CN112664460A

CN112664460A - Vacuum pump device

Info

Publication number: CN112664460A
Application number: CN202011095546.1A
Authority: CN
Inventors: 新名恭人; 穂积崇史; 杉浦哲郎; 盐川笃志
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2019-10-15
Filing date: 2020-10-14
Publication date: 2021-04-16
Also published as: EP3808983B1; TW202138679A; EP3808983A1

Abstract

The invention provides a vacuum pump device, which can maintain the interior of a rotor chamber at a high temperature. The vacuum pump device is provided with: a pump housing (2) having a rotor chamber (1) therein; a pump rotor (5) disposed in the rotor chamber (1); a rotating shaft (7) to which a pump rotor (5) is fixed; a motor (8) connected to the rotating shaft (7); a side cover (10A) that forms an end surface of the rotor chamber (1); and a side heater (55A) disposed in the side cover (10A).

Description

Vacuum pump device

Technical Field

The present invention relates to a vacuum pump apparatus, and more particularly to a vacuum pump apparatus suitably used for exhausting process gas used for manufacturing semiconductor devices, liquid crystals, LEDs, solar cells, and the like.

Background

In a manufacturing process for manufacturing a semiconductor device, a liquid crystal panel, an LED, a solar cell, or the like, a process gas is introduced into a process chamber to perform various processes such as an etching process, a CVD process, and the like. The process gas introduced into the process chamber is exhausted by a vacuum pump device. In general, a vacuum pump device used in these manufacturing processes requiring high cleanliness is a so-called dry vacuum pump device that does not use oil in a gas flow path. As a typical example of such a dry vacuum pump device, there is a positive displacement vacuum pump device in which a pair of pump rotors disposed in a rotor chamber rotate in opposite directions to each other to transfer a gas.

The process gas may contain a by-product having a high sublimation temperature. When the temperature in the rotor chamber of the vacuum pump apparatus is low, by-products may be solidified in the rotor chamber and deposited on the inner surface of the pump rotor or the pump casing. The solidified by-products hinder the rotation of the pump rotor, causing a reduction in the speed of the pump rotor, and in the worst case, causing the operation of the vacuum pump apparatus to stop. Therefore, in order to prevent the solidification of the by-product, a heater is attached to the outer surface of the pump housing to heat the rotor chamber.

On the other hand, it is necessary to cool the motor that drives the pump rotor and the gear fixed to the rotating shaft of the pump rotor. Therefore, the vacuum pump device described above is generally provided with a cooling system for cooling the motor and the gear. The cooling system is configured to cool the motor and the gear by, for example, circulating a cooling liquid through a cooling pipe provided in a motor case housing the motor and through a cooling pipe provided in a gear case housing the gear. With such a cooling system, overheating of the motor and the gear can be prevented, and stable operation of the vacuum pump device can be achieved.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2003-35290

Patent document 2: japanese patent laid-open publication No. 2012-251470

Technical problem to be solved by the invention

However, heat of the pump case heated by the heater is easily transferred to the motor case and the gear case having lower temperatures. As a result of such heat conduction, the temperature of the rotor chamber inside the pump housing may decrease. In particular, since the end surface of the rotor chamber is located close to the motor casing or the gear casing having a low temperature, the temperature of the end surface of the rotor chamber is likely to be lowered. As a result, by-products contained in the process gas may be solidified in the rotor chamber. As one of the countermeasures, a high-output heater is considered, but such a heater requires more electric power and cannot achieve energy-saving operation of the vacuum pump device.

Disclosure of Invention

The present invention provides a vacuum pump device capable of maintaining the inside of a rotor chamber of a pump housing at a high temperature.

Means for solving the problems

In one aspect, there is provided a vacuum pump device including: a pump housing having a rotor chamber therein; a pump rotor disposed within the rotor chamber; a rotating shaft to which the pump rotor is fixed; a motor coupled to the rotating shaft; a side cover forming an end surface of the rotor chamber; and a side heater disposed in the side cover.

In one mode, the side heater is configured to surround the rotating shaft.

In one aspect, the side cover includes an inner side cover forming an end surface of the rotor chamber, and an outer side cover located outside the inner side cover in an axial direction of the rotary shaft, and the side heater is disposed between the inner side cover and the outer side cover.

