JP2002221157A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure good sealing performance and to extend the service life of a lip seal at a low cost in a vacuum pump. SOLUTION: A relieving hole 53 is formed in the upper wall 332 of a gear housing 33. The relieving hole 53 comprises a small diameter part 531 and a female screw part 532 having a large diameter. An air vent filter 55 is mounted on a step between the small diameter part 531 and the female screw part 532. The filter 55 has air permeability and oil repellency. A male screw 54 is screwed to the female screw part 532, and the filter 55 is interposed between the male screw 54 and the step. A thin relieving hole 541 is drilled in the axial center part of the male screw 54.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to moving a gas transfer member in a pump chamber based on rotation of a rotary shaft, transferring gas by the operation of the gas transfer member, and providing a suction effect.
A lip ring for shaft sealing is arranged so as to slide on the peripheral surface of the rotary shaft between the oil existing area and the pump chamber, and the peripheral surface of the rotary shaft from the oil existing area side to the pump chamber side. The present invention relates to a vacuum pump configured to prevent oil leakage through a vacuum pump.

[0002]

2. Description of the Related Art A vacuum pump which moves a gas transfer member in a pump chamber based on rotation of a rotating shaft and transfers a gas by the operation of the gas transfer member to provide a suction effect is disclosed in, for example, Japanese Patent Laid-Open No. 6-101677. Disclosed. In this type of vacuum pump, a plurality of rotating shafts supporting a rotor as a gas transfer body are synchronously rotated using a gear mechanism. The gear mechanism is lubricated by lubricating oil stored in an oil bath in a housing that houses the gear mechanism. The lubricating oil is also used for lubricating a bearing for rotatably supporting the rotating shaft.

A lip seal is provided at a portion of a rotary shaft between the bearing and the casing in order to prevent the lubricating oil of the oil bath from leaking into a chamber (pump chamber) in a casing accommodating the rotor. You.

[0004] If the pressure difference before and after the lip seal is large, the lubricating oil in the oil bath tends to leak into the chamber in the casing that houses the rotor. In addition, the durability of the lip seal decreases, and the life of the lip seal shortens.

In the vacuum pump disclosed in Japanese Patent Application Laid-Open No. 9-151897, means for controlling a differential pressure between an exhaust pressure of gas exhausted from a discharge port of the vacuum pump and a pressure of a motor chamber, which is an oil existing area, is provided. Is disclosed. In this vacuum pump, nitrogen gas as a shaft sealing gas is supplied to a motor chamber, and an exhaust port of the shaft sealing gas in the motor chamber is connected to a discharge port. The control of the differential pressure is performed so as to prevent leakage of the lubricating oil from the oil bath to the chamber in the casing.

[0006]

However, control means using a pressure gauge, an electromagnetic on-off valve, and the like is required for controlling the differential pressure, and the cost of the vacuum pump increases. In addition, running cost is required for oil leakage countermeasures using shaft sealing gas.

SUMMARY OF THE INVENTION It is an object of the present invention to secure good sealing performance and extend the life of a lip seal in a vacuum pump at low cost.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention moves a gas transfer body in a pump chamber based on rotation of a rotary shaft, and transfers a gas by the operation of the gas transfer body to bring about a suction effect, thereby reducing the presence of oil. A lip ring for shaft sealing is disposed so as to slide on the peripheral surface of the rotary shaft between the region and the pump chamber, and passes from the oil existing region side to the pump chamber side via the peripheral surface of the rotary shaft. The present invention is directed to a vacuum pump designed to prevent oil leakage, and in the operation state of the vacuum pump, the pressure in the oil existing region is maintained at atmospheric pressure.

In a conventional general vacuum pump disclosed in Japanese Patent Application Laid-Open No. 9-151897, which does not perform special differential pressure control, the pressure in the oil existing region rises from the atmospheric pressure due to an increase in temperature with the operation of the vacuum pump. The pressure is increased, and the increased pressure increases the differential pressure before and after the rip ring. In the vacuum pump of the present invention, the temperature of the oil existing region rises in the operating state of the vacuum pump, but the pressure of the oil existing region in the heated state is maintained at the atmospheric pressure. Therefore, the differential pressure before and after the lip ring in the operation state of the vacuum pump becomes smaller than that of the conventional general vacuum pump.

