Vacuum pump dynamic sealing structure, vacuum pump rotor and vacuum pump

Abstract

This application provides a dynamic sealing structure for a vacuum pump, a vacuum pump rotor, and a vacuum pump. The vacuum pump includes a stator and a pair of meshing rotors. A cavity is provided within the stator. Each rotor includes a rotor shaft and rotor elements. The rotor shaft is rotatably mounted in the cavity via bearings. The rotor elements are disposed on the rotor shaft and located within the cavity. An axial clearance exists between the end face of the rotor elements and the sidewall of the stator. The dynamic sealing structure is located on the end face of the rotor elements facing the stator sidewall or on the sidewall of the stator facing the end face of the rotor elements. The dynamic sealing structure includes multiple helical grooves, which drive the process gas to move along a helical direction when the rotor elements rotate relative to the stator. This dynamic sealing structure can form a gas film within the axial clearance between the end face of the rotor elements and the inner wall of the stator. This gas film reduces the pressure difference across the sealing device, minimizing contact between the process gas and the sealing device, thereby protecting the sealing device.

Description

Technical Field

[0001] This application relates to the field of vacuum pump technology, and more specifically, to a dynamic sealing structure for a vacuum pump, a vacuum pump rotor, and a vacuum pump. Background Technology

[0002] In a vacuum pump system, the sealing device is a key component. It isolates the stator working chamber from the lubrication chamber, preventing gas leakage or impurity intrusion, and directly affects the performance of the vacuum pump. On the one hand, poor vacuum can significantly reduce the pumping efficiency, failing to meet the required vacuum level for production, thus impacting product quality. For example, in semiconductor chip manufacturing, even minor vacuum leaks can cause internal structural defects in the chip. On the other hand, process gases entering the lubrication chamber can cause lubricant emulsification, accelerate component wear, increase equipment maintenance costs, and result in substantial economic losses for the company.

[0003] Currently, common dry vacuum pumps typically use shaft seals for sealing. When the vacuum pump starts, stops, or its operating conditions change, the internal pressure of the stator changes instantaneously, while the external environmental pressure is usually relatively stable. This results in a large pressure difference on both sides of the sealing device. This pressure difference causes process gas to flow towards the sealing device, thereby corroding the sealing device and reducing its service life. Utility Model Content

[0004] This application provides at least one dynamic sealing structure for a vacuum pump, a vacuum pump rotor, and a vacuum pump. The dynamic sealing structure can form a gas film in the axial gap between the end face of the rotor element and the side wall of the stator. This gas film can achieve isolation and stabilize the pressure between the end face of the rotor element and the side wall of the stator, reducing pressure fluctuations. This reduces the pressure difference on both sides of the sealing device, reduces the contact between the process gas and the sealing device, thereby reducing the corrosion of the sealing device by the process gas and improving the service life of the sealing device.

[0005] In a first aspect, embodiments of this application provide a dynamic sealing structure for a vacuum pump. The vacuum pump includes a stator and a pair of meshing rotors. A cavity is provided inside the stator. The rotors include a rotor shaft and rotor elements. The rotor shaft is rotatably disposed in the cavity via bearings. The rotor elements are disposed on the rotor shaft and located within the cavity. An axial gap exists between the end face of the rotor elements and the side wall of the stator. The dynamic sealing structure is disposed on the end face of the rotor elements facing the side wall of the stator or on the side wall of the stator facing the end face of the rotor elements. The dynamic sealing structure includes a plurality of helical grooves. The helical grooves are used to drive the process gas to move along the helical direction when the rotor elements rotate relative to the stator, so as to form a gas film within the axial gap.

[0006] In one alternative embodiment, the rotor element comprises a multi-stage rotor element, and the dynamic sealing structure is disposed on the end face of the last stage rotor element facing the stator sidewall or on the sidewall of the stator facing the end face of the rotor element.

[0007] In one alternative embodiment, the helical grooves of the two meshing rotors have opposite helical directions.

[0008] In one optional embodiment, the helix angle of the spiral groove is 20° to 30°.

[0009] In one alternative embodiment, the depth of the spiral groove is 5~15μm.

