JPH0666281A - Shaft sealing device for vacuum pump - Google Patents

Abstract

PURPOSE:To provide a vacuum-pump shaft sealing device which prevents oil mist from entering a pump even if lubricating oil leaks from an oil seal and can cool the sliding part of the oil seal and prolong the life of the oil seal. CONSTITUTION:A shaft sealing device for a vacuum pump comprises a casing 2 provided with both a peripheral groove 25 communicating with the clearance 2 between the inner peripheral surface of the casing and the outer peripheral surface of a rotor 3 so as to form a loop, and a first communicating hole 26 through which atmospheric gas is introduced into the peripheral groove 25 from outside the casing 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal device for a vacuum pump, which supports a rotary shaft of a rotor by means of an oil lubrication bearing and is provided with an oil seal for preventing lubricant oil from entering an oil-free pump machine. In particular, the present invention relates to a vacuum pump shaft seal device suitable for preventing oil mist from entering the oil-free pump machine when lubricating oil leaks from an oil seal and oil mist is generated.

[0002]

2. Description of the Related Art An example of a vacuum pump to which the present invention is applied is shown in FIG.

The vacuum pump shown in FIG. 6 includes a housing 1, a casing 2 attached to one half of an upper portion of the housing 1, and a pair of male and female screw type rotors 3 provided inside the casing 2. , An oil-lubricated bearing 5 mounted integrally on the rotor 3 and inside the housing 1.
A rotary shaft 4 supported by the rotary drive source 6, a rotary drive source 6 installed on the other half of the upper part of the housing 1, a drive shaft 7 attached to the rotary drive source 6, and the drive shaft 7 and the rotary shaft 4. It is provided with a speed-up drive gear train 8 that is drivingly connected, an exhaust silencer 15, and a self-priming lubricating oil pump 16 provided in the housing 1 below the rotary shaft 4.

An intake port 9 is provided in the upper portion of the casing 2, and a pump interior 10 is secured above the inside of the casing 2. The intake port 9 is adapted to introduce a gas to be compressed into a pump machine 10 from a vacuum chamber (not shown).

The pair of male and female rotors 3 are synchronously rotationally driven in a non-contact manner through a drive system including a rotary drive source 6 → a drive shaft 7 → a speed increasing drive gear train 8 → a timing gear → a rotary shaft 4. Thus, the rotor 3 moves from the vacuum chamber to the intake port 9
The gas sucked in through is compressed and sent through the tooth space 11 toward the rotor discharge end 13 side. The compressed air that has been sent to the rotor discharge end 13 is pressurized to atmospheric pressure.

An exhaust port 14 is provided in the housing 1. The exhaust port 14 guides the gas compressed to the atmospheric pressure from the rotor discharge end 13 to the silencer 15.

The silencer 15 silences the compressed gas and releases it to the atmosphere.

On the other hand, the oil supply passage 1 is provided inside the rotary shaft 4.
7 is provided. The oil supply passage 17 supplies the lubricating oil 18 sent from the lubricating oil pump 16 to the oil lubrication bearing 5 to lubricate it.

On the other hand, the oil-lubricated bearing 5 on the rotary shaft 4
A sleeve 19 is attached immediately above. An oil seal 21 is mounted between the outer peripheral surface of the sleeve 19 and the inner peripheral surface of the cylindrical shaft portion 20 of the housing 1. The oil seal 21 seals the lubricating oil 18 from entering the oil-free pump machine interior 10.

By the way, in the conventional shaft seal device of the vacuum pump, as shown in FIG. 6 and enlarged in FIG. 7, the oil seal 2 is provided between the sleeve 19 and the cylindrical shaft portion 20 of the housing 1.
It is configured by mounting 1. In this conventional shaft seal device, if the lubricating oil 18 should leak from the oil seal 21, most of the lubricating oil 18 will be guided to the exhaust port 14 and recovered if it is liquid. However, the lubricating oil 1
As shown in FIG. 7, when the oil mist 8 has a mist shape, the oil mist 18 ′ may diffuse back into the pump machine 10 and enter the vacuum chamber.

A technique related to this type of apparatus is disclosed in, for example, Japanese Utility Model Publication No. 63-175355, Japanese Utility Model Publication No.
-82371 publication etc. are mentioned.

