Oil seal and airtight sealing devices for dry vacuum pumps and rotating machinery

Abstract

This disclosure relates to an oil-sealing and airtight sealing device for use in dry vacuum pumps and rotating machinery, and includes a fuel tank cap, oil slinger, fastening nut, bearing, bearing mounting seat, mounting plate, shaft seal, O-ring, expansion ring, stator, and rotor. The oil-sealing and airtight sealing device for use in dry vacuum pumps and rotating machinery of this disclosure has a high sealing effect, is applicable to dry vacuum pumps, has a simple sealing structure, is easy to implement, the sealing design is performed only on the component parts, occupies little space, does not require the addition of new parts, is easy to manufacture, and is low cost.

Description

Technical Field

[0001] "Cross - reference to Related Applications" This disclosure claims the priority of a Chinese patent application with application number 202310322395.6 and invention title "Dry Vacuum Pump and Oil - Sealing and Air - Tight Sealing Device for Rotary Machinery", which was filed with the China National Intellectual Property Administration on March 29, 2023, and all of its contents are incorporated into this disclosure by reference.

[0002] This disclosure relates to the technical field of vacuum pumps, and particularly to dry vacuum pumps and oil - sealing and air - tight sealing devices used in rotary machinery.

Background Art

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

[0004] The two axes of the rotors of the vacuum pump are parallel to each other. The rotor is composed of an impeller and a shaft. There are minute gaps between the impellers, between the impeller and the housing and the wall plate to avoid contact with each other. The two rotors are driven by a motor via a pair of synchronous gears and perform constant - speed rotation in opposite directions. Due to the meshing of the two impellers, the pump intake and exhaust ports are not directly connected. The impeller, housing, and wall plate enclose a closed cell volume. With the continuous rotation of the impeller, the cell volume is always in a cycle of intake - compression - conveyance - exhaust, constantly discharging the air and dust in the cavity outside the pump to achieve the process requirements.

[0005] A dry vacuum pump is mainly composed of rotor and stator components, which are sealed together in an oil-sealed, airtight structure that divides it into two chambers. One chamber is the working fluid transport chamber, i.e., the process by-product cavity, and the other chamber is the cooling chamber that provides lubrication to bearings, gears, etc., i.e., the lubricating oil chamber. The fluids in the two chambers must be sealed to each other and cannot communicate with one another. If process by-products leak into the lubricating oil chamber, it is likely to cause contamination of the lubricating oil and affect the service life of the pump. If lubricating oil leaks into the process by-product cavity, it is likely to cause environmental pollution, and at the same time, a lack of lubricating oil will also affect the service life of the pump. In order to balance the internal pressure of the two chambers, the process by-product cavity and the lubricating oil chamber, the two chambers must also have a gas passage and cannot be completely sealed off.

[0006] Conventional technology has relatively few oil-sealed and airtight sealing products that can be combined. In particular, the dry vacuum pump industry faces several technical problems with conventional sealing products, including low sealing effectiveness, specific requirements for the operating environment, complex sealing structures, large footprint, and high cost.

[0007] Therefore, overcoming the shortcomings of the above-mentioned conventional technical solutions and providing a sealing system that is compact in structure, has high sealing effect, is low in cost, and is applicable to the vacuum pump industry is an urgent technical problem in this field that needs to be solved. [Overview of the project] [Problems that the invention aims to solve]

[0008] To overcome the shortcomings of the above-mentioned prior art, this disclosure provides an oil-sealing and airtight sealing device for use in dry vacuum pumps and rotating machinery. Specifically, this disclosure employs the following technical solutions. [Means for solving the problem]

