Roots pump rotor and Roots pump with pneumatic seal groove

Abstract

This disclosure relates to a Roots pump rotor and a Roots pump with pneumatic seal grooves. The rotors of a Roots vacuum pump operate in pairs, and the cross-section perpendicular to the rotation axis of both rotors has a figure-eight leaf shape. Annular pneumatic seal grooves are installed on two sides of the figure-eight leaf shape. When airflow leaks from the gap between the sides of the rotor and the wall of the pump body, the pneumatic seal grooves installed on the sides reduce the amount of leakage from the gap between the sides and the wall of the pump body. This disclosure, based on the principle of pneumatic sealing, reduces the pressure difference on both sides of the sealing device, and in combination with the vortex structure formed in the grooves as the rotor rotates, can significantly improve backflow losses and gas leakage losses in the gap between the sides of the rotor and the wall of the pump body, without changing the thickness dimension of the rotor. This effectively suppresses leakage and flow from the gap due to the pressure difference inside the pump and improves the overall suction speed.

Description

Technical Field

[0001] "Cross-reference to Related Applications" This disclosure claims the priority of a Chinese patent application with application number 202310338837.6 and invention title "Roots Pump Rotor with Pneumatic Seal Groove and Roots Pump" filed with the China National Intellectual Property Administration on March 31, 2023, and all of its contents are incorporated herein by reference.

[0002] This disclosure relates to the field of vacuum pump technology, particularly to a Roots pump rotor with pneumatic seal grooves and a Roots pump.

Background Art

[0003] The use of a vacuum pump is to suck gas molecules from a vacuum chamber, reduce the gas pressure in the vacuum chamber, and achieve the required vacuum degree of the vacuum chamber. It is mainly applied in industries such as pharmaceutical and chemical industries, vacuum coating, vacuum drying, surface treatment, vacuum smelting, ceramic manufacturing, food packaging, milk extraction, beverages, etc.

[0004] With the rapid development and continuous innovation of science and technology and economic soft power, the application of vacuum technology has become increasingly widespread. In national economic fields such as semiconductors, petrochemical industries, medical facilities, food and pharmaceuticals, and metallurgy, the demand for vacuum pumps is also increasing. Vacuum pumps include Roots vacuum pumps, screw pumps, turbo-type oil-free pumps, etc. Here, the Roots-type vacuum pump has characteristics such as a large pumping speed, fast startup, small vibration, no internal compression process, and small friction loss, and thus has received high evaluation from the semiconductor industry.

[0005] In a Roots vacuum pump, the two axes of the rotor are parallel to each other. The rotor consists of a combination of impellers and shafts, with small gaps between the impellers and between the impellers and the housing and bearing plates to avoid contact between them. With the continuous development and improvement of Roots pump technology, leakage occurring in the gap between the Roots pump rotor and housing has become a bottleneck problem that limits the performance of Roots pumps. In the prior art, Chinese patent application CN110741165A discloses a twin-screw pump and pumping method, in which the technical solution is configured such that the rotor has dimensions to cooperate with the stator holes, so that when at least a portion of the outer part rotates, the outer edge of each rotor away from the other rotor is sealed with the stator holes. The problem with such a method is that it does not have a significant improvement effect on leakage from the gap at the rotor blade tips and is not sufficiently targeted. Furthermore, Chinese patent application CN105649980A discloses a Roots-type vacuum pump that facilitates the measurement of end face gaps and adjustment of rotor gaps. The technical solution involves attaching a seal slider to the end face of the housing and opening a radial measuring groove to measure the gap between the rotor and the end face. The problem with this method is that, because it employs a contact seal, it has the disadvantage of being demanding on the manufacturing process and potentially increasing energy consumption.

[0006] Conventional technology is limited by machining precision and contact between the rotor and pump housing due to thermal deformation of the rotor during operation, and it is still not possible to further reduce leakage and improve the suction speed of Roots vacuum pumps.

