Vacuum pump assembly for increased process by-product capacity

Abstract

The present disclosure relates to a vacuum pump assembly with improved process by-product capacity, comprising a front bearing plate, an upper housing, a lower housing, a long rotor, a short rotor, and a rear bearing plate, the long rotor and the short rotor respectively rotating in opposite directions about their own axes, the axes of the long rotor and the short rotor being parallel to each other, the long rotor and the short rotor respectively comprising multi-stage rotors arranged at intervals in the axial direction of the long rotor and the short rotor's respective axes, the multi-stage long rotor and the short rotor being intermeshed with each other, and the intermeshing non-critical surfaces of the rotors being provided with dust collection grooves. The present disclosure improves process by-product capacity and effectively avoids pump seizures and wear caused by adhesion of process by-products.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This disclosure claims priority to a Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on March 23, 2023, bearing application number 202310292694.X, for "Vacuum pump assembly and dry vacuum pump for improving process by-product capacity," the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to the field of vacuum pumping, and more particularly to vacuum pump assemblies that provide improved process by-product capacity. [Background technology]

[0003] The purpose of a vacuum pump is to extract gas molecules from a vacuum chamber to reduce the gas pressure inside the vacuum chamber and achieve the required vacuum level. It is mainly used in the pharmaceutical and chemical industries, vacuum deposition, vacuum drying, surface treatment, vacuum smelting, ceramic manufacturing, food packaging, milking, beverages, etc.

[0004] The two axes of the vacuum pump's rotors are parallel to each other. The rotors are composed of an impeller and a shaft, with a small gap between the impellers and between the impeller and the case and wall plate to prevent contact. The two rotors are driven by an electric motor through a pair of synchronous gears and rotate at equal speeds in opposite directions. Because the two impellers are intermeshed, the pump's intake and exhaust ports are not directly connected. Instead, the impellers, case, and wall plate enclose a closed element volume. As the impellers rotate continuously, the element volume is constantly in a cycle of intake-compression-transport-exhaust, continuously discharging air and dust from the chamber to meet the process requirements.

[0005] There are many types of dry vacuum pumps on the market, and different processes require different pump types. For example, in the prior art, Chinese Patent Application CN110741165A discloses a twin-screw vacuum pump, including two cooperating rotors configured to rotate in opposite directions about parallel rotation axes and a stator including a stator bore in which the rotors are mounted for rotation. The stator bore includes a central portion between the two rotation axes and an outer portion outside the two axes. The rotors are configured with dimensions to cooperate with the stator bore, such that when rotating about at least a portion of the outer portion, the outer edge of each rotor remote from the other rotor forms a tight seal with the stator bore. A fluid inlet is provided within the stator bore, at least a portion of which is provided in the central portion of the stator bore located between the rotation axes. Fluid outlets are provided on opposing surfaces of the stator bore, the fluid outlets being provided in the central portion of the stator bore. The fluid inlet and fluid outlet are arranged so that, as the rotor rotates, the rotor moves the pump chamber between the fluid inlet and the fluid outlet, respectively, and at least a portion of the fluid inlet is arranged to extend beyond the center of the stator bore. However, in application environments with a large amount of process by-products, the vacuum pumps of the existing technology have a significant insufficient process by-product accommodating capacity. During operation, dust particles, which are process by-products, are discharged out of the pump along with the exhaust gas. However, when the pump stops rotating, the dust particles adhere to the rotor and housing surfaces. Because the gap between the rotor and the housing is very small (minimum 0.02 mm), the adhered process by-products occupy the gap space between the rotor and the housing. This leads to wear of the dry vacuum pump and, in more serious cases, to a "stuck" state, shortening the service life of the vacuum pump and significantly increasing the operation and maintenance costs of the pump.

[0006] Therefore, how to solve the above-mentioned shortcomings of the existing technical solutions, improve the process by-product accommodating capacity of the vacuum pump, and avoid the pump from being stuck or wearing out due to the adhesion of dust particles, which are the process by-products, has become a technical problem that needs to be solved urgently in the field of technology. Summary of the Invention [Problem to be solved by the invention]

[0007] To solve the above-mentioned shortcomings of the existing technology, the present disclosure provides a vacuum pump assembly that improves the process by-product capacity. Specifically, the present disclosure adopts the following technical solutions: [Means for solving the problem]

