KR20130125703A - Screw vacuum pump - Google Patents

Abstract

Providing a screw vacuum pump that achieves miniaturization of the pump dimensions in the longitudinal direction of the rotation axis and ensures design freedom of the pump component members. The male rotor 110, the female rotor 120, the stator 130, and the drive motor 140 are provided, and the screw gear portion 111 of the male rotor 110 and the screw gear portion of the female rotor 120 ( 121 and the stator 130 cooperate to form a gas working chamber, and the stator 130 has an inlet port 134 and an exhaust port 135, and at least one of the male rotor 110 and the female rotor 120 is The rotor hollows 112 and 122 are opened at at least one end surface side in the longitudinal direction of the rotational axis of the male rotor 110 and / or the female rotor 120, and at least a part of the drive motor 140 has the rotor hollow portion 112. Screw vacuum pump 100 housed in 122).

Description

Screw Vacuum Pump {SCREW VACUUM PUMP}

The present invention relates to a screw vacuum pump.

In general, in the semiconductor device manufacturing apparatus, the liquid crystal panel manufacturing apparatus, and the solar panel manufacturing apparatus, when there is an oil backflow from the pump in the process chamber of the device manufacturing apparatus, it causes a serious problem in each device manufacturing process. So-called dry pumps, mechanical booster pumps, and turbomolecular pumps are used which are free from oil contact.

However, since the molecular weights of the process gas, the carrier gas, and the generated gas range from 1 to hundreds of dozens, the current situation is that the use is classified according to the exhaust characteristics of the various gases of the pump and the exhaust region inherent to the pump.

On the other hand, since the exhaust speed decreases depending on the type of exhaust gas, since a pump having a large exhaust speed is used in a state of poor efficiency, the problem that the power consumption is reduced and the pump size is large cannot be installed near the apparatus. have.

Moreover, the general dry pump and mechanical booster pump have a big problem that a product accumulates inside the pump between an intake port and an exhaust port, and maintenance time is short.

In this regard, the screw vacuum pump can be used in the range of atmospheric pressure to 0.5 Pa, and the pressure in the pump is characterized in that it can suppress the sudden rise in the vicinity of the exhaust port, suppress the abnormal heat generation, and reduce the power consumption. In addition, even if a large amount of product is generated, each screw tooth surface can be scraped out of the pump.

Conventionally, the screw vacuum pump of patent document 1 is known as such a screw vacuum pump.

Such a conventional screw vacuum pump includes a male rotor and a female rotor engaged with each other, a stator for accommodating the male rotor and a female rotor, a first shaft and a second shaft serving as a rotation axis of the male rotor and the female rotor, and a first shaft. And a bearing bearing for bearing the shaft and the second shaft, and a drive motor for rotationally driving the first shaft and the second shaft.

The bearing and drive motor are arranged outside of the male rotor or the female rotor, ie the male rotor or the female rotor and the bearing and the drive motor are arranged in parallel in the longitudinal direction of the axis of rotation.

Japanese Unexamined Patent Publication No. 2004-263629

By the way, in the conventional screw vacuum pump, since the male rotor or the female rotor, the receiving bearing, and the drive motor are arranged in parallel in the longitudinal direction of the rotation shaft, there is a problem that the pump dimensions in the longitudinal direction of the rotation shaft become large.

In addition, although drive heat is generated from the drive motor when the pump is driven, the peripheral member and the peripheral device of the drive motor must be designed in consideration of the influence of the drive heat of the drive motor, and as a result, the freedom of design of the pump component member is impaired. There was.

Thus, the present invention solves the conventional problem, that is, the object of the present invention is to achieve miniaturization of the pump dimensions in the longitudinal direction of the rotation axis.

Moreover, another object of this invention is to provide the screw vacuum pump which ensures the design freedom of a pump structural member.

