JP2002115688A - Cooling structure in vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently cool oil cooling a material to be cooled in a vacuum pump. SOLUTION: Gears 34, 35 are fixed while they mesh each other in protruding end parts of rotary shafts 19, 20 protruding into a gear housing 33. The rotary shafts 19, 20 are rotated in synchronization by the gears 34, 35. A thinned recessed part 473 is provided on an inner face of a bottom wall 472 of a peripheral wall 47 of the gear housing 33 storing the gears 34, 35. A cooling device 50 is attached to an outer face of a section of the bottom wall 472 corresponding to the thinned recessed part 473.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for a vacuum pump which moves a gas transfer member in a pump chamber based on rotation of a rotating shaft and transfers gas by the operation of the gas transfer member to provide a suction effect. It is.

[0002]

2. Description of the Related Art In a vacuum pump disclosed in JP-A-2-157490 and JP-A-6-101677,
Two adjacent rotors are rotated in a meshed state. The rotating operation of the two rotors rotating while meshing transfers gas. One of the rotation axes of the rotor is
The driving force is obtained from the motor, and the other rotating shaft receives the driving force from the one rotating shaft via a gear mechanism.

[0003] Lubricating oil is stored in a housing that houses the gear mechanism, and the stored oil lubricates the gear mechanism. In order to prevent this lubricating oil from leaking into the pump chamber, a lip seal is provided between the housing wall and a portion of the rotary shaft that penetrates the housing wall separating the housing chamber of the gear mechanism and the pump chamber. .

[0004] In a vacuum pump, heat is generated during the process of compressing exhaust gas, and the generated heat raises the temperature of the main body of the vacuum pump. The lip seal deteriorates when exposed to a high-temperature environment, and the sealing function of the lip seal deteriorates. Therefore, measures are taken to directly cool the lip seal with oil for lubricating the gear mechanism, or to indirectly cool the lip seal by cooling the rotating shaft with the oil.

[0005]

In order to continuously cool the object to be cooled, it is necessary to take heat from the oil which has taken heat from the object to be cooled and discharge it to the outside of the main body of the vacuum pump. That is,
It is necessary to cool the oil that has cooled the object to be cooled. This heat release is achieved by transferring heat from the oil to the outer wall of the housing containing the gear mechanism. However, the outer wall of the housing that houses the gear mechanism is thick, and the heat transfer efficiency at the outer wall is not good. Therefore, the efficiency of cooling the oil is low, and the cooling target cannot be efficiently cooled. Such poor cooling efficiency leads to early deterioration of the lip seal.

An object of the present invention is to efficiently cool oil for cooling an object to be cooled in a vacuum pump.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a vacuum pump which moves a gas transfer body in a pump chamber based on rotation of a rotating shaft and transfers gas by the operation of the gas transfer body to provide a suction action. According to the first aspect of the present invention, the rotating shaft projects into an oil existing region in the oil housing that forms a cooling oil existing region, and one of the peripheral walls of the oil housing surrounding the axis of the rotating shaft. A concave portion for thinning the wall was provided on the inner surface of the portion.

The thickness of the portion of the peripheral wall provided with the lightening recess is
The thickness of the peripheral wall is smaller than the thickness of the other part of the peripheral wall, and the heat transfer efficiency at the part of the peripheral wall provided with the concave portion is improved. The improvement of the heat transfer efficiency in a part of the peripheral wall increases the efficiency of cooling the oil in the oil housing. Since the entire peripheral wall of the oil housing is not made thinner, it is easy to secure necessary strength of the oil housing.

According to the invention of claim 2, in claim 1,
A part of the peripheral wall of the oil housing is used as a bottom wall, and the concave portion is provided on the bottom wall. Oil in the oil housing tends to go to the bottom wall. Therefore, a configuration in which the wall thickness of the bottom wall is reduced is optimal for improving the efficiency of cooling oil.

According to a third aspect of the present invention, in any one of the first and second aspects, the oil-existing region is separated from the pump chamber by a partition, and the rotating shaft passes through the partition. A contact-type sealing means for shaft sealing is interposed between the rotary shaft and the partition wall so as to protrude into the oil existing area.

[0011] The deterioration of the contact-type sealing means due to heat is suppressed by directly cooling the contact-type sealing means with oil, or indirectly cooling the contact-type sealing means by cooling the rotating shaft with the oil. .

