasteners, and the end covers on both sides are installed. Alternatively, all partitions and the two sets of rotor components can be assembled and then installed into the pump body.

[0030] The outer surface of the partition 3 is provided with a plurality of mounting holes 35, which are positioned opposite the inner wall of the pump body cavity 11. The outer wall of the pump body 1 is provided with a plurality of connection holes 14 communicating with the pump body cavity 11. Each mounting hole 35 is provided opposite to one of the connection holes 14. The inner end of the fastener passes through the connection hole 14 and is connected to the mounting hole 35.

[0031] In this embodiment, bolts are used as fasteners, with screw holes for mounting and through holes or screw holes for connecting. At least one mounting hole is provided on the top surface of the upper partition and at least one mounting hole is provided on the bottom surface of the lower partition. The number of connecting holes matches the number of mounting holes. The inner end of the bolt passes through the connecting hole and the mounting hole and is screwed in, thereby locking the partition in place within the pump body cavity. This ensures its strength and prevents lateral displacement during operation (the Roots rotor and the partition will not contact each other, thus ensuring that the rotor will not come into contact with the partition during rotation and will not be worn). For subsequent disassembly, simply separate the bolts and the partition, then remove the end cover to remove the rotor assembly and the partition together from the main pump body cavity.

[0032] In this invention, the main body is a one-piece structure; the end cap is also a one-piece structure. The one-piece structure of the main body ensures a unified machining datum during manufacturing, and since it consists of only one component, the machining accuracy is higher. This results in better assembly accuracy and effect when assembled with the rotor component, and lower debugging difficulty (in previous structures, the pump casing consisted of two parts; due to machining tolerances and other issues, it was difficult to manufacture the two pump casings to be completely identical. Combined with the machining tolerances of the rotor component, this led to higher assembly and debugging difficulty and lower accuracy).

[0033] In this invention, the pump body cavity is configured in two ways: First, the pump body cavity is completely housed within the main body, with both ends of the cavity penetrating through both ends of the main body. In this method, the main body is relatively long, and the end caps seal both ends of the pump body cavity and also provide rotational support for the connecting shaft. In this method, the dimensions of all Roots rotors decrease sequentially from the first end to the second end; that is, the external dimensions of the first-stage, second-stage, third-stage, fourth-stage, fifth-stage, and sixth-stage Roots rotors decrease sequentially. Similarly, the dimensions of the first-stage, second-stage, third-stage, fourth-stage, fifth-stage, and sixth-stage pump body sub-cavities also decrease sequentially.

[0034] The second type: The main body has a main pump cavity extending through both ends, and the end cap has an end pump cavity facing the main pump cavity on its end face. The main pump cavity and the end pump cavity constitute the pump cavity. In this embodiment, the second structure is adopted. In this structure, the length of the main body is slightly shorter than that of the main body in the first structure. With a shorter length, its processing accuracy is easier to control, the processing difficulty is also lower, and it can achieve the same high precision as processing longer products. The processing cost of the shorter body is also lower.

[0035] The Roots rotor bodies at both ends of the Roots rotor assembly are respectively disposed in the end pump body cavities of the two sets of end covers, while the other Roots rotor bodies are disposed in the main pump body cavity.

[0036] That is: the first-stage Roots rotor is located in the end pump cavity on the right, the sixth-stage Roots rotor is located in the end pump cavity on the left, and the second-stage, third-stage, fourth-stage, and fifth-stage Roots rotors are located in the main pump cavity.

[0037] Additionally, the following structure exists: the dimensions of some Roots rotor bodies decrease sequentially from the first end to the second end, and the dimensions of some pump body chambers also decrease sequentially from the first end to the second end. In this structure, the two sets of Roots rotor bodies at the first end have the same external dimensions, and the dimensions of the multi-stage Roots rotor bodies decrease sequentially from the second set of Roots rotor bodies at the first end to the second end. The external dimensions of the first set of Roots rotor bodies at the first end are consistent with the external dimensions of the second set of Roots rotor bodies; that is, the external dimensions of the first-stage Roots rotor body and the second-stage Roots rotor body are consistent, and the external dimensions of the third-stage Roots rotor body are smaller than those of the second-stage Roots rotor body. In terms of dimensions, the external dimensions of the fourth-stage Roots rotor are smaller than those of the third-stage Roots rotor, the external dimensions of the fifth-stage Roots rotor are smaller than those of the fourth-stage Roots rotor, and the external dimensions of the sixth-stage Roots rotor are smaller than those of the fifth-stage Roots rotor. In this method, the external dimensions of the first-stage diaphragm are larger than those of the first-stage Roots rotor. A receiving groove can be set on the inner surface of the left end of the pump body cavity at the end of the right end cover to accommodate the external dimensions of the first-stage diaphragm. The left side of the first-stage diaphragm is limited by the right end face of the main body, thereby enabling the external dimensions of the first-stage Roots rotor to be consistent with those of the second-stage Roots rotor.

