CN220435025U - Dry-type screw vacuum pump seal structure - Google Patents

Abstract

A dry screw vacuum pump seal structure comprising: an end cap having a seal chamber and a bearing chamber; a rotor having a rotation shaft; the shaft seal seat is arranged in the sealing cavity, an inner cavity of the shaft seal seat is arranged in the shaft seal seat, and a shaft seal seat joint sleeve is arranged at the end part of the shaft seal seat; the shaft sleeve assembly comprises a first shaft sleeve and a second shaft sleeve which are sleeved on the rotating shaft, the first shaft sleeve is attached to the inner cavity of the shaft seal seat, the second shaft sleeve is arranged between the rotating shaft and the shaft seal seat joint sleeve, and a shaft seal piece is arranged between the second shaft sleeve and the inner cavity of the shaft seal seat; the bearing is sleeved on the rotating shaft; the oil retainer is arranged between the second shaft sleeve and the bearing and is also matched with the shaft seal seat joint sleeve of the shaft seal seat; a conducting air passage is arranged between the end cover and the shaft seal seat, an air vent gap is formed between the outer peripheral surface of the first shaft sleeve and the inner cavity of the shaft seal seat, and a sealing ring is arranged between the first shaft sleeve and the inner cavity of the shaft seal seat and corresponds to the air vent gap. The advantages are that: sealing performance is improved, and reliability is high; avoiding oil leakage of the mechanism; the durability of the vacuum pump is improved; the service life is prolonged.

Description

Dry-type screw vacuum pump seal structure

Technical Field

The utility model belongs to the technical field of vacuum pumps, and particularly relates to a dry screw vacuum pump sealing structure.

Background

The vacuum pump is a device or equipment for obtaining vacuum by pumping air from a pumped container by using a mechanical, physical, chemical or physicochemical method, and is used for pumping gas molecules from a vacuum chamber and reducing the gas pressure in the vacuum chamber to reach the required vacuum degree. The types of vacuum pumps are of the closed water type, the oil-based rotary type, the roots type, the oil diffusion type, the physical absorption type, the chemical absorption type, and the like, and the vacuum pumps can be generally classified into wet type and dry type. The dry screw vacuum pump is an air extracting device which uses a pair of screws to perform air suction and air exhaust effects generated by synchronous high-speed reverse rotation in a pump shell, and the volume of an element is always in the circulation state of air suction, compression, conveying and air exhaust through the continuous rotation of an impeller on the screws, so that the air and dust in a cavity are continuously discharged out of the pump to meet the process requirements; for technical information about such a dry screw vacuum pump, see "a nitrogen-sealed dry screw vacuum pump" described in CN206360892U, and "a novel two-in-one screw vacuum pump" described in CN 204827922U. The dry screw vacuum pump has the advantages of no oil in the pump cavity, no contact or abrasion during operation, high vacuum degree, energy conservation, environmental protection, emission reduction, no maintenance and the like, and is particularly widely applied to special environments containing high water vapor content, dust, corrosive gas and the like.

However, the application of the special environment puts high requirements on the sealing performance of the dry screw vacuum pump, and the sealing structure of the existing dry screw vacuum pump mainly has the following technical defects: when the dry screw vacuum pump pumps out gas with high water content and corrosive gas, the gas easily flows into a bearing chamber at the end part of a screw rotor under the action of exhaust pressure, so that lubricating oil in a bearing is emulsified, the bearing is damaged and the like, and the working stability of the vacuum pump is affected; in addition, when the dry screw vacuum pump is used for pumping out the gas containing dust particles, the dust particles in the gas easily enter the sealing component, so that the abrasion and cracking of the sealing component are caused, the sealing structure is made to fail in advance, and poor sealing is caused, so that the maintenance cost of the vacuum pump is increased, and the service life of the vacuum pump is reduced.

At present, the sealing problem of the existing dry screw vacuum pump is not solved well, and the problems of poor sealing performance and poor durability exist. Based on the deficiencies of the prior art, the applicant has devised an advantageous design, and the technical solutions described below are created in this context.