The technique disclosed in the above-mentioned publication is such that a leaky fluid is moved inward in the radial direction by a hydrodynamic pumping action by means of a spiral projection or groove, or the leaked fluid is absorbed by an absorbent member such as a felt. It is what makes me.

[0013]

However, the prior art shown in FIG. 7 is not provided with a means for preventing the oil mist 18 'from entering the inside of the pump machine 10 should oil leak from the oil seal 21. Therefore, the oil mist 18 ′ leaked from the oil seal 21 may enter the vacuum chamber through the pump interior 10 and contaminate the product.

The object of the present invention is to prevent the intrusion of oil mist into the pump machine even if the lubricating oil leaks from the oil seal, and to cool the sliding portion of the oil seal and extend the service life of the vacuum. It is to provide a shaft seal device for a pump.

[0015]

The object of the present invention is to provide a casing with a circumferential groove that annularly communicates with a gap between an inner circumferential surface of the casing and an outer circumferential surface of the rotor, and an atmospheric gas from the outside of the casing to the circumferential groove. It is achieved by providing a communication hole for introducing.

[0016] Further, for the above-mentioned purpose, in the casing, a peripheral groove that annularly communicates with a gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor, and a communication hole that introduces atmospheric gas into the peripheral groove from the outside of the casing. In addition to the above, the housing is provided with a communication hole for introducing atmospheric gas from the outside of the housing through the inside of the housing to the rear chamber of the oil seal.

Further, for the above-mentioned purpose, in the casing, a peripheral groove that annularly communicates with a gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor, and a communication hole that introduces atmospheric gas into the peripheral groove from the outside of the casing. And a communication hole for introducing atmospheric gas from the outside of the housing through the inside of the housing into the gap between the rotor discharge end and the end surface of the housing. It

Still further, the above-mentioned object is to provide a casing with a peripheral groove that annularly communicates with a gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor, and a communication that introduces atmospheric gas into the peripheral groove from the outside of the casing. And a communication hole for introducing atmospheric gas into the oil seal rear chamber from the outside of the housing through the inside of the housing.
This is achieved by providing a communication hole that introduces atmospheric gas from the outside of the housing through the inside thereof into the gap between the rotor discharge end and the end surface of the housing.

The above-mentioned object is better achieved by forming the circumferential groove at a position separated from the intake side end surface of the rotor on the inner wall surface of the casing by one lead or more of the screw of the rotor on the downstream side. It

[0020]

According to the present invention, in the casing, a peripheral groove that annularly communicates with a gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor, and a communication hole (hereinafter This communication hole is referred to as a "first communication hole").

In the present invention, atmospheric gas is introduced from the outside of the casing into the circumferential groove through the first communication hole, and the atmospheric gas is introduced between the inner circumferential surface of the casing and the outer circumferential surface of the rotor in the low vacuum region. Introduce into the gap by self-priming. The gap communicates with the rear chamber of the oil seal, and if oil leaks from the oil seal and oil mist occurs,
The oil mist flows into the gap. On the other hand, part of the atmospheric gas introduced into the gap flows downward from above with the rotation of the rotor, and guides the oil mist floating in the gap to the exhaust port. The other part of the atmospheric gas introduced into the gap diffuses evenly around the lower part of the pump machine to prevent the oil mist from entering the pump machine. Further, the sliding portion of the oil seal can be cooled by the atmospheric gas introduced into the oil seal rear chamber through the gap. Therefore, it is possible to eliminate the problem that the lubricating oil near the sliding portion of the oil seal evaporates due to the sliding heat of the oil seal and leaks to the oil seal rear chamber side. Moreover, the atmospheric gas introduced into the gap through the first communication hole and the circumferential groove can bring the rear chamber of the oil seal close to the atmospheric pressure. As a result, the pressure difference between the inside and the outside of the oil seal can be almost eliminated, and the life of the oil seal can be kept long.

In the present invention, the casing is provided with the peripheral groove and the first communicating hole, and the housing is provided with a communicating hole for introducing atmospheric gas into the oil seal rear chamber from the outside of the casing through the inside of the housing. (Hereinafter, this communication hole will be referred to as "second
Communication hole ". ) Is provided.