The screw vacuum pump according to the present invention includes a male rotor and a female rotor having screw gears engaged with each other on the outer circumferential side, a stator for accommodating the male rotor and a female rotor, and a drive motor for rotationally driving the male rotor and the female rotor. And the screw gear portion of the male rotor and the screw gear portion of the male rotor and the stator cooperate to form a gas working chamber, and the stator has an inlet and an exhaust port communicating with one end and the other end of the gas working chamber, Either or both of the male rotor and the female rotor have a rotor hollow portion opened at least at one end face side in the longitudinal direction of the rotational axis of the male rotor and / or the female rotor, and at least a part of the drive motor is housed in the rotor hollow portion. By doing so, the above problems are solved. In addition, if a hollow portion is formed in both the male and female rotors and the motors are accommodated in each hollow portion (that is, two motors), the heat rise due to the heat generation of the motor becomes uniform in the male and female rotors. Although the thermal expansion is the same, the uniformity of the engagement gaps is also maintained, but the hollow portion is formed in either the male rotor or the female rotor and the motor is housed in the hollow portion (ie, one motor). This reduces the cost of the motor while minimizing the size of the pump, increasing the freedom of installation of the exhaust system.

According to the present invention, by storing at least a part of the drive motor in the rotor hollow portion, it is possible to reduce the size of the pump in the longitudinal direction of the rotation shaft. In addition, since most of the drive heat of the drive motor is kept inside the male rotor and / or the female rotor, the influence of the drive heat of the drive motor on the pump component members other than the male rotor and the female rotor can be reduced. A high degree of design freedom can be realized.

1 is a plan view schematically showing a screw vacuum pump as a first embodiment of the present invention.
2 is an explanatory diagram conceptually illustrating a circulation path of lubricating oil.
3 is a perspective view of the male rotor;
It is explanatory drawing which shows typically the screw gear part of a male rotor and a female rotor.
5 is an axially perpendicular cross-sectional view of the male rotor and female rotor.
Fig. 6 is a plan view schematically showing a screw vacuum pump as a second embodiment of the present invention.
It is a perspective view which shows the male rotor of the screw vacuum pump which is a modification of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment

First, as shown in Figs. 1 and 2, the screw vacuum pump 100 according to the first embodiment of the present invention is arranged in engagement with each other while maintaining the engagement gap and synchronized in the reverse direction (synchronized by an inverter not shown). A pair of male and female rotors 110 and female rotors 120 driven, a stator 130 for housing the male rotors 110 and female rotors 120, and a male rotor 110 or a female rotor 120. ), Which drives the drive motors 140A and 140B for rotationally driving, the rotary shafts (rotary shafts) 150A and 150B fixed to the male rotor 110 or the female rotor 120, and the rotary shafts 150A and 150B. Bearing bearings 160Aa, 160Ab, 160Ac, 160Ba, 160Bb, 160Bc and a pair of gears 170A, 170B attached to one end of the rotary shafts 150A, 150B (prevents contact between male and female screw rotors in the event of an abnormality). In particular, vibration and noise caused by backlash of gears are applied during rotation start and end. And oil supply means 180 for supplying lubricating oil to each of the constituent members described later by centrifugal force by using the rotation of the rotary shafts 150A and 150B, and a cooling device 190 for cooling the lubricating oil by water cooling. ).

The male rotor 110, the female rotor 120, and the stator 130 cooperate to form a gas working chamber for conveying and compressing gas.

The male rotor 110 and the female rotor 120 have screw gear portions 111 and 121 engaged with each other on the outer circumferential side while maintaining the engagement gap as shown in FIGS. 1, 3, and 4, respectively.

The screw gear parts 111 and 121 of these male rotor 110 and the female rotor 120 are arrange | positioned at the inlet port 134 side as shown to FIG. 1, FIG. 3, FIG. Each of the uneven inclination angle screw portions 111a and 121a and the uneven inclination inclination angle screw portions 111a and 121a and the back lead screw portions 111b and 121b of a single lead or a plurality of leads that transfer gas are provided.

Uneven Lead Uneven Inclined Angle Screws 111a and 121a change the root lead angle in accordance with the rotation angles of the male rotor 110 and the female rotor 120, and the male rotor 110 and the female rotor 120. ), And the volume of the V-shaped gas working chamber formed by the stator 130 changes and becomes small, and conveyance compression is performed to compress and evacuate in the vicinity of the exhaust port 135.

Differential Lead The uneven inclination-angle screw portions 111a and 121a perform transfer compression exhaust, so that the temperatures of the male rotor 110 and the female rotor 120 become uniform.

The male rotor 110 and the female rotor 120 are opened at both end surfaces of the male rotor 110 and / or the female rotor 120 in the longitudinal direction of the rotation shaft, that is, as shown in Figs. And the rotor hollow portions 112 and 122 penetrating in the longitudinal direction of the rotation shaft.

The rotor hollow sections 112 and 122 have a circular cross-sectional shape in the axial square.