[0007] Therefore, how to overcome the shortcomings of the above-mentioned conventional solutions, reduce the pressure difference of leaking airflow through gaps, and thereby reduce the leakage flow rate is a technical problem that needs to be solved urgently in this field. [Overview of the project] [Problems that the invention aims to solve]

[0008] To address the shortcomings of the prior art described above, this disclosure provides a Roots pump rotor with a pneumatic seal groove and a Roots pump. Specifically, this disclosure employs the following technical solutions. [Means for solving the problem]

[0009] A Roots pump rotor with a pneumatic seal groove, wherein the pneumatic seal groove is located in the edge region of the Roots pump rotor and includes an outer layer groove parallel to the contour of the Roots pump rotor. When the Roots pump rotor rotates, the airflow flows into the pneumatic seal groove along the housing and rotor sidewalls of the Roots pump, forming a vortex in the direction of flow. The high-speed rotation of the Roots pump rotor then forms a tangential vortex, and the pneumatic seal structure is formed by the flow-direction vortex and the tangential vortex.

[0010] Furthermore, the cross-section of the Roots pump rotor, perpendicular to its axis of rotation, has a leaf-like shape with an eight-shaped outline.

[0011] Furthermore, the outer layer groove includes two first grooves that are adjacent and parallel to each other.

[0012] Furthermore, the pneumatic seal groove further includes an inner groove located on the side wall surface of the Roots pump rotor and parallel to the rotor shaft hole.

[0013] Furthermore, the inner groove includes two second grooves that are adjacent and parallel to each other.

[0014] Furthermore, the depths of the first and second grooves are 5 mm, and during operation, the rotor does not come into contact with the inner wall of the Roots pump housing.

[0015] Furthermore, the distance between the two adjacent and parallel first grooves is 0.3 mm, and / or The distance between the two adjacent and parallel second grooves is 0.3 mm.

[0016] This disclosure further relates to a Roots pump including a Roots pump rotor with a pneumatic seal groove as described above, wherein the Roots pump includes a housing for the Roots pump and a left rotor and a right rotor housed in the housing for the Roots pump, wherein the left rotor and the right rotor are the Roots pump rotor with a pneumatic seal groove as described above. The left and right rotors rotate in opposite directions around their respective axes of rotation, and the axes of the left and right rotors are set parallel to each other. If one of the rotors is mounted vertically, the other rotor is mounted horizontally. As the rotor rotates, a pneumatic seal structure is formed when the airflow flows through the passages created by the side walls of the left and right rotors and the inner wall of the Roots pump housing.

[0017] Furthermore, an intake port is provided in the upper side wall of the housing of the Roots pump, near the front of the housing, and an exhaust port is provided in the lower side wall of the housing of the Roots pump, near the rear of the housing, with the area of ​​the intake port opening being greater than or equal to the area of ​​the exhaust port opening.

[0018] Furthermore, the housing, left rotor, and right rotor of the Roots pump are made of a high-nickel alloy material. [Effects of the Invention]

[0019] The technical solution of the present disclosure brings the following beneficial effects. A series of pneumatic seal grooves are installed on the side wall surface of the Roots pump rotor. By utilizing the flowing vortex structure, the flow path area for gas flowing from the high-pressure side to the low-pressure side along the gap between the housing of the Roots pump and the side wall surface of the rotor is reduced. By utilizing the cavity structure inside the pneumatic seal grooves, the pressure difference at both ends of the gas leakage cross-section is reduced, improving the reverse flow loss and gas leakage loss within the gap between the housing of the Roots pump and the side wall surface of the rotor, effectively suppressing the leakage and flow from the gap between the housing of the Roots pump and the side wall surface of the rotor inside the pump, and improving the overall suction speed. Also, the mass of the rotor is effectively reduced, reducing energy consumption.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram of the structure of the Roots pump rotor with pneumatic seal grooves of the present disclosure. [Figure 2] It is a front view of the Roots pump rotor with pneumatic seal grooves of the present disclosure. [Figure 3] It is a cross-sectional view taken along the A-A plane of FIG. 2. [Figure 4] It is a cross-sectional view taken along the B-B plane of FIG. 2. [Figure 5] It is a cross-sectional view taken along the C-C plane of FIG. 2. [Figure 6] It is a schematic diagram of the vortex structure inside the pneumatic groove of the Roots pump rotor with pneumatic seal grooves of the present disclosure. [Figure 7] It is a schematic diagram of the structure of the Roots pump of the present disclosure. [Figure 8] It is a plan view of the Roots pump of the present disclosure. [Figure 9] It is a cross-sectional view taken along the A-A plane of FIG. 8. [Figure 10] It is a cross-sectional view taken along the B-B plane of FIG. 8.