Disclosure of Invention

The utility model aims to provide a dry screw vacuum pump sealing structure which has the advantages of good sealing performance, high reliability, simple structure and convenient use, and can effectively solve the problems of low service life, easy abrasion and failure and poor reliability in the prior art.

The task of the utility model is accomplished in that a dry screw vacuum pump sealing structure comprises: the end cover is internally provided with a sealing cavity and a bearing cavity; a rotor having a rotation shaft passing through the sealing chamber and the bearing chamber; the shaft seal seat is matched and installed in the sealing cavity, a shaft seal seat inner cavity which is communicated with the shaft direction of the shaft seal seat is formed in the shaft seal seat, and a shaft seal seat joint sleeve which is in an annular shape is formed at the end part position of the shaft seal seat towards the bearing cavity; the shaft sleeve assembly comprises a first shaft sleeve I and a second shaft sleeve II, the first shaft sleeve I and the second shaft sleeve II are fixedly sleeved on the shaft body of the rotating shaft, the first shaft sleeve I is attached to the cavity wall of the inner cavity of the shaft seal seat, one part of the second shaft sleeve II is penetrated into the inner cavity of the shaft seal seat, the second shaft sleeve II is arranged between the rotating shaft and the shaft seal seat joint sleeve, and a plurality of shaft seal pieces are further arranged between the second shaft sleeve II and the cavity wall of the inner cavity of the shaft seal seat; the bearing is arranged in the bearing cavity, and is sleeved on the rotating shaft and is in rotating fit with the rotating shaft; the oil retainer is arranged between the second shaft sleeve II and the bearing and is bonded with the second shaft sleeve II and the bearing, and the oil retainer is also matched with the shaft seal seat joint sleeve of the shaft seal seat; a conducting air passage penetrating through the inner cavity of the shaft seal seat is further formed between the end cover and the shaft seal seat, a ventilation gap is formed between the outer peripheral surface of the first shaft sleeve I and the cavity wall of the inner cavity of the shaft seal seat, and a plurality of sealing rings are further arranged between the first shaft sleeve I and the cavity wall of the inner cavity of the shaft seal seat and correspond to the ventilation gap.

In a specific embodiment of the present utility model, a gas passage penetrating the sealing chamber inside the end cover is formed in the end cover, and a shaft seal seat ventilation groove is formed in the outer peripheral surface of the shaft seal seat, and one end of the shaft seal seat ventilation groove is arranged corresponding to the gas passage; the end face, close to the second shaft sleeve II, of the first shaft sleeve I in the axial direction is a first shaft sleeve joint face, and the end face, far away from the second shaft sleeve II, of the first shaft sleeve I in the axial direction is a first shaft sleeve external face; the seal seat is internally provided with a seal seat vent hole communicated with the seal seat inner cavity, one end of the seal seat vent hole, far away from the seal seat inner cavity, is communicated with a seal seat vent groove, and the seal seat vent hole can be communicated with the vent gap; and the shaft seal seat vent hole is positioned and arranged at a position corresponding to the joint of the first shaft sleeve joint surface, namely the joint of the first shaft sleeve I and the second shaft sleeve II.

In another specific embodiment of the utility model, a first shaft sleeve spiral groove is formed in the outer peripheral surface of the first shaft sleeve I and close to the outer joint surface of the first shaft sleeve, and a plurality of sealing rings are sleeved on the middle part of the first shaft sleeve I body and positioned at the middle part of the first shaft sleeve spiral groove and the shaft seal seat vent hole.

In a further specific embodiment of the utility model, a plurality of seal seat sealing rings are arranged between the inner wall of the seal chamber of the end cover and the outer peripheral surface of the seal seat, the seal seat sealing rings are sleeved on the inner peripheral wall of the seal chamber, and the seal seat sealing rings are arranged at positions corresponding to the positions between the seal seat ventilation grooves and the bearing chamber.

