Composite sealing screw dry vacuum pump

Abstract

The utility model relates to a composite sealing screw dry vacuum pump which comprises a pump body, a driving screw rotor and a driven screw rotor are arranged in the pump body side by side, the two screw rotors are respectively supported in a pump cavity through bearings in a front end cover and a rear end cover, and front end cover sealing assemblies are arranged at the front ends of the two screw rotors. A rear cover of the two screw rotors is provided with a rear end cover sealing assembly, the front end cover sealing assembly comprises a front ceramic shaft sleeve, an adjusting shaft sleeve, a first lip-shaped seal, an air inlet ring, a corrugated pipe mechanical seal and a lubricating oil inlet groove, and the rear end cover sealing assembly comprises a rear ceramic shaft sleeve, a framework oil seal, a second lip-shaped seal, a space ring and a third lip-shaped seal. The sealing device is simple in structure, good in reliability, long in service life, low in energy consumption and stable and reliable in sealing performance, the sealing effect is guaranteed, meanwhile, the good abrasion-resistant and corrosion-resistant effects are achieved, abrasion of transmission parts of the screw dry type vacuum pump is reduced, and it is guaranteed that the screw dry type vacuum pump can stably operate for a long time.

Description

Technical Field

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

[0002] A screw vacuum pump is a vacuum device that uses a pair of screws rotating synchronously at high speeds in opposite directions within the pump casing to create suction and exhaust. Due to the high speed of the screw vacuum pump during operation, the lubricating oil in the end cover generates oil mist. This mist enters the vacuum chamber through the gap between the rotor and the end cover. The screw vacuum pump shaft seal typically uses a single sealing ring to seal the gap, but this sealing structure results in poor sealing effectiveness during operation.

[0003] Existing dry screw vacuum pumps utilize a skeleton oil seal structure for their end cap seals. This simple structure, coupled with rubber components susceptible to aging and wear at high temperatures and chemical corrosion resistance, hinders reliable operation in specialized industries such as the chemical and pharmaceutical industries. After a period of operation, a certain amount of pumped chemical material leaks through the seals into the pump's lubricating oil tank. This material rapidly degrades the pump oil, causing gears, bearings, and other transmission components to corrode and fail quickly if the lubricant is not replaced promptly, shortening the pump's lifespan. To ensure the pump's proper operation, users must frequently replace the pump's lubricating oil, disrupting normal production and reducing efficiency.

[0004] Based on the above problems, the applicant proposes a composite sealed screw dry vacuum pump. Summary of the Invention

[0005] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide a composite sealed screw dry vacuum pump, which ensures that the screw dry vacuum pump has a good sealing effect while ensuring that the screw dry vacuum pump seal has a better corrosion resistance, reduces the wear and corrosion of the transmission parts inside the screw dry vacuum pump, and ensures that the screw dry vacuum pump can operate reliably for a long time when pumping special gases.

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

[0007] A composite sealed screw dry vacuum pump, comprising a pump body, wherein the front end of the pump body is provided with a front cover, the rear end is provided with a rear cover, the front end cover is provided with a front cover, a synchronous helical gear, a front cover sealing assembly and a front bearing are provided in the front cover, a rear bearing seat is provided on the rear cover, a rear bearing pressure cover is provided on the rear bearing seat, and a rear bearing and a rear cover sealing assembly are provided in the rear bearing pressure cover;

[0008] A pair of active screw and driven screw arranged horizontally and in parallel are provided in the pump body, and the active screw and the driven screw are respectively provided with a screw main shaft; a front bearing is sleeved on the front end of the screw main shaft, and the front bearing is arranged on the front end cover through the front bearing seat, and a front end cover sealing assembly is provided at the contact portion between the screw main shaft, the front end cover and the front bearing seat; a rear bearing is sleeved on the rear end of the screw main shaft, and the rear bearing is arranged on the rear end cover through the rear bearing seat, and a rear bearing pressure cover is provided on the rear bearing seat, and a rear end cover sealing assembly is provided at the contact portion between the screw main shaft, the rear end cover and the rear bearing seat;