ADVANTAGEOUS EFFECTS OF INVENTION

The side heater can heat the side cover itself, and therefore, the temperature in the rotor chamber having the end face formed by the side cover can be increased.

Drawings

Fig. 1 is a sectional view showing one embodiment of a vacuum pump apparatus.

Fig. 2 is a sectional view taken along line a-a of fig. 1.

Fig. 3 is a diagram showing an embodiment in which a plurality of side heaters are disposed in a side cover.

Fig. 4(a) is a view showing another embodiment in which the side heater is disposed in the side cover, and fig. 4(B) is a cross-sectional view taken along line B-B of fig. 4 (a).

Fig. 5(a) is a view showing another embodiment in which the side heater is disposed in the side cover, and fig. 5(b) is a cross-sectional view taken along line C-C of fig. 5 (a).

Fig. 6(a) is a view showing another embodiment in which the side heater is disposed in the side cover, and fig. 6(b) is a cross-sectional view taken along line D-D of fig. 6 (a).

Fig. 7(a) is a view showing another embodiment in which the side heater is disposed in the side cover, and fig. 7(b) is a cross-sectional view taken along line E-E of fig. 7 (a).

Fig. 8(a) is a view showing another embodiment in which the side heater is disposed in the side cover, and fig. 8(b) is a cross-sectional view taken along line F-F of fig. 8 (a).

Fig. 9 is a sectional view showing another embodiment of the vacuum pump apparatus.

Fig. 10 is a sectional view showing another embodiment of a vacuum pump apparatus.

Fig. 11 is an exploded perspective view showing the side cover and a plurality of heat insulating members shown in fig. 10.

Fig. 12 is a sectional view taken along line G-G of fig. 10.

Fig. 13 is a diagram showing an embodiment in which a plurality of side heaters are disposed in a side cover.

Fig. 14 is a sectional view showing another embodiment of a vacuum pump apparatus.

Fig. 15 is a cross-sectional view showing an embodiment of a vacuum pump apparatus including a multistage pump rotor.

Description of the symbols

1 rotor chamber

2 Pump case

2a air inlet

2b exhaust port

5 Pump rotor

7 rotating shaft

8 electric motor

8A motor rotor

8B motor stator

10A, 10B side cover

12 bearing shell

14 motor casing

16 Gear case

17 bearing

18 bearing

20 gears

21 cooling pipe

22 cooling tube

25A, 25B heat insulation structure

27 through hole

31A, 31B inner side cover

32A, 32B outer side cover

41A, 41B Heat insulation parts (felt)

42A, 42B Heat insulating parts (Heat insulating pad)

45 through hole

47 recess

55A, 55B side heater

56 groove

58 holes

Detailed Description

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

Fig. 1 is a sectional view showing one embodiment of a vacuum pump apparatus. The vacuum pump apparatus of the embodiment described below is a positive displacement vacuum pump apparatus. In particular, the vacuum pump apparatus shown in fig. 1 is a so-called dry vacuum pump apparatus which does not use oil in a gas flow path. Since the vaporized oil in the dry vacuum pump apparatus does not flow to the upstream side, the dry vacuum pump apparatus can be suitably used in an apparatus for manufacturing a semiconductor device requiring high cleanliness.

As shown in fig. 1, the vacuum pump apparatus includes: a pump housing 2 having a rotor chamber 1 therein, a pump rotor 5 disposed in the rotor chamber 1, a rotary shaft 7 to which the pump rotor 5 is fixed, and a motor 8 coupled to the rotary shaft 7. The pump rotor 5 and the rotary shaft 7 may be an integral structure. In fig. 1, only one pump rotor 5, one rotating shaft 7, and one motor 8 are depicted, but the pair of pump rotors 5 are disposed in the rotor chamber 1 and fixed to the pair of rotating shafts 7, respectively. The pair of motors 8 are coupled to the pair of rotating shafts 7, respectively.

The pump rotor 5 of the present embodiment is a roots-type pump rotor, but the type of the pump rotor 5 is not limited to the present embodiment. In one embodiment, the pump rotor 5 may also be a screw-type pump rotor. Further, although the pump rotor 5 of the present embodiment is a single-stage pump rotor, the pump rotor 5 may be a multi-stage pump rotor in one embodiment.