[0008] 1. A vacuum pump assembly for increasing process by-product capacity, the vacuum pump assembly including: a front bearing plate, an upper housing, a lower housing, a long rotor, a short rotor, and a rear bearing plate; The long rotor and the short rotor rotate in opposite directions around their own rotation axes, and the axes of the rotation axes of the long rotor and the short rotor are parallel to each other; The long rotor and the short rotor each include multi-stage rotors arranged at intervals in the axial direction of the rotation shaft of the long rotor and the short rotor, respectively; The multi-stage rotors of the long rotor and the short rotor are meshed with each other, and a dust collecting groove is provided on the non-critical surfaces of the rotors where they mesh with each other; The non-critical surfaces of the rotors that mesh with each other specifically refer to the parts of each stage of the multi-stage rotor that do not form a seal with the inner walls of the upper and lower housings, and the parts where the peaks and valleys between the rotors do not mesh.

[0009] Furthermore, the cross section perpendicular to the rotation axis of each stage rotor of the multi-stage rotor consisting of the long rotor and the short rotor exhibits a Y-shaped trilobe structure, and when the long rotor and the short rotor rotate, the tip of one lobe structure of each stage rotor that is far from another lobe structure of the rotor of that stage forms a seal with the inner walls of the upper housing and the lower housing.

[0010] Furthermore, the length of each stage of the multi-stage rotor of the long rotor and short rotor gradually decreases in stages along the axial direction of the rotary shaft in the direction from the intake to the exhaust.

[0011] Furthermore, the long rotor has a plurality of dust storage grooves, one end of each of which is connected to the end face of each rotor facing the intake direction, and the other end of each of which is not connected to the end face of each rotor facing the exhaust direction.

[0012] Furthermore, the number of dust storage grooves provided in the short rotor is multiple, and one end of each dust storage groove does not communicate with the end face of each rotor facing the intake direction, and the other end communicates with the end face of each rotor facing the exhaust direction.

[0013] Furthermore, when the multi-stage rotors of the long rotor and the short rotor mesh with each other, the dust retention grooves provided in the long rotor do not overlap with the dust retention grooves provided in the short rotor.

[0014] Furthermore, the upper housing and the lower housing each include multi-stage operating chambers corresponding to the multi-stage rotor, and the multi-stage operating chambers are arranged at intervals in the axial direction of the rotation shaft.

[0015] Furthermore, upper side dust collecting grooves are provided on both ends of the upper housing that face the front and rear bearing plates.

[0016] Furthermore, the lower housing is provided with a lower side dust collecting groove at each end thereof facing the front bearing plate and the rear bearing plate.

[0017] Further, the upper surface of the lower housing is provided with a plurality of dust collecting grooves of the lower stage plate provided on the upper surface of the stage plate between the multi-stage operation chambers, and / or The lower surface of the upper housing is provided with a plurality of upper stage plate dust collecting grooves that are provided on the lower surface of the stage plate between the multi-stage operation chambers. [Effects of the Invention]

[0018] The present disclosure improves the capacity to contain process by-products by adding dust collection grooves to non-critical areas of the rotor and housing, effectively avoiding pump seizures and wear caused by adhesion of process by-products. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a vacuum pump assembly configuration for improved process by-product capacity in accordance with the present disclosure. [Figure 2] FIG. 2 is a schematic diagram of the structure of the dust accumulation groove of the long rotor of the vacuum pump assembly in the present disclosure. [Figure 3] 1 is a schematic diagram of the structure of the dust accumulation groove of the short rotor of the vacuum pump assembly in the present disclosure; FIG. [Figure 4] FIG. 2 is a schematic cross-sectional view of a rotor of a vacuum pump assembly according to the present disclosure. [Figure 5] 1 is a schematic diagram of the structure of a dust accumulation groove in the upper housing of the vacuum pump assembly of the present disclosure; [Figure 6] 1 is a schematic diagram of the structure of a dust accumulation groove in a lower housing of a vacuum pump assembly according to the present disclosure; DETAILED DESCRIPTION OF THE INVENTION

[0020] The present disclosure will be further described below with reference to the drawings. The following examples are only used to more clearly illustrate the technical solutions of the present disclosure, and are not intended to limit the scope of protection of the present disclosure. It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present disclosure.

[0021] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It should be noted that the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. Furthermore, when the terms "comprise" and / or "comprises" are used in this disclosure, they are intended to specify the presence of features, steps, operations, devices, assemblies, and / or combinations thereof.

[0022] The present disclosure has been made to address the problem that the dry vacuum pump has insufficient process by-product storage capacity, and that dust particles such as process by-products remaining in the chamber adhere to the rotor and housing surfaces, causing the dry vacuum pump to stop working, significantly shortening the vacuum pump's service life and significantly increasing the pump's operation and maintenance costs. Therefore, some structures are designed to improve the chamber's process by-product storage capacity.