[0009] The front end cover sealing assembly includes a front ceramic sleeve, an adjustment sleeve, a first lip seal, an intake ring, a bellows mechanical seal and a lubricating oil inlet groove. The front end of the screw main shaft is sequentially sleeved with a front bearing, an adjustment sleeve and a front ceramic sleeve. The front ceramic sleeve is arranged between the screw main shaft and the front end cover, and the adjustment sleeve is arranged between the screw main shaft and the front bearing seat.

[0010] The bellows mechanical seal includes a stationary ring, a stationary ring seat, a dynamic ring, a dynamic ring seat, a bellows and a base. The bellows is sleeved on the adjustment sleeve. The front side of the bellows is provided with a base. The rear side of the bellows is provided with a dynamic ring seat. The dynamic ring is provided on the dynamic ring seat. The rear side of the dynamic ring is provided with a stationary ring. The stationary ring is provided on the stationary ring seat.

[0011] The rear end cover sealing assembly includes a rear ceramic sleeve, a skeleton oil seal, a second lip seal, a spacer and a third lip seal; the rear end of the screw main shaft is sequentially sleeved with a second lip seal, a spacer, a rear ceramic sleeve and a rear bearing from front to rear, the rear ceramic sleeve is arranged between the rear bearing seat and the screw main shaft, a second lip seal is arranged at the contact point between the rear end cover and the screw main shaft, a third lip seal and a skeleton oil seal are provided between the rear ceramic sleeve and the rear bearing seat, and the skeleton oil seal is arranged between the third lip seal and the rear bearing.

[0012] Furthermore, an air intake port is provided on the upper portion of one side of the pump body, and an air exhaust port is provided on the side surface of the front end cover.

[0013] Furthermore, the active screw and the driven screw are connected and driven by synchronous helical gears.

[0014] Furthermore, the main shaft of the active screw extends out of the front cover and is connected to the motor through a coupling.

[0015] Furthermore, a front inert gas interface is provided on the front end cover, an air intake ring is provided on the front ceramic sleeve, and the air intake ring is connected to the front inert gas interface through the front air intake hole; a bellows mechanical seal is provided between the air intake ring and the front bearing; and a first lip seal is provided in the gap between the air intake ring and the pump body.

[0016] Furthermore, a rear inert gas interface is provided on the rear end cover, a buffer compartment exists between the rear end cover and the screw main shaft, and the rear inert gas interface is connected to the buffer compartment through a rear air inlet hole.

[0017] Furthermore, a lubricating oil inlet groove is provided between the front bearing seat and the front end cover, and the lubricating oil inlet groove leads to the bellows mechanical seal.

[0018] Furthermore, a first sealing ring is provided between the base and the adjusting sleeve.

[0019] Furthermore, the stationary ring seat is fixed to the intake ring via an anti-rotation pin.

[0020] Furthermore, a second sealing ring is provided between the stationary ring seat and the intake ring.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] The utility model provides a composite-seal screw dry vacuum pump. Based on the working characteristics of the screw dry vacuum pump, the suction end adopts a combined sealing method of a skeleton oil seal, a lip seal, and an inert gas barrier; the exhaust end adopts a combined sealing method of a bellows mechanical seal, a lip seal, and an inert gas barrier to replace the single sealing structure of the traditional screw dry vacuum pump. This completely solves the problems of aging and frequent oil leakage of the screw dry vacuum pump seal. While ensuring the sealing effect, it has better wear resistance, corrosion resistance, high temperature resistance, high pressure resistance, and negative pressure resistance. It reduces the wear and failure of the screw dry vacuum pump transmission parts and ensures the long-term stable operation of the screw dry vacuum pump. The utility model has a simple, compact, and reasonable structure and stable and reliable operation. It can ensure the sealing effect while having good wear resistance and corrosion resistance, reduce the wear and corrosion of the screw dry vacuum pump transmission parts, and ensure the long-term operation of the screw dry vacuum pump. It solves the problems of short-term failure and oil leakage of the seals of the existing single-seal screw dry vacuum pump, and extends the normal service life of the screw dry vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a cross-sectional top view of the present invention.

