A claw vacuum pump rotor with axial and radial labyrinth throttling structures

Abstract

This invention relates to the field of vacuum pump technology, specifically to a claw-type vacuum pump rotor with an axial and radial labyrinth throttling structure. It solves the problems of insufficient axial and radial synchronous sealing and inadequate operational reliability in existing technologies. The rotor includes a rotor body with a radial throttling zone on its radial working surface. This radial throttling zone cooperates with the casing to form a radial non-contact throttling channel. An axial throttling zone is also provided on the end face of the rotor body, arranged along its contour. This axial throttling zone cooperates with an end cover to form an axial non-contact throttling channel. The beneficial effects are: by integrating axial and radial throttling zones on the rotor body to form an axial and radial non-contact throttling channel, the leakage path between the high-pressure chamber and the low-pressure chamber is significantly extended. Gas leakage requires multiple stages of throttling and eddy current energy dissipation, achieving good sealing performance even with a relatively large mechanical operating clearance, effectively reducing internal leakage.

Description

Technical Field

[0001] This invention relates to the field of vacuum pump technology, and in particular to a claw-type vacuum pump rotor with an axial and radial labyrinth throttling structure. Background Technology

[0002] Claw vacuum pumps have attracted widespread attention due to their oil-free operation, compact structure, and reliable operation. They achieve gas intake, compression, and discharge by using a pair of meshing rotors to create a periodically changing working volume within the pump chamber. To obtain high ultimate vacuum and volumetric efficiency, claw vacuum pumps typically rely on improving dimensional accuracy to achieve sealing, specifically... Figure 1 As shown, sealing is achieved by reducing the gap between the rotor and the housing, and the gap between the rotors. However, this method requires extremely high machining and assembly precision, and during operation, the rotor is prone to rubbing or local contact due to temperature rise, thermal expansion, dust intrusion, or shaft misalignment, which can lead to rotor surface damage, reduced efficiency, or even jamming.

[0003] The prior art patent with publication number CN112065722A discloses a claw pump rotor end face sealing structure, which sets a sealing groove on the rotor end face, and sets a sealing element and an elastic element in the sealing groove. The elastic element pushes the sealing element to contact the end face of the cylinder body. The sealing element uses a solid self-lubricating material to reduce the leakage of the end face gap.

[0004] This existing technology primarily improves the end-face seal of claw pumps by using contact sealing to enhance the sealing effect. However, it still has significant limitations: First, this technology only focuses on axial end-face sealing and does not address the radial seal between the rotor and the pump casing, failing to solve the problem of radial clearance leakage and making it difficult to achieve coordinated axial and radial sealing. Second, its sealing effect is highly dependent on the continuous contact between the seal and the end face and the wear resistance of its own material. Under harsh conditions such as high temperature, high speed, or the presence of hard particles, the wear rate of the seal itself will accelerate significantly, and even with elastic element compensation, its long-term reliability still faces challenges. Once the seal wears excessively or suffers localized damage, the sealing effect will deteriorate drastically, and the debris generated by wear may contaminate the pump cavity. Summary of the Invention

[0005] This invention proposes a claw-type vacuum pump rotor with axial and radial labyrinth throttling structures, which solves the problems of insufficient axial and radial synchronous sealing and inadequate operational reliability in the prior art.

[0006] The technical solution of this invention is implemented as follows:

[0007] A claw-type vacuum pump rotor with axial and radial labyrinth throttling structures includes a rotor body. A radial throttling region is provided on the radial working surface of the rotor body, which cooperates with the casing to form a radial non-contact throttling channel. An axial throttling region is provided on the end face of the rotor body, arranged along the contour of the end face, which cooperates with an end cover to form an axial non-contact throttling channel. The radial non-contact throttling channel is used to suppress radial internal leakage between the high-pressure chamber and the low-pressure chamber, and the axial non-contact throttling channel is used to suppress axial leakage between the high-pressure chamber and the low-pressure chamber.