According to the second aspect of the present invention, there is provided a pressure rise preventing means for preventing a pressure rise in the oil existing region due to a temperature rise accompanying the start of operation of the vacuum pump by releasing the pressure to an atmospheric pressure region outside the vacuum pump. A vacuum pump was configured.

An increase in pressure in the oil-existing region due to an increase in temperature accompanying the start of operation of the vacuum pump is prevented by releasing the pressure to the atmospheric pressure region, and the pressure in the oil-existing region is maintained at the atmospheric pressure.

According to the third aspect of the present invention, in the second aspect,
The pressure rise prevention means is a pressure release passage provided from the oil existing area to the atmospheric pressure area with respect to a wall of the housing forming the oil existing area.

The oil-existing region communicating with the atmospheric pressure region through the pressure release passage is always maintained at a pressure equivalent to the atmospheric pressure. According to a fourth aspect of the present invention, in the third aspect, it is possible to prevent oil leakage from the oil existing area to the atmospheric pressure area via the pressure release passage, and to release the oil from the oil existing area to the atmospheric pressure area. Oil leakage preventing means for allowing ventilation through the pressure passage is provided.

The oil-existing region communicating with the atmospheric pressure region via the pressure release passage is always maintained at a pressure equivalent to the atmospheric pressure. The oil leakage preventing means prevents oil in the oil existing area from leaking to the atmospheric pressure area via the pressure release passage.

According to a fifth aspect of the present invention, the pressure in the oil-existing region at normal temperature is adjusted so that the point of the pressure increase in the oil-existing region due to the temperature increase accompanying the start of operation of the vacuum pump is equivalent to atmospheric pressure. The pressure was lower than the atmospheric pressure.

When the vacuum pump is not operating, the pressure in the oil existing area is lower than the atmospheric pressure. In the operation state of the vacuum pump, the pressure in the oil existing region rises to the atmospheric pressure by the temperature rise.

According to a sixth aspect of the present invention, in the fifth aspect,
Raising the temperature of the oil-existing region to the temperature in the operating state of the vacuum pump, preventing a pressure increase in the oil-existing region due to the temperature rise by releasing the pressure to the atmospheric pressure region outside the vacuum pump, The oil-existing area was sealed when the temperature was in the above condition.

When the oil-existing area is sealed in the temperature state after the temperature rise, the oil-existing area has a pressure equivalent to the atmospheric pressure. When the oil-existing region is at normal temperature, the pressure in the oil-existing region becomes lower than the atmospheric pressure. The increase in the pressure in the oil existing region due to the temperature rise associated with the operation of the vacuum pump remains equivalent to the atmospheric pressure.

According to the present invention, a pressure release passage is provided in the wall of the housing forming the oil presence region from the oil presence region to the atmospheric pressure region, and the pressure release passage is opened and closed. An opening / closing means is provided, and the opening / closing means is opened so as to release a pressure increase from a pressure corresponding to the atmospheric pressure in the oil existing area. The increase in the pressure in the oil existing region due to the temperature rise associated with the operation of the vacuum pump remains equivalent to the atmospheric pressure.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a roots pump will be described below with reference to FIGS.

As shown in FIG. 1, the multi-stage roots pump 11
A front housing 13 is joined to a front end of the rotor housing 12 of the first embodiment, and a closing body 36 is joined to the front housing 13. A rear housing 14 is joined to the rear end of the rotor housing 12. The rotor housing 12 includes a cylinder block 15 and a plurality of chamber forming walls 16. As shown in FIG. 2B, the cylinder block 15 includes a pair of block pieces 17 and 18, and the chamber forming wall 16 includes a pair of wall pieces 161 and 162. As shown in FIG. 1, the space between the front housing 13 and the chamber forming wall 16, the space between the adjacent chamber forming walls 16, and the space between the rear housing 14 and the chamber forming wall 16 are pumps, respectively. Rooms 39, 40, 41, 42, 43
It has become.