[0010] In one alternative embodiment, the number of spiral grooves is 8 to 10.

[0011] In one alternative embodiment, the groove-to-dam ratio of the spiral groove is 0.8 to 1.2.

[0012] In one alternative embodiment, the width of the helical groove gradually decreases from the edge of the rotor element toward the center.

[0013] Secondly, embodiments of this application also provide a vacuum pump rotor, which is provided with the aforementioned dynamic sealing structure for a vacuum pump.

[0014] Thirdly, embodiments of this application also provide a vacuum pump, including the vacuum pump rotor described above.

[0015] The above-mentioned technical solution of this application has the following beneficial technical effects: The dynamic sealing structure of the vacuum pump in this embodiment is disposed on the end face of the rotor element facing the stator sidewall or on the sidewall of the stator facing the rotor element end face. When the rotor element rotates relative to the stator, it can drive the process gas to move in a spiral direction, thereby forming a gas film in the axial gap between the end face of the rotor element and the sidewall of the stator. This gas film can achieve isolation and stabilize the pressure between the end face of the rotor element and the sidewall of the stator, reducing pressure fluctuations. This reduces the pressure difference on both sides of the sealing device, reduces the contact between the process gas and the sealing device, thereby reducing the corrosion of the sealing device by the process gas and improving the service life of the sealing device.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. These drawings are incorporated in and constitute a part of this specification. They illustrate embodiments conforming to this application and, together with the specification, serve to explain the technical solutions of this application. It should be understood that the following drawings only show some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of a vacuum pump provided in an embodiment of this application is shown; Figure 2 It shows Figure 1 Sectional view of AA; Figure 3 It shows Figure 1 A schematic diagram of the structure of the fifth-stage rotor element; In the picture: 1. Stator; 2. First end plate; 3. Second end plate; 4. Rotor shaft; 5. Rotor element; 6. Sealing device; 7. Gearbox; 71. Gear; 8. Rear cover plate; 9. Motor; 10. Exhaust pipe; 11. Spiral groove; 12. Air film. Detailed Implementation

[0019] Various exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application.

[0020] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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 this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] refer to Figure 1 and Figure 2 This application provides a vacuum pump, including a stator 1, a pair of meshing rotors, a gearbox 7, a rear cover plate 8, and a motor 9. The stator 1 has a cavity and an exhaust pipe 10 connected to the cavity. The stator 1 has a first end plate 2 and a second end plate 3 located at opposite ends of the cavity. The rotors include a rotor shaft 4 and rotor elements 5. The rotor shaft 4 is rotatably mounted in the cavity via bearings. The rotor elements 5 are mounted on the rotor shaft 4 and located within the cavity. An axial clearance exists between the end face of the rotor elements 5 and the side wall (inner surface of the first end plate 2) of the stator 1. The rotor elements 5 and the stator 1 enclose an inlet side and an outlet side. When the rotor elements 5 rotate, they compress the process gas on the inlet side and push it towards the outlet side, where it is discharged through the exhaust pipe 10. The gearbox 7 is located on the first end plate 2 and connected to the rotor shaft 4. The rear cover plate 8 is located on the second end plate 3. The motor 9 is located in the gearbox 7 and connected to the gear 71 inside the gearbox 7. The motor 9 is used to transmit power to the rotor shaft 4 through the gear 71 and drive the rotor shaft 4 to rotate the rotor element 5.

[0025] In this embodiment, the stator 1 includes a multi-stage pump chamber. Both rotors include multi-stage rotor elements 5, with each stage of rotor elements 5 located within its respective stage of pump chamber. The two rotor elements 5 of the same stage mesh with each other, and each stage of rotor elements 5 encloses the stator 1 to form an inlet side and an outlet side, respectively.