[0023] To increase the process by-product capacity of the chamber, the volume of the working chamber needs to be increased. In this disclosure, the process by-product capacity is increased mainly through the following two ideas.

[0024] a) Improve rotor performance Since the rotor thickness, maximum outer diameter and profile line of each stage are all fixed, the only way to optimize the design is from the rotor interlocking surface. Considering that the design structure must not affect the air compression efficiency, the following points should be paid attention to for the dust collection groove: 1) When the rotors are engaged, the dust collection grooves must not overlap. 2) The dust collection groove must not penetrate the rotor, otherwise the two sides of the rotor will be connected, causing the compressed air to flow backward, which will seriously affect the air compression efficiency.

[0025] b) Improve housing Since the groove width and groove radius of each stage of the housing are fixed, the only way to optimize the design is from both the stage plate and the housing. Considering that the design structure must not affect the air compression efficiency, the following points should be paid attention to when it comes to dust collection grooves: 1) When designing the dust collection groove in the step, it is necessary to ensure that both sides of the step do not flow through. 2) The dust accumulation groove must not affect the air compression efficiency. 3) The external dimensions must be taken into consideration, and the dust collection grooves on both sides of the housing must not affect the strength of the housing steps.

[0026] Based on the above design philosophy, the present disclosure improves the process by-product accommodation capacity of the chamber through the following structural design.

[0027] a) Adding a dust collection groove to the multi-stage rotor Dust collection grooves are added to the non-critical meshing surfaces of the multi-stage rotors, and the dust collection grooves are machined axially on each rotor but must not penetrate the rotor. The dust collection grooves of the long and short rotors are offset from each other and opened in opposite directions, so they must not mesh together, otherwise this will lead to backflow of gas and affect the air compression efficiency of the pump.

[0028] b) Adding a dust collection groove to the housing The dust collection groove on the housing 1) Dust collection grooves on the step plates of each step, and 2) The dust collection grooves on both sides of the housing are divided into two parts.

[0029] 1 , a specific embodiment of the present disclosure relates to a vacuum pump assembly for improving process by-product capacity. The vacuum pump assembly for improving process by-product capacity includes a front bearing plate 1, an upper housing 2, a lower housing 3, a long rotor 4, a short rotor 5, and a rear bearing plate 6, where the front bearing plate 1, the rear bearing plate 6, the upper housing 2, and the lower housing 3 form an accommodation chamber surrounded by the front bearing plate 1, the rear bearing plate 6, the upper housing 2, and the lower housing 3. The long rotor 4 and the short rotor 5 are accommodated in the accommodation chamber. The long rotor 4 and the short rotor 5 each have a shaft hole penetrating their thickness, and a rotating shaft is inserted into the corresponding shaft hole, with both ends of the rotating shaft protruding from the shaft holes on the front bearing plate 1 and the rear bearing plate 6.

[0030] When installing, first place the lower housing 3 in the designated position of the vacuum pump, then assemble the long rotor 4 and short rotor 5 in order, then fit the upper housing 2, and finally fix the front bearing plate 1 and rear bearing plate 6 to both sides of the upper housing 2.

[0031] In operation, the long rotor 4 and the short rotor 5 rotate in opposite directions around their own rotation axes, for example, the long rotor 4 rotates clockwise and the short rotor 5 rotates counterclockwise, or the long rotor 4 rotates counterclockwise and the short rotor 5 rotates clockwise. The axes of the rotation axes of the long rotor 4 and the short rotor 5 are parallel to each other, and the term "parallel to each other" in this specification should be understood in a broad sense. Taking into account manufacturing and installation errors, it is acceptable for the axes of the rotation axes of the long rotor 4 and the short rotor 5 to be tilted at a certain angle within the tolerance range, and such tilting is also acceptable.

[0032] As shown in FIGS. 2 and 3, the long rotor 4 and the short rotor 5 each include multiple rotors arranged at intervals in the axial direction of the rotating shaft.

[0033] 2, the long rotor 4 includes a long rotating shaft 41 and multi-stage first rotors 42 arranged at intervals along the axial direction of the long rotating shaft 41. The multi-stage first rotors 42 may be arranged at equal or unequal intervals. Preferably, in this embodiment, the multi-stage first rotors 42 are arranged at unequal intervals. For example, the intervals between the multi-stage first rotors 42 gradually decrease from the right to the left of the long rotating shaft 41 (i.e., in the direction from the intake to the exhaust). The lengths of the multi-stage first rotors 42 may be the same or different. Preferably, in this embodiment, the lengths of the multi-stage first rotors 42 gradually decrease in stages along the axial direction of the long rotating shaft 41 from the intake to the exhaust.