In the present invention, the atmospheric gas is introduced from the outside of the housing into the rear chamber of the oil seal in the low vacuum region by self-priming through the second communication hole provided in the housing, and the atmospheric gas causes a floating state. A certain oil mist is forcibly guided to the exhaust port together with atmospheric gas. Further, through the first communication hole and the peripheral groove provided in the casing,
Atmospheric gas is introduced into the gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor by self-priming. Then, similar to the above-mentioned invention, part of the atmospheric gas introduced into the gap guides the oil mist floating in the gap to the exhaust port, and the other part of the atmospheric gas causes the oil mist to enter the pump machine. Prevent. Further, by mainly cooling the sliding portion of the oil seal with atmospheric gas introduced directly into the oil seal rear chamber through the second communication hole, the sliding heat of the oil seal evaporates and the sliding portion of the oil seal slides. It is possible to solve the problem that the lubricating oil leaks from. In addition, the atmospheric gas introduced through the first and second communication holes eliminates the pressure difference between the inside and outside of the oil seal, and the life of the oil seal can be kept long.

Further, according to the present invention, in addition to the peripheral groove and the first communication hole provided in the casing, a gap is provided between the rotor discharge end and the end surface of the housing through the outside of the housing and the inside of the housing. A communication hole for introducing atmospheric gas (hereinafter, this communication hole is referred to as a "third communication hole") is provided.

In the present invention, the atmospheric gas is introduced by self-priming into the gap in the low vacuum region between the rotor discharge end and the end face of the housing through the third communication hole provided in the housing. The gap communicates with the oil seal rear chamber,
Atmospheric gas is introduced into the oil seal rear chamber through this gap. Therefore, the oil mist floating near the oil seal rear chamber is guided to the exhaust port together with the third communication hole → the gap → the atmospheric gas introduced into the oil seal rear chamber. Further, atmospheric gas is self-primed into the gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor through the first communication hole and the peripheral groove provided in the casing. Then, similar to the above-mentioned invention, part of the atmospheric gas introduced into the gap guides the oil mist floating in the gap to the exhaust port, and the other part of the atmospheric gas causes the oil mist to enter the pump machine. Prevent. Further, by mainly cooling the sliding portion of the oil seal by the atmospheric gas introduced into the rear chamber of the oil seal through the second communication hole, the sliding heat of the oil seal evaporates and the sliding portion of the oil seal evaporates. It is possible to solve the problem that the lubricating oil leaks. Moreover,
Due to the atmospheric gas introduced through the first and third communication holes, the differential pressure between the inside and outside of the oil seal can be eliminated and the life of the oil seal can be kept long.

Furthermore, in the present invention, in addition to the peripheral groove and the first communication hole provided in the casing, the second and third communication holes are provided in the housing.

Therefore, according to the present invention, it is possible to more effectively prevent the entry of the oil mist into the pump machine, it is possible to effectively cool the sliding portion of the oil seal, and the inside of the oil seal is prevented. By eliminating the pressure difference between the outsides, the life of the oil seal can be kept even longer.

By the way, it has been experimentally confirmed that it is possible to better prevent the oil mist from entering the pump machine by providing the circumferential groove on the upstream side of the rotor. However, if it is provided too close to the upstream side, the gas on the intake side and the atmospheric gas come into contact with each other, degrading the pump performance.

Therefore, in the present invention, the peripheral groove is formed at a position separated from the intake side end surface of the rotor on the inner wall surface of the casing by one lead or more of the screw of the rotor on the downstream side.

As a result, the gas on the intake side of the rotor and the atmospheric gas can be prevented from directly contacting each other, so that the deterioration of the pump performance can be prevented and the oil mist can be appropriately guided to the exhaust port side. .

[0031]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view of the essential parts showing the first embodiment of the present invention.

In the first embodiment shown in FIG. 1, the peripheral groove 25 and the first communication hole 26 are formed in the casing 2 which accommodates a pair of male and female screw type rotors 3 meshing with each other.
And are provided.

The circumferential groove 25 is formed in an annular shape on the inner peripheral surface of the casing 2 and communicates with the gap 23 between the inner peripheral surface of the casing 2 and the outer peripheral surface of the rotor 3. The gap 23 communicates with the oil seal rear chamber 22 through the gap between the inside of the rotor 3 and the cylindrical shaft portion 20 of the housing 1.