[0038] Similarly, the external dimensions of the six-stage Roots rotor can be the same as those of the five-stage Roots rotor. A receiving groove is provided on the inner right surface of the end pump body cavity at the left end cap to accommodate the external fifth-stage diaphragm. The right end of the diaphragm is limited by the left end face of the main body. In this structure, the Roots rotor component includes two sets of end Roots rotors and at least one set of middle Roots rotors disposed between the two sets of end Roots rotors. The external dimensions of the middle Roots rotors decrease sequentially from the first end to the second end. The dimensions of the end Roots rotors disposed at the first end of the connecting shaft are equal to the dimensions of the middle Roots rotors at the first end, and the dimensions of the short plate Roots rotors disposed at the second end of the connecting shaft are equal to the dimensions of the middle Roots rotors at the second end. This structure is suitable for structures where both end caps have end pump body cavities.

[0039] If the pump body cavity is entirely located within the main body, the Roots rotor assembly includes at least three stages of Roots rotor bodies arranged sequentially along the axial direction of the connecting shaft. The dimensions of all the Roots rotor bodies decrease sequentially from the first end to the second end. Of course, this structure also applies if the pump body cavity is located in both the main body and the end cover.

[0040] See Figures 6-8 As shown, the end cap 13 includes a first end cap 131 connected to the first end of the main body 12 and a second end cap 132 connected to the second end of the main body 12. The size of the end pump cavity on the second end cap 132 is less than or equal to the size of the second end of the main pump cavity, and the size of the first end of the main pump cavity is less than or equal to the size of the end pump cavity on the first end cap. The end pump cavity of the first end cap is a first-stage pump cavity, the end pump cavity of the second end cap is a sixth-stage pump cavity, and the main pump cavity includes interconnected second-stage, third-stage, fourth-stage, and fifth-stage pump cavities.

[0041] In this invention, the Roots rotor assembly includes at least three stages (groups) of Roots rotor bodies. Theoretically, more than 10 stages of Roots rotor bodies can be set, but the manufacturing requirements for the rotor assembly will be higher, and the manufacturing cost will also be higher (longer length, requiring higher resistance to deformation). The choice can be made according to the actual situation. Of course, since the smaller the chamber of the pump body sub-cavity at the rear end, the airflow will be more rapid, the vacuuming effect will be better, and the vacuum degree will be better.

[0042] The main pump body cavity includes at least two chambers, and the multiple chambers are interconnected. The size of the multiple chambers decreases sequentially from the first end to the second end. The size of the chamber located at the first end of the main body is less than or equal to the size of the end pump body cavity on the first end cover, and the size of the chamber located at the second end of the main body is greater than or equal to the size of the end pump body cavity on the second end cover.

[0043] In this embodiment, the main pump body cavity includes four chambers, namely the secondary chamber, the tertiary chamber, the quaternary chamber, and the quinary chamber, which are sequentially formed by the partitions to form the secondary pump body sub-cavities, the tertiary pump body sub-cavities, the quaternary pump body sub-cavities, and the quinary pump body sub-cavities.

[0044] The pump body 1 is provided with an air inlet 15 and an air outlet 16. The air inlet 15 is connected to the first end of the pump body cavity 11, and the air outlet 16 is connected to the second end of the pump body cavity 11. In this invention, the air inlet is connected to the top of the first-stage pump body sub-cavity, and the air outlet is connected to the bottom of the sixth-stage pump body sub-cavity. The air inlet and air outlet are used to connect the pump body cavity to the outside world, that is, to connect the pump body cavity to the outer wall of the pump body.

