TWI845776B - Vacuum pump apparatus - Google Patents

Abstract

An objective of the present invention is to provide a vacuum pump apparatus capable of maintaining the inside of a rotor chamber at a high temperature. The vacuum pump apparatus includes: a pump housing (2) having a rotor chamber (1) inside; a pump rotor(s) arranged in the rotor chamber (1); a rotating shaft (7) to which the pump rotor (5) is fixed; an electric motor (8) connected to the rotating shaft (7); a side cover (10A) forming an end surface of the rotor chamber (1); and a side heater (55A) arranged inside the side cover (10A).

Description

Vacuum pump device

The present invention relates to a vacuum pump device, and in particular to a vacuum pump device suitable for exhausting process gases used in the manufacture of semiconductor elements, liquid crystals, LEDs, solar cells, etc.

In the manufacturing process of semiconductor components, liquid crystal panels, LEDs, solar cells, etc., process gases are introduced into the process chamber to perform various processes such as etching and CVD. The process gases introduced into the process chamber are exhausted by a vacuum pump device. Generally, the vacuum pump devices used in these manufacturing processes that require a higher degree of cleanliness are so-called dry vacuum pump devices that do not use oil in the gas flow path. As a representative example of such a dry vacuum pump device, there is a positive displacement vacuum pump device that transfers gas by rotating a pair of pump rotors arranged in a rotor chamber in opposite directions.

Process gases sometimes contain byproducts with high sublimation temperatures. If the temperature inside the rotor chamber of the vacuum pump device is low, the byproducts sometimes solidify inside the rotor chamber and accumulate on the inner surface of the pump rotor and pump housing. The solidified byproducts hinder the rotation of the pump rotor, causing the pump rotor speed to decrease, and in the worst case, causing the vacuum pump device to stop operating. Therefore, in order to prevent the solidification of byproducts, a heater is installed on 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 above-mentioned vacuum pump device usually has a cooling system for cooling the motor and the gear. The cooling system is configured, for example, to cool the motor and the gear by circulating the cooling liquid through the cooling pipe provided in the motor housing that accommodates the motor and the cooling pipe provided in the gear housing that accommodates the gear. Such a cooling system can prevent overheating of the motor and the gear, and realize stable operation of the vacuum pump device.

(Prior technical literature)

(Patent Literature)

Patent document 1: Japanese Patent Publication No. 2003-35290

Patent document 2: Japanese Patent Publication No. 2012-251470

However, the heat of the pump housing heated by the heater is easily transferred to the motor housing and gear housing with lower temperatures. As a result of such heat conduction, the temperature of the rotor chamber in the pump housing sometimes decreases. In particular, since the end surface of the rotor chamber is located close to the motor housing or gear housing with lower temperatures, the temperature of the end surface of the rotor chamber is easy to decrease. As a result, by-products contained in the process gas may solidify in the rotor chamber. As one of the countermeasures, the use of a high-output heater is considered, but such a heater requires more electricity and cannot achieve energy-saving operation of the vacuum pump device.

Here, the present invention provides a vacuum pump device capable of maintaining the interior of the rotor chamber of the pump housing at a relatively high temperature.

In one embodiment, a vacuum pump device is provided, comprising: a pump casing having a rotor chamber therein; a pump rotor disposed in the rotor chamber; a rotating shaft to which the pump rotor is fixed; a motor connected 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 embodiment, the side heater is configured to surround the rotation axis.

In one embodiment, the side cover comprises: an inner side cover forming the end surface of the rotor chamber, and an outer side cover located on the outer side of the inner side cover in the axial direction of the rotating shaft; the side heater is arranged between the inner side cover and the outer side cover.

The side heater can heat the side cover itself, thus making the rotor chamber, whose end surface is formed by the side cover, hot.

1: Rotor chamber

2: Pump casing

2a: Intake port

2b: Exhaust port

5: Pump rotor

7: Rotation axis

8: Motor

8A: Motor rotor

8B: Motor stator

10A, 10B: Side shields

12: Bearing housing

14: Motor shell

16: Gear housing

17: Bearings

18: Bearings

20: Gear

21,22: Cooling tube

25A, 25B: Thermal insulation structure

27,45:Through hole

31A,31B: Inner side cover

32A,32B: External side covers

41A, 41B: Insulation components (insulation boards)

42A, 42B: Thermal insulation components (thermal insulation pads)

47: Depression

55A, 55B: Side heater

56: Slot

58: Hole

FIG1 is a cross-sectional view showing an embodiment of a vacuum pump device.