The first communication hole 26 communicates with the peripheral groove 25 from the outside of the casing 2, and the atmospheric gas is introduced into the peripheral groove 25.

Regarding the other construction of the first embodiment,
This is the same as the prior art shown in FIG. 7, the same members are denoted by the same reference numerals, and further description will be omitted.

Next, the operation of the first embodiment will be described.

In this first embodiment, atmospheric gas is introduced into the peripheral groove 25 provided on the inner wall surface of the casing 2 through the first communication hole 26 provided in the casing 2.
The atmospheric gas introduced into the circumferential groove 25 flows evenly around and is introduced into the gap 23 between the inner peripheral surface of the casing 2 and the outer peripheral surface of the rotor 3, which is a low vacuum region, by self-priming.

On the other hand, the gap 23 communicates with the oil seal rear chamber 22 as described above, and should the oil seal 2
When the lubricating oil leaks from No. 1 and the oil mist 18 ′ is generated, the oil mist 18 ′ flows into the gap 23.

Here, a part of the atmospheric gas introduced into the gap 23 flows downward from above with the rotation of the rotor 3 and floats in the gap 23.
To the exhaust port 14. The other part of the atmospheric gas introduced into the gap 23 diffuses around the lower part of the pump machine 10 to prevent the oil mist 18 ′ from entering the pump machine 10.

Further, by the atmospheric gas introduced into the oil seal rear chamber 22 through the gap 23, the oil seal 2
1. Cool the sliding part of 1. Therefore, the oil seal 21
It is possible to solve the problem that the lubricating oil near the sliding portion of the oil seal 21 evaporates due to the sliding heat of the above and leaks to the oil seal rear chamber 22 side.

Moreover, the atmospheric gas introduced into the gap 23 can bring the oil seal rear chamber 22 close to the atmospheric pressure. As a result, the pressure difference between the inside and outside of the oil seal 21 can be almost eliminated, and the oil seal 2
The life of 1 can be maintained for a long time.

Regarding the other operation of the first embodiment,
This is similar to the prior art shown in FIG.

Next, FIG. 2 is an enlarged cross-sectional view of a main part showing a second embodiment of the present invention.

In the second embodiment, the casing 2 is provided with the peripheral groove 25 and the first communication hole 26, and the housing 1 is provided with the second communication hole 27.

The second communication hole 27 is formed so that atmospheric gas can be introduced into the oil seal rear chamber 22 from the outside to the inside of the housing 1.

Regarding the other structure of the second embodiment,
This is the same as the first embodiment.

Next, the operation of the second embodiment will be described.

In this second embodiment, atmospheric gas is introduced from the outside of the housing 1 into the oil seal rear chamber 22 in the low vacuum region by self-priming through the second communication hole 27 provided in the housing 1.

If the lubricating oil 18 leaks from the oil seal 21 and the oil mist 18 ′ floats in the oil seal rear chamber 22, the atmospheric gas will cause the oil mist in the oil seal rear chamber 22. 18 ′ is forced to leave a gap 2 between the inner peripheral surface of the casing 2 and the outer peripheral surface of the rotor 3.
Lead to 3.

On the other hand, atmospheric gas is introduced into the gap 23 from the outside of the casing 2 through the first communication hole 26 and the peripheral groove 25, as in the first embodiment. As a result, the oil mist 18 'introduced into the gap 23 is
Part of the atmospheric gas introduced into the gap 23 and flowing downward from above with the rotation of the rotor 3 is guided to the exhaust port 14. Furthermore, the other part of the atmospheric gas introduced into the gap 23 prevents the oil mist 18 ′ from entering the pump interior 10.

In the second embodiment, the oil seal 21 is cooled mainly by the atmospheric gas introduced directly into the oil seal rear chamber 22 through the second communication hole 27.
This makes it possible to more effectively prevent the problem that the lubricating oil evaporates due to the sliding heat of the sliding portion of the oil seal 21 and leaks to the oil seal rear chamber 22 side.

Moreover, due to the atmospheric gas introduced into the gap 23 through the first communication hole 26 and the circumferential groove 25 and the atmospheric gas introduced into the oil seal rear chamber 22 through the second communication hole 27, The differential pressure between the inside and the outside of the oil seal 21 can be eliminated, and the life of the oil seal 21 can be kept long.

