WO2020255300A1

WO2020255300A1 - Vacuum pump

Info

Publication number: WO2020255300A1
Application number: PCT/JP2019/024325
Authority: WO
Inventors: 航己岩下; 幸太郎茂木
Original assignee: 樫山工業株式会社
Priority date: 2019-06-19
Filing date: 2019-06-19
Publication date: 2020-12-24
Also published as: CN114096753B; CN114096753A; KR20210134772A; KR102610994B1; JP7152073B2; JPWO2020255300A1

Abstract

In a vacuum pump (1), side plates (6, 7) defining both ends of a pump chamber (2) comprise plates having a divided structure, formed from first and second plates (20, 30). Heater installation slits (8, 9) are formed between the first and second plates (20, 30), and film heaters (10, 11) are fitted into the slits (8, 9), in surface contact with the first plate (20) on the pump chamber side. Since the side plates (6, 7) are heated directly from the inside by means of the film heaters (10, 11), the heating efficiency of wall parts inside the pump chamber can be efficiently increased, and adhesion and deposition of product can be efficiently suppressed.

Description

Vacuum pump

The present invention relates to a vacuum pump provided with a heater for suppressing the accumulation of products and the like contained in exhaust gas on the inner wall surface of the pump.

Vacuum pumps such as mechanical booster pumps do not use a sealing liquid in the pumping part, and a pair of pump rotors rotate in the opposite direction without contact while maintaining a minute gap along the peripheral wall of the pump chamber, and are constant. The structure is such that a large amount of gas is transported from the intake side to the exhaust side to obtain a vacuum. This type of vacuum pump is capable of vacuum exhaust with less contamination by oil vapor, and is used for the purpose of creating a clean vacuum space in semiconductor manufacturing processes such as etching and CVD.

The gas discharged from the chamber or the like in the semiconductor manufacturing process or the like contains by-products or the like secondary to the process. When the gas generated by the vacuum pump is sucked and discharged, the products and the like contained in the sucked gas may solidify and adhere to and accumulate on the inner wall of the pump. For example, in the pump chamber, products may accumulate or stick to the surfaces of the side plates at both ends of the pump chamber facing the end face of the pump rotor at minute intervals. The rotation of the pump rotor stops due to the accumulation and fixed matter clogging the minute gaps, the rotational driving force of the pump rotor increases, the motor that rotates and drives the pump rotor becomes an excessive current, and the pump stops. It causes harmful effects such as pumping. In addition, when the pump is restarted after the pump is stopped, the pump may not be restarted due to accumulations and sticking substances.

Therefore, in such a vacuum pump used for gas discharge, the interior wall of the pump is heated by a heater to suppress the generation of accumulated substances and fixed substances. Conventionally, in general, a jacket heater is wound around the outer peripheral surfaces of both ends of the pump case, and the inner wall of the pump is indirectly heated from the outside. In Patent Document 1, in a turbo molecular pump, a pipe is embedded in a pump base which is one end of a pump case, a heater is arranged in the pipe, and the pump base is heated from the inside to obtain a solidified gas in the pump chamber. It suppresses deposition.

Japanese Unexamined Patent Publication No. 2014-95315

The method of wrapping a heater around the outer peripheral surface of the vacuum pump and indirectly heating the inner wall of the pump from the outside has a problem of poor heating efficiency. Further, in the structure in which the heater is embedded inside the parts constituting the pump case as described in Patent Document 1, the structure of the heater embedded portion becomes complicated, and the work efficiency of the work of embedding the heater in the heater embedded portion is complicated. There is also a problem that it is bad. Further, when the heater is embedded in the pump case to perform internal heating, a portion other than the pump interior wall portion is also heated. For example, when a bearing portion or the like supporting the pump rotor is arranged adjacent to the heater embedded position, there is an adverse effect that such a portion is also heated.

In view of these points, an object of the present invention is to provide a vacuum pump capable of easily assembling a heater and efficiently heating a pump interior wall portion.

In order to solve the above problems, the vacuum pump of the present invention has a tubular casing, a pair of side plates that block axially both side openings in the casing, and a side plate inside the casing. It has a pump chamber formed in, and a heater attached to at least one side plate, and the side plate to which the heater is attached is from the side opposite to the first plate and the pump chamber in the axial direction. A second plate superposed on the first plate and a slit formed between the first plate and the second plate are provided, and the heater is arranged in the slit in a state of being in contact with the first plate. It is characterized by that.

