KR100855187B1 - Composite dry vacuum pump having roots and screw rotor - Google Patents

Abstract

A Roots rotor and a screw rotor combined dry vacuum pump for evacuating process chambers of semiconductor and display manufacturing apparatus or for discharging gaseous substances and / or process by-products generated in the process chamber to the outside. The Roots rotor and screw rotor composite dry vacuum pump has an inner accommodating space, the inlet is provided on one side and the outlet is provided on the other side and the first accommodating and installed in the inner accommodating space of the housing. A first and a second screw rotor, the first and second root rotors, the first and second root rotors, which are accommodated in an inner receiving space of the housing and are interlocked with each other in close proximity to the first and second root rotors; Stator provided inside the case and winding the first and second gear shafts installed through the center of the second screw rotor and the first and second gears and coils which are engaged with and coupled to the first and second gear shafts. And a motor having a rotor connected to the first transmission shaft so as to be rotatable inside the stator, wherein the first and second Roots rotors have three lobes each of which has three lobes. Made and the stator is characterized in that the filler to protect the coil from various by-products flowing in the interior of the housing is filled with molding. This structure maintains high gas compression transfer efficiency when evacuating the process chambers of semiconductor and display manufacturing apparatus or when discharging the gaseous substances and / or process by-products generated in the process chamber to the outside, and is generated in the vacuum pump. It is possible to prevent the vibration and noise, and to protect the coil of the stator from the various by-products flowing from the vacuum pump at the same time has the advantage of improving the efficiency of the motor.

Roots rotor, screw rotor, motor, stator, rotor, epoxy resin, hermetic terminal, dry vacuum pump

Description

Roots and screw rotors combined dry vacuum pumps {COMPOSITE DRY VACUUM PUMP HAVING ROOTS AND SCREW ROTOR}

1 is a schematic cross-sectional view of a roots rotor and a screw rotor composite dry vacuum pump according to a first preferred embodiment of the present invention;

FIG. 2 is a schematic longitudinal sectional view of the Roots rotor and screw rotor combined dry vacuum pump shown in FIG. 1; FIG.

3 is a perspective view of the root rotor and screw rotor of the root rotor and screw rotor composite dry vacuum pump shown in FIG.

Figure 4 is a schematic diagram showing the operating state of the Roots rotor and screw rotor combined dry vacuum pump according to the first embodiment of the present invention;

5 is a schematic cross-sectional view of a roots rotor and a screw rotor combined dry vacuum pump according to a second preferred embodiment of the present invention;

FIG. 6 is a schematic longitudinal sectional view of the Roots rotor and screw rotor combined dry vacuum pump shown in FIG. 5; FIG.

7 is a perspective view of a roots rotor and a screw rotor composite dry vacuum pump according to a third embodiment of the present invention;

FIG. 8 is a schematic cross-sectional view of the Roots rotor and screw rotor combined dry vacuum pump shown in FIG. 7; FIG.

9 is a schematic cross sectional view of a conventional dry vacuum pump.

* Description of the symbols for the main parts of the drawings *

10 housing 11 suction port

12 Outlet 21, 22 First and second transmission shafts 31, 32 First and second root rotors 41, 42 First and second screw rotors

50: motor 58: epoxy resin

The present invention relates to a dry vacuum pump, and more particularly, to a dry vacuum pump in which a Roots rotor and a screw rotor are combined.

Recently, such dry vacuum pumps have a roots rotor with at least one lobe and at least one screw rotor for the purpose of maintaining a complete vacuum in the process chamber and reducing the required power costs. ). The Roots-type rotor is connected to the process chamber described above and used to suck and compress the process by-products including gaseous substances generated in the process chamber, and the screw-type rotor is used for the gas and process by-products sucked by the Roots-type rotor. It is used to vent out of one process chamber. In any case, these rotors are operated closed to maintain vacuum in the process chamber.

Typically, partitions are provided between these rooted rotor stages and screwed rotor stages to allow process by-products to move smoothly from the rooted rotor stage to the screwed rotor stage without disturbing the rotation of the rotor. A representative example of such a configuration is disclosed in U.S. Patent No. 5,549,463 to Kashiyama Industry Co., Ltd. (see FIG. 9 below).