[0026] like Figure 1As shown in this embodiment, the stator 1 is provided with a first-stage pump chamber, a second-stage pump chamber, a third-stage pump chamber, a fourth-stage pump chamber, and a fifth-stage pump chamber arranged sequentially from left to right. The rotor shaft 4 is provided with a first-stage rotor element, a second-stage rotor element, a third-stage rotor element, a fourth-stage rotor element, and a fifth-stage rotor element arranged sequentially from left to right. The first-stage rotor elements of the two rotors mesh in the first-stage pump chamber, the second-stage rotor elements of the two rotors mesh in the second-stage pump chamber, the third-stage rotor elements of the two rotors mesh in the third-stage pump chamber, the fourth-stage rotor elements of the two rotors mesh in the fourth-stage pump chamber, and the fifth-stage elements of the two rotors mesh in the fifth-stage pump chamber. The first-stage pump chamber's outlet side is connected to the second-stage pump chamber's inlet side; the second-stage pump chamber's outlet side is connected to the third-stage pump chamber's inlet side; the third-stage pump chamber's outlet side is connected to the fourth-stage pump chamber's inlet side; the fourth-stage pump chamber's outlet side is connected to the fifth-stage pump chamber's inlet side; and the fifth-stage pump chamber's outlet side is connected to the exhaust pipe 10. When the two rotors rotate synchronously, the process gas flow direction is: first-stage pump chamber's inlet side → first-stage pump chamber's outlet side → second-stage pump chamber's inlet side → second-stage pump chamber's outlet side → third-stage pump chamber's inlet side → third-stage pump chamber's outlet side → fourth-stage pump chamber's inlet side → fourth-stage pump chamber's outlet side → fifth-stage pump chamber's inlet side → fifth-stage pump chamber's outlet side → exhaust pipe 10.

[0027] refer to Figure 1 In this embodiment, a sealing device 6 with a sealing cavity is provided between the rotor shaft 4 and the stator 1. Specifically, a sealing device 6 (such as an axial lip seal) is provided between the rotor shaft 4 and the first end plate 2 and the second end plate 3 of the stator 1, respectively.

[0028] refer to Figure 2 In this embodiment, the rotor element 5 of the rotor has a five-bladed structure. Of course, the rotor element 5 can also be a three-bladed structure, a six-bladed structure, etc.

[0029] refer to Figure 2 and Figure 3In this embodiment, the rotor is provided with a dynamic sealing structure, specifically disposed on the end face of the rotor element 5 facing the side wall of the stator 1. The dynamic sealing structure includes multiple spiral grooves 11, which are used to drive the process gas to move along the spiral direction when the rotor element 5 rotates relative to the stator 1, so as to form a gas film 12 in the axial gap. Specifically, the dynamic sealing structure utilizes the pumping effect of the spiral grooves 11 to form a stable gas film 12 between the rotor and the end plate. This gas film 12 can achieve isolation and stabilize the pressure between the end face of the rotor element 5 and the side wall of the stator 1, reducing pressure fluctuations. This reduces the pressure difference on both sides of the sealing device 6, reduces the contact between the process gas and the sealing device 6, thereby reducing the corrosion of the sealing device 6 by the process gas and improving the service life of the sealing device 6. Of course, in other embodiments, the dynamic sealing structure can also be disposed on the side wall corresponding to the end face of the stator 1 facing the rotor element 5.

[0030] Optionally, when the rotors all include multi-stage rotor elements 5, the dynamic sealing structure is disposed on the last stage rotor element 5 (e.g., Figure 1 The end face of the fifth stage rotor element (shown) facing the side wall of stator 1 or the side wall of stator 1 facing the end face of the last stage rotor element 5.

[0031] Optionally, the helical grooves 11 of the two meshing rotors have opposite helical directions. This arrangement allows the axial forces generated by the two rotors to cancel each other out, maintaining the mechanical balance of the system. Specifically, when the rotors rotate, the pumping effect of the helical grooves 11 generates axial thrust (the reaction force exerted on the rotor by the gas as it moves along the helical grooves 11). If the helical grooves 11 of the two meshing rotors have the same helical direction, the axial forces will be superimposed, causing the rotor assembly to bear a unidirectional load, which may lead to bearing wear or rotor misalignment. The design with opposite helical directions allows the axial forces generated by the two rotors to cancel each other out, maintaining the mechanical balance of the system. In addition, the design with opposite helical directions promotes the formation of a more uniform distributed gas film 12 at the sealing interface, preventing the gas film 12 from rupturing due to excessively high or low local pressure, thereby more reliably isolating corrosive gases.