In the vacuum pump of the present invention, one or both of the side plates defining both ends of the pump chamber are side plates having a split structure that can be split in the axial direction, and the first and second plates that are the split members. A slit for installing a heater is formed between the two. Unlike the case where the heater embedded portion is formed inside a single component, the heater can be incorporated inside the side plate without complicating the structure of the side plate. Further, since the side plate defining the end face of the pump chamber can be directly heated from the inside, the heating efficiency can be improved. Further, the slit formed between the first and second plates reduces the contact area between the first and second plates. The slits form a heat insulating structure capable of suppressing heat transfer from the first plate to the second plate. Therefore, the amount of heat transfer to the side of the second plate on which the bearing or the like is arranged can be reduced.

Here, it is desirable to use a planar heating element (film heater or sheet heater) as the heater so that the heater can be arranged in the narrow slit formed between the first and second plates.

Further, assuming that the end face of the first plate on the side of the second plate is referred to as the end face of the first plate and the end face of the second plate on the side of the first plate is referred to as the end face of the second plate, the end faces of the first and second plates are referred to. The outer peripheral side end face portions surrounding the central side end face portions of the first and second plate end faces are separated from each other in the axial direction, and between the outer peripheral side end face portions. In addition, an annular gap surrounding the central end face portion can be formed. An annular heater can be arranged in the gap along the outer peripheral side end face portion.

In this case, the heater may be attached to the outer peripheral side end face portion of the second plate end face by a heater holding plate made of a metal plate or the like.

(A) and (b) are schematic vertical sectional views which show the vacuum pump which concerns on embodiment to which this invention was applied, respectively. (A) is a cross-sectional view showing a side plate having a divided structure attached to one end of the casing of the vacuum pump of FIG. 1, and (b) is an exploded perspective view thereof.

The vacuum pump according to the embodiment of the present invention will be described below with reference to the drawings. The vacuum pump described below is a single-stage vacuum pump, but the present invention is similarly applicable to a multi-stage vacuum pump having two or more stages.

(overall structure)
1 (a) and 1 (b) are schematic vertical cross-sectional views of the vacuum pump according to the present embodiment, respectively, when the vacuum pump is cut along an orthogonal plane including its rotation center line. The vacuum pump 1 includes a pump chamber 2, a motor 3, and a gear chamber 4. The motor 3 is arranged on one side in the axial direction of the vacuum pump and the gear chamber 4 is arranged on the other side of the pump chamber 2. The pump chamber 2 is composed of a tubular casing 5, a side plate 6 on the motor side that closes one end thereof, and a side plate 7 on the gear chamber side that closes the other end of the casing 5. ing.

The

side plates

6 and 7 have a substantially symmetrical structure. The

side plates

6 and 7 are formed with

slits

8 and 9 having a constant width that open in the outer

peripheral surfaces

6a and 7a.

Film heaters

10 and 11, which are planar heating elements having the same shape, are incorporated in the

slits

8 and 9, respectively. The

film heaters

10 and 11 are heating means for suppressing the adhesion and accumulation of products and the like on the end faces on the pump chamber side of the

side plates

6 and 7 that define the end faces on both sides of the pump chamber 2. The

film heaters

10 and 11 have a structure in which, for example, a resistance heating wire is printed on the surface of a base film made of a plastic insulating material, and the resistance heating wire is covered with a cover film made of a plastic insulating material. Various planar heating elements can be used.

The casing 5 is formed with an intake port 5a and an exhaust port 5b, which communicate with the pump chamber 2. The motor 3 is attached to the side of the side plate 6. The gear chamber 4 on the opposite side is sealed by the gear chamber side side plate 7 and the gear cover 12 attached thereto.

In the pump chamber 2, the rotor shaft 13 on the driving side and the rotor shaft 13A on the driven side are arranged in parallel at regular intervals. The direction along the rotation center line 1a of the rotor shaft 13 on the drive side is the axial direction of the vacuum pump 1.

Pump rotors

14 and 14A having the same shape are attached to the rotor shaft 13 on the driving side and the rotor shaft 13A on the driven side, respectively. In this example, the rotor shafts 13 and 13A and the

pump rotors

14 and 14A are separated, but they can also be integrated. That is, the rotor shaft 13 and the pump rotor 14 can be manufactured as a single component, and the rotor shaft 13A and the pump rotor 14A can be manufactured as a single component.