[0045] See Figures 6-8 As shown, the pump body 1 is provided with a plurality of inlets 17 and outlets 18 communicating with the pump body cavity 11. Each inlet 17 and outlet 18 is respectively positioned opposite to two meshing Roots rotor bodies 23, and the inlet 17 and outlet 18 are respectively positioned on both sides of the two meshing Roots rotor bodies 23. The pump body 1 outside the pump body cavity 11 is also provided with a number of connecting channels 19, each of the connecting channels 19 being connected to an inlet 17 and an outlet 18 on the adjacent side.

[0046] In this embodiment, taking a pump body with six sub-cavities as an example, there are 5 inlets and 5 outlets, with 5 connecting channels. The 5 inlets are designated as secondary, tertiary, quaternary, quinary, and sixth stage inlets, respectively, located at the top of the secondary, tertiary, quaternary, quinary, and sixth stage pump body sub-cavities, above the corresponding meshing Roots rotors, and connected to the top of the respective sub-cavities. The 5 outlets are designated as primary, secondary, tertiary, quaternary, and sixth stage outlets, respectively, located at the bottom of the primary, secondary, tertiary, quaternary, and sixth stage pump body sub-cavities, above the corresponding meshing Roots rotors, and connected to the bottom of the respective sub-cavities. The air inlet is located at the top of the first-stage pump body sub-cavity, above the two meshing first-stage Roots rotors. The air outlet is located at the bottom of the sixth-stage pump body sub-cavity, below the two meshing sixth-stage Roots rotors. The connecting channels are for the first, second, third, fourth, and fifth stages. The first-stage connecting channel connects the first-stage outlet to the second-stage inlet; the second-stage connecting channel connects the second-stage outlet to the third-stage inlet; the third-stage connecting channel connects the third-stage outlet to the fourth-stage inlet; the fourth-stage connecting channel connects the fourth-stage outlet to the fifth-stage inlet; and the fifth-stage connecting channel connects the fifth-stage outlet to the sixth-stage inlet.When the vacuum pump is working, the two sets of rotor components rotate, drawing external fluid (such as gas) from the inlet into the first-stage pump body sub-cavity. Then, through the meshing two sets of first-stage Roots rotors, the fluid flows downwards into the first-stage pump body sub-cavity below the two sets of first-stage Roots rotors. It then flows through the first-stage outlet, first-stage connecting channel, and second-stage inlet into the second-stage pump body sub-cavity above the two sets of second-stage Roots rotors. The fluid then flows downwards again through the two sets of meshing second-stage Roots rotors into the second-stage pump body sub-cavity below the two sets of second-stage Roots rotors. It then flows through the second-stage outlet, second-stage connecting channel, and third-stage inlet into the third-stage pump body sub-cavity above the two sets of third-stage Roots rotors. Finally, through the two sets of meshing third-stage Roots rotors, the fluid flows downwards into the third-stage pump body sub-cavity below the two sets of third-stage Roots rotors, and then flows through the third-stage outlet. The fluid enters the fourth-stage pump body sub-cavity above the two sets of four-stage Roots rotors through the third-stage connecting channel and the fourth-stage inlet. Then, driven downwards by the two sets of meshing four-stage Roots rotors, the fluid flows into the fourth-stage pump body sub-cavity below the two sets of four-stage Roots rotors. From there, it enters the fifth-stage pump body sub-cavity above the two sets of five-stage Roots rotors through the fourth-stage outlet, the fourth-stage connecting channel, and the fifth-stage inlet. The fluid then flows downwards again by the two sets of meshing five-stage Roots rotors, flowing into the fifth-stage pump body sub-cavity below the two sets of five-stage Roots rotors. Finally, it exits through the air outlet, thus achieving the vacuum pumping action. If more stages of Roots rotors are set, more inlet, outlet, and connection channels will be set; if fewer stages of Roots rotors are set, fewer inlet, outlet, and connection channels will be set.

[0047] In this embodiment, the air inlet and the first-stage outlet are located on the right end cover (first end cover), the air outlet and the sixth-stage inlet are located on the left end cover (second end cover), and the other inlets and outlets are located on the main body.