The other structure and operation of the second embodiment are the same as those of the first embodiment.

Next, FIG. 3 is an enlarged cross-sectional view of a main part showing a third embodiment of the present invention.

In the third embodiment shown in FIG. 3, the casing 2 is provided with the circumferential groove 25 and the first communication hole 26, and the housing 1 is provided with a third communication hole 28. .

The third communication hole 28 is provided so as to pass from the outside to the inside of the housing 1 and to introduce atmospheric gas into the gap 24 between the rotor discharge end 13 and the end face of the housing 1. The gap 24 passes through the gap between the rotor 3 and the cylindrical shaft portion 20 of the housing 1 and passes through the oil seal rear chamber 2
It communicates with 2.

In the third embodiment, through the third communication hole 28 provided in the housing 1, from the outside of the housing 1 to the gap 24 between the rotor discharge end portion 13 and the end surface of the housing 1 in the low vacuum region. Introduce atmospheric gas by self-priming. The atmospheric gas introduced into the gap 24 flows through the gap between the rotor 3 and the cylinder shaft portion 20 of the housing 1 into the oil seal rear chamber 22, and the lubricating oil should leak from the oil seal 21. When the oil mist 18 ′ is generated in the chamber 22, the floating oil mist 18 ′ is replaced by a gap 23 between the inner peripheral surface of the casing 2 and the outer peripheral surface of the rotor 3.
Lead to.

After that, as in the second embodiment, the first
The oil mist 18 ′ is guided to the exhaust port 14 by the atmospheric gas introduced into the gap 23 from the communication hole 26 and the circumferential groove 25, and is prevented from entering the pump machine 10.

The other structure and operation of the third embodiment are the same as those of the second embodiment.

Next, FIG. 4 is an enlarged cross-sectional view of the essential parts showing a fourth embodiment of the present invention.

In the fourth embodiment shown in FIG. 4, the casing 2 is provided with the first communicating hole 26 and the peripheral groove 25, and the housing 1 is provided with the second communicating hole 27 and the third communicating hole. Holes 28 and are provided.

As a result, in the fourth embodiment, the oil mist 1 to the pump interior 10 is produced by the synergistic action of the first communication hole 26, the circumferential groove 25, and the second and third communication holes 27 and 28.
In addition to being able to more effectively prevent the intrusion of 8 ', the sliding portion of the oil seal 21 can be effectively cooled, and the differential pressure between the inside and outside of the oil seal 21 can be eliminated, and the oil seal The life of 21 can be maintained even longer.

The other structure and operation of the fourth embodiment are the same as those of the first, second and third embodiments.

Further, FIG. 5 shows a fifth embodiment of the present invention and is a development view of the rotor for explaining the positions of the circumferential groove and the first communicating hole.

In this fifth embodiment, the circumferential groove 25 is formed at a position separated from the intake side end surface of the rotor 3 on the inner wall surface of the casing 2 toward the exhaust side (downstream side) by a distance L of one lead of the screw or more. Has been done. Then, the first communication hole 2
6 is provided from the outside of the casing 2 at an arbitrary position on the circumference of the circumferential groove 25. In addition, in FIG. 5, the tooth-shaped land portion of the rotor is hatched and indicated by reference numeral 12.

By the way, an experiment has shown that it is possible to better prevent the oil mist 18 'from entering the pump machine 10 by providing the circumferential groove 25 at a position closest to the intake side (upstream side) of the rotor 3. Have been confirmed. However, if it is provided too close to the upstream side, the gas on the intake side and the atmospheric gas come into contact with each other, resulting in deterioration of pump performance.

Therefore, in this fifth embodiment, the circumferential groove 25
Is formed on the inner wall surface of the casing 2 at a position separated from the upstream end surface which is the intake side of the rotor 3 to the downstream side by a distance L of one lead of the screw or more. It is possible to prevent the air and the atmospheric gas from directly contacting each other, so that it is possible to solve the problem that the pump performance is deteriorated, and it is possible to appropriately guide the oil mist 18 ′ to the exhaust port 14 side.

In the present invention, compressed gas may be pushed in from the outside through the first, second and third communication holes 26, 27 and 28.

Further, a small vacuum pump may be provided at the exhaust port 14 to suck the oil mist 18 '.