Figure 2 is a cross-sectional view taken along line A-A of Figure 1.

FIG3 is a diagram showing an embodiment in which a plurality of side heaters are arranged in a side cover.

FIG4(a) is a diagram showing another embodiment in which the side heater is arranged in the side cover, and FIG4(b) is a cross-sectional view taken along the line B-B of FIG4(a).

FIG5(a) is a diagram showing another embodiment in which the side heater is arranged in the side cover, and FIG5(b) is a cross-sectional view taken along the line C-C of FIG5(a).

FIG6(a) is a diagram showing another embodiment in which the side heater is arranged in the side cover, and FIG6(b) is a cross-sectional view taken along the D-D line of FIG6(a).

FIG7(a) is a diagram showing another embodiment in which the side heater is arranged in the side cover, and FIG7(b) is a cross-sectional view taken along the E-E line of FIG7(a).

FIG8(a) is a diagram showing another embodiment in which the side heater is arranged in the side cover, and FIG8(b) is a cross-sectional view taken along the F-F line of FIG8(a).

FIG9 is a cross-sectional view showing another embodiment of the vacuum pump device.

FIG10 is a cross-sectional view showing another embodiment of the vacuum pump device.

FIG. 11 is an exploded perspective view showing the side cover and a plurality of heat insulation components shown in FIG. 10 .

Figure 12 is a cross-sectional view taken along line G-G of Figure 10.

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

FIG14 is a cross-sectional view showing another embodiment of the vacuum pump device.

FIG15 is a cross-sectional view showing an embodiment of a vacuum pump device having a multi-stage pump rotor.

The following describes the implementation of the present invention with reference to the attached drawings.

FIG1 is a cross-sectional view showing an embodiment of a vacuum pump device. The vacuum pump device of the embodiment described below is a positive displacement vacuum pump device. In particular, the vacuum pump device shown in FIG1 is a so-called dry vacuum pump device that does not use oil in the gas flow path. The vaporized oil in the dry vacuum pump device does not flow upstream, so the dry vacuum pump device can be suitable for use in semiconductor device manufacturing equipment that requires higher cleanliness.

As shown in FIG1 , the vacuum pump device includes: 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 the pump rotor 5 is fixed, and a motor 8 connected to the rotating shaft 7. The pump rotor 5 and the rotating shaft 7 may also be an integral structure. In FIG1 , only one pump rotor 5, one rotating shaft 7, and one motor 8 are depicted, but a pair of pump rotors 5 are disposed in the rotor chamber 1 and are fixed to a pair of rotating shafts 7, respectively. A pair of motors 8 are connected to a pair of rotating shafts 7, respectively.

The pump rotor 5 of this embodiment is a Roots-type pump rotor, but the type of the pump rotor 5 is not limited to this embodiment. In one embodiment, the pump rotor 5 may also be a screw-type pump rotor. Furthermore, the pump rotor 5 of this embodiment is a single-stage pump rotor, but in one embodiment, the pump rotor 5 may also be a multi-stage pump rotor.

The vacuum pump device is further equipped with side covers 10A and 10B located on the outer side of the pump housing 2 in the axial direction of the rotating shaft 7. The side covers 10A and 10B are arranged on both sides of the pump housing 2 and connected to the pump housing 2. In this embodiment, the side covers 10A and 10B are fixed to the end surface of the pump housing 2 by threaded parts not shown. In one embodiment, the side covers 10A and 10B can also 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 and 10B. The pump housing 2 has an air intake port 2a and an air exhaust port 2b. The air intake port 2a is connected to a chamber (not shown) filled with gas to be transferred. In one example, the air intake port 2a is connected to a process chamber of a semiconductor device manufacturing device, and the vacuum pump device is used to exhaust the process gas introduced into the process chamber.

The vacuum pump device is further equipped with a bearing housing 12, a motor housing 14 and a gear housing 16 as a housing structure located outside the side housings 10A and 10B in the axial direction of the rotating shaft 7. The side housing 10A is located between the pump housing 2 and the gear housing 16, and the side housing 10B is located between the pump housing 2 and the bearing housing 12. The bearing housing 12 is located between the side housing 10B and the motor housing 14.