The vacuum pump device further includes side covers 10A and 10B located outside the pump housing 2 in the axial direction of the rotary shaft 7. The side covers 10A and 10B are provided on both sides of the pump housing 2 and connected to the pump housing 2. In the present embodiment, the side covers 10A and 10B are fixed to the end surface of the pump housing 2 by screws, not shown. In one embodiment, the side covers 10A, 10B may be integrated with the pump housing 2.

The rotor chamber 1 is formed by the inner surface of the pump housing 2 and the inner surfaces of the side covers 10A, 10B. The pump housing 2 has an intake port 2a and an exhaust port 2 b. The suction port 2a is connected to a chamber (not shown) filled with gas to be transferred. In one example, the inlet port 2a is connected to a process chamber of an apparatus for manufacturing a semiconductor device, and the vacuum pump apparatus is used for exhausting a process gas introduced into the process chamber.

The vacuum pump device further includes a bearing housing 12, a motor housing 14, and a gear housing 16, which are outer housing structures, located outside the side covers 10A and 10B in the axial direction of the rotary shaft 7. The side cover 10A is located between the pump housing 2 and the gear housing 16, and the side cover 10B is located between the pump housing 2 and the bearing housing 12. The bearing housing 12 is located between the side cover 10B and the motor housing 14.

The rotary shaft 7 is rotatably supported by a bearing 17 disposed in the bearing housing 12 and a bearing 18 disposed in the gear housing 16. The motor case 14 accommodates the motor rotor 8A and the motor stator 8B of the electric motor 8 therein. The bearing housing 12, the motor housing 14, and the gear housing 16 are examples of a housing structure, and the housing structure is not limited to the present embodiment.

The two electric motors 8 (only one electric motor 8 is shown in fig. 1) are rotated in synchronization in opposite directions by a motor driver (not shown), and the pair of rotary shafts 7 and the pair of pump rotors 5 can be rotated in synchronization in opposite directions. When the pump rotor 5 is rotated by the motor 8, gas is sucked into the pump housing 2 through the inlet port 2 a. The gas is transferred from the inlet port 2a to the outlet port 2b by the rotating pump rotor 5.

A pair of gears 20 that mesh with each other are disposed inside the gear case 16. Furthermore, only one gear 20 is depicted in fig. 1. As described above, the pair of pump rotors 5 are rotated synchronously by the two motors 8, and therefore the gear 20 functions to prevent the loss of synchronism of the pump rotors 5 due to sudden external factors.

A cooling pipe 21 is buried in the gear case 16. Similarly, a cooling pipe 22 is embedded in the motor case 14. The cooling pipe 21 extends over the entire peripheral wall of the gear case 16, and the cooling pipe 22 extends over the entire peripheral wall of the motor case 14. The cooling

pipes

21 and 22 are connected to a cooling liquid supply source, not shown. The cooling pipe 21 and the cooling pipe 22 are supplied with the cooling liquid from the cooling liquid supply source. The cooling liquid flowing through the cooling pipe 21 cools the gear case 16, and thereby the gear 20 and the bearing 18 disposed in the gear case 16 can be cooled. The cooling liquid flowing through the cooling pipe 22 cools the motor case 14 and the bearing case 12, thereby cooling the motor 8 disposed in the motor case 14 and the bearing 17 disposed in the bearing case 12.

The vacuum pump device includes

side heaters

55A and 55B disposed in the side covers 10A and 10B, respectively. The

side heaters

55A and 55B are disposed adjacent to the rotor chamber 1. The side cover 10A includes: an inner cover 31A forming an end surface of the rotor chamber 1, and an outer cover 32A located outside the inner cover 31A in the axial direction of the rotary shaft 7. The side heater 55A is disposed between the inner cover 31A and the outer cover 32A.

Fig. 2 is a sectional view taken along line a-a of fig. 1. As shown in fig. 2, the outer surface of the inner cover 31A has a groove 56 surrounding the through hole 27 into which the rotary shaft 7 is inserted, and the side heater 55A is disposed in the groove 56. The side heater 55A is a ring-shaped heater disposed so as to surround the rotary shaft 7 penetrating through the through hole 27. The type of the side heater 55A is not particularly limited, but a sheath heater, which is one of electric heaters, can be used for the side heater 55A.

