TW202336347A - Vacuum pump apparatus and method of operating the same - Google Patents

Abstract

The present invention provides a vacuum pump apparatus and method of operating the same that is capable of reducing deposition of by-products in a pump chamber caused by process gas, preventing unintended stop of the vacuum pump apparatus, and reliably restarting the vacuum pump apparatus.

The vacuum pump apparatus includes a pump casing (2) having a pump chamber (1) inside; a pump rotor (5E) arranged in the pump chamber (1); a rotating shaft (7) to which the pump rotor (5E) is fixed; a bearing (17) that rotatably supports the rotating shaft (7); a side cover (10A) connected to the pump casing (2); a heater (35) attached to the side cover (10A); and a heater control unit (40) that intermittently makes the heater (35) generate heat while the pump rotor (5E) is rotating; wherein the bearing (17) is connected to the side cover (10A).

Description

Vacuum pump device and operation method thereof

The present invention relates to a vacuum pump device and an operating method thereof, and in particular to a vacuum pump device and an operating method thereof that are well suited for processing gases used in the manufacturing of semiconductor devices, liquid crystal panels, LEDs, solar cells, etc. Purpose of exhaust.

In the process of manufacturing semiconductor devices, liquid crystal panels, LEDs, solar cells, etc., process gases are introduced into the processing chamber and various processes such as etching processing and CVD processing are performed. The process gas introduced into the processing chamber is exhausted by a vacuum pump device. Generally, the 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 the gas flow path. As a representative example of such a dry vacuum pump device, there is a positive displacement vacuum pump device that rotates a pair of pump rotors arranged in a pump chamber in opposite directions to transport gas.

If the temperature of the process gas introduced into the processing chamber decreases or increases due to reactions in the chamber, solidified by-products may be formed. When a large amount of solidified by-products accumulates in the vacuum pump device, it hinders the rotation of the pump rotor and sometimes causes the vacuum pump device to suddenly stop. If the vacuum pump device stops unexpectedly, it may cause damage to products such as semiconductor devices being manufactured.

The above-mentioned by-products may also accumulate in the piping connecting the processing chamber and the vacuum pump device, and/or in the piping connecting the vacuum pump device and the harm removal device on the downstream side of the vacuum pump device. Therefore, piping maintenance is performed periodically, but at this time, the vacuum pump device is stopped. When the piping maintenance is completed, the vacuum pump device is restarted. However, if a large amount of by-products accumulates in the pump chamber, the resistance to the rotation of the pump rotor will be large, and the vacuum pump device may not be able to be restarted.

[Prior technical literature]

[Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2009-97349

Therefore, a pump stopping method has been proposed in which by-products accumulated in the pump chamber are gradually scraped off by the pump rotor by repeatedly rotating and stopping the pump rotor when stopping the operation of the vacuum pump device (see Patent Document 1). According to this method, by-products are removed from the pump chamber and the vacuum pump device can be restarted.

However, this pump stopping method requires a long time (for example, about 3 hours) until completion, which reduces the productivity of product manufacturing such as semiconductor devices, and therefore may not be accepted by users.

Therefore, the present invention provides a vacuum pump and its operating method that can reduce the accumulation of by-products caused by process gases in the pump chamber, prevent unexpected stops of the vacuum pump device, and reliably restart the vacuum pump device.

In one aspect, a vacuum pump device is provided that includes: a pump housing having a pump chamber inside; a pump rotor disposed in the pump chamber; and a rotating shaft rotating in the pump chamber. The shaft is fixed with the aforementioned pump rotor; the motor is connected to the aforementioned rotating shaft; the bearing is rotatably supported by the aforementioned rotating shaft; the side cover is connected to the aforementioned pump housing; and the heater is installed the side cover; and a heater control unit that causes the heater to generate heat intermittently when the pump rotor is rotating, and the bearing is connected to the side cover.

In one embodiment, the side cover forms an end surface of the pump chamber.

In one embodiment, the pump housing forms an end surface of the pump chamber.

In one aspect, the vacuum pump device further includes a bearing housing that holds the bearing, and the bearing housing is held by the side cover.

In one embodiment, the side cover includes: a side wall that forms an end surface of the pump chamber; and a spacer made of the same material as the side wall or a material with a linear expansion coefficient larger than that of the side wall. , the aforementioned heater is arranged in the aforementioned spacer.

In one embodiment, the side cover includes: a side wall that forms an end surface of the pump chamber and is made of the same material as the rotation shaft or a material with a linear expansion coefficient larger than that of the rotation shaft; and a spacer. , the spacer holds the bearing, and the heater is arranged in the side wall.

In one embodiment, the side cover includes: a side wall connected to the pump housing; and a spacer made of the same material as the side wall or a material with a linear expansion coefficient larger than that of the side wall. , the aforementioned heater is arranged in the aforementioned spacer.

In one embodiment, the side cover includes: a side wall connected to the pump housing and made of the same material as the rotation shaft or a material with a linear expansion coefficient larger than that of the rotation shaft; and a spacer. , the spacer holds the bearing, and the heater is arranged in the side wall.

In one embodiment, the vacuum pump device further includes: a first temperature sensor for measuring the temperature of the pump housing; and a second temperature sensor for measuring the temperature of the pump housing. The temperature of the side cover is measured, the heater control unit determines a target temperature based on the temperature of the pump housing, and controls the heater so that the temperature of the side cover reaches the target temperature.

