Composite sealing roots vacuum pump device

Abstract

The utility model relates to a composite sealing roots vacuum pump device which comprises a pump body, a front end cover is arranged at the front end of the pump body, a rear end cover is arranged at the rear end of the pump body, a composite sealing structure is arranged between the front end cover and a main shaft, and the same composite sealing structure is arranged between the rear end cover and the main shaft. The composite sealing structure comprises a lip-shaped seal, a ceramic shaft sleeve, a mechanical seal, a lubricating oil inlet and a dry gas seal inlet, the ceramic shaft sleeve and a main shaft sleeve are arranged between the main shaft and the front end cover, the main shaft is sleeved with the ceramic shaft sleeve and the main shaft sleeve, the ceramic shaft sleeve is arranged close to the pump body, and the main shaft sleeve is arranged close to the bearing; a lip seal is arranged between the ceramic shaft sleeve and the front end cover, and a mechanical seal is arranged between the main shaft sleeve and the front end cover; the front end cover is provided with a lubricating oil inlet and a dry gas seal inlet. According to the utility model, the lip seal and the ceramic shaft sleeve are matched with each other, and mechanical seal and dry gas seal are combined, so that high-reliability composite seal is formed, and oil leakage of the roots vacuum pump is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of vacuum equipment, in particular to a composite sealed Roots vacuum pump device. Background Art

[0002] A Roots vacuum pump is a type of variable displacement vacuum pump equipped with two bladed rotors that rotate synchronously in opposite directions. There is a small gap between the rotors and between the rotors and the inner wall of the pump casing, so they do not touch each other. Roots vacuum pumps are widely used in various fields such as petroleum, chemical industry, plastics, pesticides, turbine rotor dynamic balancing, and aerospace simulation. The current dynamic seal of the Roots vacuum pump end cover usually adopts a labyrinth seal structure, see Figure 1 , Figure 1 This is a partial cross-section of a labyrinth seal in an existing Roots vacuum pump. The labyrinth seal structure consists of multiple piston rings nested within a piston ring seat, which is then assembled into a piston ring bushing and oil deflector plate, and then mounted on the main shaft. This seal forms a common dynamic seal in general-purpose mechanical equipment. Due to its simple structure and easy assembly and disassembly, it is widely used. However, due to the presence of clearances between the piston rings, piston ring seats, piston ring bushings, and oil deflector plate, this seal is relatively unreliable and exhibits a certain amount of leakage.

[0003] After a Roots vacuum pump is started, a high vacuum is quickly established within the pump body. A large pressure differential exists between the pump body and the oil tanks at both ends, allowing lubricant from the oil tanks to easily enter the pump body through the gaps in the labyrinth seals. If a Roots vacuum pump is used in processes involving the extraction of condensable or corrosive gases, the vacuum pump oil in the oil tanks will become contaminated by the gases being pumped after a period of operation. This can lead to emulsification, corrosion, and deterioration of the vacuum pump oil. This can be particularly true when pumping highly corrosive gases, causing transmission components such as the pump's gears and bearings to quickly fail or become damaged. Furthermore, the vacuum pump oil can contaminate the pumped medium. Therefore, Roots vacuum pumps using labyrinth seals are only suitable for processes involving the extraction of dry, clean, non-corrosive gases, placing them in a very limited position.

[0004] Based on the above problems, the applicant proposes a composite seal Roots vacuum pump device. Summary of the Invention

[0005] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide a composite sealing Roots vacuum pump device to solve the internal leakage problem of the Roots vacuum pump.

[0006] The purpose of this utility model is achieved in this way:

[0007] A composite sealed Roots vacuum pump device comprises a pump body, wherein the front end of the pump body is provided with a front cover, and the rear end is provided with a rear cover. A pair of U-shaped rotors are arranged horizontally and parallel to each other within the pump body, and the rotors are mounted on a main shaft and a rotor shaft, and the main shaft and rotor shaft are arranged within the pump body; the front end cover is provided with a front oil tank, and the rear end cover is provided with a gear box; the front end of the main shaft extends out of the front oil tank and is connected to a coupling, and the coupling is connected to a motor; a bearing is provided at the front end of the front cover, and a bearing is also provided at the rear end of the rear cover, and the bearing is sleeved on the main shaft;

[0008] A composite sealing structure is provided between the front end cover and the main shaft, and a similar composite sealing structure is provided between the rear end cover and the main shaft, and is symmetrically arranged with the composite sealing structure between the front end cover and the main shaft;

[0009] The composite sealing structure includes a lip seal, a ceramic sleeve, a mechanical seal, a lubricating oil inlet and a dry gas seal inlet. A ceramic sleeve and a main shaft sleeve are provided between the main shaft and the front end cover. The ceramic sleeve and the main shaft sleeve are both sleeved on the main shaft. The ceramic sleeve is arranged close to the pump body, and the main shaft sleeve is arranged close to the bearing. A lip seal is provided between the ceramic sleeve and the front end cover, and a mechanical seal is provided between the main shaft sleeve and the front end cover.