[0024] Figure 2 It is a sectional front view of the present utility model.

[0025] Figure 3 It is a partial schematic diagram of the front end cover sealing assembly of the present invention.

[0026] Figure 4 It is a partial schematic diagram of the bellows mechanical seal of the present invention.

[0027] Figure 5It is partial view of rear end cover sealing assembly of the utility model.

[0028] Wherein:

[0029] Pump body 1, air inlet 1.1, exhaust port 1.2, front cover 2, front end cover 3, front inert gas interface 3.1, synchronous helical gear 4, front end cover sealing assembly 5, front ceramic shaft sleeve 5.1, adjusting shaft sleeve 5.2, first lip seal 5.3, air inlet ring 5.4, front air inlet hole 5.5, bellows mechanical seal 5.6, static ring 5.61, static ring seat 5.62, dynamic ring 5.63, dynamic ring seat 5.64, bellows 5.65, first sealing ring 5.66, second sealing ring 5.67, anti-rotation pin 5.68, base 5.69, fastening screw 5.610, lubricating oil inlet groove 5.7, front bearing 6, rear end cover 7, rear inert gas interface 7.1, rear bearing 8, rear bearing gland 9, rear end cover sealing assembly 10, rear ceramic shaft sleeve 10.1, skeleton oil seal 10.2, second lip seal 10.3, spacer ring 10.4, buffer separation cavity 10.5, third lip seal 10.6, rear air inlet hole 10.7, driving screw 11, driven screw 12, screw spindle 13, shaft coupling 14, motor 15. DETAILED DESCRIPTION

[0030] In order to better understand the technical scheme of the utility model, the following will be combined with relevant drawings to make detailed description. It should be understood that the following specific examples are not used to limit the specific implementation of the technical scheme of the utility model, and they are only implementation of the technical scheme of the utility model. It should be pointed out that the description of the position relationship of each component in this paper, such as A component is located above B component, is based on the relative position of each component in the drawing, and is not used to limit the actual position relationship of each component. Example 1

[0031] Referring to Figure 1-Figure 5 , Figure 1 The sectional view of the utility model is drawn. As shown in the figure, the composite sealing screw rod dry vacuum pump involved in the embodiment 1 comprises a pump body 1, the front end of the pump body 1 is provided with a front end cover 3, the rear end is provided with a rear end cover 7, the front end cover 3 is provided with a front cover 2, the front cover 2 is provided with a synchronous helical gear 4, a front end cover sealing assembly 5 and a front bearing 6, the rear end cover 7 is provided with a rear bearing seat, the rear bearing seat is provided with a rear bearing gland 9, and the rear bearing gland 9 is provided with a rear bearing 8 and a rear end cover sealing assembly 10.

[0032] The upper part of one side of the pump body 1 is provided with an air inlet 1.1, and the side surface of the front end cover 3 is provided with an exhaust port 1.2.

[0033] A pair of horizontally arranged active screws 11 and driven screws 12 are provided in the pump body 1. The active screw 11 and the driven screw 12 are respectively provided with screw main shafts 13. The active screw 11 and the driven screw 12 are connected for transmission via a synchronous helical gear 4; the screw main shaft 13 of the active screw 11 extends out of the front cover 2 and is connected to the motor 15 via a coupling 14; the front ends of the screw main shafts 13 of the active screw 11 and the driven screw 12 are respectively provided with front cover sealing assemblies 5, and the rear ends are respectively provided with rear cover sealing assemblies 10.