In still another specific embodiment of the present utility model, two shaft sealing rings are further disposed at two end portions of the inner cavity of the second shaft sleeve ii, and the two shaft sealing rings are both sleeved on the shaft body of the shaft, one of the two shaft sealing rings is disposed between the first shaft sleeve i and the second shaft sleeve ii in a fitting manner, and the other is disposed between the second shaft sleeve ii and the oil retainer in a fitting manner.

In a further specific embodiment of the utility model, a shaft seal seat positioning groove is formed at one end part of the sealing chamber far away from the bearing chamber, and a shaft seal seat positioning part matched with the shaft seal seat positioning groove in shape is convexly arranged on the outer peripheral surface of the shaft seal seat, and the shaft seal seat positioning part can be matched and installed in the shaft seal seat positioning groove, so that the positioning and the installation of the shaft seal seat and the end cover are realized.

In a further specific embodiment of the present utility model, a bearing seat is sleeved on the bearing, a part of the bearing seat is installed in the bearing cavity in a matching way, an end part of the bearing seat opposite to the shaft seal seat also forms a bearing seat end panel, a bearing seat connecting hole matched with the peripheral shape of the oil retainer is formed in the bearing seat end panel, and the oil retainer body is installed in the bearing seat connecting hole in a matching way.

In a further specific embodiment of the utility model, a ring-shaped oil retainer conical part is formed on the peripheral edge of one side surface of the oil retainer facing the shaft seal seat, and an annular shaft seal seat matching ring is also formed on the shaft seal seat joint sleeve of the shaft seal seat, and the peripheral shape of the shaft seal seat matching ring is matched with the inner peripheral shape of the oil retainer conical part, so that the shaft seal seat matching ring and the oil retainer conical part are matched and installed together, and the shaft seal seat and the oil retainer are matched and connected.

In yet another particular embodiment of the utility model, the shaft seal is a lip seal.

Compared with the prior art, the utility model has the beneficial effects that: firstly, a plurality of sealing rings are arranged between a first shaft sleeve I and the cavity wall of an inner cavity of a shaft seal seat, ventilation gaps can be basically blocked, when a dry screw vacuum pump works to pump out mediums such as high-content water vapor, gas with dust particles, corrosive gas and the like, only a small amount of gas can pass through the sealing rings to enter a containing cavity between a second shaft sleeve II and the shaft seal seat, and a shaft seal piece can play a secondary blocking role to further prevent the mediums from entering a sealing structure or a bearing, so that multistage sealing is realized, the sealing performance is greatly improved, and the reliability is high; secondly, by arranging the first shaft sleeve spiral groove on the first shaft sleeve I, when the dry screw vacuum pump works to pump out gas with dust particles, the first shaft sleeve I rotates at a high speed under the drive of the rotor, the first shaft sleeve spiral groove rotating at a high speed can prevent the dust particles from entering into the ventilation gaps, and under the further blocking of the sealing ring, the dust particles are difficult to enter into the shaft sealing piece, so that the sealing performance is improved again, and meanwhile, the shaft sealing piece can be protected in a superior manner, and the service life is prolonged; thirdly, through arranging the oil retainer between the bearing and the shaft seal piece and between the oil retainer and the second shaft sleeve II, the oil retainer can effectively prevent overflowing lubricating oil in the bearing from flowing towards the shaft seal piece, and the oil retainer can be formed into a pincer-shaped structure with the shaft seal seat joint sleeve of the shaft seal seat, so that secondary blocking can be realized, and the shaft seal piece can block the overflowing oil and oil gas in the bearing again, so that the sealing effect is further improved, and the oil leakage phenomenon of the whole mechanism is avoided; finally, when the pressure gas is introduced into the gas channel of the end cover, the pressure gas can be blocked by the shaft seal piece and cannot enter the bearing chamber, and the sealing effect of the bearing is ensured by matching with the input of the pressure gas, so that the service life of the bearing is prolonged, and the durability of the vacuum pump is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of the overall structure of the present utility model;

FIG. 2 is a schematic view of a connection structure between a shaft seal seat and a shaft sleeve assembly according to the present utility model.