[0010] The front end cover is provided with a lubricating oil inlet and a dry gas seal inlet. The bottom end of the lubricating oil inlet reaches the mechanical seal, and the bottom end of the dry gas seal inlet reaches the gap between the lip seal and the end cover of the mechanical seal. The inert gas is transported to the interior of the end cover through the dry gas seal inlet.

[0011] Furthermore, the front end cover is fixedly connected to the front end of the pump body with hexagon socket screws, and the rear end cover is fixedly connected to the rear end of the pump body with hexagon socket screws; the front oil tank is fixedly connected to the front side of the front end cover with hexagon socket screws, and the gear box is fixedly connected to the rear side of the rear end cover with hexagon socket screws.

[0012] Furthermore, a gear is provided in the gear box, and the gear is sleeved on the end of the main shaft.

[0013] Furthermore, an O-ring is provided between the ceramic sleeve and the main shaft sleeve.

[0014] Furthermore, an O-ring is provided between the mechanical seal and the main shaft sleeve.

[0015] Furthermore, an air inlet is provided at the upper end of the pump body, and an air outlet is provided at the lower end.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] The utility model provides a composite-seal Roots vacuum pump device, which adopts the mutual cooperation of a lip seal and a ceramic sleeve, and adds a mechanical seal and a dry gas seal to form a high-reliability end cover composite seal. The lip seal isolates chemical materials in the pump body of the Roots vacuum pump from entering the end cover and blocks the materials from entering the oil tank. The mechanical seal prevents lubricating oil in the oil tank from entering the end cover and contaminating the pumped medium in the pump body. A certain micro-pressure of inert gas is supplemented between the lip seal and the mechanical seal to form a dry gas sealing structure, which further improves the reliability of the composite seal, can completely solve the internal leakage problem of the Roots vacuum pump, prevent oil leakage of the Roots vacuum pump, avoid the pumped medium from entering the lubricating oil tank, and greatly extend the service life of the Roots vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a partial cross-sectional view of the labyrinth seal of an existing Roots vacuum pump.

[0019] Figure 2 It is a structural diagram of the present utility model.

[0020] Figure 3 for Figure 2 A partial enlarged view of point A.

[0021] Figure 4 It is a side view of the present utility model.

[0022] in:

[0023] Pump body 1, air inlet 1.1, exhaust port 1.2, front cover 2, front oil tank 3, coupling 4, rear cover 5, gearbox 6, lip seal 7, ceramic sleeve 8, mechanical seal 9, gear 10, lubricating oil inlet 11, main shaft 12, main shaft sleeve 13, dry gas seal inlet 14, rotor 15, motor 16. DETAILED DESCRIPTION

[0024] To better understand the technical solution of the present invention, the following detailed description is provided with reference to the relevant illustrations. It should be understood that the following specific embodiments are not intended to limit the specific implementation of the technical solution of the present invention; they are merely examples of possible implementations of the technical solution of the present invention. It should be noted that the description herein of the positional relationships of the various components, such as component A being located above component B, is based on the relative positions of the components in the illustrations and is not intended to limit the actual positional relationships of the components. Example 1

[0025] See also Figure 2-Figure 4 , Figure 2A schematic structural diagram of the present invention is provided. As shown in the figure, a composite-seal Roots vacuum pump assembly comprises a pump body 1, with a front end cover 2 provided at the front end and a rear end cover 5 provided at the rear end. An air inlet 1.1 is provided at the upper end of the pump body 1, and an exhaust port 1.2 is provided at the lower end. A pair of 8-shaped rotors 15 are horizontally disposed in parallel within the pump body 1. The rotors 15 are mounted on a main shaft 12 and a rotor shaft, which are disposed within the pump body.

[0026] The front end cover 2 is fixedly connected to the front end of the pump body 1 with hexagon socket screws, and the rear end cover 5 is fixedly connected to the rear end of the pump body 1 with hexagon socket screws; the front end cover 2 is provided with a front oil tank 3, and the front oil tank 3 is fixedly connected to the front side of the front end cover 2 with hexagon socket screws, and the rear end cover 5 is provided with a gear box 6, and the gear box 6 is fixedly connected to the rear side of the rear end cover 5 with hexagon socket screws.