According to this patent document, the dry vacuum pump 100 includes a pair of Roots-type rotors 102 and 103 and a pair of screw-type rotors 105 and 106. The pair of Roots-type rotors 102 and 103 and the pair of screw-type rotors 105 and 106 are driven by one drive motor 104. That is, the power generated by the drive motor 104 is a pair of Roots-type rotors (102) 103 and a pair of screw-type rotors (105) by three gears (124, 125, 127). 106 is delivered to all. Between the Roots-type rotors 102 and 103 and the screw-type rotors 105 and 106, process by-products from the process chamber (not shown) as described above are transferred directly to the screw-type rotors 105 and 106. The partition 108 is provided so as not to. This patent is incorporated herein by reference in the present invention.

However, the partition 108 required in the dry vacuum pump 100 disclosed in the above-mentioned US Patent No. 5,549,463 is provided between the Roots-type rotors 102 and 103 and the screw-type rotors 105 and 106, that is, And, because the housing 107 including them to be divided into several, it was a factor to increase the effort and the number of parts to manufacture such a dry vacuum pump 100.

In addition to using the bulkhead, a variable pitch screw has been tried to reduce the power consumption and increase the amount of process by-products compressed in the dry vacuum pump using the screw-type rotor. Effectiveness is estimated to be poor because it requires a larger rotor and pump housing than ever.

In addition, a simple method of directly connecting them without a partition wall provided between the Roots-type rotor and the screw-type rotor was also attempted, but in this case, the cross sections of the Roots-type rotor and the screw-type rotor should be designed in a similar shape in order to increase the gas compression transfer efficiency. did.

However, when the Roots-type rotor and the screw-type rotor are similarly formed, the balance of the Roots-type rotor and the screw-type rotor is adversely affected, causing severe vibration and noise in the vacuum pump.

In addition, the driving motor 200 used in the vacuum pump is composed of a stator 220, a rotor 230, a shaft 240, and a motor case 210, as shown in FIG.

When the conventional vacuum pump configured as described above is operated, the pair of Roots-type rotors 102 and 103 and the pair of screw-type rotors 105 and 106 in the vacuum pump rotate due to the driving of the motor 200. The process by-products are sucked through the suction port 310 of the vacuum pump, and discharged through the discharge port 320 through the inside of the vacuum pump, so that the process chamber of the semiconductor and display manufacturing apparatus is in a vacuum state. At this time, the process by-products when the process by-products sucked due to the rotation of the pair of Roots-type rotors 102 and 103 and the pair of screw-type rotors 105 and 106 are discharged to the outlet 320 through the inside of the vacuum pump A part of is introduced into the drive motor 200. The process by-products introduced in this way may damage the stator coils 220a with a high temperature process gas to shorten the life of the driving motor 200.

Therefore, in the related art, a can 400 is installed between the stator 220 and the rotor 230 to prevent damage to the stator coil 220a by the process by-product flowing from the vacuum pump. The can 400 is roundly welded with a thin plate made of stainless steel or the like to be installed between the stator 220 and the rotor 230 so that process by-products or lubricating oil introduced from the vacuum pump do not damage the stator coil 220a. It was.

However, the can 400 installed between the stator 220 and the rotor 230 has to be installed between the minute gaps between the stator 220 and the rotor 230, so that processing and assembly thereof are difficult.

In addition, since the can installed between the stator 220 and the rotor 230 causes magnetic loss, a lot of power of the motor is consumed, thereby increasing operating costs.

The technical problem of the present invention for solving the above problems is a high gas compression when evacuating the process chamber of the semiconductor and display manufacturing apparatus or when discharging the gaseous substances and / or process by-products generated in the process chamber to the outside The present invention provides a combined dry vacuum pump having a roots rotor and a screw rotor that can maintain the transfer efficiency and maintain the balance between the roots rotor and the screw rotor to prevent vibration and noise generated from the vacuum pump.

In addition, another technical problem of the present invention is to provide a high efficiency vacuum pump motor by protecting the stator coils from various by-products flowing from the vacuum pump.

A housing having an inner accommodating space, one side of which is provided with a suction port, and the other side of which has a discharge port;

First and second root rotors that are accommodated in the inner receiving space of the housing and are installed to be engaged with each other;

First and second screw rotors which are accommodated in the inner receiving space of the housing and are installed to be engaged with each other in close proximity to the first and second root rotors;

First and second transmission shafts installed through a center of the first and second root rotors and the first and second screw rotors;

First and second gears engaged with the first and second transmission shafts; And

And a motor having a coil wound around the stator and a rotor connected to the first transmission shaft to be rotatable inside the stator.