A pair of rotating shafts 19 and 20 are rotatably supported by the front housing 13 and the rear housing 14 via radial bearings 21, 37, 22 and 38. Both rotating shafts 19 and 20 are arranged parallel to each other. The rotation shafts 19 and 20 are passed through the chamber forming wall 16.

A plurality of rotors 23, 24,
25, 26, 27 are integrally formed, and the same number of rotors 28, 29, 30, 31, 32 are integrally formed on the rotating shaft 20. The rotors 23 to 32 are
Are seen to be in the directions of the axes 191 and 201 of FIG. The thicknesses of the rotors 23, 24, 25, 26, and 27 are made smaller in this order.
The thicknesses of 8, 29, 30, 31, 32 become smaller in this order. The rotors 23 and 28 are housed in the pump chamber 39 in a state of being meshed with each other.
The pumps 4 and 29 are housed in the pump chamber 40 in a state of being engaged with each other. The rotors 25 and 30 are housed in the pump chamber 41 in a state of meshing with each other, and the rotors 26 and 31 are housed in the pump chamber 42 in a state of meshing with each other. The rotors 27 and 32 are housed in the pump chamber 43 in a state of being engaged with each other.

The gear housing 3 is mounted on the rear housing 14.
3 are assembled. The rotating shafts 19 and 20 penetrate through the rear housing 14 and protrude into the gear housing 33.
35 are fastened in a state where they are engaged with each other. An electric motor M is mounted on the gear housing 33. The driving force of the electric motor M is transmitted to the rotating shaft 1 via the shaft joint 44.
9, the rotating shaft 19 is rotated by the electric motor M in the direction of the arrow R1 in FIGS. 2 (a), 2 (b) and 3 (a). The rotation of the rotating shaft 19 is transmitted to the rotating shaft 20 via gears 34 and 35, and the rotating shaft 20 is
(B) and the rotation shaft 1 as shown by the arrow R2 in FIG.
9 rotates in the opposite direction. That is, the rotating shafts 19 and 20 are
It is rotated synchronously using the gears 34 and 35.

As shown in FIG. 2B, a passage 163 is formed in the chamber forming wall 16. An inlet 164 and an outlet 165 of the passage 163 are formed in the chamber forming wall 16. The adjacent pump chambers 39, 40, 41, 42, 43
It communicates via a passage 163.

As shown in FIG. 2A, the block piece 18
Is formed so that an inlet 181 communicates with the pump chamber 39. As shown in FIG.
Is formed so that a discharge port 171 communicates with the pump chamber 43. The gas introduced into the pump chamber 39 from the inlet 181 is rotated by the rotation of the rotors 23 and 28 to form the chamber forming wall 1.
6 from the inlet 164 via the passage 163 to the adjacent pump chamber 40 from the outlet 165. Hereinafter, similarly, the gas is transferred in the order of decreasing volume of the pump chamber, that is, in the order of the pump chambers 40, 41, 42, and 43. The gas transferred to the pump chamber 43 is discharged from the discharge port 171 to the outside. The rotors 23 to 32 are gas transfer bodies that transfer gas.

As shown in FIGS. 4A and 4B, seal housings 47 and 48 are formed around the rotation shafts 19 and 20 in the rear housing 14. Seal accommodation room 4
The lip seals 45 and 46 are accommodated in 7 and 48, respectively. The lip seals 45 and 46 include ring-shaped holding fittings 49 and 50 and rubber lip rings 51 and 52 held by the holding fittings 49 and 50 so as to cover a part of the holding fittings 49 and 50. . Rubber lip ring 5
The reference numerals 1 and 52 are curved toward the radial bearings 37 and 38. The inner peripheral side of the rubber lip ring 51 of the lip seal 45 accommodated in the seal accommodating chamber 47 contacts the peripheral surface 192 of the rotating shaft 19. The inner peripheral side of the rubber lip ring 52 of the lip seal 46 accommodated in the seal accommodating chamber 48 contacts the peripheral surface 202 of the rotating shaft 20.