In the figure: 1. the sealing device comprises an end cover, a sealing chamber, a shaft seal seat sealing ring, a shaft seal seat positioning groove, a bearing chamber and a gas channel, wherein the end cover, the sealing chamber, the shaft seal seat sealing ring, the shaft seal seat positioning groove, the bearing chamber and the gas channel are arranged in sequence; 2. the rotor, 21, the rotating shaft, 22, the rotating plate; 3. the sealing device comprises a shaft seal seat, a 31-type shaft seal seat inner cavity, a 32-type shaft seal seat joint sleeve, a 321-type shaft seal seat matching ring, a 33-type shaft seal seat ventilation groove, a 34-type shaft seal seat ventilation hole and a 35-type shaft seal seat positioning part; 4. the shaft sleeve assembly 41, the first shaft sleeve I, 411, the first shaft sleeve joint surface 412, the first shaft sleeve external joint surface 413, the first shaft sleeve spiral groove 42, the second shaft sleeve II, 421 and the rotary shaft sealing ring; 5. bearing, 51, bearing seat, 511, bearing seat end panel, 512, bearing seat connecting hole; 6. oil slingers, 61. Oil slinger taper; 7. a shaft seal; 8. a ventilation slit; 9. and (3) a sealing ring.

Detailed Description

The following detailed description of specific embodiments of the utility model, while given in connection with the accompanying drawings, is not intended to limit the scope of the utility model, and any changes that may be made in the form of the inventive concepts described herein, without departing from the spirit and scope of the utility model.

In the following description, any reference to the directions or azimuths of up, down, left, right, front and rear is based on the positions shown in the corresponding drawings, and therefore, should not be construed as a limitation on the technical solutions provided by the present utility model.

Referring to fig. 1 and 2, a dry screw vacuum pump sealing structure is shown, which comprises an end cover 1, wherein a sealing chamber 11 and a bearing chamber 12 are formed in the end cover 1, the end cover 1 is arranged at one side of a vacuum pump body, and the sealing chamber 11 is positioned at the left side of the bearing chamber 12 as shown in fig. 1; a rotor 2, the rotor 2 includes a rotating shaft 21 passing through the sealing chamber 11 and the bearing chamber 12, the rotor 2 is installed in the pump cavity of the vacuum pump; the shaft seal seat 3 is matched and installed in the sealing cavity 11, the shaft seal seat 3 is in a cylindrical shape, a shaft seal seat inner cavity 31 penetrating through the shaft direction of the shaft seal seat 3 is formed in the shaft seal seat 3, a shaft seal seat joint sleeve 32 in an annular shape is formed by narrowing towards the bearing cavity 12 at the end position of the shaft seal seat 3, and the radial diameter of the shaft seal seat joint sleeve 32 is smaller than that of the shaft seal seat 3 body.

