Screw vacuum pump

Abstract

The utility model discloses a screw vacuum pump which comprises a pump body and two connecting shafts, a screw pump body cavity is arranged in the pump body, two screw rotor components meshed with each other are arranged in the screw pump body cavity, and each screw rotor component is installed on one connecting shaft. A pump body cavity is formed in each pump shell, and the two pump body cavities form the screw pump body cavity; a convex ring is arranged on the end face of one pump shell, a concave cavity matched with the convex ring is formed in the end face of the other pump shell, and the convex ring is inserted into the concave cavity; an air inlet and an air outlet which are communicated with the screw pump body cavity are respectively formed in the outer wall of the pump body; a silencer is further installed on the portion, on the air outlet side, of the outer wall of the pump body, a connecting air inlet and an air outlet are formed in the silencer, and the connecting air inlet is communicated with the air outlet. According to the utility model, the assembling and debugging convenience is improved, and the noise is reduced.

Description

Technical Field

[0001] The utility model relates to a vacuum pump, in particular to a screw vacuum pump. Background Art

[0002] As vacuum plays an increasingly important role in the field of new industrial technologies, the demand for vacuum pumps has increased rapidly. The original traditional vacuum pumps are mainly vacuum systems composed of liquid ring pumps, steam ejectors, reciprocating vacuum pumps, Roots vacuum pumps, oil sliding valve pumps or oil rotary vane pumps, etc. These vacuum pumps themselves have high energy consumption and low efficiency, or produce waste water and waste oil in the process of obtaining vacuum, which pollutes the environment. Therefore, when the dry screw vacuum pump was successfully developed and applied, it was widely used to replace the original traditional vacuum pumps due to its high efficiency, energy saving and no secondary pollutant emissions.

[0003] Roots vacuum pumps and screw vacuum pumps are both positive displacement vacuum pumps, which realize the transfer of gas in the pump chamber by rotating two intermeshing rotor parts. For example, the application number is: 202210430835.5, the patent name is: a two-stage pump body and its vacuum pump, which adopts a two-stage pump body structure, but the structure has the following shortcomings:

[0004] 1. Due to the high precision of the internal pump body cavity, the alignment speed of the two pump shells is slow and the alignment accuracy is low when they are assembled, which requires a long time for debugging;

[0005] 2. The gas delivered by the screw pump is discharged directly. Due to the fast exhaust speed, the noise will be relatively loud. Summary of the invention

[0006] The utility model aims to provide a screw vacuum pump. By using the structure, the screw vacuum pump can be made more compact, the convenience of assembly is improved, and the noise is reduced.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a screw vacuum pump, comprising a pump body and two connecting shafts which are parallel to each other and rotatably installed in the pump body, a screw pump body cavity is arranged in the pump body, two screw rotor parts which mesh with each other are arranged in the screw pump body cavity, each of the screw rotor parts is respectively installed on a connecting shaft, the pump body comprises two pump shells, each of the pump shells is provided with a pump body cavity, one end of the pump body cavity is connected with one side of the pump shell, and the opening direction of the pump body cavity is arranged toward the other pump shell, and the two pump body cavities constitute the screw pump body cavity;

[0008] A convex ring is provided on the end surface of one pump housing, and a concave cavity matching the convex ring is provided on the end surface of the other pump housing, and the convex ring is inserted into the concave cavity;

[0009] An air inlet and an air outlet connected to the screw pump body cavity are respectively provided on the outer wall of the pump body, wherein the air inlet is connected to one end of the screw pump body cavity, and the air outlet is connected to the other end of the screw pump body cavity;

[0010] A muffler is also installed on the outer wall of the pump body at the air outlet side, and the muffler is provided with a connecting air inlet and an exhaust port, and the connecting air inlet is communicated with the air outlet.

[0011] In the above technical solution, a one-way valve is installed on the exhaust port.