As shown in FIG. 3B, a lubricating oil Y is stored in a gear housing chamber 331 in the gear housing 33, and the lubricating oil Y lubricates the gears 34 and 35. The gear housing chamber 331 of the gear housing 33 that houses the gears 34 and 35 that constitute the gear mechanism and the radial bearings 37 and 38 that are bearings is an oil existing area that stores the lubricating oil Y. The stored oil in the gear storage chamber 331 is
It is lifted up by the rotation of. The lubricating oil Y scraped up by the rotation of the gears 34, 35 lubricates the radial bearings 37, 38. The lubricating oil Y that has entered the seal accommodating chambers 47 and 48 from the ring gaps between the radial bearings 37 and 38 lubricates the rubber lip rings 51 and 52 of the lip seals 45 and 46.

As shown in FIGS. 3 (b) and 4 (b),
The pressure release port 53 is formed in the upper wall 332 of the gear housing 33. The pressure release port 53 includes a small-diameter portion 531 and a large-diameter female screw portion 532. Small diameter part 531 and female screw part 53
An air vent filter 55 is placed on the step with the second. The air vent filter 55 includes a polyester-based nonwoven fabric 551 and a porous film 552 made of polytetrafluoroethylene. The air vent filter 55 has air permeability and oil repellency. A male screw 54 is screwed into the female screw portion 532, and the air vent filter 55 is
And the step. A hexagonal hole-shaped pressure release hole 541 is formed through the shaft of the male screw 54.
The small-diameter portion 531 and the pressure-release hole 541 of the pressure-release port 53 form a pressure-release passage 56 that connects the gear housing chamber 331 to the atmospheric pressure region. The screwing of the male screw 54 into the female screw portion 532 is performed by fitting a hexagon wrench into the pressure release hole 541.

In the first embodiment, the following effects can be obtained. (1-1) With the operation of the vacuum pump, the temperature of the gear housing chamber 331, which is the oil existing area, rises. Since the gear storage chamber 331 communicates with the atmospheric pressure region via the pressure release passage 56, the pressure increase due to the temperature rise of the gear storage chamber 331 is released to the atmospheric pressure region via the pressure release passage 56. Therefore, the inside of the gear housing chamber 331 is always maintained at a pressure equivalent to the atmospheric pressure. That is, there is no pressure increase in the gear housing chamber 331 due to the temperature rise accompanying the operation of the vacuum pump. The configuration in which the gear housing chamber 331 is communicated with the atmospheric pressure region to maintain the pressure in the gear housing chamber 331 at atmospheric pressure corresponds to a conventional structure that does not perform a special differential pressure control disclosed in Japanese Patent Application Laid-Open No. 9-151897. The differential pressure across the lip rings 51, 52 is made smaller than in the case of a general vacuum pump. As a result, rubber lip rings 51 and 52 for preventing oil leakage from the gear housing chamber 331 to the pump chamber 43 side.
Sealability is improved. Also, rubber lip ring 5
The durability of the rubber lip ring 5 is improved.
1, 52 have a longer life.

(1-2) Japanese Patent Application Laid-Open No. Hei 9-151897 discloses a configuration in which a pressure increase in the gear housing chamber 331 due to a temperature increase accompanying the start of operation of the vacuum pump is prevented by releasing the pressure into the atmospheric pressure region outside the vacuum pump. Is much less expensive than the special differential pressure control arrangement as disclosed in US Pat.