[0027] The front end (exit end) of the main shaft 12 extends out of the front oil tank 3 and is connected to the coupling 4 , and the coupling 4 is connected to the motor 16 ; a gear 10 is provided in the gear box 6 , and the gear 10 is sleeved on the end of the main shaft 12 .

[0028] A bearing is provided at the front end of the front cover 2 , and a bearing is also provided at the rear end of the rear cover 5 . The bearing sleeves are mounted on the main shaft 12 .

[0029] A composite sealing structure is provided between the front end cover 2 and the main shaft 12 , and a similar composite sealing structure is provided between the rear end cover 5 and the main shaft 12 , and is symmetrically arranged with the composite sealing structure between the front end cover 2 and the main shaft 12 .

[0030] The composite sealing structure includes a lip seal 7, a ceramic sleeve 8, a mechanical seal 9, a lubricating oil inlet 11 and a dry gas seal inlet 14. A ceramic sleeve 8 and a main shaft sleeve 13 are provided between the main shaft 12 and the front end cover 2. The ceramic sleeve 8 and the main shaft sleeve 13 are both sleeved on the main shaft 12. The ceramic sleeve 8 is arranged close to the pump body 1, and the main shaft sleeve 13 is arranged close to the bearing. An O-ring is provided between the ceramic sleeve 8 and the main shaft sleeve 13; a lip seal 7 is provided between the ceramic sleeve 8 and the front end cover 2, a mechanical seal 9 is provided between the main shaft sleeve 13 and the front end cover 2; an O-ring is also provided between the mechanical seal 9 and the main shaft sleeve 13;

[0031] A lubricating oil inlet 11 and a dry gas seal inlet 14 are provided on the front end cover 2. The bottom end of the lubricating oil inlet 11 reaches the mechanical seal 9, and the bottom end of the dry gas seal inlet 14 reaches the end cover gap between the lip seal 7 and the mechanical seal 9. The inert gas is transported to the inside of the end cover through the dry gas seal inlet 14 on the end cover of the Roots vacuum pump. An inert gas flowmeter is provided outside the vacuum pump to detect the effectiveness of the mechanical seal or lip seal by the flowmeter.

[0032] Working principle:

[0033] The Roots vacuum pump's pump body is located in the center of the pump, with an air inlet and exhaust port located at the top and bottom of the pump body. End caps and lubricating oil tanks are located on the front and rear sides of the pump body, respectively. Dynamic seals must be installed to separate the pump body from the lubricating oil tanks located on both sides of the pump body. Two figure-eight rotors are installed within the pump body. These two rotors rotate synchronously at high speed and in opposite directions to achieve vacuum pumping. During vacuuming, no other media is allowed to penetrate the pump body. Dynamic seals located within the end caps on both sides of the pump body are used to isolate the lubricating oil in the tank from the pumped gas, preventing mutual leakage between the lubricating oil in the tank and the pumped gas, thereby preventing failure and accidents caused by mutual interference.

[0034] The utility model discloses a composite seal Roots vacuum pump device, which is mainly composed of a pump body, a rotor, an end cover, a composite seal, an oil tank, a gear, a coupling and an electric motor. The composite seal includes a lip seal ring, a ceramic sleeve, a sleeve, an O-ring, a mechanical seal and a dry gas seal.

[0035] The lip seal, located near the pump body and primarily made of PTFE, is corrosion-resistant to various strong acids, bases, and solvents. Furthermore, it can operate in dry friction with the ceramic sleeve without the need for lubricant. The ceramic sleeve is highly hard and, after polishing, achieves an exceptionally smooth finish and a low coefficient of friction. This significantly reduces friction between the sleeve and the lip seal, minimizing heat generation and wear, and extending the service life of the lip seal.

[0036] Ceramic bushings utilize high-precision, high-hardness tungsten carbide ceramic bushings, further reducing the friction coefficient between the bushing and the lip seal, thereby reducing wear on the bushing and lip seal, and extending the service life of the bushing and lip seal. The surface finish of the ceramic bushing reaches Ra0.2-0.4 microns and the hardness reaches Mohs 8-9 (diamond 10), ensuring a normal service life of the lip seal and ceramic bushing of more than 20,000 hours.

[0037] The mechanical seal is installed on the outside of the lip seal, that is, on the side close to the vacuum pump oil tank. When the Roots vacuum pump is operating, the vacuum pump lubricating oil in the oil tank is thrown into the lubricating oil groove on the upper part of the pump end cover by the high-speed rotating gears and oil slinger. The lubricating oil then enters the mechanical seal through the lubricating oil inlet on the end cover to cool and lubricate the friction sealing surface of the mechanical seal. The lubricating oil then flows through the bearing to lubricate and cool the bearing, and finally flows back into the oil tank through the internal gap of the bearing.