In this embodiment, the sealing structure of the dry screw vacuum pump further includes a shaft sleeve assembly 4, the shaft sleeve assembly 4 includes a first shaft sleeve i 41 and a second shaft sleeve ii 42, the radial diameter of the second shaft sleeve ii 42 is smaller than that of the first shaft sleeve i 41, the first shaft sleeve i 41 and the second shaft sleeve ii 42 are fixedly sleeved on the shaft body of the rotating shaft 21, the first shaft sleeve i 41 is attached to the cavity wall of the shaft seal seat inner cavity 31, a part of the second shaft sleeve ii 42 is inserted into the shaft seal seat inner cavity 31, the second shaft sleeve ii 42 is attached between the rotating shaft 21 and the shaft seal seat joint sleeve 32, and a plurality of shaft seal members 7 are further disposed between the second shaft sleeve ii 42 and the cavity wall of the shaft seal seat inner cavity 31, as shown in fig. 1, the number of the shaft seal members 7 is two; a bearing 5, at least a part of the bearing 5 is installed in the bearing chamber 12, and the bearing 5 is sleeved on the rotating shaft 21 and is matched with the rotating shaft in a rotating way; a slinger 6, wherein the slinger 6 is arranged between the second shaft sleeve II 42 and the bearing 5 and is jointed with the second shaft sleeve II and the bearing 5, and the slinger 6 is also jointed with the shaft seal seat joint sleeve 32 of the shaft seal seat 3 in a sealing way; a gas passage penetrating through the shaft seal seat inner cavity 31 is formed between the end cover 1 and the shaft seal seat 3, a vent gap 8 with one end communicated to the outside is formed between the outer peripheral surface of the first shaft sleeve I41 and the cavity wall of the shaft seal seat inner cavity 31, and a plurality of sealing rings 9 are also arranged between the first shaft sleeve I41 and the cavity wall of the shaft seal seat inner cavity 31 and in the corresponding vent gap 8, as shown in fig. 2, the sealing rings 9 are O-shaped sealing rings and are matched and installed on the outer peripheral surface of the first shaft sleeve I41, and the number of the sealing rings 9 is three, and of course, the sealing rings can be flexibly changed according to actual use requirements, and are not repeated herein; and a part of the sealing ring 9 protrudes out of the first shaft sleeve I41 and can isolate the ventilation gap 8, when the dry screw vacuum pump works to pump out high-content water vapor, gas with dust particles, corrosive gas and other mediums, only a small amount of gas can pass through the plurality of sealing rings 9 to enter the containing cavity between the second shaft sleeve II 42 and the shaft seal seat 3 when passing through the ventilation gap 8, so that the sealing performance can be effectively improved, the reliability and the durability of the work can be ensured, water vapor, dust and corrosive gas can be prevented from entering the sealing structure, the damage to equipment is avoided, the efficiency and the reliability of the sealing mechanism are improved, frequent replacement and maintenance are not needed, the use and maintenance cost is effectively saved, and the requirement on the use environment of the dry screw vacuum pump is lower.

Referring to fig. 1 and 2, a gas passage 13 penetrating the sealing chamber 11 is formed in the end cap 1, and a seal seat ventilation groove 33 is formed on the outer peripheral surface of the seal seat 3, wherein one end of the seal seat ventilation groove 33 is disposed corresponding to the gas passage 13; an end face of the first shaft sleeve i 41, which is axially close to the second shaft sleeve ii 42, is a first shaft sleeve fitting face 411, and an end face of the first shaft sleeve i 41, which is axially far from the second shaft sleeve ii 42, is a first shaft sleeve external face 412; the seal seat 3 is also provided with a seal seat vent hole 34 which is communicated with the seal seat inner cavity 31 in the seal seat, one end of the seal seat vent hole 34 away from the seal seat inner cavity 31 is communicated with a seal seat vent groove 33, and the seal seat vent hole 34 can be communicated with the vent gap 8; and the shaft seal seat vent hole 34 is positioned and arranged at a position corresponding to the joint of the first shaft sleeve joint surface 411, i.e. the joint of the first shaft sleeve I41 and the second shaft sleeve II 42.

In the present embodiment, a first sleeve spiral groove 413 is provided on the outer peripheral surface of the first sleeve i 41 at a position close to the first sleeve outer joint surface 412, and a plurality of seal rings 9 are fitted around the middle of the first sleeve i 41 body and positioned between the first sleeve spiral groove 413 and the shaft seal seat vent hole 34.

Notably, are: by providing the gas channel 13 on the end cover 1, when a certain pressure gas such as nitrogen needs to be introduced into the cavity of the dry screw vacuum pump to dilute and purge corrosive gas and dust in the pump cavity of the pump body to avoid corrosion of the pump body and the rotor, the pressure gas enters the seal seat ventilation groove 33 through the gas channel 13, and after the diversion of the seal seat ventilation groove 33 and the seal seat ventilation hole 34, enters the seal seat cavity 31 and enters the space between the second sleeve II 42 and the seal seat 3, at the moment, the pressure gas is blocked by the seal member 7 and cannot enter the bearing cavity 12 on the right side, and the pressure gas can pass through the ventilation gap 8 and the seal ring 9 and further pass through the first sleeve spiral groove 413 to be released into the pump cavity to perform dilution and purge operation.