(1-3) The lubricating oil Y flowing with the pressure release through the pressure release passage 56 enters the pressure release passage 56. The lubricating oil Y that has entered the pressure release passage 56 is
5 is trapped by the air vent filter 55 due to the oil repelling action. That is, the air vent filter 55 allows the flow of air, but blocks the passage of the lubricating oil Y. Therefore,
The lubricating oil Y in the gear housing chamber 331 does not leak outside the main body of the vacuum pump via the pressure release passage 56.

(1-4) The pressure release passage 56 is provided in the upper wall 332 of the gear housing 33, and the air vent filter 55 is provided in the middle of the upward pressure release passage 56. Lubricating oil Y trapped by air vent filter 55
Falls into the gear storage chamber 331 due to its own weight. The configuration in which the air vent filter 55 is provided in the upward pressure release passage 56 is optimal for preventing the lubricating oil Y from passing through the air vent filter 55. That is, the pressure release passage 56 facing upward is optimal as a place where the air vent filter 55 as the oil passage preventing means is installed.

(1-5) The air vent filter 55 having oil repellency is suitable as oil leakage preventing means. Next, a second embodiment of FIG. 5 will be described. The same components as those in the first embodiment are denoted by the same reference numerals.

A pressure release port 65 is formed in the upper wall 332 of the gear housing 33, and a sintered filter 66 is closely fitted in the pressure release port 65. The sintered filter 66 is made of copper,
It is formed by sintering metal particles such as stainless steel or ceramic particles. The sintered filter 66 allows ventilation through the pressure release port 65 between the gear housing chamber 331 and the atmospheric pressure region.

The lubricating oil Y flowing with the pressure release through the pressure release port 65 enters the upward pressure release port 65. Pressure relief port 65
The lubricating oil Y that has entered is trapped by the sintered filter 66 by the capturing action of the sintered filter 66. The lubricating oil Y trapped by the sintering filter 66 falls into the gear storage chamber 331 by its own weight and returns. Therefore, the lubricating oil Y in the gear housing chamber 331 does not leak outside through the pressure release port 65.

The sintered filter 66 obtained by sintering the metal particles or the ceramic particles does not absorb and adsorb the lubricating oil Y. Therefore, the lubricating oil Y trapped by the sintering filter 66 remains trapped by the sintered filter 66. It will not be. Therefore, the air permeability of the sintered filter 66 is not invalidated by the lubricating oil Y. The sintered filter 66 that does not absorb or adsorb the lubricating oil Y is suitable as an oil leakage preventing means that prevents oil passage and allows ventilation.

Next, a third embodiment shown in FIG. 6 will be described. The same components as those in the first embodiment are denoted by the same reference numerals. A screw hole 57 for pressure release is formed through the upper wall 332 of the gear housing 33, and the screw plug 5 is inserted into the screw hole 57.
8 is screwed. The head 581 of the screw stopper 58 and the upper wall 3
A seal ring 59 is interposed between the outer wall surface and the outer wall surface of the screw 32, and when the screw plug 58 is screwed into the screw hole 57,
The gear housing 331 is sealed from the outside of the gear housing 33. The pressure in the sealed gear housing 331 before the operation is lower than the atmospheric pressure. The pressure in the gear housing chamber 331 is reduced as follows.

After the screw stopper 58 is removed from the screw hole 57 and the gear housing chamber 331 is opened to the atmosphere, a test operation of the vacuum pump is performed. By the trial operation of the vacuum pump, the gear storage chamber 331
, The pressure of the gear housing chamber 331 opened to the atmosphere through the screw hole 57 remains equivalent to the atmospheric pressure. After the temperature of the gear storage chamber 331 reaches the maximum temperature,
The screw stopper 58 is screwed into the screw hole 57 so that the gear housing chamber 331 is formed.
Seal. After that, when the test operation of the vacuum pump is stopped, the pressure in the gear housing chamber 331 becomes lower than the atmospheric pressure as the temperature decreases.