The rotating shaft 7 is supported by a bearing 17 disposed in the bearing housing 12 and a bearing 18 disposed in the gear housing 16 so as to be rotatable. The motor housing 14 accommodates the motor rotor 8A and the motor stator 8B of the motor 8 therein. The bearing housing 12, the motor housing 14 and the gear housing 16 are examples of the outer shell structure, and the outer shell structure is not limited to the present embodiment.

Two motors 8 (only one motor 8 is shown in FIG. 1 ) are synchronously rotated in opposite directions by a motor driver not shown, which can cause a pair of rotating shafts 7 and a pair of pump rotors 5 to synchronously rotate in opposite directions. When the pump rotors 5 are rotated by the motor 8, gas is sucked into the pump housing 2 from the air intake port 2a. The gas is transferred from the air intake port 2a to the air exhaust port 2b by the rotating pump rotor 5.

A pair of gears 20 that mesh with each other are arranged inside the gear housing 16. In addition, only one gear 20 is depicted in FIG1. As described above, a pair of pump rotors 5 are rotated synchronously by two motors 8, so the role of the gear 20 is to prevent the synchronous rotation of the pump rotors 5 from being out of step due to sudden external factors.

A cooling pipe 21 is embedded in the gear housing 16. Similarly, a cooling pipe 22 is embedded in the motor housing 14. The cooling pipe 21 extends over the entire peripheral wall of the gear housing 16, and the cooling pipe 22 extends over the entire peripheral wall of the motor housing 14. The cooling pipe 21 and the cooling pipe 22 are connected to a cooling liquid supply source (not shown). The cooling liquid is supplied from the cooling liquid supply source to the cooling pipe 21 and the cooling pipe 22. The cooling liquid flowing in the cooling pipe 21 cools the gear housing 16, thereby cooling the gear 20 and the bearing 18 arranged in the gear housing 16. The cooling liquid flowing in the cooling tube 22 cools the motor housing 14 and the bearing housing 12, thereby cooling the motor 8 disposed in the motor housing 14 and the bearing 17 disposed in the bearing housing 12.

The vacuum pump device includes side heaters 55A and 55B respectively arranged in the side covers 10A and 10B. The side heaters 55A and 55B are arranged adjacent to the rotor chamber 1. The side cover 10A includes an inner side cover 31A forming the end surface of the rotor chamber 1, and an outer side cover 32A located on the outer side of the inner side cover 31A in the axial direction of the rotating shaft 7. The side heater 55A is arranged between the inner side cover 31A and the outer side cover 32A.

FIG2 is a cross-sectional view taken along line A-A of FIG1. As shown in FIG2, the outer surface of the inner side cover 31A has a groove 56 surrounding the through hole 27 for inserting the rotating shaft 7, and the side heater 55A is disposed in the groove 56. The side heater 55A is an annular heater configured to surround the rotating shaft 7 passing through the through hole 27. The type of the side heater 55A is not particularly limited, but a sheath heater, which is a type of electric heater, can be used for the side heater 55A.

The side cover 10A is located closer to the gear housing 16 provided with the cooling tube 21 than the pump housing 2, so the temperature of the side cover 10A is easier to lower than that of the pump housing 2. According to the embodiment shown in FIG. 1 and FIG. 2, a side heater 55A is provided between the pump housing 2 and the gear housing (outer housing structure) 16. The side heater 55A can heat the side cover 10A itself, so that the inside of the rotor chamber 1 whose end surface is formed by the side cover 10A can be made high temperature. In particular, the gear housing 16 can be cooled by the cooling liquid flowing in the cooling tube 21, and the side heater 55A can maintain the inside of the rotor chamber 1 at a high temperature.

The process gas handled by the vacuum pump device of this embodiment sometimes contains by-products that solidify as the temperature decreases. During the operation of the vacuum pump device, the process gas is compressed in the process of being transferred from the air intake port 2a to the air exhaust port 2b by the pump rotor 5. Therefore, the inside of the rotor chamber 1 becomes high temperature due to the compression heat of the process gas. Moreover, according to this embodiment, the side cover 10A is heated by the side heater 55A, so that the inside of the rotor chamber 1 can be maintained at a high temperature. Therefore, the solidification of the by-products can be reliably prevented.

The specific structure for configuring the side heater 55A in the side cover 10A is not limited to the embodiments shown in Figs. 1 and 2. For example, the side cover 10A having a hole for configuring the side heater 55A may be formed by casting, and the side heater 55A may be inserted into the hole. In this case, the inner side cover 31A and the outer side cover 32A may not be separated in the side cover 10A.