In one aspect, the heater control unit is configured to stop the heat generation of the heater or reduce the heat generation temperature of the heater after the temperature of the side cover reaches the target temperature.

In one aspect, the vacuum pump device further includes a displacement sensor for measuring the axial displacement of the bearing, and the heater control unit is configured to detect when the axial displacement of the bearing reaches a threshold value. Stop the heating of the heater.

In one aspect, the vacuum pump device further includes a second heater, and the second heater is mounted on the pump housing.

In one aspect, the vacuum pump device further includes a cooler mounted on the pump housing.

In one aspect, there is provided a method of operating a vacuum pump device, wherein a pump rotor disposed in a pump chamber of a pump casing is fixed to a rotating shaft, the rotating shaft is rotatably supported by a bearing, and the bearing is connected to the pump casing. The side cover is connected to the heater installed on the side cover to generate heat intermittently when the process gas is being exhausted by the rotation of the pump rotor.

In one embodiment, the side cover forms an end surface of the pump chamber.

In one embodiment, the pump housing forms an end surface of the pump chamber.

In one embodiment, the bearing is held by a bearing housing, and the bearing housing is held by the side cover.

In one embodiment, the side cover includes: a side wall that forms an end surface of the pump chamber; and a spacer made of the same material as the side wall or a material with a linear expansion coefficient larger than that of the side wall. , the aforementioned heater is arranged in the aforementioned spacer.

In one embodiment, the side cover includes: a side wall that forms an end surface of the pump chamber and is made of the same material as the rotation shaft or a material with a linear expansion coefficient larger than that of the rotation shaft; and a spacer. , the spacer holds the bearing, and the heater is arranged in the side wall.

In one embodiment, the side cover includes: a side wall connected to the pump housing; and a spacer made of the same material as the side wall or a material with a linear expansion coefficient larger than that of the side wall. , the aforementioned heater is arranged in the aforementioned spacer.

In one embodiment, the side cover includes: a side wall connected to the pump housing and made of the same material as the rotation shaft or a material with a linear expansion coefficient larger than that of the rotation shaft; and a spacer. , the spacer holds the bearing, and the heater is arranged in the side wall.

In one mode, the operation method further includes: determining a target temperature based on the temperature of the pump housing, and controlling the heater so that the temperature of the side cover reaches the target temperature.

In one form, the operation method further includes: after the temperature of the side cover reaches the target temperature, stopping the heating of the heater or lowering the heating temperature of the heater.

In one mode, the operation method further includes: stopping the heating of the heater when the axial displacement of the bearing reaches a threshold value.

In one form, the operation method further includes heating the pump housing using a second heater installed on the pump housing.

In one form, the operation method further includes cooling the pump housing using a cooler installed on the pump housing.

When the heater intermittently generates heat while rotating the pump rotor, the side cover repeatedly undergoes thermal expansion and contraction, and the rotation shaft reciprocates in the axial direction via a bearing connected to the side cover. As the rotating shaft reciprocates in the axial direction, the pump rotor also moves back and forth in the axial direction. The rotating pump rotor can scrape off the by-products accumulated in the pump chamber. As a result, the pump rotor can rotate smoothly.

1: Pump room

2: Pump housing

2a: Suction port

2b:Exhaust port

5A~5E: Pump rotor

7:Rotation axis

8: Electric motor

8A:Motor rotor

8B: Motor stator

10A, 10B: Side cover

14: Motor housing

16:Gear housing

17,18:Bearing

20:Gear

24:Bearing shell

31:Side wall

32: Spacer

35:Heater

36:next door

40: Heater control section

40a: Storage device

40b:Computing device

40c:Power supply

45: First temperature sensor

46: Second temperature sensor

49: Displacement sensor

50: Second heater

51:Cooler

60: Rotating circular plate

62:Partition wall

70A, 70B: Shell side wall

100: By-products

110: Lubricating oil

FIG. 1 is a cross-sectional view showing one embodiment of the vacuum pump device.

Figure 2 shows an enlarged cross-sectional view of the side cover, bearing housing, and bearing located on the exhaust side.

FIG. 3 is a cross-sectional view showing a state in which the pump rotor moves in the axial direction due to thermal expansion of the rotating shaft.

4 is a cross-sectional view showing a state in which the pump rotor is moved toward the side cover by thermal expansion of the spacer using heat generated by the heater.

FIG. 5 is a cross-sectional view showing an embodiment provided with a displacement sensor for measuring bearing displacement.

Figure 6 is a cross-sectional view showing an embodiment of a side cover made of a single material.

Figure 7 is a cross-sectional view showing an embodiment in which the bearing is directly held on the side cover.

Figure 8 is a cross-sectional view showing another embodiment in which the bearing is directly held on the side cover.

FIG. 9 is a diagram showing one embodiment of a vacuum pump device including a second heater mounted on a pump housing.

FIG. 10 is a diagram showing one embodiment of a vacuum pump device including a cooler mounted on a pump housing.

FIG. 11 is a cross-sectional view showing another embodiment of the vacuum pump device.

Figure 12 is a cross-sectional view showing still another embodiment of the vacuum pump device.

FIG. 13 is a cross-sectional view showing still another embodiment of the vacuum pump device.