According to a fourth aspect of the present invention, in any one of the first to third aspects, the vacuum pump arranges a plurality of the rotating shafts in parallel and arranges a rotor on each of the rotating shafts. A multistage vacuum pump in which rotors on adjacent rotary shafts are meshed with each other and a plurality of pump chambers accommodating a plurality of meshed rotors as a set are arranged in the axial direction of the rotary shaft. The volume of the pump chamber becomes smaller in the order of approaching the partition wall along the axial direction of the rotary shaft, and the gas is transferred through the plurality of pump chambers in the order of the smaller volume. The pump chamber adjacent to the oil existing area was a pump chamber having a minimum volume.

Such a vacuum pump is suitable as an object to which the present invention is applied. In the invention of claim 5, in claim 4, 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, and the oil-existing area is The oil for lubricating the gear mechanism is stored, and oil scraping means for scraping the stored oil so as to lubricate the gear mechanism is provided in the oil existing area.

Oil for lubricating the gear mechanism is used for cooling. In a sixth aspect of the present invention, in any one of the first to fifth aspects, a cooler is provided on a surface of the oil housing corresponding to the recess.
The cooler cools a surface of the oil housing.

The configuration in which the portion of the peripheral wall of the oil housing corresponding to the lightening recess is cooled by the cooler further enhances the heat transfer efficiency at the portion of the peripheral wall.

[0016]

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. 1A, a front housing 13 is joined to a front end of a rotor housing 12 of the multi-stage roots pump 11, and
The sealing body 36 is joined to the. Rotor housing 1
A rear housing 14 as a partition is joined to the rear end of 2. 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 is composed of a pair of block pieces 17 and 18, and the chamber forming wall 16 is formed of a pair of wall pieces 16.
1,162. As shown in FIG. 1A, the space between the front housing 13 and the room forming wall 16, the space between the adjacent room forming walls 16, and the space between the rear housing 14 and the room forming wall 16 are: , Pump chambers 39, 4 respectively
0, 41, 42 and 43.

A pair of rotating shafts 19, 20 are rotatably supported by the front housing 13 and the rear housing 14 via radial bearings 21, 37, 22, 38 as bearings. 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 serving as gas transfer bodies are integrally formed on the rotating shaft 19, and the same number of rotors 28, 29, 30, are formed on the rotating shaft 20.
31 and 32 are integrally formed. Rotors 23-32
Have the same shape and the same size when viewed in the direction of the axes 191 and 201 of the rotating shafts 19 and 20. Rotors 23, 24, 2
The thicknesses of the rotors 5, 26, 27 are reduced in this order, and the thicknesses of the rotors 28, 29, 30, 31, 32 are also reduced to this extent. The rotors 23 and 28 are housed in the pump chamber 39 in a state of being engaged with each other with a slight gap therebetween.
Similarly, the pumps 4 and 29 are housed in the pump chamber 40 in a mutually engaged state. Hereinafter, similarly, the rotors 25 and 30 are in the pump chamber 41, the rotors 26 and 31 are in the pump chamber 42,
The rotors 27 and 32 are housed in the pump chamber 43, respectively.

A gear housing 33 as an oil housing is screwed on the rear housing 14 (shown in FIG. 3).
Are joined by tightening. Rear housing 1
4 and the edge 47 of the peripheral wall 47 of the gear housing 33.
1, a seal ring 48 is interposed.

The rotating shafts 19 and 20 are connected to the rear housing 14.
, And protrudes into the gear housing 33, and the protruding ends 192, 202 of the respective rotating shafts 19, 20 have gears 3.
4, 35 are fastened in a state where they are engaged with each other. An electric motor M is mounted on an end wall 49 of the gear housing 33. The driving force of the electric motor M is transmitted to the rotating shaft 19 via the shaft joint 10, and the rotating shaft 19 is rotated by the electric motor M in the direction of arrow R <b> 1 in FIGS. 2A, 2 </ b> B, and 2 </ b> C. Is done. The rotating shaft 20 obtains a driving force from the electric motor M via the gears 34 and 35, and the rotating shaft 20 is rotated by the rotating shaft 19 as shown by an arrow R2 in FIGS. 2 (a), 2 (b) and 2 (c). And rotate in the opposite direction.