[0009] An oil-sealing and airtight sealing device for use in dry vacuum pumps and rotating machinery, comprising a fuel tank cap (1), oil slinger (3), tightening nut (4), bearing (5), bearing fixing seat (6), fixing plate (7), shaft seal (8), O-ring (9), expansion ring (10), stator (11), rotor (13), The fuel tank cap (1), oil sling (3), tightening nut (4), bearing (5), bearing fixing seat (6), and the side of the fixing plate (7) adjacent to the bearing fixing seat (6) constitute a lubricating oil chamber (2). The shaft seal (8), O-ring (9), expansion ring (10), stator (11), rotor (13), and the side of the fixed plate (7) adjacent to the shaft seal (8) constitute a process by-product cavity (12), where, The fixing plate (7) and the shaft seal (8) are sequentially fitted onto the rotor (13), the expansion ring (10) is positioned between the fixing plate (7) and the rotor (13), and the O-ring (9) is positioned between the shaft seal (8) and the rotor (13), providing airtightness and oil seal to the lubricating oil chamber (2) and the process byproduct cavity (12), respectively.

[0010] Furthermore, a fixed plate step is provided on the surface of the rotor (13), and the fixed plate (7) is attached to the fixed plate step. An expansion ring mounting groove is provided in the stepped portion of the fixing plate or the fixing plate (7), and the expansion ring (10) is mounted in the expansion ring mounting groove. Furthermore, a high-pressure intake hole (21) is provided in the fixing plate (7), and the space inside the high-pressure intake hole (21) is in communication with the surface of the rotor (13). Due to the pressure difference on both sides, the expansion ring (10) comes into close contact with the downstream end face of the expansion ring mounting groove.

[0011] Furthermore, there are multiple expansion rings (10), and the multiple expansion rings (10) are provided at intervals along the length of the rotor (13).

[0012] Furthermore, an oil-sealed step is provided on the surface of the rotor (13), and the shaft seal (8) is attached to the oil-sealed step of the rotor. An O-ring mounting groove is provided in the oil seal step portion or the shaft seal (8), and the O-ring (9) is mounted in the O-ring mounting groove.

[0013] Furthermore, the bearing (5) is fitted onto the rotor (13) on the side away from the fixing plate (7), the bearing fixing seat (6) is fitted onto the outside of the bearing (5), and the bearing fixing seat (6) is fixed to the fixing plate (7). The rotor (13) is located on one side surface of the lubricating oil chamber (2) and has a male thread near the mounting position of the bearing (5). The tightening nut (4) is fitted onto the male thread and used to secure the bearing (5).

[0014] Furthermore, a non-contact seal is used between the bearing fixing seat (6) and the shaft seal (8).

[0015] Furthermore, the non-contact seal is specifically a labyrinth seal structure, and has a combination of small irregularities between the shaft seal (8) and the bearing fixing seat (6).

[0016] Furthermore, the fuel tank cap (1) is fixedly connected to the fixing plate (7), The oil slinger (3) is located inside the lubrication chamber (2) and is fixed to the rotor (13). The inner surface of the fuel tank cap (1) is provided with a slope and is used to guide the lubricating oil splashed from the oil slinger (3) to the bearing (5).

[0017] Furthermore, the stator (11) has a hollow structure, and the rotor (13) is attached inside the stator (11).

Advantages of the Invention

[0018] The oil seal and airtight seal device used in the dry vacuum pump and rotary machine of the present disclosure has a high sealing effect, is applicable to a dry vacuum pump, has a simple seal structure, is easy to realize, only performs seal design on component parts, has a small occupied space, does not require addition of new parts, is easy to process, and has a low cost.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic structural diagram of the oil seal and airtight seal device used in the dry vacuum pump and rotary machine of the present disclosure. [Figure 2] It is a schematic diagram of the airtight structure of the seal device of the present disclosure. [Figure 3] It is a schematic structural diagram of the expansion ring of the seal device of the present disclosure. [Figure 4] It is a schematic structural diagram of the oil seal of the seal device of the present disclosure.

Modes for Carrying Out the Invention

[0020] Hereinafter, the present disclosure will be further described with reference to the drawings. The following examples are for more clearly explaining the technical solution of the present disclosure, and thus the protection scope of the present disclosure cannot be limited thereby. Note that all the following detailed descriptions are exemplary and are intended to provide further explanations of the present disclosure.