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

Fig. 4(a) is a diagram showing another embodiment in which the side heater 55A is arranged in the side cover 10A, and Fig. 4(b) is a cross-sectional view of the line B-B of Fig. 4(a). The side heater 55A may also be in the shape of a rod as shown in Fig. 4(a) and Fig. 4(b). Grooves 56 are formed on the side surface of the inner side cover 31A, and the side heater 55A is arranged in these grooves 56. The through hole 27 for inserting the rotating shaft 7 is located between these side heaters 55A. Therefore, the side heater 55A is arranged to surround the rotating shaft 7 extending in the through hole 27. In this embodiment, two grooves 56 are formed parallel to each other above and below the through hole 27, and two side heaters 55A are arranged in these grooves 56, respectively. The side heaters 55A are also located above and below the through hole 27 and are parallel to each other. The embodiments shown in FIG. 4(a) and FIG. 4(b) have the advantages of being easy to form the groove 56 and being able to reduce manufacturing costs.

FIG. 5(a) is a diagram showing another embodiment in which the side heater 55A is arranged in the side cover 10A, and FIG. 5(b) is a cross-sectional view of the C-C line of FIG. 5(a). As shown in FIG. 5(a) and FIG. 5(b), the rod-shaped side heater 55A may be arranged in a manner to surround the through hole 27 for inserting the rotating shaft 7. In this embodiment, two grooves 56 are formed parallel to each other above and below the through hole 27, and further, two grooves 56 are formed parallel to each other on both sides of the through hole 27. The four grooves 56 are formed on the side surface of the inner side cover 31A. The four side heaters 55A are respectively arranged in the four grooves 56. These side heaters 55A also surround the through hole 27 (and the rotating shaft 7). The side heater 55A configured in this way can evenly heat the rotor chamber 1. Five or more side heaters 55A may also be provided.

Fig. 6(a) is a diagram showing another embodiment in which the side heater 55A is arranged in the side cover 10A, and Fig. 6(b) is a cross-sectional view of the D-D line of Fig. 6(a). As shown in Fig. 6(a) and Fig. 6(b), the side heater 55A may be in the shape of a rod. Holes 58 are formed inside the inner side cover 31A, and the side heater 55A is arranged in these holes 58. The through hole 27 for inserting the rotating shaft 7 is located between these side heaters 55A. Therefore, the side heater 55A is arranged to surround the rotating shaft 7. In this embodiment, two holes 58 are formed parallel to each other above and below the through hole 27, and two side heaters 55A are arranged in these holes 58, respectively. These side heaters 55A are also located above and below the through hole 27 and are parallel to each other. The embodiments shown in FIG. 6(a) and FIG. 6(b) have the advantages of being easy to form the hole 58 and being able to reduce manufacturing costs.

FIG. 7(a) is a diagram showing another embodiment in which the side heater 55A is arranged in the side cover 10A, and FIG. 7(b) is a cross-sectional view of the E-E line of FIG. 7(a). As shown in FIG. 7(a) and FIG. 7(b), the rod-shaped side heater 55A may be arranged in a manner to surround the through hole 27 for inserting the rotating shaft 7. Holes 58 are formed inside the inner side cover 31A, and the side heater 55A is arranged in these holes 58. In this embodiment, two holes 58 are formed parallel to each other above and below the through hole 27, and further, two holes 58 are formed parallel to each other on both sides of the through hole 27. Four side heaters 55A are respectively arranged in four holes 58. These side heaters 55A also surround the through hole 27 (and the rotating shaft 7). The side heater 55A configured in this way can evenly heat the rotor chamber 1. Five or more side heaters 55A may also be provided.

FIG8(a) is a diagram showing another embodiment in which the side heater 55A is arranged in the side cover 10A, and FIG8(b) is a cross-sectional view of the F-F line of FIG8(a). As shown in FIG8(a) and FIG8(b), the side heater 55A may be a sheet-shaped heater. The side heater 55A is mounted on the side surface of the inner side cover 31A. In this embodiment, the side heater 55A is annular and surrounds the through hole 27 for the rotation shaft 7 to be inserted, but the shape of the side heater 55A is not limited to this embodiment. For example, as described with reference to FIG4 to FIG7, the side heater 55A may extend in a straight line in a manner to surround the through hole 27 for the rotation shaft 7 to pass through.