[0034] 3, the short rotor 5 includes a short rotating shaft 51 and multi-stage second rotors 52 arranged at intervals along the axial direction of the short rotating shaft 51. The multi-stage second rotors 52 may be arranged at equal or unequal intervals. Preferably, in this embodiment, the multi-stage second rotors 52 are arranged at unequal intervals. For example, the intervals between the multi-stage second rotors 52 gradually decrease from the right to the left of the short rotating shaft 51 (i.e., in the direction from intake to exhaust). The lengths of the multi-stage second rotors 52 may be the same or different. Preferably, in this embodiment, the length of the multi-stage second rotors 52 gradually decreases in stages along the axial direction of the short rotating shaft 51 from intake to exhaust.

[0035] Furthermore, as shown in Figures 2 and 3, the multi-stage rotors of the long rotor 4 and the short rotor 5 are meshed with each other, and dust collecting grooves are provided on the non-critical surfaces of the rotors where they mesh with each other.

[0036] Specifically, as shown in FIG. 2, a first dust storage groove 43 is provided on the non-critical surface of the multi-stage first rotor 42, and as shown in FIG. 3, a second dust storage groove 53 is provided on the non-critical surface of the multi-stage second rotor 52.

[0037] Here, the non-critical surfaces of the rotors that mesh with each other specifically refer to the portions of each rotor stage of the multi-stage rotor that do not form a seal with the inner walls of the upper housing 2 and the lower housing 3, and the portions where the rotor peaks and valleys do not mesh with each other. In other words, the non-critical surfaces do not include the portions where the rotors form a seal with the inner walls of the upper housing or the lower housing, nor the portions where the rotor peaks and valleys mesh with each other.

[0038] 4, the ranges of angles A, B, and C are the critical surfaces that mesh, and are not allowed to have dust collection grooves; that is, the non-critical surfaces do not include the areas indicated by angles A, B, and C in the figure. That is, for a long rotor, the first dust collection groove 43 is provided at a position other than the areas corresponding to angles A, B, and C, and for a short rotor, the second dust collection groove 53 is provided at a position other than the areas corresponding to angles A, B, and C. It should also be noted that the magnitudes of angles A, B, and C can be calculated based on a series of parameters such as the pump center distance, rotation speed, and maximum outer rotor contour, as well as empirical formulas, and then rounded off.

[0039] Furthermore, as shown in Figure 4, the cross section perpendicular to the rotation axis of each stage of the multi-stage rotors consisting of the long rotor 4 and the short rotor 5 has a Y-shaped trilobe structure, that is, the outline of the rotor of each stage has a Y-shaped trilobe shape, and when the long rotor 4 and the short rotor 5 rotate, the tip of one lobe structure of the rotor of each stage that is far from another lobe structure of the rotor of that stage forms a sealing portion with the inner walls of the upper housing 2 and the lower housing 3.

[0040] Furthermore, as shown in FIG. 2, the first rotors 42 of each stage of the long rotor 4 are provided with a plurality of first dust collection grooves 43, which are provided on non-critical surfaces of the first rotors 42 of each stage, and one end of each first dust collection groove 43 communicates with the end face of each first rotor 42 facing the intake direction, while the other end of each first dust collection groove 43 does not communicate with the end face of each first rotor 42 facing the exhaust direction. That is, to ensure that both sides of the rotor are not connected and to avoid backflow of compressed air, the first dust collection grooves 43 on the first rotors 42 of each stage do not pass through the rotor.

[0041] Furthermore, as shown in FIG. 3 , the second rotors 52 of each stage of the short rotor 5 are provided with a plurality of second dust collection grooves 53, which are provided on non-critical surfaces of the second rotors 52 of each stage, and one end of each second dust collection groove 53 does not communicate with the end face of each second rotor 52 facing the intake direction, and the other end of each second dust collection groove 53 communicates with the end face of each second rotor 52 facing the exhaust direction. That is, to ensure that both sides of the rotor are not connected and to avoid backflow of compressed air, the second dust collection grooves 53 on the second rotors 52 of each stage do not penetrate the rotor.