[0008] Furthermore, both the radial and axial throttling regions include multi-stage labyrinth tooth structures.

[0009] Furthermore, the multi-stage labyrinth tooth structure forms a multi-stage throttling gap between the casing or end cover. This allows high-pressure gas to flow through axial and radial non-contact throttling channels when leaking to the low-pressure side, undergoing multiple throttling and eddy current energy dissipation processes.

[0010] Furthermore, the multi-stage labyrinth tooth structure includes multiple labyrinth tooth grooves formed on the rotor body. The labyrinth tooth grooves can serve as temporary storage spaces for tiny particles. During operation, solid particles entering the labyrinth channel are easily thrown to the bottom of the labyrinth tooth grooves and settle under the centrifugal force generated by the rotor rotation, thereby reducing the probability of particles entering the main sealing gap and protecting the critical gap between the rotor and the pump casing.

[0011] Furthermore, the labyrinth grooves can be rectangular, trapezoidal, or serrated. A combination of these three types can also be used to enhance the vortex flow and energy dissipation effect of the gas within the throttling channel.

[0012] Furthermore, the tips of the multi-stage labyrinth tooth structure are coated with an easy-wear coating. During initial rotor operation or hot deformation, the easy-wear coating can form an adaptive, slight run-in with the housing or end cover, thereby achieving a near-zero gap labyrinth seal effect without hard contact, further improving sealing performance and reducing the risk of rotor damage.

[0013] Furthermore, the material for the wear-resistant coating is polytetrafluoroethylene, polyimide, or a composite material of the above. This type of material exhibits good wear resistance, lubricity, and adaptability.

[0014] Furthermore, the multi-level labyrinth tooth structure has no fewer than 3 levels and no more than 10 levels of teeth. This causes the gas to undergo multiple throttling, expansion, and vortex dissipation processes during flow.

[0015] Furthermore, the rotor body is either a female rotor or a male rotor.

[0016] Furthermore, both the female and male rotors are rotatably mounted within the casing, with their radial surfaces in contact with each other. The rotation of the female and male rotors enables meshing transmission to complete the intake, compression, and discharge of gas.

[0017] The beneficial effects of this invention are: by integrating axial and radial throttling zones on the rotor body, forming axial and radial non-contact throttling channels, the leakage path between the high-pressure chamber and the low-pressure chamber is significantly extended. When gas leaks, it needs to undergo multiple stages of throttling and eddy current energy dissipation. Under the condition of allowing a large mechanical operating clearance, a good sealing effect can still be obtained, effectively reducing internal leakage.

[0018] Employing a non-contact labyrinth throttling seal, which does not rely on the minute contact gap between the rotor and the pump casing and end cover, it can significantly reduce the risk of abrasion, wear and jamming caused by rotor thermal expansion, phase shift or dust particle intrusion. At the same time, the labyrinth grooves can temporarily store dust particles, and the wear-resistant coating can achieve self-adaptive running-in, further improving the rotor's adaptability and service life under harsh conditions such as high temperature, high speed and high dust.

[0019] The multi-stage labyrinth structure is integrated with the rotor body, enabling the sealing function to be achieved by the rotor itself. This reduces the reliance on high-precision pump housings and additional sealing elements, thereby significantly improving the operational reliability of claw vacuum pumps under high temperature, high dust, and high speed conditions. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the rotor structure of a claw-type vacuum pump in the prior art;

[0022] Figure 2 This is a schematic diagram of the claw-type vacuum pump rotor in this application;

[0023] Figure 3 The radial sealing structure of the claw vacuum pump rotor in this application;

[0024] Figure 4 This is the axial sealing structure for the claw-type vacuum pump rotor in this application;

[0025] Figure 5 The labyrinth toothed groove is a claw vacuum pump that can be considered for use in this application.