[0034] The front end of the screw main shaft 13 is sleeved with a front bearing 6, and the front bearing 6 is arranged on the front end cover 3 through the front bearing seat, and the front end cover sealing assembly 5 is provided at the contact portion between the screw main shaft 13, the front end cover 3 and the front bearing seat; the rear end of the screw main shaft 13 is sleeved with a rear bearing 8, and the rear bearing 8 is arranged on the rear end cover 7 through the rear bearing seat, and the rear bearing pressure cover 9 is provided on the rear bearing seat, and the rear end cover sealing assembly 10 is provided at the contact portion between the screw main shaft 13, the rear end cover 7 and the rear bearing seat.

[0035] The front end cover 3 is provided with a front inert gas interface 3.1, and the rear end cover 7 is provided with a rear inert gas interface 7.1.

[0036] The front end cover sealing assembly 5 includes a front ceramic sleeve 5.1, an adjusting sleeve 5.2, a first lip seal 5.3, an intake ring 5.4, a bellows mechanical seal 5.6 and a lubricating oil inlet groove 5.7. The front end of the screw main shaft 13 is sequentially sleeved with a front bearing 6, an adjusting sleeve 5.2 and a front ceramic sleeve 5.1, the front ceramic sleeve 5.1 being arranged between the screw main shaft 13 and the front end cover 3, and the adjusting sleeve 5.2 being arranged between the screw main shaft 13 and the front bearing seat; an intake ring 5.4 is sleeved on the front ceramic sleeve 5.1, and the intake ring 5.4 is connected to the front inert gas interface 3.1 through the front intake hole 5.5; a first lip seal 5.3 is arranged in the gap between the intake ring 5.4 and the pump body 1, and a bellows mechanical seal 5.6 is arranged between the intake ring 5.4 and the front bearing 6;

[0037] A lubricating oil inlet groove 5.7 is provided between the front bearing seat and the front end cover 3, and the lubricating oil inlet groove 5.7 leads to a bellows mechanical seal 5.6;

[0038] The bellows mechanical seal 5.6 includes a stationary ring 5.61, a stationary ring seat 5.62, a dynamic ring 5.63, a dynamic ring seat 5.64, a bellows 5.65 and a base 5.69. The bellows 5.65 is sleeved on the adjustment sleeve 5.2. The base 5.69 is set on the front side of the bellows 5.65. The base 5.69 is fixed to the adjustment sleeve 5.2 by fastening screws 5.610. There is a screw between the base 5.69 and the adjustment sleeve 5.2. There is a first sealing ring 5.66. A dynamic ring seat 5.64 is provided on the rear side of the bellows 5.65. A dynamic ring 5.63 is provided on the dynamic ring seat 5.64. A static ring 5.61 is provided on the rear side of the dynamic ring 5.63. The static ring 5.61 is provided on the static ring seat 5.62. The static ring seat 5.62 is fixed to the intake ring 5.4 by an anti-rotation pin 5.68; a second sealing ring 5.67 is provided between the static ring seat 5.62 and the intake ring 5.4.

[0039] The rear end cover sealing assembly 10 includes a rear ceramic sleeve 10.1, a skeleton oil seal 10.2, a second lip seal 10.3, a spacer 10.4 and a third lip seal 10.6. A buffer compartment 10.5 is provided between the rear end cover 7 and the screw main shaft 13, and the rear inert gas interface 7.1 is connected to the buffer compartment 10.5 through the rear air inlet hole 10.7; the rear end of the screw main shaft 13 is sequentially sleeved with a second lip seal 10.3, a spacer 10.4, a rear ceramic sleeve 10.1 and a rear bearing 8 from front to back, the rear ceramic sleeve 10.1 is arranged between the rear bearing seat and the screw main shaft 13, and a second lip seal 10.3 is provided at the contact point between the rear end cover 7 and the screw main shaft 13, a third lip seal 10.6 and a skeleton oil seal 10.2 are provided between the rear ceramic sleeve 10.1 and the rear bearing seat, and the skeleton oil seal 10.2 is provided between the third lip seal 10.6 and the rear bearing 8.