Further, in the present invention, filters may be provided in the exhaust port 14 and the first, second, and third communication holes 26, 27, 28 depending on the atmosphere and environment of the place where the vacuum pump is used.

Further, the first, second and third communication holes 2
Orifices or valves for adjusting the flow rate of atmospheric gas may be provided in 6, 27 and 28.

[0073]

According to the invention described in claim 1 of the present invention described above, the casing is provided with a peripheral groove annularly communicating with the gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor, and the casing. A first communication hole for introducing atmospheric gas from the outside is provided in the peripheral groove, and a gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor is provided from the outside of the casing through the first communication hole and the peripheral groove. Introduce atmospheric gas to the
This atmospheric gas guides the oil mist to the exhaust port side, and also prevents the oil mist from entering the pump, so even if the oil leaks from the oil seal, the oil mist in the pump will be lost. Has the effect of preventing the intrusion of oil, and since the sliding part of the oil seal can be cooled by the atmospheric gas introduced into the gap, the lubricating oil evaporates due to the sliding heat of the sliding part of the oil seal. This has the effect of eliminating the problem of leaking to the oil seal rear chamber side, and by introducing atmospheric gas into the gap, the differential pressure between the inside and outside of the oil seal is eliminated and the life of the oil seal is extended. There is also an effect that can be maintained.

Further, according to the second aspect of the present invention, the oil seal is provided not only in the casing where the peripheral groove and the first communication hole are provided but also in the housing from the outside thereof through the inside of the housing. A second communication hole for introducing atmospheric gas is provided in the rear chamber, and the atmospheric gas is introduced by self-priming into the oil seal rear chamber through the second communication hole provided in the housing, and the oil mist is generated by this atmospheric gas. Is forcibly guided to the gap between the inner peripheral surface of the casing and the outer peripheral surface of the rotor, and then the oil mist is guided to the exhaust port side by the atmospheric gas introduced into the gap through the first communication hole and the peripheral groove, and the pump Since the oil mist is prevented from entering the machine, even if oil mist should occur, it is possible to more reliably prevent the oil mist from entering the pump machine. Outside, since the sliding portion of the oil seal by the atmosphere gas introduced into the oil seal rear chamber through the second communicating hole can directly cool with,
The sliding portion of the oil seal can be cooled more effectively, the pressure difference between the inside and outside of the oil seal can be eliminated, and the life of the oil seal can be kept longer.

Further, according to the third aspect of the present invention, in addition to the casing having the peripheral groove and the first communication hole, the housing has the rotor discharge end and the end surface of the housing from the outside of the housing. A third communication hole for introducing atmospheric gas is provided in the space between them. The third communication hole → the above clearance → the clearance between the rotor and the cylindrical shaft portion of the housing is self-priming to the oil seal rear chamber to cause atmospheric gas Therefore, in the present invention as well as the invention according to the second aspect, there is an effect that the intrusion of the oil mist into the pump machine can be prevented more reliably, and the oil seal is more effective. The effect is that the oil seal can be cooled, the differential pressure between the inner side and the outer side of the oil seal is eliminated, and the life of the oil seal can be kept longer.

According to the fourth aspect of the present invention, the casing is provided with the peripheral groove and the first communication hole, and the housing is provided with the second communication hole and the third communication hole. Since the holes are provided, the synergistic action of the peripheral groove, the first communication hole, and the second and third communication holes makes the pump more effective than the inventions according to claims 1 to 3. This has the effect of preventing oil mist from entering the machine, cooling the oil seal, and maintaining the life of the oil seal longer.

According to the fifth aspect of the present invention, the circumferential groove is located downstream from the intake side end surface of the rotor on the inner wall surface of the casing by one lead or more of the screw of the rotor. Since it is formed in the above, there is an effect that the deterioration of the pump performance due to the contact between the gas on the intake side of the rotor and the atmospheric gas is prevented, and the oil mist can be appropriately guided to the exhaust port side.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part showing a second embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of a main part showing a third embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view of a main part showing a fourth embodiment of the present invention.

FIG. 5 shows a fifth embodiment of the present invention and is a development view of the rotor for explaining the positions of the circumferential groove and the first communication hole.

FIG. 6 is a partially cutaway side view showing an example of a vacuum pump.