[0026] In the figure: 1. Female rotor, 2. Male rotor, 3. Housing, 4. Clearance between rotor and housing, 5. Clearance between rotors, 6. Radial non-contact throttling channel, 7. Axial non-contact throttling channel, 11. Radial throttling zone, 12. Axial throttling zone, 81. Rectangular toothed groove, 82. Trapezoidal toothed groove, 83. Sawtooth toothed groove. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1, such as Figure 2 , Figure 3 , Figure 4 As shown, this application embodiment provides a claw vacuum pump rotor with an axial and radial labyrinth throttling structure. The claw vacuum pump rotor includes a rotor body 10. A radial throttling area 11 is provided on the radial working surface of the rotor body 10. The radial throttling area 11 cooperates with the housing 3 to form a radial non-contact throttling channel 6. An axial throttling area 12 is provided on the end face of the rotor body 10, which is arranged along the contour of the end face of the rotor body 10. The axial throttling area 12 cooperates with the end cover to form an axial non-contact throttling channel 7.

[0029] The radial working surface refers to the cylindrical surface on the rotor body that is close to and moves relative to the inner wall of the casing 3. It is the main path for radial leakage of gas between the rotor and the casing. The claw vacuum pump rotor integrates a radial throttling region 11 and an axial throttling region 12 on its radial working surface and end face, respectively, forming a cooperative axial non-contact throttling channel 7 and a radial non-contact throttling channel 6. The leakage path of high-pressure gas to low-pressure side is physically segmented and extended, and the gas must flow through the axial non-contact throttling channel 7 or the radial non-contact throttling channel 6. When the gas flows through these channels, due to physical constraints such as abrupt changes in channel cross-section and changes in flow direction, its pressure and velocity change drastically, generating multi-stage throttling effects and local eddies. This converts the pressure energy of the gas into heat energy and dissipates it, thus effectively reducing the internal leakage flow even with a certain mechanical clearance between the rotor body 10 and the casing 3 and end cover.

[0030] In one embodiment, both the radial throttling region 11 and the axial throttling region 12 include a multi-stage labyrinth tooth structure. This multi-stage labyrinth tooth structure is a continuous convex-concave structure directly machined onto the corresponding surfaces of the rotor body 10, such as a series of alternating convex teeth and grooves. These convex teeth and grooves are arranged sequentially along the gas leakage direction, collectively forming a tortuous, elongated gas flow path. Furthermore, employing this multi-stage labyrinth tooth structure can significantly increase the resistance and path length of the leaking gas flow, forcing the gas to continuously undergo throttling, expansion, and kinetic energy loss as it passes through the narrow gap between the multi-stage convex teeth and the stationary component, thereby greatly enhancing the overall throttling and sealing effect and compensating for the insufficient sealing capacity of a single, larger gap.

[0031] In one embodiment, a multi-stage labyrinth tooth structure forms a multi-stage throttling gap between the housing 3 and the end cover. Each stage of the labyrinth tooth maintains a small, uniform gap between its tip and the corresponding inner wall of the housing 3 or the inner surface of the end cover; this is the multi-stage throttling gap. This gap size is much larger than the gap required for conventional adhesive sealing, allowing the rotor body 10 to expand to a certain extent under heat without contact. When high-pressure gas passes through this series of throttling gaps sequentially, a throttling and pressure reduction occurs at each gap, converting part of the gas's pressure energy into the kinetic energy of a high-speed jet. Subsequently, it suddenly expands within the adjacent tooth cavity, and the kinetic energy is dissipated into internal energy due to eddies and friction. Furthermore, by employing this multi-stage throttling gap structure, the sealing effect does not depend on the absolute size of a single gap, but is achieved through the cumulative throttling effect of multiple stages in series, thus achieving excellent sealing performance while ensuring reliability.