The first and second root rotors each consist of three lobes, and the stator rotor and screw rotor are filled with fillers for protecting the coils from various by-products flowing from the inside of the housing. Provides a combined dry vacuum pump.

Such Roots rotor and screw rotor combined dry vacuum pumps provide high gas compression for evacuating process chambers of semiconductor and display manufacturing equipment or for discharging gaseous materials and / or process by-products generated from process chambers to the outside. Maintains the transfer efficiency, prevents vibration and noise generated in the vacuum pump, and protects the stator coils from process by-products flowing from the vacuum pump, thereby improving the reliability of the motor.

Hereinafter, the Roots rotor and the screw rotor composite dry vacuum pump according to the first embodiment of the present invention having the above characteristics will be described in more detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a Roots rotor and a screw rotor combined dry vacuum pump according to a first preferred embodiment of the present invention, Figure 2 is a longitudinal cross-sectional view of the Roots rotor and screw rotor combined dry vacuum pump shown in FIG. 3 is a perspective view showing the root rotor and the screw rotor of the root rotor and screw rotor composite dry vacuum pump shown in FIG.

1 to 3, the Roots rotor and the screw rotor composite dry vacuum pump according to the first embodiment of the present invention is provided with an inlet 11 on one side, the outlet 12 is provided on the other side In the housing 10 having an inner receiving space and the inner receiving space of the housing 10, the first and second root rotors 31 and 32 and the inner receiving space of the housing 10, which are installed to be engaged with each other, are accommodated. , The first and second screw rotors 41 and 42, the first and second root rotors 31 and 32, and the first and second screw rotors which are installed in close proximity to the first and second root rotors 31 and 32. First and second gears 24 and 26 engaged with and engaged with the first and second transmission shafts 21 and 22 and the first and second transmission shafts 21 and 22 installed through the center of the 41 and 42. And a rotor 56 wound around the coil 54a and connected to the first transmission shaft 21 so as to be rotatable inside the stator 54 and the stator 54 provided in the case 52. It consists ruthless drive motor 50.

Looking at this in more detail as follows.

The housing 10 has a space enclosed therein to make a vacuum, and an inlet 11 is formed at one side of the housing 10 and an outlet 12 is formed at the other side. The air is sucked in the environment to make a vacuum through the inlet 11, and the air is discharged to the outside using the outlet 12. In addition, a predetermined space 13 is formed in the lower housing 10 of the first root rotor 31 and the second root rotor 32 to allow the suction object to remain.

The first and second root rotors 31 are composed of three lobes 31a, 31b, 31c, 32a, 32b, and 32c, respectively, and are accommodated in the inner receiving space of the housing 10. Each of the three lobes 31a, 31b, 31c, 32a, 32b, 32c is engaged with each other and rotates to entrain air and transfer it to the first and second screw rotors 41 and 42. One of the three lobes 31a, 31b, 31c, 32a, 32b, 32c has two lobes 31b, 31c, of different lengths from the center of rotation to the ends of the lobes 31a, 32a. 32b, 32c) shorter than the length. The outer circumferential surfaces of the first and second root rotors 31 and 32 in contact with the short lobes 31a and 32a are formed in a shape that can be closed in contact with the shorter lobes 31a and 32a during rotation. .

That is, the opposite positions of the shortly formed lobes 31a of the first roots rotor 31 come into contact with the shortly formed lobes 32a of the second roots rotor 32 during rotation, and conversely, The opposite position of the shortly formed lobe 32a rotates in contact with the shortly formed lobe 31a of the first roots rotor 31 during rotation.

In the first and second screw rotors 41 and 42, the first screw rotor 41 and the second screw rotor 42 have a pair of shapes, and the two screw rotors 41 and 42 mesh with each other to rotate the first and second screw rotors 41 and 42. By the volume change formed between the grooves of the two screw rotors 41 and 42 and the housing 10, the gas can be continuously sucked, compressed and discharged. In addition, the diameters of the first and second screw rotors 41 and 42 may be thermally expanded by the heat inside the housing 10 so that the first and second screw rotors 41 and 42 rotate by friction with the inside of the housing 10. In consideration of this obstruction, the diameter of the suction port 11 toward the discharge port 12 is shortened.

The transmission shafts 21 and 22 extend through the centers of the first root rotor 31 and the first screw rotor 42, and the first transmission shaft 21 and the second root rotor 32 and the second screw are formed. It consists of a second transmission shaft 22 extending through the center of the rotor 42, the first gear 24 to be rotated in engagement with the first transmission shaft 21 and the second transmission shaft 22. ) And a second gear 26 are formed. The driving motor 50 is installed at one end of the first transmission shaft 21. A plurality of bearings 70 are coupled to both ends of the first and second transmission shafts 21 and 22.