FIG. 1 is a cross-sectional view showing one embodiment of the 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 FIG. 1 is a so-called dry vacuum pump device that does not use oil in the gas flow path. Since the dry vacuum pump device does not allow vaporized oil to flow to the upstream side, it is well suited to manufacturing equipment for semiconductor devices that require high cleanliness.

As shown in FIG. 1 , the vacuum pump device includes: a pump housing 2 having a pump chamber 1 inside; pump rotors 5A to 5E arranged in the pump chamber 1; and a rotating shaft 7. Pump rotors 5A to 5E and an electric motor 8 are fixed to the rotating shaft 7 . The electric motor 8 is connected to the rotating shaft 7 . The pump rotors 5A to 5E and the rotating shaft 7 may be an integral structure. In FIG. 1 , only one set of pump rotors 5A to 5E and the rotating shaft 7 are depicted, but a pair of pump rotors 5A to 5E are arranged in the pump chamber 1 and fixed to the pair of rotating shafts 7 respectively. The electric motor 8 is connected to one of the pair of rotating shafts 7 . In one embodiment, a pair of electric motors 8 may be connected to a pair of rotation shafts 7 respectively.

The pump rotors 5A to 5E of this embodiment are Roots type pump rotors, but in one embodiment, the pump rotors 5A to 5E may also be claw type pump rotors. Moreover, the pump rotors 5A~5E can also be made of Luo A combination of ziggurat type pump rotor and claw type pump rotor. The pump rotors 5A to 5E of this embodiment are multi-stage pump rotors, but in one embodiment, the pump rotors may also be single-stage pump rotors.

The vacuum pump device further includes side covers 10A and 10B located outside the pump housing 2 in the axial direction of the rotating 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 this embodiment, the side covers 10A and 10B are fixed to the end surfaces of the pump housing 2 with screws (not shown).

The pump 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 air suction port 2a and an exhaust port 2b. The suction port 2a is connected to a chamber (not shown) filled with gas to be transported. In one example, the suction port 2a is connected to a processing chamber of a semiconductor device manufacturing apparatus, and the vacuum pump device is used to discharge the process gas from the processing chamber.

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

The motor housing 14 accommodates the motor rotor 8A and the motor stator 8B of the motor 8 inside. A pair of gears 20 meshing with each other is arranged inside the gear housing 16 . Furthermore, only one gear 20 is depicted in FIG. 1 . The motor 8 is rotated by a motor driver (not shown), and one rotation shaft 7 connected to the motor 8 rotates the other rotation shaft 7 not connected to the motor 8 in the opposite direction via the gear 20 .

In one embodiment, a pair of electric motors 8 each connected to a pair of rotation shafts 7 may be provided. The pair of electric motors 8 synchronously rotates in opposite directions via a motor driver (not shown), thereby causing the pair of rotating shafts 7 and the pair of pump rotors 5A to 5E to synchronously rotate in opposite directions. In this case, the function of the gear 20 is to prevent the synchronous rotation of the pump rotor 5 from losing synchronization due to sudden external factors.

In the embodiment shown in FIG. 1 , the motor housing 14 is arranged outside the side cover 10A, and the gear housing 16 is arranged outside the side cover 10B. However, the structure of the vacuum pump device is not limited to this embodiment. In one embodiment, the gear housing 16 may be disposed outside the side cover 10A, and the motor housing 14 may be disposed outside the side cover 10B. Furthermore, in one embodiment, both the motor housing 14 and the gear housing 16 may be disposed outside either the side cover 10A or the side cover 10B.

When the pump rotors 5A to 5E are rotated by the motor 8, gas is sucked into the pump chamber 1 of the pump housing 2 from the suction port 2a. The gas is sequentially compressed by the rotating pump rotors 5A to 5E, is transported to the exhaust port 2b, and is discharged from the pump chamber 1 through the exhaust port 2b.

The rotating shaft 7 is rotatably supported by bearings 17 and 18 . The bearing 17 is held by the bearing housing 24, and the bearing 18 is supported by the side cover 10B. The bearing 17 is connected to the side cover 10A via the bearing housing 24 . More specifically, the bearing housing 24 is held by the side cover 10A, and the positions of the bearing housing 24 and the bearing 17 are fixed by the side cover 10A. Since the inner ring of the bearing 17 is fixed to the rotating shaft 7 , the axial position of the portion of the rotating shaft 7 held by the bearing 17 is fixed.

On the other hand, the bearing 18 is supported movably in the axial direction by the side cover 10B. More specifically, the inner ring of the bearing 18 is fixed to the rotating shaft 7 , but the outer ring of the bearing 18 is not fixed to the side cover 10B but is only supported by the side cover 10B. Therefore, the bearing 18 can move in the axial direction integrally with the rotation shaft 7 .

A bearing housing that holds the bearing 18 may be disposed between the side cover 10B and the bearing 18 . In this case, the bearing housing is fixed to the side cover 10B, but the outer ring of the bearing 18 is not fixed to the bearing housing but is only supported by the bearing housing. The bearing 18 can move in the axial direction integrally with the rotating shaft 7 .

During the operation of the vacuum pump device, gas is compressed while being transported from the suction port 2a to the exhaust port 2b by the pump rotors 5A to 5E. Therefore, the rotation shaft 7 located in the pump chamber 1 thermally expands due to the compression heat of the gas. The axial position of the bearing 17 is fixed. In contrast, the bearing 18 can move along the axial direction. Therefore, the rotating shaft 7 thermally expands in the axial direction starting from the bearing 17. As the rotating shaft 7 thermally expands, the bearing 18 moves in the axial direction.