As shown in FIG. 1, the stator 130 is fixed to the stator main body 131 for accommodating the male rotor 110 and the female rotor 120, and the stator 130 to drive motors 140A and 140B and bearing bearings. A first support part 132 supporting 160Aa, 160Ab, 160Ba, 160Bb, a second support part 133 fixed to the stator 130, and supporting bearing bearings 160Ac, 160Bc, and a stator body part 131 And an inlet port 134 and an exhaust port 135 which are formed at the bottom of the gas working chamber and communicate with one end and the other end of the gas working chamber.

As shown in FIG. 1, a part of the first support part 132 is accommodated in the rotor hollow parts 112 and 122.

A part of drive motor 140A, 140B is respectively accommodated in the rotor hollow part 112,122 of male rotor 110 and the female rotor 120, as shown in FIG. 1, by an inverter (not shown). It is controlled synchronously.

As shown in FIG. 1, drive motor 140A is arrange | positioned between bearing bearings 160Aa and 160Ab.

The drive motor 140B is arrange | positioned between bearing bearings 160Ba and 160Bb, as shown in FIG.

As shown in FIG. 1, the rotating shafts 150A and 150B are partially housed in the rotor hollow portions 112 and 122.

As shown in FIG. 1, the rotation shaft 150A, 150B has the flange part 151A, 151B extended and fixed toward the inner peripheral wall of the rotor hollow part 112, 122, respectively.

As shown in FIG. 1, bearing mechanisms of the rotary shafts 150A and 150B include bearing bearings 160Aa and 160Ba disposed on the inlet port 134 side and bearing bearings 160Ac and 160Bc disposed on the exhaust port 135 side. And bearing bearings 160Ab and 160Bb disposed between bearing bearings 160Aa and 160Ac or bearing bearings 160Ba and 160Bc.

The gears 170A and 170B are attached to the rotary shafts 150A and 150B, and when abnormalities occur, the contact between the screw gear portion 111 of the male rotor 110 and the screw gear portion 121 of the female rotor 120 is caused. And the vibration and noise caused by the backlash of the screw gears 111 and 121, especially at the time of starting and ending rotation.

The oil supply means 180 supplies lubricating oil to each of the constituent members. As shown in FIG. 2, the oil supply unit 180 centrifugally compresses the lubricating oil from the oil reservoir 181 storing the lubricating oil and the oil reservoir 181. It consists of the lifting head 182 which pushes upward by a drag effect, and the oil flow path 183 which supplies the lubricating oil pushed up by the lifting head 182 to each structural member.

2 is a figure which conceptually demonstrates the circulation path of lubricating oil by hatching the part which concerns on the circulation path of lubricating oil. In addition, the arrow shown in FIG. 2 was described in order to conceptually explain the circulation path of lubrication oil, and does not show the specific circulation path of lubrication oil.

The oil storage part 181 is a space formed in the lower part of the stator 130, and stores lubricating oil as shown in FIG. 2, and in this oil storage part 181, the cooling pipe of the cooling apparatus 190 mentioned later is mentioned. 191 is disposed.

As shown in FIG. 2, the lifting head 182 has a through hole penetrating in the up and down direction, and the inner circumferential surface of the through hole is formed in a tapered shape in which the diameter is extended from below to upward. The lifting head 182 is fixed to the lower ends of the rotary shafts 150A and 150B, and rotates together with the rotary shafts 150A and 150B when the screw vacuum pump 100 is driven, and the tapered inner peripheral surface and the rotary shaft are described above. It is comprised so that lubrication oil may be pushed up from the oil storage part 181 by the centrifugal force and drag effect which utilized rotation of 150A, 150B.