[0032] Optionally, the helix angle of the spiral groove 11 is 20°~30°. This setting achieves a balance between conveying efficiency and leakage. Specifically, when the helix angle is too small (α<15°), When the axial flow component of the process gas (pointing towards the high-pressure area) is weak, the circumferential flow component is strong, the gas is prone to circumferential leakage, and the pressure rise is slow, resulting in low film stiffness (poor resistance to load fluctuations). When the helix angle is too large (α>45°), When the axial flow is fast, the radial leakage component of the gas (perpendicular to the direction of movement) increases. Although the axial transport is fast, the leakage increases dramatically. Furthermore, the pressure distribution is uneven, and the gas film 12 is prone to local vacuum, resulting in decreased stability. In this embodiment, the helix angle of the spiral groove 11 is set to 20°~30°, which can greatly improve the problems caused by the helix angle being too small or too large, and achieve a balance between transport efficiency and leakage.

[0033] Optionally, the depth of the spiral groove 11 is 5~15μm. This setting ensures the thickness of the gas film 12, avoiding frictional contact and controlling leakage. Specifically, the depth of the spiral groove 11 directly affects the thickness of the gas film 12 formed between the moving ring (rotor) and the stationary ring (end plate). If the groove depth is too small (e.g., <5μm), the gas flow resistance increases, making it difficult to form a sufficiently thick gas film 12, resulting in direct contact at the sealing interface and ineffective isolation of corrosive gases. If the groove depth is too large (e.g., >20μm), the excessively thick gas film 12 will lead to increased leakage and reduced pumping efficiency. In this embodiment, the depth of the spiral groove 11 is set to 5μm. 15μm, can produce 0.1 during rotation. A 1μm thick gas film (formed by compression through gas shear force and centrifugal force) can both avoid frictional contact and control leakage.

[0034] Optionally, the number of spiral grooves 11 is 8 to 10. This arrangement forms a uniformly distributed airflow channel within the axial clearance, avoiding dead zones in gas flow and ensuring the continuous and stable operation of the gas film 12. Specifically, the main function of the spiral grooves 11 is to generate a pumping effect through rotation, transporting gas from the outer edge to the center. If the number of grooves is too small (e.g., <4), the circumferential pressure distribution is uneven, and the thickness of the gas film 12 fluctuates greatly (e.g., with 3 grooves, the pressure difference between adjacent grooves can reach 30%), which can easily lead to eccentricity of the gas film 12 due to excessively high local pressure, causing vibration of the rotor shaft 4. If the number of grooves is too large (e.g., >12), the distance between the grooves is too small, the flow interference between adjacent grooves is enhanced (gas is squeezed against each other between grooves), the flow resistance increases, the pressure build-up efficiency decreases, and the processing difficulty increases (too small a groove spacing easily leads to processing errors). In this embodiment, the number of spiral grooves 11 is set to 8 to 10, which can form a uniformly distributed airflow channel within the axial clearance, avoiding dead zones in gas flow, ensuring the continuous and stable operation of the gas film 12, and preventing sealing failure caused by local high or low pressure.

[0035] Optionally, the groove-to-dam ratio of the spiral groove 11 is 0.8 to 1.2. This setting balances the uniformity of the gas film 12 and the pumping efficiency. Specifically, if the groove-to-dam ratio is too small (<0.5), i.e., the groove width is too large and the dam width is too small, the bearing area is insufficient, the total bearing capacity of the gas film 12 decreases, and although the gas flow rate is sufficient, the pressure cannot be effectively transmitted to the bearing surface, resulting in poor stability of the gas film 12, which may lead to breakage of the gas film 12 or local high pressure, weakening the sealing effect. If the groove-to-dam ratio is too large (>2), i.e., the dam width is too large and the groove width is too small, the gas delivery channel is narrow, the flow rate is insufficient, the dam surface pressure cannot be fully established, and the gas film 12 thickness is easily uneven due to insufficient gas supply, resulting in a sudden increase in local pressure, which leads to a decrease in gas pumping efficiency, making it difficult to form a continuous gas film 12, and corrosive gas may seep into the sealing interface. In this embodiment, the groove-to-dam ratio of the spiral groove 11 is set to 0.8 to 1.2, which can ensure both sufficient gas flow rate and a sufficiently large bearing area, thereby achieving a balance between the uniformity of the gas film 12 and the pumping efficiency.