Since the side cover 10A is located closer to the gear case 16 provided with the cooling pipe 21 than the pump case 2, the temperature of the side cover 10A is likely to be lower than that of the pump case 2. According to the embodiment shown in fig. 1 and 2, the side heater 55A is provided between the pump housing 2 and the gear housing (housing structure) 16. Since the side heater 55A can heat the side cover 10A itself, the temperature in the rotor chamber 1 having the end face formed by the side cover 10A can be made high. In particular, the gear case 16 can be cooled by the coolant flowing through the cooling pipe 21, and the side heater 55A can maintain the inside of the rotor chamber 1 at a high temperature.

The process gas to be treated by the vacuum pump apparatus of the present embodiment may contain by-products that are solidified as the temperature decreases. During operation of the vacuum pump apparatus, the process gas is compressed while being transferred from the inlet port 2a to the outlet port 2b by the pump rotor 5. Therefore, the inside of the rotor chamber 1 becomes high temperature by the compression heat of the process gas. Further, according to the present embodiment, the side cover 10A is heated by the side heater 55A, and the inside of the rotor chamber 1 can be maintained at a high temperature. Therefore, the solidification of the by-product can be reliably prevented.

The specific configuration for disposing the side heater 55A in the side cover 10A is not limited to the embodiment shown in fig. 1 and 2. For example, the side cover 10A having a hole in which the side heater 55A is disposed may be formed by casting, and the side heater 55A may be inserted into the hole. In this case, the inner cover 31A and the outer cover 32A may not be separated from each other in the side cover 10A.

In one embodiment, as shown in fig. 3, a plurality of side heaters 55A may be disposed in the side cover 10A. In the embodiment shown in fig. 3, two side heaters 55A extending in parallel are disposed in the side cover 10A. Three or more side heaters 55A may be disposed.

Fig. 4(a) is a diagram showing another embodiment in which the side heater 55A is disposed in the side cover 10A, and fig. 4(B) is a cross-sectional view taken along line B-B of fig. 4 (a). As shown in fig. 4(a) and 4(b), the side heater 55A may have a rod shape. Grooves 56 are formed in the side surface of the inner cover 31A, and the side heaters 55A are disposed in these grooves 56. The through hole 27 into which the rotary shaft 7 is inserted is located between these side heaters 55A. Therefore, the side heater 55A is arranged to surround the rotation shaft 7 extending within the through hole 27. In the present embodiment, two grooves 56 are formed in parallel above and below the through hole 27, and two side heaters 55A are disposed in the grooves 56, respectively. The side heaters 55A are also located above and below the through-hole 27, parallel to each other. The embodiment shown in fig. 4(a) and 4(b) has an advantage that the groove 56 is easily formed, and the manufacturing cost can be reduced.

Fig. 5(a) is a view showing another embodiment in which the side heater 55A is disposed in the side cover 10A, and fig. 5(b) is a cross-sectional view taken along line C-C of fig. 5 (a). As shown in fig. 5(a) and 5(b), a rod-shaped side heater 55A may be disposed so as to surround the through hole 27 into which the rotary shaft 7 is inserted. In this embodiment, two grooves 56 are formed above and below the through hole 27 in parallel with each other, and further two grooves 56 are formed on both sides of the through hole 27 in parallel with each other. The four grooves 56 are formed in the side surface of the inner cover 31A. The four side heaters 55A are disposed in the four grooves 56, respectively. These side heaters 55A also surround the through hole 27 (and the rotary shaft 7). The side heater 55A thus arranged can uniformly heat the rotor chamber 1. More than five side heaters 55A may be provided.