The oil flow passage 183 is formed at a position physically separated from the above-described gas working chamber, and supplies the lubricating oil pushed up by the lifting head 182 to the respective constituent members and is supplied to the constituent members. It is a circulation path which returns the lubricating oil back to the oil reservoir 181. The lubricating oil flows along the inner wall defining the oil flow passage 183 and flows into the mist in the hollow oil flow passage 183. Specifically, in this embodiment, as shown in FIG. 2, the lubricating oil is pushed up from the oil storage portion 181 by the lifting head 182, and passes through the hollow portions formed in the rotary shafts 150A and 150B. It moves upward by the centrifugal force and is discharged to the outside of the rotation shafts 150A and 150B near the upper portions of the bearing bearings 160Aa and 160Ba. Next, the discharged lubricating oil is supplied into the bearing bearings 160Aa and 160Ba, and flows into the mist in the hollow formed between the bearing bearings 160Aa and 160Ba and the drive motors 140A and 140B. At the same time, it flows on the inner wall defining the hollow portion and is supplied into the drive motors 140A and 140B. Next, the lubricating oil from the drive motors 140A and 140B flows into the mist in the hollow portion formed between the drive motors 140A and 140B and the bearing bearings 160Ab and 160Bb, and defines the hollow portion. It flows on the inner wall and is supplied into bearing bearings 160Ab and 160Bb. Next, the lubricating oil from the bearing bearings 160Ab and 160Bb flows in the hollow portion formed between the bearing bearings 160Ab and 160Bb and the synchronous gears 170A and 170B in the form of a mist and defines the hollow portion. It flows on the inner wall and is supplied to the synchronous gears 170A and 170B. Next, the lubricating oil supplied to the synchronous gears 170A, 170B is supplied to the surface of the synchronous gears 170A, 170B including the engaging portion between the synchronous gears 170A, 170B. Next, the lubricating oil is supplied into bearing bearings 160Ac and 160Bc, and is returned to oil storage part 181 again. In addition, what is necessary is just to set the supply point of lubricating oil arbitrarily according to embodiment.

The cooling device 190 cools the lubricating oil stored in the oil storage unit 181 by water cooling, and as shown in FIG. 2, a cooling pipe 191 disposed in the oil storage unit 181 to circulate the cooling water, and It is comprised by the cooling pump 192 which supplies cooling water to the cooling pipe 191. In addition, illustration of the cooling apparatus 190 is abbreviate | omitted in FIG.

As shown in FIG. 5, the engagement of the male rotor 110 and the female rotor 120 is the rotation shaft (rotation shaft) 150A of the male rotor 110 and the rotation shaft (rotation shaft) 150B of the female rotor 120. In the position away from the gear engagement pitch sources SA and SB, which are determined according to the interaxial distance of and the number of teeth of the male rotor 110 and the female rotor 120.

Therefore, there is no tooth surface in which the tooth surface speeds of the screw gear portion 111 and the screw gear portion 121 coincide, and there is an action of scraping the sucked reaction product and the like, thereby exerting the effect of scraping the reaction product out of the pump. .

In addition, code | symbol DA and DB shown in FIG. 5 have shown the outer diameter of the male rotor 110 and the female rotor 120. As shown in FIG.

In this embodiment obtained in this way, by storing a part of drive motor 140A, 140B in rotor hollow part 112, 122, the dimension of a pump in a rotating shaft longitudinal direction can be miniaturized.

In addition, most of the drive trains of the drive motors 140A and 140B are kept inside the male rotor 110 and the female rotor 120, and the drive to the pump component members other than the male rotor 110 and the female rotor 120 is performed. Since the influence of the driving heat of the motors 140A and 140B can be reduced, a high degree of freedom in designing the pump constituent member can be realized.

In addition, part of the drive motors 140A and 140B is housed in the rotor hollow portions 112 and 122, so that the driving heat generated from the drive motors 140A and 140B is transferred to the male rotor 110 and the female rotor 120. Since the temperature of the screw gears 111 and 121 of the male gears 111 and 121 can be made uniform, and the thermal expansion of the screw gears 111 and 121 of the male rotor 110 and the female rotor 120 can be maintained to the same degree, the male rotor 110 ) And the engagement gaps of the screw gears 111 and 121 of the arm rotor 120 are not biased and maintain a uniform gap. Therefore, the engagement contact between the screw gear portions 111 and 121 is lost, and the engagement gap is stabilized, so that the back diffusion from the exhaust port 135 side can be suppressed to reduce the power consumption, so that the screw vacuum pump 100 can be stabilized. Driving can be realized.

Drive motors 140A and 140B are disposed between bearing bearings 160Aa and 160Ab and bearing bearings 160Ba and 160Bb.

This ensures a certain distance between bearing bearings 160Aa and 160Ab and bearing bearings 160Ba and 160Bb to secure the bearing of the rotating shaft, while bearing bearings 160Aa and 160Bb and bearing bearings 160Ba and 160Bb. By effectively using the space between the mounting spaces of the drive motors 140A and 140B, the size of the pump in the rotational axis longitudinal direction can be further reduced. In other words, since the motor is placed inside the screw rotor, the external dimension of the pump can be significantly reduced. Conventional pumps cannot be installed in the vicinity of semiconductor device manufacturing apparatuses, liquid crystal panel manufacturing apparatuses, and solar panel manufacturing apparatuses. However, this motor built-in screw pump can be installed in the vicinity of each apparatus or under a chamber, thereby greatly reducing the apparatus installation space. It can be improved.