The sealing effect can be further improved by the arrangement of the first shaft sleeve spiral groove 413, particularly, when the dry screw vacuum pump works to pump out gas with dust particles, the first shaft sleeve I41 is driven by the rotating shaft 21 to rotate at a high speed, the first shaft sleeve spiral groove 413 is also synchronously rotated at a high speed, the dust particles can be blocked from entering the ventilation gap 8 by the first shaft sleeve spiral groove 413 rotating at the high speed, and the dust particles are difficult to enter the position of the shaft seal piece 7 under the further blocking of the sealing ring 9, so that the shaft seal piece 7 is effectively protected, and the service life of the whole structure can be prolonged.

Further, a plurality of seal seals 111 are provided between the inner wall of the seal chamber 11 of the end cap 1 and the outer peripheral surface of the seal seat 3, the seal seals 111 are fitted around the inner peripheral wall of the seal chamber 11, and the seal seals 111 are disposed at positions corresponding to the positions between the seal ventilation grooves 33 and the bearing chamber 12.

With continued reference to fig. 1 and fig. 2, two end portions of the inner cavity of the second shaft sleeve ii 42 are further provided with a rotary shaft sealing ring 421 respectively, the two rotary shaft sealing rings 421 are both sleeved on the shaft body of the rotary shaft 21, one of the two rotary shaft sealing rings 421 is disposed between the first shaft sleeve i 41 and the second shaft sleeve ii 42 in a fitting manner, the rotary shaft sealing ring 421 can effectively improve the sealing effect between the rotary shaft 21 and the first shaft sleeve i 41 and the second shaft sleeve ii 42, and the other rotary shaft sealing ring 421 is disposed between the second shaft sleeve ii 42 and the oil retainer 6 in a fitting manner, so as to improve the sealing performance of the connection point between the second shaft sleeve ii 42 and the oil retainer 6; as shown in fig. 1 and 2, the two rotary shaft seal rings 421 are both configured as O-ring structures.

Preferably, a shaft seal seat positioning groove 112 is formed at an end portion of the sealing chamber 11 far from the bearing chamber 12, and a shaft seal seat positioning portion 35 adapted to the shape of the shaft seal seat positioning groove 112 is formed on the outer circumferential surface of the shaft seal seat 3 in a protruding manner, and the shaft seal seat positioning portion 35 can be fitted in the shaft seal seat positioning groove 112 to realize the fitting connection of the shaft seal seat 3 and the end cover 1.

In this embodiment, a bearing seat 51 is sleeved on the bearing 5, a part of the bearing seat 51 is fitted into the bearing chamber 12, an end portion of the bearing seat 51 opposite to the shaft seal seat 3 further forms a bearing seat end panel 511, a bearing seat connecting hole 512 adapted to the peripheral shape of the oil retainer 6 is formed in the bearing seat end panel 511, and the oil retainer 6 body is fitted into the bearing seat connecting hole 512.

Further, a ring-shaped oil retainer tapered portion 61 is formed on an outer peripheral edge of a side surface of the oil retainer 6 facing the shaft seal seat 3, and an annular shaft seal seat mating ring 321 is formed on the shaft seal seat engaging sleeve 32 of the shaft seal seat 3, and an outer peripheral shape of the shaft seal seat mating ring 321 is adapted to an inner peripheral shape of the oil retainer tapered portion 61, so that the shaft seal seat mating ring 321 is fitted to the oil retainer tapered portion 61, thereby realizing a fitting connection between the shaft seal seat 3 and the oil retainer 6.