[0032] In one embodiment, the multi-stage labyrinth tooth structure includes a plurality of labyrinth tooth slots formed on the rotor body 10. For example... Figure 5 As shown, the labyrinthine grooves refer to the recessed spaces formed between adjacent protrusions in a multi-stage labyrinthine tooth structure. These labyrinthine grooves not only constitute the space for gas expansion and eddy current dissipation but also play an additional role in the rotor's rotational motion. Specifically, when gas containing tiny solid particles enters the non-contact throttling channel, the particles are subjected to centrifugal force generated by the rotor's rotation while flowing with the gas. Due to the presence of the labyrinthine grooves, particles are more easily thrown to the bottom of the grooves under centrifugal force and settle or temporarily remain there, thereby reducing the probability of particles being directly carried into the more critical main sealing area between the rotor body 10 and the housing 3. Furthermore, by adopting a structure including labyrinthine grooves, gas throttling and sealing are achieved while also providing a buffering function for dust particles, protecting key mating surfaces, and improving the rotor's adaptability and lifespan under dusty conditions.

[0033] In one embodiment, for the aforementioned labyrinthine toothed groove, such as Figure 5As shown, the labyrinthine tooth grooves are rectangular tooth grooves 81, trapezoidal tooth grooves 82, or sawtooth tooth grooves 83. As a specific implementation, the groove wall of the rectangular tooth groove 81 is perpendicular to the rotor surface; the groove wall of the trapezoidal tooth groove 82 is inclined, which helps to guide a gentle change in the gas flow direction, reducing flow separation losses. Simultaneously, its inclined wall surface may be more conducive to particles sliding along the wall surface to the groove bottom under centrifugal force. The sawtooth tooth groove 83 has sharp tooth tips and steep tooth sides, which can more strongly disturb the airflow, generating more significant vortices and turbulence, thereby enhancing the energy dissipation effect. These three tooth shapes or combinations thereof can be selected according to different sealing pressures, media characteristics, and processing requirements to achieve optimal throttling and particle-resistant effects.

[0034] Example 2, based on Example 1, provides a claw-type vacuum pump rotor with an axial and radial labyrinth throttling structure. The tips of the multi-stage labyrinth tooth structure are coated with a wear-resistant coating. This wear-resistant coating is directly applied to or attached to the surface of the labyrinth tooth tips, i.e., the part closest to the housing 3 or end cover. During initial installation or operation of the rotor, when thermal deformation reduces the gap between the rotor body 10 and stationary components, the wear-resistant coating at the tooth tips may undergo slight, limited adaptive contact and break-in with the housing 3 or end cover. Due to the characteristics of the coating material, this break-in is gentle and will not cause hard damage to the rotor body 10 substrate or stationary components. After break-in, the tooth tip gap can be further reduced, tending towards a more optimized equilibrium state.

[0035] In one embodiment, the wear-resistant coating material is polytetrafluoroethylene (PTFE), polyimide, or a composite of the above materials. PTFE has an extremely low coefficient of friction and good self-lubricating properties, while polyimide exhibits excellent high-temperature stability and wear resistance. Coatings made from these materials or their composites ensure that, in the event of slight contact, the coating itself preferentially undergoes minor wear, thereby protecting the more valuable rotor body 10 and housing 3 components while maintaining good operational stability.

[0036] In one embodiment, the multi-stage labyrinth tooth structure has no fewer than 3 and no more than 10 tooth stages. The number of tooth stages refers to the number of protruding teeth arranged along the gas leakage direction. With fewer than 3 stages, the throttling stages are too few, the gas pressure decay process is insufficient, and it is difficult to achieve the ideal sealing effect. With more than 10 stages, although the sealing effect may theoretically continue to improve, it increases the axial length or radial dimension of the rotor body 10, making the structure more complex, significantly increasing processing costs, and placing higher demands on the overall structural layout of the pump. Using 3 to 10 tooth stages can achieve a good balance between sealing performance, structural compactness, and process economy while ensuring effective multi-stage throttling and a sufficiently long leakage path.