The shaft end 13a on the motor side of the rotor shaft 13 on the drive side is supported by a bearing 15 attached to the side plate 6 on the motor side. The motor shaft 16 is integrally formed at a portion of the shaft end portion 13a extending into the motor 3. The shaft end portion 13b on the gear chamber side of the rotor shaft 13 is supported by a bearing 17 attached to the side plate 7 on the gear chamber side and extends to the inside of the gear chamber 4. The shaft end of the driven rotor shaft 13A on the motor side is supported by a bearing 15A attached to the side plate 6 on the motor side, and the shaft end on the gear chamber side is attached to the side plate 7 on the gear chamber side. It is supported by the bearing 17A and extends to the inside of the gear chamber 4. In the gear chamber 4, the shaft end portion 13b on the gear chamber side of the rotor shaft 13 on the drive side is connected to the shaft end portion of the rotor shaft 13A on the driven side via the gear train 18. When the rotor shaft 13 on the driving side rotates, the rotor shaft 13A on the driven side rotates synchronously in the opposite direction.

(Side plate)
FIG. 2A is a cross-sectional view showing the side plate 6, and FIG. 2B is an exploded perspective view showing its main components. Explaining with reference to these figures, the side plate 6 that closes one open end of the pump chamber 2 is a plate having a divided structure, and is the first plate 20 on the pump chamber side laminated from the axial direction. It is composed of a second plate 30 on the motor side. A slit 8 is formed between the first plate 20 and the second plate 30. In the slit 8, the film heater 10 is fixed to the first plate 20 by the heater holding plate 40.

The first plate 20 has a contour shape substantially similar to that of the casing 5. Two shaft holes 21 and 22 having the same diameter are formed in the central portion of the first plate 20, respectively, a shaft end portion 13a of the rotor shaft 13 on the drive side and a rotor on the driven side (not shown). The shaft end of the shaft is passed through. The pump chamber side end face 23 that defines the end face of the pump chamber 2 in the first plate 20 is a flat end face. Assuming that the end face of the first plate 20 facing the side of the second plate 30 is referred to as the first plate end face 24, the first plate end face 24 is the central end face portion 24a including the shaft holes 21 and 22 and the center thereof. It includes a stepped end face portion 24b that surrounds the side end face portion 24a, and an outer peripheral side end face portion 24c that surrounds the stepped end face portion 24b. The central end face portion 24a is a ring-shaped convex end face portion that surrounds each of the shaft holes 21 and 22. The step end face portion 24b and the outer peripheral side end face portion 24c are end face portions having an oval contour surrounding the center side end face portion 24a. The stepped end face portion 24b slightly protrudes toward the second plate 30 with respect to the outer peripheral side end face portion 24c. The central end face portion 24a projects toward the second plate 30 with respect to the step end face portion 24b.

The second plate 30 on the side of the motor 3 is a plate thicker than the first plate 20 as a whole, and has the same contour shape as the first plate 20. The second plate 30 is formed with

shaft holes

31 and 32 having a bearing mounting portion on which the bearing 15 is mounted in the central portion thereof, and functions as a bearing case. The second plate 30 includes a motor-side end surface 33 facing the motor 3 side and a flat end surface facing the first plate 20 side. This end face shall be referred to as a second plate end face 34.

Here, in the second plate end face 34, the end face portion facing the central end face portion 24a of the first plate 20 is called the central end face portion 34a, and the end face portion facing the outer peripheral side end face portion 24c of the first plate 20 is called. It shall be referred to as an outer peripheral side end face portion 34c. In this example, the end face 34 of the second plate is a flat surface, but the end face portion 34a on the central side thereof may be a convex end face portion. Further, the central

end face portions

24a and 34a of the first and

second plates

20 and 30 can both be convex end face portions.

The side plates 6 are configured by superimposing and fastening the first and

second plates

20 and 30 from the axial direction with fasteners such as fastening bolts (not shown). The convex central end surface portion 24a on the first plate end surface 24 and the central end surface portion 34a on the side of the second plate end surface 34 facing the convex central side end surface portion 24a are in contact with each other in an airtight state with a sealing material (not shown) sandwiched between them.

An oval shape formed so as to surround the central

end face portions

24a and 34a between the outer peripheral side end face portion 24c of the first plate end face 24 and the outer peripheral side end face portion 34c of the second plate end face 34 facing the outer peripheral side end face portion 24c. The slit 8 is formed. The slit 8 opens on the outer peripheral surface 6a of the side plate 6.