[0040] Working principle:

[0041] The air intake of the screw dry vacuum pump is located on the upper part of the pump body near the side of the rear end cover. This area is in a vacuum state when the screw dry vacuum pump is evacuating air. The exhaust port of the screw dry vacuum pump is located on the side of the front end cover. The exhaust port is connected to the exhaust end of the inner cavity of the pump body through the air duct in the front end cover. That is, the exhaust end of the screw dry vacuum pump is located on the side of the pump body near the side of the front end cover. The pressure in this area is usually higher than atmospheric pressure. Therefore, the sealing structure in the front end cover of the screw dry vacuum pump and the sealing structure and sealing method in the rear end cover are completely different. A more reliable front and rear end cover sealing structure must be designed according to the characteristics of the screw dry vacuum pump. Therefore, the utility model provides a composite seal screw dry vacuum pump. According to the particularity of the internal structure of the screw dry vacuum pump, a combined sealing structure is designed that combines a mechanical seal with a lip seal and assists with an inert gas barrier seal. It is a screw dry vacuum pump with a high-reliability sealing structure.

[0042] The sealing difficulty of the screw dry vacuum pump lies on the side of the front cover. The exhaust port of the screw dry vacuum pump is set on the side of the front cover, which is the highest temperature rise point and the highest pressure point of the screw dry vacuum pump. The exhaust pressure of the screw dry vacuum pump is usually higher than the atmospheric pressure, so the compression ratio at the exhaust port is the largest, and the discharged chemical materials are most likely to accumulate at the front cover. This requires the front cover seal to meet the characteristics of high temperature resistance, corrosion resistance, and high pressure resistance, while traditional skeleton oil seals cannot adapt to this working condition.

[0043] The screw dry vacuum pump of the utility model is provided with a combined sealing structure, which includes an adjusting sleeve and a ceramic sleeve arranged in sequence at the end of the screw rotor shaft, a bellows mechanical seal and a lip seal arranged on the outer rings of the adjusting sleeve and the ceramic sleeve, and cooperates with the inert gas input on the front and rear end covers to form a composite sealing structure.

[0044] The utility model is sealed at the shaft end of the active screw and the inner hole of the front cover by a skeleton oil seal; the active screw and the driven screw rotors are supported in the pump chamber by bearings in the front and rear end covers respectively, the front ends of the two screw rotors are provided with a front cover composite sealing assembly, and the rear covers of the two screw rotors are provided with a rear end composite sealing structure. The two screw rotors transmit torque and ensure the meshing of the two screw rotors in the pump chamber through synchronous helical gears provided at the shaft end of one side of the front cover, and are driven by synchronous helical gears provided at the shaft ends of the two screw rotors in the front cover.

[0045] After special treatment, the surface finish of the ceramic sleeve reaches Ra0.2~0.4 microns and the hardness reaches Mohs 8~9 (diamond 10), which can greatly reduce the friction and heat between the lip seal and the ceramic sleeve, thereby greatly extending the normal service life of the lip seal and the ceramic sleeve; in addition, applying a slight positive pressure of nitrogen to the cavity between the mechanical seal and the lip seal through the nitrogen inlet hole in the front cover can effectively isolate the mutual penetration of the pumped medium and the vacuum pump lubricating oil, thereby extending the normal service life of the vacuum pump.

[0046] The rear end cover is usually in a vacuum state, and the temperature in the rear end cover area is relatively low, so chemical materials will hardly condense there, so the sealing structure of the rear end cover of the screw dry vacuum pump is relatively simple; the rear end cover sealing assembly includes two lip seals and a skeleton oil seal and a ceramic sleeve arranged in sequence, and then combined with a nitrogen seal; because the side of the rear end cover close to the pump head is in a vacuum state, the pumped material will not accumulate in the vacuum state, so the sealing requirements of the rear end cover are relatively simple, and the above sealing structure can fully meet various working conditions.