When the vacuum pump is operated after the pressure in the gear housing chamber 331 is reduced as described above, the gear housing chamber 3 due to the temperature rise can be obtained.
The pressure increase in 31 remains at atmospheric pressure. Therefore, the third
Also in the embodiment, the same effect as the item (1-1) in the first embodiment can be obtained. Further, a configuration in which the pressure of the gear housing chamber 331 at normal temperature is made lower than the atmospheric pressure so that the reaching point of the pressure increase of the gear housing chamber 331 due to the temperature rise is equivalent to the atmospheric pressure is disclosed in Japanese Patent Application Laid-Open No. 9-151897. Compared to a special differential pressure control configuration as disclosed in the gazette,
It is much cheaper.

Next, a fourth embodiment shown in FIG. 7 will be described. The same components as those in the first embodiment are denoted by the same reference numerals. A screw hole 60 for pressure release is provided through an upper wall 332 of the gear housing 33, and a guide screw 61 is screwed into the screw hole 60. A pressure release hole 611 is formed through the shaft of the guide screw 61, and the plug 6 is inserted through the pressure release hole 611.
2 is slidably inserted. Head 62 of stopper 62
A seal ring 63 is interposed between 1 and the outer wall surface of the upper wall 332. A compression spring 64 is interposed between the guide screw 61 and the flange 622 on the distal end side of the plug 62. The compression spring 64 urges the stopper 62 toward the gear housing chamber 331. This bias has been reduced. A slit 623 is formed on the shaft peripheral surface of the plug 62 so as to pass through the guide screw 61. The slit 623 communicates the upper side and the lower side of the screw hole 60 separated by the guide screw 61.

When the head 621 of the stopper 62 is in contact with the seal ring 63, the gear housing 331 is in a sealed state. When the pressure in the gear storage chamber 331 becomes higher than the atmospheric pressure, and the pressure difference between the pressure in the gear storage chamber 331 and the atmospheric pressure via the head 621 of the plug 62 exceeds the spring force of the compression spring 64, the plug is stopped. The head 621 of the cylinder 62 is separated from the seal ring 63. When the head 621 separates from the seal ring 63,
The gear housing chamber 331 communicates with the atmospheric pressure region through the screw hole 60 and the slit 623. Therefore, even in a state where the temperature of the gear housing chamber 331 is increased with the operation of the vacuum pump,
The pressure in the gear housing 331 is maintained at atmospheric pressure.

After the operation of the vacuum pump is stopped, the gear housing 33
The pressure in 1 is reduced to below the atmospheric pressure by the temperature decrease. When the pressure difference between the pressure in the gear housing chamber 331 and the atmospheric pressure via the head 621 of the plug 62 becomes smaller than the spring force of the compression spring 64, the plug 6
The second head 621 is in contact with the seal ring 63, and the gear housing 331 is sealed.

In the fourth embodiment, the same effects as in the items (1-1) and (1-2) in the first embodiment can be obtained. Next, a fifth embodiment of FIG. 8 will be described. The same components as those in the first embodiment are denoted by the same reference numerals.

A pressure release screw hole 60 is formed in the upper wall 332 of the gear housing 33, and a purge valve 67 is screwed into the screw hole 60. The ball valve 68 in the purge valve 67 is located at the position indicated by the solid line in FIG.
1 and a vent hole 6 communicating with the atmosphere.
The communication with 72 is cut off. The ball valve 68 connects the passage 671 and the vent hole 672 at the position indicated by the dashed line in FIG. The ball valve 68 is urged toward the dashed line position in FIG. 8 by a compression spring 69 having a weak spring force.

When the pressure in the gear storage chamber 331 is equal to or higher than the atmospheric pressure, the ball valve 68 is disposed at the position indicated by a chain line in FIG.
The pressure in the gear housing chamber 331 is maintained at a pressure equivalent to the atmospheric pressure. Therefore, the operation of the vacuum pump causes the gear chamber 3
Even in the state where the temperature of the gear 31 has risen, the pressure in the gear housing chamber 331 is maintained at the atmospheric pressure.