Fig. 6(a) is a view showing another embodiment in which the side heater 55A is disposed in the side cover 10A, and fig. 6(b) is a cross-sectional view taken along line D-D of fig. 6 (a). As shown in fig. 6(a) and 6(b), the side heater 55A may have a rod shape. Holes 58 are formed in the inner cover 31A, and the side heater 55A is disposed in the holes 58. The through hole 27 into which the rotary shaft 7 is inserted is located between these side heaters 55A. Thus, the side heater 55A is configured to surround the rotation shaft 7. In the present embodiment, two holes 58 are formed in parallel above and below the through hole 27, and two side heaters 55A are disposed in the holes 58, respectively. These side heaters 55A are also located above and below the through-hole 27, parallel to each other. The embodiment shown in fig. 6(a) and 6(b) has an advantage that the hole 58 is easily formed, and the manufacturing cost can be reduced.

Fig. 7(a) is a view showing another embodiment in which the side heater 55A is disposed in the side cover 10A, and fig. 7(b) is a cross-sectional view taken along line E-E of fig. 7 (a). As shown in fig. 7(a) and 7(b), a rod-shaped side heater 55A may be disposed so as to surround the through hole 27 into which the rotary shaft 7 is inserted. Holes 58 are formed in the inner cover 31A, and the side heater 55A is disposed in the holes 58. In this embodiment, two holes 58 are formed above and below the through hole 27 in parallel with each other, and further two holes 58 are formed on both sides of the through hole 27 in parallel with each other. The four side heaters 55A are disposed in the four holes 58, respectively. These side heaters 55A also surround the through hole 27 (and the rotary shaft 7). The side heater 55A thus arranged can uniformly heat the rotor chamber 1. More than five side heaters 55A may be provided.

Fig. 8(a) is a view showing another embodiment in which the side heater 55A is disposed in the side cover 10A, and fig. 8(b) is a cross-sectional view taken along line F-F of fig. 8 (a). As shown in fig. 8(a) and 8(b), the side heater 55A may be a sheet-like heater. The side heater 55A is attached to a side surface of the inner side cover 31A. In the present embodiment, the side heater 55A is in the shape of a ring surrounding the through hole 27 into which the rotary shaft 7 is inserted, but the shape of the side heater 55A is not limited to the present embodiment. For example, as described with reference to fig. 4 to 7, the side heater 55A may linearly extend so as to surround the through hole 27 through which the rotary shaft 7 passes.

The side heaters 55A of the embodiments described with reference to fig. 2 to 8 are all adjacent to the rotor chamber 1. The arrangement of the side heater 55A described with reference to fig. 4 to 8 is an example, and the present invention is not limited to these embodiments.

As shown in fig. 1, the side heater 55B is also disposed in the side cover 10B. The side cover 10B includes: an inner cover 31B forming an end surface of the rotor chamber 1, and an outer cover 32B located outside the inner cover 31B in the axial direction of the rotary shaft 7. The outer surface of the inner side cover 31B has a groove (not shown), and the side heater 55B is disposed in the groove. The side heater 55B is a ring heater or a rod heater disposed so as to surround the rotary shaft 7. The description of the side heater 55A and the side cover 10A with reference to fig. 1 to 8 can also be applied to the side heater 55B and the side cover 10B, and thus other descriptions of the side heater 55B and the side cover 10B are omitted.

Fig. 9 is a sectional view showing another embodiment of the vacuum pump apparatus. The configuration of the present embodiment, which is not particularly described, is the same as the embodiment described with reference to fig. 1 to 8, and therefore, redundant description thereof is omitted.

A heat insulating structure 25A as a heat insulator is interposed between the side cover 10A and the gear case (housing structure) 16. The side cover 10A and the gear case 16 are separated from each other (do not contact each other), and the heat insulating structure 25A contacts both the side cover 10A and the gear case 16. The heat insulating structure 25A is located between the pump case 2 and the gear case 16, and has a function of reducing heat conduction from the pump case 2 to the gear case 16 through the side cover 10A.

The heat insulating structure 25A has a lower heat conductivity than the side cover 10A. More specifically, the heat insulating structure 25A is made of a material having a lower thermal conductivity than the material of the side cover 10A. In the present embodiment, the pump housing 2 and the side covers 10A and 10B forming the rotor chamber 1 are made of cast iron. The bearing housing 12, motor housing 14 and gear housing 16 are constructed of aluminum. The heat insulating structure 25A is made of a resin having a lower thermal conductivity than the material of the side cover 10A. In one example, the heat insulating structure 25A is made of Polytetrafluoroethylene (PTFE), which is one of fluororesins. Polytetrafluoroethylene (PTFE) has a lower thermal conductivity than cast iron and has the property of being able to withstand high temperatures. However, as long as the material has a lower thermal conductivity than the material of the side cover 10A, the material of the heat insulating structure 25A may be a metal such as stainless steel, titanium, or spheroidal graphite austenitic cast iron (Ni-resist).