On the other hand, a bearing for supporting the first and second root rotors 31 and 32 and the first and second screw rotors 41 and 42 on the inlet 11 side in which the vacuum and atmospheric pressures can be repeated during pump operation. In (70), the lubricating grease could come out of the bearing 70 due to the pressure difference, which caused the failure of the vacuum pump. Accordingly, the bearing 70 may be coupled only to one end of both ends of the first and second transmission shafts 21 and 22, that is, the ends of the first and second transmission shafts 21 and 22 on the outlet 12 side. have.

The drive motor 50 is a circuit in which a coil 54a is wound and connected to the first transmission shaft 21 so as to be rotatable inside the stator 54 and the stator 54 provided inside the case 52. Including the electrons 56, the stator 54 is filled with a filler for protecting the coil 54a from various by-products flowing from the vacuum pump.

Looking at this in more detail as follows.

In the inner accommodating space of the case 52, a stator 54 having a coil 54a wound thereon and a rotor 56 connected to the first transmission shaft 21 to be rotatable inside the stator 54. The area around the stator coil 54a is filled and filled so that the coil 54a is not exposed to the outside. These fillings are filled and molded to a predetermined length so as not to interfere with the rotation of the rotor 56. An epoxy resin 58 having good chemical resistance and thermal conductivity is used as a filler surrounding the region around the coil 54a.

It should be noted here that, unlike the conventional drive motor 104, the drive motor 50 according to the preferred embodiment of the present invention does not have a can 200 installed between the stator 54 and the rotor 56. to be. As described above, the conventional drive motor 104 is completely isolated and sealed using the can 200 to protect the stator coil 120a from various by-products flowing from the vacuum pump. However, the can 200 is installed between the stator 120 and the rotor 130, and a lot of power of the driving motor 100 is consumed due to the magnetic force loss, and the stator coil 120a flows in from the vacuum pump 300. It was easy to be damaged by exposure to various byproducts. In addition, since there is a need for the can 200 to exist at a precise position between the minute gap between the stator 120 and the rotor 130, there was a manufacturing problem. This requirement has been solved by the present invention. In a preferred embodiment of the present invention, instead of using the can 200, the epoxy resin 58 having excellent chemical resistance and thermal conductivity is filled and molded around the stator coil 54a so that the stator coil 54a is not exposed. It can be isolated and protected from various by-products flowing from the vacuum pump, there is no loss of magnetic force generated between the stator 54 and the rotor 56, the heat generated from the stator coil 54a is excellent in thermal conductivity It is provided by the epoxy resin 58, the motor 50 can be quickly discharged to the outside.

In addition, such a drive motor 50 may be used in a variety of types to suit the desired power, water-cooled motor is used in the Roots rotor and screw rotor composite dry vacuum pump according to a preferred embodiment of the present invention.

In addition, the case 52 is manufactured by welding the seam portion of the case 52 to prevent external air from flowing into the case 52, or installing an O-ring on the seam portion of the case 52, or the case 52. ) Can be cast integrally.

By such a structure, outside air can be prevented from flowing into the case 52, thereby ensuring the airtightness inside the case 52.

In addition, an airtight terminal 90 is installed at one side of the case 52 to prevent external air from flowing into the case 52. The airtight terminal 90 is conventionally provided with external air of the case 210. Although the airtightness was maintained by the can 400 provided inside the case 210 even when introduced into the gap of the electrical terminal 500 installed on one side, in the present invention, since the case 52 plays a role, external air It is preferable that an airtight terminal 90 is installed to prevent flow into the case 52.

In addition, one side of the case 52 is further provided with a control member 95 for controlling the frequency of the motor 50. The control member 95 is provided at one side of the case 52 in order to prevent the heat generated from the control member 95 from being overheated by cooling the control member 95 using the coolant of the motor 50. to be.

In this way, by filling and molding the area around the stator coil 54a of the motor 50 with the epoxy resin 58, the stator coil 54a is protected from various by-products flowing from the vacuum pump to provide a highly efficient motor 50. It will be possible.

Referring to the suction, compression and discharge process of the Roots rotor and screw rotor composite dry vacuum pump having the structure as described above are as follows.