The slit 8 has a film heater 10 having a constant width that draws an oval loop having a size surrounding the step end face portion 24b (a size surrounding the central

end face portions

24a, 34a), and a heater having the same shape as the film heater 10. The holding plate 40 and the pressing plate 40 are arranged. The heater holding plate 40 is a rigid component such as a metal plate. The film heater 10 is located on the outer peripheral side end face portion 24c side of the first plate 20, and the heater holding plate 40 is located on the outer peripheral side end face portion 34c side of the second plate 30. The film heater 10 is fixed to the outer peripheral side end surface portion 24c of the first plate end surface 24 in a surface contact state by a heater holding plate 40 using a fastener such as a fastening bolt (not shown). The first plate 20 to which the film heater 10 is attached and the second plate 30 are fastened and fixed.

As shown in FIG. 1, the other side plate 7 is also a plate having a divided structure, and a film heater 11 and a heater holding plate 41 are mounted on the slit 9 formed therein. Like the side plate 6, the side plate 7 has a divided structure composed of a first plate 50 having a structure similar to that of the first plate 20 and a second plate 60 having a structure similar to that of the second plate 30. .. The film heater 11 is fixed to the first plate 50 on the pump chamber side by the heater holding plate 41. The detailed structure of the side plate 7 will be omitted.

In the vacuum pump 1 having this configuration, the

side plates

6 and 7 constituting the end walls on both sides of the pump chamber 2 are divided plates.

Film heaters

10 and 11 are incorporated in the

side plates

6 and 7, respectively. When the film heater 10 is attached to the first plate 20 of the side plate 6 by the heater holding plate 40, and the first and

second plates

20 and 30 are overlapped and fastened in that state, the side in which the film heater 10 is incorporated is incorporated. Plate 6 is obtained. Similarly, when the film heater 11 is attached to the first plate 50 of the side plate 7 by the heater holding plate 41, and the first and

second plates

50 and 60 are overlapped and fastened in that state, the film heater 11 is incorporated inside. The side plate 7 is obtained.

The

film heaters

10 and 11 can be incorporated inside the

side plates

6 and 7 without making the

side plates

6 and 7 have a complicated structure, and the

side plates

6 and 7 can be heated directly from the inside. Since the heating efficiency of the

film heaters

10 and 11 can be increased and the indoor wall portion of the pump can be maintained at a high temperature, the adhesion and accumulation of products can be efficiently suppressed.

In addition, slits 8 and 9 are formed in the

side plates

6 and 7. The mating surface of the

first plates

20 and 50 and the

second plates

30 and 60 constituting the

side plates

6 and 7 is only the central end surface portion. The contact area between the first and second plates is reduced, and the

slits

8 and 9 form a heat insulating structure between the first and second plates. The amount of heat transfer from the side of the

first plates

20 and 50 directly heated by the

film heaters

10 and 11 to the side of the

second plates

30 and 60 can be reduced, and the

bearings

15 and 17 on the sides of the

second plates

30 and 60 can be reduced. It is possible to avoid the harmful effect that the portion is heated unnecessarily. Further, the amount of heat transferred to the

second plates

30 and 60 can be reduced, and the amount of heat radiated from the

second plates

30 and 60 can also be suppressed, so that the heating efficiency and high temperature of the

first plates

20 and 50 can be maintained.

Claims

With a tubular casing
A pair of side plates that block the opening ends on both sides in the axial direction of the casing,
A pump chamber formed between the side plates inside the casing and
It has a heater attached to at least one of the side plates.
The side plate to which the heater is attached
1st plate and
A second plate superposed on the first plate from the side opposite to the pump chamber in the axial direction, and
It is provided with a slit formed between the first plate and the second plate.
The heater is a vacuum pump arranged in the slit in contact with the first plate.
The vacuum pump according to claim 1, wherein the heater is a planar heating element.
It is assumed that the end face on the side of the second plate in the first plate is referred to as the end face of the first plate, and the end face on the side of the first plate in the second plate is referred to as the end face of the second plate.
The central end face portions of the first and second plate end faces are in contact with each other.
The outer peripheral end face portions surrounding the central end face portion of each of the first and second plate end faces are separated from each other in the axial direction.
An annular slit surrounding the central end face portion is formed between the outer peripheral side end face portions.
The vacuum pump according to claim 2, wherein the annular heater is arranged in the slit along the outer peripheral side end face portion.
Equipped with a heater holding plate,
The vacuum pump according to claim 3, wherein the heater is attached to the outer peripheral side end surface portion of the second plate end surface by the heater holding plate.