Another housing structure such as a bearing housing may be disposed between the side cover 10A and the gear housing 16. In this case, the heat insulating structure 25A is sandwiched between the side cover 10A and the housing structure.

The heat insulating structure 25A is annular and arranged to surround the outer peripheral surface of the rotating shaft 7. The inner surface of the heat insulating structure 25A contacts the outer surface of the side cover 10A, and the outer surface of the heat insulating structure 25A contacts the inner end surface of the gear case 16. The heat insulating structure 25A has a continuous annular shape, and the heat insulating structure 25A also functions as a seal for sealing a gap between the side cover 10A and the gear case 16.

Similarly, the heat insulating structure 25B is sandwiched between the side cover 10B and the bearing housing (housing structure) 12. That is, the side cover 10B and the bearing housing 12 are separated from each other (do not contact each other), and the heat insulating structure 25B contacts both the side cover 10B and the bearing housing 12. The heat insulating structure 25B is located between the pump housing 2 and the bearing housing 12, and has a function of reducing heat conduction from the pump housing 2 to the bearing housing 12 through the side cover 10B.

The heat insulating structure 25B has a continuous annular shape, and the heat insulating structure 25B also functions as a seal for sealing a gap between the side cover 10B and the bearing housing 12. That is, the inner surface of the heat insulating structure 25B contacts the outer surface of the side cover 10B, and the outer surface of the heat insulating structure 25B contacts the inner end surface of the bearing housing 12. The heat insulating structure 25B has a lower heat conductivity than the side cover 10B. More specifically, the heat insulating structure 25B is made of a material having a lower thermal conductivity than the material of the side cover 10B. The heat insulating structure 25B has the same structure as the heat insulating structure 25A, and therefore, redundant description thereof will be omitted.

Another housing structure may be disposed between the side cover 10B and the bearing housing 12. In this case, the heat insulating structure 25B is sandwiched between the side cover 10B and the housing structure. Further, the bearing housing 12 may not be provided between the side cover 10B and the motor housing 14. In this case, the heat insulating structure 25B is sandwiched between the side cover 10B and the motor case 14.

Fig. 10 is a sectional view showing another embodiment of the vacuum pump apparatus. The configuration of the present embodiment, which is not particularly described, is the same as the embodiment described with reference to fig. 1 to 8, and therefore, redundant description thereof is omitted. In the present embodiment, a plurality of

heat insulating members

41A, 42A as heat insulators are provided in the side cover 10A. The

heat insulating structures

25A and 25B are not provided.

The plurality of

heat insulating members

41A, 42A are sandwiched between the inner cover 31A and the outer cover 32A. That is, the inner cover 31A and the outer cover 32A are separated from each other (do not contact each other), and the plurality of

heat insulating members

41A and 42A contact both the inner cover 31A and the outer cover 32A. The plurality of

heat insulating members

41A, 42A as the heat insulator are positioned between the pump housing 2 and the gear housing 16, and the plurality of

heat insulating members

41A, 42A have a lower thermal conductivity than the side cover 10A. Therefore, the plurality of

heat insulating members

41A, 42A have a function of reducing heat conduction from the pump case 2 to the gear case 16 through the side cover 10A.

Fig. 11 is an exploded perspective view showing the side cover 10A and the plurality of

heat insulating members

41A and 42A shown in fig. 10. The plurality of

heat insulating members

41A, 42A include: a heat shield plate 41A having two through holes 45 through which the rotating shaft 7 passes, and a plurality of heat insulating spacers 42A arranged around the heat shield plate 41A. A recess 47 is formed in the outer surface of the inner cover 31A, and the heat shield plate 41A is disposed in the recess 47. In one embodiment, a recess 47 may be formed in the inner surface of the outer cover 32A, and the heat shield plate 41A may be disposed in the recess 47 of the outer cover 32A. The heat insulating plate 41A of the present embodiment is a single structure, but may be separated into a plurality of structures. Sealing members (not shown) such as O-rings are disposed between the heat shield plate 41A and the inner cover 31A and between the heat shield plate 41A and the outer cover 32A.

