KR20160029453A - Two stages type's dry vacuum pump - Google Patents

Abstract

The present invention provides a two stage type dry vacuum pump, which can obtain the degree of a vacuum in a high-degree vacuum area, wherein an exhaust speed is greater compared to a conventional pump at low pressure, and achievement of a high-degree vacuum is possible with only a two stage cylinder structure for a route of a vented process gas not to be complex and long, thereby maximizing a transportation speed of gas passing through the inside of the pump. To achieve this, according to the present invention, the two stage type dry vacuum pump comprises: a pump body cylinder; a first stage cylinder and a second stage cylinder; a pair of roots-type rotors; a pair of screw type rotors; a motor; a pair of gears; a first stage suction path; an exhaust transfer path; a first stage exhaust path; a second stage exhaust path; a first stage exhaust valve; a second stage exhaust valve; and a cooling water jacket.

Description

[0001] The present invention relates to a two-stage type dry vacuum pump,

The present invention relates to a vacuum pump, and more particularly, to a vacuum pump having two cylinders in which a roots-type rotor and a screw-type rotor are combined in a different manner, so that the structure is simple, To a vacuum pump.

Generally, a vacuum pump is a device that removes gas molecules in an airtight container. It is used to suck gas at low pressure below atmospheric pressure, compress it, and release it into the atmosphere to increase the degree of vacuum in the container. These vacuum pumps are largely divided into mechanical vacuum pumps and diffusion pumps, which are represented by dry and wet respectively. Unlike the wet type, in which the diffusion pump uses oil to realize high vacuum, the mechanical vacuum pump has a relatively low degree of vacuum, but it is a dry type that does not use oil. Therefore, the structure is relatively simple, durable and has a stable degree of vacuum It is widely used in various industrial fields because it is easy to operate by the user and the cost to maintain is low.

As a result, the progress of vacuum technology has been remarkably accelerated in recent years, and its application fields are spreading to semiconductor deposition, electronic industry, metal, chemical, medicine, and nuclear industry.

In addition, there are many types of vacuum pumps that produce vacuum, such as a water pump type, an oil type pump type, a Lutz type, a liquid diffusion type, a physical absorption type, and a chemical absorption type, but they can be largely divided into a wet type and a dry type. However, wetting (pouring water or oil into a vacuum pump) such as a water-podding type or an oil-rotating type has not been used in industrial fields such as semiconductor, food, chemical, and pharmaceutical industry which have no suction of impurities, Vacuum pumps of the type that do not inject water or oil in the pump have been widely used. In particular, in order to prevent oil molecules from leaking into the process chamber in the semiconductor manufacturing process, a non-oil dry vacuum pump has been adopted have.

However, in the case of the volumetric dry vacuum pump, it is difficult to use only one pump to suck gas for high vacuum of 1 x 10 ^-3 Torr or less. Therefore, in order to increase the discharge efficiency of the gas, A roots-type multi-stage dry vacuum pump, a screw dry vacuum pump or a claw dry vacuum pump are widely used in order to achieve high vacuum by connecting the pump in series or multi-stage.

1. Roots type multistage dry vacuum pump

For the pump's reaching pressure to operate up to 10 ^-3 Torr at atmospheric pressure, the compression ratio should be about 100,000: 1. To make this compression ratio, a large number of cylinders are required, usually five or six stages. As the number of cylinders increases, the structure of the pump becomes complicated, the length of the shaft becomes longer, and the size of the pump naturally increases. When the shaft is long, the shaft rotates and the shaft rotates. As a result of the temperature rise of the pump, the expansion / contraction occurs. In the cylinder, there is interference between rotor and rotor gap, rotor and cylinder gap, Sudden stopping problems often arise.

In addition, since the working process gas sucked through the suction port of the pump has to be exhausted through a multi-stage, for example, a six-stage cylinder, the problem of a long gas flow and a large maintenance are required.

In addition, since many stages (cylinders) need to be assembled, the parts must be precisely machined, a skilled engineer must perform the assembly of the pump, and a precise assembly technique is required, which takes a lot of time. The problem of sudden stopping often occurs.