It should be noted that: the oil retainer 6 arranged between the bearing 5 and the shaft seal seat 2 can effectively prevent the overflowing lubricating oil in the bearing 5 from flowing towards the shaft seal piece 3, the oil retainer 6 can realize secondary blocking of the oil with a pincer-shaped structure formed by the shaft seal seat joint sleeve 32 of the shaft seal seat 3, the shaft seal piece 7 can block the overflowing oil and oil gas in the bearing 5 again, the lubricating oil is prevented from polluting a pump cavity of the vacuum pump, the sealing effect is further improved, the oil leakage phenomenon of the sealing structure is avoided, and the service life is effectively prolonged.

Preferably, the shaft seal 7 is a lip seal; the lip-shaped sealing ring has strong corrosion resistance, is not easy to age and has good wear resistance, and the lip-shaped sealing ring can be automatically compensated to a certain extent after being worn, thereby enhancing the working reliability.

It should be noted that the above embodiments can be freely changed as required. The foregoing is merely a preferred embodiment of the present utility model and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present utility model, which are intended to be comprehended within the scope of the present utility model. In summary, the technical scheme provided by the utility model overcomes the defects in the prior art, successfully completes the task of the utility model, and faithfully honors the technical effects carried by the applicant in the technical effect column above.

Claims (9)

1. A dry screw vacuum pump seal structure, comprising: an end cover (1), wherein a sealing chamber (11) and a bearing chamber (12) are formed in the end cover (1); a rotor (2) having a rotation shaft (21) passing through the sealing chamber (11) and the bearing chamber (12); the shaft seal seat (3) is matched and installed in the sealing cavity (11), a shaft seal seat inner cavity (31) which is communicated with the shaft direction of the shaft seal seat is formed in the shaft seal seat (3), and a shaft seal seat joint sleeve (32) which is in an annular shape is formed at the end part position of the shaft seal seat (3) towards the bearing cavity (12); the shaft sleeve assembly (4) comprises a first shaft sleeve I (41) and a second shaft sleeve II (42), the first shaft sleeve I (41) and the second shaft sleeve II (42) are fixedly sleeved on a shaft body of the rotating shaft (21), the first shaft sleeve I (41) is attached to a cavity wall of an inner cavity (31) of the shaft seal seat, a part of the second shaft sleeve II (42) is penetrated into the inner cavity (31) of the shaft seal seat, the second shaft sleeve II (42) is arranged between the rotating shaft (21) and the joint sleeve (32) of the shaft seal seat, and a plurality of shaft seal pieces (7) are further arranged between the second shaft sleeve II (42) and the cavity wall of the inner cavity (31) of the shaft seal seat; a bearing (5), at least a part of the bearing (5) is arranged in the bearing chamber (12), and the bearing (5) is sleeved on the rotating shaft (21) and is in rotating fit with the rotating shaft; the oil retainer (6) is arranged between the second shaft sleeve II (42) and the bearing (5) and is attached to the second shaft sleeve II and the bearing, and the oil retainer (6) is also matched with the shaft seal seat joint sleeve (32) of the shaft seal seat (3); a conducting air passage penetrating through the shaft seal seat inner cavity (31) is further formed between the end cover (1) and the shaft seal seat (3), an air vent gap (8) is formed between the outer peripheral surface of the first shaft sleeve I (41) and the cavity wall of the shaft seal seat inner cavity (31), and a plurality of sealing rings (9) are further arranged between the first shaft sleeve I (41) and the cavity wall of the shaft seal seat inner cavity (31) and correspond to the air vent gap (8).