[0042] In this embodiment, the number of dust storage grooves on the long rotor and the short rotor is not limited. For example, as shown in FIG. 4, each long rotor and each short rotor of each stage are provided with 12 dust storage grooves. Since the cross section of each rotor has a Y-shaped trilobe structure, four dust storage grooves are provided on the non-critical surface of each lobe structure, and the four dust storage grooves are arranged symmetrically.

[0043] Furthermore, as shown in FIGS. 2 and 3, when the multi-stage rotors, i.e., the long rotor 4 and the short rotor 5, are meshed with each other, the dust collection grooves on the long rotor 4 do not overlap with the dust collection grooves on the short rotor 5. That is, in this embodiment, the first dust collection groove 43 on the long rotor 4 and the second dust collection groove 53 on the short rotor 5 are offset from each other and open in opposite directions, thereby preventing backflow of gas and improving the air compression efficiency of the pump.

[0044] In this embodiment, after adding a dust collection groove to the rotor, the process by-product carrying capacity of the pump can reach 15g.

[0045] As shown in FIGS. 5 and 6, the upper housing 2 and the lower housing 3 each include multi-stage operating chambers corresponding to the multi-stage rotor, and the multi-stage operating chambers are arranged at intervals in the axial direction of the rotation shaft.

[0046] 5, the upper housing 2 is provided with multi-stage upper working chambers 21 corresponding to the multi-stage first rotor 42 and the multi-stage second rotor 52, and the multi-stage upper working chambers 21 are arranged at intervals in the axial direction of the rotation shaft. In other words, the upper working chambers can be used to simultaneously accommodate the multi-stage first rotor 42 and the multi-stage second rotor 52.

[0047] 6, the lower housing 3 is provided with multi-stage lower working chambers 31 corresponding to the multi-stage first rotor 42 and the multi-stage second rotor 52, and the multi-stage lower working chambers 31 are arranged at intervals in the axial direction of the rotation shaft. In other words, the multi-stage first rotor 42 and the multi-stage second rotor 52 are synchronously housed in a chamber formed by being surrounded by the lower working chamber and the upper working chamber, and rotate in opposite directions around their respective rotation shafts.

[0048] Furthermore, as shown in FIG. 5, upper side dust collection grooves 22 are provided on both ends of the upper housing 2 facing the front bearing plate 1 and the rear bearing plate 6, respectively. In other words, upper side dust collection grooves 22 are provided on both ends of the upper housing 2 along its length, respectively, which further improves the process by-product storage capacity.

[0049] Of course, in addition to providing dust storage grooves at both ends of the upper housing along its length, it is also possible to provide multiple upper plate dust storage grooves on the underside of the upper housing, and as shown in Figure 5, the dust storage grooves of the multiple upper plates are located on the underside of the plates between the multi-stage upper operating chambers 21, and the dust storage grooves of the upper plates are strip-shaped and processed perpendicular to the axial direction of the rotating shaft, and one end of the dust storage grooves of the multiple upper plates penetrates the contact surface between the upper housing 2 and the rotor rotating shaft.

[0050] 6, a lower side dust collection groove 32 is provided at each end of the lower housing 3 facing the front bearing plate 1 and the rear bearing plate 6, i.e., a lower side dust collection groove 32 is provided at each end of the length of the lower housing 3. In addition, the upper surface of the lower housing 3 is provided with a plurality of lower stage plate dust collection grooves 33 provided on the upper surfaces of the stage plates between the multi-stage lower working chambers 31, the lower stage plate dust collection grooves 33 being strip-shaped and processed perpendicular to the axial direction of the rotating shaft, and one end of the plurality of lower stage plate dust collection grooves penetrates the contact surface between the lower housing 3 and the rotor rotating shaft, further improving the capacity to accommodate process by-products.

[0051] The upper and lower housings are provided with a multi-stage operation chamber that houses the multi-stage rotor, and the areas located on both sides of the multi-stage operation chamber are called step plates, and the widths of the dust storage grooves of the upper and lower step plates are 30% to 50% of the width of the step plates.

[0052] In this embodiment, the side dust collection groove and step dust collection groove are added to the upper and lower housings, thereby improving the storage capacity of process by-products by approximately 30 g.

[0053] Currently, if a dry vacuum pump does not have a dust retention groove, its process by-product storage capacity is less than 1g. In this disclosure, by designing a rotor with a dust retention groove structure, the process by-product storage capacity of the dry vacuum pump is increased by approximately 15g. The housing is optimized and improved, and dust retention grooves on both sides and a step-plate dust retention groove are added to the lower housing, and dust retention grooves on both sides and a step-plate dust retention groove are added to the upper housing, thereby increasing the process by-product storage capacity by approximately 30g, i.e., the total process by-product storage capacity of the pump can reach 45g, greatly extending the service life of the pump. This solves the technical problem of existing dry pumps, where the process by-product storage capacity is insufficient and the process by-product dust remaining in the chamber adheres to the surfaces of the rotor and housing, causing the dry vacuum pump to stop working.