[0012] In the above technical solution, the muffler includes a shell, a muffler cavity is provided in the shell, and the connecting air inlet and the exhaust port are connected to the muffler cavity;

[0013] And / or, at least two partitions are provided in the muffler cavity, and a plurality of the partitions are arranged between the connecting air inlet and the exhaust port at intervals, and the plurality of the partitions divide the muffler cavity into a plurality of independent chambers, and the connecting air inlet and the exhaust port are respectively connected to one of the chambers at both ends of the muffler;

[0014] Each of the partitions is provided with a connecting hole for connecting the adjacent chambers.

[0015] In the above technical solution, the connection holes on the adjacent partitions are arranged staggered with each other;

[0016] And / or, a connecting pipe is installed on each of the connecting holes, and the connecting pipe connects the adjacent chambers.

[0017] In the above technical solution, a sealing structure is provided between the two pump casings;

[0018] The sealing structure includes a first sealing structure and a second sealing structure, wherein the first sealing structure is disposed between the convex ring and the concave cavity, the second sealing structure is disposed outside the first sealing structure, and the second sealing structure is disposed outside the convex ring and the concave cavity.

[0019] In the above technical solution, the first sealing structure includes a first elastic sealing ring; a first sealing ring installation groove is provided on the end surface of the concave cavity or on the end surface of the convex ring, and the first sealing ring is installed in the first sealing ring installation groove;

[0020] The second sealing structure comprises a second elastic sealing ring. A second sealing ring installation groove is provided on the pump housing end surface outside the convex ring or on the pump housing end surface outside the concave cavity. The second sealing ring is installed in the second sealing ring installation groove.

[0021] In the above technical solution, the air inlet and the air outlet are respectively arranged on the two pump shells, and the air inlet and the air outlet are respectively connected to the corresponding pump body cavity in the pump shell, the air inlet is connected to the end away from the corresponding pump body cavity opening, and the air outlet is connected to the end away from the corresponding pump body cavity opening.

[0022] In the above technical solution, a gear housing is provided at each end of the pump body, and a gear cavity is provided in each gear housing;

[0023] The two ends of the connecting shaft are rotatably connected to the ends of the two pump shells respectively, and the ends of the connecting shaft are respectively inserted into the gear cavity on one side.

[0024] In the above technical solution, a first gear is installed at one end of each of the connecting shafts, the first gear is arranged in one of the gear chambers, and the two first gears are meshed with each other;

[0025] A second gear is installed at the other end of one of the connecting shafts, and a connecting bearing is installed at the other end of another of the connecting shafts. A connecting gear is rotatably installed outside the connecting bearing. The connecting bearing, the connecting gear and the second gear are arranged in another of the gear cavities, and the connecting gear is meshed with the second gear.

[0026] In the above technical solution, the outer diameter of the connecting gear is different from the outer diameter of the second gear;

[0027] And / or, a driving mechanism is installed on the outer wall of the gear housing on one side of the connecting gear, the end of the driving mechanism is inserted into the gear cavity of the gear housing, and the end of the driving mechanism is connected to the connecting gear, and the driving mechanism is configured to drive the connecting gear to rotate.

[0028] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0029] 1. In the utility model, the two pump casings are quickly assembled and positioned directly through the convex ring and the concave cavity, which can effectively improve the assembly efficiency and reduce the debugging time;

[0030] 2. In the utility model, a muffler is installed on the air outlet of the pump body. The installation of the muffler can effectively reduce the noise during the exhaust process of the vacuum pump, which is more environmentally friendly;

[0031] 3. In the utility model, a one-way valve is installed on the exhaust port to prevent gas from entering from the exhaust port of the pump body, further reducing exhaust noise;

[0032] 3. The utility model also provides two connecting gears and a second gear of different sizes, thereby forming a variable speed gear structure, which can effectively increase the rotation speed of the internal screw rotor component and improve the vacuuming efficiency;

[0033] 4. The pump body of the utility model adopts a two-stage structure, which can be flatter and more compact, with a simpler structure and is easy to produce and manufacture. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the first embodiment of the present utility model;

[0035] Figure 2 yes Figure 1 A top view of

[0036] Figure 3 yes Figure 1 Schematic diagram of the cross-sectional structure of the middle BB;