Modes for Carrying Out the Invention

[0021] The present disclosure will be further described below with reference to the drawings. The following embodiments are 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.

[0022] Unless otherwise specified, all technical and scientific terms used in this disclosure have the same meaning as those ordinarily understood by those skilled in the art. The terms used herein are for illustrative purposes only and do not limit the exemplary embodiments provided herein. As used herein, unless otherwise specified in context, singular nouns are also intended to include plural nouns, and where the terms “include” and / or “contain” are used herein, it should be understood that they indicate the presence of features, steps, operations, devices, modules, and / or combinations thereof. Directions or positional relationships indicated by terms such as “longitudinal,” “lateral,” “up,” “down,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inside,” and “outside” are based on the directions or positional relationships shown in the drawings and are for illustrative purposes only. They do not indicate or imply that the devices or elements shown necessarily have a specific orientation or are configured or operated in a specific orientation, and therefore should not be understood as limiting this disclosure.

[0023] As shown in Figures 1 and 2, a specific embodiment 1 of the present disclosure relates to a Roots pump rotor with a pneumatic seal groove, wherein the cross section perpendicular to the axis of rotation of the Roots pump rotor with the pneumatic seal groove has a figure-eight leaf shape. The pneumatic seal groove 6 includes an outer layer groove 61 located in the edge region of the side wall surface of the Roots pump rotor and parallel to the figure-eight leaf shape; that is, the outer layer groove 61 is installed in the edge region of the side wall surface of the Roots pump rotor, and the cross section of the outer layer groove 61 also has a figure-eight leaf shape. Based on the pneumatic seal groove, when the rotor rotates, a pneumatic seal structure is formed as the airflow flows through the passage formed by the side wall of the rotor and the inner wall of the housing.

[0024] Furthermore, based on the pneumatic seal groove, the airflow flows into the pneumatic seal groove along the side walls of the Roots pump housing and rotor, forming a vortex in the direction of flow. The high-speed rotation of the Roots pump rotor then forms a tangential vortex. The pneumatic seal structure is formed by the flow-direction vortex and the tangential vortex working together, that is, the flow-direction vortex and the tangential vortex work together to reduce leakage from the rotor side walls.

[0025] It should be understood that the pneumatic seal groove has a hollow structure inside, which reduces the pressure difference at both ends of the gas leak cross-section based on this hollow structure, improving backflow loss and gas leak loss in the gap between the Roots pump housing and the rotor side wall, effectively suppressing leakage and flow from the gap between the Roots pump housing and the rotor side wall inside the pump, and improving the overall suction speed.

[0026] Furthermore, the Roots pump rotor has two opposing side walls, and the pneumatic seal grooves may be installed on each of these two side walls, that is, the pneumatic seal grooves 6 are installed on either of the two side walls of the Roots pump rotor, as shown in Figures 3 to 5.

[0027] As shown in Figures 3, 4, and 5, the pneumatic seal groove 6 installed on the side wall surface of the Roots pump rotor has a multilayer fitting configuration and includes an outer layer groove 61 parallel to a figure-eight leaf shape. The outer layer groove 61 includes two adjacent and parallel first grooves, that is, the two first grooves included in the outer layer groove 61 have a figure-eight annular structure, and the two figure-eight annular first grooves are fitted and installed in the edge region of the Roots pump rotor.

[0028] Furthermore, as shown in Figures 1 to 5, the pneumatic seal groove 6 of this disclosure further includes an inner groove 62 located on the side wall surface of the Roots pump rotor and parallel to the rotor shaft hole. It should be noted that "parallel to the rotor shaft hole" here should be understood in a broad sense, and the inner groove may be installed in a parallel relationship where it is fitted into the rotor shaft hole, or in a parallel relationship where it is installed at a distance from the rotor shaft hole.