After the operation of the vacuum pump is stopped, the gear housing 33
The pressure in 1 is reduced to below the atmospheric pressure by the temperature decrease. When the pressure difference between the pressure in the gear housing chamber 331 and the atmospheric pressure via the ball valve 68 becomes lower than the spring force of the compression spring 69, the ball valve 6
8 is disposed at the position indicated by the solid line in FIG. 8, and the gear housing chamber 331 is sealed.

In the fifth embodiment, the same effects as in the fourth embodiment can be obtained. In the present invention, the following embodiments are also possible. (1) In the second embodiment, the pressure of the oil-existing region at normal temperature is adjusted so that the reaching point of the pressure increase in the oil-existing region due to the temperature increase accompanying the start of operation of the vacuum pump is equivalent to the atmospheric pressure. In order to make the pressure lower than the atmospheric pressure, the screw plug 58 is removed in the room under the low pressure, and the screw plug 58 is attached.

(2) The present invention is applied to a vacuum pump other than a roots pump. Inventions other than those described in the claims that can be grasped from the above-described embodiment will be described below.

[1] The vacuum pump according to claim 4, wherein the oil leakage preventing means is an air vent filter having air permeability and oil repellency. [2] A pressure release passage is provided on the wall of the oil housing that forms the oil presence area so as to extend from the oil presence area to the atmospheric pressure area. The vacuum pump according to claim 6, wherein the pressure passage is closed with a stopper.

[3] The shaft seal in the vacuum pump according to any one of claims 1 to 7, wherein the oil existing area is an area for accommodating a bearing for rotatably supporting the rotating shaft. Construction.

[4] In the vacuum pump, a plurality of the rotating shafts are arranged in parallel, a rotor is arranged on each of the rotating shafts, and rotors on adjacent rotating shafts are engaged with each other.
The vacuum pump according to any one of claims 1 to 7, wherein the vacuum pump is a roots pump including a plurality of pump chambers accommodating a plurality of rotors meshing with each other as a set, or a single pump chamber. Shaft sealing structure.

[5] The vacuum pump according to the item [4], wherein the plurality of rotating shafts are synchronously rotated by using a gear mechanism, and the oil existing area is an area for accommodating the gear mechanism. Shaft sealing structure.

[0054]

As described above in detail, according to the present invention, in the operation state of the vacuum pump, the pressure in the oil existing region is maintained at a level equivalent to the atmospheric pressure. An excellent effect is obtained in that the life of the lip seal can be extended at a low cost.

[Brief description of the drawings]

FIG. 1 shows a multi-stage roots pump 11 according to a first embodiment.
FIG.

FIG. 2A is a sectional view taken along line AA of FIG. (B) is FIG.
BB sectional drawing of FIG.

FIG. 3A is a sectional view taken along line CC of FIG. 1; (B) is FIG.
FIG.

FIG. 4A is a sectional view taken along line EE of FIG. 3B. (B)
FIG. 4 is a sectional view taken along line FF of FIG.

FIG. 5 is an enlarged side sectional view of a main part showing a second embodiment.

FIG. 6 is an enlarged side sectional view of a main part showing a third embodiment.

FIG. 7 is an enlarged side sectional view of a main part showing a fourth embodiment.

FIG. 8 is an enlarged side sectional view of a main part showing a fifth embodiment.

[Explanation of symbols]

11 Multi-stage roots pump which is a vacuum pump. 19, 20
…Axis of rotation. 192, 202 ... peripheral surface. 23, 24, 25,
26, 27, 28, 29, 30, 31, 32 ... rotors serving as gas transfer bodies. Reference numeral 33 denotes a gear housing serving as a housing forming an oil existing area. Reference numeral 331 denotes a gear storage chamber serving as an oil existing area. 39, 40, 41, 42, 43 ... Pump room.
51, 52 ... rip ring. 55 ... Air vent filter which serves as oil leakage prevention means. 66: A sintered filter serving as an oil leakage preventing means. 56 ... a pressure release passage serving as a pressure rise preventing means.