In addition, the male rotor 110 and the female rotor 120 are provided with uneven lead uneven inclination-angle screw portions 111a and 121a on the inlet port 134 side and back lead screw portions 111b and 121b on the exhaust port 135 side. Further, the engagement of the male rotor 110 and the female rotor 120 is determined according to the interaxial distance of the male rotor 110 and the female rotor 120 and the number of teeth of the male rotor 110 and the female rotor 120. By being in the position away from the gear engagement pitch sources SA and SB, it is possible to increase the compression ratio and to scrape off the product, and to maintain a stable exhaust speed up to 0.5 Pa.

Second Embodiment

Next, the screw vacuum pump 200 which is a 2nd Example of this invention is demonstrated based on FIG.

Here, since the structure other than the drive motor 240 in the screw vacuum pump 200 which is 2nd Example is exactly the same as the above-mentioned content, the specification about the screw vacuum pump 100 of 1st Example and FIG. By substituting the code | symbol of the 100th number shown in FIG. 5 with the code | symbol of the 200th number, the description is abbreviate | omitted about the structure other than the drive motor 240. FIG.

In the screw vacuum pump 200 according to the second embodiment of the present invention, as shown in FIG. 6, a single drive motor 240 as a drive source common to the male rotor 210 and the female rotor 220 is provided to the male rotor 210. It is housed in the formed rotor hollow part 212.

The drive motor 240 drives the rotary shaft 250A to rotate, and the driving force of the drive motor 240 is also transmitted to the rotary shaft 250B through the synchronous gears 270A and 270B in a synchronous state. In order to drive the other screw rotor to rotate, the synchronous gears 270A and 270B are larger in width and stronger than the gears 170A and 170B of the first embodiment.

Also in the second embodiment, the oil supply means 280 and the cooling device (not shown) configured in the same manner as the first embodiment described above are formed, but there is no difference other than the number of drive motors supplied with lubricating oil. Therefore, the illustration and explanation are omitted.

Also in this embodiment, since the motor is placed inside the screw rotor, the external dimension of the pump can be significantly reduced. Conventional pumps could not be installed in the vicinity of semiconductor device manufacturing apparatuses, liquid crystal panel manufacturing apparatuses, and solar panel manufacturing apparatuses. However, this motor built-in screw pump can be installed in the vicinity of each apparatus or under the chamber, thereby greatly improving the apparatus installation space. can do.

Variation example

Next, the modification common to the 1st Example and 2nd Example of this invention is demonstrated based on FIG.

In the above-described first and second embodiments, as illustrated in FIG. 1 or 6, the screw gear portions 111, 121, 211, and 221 of the male rotor 110 and 210 and the female rotor 120 and 220 are shown. The description has been made as having the uneven lead uneven inclination-angled screw portions 111a, 121a, 211a, and 221a and the back lead screw portions 111b, 121b, 211b, and 221b of one lead or a plurality of leads.

In this modified example, as shown in FIG. 7, the screw gear parts 311 and 321 of the male rotor 310 and the female rotor 320 are the 1st back lead screw parts 311a and 321a arrange | positioned at the inlet port 335 side. ), One lead or a plurality of leads continuous to the uneven lead uneven inclination-angle screw portions 311b and 321b continuous to the first back lead screw portions 311a and 321a and the uneven lead uneven inclination angle screw portions 311b and 321b. It has the 2nd lamp lead screw parts 311c and 321c.

In addition, only the male rotor 310 is shown in FIG. 7.

On the other hand, in the above-described first embodiment, second embodiment, and modified example, the screw gear portions of the male rotor and the female rotor were described as having an uneven lead uneven inclination angle screw portion and a back lead screw portion. It does not matter even if it is designed as having only it.

Moreover, what is necessary is just to set suitably the dimension design and combination of the uneven lead uneven inclination-angle screw part and the back lead screw part according to embodiment.