[0021] Unless otherwise expressly stated, all technical and scientific terms used in this disclosure are used in the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. Note that the terms used herein are for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments of this disclosure. As used herein, unless otherwise expressly stated in the context, the singular form is intended to include the plural form, and when the terms "comprising" and / or "include" are used in this disclosure, it should be understood that features, steps, operations, devices, modules and / or combinations thereof are present.

[0022] Referring to FIG. 1, a specific embodiment of the present disclosure relates to an oil seal and airtight sealing device used for a dry vacuum pump and a rotating machine, and includes a fuel tank cap 1, an oil slinger 3, a tightening nut 4, a bearing 5, a bearing fixing seat 6, a fixing plate 7, a shaft seal 8, an O-ring 9, an expansion ring 10, a stator 11, and a rotor 13.

[0023] The sides of the fuel tank cap 1, the oil slinger 3, the tightening nut 4, the bearing 5, the bearing fixing seat 6, and the fixing plate 7 adjacent to the bearing fixing seat 6 constitute a lubricating oil chamber 2.

[0024] The sides of the shaft seal 8, the O-ring 9, the expansion ring 10, the stator 11, the rotor 13, and the fixing plate 7 adjacent to the shaft seal 8 constitute a process by-product cavity 12.

[0025] In the sealing device, the fuel tank cap 1 is fixedly connected to the fixing plate 7.

[0026] The oil slinger 3 is located inside the lubrication chamber 2 and is fixed to the rotor 13. The inner surface of the fuel tank cap 1 is provided with a slope, the slope facing the oil slinger 3, and is used to guide the lubricating oil splashed from the oil slinger 3 to the bearing 5. It should be understood that the slope is located above the oil slinger 3 and the bearing 5, and when lubricating oil is splashed, the slope guides the lubricating oil splashed from the oil slinger 3 to the bearing 5 and the bearing mounting seat 6, thereby lubricating the bearing 5. At the same time, the lubricating oil splashed to the bearing mounting seat 6 flows further to the shaft seal 8 located below the bearing mounting seat 6, thereby lubricating the shaft seal 8.

[0027] Specifically, as shown in Figure 4, the black area at location A in Figure 4 indicates that the lubricating oil splashed from the oil slinger 3 slides down onto the bearing fixing seat 6, further lubricating the bearing 5. The area at location B in Figure 4 shows the lubricating oil that has flowed to the shaft seal 8, lubricating the shaft seal 8.

[0028] The bearing 5 is fitted onto the surface of the rotor 13, the bearing fixing seat 6 is fitted onto the outside of the bearing 5, the bearing fixing seat 6 is fixed to the side of the fixing plate 7 facing the lubrication oil chamber 2, the shaft seal 8 and the fixing plate 7 are fitted onto the rotor 13 in sequence, and the shaft seal 8 is located between the bearing fixing seat 6 and the fixing plate 7.

[0029] The rotor 13 is located on one side surface of the lubrication chamber 2 and has a male thread near the mounting position of the bearing 5. The tightening nut 4 is fitted onto the male thread and used to secure the bearing 5.

[0030] The stator 11 has a hollow structure, and the rotor 13 is mounted inside the stator 11.

[0031] Furthermore, based on the connection relationships of each of the above structures, as shown in Figures 2 and 4, a fixed plate step portion 13a is provided on the surface of the rotor 13, the fixed plate 7 is attached to the fixed plate step portion 13a, and an expansion ring mounting groove 10a is provided in the fixed plate step portion 13a or the fixed plate 7, and the expansion ring 10 is mounted in the expansion ring mounting groove 10a. In other words, the expansion ring 10 is located between the fixed plate 7 and the rotor 13, forming an airtight structure, and during operation, this airtight structure prevents the process byproduct medium in the process byproduct cavity 12 from entering the lubricating oil chamber through the gap and causing lubricating oil contamination.