Continued on the front page (72) Inventor Yuji Hashimoto 2-1-1 Toyota-cho, Kariya-shi, Aichi Pref. Inside Toyota Industries Corporation (72) Inventor Masahiro Kawaguchi 2-1-1 Toyota-cho, Kariya-shi, Aichi Pref. F term in Toyota Industries Corporation (reference) 3H003 AA01 AC04 BC00 3H029 AA06 AA09 AA18 AB06 BB16 BB44 CC15 CC16 CC17 CC20 CC25 CC32

Claims (7)

[Claims] 1. A gas transfer unit in a pump chamber is moved based on the rotation of a rotating shaft, and a gas is transferred by an operation of the gas transfer unit to bring about a suction action. A vacuum in which a lip ring for a shaft seal is disposed so as to be in sliding contact with the peripheral surface of the rotary shaft, and oil is prevented from leaking from the oil-existing region side to the pump chamber side via the peripheral surface of the rotary shaft. A vacuum pump, wherein a pressure in the oil-existing region is maintained at an atmospheric pressure when the vacuum pump is in an operating state. 2. A gas transfer unit in a pump chamber is moved based on rotation of a rotating shaft, and a gas is transferred by an operation of the gas transfer unit to bring about a suction action. A vacuum in which a lip ring for a shaft seal is disposed so as to be in sliding contact with the peripheral surface of the rotary shaft, and oil is prevented from leaking from the oil-existing region side to the pump chamber side via the peripheral surface of the rotary shaft. A vacuum pump, comprising: a pressure rise preventing means for preventing a pressure increase in the oil existing region due to a temperature rise accompanying the start of operation of the vacuum pump by releasing the pressure to an atmospheric pressure region outside the vacuum pump. 3. The pressure release passage according to claim 2, wherein the pressure rise preventing means is a pressure release passage provided from the oil existing area to the atmospheric pressure area with respect to a wall of the housing forming the oil existing area. The described vacuum pump. 4. An oil leak from said oil existence region to said atmospheric pressure region via said pressure release passage is prevented, and ventilation from said oil existence region to said atmospheric pressure region via said pressure release passage is prevented. 4. The vacuum pump according to claim 3, further comprising a means for preventing oil leakage. 5. A gas transfer unit in a pump chamber is moved based on rotation of a rotating shaft, and a gas is transferred by an operation of the gas transfer unit to bring about a suction action. A vacuum in which a lip ring for a shaft seal is disposed so as to be in sliding contact with the peripheral surface of the rotary shaft, and oil is prevented from leaking from the oil-existing region side to the pump chamber side via the peripheral surface of the rotary shaft. In the pump, the ultimate point of the pressure rise in the oil presence region due to the temperature rise accompanying the start of operation of the vacuum pump is equivalent to the atmospheric pressure,
A vacuum pump in which the pressure in the oil existing region in a normal temperature state is lower than atmospheric pressure. 6. An oil-existing region is heated to a temperature in an operating state of a vacuum pump, and a pressure increase in the oil-existing region due to the temperature rise is prevented by releasing the pressure to an atmospheric pressure region outside the vacuum pump. The vacuum pump according to claim 5, wherein the oil-existing region is sealed when the temperature is after the temperature rise. 7. A gas transfer body in a pump chamber is moved based on rotation of a rotating shaft, and a gas is transferred by an operation of the gas transfer body to produce a suction effect, and the gas transfer body between the oil existing area and the pump chamber is provided. A vacuum in which a lip ring for a shaft seal is disposed so as to be in sliding contact with the peripheral surface of the rotary shaft, and oil is prevented from leaking from the oil-existing region side to the pump chamber side via the peripheral surface of the rotary shaft. In the pump, a pressure release passage is provided to a wall of the housing forming the oil presence region so as to reach the atmospheric pressure region from the oil presence region, and an opening / closing means for opening and closing the pressure release passage is provided.
A vacuum pump wherein the opening / closing means is opened so as to release a pressure increase from a pressure corresponding to the atmospheric pressure in the oil existing area.