[0029] In some preferred embodiments, the inner layer groove 62 is fitted to the outside of the rotor shaft hole, and that is, the inner layer groove may include two adjacent and parallel second grooves, or one second groove, or three parallel second grooves, etc., installed on the outside of the Roots pump rotor shaft hole. The second grooves included in the inner layer groove have an annular structure, and if there are two or three second grooves, the multiple annular second grooves are fitted to the outside of the rotor shaft hole of the Roots pump rotor.

[0030] In some other preferred embodiments, the inner layer groove 62 further includes a second groove located outside the figure-eight leaf-shaped through-hole, that is, the inner layer groove can be located on one or both sides of the figure-eight leaf-shaped structure adjacent to the rotor shaft hole, and of course, the second groove may also be annular in structure, in which case the annular second groove forms a spaced parallel relationship with the rotor shaft hole.

[0031] It should be understood that the number of grooves in the outer and inner layers described above must be adjusted according to the size of the rotor. If the rotor is large, the number of groove layers must be increased to improve the sealing effect.

[0032] The depths of the first and second grooves included in the pneumatic seal groove are 5 mm, and during operation, the Roots pump rotor does not come into contact with the inner wall of the housing. The spacing between two adjacent and parallel grooves included in the outer and inner grooves is 0.3 mm, meaning that the spacing between two adjacent and parallel first grooves may be 0.3 mm, and the spacing between two adjacent and parallel second grooves may also be 0.3 mm.

[0033] As shown in Figure 6, the present disclosure provides a pneumatic seal groove in the Roots pump rotor so that after the airflow flows into the pneumatic seal groove along the housing and rotor sidewall of the Roots pump, it forms a flow-direction vortex, and as the rotor rotates at high speed, a tangential vortex is formed, and the flow-direction vortex and the tangential vortex work together to reduce leakage from the rotor sidewall.

[0034] As shown in Figure 7, a specific embodiment 2 of the present disclosure relates to a Roots pump including a Roots pump rotor with an annular pneumatic seal groove, the Roots pump including a Roots pump housing 1, a left rotor 2, and a right rotor 3, where the left rotor 2 and the right rotor 3 are the aforementioned Roots pump rotors, and their specific structures can be found by referring to those described above. The left rotor 2 and the right rotor 3 are housed in the Roots pump housing 1, and the left rotor 2 has a corresponding left rotation axis 7 drilled into it, and the right rotor 3 has a corresponding right rotation axis 8 drilled into it, the axes of the left rotation axis 7 and the right rotation axis 8 are set parallel to each other, and the left rotor 2 and the right rotor 3 rotate in opposite directions around their respective rotation axes, for example, the left rotor 2 rotates clockwise and the right rotor 3 rotates counterclockwise, or the left rotor 2 rotates counterclockwise and the right rotor 3 rotates clockwise.

[0035] It should be noted that the term "installed parallel to each other" should be understood in a broad sense. Considering manufacturing and installation tolerances, the axes of the left and right rotation shafts are permitted to have a certain angle of inclination within the tolerance range, and such inclination is also acceptable.

[0036] As shown in Figures 8 and 9, the cross-sections perpendicular to the rotation axis of the left rotor 2 and the right rotor 3 both have an eight-shaped leaf contour. When one rotor is installed vertically, the other rotor is installed horizontally. For example, when the left rotor 2 is installed vertically, the right rotor 3 is installed horizontally, and when the right rotor 3 is installed vertically, the left rotor 2 is installed horizontally. Furthermore, when the rotors rotate, a pneumatic seal structure is formed as the airflow flows through the passage formed by the rotor's side wall and the housing's inner wall.

[0037] As shown in Figures 7 to 10, an intake port 5 is opened in the upper side wall of the Roots pump housing 1, near the front of the housing 1, and an exhaust port 4 is opened in the lower side wall of the Roots pump housing 1, near the rear of the housing 1. The opening area of ​​the intake port 5 is greater than or equal to the opening area of ​​the exhaust port 4.