On the other hand, in the case of a six-stage cylinder for obtaining a high vacuum, mounting the six stages on one shaft requires precise technology. Therefore, two pumps of three stages are usually used and connected in series to increase the overall size of the pump , The cost of the two pumps is required, and the cost of the pump is increased. Thus, the flow path of the process gas sucked through the suction port becomes longer and the maintenance cost becomes higher.

2. Screw type dry vacuum pump

The pump's reaching pressure is often used in processes ranging from atmospheric pressure up to 10 ^-2 Torr and requires a lot of energy to compress the process gas through multiple rows of screw rotors in a single cylinder and thus consumes a lot of power. Compared to the Roots method, it can rotate about 3 times faster to achieve almost the same performance. There is a high possibility that leakage occurs at the sealing portion of the shaft portion, and there arises a problem of bearing lubrication and noise.

There is a problem that when the process gas is compressed, heat is generated to overheat and the stagnation occurs in the gap between the rotor and the rotor to suddenly stop the pump, and when the gap is increased to solve the problem, the pump performance is deteriorated.

3. Claw dry vacuum pump

Claude Dry Vacuum Pumps are widely used in the working process of the pump up to 10 ^-2 Torr from the atmospheric pressure, usually requiring 4 stages of cylinders. Also, the exhaust speed is relatively smaller than that of a conventional Roots-type dry pump because the inlet conductance is small.

Since the Claw itself acts as a valve, the intake port is gradually opened slowly and then gradually closed, resulting in a low conductance. On the other hand, the roots-type dry vacuum pump has a relatively large conductance, .

The vacuum pump is disadvantageous in that the gas path of each cylinder stage (interstage) is long because the pump structure is such that the claw rotors are all directed in the same direction and the gas is exhausted from the first stage cylinder exhaust to the second stage cylinder intake.

Korean Patent Registration No. 10-1385954

It is an object of the present invention to solve the problems of the conventional dry vacuum pumps described above, and it is an object of the present invention to provide a vacuum pump which can obtain a vacuum degree in a high vacuum region, Cylinder type vacuum pump capable of achieving a high vacuum only by a simple structure of the cylinder, so that the path of the exhausted process gas is not complicated and is not long, so that the transportation speed of the gas passing through the pump can be maximized.

In order to achieve the above object, a two-stage dry vacuum pump according to the present invention includes a pump body cylinder having an internal space, a suction port on one side, and an exhaust port on the other side; A first-stage cylinder and a second-stage cylinder which form an internal accommodation space of the pump body cylinder; A pair of roots-shaped rotors which are arranged to rotate in opposite directions in synchronism with each other on a pump shaft passing through the first-stage cylinder, two pump shafts arranged in parallel through the first-stage and second-stage cylinders; A pair of screw-type rotors provided on the pump shaft passing through the two-stage cylinder so as to be engaged with each other and to rotate in the opposite direction; A motor for rotationally driving any of the pump shafts; A pair of gears meshed with each other on the pump shaft so that the two pump shafts rotate together; A first-stage suction passage connecting the suction port and the first-stage cylinder; An exhaust conveyance passage connecting the first stage cylinder and the second stage cylinder; A first stage exhaust passage connecting the exhaust gas passage and the exhaust port; A two-stage exhaust passage connecting the rear end of the two-stage cylinder to the exhaust port; A first stage exhaust valve opened and closed by a gas pressure exhausted through the first stage exhaust passage; A two-stage exhaust valve opened and closed by a gas pressure exhausted through the two-stage exhaust passage; And a cooling water jacket through which cooling water is circulated to cool at least the two-stage cylinder and the bearing support portion of the pump shaft.

According to a preferred embodiment of the present invention, the first-stage and second-stage exhaust valves are lifted from the valve seat by a gas pressure discharged by a predetermined pressure or more, and are brought into close contact with the valve seat by their own weight And is a metal ball.

According to a preferred embodiment of the present invention, the one-stage exhaust passage and the two-stage exhaust passage are integrated into one through a connection space in contact with the exhaust port.