As shown in FIG. 3, lubricating oil Y is stored in the bottom of a gear housing chamber 331 that houses a gear mechanism composed of gears 34 and 35, and a part of the gears 34 and 35 is immersed. Therefore, the lubricating oil Y is swept up by the rotation of the gears 34 and 35. The gear mechanism including the gears 34 and 35 serves as an oil scraping means for scraping the stored oil. The lubricating oil Y lubricates the gears 34, 35 and the radial bearings 37, 38. The rear housing 14 serves as a partition wall that separates the pump chamber 43 from the gear housing chamber 331 which is an oil existing area. The lubricating oil Y is supplied to the rotating shafts 19 and 2
The 0 protruding ends 192 and 202 are cooled.

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 flows in the order of decreasing the volume of the pump chamber, that is, the pump chamber 4
The transport is performed in the order of 0, 41, 42, 43. Pump room 43
The gas transferred to the discharge port 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. 1A and 1B, rubber lip seals 44 and 45 serving as contact-type sealing means are disposed at the protruding ends 192 and 202 of the rotating shafts 19 and 20, respectively. . The lip seals 44, 45 are
A sliding action is brought into sliding contact with the peripheral surfaces of the protruding end portions 192 and 202, which are the protruding portions of. The lubricating oil Y reaches the lip seals 44 and 45 via the gap between the inner ring and the outer ring of the radial bearings 37 and 38. Lip seal 44,
45 is cooled by being lubricated by the lubricating oil Y.

As shown in FIGS. 3 and 4, the rotating shaft 19,
The bottom wall 4 of the peripheral wall 47 surrounding the 20 axes 191 and 201
A lightening recess 473 is provided on the inner surface of 72. The lightening recess 473 is provided so as to remove the vicinity of the edge 471 of the peripheral wall 47 and the end wall 49.

A cooler 50 is provided on the outer surface of the bottom wall 472. The cooler 50 has a supply pipe 501 and a discharge pipe 50.
2 are connected. The supply pipe 501 sends a coolant from a coolant supply source (not shown) to the cooler 50, and the discharge pipe 502
Recirculates the coolant passing through the cooler 50 to the coolant supply source. The cooling liquid passing through the cooler 50 is supplied to the bottom wall 472.
Cool the outer surface of the.

In the first embodiment, the following effects can be obtained. (1-1) The thickness of the portion of the peripheral wall 47 where the lightening concave portion 473 is provided is smaller than the thickness of the other portion of the peripheral wall 47 without the lightening concave portion 473. Since the heat transfer efficiency of the wall becomes higher as the wall thickness becomes smaller, the heat transfer efficiency at the portion of the peripheral wall 47 where the lightening recess 473 is provided is reduced.
The heat transfer efficiency is higher than the heat transfer efficiency in other parts of the peripheral wall 47 without the 73. The improvement of the heat transfer efficiency in a part of the peripheral wall 47 increases the efficiency of cooling the oil in the gear housing 33 serving as the oil housing. The improvement in the efficiency of cooling the oil in the gear housing 33 results in efficient cooling of the lip seals 44 and 45, which are contact-type sealing means for the shaft seal, and extends the life of the lip seals 44 and 45.

(1-2) The lightening recess 473 is provided only on the bottom wall 472 which is a part of the peripheral wall 47. The presence of the lightening recess 473 does not reduce the thickness of the entire peripheral wall 47 of the gear housing 33, so that the necessary strength of the gear housing 33 can be easily secured.

(1-3) The oil in the gear housing 33 accumulates on the bottom of the gear housing chamber 331, that is, on the inner surface of the bottom wall 472. The stored oil that accumulates on the inner surface of the bottom wall 472 contacts the surface of the lightening recess 473 and the heat of the stored oil is reduced by the lightening recess 473.
Through the surface of the bottom wall 472 having a small wall thickness. Therefore, the configuration in which the lightening recess 473 is provided on the inner surface of the bottom wall 472 where the stored oil exists is optimal for improving the efficiency of cooling the lubricating oil Y.

(1-4) Lip seal 4 interposed between rear housing 14 as a partition and rotating shafts 19 and 20
The deterioration of the lip seals 44 and 45 due to the heat of the lip seals 44 and 45 is performed by directly cooling the lip seals 44 and 45 with the lubricating oil Y or by cooling the protruding ends 192 and 202 of the rotating shafts 19 and 20 with the lubricating oil Y. By cooling indirectly.