[0037] In one embodiment, the rotor body 10 is either a female rotor 1 or a male rotor 2. Both the female rotor 1 and the male rotor 2 are rotatably mounted within the housing 3, and their radial surfaces are in contact with each other. In actual claw vacuum pumps, the profiles of the female rotor 1 and the male rotor 2 mesh with each other, and their radial surfaces periodically contact or maintain a very small gap during rotation to separate and transport gas. In this application, regardless of whether a labyrinth throttling structure is provided on the rotor, the basic meshing and fit relationship of this pair of rotors within the housing 3 remains unchanged.

[0038] It should be noted that, in some optional embodiments, the aforementioned radial throttling zone 11 and axial throttling zone 12 can be located within a certain axial length range of the rotor body 10 near the exhaust side. The advantage of this design is that the high-pressure gas enters the throttling zone before being discharged from the pump chamber, which most effectively suppresses reverse leakage from the high-pressure exhaust chamber to the low-pressure region, directly improving the pump's volumetric efficiency and ultimate vacuum.

[0039] In some alternative embodiments, the aforementioned axial throttling zone 12 can completely replace the conventional contact mechanical seal or axial bearing seal located between the rotor end and the end cover. This means that the axial positioning and sealing of the rotor rely entirely on the axial non-contact throttling channel 7 formed by the axial throttling zone 12 and the end cover, thereby completely eliminating friction loss and wear risk in this area, which is especially beneficial for high-speed operating conditions.

[0040] It should also be noted that "arranged along the outline of the rotor body end face" in the claims means that the labyrinth tooth structure in the axial throttling zone 12 is arranged along the outer edge shape of the rotor end face to ensure that an effective axial throttling channel 7 can be formed in the entire circumferential direction of the end face, thereby suppressing axial leakage from different directions.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A claw-type vacuum pump rotor with axial and radial labyrinth throttling structures, characterized in that, The rotor body includes a radial throttling area (11) on its radial working surface. The radial throttling area (11) and the housing (3) cooperate to form a radial non-contact throttling channel (6). An axial throttling area (12) is arranged along the contour of the rotor body end face. The axial throttling area (12) and the end cover cooperate to form an axial non-contact throttling channel (7).

2. The claw-type vacuum pump rotor according to claim 1, characterized in that, Both the radial and axial throttling regions include multi-stage labyrinth tooth structures.

3. The claw-type vacuum pump rotor according to claim 2, characterized in that, The multi-stage labyrinth tooth structure forms a multi-stage throttling gap between the housing (3) or the end cover.

4. The claw-type vacuum pump rotor according to claim 3, characterized in that, The multi-stage labyrinth tooth structure includes multiple labyrinth tooth grooves formed on the rotor body.

5. The claw-type vacuum pump rotor according to claim 4, characterized in that, The labyrinth tooth groove is a rectangular tooth groove (81), a trapezoidal tooth groove (82), or a sawtooth tooth groove (83).

6. The claw-type vacuum pump rotor according to any one of claims 2 to 5, characterized in that, The tips of the multi-level labyrinth tooth structure are coated with an easy-wear coating.

7. The claw-type vacuum pump rotor according to claim 6, characterized in that, The material for the easily worn coating is polytetrafluoroethylene, polyimide, or a composite material of the above materials.

8. The claw-type vacuum pump rotor according to claim 2, characterized in that, The number of tooth levels in a multi-level labyrinth tooth structure shall be no less than 3 and no more than 10.

9. The claw-type vacuum pump rotor according to claim 1 or 8, characterized in that, The rotor body is either a female rotor (1) or a male rotor (2).

10. The claw-type vacuum pump rotor according to claim 9, characterized in that, Both the female rotor (1) and the male rotor (2) are rotatably mounted inside the housing (3), and the radial surfaces of the female rotor (1) and the male rotor (2) are in contact with each other.

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