2. A dry screw vacuum pump seal structure according to claim 1, wherein: a gas channel (13) penetrating through the sealing chamber (11) in the end cover (1) is formed on the end cover, a shaft seal seat ventilation groove (33) is formed on the outer peripheral surface of the shaft seal seat (3), and one end part of the shaft seal seat ventilation groove (33) is arranged corresponding to the gas channel (13); the end face, close to the second shaft sleeve II (42), of the first shaft sleeve I (41) in the axial direction is a first shaft sleeve joint face (411), and the end face, far away from the second shaft sleeve II (42), of the first shaft sleeve I (41) in the axial direction is a first shaft sleeve external joint face (412); the inside of the shaft seal seat (3) is also provided with a shaft seal seat vent hole (34) communicated with the shaft seal seat inner cavity (31) in the shaft seal seat, one end of the shaft seal seat vent hole (34) away from the shaft seal seat inner cavity (31) is communicated with a shaft seal seat vent groove (33), and the shaft seal seat vent hole (34) can be communicated with the vent gap (8); and the shaft seal seat vent hole (34) is positioned and arranged at a position corresponding to the joint of the first shaft sleeve joint surface (411), namely the joint of the first shaft sleeve I (41) and the second shaft sleeve II (42).

3. A dry screw vacuum pump seal structure according to claim 2, wherein: a first sleeve spiral groove (413) is formed in the outer peripheral surface of the first sleeve I (41) and close to the first sleeve external connection surface (412), and a plurality of sealing rings (9) are sleeved on the middle of the first sleeve I (41) body and positioned at the position between the first sleeve spiral groove (413) and the shaft seal seat vent hole (34).

4. A dry screw vacuum pump seal according to claim 2 or 3, wherein: a plurality of seal seat sealing rings (111) are further arranged between the inner wall of the seal chamber (11) of the end cover (1) and the outer peripheral surface of the seal seat (3), the seal seat sealing rings (111) are sleeved on the inner peripheral wall of the seal chamber (11), and the seal seat sealing rings (111) are arranged at positions corresponding to the positions between the seal seat ventilation grooves (33) and the bearing chamber (12).

5. A dry screw vacuum pump seal structure according to claim 1, wherein: two end parts of the inner cavity of the second shaft sleeve II (42) are respectively provided with a rotating shaft sealing ring (421), the two rotating shaft sealing rings (421) are sleeved on the shaft body of the rotating shaft (21), one of the two rotating shaft sealing rings (421) is attached between the first shaft sleeve I (41) and the second shaft sleeve II (42), and the other is attached between the second shaft sleeve II (42) and the oil retainer (6).

6. A dry screw vacuum pump seal structure according to claim 1, wherein: a shaft seal seat positioning groove (112) is formed at one end part of the sealing chamber (11) far away from the bearing chamber (12), a shaft seal seat positioning part (35) matched with the shaft seal seat positioning groove (112) in shape is convexly arranged on the outer circumferential surface of the shaft seal seat (3), and the shaft seal seat positioning part (35) can be matched and installed in the shaft seal seat positioning groove (112), so that the positioning and installation of the shaft seal seat (3) and the end cover (1) are realized.

7. A dry screw vacuum pump seal structure according to claim 1, wherein: the bearing (5) is sleeved with a bearing seat (51), a part of the bearing seat (51) is matched and installed in the bearing cavity (12), one end part of the bearing seat (51) opposite to the shaft seal seat (3) is further provided with a bearing seat end panel (511), the bearing seat end panel (511) is provided with a bearing seat connecting hole (512) matched with the peripheral shape of the oil retainer (6), and the oil retainer (6) body is matched and installed in the bearing seat connecting hole (512).

8. A dry screw vacuum pump seal structure according to claim 1, wherein: a ring-shaped oil retainer conical part (61) is formed on the peripheral edge of one side surface of the oil retainer (6) facing the shaft seal seat (3), an annular shaft seal seat matching ring (321) is further formed on a shaft seal seat joint sleeve (32) of the shaft seal seat (3), the peripheral shape of the shaft seal seat matching ring (321) is matched with the inner peripheral shape of the oil retainer conical part (61), and the shaft seal seat matching ring (321) is matched with the oil retainer conical part (61) to be installed together, so that the shaft seal seat (3) is matched and connected with the oil retainer (6).

9. A dry screw vacuum pump seal structure according to claim 1, wherein: the shaft seal (7) is a lip-shaped sealing ring.