100, 200... Screw vacuum pump
110, 210... Male rotor
111, 211... Screw gear part
111a... Uneven Lead Unequal Inclination Angle Screw
111b... Back lead screw
112, 212... Rotor hollow
120, 220... Arm rotor
121, 221... Screw gear part
121a. Uneven Lead Unequal Inclination Angle Screw
121b. Back lead screw
122, 222... Rotor hollow
130, 230... The stator
131, 231... Stator Body
132, 232. The first support
133, 233... The second support
134, 234... Intake port
135, 235... Exhaust
140A. Drive motor
140B. Drive motor
240... Drive motor
150 A, 250 A... Rotating shaft
150B, 250B... Rotating shaft
151A, 251A... Flange portion
151B, 251B... Flange portion
160Aa, 260Aa... Bearing bearing
160Ab, 260Ab... Bearing bearing
160Ac, 260Ac... Bearing bearing
160Ba, 260Ba... Bearing bearing
160Bb, 260Bb... Bearing bearing
160Bc, 260Bc... Bearing bearing
170A, 170B. Gear
270A, 270B. Synchronous gear
180, 280... Oil supply means
181. Oil reservoir
182. Lifting head
183. Oil distributor
190. Cooling device
191. Cooling pipe
192... Cooling pump
310... Male rotor
311 ... Screw gear part
311a... First light lead screw
311b... Uneven Lead Unequal Inclination Angle Screw
311c... Second light lead screw part
312. Rotor hollow

Claims (9)

A male rotor and a female rotor each having a screw gear part engaged with each other on an outer circumferential side, a stator for accommodating the male rotor and a female rotor, and a drive motor for rotationally driving the male rotor and the female rotor,
The screw gear portion of the male rotor and the screw gear portion and stator of the female rotor cooperate to form a gas working chamber,
The stator has an inlet and an exhaust port communicating with one end and the other end of the gas operation chamber,
At least one of the male rotor and the female rotor has a rotor hollow portion opened at least at one end face side in the longitudinal direction of the rotational axis of the male rotor and / or the female rotor,
At least a portion of the drive motor is accommodated in the rotor hollow portion, the screw vacuum pump. The method of claim 1,
The male rotor and the female rotor each have the rotor hollow portion,
Two drive motors are formed,
At least a part of said drive motor is accommodated in the rotor hollow part of the said male rotor and a female rotor, respectively, The screw vacuum pump characterized by the above-mentioned. 3. The method according to claim 1 or 2,
And further comprising a rotating shaft at least partially housed in the rotor hollow and fixed to the male and / or female rotors, and at least two bearing bearings bearing the rotating shaft,
The said drive motor is arrange | positioned between the said bearing bearings, The screw vacuum pump characterized by the above-mentioned. The method according to any one of claims 1 to 3,
The stator includes a stator main body for accommodating the male rotor and the female rotor, and a support part fixed to the stator main body to accommodate a portion of the rotor in the rotor hollow part and supporting the drive motor and / or bearing bearing. Screw vacuum pump, characterized in that. The method according to any one of claims 1 to 4,
The screw gear portion of the male rotor and the female rotor has an uneven lead uneven inclination angle screw portion disposed on the inlet port side, and one or more lead back lead screw portions connected to the uneven lead uneven inclination angle screw portion. Screw vacuum pump. The method according to any one of claims 1 to 4,
The screw gear portion of the male rotor and the female rotor includes a first light lead screw portion disposed on the inlet port side, an uneven lead uneven tilt angle screw portion continuous to the first light lead screw portion, and an uneven lead uneven tilt angle screw portion. The screw vacuum pump which has the lead screw part of the 1st lead or the 2nd lead which is continuous to the 2nd lead. 7. The method according to any one of claims 1 to 6,
The engagement of the male rotor and the female rotor is in a position deviated from the gear engagement pitch circle determined by the interaxial distance between the rotational axis of the male rotor and the rotational axis of the female rotor and the number of teeth of the male and female rotors. Vacuum pump. The method according to any one of claims 1 to 7,
Further comprising an oil supply means for supplying a lubricating oil and a rotating shaft fixed to the male rotor and / or the female rotor,
The oil supply means includes an oil reservoir for storing lubricating oil, a lifting head fixed to the rotary shaft and pushing up the lubricating oil from the oil reservoir using rotation of the rotary shaft, and pushed by the lifting head. A screw vacuum pump, comprising: an oil flow path for circulating the raised lubricating oil at a predetermined point. The method of claim 8,
And a cooling device for cooling the lubricating oil.

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