[0038] The dry gas seal is installed in the gap between the mechanical seal and the lip seal in the end cover of the Roots vacuum pump to enhance the sealing reliability of the end cover. Dry gas sealing involves machining dry gas inlet holes in the corresponding sealing positions of the end cover to allow external dry gas to be introduced between the mechanical seal and the lip seal. This further enhances the reliability of the mechanical and lip seals. During operation, the pump chamber of a Roots vacuum pump is in a vacuum state, while the lubricating oil tank outside the pump body is at atmospheric pressure, resulting in a significant pressure differential between the two. The dry gas seal utilizes external dry gas, typically an inert gas such as nitrogen or argon. This inert gas is adjusted to a slightly positive pressure close to atmospheric pressure by a pressure regulating valve and then delivered to the interior of the end cover through the dry gas seal inlet on the Roots vacuum pump end cover. If the mechanical seal and lip seal inside the end cover are leak-free, there is virtually no inert gas loss. However, if the mechanical seal or lip seal leaks, some inert gas consumption will occur. An inert gas flowmeter installed outside the vacuum pump can be used to determine if the mechanical seal or lip seal inside the end cover is failing.

[0039] The above are only specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. Any technical solution formed by equivalent transformation or equivalent replacement shall fall within the scope of protection of the present invention.

Claims

1. A composite sealed Roots vacuum pump device, characterized in that: It comprises a pump body (1), wherein the front end of the pump body (1) is provided with a front cover (2), and the rear end is provided with a rear cover (5), a pair of 8-shaped rotors (15) are arranged in parallel in the horizontal direction inside the pump body (1), and the rotors (15) are arranged on the main shaft (12) and the rotor shaft, and the main shaft (12) and the rotor shaft are arranged in the pump body; the front end cover (2) is provided with a front oil tank (3), and the rear end cover (5) is provided with a gear box (6); the front end of the main shaft (12) extends out of the front oil tank (3) and is connected to a coupling (4), and the coupling (4) is connected to a motor (16); the front end of the front end cover (2) is provided with a bearing, and the rear end of the rear end cover (5) is also provided with a bearing, and the bearing sleeve is arranged on the main shaft (12); A composite sealing structure is provided between the front end cover (2) and the main shaft (12), and a similar composite sealing structure is provided between the rear end cover (5) and the main shaft (12), and is symmetrically arranged with the composite sealing structure between the front end cover (2) and the main shaft (12); The composite sealing structure comprises a lip seal (7), a ceramic sleeve (8), a mechanical seal (9), a lubricating oil inlet (11) and a dry gas seal inlet (14); a ceramic sleeve (8) and a main shaft sleeve (13) are provided between the main shaft (12) and the front end cover (2); the ceramic sleeve (8) and the main shaft sleeve (13) are both sleeved on the main shaft (12); the ceramic sleeve (8) is arranged close to the pump body (1), and the main shaft sleeve (13) is arranged close to the bearing; a lip seal (7) is provided between the ceramic sleeve (8) and the front end cover (2); and a mechanical seal (9) is provided between the main shaft sleeve (13) and the front end cover (2); The front end cover (2) is provided with a lubricating oil inlet (11) and a dry gas seal inlet (14). The bottom end of the lubricating oil inlet (11) reaches the mechanical seal (9), and the bottom end of the dry gas seal inlet (14) reaches the end cover gap between the lip seal (7) and the mechanical seal (9). Inert gas is transported to the interior of the end cover through the dry gas seal inlet (14).

2. A composite sealed Roots vacuum pump device according to claim 1, characterized in that: The front end cover (2) is fixedly connected to the front end of the pump body (1) by means of hexagon socket screws, and the rear end cover (5) is fixedly connected to the rear end of the pump body (1) by means of hexagon socket screws; the front oil tank (3) is fixedly connected to the front side of the front end cover (2) by means of hexagon socket screws, and the gear box (6) is fixedly connected to the rear side of the rear end cover (5) by means of hexagon socket screws.

3. The composite seal Roots vacuum pump device according to claim 1, characterized in that: A gear (10) is provided in the gear box (6), and the gear (10) is sleeved on the end of the main shaft (12).

4. The composite seal Roots vacuum pump device according to claim 1, characterized in that: An O-type sealing ring is provided between the ceramic shaft sleeve (8) and the main shaft sleeve (13).

5. The composite seal Roots vacuum pump device according to claim 1, characterized in that: An O-type sealing ring is provided between the mechanical seal (9) and the main shaft sleeve (13).

6. The composite seal Roots vacuum pump device according to claim 1, characterized in that: An air inlet (1.1) is provided at the upper end of the pump body (1), and an air outlet (1.2) is provided at the lower end.

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