[0036] Optionally, the width of the helical groove 11 gradually decreases from the edge to the center of the rotor element 5. This configuration optimizes the dynamic balance and pressure distribution of the gas flow, ensuring the formation of a more stable gas film 12. Specifically, the cross-section of the helical groove 11 gradually narrows (i.e., the width decreases from the outside to the inside), and combined with the design of the helix angle, it can more effectively transport gas from the outer edge to the center. This tapered structure generates stronger shear and centrifugal forces during rotation, accelerating the gas movement towards the center, thereby forming a more stable gas film 12 between the stationary and moving rings.

[0037] The dynamic sealing structure of the vacuum pump in this embodiment is provided on the end face of the rotor element 5 facing the side wall of the stator 1 or on the side wall of the stator 1 facing the end face of the rotor element 5. When the rotor element 5 rotates relative to the stator 1, it can drive the process gas to move in a spiral direction, thereby forming a gas film in the axial gap between the end face of the rotor element 5 and the side wall of the stator 1. This gas film can achieve isolation and at the same time stabilize the pressure between the end face of the rotor element 5 and the side wall of the stator 1, reducing pressure fluctuations. This reduces the pressure difference on both sides of the sealing device 6, reduces the contact between the process gas and the sealing device 6, thereby reducing the corrosion of the sealing device 6 by the process gas and improving the service life of the sealing device 6.

[0038] One or more embodiments in this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this specification should be included within the protection scope of this application.

[0039] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dynamic sealing structure for a vacuum pump, the vacuum pump comprising a stator and a pair of meshing rotors, the stator having a cavity, the rotors comprising a rotor shaft and rotor elements, the rotor shaft being rotatably disposed in the cavity via bearings, the rotor elements being disposed on the rotor shaft and located within the cavity, and an axial clearance existing between the end face of the rotor element and the side wall of the stator, characterized in that, The dynamic sealing structure is disposed on the end face of the rotor element facing the stator sidewall or on the sidewall of the stator facing the end face of the rotor element. The dynamic sealing structure includes a plurality of spiral grooves. The spiral grooves are used to drive the process gas to move along the spiral direction when the rotor element rotates relative to the stator, so as to form a gas film in the axial gap.

2. The dynamic sealing structure for a vacuum pump according to claim 1, characterized in that, The rotor element includes multiple stages of rotor elements, and the dynamic sealing structure is disposed on the end face of the last stage rotor element facing the stator sidewall or on the sidewall of the stator facing the end face of the rotor element.

3. The dynamic sealing structure for a vacuum pump according to claim 1, characterized in that, The helical grooves of the two meshing rotors have opposite helical directions.

4. The dynamic sealing structure for a vacuum pump according to claim 1, characterized in that, The helix angle of the spiral groove is 20°~30°.

5. The dynamic sealing structure for a vacuum pump according to claim 1, characterized in that, The depth of the spiral groove is 5~15μm.

6. The dynamic sealing structure for a vacuum pump according to claim 1, characterized in that, The number of spiral grooves is 8 to 10.

7. The dynamic sealing structure for a vacuum pump according to claim 1, characterized in that, The groove-to-dam ratio of the spiral groove is 0.8 to 1.

2.

8. The dynamic sealing structure for a vacuum pump according to claim 1, characterized in that, The width of the spiral groove gradually decreases from the edge of the rotor element to the center.

9. A vacuum pump rotor, characterized in that, It is equipped with the dynamic sealing structure for vacuum pumps as described in any one of claims 1-8.

10. A vacuum pump, characterized in that, Includes the vacuum pump rotor as described in claim 9.

Images