[0037] Figure 4 yes Figure 2 Schematic diagram of the cross-sectional structure of the CC;

[0038] Figure 5 This is a schematic diagram of the structure of the pump body in the split state in the first embodiment of the utility model;

[0039] Figure 6 It is a schematic diagram of the end surface structure of the second pump casing in the first embodiment of the utility model;

[0040] Figure 7 yes Figure 1 Schematic diagram of the cross-sectional structure of AA;

[0041] Figure 8 It is a structural schematic diagram of the muffler in the first embodiment of the utility model;

[0042] Fig. 9 It is a schematic cross-sectional structural diagram of the muffler in the first embodiment of the utility model.

[0043] Wherein: 1. pump body; 2. connecting shaft; 3. screw pump body cavity; 4. screw rotor component; 5. convex ring; 6. concave cavity; 7. air inlet; 8. air outlet; 9. muffler; 10. connecting air inlet; 11. exhaust port; 12. first pump shell; 13. second pump shell; 14. first pump body cavity; 15. second pump body cavity; 16. shell; 17. partition; 18. chamber; 19. connecting pipe; 20. first sealing structure; 21. second sealing structure; 22. first sealing ring installation groove; 23. second sealing ring installation groove; 24. cooling cavity; 25. first gear shell; 26. second gear shell; 27. first gear cavity; 28. second gear cavity; 29. ​​first gear; 30. second gear; 31. connecting bearing; 32. connecting gear; 33. driving mechanism. DETAILED DESCRIPTION

[0044] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0045] Example 1: See Figures 1 to 9 As shown, a screw vacuum pump comprises a pump body 1 and two connecting shafts 2 which are parallel to each other and rotatably installed in the pump body 1, a screw pump body cavity 3 is arranged in the pump body 1, two screw rotor parts 4 which are meshed with each other are arranged in the screw pump body cavity 3, each of the screw rotor parts 4 is respectively installed on a connecting shaft 2, the pump body 1 comprises two pump shells, each of the pump shells is provided with a pump body cavity, one end of the pump body cavity is connected with one side of the pump shell, and the opening direction of the pump body cavity is arranged toward the other pump shell, and the two pump body cavities constitute the screw pump body cavity 3;

[0046] A convex ring 5 is provided on the end surface of one of the pump shells, and a concave cavity 6 matching the convex ring 5 is provided on the end surface of the other pump shell, and the convex ring 5 is inserted into the concave cavity 6;

[0047] An air inlet 7 and an air outlet 8 communicating with the screw pump body cavity 3 are respectively provided on the outer wall of the pump body 1, wherein the air inlet 7 is connected to one end of the screw pump body cavity 3, and the air outlet 8 is connected to the other end of the screw pump body cavity 3;

[0048] A muffler 9 is further installed on the outer wall of the pump body 1 on the side of the air outlet 8 , and the muffler 9 is provided with a connecting air inlet 10 and an air outlet 11 , and the connecting air inlet 10 is communicated with the air outlet 8 .

[0049] In this embodiment, in actual use, the pitch of the screw rotor component gradually decreases from the air inlet toward the air outlet. In this process, the two meshing screw rotor components rotate synchronously and in opposite directions, and the gas at the air inlet is drawn into the screw pump body cavity, and then sent out toward the air outlet, and then sent to the connecting air inlet of the muffler through the air outlet, and then discharged from the exhaust port after being silenced by the muffler. Among them, when the two pump shells are assembled, the convex ring and the concave cavity are used for rapid positioning to achieve the alignment of the two pump shells. At the same time, screw holes are set at the connection of the two pump shells, and the two pump shells are quickly connected by bolts. In this way, the assembly efficiency is high, and no debugging is required between the two pump shells, which can ensure that the inner walls of the pump body cavities of the two pump shells are flush, thereby ensuring the assembly quality. During assembly, first connect one end of the coupling shaft to a pump casing, then install the two screw rotor components on the corresponding coupling shafts, and then align the two pump casings by aligning the convex ring and the concave cavity, and then use bolts to lock the two pump casings to achieve quick installation. Among them, the connection between the coupling shaft and the corresponding pump casing is rotatably connected by a bearing, and the position of the bearing is fine-tuned to adjust the gap between the screw rotor component and the screw pump body cavity, and the gap between the two screw rotor components can also be adjusted. Of course, in the utility model, the screw rotor component and the coupling shaft can be a separate structure, or an integrated structure.