[0048] In this embodiment, a primary connecting channel is located on the right end cap and the right end of the main body. The left end of the primary connecting channel inside the end cap communicates with the right end of the primary connecting channel inside the main body. A sealing ring is provided at the connection point to ensure the sealing effect of the primary connecting channel after the end cap and the main body are connected. Similarly, a fifth-level connecting channel is located on the left end cap and the left end of the main body. The right end of the fifth-level connecting channel inside the left end cap communicates with the left end of the fifth-level connecting channel inside the main body. A sealing ring is provided at the connection point to ensure the sealing effect of the fifth-level connecting channel after the end cap and the main body are connected. Simultaneously, a sealing ring is also provided at the connection point between the end cap and the main body to ensure a tight seal.

[0049] See Figure 1 , 6 More preferably, as described in section -8, the outer wall of the pump body 1 is provided with a through groove 110 communicating with the connecting channel 19, and a sealing plate 101 is detachably installed on the pump body 1 to seal the through groove 110. To facilitate the processing of the connecting channel, especially since the main body is an integral structure and the connecting channel is located outside the pump body cavity (i.e., inside the main body), a through groove communicating with the connecting channel is also provided for easier processing. The through groove can be provided on the front end face, rear end face, or both the front and rear end faces. The main body can have one through groove communicating with all the connecting channels on the main body, or multiple through grooves, each communicating with each connecting channel on the main body. Each end cap also has a through groove communicating with the connecting channel inside the end cap, facilitating the processing of the main body and end caps. Subsequently, fasteners (e.g., bolts) are used to connect the sealing plate and the pump body, thereby sealing the through groove and preventing the connecting channel from communicating with the outside of the pump body. Preferably, a sealing ring is provided at the connection between the sealing plate and the pump body to ensure a sealing effect.

[0050] At the same time, if the working environment of the vacuum pump is harsh, the sealing plate can be opened to clean or wash the inside of the vacuum pump, such as the pump body cavity and the first-stage rotor components, from the through groove, air inlet and air outlet (using fluids or other cleaning agents). This also facilitates maintenance, as it does not require disassembling the rotor components and pump body, nor does it require reinstallation and debugging, making it easy to inspect and clean.

[0051] In this invention, the Roots rotor component and the coupling are an integral structure; or the Roots rotor component and the coupling are separate structures. Preferably, the Roots rotor component and the coupling are an integral structure, which eliminates the need to separately manufacture and assemble the Roots rotor component and the coupling, resulting in higher processing precision, higher subsequent assembly precision, and easier debugging.

[0052] The two ends of the connecting shaft 21 are rotatably connected to the two ends of the pump body 1 (in this embodiment, the two ends of the pump body are rotatably connected to the end covers on both sides). A drive unit 4 is also provided on one side of the pump body 1, which drives the two rotor components to rotate. The drive unit is preferably a motor, which drives one connecting shaft to rotate. Meshing gears (or other transmission mechanisms) can be provided at the ends of the two connecting shafts. When one connecting shaft is driven to rotate, the meshing gears can drive the other connecting shaft to rotate, thereby realizing the mutual rotation of the two sets of rotor components. The drive unit is mounted on a set of end covers; preferably, the drive unit is mounted on the end cover near the air inlet side.

[0053] The outer end of the end cover is also provided with a bearing mounting cavity that communicates with the end pump body cavity for mounting a bearing, which in turn provides rotational support for the end of the connecting shaft. The bearing mounting cavity on the right side is sealed by the drive unit, while a cover plate is installed on the left end cover to shield and seal the bearing mounting cavity on the left side.

[0054] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0055] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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. For instance, the two components can be mechanically connected by contact or abutting; they can also be directly hooked or connected by an intermediate medium; or they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

Claims

1. A multi-stage Roots vacuum pump, characterized by: The pump body and two sets of mutually meshing rotor components rotatingly arranged in the pump body; The rotor components include a shaft and Roots rotor components arranged on the shaft, the Roots rotor components include at least three Roots rotor bodies arranged along the axis of the shaft in sequence, and the sizes of some or all of the Roots rotor bodies gradually decrease from the first end to the second end; The pump body is provided with a pump cavity for accommodating the Roots rotor components, and the pump cavity gradually decreases in size from the first end to the second end in a stepped manner, and each level of the Roots rotor body is matched with the corresponding position of the pump cavity; The pump body includes a main body and end covers arranged at both ends of the main body, and the pump cavity is arranged in the main body or in the main body and the end covers; The pump cavity between adjacent Roots rotor bodies is further provided with a partition plate, the outer surface of the partition plate is close to or in contact with the inner wall of the pump cavity, and the partition plate is detachably connected with the pump body.