First, as shown in FIGS. 2 and 4, when the driving motor 50 is driven, the first transmission shaft 21 coupled to the driving motor 50 rotates, together with the first transmission shaft ( The second gear 26 engaged with the first gear 24 of 21 rotates so that the first and second root rotors 31 and 32 and the first and second screw rotors 41 and 42 rotate. When the first and second root rotors 31 and 32 are rotated, the first and second root rotors 31 and 32 are engaged with each other and rotate to suck and compress air through the inlet 11, and then the first and second root rotors 31 and 32 are rotated. 2 is discharged to the outlet 12 through the screw rotors (41, 42).

That is, when the first and second root rotors 31 and 32 and the first and second screw rotors 41 and 42 rotate one rotation, one of the three lobes 31a, 31b, 31c, 32a, 32b, and 32c is used. The lobes 31a and 32a are formed to be short so that the first and second root rotors 31 and 32 compress the inhaled air twice and are transferred to the first and second screw rotors 41 and 42 and the first and second screws The air transferred to the rotors 41 and 42 is distributed through the first and second screw rotors 41 and 42, respectively, and discharged to the discharge port 12.

Accordingly, the suction, compression, and discharge strokes are carried out at one time when the first and second root rotors 31 and 32 and the first and second screw rotors 41 and 42 are rotated in one rotation, so that the suction gas is continuously transferred. The balance of the first and second root rotors 31 and 32 and the first and second screw rotors 41 and 42 may be maintained to prevent vibration and noise generated in the vacuum pump.

That is, the first and second root rotors 31 and 32 may be balanced with the first and second screw rotors 41 and 42 while maintaining a similar shape to maintain a high gas compression transfer efficiency. The two root rotors 31 and 32 are designed with three lobes 31a, 31b, 31c, 32a, 32b, and 32c, respectively, to prevent vibration and noise generated from the vacuum pump. And adjusting the length of one lobe 31a, 32a of the three lobes 31a, 31b, 31c, 32a, 32b, and 32c of the first and second root rotors 31 and 32. Suction occurs during the gas transfer from the Roots rotors 31 and 32 to the screw rotors 41 and 42 before adjusting the length by allowing suction and discharge to proceed continuously from the 32 to the first and second screw rotors 41 and 42. The interruption of internal fluid flow was eliminated to minimize vibration and noise. Further, by reducing the contact area between the outer diameters of the first and second root rotors 31 and 32 and the inner diameter of the housing 10, the life of the vacuum pump is extended by reducing wear caused by friction.

Figure 5 is a cross-sectional view showing a Roots rotor and a screw rotor combined dry vacuum pump according to a second preferred embodiment of the present invention, Figure 6 is a schematic of the Roots rotor and screw rotor combined dry vacuum pump shown in FIG. Phosphorus longitudinal cross section is shown.

5 and 6, the Roots rotor and the screw rotor composite dry vacuum pump according to the second preferred embodiment of the present invention, the first and second roots on one side of the first and second roots rotors 31 and 32. Its length is longer than the rotors 31 and 32, and the third and fourth root rotors 61 and 62 are formed so that a plurality of lobes are paired, and the first and second root rotors 31 and 32 and the first and second root rotors 31 and 32 are combined. It is the same as the first embodiment except that the partition wall 80 having the inflow hole 82 is formed between the three and four root rotors 61 and 62.

Roots and screw rotors combined dry vacuum pump having a structure such as this is the length of the third, fourth root rotors (61, 62) is formed longer than the length of the first, second root rotors (31, 32) third, fourth As the volume of the inside of the housing 10 in which the Roots rotors 61 and 62 are accommodated increases, the amount of air sucked increases, thereby increasing the amount of transport and discharge, thereby rapidly creating an environment requiring a vacuum state.

Figure 7 is a perspective view showing a Roots rotor and a screw rotor composite dry vacuum pump according to a third embodiment of the present invention, Figure 8 is a cross-sectional view of the Roots rotor and screw rotor composite dry vacuum pump shown in FIG. Is shown.

As shown in Figure 7 and 8, the Roots rotor and the screw rotor composite dry vacuum pump according to the third embodiment of the present invention is the third, fourth screw on one side of the first, second root rotors (31, 32) The rotors 43 and 44 are further provided, and the discharge port 16 is further provided in the lower portion of the housing 10 of the third and fourth screw rotors 43 and 44 as in the first embodiment.