In the present invention as described above, the structure of the dry vacuum pump is designed to have a two-stage structure, a roots type rotor is used for the first stage cylinder, and a screw type rotor is used for the second stage cylinder. (10 ^-3 to 10 ^-8 Torr) can be obtained by removing the residual gas that has not been exhausted in the process of exhausting by the car in the step of sucking, compressing and secondary exhausting the two-stage cylinder, (1 ~ 10 ^-3 Torr), and the pressure of these pumps is in the range of 1 ~ 10 ^-3 Torr). As a result, even in a low-vacuum working process in which a large amount of exhaust gas is continuously discharged, The present invention solves the problem caused by overheating of the pump by solving the overpressure of the compressed gas at the primary exhaust valve connected to the exhaust passage, Structural design with the pump structure is simple, and the effect of cost reductions in non-material, processing costs, assembly costs.

1 is a front sectional view of a two-stage dry vacuum pump according to the present invention.
FIG. 2 is a AA flat cross-sectional view of a two-stage dry vacuum pump according to the present invention.
3 is a cross-sectional view of the two-stage dry vacuum pump according to the present invention on the BB side.
4 is a CC side sectional view of a two-stage dry vacuum pump according to the present invention.
5 is a DD side sectional view of a two-stage dry vacuum pump according to the present invention.

The present invention can be further specified by the following embodiments. Such embodiments are provided for illustrative purposes to those skilled in the art and are not intended to limit the scope of the invention described in the claims. Accordingly, the invention is not to be interpreted as being limited to the embodiments described, but includes some and all modifications which are obvious as the result of the disclosure herein.

Hereinafter, a two-stage dry vacuum pump of the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings.

As shown in Figs. 1 to 2 or 5, the vacuum pump apparatus of the present invention includes a pump body cylinder 1 forming a main body of the apparatus. On the upper side of the pump body cylinder 1, A top cover 12 having a suction port 15 and an exhaust port 21 is mounted on the other side and a receiving space of the inside has a first stage cylinder 2 and a second stage Two pump shafts 4 and 5 are arranged side by side horizontally through the peanut-shaped space of the first-stage cylinder 2 and the second-stage cylinder 3, One of the two pump shafts 4 and 5 is a drive shaft 4 to which the motor 34 is mounted and the other one of the pump shafts 4 and 5 forms a driven shaft 5 that is rotationally driven in the opposite direction in conjunction therewith do.

A pair of roots type rotors 6 and 7 are provided so as to be synchronized with each other and rotate in the opposite direction to the pump shafts 4 and 5 passing through the first stage cylinder 2, 3 and a pair of screw-type rotors 8, 9 for synchronizing with each other and rotating in the opposite direction.

One end of the pump shaft 4 (drive shaft) 5 (driven shaft) is connected to the motor side surface 5a via the bearing 30, The drive shaft 4 is supported by a motor shaft 34 via a coupling 32 and 33 provided in a motor flange housing 14 supported by a plate 13 and connected to one side of the side plate 13. [ And the other end of the pump shaft 4 or 5 is supported via a bearing 29 on a gear side plate 11 forming a side wall of the second stage cylinder 3, A pair of gears 26 and 27 are mounted on an end of the gear 11 that has passed through the plate 11 and are fitted with a main shaft gear 26 and a driven shaft gear 27 of the same size, And is protected by the gear casing 10 connected to the side surface of the plate 11 so as not to be exposed to the outside.

And a first suction passage 16 for connecting the suction port 15 and the first-stage cylinder 2 so as to communicate with each other is formed in the lower portion of the first-stage cylinder 2, And the exhaust gas transfer passage 17 is connected to the second stage cylinder 3 through the second stage cylinder intake port 22. The exhaust gas transfer passage 17 is connected to the exhaust gas transfer passage 17, 17 and the exhaust port 21 are connected to each other through a single-stage exhaust passage 18.

A two-stage exhaust passage 23 is formed through the gear side plate 11 to connect the rear end of the two-stage cylinder 3 and the exhaust port 21, and the two- Stage exhaust valve 19 is connected to the two-stage exhaust passage 24 formed in the pump body cylinder 1 by the gas pressure exhausted through the one-stage exhaust passage 18, Stage exhaust valve 25 which is provided at the end of the one-stage exhaust passage 18 and which is opened and closed by the gas pressure exhausted through the two-stage exhaust passages 23 and 24 in the same manner, So as to open and close the valve seat 25b.