[0032] It should be understood that the expansion ring mounting groove is an annular groove, which is wound around the outside of the rotor and used to mount the expansion ring. The installation position of the expansion ring mounting groove is not particularly limited; for example, the expansion ring mounting groove may be provided on the stepped portion of the fixed plate on the rotor, or of course, on the side of the fixed plate facing the rotor, as long as a seal is achieved between the rotor and the fixed plate.

[0033] In some preferred embodiments, as shown in Figure 4, the expansion ring mounting groove 10a is located on the stepped portion 13a of the fixing plate on the outer surface of the rotor 13.

[0034] Referring to Figure 2, this is a schematic diagram of the airtight structure of the present disclosure. A high-pressure intake hole 21 is provided in the fixed plate 7, and the space inside the high-pressure intake hole 21 communicates with the surface of the rotor 13. Because a gap 22 exists between the rotor 13 and the fixed plate 7, if it were not airtight, the process byproduct medium in the process byproduct cavity 12 would enter the lubricating oil chamber 2 through the gap 22 during operation, causing lubricating oil contamination. In order to balance the internal pressure of the two chambers, the process byproduct cavity 12 and the lubricating oil chamber 2, it is necessary to leave a gas passage between the two chambers, and complete isolation is not possible. Therefore, an expansion ring 10 is used here to create an airtight seal, and the high-pressure intake hole 21 is left in the fixed plate 7 to ensure sealing performance.

[0035] Referring to Figure 3, this is a schematic diagram of the structure of the expansion ring 10 of this disclosure. Based on the characteristics of the dry vacuum pump, such as the operating speed and working medium, the airtight device employs an expansion ring seal configuration. The expansion ring seal is named for its use of a self-expanding seal ring with a notch, and is a device that seals using the principles of occlusion and throttling. Multiple expansion rings are placed in an annular groove machined into the shaft shoulder, and the expansion rings adhere to the inner bore of the stator seal seat by their own elastic force, forming a pretension type seal on the outer circular portion of the expansion ring, and gas leaks downstream only through the gap between the expansion ring and the annular groove. During operation, the expansion ring 10 adheres tightly to the downstream end face of the expansion ring groove due to the pressure difference on both sides, and the high-pressure gas that enters the gap from the high-pressure intake hole 21 fills the back gap space, further strengthening the seal between the outer circle of the expansion ring 10 and the inner bore of the stator seal seat, with the only remaining leakage passage being the notch in the expansion ring 10. Because the notch is very small, only a very small amount of gas can leak out, and at the same time, the notch can balance the pressure inside the two chambers within the pump.

[0036] To improve airtightness, in some preferred embodiments, as shown in Figure 2, a plurality of expansion rings 10 can be arranged in parallel, and the plurality of expansion rings 10 can be spaced along the length of the rotor 13, so that after being sealed through several expansion rings 10, the amount of gas that can leak out is reduced.

[0037] Naturally, it should be understood that when multiple expansion rings are provided, multiple expansion ring mounting grooves must be provided in the stepped portion of the fixing plate on the rotor surface, and the multiple expansion rings are correspondingly provided in the multiple expansion ring mounting grooves. As shown in Figure 4, two expansion ring mounting grooves 10a are provided in the stepped portion 13a of the fixing plate, and the corresponding expansion rings 10 are housed in the two expansion ring mounting grooves 10a, and a high-pressure intake hole 21 is opened in the fixing plate 7, and the high-pressure intake hole 21 is located between the two expansion rings 10 to improve airtightness.

[0038] The expansion ring 10 is manufactured using cast iron material, is highly precise, can automatically compensate after wear, and has a long service life.