FIG. 7 is an enlarged cross-sectional view showing a conventional shaft sealing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Casing, 3 ... Rotor, 4 ... Rotor shaft of a rotor, 5 ... Oil lubrication bearing of a rotary shaft, 9 ... Intake port,
10 ... In pump machine, 14 ... Exhaust port, 18 ... Lubricating oil, 1
8 '... Oil mist, 21 ... Oil seal, 22 ... Oil seal rear chamber, 23 ... Gap between inner peripheral surface of casing and outer peripheral surface of rotor, 24 ... Gap between rotor discharge end and end surface of housing, 25 ... Circumferential groove, 26 ... First communication hole, 27
... second communication hole, 28 ... third communication hole, L ... distance for one lead of the screw of the rotor.

Front page continued (72) Inventor Riichi Uchida 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Machinery Research Institute, Hiritsu Seisakusho Co., Ltd. In-house

Claims (5)

[Claims] 1. A casing is mounted on the housing,
A rotating shaft is supported in the housing through an oil lubrication bearing, and a pair of male and female screw type rotors meshing with each other are attached to the rotating shaft. The rotor is housed in the casing, and the rotating shaft and the housing are accommodated. In the shaft seal device for the vacuum pump, which is equipped with an oil seal that prevents the entry of lubricating oil into the pump machine in the casing,
The casing is provided with a peripheral groove that annularly communicates with a gap between an inner peripheral surface of the casing and an outer peripheral surface of the rotor, and a communication hole that introduces atmospheric gas into the peripheral groove from outside the casing. A shaft seal device for a vacuum pump. 2. A casing is mounted on the housing,
A rotating shaft is supported in the housing through an oil lubrication bearing, and a pair of male and female screw type rotors meshing with each other are attached to the rotating shaft. The rotor is housed in the casing, and the rotating shaft and the housing are accommodated. In the shaft seal device for the vacuum pump, which is equipped with an oil seal that prevents the entry of lubricating oil into the pump machine in the casing,
The casing is provided with a peripheral groove that annularly communicates with a gap between an inner peripheral surface of the casing and an outer peripheral surface of the rotor, and a communication hole that introduces atmospheric gas from the outside of the casing into the peripheral groove. A shaft seal device for a vacuum pump, characterized in that a communication hole for introducing atmospheric gas from the outside to the inside of the housing is introduced into the oil seal rear chamber. 3. A casing is mounted on the housing,
A rotating shaft is supported in the housing through an oil lubrication bearing, and a pair of male and female screw type rotors meshing with each other are attached to the rotating shaft, and the rotor is housed in the casing, and the rotating shaft and the housing. In the shaft seal device for the vacuum pump, which is equipped with an oil seal that prevents the entry of lubricating oil into the pump machine in the casing,
The casing is provided with a peripheral groove that annularly communicates with a gap between an inner peripheral surface of the casing and an outer peripheral surface of the rotor, and a communication hole that introduces atmospheric gas into the peripheral groove from the outside of the casing. A shaft seal device for a vacuum pump, characterized in that a communication hole for introducing atmospheric gas from the outside thereof through the inside of the housing into a gap between the rotor discharge end and the end surface of the housing is provided. 4. A casing is mounted on the housing,
A rotating shaft is supported in the housing through an oil lubrication bearing, and a pair of male and female screw type rotors meshing with each other are attached to the rotating shaft, and the rotor is housed in the casing, and the rotating shaft and the housing. In the shaft seal device for the vacuum pump, which is equipped with an oil seal that prevents the entry of lubricating oil into the pump machine in the casing,
The casing is provided with a peripheral groove that annularly communicates with a gap between an inner peripheral surface of the casing and an outer peripheral surface of the rotor, and a communication hole that introduces atmospheric gas into the peripheral groove from the outside of the casing. Is a communication hole that introduces atmospheric gas into the rear chamber of the oil seal from the outside of the housing through the interior of the housing, and atmospheric gas in the gap between the rotor discharge end and the end surface of the housing through the interior of the housing from the outside of the housing. A shaft seal device for a vacuum pump, which is provided with a communication hole for introducing. 5. The peripheral groove is formed at a position distant from the intake side end surface of the rotor on the inner wall surface of the casing by one lead or more of the screw of the rotor on the downstream side. A shaft sealing device for a vacuum pump according to any one of 1.