FIG. 2 is an enlarged cross-sectional view showing the side cover 10A, the bearing housing 24 and the bearing 17 located on the exhaust side. As shown in FIG. 2 , the pump housing 2 has a partition wall 36 inside, and the pump rotor 5E is arranged between the partition wall 36 and the side cover 10A. In this embodiment, the side cover 10A is provided with: a side wall 31 that forms an end surface of the pump chamber 1; and a spacer 32 that is made of the same material as the side wall 31 or has a linear expansion coefficient larger than that of the side wall 31. Made of materials with large coefficients. A spacer 32 is located between the side wall 31 and the bearing housing 24 . The bearing housing 24 is held by the spacer 32 , and the bearing housing 24 is connected to the side wall 31 via the spacer 32 .

The vacuum pump device includes a heater 35 attached to the side cover 10A. In this embodiment, the heater 35 is arranged in the spacer 32 of the side cover 10A. The spacer 32 is made of the same material as the side wall 31 and the pump housing 2 or a metal whose linear expansion coefficient is larger than that of the side wall 31 . For example, when the side wall 31 and the pump housing 2 are made of cast iron, the spacer 32 is made of cast iron or stainless steel, aluminum, aluminum alloy, or copper whose linear expansion coefficient is larger than that of cast iron. When the heater 35 generates heat, the spacer 32 thermally expands, and the bearing housing 24 held by the spacer 32 moves in the axial direction. In particular, the spacer 32 has a shape surrounding the bearing housing 24 and is prone to thermal expansion in the axial direction.

If the temperature of the process gas processed by the vacuum pump device decreases or increases due to reactions in the chamber, solidified by-products may sometimes be formed. Such by-products gradually accumulate in the pump chamber 1 as the vacuum pump device operates. FIG. 3 is a cross-sectional view showing a state in which the pump rotor 5E moves in the axial direction due to thermal expansion of the rotating shaft 7 . As described above, the high-temperature rotating shaft 7 thermally expands in the axial direction. As a result, the pump rotor 5E moves in a direction away from the side cover 10A forming the end surface of the pump chamber 1 . By-product 100 It gradually accumulates in the gap between the pump rotor 5E and the side cover 10A. Such by-products 100 hinder the rotation of the pump rotor 5E, causing the vacuum pump device to stop unexpectedly or preventing the vacuum pump device from restarting.

Therefore, as shown in FIG. 4 , the spacer 32 is thermally expanded by the heat generated by the heater 35 , thereby moving the bearing housing 24 and the bearing 17 in the axial direction, thereby moving the pump rotor 5E toward the side cover 10A. As the rotating pump rotor 5E moves toward the side cover 10A (end surface of the pump chamber 1 ), the by-products 100 accumulated in the gap between the pump rotor 5E and the side cover 10A are scraped off little by little.

When the pump rotor 5E reaches the initial position shown in FIG. 2 , the heater 35 stops generating heat. The initial position of the pump rotor 5E is the position of the pump rotor 5E when the entire vacuum pump device is at room temperature. When the heat generation of the heater 35 stops, the temperature of the spacer 32 gradually decreases, and the spacer 32 gradually shrinks. As the spacer 32 contracts, the pump rotor 5E moves away from the side cover 10A. As shown in FIG. 3 , the gap between the pump rotor 5E and the side cover 10A becomes larger. Since the by-product 100 gradually accumulates in the gap, the heater 35 is heated again and the spacer 32 is thermally expanded. As shown in FIG. 4 , the rotating pump rotor 5E moves toward the side cover 10A (the end surface of the pump chamber 1 ), and gradually removes the by-products 100 accumulated in the gap between the pump rotor 5E and the side cover 10A. Scrape off.

Similarly, the by-product 100 accumulated between the partition wall 36 and the pump rotor 5E is also rotated when the heat generation of the heater 35 is stopped and the pump rotor 5E moves away from the side cover 10A (in a direction approaching the partition wall 36 ). Pump rotor 5E is scraped off bit by bit.

In this way, by repeating the heating and stopping of the heater 35 during the operation of the vacuum pump device (that is, during the exhaust of the process gas), the rotating pump rotor 5E is reciprocated in the axial direction, utilizing the rotating The pump rotor 5E scrapes off by-products accumulated in the pump chamber 1 . Through the same mechanism, the rotating pump rotors 5A to 5D can also scrape off by-products accumulated in the pump chamber 1 . As a result, by-products are removed from the pump chamber 1 and the pump rotors 5A to 5E can rotate smoothly.

In conventional pumps, the pump rotor does not reciprocate as mentioned above during operation. Therefore, if the operation continues, a large amount of by-products will accumulate near the pump rotor, and a large amount of by-products will be bitten at a certain time. causing the pump to stop suddenly. According to the present invention, the pump rotors 5A to 5E always repeatedly perform the reciprocating motion, so that a state in which by-products are hardly accumulated can be always achieved in the pump chamber 1, especially near the pump rotors 5A to 5E, and thus the sudden failure of the pump can be prevented. stop.