The heat insulating board 41A and the heat insulating spacer 42A have lower thermal conductivity than the side cover 10A. Therefore, the heat shield plate 41A and the heat insulating spacer 42A can reduce heat conduction from the pump casing 2 to the gear casing 16 through the side cover 10A, and maintain the inside of the rotor chamber 1 at a high temperature. In particular, the gear case 16 can be cooled by the coolant flowing through the cooling pipe 21 (see fig. 10), and the heat insulating plate 41A and the heat insulating liner 42A can maintain the inside of the rotor chamber 1 at a high temperature.

The heat insulating board 41A and the heat insulating spacer 42A are made of a material having a lower thermal conductivity than the material constituting the side cover 10A. In the present embodiment, the pump housing 2 and the side covers 10A and 10B constituting the rotor chamber 1 are made of cast iron. The heat insulating plate 41A and the heat insulating spacer 42A are made of metal such as stainless steel, titanium, or spheroidal graphite austenitic cast iron (Ni-resist) having a lower thermal conductivity than the material of the side cover 10A. In the present embodiment, the heat insulating board 41A and the heat insulating spacer 42A are made of stainless steel. Stainless steel has a lower thermal conductivity than cast iron. Further, stainless steel has high mechanical rigidity, and high dimensional accuracy can be ensured at the time of assembling the vacuum pump device. However, the heat insulating board 41A and/or the heat insulating spacer 42A may be made of other materials such as resin as long as they have a lower thermal conductivity and a higher mechanical rigidity than the material of the side cover 10A.

The total sectional area of the heat insulating board 41A and the heat insulating spacer 42A is smaller than the sectional area of the side cover 10A. Therefore, the heat insulating plate 41A and the heat insulating spacer 42A, which have a small thermal conductivity and a small sectional area, contribute to reducing the heat conduction from the pump housing 2 toward the gear housing 16.

As shown in fig. 10, a plurality of

heat insulating members

41B, 42B as heat insulators, that is, a heat insulating plate 41B and a plurality of heat insulating spacers 42B are similarly provided in the other side cover 10B. The side cover 10B includes: an inner cover 31B forming an end surface of the rotor chamber 1, and an outer cover 32B located outside the inner cover 31B in the axial direction of the rotary shaft 7.

The side cover 10B, the heat insulating plate 41B, and the plurality of heat insulating spacers 42B are substantially the same in structure and arrangement as the side cover 10A, the heat insulating plate 41A, and the plurality of heat insulating spacers 42A. The descriptions of the side cover 10A, the heat insulating plate 41A, and the plurality of heat insulating spacers 42A with reference to fig. 10 and 11 can also be applied to the side cover 10B, the heat insulating plate 41B, and the plurality of heat insulating spacers 42B, and therefore, other detailed descriptions thereof are omitted.

The heat insulating plate 41B and the heat insulating liner 42B formed in the side cover 10B are located between the pump housing 2 and the bearing housing 12. The heat insulating board 41B and the heat insulating spacer 42B have lower thermal conductivity than the side cover 10B. Therefore, the heat insulating plate 41B and the heat insulating spacer 42B have a function of reducing heat conduction from the pump casing 2 toward the bearing casing 12 through the side cover 10B. In particular, the motor case 14 and the bearing case 12 can be cooled by the coolant flowing through the cooling pipe 22, and the heat insulating plate 41B and the heat insulating liner 42B can maintain the inside of the rotor chamber 1 at a high temperature.

The total sectional area of the heat insulating board 41B and the heat insulating spacer 42B is smaller than that of the side cover 10B. Therefore, the heat insulating plate 41B and the heat insulating liner 42B, which have a smaller thermal conductivity and a smaller sectional area, contribute to reducing the heat conduction from the pump housing 2 toward the bearing housing 12.