The exhaust valves 19 and 25 are spherical metal balls having their own weights. When the exhaust gas flowing through the exhaust conveyance passage 17 exceeds a designed predetermined pressure, the exhaust valves 19 and 25 pass through the first stage exhaust passage 18, The load exerted on the exhaust valve 19 becomes larger than the self weight of the metal ball so that the one-stage exhaust valve 19 is lifted away from the valve seat 19a. When this state is released, The exhaust gas is partially exhausted to the outside through the exhaust port 21 and the exhaust gas exhausted from the two-stage cylinder 3 through the two-stage exhaust passages 23 and 24 is likewise exhausted to its exhaust pressure The two-stage exhaust valve 25 is opened.

In order to cool the heat generated in the bearings 29 and 30 and the two-stage cylinder 3 exhausted through the gear side plate 11, the two-stage cylinder 3 and the motor side plate 13 The cooling water jackets 35, 36 and 37 are formed to prevent the cooling water fed from a pump (not shown) from being circulated to prevent overheating. In the present invention, the cooling water jacket is not formed in the first- In the first stage cylinder 2, since the cold gas coming from the vacuum system flows into the second stage cylinder 3, there is no fear of overheating. In the second stage cylinder 3 having a high compression ratio, (2) is thermally balanced with the first stage cylinder (2) by the cooling of the second stage cylinder (3), so that the equilibrium of the whole device is distorted by the uneven thermal load, Without this do.

The one-stage exhaust passage 18 and the two-stage exhaust passage 24 are integrated into one through a connection space 20 which is in contact with the exhaust port 21.

Reference numerals 28 and 31 denote bearing covers, and reference numerals 38 and 39 denote sealing members which block the exhaust gas from leaking along the pump shafts 4 and 5.

The operation of the present invention will be described below.

When the motor 34 is driven while the intake port 15 is connected to a vacuum system not shown, the main shaft 4 rotates and the rotation of the main shaft 4 is transmitted to the pair of gears 26 The pair of roots rotors 6 and 7, which rotate in the interlocking manner as shown in FIG. 3, start to rotate in conjunction with the rotation of the driven shaft 5 in the opposite direction The gas is sucked from the vacuum equipment into the first stage cylinder 2 and is pushed toward the exhaust side, that is, the lower side while gradually compressing as the rotation. In this initial low vacuum state, the suction amount (i.e., the displacement amount) .

An exhaust conveyance passage 17 connected to the second stage cylinder 3 is formed on the lower side of the first stage cylinder 2 to push the gas toward the second stage cylinder 3 side through the exhaust conveyance passage 17 .

At this time, since a large amount of gas is exhausted at a predetermined pressure or more, that is, at the initial stage of the discharge, the first stage exhaust valve 19 is opened, Stage exhaust passage 18 and the exhaust port 21, and a part of the gas whose pressure has been reduced flows into the second-stage cylinder 3 through the second-stage cylinder inlet 22.

The gas introduced into the two-stage cylinder 3 flows into the screw-type rotor 8, and the gas is introduced into the two-stage cylinder 3, The compressed gas is pushed up through the two-stage exhaust passages 23 and 24 and the two-stage exhaust valve 25 is pushed up through the two passages 23 and 24, So that the compressed gas is discharged to the outside through the exhaust port 21.