(1-5) Rubber lip seals 44 and 45
Is extremely excellent in close contact with the peripheral surfaces of the rotating shafts 19 and 20, but the durability is extremely reduced without lubrication with the lubricating oil Y. The rubber lip seals 44 and 45 which are lubricated by the lubricating oil Y and subjected to a cooling action are contact-type sealing means capable of securing high durability and high sealing performance.

(1-6) The pump chamber 43 is a pump chamber having a minimum volume adjacent to the gear housing chamber 331 via the rear housing 14 serving as a partition. The pump chamber 43 having the minimum volume is a place where the temperature is highest. Therefore, the rear housing 1
The temperatures of the protruding ends 192 and 202 of the shaft 4 and the rotating shafts 19 and 20 are also likely to be high, and the lip seals 44 and 45 are exposed to a severe high temperature environment. Therefore, the lip seals 44, 4
5 is extremely important, and the present invention is particularly suitable for application to the multi-stage roots pump 11 having the lip seals 44 and 45, which are important cooling targets.

(1-7) The cooler 50 for cooling the outer surface of the bottom wall 472 indirectly cools the lubricating oil Y in the gear housing 33 via the portion of the bottom wall 472 corresponding to the recess 473. . The configuration in which the portion of the bottom wall 472 corresponding to the lightening concave portion 473 is cooled by the cooler 50 promotes heat transfer at the portion of the bottom wall 472 corresponding to the lightening concave portion 473, and the bottom wall corresponding to the lightening concave portion 473. The heat transfer efficiency at the portion 472 is further enhanced.

Next, a second embodiment shown in FIGS. 5A and 5B will be described. The same components as those in the first embodiment are denoted by the same reference numerals. The bottom wall 472 of the peripheral wall 47 of the gear housing 33 is provided with a plurality of lightening recesses 474 and 475 (two in the present embodiment). Lightening recess 47
The partition wall 476 that partitions the rotation shafts 19, 2
0 is along the direction of the axes 191 and 201.

The same effects as in the first embodiment can be obtained in the second embodiment. The partition wall 476 contributes to securing the strength of the gear housing 33. Therefore, the partition wall 476 is formed on the bottom wall 4 corresponding to the lightening concave portions 474 and 475.
It is possible to make the wall thickness of the portion 72 even thinner than in the case of the first embodiment.

Next, a third embodiment shown in FIGS. 6A and 6B will be described. The same components as those in the first embodiment are denoted by the same reference numerals. The bottom wall 472 of the peripheral wall 47 of the gear housing 33 is provided with a plurality of lightening recesses 477 and 478 (two in the present embodiment). Lightening recess 47
The partition wall 479 for partitioning the rotation shafts 19, 2
It is along the direction orthogonal to the 0 axes 191 and 201.

The same effects as in the second embodiment can be obtained in the third embodiment. The scraping resistance when the stored oil at the bottom of the gear housing 33 is scraped by the gears 34 and 35 causes power loss of the multi-stage roots pump 11. The partition wall that intersects with the rotation direction of the gears 34 and 35 becomes a resistance to the flow of the stored oil, and the above-described lifting resistance increases. The configuration in which the partition wall 479 extends along the direction orthogonal to the axes 191 and 201 of the rotating shafts 19 and 20 is effective in suppressing the increase in the scraping resistance due to the presence of the partition wall.

In the present invention, the following embodiments are also possible. (1) A recess is provided on the inner surface of the side wall of the peripheral wall 47 of the gear housing 33. (2) A recess is provided on the inner surface of the upper wall of the peripheral wall 47 of the gear housing 33. (3) Three or more concave portions are provided on the inner surface of the peripheral wall 47 of the gear housing 33.

The inventions other than those described in the claims which can be grasped from the above embodiment will be described below. (1) The set position of the lightening recess is disengaged from a portion where the oil housing is connected to another member.
A cooling structure in the vacuum pump according to claim 6.

In this case, the connecting portion is connected to the edge 47 of the peripheral wall 47.
It is one.