[0039] Furthermore, referring to Figure 4, we have a schematic diagram of the oil seal structure of the present disclosure. The lubricating oil seal of the present disclosure is divided into two locations: the first is a seal between the shaft seal 8 and the rotor 13, and the second is a seal between the bearing fixed seat 6 and the shaft seal 8. This oil seal structure at these two locations prevents the lubricating oil from the lubricating oil chamber from leaking into the process byproduct cavity, thereby avoiding environmental pollution and ensuring that the amount of lubricating oil used is sufficient.

[0040] As shown in Figure 4, for the seal between the first shaft seal 8 and the rotor 13, since both the shaft seal 8 and the rotor 13 are rotating members and are relatively stationary, the seal between them employs a contact-type static seal, where the gap between the shaft seal 8 and the rotor 13 is sealed by an O-ring 9.

[0041] Specifically, as shown in Figure 4, an oil-seal step is provided on the surface of the rotor 13, the shaft seal 8 is attached to the oil-seal step of the rotor 13, and an O-ring mounting groove is provided in the oil-seal step or the shaft seal 8, and the O-ring 9 is mounted in the O-ring mounting groove.

[0042] It should be understood that the oil seal step portion is adjacent to the fixed plate step portion and is located on the side closer to the lubricating oil chamber, and is used for attaching the oil seal structure, etc. Similarly, this embodiment does not specifically limit the installation position of the O-ring mounting groove, for example, the O-ring mounting groove may be provided on the oil seal step portion on the outer surface of the rotor 13, or on the side of the shaft seal facing the rotor, as long as a seal between the rotor and the shaft seal is achieved.

[0043] In some preferred embodiments, the O-ring mounting groove is provided on the side of the shaft seal 8 facing the rotor 13.

[0044] During installation, first the O-ring 9 and expansion ring 10 are fixed to the O-ring mounting groove and expansion ring mounting groove, respectively. Next, the rotor 13 is installed inside the stator 11 and sealed by the fixing plate 7 to form the process by-product cavity 12. Then the shaft seal 8 is attached to the rotor 13, the bearing fixing seat 6 is fastened to the fixing plate 7, the bearing 5 is installed and the rotor 13 is locked in place with the tightening nut 4, the oil slinger 3 is fixed to the rotor 13, and the fuel tank cap 1 is assembled to the fixing plate 7.

[0045] During operation, the rotor 13 rotates by the support action of the bearing 5, which moves the oil slinger 3, tightening nut 4, shaft seal 8, and O-ring 9. The fuel tank cap 1, bearing mounting seat 6, mounting plate 7, expansion ring 10, and stator 11 are all fixed in place so as not to move. Lubricating oil is injected into the lubricating oil chamber 2, and the lubricating oil is driven by the oil slinger 3 to be ejected onto the slope of the fuel tank cap 1 and guided to the bearing 5 and bearing mounting seat 6, lubricating the bearing 5 and shaft seal 8.

[0046] A non-contact seal is used for the seal between the second bearing mounting seat 6 and the shaft seal 8. This seal device does not come into contact with the shaft and has no friction points. Specifically, a labyrinth seal structure can be used, which includes structures such as oil grooves and labyrinths, and achieves the purpose of sealing by utilizing centrifugal force and small play.

[0047] The labyrinth seal of this disclosure is a seal structure with a combination of protrusions and recesses that has a small amount of play between the shaft seal 8 and the bearing fixing seat 6, and is particularly applicable to preventing oil leakage from high-speed shafts.

[0048] The radial and axial data for the labyrinth seal play of this disclosure are shown in Table 1 below.