The two-stage dry vacuum pump is a process that sucks, compresses, and exhausts the residual gas from the first-stage cylinder in a two-stage cylinder. The two-stage dry vacuum pump is a pump having a structure for obtaining high vacuum (10 ^-3 to 10 ^-8 Torr) In more detail, the dry vacuum pump has a two-stage structure, and the residual gas that has not been exhausted in the process of suction, compression, and exhaustion in the first stage cylinder is removed by suction, compression and exhaust in a two- In this case, the first stage is constituted by a Roots type rotor, and the second stage is constituted by a screw type rotor. Thus, the vacuum performance can be remarkably improved through the combination of advantages of each type. It is meaningful. In other words, in a low-vacuum work process with a large amount of exhaust continuously, the overpressure of the compressed gas is solved at the primary exhaust valve connected to the exhaust passage of the first-stage cylinder, thereby solving the problem caused by the overheating problem of the pump. , It is possible to obtain a high vacuum by removing the residual gas which has not been exhausted in the process of compression and exhaust in a process of sucking, compressing and exhausting in a two-stage cylinder, so that it is possible to obtain high vacuum, In the vacuum working process, the working process gas sucked through the inlet of the first-stage cylinder moves to the exhaust port by rotation of the Roots-type rotor, and the compressed gas is mostly exhausted by opening the first exhaust valve. As the vacuum working process proceeds The amount of gas sucked through the intake port is reduced, and the exhaust gas is exhausted through the exhaust valve of the first-stage cylinder Seuryang also reduced eventually that prevents any work done in the first-stage exhaust gas residual in the cylinder to the primary exhaust valve while the displacement line.

As a result, the pump structure is simple, and the cost is reduced in terms of material ratio, processing cost, and assembly cost by designing a simple structure having one cylinder and two cylinders in one pump body.

It will be apparent to those skilled in the art that various modifications and equivalent arrangements may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, it is to be understood that the present invention is not limited to the above-described embodiments. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims. It is also to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

1: Pump body cylinder 2: Single cylinder
3: second stage cylinder 4:
5: Slave shaft 6: Single stage rotor
7: Single stage rotor 8: Two stage screw rotor
9: Two-stage screw rotor 10: Gear casing
11: gear side plate 12: top cover
13: motor side plate 14: motor flange housing
15: Suction port 16: First suction path
17: exhaust gas passage 18: one stage exhaust passage
19: First stage exhaust valve 20: Exhaust connection space
21: Exhaust port 22: Two-stage cylinder inlet
23: Two stage exhaust system 24: Two stage exhaust system
25: Two-stage exhaust valve 26: Main shaft gear
27: follower shaft gear 28: bearing cover
29: Bearings 30: Bearings
31: bearing cover 32: pump coupling
33: motor coupling 34: motor
35: Cooling water jacket 36: Cooling water jacket
37: cooling water jacket 38: seal member
39: Seal member

Claims (3)

A pump body cylinder having an internal accommodation space, having a suction port on one side and an exhaust port on the other side; A first-stage cylinder and a second-stage cylinder which form an internal accommodation space of the pump body cylinder; A pair of roots-shaped rotors which are arranged to rotate in opposite directions in synchronism with each other on a pump shaft passing through the first-stage cylinder, two pump shafts arranged in parallel through the first-stage and second-stage cylinders; A pair of screw-type rotors provided on the pump shaft passing through the two-stage cylinder so as to be engaged with each other and to rotate in the opposite direction; A motor for rotationally driving any of the pump shafts; A pair of gears meshed with each other on the pump shaft so that the two pump shafts rotate together; A first-stage suction passage connecting the suction port and the first-stage cylinder; An exhaust conveyance passage connecting the first stage cylinder and the second stage cylinder; A first stage exhaust passage connecting the exhaust gas passage and the exhaust port; A two-stage exhaust passage connecting the rear end of the two-stage cylinder to the exhaust port; A first stage exhaust valve opened and closed by a gas pressure exhausted through the first stage exhaust passage; A two-stage exhaust valve opened and closed by a gas pressure exhausted through the two-stage exhaust passage; And a cooling water jacket through which cooling water circulates to cool at least the two-stage cylinder and the bearing support portion of the pump shaft. The exhaust gas recirculation device according to claim 1, wherein the first and second exhaust valves are opened by a gas pressure discharged from the valve seat by a predetermined pressure or more, and when the exhaust gas pressure is constant or lower, Wherein the vacuum pump is a two-stage dry vacuum pump. 3. The two-stage dry vacuum pump according to claim 1 or 2, wherein the one-stage exhaust passage and the two-stage exhaust passage are integrated through a connection space in contact with the exhaust port.

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