[0042]

As described above in detail, according to the present invention, the rotation shaft is projected into the oil existing region in the oil housing which forms the cooling oil existing region, and the oil surrounding the axis of the rotation shaft is provided. The provision of the concave portion for thinning the wall on a part of the inner wall of the peripheral wall of the housing provides an excellent effect that the oil for cooling the object to be cooled in the vacuum pump can be efficiently cooled.

[Brief description of the drawings]

FIG. 1 shows a first embodiment, in which (a) is a plan sectional view of the whole multi-stage roots pump 11; (B) Lip seal 4
4 and 45 are enlarged plan sectional views.

FIG. 2A is a sectional view taken along line AA of FIG. (B) is FIG.
BB sectional drawing of FIG. (C) is a sectional view taken along line CC of FIG. 1.

FIG. 3 is a sectional view taken along line DD of FIG. 1;

FIG. 4 is a sectional view taken along line EE of FIG. 3;

FIG. 5 shows a second embodiment, in which (a) is a sectional view.
(B) is a sectional view taken along line FF of (a).

FIG. 6 shows a third embodiment, in which (a) is a sectional view.
(B) is GG sectional drawing of (a).

[Explanation of symbols]

11 Multi-stage roots pump which is a vacuum pump. 14. Rear housing serving as a partition. 19, 20 ... rotating shaft. 191,
201 ... axis. 192, 202: Protruding ends of the rotating shaft. 2
3 to 32: rotors serving as gas transfer bodies. Reference numeral 33 denotes a gear housing serving as an oil housing. Reference numeral 331 denotes a gear storage chamber serving as an oil existing area. 34, 35 ... gears constituting a gear mechanism.
39-43 ... Pump room. 44, 45: Lip seals serving as contact-type sealing means. 47 ... peripheral wall. 472 ... Bottom wall. 47
3,474,475,477,478... 5
0 ... cooler. Y: Lubricating oil.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hitoshi Masaji 2-1-1 Toyota-machi, Kariya-shi, Aichi F-term in Toyota Industries Corporation (reference) 3H029 AA06 AA17 AA21 AB06 BB12 CC09 CC25 CC26 CC48 CC56

Claims (6)

[Claims] 1. A vacuum pump for moving a gas transfer body in a pump chamber based on rotation of a rotating shaft and transferring a gas by an operation of the gas transfer body to provide a suction action, wherein a region where a cooling oil exists is formed. In a vacuum pump, the rotary shaft protrudes into an oil existing area in an oil housing to be provided, and a concave portion for thinning a wall is provided on a part of an inner surface of a peripheral wall of the oil housing surrounding the axis of the rotary shaft. Cooling structure. 2. A cooling structure in a vacuum pump according to claim 1, wherein a part of a peripheral wall of said oil housing is used as a bottom wall, and said lightening recess is provided in said bottom wall. 3. The oil-existing region is separated from the pump chamber by a partition, the rotating shaft penetrates the partition and protrudes into the oil-existing region, and a shaft is provided between the rotating shaft and the partition. 3. The cooling structure of a vacuum pump according to claim 1, further comprising a contact-type sealing means for sealing. 4. The vacuum pump according to claim 1, wherein a plurality of said rotating shafts are arranged in parallel, a rotor is arranged on each of said rotating shafts, rotors on adjacent rotating shafts are meshed with each other, and said vacuum pump is in a state of being meshed with each other. A multi-stage vacuum pump in which a plurality of pump chambers accommodating a plurality of rotors as one set are arranged in the axial direction of the rotating shaft, and the volumes of the plurality of pump chambers are formed in the partition along the axial direction of the rotating shaft. The gas is transferred through the plurality of pump chambers in the order of decreasing volume, and the pump chamber adjacent to the oil existing area is a pump chamber having a minimum volume. A cooling structure in the vacuum pump according to any one of claims 1 to 3. 5. A plurality of said rotating shafts are synchronously rotated by using a gear mechanism, said oil present area is an area for accommodating said gear mechanism, and said oil present area lubricates said gear mechanism. 5. The cooling structure according to claim 4, wherein oil for storing the oil is stored in the oil-existing area, and oil-raising means for raking the stored oil so as to lubricate the gear mechanism is provided in the oil-existing region. 6. A cooling device is provided on a surface of the oil housing corresponding to the hollow portion, and the cooling device cools a surface of the oil housing. A cooling structure in the vacuum pump described in the paragraph.