[0047] A bellows mechanical seal consists of an intake ring, a stationary ring, a stationary ring seat, a dynamic ring, a dynamic ring seat, a bellows, a sealing ring, a base, and fastening screws. The dynamic and static rings are the core components of a bellows mechanical seal, forming a high-precision friction pair to prevent media leakage. The dynamic ring can flexibly move on the sleeve and automatically compensate for the wear of the sealing surface, ensuring a good fit and seal with the static ring. The bellows acts as a compensating element, providing preload, compensation, and cushioning. It requires good elasticity and corrosion resistance to overcome friction between the auxiliary seal and transmission components and ensure a good fit of the end face sealing pair. The sealing rings include the dynamic ring sealing ring and the static ring sealing ring. They provide sealing for the static and dynamic rings, while also providing floating and cushioning functions.

[0048] Advantages of bellows mechanical seals:

[0049] Wear resistance: The main material of the bellows mechanical seal is made of high-hardness materials such as cemented carbide and silicon carbide to make mirror-surface friction pairs, which have excellent wear resistance and can meet the sealing requirements of various special working conditions such as high speed, high temperature, and high pressure;

[0050] Long service life: The bellows mechanical seal adopts a corrugated structure, which can effectively resist the erosion and wear of the medium and has a long service life. In addition, different materials of bellows can be selected according to different media and operating temperatures to further extend the service life of the mechanical seal.

[0051] Good sealing performance: The bellows mechanical seal adopts a corrugated structure to form multiple sealing layers, and there is a certain amount of loose air layer between the sealing layers, thus ensuring good sealing performance and preventing medium leakage;

[0052] Wide range of applications: Bellows mechanical seals are suitable for various working conditions, including sealing of low temperature, high temperature, high vacuum, high pressure, corrosive, abrasive, flammable, explosive, and toxic media;

[0053] Long maintenance cycle: Under normal working conditions, bellows mechanical seals do not require frequent maintenance and have a long maintenance cycle;

[0054] Less frictional power loss: The frictional power loss of bellows mechanical seals is less, usually only 10-50% of that of stuffing box seals;

[0055] Good shock resistance: Bellows mechanical seals do not require high precision and finish of the shaft, are insensitive to the vibration of the rotating shaft and the deflection of the shaft relative to the mechanical seal mounting hole, and have low sensitivity to shaft vibration;

[0056] Balanced seal: The bellows seal itself is a balanced seal, which reduces leakage points and has good tracking and shock resistance;

[0057] High temperature and high pressure resistance: Welded metal bellows seals are suitable for high temperature, high speed and other working conditions, and have the ability to withstand high pressure and vacuum.