2. - Multistage Roots vacuum pump according to claim 1, characterized in that: Adjacent partition plates and the end faces of the most side partition plates and the pump cavity form pump sub-cavities, respectively, and each level of the Roots rotor body in the two sets of rotor components is arranged in a pump sub-cavity.

3. The multi-stage Roots pump of claim 1, wherein: The pump cavity is arranged in the main body, and the two ends of the pump cavity are penetrated through the two ends of the main body.

4. The multi-stage Roots pump of claim 1, wherein: The main body is an integral structure; And / or, the end cover is an integral structure.

5. The multi-stage Roots pump of claim 1, wherein: The main body is provided with a main pump cavity penetrating through both ends, and the end face of the end cover is provided with an end pump cavity opposite to the end of the main pump cavity, and the main pump cavity and the end pump cavity form the pump cavity.

6. A multi-stage Roots pump according to claim 5, characterized in that: The Roots rotor bodies at both ends of the Roots rotor components are arranged in the end pump cavities of the two sets of end covers, and the other Roots rotor bodies are arranged in the main pump cavity.

7. A multi-stage Roots pump according to claim 5, characterized in that: The end cover includes a first end cover connected with the first end of the main body and a second end cover connected with the second end of the main body, the size of the end pump cavity on the second end cover is less than or equal to the size of the second end of the main pump cavity, and the size of the first end of the main pump cavity is less than or equal to the size of the end pump cavity on the first end cover.

8. A multi-stage Roots pump according to claim 7, characterized in that: The main pump cavity includes at least two chambers, and the chambers are in communication with each other, and the sizes of the chambers gradually decrease from the first end to the second end; And / or, the size of the chamber arranged at the first end of the main body is less than or equal to the size of the end pump cavity on the first end cover, and the size of the chamber arranged at the second end of the main body is greater than or equal to the size of the end pump cavity on the second end cover.

9. The multi-stage Roots pump of claim 1, wherein: The pump body is provided with an air inlet and an air outlet, the air inlet is in communication with the first end of the pump cavity, and the air outlet is in communication with the second end of the pump cavity.

10. The multi-stage Roots pump of claim 1, wherein: The pump body is provided with a plurality of inlets and outlets in communication with the pump cavity, each inlet and outlet is opposite to two Roots rotor bodies meshing with each other, and the inlets and outlets are arranged on both sides of the two Roots rotor bodies meshing with each other; The pump body is further provided with a plurality of connection channels outside the pump cavity, and each connection channel is in communication with an inlet and an adjacent outlet.

11. A multi-stage Roots pump according to claim 10, characterized in that: The outer wall of the pump body is provided with a through slot in communication with the connecting channel, and a sealing plate detachably mounted on the pump body is arranged to seal the through slot.

12. The multi-stage Roots pump of claim 1, wherein: The partition plate comprises oppositely arranged upper and lower partition plates, the bottom of the upper partition plate is provided with two upper arc-shaped notches respectively matched with the upper outer surfaces of the two connecting shafts, the top of the lower partition plate is provided with two lower arc-shaped notches respectively matched with the lower outer surfaces of the two connecting shafts, and the upper and lower partition plates are detachably connected with the pump body through fasteners.

13. A multi-stage Roots pump according to claim 12, characterized in that: The outer surface of the partition plate is provided with a plurality of mounting holes, and the mounting holes are arranged opposite to the inner wall of the pump body cavity; The outer wall of the pump body is provided with a plurality of connecting holes in communication with the pump body cavity, and each mounting hole is arranged opposite to one connecting hole, and the inner end of the fastener is connected with the mounting hole through the connecting hole.

14. The multi-stage Roots pump of claim 1, wherein: The Roots rotor component and the connecting shaft are in an integral structure. Or, the Roots rotor component and the connecting shaft are in a split structure.

15. The multi-stage Roots pump of claim 1, wherein: The two ends of the connecting shaft are rotatably connected with the two ends of the pump body, and the pump body is further provided with a driving portion on one side, and the driving portion is used to drive the two rotor components to rotate.

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