Fig. 12 is a sectional view taken along line G-G of fig. 10. As shown in fig. 12, the side heater 55A is configured to surround the heat insulating board 41A. Although not shown, the side heater 55B is similarly disposed so as to surround the heat insulating plate 41B. As shown in fig. 13, a plurality of side heaters 55A may be provided in the side cover 10A. Similarly, a plurality of side heaters 55B may be provided in the side cover 10B. The structure and arrangement of the side heater 55A and the side cover 10A described with reference to fig. 4 to 8 can be applied to the side heater 55A and the side cover 10A and/or the side heater 55B and the side cover 10B in the embodiment of fig. 10 and 11. In this case as well, the side heater 55A is disposed so as to surround the heat insulating plate 41A, and the side heater 55B is disposed so as to surround the heat insulating plate 41B.

Fig. 14 is a sectional view showing another embodiment of a vacuum pump apparatus. The configuration of the present embodiment, which is not particularly described, is the same as the embodiment described with reference to fig. 1 to 13, and therefore, redundant description thereof is omitted. In the present embodiment, as shown in fig. 14, the vacuum pump device includes both the

heat insulating structures

25A and 25B and the

heat insulating members

41A, 42A, 41B, and 42B as heat insulators. According to the present embodiment, the combination of the

double heat insulators

25A, 25B, 41A, 42A, 41B, and 42B and the

side heaters

55A and 55B can maintain the inside of the rotor chamber 1 at a high temperature. Further, the power required for the operation of the

side heaters

55A and 55B can be reduced.

In each of the embodiments described above, the

side heaters

55A and 55B are disposed on both sides of the rotor chamber 1, but the present invention is not limited to such a configuration. In one embodiment, the side heater may be disposed only on one side of the rotor chamber 1. For example, in the case where the cooling pipe 21 is not provided in the gear case 16, the side heater 55A may be omitted. Similarly, the heat insulator is disposed on both sides of the rotor chamber 1, but in one embodiment, the heat insulator may be disposed only on one side of the rotor chamber 1.

Fig. 15 is a cross-sectional view showing an embodiment of a vacuum pump apparatus including a multistage pump rotor. The configuration of the present embodiment, which is not particularly described, is the same as the embodiment shown in fig. 14, and therefore, redundant description thereof is omitted. The vacuum pump apparatus shown in fig. 15 includes a multistage pump rotor 5 having a plurality of rotors 5a to 5 e. The intake port 2a is located at the gear-side end of the pump housing 2, and the exhaust port 2b is located at the motor-side end of the pump housing 2. As the multistage pump rotor 5 rotates, the gas is compressed and transferred from the inlet port 2a to the outlet port 2 b. The compression heat generated when the gas is compressed is highest in the vicinity of the exhaust port 2 b. Therefore, the temperature of the exhaust side of the rotor chamber 1 is higher than the temperature of the suction side of the rotor chamber 1.

Depending on the type of process gas, by-products having a relatively low sublimation temperature may be contained. Such by-products are easily solidified on the air intake side of the rotor chamber 1, and are not easily solidified on the air exhaust side of the rotor chamber 1. Therefore, in such a case, the vacuum pump device may include the side heater 55A and/or the heat insulating structure 25A and/or the

heat insulating members

41A and 42A only between the gear housing 16 and the pump housing 2, as shown in fig. 15.

The above-described embodiments are described in order for those having ordinary knowledge in the art to which the present invention pertains to be able to practice the present invention. Various modifications of the above-described embodiments will be apparent to those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the embodiments described above, but is to be construed as the widest scope of the technical idea defined by the scope of the claims of the present invention.

Claims

1. A vacuum pump device is characterized by comprising:

a pump housing having a rotor chamber therein;

a pump rotor disposed within the rotor chamber;

a rotating shaft to which the pump rotor is fixed;

a motor coupled to the rotating shaft;

a side cover forming an end surface of the rotor chamber; and

a side heater disposed within the side cover.

2. Vacuum pumping apparatus as defined in claim 1,

the side heater is configured to surround the rotation shaft.

3. Vacuum pumping apparatus as defined in claim 1 or 2,

the side cover has an inner side cover forming an end surface of the rotor chamber and an outer side cover located outside the inner side cover in an axial direction of the rotary shaft,

the side heater is disposed between the inner side cover and the outer side cover.