[0038] It should be understood that the upper side walls, lower side walls, front side, and rear side of the Roots pump housing are not specifically limited. The sides of the Roots pump housing along the length of the rotation axis can be considered the front side and rear side, and the sides of the Roots pump housing along a direction perpendicular to the line connecting the two rotation axes can be considered the upper side walls and lower side walls.

[0039] In this disclosure, the materials of the Roots pump housing 1, left rotor 2, and right rotor 3 are high-nickel alloy materials.

[0040] This disclosure describes how, after adding a pneumatic seal groove, the flow vortex structure is used to reduce the flow area in which gas flows from the high-pressure side to the low-pressure side along the gap between the housing and the rotor sidewall of the Roots pump, the internal cavity structure of the pneumatic seal groove is used to reduce the pressure difference at both ends of the gas leak cross-section, improving backflow loss and gas leak loss in the gap between the housing and the rotor sidewall of the Roots pump, effectively suppressing leakage and flow from the gap between the housing and the rotor sidewall of the pump, improving the overall suction speed, reducing the rotor mass, and reducing energy consumption, all while keeping the rotor thickness dimension unchanged.

[0041] The foregoing are merely preferred embodiments of the present disclosure, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present disclosure, and these improvements and modifications should also be considered within the scope of the present disclosure.

Claims

1. A Roots pump rotor with a pneumatic seal groove, wherein the pneumatic seal groove is located in the edge region of the side wall surface of the Roots pump rotor and includes an outer layer groove parallel to the contour of the Roots pump rotor. A Roots pump rotor with a pneumatic seal groove, characterized in that, when the Roots pump rotor rotates, the airflow flows into the pneumatic seal groove along the housing and side walls of the rotor, forming a vortex in the direction of flow, and a tangential vortex is formed by the high-speed rotation of the Roots pump rotor, and a pneumatic seal structure is formed by the vortex in the direction of flow and the tangential vortex.

2. The Roots pump rotor with a pneumatic seal groove according to claim 1, characterized in that the cross section of the Roots pump rotor perpendicular to its axis of rotation has a leaf shape with an eight-shaped outline.

3. The Roots pump rotor with pneumatic seal grooves according to claim 1, characterized in that the outer layer groove includes two adjacent and parallel first grooves.

4. The Roots pump rotor with a pneumatic seal groove according to claim 3, characterized in that the pneumatic seal groove further includes an inner groove located on the side wall surface of the Roots pump rotor and parallel to the rotor shaft hole.

5. The Roots pump rotor with pneumatic seal grooves according to claim 4, characterized in that the inner layer groove includes two adjacent and parallel second grooves.

6. The Roots pump rotor with pneumatic seal grooves according to claim 5, characterized in that the depth of the first groove and the second groove is 5 mm, and the rotor does not come into contact with the inner wall of the housing of the Roots pump during operation.

7. The distance between the two adjacent and parallel first grooves is 0.3 mm, and / or The Roots pump rotor with pneumatic seal grooves according to claim 5, characterized in that the distance between the two adjacent and parallel second grooves is 0.3 mm.

8. The Roots pump includes a housing for a Roots pump, and a left rotor and a right rotor housed in the housing for the Roots pump, wherein the left rotor and the right rotor are Roots pump rotors with pneumatic seal grooves as described in any one of claims 1 to 7. The left and right rotors rotate in opposite directions around their respective axes of rotation, and the axes of the left and right rotors are set parallel to each other. If one of the rotors is mounted vertically, the other rotor is mounted horizontally. A Roots pump characterized in that, when the rotor rotates, an air pressure seal structure is formed when the airflow flows through a passage formed by the side walls of the left rotor and the right rotor and the inner wall of the housing of the Roots pump.

9. An air intake port is provided in the upper side wall of the housing of the Roots pump, near the front of the housing, and an exhaust port is provided in the lower side wall of the housing of the Roots pump, near the rear of the housing. The Roots pump according to claim 8, characterized in that the area of ​​the opening of the intake port is greater than or equal to the area of ​​the opening of the exhaust port.

10. The Roots pump according to claim 8, characterized in that the housing of the Roots pump, the left rotor, and the right rotor are made of a high-nickel alloy material.

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