As shown in FIG. 2 , the vacuum pump device includes a heater control unit 40 that controls heat generation of the heater 35 . The heater control unit 40 is configured to cause the heater 35 to generate heat intermittently while the pump rotors 5A to 5E are rotating (the heater 35 generates heat and stops the heat generation periodically). The heater control unit 40 includes a storage device 40a that stores a program; an arithmetic device 40b that performs calculations according to instructions included in the program; and a power supply 40c that supplies electric power to the heater 35 . The heater control unit 40 includes at least one computer. The storage device 40a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Examples of the computing device 40b include a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). However, the specific structure of the heater control unit 40 is not limited to these examples.

The vacuum pump device further includes a first temperature sensor 45 for measuring the temperature of the pump housing 2 and a second temperature sensor 46 for measuring the temperature of the side cover 10A. The first temperature sensor 45 is fixed to the pump housing 2 . The first temperature sensor 45 may be fixed on the outer surface of the pump housing 2 , or may be embedded in the pump housing 2 . The first temperature sensor 45 is provided to indirectly measure the temperature of the rotating shaft 7 . That is, the temperature of the rotation shaft 7 arranged inside the pump housing 2 can be estimated based on the temperature of the pump housing 2 measured by the first temperature sensor 45 .

The second temperature sensor 46 is fixed on the side cover 10A. The second temperature sensor 46 may be fixed on the outer surface of the side cover 10A, or may be embedded in the side cover 10A. As shown in Figures 2 to 4 In the embodiment, the second temperature sensor 46 is fixed on the spacer 32 of the side cover 10A. Therefore, the second temperature sensor 46 can measure the temperature of the side cover 10A (more specifically, the temperature of the spacer 32 ). The second temperature sensor 46 may also be embedded in the spacer 32 .

The heater control unit 40 is configured to determine the target temperature of the spacer 32 , that is, the target temperature of the side cover 10A based on the temperature of the pump housing 2 measured by the first temperature sensor 45 . Since the temperature of the pump casing 2 indirectly indicates the temperature of the rotating shaft 7 , the degree of thermal expansion of the rotating shaft 7 , that is, the axial expansion of the pump rotor 5E from the initial position can be estimated based on the temperature of the pump casing 2 . Moving distance. Therefore, the heater control unit 40 can determine the target temperature of the spacer 32 required to return the pump rotor 5E, which has moved due to the thermal expansion of the rotating shaft 7, to the initial position.

The heater control unit 40 determines the target temperature of the spacer 32 required to return the pump rotor 5E to the initial position based on the temperature of the pump housing 2, the axial thickness of the spacer 32, and the linear expansion coefficient of the spacer 32. . The relationship between the movement distance of the pump rotor 5E and the temperature of the spacer 32 may be obtained through experiments, simulations, etc., and the target temperature of the spacer 32 may be determined based on the obtained relationship.

The heater control unit 40 is configured to control the heater 35 so that the temperature of the spacer 32 reaches the target temperature determined above. The temperature of the spacer 32 is measured by the second temperature sensor 46, and the spacer 32 is heated to the target temperature. As the spacer 32 is heated, the bearing housing 24, the bearing 17, the rotating shaft 7, and the pump rotor 5E move in the axial direction. And, when the spacer 32 is heated to the target temperature, the pump rotor 5E returns to the initial position shown in FIG. 4 . Then, the heater control unit 40 stops the heat generation by the heater 35 . In one embodiment, the heater control unit 40 may lower the heating temperature of the heater 35 after the spacer 32 is heated to the target temperature. In addition, the heater control unit 40 may stop the heat generation of the heater 35 after lowering the heat generation temperature of the heater 35 .

In this manner, the heater control section 40 causes the heater 35 to intermittently generate heat to reciprocate the pump rotor 5E between the initial position shown in FIG. 4 and the thermal expansion position shown in FIG. 3 . Thereby, the other pump rotors 5A to 5D also reciprocate in the axial direction. Since the pump rotors 5A to 5E reciprocate in the axial direction in the pump chamber 1 while rotating, the pump rotors 5A to 5E can scrape off by-products accumulated in the pump chamber 1 .

In one embodiment, as shown in FIG. 5 , the vacuum pump device is provided with a displacement sensor 49 for measuring the axial displacement of the bearing 17 . The displacement sensor 49 is installed on the side wall 31 of the side cover 10A and is arranged toward the bearing housing 24 that holds the bearing 17 . Therefore, the displacement sensor 49 measures the axial displacement of the bearing 17 by measuring the axial displacement of the bearing housing 24 . In one embodiment, the displacement sensor 49 may also be configured to directly measure the axial displacement of the bearing 17 .

The displacement sensor 49 is electrically connected to the heater control unit 40 . The heater control unit 40 is configured to stop the heat generation of the heater 35 when the axial displacement of the bearing 17 reaches a threshold value. In this way, by controlling the heat generation of the heater 35 based on the axial displacement of the bearing 17, it is possible to prevent the pump rotor 5E from coming into contact with the inner surface of the side cover 10A (the end surface of the pump chamber 1).