[0050] In this embodiment, the pump housing includes a first pump housing 12 and a second pump housing 13. The pump body cavity in the first pump housing 12 is a first pump body cavity 14. The right end of the first pump body cavity 14 is connected to the right end face of the first pump housing 12. The pump body cavity in the second pump housing 13 is a second pump body cavity 15. The left end of the second pump body cavity 15 is connected to the left end face of the second pump housing 13. The right end of the first pump housing fits the left end of the second pump housing, and the two are connected by bolts. In this embodiment, the concave cavity is arranged on the right end face of the first pump housing, and the inner surface of the concave cavity is connected to the right end of the first pump body cavity. The convex ring is arranged on the left end face of the second pump housing, and the inner surface of the convex ring is arranged flush with the inner surface of the second pump body cavity. In this way, when the first pump housing and the second pump housing are connected, the convex ring is directly inserted into the concave cavity to realize the rapid positioning of the first pump housing and the second pump housing. After the positioning is completed, the first pump housing and the second pump housing are screwed together by bolts.

[0051] Wherein, a one-way valve is installed on the exhaust port. Through the setting of the one-way valve, it can be ensured that when the exhaust port is exhausted, no air will enter the muffler at the sewage outlet, making the exhaust smoother and the exhaust sound smaller.

[0052] See also Figure 4 , 8As shown in FIG. 9 , the muffler 9 includes a shell 16, a muffler cavity is provided in the shell 16, and the connecting air inlet 10 and the exhaust port 11 are connected to the muffler cavity;

[0053] At least two partitions 17 are provided in the muffler cavity, and a plurality of the partitions 17 are arranged between the connecting air inlet 10 and the exhaust port 11 at intervals. The plurality of the partitions 17 divide the muffler cavity into a plurality of independent chambers 18, and the connecting air inlet 10 and the exhaust port 11 are respectively connected to one of the chambers 18 at both ends of the muffler 9;

[0054] Each of the partitions 17 is provided with a connection hole for connecting the adjacent chambers 18 .

[0055] The silencer chamber is divided into multiple independent chambers by partitions, and the adjacent chambers are connected by connecting holes. In this way, when the gas connected to the air inlet flows to the exhaust port and is discharged, the partition can block and slow down the gas to a certain extent, and when the gas hits the partition, the impact force and energy of the gas itself can be consumed, thereby reducing the exhaust noise and playing a certain silencing role.

[0056] Furthermore, the connection holes on the partition are staggered with each other. The staggered arrangement can extend the flow path of the gas, and the gas will collide with the partition first, consuming the energy of the gas and reducing noise.

[0057] See also Fig. 9 As shown, a connecting pipe 19 is installed on each of the connecting holes, and the connecting pipe 19 connects the adjacent chambers 18. Furthermore, the two ends of the connecting pipe are respectively arranged close to the inner walls of the chambers on both sides, so that the gas needs to hit the partition first, and then flow in the cavity before being discharged from another connecting pipe, thereby increasing the energy and flow rate of the gas flow process and making the exhaust sound smaller.

[0058] See also Figures 3 to 5 As shown, a sealing structure is provided between the two pump casings;

[0059] The sealing structure includes a first sealing structure 20 and a second sealing structure 21 . The first sealing structure 20 is disposed between the convex ring 5 and the concave cavity 6 , and the second sealing structure 21 is disposed outside the first sealing structure 20 . The second sealing structure 21 is disposed outside the convex ring 5 and the concave cavity 6 .

[0060] The sealing structure is used to seal the connection between the two pump shells, so that the gas can only enter the screw pump body cavity from the air inlet and can only be discharged from the air outlet, ensuring the vacuum effect. In addition, the double-channel sealing structure is used, which has a better sealing effect.