[0054] It should be pointed out that the above is only a preferred embodiment of the present disclosure, and those skilled in the art may make some improvements and modifications without departing from the technical principles of the present disclosure, and these improvements and modifications should also be considered as part of the protection scope of the present disclosure.

Claims

1. 1. A vacuum pump assembly comprising: Includes a front bearing plate, upper housing, lower housing, long rotor, short rotor, and rear bearing plate. The long rotor and the short rotor rotate in opposite directions around their own rotation axes, and the axes of the rotation axes of the long rotor and the short rotor are parallel to each other; The long rotor and the short rotor each include multi-stage rotors arranged at intervals in the axial direction of the rotation shaft of the long rotor and the short rotor, respectively; The multi-stage rotors of the long rotor and the short rotor are meshed with each other, and a dust collecting groove is provided on the non-critical surfaces of the rotors where they mesh with each other; The non-critical intermeshing surfaces of the rotors refer to the portions of the rotors of each stage of the multi-stage rotor that do not form a seal with the inner walls of the upper and lower housings, and the portions where the peaks and valleys of the rotors do not intermesh.

1. A vacuum pump assembly for improving process by-product capacity, comprising:

2. A cross section perpendicular to the rotation axis of each stage of the multi-stage rotor including the long rotor and the short rotor has a Y-shaped trilobe structure, and when the long rotor and the short rotor rotate, a lobe apex of one lobe structure of each stage rotor farther from another lobe structure of the rotor of that stage forms a seal with the inner walls of the upper housing and the lower housing.

10. The vacuum pump assembly of claim 1, wherein the vacuum pump assembly has a flow rate of 100 rpm.

3. the number of the dust retention grooves provided in the long rotor is plural, and one end of each of the dust retention grooves communicates with an end face of the long rotor facing the intake direction, and the other end does not communicate with an end face of the long rotor facing the exhaust direction; 10. The vacuum pump assembly of claim 1, wherein the vacuum pump assembly has a flow rate of 100 rpm.

4. The number of the dust retention grooves provided in the short rotor is plural, and one end of each of the dust retention grooves does not communicate with the end face of the short rotor facing the intake direction, and the other end communicates with the end face of the short rotor facing the exhaust direction.

10. The vacuum pump assembly of claim 1, wherein the vacuum pump assembly has a flow rate of 100 rpm.

5. When the multi-stage rotors of the long rotor and the short rotor mesh with each other, the dust retention groove provided in the long rotor does not overlap with the dust retention groove provided in the short rotor.

5. A vacuum pump assembly for increasing process by-product capacity according to claim 3 or 4.

6. The length of each stage of the multi-stage rotor including the long rotor and the short rotor gradually decreases in stages along the axis of the rotary shaft in a direction from the intake to the exhaust.

10. The vacuum pump assembly of claim 1, wherein the vacuum pump assembly has a flow rate of 100 rpm.

7. the upper housing and the lower housing each include a multi-stage operating chamber corresponding to a multi-stage rotor, and the multi-stage operating chambers are arranged at intervals in the axial direction of the rotation shaft; 10. The vacuum pump assembly of claim 1, wherein the vacuum pump assembly has a flow rate of 100 rpm.

8. upper side dust collecting grooves are provided on both ends of the upper housing facing the front bearing plate and the rear bearing plate, 8. The vacuum pump assembly of claim 7, wherein the vacuum pump assembly has a process by-product capacity increased.

9. a lower surface dust collecting groove is provided at each end of the lower housing facing the front bearing plate and the rear bearing plate; 8. The vacuum pump assembly of claim 7, wherein the vacuum pump assembly has a process by-product capacity increased.

10. The upper surface of the lower housing is provided with a plurality of dust collecting grooves of the lower stage plate, which are provided on the upper surface of the stage plate between the multi-stage operation chambers; and / or A plurality of upper stage plate dust collecting grooves are provided on the lower surface of the upper housing, the upper stage plate being provided on the lower surface of the stage plate between the multi-stage operation chambers.

8. The vacuum pump assembly of claim 7, wherein the vacuum pump assembly has a process by-product capacity increased.

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