In one embodiment, as shown in FIG. 6 , the side cover 10A may also be made of a single material. More specifically, a part of the side cover 10A forms an end surface of the pump chamber 1 , and the other part of the side cover 10A holds the bearing housing 24 . The side cover 10A is made of the same material as the pump housing 2 or a material whose linear expansion coefficient is larger than that of the pump housing 2 . For example, when the pump casing 2 is made of cast iron, the entire side cover 10A is made of cast iron, or stainless steel, aluminum, aluminum alloy, or copper whose linear expansion coefficient is larger than that of the pump casing 2 . In the embodiment shown in FIG. 6 , the heater 35 repeatedly generates heat and stops the heat generation, and the rotating pump rotors 5A to 5E can also scrape off by-products accumulated in the pump chamber 1 .

In one embodiment, as shown in FIG. 7 , the bearing housing 24 may not be provided. In the embodiment shown in FIG. 7 , the bearing 17 is directly held on the side cover 10A. More specifically, the bearing 17 is directly held by the spacer 32 of the side cover 10A. In addition, in one embodiment, as shown in FIG. 8 , the side cover 10A may also be made of a single material without the bearing housing 24 . The embodiment shown in FIG. 8 is a combination of the embodiment shown in FIG. 6 and the embodiment shown in FIG. 7 , and the bearing 17 is directly held by the side cover 10A. In the embodiment shown in FIGS. 7 and 8 , as the heater 35 repeatedly generates heat and stops generating heat, the rotating pump rotors 5A to 5E can also scrape off by-products accumulated in the pump chamber 1 .

In one embodiment, as shown in FIG. 9 , in order to prevent the accumulation of by-products in the pump chamber 1 due to the temperature drop of the process gas, the vacuum pump device may also be equipped with a second pump installed on the pump housing 2 . Heater 50. Among the process gases, there are also process gases that produce by-products as the temperature of the process gas rises. When used for exhausting such process gas, as shown in FIG. 10 , the vacuum pump device may further include a cooler 51 installed in the pump housing 2 . The cooler 51 is, for example, a water-cooled cooler. The second heater 50 shown in FIG. 9 and the cooler 51 shown in FIG. 10 may be installed on the outer surface of the pump housing 2 , or may be embedded in the pump housing 2 .

According to the embodiment shown in FIGS. 9 and 10 , it is possible to reliably prevent the reciprocating movement of the pump rotors 5A to 5E in the axial direction caused by the intermittent operation of the heater 35 in combination with the second heater 50 or the cooler 51 . Accumulation of by-products in the pump chamber 1.

FIG. 11 is a cross-sectional view showing another embodiment of the vacuum pump device. As shown in FIG. 11 , in the vacuum pump device of this embodiment, lubricating oil 110 used to lubricate and cool the bearing 17 is stored at the bottom of the motor housing 14 . The structure and operation of this embodiment that are not particularly described are the same as those of the embodiment described with reference to FIGS. 1 to 4 , and therefore repeated descriptions thereof are omitted.

The vacuum pump device of this embodiment includes a rotating disc 60 that supplies lubricating oil 110 to the bearing 17 and a partition wall 62 arranged between the motor 8 and the bearing housing 24 . The rotating discs 60 are respectively connected to a pair of rotating shafts 7 and rotate together with the rotating shafts 7 . In one embodiment, the rotating disc 60 may be connected to one of the pair of rotating shafts 7 and rotate together with the connected rotating shaft 7 . The lubricating oil 110 is stirred up by the rotation of the rotating disc 60 and supplied to the bearing 17 .

The partition wall 62 is fixed to the inner wall of the motor housing 14 and has a through hole (not shown) through which the rotating shaft 7 passes. The partition wall 62 is configured to separate the space where the lubricating oil 110 is stored and the space where the electric motor 8 is accommodated, and is provided to prevent the lubricating oil 110 from coming into contact with the electric motor 8 .

The lubricating oil 110 in the motor housing 14 is always in contact with the spacer 32 of the side cover 10A. If the heater 35 is disposed in the spacer 32 , the temperature of the lubricating oil 110 will rise due to the heat of the heater 35 , and the cooling effect on the bearing 17 may not be sufficiently obtained. Therefore, in the embodiment shown in FIG. 11 , the heater 35 is disposed in the side wall 31 of the side cover 10A.

The side cover 10A includes a side wall 31 that forms an end surface of the pump chamber 1 and a spacer 32 that holds the bearing 17 . The spacer 32 is connected to the side wall 31 and is located between the side wall 31 and the bearing housing 24 . The bearing housing 24 is held by the spacer 32 , and the bearing housing 24 is connected to the side wall 31 via the spacer 32 . The bearing 17 is connected to the spacer 32 via the bearing housing 24 . The spacer 32 holds the bearing 17 via the bearing housing 24 .

The side wall 31 is made of the same material as the rotating shaft 7 or a metal whose linear expansion coefficient is larger than that of the rotating shaft 7 . For example, when the rotating shaft 7 is made of cast iron, the side wall 31 is made of cast iron, or stainless steel, aluminum, aluminum alloy, or copper whose linear expansion coefficient is larger than that of cast iron. In one embodiment, the side wall 31 may also be made of the same material as the pump housing 2 and/or the spacer 32 , or a metal with a linear expansion coefficient larger than that of the pump housing 2 and/or the spacer 32 . composition.

When the heater 35 generates heat, the side wall 31 thermally expands, and the spacer 32 connected to the side wall 31 moves in the axial direction. Thereby, the bearing housing 24 and the bearing 17 held by the spacer 32 move in the axial direction, and the pump rotor 5E moves toward the side cover 10A. When the rotating pump rotor 5E moves toward the side cover 10A (end surface of the pump chamber 1 ), by-products accumulated in the gap between the pump rotor 5E and the side cover 10A can be scraped off little by little.