[0061] See also Figures 3 to 5 As shown, the first sealing structure 20 includes a first elastic sealing ring; a first sealing ring installation groove 22 is provided on the end surface of the concave cavity 6 or on the end surface of the convex ring, and the first sealing ring is installed in the first sealing ring installation groove 22;

[0062] The second sealing structure 21 includes a second elastic sealing ring. A second sealing ring installation groove 23 is provided on the pump housing end surface outside the convex ring 5 or on the pump housing end surface outside the concave cavity. The second sealing ring is installed in the second sealing ring installation groove 23.

[0063] In this embodiment, the first sealing ring installation groove is arranged on the left end face at the outer edge of the concave cavity, and the second sealing ring installation groove is arranged on the pump housing end face outside the concave cavity, that is, the first sealing ring installation groove and the second sealing ring installation groove are both arranged on the right end face of the first pump housing, when the convex ring and the concave cavity are aligned and assembled, it can be sealed by the first elastic sealing ring, and when the right end face of the first pump housing and the left end face of the second pump housing are connected, the second elastic sealing ring is used to perform double sealing to ensure the sealing effect. At the same time, in this embodiment, the cross-sectional diameter of the first elastic sealing ring will be greater than the width of the first sealing ring installation groove, and the cross-sectional diameter of the second elastic sealing ring will be greater than the width of the second sealing ring installation groove, so that when the first elastic sealing ring and the second elastic sealing ring are installed in the corresponding sealing ring installation groove, their outer surfaces will be against the inner wall of the corresponding sealing ring installation groove, and their right outer surfaces will be outside the right side of the corresponding sealing ring installation groove, and when the first pump housing and the second pump housing are locked, the corresponding elastic sealing ring will be squeezed and deformed, and tightly pressed in the corresponding sealing ring installation groove, thereby achieving the sealing of the screw pump body cavity.

[0064] See also Figure 1 , 2 As shown in Figures 4 and 5, the air inlet 7 and the air outlet 8 are respectively arranged on the two pump housings, and the air inlet and the air outlet are respectively connected with the corresponding pump body cavities in the pump housings, the air inlet is connected with an end away from the corresponding pump body cavity opening, and the air outlet is connected with an end away from the corresponding pump body cavity opening.

[0065] In this embodiment, the air inlet 7 is arranged on the left side of the top of the first pump casing 12, and its bottom is connected to the left side of the first pump body cavity 14. The air outlet 8 is arranged on the right side of the bottom of the second pump casing 13, and its top is connected to the right side of the second pump body cavity 15. In this way, the air flow can rotate along the screw rotor component 4 and be discharged from the right bottom of the pump body 1.

[0066] Furthermore, a cooling chamber 24 is provided in the pump casing, and the cooler surrounds the outside of the corresponding pump body cavity. A cooling medium inlet and a cooling medium outlet are provided on the outer wall of the pump casing and are connected to the cooling chamber for conveying the cooling medium to cool the pump body, thereby extending the service life and ensuring the vacuum effect.

[0067] See also Figures 1 to 4 As shown in 7, a gear housing is provided at each end of the pump body 1, and a gear cavity is provided in each gear housing;

[0068] The two ends of the connecting shaft 2 are rotatably connected to the ends of the two pump shells respectively, the middle part of the connecting shaft is located in the pump body cavities of the two pump shells, and the ends of the connecting shaft 2 are respectively inserted into the gear cavity on one side.

[0069] In this embodiment, the gear housing is a first gear housing 25 and a second gear housing 26, the gear cavity is a first gear cavity 27 and a second gear cavity 28, the first gear cavity 27 is arranged in the first gear housing 25, and the second gear cavity 28 is arranged in the second gear housing 26. The first gear housing is installed on the left side of the first pump housing, and the second gear housing is installed on the right side of the second pump housing. The two ends of the connecting shaft are rotatably connected to the two pump housings through bearings respectively.

[0070] See also Figure 3 , 4 As shown in Figures 7 and 8, a first gear 29 is installed at one end of each of the coupling shafts 2, the first gear 29 is arranged in one of the gear cavities, and the two first gears 29 are meshed with each other; wherein, a first gear is arranged at the left end of the coupling shaft, and the first gear is arranged in the first gear cavity.