[0049] Table 1 Radial and axial labyrinth seal play [Table 1]

[0050] The foregoing describes only preferred embodiments of the present disclosure, and those skilled in the art can make several further 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. An oil seal and airtight sealing device for use in dry vacuum pumps and rotating machinery, wherein the oil seal and airtight sealing device includes a fuel tank cap (1), an oil slinger (3), a tightening nut (4), a bearing (5), a bearing fixing seat (6), a fixing plate (7), a shaft seal (8), an O-ring (9), an expansion ring (10), a stator (11), and a rotor (13). The fuel tank cap (1), oil slinger (3), tightening nut (4), bearing (5), bearing fixing seat (6), and the side of the fixing plate (7) adjacent to the bearing fixing seat (6) constitute a lubricating oil chamber (2). The shaft seal (8), O-ring (9), expansion ring (10), stator (11), rotor (13), and the side of the fixed plate (7) adjacent to the shaft seal (8) constitute a process by-product cavity (12), where, An oil-sealing and airtight sealing device for use in dry vacuum pumps and rotating machinery, characterized in that the fixing plate (7) and the shaft seal (8) are sequentially fitted onto the rotor (13), the expansion ring (10) is positioned between the fixing plate (7) and the rotor (13), and the O-ring (9) is positioned between the shaft seal (8) and the rotor (13), thereby providing airtightness and oil sealing to the lubricating oil chamber (2) and the process by-product cavity (12), respectively.

2. A fixed plate step is provided on the surface of the rotor (13), and the fixed plate (7) is attached to the fixed plate step. An oil seal and airtight sealing device for a dry vacuum pump and rotating machinery according to claim 1, characterized in that an expansion ring mounting groove is provided in the stepped portion of the fixing plate or the fixing plate (7), and the expansion ring (10) is mounted in the expansion ring mounting groove.

3. A high-pressure intake hole (21) is provided in the fixing plate (7), and the space inside the high-pressure intake hole (21) is in communication with the surface of the rotor (13). The oil seal and airtight sealing device for a dry vacuum pump and rotating machinery according to claim 2, characterized in that the expansion ring (10) is in close contact with the downstream end face of the expansion ring mounting groove due to the pressure difference on both sides.

4. The oil seal and airtight sealing device for a dry vacuum pump and rotating machine according to claim 2, characterized in that there are multiple expansion rings (10), and the multiple expansion rings (10) are provided at intervals along the longitudinal direction of the rotor (13).

5. An oil-sealed stepped portion is provided on the surface of the rotor (13), and the shaft seal (8) is attached to the oil-sealed stepped portion. The oil seal and airtight sealing device for a dry vacuum pump and rotating machinery according to claim 1, characterized in that an O-ring mounting groove is provided in the oil seal step portion or the shaft seal (8), and the O-ring (9) is mounted in the O-ring mounting groove.

6. The bearing (5) is fitted onto the rotor (13) on the side away from the fixing plate (7), the bearing fixing seat (6) is fitted onto the outside of the bearing (5), and the bearing fixing seat (6) is fixed to the fixing plate (7). The oil seal and airtight sealing device for a dry vacuum pump and rotating machine according to claim 1, characterized in that the rotor (13) is located on one side surface of the lubricating oil chamber (2) and has a male thread near the mounting position of the bearing (5), and the tightening nut (4) is fitted onto the male thread and used to fix the bearing (5).

7. The oil-sealed and airtight sealing device for a dry vacuum pump and rotating machinery according to claim 5, characterized in that a non-contact seal is used between the bearing fixing seat (6) and the shaft seal (8).

8. The oil-sealed and airtight sealing device for a dry vacuum pump and rotating machinery according to claim 7, characterized in that the non-contact seal has a labyrinth seal structure and has a combination of small playful irregularities between the shaft seal (8) and the bearing fixing seat (6).

9. The fuel tank cap (1) is fixedly connected to the fixing plate (7), The oil slinger (3) is located inside the lubrication chamber (2) and fixed to the rotor (13), and a slope is provided on the inner surface of the fuel tank cap (1), and is used to guide the lubricating oil splashed from the oil slinger (3) to the bearing (5), as described in claim 1, and is an oil seal / airtight sealing device for use in a dry vacuum pump and rotating machine.

10. The oil seal and airtight sealing device for a dry vacuum pump and rotating machine according to claim 1, characterized in that the stator (11) has a hollow structure and the rotor (13) is mounted inside the stator (11).

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