The side heaters 55A of the embodiments described with reference to FIGS. 2 to 8 are all adjacent to the rotor chamber 1. The configurations of the side heaters 55A described with reference to FIGS. 4 to 8 are examples and do not mean that the present invention is limited to these embodiments.

As shown in FIG1 , the side heater 55B is also arranged in the side cover 10B. The side cover 10B includes an inner side cover 31B forming the end surface of the rotor chamber 1, and an outer side cover 32B located outside the inner side cover 31B in the axial direction of the rotating shaft 7. The outer surface of the inner side cover 31B has a groove (not shown), and the side heater 55B is set in the groove. The side heater 55B is a ring-shaped heater or a rod-shaped heater arranged in a manner surrounding the rotating shaft 7. The description of the side heater 55A and the side cover 10A with reference to FIGS. 1 to 8 can also be applied to the side heater 55B and the side cover 10B, so other descriptions of the side heater 55B and the side cover 10B are omitted.

FIG9 is a cross-sectional view showing another embodiment of the vacuum pump device. The structure of this embodiment not specifically described is the same as the embodiment described with reference to FIG1 to FIG8, so the repeated description thereof is omitted.

An insulating structure 25A serving as an insulator is sandwiched between the side cover 10A and the gear housing (housing structure) 16. The side cover 10A and the gear housing 16 are separated from each other (not in contact with each other), and the insulating structure 25A is in contact with both the side cover 10A and the gear housing 16. The insulating structure 25A is located between the pump housing 2 and the gear housing 16, and has the function of reducing heat conduction from the pump housing 2 to the gear housing 16 through the side cover 10A.

The heat insulating structure 25A has a lower thermal 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 constituting 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, the motor housing 14 and the gear housing 16 are made 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 a type of fluororesin. Polytetrafluoroethylene (PTFE) has a lower thermal conductivity than cast iron and has a property of being able to withstand high temperatures. However, as long as the thermal conductivity of the material is lower than that 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 outer shell structure such as a bearing shell may be arranged between the side cover 10A and the gear shell 16. In this case, the heat insulating structure 25A is sandwiched between the side cover 10A and the outer shell structure.

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

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

The heat insulating structure 25B has a continuous ring shape, and the heat insulating structure 25B also functions as a seal to seal the gap between the side cover 10B and the bearing shell 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 shell 12. The heat insulating structure 25B has a lower thermal conductivity than the side cover 10B. More specifically, the heat insulating structure 25B is made of a material with a lower thermal conductivity than the material constituting the side cover 10B. The structure of the heat insulating structure 25B is the same as that of the heat insulating structure 25A, so its repeated description is omitted.

Another outer shell structure may be arranged between the side cover 10B and the bearing shell 12. In this case, the heat insulating structure 25B is sandwiched between the side cover 10B and the outer shell structure. In addition, there is a case where the bearing shell 12 is not arranged between the side cover 10B and the motor shell 14. In this case, the heat insulating structure 25B is sandwiched between the side cover 10B and the motor shell 14.

FIG. 10 is a cross-sectional view showing another embodiment of the vacuum pump device. The structure of this embodiment not specifically described is the same as the embodiment described with reference to FIGS. 1 to 8 , so the repeated description thereof is omitted. In this embodiment, a plurality of heat insulating members 41A and 42A serving as heat insulators are provided in the side cover 10A. Heat insulating structures 25A and 25B are not provided.

The plurality of heat insulating members 41A and 42A are sandwiched between the inner side cover 31A and the outer side cover 32A. That is, the inner side cover 31A and the outer side cover 32A are separated from each other (not in contact with each other) and there is a space between the inner side cover 31A and the outer side cover 32A, and the plurality of heat insulating members 41A and 42A are in contact with both the inner side cover 31A and the outer side cover 32A. The plurality of heat insulating members 41A and 42A as the heat insulator are located between the pump housing 2 and the gear housing 16, and the plurality of heat insulating members 41A and 42A have a lower thermal conductivity than the side cover 10A. Therefore, the plurality of heat insulating members 41A and 42A have the function of reducing heat conduction from the pump housing 2 through the side cover 10A toward the gear housing 16.