[0071] The other end of one of the connecting shafts 2 is installed with a second gear 30, and the other end of another connecting shaft 2 is installed with a connecting bearing 31, and a connecting gear 32 is rotatably installed outside the connecting bearing 31. The connecting bearing 31, the connecting gear 32 and the second gear 30 are arranged in another gear cavity, and the connecting gear 32 is meshed with the second gear 30. Among them, the right end of one connecting shaft is installed with a second gear, and the right end of another connecting shaft is installed with a connecting bearing and a connecting gear, and the connecting gear is rotatably connected with the connecting shaft through the connecting bearing.

[0072] See also Figure 7 As shown, the outer diameter of the connecting gear is different from the outer diameter of the second gear; in this embodiment, the diameters of the first gear and the second gear are equal, and the outer diameter of the connecting gear is greater than the outer diameter of the second gear.

[0073] A driving mechanism 33 is installed on the outer wall of the gear housing on one side of the connecting gear 32, the end of the driving mechanism 33 is inserted into the gear cavity of the gear housing, and the end of the driving mechanism 33 is connected to the connecting gear 32, and the driving mechanism 33 is configured to drive the connecting gear 32 to rotate. In this embodiment, the driving mechanism is installed on the right outer wall of the second gear housing.

[0074] The driving mechanism adopts a combination of a motor and a reducer, or the driving mechanism directly adopts a motor. The driving mechanism is directly connected to the connecting gear to drive the connecting gear to rotate.

[0075] In the utility model, the connecting gear and the second gear form a speed change structure. For example, the outer diameter of the connecting gear is larger than the outer diameter of the second gear. The number of teeth of the connecting gear will be more than the number of teeth of the second gear. Therefore, when the driving mechanism drives the connecting gear to rotate, due to the meshing relationship between the connecting gear and the second gear, the second gear will be synchronously driven to rotate. The second gear is directly connected to the connecting shaft. Therefore, the second gear will drive a connecting shaft to rotate. Due to the meshing of the two first gears, when the connecting shaft rotates, another connecting shaft is driven to rotate through the first gear, thereby realizing the accelerated rotation of the connecting shaft and the screw rotor component. At the same time, since the connecting gear is connected to the connecting shaft through the connecting bearing, the connecting gear and the first gear at the other end will not interfere with each other. When the first gear at the left end synchronously drives the connecting shaft to rotate, the connecting shaft and the connecting gear rotate through the connecting bearing. The speeds of the connecting gear and the connecting shaft on which the connecting gear is installed are different, which will not affect the normal operation of the vacuum pump. This structure is an accelerating gear structure.

[0076] Similarly, if the size of the connecting gear is smaller than that of the second gear, the number of teeth of the connecting gear will be less than that of the second gear, and the rotation speed of the connecting gear will be greater than that of the second gear. This structure is a reduction gear structure.

[0077] You can choose according to the actual situation. In this embodiment, it is preferred that the diameter of the connecting gear is larger than the diameter of the second gear. In this way, the connecting gear and the second gear form an acceleration gear structure, which can increase the vacuum pumping efficiency. At the same time, the power of the driving mechanism does not need to be increased, and the cost is lower.

[0078] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0079] In the present utility model, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral one; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, for example, the two can form a mechanical abutment or abutment connection through abutment, contact, etc., the two can also be directly hung or hung through an intermediate medium, etc., or it can be the internal connection of the two elements or the interaction relationship between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A screw vacuum pump, comprising a pump body and two connecting shafts which are parallel to each other and rotatably mounted in the pump body, wherein a screw pump body cavity is provided in the pump body, and two mutually meshing screw rotor components are provided in the screw pump body cavity, and each of the screw rotor components is respectively mounted on a connecting shaft, characterized in that: The pump body includes two pump shells, each of which is provided with a pump body cavity, one end of the pump body cavity is connected to one side of the pump shell, and the opening direction of the pump body cavity is arranged toward the other pump shell, and the two pump body cavities constitute the screw pump body cavity; A convex ring is provided on the end surface of one pump housing, and a concave cavity matching the convex ring is provided on the end surface of the other pump housing, and the convex ring is inserted into the concave cavity; An air inlet and an air outlet connected to the screw pump body cavity are respectively provided on the outer wall of the pump body, wherein the air inlet is connected to one end of the screw pump body cavity, and the air outlet is connected to the other end of the screw pump body cavity; A muffler is also installed on the outer wall of the pump body at the air outlet side, and the muffler is provided with a connecting air inlet and an exhaust port, and the connecting air inlet is communicated with the air outlet.