When the heat generation of the heater 35 stops, the temperature of the side wall 31 gradually decreases, and the side wall 31 gradually shrinks. As the side wall 31 contracts, the pump rotor 5E moves away from the side cover 10A, and the gap between the pump rotor 5E and the side cover 10A becomes larger. In the embodiment shown in FIG. 11 , similarly to the embodiment described with reference to FIGS. 3 and 4 , the heater 35 repeatedly generates heat and stops the heat generation, so that the rotating pump rotors 5A to 5E can scrape off accumulated deposits. By-products in pump chamber 1.

Figure 12 is a cross-sectional view showing still another embodiment of the vacuum pump device. The structure and operation of this embodiment that are not particularly described are the same as those of the embodiment described with reference to FIGS. 1 to 4 , and therefore repeated descriptions thereof are omitted. As shown in FIG. 12 , the pump casing 2 of this embodiment has casing side walls 70A and 70B that form end surfaces of the pump chamber 1 , and the pump casing 2 covers the entire pump chamber 1 . The pump chamber 1 is formed by the inner surface of the pump housing 2 . The side covers 10A and 10B are provided on both sides of the pump housing 2 and connected to the pump housing 2 . More specifically, the side wall 31 of the side cover 10A is connected to the housing side wall 70A of the pump housing 2 , and the side cover 10B is connected to the housing side wall 70B of the pump housing 2 . The rotating shaft 7 extends through the casing side walls 70A and 70B of the pump casing 2 .

The side cover 10A is provided with: a side wall 31 connected to the housing side wall 70A of the pump housing 2; and a spacer 32 made of the same material as the side wall 31 or a linear expansion coefficient larger than that of the side wall 31. Material composition. A spacer 32 is located between the side wall 31 and the bearing housing 24 . The bearing housing 24 is held by the spacer 32 , and the bearing housing 24 is connected to the side wall 31 via the spacer 32 . In this embodiment, the heater 35 is arranged in the spacer 32 of the side cover 10A. The embodiment shown in Figure 12 During the operation, the heater 35 repeatedly generates heat and stops generating heat, and the rotating pump rotors 5A to 5E can also scrape off the by-products accumulated in the pump chamber 1 .

FIG. 13 is a cross-sectional view showing still another embodiment of the vacuum pump device. In the vacuum pump device of this embodiment, as in the embodiment described with reference to FIG. 11 , lubricating oil 110 for lubricating and cooling the bearing 17 is stored at the bottom of the motor housing 14 . The structure and operation of this embodiment that are not particularly described are the same as those of the embodiment described with reference to FIG. 11 , and therefore repeated descriptions thereof will be omitted. As shown in FIG. 13 , the pump casing 2 of this embodiment has casing side walls 70A and 70B that form end surfaces of the pump chamber 1 , and the pump casing 2 covers the entire pump chamber 1 . The pump chamber 1 is formed by the inner surface of the pump housing 2 . The side covers 10A and 10B are provided on both sides of the pump housing 2 and connected to the pump housing 2 . More specifically, the side wall 31 of the side cover 10A is connected to the housing side wall 70A of the pump housing 2 , and the side cover 10B is connected to the housing side wall 70B of the pump housing 2 . The rotating shaft 7 extends through the casing side walls 70A and 70B of the pump casing 2 .

The side cover 10A includes a side wall 31 connected to the housing side wall 70A of the pump housing 2 and a spacer 32 that holds the bearing 17 . The side wall 31 is made of the same material as the rotating shaft 7 or a metal with a linear expansion coefficient larger than that of the rotating shaft 7 . In this embodiment, the heater 35 is arranged in the side wall 31 of the side cover 10A. In the embodiment shown in FIG. 13 , the heater 35 repeatedly generates heat and stops the heat generation, and the rotating pump rotors 5A to 5E can also scrape off by-products accumulated in the pump chamber 1 .

The above-described embodiments are described so that a person having ordinary knowledge in the technical field to which the present invention belongs can implement the present invention. Various modifications of the above-described embodiments can of course be implemented by those with ordinary knowledge in the technical field to which the present invention belongs, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but should be interpreted in the broadest scope based on the technical ideas defined by the claims.

1: Pump room

2: Pump housing

2b:Exhaust port

5E:Pump rotor

7:Rotation axis

10A: Side cover

14: Motor housing

17:Bearing

24:Bearing shell

31:Side wall

32: Spacer

35:Heater

36:next door

40: Heater control section

40a: Storage device

40b:Computing device

40c:Power supply

45: First temperature sensor

46: Second temperature sensor

100: By-products

Claims (26)