FIG. 11 is an exploded perspective view showing the side cover 10A shown in FIG. 10 and a plurality of heat insulating components 41A, 42A. The plurality of heat insulating components 41A, 42A include: a heat insulating plate 41A having two through holes 45 for the rotation shaft 7 to pass through, and a plurality of heat insulating pads 42A arranged around the heat insulating plate 41A. A recess 47 is formed on the outer surface of the inner side cover 31A, and the heat insulating plate 41A is arranged in the recess 47. In one embodiment, a recess 47 may be formed on the inner surface of the outer side cover 32A, and the heat insulating plate 41A may be arranged in the recess 47 of the outer side cover 32A. The heat insulating plate 41A of this embodiment is a single structure, but may be separated into a plurality of structures. Seals such as O-rings (not shown) are arranged between the heat insulation plate 41A and the inner side cover 31A, and between the heat insulation plate 41A and the outer side cover 32A.

The heat insulation plate 41A and the heat insulation pad 42A have lower thermal conductivity than the side cover 10A. Therefore, the heat insulation plate 41A and the heat insulation pad 42A can reduce the heat conduction from the pump housing 2 through the side cover 10A toward the gear housing 16, and maintain the rotor chamber 1 at a high temperature. In particular, the gear housing 16 can be cooled by the coolant flowing in the cooling pipe 21 (refer to Figure 10), and the heat insulation plate 41A and the heat insulation pad 42A can maintain the rotor chamber 1 at a high temperature.

The heat insulation board 41A and the heat insulation pad 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 casing 2 and the side covers 10A, 10B constituting the rotor chamber 1 are made of cast iron. The heat insulation board 41A and the heat insulation pad 42A are made of a 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 insulation board 41A and the heat insulation pad 42A are made of stainless steel. Stainless steel has a lower thermal conductivity than cast iron. Furthermore, stainless steel has high mechanical rigidity and can ensure high dimensional accuracy when assembling the vacuum pump device. However, the material of the heat insulation board 41A and/or the heat insulation pad 42A may also be other materials such as resin as long as the thermal conductivity is lower than that of the material of the side cover 10A and the mechanical rigidity is higher.

The total cross-sectional area of the heat shield 41A and the heat shield 42A is smaller than the cross-sectional area of the side cover 10A. Therefore, the heat shield 41A and the heat shield 42A having smaller thermal conductivity and cross-sectional area help reduce heat conduction from the pump housing 2 toward the gear housing 16.

As shown in FIG10 , a plurality of heat insulating members 41B and 42B, namely, a heat insulating plate 41B and a plurality of heat insulating pads 42B, are similarly provided in another side cover 10B as heat insulators. The side cover 10B includes an inner side cover 31B forming the end surface of the rotor chamber 1, and an outer side cover 32B located on the outer side of the inner side cover 31B in the axial direction of the rotating shaft 7.

The structure and configuration of the side cover 10B, the heat insulation board 41B and the plurality of heat insulation pads 42B are substantially the same as those of the side cover 10A, the heat insulation board 41A and the plurality of heat insulation pads 42A. The description of the side cover 10A, the heat insulation board 41A and the plurality of heat insulation pads 42A with reference to FIG. 10 and FIG. 11 can also be applied to the side cover 10B, the heat insulation board 41B and the plurality of heat insulation pads 42B, so other detailed descriptions thereof are omitted.

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

The total cross-sectional area of the heat shield 41B and the heat shield 42B is smaller than the cross-sectional area of the side cover 10B. Therefore, the heat shield 41B and the heat shield 42B having smaller thermal conductivity and cross-sectional area help reduce heat conduction from the pump housing 2 to the bearing housing 12.

FIG12 is a cross-sectional view taken along line G-G of FIG10. As shown in FIG12, the side heater 55A is configured to surround the heat insulation board 41A. Although not shown, the side heater 55B is similarly configured to surround the heat insulation board 41B. As shown in FIG13, a plurality of side heaters 55A may be disposed in the side cover 10A. Similarly, a plurality of side heaters 55B may be disposed in the side cover 10B. Furthermore, the structure and configuration of the side heater 55A and the side cover 10A described with reference to FIGS. 4 to 8 may also be applied to the side heater 55A and the side cover 10A and/or the side heater 55B and the side cover 10B of the embodiments of FIGS. 10 and 11. In this case as well, the side heater 55A is configured to surround the heat insulation board 41A, and the side heater 55B is configured to surround the heat insulation board 41B.