2. The screw vacuum pump according to claim 1, characterized in that: A one-way valve is installed on the exhaust port.

3. The screw vacuum pump according to claim 1, characterized in that: The muffler comprises a shell, a muffler cavity is arranged in the shell, and the connecting air inlet and the air outlet are connected to the muffler cavity; And / or, at least two partitions are provided in the muffler cavity, and a plurality of the partitions are arranged between the connecting air inlet and the exhaust port at intervals, and the plurality of the partitions divide the muffler cavity into a plurality of independent chambers, and the connecting air inlet and the exhaust port are respectively connected to one of the chambers at both ends of the muffler; Each of the partitions is provided with a connecting hole for connecting the adjacent chambers.

4. The screw vacuum pump according to claim 3, characterized in that: The connection holes on the adjacent partitions are arranged in a staggered manner; And / or, a connecting pipe is installed on each of the connecting holes, and the connecting pipe connects the adjacent chambers.

5. The screw vacuum pump according to claim 1, characterized in that: A sealing structure is provided between the two pump casings; The sealing structure includes a first sealing structure and a second sealing structure, wherein the first sealing structure is disposed between the convex ring and the concave cavity, the second sealing structure is disposed outside the first sealing structure, and the second sealing structure is disposed outside the convex ring and the concave cavity.

6. The screw vacuum pump according to claim 5, characterized in that: The first sealing structure comprises a first elastic sealing ring; a first sealing ring installation groove is provided on the end surface of the concave cavity or on the end surface of the convex ring, and the first sealing ring is installed in the first sealing ring installation groove; The second sealing structure comprises a second elastic sealing ring. A second sealing ring installation groove is provided on the pump housing end surface outside the convex ring or on the pump housing end surface outside the concave cavity. The second sealing ring is installed in the second sealing ring installation groove.

7. The screw vacuum pump according to claim 1, characterized in that: The air inlet and the air outlet are respectively arranged on the two pump shells, and the air inlet and the air outlet are respectively connected to the corresponding pump body cavity in the pump shell, the air inlet is connected to the end away from the corresponding pump body cavity opening, and the air outlet is connected to the end away from the corresponding pump body cavity opening.

8. The screw vacuum pump according to claim 1, characterized in that: The two ends of the pump body are respectively provided with a gear housing, and each of the gear housings is respectively provided with a gear cavity; The two ends of the connecting shaft are rotatably connected to the ends of the two pump shells respectively, and the ends of the connecting shaft are respectively inserted into the gear cavity on one side.

9. The screw vacuum pump according to claim 8, characterized in that: A first gear is installed at one end of each of the connecting shafts, the first gear is arranged in one of the gear cavities, and the two first gears are meshed with each other; A second gear is installed at the other end of one of the connecting shafts, and a connecting bearing is installed at the other end of another of the connecting shafts. A connecting gear is rotatably installed outside the connecting bearing. The connecting bearing, the connecting gear and the second gear are arranged in another of the gear cavities, and the connecting gear is meshed with the second gear.

10. The screw vacuum pump according to claim 9, characterized in that: The outer diameter of the connecting gear is different from the outer diameter of the second gear; And / or, a driving mechanism is installed on the outer wall of the gear housing on one side of the connecting gear, the end of the driving mechanism is inserted into the gear cavity of the gear housing, and the end of the driving mechanism is connected to the connecting gear, and the driving mechanism is configured to drive the connecting gear to rotate.

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