[0058] 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 screw dry vacuum pump, characterized in that: It comprises a pump body (1), wherein the front end of the pump body (1) is provided with a front cover (3), the rear end is provided with a rear cover (7), the front cover (3) is provided with a front cover (2), the front cover (2) is provided with a synchronous helical gear (4), a front cover sealing assembly (5) and a front bearing (6), the rear end cover (7) is provided with a rear bearing seat, the rear bearing seat is provided with a rear bearing pressure cover (9), and the rear bearing pressure cover (9) is provided with a rear bearing (8) and a rear end cover sealing assembly (10); A pair of active screws (11) and driven screws (12) arranged horizontally and in parallel are provided in the pump body (1), and the active screws (11) and the driven screws (12) are respectively provided with screw main shafts (13); a front bearing (6) is sleeved on the front end of the screw main shaft (13), and the front bearing (6) is arranged on the front end cover (3) through the front bearing seat, and a front end cover sealing assembly (5) is provided at the contact portion between the screw main shaft (13), the front end cover (3) and the front bearing seat; a rear end bearing (8) is sleeved on the rear end cover (7) through the rear bearing seat, and a rear bearing pressure cover (9) is provided on the rear bearing seat, and a rear end cover sealing assembly (10) is provided at the contact portion between the screw main shaft (13), the rear end cover (7) and the rear bearing seat; The front end cover sealing assembly (5) comprises a front ceramic sleeve (5.1), an adjusting sleeve (5.2), a first lip seal (5.3), an intake ring (5.4), a bellows mechanical seal (5.6) and a lubricating oil inlet groove (5.7); the front end of the screw main shaft (13) is sequentially sleeved with a front bearing (6), an adjusting sleeve (5.2) and a front ceramic sleeve (5.1); the front ceramic sleeve (5.1) is arranged between the screw main shaft (13) and the front end cover (3); and the adjusting sleeve (5.2) is arranged between the screw main shaft (13) and the front bearing seat; The bellows mechanical seal (5.6) comprises a stationary ring (5.61), a stationary ring seat (5.62), a dynamic ring (5.63), a dynamic ring seat (5.64), a bellows (5.65) and a base (5.69); the bellows (5.65) is sleeved on the adjustment sleeve (5.2); the base (5.69) is provided on the front side of the bellows (5.65); the dynamic ring seat (5.64) is provided on the rear side of the bellows (5.65); the dynamic ring (5.63) is provided on the dynamic ring seat (5.64); the stationary ring (5.61) is provided on the rear side of the dynamic ring (5.63); and the stationary ring (5.61) is provided on the stationary ring seat (5.62); The rear end cover sealing assembly (10) comprises a rear ceramic sleeve (10.1), a skeleton oil seal (10.2), a second lip seal (10.3), a spacer (10.4) and a third lip seal (10.6); the rear end of the screw main shaft (13) is provided with the second lip seal (10.3), the spacer (10.4), the rear ceramic sleeve (10.1) and the rear bearing (8) in sequence from front to back, the rear ceramic sleeve (10.1) is arranged between the rear bearing seat and the screw main shaft (13), the second lip seal (10.3) is provided at the contact point between the rear end cover (7) and the screw main shaft (13), the third lip seal (10.6) and the skeleton oil seal (10.2) are provided between the rear ceramic sleeve (10.1) and the rear bearing seat, and the skeleton oil seal (10.2) is provided between the third lip seal (10.6) and the rear bearing (8).

2. A composite sealed screw dry vacuum pump according to claim 1, characterized in that: An air intake port (1.1) is provided on the upper portion of one side of the pump body (1), and an air exhaust port (1.2) is provided on the side of the front end cover (3).

3. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: The active screw (11) and the driven screw (12) are connected for transmission via a synchronous helical gear (4).

4. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: The screw main shaft (13) of the active screw (11) extends out of the front cover (2) and is connected to the motor (15) through a coupling (14).

5. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: A front inert gas interface (3.1) is provided on the front end cover (3); an air intake ring (5.4) is sleeved on the front ceramic sleeve (5.1); the air intake ring (5.4) is connected to the front inert gas interface (3.1) through a front air intake hole (5.5); a bellows mechanical seal (5.6) is provided between the air intake ring (5.4) and the front bearing (6); and a first lip seal (5.3) is provided in the gap between the air intake ring (5.4) and the pump body (1).

6. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: A rear inert gas interface (7.1) is provided on the rear end cover (7), a buffer compartment (10.5) is present between the rear end cover (7) and the screw main shaft (13), and the rear inert gas interface (7.1) is connected to the buffer compartment (10.5) via a rear air inlet hole (10.7).

7. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: A lubricating oil inlet groove (5.7) is provided between the front bearing seat and the front end cover (3), and the lubricating oil inlet groove (5.7) leads to the bellows mechanical seal (5.6).

8. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: A first sealing ring (5.66) is provided between the base (5.69) and the adjusting shaft sleeve (5.2).

9. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: The stationary ring seat (5.62) is fixed on the intake ring (5.4) via an anti-rotation pin (5.68).

10. The composite sealed screw dry vacuum pump according to claim 1, characterized in that: A second sealing ring (5.67) is provided between the stationary ring seat (5.62) and the intake ring (5.4).

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