FIG. 14 is a cross-sectional view showing another embodiment of the vacuum pump device. The structure of this embodiment that is not specifically described is the same as the embodiment described with reference to FIG. 1 to FIG. 13, so the repeated description thereof is omitted. In this embodiment, as shown in FIG. 14, the vacuum pump device has both the heat insulating structure 25A, 25B and the heat insulating member 41A, 42A, 41B, 42B as a heat insulator. According to this embodiment, by combining the double heat insulator 25A, 25B, 41A, 42A, 41B, 42B with the side heater 55A, 55B, the rotor chamber 1 can be maintained at a high temperature. In addition, the power required for the operation of the side heaters 55A, 55B can be reduced.

In each of the above-described embodiments, side heaters 55A and 55B are arranged on both sides of the rotor chamber 1, but the present invention is not limited to such an arrangement. In one embodiment, the side heater may be arranged on only one side of the rotor chamber 1. For example, when the cooling pipe 21 is not provided in the gear housing 16, the side heater 55A may be omitted. Similarly, the above-mentioned heat insulator is arranged on both sides of the rotor chamber 1, but in one embodiment, the heat insulator may be arranged on only one side of the rotor chamber 1.

FIG15 is a cross-sectional view showing an embodiment of a vacuum pump device having a multi-stage pump rotor. The structure of this embodiment, which is not specifically described, is the same as that of the embodiment shown in FIG14, and therefore repeated descriptions thereof are omitted. The vacuum pump device shown in FIG15 has a multi-stage pump rotor 5 having a plurality of rotors 5a to 5e. The air intake port 2a is located at the end of the pump housing 2 on the gear side, and the air exhaust port 2b is located at the end of the pump housing 2 on the motor side. As the multi-stage pump rotor 5 rotates, the gas is compressed and transferred from the air intake port 2a to the air exhaust port 2b. The compression heat generated when the gas is compressed is highest near the air exhaust port 2b. Therefore, the temperature on the exhaust side of the rotor chamber 1 is higher than the temperature on the intake side of the rotor chamber 1.

Depending on the type of process gas, byproducts with relatively low sublimation temperatures are sometimes included. Such byproducts are easily solidified on the air intake side of the rotor chamber 1, but are not easily solidified on the air exhaust side of the rotor chamber 1. Therefore, in such a case, as shown in FIG. 15, the vacuum pump device may only have a side heater 55A and/or an insulating structure 25A and/or insulating members 41A, 42A between the gear housing 16 and the pump housing 2.

The above-mentioned embodiments are recorded for the purpose of enabling people with ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various variations of the above-mentioned embodiments are natural to those skilled in the art, and the technical concept of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is interpreted as the widest scope of the technical concept defined by the scope of the patent application of the present invention.

1: Rotor chamber

2: Pump casing

2a: Intake port

2b: Exhaust port

5: Pump rotor

7: Rotation axis

8: Motor

8A: Motor rotor

8B: Motor stator

10A, 10B: Side shields

12: Bearing housing

14: Motor shell

16: Gear housing

17: Bearings

18: Bearings

20: Gear

21,22: Cooling tube

31A,31B: Inner side cover

32A,32B: External side covers

55A, 55B: Side heater

Claims (5)

A vacuum pump device comprises: a pump casing having a rotor chamber therein; a pump rotor disposed in the rotor chamber; a rotating shaft to which the pump rotor is fixed; a motor connected to the rotating shaft; a side cover forming an end surface of the rotor chamber; and a side heater disposed in the side cover; the side cover having: An inner side cover on the end surface of the chamber; an outer side cover located on the outer side of the inner side cover in the axial direction of the rotation axis; and a plurality of heat insulation components sandwiched between the inner side cover and the outer side cover; the side heater is arranged between the inner side cover and the outer side cover; and there is a space between the inner side cover and the outer side cover. A vacuum pump device as described in claim 1, wherein the side heater is configured to surround the rotating shaft. A vacuum pump device as described in claim 1 or 2, wherein the total cross-sectional area of the plurality of heat-insulating components is smaller than the cross-sectional area of the inner side cover and smaller than the cross-sectional area of the outer side cover. A vacuum pump device as described in any one of claims 1 to 3, wherein the plurality of thermal insulation components include: a thermal insulation board having a through hole for the rotating shaft to pass through; and a plurality of thermal insulation pads arranged around the thermal insulation board. A vacuum pump device as described in any one of claims 1 to 3, wherein the outer surface of the inner side cover has a groove, and the side heater is disposed in the groove.

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