Roots rotor and screw rotor combined dry vacuum pump having such a structure is a gaseous substance and / or process by-products generated in the process chamber is sucked to the first, second root rotors (31, 32) side, Substances and / or process by-products are conveyed through the first, second, third and fourth screw rotors 41, 42, 43 and 44 provided on both sides of the first and second root rotors 31 and 32, respectively. By discharging to 12, 16, the amount of conveying and discharging can be increased to quickly create an environment requiring a vacuum state.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously change and modify the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated.

As mentioned above, the Roots rotor and the screw rotor composite dry vacuum pump according to the present invention are used to evacuate process chambers of semiconductor and display manufacturing apparatuses or to remove gaseous substances and / or process by-products generated in process chambers. It is possible to prevent high vibration and noise generated from the vacuum pump by maintaining a high gas compression transfer efficiency during the discharge of the furnace, and to maintain the balance between the Roots rotor and the screw rotor, and to isolate and protect the stator coils from various by-products flowing from the vacuum pump. By filling the filling to be filled, there is no difficulty in manufacturing due to the difficulty of processing, it is possible to prevent the power loss of the motor to provide a high efficiency of the motor.

Claims (17)

A housing having an internal working space and having a suction port at one side and a discharge port at the other side; First and second root rotors that are accommodated in the inner accommodating space of the housing and are installed to be engaged with each other;   First and second screw rotors which are accommodated in the inner receiving space of the housing and are installed to be engaged with each other in close proximity to the first and second root rotors;   First and second transmission shafts installed through a center of the first and second root rotors and the first and second screw rotors;   First and second gears engaged with the first and second transmission shafts; And a motor having a coil wound around the rotor and a rotor connected to the first transmission shaft to be rotatable inside the stator. The first and second root rotors are each composed of three lobes, and the stator is filled with a filler for protecting the coil from various by-products flowing from the inside of the housing, and any one of the three lobes The lobe is formed shorter than the length of each of the two lobes from the center of rotation to the end of the lobe, and the outer circumferential surface of the first and second roots rotors contacting the shorter lobes is characterized in that Roots rotor and screw rotor composite dry vacuum pump, characterized in that formed in a shape that can be closed in contact. delete delete The third and fourth root rotors of claim 1, wherein a length of the first and second root rotors is longer than that of the first and second root rotors and a plurality of lobes are paired with each other. Roots and screw rotors combined dry vacuum pump, characterized in that the partition wall is formed between the first and the second roots rotor and the third and fourth roots rotor formed inlet hole. delete According to claim 1, wherein the first and second root rotor, one side of the third and fourth screw rotor is further provided, the lower side of the third and fourth screw rotor is characterized in that the discharge port is further provided. Roots and screw rotors combined dry vacuum pump. The roots rotor and the screw rotor according to any one of claims 1, 4 and 6, wherein the first and second screw rotors are formed to have shorter diameters from the inlet side to the outlet side. Combined dry vacuum pump. 8. The roots rotor and screw rotor composite dry vacuum pump according to claim 7, wherein a lower portion of the roots rotor is provided with a space in which the material to be sucked can remain. The Roots rotor and screw rotor composite dry vacuum pump according to any one of claims 1, 4 and 6, wherein a space in which the material to be sucked is left is formed under the roots rotor. The bearing of any one of claims 1, 4, and 6, wherein only one end of the first and second transmission shafts includes a plurality of bearings for smoothly rotating the first and second transmission shafts. Roots rotor and screw rotor composite dry vacuum pump, characterized in that. 7. The Roots rotor and screw rotor composite dry vacuum pump according to any one of claims 1, 4 and 6, wherein the filler is an epoxy resin. 12. The roots rotor and screw rotor combined dry vacuum pump according to claim 11, wherein an airtight terminal is installed at one side of the case to prevent external air from flowing into the case. 13. The roots rotor and screw rotor composite dry vacuum pump according to claim 12, wherein the case is provided with a gastight means to prevent external air from flowing into the case. 14. The roots rotor and screw rotor composite dry vacuum pump according to claim 13, wherein the airtight means is formed of the case. 14. The roots rotor and the screw rotor composite dry vacuum pump according to claim 13, wherein the airtight means is welded at the joint of the case. 14. The roots rotor and screw rotor composite dry vacuum pump according to claim 13, wherein the airtight means is provided with an O-ring at the joint portion of the case. 14. The roots rotor and screw rotor composite dry vacuum pump according to claim 13, wherein one side of the case is further provided with a control member for controlling the frequency of the motor.

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