A vacuum pump device having: a pump housing having a pump chamber inside; A pump rotor, which is arranged in the aforementioned pump chamber; A rotating shaft on which the aforementioned pump rotor is fixed; An electric motor connected to the aforementioned rotating shaft; A bearing that rotatably supports the aforementioned rotating shaft; A side cover, which is connected to the aforementioned pump housing; A heater installed on the aforementioned side cover; and a heater control unit that causes the heater to generate heat intermittently while the pump rotor is rotating, The aforementioned bearing is connected to the aforementioned side cover. The vacuum pump device according to claim 1, wherein, The side cover forms an end surface of the pump chamber. The vacuum pump device according to claim 1, wherein, The pump housing forms an end surface of the pump chamber. The vacuum pump device according to claim 1, wherein, The aforementioned vacuum pump device further includes a bearing housing, which holds the aforementioned bearing. The bearing housing is held on the side cover. The vacuum pump device according to claim 2, wherein, The aforementioned side cover has: A side wall that forms the end face of the aforementioned pump chamber; and a spacer, which is made of the same material as the aforementioned side wall or a material with a linear expansion coefficient greater than that of the aforementioned side wall, The heater is arranged in the spacer. The vacuum pump device according to claim 2, wherein, The aforementioned side cover has: A side wall, which forms the end surface of the aforementioned pump chamber and is made of the same material as the aforementioned rotating shaft or a material whose linear expansion coefficient is larger than that of the aforementioned rotating shaft; and a spacer holding the aforementioned bearing, The heater is arranged in the side wall. The vacuum pump device according to claim 3, wherein, The aforementioned side cover has: A side wall connected to the aforementioned pump housing; and a spacer, which is made of the same material as the aforementioned side wall or a material whose linear expansion coefficient is larger than that of the aforementioned side wall, The heater is arranged in the spacer. The vacuum pump device according to claim 3, wherein, The aforementioned side cover has: A side wall, which is connected to the aforementioned pump housing and is made of the same material as the aforementioned rotating shaft or a material with a linear expansion coefficient larger than that of the aforementioned rotating shaft; and a spacer holding the aforementioned bearing, The heater is arranged in the side wall. The vacuum pump device as described in claim 1 also has: a first temperature sensor, the first temperature sensor is used to measure the temperature of the aforementioned pump housing; and a second temperature sensor, the second temperature sensor is used to measure the temperature of the aforementioned side cover, The heater control unit determines a target temperature based on the temperature of the pump housing and controls the heater so that the temperature of the side cover reaches the target temperature. The vacuum pump device according to claim 9, wherein, The heater control unit is configured to stop the heat generation of the heater or reduce the heat generation temperature of the heater after the temperature of the side cover reaches the target temperature. The vacuum pump device according to claim 1, wherein, It also has a displacement sensor, which is used to measure the axial displacement of the aforementioned bearing. The heater control unit is configured to stop heat generation by the heater when the axial displacement of the bearing reaches a threshold value. The vacuum pump device according to claim 1 further includes a second heater installed in the pump housing. The vacuum pump device according to claim 1 further includes a cooler mounted on the pump housing. A method of operating a vacuum pump device, wherein: The pump rotor arranged in the pump chamber of the pump casing is fixed to the rotating shaft, The aforementioned rotating shaft is rotatably supported by a bearing, The bearing is connected to the side cover connected to the pump housing, and causes the heater installed on the side cover to intermittently generate heat when the process gas is exhausted by the rotation of the pump rotor. The operating method of the vacuum pump device according to claim 14, wherein, The side cover forms an end surface of the pump chamber. The operating method of the vacuum pump device according to claim 14, wherein, The pump housing forms an end surface of the pump chamber. The operating method of the vacuum pump device according to claim 14, wherein, The aforementioned bearing is retained in the bearing housing, The bearing housing is held on the side cover. The operating method of the vacuum pump device according to claim 15, wherein, The aforementioned side cover has: A side wall that forms the end face of the aforementioned pump chamber; and a spacer, which is made of the same material as the aforementioned side wall or a material whose linear expansion coefficient is larger than that of the aforementioned side wall, The heater is arranged in the spacer. The operating method of the vacuum pump device according to claim 15, wherein, The aforementioned side cover has: A side wall, which forms the end surface of the aforementioned pump chamber and is made of the same material as the aforementioned rotating shaft or a material whose linear expansion coefficient is larger than that of the aforementioned rotating shaft; and a spacer holding the aforementioned bearing, The heater is arranged in the side wall. The operating method of the vacuum pump device according to claim 16, wherein, The aforementioned side cover has: A side wall connected to the aforementioned pump housing; and a spacer, which is made of the same material as the aforementioned side wall or a material whose linear expansion coefficient is larger than that of the aforementioned side wall, The heater is arranged in the spacer. The operating method of the vacuum pump device according to claim 16, wherein, The aforementioned side cover has: A side wall, which is connected to the aforementioned pump housing and is made of the same material as the aforementioned rotating shaft or a material with a linear expansion coefficient larger than that of the aforementioned rotating shaft; and a spacer holding the aforementioned bearing, The heater is arranged in the side wall. The operation method of the vacuum pump device as described in claim 14 also includes: The target temperature is determined based on the aforementioned temperature of the pump housing, The heater is controlled so that the temperature of the side cover reaches the target temperature. The operation method of the vacuum pump device as described in claim 22 also includes: After the temperature of the side cover reaches the target temperature, the heating of the heater is stopped or the heating temperature of the heater is lowered. The operation method of the vacuum pump device as described in claim 14 also includes: When the axial displacement of the bearing reaches a threshold value, the heating of the heater is stopped. The operation method of the vacuum pump device as described in claim 14 also includes: The pump housing is heated by a second heater installed on the pump housing. The operation method of the vacuum pump device as described in claim 14 also includes: The pump housing is cooled by a cooler installed on the pump housing.

Images